diff --git a/_index.db b/_index.db index 07381efd0..16ab54bd6 100644 Binary files a/_index.db and b/_index.db differ diff --git a/data/en.wikipedia.org/wiki/-bacter-0.md b/data/en.wikipedia.org/wiki/-bacter-0.md new file mode 100644 index 000000000..cf9cd9519 --- /dev/null +++ b/data/en.wikipedia.org/wiki/-bacter-0.md @@ -0,0 +1,38 @@ +--- +title: "-bacter" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/-bacter" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:49.425902+00:00" +instance: "kb-cron" +--- + +The suffix -bacter is used in microbiology for many genera and is intended to mean "bacteria". + + +== Meaning == + +Bacter is a Neo-Latin (i.e. Modern Latin) term coined from bacterium, which in turn derives from the Greek βακτήριον, meaning small staff (diminutive of βακτηρία). Consequently, it formally means "rod". +It differs from the suffix -bacterium in grammatical gender, as the suffix -bacter is male, whereas the suffix -bacterium) is neuter; this was decided in Juridical (or Judicial) Opinion n° 3 of the Bacteriological Code. +Nevertheless, for historical reasons, two archaeal species finish in -bacter: Methanobrevibacter and Methanothermobacter. + + +== Usage == + +Juridical Opinion n° 2 in the Bacteriological Code discusses the declension of the word, given that authors differently assumed the genitive case of bacter to be bactris (3rd declension words of Latin origin ending in =ter), bacteri (2nd declension) or bacteris (3rd declension, used for words of Greek origin, such as astris). The Opinion opts for the latter: consequently, higher taxa are formed with the stem =bacter- and not =bactr-. In Juridical Opinion n° 3 it was established to be masculine. +For example, Campylobacter is a genus of Campylobacterales. +These rules were established so that the specific epithets were paired with the correct gender as imposed by the Bacteriological Code and the correct higher taxon names were formed. +An interesting effect of this is that the genus Fibrobacter gives its name both to the phylum Fibrobacteres, which obeys Latin grammar, and to the class Fibrobacteria, which follows the recommendation of using the suffix -ia + + +== Genera == + + +== See also == +-monas +Bacteriological Code +bacterial taxonomy has a discussion of endings of Bacterial phyla + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/-monas-0.md b/data/en.wikipedia.org/wiki/-monas-0.md new file mode 100644 index 000000000..6c13a3139 --- /dev/null +++ b/data/en.wikipedia.org/wiki/-monas-0.md @@ -0,0 +1,35 @@ +--- +title: "-monas" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/-monas" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:50.635748+00:00" +instance: "kb-cron" +--- + +The suffix -monas is used in microbiology for many genera and is intended to mean "unicellular organism". + + +== Meaning == +The suffix -monas found in many genera in microbiology is similar in usage to -bacter, -bacillus, -coccus or -spirillum. The genera with the suffix are not a monophyletic group and the suffix is chosen over -bacter, often simply out of stylistic preferences to match with Greek words. +The first genus to be given the suffix -monas was Pseudomonas, a genus of gammaproteobacteria. The generic epithet Pseudomonas was coined by Walter Migula in 1894, who did not give an etymology. +Since the 7th edition of Bergey's manual (=top authority in bacterial nomenclature), other authors have given the etymology to be: Greek pseudēs (ψευδής, false) and monas (μονάς, single unit or monad), which can mean "false unit". However, "false unit" conceptually does not make much sense, namely, it does not mean "an organism which may falsely appear as a single unit but it is not" as it is not found in multicellular chains nor was it ever described as such. One speculation is that the name was chosen simply out of aesthetics, while the most plausible theory states that Migula intended it as false Monas, a nanoflagellate protist (Chrysophyceae: Ochromonadales: Ochromonadaceae: Chrysomonadida: Ochromonadidae). Subsequently, the term "monas" was used in the early history of microbiology to denote single-celled organisms. + + +== Grammar == + +In English to make a vernacular name for members of a genus, i.e. trivialising the scientific name, the scientific name is taken and written with sentence case and in roman type (i.e. "standard") as opposed to uppercase italic, the plurals are generally constructed by adding an "s", regardless of Greco-Roman grammar. In the case of genera ending in monas the ending is changed to monad with plural -monads. Example: a member of the genus Pseudomonas is a pseudomonad, while two are pseudomonads. The use of the stem for non-nominative cases is seen more often in botany, where trivialisation is more common, e.g. a bromeliad is a member of the genus Bromelia. + + +== Archaeal genera == + + +== Bacterial genera == + + +== See also == +-bacter + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/-onym-0.md b/data/en.wikipedia.org/wiki/-onym-0.md new file mode 100644 index 000000000..ea2bdeca0 --- /dev/null +++ b/data/en.wikipedia.org/wiki/-onym-0.md @@ -0,0 +1,17 @@ +--- +title: "-onym" +chunk: 1/4 +source: "https://en.wikipedia.org/wiki/-onym" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:53.225045+00:00" +instance: "kb-cron" +--- + +The suffix -onym (from Ancient Greek: ὄνυμα, lit. 'name') is a bound morpheme, that is attached to the end of a root word, thus forming a new compound word that designates a particular class of names. In linguistic terminology, compound words that are formed with suffix -onym are most commonly used as designations for various onomastic classes. Most onomastic terms that are formed with suffix -onym are classical compounds, whose word roots are taken from classical languages (Greek and Latin). +For example, onomastic terms like toponym and linguonym are typical classical (or neoclassical) compounds, formed from suffix -onym and classical (Greek and Latin) root words (Ancient Greek: τόπος / place; Latin: lingua / language). In some compounds, the -onym morpheme has been modified by replacing (or dropping) the "o". In the compounds like ananym and metanym, the correct forms (anonym and metonym) were pre-occupied by other meanings. Other, late 20th century examples, such as hypernym and characternym, are typically redundant neologisms, for which there are more traditional words formed with the full -onym (hyperonym and charactonym). +The English suffix -onym is from the Ancient Greek suffix -ώνυμον (ōnymon), neuter of the suffix ώνυμος (ōnymos), having a specified kind of name, from the Greek ὄνομα (ónoma), Aeolic Greek ὄνυμα (ónyma), "name". The form -ōnymos is that taken by ónoma when it is the end component of a bahuvrihi compound, but in English its use is extended to tatpuruṣa compounds. +The suffix is found in many modern languages with various spellings. Examples are: Dutch synoniem, German Synonym, Portuguese sinónimo, Russian синоним (sinonim), Polish synonim, Finnish synonyymi, Indonesian sinonim, Czech synonymum. +According to a 1988 study of words ending in -onym, there are four discernible classes of -onym words: (1) historic, classic, or, for want of better terms, naturally occurring or common words; (2) scientific terminology, occurring in particular in linguistics, onomastics, etc.; (3) language games; and (4) nonce words. Older terms are known to gain new, sometimes contradictory, meanings (e.g., eponym and cryptonym). In many cases, two or more words describe the same phenomenon, but no precedence is discernible (e.g., necronym and penthonym). New words are sometimes created, the meaning of which duplicating existing terms. On occasion, new words are formed with little regard to historical principles. + +== Words that end in -onym == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/-onym-1.md b/data/en.wikipedia.org/wiki/-onym-1.md new file mode 100644 index 000000000..8b09599dc --- /dev/null +++ b/data/en.wikipedia.org/wiki/-onym-1.md @@ -0,0 +1,29 @@ +--- +title: "-onym" +chunk: 2/4 +source: "https://en.wikipedia.org/wiki/-onym" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:53.225045+00:00" +instance: "kb-cron" +--- + +acronym: considered to be a "word" in its original sense formed from the initials of one or more words that is pronounceable like a normal word, such as NATO, sometimes in distinction to initialism; reflecting a historical development from its component word initials +agoronym: a name of a square or a marketplace. agronym: a name of a field or a plain. allonym: an author's name of another person — often, a well-known person's name; an alternative term for a pseudonym +anacronym: an acronym so well-established that its origin as an abbreviation is no longer widely known and its component initials are in danger of no longer being recognized (a blend of anachronism and acronym) +andronym: a male name, or a man's name adopted by a woman as a pseudonym. anonym: something created anonymously, or its creator; an unknown author; this term now generally replaced by pseudonym +anemonym: name of a hurricane or violent wind +anepronym: a portmanteau of anacronym and eponym; an original eponym of a trademark term that becomes so well established that it is used to define other objects that share its own definition (e.g., aspirin) +anthroponym: a proper name of a human being, individual or collective. anthropotoponym: a type of toponym (place name) that is derived from an anthroponym +antonym: a word with the exact opposite meaning of another word; an antithesis: often shown in opposite word pairs such as "high" and "low" (compare with "synonym") +apronym: a word which, as an acronym or backronym, has a meaning related to the meaning of the words constituting the acronym or backronym; such as PLATO for "Programmed Logic for Automated Teaching" alluding to Plato, the philosopher and teacher +aptronym: a name appropriate to its owner's occupation or physical properties, such as "Goldsmith" or "Longman" (compare with "charactonym") — coined by Franklin P. Adams +asteroidonym: a proper name of an asteroid. astionym: a name of a town or city. astronym: a name of a star (or more loosely of a constellation, or other heavenly body). autoethnonym: an ethnonym of endonymic (native) origin, created and used by an ethnic group as a self-designation (see also: endoethnonym). autoglossonym or autoglottonym: a glossonym / glottonym (language name) of endonymic (native) origin, created and used by native speakers as a designation for their language. autolinguonym: a linguonym (language name) of endonymic (native) origin, same as autoglossonym / autoglottonym (see also: endolinguonym). autonym: Botanical nomenclature for an automatically created name. Not to be confused with onomastic autonym, formerly used as a variant term for endonym. backronym: an ordinary word understood as an (usually amusing or ironic) acronym (a portmanteau of back + acronym), such as Fiat understood as "Fix It Again Tomorrow" +basionym: the first name published for a biological taxon (species, genus, etc.), which remains the defining name for the taxon even when the taxon has been transferred to a new name +caconym: a bad name, either from poor formation (as through mixing Greek and Latin) or unpleasantness (as through lengthiness or cacophony) +capitonym: a word that changes its meaning (and sometimes pronunciation) when it is capitalized, such as March and march or Polish and polish. charactonym: a name of a fictional character reflected in his personality traits, such as Shakespeare's Pistol or Bottom (compare with "aptronym") +choronym: a proper name of a region or a country. chrematonym: a proper name of a particular (unique) object, natural or artificially made. For example: Hope Diamond (proper name of a famous diamond), Bayeux Tapestry (proper name of a famous tapestry), or Wanamaker Organ (proper name of a famous musical instrument). chresonym: Biol. use of a taxonomic name; historically sometimes referred to as a synonym. Sometimes divided into orthochresonyms (correct usages) and heterochresonyms (names incorrectly applied). chrononym: a proper name of a time period, like the Bronze Age, or the Middle Ages. co-hyponym: a word that shares the same superordinate term as another word. For example: "lily" and "rose" are co-hyponyms in the superordinate category "flower." +cometonym: a proper name of a comet. comonym: a name of a village. contronym or antagonym or autoantonym: a word that may have opposite meanings in different contexts, such as cleave meaning "stick together" or "split apart" +cosmonym: a proper name of a cosmic feature, outside Earth. cryptonym: a code name; a word or name used clandestinely to refer to another name or word +demonym: a name, derived from a place name, for residents of that place (e.g., Utahn, from Utah, or Sioux Cityan, from Sioux City) — coined by George H. Scheetz, according to Paul Dickson in What Do You Call a Person From...? A Dictionary of Resident Names. The term first appeared in print in 1988 in Names' Names: A Descriptive and Prescriptive Onymicon by George H. Scheetz. See also taxonym. dromonym: a name of a road or any other communication or transport route by land, water or air. drymonym: a proper name of a wood or forest. ecclesiastonym: a name referring to members of a religious entity, e.g. Methodist, Protestant, Rastafarian, Wiccan (from Greek ekklisiastís 'churchgoer') +ecclesionym: a name of a church. endochoronym: a choronym (regional or country name) of endonymic (native) origin, created and used by native population as a designation for their region or country. endoethnonym: an ethnonym of endonymic (native) origin, created and used by an ethnic group as a self-designation (see also: autoethnonym). endolinguonym: a linguonym (language name) of endonymic (native) origin, created and used by native speakers as a designation for their language (see also: autolinguonym). endonym: a self-assigned name by locals of a place, or a group of people; formerly also known as autonym, but that term is polysemic (not to be confused with the autonym in botany). endotoponym: a type of toponym (place name) of endonymic (native) origin, created and used by native population as a designation for some toponymic feature in their homeland. eponym: a botanical, zoological, artwork, or place name that derives from a real or legendary person; a name for a real or hypothetical person from whom a botanical, geographical, artwork or zoological name is derived; a person after whom a medical condition is named, or the condition so named. A type of taxonym. ergonym: a name of an incorporated work-oriented entity, like a workshop, company or any firm in general. ethnochoronym: a choronym derived from an ethnonym. ethnohydronym: a hydronym that is formed from an ethnonym. ethnonym: a name of an ethnic group. ethnotoponym: a type of toponym that is formed from an ethnonym. exochoronym: a choronym (regional or country name) of exonymic (foreign) origin, created and used by those who don't belong to the native population of a referred territory. exoethnonym: an ethnonym of exonymic (foreign) origin, created and used as a designation for an ethnic group by those who do not belong to it. exolinguonym: a linguonym (language name) of exonymic (foreign) origin, created and used by those who are not native speakers of that language. exonym: a name used by one group of people for another group, but who call themselves by a different name, such as "Germans" for "Deutsche"; a place name used by one group that differs from the name used by the people who live there, such as "Cologne" for "Köln". \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/-onym-2.md b/data/en.wikipedia.org/wiki/-onym-2.md new file mode 100644 index 000000000..19e42dbde --- /dev/null +++ b/data/en.wikipedia.org/wiki/-onym-2.md @@ -0,0 +1,26 @@ +--- +title: "-onym" +chunk: 3/4 +source: "https://en.wikipedia.org/wiki/-onym" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:53.225045+00:00" +instance: "kb-cron" +--- + +exotoponym: a type of toponym (place name) of exonymic (foreign) origin, created and used by those who don't belong to the native population of a region in which the referred toponymic feature is located. gamonym: a name bestowed as a consequence of marriage. Judy Jones married Count Stephen Smith: her gamonyms include Mrs. Stephen Smith, Judy Smith, and Countess Smith. geonym: a name of a geographic feature, on Earth. glacionym: a name of a glacier. glossonym or glottonym: a name of a language +gynonym: a female name, or a woman's name adopted by a man as a pseudonym. hagionym: a name of a saint. hagiotoponym: a type of toponym (place name) derived from a hagionym (name of a saint). helonym: a name of a swamp, marsh, or bog. heterochresonym: (biological taxonomy) see chresonym. heteronym: a word that is spelled in the same way as another but that has a different sound and meaning, for example "bow" as in "bow of a ship" or "bow and arrow" (compare "homonym") +hodonym: a name of a street or road (also odonym). holonym: a word for the whole of which other words are part, in the way house contains roof, door and window; or car contains steering-wheel and engine (compare "meronym") +homonym: 1: a: a word pronounced like another, but differing in meaning or derivation or spelling—also known as a homophone (e.g. to, too, two). b: a word spelled like another, but differing in derivation or meaning or pronunciation—also known as a homograph or heteronym (lead, to conduct, and lead, the metal). Compare autantonym, contronym, and heteronym. c: a word spelled and pronounced like another, but differing in meaning (pool of water, and pool, the game). 2: a namesake. 3: Biol. a taxonomic designation that is identical to another one of the same rank, but based on a different type; only one of the homonyms is considered a valid designation (see homonym (biology)). Compare to synonym. hydronym: a name of river, lake, sea or any other body of water. hypernym: sometimes spelled hyperonym, a generic word that stands for a class or group of equally ranked items, such as "tree" for "beech" or "elm", or "house" for "chalet" or "bungalow". A hypernym is said to be "superordinate" to a hyponym. hypocoronym, hypocorism, or hypocoristic: a colloquial, usually unofficial, name of an entity; a pet-name or "nickname" +hyponym: an item that belongs to and is equally ranked in a generic class or group, for example "lily" or "violet" in the class of "flowers"; or "limousine" or "hatchback" in the class of "automobiles". A hyponym is said to be "subordinate" to a hyperonym. insulonym: a name of an island. isonym: 1: a word having the same root or stem as another — also known as paronym. Compare exonym, heteronym, paronym, and synonym. 2: one person's surname that is the same as another person's surname. 3: Biol. a taxonomic designation that is identical to another designation, and based on the same type, but published at a different time by the same or other authors (see isonym (taxonomy)). limnonym: a name of a lake or a pond. logonym: a polysemic term, with several meanings. linguonym: a name of a language +macrotoponym: a type of toponym that designates an important toponymic feature, that has a wider (regional, national, continental, global) significance. meronym: a word that names a part that belongs to and is therefore subordinate to a larger entity; a part-whole relationship, such as "door" or "window" in "house", or "engine" or "steering-wheel" in "car" (compare "holonym") +meteoronym: a proper name of a meteor. metonym: a word that substitutes a part for the whole it is associated with, for example "crown" for "monarch"; metonymy is the figure of speech incorporating a metonym +matronym or matronymic: a name of a human being making reference to that person's mother (contrast "patronym") +mononym: a word indicating the "single name" as generally applied to people e.g. Madonna or Plato. morphonym: a name of a taxonomic species. microtoponym: a type of toponym that is used locally, as designation for some toponymic feature that has only a local significance. necronym: a reference to or name of a person who has died. numeronym: is a number-based word. oceanonym: a name of an ocean. odonym: a name of a street or road (also hodonym). oikonym, also (Latinized) oeconym or econym: a name of a house or other building. oronym: 1: a name of a hill, mountain, or mountain-range; 2: a neologism for same-sounding (homophonic) words or phrases. orthonym: The correct word for a concept in a specified language. By extension in some religious and ideological cults, the one that appears in the database of the ideological or religious registry of name (such as the church or nationalist civil register). orthochresonym: (biological taxonomy) see chresonym. paedonymic: a name adopted from one's child's name, as in the kunya of Islamic names or when one is identified by means of one's child's name ("Tim's dad"). paronym: a word that is related to another word and derives from the same root; a cognate word, such as dubious and doubtful +patronym or patronymic: a name adopted from the father's or ancestor's name, for example "Johnson" from "John," "MacDonald" from "Donald," "O'Brien" from "Brien," or "Ivanovich" from "Ivan" +pelagonym: a name of a sea. phaleronym: a name of a medal, or any other honorary decoration. phantonym: a word that looks like it would mean one thing, when in reality it means something completely different. Such as "noisome" meaning "smelly" or "unhealthy" and not "noisy". phytonym: a name of an individual plant. planetonym: a proper name of a planet. plesionym or near-synonym: word that is almost synonymous with another word, but not quite +poetonym: a fictional or literary name +politonym: a name referring to members of a political entity +potamonym: a name of a river or a stream. prosoponym: a personal name; full name of an individual person. pseudonym: a false and fictitious name, especially one adopted by an author; a pen name +retronym: a compound or modified noun that replaces an original simple noun, for example "analog watch" now means what "watch" used to mean before the invention of the digital watch, and motorcycles became "solo motorcycles" when others were built with sidecars +speleonym: a name of a cave or some other subterranean feature. synonym: 1: a word equivalent in meaning or nearly so to another word; a word that may be substituted for another word that has the same or a similar meaning, such as near and close (compare "antonym"). 2: In Biology, one or more names given to the same taxon, and so considered equivalent. Usually, only one of them is considered as correct (senior synonym in animal taxonomy, accepted name in plant taxonomy), while the other are considered deprecated (see synonym (taxonomy)). \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/-onym-3.md b/data/en.wikipedia.org/wiki/-onym-3.md new file mode 100644 index 000000000..5d2c63b89 --- /dev/null +++ b/data/en.wikipedia.org/wiki/-onym-3.md @@ -0,0 +1,31 @@ +--- +title: "-onym" +chunk: 4/4 +source: "https://en.wikipedia.org/wiki/-onym" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:53.225045+00:00" +instance: "kb-cron" +--- + +tautonym: a binomial or scientific name in the taxonomy of living things in which the generic and specific names are the same, such as Gorilla gorilla; a scientific name in which the specific name is repeated, such as Homo sapiens sapiens as distinct from Homo sapiens neanderthalensis; a noun component that is repeated, such as aye-aye or tom-tom; a personal name where both forename and surname are identical, such as Francis Francis +taxonym: a name used for classification or identification purposes, usually signifying a relationship to something. Taxonyms include binomens, names of clades or taxas, demonyms, ethnonyms, and eponyms. Examples include canine, hominid, and Dryad. teknonym: a name that refers to a parent by the name of one of their children. textonym: a word that is generated by a single sequence of numerals keyed in to a mobile telephone; for example, 726 produces pam, ram, sam, and ran. Also called homonumeric words. theonym: a name of a god or a goddess. The names societies give their gods at times is useful in understanding the origin of their language as well as their view of a particular deity. Analysis of theonyms has been useful in understanding the connections of Indo-European languages, and possibly their religions, in particular. In Abrahamic faiths the origin and meaning of the Tetragrammaton is sometimes deemed to have important historical or even metaphysical meaning. theronym: a name — especially a product name — that has been derived from the name of an animal. topoanthroponym: an anthroponym that is derived from a toponym. topoethnonym: an ethnonym that is derived from a toponym. toponym: a place or geographical name; the name of an area of the body, as distinguished from the name of an organ +troponym: a verb conveying a meaning that is a particular case of the meaning of another verb. For example, to duel is a troponym of to fight; to write is a troponym of to communicate; etc. The concept of troponym is to verbs as that of hyponym is to nouns. urbanonym: a name of an urban element (street, square etc.) in towns and cities. zoonym: a name of an animal. + +== References == + +=== Citations === + +=== Sources === + +== Further reading == +Brown, A. F. (1963). Normal and Reverse English Word List. Vol. 1–8. Philadelphia: University of Pennsylvania. +Herbst, Richard C. (1979). Herbst's Backword Dictionary for Puzzled People. New York: Alamo Publishing Company. +Lehnert, Martin (1971). Reverse Dictionary of Present-Day English. Leipzig: Verlag Enzyklopädie. +Laurence Urdang, ed. (1981). -Ologies & -Isms: A Thematic Dictionary (2nd ed.). Detroit: Gale Research Company. + +== External links == + +Words That End In nym : Words That End With nym +Nym Words +Onyms \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/-phoresis-0.md b/data/en.wikipedia.org/wiki/-phoresis-0.md new file mode 100644 index 000000000..337e567b7 --- /dev/null +++ b/data/en.wikipedia.org/wiki/-phoresis-0.md @@ -0,0 +1,26 @@ +--- +title: "-phoresis" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/-phoresis" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:54.388999+00:00" +instance: "kb-cron" +--- + +The suffix -phoresis means "migration": + +Phoresis, where one organism attaches itself to another for travel. +Diffusiophoresis, motion observed in liquid environments where chemical gradients are generated by contact between solutions with different solute concentrations +Electrophoresis, motion of dispersed particles relative to a fluid under the influence of a spatially uniform electric field +Isotachophoresis, technique in analytical chemistry used to separate charged particles +Necrophoresis, disposal of bodies of dead members of their colony in social insects +Thermophoresis, phenomenon observed when a mixture of two or more types of motile particles (particles able to move) is subjected to the force of a temperature gradient and the different types of particles respond to it differently + + +== See also == +Apheresis ('taking away'), where a constituent of blood is separated out and the remainder returned to the circulation + + +== External links == + The dictionary definition of -phoresis at Wiktionary \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/-yllion-0.md b/data/en.wikipedia.org/wiki/-yllion-0.md new file mode 100644 index 000000000..5710572ae --- /dev/null +++ b/data/en.wikipedia.org/wiki/-yllion-0.md @@ -0,0 +1,158 @@ +--- +title: "-yllion" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/-yllion" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:56.940379+00:00" +instance: "kb-cron" +--- + +-yllion (pronounced ) is a proposal from Donald Knuth for the terminology and symbols of an alternate decimal superbase system. In it, he adapts the familiar English terms for large numbers to provide a systematic set of names for much larger numbers. In addition to providing an extended range, -yllion also dodges the long and short scale ambiguity of -illion. +Knuth's digit grouping is exponential instead of linear; each division doubles the number of digits handled, whereas the familiar system only adds three or six more. His system is basically the same as one of the ancient and now-unused Chinese numeral systems, in which units stand for 104, 108, 1016, 1032, ..., 102n, and so on (with an exception that the -yllion proposal does not use a word for thousand which the original Chinese numeral system has). Today the corresponding Chinese characters are used for 104, 108, 1012, 1016, and so on. + + +== Details and examples == + +In Knuth's -yllion proposal: + +1 to 999 still have their usual names. +1000 to 9999 are divided before the 2nd-last digit and named "foo hundred bar." (e.g. 1234 is "twelve hundred thirty-four"; 7623 is "seventy-six hundred twenty-three") +104 to 108 − 1 are divided before the 4th-last digit and named "foo myriad bar". Knuth also introduces at this level a grouping symbol (comma) for the numeral. So 382,1902 is "three hundred eighty-two myriad nineteen hundred two." +108 to 1016 − 1 are divided before the 8th-last digit and named "foo myllion bar", and a semicolon separates the digits. So 1,0002;0003,0004 is "one myriad two myllion, three myriad four." +1016 to 1032 − 1 are divided before the 16th-last digit and named "foo byllion bar", and a colon separates the digits. So 12:0003,0004;0506,7089 is "twelve byllion, three myriad four myllion, five hundred six myriad seventy hundred eighty-nine." +etc. +Each new number name is the square of the previous one — therefore, each new name covers twice as many digits. Knuth continues borrowing the traditional names changing "illion" to "yllion" on each one. +Abstractly, then, "one n-yllion" is + + + + + 10 + + + 2 + + n + + + 2 + + + + + + + {\displaystyle 10^{2^{n+2}}} + +. "One trigintyllion" ( + + + + + 10 + + + 2 + + 32 + + + + + + + {\displaystyle 10^{2^{32}}} + +) would have 232 + 1, or 42;9496,7297, or nearly forty-three myllion (4300 million) digits (by contrast, a conventional "trigintillion" has merely 94 digits — not even a hundred, let alone a thousand million, and still 7 digits short of a googol). Better yet, "one centyllion" ( + + + + + 10 + + + 2 + + 102 + + + + + + + {\displaystyle 10^{2^{102}}} + +) would have 2102 + 1, or 507,0602;4009,1291:7605,9868;1282,1505, or about 1/20 of a tryllion digits, whereas a conventional "centillion" has only 304 digits. +The corresponding Chinese "long scale" numerals are given, with the traditional form listed before the simplified form. Same numerals are used in the Ancient Greek numeral system, and also the Chinese "short scale" (new number name every power of 10 after 1000 (or 103+n)), "myriad scale" (new number name every 104n), and "mid scale" (new number name every 108n). Today these Chinese numerals are still in use, but are used in their "myriad scale" values, which is also used in Japanese and in Korean. For a more extensive table, see Myriad system. + + +== Latin- prefix == +In order to construct names of the form n-yllion for large values of n, Knuth appends the prefix "latin-" to the name of n without spaces and uses that as the prefix for n. For example, the number "latintwohundredyllion" corresponds to n = 200, and hence to the number + + + + + 10 + + + 2 + + 202 + + + + + + + {\displaystyle 10^{2^{202}}} + +. + + +== Negative powers == +To refer to small quantities with this system, the suffix -th is used. +For instance, + + + + + 10 + + − + 4 + + + + + {\displaystyle 10^{-4}} + + is a myriadth. + + + + + + 10 + + − + 16777216 + + + + + {\displaystyle 10^{-16777216}} + + is a vigintyllionth. + + +== See also == +Nicolas Chuquet – French mathematician (c.1445–c.1455 – c.1488–1500) +Jacques Pelletier du Mans – French humanist, poet, mathematician (1517–1582) +Knuth's up-arrow notation – Method of notation of very large integers +The Sand Reckoner – Work by Archimedes + + +== References == + +Donald E. Knuth. Supernatural Numbers in The Mathematical Gardener (edited by David A. Klarner). Wadsworth, Belmont, CA, 1981. 310—325. +Robert P. Munafo. The Knuth -yllion Notation ( Archived 2012-02-13 at the Wayback Machine 2012-02-25), 1996–2012. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Above_and_Beyond_(1952_film)-0.md b/data/en.wikipedia.org/wiki/Above_and_Beyond_(1952_film)-0.md new file mode 100644 index 000000000..2e15fffd8 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Above_and_Beyond_(1952_film)-0.md @@ -0,0 +1,58 @@ +--- +title: "Above and Beyond (1952 film)" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Above_and_Beyond_(1952_film)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:57.781437+00:00" +instance: "kb-cron" +--- + +Above and Beyond is a 1952 American World War II docudrama film directed by Melvin Frank and Norman Panama about Lt. Col. Paul W. Tibbets Jr., the pilot of the aircraft that dropped the atomic bomb on Hiroshima in August 1945. The film stars Robert Taylor as Tibbets and features a love story with Eleanor Parker as his wife. + + +== Plot == +Col. Paul W. Tibbets Jr. is assigned to a dangerous mission testing a new bomber, the Boeing B-29 Superfortress. The perilous assignment has caused his wife Lucy to worry for his life and whether their marriage can survive the constant separations. +After a year of scrutiny, Maj. Gen. Vernon C. Brent, who championed Tibbets as a test pilot, selects him to lead a new unit in the Pacific war flying the B-29, armed with a new secret weapon. Scientists of the Manhattan Project explain their secret weapon, the atomic bomb. Along with Maj. Bill Uanna, the only other person who knows what the mission will entail, Tibbets is expected to keep strict discipline over the personnel assigned to a B-29 conversion unit at Wendover Field, Utah. When families of crew members are brought to Wendover, tensions erupt between the Tibbetses over his secrecy concerning the mission. +T the B-29 designated for the Hiroshima bombing is named the Enola Gay and is flown to the Pacific island base of Tinian. After the bomb is dropped, Tibbets realizes the devastation that he has caused as he sees the flash and subsequent atomic blast. Back on Tinian, the crew is mobbed and although a second mission is mounted, it proves unnecessary with the end of the war after the bombing of Nagasaki. Tibbets returns home, flying first to Washington, where he has a joyous reunion with his wife. + + +== Cast == + + +== Production == +The film was suggested by screenwriter Beirne Lay Jr., a colonel in the Air Force Reserve, to General Curtis LeMay, commander of the Strategic Air Command (SAC). The men had previously discussed the high rate of divorce among flight crews and felt that a film depicting the problem might help raise morale. +Lay suggested a film based on the experiences of Colonel Paul Tibbets, commander of the 509th Composite Group during World War II. LeMay approved, and after writing an outline, Lay transferred scriptwriting duties to Melvin Frank and Norman Panama. Although Tibbets lent his full approval and support to the film, he felt that he was too closely involved to be objective and suggested Lt. Col. Charles F.H. Begg, commander of the nuclear-ordnance squadron, and Charles Sweeney, pilot of the Nagasaki bombing, as technical advisors. Begg, Major Norman W. Ray and Major James B. Bean served as USAF technical advisors. +The film was originally titled Eagle on His Cap. Studio principal photography began on February 5, 1952 before transferring to Davis–Monthan Air Force Base, which was predominantly utilized for the airfield scenes at Wendover Air Force Base, Boeing's Wichita testing area and Tinian. The production wrapped on March 26, 1952. +For dramatic effect, some incidents were somewhat exaggerated, such as the scene in which the Hiroshima bomb is armed mid-flight. The filmmakers added some turbulence to increase tension, although the actual flight was perfectly smooth throughout. In addition, the entire mission is depicted in daylight, although the actual takeoff from Tinian was in full darkness at 2:45 a.m. However, the scene in which Tibbets' wife summons a nuclear scientist from Los Alamos to repair a drain, believing him to be a janitor, is accurate. +Coproducer Norman Panama claimed that the system that he and Melvin Frank implemented for The Reformer and the Redhead (1950) by which all shots and dialogue were precisely planned and diagrammed, with suggestions welcomed from the cast and crew, saved $76,000 per day of production. +A sequel film focusing on the worries faced by wives of military aviators was contemplated but never materialized. + + +== Release == +Robert Taylor urged MGM to allow him to promote the film on television, and he appeared with Paul Tibbets on Ed Sullivan's Toast of the Town show, an unusual step at a time when the major studios disapproved of its stars appearing on television, which they saw as a threat. Although the studio was hesitant about the television appearance, the publicity gained was important to the film's initial success. + + +== Reception == +In a contemporary review for The New York Times, critic Bosley Crowther wrote:So long as attention is directed to the strictly technical activities of preparing for and delivering the mysterious atomic bomb, this tediously long and earnest picture has substance and plausibility ... But the long-drawn and intimate attention that the script writers and the picture give to the heartthrobs of Colonel and Mrs. Tibbets is a bit on the ostentatious side. Not only is it directed to make a lot out of ordinary things, such as the normal discomforts of a family at an Air Force base during the war, but it is carried beyond practical reason in ripping the couple apart. Although it is generously planted that they are rapturously in love, it is also assumed that they would split up over the colonel's deep absorption in his job.Critic Edwin Schallert of the Los Angeles Times, despite praising Tibbets as "a courageous individual who had a great respect for other men's lives", wrote: "Above and Beyond" might be charged with being too long, because it exceeds a full two hours by a couple of minutes. Shorter, it would have been somewhat more acceptable for the general public. However, for those who are interested in a well-documented feature with human interest, this screen event is unique.According to MGM records, the film earned $2,647,000 in the U.S. and Canada and $1,333,000 overseas, resulting in a profit of $1,037,000. + + +== Awards == +Above and Beyond was nominated for two Academy Awards: Best Original Motion Picture Story for Beirne Lay Jr. and Best Scoring of a Dramatic Picture for Hugo Friedhofer. + + +== References == + + +=== Citations === + + +=== Bibliography === + + +== External links == +Above and Beyond at IMDb +Above and Beyond at the TCM Movie Database (archived) +Above and Beyond at the AFI Catalog of Feature Films +Above and Beyond at Rotten Tomatoes +About the RCA811-K radio that gives Mrs. Tibbets the news about Hiroshima \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Anthropic_Bias-0.md b/data/en.wikipedia.org/wiki/Anthropic_Bias-0.md new file mode 100644 index 000000000..37ff47c21 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Anthropic_Bias-0.md @@ -0,0 +1,56 @@ +--- +title: "Anthropic Bias" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Anthropic_Bias" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:34.825537+00:00" +instance: "kb-cron" +--- + +Anthropic Bias: Observation Selection Effects in Science and Philosophy (2002) is a book by philosopher Nick Bostrom. It investigates how to reason when one suspects that evidence is biased by "observation selection effects"—when the evidence has been pre-filtered by the condition that some observer was appropriately positioned to "receive" it. This conundrum is sometimes called the "anthropic principle", "self-locating belief", or "indexical information". +The book first discusses the fine-tuned universe hypothesis and its possible explanations, notably considering the possibility of a multiverse. Bostrom argues against the self-indication assumption (SIA), a term he uses to characterize some existing views, and introduces the self-sampling assumption (SSA). He later refines SSA into the strong self-sampling assumption (SSSA), which uses observer-moments instead of observers to address certain paradoxes in anthropic reasoning. + + +== Self-sampling assumption == +The self-sampling assumption (SSA) states that: + +All other things equal, an observer should reason as if they are randomly selected from the set of all actually existent observers (past, present and future) in their reference class. +For instance, if there is a coin flip that on heads will create one observer and on tails will create two, then we have two possible worlds, one with one observer and one with two. These worlds are equally probable, so the SSA probability of being the first (and only) observer in the heads world is 1 ⁄2, that of being the first observer in the tails world is 1 ⁄2 × 1 ⁄2 = 1 ⁄4, and the probability of being the second observer in the tails world is also 1 ⁄4. +This is why SSA gives an answer of 1 ⁄2 probability of heads in the Sleeping Beauty problem. +Unlike SIA, SSA is dependent on the choice of reference class. If the agents in this example were in the same reference class as a trillion others, then the probability of being in the heads world upon the agent being told they are in the Sleeping Beauty problem is ≈ 1 ⁄3, similar to SIA. +SSA may imply the doomsday argument depending on the choice of reference class. +In Anthropic Bias, Bostrom suggests refining SSA to what he calls the strong self-sampling assumption (SSSA), which replaces "observers" in the SSA definition by "observer-moments". This coincides with the intuition that an observer who lives longer has more opportunities to experience existing, and provides flexibility to refine reference classes in certain thought experiments to avoid paradoxical conclusions. + + +== Self-indication assumption == +The self-indication assumption (SIA) is a philosophical principle defined in Anthropic Bias. It states that: + +All other things equal, an observer should reason as if they are randomly selected from the set of all possible observers. +Note that "randomly selected" is weighted by the probability of the observers existing: under SIA you are still unlikely to be an unlikely observer, unless there are many of them. +For instance, if there is a coin flip that on heads will create one observer and on tails will create two, we have three possible observers (1st observer on heads, 1st on tails, 2nd on tails). Each has an equal probability for existence, so SIA assigns 1 ⁄3 probability to each. Alternatively, this could be interpreted as saying there are two possible observers (1st observer on either heads or tails, 2nd observer on tails), the first existing with probability one and the second existing with probability 1 ⁄2, so SIA assigns 2 ⁄3 to being the first observer and 1 ⁄3 to being the second. This is the same as in the first interpretation. This is why SIA gives an answer of 1 ⁄3 probability of heads in the Sleeping Beauty problem. +Notice that, unlike SSA, SIA is not dependent on the choice of reference class, as long as the reference class is large enough to contain all subjectively indistinguishable observers. If the reference class is large, SIA will make it more likely, but this is compensated by the much reduced probability that the agent will be that particular agent in the larger reference class. +Although this anthropic principle was originally designed as a rebuttal to the doomsday argument (by Dennis Dieks in 1992), it has general applications in the philosophy of anthropic reasoning, and Ken Olum has suggested its importance to the analysis of quantum cosmology. +Bostrom argued against the SIA, as it would allow purely a priori reasoning to settle the scientific question of whether the universe is infinite/open rather than finite/closed. +Olum has written in defense of the SIA. Nick Bostrom and Milan Ćirković have critiqued his defense. +Matthew Adelstein has also defended the SIA, arguing that all alternatives imply the soundness of the doomsday argument and other even stranger conclusions. + + +== Reviews == +A review by Virginia Commonwealth University said the book "deserves a place on the shelf" of those interested in these subjects. + + +== See also == +Anthropic principle +Bayesian inference +Self-indication assumption doomsday argument rebuttal + + +== Notes == + + +== References == + + +== External links == +Anthropic Bias: Observation Selection Effects in Science and Philosophy (full text) \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Apollo_13_(film)-0.md b/data/en.wikipedia.org/wiki/Apollo_13_(film)-0.md new file mode 100644 index 000000000..3d1fdc67a --- /dev/null +++ b/data/en.wikipedia.org/wiki/Apollo_13_(film)-0.md @@ -0,0 +1,14 @@ +--- +title: "Apollo 13 (film)" +chunk: 1/7 +source: "https://en.wikipedia.org/wiki/Apollo_13_(film)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:59.048022+00:00" +instance: "kb-cron" +--- + +Apollo 13 is a 1995 American docudrama film directed by Ron Howard and starring Tom Hanks, Kevin Bacon, Bill Paxton, Gary Sinise, Ed Harris and Kathleen Quinlan. The screenplay by William Broyles Jr. and Al Reinert dramatizes the aborted 1970 Apollo 13 lunar mission and is an adaptation of the 1994 book Lost Moon: The Perilous Voyage of Apollo 13, by astronaut Jim Lovell and Jeffrey Kluger. +The film tells the story of astronauts Lovell, Jack Swigert, and Fred Haise aboard the ill-fated Apollo 13 for the United States' fifth crewed mission to the Moon, which was intended to be the third to land. En route, an on-board explosion deprives their spacecraft of much of its oxygen supply and electrical power, which forces NASA's flight controllers to abandon the Moon landing and improvise scientific and mechanical solutions to get the three astronauts to Earth safely. Howard went to great lengths to create a technically accurate movie, employing NASA's assistance in astronaut and flight-controller training for his cast and obtaining permission to film scenes aboard a reduced-gravity aircraft for realistic depiction of the weightlessness experienced by the astronauts in space. +Released in theaters by Universal Pictures in the United States on June 30, 1995, Apollo 13 received critical acclaim and was nominated for nine Academy Awards, including Best Picture (winning for Best Film Editing and Best Sound). The film also won the Screen Actors Guild Award for Outstanding Performance by a Cast in a Motion Picture, as well as two British Academy Film Awards. In total, the film grossed over $355 million worldwide during its theatrical releases and becoming the third-highest-grossing film of 1995. +It is listed in The New York Times Guide to the Best 1,000 Movies Ever Made (2004). In 2023, the film was selected for preservation in the United States National Film Registry by the Library of Congress as being "culturally, historically or aesthetically significant." \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Apollo_13_(film)-1.md b/data/en.wikipedia.org/wiki/Apollo_13_(film)-1.md new file mode 100644 index 000000000..ebb3fd032 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Apollo_13_(film)-1.md @@ -0,0 +1,53 @@ +--- +title: "Apollo 13 (film)" +chunk: 2/7 +source: "https://en.wikipedia.org/wiki/Apollo_13_(film)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:59.048022+00:00" +instance: "kb-cron" +--- + +== Plot == +On July 20, 1969, astronaut Jim Lovell hosts a party where guests watch Neil Armstrong's televised first steps on the Moon from Apollo 11. Lovell, who orbited the Moon on Apollo 8, tells his wife Marilyn that he will return to the Moon to walk on its surface. +Three months later, as Lovell is conducting a VIP tour of NASA's Vehicle Assembly Building, his boss Deke Slayton informs him that his crew will fly Apollo 13 instead of 14, swapping flights with Alan Shepard's crew. Lovell, Ken Mattingly, and Fred Haise train for their mission. Days before launch in April 1970, Mattingly is exposed to German measles, and the flight surgeon demands his replacement with Mattingly's backup, Jack Swigert. Lovell resists breaking up his team, but relents when Slayton threatens to bump his crew to a later mission. As the launch date approaches, Marilyn has a nightmare about her husband dying in space, and tells Lovell she will not go to Kennedy Space Center to see him off for an unprecedented fourth launch. She later changes her mind and surprises him. +On launch day, Flight Director Gene Kranz in Houston's Mission Control Center gives the go for launch. As the Saturn V rocket climbs through the atmosphere, a second stage engine cuts off prematurely, but the craft reaches its Earth parking orbit. After the third stage fires again to send Apollo 13 to the Moon, Swigert performs the maneuver to turn the Command Module Odyssey around to dock with the Lunar Module Aquarius and pull it away from the spent rocket. +Three days into the mission, by order of Mission Control, Swigert turns on the liquid oxygen stirring fans. An electrical short causes a tank to explode, emptying its contents into space and sending the craft tumbling. The other tank is soon found to be leaking. Consumables manager Sy Liebergot convinces Kranz that shutting off two of Odyssey's three fuel cells offers the best chance to stop the leak, but this does not work. With only one fuel cell, mission rules dictate the Moon landing be aborted. Lovell and Haise power up Aquarius to use as a "lifeboat", while Swigert shuts down Odyssey to save its battery power for the return to Earth. Kranz charges his team with bringing the astronauts home, declaring "failure is not an option". Consumables manager John Aaron recruits Mattingly to help him improvise a procedure to restart Odyssey for the landing on Earth. +As the crew watches the Moon pass beneath them, Lovell laments his lost dream of walking on its surface, then turns his crew's attention to the business of getting home. With Aquarius running on minimal electrical power and rationed water supply, the crew suffers from freezing conditions, and Haise develops a urinary tract infection. Swigert suspects Mission Control is concealing the fact they are doomed; Haise angrily blames Swigert's inexperience for the accident; but Lovell quashes the argument. As Aquarius's carbon dioxide filters run out, concentration of the gas approaches a dangerous level. Ground control improvises a "Rube Goldberg" device to make the Command Module's incompatible filter cartridges work in the Lunar Module. With Aquarius's navigation systems shut down, the crew makes a vital course correction manually by steering the Lunar Module and controlling its engine. +Mattingly and Aaron struggle to find a way to power up the Command Module systems without drawing too much power, and finally read the procedure to Swigert, who restarts Odyssey by drawing the extra power from Aquarius. When the crew jettisons the Service Module, they are surprised by the extent of the damage, raising the possibility that the ablative heat shield was compromised. As they release Aquarius and re-enter the Earth's atmosphere, no one is sure that Odyssey's heat shield is intact. The tense period of radio silence due to ionization blackout is longer than normal, but the astronauts report all is well, and the world watches Odyssey splash down and celebrates their return. +As helicopters bring the crew aboard the USS Iwo Jima for a hero's welcome, Lovell's voice-over describes the cause of the explosion, and the subsequent careers of Haise, Swigert, Mattingly, Kranz, and himself. He wonders if and when mankind will return to the Moon. + +== Cast == + +Apollo 13 crew: + +Tom Hanks as Commander Jim Lovell +Bill Paxton as Lunar Module Pilot Fred Haise +Kevin Bacon as backup Command Module Pilot Jack Swigert +Gary Sinise as prime Command Module Pilot Ken Mattingly, who was grounded shortly before the mission +Other astronauts: + +Mark Wheeler as Apollo 11 Commander Neil Armstrong +Larry Williams as Apollo 11 Lunar Module Pilot Buzz Aldrin +David Andrews as Apollo 12 Commander Pete Conrad +Ben Marley as Apollo 13 backup Commander John Young +Brett Cullen as capsule communicator (CAPCOM) 1 "Andy" (a composite astronaut, based on Jack R. Lousma and William Pogue) +Ned Vaughn as CAPCOM 2 (a composite astronaut) +NASA ground personnel: + +Ed Harris as White Team Flight Director Gene Kranz. +Chris Ellis as Director of Flight Crew Operations Deke Slayton +Joe Spano as NASA Director, a composite character loosely based on Manned Spacecraft Center director Christopher C. Kraft, Jr. +Marc McClure as Black Team Flight Director Glynn Lunney +Clint Howard as White Team Electrical, Environmental and Consumables Manager (EECOM) Sy Liebergot +Ray McKinnon as White Team Flight Dynamics Officer (FIDO) Jerry Bostick +Todd Louiso as White Team Flight Activities Officer (FAO) +Gabriel Jarret as White Team Guidance, Navigation, and Controls Systems Engineer (GNC) +Andy Milder as White Team Guidance Officer (GUIDO) +Jim Meskimen as White Team Telemetry, Electrical, EVA Mobility Unit Officer (TELMU) +Loren Dean as EECOM John Aaron +Christian Clemenson as Flight Surgeon Dr. Charles Berry +Carl Gabriel Yorke as SIM (Simulator) 1 +Xander Berkeley as Henry Hurt, a fictional NASA Office of Public Affairs staff member +Endre Hules as Günter Wendt, pad leader +Civilians: \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Apollo_13_(film)-2.md b/data/en.wikipedia.org/wiki/Apollo_13_(film)-2.md new file mode 100644 index 000000000..16325e2a9 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Apollo_13_(film)-2.md @@ -0,0 +1,44 @@ +--- +title: "Apollo 13 (film)" +chunk: 3/7 +source: "https://en.wikipedia.org/wiki/Apollo_13_(film)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:59.048022+00:00" +instance: "kb-cron" +--- + +Kathleen Quinlan as Marilyn Gerlach Lovell, Jim's wife +Jean Speegle Howard (Ron Howard's mother) as Blanche Lovell, Jim's mother +Mary Kate Schellhardt as Barbara Lovell, Jim's older daughter +Max Elliott Slade as James "Jay" Lovell, Jim's older son +Emily Ann Lloyd as Susan Lovell, Jim's younger daughter +Miko Hughes as Jeffrey Lovell, Jim's younger son +Rance Howard (Ron Howard's father) as the Lovell family minister +Tracy Reiner as Mary Haise, Fred's wife +Michele Little as Jane Conrad +Cameos: + +Jim Lovell appears as Captain Leland Kirkemo of the recovery ship USS Iwo Jima; Howard had intended to make him an admiral, but Lovell himself, having retired as a captain, chose to appear in his actual rank (and wearing his own Navy uniform). +Marilyn Lovell appears among the spectators during the launch sequence. +Jeffrey Kluger appears as a television reporter. +Horror film director Roger Corman, a mentor of Howard, appears as a congressman being given a VIP tour by Lovell of the Vehicle Assembly Building, as it had become something of a tradition for Corman to make a cameo appearance in his protégés' films. +CBS News anchor Walter Cronkite appears in archive news footage and can be heard in newly recorded announcements, some of which he edited himself to sound more authentic. +Cheryl Howard (Ron Howard's wife) and Bryce Dallas Howard (Ron Howard's eldest daughter) as uncredited background performers in the scene where the astronauts wave goodbye to their families. + +== Production == + +=== Development === +The movie rights to Jim Lovell's book Lost Moon were being shopped to potential buyers before it was written. He stated that his first reaction was that Kevin Costner would be a good choice to play him. + +=== Pre-production === +The original screenplay by William Broyles Jr. and Al Reinert was written with Costner in mind because of his facial similarities with Lovell. By the time Ron Howard acquired the director's position, Tom Hanks had expressed interest in doing a film based on Apollo 13. When Hanks' representative informed him that a script was being passed around he had it sent to him, and Costner's name never came up in serious discussion. Hanks was ultimately cast as Lovell because of his knowledge of Apollo and space history. +Because of his interest in aviation, John Travolta asked Howard for the role of Lovell, but was politely turned down. John Cusack was offered the role of Fred Haise but turned it down, and the role went to Bill Paxton. Brad Pitt was offered the role of Jack Swigert, but also turned it down in favor of Seven, so the role went to Kevin Bacon. Howard invited Gary Sinise to read for any of the characters, and Sinise chose Ken Mattingly. +After Hanks had been cast and construction of the spacecraft sets had begun, John Sayles rewrote the script. While planning the film, Howard decided that every shot would be original and that no mission footage would be used. The spacecraft interiors were constructed by the Kansas Cosmosphere and Space Center's Space Works, which also restored the Apollo 13 Command Module. Two individual Lunar Modules and two Command Modules were constructed for filming. Composed of some original Apollo materials, they were built so that different sections were removable, which allowed filming to take place inside them. Space Works also built modified Command and Lunar Modules for filming inside a Boeing KC-135 reduced-gravity aircraft, and the pressure suits worn by the actors, which are exact reproductions of those worn by the Apollo astronauts, right down to the detail of being airtight. When suited up with their helmets locked in place, the actors were cooled by and breathed air pumped into the suits, as in actual Apollo suits. +The Christopher C. Kraft Jr. Mission Control Center consisted of two control rooms on the second and third floors of Building 30 at the Johnson Space Center in Houston, Texas. NASA offered the use of the control room for filming, but Howard declined, opting instead to make his own replica. Production designer Michael Corenblith and set decorator Merideth Boswell were in charge of the construction of the Mission Control set at Universal Studios. It was equipped with giant rear-screen projection capabilities, and a complex set of computers with individual video feeds to all the flight controller stations. The actors playing the flight controllers could communicate with each other on a private audio loop. The Mission Control room built for the film was on the ground floor. One NASA employee, a consultant for the film, said the set was so realistic that he would leave at the end of the day and look for the elevator before he remembered he was not in Mission Control. The recovery ship USS Iwo Jima had been scrapped by the time the film was made, so her sister ship, New Orleans, was used instead. +To prepare for their roles in the film, Hanks, Paxton, and Bacon all attended the U.S. Space Camp in Huntsville, Alabama. While there, astronauts Jim Lovell and David Scott, commander of Apollo 15, did actual training exercises with the actors inside a simulated Command Module and Lunar Module. The actors were also taught about each of the 500 buttons, toggles, and switches used to operate the spacecraft. The actors then traveled to Johnson Space Center in Houston where they flew in the KC-135 to simulate weightlessness in outer space. +Each member of the cast performed extensive research for the project to provide an authentic story. Technical adviser Scott was impressed with their efforts, stating that each actor was determined to make every scene technically correct, word for word. +In Los Angeles, Ed Harris and all the actors portraying flight controllers enrolled in a Flight Controller School led by Gerry Griffin, an Apollo 13 flight director, and flight controller Jerry Bostick. The actors studied audiotapes from the mission, reviewed hundreds of pages of NASA transcripts, and attended a crash course in physics. +Reportedly, Pete Conrad expressed interest in appearing in the film. + +=== Filming === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Apollo_13_(film)-3.md b/data/en.wikipedia.org/wiki/Apollo_13_(film)-3.md new file mode 100644 index 000000000..aa9d890f2 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Apollo_13_(film)-3.md @@ -0,0 +1,38 @@ +--- +title: "Apollo 13 (film)" +chunk: 4/7 +source: "https://en.wikipedia.org/wiki/Apollo_13_(film)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:59.048022+00:00" +instance: "kb-cron" +--- + +Principal photography for Apollo 13 started in August 1994. +Howard anticipated difficulty in portraying weightlessness in a realistic manner. He discussed this with Steven Spielberg, who suggested filming aboard the KC-135 airplane, which can be flown in such a way as to create about 23 seconds of weightlessness, a method NASA has always used to train its astronauts for space flight. Howard obtained NASA's permission and assistance to obtain three hours and 54 minutes of filming time in 612 zero-g maneuvers. Filming in this environment was a time and cost saver because the stage recreation and computer graphics would have been expensive. The final three weeks of filming took place in the stages on the Universal Studios Lot in Universal City, California, where two life-size replicas of both the command module and the lunar module were built for simultaneous shooting on different soundstages. Air-cooling units lowered the temperatures inside each soundstage to around 38 °F (3 °C), to simulate the conditions necessary for condensation and the visibility of the actors' breath inside the spacecraft. Filming wrapped on February 25, 1995. The final scene to be filmed was the splashdown sequence at the film's conclusion, which was shot on a large, artificial lake on the Universal lot. + +==== Safety ==== +While filming in a 25-second burst of weightlessness was "charged and frenetic", the cast and crew only suffered from bumps and bruises, and most injuries occurred when they bumped on non-padded items. The cast and crew of Apollo 13 describe the weightlessness experience as being in a "vomit comet" and "roller coaster ride", but the motion sickness afflicted only a few members. +During filming of the low-temperature scenes in the Universal stages, signs that explained frostbite symptoms were posted on the stages' walls, and the crew worked in parkas. + +=== Post-production === +The visual effects supervisor was Robert Legato. +To avoid awkward visible switches to stock news footage in a live action film, he decided to produce the Saturn V launch sequence using miniature models and digital image stitching to create a panoramic background. On Howard's request to "shoot it like Martin Scorsese would shoot it", Legato studied Scorsese's scenes of pool games from The Color of Money, and copied his technique of creating a sense of rhythm by repeating two or three frames between each cut (just enough to be undetectable) for the engine ignition sequence. Legato says this scene inspired James Horner's soundtrack music for the launch. The long-range shot of the vehicle in flight was filmed using a $25 1:144 scale model Revell kit, with the camera realistically shaking, and it was digitized and re-filmed off of a high resolution monitor through a black filter, slightly overexposed to keep it from "looking like a video game". +The exhaust of the attitude control thrusters was generated with computer-generated imagery (CGI). This was also attempted to show the astronaut's urine dump into space, but wasn't high enough resolution to look right, so droplets sprayed from an Evian bottle were photographed instead. +The producers wanted to use CGI to render the splashdown, but Legato adamantly insisted this would not look realistic. Real parachutes were used with a prop capsule tossed out of a helicopter. +During weightless filming, all of the dialogue had been rendered unusable by the loudness of the plane. This required Hanks, Bacon and Paxton to attend ADR sessions, where they redubbed all of the lines for the weightless scenes. + +== Soundtrack == + +The score to Apollo 13 was composed and conducted by James Horner, and performed by the Hollywood Studio Symphony. The soundtrack was released in 1995 by MCA Records and has seven tracks of score, eight period songs used in the film, and seven tracks of dialogue by the actors at a total running time of nearly seventy-eight minutes. The music also features solos by vocalist Annie Lennox and Tim Morrison on the trumpet. The score was a critical success and garnered Horner an Academy Award nomination for Best Original Score. + +== Release == + +=== Theatrical === +Apollo 13 was released on June 30, 1995, in North America and on September 22, 1995, in the United Kingdom. +In September 2002 and for its 30th anniversary in September 2025, the film was re-released in IMAX. It is the first film to be digitally remastered using IMAX DMR technology. + +=== Home media === +Apollo 13 was released on VHS on November 21, 1995, and on LaserDisc the following week. On September 9, 1997, the film debuted on a THX certified widescreen VHS release. +A 10th-anniversary DVD of the film was released in 2005; it included both the original theatrical version and the IMAX version, along with several extras. The IMAX version has a 1.66:1 aspect ratio. +In 2006, Apollo 13 was released on HD DVD and on April 13, 2010, it was released on Blu-ray as the 15th-anniversary edition on the 40th anniversary of the Apollo 13 accident. The film was released on 4K UHD Blu-ray on October 17, 2017. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Apollo_13_(film)-4.md b/data/en.wikipedia.org/wiki/Apollo_13_(film)-4.md new file mode 100644 index 000000000..d0a74785d --- /dev/null +++ b/data/en.wikipedia.org/wiki/Apollo_13_(film)-4.md @@ -0,0 +1,26 @@ +--- +title: "Apollo 13 (film)" +chunk: 5/7 +source: "https://en.wikipedia.org/wiki/Apollo_13_(film)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:59.048022+00:00" +instance: "kb-cron" +--- + +== Box office == +Apollo 13 earned $25,353,380 from 2,347 theaters during its opening weekend, which made up 14.7% of the total US gross. Upon its opening, it was ranked number one at the box office, beating Pocahontas. Additionally, it surpassed Forrest Gump for having the largest opening weekend for a Tom Hanks film. Within five days, Apollo 13 generated $38.5 million, becoming the second-highest five-day opening of all time, behind Terminator 2: Judgment Day. The weekend of the film's opening earned $154 million from ticket sales, surpassing the previous record held by the combined Thanksgiving 1992 openings of Aladdin, The Bodyguard and Home Alone 2: Lost in New York. It would continue to stay in the number one spot for four weeks until it was dethroned by Waterworld. Earning $355,237,933, Apollo 13 was the third-highest-grossing film of 1995, behind Die Hard with a Vengeance and Toy Story (which also starred Hanks). +On September 19, 2025, Apollo 13 began a 30th anniversary re-release in IMAX screenings. As of September 21, 2025, the 2025 re-release has made $627,155 from screenings in 200 IMAX theaters. + +== Reception == +On the review aggregator website Rotten Tomatoes, 94% of 150 critics' reviews are positive. The website's consensus reads: "In recreating the troubled space mission, Apollo 13 pulls no punches: it's a masterfully told drama from director Ron Howard, bolstered by an ensemble of solid performances." Metacritic, which uses a weighted average, assigned the film a score of 78 out of 100, based on 22 critics, indicating "generally favorable" reviews. Audiences surveyed by CinemaScore gave the film an average grade of "A" on an A+ to F scale. + +=== Critical response === +Roger Ebert of the Chicago Sun-Times praised the film in his review, saying: "This is a powerful story, one of the year's best films, told with great clarity and remarkable technical detail, and acted without pumped-up histrionics." Richard Corliss of Time highly praised the film, saying: "From lift-off to splashdown, Apollo 13 gives one hell of a ride." Edward Guthmann of San Francisco Chronicle gave a mixed review and wrote: "I just wish that Apollo 13 worked better as a movie, and that Howard's threshold for corn, mush and twinkly sentiment weren't so darn wide." Peter Travers of Rolling Stone praised the film and wrote: "Howard lays off the manipulation to tell the true story of the near-fatal 1970 Apollo 13 mission in painstaking and lively detail. It's easily Howard's best film." +Janet Maslin made the film an NYT Critics' Pick, calling it an "absolutely thrilling" film that "unfolds with perfect immediacy, drawing viewers into the nail-biting suspense of a spellbinding true story." According to Maslin, "like Quiz Show, Apollo 13 beautifully evokes recent history in ways that resonate strongly today. Cleverly nostalgic in its visual style (Rita Ryack's costumes are especially right), it harks back to movie making without phony heroics and to the strong spirit of community that enveloped the astronauts and their families. Amazingly, this film manages to seem refreshingly honest while still conforming to the three-act dramatic format of a standard Hollywood hit. It is far and away the best thing Mr. Howard has done (and Far and Away was one of the other kind)." +The academic critic Raymond Malewitz focuses on the DIY aspects of the "mailbox" filtration system to illustrate the emergence of an unlikely hero in late 20th-century American culture—"the creative, improvisational, but restrained thinker—who replaces the older prodigal cowboy heroes of American mythology and provides the country a better, more frugal example of an appropriate 'husband'." +Marilyn Lovell praised Quinlan's portrayal of her, stating she felt she could feel what Quinlan's character was going through, and remembered how she felt in her mind. + +== Accolades == + +== Technical and historical accuracy == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Apollo_13_(film)-5.md b/data/en.wikipedia.org/wiki/Apollo_13_(film)-5.md new file mode 100644 index 000000000..844e85ee7 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Apollo_13_(film)-5.md @@ -0,0 +1,21 @@ +--- +title: "Apollo 13 (film)" +chunk: 6/7 +source: "https://en.wikipedia.org/wiki/Apollo_13_(film)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:59.048022+00:00" +instance: "kb-cron" +--- + +In the film, Lovell tells his wife he was given command of Apollo 13 instead of 14 because original commander Alan Shepard's "ear infection is flaring up again"; in fact, Shepard had no "ear infection"; he had been grounded since 1963 by Ménière's disease. This was surgically corrected four years later and he was returned to flight duty in May 1969; Manned Spacecraft Center management felt he needed more training time for a lunar mission. +The film portrays the Saturn V launch vehicle being rolled out to the launch pad two days before launch. In reality, the launch vehicle was rolled out on the Mobile Launcher using the crawler-transporter two months before the launch date. +The film depicts the crew hearing a bang shortly after Swigert followed directions from mission control to stir the oxygen and hydrogen tanks. In reality, the crew heard the bang 95 seconds later. +The film depicts Sy Liebergot suggesting that the oxygen leak was in one or two of Odyssey's fuel cells, and the order to shut them down was passed up to the crew, forcing abort of the lunar landing mission. In reality, Mission Control did not order the shutdown; Haise found the cells were already dead, because of starvation due to the damage to the oxygen system. +The film depicts Swigert and Haise arguing about who was at fault. The show The Real Story: Apollo 13 broadcast on the Smithsonian Channel includes Haise stating that no such argument took place and that there was no way anyone could have foreseen that stirring the tank would cause problems. Similarly on the BBC 13 Minutes to the Moon program, backup lunar module pilot on the mission Charles Duke says the film portrayed Swigert as unprepared for the flight, but it was untrue and that Swigert was very familiar with the Command Module as he had been involved with the development of it during his time as an engineering test pilot at North American Aviation, prior to becoming an astronaut. +The dialogue between ground control and the astronauts was taken nearly verbatim from transcripts and recordings, with the exception of one of the taglines of the film, "Houston, we have a problem." (This quote was voted #50 on the list "AFI's 100 Years... 100 Movie Quotes".) According to audio of the air-to-ground communications, the actual words uttered by Swigert were "Okay, Houston, we've had a problem here". Ground control responded by saying, "This is Houston. Say again, please." Jim Lovell then repeated, "Houston, we've had a problem." +One other incorrect dialogue is after the re-entry blackout. In the film, Tom Hanks (as Lovell) says "Hello Houston... this is Odyssey... it's good to see you again." In the actual re-entry, the Command Module's transmission was finally acquired by a Sikorsky SH-3D Sea King recovery helicopter which then relayed communications to Mission Control. CAPCOM astronaut Joe Kerwin (not Mattingly, who serves as CAPCOM in this scene in the film) then made a call to the spacecraft "Odyssey, Houston standing by. Over." Swigert, not Lovell, replied "Okay, Joe," and unlike the film, this was well before the parachutes deployed; the celebrations depicted at Mission Control were triggered by visual confirmation of their deployment. +The tagline "Failure is not an option", stated in the film by Gene Kranz, also became very popular, but was not taken from the historical transcripts. The following story relates the origin of the phrase, from an e-mail by Apollo 13 Flight Dynamics Officer Jerry Bostick: + +As far as the expression "Failure is not an option," you are correct that Kranz never used that term. In preparation for the movie, the script writers, Al Reinart and Bill Broyles, came down to Clear Lake to interview me on "What are the people in Mission Control really like?" One of their questions was "Weren't there times when everybody, or at least a few people, just panicked?" My answer was "No, when bad things happened, we just calmly laid out all the options, and failure was not one of them. We never panicked, and we never gave up on finding a solution." I immediately sensed that Bill Broyles wanted to leave and assumed that he was bored with the interview. Only months later did I learn that when they got in their car to leave, he started screaming, "That's it! That's the tag line for the whole movie, Failure is not an option. Now we just have to figure out who to have say it." Of course, they gave it to the Kranz character, and the rest is history. +In the film, Flight Director Gene Kranz and his White Team are portrayed as managing all of the essential parts of the flight, from liftoff to landing. Consequently, the actual role of the other flight directors and teams, especially Glynn Lunney and his Black Team, were neglected. In fact, it was Flight Director Lunney and his Black Team who got Apollo 13 through its most critical period in the hours immediately after the explosion, including the mid-course correction that sent Apollo 13 on a "free return" trajectory around the Moon and back to the Earth. Astronaut Ken Mattingly, who was replaced as Apollo 13 Command Module Pilot at the last minute by Swigert, later said: \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Apollo_13_(film)-6.md b/data/en.wikipedia.org/wiki/Apollo_13_(film)-6.md new file mode 100644 index 000000000..7b6da9d6a --- /dev/null +++ b/data/en.wikipedia.org/wiki/Apollo_13_(film)-6.md @@ -0,0 +1,36 @@ +--- +title: "Apollo 13 (film)" +chunk: 7/7 +source: "https://en.wikipedia.org/wiki/Apollo_13_(film)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:59.048022+00:00" +instance: "kb-cron" +--- + +If there was a hero, Glynn Lunney was, by himself, a hero, because when he walked in the room, I guarantee you, nobody knew what the hell was going on. Glynn walked in, took over this mess, and he just brought calm to the situation. I've never seen such an extraordinary example of leadership in my entire career. Absolutely magnificent. No general or admiral in wartime could ever be more magnificent than Glynn was that night. He and he alone brought all of the scared people together. And you've got to remember that the flight controllers in those days were—they were kids in their thirties. They were good, but very few of them had ever run into these kinds of choices in life, and they weren't used to that. All of a sudden, their confidence had been shaken. They were faced with things that they didn't understand, and Glynn walked in there, and he just kind of took charge. +A DVD commentary track, recorded by Jim and Marilyn Lovell and included with the Signature Laserdisc and later included on both DVD versions, mentions several inaccuracies included in the film, all done for reasons of artistic license: + +In the film, Mattingly plays a key role in solving a power consumption problem that Apollo 13 faced as it approached re-entry. Lovell points out in his commentary that this was actually a composite of several astronauts and engineers—including Charles Duke (whose rubella led to Mattingly's grounding)—all of whom worked to solve that problem. +When Swigert is getting ready to dock with the LM, a concerned NASA technician says: "If Swigert can't dock this thing, we don't have a mission." Lovell and Haise also seem worried. In his DVD commentary, the real Jim Lovell says that if Swigert had been unable to dock with the LM, he or Haise could have done it. He also says that Swigert was a well-trained Command Module Pilot, and no one was really worried about whether he was up to the job, but he admitted that it made a nice subplot for the film. What the astronauts were really worried about, Lovell says, was the expected rendezvous between the Lunar Module and the Command Module after Lovell and Haise left the surface of the Moon. +A scene set the night before the launch, showing the astronauts' family members saying their goodbyes while separated by a road, to reduce the possibility of any last-minute transmission of disease, depicted a tradition that did not begin until the Space Shuttle program. +The film depicts Marilyn Lovell accidentally dropping her wedding ring down a shower drain. According to Jim Lovell, this did occur, but the drain trap caught the ring and his wife was able to retrieve it. Lovell has also confirmed that the scene in which his wife had a nightmare about him being "sucked through an open door of a spacecraft into outer space" also occurred, though he believes the nightmare was prompted by her seeing a scene in Marooned, a 1969 film they saw three months before Apollo 13 launched. +When the three astronauts are putting on their spacesuits, the NASA "worm" logo can be clearly seen on the glass behind Kevin Bacon, but that logo did not start to be used until 1975. + +== See also == +From the Earth to the Moon, a 1998 docudrama mini-series based around the Apollo missions +Gravity, a 2013 film about astronauts stranded in Earth orbit +Survival film +1970s nostalgia + +== References == + + This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration. + +== External links == + +Apollo 13 at IMDb +Apollo 13 at the TCM Movie Database (archived) +Apollo 13 at the AFI Catalog of Feature Films +Apollo 13 at Rotten Tomatoes +Apollo 13 at Box Office Mojo \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Bloggingheads.tv-0.md b/data/en.wikipedia.org/wiki/Bloggingheads.tv-0.md new file mode 100644 index 000000000..365b2ebcc --- /dev/null +++ b/data/en.wikipedia.org/wiki/Bloggingheads.tv-0.md @@ -0,0 +1,22 @@ +--- +title: "Bloggingheads.tv" +chunk: 1/2 +source: "https://en.wikipedia.org/wiki/Bloggingheads.tv" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:02.676059+00:00" +instance: "kb-cron" +--- + +Bloggingheads.tv, sometimes abbreviated "bhtv", is a political, world events, philosophy, and science video blog discussion site in which the participants take part in a back and forth conversation via webcam broadcast online to viewers. The site operated as a project of the Nonzero Foundation since 2012, but the site was started by the journalist and author Robert Wright and blogger and journalist Mickey Kaus on November 1, 2005. Kaus has since dropped out of operational duties of the site as he didn't want his frequent linking to be seen as a conflict of interest. +Most of the earlier discussions posted to the site involved one or both of those individuals, but since has grown to include a total of over one thousand individual contributors, mostly journalists, academics, scientists, authors, well known political bloggers, and other notable individuals. Unregistered users are able to view all of the videos which are contained on the site, while free registration is required to comment on the individual discussions, or participate in the forums. In April 2022, Wright announced that Bloggingheads will be ending, stating that "the era in which Bloggingheads makes sense is kinda over," however the site currently continues to operate. + +== Format == +Bloggingheads discussions are conducted via webcam between two (or more) people, and can be viewed online in Flash format, or downloaded as WMV video files, MP4 video files, or MP3 sound files. New diavlogs are generally posted daily, and are all archived for future viewing. The diavlogs are generally broken up into a series of topics and subtopics a few minutes in length, links to which are placed below the video window to allow viewers to navigate to a given topic if they do not wish to view the whole discussion. +Most of the discussions posted to Bloggingheads.tv involve well known (or semi-well known) journalists, bloggers, science writers, scientists, philosophers, book authors, or other specialists in segments of current world events. Many of the discussions are of a political nature or are related to the current political environment. Those with differing points of view are often matched against one another. Diavlogs involving guests appearing for the first time often take the form of an interview, more often than that of a discussion, with a longtime Bloggingheads contributor playing the role of interviewer. + +=== Regular segments === + +Although most episodes and matchups do not occur on any kind of a regular basis, there are a few notable exceptions to this. There is a frequent diavlog matchup between the two co-founders of Bloggingheads.tv, Robert Wright and Mickey Kaus, generally related to politics in some form, that usually occurs on either Wednesday or Thursday. While some of the other diavloggers are frequently matched against each other (e.g. David Corn & James Pinkerton) there is usually not a regularly scheduled time at which they take place. +"Science Saturday" was the name given to the weekly episode appearing on Saturday that was always science related. Its last episode was released on December 24, 2011. It usually (but not always) involved either one or both of the science writers John Horgan and George Johnson. Many well-known people in the science community were a part of Science Saturday, including Michael Shermer of Skeptic Magazine, biologist PZ Myers, Craig Venter of the Human Genome Project, aging researcher and biogerentologist Aubrey de Grey, and philosopher David Chalmers, among many others. However, in September 2009, four high-profile science bloggers who had previously participated in Bloggingheads.tv discussions publicly distanced themselves from the site and stated they would no longer agree to appear in Bloggingheads.tv segments. The scientists – Sean Carroll, Carl Zimmer, Phil Plait and PZ Myers – all criticized what they claimed was a policy by Bloggingheads.tv to provide a platform for the anti-scientific ideology of creationism without an opposing point of view for balance. PZ Myers said: "[Bloggingheads.tv] was setting up crackpots with softball interviews that made them look reasonable, because their peculiar ideas were never confronted." +"The Week in Blog" was a weekly segment which normally appeared on the site on Fridays. Its last episode was released on March 7, 2012. The format was to discuss what has showed up on the past week on both liberal and conservative blogs, from both a liberal and conservative viewpoint. The three regular hosts of "TWIB" were Bill Scher of Liberal Oasis, Kristin Soltis of the Winston Group, and Matt Lewis of The Daily Caller. Original host Conn Carroll of The Heritage Foundation stepped aside in early 2009. Guests who appeared on the show are Armando Llorens (of Daily Kos), Amanda Carpenter, and Nate Silver (of FiveThirtyEight) among many others. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Bloggingheads.tv-1.md b/data/en.wikipedia.org/wiki/Bloggingheads.tv-1.md new file mode 100644 index 000000000..867851238 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Bloggingheads.tv-1.md @@ -0,0 +1,38 @@ +--- +title: "Bloggingheads.tv" +chunk: 2/2 +source: "https://en.wikipedia.org/wiki/Bloggingheads.tv" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:02.676059+00:00" +instance: "kb-cron" +--- + +== History == +On November 1, 2005, the site launched, with Robert Wright and Mickey Kaus as the only two initial participants in the video discussions. The site has since featured more than one thousand other diavloggers. On October 18, 2006, a site redesign was launched, with a revised home page and improved functionality: ability to comment on diavlogs was added, and to participate in forum discussions. +In January 2007, it was announced that cable TV pioneer and C-SPAN founding chairman Bob Rosencrans, with a loose network of others, would become an angel investor of Bloggingheads.tv. The infusion of cash kicked off a dramatic expansion of the site's content, and a corresponding growth in viewers. On March 24, 2007, in a diavlog between Garance Franke-Ruta and Ann Althouse, Althouse became quite animated and angry (to the point of yelling) over a comment Franke-Ruta made (in reference to an earlier controversy involving Jessica Valenti and former US president Bill Clinton) referred to as an on-air "meltdown" by some. This led to many blog posts and news stories in the following days on both the initial controversy and Althouse's on air behavior. +On October 24, 2007, Bloggingheads.tv entered into a relationship with The New York Times, whereby selected video segments from the Bloggingheads site would appear in the "Videos" section on the Times website, under the Opinion subsection. In 2008, several new segments and diavloggers were added or made more regular, including "Free Will", "This Week in Blog", and "UN Plaza". Other updates and tweaks to the site, such as the addition of the MP4 video format were also gradually phased in. In April 27, 2022, during an appearance on "the DMZ," Wright announced that Bloggingheads will be ending, with the remaining segments moving to their own independent platforms. + +=== Media recognition === +Traditional media outlets, such at The New York Times and others, have written mostly favorable reviews of Bloggingheads.tv. Stories are also often written about individuals who take part in the video discussions, as they are often well known individuals in the scientific, academic, journalism, or blogosphere community. Some events and personality appearances on Bloggingheads.tv have led to larger than usual amounts of media coverage, such as the March 24, 2007 Ann Althouse controversy described above, and the appearance of Andrew Sullivan on December 26, 2006 and January 1, 2007, when he discussed in the most clear terms up to that point his reversal of viewpoint on the Iraq War, and his plea of apology for supporting it in the first place. + +== Contributors to Bloggingheads.tv == +Apart from the regular contributors, a host of well known occasional guests have appeared, usually in the form of being interviewed. Among others, the political scientist Francis Fukuyama talked about his book America at the Crossroads; the Israeli journalist Gershom Gorenberg discussed his book The Accidental Empire (about the history of the settlements); The Washington Post columnist Joel Achenbach on an article of his about global warming deniers (among other topics); Andrew Sullivan on his book The Conservative Soul; biogerentologist Aubrey de Grey on how to defeat the "disease" of aging; philosopher David Chalmers; Nate Silver (of FiveThirtyEight.com); and Craig Venter, director of the Human Genome Project, who spoke of future scientific innovations he is currently pursuing. + +== See also == +Digital television +Interactive television +Podcast +Political podcast +MSN TV +Streaming television +Video on demand +Webcast + +== References == + +== External links == +Official website +New York Times Article on the operation of Bloggingheads.tv +Associated Press article in the NY Sun on the BloggingHeads.tv setup Archived August 11, 2022, at the Wayback Machine +Business Week article on Bloggingheads.tv \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Blue_Mind-0.md b/data/en.wikipedia.org/wiki/Blue_Mind-0.md new file mode 100644 index 000000000..467c724d1 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Blue_Mind-0.md @@ -0,0 +1,32 @@ +--- +title: "Blue Mind" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Blue_Mind" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:36.032379+00:00" +instance: "kb-cron" +--- + +Blue Mind: The Surprising Science That Shows How Being Near, In, On, Or Under Water Can Make You Happier, Healthier, More Connected, and Better at What You Do is a bestselling book by marine biologist Wallace J. Nichols about the effects bodies of water have on human health and well-being. + + +== Contents == +The book covers "therapeutic landscapes" as they are referred to in medical literature, specifically ones that are near, in, or on the water. The book analyzes studies that suggest living or simply being near bodies of water can have powerful psychological and even physiological effects. + + +=== Human condition === +Blue Mind considers the impact of water on the human condition and mental health. Author Wallace Nichols told Quartz: + +People can experience the benefits of the water whether they're near the ocean, a lake, river, swimming pool or even listening to the soothing sound of a fountain. Most communities are built near bodies of water not just for practical reasons, but because as humans, we're naturally drawn to blue space...but even if you aren't in an area where there is easy access to water, you can still experience [its] emotional benefits. Many scribes, poets, painters, and sailors have attested to the feeling of wellness and peace that comes over them when they're in, or near, bodies of water. + + +=== Research === +Blue Mind compiles and analyzes recent scientific research that has shown water's favorable cognitive and physical impacts being quantified by experts. The book shows proof that living near the shore, for example, has been shown to boost physical health and well-being. It also provides evidence that water generates a meditative state, which makes us happier, healthier, calmer, and more creative. + + +== Reception == +The book was received well by critics, and made The New York Times Best Seller list. A review from The Guardian labeled Blue Mind "popular psychology", calling it "a study in water and why it makes us happy". A review from the Association for the Sciences of Limnology and Oceanography said "Blue Mind is an interesting read and presents a different perspective on water than we typically think about during the course of our hectic days." + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Blueprint_for_Disaster-0.md b/data/en.wikipedia.org/wiki/Blueprint_for_Disaster-0.md new file mode 100644 index 000000000..80d054e96 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Blueprint_for_Disaster-0.md @@ -0,0 +1,36 @@ +--- +title: "Blueprint for Disaster" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Blueprint_for_Disaster" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:02.771652+00:00" +instance: "kb-cron" +--- + +Blueprint for Disaster is a Canadian documentary television series that premiered in 2004 on Discovery Channel Canada. Produced by Temple Street Productions, the program investigates why and how various disasters have happened. Toronto-based Voice Artist Adrian Bell provided the narration for the first series. As of 2008, two seasons have been produced. + + +== Episodes == + + +=== Season 1 === + + +=== Season 2 === + + +== See also == +Seconds from Disaster +Seismic Seconds +Mayday +Trapped + + +== References == + + +== External links == +Official website at the Wayback Machine (archived September 30, 2005) by the Discovery Channel +Temple Street Productions +Blueprint for Disaster at IMDb \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Brain_Blogger-0.md b/data/en.wikipedia.org/wiki/Brain_Blogger-0.md new file mode 100644 index 000000000..9a5791bff --- /dev/null +++ b/data/en.wikipedia.org/wiki/Brain_Blogger-0.md @@ -0,0 +1,20 @@ +--- +title: "Brain Blogger" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Brain_Blogger" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:03.982473+00:00" +instance: "kb-cron" +--- + +Brain Blogger is a Scientific American partner biomedical blog sponsored by the Global Neuroscience Initiative Foundation (GNIF) and edited by Shaheen Lakhan. Its byline is "a brain-themed community." It reviews the latest news and stories related to neuroscience/neurology, psychology/psychiatry, and health/healthcare. +According to its website, the blog is written by over 100 biomedical professionals—from neurosurgeons to psychologists—and follows the Health On the Net Foundation honor code of medical blogging ethics. It is syndicated by Google News and major media outlets, including Time Warner, San Antonio Express-News, and Sun-Times News Group. +Brain Blogger is a finalist for two Seed Media Group's Research Blogging Awards 2010 in the categories "Best Blog — Neuroscience" and "Best Blog — Psychology". Moreover, it ranks first in Blogs.com's "10 Best Brain Blogs". + + +== References == + + +== External links == +Official website \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Challenger_(1990_film)-0.md b/data/en.wikipedia.org/wiki/Challenger_(1990_film)-0.md new file mode 100644 index 000000000..91a267757 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Challenger_(1990_film)-0.md @@ -0,0 +1,38 @@ +--- +title: "Challenger (1990 film)" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Challenger_(1990_film)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:07.293372+00:00" +instance: "kb-cron" +--- + +Challenger is a 1990 American disaster drama television film based on the events surrounding the Space Shuttle Challenger disaster in 1986. Its production was somewhat controversial as the families of the astronauts generally objected to it. A prologue states that the film was "researched with the consultation of the National Aeronauts and Space Administration" and partly filmed at NASA's Johnson Space Center in Houston, Texas. + + +== Plot == +The film concentrates on the safety inspections and arguments surrounding the O-rings that ultimately were blamed for the explosion of Challenger. While doing this, it also aims to show the personal humanity of the seven crew members. Generally, the film supports the Space Shuttle program and the dedication of NASA personnel in general while criticizing NASA management. +After beginning on the eve of the launch, the rest of the film is told through flashback, beginning on July 19, 1985, when Christa McAuliffe was officially selected to be the first teacher to travel into space. The film ends just as the shuttle takes off on January 28, 1986, following a symbolic scene of each of the seven crew members and passengers reciting in their thoughts John Gillespie Magee Jr.'s poem "High Flight". U.S. President Ronald Reagan used part of "High Flight" in a speech written by Peggy Noonan on the night after the Challenger disaster while eulogizing the fallen members of the crew. + + +== Cast == +Karen Allen portrayed Christa McAuliffe, Kristin Bond portrayed McAuliffe's daughter, Caroline, and Kale Browne portrayed McAuliffe's husband, Steven. Allen and Browne were married in real life. +Peter Boyle portrayed Roger Boisjoly, the Thiokol engineer most vocal about the danger of launching at extremely low temperatures because of the risk that the O-ring seals in the shuttle's rocket boosters would fail at those temperatures. +The film also examines the personal lives of the other members of the crew - Barry Bostwick as Commander Dick Scobee, Brian Kerwin as Pilot Michael Smith, Joe Morton as Dr. Ronald McNair, Keone Young as Lt. Col. Ellison Onizuka, Richard Jenkins as Gregory B. Jarvis, Julie Fulton as Dr. Judith Resnik - and their families - Angela Bassett as Cheryl McNair, Elizabeth Kemp as Jane Smith, Jeanne Mori as Lorna Onizuka, Debbie Boily as Marcia Jarvis, Melinda Ann Austin as June Scobee, Melissa Chan as Janelle Onizuka, Gavin Luckett as Reggie McNair, Naoka Nakagawa as Darien Onizuka, Thomas Allen Jr. as Scott Smith - before they boarded Challenger. + + +== Emmy award == +At the 42nd Primetime Emmy Awards in September 1990, Challenger won Outstanding Sound Editing for a Miniseries or a Special. + + +== See also == +The Challenger Disaster, 2013 film +Challenger: The Final Flight, 2020 documentary miniseries + + +== References == + + +== External links == +Challenger at IMDb \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Climate_Audit-0.md b/data/en.wikipedia.org/wiki/Climate_Audit-0.md new file mode 100644 index 000000000..5034dd690 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Climate_Audit-0.md @@ -0,0 +1,47 @@ +--- +title: "Climate Audit" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Climate_Audit" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:05.250095+00:00" +instance: "kb-cron" +--- + +Climate Audit is a blog founded in 2005 by Steve McIntyre. +In November 2009 journalist Andrew Revkin described it in The New York Times as "a popular skeptics’ blog" run by McIntyre, a retired Canadian mining consultant. In 2010, a Nature article described the site as part of the "climate change skeptic community" alongside the Air Vent and the Blackboard. + + +== Founding == +In 2004 Stephen McIntyre blogged on his website climate2003.com about his efforts with Ross McKitrick to get an extended analysis of the hockey stick graph into the journal Nature. +On 25 October 2004 McIntyre posted comments on climate2003.com about a piece by William Connolley circulated on various blogs, and on 26 October wrote, "Maybe I’ll start blogging some odds and ends that I’m working on. I’m going to post up some more observations on some of the blog criticisms." On 1 December Michael E. Mann and nine other scientists launched the RealClimate website as "a resource where the public can go to see what actual scientists working in the field have to say about the latest issues." On climate2003.com McIntyre noted this development in a blog post on 10 December, where he wrote "Mann and some of his colleagues have set up a blog at the above address. A couple of Mann's first postings have been arguments against our papers. I'll post up a two quick comments below." On 2 February 2005 McIntyre set up his Climate Audit blog, having found difficulties with posting comments on the climate2003.com layout. +Judith Curry of the Georgia Institute of Technology has said "McIntyre started the blog climateaudit.org so that he could defend himself against claims being made at the blog Realclimate with regards to his critique of the “hockey stick” since he was unable to post his comments there". She has also referred to this site as one of several "Climate Auditor" websites. + + +== Climatic Research Unit information requests and email controversy == + +After the UK Freedom of Information Act (FOIA) came into effect in 2005, Climate Audit readers were asked to make FOI requests to the Climatic Research Unit (CRU) at the University of East Anglia (UEA) for the raw data from weather stations used in developing instrumental temperature record datasets, for copies of agreements under which the raw data was obtained from meteorology institutions, and also for email correspondence relating to the Intergovernmental Panel on Climate Change Fourth Assessment Report. +On 12 August 2009, Olive Heffernan wrote in naturenews that "Since 2002, Steve McIntyre, the editor of Climate Audit, a blog that investigates the statistical methods used in climate science, has repeatedly asked Phil Jones, director of the Climatic Research Unit (CRU) at the University of East Anglia, UK, for access to monthly global surface temperature data held by the institute. But in recent weeks, Jones has been swamped by a sudden surge in demands for data". She described how CRU had received 58 FOIA requests between 24 and 29 July 2009 from McIntyre or others associated with the blog. The raw data was restricted to academics, and the unit's director Phil Jones said that the data was subject to confidentiality agreements with various governments, but he was seeking agreement to get the raw data available online. He said that “Data release needs to be done in a systematic way.” +The site was one of the first to receive word of the e-mails which had been leaked from the University of East Anglia with Jonathan Leake of The Times writing, "The storm began with just four cryptic words. 'A miracle has happened,' announced a contributor to Climate Audit, a website devoted to criticising the science of climate change." Louise Gray wrote in The Daily Telegraph, "Climate Audit was one of the first to post up the stolen emails from the University of East Anglia that led to the 'climategate' scandal". +Bloomberg said of the controversy, "Web sites and blogs including the Climate Audit Mirror Site have carried copies of e-mails, correspondence between climatologists and commentary. In one e-mail cited widely on blogs including Climate Audit, Phil Jones writes about completing “Mike’s nature trick of adding in the real temps” in order to hide the decline." According to Antonio Regalado writing in Science Insider, Jones wrote e-mails stating that he convinced the university's FOI managers to not release data to "greenhouse skeptics" because Jones believed that they planned to harm the UEA or setback climate science by drawing scientists into disputes, wasting research time. "Think I've managed to persuade UEA to ignore all further FOIA requests if the people have anything to do with Climate Audit," Jones wrote in 2007. The House of Commons' Science and Technology Committee largely vindicated the scientists involved in the scandal, but left consideration of the quality of the science and the conduct of the research to committees chaired by Lord Oxburgh and Sir Muir Russell. Fox News said that McIntyre "who also worked at the IPCC and submitted notes to the Science and Technology Committee for its investigation, wrote a lengthy rebuttal of the decision on his blog", and disputed the committee's conclusion that the word trick "appears to be a colloquialism for a 'neat' method of handling data". Further investigations by the United States Environmental Protection Agency, the Inspector General of the United States Department of Commerce and the Office of the Inspector General (OIG) of the National Science Foundation reaffirmed that the accusations against the scientists were unfounded. + + +== Reception == +James Hansen, the former director of NASA's Goddard Institute, has dismissed McIntyre as a "court jester". +"If a single person can be credited with setting the stage for Climategate, it's Stephen McIntyre, the retired mining consultant behind the popular skeptic blog Climate Audit," wrote Kate Sheppard at Mother Jones in 2011. "Emails from this period show the scientists lashing out against McIntyre. He is referred to as a "bozo" and "a playground bully." McIntyre clearly gets a rise out of irking scientists, whom he frequently refers to as 'the Team'—another play on the hockey-stick metaphor. He likes to 'tease these guys and kind of make fun of them,' he says, and their evident aggravation at his inquiries only egged him on. 'I think it was a mistake for them to in effect adopt a fatwa against Climate Audit,' says McIntyre." +Patrick J. Michaels, a former contributor to the IPCC and a former fellow at the denialist Cato Institute, named Climate Audit as part of 'a new “parallel universe” of emerging online publications, manned by serious scientists critical of world governments approach to climate change'. “A parallel universe is assembling itself parallel to the IPCC. This universe has become very technical -- very proficient at taking apart the U.N.’s findings." +Internet voting by the public organized by the Weblog Awards, a right-wing blog sponsored by conservative media group Wizbang LLC, won the website the 2007 Weblog "Best Science Blog" award and it was a runner up in the same category in 2008. + + +== See also == +Global warming controversy +The Hockey Stick Illusion +Tree ring + + +== References == + + +== External links == +ClimateAudit +Climate Audit on LittleSis, a website that publishes data on who-knows-who between government, donors and business \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Code_of_a_Killer-0.md b/data/en.wikipedia.org/wiki/Code_of_a_Killer-0.md new file mode 100644 index 000000000..87d5ae288 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Code_of_a_Killer-0.md @@ -0,0 +1,52 @@ +--- +title: "Code of a Killer" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Code_of_a_Killer" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:08.497073+00:00" +instance: "kb-cron" +--- + +Code of a Killer is a three-part British police drama television series which tells the true story of Alec Jeffreys' discovery of DNA fingerprinting and its introductory use by Detective David Baker in catching the double murderer Colin Pitchfork. Filming commenced in late September 2014, and the program aired on the ITV network, on 6 and 13 April 2015. Endemol Shine handled international distribution of the series. + + +== Plot == +Set over a nearly four-year period from 1983 to 1987, DCS David Baker leads an investigation into the vicious murders of the two Leicestershire teenage schoolgirls, Lynda Mann and Dawn Ashworth. Meanwhile, Alec Jeffreys is an ambitious scientist who has recently discovered a remarkable method to read a person's DNA and, from it, generate a unique DNA fingerprint. Convinced one local person committed both crimes, Baker approaches Jeffreys to utilise his scientific technique to solve the murders. The first-ever DNA manhunt follows, involving the blood testing of many men — all in the aid of catching the killer. + + +== Cast == + + +== Production == + + +=== Development === +Code of a Killer was commissioned by ITV's Director of Drama Steve November and Controller of Drama Victoria Fea on 16 May 2014. The series was developed with the participation of retired Professor Sir Alec Jeffreys and former Detective Chief Superintendent David Baker. It was written by Michael Crompton, directed by James Strong, produced by Priscilla Parish, and executive produced by Simon Heath for World Productions. Filming began in late September 2014, and the episodes were shown on 6 and 13 April 2015 at 9:00 p.m. on the ITV network. + + +== Broadcast == +The series premiered in Australia on BBC First on 19 September 2015. + + +== Episodes == +Originally aired in 2015 in the UK and Australia as two 65-minute episodes; currently streams online as three 45-minute episodes plus one 28-minute ‘Behind the Scenes’ special. The episode descriptions below are for the (current) thee-episode format, while air dates and viewership data apply to the (original) two-episode format. + + +== Reception == + + +=== Critical reception === +The drama received a mixed reception. The first part was criticised for dramatic sluggishness and a reliance on crime-show clichés in the portrayal of the two main characters. The depiction of Alec Jeffreys as the stereotypical absent-minded "boffin" was cited by several reviewers. Gerard O'Donovan in The Daily Telegraph called the show's version of him a "stock obsessive boffin so wedded to his lab instruments that his marriage was permanently on the brink of collapse". Julia Raeside in The Guardian wrote, "There are obligatory scenes in which Jeffreys misses a school play and receives a phone call from his wife pronouncing, 'Your dinner’s in the dog.' There are only so many times co-workers can remark, 'Don’t work too late' or 'Aren’t you going home?' before the hammering repetition starts to cause a dent in your enjoyment." Chris Bennion in The Independent concluded that "Sadly this drama had the fingerprints of countless other by-numbers crime thrillers all over it." +Alex Hardy in The Times was less critical, giving the show four stars out of five and saying that "this fact-based drama managed to balance tragedy with optimism", but added that it "inevitably contained elements of soap". + + +== Notes == + + +== References == + + +== External links == +Code of a Killer at IMDb +Code of a Killer at British TV Detectives \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Compound_Interest_(website)-0.md b/data/en.wikipedia.org/wiki/Compound_Interest_(website)-0.md new file mode 100644 index 000000000..4fe96943d --- /dev/null +++ b/data/en.wikipedia.org/wiki/Compound_Interest_(website)-0.md @@ -0,0 +1,14 @@ +--- +title: "Compound Interest (website)" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Compound_Interest_(website)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:06.421945+00:00" +instance: "kb-cron" +--- + +Compound Interest is a website launched in 2013 by Andy Brunning with infographics on everyday chemistry. The infographics describe, for example, how chemicals found in food and nature give them smell, taste, and color. The website has a monthly collaboration with the American Chemical Society. Content of the website is used as information source by various newspapers and media, including the Washington Post, Time, The Conversation, and Forbes. + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Cosmic_Variance_(blog)-0.md b/data/en.wikipedia.org/wiki/Cosmic_Variance_(blog)-0.md new file mode 100644 index 000000000..b4a1b28cd --- /dev/null +++ b/data/en.wikipedia.org/wiki/Cosmic_Variance_(blog)-0.md @@ -0,0 +1,21 @@ +--- +title: "Cosmic Variance (blog)" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Cosmic_Variance_(blog)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:07.674208+00:00" +instance: "kb-cron" +--- + +Cosmic Variance was a collaborative weblog discussing physics, astrophysics, and other topics, written by JoAnne Hewett, Mark Trodden, Sean Carroll, Risa Wechsler, Julianne Dalcanton, Clifford Johnson, John Conway, and Daniel Holz. It was the successor to Carroll's earlier blog Preposterous Universe, which began in early 2004 and ran through much of 2005. The blog's name came from th concept of cosmic variance in cosmology. +Cosmic Variance rapidly become "undoubtedly the most popular blog written by physicists." In 2006, Nature reported that it was the fourth most popular science blog and one of only five blogs by scientists in the 3500 most popular blogs. As of July 26, 2007, Cosmic Variance had a Technorati authority of 1001 and rank of 2277. In 2008, the blog became part of the Discover magazine website. +Most writing on Cosmic Variance focused on modern physics, astrophysics, and cosmology, at a level accessible to the interested non-scientist. However, topics of discussion ranged widely, including science and religion, science journalism, higher education, and politics. Several discussions on Cosmic Variance gained attention in the print media, including a discussion on women in science that compared physicist Lisa Randall to Jodie Foster and a post by John Conway about his discovery of a "bump" in particle accelerator data that turned out not to be caused by the Higgs boson. When the engagement of Carroll to science writer Jennifer Ouellette was first announced on his blog, the story was picked up by both the New York Times and the prominent scientific journal Nature. +Cosmic Variance hosted a number of guest bloggers, including string theorist Joseph Polchinski reviewing Lee Smolin's book The Trouble With Physics. + + +== References == + + +== External links == +Cosmic Variance \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Creation_(2009_film)-0.md b/data/en.wikipedia.org/wiki/Creation_(2009_film)-0.md new file mode 100644 index 000000000..c94d48ebe --- /dev/null +++ b/data/en.wikipedia.org/wiki/Creation_(2009_film)-0.md @@ -0,0 +1,27 @@ +--- +title: "Creation (2009 film)" +chunk: 1/2 +source: "https://en.wikipedia.org/wiki/Creation_(2009_film)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:09.638572+00:00" +instance: "kb-cron" +--- + +Creation is a 2009 British biographical drama film about Charles Darwin's relationship with his wife Emma and his memory of their eldest daughter Annie, as he struggles to write On the Origin of Species. The film, directed by Jon Amiel and starring real life couple Paul Bettany and Jennifer Connelly as Charles and Emma Darwin, is a somewhat fictionalised account based on Randal Keynes's Darwin biography Annie's Box. + +== Plot == +British naturalist Charles Darwin is a young father who lives a quiet life in an idyllic village. He is a brilliant and deeply emotional man, devoted to his wife and children. Darwin is especially fond of his eldest daughter Annie, a precocious and inquisitive ten-year-old. He teaches her much about nature and science, including his theory of evolution, and tells her stories of his travels. Her favourite story, despite the sad ending, is about the young orangutan Jenny, who is brought from Borneo to the London Zoo, where she finally died of pneumonia in the arms of her keeper. Darwin is furious when he learns that the family clergyman has made Annie kneel on rock salt as punishment for contradicting him about dinosaurs, which she takes as having become extinct long ago. This contradicts their church's position that life is unchanging and that the Earth is very young -- Young Earth Creationism being a then-recent heresy taken as dogma by Seventh-day Adventists. +Having returned from his expedition in the Galapagos Islands 15 years earlier, Darwin is still trying to finish a manuscript about his findings, which will articulate his theory of evolution. The delay is caused by anxiety about his relationship with his devoutly religious wife, Emma, who fundamentally opposes his ideas, which pose a threat to established Anglican theology. Emma worries that she may go to heaven and he may not, separating them for eternity. +The film shows Annie, through flashbacks and Darwin's hallucinations, as a vibrant apparition who goads her father to address his fears and finish his big work. It is apparent that Annie has died, and that her death is a taboo subject between Darwin and Emma, as both feel intense blame for her death. As a result of the strained relations between Charles and Emma, they entirely stop having sex. Anguished, Darwin begins to suffer from a mysterious, fatiguing illness. +It is revealed that after Annie becomes ill in 1851, Darwin takes her to the Worcestershire town of Malvern for James Manby Gully's water cure therapy, against Emma's will. Annie's condition worsens, and she ultimately dies after her father, at her request, tells her Jenny's story once more. Darwin is devastated, and her death sharpens his conviction that natural laws operate without divine intervention. To his contemporaries, this is an idea so dangerous it seems to threaten the existence of God (in reality, many of Darwin's biggest supporters were believers). In a box in Darwin's study, we discover the notes and observations that will become On the Origin of Species. +Having read his 230 page synopsis, Darwin's friends in the scientific community, Joseph Dalton Hooker and Thomas Henry Huxley, also encourage him. Huxley admiringly tells Darwin that with his theory he has "killed God", which fills Darwin with dread. In his hallucinations, he also feels that Annie disapproves of his procrastination. +Darwin receives a letter from Alfred Russel Wallace in 1858, which details the same findings as Darwin in 20 pages. He has mixed feelings about this; all his work may have been in vain, but on the other hand, as he will not have to write his book, the discord with Emma will heal. However, Darwin's friends urge him to continue, as his book is much more comprehensive. +After receiving treatment at Malvern himself, Darwin makes a pilgrimage to the hotel where Annie died. The journey marks a change in him; upon his return home, he is able to reconnect with his wife, and they speak to each other for the first time of their fears and grief over Annie's death. They specifically speak about the possibility that Annie died because she was genetically weak, as Darwin and Emma are first cousins. Their renewed devotion restores Darwin's health, and he is able to resume his work. Emma's faith in their marriage is also restored, and she regains strength to support his controversial work. Darwin decides that Emma must make the decision about publishing his work. After reading the manuscript, she quietly returns it to him, having addressed the package to John Murray publishers in London. Emma accepts that she is an "accomplice" now, but hopes that God will forgive them both. +Darwin walks down the lane, holding the package. When the postman arrives, Darwin falters, almost letting him go empty-handed. The postman rides away, unaware of the powerful idea about to be released onto the world. As Darwin walks home, the little figure of Annie walks alongside him. + +== Cast == + +== Production == +Creation is an adaptation by screenwriter John Collee of Annie's Box: Charles Darwin, His Daughter and Human Evolution, a bestselling biography of Charles Darwin by Darwin's great-great grandson Randal Keynes. +The film was produced by Jeremy Thomas's Recorded Picture Company as a co-development with BBC Films, and with financial assistance from the UK Film Council's development fund. Much of the filming, which was completed in December 2008, took place in the Wiltshire town of Bradford on Avon, which was standing in for Malvern, and at Darwin's home, Down House in Kent. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Creation_(2009_film)-1.md b/data/en.wikipedia.org/wiki/Creation_(2009_film)-1.md new file mode 100644 index 000000000..f8792718b --- /dev/null +++ b/data/en.wikipedia.org/wiki/Creation_(2009_film)-1.md @@ -0,0 +1,31 @@ +--- +title: "Creation (2009 film)" +chunk: 2/2 +source: "https://en.wikipedia.org/wiki/Creation_(2009_film)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:09.638572+00:00" +instance: "kb-cron" +--- + +== Releases == +The film had its world premiere on 10 September 2009 at the 2009 Toronto International Film Festival as the opening night gala presentation, the first non-Canadian film since 1996 to be so honoured. +On 24 September 2009, Variety reported that Newmarket Films had acquired the rights to the film, which Newmarket released on 22 January in the U.S. +The film was released in the U.K. on 25 September 2009, in Greece on 15 October 2009, in Japan on 20 October 2009 (Tokyo International Film Festival), in New Zealand on 24 December 2009, in the Netherlands on 7 January 2010, in Belgium on 20 January 2010, and in the U.S. and Canada on 22 January 2010. +According to producer Jeremy Thomas, the United States was one of the last countries to find a distributor, due to the prominence of controversy about evolution and creation. Thomas said, in the beginning of September 2009: + +It is unbelievable to us that this is still a really hot potato in America. There's still a great belief that He [God] made the world in six days. It's quite difficult for us in the U.K. to imagine religion in America. We live in a country which is no longer so religious. But in the U.S., outside of New York and Los Angeles, religion rules. +His comments in the mainstream press, and the publicity surrounding the Toronto premiere, provoked Internet flame wars across religious, atheist, science, and film communities. Posts on related blogs such as that of film critic Roger Ebert (a noted admirer of Darwin) stretched into the hundreds. + +== Reception == +The film has received mixed reviews by critics. Review aggregator Rotten Tomatoes reports that 47% of critics have given the film a positive review based on 115 reviews, with an average score of 5.5/10: + +This Charles Darwin biopic is curiously dispassionate, but Creation contains some of director Jon Amiel's best work, and Paul Bettany's performance is not to be missed. Based on 28 reviews, Metacritic assigned a score of 51/100, indicating "mixed or average reviews". +In The New York Times, A. O. Scott wrote "the film traffics in the pseudo-psychological mumbo-jumbo that is the standard folk religion of the film biography, and undermines its interest in reason by dabbling in emotive pop occultism." +Film critic Philip French, writing in The Observer, called the film "A complex, truthful work that does justice to Darwin's theories and their implications", while his colleague, film critic Peter Bradshaw in The Guardian, wrote "This gentle, heartfelt and well-acted film about Charles Darwin and his personal agony preceding the 1859 publication of 'On the Origin of Species' does not shy away from the issues. But it personalises them, and places them in a new context." +In The Daily Telegraph, film critic Tim Robey opined: "Bettany has a genius for distraction and reverie, guiding the film intelligently in and out of its soul-searching flashbacks. Only the closing shot of father and daughter walking hand in hand feels like a sentimental misstep—the one touch too much, in a sad, searching piece of work about the reluctant labour of a great idea." In Screen International, senior film critic Fionnuala Halligan wrote: "Bettany is undoubtedly the film's main asset: physically and emotionally convincing as Darwin in a very tricky role. Amiel's core challenge here is to make audiences believe their story: parents to 10 children, eminent Victorians with an unusual devotion to their brood; the author of a book which changed the world." +Writing in The Hollywood Reporter, film critic Ray Bennett said "Amiel's greatest achievement is that Creation is a deeply human film with moments of genuine lightness and high spirits to go with all the deep thinking." + +== References == + +== External links == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Daedalus-0.md b/data/en.wikipedia.org/wiki/Daedalus-0.md new file mode 100644 index 000000000..f91b22167 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Daedalus-0.md @@ -0,0 +1,26 @@ +--- +title: "Daedalus; or, Science and the Future" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Daedalus;_or,_Science_and_the_Future" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:37.233315+00:00" +instance: "kb-cron" +--- + +Daedalus; or, Science and the Future is a book by the British scientist J. B. S. Haldane, published in England in 1924. It was the text of a lecture read to the Heretics Society (an intellectual club at the University of Cambridge) on 4 February 1923. +Haldane uses the Greek myth of Daedalus as a symbol for the revolutionary nature of science with particular regard to his own discipline of biology. + +The chemical or physical inventor is always a Prometheus. There is no great invention, from fire to flying, which has not been hailed as an insult to some god. But if every physical and chemical invention is a blasphemy, every biological invention is a perversion. There is hardly one which, on first being brought to the notice of an observer from any nation which had not previously heard of their existence, would not appear to him as indecent and unnatural. +He also expressed skepticism over the human benefits of some scientific advances, arguing that scientific advance would bring grief, rather than progress to mankind, unless it was accompanied by a similar advance in ethics. +The book is an early vision of transhumanism and his vision of a future in which humans controlled their own evolution through directed mutation and use of in vitro fertilisation ("ectogenesis") was a major influence on Aldous Huxley's Brave New World. The book ends with the image of a biologist, much like Haldane himself, in a laboratory: "just a poor little scrubby underpaid man groping blindly amid the mazes of the ultramicroscope... conscious of his ghastly mission and proud of it." +The book has been discussed at length by other writers, including Freeman Dyson in his book Imagined Worlds and Sal Restivo in Science, Society, and Values, and the concept has been used in contemporary science lectures. + + +== References == + + +== External links == + + Daedalus; or, Science and the Future at Project Gutenberg +book at HathiTrust \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Day_One_(1989_film)-0.md b/data/en.wikipedia.org/wiki/Day_One_(1989_film)-0.md new file mode 100644 index 000000000..9bc2c2681 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Day_One_(1989_film)-0.md @@ -0,0 +1,40 @@ +--- +title: "Day One (1989 film)" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Day_One_(1989_film)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:10.888395+00:00" +instance: "kb-cron" +--- + +Day One is a made-for-TV docudrama film about the Manhattan Project, the research and development of the atomic bomb during World War II. It is based on the book by Peter H. Wyden. The film was written by David W. Rintels and directed by Joseph Sargent. It starred Brian Dennehy as General Leslie Groves, David Strathairn as Dr. J. Robert Oppenheimer and Michael Tucker as Dr. Leo Szilard. It premiered in the United States on March 5, 1989 on the CBS network. It won the Primetime Emmy Award for Outstanding Drama/ or Comedy Special at the 41st Primetime Emmy Awards in 1989. The movie received critical acclaim for its historical accuracy despite being a dramatization. + + +== Plot == +Hungarian physicist Leo Szilard flees Germany on the last train out and leaves Europe during World War II. He attempts to convince the military in England that a nuclear bomb can be built and that the Germans are already working on it. His idea is filed and ignored. He eventually arrives in the United States where, with the help of Albert Einstein, he persuades the Federal government after a year to build an atomic bomb. The Manhattan Project is started and General Leslie Groves selects physicist J. Robert Oppenheimer to head the Los Alamos Laboratory in New Mexico, where the bomb is built. As World War II draws to a close, Szilard (whose idea was responsible for the progress made) has second thoughts about atomic weapons and debates how and when to use the bom +As Germany is being defeated and its scientists interrogated, it is found out that they have not even come close to constructing a nuclear bomb (partly due to bad cooperation by scientists). Despite the fact that no one has the technology now, and the original reason for the Manhattan Project is gone, work continues. Szilard, who first used Einstein to get his ideas about building a bomb across to the US leaders, now convinces him to join him in writing a letter to President Harry S. Truman to do the opposite, namely not to build the bomb, in order to avoid an arms race. 68 scientists sign a petition, but that is held back by the military. +U.S. President Truman is faced with four options: peace talks (which would require the Japanese to keep their emperor, as eventually happened), a blockade (which was thought to be cowardly), an invasion (estimated by some to cost up to a million lives, though such numbers have been widely disputed), or dropping the bomb. Another consideration is that the USSR had said they would enter the war against Japan three months after the surrender of Germany and there is a fear that they might not leave. So Truman decides that the best course of action is to drop the bomb on Hiroshima, against the advice of General Dwight D. Eisenhower. + + +== Cast == + + +== Production == +In order to depict a desert setting, certain scenes of the film were filmed in a town named Notre Dame de Lourdes, located in the province of Quebec. The town offered a wide expanse of sand quarry that was used for filming. + + +== See also == +The Beginning or the End, 1947 docudrama film about the Manhattan Project. +Oppenheimer, 1980 biographical television series about J. Robert Oppenheimer (Sam Waterston) and the project to build the atomic bomb. +Fat Man and Little Boy, 1989 film about the Manhattan Project, starring Paul Newman as General Leslie Groves and Dwight Schultz as Oppenheimer +Nuclear Secrets, 2007 TV mini-series with two episodes dedicated to the Manhattan Project +Manhattan, 2014-15 television series set at the Manhattan Project +Oppenheimer, 2023 film about Oppenheimer (Cillian Murphy) and the Manhattan Project + + +== References == + + +== External links == +Day One at IMDb \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Day_of_Archaeology-0.md b/data/en.wikipedia.org/wiki/Day_of_Archaeology-0.md new file mode 100644 index 000000000..0183ca72e --- /dev/null +++ b/data/en.wikipedia.org/wiki/Day_of_Archaeology-0.md @@ -0,0 +1,37 @@ +--- +title: "Day of Archaeology" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Day_of_Archaeology" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:08.853588+00:00" +instance: "kb-cron" +--- + +The Day of Archaeology is an annual, 24-hour, international online event in which archaeologists and those in related fields write blog posts about their work. It was inspired by the Day of Digital Humanities and, similarly, allows practitioners of many kinds, to document their work informally and 'provide a window into the daily lives of archaeologists from all over the world'. Though it encourages diversity rather than thematic posts, the project has some similarities to Blog Action Day. + + +== Overview == +The first event took place on 27 July 2011. The event is organised by a voluntary committee of archaeologists based in the United Kingdom, United States of America and Spain. The main site runs a customised WordPress content management system and the event is promoted through Twitter and Facebook pages (see External links). +The project is supported by several British archaeological and academic organisations: server space is provided on the Portable Antiquities Scheme servers and long-term digital preservation is provided by the Archaeology Data Service. L-P Archaeology and the UCL Centre for Digital Humanities provide technical and management advice. In 2011 and 2013 the event was timed to coincide with the Festival of British Archaeology. +The project covers any form of work that could be considered archaeology and encourages contributions from any level of professionalism. + + +== External coverage == +Several archaeologists have blogged about the project in official and personal capacities and the project committee wrote posts on various other sites, notably the Society for Historical Archaeology and the British Museum. +After the 2011 event a preliminary data mining analysis was conducted. Similarly, after the 2014 event a topic modelling and keyword analysis was published. +The Day of Archaeology project was nominated for a British Archaeology Award in July 2011 in the 'Best Representation of Archaeology in the Media' category and was highly commended. + + +== Event summaries == + +Data sources: + + +== References == + + +== External links == +Day of Archaeology on Twitter +Day of Archaeology on Facebook +Day of Archaeology on Flickr \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Durma_Melhor-0.md b/data/en.wikipedia.org/wiki/Durma_Melhor-0.md new file mode 100644 index 000000000..bf9560153 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Durma_Melhor-0.md @@ -0,0 +1,25 @@ +--- +title: "Durma Melhor" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Durma_Melhor" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:10.048691+00:00" +instance: "kb-cron" +--- + +Durma Melhor ("Sleep Better", translated into English) is a Brazilian blog featuring relevant information on issues related to sleep. Published in Portuguese, the blog content includes articles on nutrition, beauty, exercise, relaxation, environment, technology, scientific studies and frequently asked questions regarding sleep. +It also features a selection of videos, podcasts, books, websites, soothing songs available for free download, as well as online tests to assess one's sleep quality and a comprehensive list of sleep labs in Brazil. +Durma Melhor contributors include Dr. Flávio Alóe, neurologist and neurophysiologist of the Brazilian Society of Clinical Neurophysiology and a certified physician in Sleep Medicine by the Brazilian Society of Sleep, who's been widely interviewed by Brazilian magazines, newspapers and TV shows, such as Programa do Jô. +In April 2010, Durma Melhor launched a channel that allows the general public to send questions and have them answered by experts in sleep medicine. +The blog was launched in January 2010 by Marcos Miguel, a Brazilian journalist who's graduated at the Universidade Federal de Juiz de Fora, in Minas Gerais state. + + +== See also == + + +== References == + + +== External links == +Official site \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/End_Day-0.md b/data/en.wikipedia.org/wiki/End_Day-0.md new file mode 100644 index 000000000..beba794f9 --- /dev/null +++ b/data/en.wikipedia.org/wiki/End_Day-0.md @@ -0,0 +1,68 @@ +--- +title: "End Day" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/End_Day" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:12.078299+00:00" +instance: "kb-cron" +--- + +End Day is a 2005 docu-drama produced by the BBC. It aired on the National Geographic Channel, on the TV series National Geographic Channel Presents, and BBC Three. It depicts a set of five doomsday scenarios. The documentary follows the fictional scientist Dr. Howell, played by Glenn Conroy, as he travels from his London hotel room to his laboratory in New York City, and shows how each scenario affects his journey as well as those around him, with various experts providing commentary on that specific disaster as it unfolds. After each 'End Day' runs its course, the day repeats, this time with the next scenario panning out. +The following descriptions of the program were released by the BBC: + +"Imagine waking up to the last day on Earth..." +"Inspired by the predictions of scientists, End Day creates apocalyptic scenarios that go beyond reality. In a single hour, explore five different fictional disasters, from a giant tsunami hitting New York to a deadly meteorite strike on Berlin." + + +== Scenarios == + + +=== Mega-Tsunami === +A volcanic eruption of Cumbre Vieja on the island of La Palma in the Canary Islands triggers a massive landslide. A sizable portion of the island collapses into the sea, causing a massive tsunami, 500 feet (150 m) tall, to race across the Atlantic Ocean. The United States Navy searches for the wave and locates it, predicting that the mega-tsunami will strike the East Coast of the United States. An evacuation of New York City is ordered but not completed by the time the wave arrives and inundates the city, killing thousands of people but leaving many sturdier buildings intact, which proved to be crucial in providing a means of escape. A briefing by the US government after the flood waters started receding reveals that the wave travelled over two miles inland. Despite the vast amount of casualties, a substantial number of New York citizens survive the disaster by climbing to the upper floors of tall buildings, which were able to withstand the force of the tsunami. + + +=== Killer Meteorite === +This scenario begins with a suspected missile attack in a remote area of the Middle East. The missiles are soon revealed to be a meteor shower of meteoroids, the advance guard of a much larger asteroid that is predicted to impact Berlin, Germany. After determining the asteroid's size and orbital characteristics, the militaries of Germany, Britain, and the United States attempt to alter its course using ICBMs. The asteroid is shattered into hundreds of fragments, but the effort fails to alter its course. An evacuation of Berlin is achieved with public transport; citizens unable to escape seek shelter in the city's U-Bahn stations. As fragments rain down across Berlin, one train manages to escape just in time to avoid the largest fragment striking and destroying a large portion of the city's centre, leaving an impact crater where the Reichstag building once stood. + + +=== Global Pandemic === + +In this scenario, a variant of influenza named the "Far East Virus" with similarities to SARS spreads to the UK after its patient zero travels from Hong Kong to London, then infects people on a London Underground train. The virus rapidly spreads across Europe and beyond without any containment, developing into a pandemic. Areas of the UK are placed under quarantine. Countries around the world enact martial law and close their borders in an effort to slow the spread of the disease. These efforts fail, and the outbreak reaches the scale of the 1918-20 Spanish flu pandemic, killing millions of people. + + +=== Supervolcano === +The supervolcano beneath Yellowstone National Park begins to become active, showing the initial signs of activity through volcanic earthquakes in Wyoming. Volcanic activity increases in the area at an exponential rate, indicating that an eruption is imminent. A geyser and then Yellowstone itself explodes, incinerating everything within 100 kilometres of the caldera. The volcanic ash launched into the atmosphere grounds civil aviation across Europe and North America and is expected to bring about a volcanic winter. Survivors emerge from the wreckage of Denver, the city scorched by pyroclastic and lava flows. + + +==== Note ==== +This segment has only aired in the UK. The BBC docudrama Supervolcano explored this scenario more in-depth. + + +=== Strange Matter === +Dr. Howell reaches the laboratory unimpeded, and is tasked with carrying out an experiment using the world's largest particle accelerator. The experiment goes wrong, resulting in the creation of a strangelet, a hypothetical particle containing strange quarks that is capable of converting ordinary matter into strange matter. The strangelet causes the particle accelerator to explode, then rises to the surface, converting the entirety of New York City and wreaking havoc on Earth's atmosphere, triggering vast storm systems to form. Paris is devoured by one such storm system, and the strange matter continues to spread exponentially. Off-screen, the strangelet finishes consuming and converting the planet into a sphere of pure strange matter. Ironically, by preventing Dr. Howell from reaching the particle accelerator, each of the other potential disasters inadvertently saved the Earth from total destruction. + + +== Alternative versions == +All original official sources cite five different scenarios including a giant volcanic explosion, but the volcanic explosion segment has never been aired in the United States, having been edited out by the National Geographic Channel, possibly for time problems or the inaccurate depiction of the Western United States and Yellowstone park. All references to it on the National Geographic website have been removed. Only the other four scenarios have been aired. However, the BBC website had the super volcano segment until it was removed some time after 28 May 2006. UKTV History aired the version including the supervolcano segment on 23 January 2007. However, in the original BBC airing, each of the scenarios showed the attempts of a family or person to escape the depicted disaster, as well as following Dr. Howell; these segments were mostly cut from the UKTV History version aired in 2007. The volcano sequence can however be found on the popular video website YouTube. +A French-dubbed version of End Day was aired in France on W9) and in Belgium (on RTBF), under the title Fin du monde : les quatre scénarios (End day: the four scenarios). The "super volcano" scenario was not included. + + +== References in the film == +When Dr. Howell drives off in a taxi at the beginning of the second segment, a cinema showing "Groundhog Day appears. In Groundhog Day, the protagonist is stuck in a single day of his life, repeating it time after time with minor variations. + + +== See also == +Extinction event +Near-Earth object + + +== References == + + +== External links == +End Day at BBC Online +"National Geographic Channel: End Day official website". Archived from the original on 11 December 2005. Retrieved 7 July 2006. +"BBC: End Day official website". Archived from the original on 28 May 2006. Retrieved 17 July 2006. +End Day at IMDb +Banks-Smith, Nancy (17 March 2005). "The inedible journey". The Guardian. Archived from the original on 28 July 2025. Retrieved 28 July 2025. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Eternity b/data/en.wikipedia.org/wiki/Eternity new file mode 100644 index 000000000..e69de29bb diff --git a/data/en.wikipedia.org/wiki/FESOM-0.md b/data/en.wikipedia.org/wiki/FESOM-0.md new file mode 100644 index 000000000..7c944438f --- /dev/null +++ b/data/en.wikipedia.org/wiki/FESOM-0.md @@ -0,0 +1,42 @@ +--- +title: "FESOM" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/FESOM" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:40.618673+00:00" +instance: "kb-cron" +--- + +FESOM (Finite-Element/volumE Sea ice-Ocean Model) is a +multi-resolution ocean general circulation model that solves the equations +of motion describing the ocean and sea ice using finite-element and +finite-volume methods on unstructured computational grids. The model +is developed and supported by researchers at the Alfred Wegener +Institute, Helmholtz Centre for Polar and Marine Research (AWI), in Bremerhaven, +Germany. + + +== Overview == +FESOM implements the idea of using meshes with variable resolution +to simulate the circulation of the global ocean with regional focus. Because +of the broad range of scales characterizing the ocean circulation, downscaling +is commonly needed to describe processes on regional scales. FESOM allows global +multi-resolution cross-scale simulations without traditional nesting. +The dynamical core of the new version (FESOM2) switches from the finite-element +method used in the original version of FESOM to the finite-volume method for the sake of better computational efficiency. Both versions include the Finite-Element Sea Ice Model (FESIM). FESOM is also used as the ocean component of the AWI-CM, the coupled atmosphere-ocean climate model developed at AWI. + + +== History == +The prototype version of FESOM appeared in 2004 due to work of Sergey Danilov, +Gennady Kivman and Jens Schröter. Ralph Timmermann extended it to a full global ocean – sea ice configuration in 2009. Qiang Wang rewrote its numerical algorithm and parameterizations from 2008 through 2014, which led to essentially improved numerical and physical performance. The last release of FESOM with the finite-element dynamical core is FESOM1.4 (Wang et al., 2014). +The release of AWI-CM using FESOM is by Sidorenko et al. in 2015. + + +== References == + + +== External links == +FESOM1.4 source code Archived 2018-11-03 at the Wayback Machine +FESOM2 source code +FESOM website \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Fallout_(Irish_TV_series)-0.md b/data/en.wikipedia.org/wiki/Fallout_(Irish_TV_series)-0.md new file mode 100644 index 000000000..7bf5a2444 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Fallout_(Irish_TV_series)-0.md @@ -0,0 +1,33 @@ +--- +title: "Fallout (Irish TV series)" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Fallout_(Irish_TV_series)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:13.307917+00:00" +instance: "kb-cron" +--- + +Fallout is a RTÉ two-part fictional, doom laden docudrama. It deals with the nuclear fallout following a hypothetical disaster in the Sellafield Nuclear Reprocessing Plant in Cumbria on the British coast of the Irish Sea. The docu-drama suggests that, due to a changing wind direction, Ireland would bear the brunt of the British accident. The docu-drama was based on the false premise, that such an accident as depicted in the drama could happen and that parts of Ireland would need to be evacuated following a serious accident at Sellafield. Dr Ann McGarry, chief executive of the Radiological Protection Institute of Ireland, said: "The scenario envisaged in the programme is not realistic and grossly exaggerates the amount of radioactivity that could reach Ireland. The RPII cannot envisage any realistic scenario that would cause the radiation levels in Ireland to reach the concentrations as what was depicted in the drama". Following the dramatized accident, the docu-drama depicts Irish evacuation riots, societal collapse and widespread health impacts. + + +== Episodes == + + +=== Part one === +Part One aired on 23 April 2006, and focuses on the immediate aftermath of the incident and the implications which may arise for the Irish population. The plot is released in the style of "breaking news" (from both RTÉ News and BBC News 24) and as footage captured by a documentary crew and various camera phone video clips from eyewitnesses. + + +=== Part two === +Part Two aired 24 April 2006 and is set a year later, dealing with more long-term repercussions such as the social and economic climate. The main characters are revisited and interviewed. + + +== Criticism == +Minister for the Environment, Heritage and Local Government Dick Roche criticised the show for "portraying Irish people as barbaric". The accident scenario is considered outlandish. In addition, the Irish government are currently attempting through a court action to close the Sellafield nuclear plant; the topic of the programme may be regarded as being sub judice. + +When attempting to stem leaks found in the Sellafield facility, an explosion occurs. This sets off a further chain of explosions in the HASTs (Highly Active Storage Tank), resulting in the release of a highly radioactive plume. A north-easterly wind carries this radioactive material over the Irish Sea, which hits Ireland's eastern coast, particularly County Louth and the Dublin area (Ireland's main population centre) causing widespread chaos. + +The Radiological Protection Institute of Ireland also voiced criticisms at the time of airing, Dr Ann McGarry, chief executive of the Radiological Protection Institute of Ireland, said: "The scenario envisaged in the programme is not realistic and grossly exaggerates the amount of radioactivity that could reach Ireland. The RPII cannot envisage any realistic scenario that would cause the radiation levels in Ireland to reach the concentrations as what was depicted in the drama". The RPII was also concerned that the programme appeared to suggest that evacuation would be the appropriate response to an accident at Sellafield. With Dr. McGarry explaining that International best practice indicates that evacuation would not be required as Ireland is at sufficient distance from the British nuclear facilities, that radiation levels arising from an accident would never be sufficiently high to give rise to the effects displayed in the programme. + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Formularium_Slovenicum-0.md b/data/en.wikipedia.org/wiki/Formularium_Slovenicum-0.md new file mode 100644 index 000000000..d4e8853fa --- /dev/null +++ b/data/en.wikipedia.org/wiki/Formularium_Slovenicum-0.md @@ -0,0 +1,30 @@ +--- +title: "Formularium Slovenicum" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Formularium_Slovenicum" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:46.684685+00:00" +instance: "kb-cron" +--- + +Formularium Slovenicum is Slovenian addendum to the European Pharmacopoeia. It promotes Slovenian pharmaceutical terminology and the regulations affecting the field of pharmacy in Slovenia. It has been regularly published by the Agency for Medicinal Products and Medical Devices of the Republic of Slovenia. +Slovenia does not have its own pharmacopoeia, i.e. a collection of monographs and other provisions containing legally binding regulations regarding the development, manufacture, and quality assessment of medicinal products and their ingredients as well as other information on medicinal products and their use. Since 1997, European Pharmacopoeia has been in force in the Republic of Slovenia. The alignment of provisions of the national law in the field of medicinal products and regulations at the level of the European Pharmacopoeia brought forward the need for Slovenian addendum to the European Pharmacopoeia. The committee for drafting the national addendum at the Office for Medicinal Products of the Slovenian Ministry of Health issued in June 1998 the first edition of Formularium Slovenicum. Several amendments and updated editions have followed, though the work of the committee preparing Formularium Slovenicum was interrupted between 2013 and 2018. +Formularium Slovenicum supplements European Pharmacopoeia standards and provides translations of titles, complete translations of the main monographs or their individual parts, and translations of general chapters. The chapter National monographs comprises interesting and useful monographs for Slovenian pharmacy practice that the European Pharmacopoeia does not include. It also includes the chapter Standard Terms for Pharrmaceutical Forms, Methods of Administration, and Containers. Formularium Slovenicum has an important role in the drafting, development, and promotion of Slovenian pharmaceutical terms. + + +== Editions == +The first edition has been followed by numerous amendments and updated editions: + +1st edition – June 1998, six amendments +2nd edition – 2005, five amendments +3rd edition – 2011, two amendments +4th edition – August 2018, one amendment (solely online) +5th edition – August 2020 (solely online) + + +== References == + + +== External links == +Official website \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Formulary_(pharmacy)-0.md b/data/en.wikipedia.org/wiki/Formulary_(pharmacy)-0.md new file mode 100644 index 000000000..1add53752 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Formulary_(pharmacy)-0.md @@ -0,0 +1,41 @@ +--- +title: "Formulary (pharmacy)" +chunk: 1/2 +source: "https://en.wikipedia.org/wiki/Formulary_(pharmacy)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:47.938196+00:00" +instance: "kb-cron" +--- + +A formulary is a list of pharmaceutical drugs, often decided upon by a group of people, for various reasons such as insurance coverage or use at a medical facility. Traditionally, a formulary contained a collection of formulas for the compounding and testing of medication (a resource closer to what would be referred to as a pharmacopoeia today). Today, when most prescription drugs are fully prepared by their manufacturers, the main function of a prescription formulary is to specify particular medications that are approved to be prescribed at a particular hospital, in a particular health system, or under a particular health insurance policy. The development of prescription formularies is based on evaluations of efficacy, safety, and cost-effectiveness of drugs. +Depending on the individual formulary, it may also contain additional clinical information, such as side effects, contraindications, and doses. +By the turn of the millennium, 156 countries had national or provincial essential medicines lists and 135 countries had national treatment. + +== Australia == +In Australia, where there is a public health care system, medications are subsidised under the Pharmaceutical Benefits Scheme (PBS) and medications that are available under the PBS and the indications for which they can be obtained under said scheme can be found in at least two places, the PBS webpage and the Australian Medicines Handbook. + +== Canada == +The Prescription Drug List is the national formulary that lists all medical ingredients for human and animal use available with a prescription with the exception of those under the Controlled Drugs and Substances Act. The Canadian Agency for Drugs and Technologies in Health (CADTH) is the advisory body that evaluates new medical technologies and prescription medication. Based on recommendations the provincial and territorial governments decide whether or not to implement changes to their healthcare system and public drug formularies. Provincial and territorial government provide partial prescription drug coverage and the overall drug payment is a mix of public taxation, private insurance and out-of-pocket expenses. Insurance coverage differs regionally, although each public drug coverage plan must meet standards set by the federal government. Regional health authorities are in charge of regulating and providing its residents insurance while the federal government provides insurance for specifically eligible veterans, First Nations, Inuit, Canadian Forces, federal inmates and some refugees. + +== India == +The National Formulary of India (NFI) published by Indian Pharmacopoeia Commission (IPC) is essentially meant for the guidance of the members of the medical and pharmaceutical profession; medical students, nurses and pharmacists etc. working in hospitals, dispensaries and in sales establishments. In the preparation of this Formulary, the expert opinion of medical practitioners, teachers in medicine, nurses, pharmacists etc. has been obtained. The selection of drugs for inclusion in the National Formulary has been made taking into consideration the relative advantages and disadvantages of the various drugs used in current medical practice and their availability in the country. Thus, the National Formulary of India represents a broad consensus of expert opinion in respect of drugs and their formulations and provides the physicians with carefully selected therapeutic agents of proved effectiveness which form the basis of rational drug therapy. +The National Formulary of India is an authoritative guide to prescribing, dispensing and administering medicines for healthcare professionals. It will be useful for framing national drug policies in the country. The Ministry of Health and Family Welfare, Govt. of India vide its notification F. No. X. 11035/2/06-DFQC, dated 8th May 2008 assigned this mandatory responsibility to the Indian Pharmacopoeia Commission, Ghaziabad to publish NFI on regular basis. The First Edition of NFI – National Formulary of India was published in year 1960. The IPC has published three consecutive editions of National Formulary of India since its formation. The Indian Pharmacopoeia Commission has published the 4th edition, 5th edition and 6th edition of NFI. Stakeholders may order the copy of NFI-2021 from https://www.ipc.gov.in/shop/index.php?route=product/category&path=60 . The 7th Edition of National Formulary of India (NFI-2026) is expected to release by early 2026 along with its digital version. + +=== Contents of the 6th Edition of the NFI (NFI-2021) === +34 therapeutic categories chapters including 591 drug monographs and 23 Appendices based on contemporary knowledge. +33 rational fixed-dose combinations. +The NFI is aligned with the National Health Programmes and the National List of Essential Medicines (NLEM) of India. +Important weblinks related to NLEM, drugs banned in India, NHP, drugs banned in sports, immunization schedule, wherever necessary are provided for information to readers. +Special notes on "How to use NFI?" and Salient Features of NFI are added in this edition. +Indications approved by the Indian drug regulator, clinically relevant ones, and as per standard care are included. +The term 'availability' is replaced with 'dosage forms and usual strength' +The clinically relevant precautions and contraindications are included. +The common or the serious and clinically relevant adverse effects are included. +Storage conditions for medicines are included for special cases only. +The chapter on Medicines banned in sports in the previous edition has been considered under appendices in this edition. +Considering the prevalence of diabetes in the country a separate Chapter on Management of Diabetes is included after revising completely. +A new appendix on Good Distribution Practices is incorporated. +Appendix on National Immunization Schedule and IAP Immunization Schedule is revised as per current requirement. + +== United States == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Formulary_(pharmacy)-1.md b/data/en.wikipedia.org/wiki/Formulary_(pharmacy)-1.md new file mode 100644 index 000000000..270f2ee2f --- /dev/null +++ b/data/en.wikipedia.org/wiki/Formulary_(pharmacy)-1.md @@ -0,0 +1,43 @@ +--- +title: "Formulary (pharmacy)" +chunk: 2/2 +source: "https://en.wikipedia.org/wiki/Formulary_(pharmacy)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:47.938196+00:00" +instance: "kb-cron" +--- + +In the US, where a system of quasi-private healthcare is in place, a formulary is a list of prescription drugs available to enrollees, and a tiered formulary provides financial incentives for patients to select lower-cost drugs. For example, under a 3-tier formulary, the first tier typically includes generic drugs with the lowest cost sharing (e.g., 10% coinsurance), the second includes preferred brand-name drugs with higher cost sharing (e.g., 25%), and the third includes non-preferred brand-name drugs with the highest cost-sharing (e.g., 40%). +When used appropriately, formularies can help manage drug costs imposed on the insurance policy. However, for drugs that are not on formulary, patients must pay a larger percentage of the cost of the drug, sometimes 100%. Formularies vary between drug plans and differ in the breadth of drugs covered and costs of co-pay and premiums. Most formularies cover at least one drug in each drug class, and encourage generic substitution (also known as a preferred drug list). Formularies have shown to cause issues in hospitals when patients are discharged when not aligned with outpatient drug insurance plans. + +== United Kingdom == +In the UK, the National Health Service (NHS) provides publicly funded universal health care, financed by national health insurance. Here, formularies exist to specify which drugs are available on the NHS. The two main reference sources providing this information are the British National Formulary (BNF) and the Drug Tariff. There is a section in the Drug Tariff, known unofficially as the "Blacklist", detailing medicines which are not to be prescribed under the NHS and must be paid for privately by the patient. Recommendations for additions to the NHS formulary are provided by the National Institute for Health and Care Excellence. +In addition to this, local NHS hospital trusts and Primary Care (General Practitioners) Clinical Commissioning Groups (CCGs), produce their own lists of medicines deemed preferable for prescribing within their locality or organisation; such lists are usually a subset of the more comprehensive BNF. These formularies are not absolutely binding, and physicians may prescribe a non-formulary medicine if they consider it necessary and justifiable. Often, these local formularies are shared between a Primary Care Organisation (PCO) and hospitals within that PCO's jurisdiction, in order to facilitate the procedure of transferring a patient from primary care to secondary care, thus causing fewer "interfacing" issues in the process. +As in the United States, the NHS actively encourages prescribing of generic drugs, in order to save more of the budget allocated to them by the Department of Health. + +== National formulary == +A national formulary contains a list of medicines that are approved for prescription throughout the country, indicating which products are interchangeable. It includes key information on the composition, description, selection, prescribing, dispensing and administration of medicines. Those drugs considered less suitable for prescribing are clearly identified. +Examples of national formularies are: + +Australian Pharmaceutical Formulary (APF) +Österreichisches Arzneibuch (ÖAB), the Austrian national formulary +British National Formulary (BNF) and British National Formulary for Children (BNFC) +Farmacotherapeutisch Kompas (FK), the Dutch national formulary +Formularium Nasional (Fornas), the Indonesian national formulary +Hrvatska Farmakopeja, the Croatian national formulary +National Formulary of India, India +Japan National Health Insurance Drug Price List +Pharmaceutical Schedule, New Zealand's publicly funded national formulary +United States National Formulary, later bought out and merged with the United States Pharmacopeia (USP-NF) +Farmaceutiska Specialiteter i Sverige (FASS), the Swedish national formulary. Usage of the database is free of charge and it has no promotional texts or advertising. FASS has been developed by the Swedish Association of the Pharmaceutical Industry (LIF) in close cooperation with Sweden's pharmaceutical industry, with additional assistance from the Medical Products Agency, the Pharmaceutical Benefits Board and the National Corporation of Pharmacies. Information on interactions is derived from a joint development between the Department of Pharmaceutical Biosciences at Uppsala University and the Swedish Association of the Pharmaceutical Industry (LIF). + +== See also == +Pharmacopoeia – Standard reference work on pharmaceutial drugs and compound medicines +Pharmaceutical policy – Branch of health policy + +== References == + +== External links == +A National Formulary for Canada, Department of Economics, University of Calgary, 2005 (archived 6 July 2011) +The Kazakhstan National Formulary (archived 27 March 2022) \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/From_the_Earth_to_the_Moon_(miniseries)-0.md b/data/en.wikipedia.org/wiki/From_the_Earth_to_the_Moon_(miniseries)-0.md new file mode 100644 index 000000000..8c77608c8 --- /dev/null +++ b/data/en.wikipedia.org/wiki/From_the_Earth_to_the_Moon_(miniseries)-0.md @@ -0,0 +1,49 @@ +--- +title: "From the Earth to the Moon (miniseries)" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/From_the_Earth_to_the_Moon_(miniseries)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:15.915845+00:00" +instance: "kb-cron" +--- + +From the Earth to the Moon is a 1998 American twelve-part television miniseries co-produced by Ron Howard, Brian Grazer, Tom Hanks and Michael Bostick. The series aired on HBO from April 5 to May 10, 1998. In docudrama format, it tells the story of the Apollo program during the 1960s and early 1970s. Largely based on Andrew Chaikin's 1994 book, A Man on the Moon, the series is known for its accurate telling of the story of Apollo and the special effects under visual director Ernest D. Farino. The series takes its title from, but is not based upon, Jules Verne's 1865 science fiction novel From the Earth to the Moon. +Hanks appears in every episode, introducing each of the first eleven. The twelfth and final episode, represented in pseudo-documentary format, is narrated by Blythe Danner, interspersed with a reenactment of the production of Georges Méliès' 1902 film Le Voyage dans la Lune, also in part inspired by Verne's novel. Hanks narrates and appears in these scenes as Méliès' assistant, with Tchéky Karyo as Méliès. + + +== Cast == + +The miniseries has a fairly large cast. It portrays 30 of the 32 astronauts who flew, or were preparing to fly, the 12 missions of the Apollo program. (The only two Apollo astronauts not portrayed by credited actors are Apollo 13 Command Module pilot Jack Swigert, who is heard but not seen in Episode 8, and Apollo 17 Command Module pilot Ronald Evans, who has a brief appearance in the liftoff scene of Apollo 17 in the final episode.) Members of many of the astronauts' families, and other NASA and non-NASA personnel, are also portrayed. +Several fictional (or fictionalized) characters are also included, notably television newscaster Emmett Seaborn (Lane Smith) who appears in nine of the 12 episodes. +Astronaut David Scott, from Apollo 15, was the chief technological consultant. + + +== Episodes == +The 12 episodes, each directed by a different person, use a variety of viewpoints and themes, while sequentially covering the Mercury, Gemini, and Apollo programs. Lane Smith portrays Emmett Seaborn, a seasoned reporter for a fictional television network who covers the U.S. space program from its earliest days, providing continuity for most of the episodes. + + +== Integration with existing films == +The miniseries, concentrating on the Apollo space program, was produced with an intent not to repeat other dramatic portrayals of events of the space race. +Project Mercury, which was portrayed in the 1983 film The Right Stuff, was briefly summarized in the first episode. Miniseries producers Hanks, Howard and Grazer, who had previously produced the 1995 film Apollo 13, shot the episode "We Interrupt This Program" from the perspective of the media covering that flight, as the film had already covered the story from the point of view of the crew and the mission control team. + + +== Production == +Many of the actors had opportunity to interact and form friendships with the real life astronauts they were portraying. Brett Cullen, who played Apollo 9 Command Module pilot and Apollo 15 commander David Scott, was invited to the Scott family home each time an episode he appeared in was first televised. Two short clips from the final scenes of Apollo 13 were used in "That's All There Is"; a splashdown sequence, and a view of the recovery ship USS Iwo Jima (portrayed by USS New Orleans). +The original series was shot in Super 35, intended to be viewed on standard television sets of the time in 1.33:1 aspect ratio. With the proliferation of widescreen flat-panel TV sets the series was remastered in the 1.78:1 aspect ratio and re-released in 2005 as a 5-disc DVD box set. As is the case with most material shot in this format, the widescreen framing causes the loss (in some shots) of the top and bottom parts of the frames from the original broadcast, but reveals additional information on the left and right. This is not always noticeable because of careful transfer process, but in some scenes important details are lost. For example, in the first episode, when the Gemini 8 / Agena assembly is tumbling around in space with a stuck thruster, the thruster is not visible in the new widescreen version, as it is cut off by the top of the frame. Some captions have also been compromised. +Parts of the miniseries were filmed at the Disney-MGM Studios (now Disney's Hollywood Studios) in Orlando, Florida. Scenes of the moonwalks were shot inside the blimp hangars on a former Marine base in Tustin, California. Approximately half the area inside was converted to the Moon's surface, with the remainder used to hold production trailers. To simulate lunar surface gravity, weather balloons filled with helium were attached to the backs of the actors playing the astronauts in the lunar extravehicular activity scenes, effectively reducing their weights to one-sixth. +The score of "Spider" prominently features an imitation of the main title theme from the 1963 World War II movie The Great Escape, and Tom Kelly jokes about having a crew digging a tunnel out of the Grumman plant. The episode also featured a real Apollo Lunar Module (LM-13), which had been built for the Apollo 18 mission but was never used due to budget cuts. + + +== Awards and nominations == + + +== See also == +Apollo 11 in popular culture + + +== References == + + +== External links == +From the Earth to the Moon at IMDb \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Gagarin b/data/en.wikipedia.org/wiki/Gagarin new file mode 100644 index 000000000..e69de29bb diff --git a/data/en.wikipedia.org/wiki/Geekadelphia-0.md b/data/en.wikipedia.org/wiki/Geekadelphia-0.md new file mode 100644 index 000000000..6bd1b365a --- /dev/null +++ b/data/en.wikipedia.org/wiki/Geekadelphia-0.md @@ -0,0 +1,30 @@ +--- +title: "Geekadelphia" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Geekadelphia" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:11.254524+00:00" +instance: "kb-cron" +--- + +Geekadelphia was a Philadelphia-based weblog focused on entertainment, science, technology and other related areas pertaining to the city of Philadelphia. Founded in 2007, the blog also co-hosted the Philadelphia Geek Awards with the Academy of Natural Sciences of Drexel University. The site ceased operation in November 2017, and it is no longer online. + + +== History == +Geekadelphia was founded by Tim Quirino and Eric Smith in 2007, who, according to Smith, "wanted a place to ramble about things that interested us and have a site to host whatever silly videos we'd make." Its first post was published on November 29th, 2007. In its early days, revenue earned from Geekadelphia was only enough to pay for hosting. Events on behalf of the site were created, along with a podcast with Benjamin Gilbert and a webcomic. In 2013, Geekadelphia was rebranded and incorporated in the company Analog Boys. Quirino left for San Francisco in 2014 to work as a designer for Facebook. On November 30, 2017, the site posted a blog titled 'You're Still Here? Go Home' explaining how the site has come to an end. + + +== Events == +In 2008, Geekadelphia hosted a Battlestar Galactica-themed party in Old City with The Hacktory, a Philadelphia-based organization promoting the application of technology in the arts, and Indy Hall. The site's staff decorated the Trocadero Theatre for the screenings of Jennifer's Body in 2009 and Zombieland in 2010. + + +=== Philadelphia Geek Awards === +In 2011, Geekadelphia launched the Philadelphia Geek Awards, in conjunction with the Academy of Natural Sciences of Drexel University, to honor and celebrate achievements within the Philadelphia community. Its second annual ceremony, hosted at the university, was reported to have sold over 400 in a few minutes. During its third-annual ceremony, Smith stated his criteria for geek as "more about having a hobby or a side project that you feel really passionate about, that you care so much about that you pour yourself into it." The organizers "retired" the Awards as of August 2018, citing "it was a struggle to keep the event funded well enough to operate". + + +== References == + + +== links == +Geekadelphia Blog (archived link by WebArchive, January 2019) \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Gory_Details-0.md b/data/en.wikipedia.org/wiki/Gory_Details-0.md new file mode 100644 index 000000000..1a2d927ea --- /dev/null +++ b/data/en.wikipedia.org/wiki/Gory_Details-0.md @@ -0,0 +1,46 @@ +--- +title: "Gory Details" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Gory_Details" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:39.692174+00:00" +instance: "kb-cron" +--- + +Gory Details: Adventures from the Dark Side of Science is a 2021 non-fiction book by American science journalist Erika Engelhaupt. It examines the more unsavory aspects of science, such as insects and death. The book was published by National Geographic Partners. + + +== Synopsis == +Covering a large swath of scientific fields, such as anatomy, psychology, forensics, and entomology, Erika Engelhaupt examines “the gross, the bizarre, the taboo and morbidly fascinating elements of science.” +The book is divided into six parts, titled: + +Morbid Curiosity +That's Disgusting +Breaking Taboos +Creepy Crawlies +Gross Anatomy +Mysterious Minds +Each part contains 6-8 chapters. Each individual chapter can be enjoyed as a stand-alone selection. Complex topics are made more easily accessible through black-and-white illustrations and a glow-in-the-dark cover (hardcover only). + + +== Background == +Gory Details began as a blog hosted initially by Science News and later moved to National Geographic. Engelhaupt was inspired to create the blog based on books that she had read and reviewed for Science News. She wanted to write about “weird and morbid science” and “address the things that people are afraid to talk about.” She first presented the idea as a column for the magazine and was rejected, but was then offered the opportunity to write it as a blog on the Science News website. +The book contains “updated and expanded versions of some blog posts, as well as plenty of new material.” It maintains the same concept of the blog, in that it does not merely identifies “things that are gross or scary” but it teaches “something fascinating about nature and how the world works.” + + +== Reception == +Library Journal called Gory Details, "a must-read for curious minds, trivia fans, and crime drama enthusiasts." +Chris Scott of the Chattanooga Times Free Press describes Gory Details as “the sort of book that leads not only to greater understanding of the world, but to a desire to know more - the unifying trait of scientists and those who are merely curious about their surroundings.” He appreciates that each “chapter is full of facts and profiles of the scientists who have discovered them or used them to benefit humanity.” +In an interview with Erika Engelhaupt, Carter Wilson of Making It Up podcast praised the author for how she “breaks it all down with humor” and how that approach “softens the whole thing”, so that “the more you learn about it, the less it comes off as gross anymore.” +Rebecca Bennett, writing for the Austin American-Statesman, finds Gory Details to be a combination of “fascinating fact, compelling descriptions and humor.” She describes Engelhaupt’s tone as casual and relatable, and the topics covered as “interesting and readable.” +Book Riot's Rachel Brittain included Gory Details on the list of "25 Must-Read Nonfiction Books" and associate editor Danika Ellis found Engelhaupt's work to be "filled to the brim with far out facts." + + +== Author biography == + +Erika Engelhaupt was born in Kansas City, Missouri. She got her curiosity for science from her father who was an electrochemist. She received a Master of Science degree in biology from Tulane University and an M.S. degree in environmental studies from the University of Colorado Boulder. While pursuing a PhD in Biology at the University of Colorado Boulder, she determined that she “didn't really want to finish a whole PhD” but instead “really wanted to go straight into science writing and science journalism.” +Her work as a freelance science writer has appeared in “National Geographic, NPR, Scientific American, Popular Mechanics, Science News, The Philadelphia Inquirer, and Boulder Daily Camera.” Between 2009 and 2014, Engelhaupt was an editor at Science News and later worked as an online science editor at National Geographic. At CSICon 2023, she gave a talk titled "Disgust: How an Overlooked Emotion Meddles With Our Minds" based on content covered in Gory Details. She splits her time between Knoxville, Tennessee and Washington, DC. + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Grandma_Got_STEM-0.md b/data/en.wikipedia.org/wiki/Grandma_Got_STEM-0.md new file mode 100644 index 000000000..4c07af39d --- /dev/null +++ b/data/en.wikipedia.org/wiki/Grandma_Got_STEM-0.md @@ -0,0 +1,21 @@ +--- +title: "Grandma Got STEM" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Grandma_Got_STEM" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:12.420729+00:00" +instance: "kb-cron" +--- + +Grandma Got STEM is a blog by Rachel Levy, a mathematician at Harvey Mudd College, about earlier generations of women in science, technology, engineering, and mathematics (STEM). Levy founded the blog in March 2013, and by June 2013 had already accumulated 100 posts to it. +The blog is aimed at a general audience. +Its entries include pictures and stories about women who worked in STEM fields, and are intended to counter stereotypes of older women as being technologically inept, as well as to inspire future generations of women in STEM. +As the name of the blog suggests, the women featured on the blog are generally old enough to be grandmothers, although not all of them had children. Although many famous researchers are included, the blog posts also feature women who worked at lower-level teaching and laboratory assistant positions in STEM. + + +== References == + + +== External links == +Grandma Got STEM \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Hawking_(2004_film)-0.md b/data/en.wikipedia.org/wiki/Hawking_(2004_film)-0.md new file mode 100644 index 000000000..4f25d3120 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Hawking_(2004_film)-0.md @@ -0,0 +1,40 @@ +--- +title: "Hawking (2004 film)" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Hawking_(2004_film)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:18.382720+00:00" +instance: "kb-cron" +--- + +Hawking is a 2004 biographical drama television film directed by Philip Martin and written by Peter Moffat. Starring Benedict Cumberbatch, it chronicles Stephen Hawking's early years as a PhD student at the University of Cambridge, following his search for the beginning of time, and his struggle against motor neurons disease. It premiered in the UK in April 2004. +The film received positive reviews, with critics particularly lauding Cumberbatch's performance as Hawking. It received two British Academy Television Awards nominations: Best Single Drama and Best Actor (Cumberbatch). Cumberbatch won the Golden Nymph for Best Performance by an Actor in a TV Film or Miniseries. +Cumberbatch's portrayal of Hawking was the first portrayal of the physicist on screen not by himself. + + +== Plot == +At Stephen Hawking's 21st birthday party he meets a new friend, Jane Wilde. There is a strong attraction between the two and Jane is intrigued by Stephen's talk of stars and the universe, but realises that there is something very wrong with Stephen when he suddenly finds that he is unable to stand up. A stay in hospital results in a distressing diagnosis. Stephen has motor neurone disease and doctors don't expect him to survive for more than two years. Stephen returns to Cambridge where the new term has started without him. But he cannot hide from the reality of his condition through work because he can't find a subject for his PhD. While his colleagues throw themselves into academic and college life, Stephen's life seems to have been put on hold. He rejects the help of his supervisor Dennis Sciama and sinks into a depression. It is only Stephen's occasional meetings with Jane and her faith in him that seem to keep him afloat. The prevailing theory in cosmology at the time is Steady State, which argues that the universe had no beginning – it has always existed, and always will – and Steady State is dominated by Professor Fred Hoyle, a plain-speaking Yorkshireman, and one of the first science TV pundits. +Stephen gets an early glimpse of a paper by Hoyle that is to be presented at a Royal Society lecture. He works through the calculations, identifies a mistake, and publicly confronts Hoyle after he has finished speaking. The row causes a stir in the department but, more importantly, it seems to give Stephen the confidence to get started on his own work. At almost the same time Stephen is introduced to a new way of thinking about his subject by another physicist, Roger Penrose. Topology is an approach that uses concepts of shape rather than equations to think about the nature of the universe, and this proves to be the perfect tool for Stephen, who is starting to find it very difficult to write. Penrose's great passion is the fate of dying stars. When a star comes to the end of its life, it begins to collapse in on itself. His calculations suggest something extraordinary. The collapse of the dying star appears to continue indefinitely, until the star is infinitely dense, forming a black hole in space. And at the heart of this black hole, Penrose shows, is something scientists call a singularity. It is this which leads Stephen to his PhD subject. He has always had a niggling scepticism about Steady State Theory, and now he can begin to see a way of explaining the revolutionary and highly controversial idea that the universe might have had a beginning. Sciama is sceptical but supportive – glad to see his student fired up and ready to work. Meanwhile, Stephen's condition continues to decline, he writes and walks with difficulty and his speech is starting to slur. But he now has a focus for his energies and, with the support of Jane, enters a new phase. He also commits to his relationship with her, asking her to marry him and in doing so exhibiting a defiant determination to survive. +With his mind fired up, Stephen begins to work away at the implications of Penrose's discovery and starts to home in on the idea of a singularity. With remarkable insight – a real Eureka moment – he asks himself: what would happen if you ran Penrose's maths backwards? Instead of something collapsing into nothingness, what if nothingness exploded into something? And what if you applied this not to a star but to the whole universe? Answer: the universe really could have originated in a big bang. At last, Stephen enters a period of feverish academic work. He applies Penrose's theorems for collapsing stars to the universe itself. Justifying Sciama's faith in him, he produces a PhD of real brilliance and profound implications. In theory, at least, the big bang could have happened. Two years after his initial diagnosis, Stephen is not only still very much alive, but has played a part in a great scientific breakthrough which revolutionises the way people think about the universe. Today, the scientific consensus is that the universe started with a big bang: billions of years ago, a cosmic explosion brought space and time into existence. +A secondary, interwoven storyline follows a different but connected scientific quest. Unbeknownst to Hawking, just as he was being diagnosed in 1963, two American scientists were embarking on their own scientific mission. Their research was to produce hard evidence to support Hawking's theoretical work. Arno Allan Penzias and Robert Woodrow Wilson are encountered in a hotel room in Stockholm in 1978. They are being interviewed about their discovery on the eve of receiving the Nobel Prize for Physics. They describe how, in the hills above New Jersey, they scanned the skies with a radio-telescope, and began to pick up a strange radio signal from space. In time, the two scientists came to realise that they had detected the left-over heat of the first, ancient explosion that had created the universe. They had found the physical proof of the big bang. + + +== Cast == + + +== Reception == + + +=== Accolades === +Hawking received two nominations at the 2005 British Academy Television Awards: Best Single Drama and Best Actor (Cumberbatch). At the Monte-Carlo Television Festival, Benedict Cumberbatch won the Golden Nymph for Best Performance by an Actor in a TV film or miniseries. + + +== Notes == + + +== References == + + +== External links == +Hawking at IMDb \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Hiroshima b/data/en.wikipedia.org/wiki/Hiroshima new file mode 100644 index 000000000..e69de29bb diff --git a/data/en.wikipedia.org/wiki/Hiroshima_(1995_film)-0.md b/data/en.wikipedia.org/wiki/Hiroshima_(1995_film)-0.md new file mode 100644 index 000000000..c3035ad15 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Hiroshima_(1995_film)-0.md @@ -0,0 +1,50 @@ +--- +title: "Hiroshima (1995 film)" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Hiroshima_(1995_film)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:21.047019+00:00" +instance: "kb-cron" +--- + +Hiroshima is a 1995 Japanese-Canadian war drama film directed by Koreyoshi Kurahara and Roger Spottiswoode about the decision-making processes that led to the dropping of the atomic bombs by the United States on the Japanese cities of Hiroshima and Nagasaki toward the end of World War II. The three-hour film was made for television (Showtime Network) and had no theatrical release. +A combination of dramatization, historical footage, and eyewitness interviews, the film alternates between documentary footage and dramatic recreations. The dramatizations and most of the original footage are presented as sepia-toned images, serving to blur the distinction between them. The languages are English and Japanese, with subtitles, and the actors are largely Canadian and Japanese. + + +== Synopsis == +The film opens on 12 April 1945 with the death of Franklin Roosevelt and the succession of Harry Truman to the presidency. In Europe, the Germans are close to surrender, but in the Pacific the bloody battle for Okinawa is still under way. American casualties have almost reached 900,000, with Japanese casualties at 1.1 million; 8 million Asian civilians have died in the war that began with Japan's 1931 invasion of Manchuria. +The new president knows nothing about the nuclear weapons being developed at Los Alamos, and he must decide on whether to use them and how. When nuclear physicist Leo Szilard delivers a petition signed by 73 scientists urging the president not to deploy the bomb, U.S. Secretary of State James F. Byrnes tells him: "You do not spend two billion dollars and then show them [American voters] nothing." Also urging deployment is Maj. Gen. Leslie Groves, director of the Manhattan Project. The Interim Committee appointed by Truman recommends unanimously that he use the bomb on "war plants surrounded by worker housing", without warning. General George Marshall lays out plans for the invasion of Kyūshū in November and Honshū in March 1946. +In Japan, Minister of War General Anami Korechika argues that the homeland must be defended. The voice of reason is the new civilian prime minister, Kantarō Suzuki. In Tokyo, Admiral Yonai Mitsumasa assures the cabinet of victory. +On July 16, the Trinity test shows that a plutonium bomb (Fat Man) is feasible and that a nuclear blast is even more powerful than scientists predicted. The uranium bomb (Little Boy, which is untested but is expected to work) leaves Los Alamos for Tinian island in the Pacific. At the Potsdam conference, Joseph Stalin promises to join the war against Japan. Winston Churchill urges Truman to use the bomb to constrain Russian expansion. The Allied leaders deliver an ultimatum to Japan "to give them one last chance." +Truman strikes Kyoto off the target list, leaving Hiroshima as the primary target. The Enola Gay makes the drop on the morning of August 6, 1945. On August 9, the Soviet Union invades Manchuria and the Fat Man plutonium bomb devastates Nagasaki. Hirohito finally intervenes, telling the cabinet that Japan "must endure the unendurable" and surrender. Young army officers urge General Anami to join them in a military coup, but he tells them: "The emperor has spoken; we must obey him." On August 15, the emperor's surrender message is broadcast to Japan, and Anami commits ritual suicide. + + +== Reception == +Though not widely reviewed, Hiroshima was praised online: "Fascinating, and surprisingly ambivalent, docudrama rehashes familiar terrain with remarkable freshness precisely because of the emphasis on the politicians (rather than on the scientists), the bi-national approach, and an odd mixing of dramatization, newsreel footage, and even a few talking-head interviews with people who were there." + + +== Awards == +12th Gemini Awards, Toronto: Best Dramatic TV Movie or Mini-Series, 1998 +12th Gemini Awards, Toronto: Best Direction in a Dramatic Program or Mini-Series, Roger Spottiswoode, 1998 +12th Gemini Awards, Toronto: Best Performance by an Actor in a Leading Role in a Dramatic Program or Mini-Series, Kenneth Welsh, 1998 +Humanitas Prize, USA: Writing Award, PBS/Cable Television, to John Hopkins & Toshiro Ishido 1997 +48th Primetime Emmy Awards, Los Angeles: Nominee: Outstanding Miniseries, 1996 + + +== Cast == + + +== See also == +Atomic bombings of Hiroshima and Nagasaki +Surrender of Japan +List of historical drama films +List of historical drama films of Asia + + +== References == + + +== External links == +Hiroshima at IMDb +Hiroshima review, Variety, 4 August 1995 at Internet Archive. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Hostile_Waters_(film)-0.md b/data/en.wikipedia.org/wiki/Hostile_Waters_(film)-0.md new file mode 100644 index 000000000..3670ceded --- /dev/null +++ b/data/en.wikipedia.org/wiki/Hostile_Waters_(film)-0.md @@ -0,0 +1,81 @@ +--- +title: "Hostile Waters (film)" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Hostile_Waters_(film)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:23.327466+00:00" +instance: "kb-cron" +--- + +Hostile Waters is a British 1997 television film about the loss of the Soviet Navy's K-219, a Yankee I class nuclear ballistic missile sub. The film stars Rutger Hauer as the commander of K-219 and claims to be based on the true story, also described in the 1997 book of the same name. The film was produced by World Productions for the BBC and HBO, in association with Invision Productions and UFA Filmproduktions. It was written by Troy Kennedy Martin and directed by David Drury, and was first transmitted on BBC One on 26 July 1997. + + +== Plot == +In 1986, the Soviet Navy submarine K-219 performs a Crazy Ivan, and USS Aurora collides with her, causing a rupture of the seal on one of its ballistic missile tubes. The leaking seawater causes a corrosive reaction which floods the sub with toxic gas. The corrosive reaction starts a fire that floods the sub with more toxic gas and smoke. +The captain surfaces the boat, moves the crew out to the deck, and attempts to vent the sub. The chief engineer informs the captain that the fire may cook off the nukes and cause a nuclear explosion. The launch doors are opened on the sub to vent smoke. +Aurora ascertains that a fire is aboard K-219, and informs the Pentagon. The Pentagon, fearing radiological contamination of the Eastern Seaboard, orders Aurora to prepare to sink K-219. The fact that the launch doors are open on the SLBMs causes consternation in Washington D.C., with calls for the immediate sinking of the sub, should it appear to be preparing to launch. +The captain of K-219 prepares a bold plan to dive with the launch doors open, to flood the missile bay and quench the fires. As the captain dives the sub, Aurora prepares to fire, assuming K-219 is setting about to launch its missiles. After a brief but heated argument the U.S. commander is convinced to wait before launching and realises that the Soviet sub is diving, rather than launching its SLBMs. +K-219's tactic works, and the sub resurfaces with the fires out. A new crisis develops: Both nuclear reactors are overheating, and the cooling rods must be lowered manually by two crew members who have only limited oxygen left. The rods are lowered, and both reactors are shut down, averting disaster, but one crew member remains locked inside the reactor room, running out of oxygen. With seawater flooding the submarine, the captain of K-219 decides to abandon ship. Throughout the crisis, Washington insists that no information on the possibility of nuclear fallout along the eastern American coastline be leaked to the Governors and no evacuation plans be activated to protect the population, in order not to derail the forthcoming Reykjavik Summit between Soviet leader Mikhail Gorbachev and U.S. President Ronald Reagan. +Capt. Britanov and his surviving crew members return safely to Moscow with some crew decorated and he being dismissed from the navy. The Reykjavik Summit takes place as planned. +The film's postscript details that as a legacy almost a decade after the end of the Cold War, fifty one nuclear warheads and seven nuclear reactors from nuclear submarines litter the North Atlantic ocean floor. + + +== Cast == +Rutger Hauer as Captain Igor Britanov +Martin Sheen as Aurora Skipper +Max von Sydow as Admiral Chernavin +Colm Feore as Pshenishny +Rob Campbell as Sergei Preminin +Harris Yulin as Admiral Quinn +Regina Taylor as Lieutenant Curtis +John Rothman as Aurora Executive Officer +Michael Attwell as Kuzmenko +Dominic Monaghan as Sasha +Peter Guinness as Vladimirov +James E. Kerr as Aznabaev +Alexis Denisof as John Baker +Seamus McQuade as Helmsman +Paul Birchard as Torpedo Chief +Oliver Marlo as Doctor +Mark Drewry as Petrachkov +Denzil Kilvington as Volnigbirov +Garry Cooper as Gennady +Frank Baker as Pumps +Richard Graham as Belikov +Joachim Paul Assböck as Tigran Gasparian +Alexander Wachholz as Martinov +David King as Admiral 2nd Class +Todd Boyce as Larry Brock +Michael Shannon as Admiral +Sanja Spengler as Britanov's Wife +Philip Martin Brown as Cook +J.J. Gordon as Officer 4 +Lawrence Elman as Officer +Erik Hansen as Naval Marshall +William Marsh as Acoustics Officer +Rainer Sellien as Technician +Norbert Tefelski as Admiral / Engineer +Felix zu Knyphausen as Sonar Operator +Frank Witter as Russian Submarine Soldier (uncredited) + + +== Development == +The film was Troy Kennedy Martin's first work for British television in 12 years, since Edge of Darkness. HBO's involvement made the project financially possible, but the US network required American characters to be at the centre of the film, though without any named after real Americans, for fear of potential legal action: Kennedy Martin's script went through ten versions. The American submarine involved (in the film's version of events), the Augusta, is called the Aurora in the film. + + +== Reception == +The film screened at 9pm on BBC One on 26 July 1997. Ahead of broadcast, the United States Navy's chief of information denied the story of a collision with K-219: "The US Navy normally does not comment on submarine operations, but in this case, because the scenario is so outrageous, the US Navy is compelled to respond." +John Preston wrote a highly positive review for The Sunday Telegraph: "it had a terrific cast, must have cost a fortune to make and proved to be the most gripping thing I've seen since – since Edge of Darkness". He called Hauer "better than he's been in decades". In a tongue-in-cheek review, Jim Shelley in The Guardian also praised Hauer's performance: "Rutger saunters through it all with considerable aplomb, bestowing upon even his most staccato speeches a kind of suave grandeur, like Clark Gable in The Misfits." The Sunday Times was dismissive: "Given the scale of the crisis and the nautical setting, the language is incredibly mild. However, a few days spent studying nuclear physics and post-war submarine design prior to viewing may increase enjoyment." +HBO screened the film a few hours later, at 9pm. Variety wrote that "the characters are simplistically drawn, which, for this genre, is not necessarily a bad thing" but praised Hauer's acting and the technical aspects. The New York Times wrote that it delivered "first-rate dramatic tension. Mr. Hauer is quietly powerful as Captain Britanov... Nothing much happens on the American sub, so Martin Sheen's role as its captain consists mainly of looking worried. But he does it with thrilling understatement". + + +== Lawsuit == +Igor Britanov himself took out a lawsuit against HBO's parent company Warner Bros., alleging that the film-makers had not sought his permission to portray him and that the film made him look incompetent. After three years of hearings, in 2004 an American court found in his favour and awarded him damages: Britanov declined to say how much, but Russian media reported this as tens of thousands of dollars. In a statement, Britanov said: "A submarine with open hatches would sink to the bottom like a stone and I'm already sick of explaining to my submariner colleagues that I did nothing of the sort". + + +== References == + + +== External links == +Hostile Waters at IMDb \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Inferior_(book)-0.md b/data/en.wikipedia.org/wiki/Inferior_(book)-0.md index f615111ca..bb82863c5 100644 --- a/data/en.wikipedia.org/wiki/Inferior_(book)-0.md +++ b/data/en.wikipedia.org/wiki/Inferior_(book)-0.md @@ -4,7 +4,7 @@ chunk: 1/1 source: "https://en.wikipedia.org/wiki/Inferior_(book)" category: "reference" tags: "science, encyclopedia" -date_saved: "2026-05-05T07:09:40.781940+00:00" +date_saved: "2026-05-05T07:37:40.982637+00:00" instance: "kb-cron" --- diff --git a/data/en.wikipedia.org/wiki/Intertidal_zone-0.md b/data/en.wikipedia.org/wiki/Intertidal_zone-0.md new file mode 100644 index 000000000..65cd02cef --- /dev/null +++ b/data/en.wikipedia.org/wiki/Intertidal_zone-0.md @@ -0,0 +1,24 @@ +--- +title: "Intertidal zone" +chunk: 1/2 +source: "https://en.wikipedia.org/wiki/Intertidal_zone" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:11.460624+00:00" +instance: "kb-cron" +--- + +The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various species of life, such as sea stars, sea urchins, and many species of coral with regional differences in biodiversity. Sometimes it is referred to as the littoral zone or seashore, although those can be defined as a wider region. +The intertidal zone also includes steep rocky cliffs, sandy beaches, bogs or wetlands (e.g., vast mudflats). This area can be a narrow strip, such as in Pacific islands that have only a narrow tidal range, or can include many meters of shoreline where shallow beach slopes interact with high tidal excursion. The peritidal zone is similar but somewhat wider, extending from above the highest tide level to below the lowest. Organisms in the intertidal zone are well-adapted to their environment, facing high levels of interspecific competition and the rapidly changing conditions that come with the tides. The intertidal zone is also home to several species from many different phyla (Porifera, Annelida, Coelenterata, Mollusca, Arthropoda, etc.). +The water that comes with the tides can vary from brackish waters, fresh with rain, to highly saline and dry salt, with drying between tidal inundations. Wave splash can dislodge residents from the littoral zone. With the intertidal zone's high exposure to sunlight, the temperature can range from very hot with full sunshine to near freezing in colder climates. Some microclimates in the littoral zone are moderated by local features and larger plants such as mangroves. Adaptations in the littoral zone allow the utilization of nutrients supplied in high volume on a regular basis from the sea, which is actively moved to the zone by tides. The edges of habitats, in this case the land and sea, are themselves often significant ecosystems, and the littoral zone is a prime example. +A typical rocky shore can be divided into a spray zone or splash zone (also known as the supratidal zone), which is above the spring high-tide line and is covered by water only during storms, and an intertidal zone, which lies between the high and low tidal extremes. Along most shores, the intertidal zone can be clearly separated into the following subzones: high tide zone, middle tide zone, and low tide zone. The intertidal zone is one of a number of marine biomes or habitats, including estuaries, the neritic zone, the photic zone, and deep zones. + +== Zonation == + +Marine biologists divide the intertidal region into three zones (low, middle, and high), based on the overall average exposure of the zone. The low intertidal zone, which borders on the shallow subtidal zone, is only exposed to air at the lowest of low tides and is primarily marine in character. The mid intertidal zone is regularly exposed and submerged by average tides. The high intertidal zone is only covered by the highest of the high tides, and spends much of its time as terrestrial habitat. The high intertidal zone borders on the splash zone (the region above the highest still-tide level, but which receives wave splash). On shores exposed to heavy wave action, the intertidal zone will be influenced by waves, as the spray from breaking waves will extend the intertidal zone. +Depending on the substratum and topography of the shore, additional features may be noticed. On rocky shores, tide pools form in depressions that fill with water as the tide rises. Under certain conditions, such as those at Morecambe Bay, quicksand may form. + +== Low tide zone (lower littoral) == +This subregion is mostly submerged – it is only exposed at the point of low tide and for a longer period of time during extremely low tides. This area is teeming with life; the most notable difference between this subregion and the other three is that there is much more marine vegetation, especially seaweeds. There is also a great biodiversity. Organisms in this zone generally are not well adapted to periods of dryness and temperature extremes. Some of the organisms in this area are abalone, sea anemones, brown seaweed, chitons, crabs, green algae, hydroids, isopods, limpets, mussels, nudibranchs, sculpin, sea cucumber, sea lettuce, sea palms, starfish, sea urchins, shrimp, snails, sponges, surf grass, tube worms, and whelks. Creatures in this area can grow to larger sizes because there is more available energy in the localized ecosystem. Also, marine vegetation can grow to much greater sizes than in the other three intertidal subregions due to the better water coverage. The water is shallow enough to allow plenty of sunlight to reach the vegetation to allow substantial photosynthetic activity, and the salinity is at almost normal levels. This area is also protected from large predators such as fish because of the wave action and the relatively shallow water. + +== Ecology == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Intertidal_zone-1.md b/data/en.wikipedia.org/wiki/Intertidal_zone-1.md new file mode 100644 index 000000000..5ffc396a2 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Intertidal_zone-1.md @@ -0,0 +1,42 @@ +--- +title: "Intertidal zone" +chunk: 2/2 +source: "https://en.wikipedia.org/wiki/Intertidal_zone" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:11.460624+00:00" +instance: "kb-cron" +--- + +The intertidal region is an important model system for the study of ecology, especially on wave-swept rocky shores. The region contains a high diversity of species, and the zonation created by the tides causes species ranges to be compressed into very narrow bands. This makes it relatively simple to study species across their entire cross-shore range, something that can be extremely difficult in, for instance, terrestrial habitats that can stretch thousands of kilometres. Communities on wave-swept shores also have high turnover due to disturbance, so it is possible to watch ecological succession over years rather than decades. +The burrowing invertebrates that make up large portions of sandy beach ecosystems are known to travel relatively great distances in cross-shore directions as beaches change on the order of days, semilunar cycles, seasons, or years. The distribution of some species has been found to correlate strongly with geomorphic datums such as the high tide strand and the water table outcrop. +Since the foreshore is alternately covered by the sea and exposed to the air, organisms living in this environment must be adapted to both wet and dry conditions. Intertidal zone biomass reduces the risk of shoreline erosion from high intensity waves. Typical inhabitants of the intertidal rocky shore include sea urchins, sea anemones, barnacles, chitons, crabs, isopods, mussels, starfish, and many marine gastropod molluscs such as limpets and whelks. Sexual and asexual reproduction varies by inhabitants of the intertidal zones. +Humans have historically used intertidal zones as foraged food sources during low tide. Migratory birds also rely on intertidal species for feeding areas because of low water habitats consisting of an abundance of mollusks and other marine species. + +== Legal issues == + +As with the dry sand part of a beach, legal and political disputes can arise over the ownership and use of the foreshore. One recent example is the New Zealand foreshore and seabed controversy. In legal discussions, the foreshore is often referred to as the wet-sand area. + +For privately owned beaches in the United States, some states such as Massachusetts use the low-water mark as the dividing line between the property of the State and that of the beach owner; however the public still has fishing, fowling, and navigation rights to the zone between low and high water. Other states such as California use the high-water mark. +In the United Kingdom, the foreshore is generally deemed to be owned by the Crown, with exceptions for what are termed several fisheries, which can be historic deeds to title, dating back to King John's time or earlier, and the Udal Law, which applies generally in Orkney and Shetland. +In Greece, according to the L. 2971/01, the foreshore zone is defined as the area of the coast that might be reached by the maximum climbing of the waves on the coast (maximum wave run-up on the coast) in their maximum capacity (maximum referring to the "usually maximum winter waves" and of course not to exceptional cases, such as tsunamis). The foreshore zone, a part of the exceptions of the law, is public, and permanent constructions are not allowed on it. In Italy, about half the shoreline is owned by the government but leased to private beach clubs called lidos. +In the East African and West Indian Ocean, intertidal zone management is often neglected of being a priority due to there being no intent for collective economic productivity. According to workshops performing questionaries, it is stated that eighty-six percent of respondents believe mismanagement of mangrove and coastal ecosystems are due to lack of knowledge to steward the ecosystems, yet forty-four percent of respondents state that there is a fair amount of knowledge used in those regions for fisheries. + +== Threats == + +Intertidal zones are sensitive habitats with an abundance of marine species that can experience ecological hazards associated with tourism and human-induced environmental impacts. A variety of other threats that have been summarized by scientists include nutrient pollution, overharvesting, habitat destruction, and climate change. Habitat destruction is advanced through activities including harvesting fisheries with drag nets and a neglect of the sensitivity of intertidal zones. + +== Gallery == + +== See also == +Ballantine Scale +Ecological forecasting +Littoral series +NaGISA +Shorezone +Tidelands + +== References == + +== External links == +Watch the online documentary The Intertidal Zone \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Island-0.md b/data/en.wikipedia.org/wiki/Island-0.md new file mode 100644 index 000000000..444ff5ced --- /dev/null +++ b/data/en.wikipedia.org/wiki/Island-0.md @@ -0,0 +1,31 @@ +--- +title: "Island" +chunk: 1/5 +source: "https://en.wikipedia.org/wiki/Island" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:12.739706+00:00" +instance: "kb-cron" +--- + +An island or isle is a piece of land, distinct from a continent, completely surrounded by water. There are continental islands, which were formed by being split from a continent by plate tectonics, and oceanic islands, which have never been part of a continent. Oceanic islands can be formed from volcanic activity, grow into atolls from coral reefs, and form from sediment along shorelines, creating barrier islands. River islands can also form from sediment and debris in rivers. Artificial islands are those made by humans, including small rocky outcroppings built out of lagoons and large-scale land reclamation projects used for development. +Islands are host to diverse plant and animal life. Oceanic islands have the sea as a natural barrier to the introduction of new species, causing the species that do reach the island to evolve in isolation. Continental islands share animal and plant life with the continent they split from. Depending on how long ago the continental island formed, the life on that island may have diverged greatly from the mainland due to natural selection. +Humans have lived on and traveled between islands for thousands of years at a minimum. Some islands became host to humans due to a land bridge or a continental island splitting from the mainland, or by boat travel. In the far north or south some islands are joined by seasonal or glacial ice. Today, up to 10% of the world's population lives on islands. Islands are popular targets for tourism due to their perceived natural beauty, isolation, and unique cultures. +Islands became the target of colonization by Europeans, resulting in the majority of islands in the Pacific being put under European control. Decolonization has resulted in some but not all island nations becoming self-governing, with lasting effects related to industrialisation, invasive species, nuclear weapons testing, and tourism. Islands and island countries are threatened by climate change. Sea level rise threatens to submerge nations such as Maldives, the Marshall Islands, and Tuvalu completely. Increases in the frequency and intensity of tropical cyclones can cause widespread destruction of infrastructure and animal habitats. Species that live exclusively on islands are some of those most threatened by extinction. Some islands can be a disputed territory like Taiwan which China claims. + +== Definition == + +An island is an area of land surrounded by water on all sides that is distinct from a continent. There is no standard of size that distinguishes islands and continents. Continents have an accepted geological definition – they are the largest landmass of a particular tectonic plate. Islands can occur in any body of water, including lakes, rivers, seas. Low-tide elevations, areas of land that are not above the surface during a high tide, are generally not considered islands. Islands that have been bridged or otherwise joined to a mainland with land reclamation are sometimes considered "de-islanded", but not in every case. + +== Etymology == +The word island derives from Middle English iland, from Old English igland, itself from ig or ieg, similarly meaning 'island' when used independently, and with the suffix -land carrying its contemporary meaning. Old English ieg is actually a cognate of Swedish ö and German Aue, and more distantly related to Latin aqua (water). +The spelling of the word with ⟨s⟩ was modified in the 15th century because of a false etymology caused by an association with the Old French loanword isle, which itself comes from the Latin word insula. + +== Geology == + +=== Formation in oceans === +Islands often are found in archipelagos or island chains, which are collections of islands. These chains are thought to form from volcanic hotspots, areas of the lithosphere where the mantle is hotter than the surrounding area. These hotspots would give rise to volcanoes whose lava would form the rock the islands are made of. For some islands, the movement of tectonic plates above stationary hotspots would form islands in a linear chain, with the islands further away from the hotspot being progressively older and more eroded, before disappearing under the sea entirely. An example is the Hawaiian Islands, with the oldest island being 25 million years old, and the youngest, Hawaii, still being an active volcano. However, not all island chains are formed this way. Some may be formed all at once by fractures in the tectonic plates themselves, simultaneously creating multiple islands. One supporting piece of evidence is that of the Line Islands, which are all estimated to be 8 million years old, rather than being different ages. +Other island chains form due to being separated from existing continents. The Japanese archipelago may have been separated from Eurasia due to seafloor spreading, a phenomenon where new oceanic crust is formed, pushing away older crust. Islands sitting on the continental shelf may be called continental islands. Other islands, like those that make up New Zealand, are what remains of continents that shrank and sunk beneath the sea. It was estimated that Zealandia, the continent-like area of crust that New Zealand sits on, has had 93% of its original surface area submerged. +Some islands are formed when coral reefs grow on volcanic islands that have submerged beneath the surface. When these coral islands encircle a central lagoon, the island is known as an atoll. The formation of reefs and islands related to those reefs is aided by the buildup of sediment in shallow patches of water. In some cases, tectonic movements lifting a reef out of the water by as little as 1 meter can cause sediment to accumulate and an island to form. +Barrier islands are long, sandy bars that form along shorelines due to the deposition of sediment by waves. These islands erode and grow as the wind and waves shift. Barrier islands have the effect of protecting coastal areas from severe weather because they absorb some of the energy of large waves before they can reach the shore. +Antarctic islands, are sometimes permanently connected to another land mass by sea or glacial ice. An example of this is Ross Island in Antarctica. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Island-1.md b/data/en.wikipedia.org/wiki/Island-1.md new file mode 100644 index 000000000..500184324 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Island-1.md @@ -0,0 +1,32 @@ +--- +title: "Island" +chunk: 2/5 +source: "https://en.wikipedia.org/wiki/Island" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:12.739706+00:00" +instance: "kb-cron" +--- + +=== Formation in freshwater === +A fluvial island is an island that forms from the erosion and sedimentation of debris in rivers; almost all rivers have some form of fluvial islands. These islands may only be a few meters high, and are usually temporary. Changes in the flow speed, water level, and sediment content of the river may affect the rate of fluvial island formation and depletion. Permanent river islands also exist, the largest of which (that is completely inland) is Bananal Island in the Tocantins of Brazil, which has a maximum width of 55 kilometers. +Lakes form for a variety of reasons, including glaciers, plate tectonics, and volcanism. Lake islands can form as part of these processes. + +== Life on islands == +The field of insular biogeography studies the ecological processes that take place on islands, with a focus on what factors effect the evolution, extinction, and richness of species. Scientists often study islands as an isolated model of how the process of natural selection takes place. Island ecology studies organisms on islands and their environment. It has yielded important insights for its parent field of ecology since the time of Charles Darwin. + +=== Endemism === + +In biology, endemism is defined as the phenomenon where species or genus is only found in a certain geographical area. Islands isolate land organisms from others with water, and isolate aquatic organisms living on them with land. Island ecosystems have the highest rates of endemism globally. This means that islands contribute heavily to global biodiversity. Areas with high lives of biodiversity are a priority target of conservation efforts, to prevent the extinction of these species. Despite high levels of endemism, the total species richness, the total number of unique species in a region, is lower on islands than on mainlands. The level of species richness on islands is proportional to the area of that island, a phenomenon known as the species-area relationship. This is because larger areas have more resources and thus can support more organisms. Populations with a higher carrying capacity also have more genetic diversity, which promotes speciation. + +=== Dispersal === + +Oceanic islands, ones that have never been connected to shore, are only populated by life that can cross the sea. This means that any animals present on the island had to have flown there, in the case of birds or bats, were carried by such animals, or were carried in a sea current in what is known as a "rafting event". This phenomenon is known as oceanic dispersal. Tropical cyclones have the capacity to transport species over great distances. Animals like tortoises can live for weeks without food or water, and are able to survive floating on debris in the sea. One case study showed that in 1995, fifteen iguanas survived a 300 km journey to Anguilla in the Caribbean, an island which no iguana had lived on previously. They survived floating on a mass of uprooted trees from a storm. Plant species are thought to be able to travel great distances of ocean. New Zealand and Australia share 200 native plant species, despite being separated by 1500 km. +Continental islands, islands that were at one point connected to a continent, are expected to share a common history of plant and animal life up until the point that the island broke away from the continent. For example, the presence of freshwater fish on an island surrounded by ocean would indicate that it once was attached to a continent, since these fish cannot traverse the ocean on their own. Over the course of time, evolution and extinction changes the nature of animal life on a continental island, but only once it splits from the mainland. An example is that of the southern beech, a tree that is present in Australia, New Zealand, parts of South American, and New Guinea, places that today are geographically distant. A possible explanation for this phenomenon is that these landmasses were once all part of the continent Gondwana and separated by tectonic drift. However, there are competing theories that suggest this species may have reached faraway places by way of oceanic dispersal. + +=== Evolution on island groups === + +Species that colonize island archipelagos exhibit a specific property known as adaptive radiation. In this process, a species that arrives on a group of islands rapidly becomes more diverse over time, splitting off into new species or subspecies. A species that reaches an island ecosystem may face little competition for resources, or may find that the resources that they found in their previous habitat are not available. These factors together result in individual evolutionary branches with different means of survival. +The classical example of this is Darwin's finches, a group of up to fifteen tanager species that are endemic to the Galápagos Islands. These birds evolved different beaks in order to eat different kinds of food available on the islands. The large ground finch has a large bill used to crack seeds and eat fruit. The Genovesa cactus finch prefers cacti as a food source, and has a beak adapted for removing pulp and flowers from cacti. The green warbler-finch (in the habit of true warbler species) consumes spiders and insects that live on plants. Other examples of this phenomenon exist worldwide, including in Hawaii and Madagascar, and are not limited to island ecosystems. + +==== The island rule ==== \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Island-2.md b/data/en.wikipedia.org/wiki/Island-2.md new file mode 100644 index 000000000..18915197c --- /dev/null +++ b/data/en.wikipedia.org/wiki/Island-2.md @@ -0,0 +1,27 @@ +--- +title: "Island" +chunk: 3/5 +source: "https://en.wikipedia.org/wiki/Island" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:12.739706+00:00" +instance: "kb-cron" +--- + +Species endemic to islands show a common evolutionary trajectory. Foster's rule (also known as the island rule), states that small mammals such as rodents evolve to become larger, known as island gigantism. One such example is the giant tortoise of the Seychelles, though it is unknown if it grew in size before or after reaching the island. Larger animals such as the hippopotamus tend to become smaller, such as in the case of the pygmy hippopotamus. This is known as insular dwarfism. In the case of smaller animals, it has been hypothesized that animals on islands may have fewer predators and competitors, resulting in selection pressure towards larger animals. Larger animals may exhaust food resources quickly due to their size, causing malnutrition in their young, resulting in a selection pressure for smaller animals that require less food. Having fewer predators would mean these animals did not need not be large to survive. + +=== Darwin, the Galápagos, and natural selection === +Charles Darwin formulated the theory of natural selection through the study of island ecology. The species he observed on the Galápagos Islands, including tanager birds, contributed to his understanding of how evolution works. He first traveled to the islands as a naturalist on HMS Beagle in 1835, as part of a five-year circumnavigation of Earth. He wrote that "the different islands to a considerable extent are inhabited by a different set of beings". Through the study of the finches and other animals he realized that organisms survive by changing to adapt to their habitat. It would be over twenty years before he published his theories in On the Origin of Species. + +== Humans and islands == + +=== History of exploration === + +The first evidence of humans colonizing islands probably occurred in the Paleolithic era, 100,000 to 200,000 years ago. Reaching the Indonesian islands of Flores and Timor would have required crossing distances of water of at least 29 km (18 mi). Some islands, such as Honshu, were probably connected to the mainland with a land bridge that allowed humans to colonize it before it became an island. +The first people to colonize distant oceanic islands were the Polynesians. Many of the previous island settlements required traveling distances of less than 100 km (62 mi), whereas Polynesians may have traveled 2,000–3,200 km (1,200–2,000 mi) to settle islands such as Tahiti. They would send navigators to sail the ocean without the aid of navigational instruments to discover new islands for settlement. Between 1100 and 800 BC, Polynesians sailed East from New Guinea and the Solomon Islands and reached the islands that make up the modern-day Fiji and Samoa. The furthest extent of this migration would be Easter Island in the East, and New Zealand in the South, with New Zealand's first settlements between 1250 and 1300. +Historians have sought to understand why some remote islands have always been uninhabited, while others, especially in the Pacific Ocean, have long been populated by humans. Generally, larger islands are more likely to be able to sustain humans and thus are more likely to have been settled. Small islands that cannot sustain populations on their own can still be habitable if they are within a "commuting" distance to an island that has enough resources to be sustainable. The presence of an island is marked by seabirds, differences in cloud and weather patterns, as well as changes in the direction of waves. It is also possible for human populations to have gone extinct on islands, evidenced by explorers finding islands that show evidence of habitation but no life. +Not all islands were or are inhabited by maritime cultures. In the past, some societies were found to have lost their seafaring ability over time, such as the case of the Canary Islands, which were occupied by an indigenous people since the island's first discovery in the first century until being conquered by the Spanish Empire in 1496. It has been hypothesized that since the inhabitants had little incentive for trade and had little to any contact with the mainland, they had no need for boats. +The motivation for island exploration has been the subject of research and debate. Some early historians previously argued that early island colonization was unintentional, perhaps by a raft being swept out to sea. Others compare the motivations of Polynesian and similar explorers with those of Christopher Columbus, the explorer who sailed westward over the Atlantic Ocean in search of an alternate route to the East Indies. These historians theorize that successful explorers were rewarded with recognition and wealth, leading others to attempt possibly dangerous expeditions to discover more islands, usually with poor results. + +=== Lifestyle === +About 10% of the world's population lives on islands. The study of the culture of islands is known as island studies. The interest in the study of islands is due to their unique cultures and natural environments that differ from mainland cultures. This is for a few reasons: First, the obvious political and geographic isolation from mainland cultures. Second, unique restraints on resources and ecology creating marine-focused cultures with a focus on fishing and sailing. Third, a lasting historical and political significance of islands. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Island-3.md b/data/en.wikipedia.org/wiki/Island-3.md new file mode 100644 index 000000000..c286d7f6d --- /dev/null +++ b/data/en.wikipedia.org/wiki/Island-3.md @@ -0,0 +1,32 @@ +--- +title: "Island" +chunk: 4/5 +source: "https://en.wikipedia.org/wiki/Island" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:12.739706+00:00" +instance: "kb-cron" +--- + +==== Diet ==== +The Polynesian diet got most of its protein from fishing. Polynesians were known to fish close to shore, as well as in deep water. It was reported that Rapa Nui people were known to fish as far as 500 km (310 mi) from shore at coral reefs. Spear, line, and net fishing were all used, to catch tuna as well as sharks and stingrays. Island cultures also cultivate native and non-native crops. Polynesians grew the native yam, taro, breadfruit, banana, coconut and other fruits and vegetables. Different island climates made different resources more important, such as the Hawaiian islands being home to irrigated fields of taro, whereas in some islands, like Tahiti, breadfruit was more widely cultivated and fermented in order to preserve it. There is archeological evidence that Canary Islanders would chew the roots of ferns for sustenance, a practice that wore heavily on their molars. These islanders would also grow barley and raised livestock such as goats. + +=== Island nations and territories === + +Many island nations have little land and a restricted set of natural resources. However, these nations control some of the largest fisheries in the world, deposits of copper, gold, and nickel, as well as oil deposits. The natural beauty of island nations also makes them a magnet for tourism. Islands also have geopolitical value for naval bases, weapons testing, and general territorial control. One such example is French Polynesia, a territory that receives substantial military expenditure and aid from France. Three others, Palau, Federated States of Micronesia, and the Marshall Islands, are island nations of the Pacific region that maintain a defense, aid, and immigration agreement with the United States called a Compact of Free Association. + +==== Colonization ==== + +Since the first discoveries of Polynesian, Micronesian, and other islands by Westerners, these nations have been the subject of colonization. Islands were the target of Christian missionaries. These missionaries faced resistance, but found success when some local chiefs used European support to centralize power. Beginning in the 16th century, European states placed most of Oceania in under colonial administration. Pohnpei was colonized by Spain as early as 1526. It changed hands from Germany to Japan to the United States before joining the Federated States of Micronesia in 1982, maintaining a "free association" status with the U.S. Guam was a Spanish territory until 1898, and now is an unincorporated territory of the U.S. +The decolonization era saw many island states achieve independence or some form of self-governance. Nuclear weapons testing on the Marshall Islands left many atolls destroyed or uninhabitable, causing the forced displacement of people from their home islands as well as increases in cancer rates due to radiation. Colonization has resulted in a decline of observance of traditional cultural practices in places such as Hawaii, where Native Hawaiians are now a minority. Cultural attitudes related to communal ownership of land as well as a lack of individualistic decision-making may make some island cultures less compatible with the global capitalist economy, causing these nations to experience less economic growth. + +=== Tourism === +Islands have long been a popular target for tourism, thanks to their unique climates, cultures, and natural beauty. However, islands may suffer from poor transportation connectivity from airplanes and boats and strains on infrastructure from tourist activity. Islands in colder climates often rely on seasonal tourists seeking to enjoy nature or local cultures, and may only be one aspect of an island's economy. In contrast, tourism on tropical islands can often make up the majority of the local economy and built environment. These islands sometimes also require consistent foreign aid on top of tourism in order to ensure economic growth. This reliance can result in social inequality and environmental degradation. During tourism downturns, these economies struggle to make up the lost inflow of cash with other industries. + +== Threats to islands == + +Climate change threatens human development on islands due to sea level rise, more dangerous tropical cyclones, coral bleaching, and an increase in invasive species. For example, in 2017 Hurricane Maria caused a loss of almost all the infrastructure in Dominica. Sea level rise and other climate changes can reduce freshwater reserves, resulting in droughts. These risks are expected to decrease the habitability of islands, especially small ones. Beyond risks to human life, plant and animal life are threatened. It has been estimated that almost 50 percent of land species threatened by extinction live on islands. In 2017, a detailed review of 1,288 islands found that they were home to 1,189 highly-threatened vertebrate species, which was 41 percent of the global figure. Coral bleaching is expected to occur with more frequency, threatening marine ecosystems, some of which island economies are dependent on. +Some islands that are low-lying may cease to exist given high enough amounts of sea level rise. Tuvalu received media attention for a press conference publicizing the ongoing submerging of the island country. Tuvalu signed a cooperation agreement with Australia agreeing to annually allow 280 of its citizens to become permanent residents of Australia. The Marshall Islands, a country of 1,156 islands, have also been identified as a country that may be existentially threatened by rising seas. +Increasing intensity of tropical storms also increases the distances and frequency with which invasive species may be transported to islands. Floodwaters from these storms may also wash plants further inland than they would travel on their own, introducing them to new habitats. Agriculture and trade also have introduced non-native life to islands. These processes result in an introduction of invasive species to ecosystems that are especially small and fragile. One example is the apple snail, initially introduced to the U.S. by aquarium owners. It has since been transported by hurricanes across the Gulf Coast and neighboring islands. These species compete for resources with native animals, and some may grow so densely that they displace other forms of existing life. + +== Artificial islands == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Island-4.md b/data/en.wikipedia.org/wiki/Island-4.md new file mode 100644 index 000000000..6797d17d9 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Island-4.md @@ -0,0 +1,20 @@ +--- +title: "Island" +chunk: 5/5 +source: "https://en.wikipedia.org/wiki/Island" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:12.739706+00:00" +instance: "kb-cron" +--- + +For hundreds of years, islands have been created through land reclamation. One of the first recorded instances of this when people of the Solomon Islands created eighty such islands by piling coral and rock in the Lau Lagoon. However, the first permanent artificial island is Al-Sayah island, in Bahrain – created at least 1,200 years ago. One traditional way of constructing islands is with the use of a revetment. Sandbags or stones are dropped with a barge into the sea to bring the land level slightly out of the water. The island area is then filled with sand or gravel, followed by a construction of this revetment to hold it together. Islands have also been constructed with a permanent caisson, a steel or concrete structure built in a closed loop and then filled with sand. +Some modern islands have been constructed by pouring millions of tons of sand into the sea, such as with Pearl Island in Qatar or the Palm Islands in Dubai. These islands are usually created for real estate development, and are sold for private ownership or construction of housing. Offshore oil platforms have also been described as a type of island. Some atolls have been covered in concrete to create artificial islands for military purposes, such as those created by China in the South China Sea. These atolls were previously low-tide elevations, landmasses that are only above water during low tide. The United Nations Convention on the Law of the Sea indicates that these islands may not have the same legal status as a naturally occurring island, and as such may not confer the same legal rights. + +== See also == + +== References == + +== External links == + Media related to Island (category) at Wikimedia Commons + Quotations related to Islands at Wikiquote \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Kinematic_wave-0.md b/data/en.wikipedia.org/wiki/Kinematic_wave-0.md new file mode 100644 index 000000000..f689697a9 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Kinematic_wave-0.md @@ -0,0 +1,225 @@ +--- +title: "Kinematic wave" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Kinematic_wave" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:13.990990+00:00" +instance: "kb-cron" +--- + +In gravity and pressure driven fluid dynamical and geophysical mass flows such as ocean waves, avalanches, debris flows, mud flows, flash floods, etc., kinematic waves are important mathematical tools to understand the basic features of the associated wave phenomena. +These waves are also applied to model the motion of highway traffic flows. +In these flows, mass and momentum equations can be combined to yield a kinematic wave equation. Depending on the flow configurations, the kinematic wave can be linear or non-linear, which depends on whether the wave phase speed is a constant or a variable. A kinematic wave can be described by a simple partial differential equation with a single unknown field variable (e.g., the flow or wave height, + + + + h + + + {\displaystyle h} + +) in terms of the two independent variables, namely the time ( + + + + t + + + {\displaystyle t} + +) and the space ( + + + + x + + + {\displaystyle x} + +) with some parameters (coefficients) containing information about the physics and geometry of the flow. In general, the wave can be advecting and diffusing. However, in simple situations, the kinematic wave is mainly advecting. + + +== Kinematic wave for debris flow == +Non-linear kinematic wave for debris flow can be written as follows with complex non-linear coefficients: + + + + + + + + ∂ + h + + + ∂ + t + + + + + + C + + + + ∂ + h + + + ∂ + x + + + + = + D + + + + + ∂ + + 2 + + + h + + + ∂ + + x + + 2 + + + + + + , + + + {\displaystyle {\frac {\partial h}{\partial t}}+C{\frac {\partial h}{\partial x}}=D{\frac {\partial ^{2}h}{\partial x^{2}}},} + + +where + + + + h + + + {\displaystyle h} + + is the debris flow height, + + + + t + + + {\displaystyle t} + + is the time, + + + + x + + + {\displaystyle x} + + is the downstream channel position, + + + + C + + + {\displaystyle C} + + is the pressure gradient and the depth dependent nonlinear variable wave speed, and + + + + D + + + {\displaystyle D} + + is a flow height and pressure gradient dependent variable diffusion term. +This equation can also be written in the conservative form: + + + + + + + + ∂ + h + + + ∂ + t + + + + + + + + + ∂ + F + + + ∂ + x + + + + = + 0 + , + + + {\displaystyle {\frac {\partial h}{\partial t}}+{\frac {\partial F}{\partial x}}=0,} + + +where + + + + F + + + {\displaystyle F} + + is the generalized flux that depends on several physical and geometrical parameters of the flow, flow height and the hydraulic pressure gradient. For + + + + F + = + + h + + 2 + + + + / + + 2 + + + {\displaystyle F=h^{2}/2} + +, this equation reduces to the Burgers' equation. + + +== References == + + +== Further reading == +Singh, Vijay P. (1996). "Linearization of Hydraulic Equations". Kinematic Wave Modeling in Water Resources : Surface-Water Hydrology. New York: John Wiley & Sons. pp. 211–253. ISBN 0-471-10945-2. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Knoll_(oceanography)-0.md b/data/en.wikipedia.org/wiki/Knoll_(oceanography)-0.md new file mode 100644 index 000000000..f04ab806c --- /dev/null +++ b/data/en.wikipedia.org/wiki/Knoll_(oceanography)-0.md @@ -0,0 +1,19 @@ +--- +title: "Knoll (oceanography)" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Knoll_(oceanography)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:15.200691+00:00" +instance: "kb-cron" +--- + +In marine geology, a knoll is defined as a rounded underwater hill, not exceeding 1000 meters in height. Any rounded underwater features exceeding that height are referred to as seamounts. They are believed to cover around 16.3% of the world's seafloor. + + +== Examples == +Orphan Knoll +Graveyard Seamounts + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Lagoon-0.md b/data/en.wikipedia.org/wiki/Lagoon-0.md new file mode 100644 index 000000000..0e8682ca1 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Lagoon-0.md @@ -0,0 +1,52 @@ +--- +title: "Lagoon" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Lagoon" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:16.460249+00:00" +instance: "kb-cron" +--- + +A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as a reef, a barrier island or islands, a barrier peninsula, or an isthmus. Lagoons are commonly divided into coastal lagoons (or barrier lagoons) and atoll lagoons. They have also been identified as occurring on mixed-sand and gravel coastlines. There is an overlap between bodies of water classified as coastal lagoons and bodies of water classified as estuaries. Lagoons are common coastal features around many parts of the world. + + +== Definition and terminology == +Lagoons are shallow, often elongated bodies of water separated from a larger body of water by a shallow or exposed shoal, coral reef, or similar feature. Some authorities include fresh water bodies in the definition of "lagoon", while others explicitly restrict "lagoon" to bodies of water with some degree of salinity. The distinction between "lagoon" and "estuary" also varies between authorities. Richard A. Davis Jr. restricts "lagoon" to bodies of water with little or no fresh water inflow, and little or no tidal flow, and calls any bay that receives a regular flow of fresh water an "estuary". Davis does state that the terms "lagoon" and "estuary" are "often loosely applied, even in scientific literature". Timothy M. Kusky characterizes lagoons as normally being elongated parallel to the coast, while estuaries are usually drowned river valleys, elongated perpendicular to the coast. Coastal lagoons are classified as inland bodies of water. +When used within the context of a distinctive portion of coral reef ecosystems, the term "lagoon" is synonymous with the term "back reef" or "backreef", which is more commonly used by coral reef scientists to refer to the same area. +Many lagoons do not include "lagoon" in their common names. Currituck, Albemarle and Pamlico Sounds in North Carolina, Great South Bay between Long Island and the barrier beaches of Fire Island in New York, Isle of Wight Bay, which separates Ocean City, Maryland from the rest of Worcester County, Maryland, Banana River in Florida, US, Lake Illawarra in New South Wales, Australia, Montrose Basin in Scotland, and Broad Water in Wales have all been classified as lagoons, despite their names. In England, The Fleet at Chesil Beach has also been described as a lagoon. +In some languages the word for a lagoon is simply a type of lake: In Chinese a lake is hu (湖), and a lagoon is xihu (潟湖). In the French Mediterranean several lagoons are called étang ("lake"). Contrariwise, several other languages have specific words for such bodies of water. In Spanish, coastal lagoons generically are laguna costera, but those on the Mediterranean coast are specifically called albufera. In Russian and Ukrainian, those on the Black Sea are liman (лиман), while the generic word is laguna (Лагуна). Similarly, in the Baltic, Danish has the specific Nor, and German the specifics Bodden and Haff, as well as generic terms derived from laguna. In Poland these lagoons are called zalew ("bay"), and in Lithuania marios ("lagoon, reservoir"). In Jutland several lagoons are known as fjord. In New Zealand the Māori word hapua refers to a coastal lagoon formed at the mouth of a braided river where there are mixed sand and gravel beaches, while waituna, an ephemeral coastal waterbody, is neither a true lagoon, lake, nor estuary. +Some languages differentiate between coastal and atoll lagoons. In French, lagon refers specifically to an atoll lagoon, while coastal lagoons are described as étang, the generic word for a still lake or pond. +In Vietnamese, Đầm san hô refers to an atoll lagoon, whilst Đầm phá is coastal. +In Latin America, the term laguna in Spanish, which lagoon translates to, may be used for a small fresh water lake in a similar way a creek is considered a small river. However, sometimes it is popularly used to describe a full-sized lake, such as Laguna Catemaco in Mexico, which is actually the third-largest lake by area in the country. The brackish water lagoon may be thus explicitly identified as a "coastal lagoon" (laguna costera). In Portuguese, a similar usage is found: lagoa may be a body of shallow seawater, or a small freshwater lake not linked to the sea. + + +=== Etymology === +Lagoon is derived from the Venetian łaguna, which refers to the waters around Venice, i.e. the Venetian Lagoon. Laguna is attested in English by at least 1612, and had been Anglicized to lagune by 1673. In 1697 William Dampier referred to a "Lagune or Lake of Salt water" on the coast of Mexico. Captain James Cook described an island "of Oval form with a Lagoon in the middle" in 1769. + + +== Atoll lagoons == + +Atoll lagoons form as coral reefs grow upwards while the islands that the reefs surround subside, until eventually only the reefs remain above sea level. Unlike the lagoons that form shoreward of fringing reefs, atoll lagoons often contain some deep (>20 m (66 ft)) portions. + + +== Coastal lagoons == + +Coastal lagoons form along gently sloping coasts where barrier islands or reefs can develop offshore, and the sea-level is rising relative to the land along the shore (either because of an intrinsic rise in sea-level, or subsidence of the land along the coast). Coastal lagoons do not form along steep or rocky coasts, or if the range of tides is more than 4 metres (13 ft). Due to the gentle slope of the coast, coastal lagoons are shallow. A relative drop in sea level may leave a lagoon largely dry, while a rise in sea level may let the sea breach or destroy barrier islands, and leave reefs too deep underwater to protect the lagoon. Coastal lagoons are young and dynamic, and may be short-lived in geological terms. Coastal lagoons are common, occurring along nearly 15 percent of the world's shorelines. In the United States, lagoons are found along more than 75 percent of the Eastern and Gulf Coasts. +Coastal lagoons can be classified as leaky, restricted, or choked. +Coastal lagoons are usually connected to the open ocean by inlets between barrier islands. The number and size of the inlets, precipitation, evaporation, and inflow of fresh water all affect the nature of the lagoon. Lagoons with little or no interchange with the open ocean, little or no inflow of fresh water, and high evaporation rates, such as Lake St. Lucia, in South Africa, may become highly saline. Lagoons with no connection to the open ocean and significant inflow of fresh water, such as the Lake Worth Lagoon in Florida in the middle of the 19th century, may be entirely fresh. On the other hand, lagoons with many wide inlets, such as the Wadden Sea, have strong tidal currents and mixing. Coastal lagoons tend to accumulate sediments from inflowing rivers, from runoff from the shores of the lagoon, and from sediment carried into the lagoon through inlets by the tide. Large quantities of sediment may be occasionally be deposited in a lagoon when storm waves overwash barrier islands. Mangroves and marsh plants can facilitate the accumulation of sediment in a lagoon. Benthic organisms may stabilize or destabilize sediments. + + +=== Largest coastal lagoons === + + +== Images == + + +== See also == + + +== Notes == + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/List_of_academic_databases_and_search_engines-0.md b/data/en.wikipedia.org/wiki/List_of_academic_databases_and_search_engines-0.md new file mode 100644 index 000000000..3b98ea28f --- /dev/null +++ b/data/en.wikipedia.org/wiki/List_of_academic_databases_and_search_engines-0.md @@ -0,0 +1,35 @@ +--- +title: "List of academic databases and search engines" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/List_of_academic_databases_and_search_engines" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:01.149047+00:00" +instance: "kb-cron" +--- + +This page contains a representative list of major databases and search engines useful in an academic setting for finding and accessing articles in academic journals, institutional repositories, archives, or other collections of scientific and other articles. As the distinction between a database and a search engine is unclear for these complex document retrieval systems, see: + +the general list of search engines for all-purpose search engines that can be used for academic purposes +the article about bibliographic databases for information about databases giving bibliographic information about finding books and journal articles. +Note that "free" or "subscription" can refer both to the availability of the database or of the journal articles included. This has been indicated as precisely as possible in the list: + + +== List == + + +== See also == + +Academic publishing +Google Scholar +Lists of databases +List of digital library projects +List of educational video websites +List of neuroscience databases +List of online databases +List of online encyclopedias +List of open access journals +Lists of academic journals + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/List_of_international_databases_on_individual_student_achievement_tests-0.md b/data/en.wikipedia.org/wiki/List_of_international_databases_on_individual_student_achievement_tests-0.md new file mode 100644 index 000000000..f18f4b39b --- /dev/null +++ b/data/en.wikipedia.org/wiki/List_of_international_databases_on_individual_student_achievement_tests-0.md @@ -0,0 +1,18 @@ +--- +title: "List of international databases on individual student achievement tests" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/List_of_international_databases_on_individual_student_achievement_tests" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:59.819238+00:00" +instance: "kb-cron" +--- + +This article contains a list of international databases on individual student achievement tests that can be used for psychometric research. In other words, this table only includes datasets containing items measuring ability and directly answered by students. + + +== See also == +List of online databases + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/List_of_peninsulas-0.md b/data/en.wikipedia.org/wiki/List_of_peninsulas-0.md new file mode 100644 index 000000000..7b7cc17d0 --- /dev/null +++ b/data/en.wikipedia.org/wiki/List_of_peninsulas-0.md @@ -0,0 +1,308 @@ +--- +title: "List of peninsulas" +chunk: 1/2 +source: "https://en.wikipedia.org/wiki/List_of_peninsulas" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:07.459713+00:00" +instance: "kb-cron" +--- + +A peninsula (Latin: paeninsula from paene "almost" and insula "island") is a piece of land that is bordered mostly by water but connected to mainland. The surrounding water is usually understood to be continuous, though not necessarily named as such. A peninsula can also be a headland, cape, island promontory, bill, point, +or spit. A point is generally considered a tapering piece of land projecting into a body of water that is less prominent than a cape. In English, the plural of peninsula is peninsulas or, less commonly, peninsulae. A river which courses through a very tight meander is also sometimes said to form a "peninsula" within the (almost closed) loop of water. +Presented below is a list of peninsulas. + +== Africa == + +=== Macaronesia === +Jandía, Fuerteventura, Canary Islands, Spain +Macizo de Anaga, Tenerife, Canary Islands, Spain +Ponta de São Lourenço, Madeira Island, Portugal + +=== North Africa === + +=== Somali Peninsula === + +The Horn of Africa is a peninsula in Northeast Africa that juts into the Guardafui Channel, and is the easternmost projection of the African continent. It denotes the region containing the countries of Djibouti, Eritrea, Ethiopia, and Somalia. + +Buri Peninsula, Eritrea +Ras Hafun, Somalia +Ras Kasar, Eritrea +Ras Siyyan, Djibouti + +=== West Africa === +Lekki Peninsula, Lagos, Nigeria +Cap-Vert, Senegal +Turner's Peninsula, Sierra Leone + +=== Other peninsulas in Africa === +Bakassi, Cameroon, but disputed with Nigeria +Cape Peninsula, South Africa +Le Morne Brabant, Mauritius +Uyoma, Kenya + +== Antarctica == +Antarctic Peninsula +Edward VII Peninsula +Fletcher Peninsula +Fowler Peninsula +Martin Peninsula + +== Asia == + +=== Central Asia === +Kazakhstan + +Mangyshlak Peninsula + +=== Eastern Asia === + +==== China ==== +Source: + +Liaodong Peninsula +Shandong Peninsula +Dapeng Peninsula +Leizhou Peninsula + +==== Hong Kong ==== +Hong Kong itself is a peninsula. + +Kowloon Peninsula +Sai Kung Peninsula +Stanley Peninsula +Shek O + +==== Japan ==== + +===== Hokkaido ===== +Shiretoko Peninsula +Shakotan Peninsula + +===== Honshū ===== +Oshika-hanto +Noto-hanto +Oga-hanto +Miura-hanto +Bōsō-hanto + +===== Kyūshū ===== +Nishi-sonogi-hanto +Satsuma-hanto +Ōsumi-hanto +Shimabara-hanto + +==== Korea ==== + +The whole landmass encompassing North and South Korea is a peninsula, surrounded by the East Sea to the east and south, and the Yellow Sea to the west and south, with the Korea Strait connecting them. + +==== Macau ==== +Macau Peninsula + +==== Taiwan ==== +Hengchun Peninsula + +=== Northern Asia === + +=== South-eastern Asia === + +==== Indochina ==== +Indochina Peninsula +Malay Peninsula + +==== Indonesia ==== + +==== Malaysia ==== +Northwestern Peninsula, Kudat +Pitas Peninsula, Pitas +Semporna Peninsula, Semporna and Tawau +Sandakan Peninsula, Sandakan +Peninsula Malaysia + +==== Philippines ==== + +==== Thailand ==== +Sathing Phra Peninsula + +==== Singapore ==== +Tuas + +==== Vietnam ==== + +=== India === + +The Deccan Peninsula is a dominant geographical feature of the Indian subcontinent +Other peninsulas on the Indian Subcontinent include: + +=== Western Asia === + +==== Arabia ==== +Arabian Peninsula; Saudi Arabia, Iraq, Kuwait, Qatar, Jordan, United Arab Emirates, Yemen, Oman +Al-Faw Peninsula, Iraq +Musandam Peninsula; Oman, United Arab Emirates + Qatar Peninsula + +==== Eastern Mediterranean ==== +Beirut, Lebanon +El Mina, Lebanon +Haifa, Israel +Acre, Israel +Sinai Peninsula, Egypt + +==== Turkey ==== + +== Europe == +Europe is sometimes considered to be a large peninsula extending off Eurasia. As such, it is one of the largest peninsulas in the world and the only one to have the status as a full continent, largely as a matter of convention rather than science. It is composed of many smaller peninsulas, the four main and largest component peninsulas being the Scandinavian, Iberian, Balkan, and Apennine peninsulas. + +=== Balkan Peninsula === + +The Balkans is a region which natural borders do not coincide with the technical definition of a peninsula hence modern geographers reject the idea of a Balkan Peninsula. It would include Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Greece, Kosovo, North Macedonia, Montenegro, Romania, Serbia, Slovenia and the European part of Turkey. + +Chalkidiki, Greece +Kassandra, Greece +Mani Peninsula, Greece +Mount Athos, Greece +Peloponnese, Greece (now an island because of the Corinth Canal) +Sithonia, Greece +Pilio, Greece +Istria, Croatia +Piran Peninsula, Slovenia +Pelješac, Croatia +Prevlaka, Croatia +Split, Croatia +Zadar, Croatia +Karaburun Peninsula, Albania +Luštica, Montenegro +Gallipoli, Turkey +Klek (peninsula), Bosnia and Herzegovina +Istanbul, Turkey + +=== France === +Brittany +Cap Corse, Corsica +Cotentin Peninsula, Normandy +Crozon, Finistère +Landes du Médoc, Aquitaine + +=== Iberian Peninsula === + +Encompassing continental Portugal and Spain, Andorra, Gibraltar (British Overseas Territory), and a small amount of Southern France, the Iberian Peninsula is a dominant geographical feature of Iberia. +Other peninsulas in Iberia include: + +=== Ireland === + +=== Italy === + +The Apennine Peninsula is the dominant geographical feature of Italy. +Other peninsulas in Italy include: + +Adriatic Sea +Promontorio del Gargano +Ionian Sea +Calabria +Salento +Ligurian Sea +Portofino +Portovenere +Promontorio di Piombino +Tyrrhenian Sea +Gaeta +Promontorio del Circeo +Promontorio dell'Argentario +Promontorio di Punta Ala +Sorrentine Peninsula + +=== Malta === +Valletta +Senglea +Birgu +Sliema +Ta' Xbiex +Marsaskala +Fort Ricasoli + +=== Russia === + +=== Scandinavia === + +==== Norway ==== + +==== Sweden ==== + +==== Denmark ==== + +=== Finland === +Hanko Peninsula, Hanko +Porkkala Peninsula, Kirkkonummi +Suensaari, Tornio + +=== Estonia === + +=== Turkey === + +Gallipoli Peninsula +Thracian Peninsula + +=== Ukraine === +Crimean Peninsula, occupied by Russia +Chonhar Peninsula +Kinburn Peninsula +Rybalskyi Peninsula + +=== United Kingdom and the Crown Dependencies === + +==== England ==== + +==== Northern Ireland ==== +Ards Peninsula +Islandmagee +Lecale peninsula +Ramore Head, Portrush +Oxford Island +Magilligan + +==== Scotland ==== + +==== Wales ==== +Creuddyn Peninsula juts out of the North Wales coast +Gower Peninsula, Swansea +Llŷn Peninsula +Marloes Peninsula, Pembrokeshire +South Pembrokeshire Peninsula +St Davids Head, Pembrokeshire +Wales, itself a peninsula + +==== Channel Islands ==== +Le Clos du Valle, Guernsey +Little Sark, Sark + +==== Isle of Man ==== +Langness Peninsula, Malew + +=== Other peninsulas in Europe === + +== North America == + +=== Belize === +Placencia Peninsula, Belize + +=== Canada === +Dunlas Peninsula, Melville Island, Northwest Territories/Nunavut +Labrador Peninsula, encompassing all of Labrador and most of Quebec +Natkusiak Peninsula, Victoria Island, Northwest Territories/Nunavut +Storkerson Peninsula, Victoria Island, Northwest Territories/Nunavut +Wollaston Peninsula, Victoria Island, Northwest Territories/Nunavut + +==== British Columbia ==== + +==== New Brunswick ==== + +==== Newfoundland and Labrador ==== + +==== Northwest Territories ==== + +==== Nova Scotia ==== + +==== Nunavut ==== + +===== Baffin Island ===== \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/List_of_peninsulas-1.md b/data/en.wikipedia.org/wiki/List_of_peninsulas-1.md new file mode 100644 index 000000000..d9d981e56 --- /dev/null +++ b/data/en.wikipedia.org/wiki/List_of_peninsulas-1.md @@ -0,0 +1,206 @@ +--- +title: "List of peninsulas" +chunk: 2/2 +source: "https://en.wikipedia.org/wiki/List_of_peninsulas" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:07.459713+00:00" +instance: "kb-cron" +--- + +==== Ontario ==== + +==== Quebec ==== +Gaspé Peninsula +Ungava Peninsula + +=== Caribbean === + +==== Haiti ==== +Peninsule de Tiburon, Haiti +Peninsule de Mole-St-Nicolas, Haiti + +==== Dominican Republic ==== +Peninsula de Samaná, Dominican Republic + +==== Puerto Rico ==== +Barrio Obrero, Puerto Rico + +==== Cuba ==== +Zapata Peninsula, Cuba +Guanahacabibes Peninsula, Cuba +Hicacos Peninsula, Cuba + +==== Saint Lucia ==== +Vigie Peninsula, St Lucia + +=== Costa Rica === +Nicoya Peninsula, Costa Rica +Osa Peninsula, Costa Rica + +=== Greenland === +Wegener Peninsula +Hayes Halvo +Ingnerit +Nuussuaq Peninsula +Sigguup Nunaa (Svartenhuk Halvø) + +=== Mexico === + +Baja California Peninsula, Mexico, containing the states of Baja California and Baja California Sur +Yucatán Peninsula, partly separating the Gulf of Mexico from the Caribbean + +=== Panama === + +=== United States === + +==== Alaska ==== +Alaska Peninsula +Cleveland Peninsula +Kenai Peninsula +Seward Peninsula +Lisburne Peninsula + +==== California ==== + +==== Florida ==== + +Florida is a well-known example of a large peninsula, with its land area divided between the larger Florida peninsula and the smaller Florida Panhandle on the north and west. It has several smaller peninsulas within it: + +The St. Johns River creates a large peninsula over 75 miles (121 km) in length that stretches from eastern Jacksonville down to the border of Flagler and Volusia counties, where the river emanates from Lake George. +Fairpoint Peninsula +Pinellas peninsula, including St. Petersburg and Clearwater +Much of Tampa lies on a peninsula called Interbay Peninsula jutting out into Tampa Bay +Cape Sable + +==== Maryland ==== + +Maryland shares the Delmarva Peninsula east of Chesapeake Bay with Delaware and Virginia. +St. Mary's Peninsula is defined by the Patuxent River, the Potomac River, and Chesapeake Bay. +Calvert Peninsula lies between Chesapeake Bay and the Patuxent River. +Numerous smaller tidal tributaries form smaller peninsulas on both the Eastern and Western shores of Chesapeake Bay. Named examples include the Broadneck Peninsula in Anne Arundel County and the Elk Neck Peninsula in Cecil County. + +==== Massachusetts ==== + +Cape Cod, Massachusetts, a cape that can be viewed as a peninsula +Cape Ann, includes the towns of Gloucester and Rockport +Nahant, a town in Essex County, is on a small peninsula. +Nantasket Peninsula, Hull +Shawmut Peninsula, Boston + +==== Michigan ==== + +==== New Jersey ==== + +==== New York ==== + +Irondequoit, NY (geographical headland) + +==== Oregon ==== + +==== Utah ==== +Antelope Island, Utah, becomes a peninsula when waters are low, on the south shore of the Great Salt Lake +Promontory Peninsula, on the north eastern shore of the Great Salt Lake +Stansbury Peninsula becomes an island when waters are high, on the south shore of the Great Salt Lake + +==== Vermont ==== +Alburgh, Vermont, is on the Alburgh Tongue, a peninsula extending from Quebec, Canada into Lake Champlain + +==== Virginia ==== +Middle Peninsula, on the western shore of the Chesapeake Bay +Northern Neck, on the western shore of the Chesapeake Bay +Virginia Peninsula, on the western shore of the Chesapeake Bay + +==== Washington ==== + +==== Wisconsin ==== +Bark Point, Wisconsin in Lake Superior +Bayfield Peninsula, Wisconsin in Lake Superior +Chequamegon Point, Wisconsin in Lake Superior +Door Peninsula, Wisconsin, in Lake Michigan +Jones Island, Milwaukee, Wisconsin in Lake Michigan +Little Tail Point, Wisconsin in Green Bay (Lake Michigan) +Marshall's Point, Wisconsin on North Bay in Lake Michigan +MawBilly Joelwe Point, Wisconsin on MawBilly Joelwe Bay in Lake Superior +Roman Point on Siskiwit Bay, Wisconsin, in Lake Superior +Toft Point between Bailey's Harbor, Wisconsin and Moonlight Bay, Wisconsin in Lake Michigan + +==== Other states ==== + +== Oceania == + +=== Australia === + +=== New Zealand === + +==== North Island ==== + +==== South Island ==== + +==== Outlying Islands ==== + +=== Papua New Guinea === +Gazelle Peninsula, New Britain +Huon Peninsula +Papuan Peninsula + +=== Hawaii === +Mokapu, Hawaii + +== South America == + +=== Southern Cone === +The Southern Cone, like Europe, is sometimes considered to be a large peninsula. Geographically, the peninsula encompasses most of Chile, Argentina, Uruguay and Southern Brazil and the southernmost portion of Paraguay, which makes it one of the largest peninsulas in the world. Like the Indian Peninsula, the Southern Cone is sometimes considered to be a subcontinent. + +=== Other peninsulas in South America === + +==== Argentina ==== +Valdés Peninsula +Verde Peninsula + +==== Brazil ==== +Cabo de São Tomé +Itapagipe Peninsula + +==== Chile ==== +Brunswick Peninsula +Hardy Peninsula +Taitao Peninsula + +==== Colombia ==== +Guajira Peninsula + +==== Peru ==== +Illescas Peninsula +Paracas Peninsula + +==== Uruguay ==== +Punta del Este + +==== Venezuela ==== +Araya Peninsula +Guajira Peninsula +Paraguaná Peninsula +Paria Peninsula + +== Fictional peninsulas == + +Brobdingnag in Gulliver's Travels by Jonathan Swift +Xanth in Xanth series by Piers Anthony +The Valyrian Peninsula in the A Song of Ice and Fire novels by George R. R. Martin + +== See also == +Cape (geography) +Headland +Isthmus +List of islands +Promontory +Salient (geography) +Spit (landform) +Tombolo + +== References == + +== External links == + The dictionary definition of peninsula at Wiktionary + Media related to Peninsulas at Wikimedia Commons \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Littoral_zone-0.md b/data/en.wikipedia.org/wiki/Littoral_zone-0.md new file mode 100644 index 000000000..1219d58c5 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Littoral_zone-0.md @@ -0,0 +1,34 @@ +--- +title: "Littoral zone" +chunk: 1/3 +source: "https://en.wikipedia.org/wiki/Littoral_zone" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:17.722778+00:00" +instance: "kb-cron" +--- + +The littoral zone, also called litoral or nearshore, is the part of an ocean, sea, lake, or river, that is close to the shore. It provides extensive and productive habitats around the world, adjacent to land-water interfaces. +In coastal ecology, the littoral zone includes the foreshore (intertidal zone) extending from the high water mark (which is rarely inundated) to the low water mark (where coastal areas become permanently submerged). However, the geographical meaning of littoral zone extends well beyond the intertidal zone to include all neritic waters within the bounds of continental shelves. Continental shelves cover an area of about 7% of the surface area of the oceans. +In lake ecosystems, the littoral zone covers about 78% of Earth's total lake area. These zones support abundant plant growth, making them not only structurally distinct from the pelagic (open water) zone but also highly productive. Productivity in both marine and lake littoral zones can reach levels comparable to tropical rainforests. + +== Definitions and characteristics == +The littoral zone has no single definition. What is regarded as the full extent of the littoral zone, and the way the littoral zone is divided into subregions, varies in different contexts. For lakes, the littoral zone is the nearshore habitat where photosynthetically active radiation penetrates to the lake bottom in sufficient quantities to support photosynthesis. Along marine coastlines, the littoral zone can extend to the edge of the continental shelf, where water can be sufficiently shallow to allow photosynthesis. + +The use of the term varies from one part of the world to another, and between different disciplines. For example, military commanders speak of the littoral in ways that are quite different from the definition used by marine biologists. For the purposes of naval operations, the US Navy divides the littoral zone in the ways shown on the diagram at the top of this article. The US Army Corps of Engineers and the US Environmental Protection Agency have their own definitions, which have legal implications. The UK Ministry of Defence defines the littoral as those land areas (and their adjacent areas and associated air space) that are susceptible to engagement and influence from the sea. +The adjacency of water gives a number of distinctive characteristics to littoral regions. The erosive power of water results in particular types of landforms, such as sand dunes, and estuaries. The natural movement of the littoral along the coast is called the littoral drift. Biologically, the ready availability of water enables a greater variety of plant and animal life, and particularly the formation of extensive wetlands. In addition, the additional local humidity due to evaporation usually creates a microclimate supporting unique types of organisms. +The word littoral may be used both as a noun and as an adjective. It derives from the Latin noun litus, litoris, meaning "shore". (The doubled t is a late-medieval innovation, and the word is sometimes seen in the more classical-looking spelling litoral.) + +== In oceanography and marine biology == + +In oceanography and marine biology, the idea of the littoral zone is extended roughly to the edge of the continental shelf. Starting from the shoreline, the littoral zone begins at the spray region just above the high tide mark. From here, it moves to the intertidal region between the high and low water marks, and then out as far as the edge of the continental shelf. These three subregions are called, in order, the supralittoral zone, the eulittoral zone, and the sublittoral zone. + +=== Supralittoral zone === + +The supralittoral zone (also called the splash, spray or supratidal zone) is the area above the spring high tide line that is regularly splashed, but not submerged by ocean water. Seawater penetrates these elevated areas only during storms with high tides. Organisms that live here must cope with exposure to fresh water from rain, cold, heat, dryness and predation by land animals and seabirds. At the top of this area, patches of dark lichens can appear as crusts on rocks. Some types of periwinkles, Neritidae and detritus feeding Isopods commonly inhabit the lower supralittoral. + +=== Eulittoral zone === + +The eulittoral zone (also called the midlittoral or mediolittoral zone) is the intertidal zone, known also as the foreshore. It extends from the spring high tide line, which is rarely inundated, to the spring low tide line, which is rarely not inundated. It is alternately exposed and submerged once or twice daily. Organisms living here must be able to withstand the varying conditions of temperature, light, and salinity. Despite this, productivity is high in this zone. The wave action and turbulence of recurring tides shape and reform cliffs, gaps and caves, offering a huge range of habitats for sedentary organisms. Protected rocky shorelines usually show a narrow, almost homogenous, eulittoral strip, often marked by the presence of barnacles. Exposed sites show a wider extension and are often divided into further zones. For more on this, see intertidal ecology. + +=== Sublittoral zone === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Littoral_zone-1.md b/data/en.wikipedia.org/wiki/Littoral_zone-1.md new file mode 100644 index 000000000..04a1a424f --- /dev/null +++ b/data/en.wikipedia.org/wiki/Littoral_zone-1.md @@ -0,0 +1,27 @@ +--- +title: "Littoral zone" +chunk: 2/3 +source: "https://en.wikipedia.org/wiki/Littoral_zone" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:17.722778+00:00" +instance: "kb-cron" +--- + +The sublittoral zone starts immediately below the eulittoral zone. This zone is permanently covered with seawater and is approximately equivalent to the neritic zone. +In physical oceanography, the sublittoral zone refers to coastal regions with significant tidal flows and energy dissipation, including non-linear flows, internal waves, river outflows and oceanic fronts. In practice, this typically extends to the edge of the continental shelf, with depths around 200 meters. +In marine biology, the sublittoral zone refers to the areas where sunlight reaches the ocean floor, that is, where the water is never so deep as to take it out of the photic zone. This results in high primary production and makes the sublittoral zone the location of the majority of sea life. As in physical oceanography, this zone typically extends to the edge of the continental shelf. The benthic zone in the sublittoral is much more stable than in the intertidal zone; temperature, water pressure, and the amount of sunlight remain fairly constant. Sublittoral corals do not have to deal with as much change as intertidal corals. Corals can live in both zones, but they are more common in the sublittoral zone. +Within the sublittoral, marine biologists also identify the following: + +The infralittoral zone is the algal dominated zone, which may extend to five metres below the low water mark. +The circalittoral zone is the region beyond the infralittoral, that is, below the algal zone and dominated by sessile animals such as mussels and oysters. +Shallower regions of the sublittoral zone, extending not far from the shore, are sometimes referred to as the subtidal zone. + +== In freshwater ecosystems == + +In freshwater situations, the littoral zone is the nearshore habitat where photosynthetically active radiation penetrates to the lake bottom in sufficient quantities to support photosynthesis. Sometimes other definitions are used. For example, the Minnesota Department of Natural Resources defines littoral as that portion of the lake that is less than 15 feet in depth. Such fixed-depth definitions often do not accurately represent the true ecological zonation, but are sometimes used because they are simple measurements to make bathymetric maps or when there are no measurements of light penetration. The littoral zone comprises an estimated 78% of Earth's total lake area. +The littoral zone may form a narrow or broad fringing wetland, with extensive areas of aquatic plants sorted by their tolerance to different water depths. Typically, four zones are recognized, from higher to lower on the shore: wooded wetland, wet meadow, marsh and aquatic vegetation. The relative areas of these four types depends not only on the profile of the shoreline, but upon past water levels. The area of wet meadow is particularly dependent upon past water levels; in general, the area of wet meadows along lakes and rivers increases with natural water level fluctuations. Many of the animals in lakes and rivers are dependent upon the wetlands of littoral zones, since the rooted plants provide habitat and food. Hence, a large and productive littoral zone is considered an important characteristic of a healthy lake or river. +The littoral zone of lakes is typically inhabited by macrophytes (freshwater aquatic plants). These macrophytes include: emergent macrophytes with stalks and leaves extending above the water surface, floating-leaved macrophytes rooted in the lakebed, free-floating macrophytes drifting on the surface, and submerged macrophytes growing entirely below the water surface. The distribution of macrophytes, especially submerged macrophytes, indicate of the extent of the littoral zone. However, some areas of the littoral zone may remain unvegetated when environmental conditions are unfavorable for plant growth, such as when the substrate is unsuitable, light penetration is insufficient, or wave action is too strong. The macrophytes that typically grow in the littoral zone contribute to making littoral zones among the world’s most productive habitats and can therefore play an important role in the global climate, for example by functioning as a carbon sink. +Littoral zones are at particular risk for two reasons. First, human settlement is often attracted to shorelines, and settlement often disrupts breeding habitats for littoral zone species. For example, many turtles are killed on roads when they leave the water to lay their eggs in upland sites. Fish can be negatively affected by docks and retaining walls which remove breeding habitat in shallow water. Some shoreline communities even deliberately try to remove wetlands since they may interfere with activities like swimming. Overall, the presence of human settlement has a demonstrated negative impact upon adjoining wetlands. An equally serious problem is the tendency to stabilize lake or river levels with dams. Dams removed the spring flood, which carries nutrients into littoral zones and reduces the natural fluctuation of water levels upon which many wetland plants and animals depend. Hence, over time, dams can reduce the area of wetland from a broad littoral zone to a narrow band of vegetation. Marshes and wet meadows are at particular risk. + +== Habitats in littoral zones == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Littoral_zone-2.md b/data/en.wikipedia.org/wiki/Littoral_zone-2.md new file mode 100644 index 000000000..d00620e6c --- /dev/null +++ b/data/en.wikipedia.org/wiki/Littoral_zone-2.md @@ -0,0 +1,19 @@ +--- +title: "Littoral zone" +chunk: 3/3 +source: "https://en.wikipedia.org/wiki/Littoral_zone" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:17.722778+00:00" +instance: "kb-cron" +--- + +Many vertebrates (e.g., mammals, waterfowl, reptiles) and invertebrates (insects, etc.) use both the littoral zone as well as the terrestrial ecosystem for food and habitat. Biota that are commonly assumed to reside in the pelagic zone often rely heavily on resources from the littoral zone. Littoral areas of ponds and lakes are typically better oxygenated, structurally more complex, and afford more abundant and diverse food resources than do profundal sediments. All these factors lead to a high diversity of insects and very complex trophic interactions. +The great lakes of the world represent a global heritage of surface freshwater and aquatic biodiversity. Species lists for 14 of the world's largest lakes reveal that 15% of the global diversity (the total number of species) of freshwater fishes, 9% of non-insect freshwater invertebrate diversity, and 2% of aquatic insect diversity live in this handful of lakes. The vast majority (more than 93%) of species inhabit the shallow, nearshore littoral zone, and 72% are completely restricted to the littoral zone, even though littoral habitats are a small fraction of total lake areas. +Because the littoral zone is important for many recreational and industrial purposes, it is often severely affected by many human activities that increase nutrient loading, spread invasive species, cause acidification and climate change, and produce increased fluctuations in water level. Littoral zones are both more negatively affected by human activity and less intensively studied than offshore waters. Conservation of the remarkable biodiversity and biotic integrity of large lakes will require better integration of littoral zones into our understanding of lake ecosystem functioning and focused efforts to alleviate human impacts along the shoreline. + +== See also == + +== References == + +=== Sources === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Longhurst_code-0.md b/data/en.wikipedia.org/wiki/Longhurst_code-0.md new file mode 100644 index 000000000..b600e99e9 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Longhurst_code-0.md @@ -0,0 +1,17 @@ +--- +title: "Longhurst code" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Longhurst_code" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:18.907502+00:00" +instance: "kb-cron" +--- + +Longhurst code refers to a set of geospatial four-letter geocodes for referencing geographic regions in oceanography. +The set of 56 geocodes represent biogeochemical provinces that partition the pelagic environment. It is assumed that each province represents a unique set of environmental conditions. +They are named after Alan R. Longhurst, the author of "Ecological Geography of the Sea", the textbook in which these codes are defined. +These codes have also been used in bioinformatic databases such as IMGTooltip Integrated Microbial Genomes to represent sample origins for sequenced microbial genomes, as a supplement to latitude and longitude coordinate metrics. + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Longshore_drift-0.md b/data/en.wikipedia.org/wiki/Longshore_drift-0.md new file mode 100644 index 000000000..8b45f102b --- /dev/null +++ b/data/en.wikipedia.org/wiki/Longshore_drift-0.md @@ -0,0 +1,54 @@ +--- +title: "Longshore drift" +chunk: 1/3 +source: "https://en.wikipedia.org/wiki/Longshore_drift" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:20.233864+00:00" +instance: "kb-cron" +--- + +Longshore drift from longshore current is a geological process that consists of the transportation of sediments (clay, silt, pebbles, sand, shingle, shells) along a coast parallel to the shoreline, which is dependent on the angle of incoming wave direction. Oblique incoming wind squeezes water along the coast, generating a water current that moves parallel to the coast. Longshore drift is simply the sediment moved by the longshore current. This current and sediment movement occurs within the surf zone. The process is also known as littoral drift. +Beach sand is also moved on such oblique wind days, due to the swash and backwash of water on the beach. Breaking surf sends water up the coast (swash) at an oblique angle and gravity then drains the water straight downslope (backwash) perpendicular to the shoreline. Thus beach sand can move downbeach in a sawtooth fashion many tens of meters (yards) per day. This process is called "beach drift", but some workers regard it as simply part of "longshore drift" because of the overall movement of sand parallel to the coast. +Longshore drift affects numerous sediment sizes as it works in slightly different ways depending on the sediment (e.g. the difference in long-shore drift of sediments from a sandy beach to that of sediments from a shingle beach). Sand is largely affected by the oscillatory force of breaking waves, the motion of sediment due to the impact of breaking waves and bed shear from long-shore current. Because shingle beaches are much steeper than sandy ones, plunging breakers are more likely to form, causing the majority of longshore transport to occur in the swash zone, due to a lack of an extended surf zone. + +== Development of longshore drift theories == + +The concept of longshore drift or transportation of sediment parallel to the shore by wave action has evolved considerably with time. Early observations related to sediment displacement can be traced back to coastal communities, but the formal scientific understanding of this started crystallising in the 19th and early 20th centuries. While such early perceptions were imprecise, this evolution has encouraged a gradually more sophisticated understanding of the processes occurring at coastlines. Understanding of the coastline processes has continued to evolve through a succession of developments that began many years ago. + +=== Early observations === +Erosion of coasts and sediment transport was known in ancient times, mostly in those parts of the world where dramatic changes of shores take place. However, these early observations were largely anecdotal. Fishermen, sailors and locals would note that sand and gravel seemingly "moved" down the beaches; they didn't fully understand the mechanics, however. Because of the general scientific knowledge, this was an interesting but somewhat misunderstood phenomenon. + +=== 19th century: first scientific studies === +The systematic investigation into the coast processes, including those responsible for longshore drift, began in the mid-1800s when scientists tried to explain the processes of sediment movement along coasts. Among the first of such theories were those proposed by a French engineer, Jean-Baptiste Fourier, and an Irish geologist, Robert Mallet. They studied wave action and sediment transport; however, at that time, the term "longshore drift" was not yet coined. Instead, the principal focus was to understand the processes of waves and their impact on the resuspension and movement of sand and pebbles. The subject was of primary importance because it helped to explain the morphological features of any coast. However, while much is covered, the complete significance of such mechanisms was yet to be fully realised. + +=== 20th century: longshore drift defined === +In the early years of the 20th century, longshore drift became much more refined in its explanation through oceanographers and coastal engineers. They realised that the angle of wave approach to the coast is of paramount importance to sediment transport. This then led to the development in the concept of "longshore currents," which in turn transport sediment along the coast. These currents then became recognised as the main agent of longshore drift. An important concept which emerged during this generation was that of the "drift-aligned" beach. It explained how beaches get to form as a result of prevailing wind and wave directions and that on one side of the beach deposition takes place, while on the other side, erosion does. While the mechanics were becoming more apparent, the interrelationship of the forces in play still proved quite problematic for those trying to manage coasts. + +== Overview == + +=== Longshore drift formulas === +Numerous calculations take into consideration the factors that produce longshore drift. +These formulations are: + +Bijker formula (1967, 1971) +The Engelund and Hansen formula (1967) +The Ackers and White formula (1973) +The Bailard and Inman formula (1981) +The Van Rijn formula (1984) +The Watanabe formula (1992) +These formulas provide a different view of the processes that generate longshore drift. The most common factors taken into consideration in these formulas are: + +Suspended and bed load transport +Waves, e.g., breaking and non-breaking +The shear exerted by waves or the flow associated with waves. + +=== Features of shoreline change === +Longshore drift plays a large role in the evolution of a shoreline, as if there is a slight change of sediment supply, wind direction, or any other coastal influence longshore drift can change dramatically, affecting the formation and evolution of a beach system or profile. These changes do not occur due to one factor within the coastal system, in fact there are numerous alterations that can occur within the coastal system that may affect the distribution and impact of longshore drift. +Some of these are: + +Geological changes, e.g. erosion, backshore changes and emergence of headlands. +Change in hydrodynamic forces, e.g. change in wave diffraction in headland and offshore bank environments. +Change to hydrodynamic influences, e.g. the influence of new tidal inlets and deltas on drift. +Alterations of the sediment budget, e.g. switch of shorelines from drift to swash alignment, exhaustion of sediment sources. +The intervention of humans, e.g. cliff protection, groynes, detached breakwaters. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Longshore_drift-1.md b/data/en.wikipedia.org/wiki/Longshore_drift-1.md new file mode 100644 index 000000000..f57422e39 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Longshore_drift-1.md @@ -0,0 +1,54 @@ +--- +title: "Longshore drift" +chunk: 2/3 +source: "https://en.wikipedia.org/wiki/Longshore_drift" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:20.233864+00:00" +instance: "kb-cron" +--- + +=== The sediment budget === +The sediment budget takes into consideration sediment sources and sinks within a system. This sediment can come from any source with examples of sources and sinks consisting of: + +Rivers +Lagoons +Eroding land sources +Artificial sources e.g. nourishment +Artificial sinks e.g. mining/extraction +Offshore transport +Deposition of sediment on shore +Gullies through the land +This sediment then enters the coastal system and is transported by longshore drift. A good example of the sediment budget and longshore drift working together in the coastal system is inlet ebb-tidal shoals, which store sand that has been transported by long-shore transport. As well as storing sand these systems may also transfer or by pass sand into other beach systems, therefore inlet ebb-tidal (shoal) systems provide good sources and sinks for the sediment budget. +Sediment deposition throughout a shoreline profile conforms to the null point hypothesis; where gravitational and hydraulic forces determine the settling velocity of grains in a seaward fining sediment distribution. Long shore occurs in a 90 to 80 degree backwash so it would be presented as a right angle with the wave line. + +== Natural features == +This section consists of features of longshore drift that occur on a coast where long-shore drift occurs uninterrupted by man-made structures. + +=== Spits === + +Spits are formed when longshore drift travels past a point (e.g. river mouth or re-entrant) where the dominant drift direction and shoreline do not veer in the same direction. As well as dominant drift direction, spits are affected by the strength of wave-driven current, wave angle and the height of incoming waves. +Spits are landforms that have two important features, with the first feature being the region at the up-drift end or proximal end (Hart et al., 2008). The proximal end is constantly attached to land (unless breached) and may form a slight “barrier” between the sea and an estuary or lagoon (called peresyp in the Russian tradition of geomorphology). The second important spit feature is the down-drift end or distal end, which is detached from land and in some cases, may take a complex hook-shape or curve, due to the influence of varying wave directions. +As an example, the New Brighton spit in Canterbury, New Zealand, was created by longshore drift of sediment from the Waimakariri River to the north. This spit system is currently in equilibrium but undergoes alternate phases of deposition and erosion. + +=== Barriers === + +Barrier systems are attached to the land at both the proximal and distal ends and are generally widest at the down-drift end. These barrier systems may enclose an estuary or lagoon system, like that of Lake Ellesmere / Te Waihora enclosed by the Kaitorete Spit or hapua which form at river-coast interface such as at the mouth of the Rakaia River. +The Kaitorete Spit in Canterbury, New Zealand, is a barrier/spit system (which generally falls under the definition of barrier, as both ends of the landform are attached to land, but has been named a spit) that has existed below Banks Peninsula for the last 8,000 years. This system has undergone numerous changes and fluctuations due to avulsion of the Waimakariri River (which now flows to the north of Banks Peninsula), erosion and phases of open marine conditions. The system underwent further changes c. 500 years Before Present, when longshore drift from the eastern end of the “spit” system created the barrier, which has been retained due to ongoing longshore transport. + +=== Tidal inlets === + +The majority of tidal inlets on longshore drift shores accumulate sediment in flood and ebb shoals. Ebb-deltas may become stunted on highly exposed shores and in smaller spaces, whereas flood deltas are likely to increase in size when space is available in a bay or lagoon system. Tidal inlets can act as sinks and sources for large amounts of material, which therefore impacts on adjacent parts of the coastline. +The structuring of tidal inlets is also important for longshore drift: if an inlet is unstructured, sediment may by-pass the inlet and form bars at the down-drift part of the coast. This may also depend on the inlet size, delta morphology, sediment rate and by-passing mechanism. Channel location variance and amount may also influence the impact of longshore drift on a tidal inlet. +Arcachon lagoon in southwest France is an example of a tidal inlet system, which provides large sources and sinks for longshore drift sediments. The impact of longshore drift sediments on this inlet system is highly influenced by the variation in the number of lagoon entrances and the location of these entrances. Any change in these factors can cause severe down-drift erosion or down-drift accretion of large swash bars. + +=== Sand Islands === + +Where longshore drift is interrupted by other natural features, sufficient sediment deposition can occur to form long-term land structures extending off the coast. The formation process is similar to that of a Barrier island. +K'gari is the largest sand island in the world, located on Australia's east coast, and was formed from interrupted northerly longshore drift. +Over extensive periods, drifting sediment can 'leak' into deeper water, where the wind and waves driving longshore drift are weaker. This allows extensive sediment deposits to be built up off-shore, which is gradually transferred back to the coast as the sea level falls in long-term glacial cycles. + +== Human influences == +This section consists of long-shore drift features that occur unnaturally and in some cases (e.g. groynes, detached breakwaters) have been constructed to enhance the effects of longshore drift on the coastline but in other cases have a negative impact on long-shore drift (ports and harbours). + +=== Groynes === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Longshore_drift-2.md b/data/en.wikipedia.org/wiki/Longshore_drift-2.md new file mode 100644 index 000000000..197e3674d --- /dev/null +++ b/data/en.wikipedia.org/wiki/Longshore_drift-2.md @@ -0,0 +1,59 @@ +--- +title: "Longshore drift" +chunk: 3/3 +source: "https://en.wikipedia.org/wiki/Longshore_drift" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:20.233864+00:00" +instance: "kb-cron" +--- + +Groynes are shore protection structures, placed at equal intervals along the coastline in order to stop coastal erosion and generally cross the intertidal zone. Due to this, groyne structures are usually used on shores with low net and high annual longshore drift in order to retain the sediments lost in storm surges and further down the coast. +There are numerous variations to groyne designs with the three most common designs consisting of: + +zig-zag groynes, which dissipate the destructive flows that form in wave-induced currents or in breaking waves. +T-head groynes, which reduce wave height through wave diffraction. +‘Y’ head, a fish-tail groyne system. + +=== Artificial headlands === +Artificial headlands are also shore protection structures, which are created in order to provide a certain amount of protection to beaches or bays. Although the creation of headlands involves accretion of sediments on the up-drift side of the headland and moderate erosion of the down-drift end of the headland, this is undertaken in order to design a stabilised system that allows material to accumulate in beaches further along the shore. +Artificial headlands can occur due to natural accumulation or also through artificial nourishment. + +=== Detached breakwaters === +Detached breakwaters are shore protection structures, created to build up sandy material in order to accommodate drawdown in storm conditions. In order to accommodate drawdown in storm conditions detached breakwaters have no connection to the shoreline, which lets currents and sediment pass between the breakwater and the shore. This then forms a region of reduced wave energy, which encourages the deposition of sand on the lee side of the structure. +Detached breakwaters are generally used in the same way as groynes, to build up the volume of material between the coast and the breakwater structure in order to accommodate storm surges. + +=== Ports and harbours === +The creation of ports and harbours throughout the world can seriously impact on the natural course of longshore drift. Not only do ports and harbours pose a threat to longshore drift in the short term, they also pose a threat to shoreline evolution. The major influence, which the creation of a port or harbour can have on longshore drift, is the alteration of sedimentation patterns, which in turn may lead to accretion and/or erosion of a beach or coastal system. +As an example, the creation of a port in Timaru, New Zealand in the late 19th century led to a significant change in the longshore drift along the South Canterbury coastline. Instead of longshore drift transporting sediment north up the coast towards the Waimataitai lagoon, the creation of the port blocked the drift of these (coarse) sediments and instead caused them to accrete to the south of the port at South beach in Timaru. The accretion of this sediment to the south, therefore meant a lack of sediment being deposited on the coast near the Waimataitai lagoon (to the north of the port), which led to the loss of the barrier enclosing the lagoon in the 1930s and then shortly after, the loss of the lagoon itself. As with the Waimataitai lagoon, the Washdyke Lagoon, which currently lies to the north of the Timaru port, is undergoing erosion and may eventually breach, causing loss of another lagoon environment. + +== See also == +Beach evolution +Beach erosion and accretion +Coastal management, to prevent coastal erosion and creation of beach +Coastal erosion +Coastal geography +Sand dune stabilisation + +== References == + +=== Citations === + +=== Books === +Bruun, Per, ed. (2005). Port and coastal engineering developments in Science and technology. South Carolina: P. Bruun. +Hart, D.E; Marsden, I; Francis, M (2008). "Chapter 20: Coastal systems". In Winterbourne, M; Knox, G.A.; Marsden, I.D.; Burrows, C (eds.). Natural history of Canterbury (3rd ed.). Canterbury University Press. pp. 653–684. +Reeve, D; Chadwick, A; Fleming, C (2004). Coastal engineering-processes, theory and design practice. New York: Spon Press. + +=== Journal articles === +Kirk, R.M; Lauder, G.A (2000). "Significant coastal lagoon systems in the South Island, New Zealand". Science for Conservation. DOC 46p: 13–24. +Michel, D; Howa, H.L (1997). "Morphodynamic behaviour of a tidal inlet system in a mixed-energy environment". Physics and Chemistry of the Earth. 22 (3–4): 339–343. Bibcode:1997PCE....22..339M. doi:10.1016/s0079-1946(97)00155-9. +Peterson, D; Deigaard, R; Fredsoe, J (July 2008). "Modelling the morphology of sandy spits". Coastal Engineering. 55 (7–8): 671–684. Bibcode:2008CoasE..55..671P. doi:10.1016/j.coastaleng.2007.11.009. +Soons, J.M; Schulmeister, J; Holt, S (April 1997). "The Holocene evolution of a well nourished gravelly barrier and lagoon complex, Kaitorete "Spit", Canterbury, New Zealand". Marine Geology. 26 (1–2): 69–90. Bibcode:1997MGeol.138...69S. doi:10.1016/S0025-3227(97)00003-0. + +== External links == +Photos, animation and explanation for schools, geography-site.co.uk +Intranet.lissjunior.hants.sch.uk has a brief animation on longshore drift. +USGS — Coastal Erosion on Cape Cod, woodshole.er.usgs.gov +Shore drift, ecy.wa.gov +Longshore drift in South Carolina, cofc.edu +British Geological Survey: portable streamer traps for longshore sediment transport measurement \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Lower_oceanic_crust-0.md b/data/en.wikipedia.org/wiki/Lower_oceanic_crust-0.md new file mode 100644 index 000000000..521dd5c44 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Lower_oceanic_crust-0.md @@ -0,0 +1,32 @@ +--- +title: "Lower oceanic crust" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Lower_oceanic_crust" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:21.427862+00:00" +instance: "kb-cron" +--- + +The lower oceanic crust is the lower part of the oceanic crust and represents the major part of it (the largest part by volume). It is generally located 4–8 km below the ocean floor and the major lithologies are mafic (ultramafic and gabbroic rocks) which derive from melts rising from the Earth's mantle. This part of the oceanic crust is an important zone for processes such as melt accumulation and melt modification (fractional crystallisation and crustal assimilation). The recycling of this part of the oceanic crust, together with the upper mantle has been suggested as a significant source component for tholeiitic magmas in Hawaiian volcanoes. Although the lower oceanic crust builds the link between the mantle and the MORB, and can't be neglected for the understanding of MORB evolution, the complex processes operating in this zone remain unclear and there is an ongoing debate in Earth Sciences about this. It is 6KM long. + + +== Processes == +The lower oceanic crust connects the Earth's mantle with the MORB, where around 60% of the total magma production of the Earth happens. The three main processes happening in this region of the oceanic crust are partial melting of the Earth's mantle, melt accumulation at various depths and the chemical modification of this melts during ascent,. This three processes do not happen in a strict order but occur all simultaneously over a depth range of 4–18 km suggesting that these processes can occur already in the upper mantle. The mantle melts are most commonly modified by fractional crystallisation due to cooling and by assimilation of crustal rocks. + + +== Spreading rates == +The most important parameter controlling the processes operating in the lower oceanic crust is the magma supply, this is further controlled by the spreading rate, and therefore, spreading rate is a critical variable in models for the formation of the lower oceanic crust. The rate at which plate divergence occurs at mid-ocean ridges is not the same for all ridge segments. Ridges with a spreading rate less than 3 cm/a are considered slow-spreading ridges, while those with a rate greater than 5 cm/a are considered fast-spreading ridges + + +=== Fast-spreading ridges === +Intensive search spanning over three decades of seismic imaging have shown that the ridge axis is underlain by a crystal mush containing a small percentage of melt, capped by a thin melt lens containing a generally high, but variable melt fraction. The completely liquid body is a thin and narrow sill-like lens (10 to 150 m [33 to 492 ft] thick and < 2 km [1.2 mi] wide). The lens is maintained by reinjection of primitive magma. The lack of any detectable large magma chamber and the common detection of small lens/mush zone at fast-spreading ridges emphasize the small magma chamber model. +Modally and compositionally layered gabbroic rock is often found (or abundant) in the lower crustal sections of ophiolite. The layered lower crust is thus one of the key features of all models of fast-spreading lower crust. Nevertheless, distinct modal layering as observed in major ophiolites has rarely been observed or sampled on the ocean floor. The IODP expedition 345 was one of the first drilling project, which sampled a significant thickness of layered igneous rocks. A shallow melt can erupt through cool crust and produce sheeted dikes and volcanics, but the small chamber seems difficult to resolve with traditional ideas of fractional crystallization and crystal settling to form the thick sequence of layered gabbros and foliated gabbros and ultramafics. One proposed model is the so-called "gabbro glacier", where crystals settle in a shallow melt-dominated lens beneath the ridge axis. The weight of the accumulating crystals settling to the bottom of the magma lens induces a ductile flow and deformation within the gabbros, just like the ice in a glacier responds to accumulated snow. Nevertheless, the model fails to explain the layered variations in mineral types, the correlated layering in mineral compositional variations, and the apparently primary near-vertical fabrics in the upper gabbros that appear to represent subvertical melt conduits. Kelemen and co-workers concluded that most of the lower oceanic crust crystallized in place, and proposed "the sheeted sill" model. In the model the sills form when porous flow of rising basaltic liquids (or small melt-filled fractures) are stopped beneath permeability (earth sciences) barriers of earlier crystallized melts and pond to form the sills. Cooling rates are generally sufficiently slow that crystals and their interstitial liquids are in chemical equilibrium, as long as the liquid is immobile. However, buoyancy and/or compaction (geology) may induce liquid migration through the mush, resulting a significant compositional and microstructural modification. + + +=== Slow-spreading ridges === +Slow- and intermediate-spreading ridges form typically valleys about 30 to 50 km (19 to 31 mi) wide and 1 to 5 km (0.62 to 3.11 mi) deep, with step-like inward-facing scarps, similar to rift valleys on land. Compared to fast spreading-ridges, the magma supply and therefore the heat flow is low and can't maintain a persistent liquid magma chamber. Sinton and Detrick (1992) modelled a schematic cross section of an axial magma chamber beneath a slow-spreading ridge such as the Mid-Atlantic Ridge. Due to the reduced heat and magma supply, a steady-state eruptible magma lens is relinquished in favor of a sill-like mush zone and a smaller transition zone beneath the well-developed rift valley. Convection and mixing in the magma chamber is far less likely than at fast ridges. +Thermal constrains led to the development of different models to reconstruct the accretion history. The "infinite leek" model suggests small magma batches, forming small "nested" intrusions. Another model proposed that crystallization could occur at depth, where temperatures are higher, the formed cumulates are then "dragged" up by mantle flow to form the lower oceanic crust. Today, a model intermediate between these two has become popular. This model is referred to as a "plum pudding", where the lower oceanic crust is constructed from a number of nested plutons that crystallize within the mantle or crust. Schwartz et al. (2005) describes another variant. He postulates that the lower crust is constructed both from the nested shallow-level plutons and from the products of deeper-seated crystallization + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Man_and_Matter-0.md b/data/en.wikipedia.org/wiki/Man_and_Matter-0.md new file mode 100644 index 000000000..21cecbd08 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Man_and_Matter-0.md @@ -0,0 +1,47 @@ +--- +title: "Man and Matter" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Man_and_Matter" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:43.608386+00:00" +instance: "kb-cron" +--- + +Man and Matter - Essays Scientific & Christian is a 1951 book written by a British chemist, museum curator and historian of science Frank Sherwood Taylor. The work presents a critical mind's account of the clash between religion and science. It provides insights into a unique perspective of a person, who has been received into the Catholic Church after forty years of struggling to find his way in a conflicted world of scientific and religious explanations. +The book consists of a preface, personal introduction, and twelve essays, read to the followers of the Catholic Church. The essays reflect on various, more or less controversial issues dividing religion and science, such as materialism, pain, and morality. They have been written at different times and therefore represent the shifting views of the author, as he searches for decisive arguments. All essays have been intended to fall in line with "the Christian doctrine and common sense". + + +== Book contents == + + +=== Preface === +In the preface, the author informs the reader of the position he has assumed when writing the essays - one of a formerly confused, but now reassured, believer. + + +=== Personal introduction === +First chapter, adequately titled Personal Introduction, gives insightful information on why a scientifically inclined and critical person would choose to return to Church, after having been exposed to various religious and scientific influences throughout life. This chapter provides rich insights into author's early experiences, such as growing up in an Anglican family, receiving Christian education, praying, learning the Bible, and partaking in various religious customs and traditions, all very typical of the times, place, and author's social class. However, despite these influences, Sherwood Taylor had great difficulties accepting faith and religion as they were presented to him. Realization that religion might lack rational foundation has severely swayed his views, and initiated an over 40-year long journey in quest of an ultimate verdict between religion and materialism. Along the way, the author has encountered themes such as mind and body, physical concepts of extension, mass, and motion, perception, superstitions, consciousness, spiritualism, qualia and many more, all having great influence on the author and contributing to his understanding of the world, but still not decisive. Sherwood Taylor's problem with materialism lied in its inability to account for mental experiences, and for the sense of "self" as a thinking entity. Additionally, scientific praise of determinism was hardly in line with Sherwood Taylor's belief in will and choice. Despite his great respect for science, the author started to find it increasingly difficult to believe that science could ever explain his life, thoughts, and experiences, his poetic, and mystic side, desperately searching for God. +A pivotal turn took place, when F. Sherwood Taylor accidentally received a letter meant for a member of the Rationalist Press Association, asking to give a lecture on Galileo. Despite a mistake, Sherwood Taylor offered his services, and soon found himself an expert on Galileo's case. While investigating the matter, he came to the conclusion, that Galileo's story was full of deliberate distortions implemented by anti-Catholic and "rational" writers. This made him realize that science is guilty of all the offences usually assigned to Church - it's ill-founded, wicked, deceitful, and superstitious. Following this and other events, including hearing a voice in his head say "Why are you wasting your life?", F. Sherwood Taylor started to see Christianity as the purest and most intelligible of religions, offering so long-sought solutions to many countless problems of life. Additionally, his career in chemistry begun to feel uncomfortable, as it was contributing to a materialist worldview. He joined the Roman Catholic Church, and, although not without doubts, has made up his mind. +The remaining of the book presents 12 essays, which are F. Sherwood Taylor's attempt at progressive, but not final, integration of the religious and scientific methodologies and ways of considering and understanding the world. + + +=== Essays === +The Deficiencies of Materialism +Science, Philosophy and Religion +Biology and Man +Evolution and Religion +The Problem of Pain in Nature +On the Excellence of Things +The Vocation of Science +The Place of Science in Christian Education +Some Moral Problems Raised by Science +The Church and Science +Mysticism, Christian and Pagan +The Catholic Layman and His Responsibilities + + +== Reception == +The book has been reviewed by Sister Francis Augustine Richey, who regards the author as "a distinguished scientist, a convert moreover from the fringes of scientism to catholicism, a writer with a singularly gifted mind, sensitive, imaginative, intuitive and logical". She states, that as a chemist and historian of science, Sherwood Taylor relies on experience, and writes from a position that emphasizes the appreciation of science. However, he does so in a thoughtful and critical manner, raising "an inspiring call into the battle against materialism". He engages in a careful analysis of scientific method and knowledge, and does so from an easily approachable objective perspective, which Sister Francis Augustine Richey calls "impersonally personal". She describes the book as valuable and illuminating for "teacher and pupil whether of science, philosophy, or religion". + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Mangrove-0.md b/data/en.wikipedia.org/wiki/Mangrove-0.md new file mode 100644 index 000000000..9c6afaf95 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Mangrove-0.md @@ -0,0 +1,40 @@ +--- +title: "Mangrove" +chunk: 1/7 +source: "https://en.wikipedia.org/wiki/Mangrove" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:22.795957+00:00" +instance: "kb-cron" +--- + +A mangrove is a shrub or tree that grows mainly in coastal saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have particular adaptations to take in extra oxygen and remove salt, allowing them to tolerate conditions that kill most plants. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse due to convergent evolution in several plant families. They occur worldwide in tropical and subtropical coastal areas, mainly between latitudes 30° N and 30° S, with the greatest mangrove area within 5° of the equator. Mangrove plant families first appeared during the Late Cretaceous to Paleocene epochs and became widely distributed in part due to the movement of tectonic plates. The oldest known fossils of mangrove palm date to 75 million years ago. +Mangroves are salt-tolerant (halophytic) and are adapted to live in harsh coastal conditions. They contain a complex salt filtration system and a complex root system to cope with saltwater immersion and wave action. They are adapted to the low-oxygen conditions of waterlogged mud, but are most likely to thrive in the upper half of the intertidal zone. +The mangrove biome, often called the mangrove forest or mangal, is a distinct saline woodland or shrubland habitat characterized by depositional coastal environments, where fine sediments (often with high organic content) collect in areas protected from high-energy wave action. The saline conditions tolerated by various mangrove species range from brackish water, through pure seawater (3 to 4% salinity), to water concentrated by evaporation to over twice the salinity of ocean seawater (up to 9% salinity). +Beginning in 2010, remote sensing technologies and global data have been used to assess areas, conditions and deforestation rates of mangroves around the world. In 2018, the Global Mangrove Watch Initiative released a new global baseline which estimates the total mangrove forest area of the world as of 2010 at 137,600 km2 (53,100 sq mi), spanning 118 countries and territories. A 2022 study on losses and gains of tidal wetlands estimates a 3,700 km2 (1,400 sq mi) net decrease in global mangrove extent from 1999 to 2019. Mangrove loss continues due to human activity, with a global annual deforestation rate estimated at 0.16%, and per-country rates as high as 0.70%. Degradation in quality of remaining mangroves is also an important concern. +There is interest in mangrove restoration for several reasons. Mangroves support sustainable coastal and marine ecosystems. They protect nearby areas from tsunamis and extreme weather events. Mangrove forests are also effective at carbon sequestration and storage. The success of mangrove restoration may depend heavily on engagement with local stakeholders, and on careful assessment to ensure that growing conditions will be suitable for the species chosen. +In 2025, the area of mangroves globally is estimated at 15.9 million hectares. Asia has the largest area, at 6.10 million ha, and Europe reported no mangrove area. Among countries and areas, Indonesia has the world’s largest extent of mangroves, at 3.40 million ha, followed by Brazil (1.39 million ha), Australia (1.11 million ha), Nigeria (976 000 ha) and Mexico (947 000 ha). Collectively, these five countries host almost half (49%) of the global mangrove area. +The International Day for the Conservation of the Mangrove Ecosystem is celebrated every year on 26 July. + +== Etymology == + +Etymology of the English term mangrove is speculative and disputed. +The term may have come to English from the Portuguese mangue or the Spanish +mangle. Further back, it may be traced to South America and Cariban and Arawakan languages such as Taíno. Other possibilities include the Malay language manggi-manggi. +The English usage may reflect a corruption via folk etymology of the words mangrow and grove. +The word "mangrove" is used in at least three senses: + +Most broadly to refer to the habitat and entire plant assemblage or mangal, for which the terms mangrove forest biome and mangrove swamp are also used; +To refer to all trees and large shrubs in a mangrove swamp; and +Narrowly to refer only to mangrove trees of the genus Rhizophora of the family Rhizophoraceae. + +== Biology == +According to Hogarth (2015), among the recognized mangrove species there are about 70 species in 20 genera from 16 families that constitute the "true mangroves" – species that occur almost exclusively in mangrove habitats. Demonstrating convergent evolution, many of these species found similar solutions to the tropical conditions of variable salinity, tidal range (inundation), anaerobic soils, and intense sunlight. Plant biodiversity is generally low in a given mangrove. The greatest biodiversity of mangroves occurs in Southeast Asia, particularly in the Indonesian archipelago. + +=== Adaptations to low oxygen === +The red mangrove (Rhizophora mangle) survives in the most inundated areas, props itself above the water level with stilt or prop roots and then absorbs air through lenticels in its bark. +The black mangrove (Avicennia germinans) lives on higher ground and develops many specialized root-like structures called pneumatophores, which stick up out of the soil like straws for breathing. +These "breathing tubes" typically reach heights of up to 30 cm (12 in), and in some species, over 3 m (9.8 ft). The roots also contain wide aerenchyma to facilitate transport within the plants. + +=== Nutrient uptake === +Because the soil is perpetually waterlogged, little free oxygen is available. Anaerobic bacteria liberate nitrogen gas, soluble ferrum (iron), inorganic phosphates, sulfides, and methane, which make the soil much less nutritious. Pneumatophores (aerial roots) allow mangroves to absorb gases directly from the atmosphere, and other nutrients such as iron, from the inhospitable soil. Mangroves store gases directly inside the roots, processing them even when the roots are submerged during high tide. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Mangrove-1.md b/data/en.wikipedia.org/wiki/Mangrove-1.md new file mode 100644 index 000000000..912179c26 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Mangrove-1.md @@ -0,0 +1,36 @@ +--- +title: "Mangrove" +chunk: 2/7 +source: "https://en.wikipedia.org/wiki/Mangrove" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:22.795957+00:00" +instance: "kb-cron" +--- + +=== Limiting salt intake === +Red mangroves exclude salt by having significantly impermeable roots that are highly suberised (impregnated with suberin), acting as an ultrafiltration mechanism to exclude sodium salts from the rest of the plant. One study found that roots of the Indian mangrove Avicennia officinalis exclude 90% to 95% of the salt in water taken up by the plant, depositing the excluded salt in the cortex of the root. An increase in the production of suberin and in the activity of a gene regulating cytochrome P450 were observed in correlation with an increase in the salinity of the water to which the plant was exposed. In a frequently cited concept that has become known as the "sacrificial leaf", salt which does accumulate in the shoot (sprout) then concentrates in old leaves, which the plant then sheds. However, recent research on the Red mangrove Rhizophora mangle suggests that the older, yellowing leaves have no more measurable salt content than the other, greener leaves. + +=== Limiting water loss === + +Because of the limited fresh water available in salty intertidal soils, mangroves limit the amount of water they lose through their leaves. They can restrict the opening of their stomata (pores on the leaf surfaces, which exchange carbon dioxide gas and water vapor during photosynthesis). They also vary the orientation of their leaves to avoid the harsh midday sun and so reduce evaporation from the leaves. A captive red mangrove grows only if its leaves are misted with fresh water several times a week, simulating frequent tropical rainstorms. + +=== Filtration of seawater === +A 2016 study by Kim et al. investigated the biophysical characteristics of sea water filtration in the roots of the mangrove Rhizophora stylosa from a plant hydrodynamic point of view. R. stylosa can grow even in saline water and the salt level in its roots is regulated within a certain threshold value through filtration. The root possesses a hierarchical, triple layered pore structure in the epidermis and most Na+ ions are filtered at the first sublayer of the outermost layer. The high blockage of Na+ ions is attributed to the high surface zeta potential of the first layer. The second layer, which is composed of macroporous structures, also facilitates Na+ ion filtration. The study provides insights into the mechanism underlying water filtration through halophyte roots and could serve as a basis for the development of a bio-inspired method of desalination. +Uptake of Na+ ions is desirable for halophytes to build up osmotic potential, absorb water and sustain turgor pressure. However, excess Na+ ions may work on toxic element. Therefore, halophytes try to adjust salinity delicately between growth and survival strategies. In this point of view, a novel sustainable desalination method can be derived from halophytes, which are in contact with saline water through their roots. Halophytes exclude salt through their roots, secrete the accumulated salt through their aerial parts and sequester salt in senescent leaves and/or the bark. Mangroves are facultative halophytes and Bruguiera is known for its special ultrafiltration system that can filter approximately 90% of Na+ions from the surrounding seawater through the roots. The species also exhibits a high rate of salt rejection. The water-filtering process in mangrove roots has received considerable attention for several decades. Morphological structures of plants and their functions have been evolved through a long history to survive against harsh environmental conditions. + +=== Increasing survival of offspring === + +In this harsh environment, mangroves have evolved a special mechanism to help their offspring survive. Mangrove seeds are buoyant and are therefore suited to water dispersal. Unlike most plants, whose seeds germinate in soil, many mangroves (e.g. red mangrove) are viviparous, meaning their seeds germinate while still attached to the parent tree. Once germinated, the seedling grows either within the fruit (e.g. Aegialitis, Avicennia and Aegiceras), or out through the fruit (e.g. Rhizophora, Ceriops, Bruguiera and Nypa) to form a propagule (a ready-to-go seedling) which can produce its own food via photosynthesis. +The mature propagule then drops into the water, which can transport it great distances. The propagules of some species, such as red mangrove, can survive desiccation and remain buoyant and viable for up to a year before arriving in a suitable environment. Once in a suitable, low salinity environment, air-filled intercellular spaces flood with water so that the elongated shape now floats vertically rather than horizontally. In this position, it is more likely to lodge in the mud and root. If it does not root, it can regain buoyancy and drift again in search of more favorable conditions. + +== Taxonomy and evolution == +The following listings, based on Tomlinson, 2016, give the mangrove species in each listed plant genus and family. Mangrove environments in the Eastern Hemisphere harbor six times as many species of trees and shrubs as do mangroves in the New World. Genetic divergence of mangrove lineages from terrestrial relatives, in combination with fossil evidence, suggests mangrove diversity is limited by evolutionary transition into the stressful marine environment, and the number of mangrove lineages has increased steadily over the Tertiary with little global extinction. However, the first mangroves were composed of marine taxa that had become adapted to coastal, brackish environments, and these are documented as early as the Pennsylvanian, and other examples are known from the early Cisuralian. It is likely that mangroves are even older than that, given that life originated in the seas, and that many environments previously thought to be freshwater (and many of which had an abundant flora) display evidence of marine influence. + +=== True mangroves === + +=== Other mangroves === + +== Species distribution == + +Mangroves are a type of tropical vegetation with some outliers established in subtropical latitudes, notably in South Florida and southern Japan, as well as South Africa, New Zealand and Victoria (Australia). These outliers result either from unbroken coastlines and island chains or from reliable supplies of propagules floating on warm ocean currents from rich mangrove regions. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Mangrove-2.md b/data/en.wikipedia.org/wiki/Mangrove-2.md new file mode 100644 index 000000000..9e85ce994 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Mangrove-2.md @@ -0,0 +1,20 @@ +--- +title: "Mangrove" +chunk: 3/7 +source: "https://en.wikipedia.org/wiki/Mangrove" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:22.795957+00:00" +instance: "kb-cron" +--- + +"At the limits of distribution, the formation is represented by scrubby, usually monotypic Avicennia-dominated vegetation, as at Westonport Bay and Corner Inlet, Victoria, Australia. The latter locality is the highest latitude (38° 45'S) at which mangroves occur naturally. The mangroves in New Zealand, which extend as far south as 37°, are of the same type; they start as low forest in the northern part of the North Island but become low scrub toward their southern limit. In both instances, the species is referred to as Avicennia marina var. australis, although genetic comparison is clearly needed. In Western Australia, A. marina extends as far south as Bunbury (33° 19'S). In the northern hemisphere, scrubby Avicennia gerrninans in Florida occurs as far north as St. Augustine on the east coast and Cedar Point on the west. There are records of A. germinans and Rhizophora mangle for Bermuda, presumably supplied by the Gulf Stream. In southern Japan, Kandelia obovata occurs to about 31 °N (Tagawa in Hosakawa et al., 1977, but initially referred to as K. candel)." + +== Mangrove forests == + +Mangrove forests, also called mangrove swamps or mangals, are found in tropical and subtropical tidal areas. Areas where mangroves occur include estuaries and marine shorelines. +The intertidal existence to which these trees are adapted represents the major limitation to the number of species able to thrive in their habitat. High tide brings in salt water, and when the tide recedes, solar evaporation of the seawater in the soil leads to further increases in salinity. The return of tide can flush out these soils, bringing them back to salinity levels comparable to that of seawater. +At low tide, organisms are also exposed to increases in temperature and reduced moisture before being then cooled and flooded by the tide. Thus, for a plant to survive in this environment, it must tolerate broad ranges of salinity, temperature, and moisture, as well as several other key environmental factors—thus only a select few species make up the mangrove tree community. +About 110 species are considered mangroves, in the sense of being trees that grow in such a saline swamp, though only a few are from the mangrove plant genus, Rhizophora. However, a given mangrove swamp typically features only a small number of tree species. It is not uncommon for a mangrove forest in the Caribbean to feature only three or four tree species. For comparison, the tropical rainforest biome contains thousands of tree species, but this is not to say mangrove forests lack diversity. Though the trees themselves are few in species, the ecosystem that these trees create provides a home (habitat) for a great variety of other species, including as many as 174 species of marine megafauna. + +Mangrove plants require a number of physiological adaptations to overcome the problems of low environmental oxygen levels, high salinity, and frequent tidal flooding. Each species has its own solutions to these problems; this may be the primary reason why, on some shorelines, mangrove tree species show distinct zonation. Small environmental variations within a mangal may lead to greatly differing methods for coping with the environment. Therefore, the mix of species is partly determined by the tolerances of individual species to physical conditions, such as tidal flooding and salinity, but may also be influenced by other factors, such as crabs preying on plant seedlings. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Mangrove-3.md b/data/en.wikipedia.org/wiki/Mangrove-3.md new file mode 100644 index 000000000..5b6e97a42 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Mangrove-3.md @@ -0,0 +1,26 @@ +--- +title: "Mangrove" +chunk: 4/7 +source: "https://en.wikipedia.org/wiki/Mangrove" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:22.795957+00:00" +instance: "kb-cron" +--- + +Once established, mangrove roots provide an oyster habitat and slow water flow, thereby enhancing sediment deposition in areas where it is already occurring. The fine, anoxic sediments under mangroves act as sinks for a variety of heavy (trace) metals which colloidal particles in the sediments have concentrated from the water. Mangrove removal disturbs these underlying sediments, often creating problems of trace metal contamination of seawater and organisms of the area. +Mangrove swamps protect coastal areas from erosion, storm surge (especially during tropical cyclones), and tsunamis. They limit high-energy wave erosion mainly during events such as storm surges and tsunamis. +The mangroves' massive root systems are efficient at dissipating wave energy. Likewise, they slow down tidal water so that its sediment is deposited as the tide comes in, leaving all except fine particles when the tide ebbs. In this way, mangroves build their environments. Because of the uniqueness of mangrove ecosystems and the protection against erosion they provide, they are often the object of conservation programs, including national biodiversity action plans. +The unique ecosystem found in the intricate mesh of mangrove roots offers a quiet marine habitat for young organisms. In areas where roots are permanently submerged, the organisms they host include algae, barnacles, oysters, sponges, and bryozoans, which all require a hard surface for anchoring while they filter-feed. Shrimps and mud lobsters use the muddy bottoms as their home. Mangrove crabs eat the mangrove leaves, adding nutrients to the mangal mud for other bottom feeders. In at least some cases, the export of carbon fixed in mangroves is important in coastal food webs. +Larger marine organisms benefit from the habitat as a nursery for their offspring. Lemon sharks depend on mangrove creeks to give birth to their pups. The ecosystem provides little competition and minimizes threats of predation to juvenile lemon sharks as they use the cover of mangroves to practice hunting before entering the food web of the ocean. +Mangrove plantations in Vietnam, Thailand, Philippines, and India host several commercially important species of fish and crustaceans. +Mangrove forests can decay into peat deposits because of fungal and bacterial processes as well as by the action of termites. It becomes peat in good geochemical, sedimentary, and tectonic conditions. The nature of these deposits depends on the environment and the types of mangroves involved. In Puerto Rico, the red, white, and black mangroves occupy different ecological niches and have slightly different chemical compositions, so the carbon content varies between the species, as well between the different tissues of the plant (e.g., leaf matter versus roots). +In Puerto Rico, there is a clear succession of these three trees from the lower elevations, which are dominated by red mangroves, to farther inland with a higher concentration of white mangroves. Mangrove forests are an important part of the cycling and storage of carbon in tropical coastal ecosystems. Knowing this, scientists seek to reconstruct the environment and investigate changes to the coastal ecosystem over thousands of years using sediment cores. However, an additional complication is the imported marine organic matter that also gets deposited in the sediment due to the tidal flushing of mangrove forests. Termites play an important role in the formation of peat from mangrove materials. They process fallen leaf litter, root systems and wood from mangroves into peat to build their nests, and stabilise the chemistry of this peat that represents approximately 2% of above ground carbon storage in mangroves. As the nests are buried over time this carbon is stored in the sediment and the carbon cycle continues. +Mangroves are an important source of blue carbon. Globally, mangroves stored 4.19 Gt (9.2×1012 lb) of carbon in 2012. Two percent of global mangrove carbon was lost between 2000 and 2012, equivalent to a maximum potential of 0.316996250 Gt (6.9885710×1011 lb) of emissions of carbon dioxide in Earth's atmosphere. +Globally, mangroves have been shown to provide measurable economic protections to coastal communities affected by tropical storms. + +== Mangrove microbiome == + +Plant microbiomes play crucial roles in the health and productivity of mangroves. Many researchers have successfully applied knowledge acquired about plant microbiomes to produce specific inocula for crop protection. Such inocula can stimulate plant growth by releasing phytohormones and enhancing uptake of some mineral nutrients (particularly phosphorus and nitrogen). However, most of the plant microbiome studies have focused on the model plant Arabidopsis thaliana and economically important crop plants, such as rice, barley, wheat, maize and soybean. There is less information on the microbiomes of tree species. Plant microbiomes are determined by plant-related factors (e.g., genotype, organ, species, and health status) and environmental factors (e.g., land use, climate, and nutrient availability). Two of the plant-related factors, plant species and genotypes, have been shown to play significant roles in shaping rhizosphere and plant microbiomes, as tree genotypes and species are associated with specific microbial communities. Different plant organs also have specific microbial communities depending on plant-associated factors (plant genotype, available nutrients, and organ-specific physicochemical conditions) and environmental conditions (associated with aboveground and underground surfaces and disturbances). + +=== Root microbiome === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Mangrove-4.md b/data/en.wikipedia.org/wiki/Mangrove-4.md new file mode 100644 index 000000000..4a11e2f39 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Mangrove-4.md @@ -0,0 +1,23 @@ +--- +title: "Mangrove" +chunk: 5/7 +source: "https://en.wikipedia.org/wiki/Mangrove" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:22.795957+00:00" +instance: "kb-cron" +--- + +Mangrove roots harbour a repertoire of microbial taxa that contribute to important ecological functions in mangrove ecosystems. Like typical terrestrial plants, mangroves depend upon mutually beneficial interactions with microbial communities. In particular, microbes residing in developed roots could help mangroves transform nutrients into usable forms before plant assimilation. These microbes also provide mangroves phytohormones for suppressing phytopathogens or helping mangroves withstand heat and salinity. In turn, root-associated microbes receive carbon metabolites from the plant via root exudates, thus close associations between the plant and microbes are established for their mutual benefits. +The taxonomic class level shows that most Proteobacteria were reported to come from Gammaproteobacteria, followed by Deltaproteobacteria and Alphaproteobacteria. The diverse function and the phylogenic variation of Gammaproteobacteria, which consisted of orders such as Alteromonadales and Vibrionales, are found in marine and coastal regions and are high in abundance in mangrove sediments functioning as nutrient recyclers. Members of Deltaproteobacteria found in mangrove soil are mostly sulfur-related, consisting of Desulfobacterales, Desulfuromonadales, Desulfovibrionales, and Desulfarculales among others. +Highly diverse microbial communities (mainly bacteria and fungi) have been found to inhabit and function in mangrove roots. For example, diazotrophic bacteria in the vicinity of mangrove roots could perform biological nitrogen fixation, which provides 40–60% of the total nitrogen required by mangroves; the soil attached to mangrove roots lacks oxygen but is rich in organic matter, providing an optimal microenvironment for sulfate-reducing bacteria and methanogens, ligninolytic, cellulolytic, and amylolytic fungi are prevalent in the mangrove root environment; rhizosphere fungi could help mangroves survive in waterlogged and nutrient-restricted environments. These studies have provided increasing evidence to support the importance of root-associated bacteria and fungi for mangrove growth and health. +Recent studies have investigated the detailed structure of root-associated microbial communities at a continuous fine-scale in other plants, where a microhabitat was divided into four root compartments: endosphere, episphere, rhizosphere, and nonrhizosphere or bulk soil. Moreover, the microbial communities in each compartment have been reported to have unique characteristics. Root exudates selectively enrich adapted microbial populations; however, these exudates were found to exert only marginal impacts on microbes in the bulk soil outside the rhizosphere. Furthermore, it was noted that the root episphere, rather than the rhizosphere, was primarily responsible for controlling the entry of specific microbial populations into the root, resulting in the selective enrichment of Proteobacteria in the endosphere. These findings provide new insights into the niche differentiation of root-associated microbial communities. Nevertheless, amplicon-based community profiling may not provide the functional characteristics of root-associated microbial communities in plant growth and biogeochemical cycling. Unraveling functional patterns across the four root compartments holds a great potential for understanding functional mechanisms responsible for mediating root–microbe interactions in support of enhancing mangrove ecosystem functioning. +The diversity of bacteria in disturbed mangroves is reported to be higher than in +well-preserved mangroves Studies comparing mangroves in different conservation states show that bacterial composition in disturbed mangrove sediment alters its structure, leading to a functional equilibrium, where the dynamics of chemicals in mangrove soils lead to the remodeling of its microbial structure. + +=== Suggestions for future mangrove microbial diversity research === +Despite many research advancements in mangrove sediment bacterial metagenomics +diversity in various conditions over the past few years, bridging the research gap and +expanding our knowledge towards the relationship between microbes mainly constituted of bacteria and its nutrient cycles in the mangrove sediment and direct and indirect impacts on mangrove growth and stand-structures as coastal barriers and other ecological service providers. Thus, based on studies by Lai et al.'s systematic review, here they suggest sampling improvements and a fundamental environmental index for future reference. + +=== Mangrove virome === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Mangrove-5.md b/data/en.wikipedia.org/wiki/Mangrove-5.md new file mode 100644 index 000000000..b08f71955 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Mangrove-5.md @@ -0,0 +1,41 @@ +--- +title: "Mangrove" +chunk: 6/7 +source: "https://en.wikipedia.org/wiki/Mangrove" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:22.795957+00:00" +instance: "kb-cron" +--- + +Mangrove forests are one of the most carbon-rich biomes, accounting for 11% of the total input of terrestrial carbon into oceans. Viruses are thought to significantly influence local and global biogeochemical cycles, though as of 2019, little information was available about the community structure, genetic diversity, and ecological roles of viruses in mangrove ecosystems. +Viruses are the most abundant biological entities on earth, present in virtually all ecosystems. By lysing their hosts, that is, by rupturing their cell membranes, viruses control host abundance and affect the structure of host communities. Viruses also influence their host diversity and evolution through horizontal gene transfer, selection for resistance and manipulation of bacterial metabolisms. Importantly, marine viruses affect local and global biogeochemical cycles through the release of substantial amounts of organic carbon and nutrients from hosts and assist microbes in driving biogeochemical cycles with auxiliary metabolic genes (AMGs). +It is presumed that AMGs augment viral-infected host metabolism and facilitate the production of new viruses. AMGs have been extensively explored in marine cyanophages and include genes involved in photosynthesis, carbon turnover, phosphate uptake and stress response. Cultivation-independent metagenomic analysis of viral communities has identified additional AMGs that are involved in motility, central carbon metabolism, photosystem I, energy metabolism, iron–sulphur clusters, anti-oxidation and sulphur and nitrogen cycling. Interestingly, a recent analysis of Pacific Ocean Virome data identified niche-specialised AMGs that contribute to depth-stratified host adaptations. Given that microbes drive global biogeochemical cycles, and viruses infect a large fraction of microbes at any given time, viral-encoded AMGs must play important roles in global biogeochemistry and microbial metabolic evolution. +Mangrove forests are the only woody halophytes that live in salt water along the world's subtropical and tropical coastlines. Mangroves are one of the most productive and ecologically important ecosystems on earth. The rates of primary production of mangroves equal those of tropical humid evergreen forests and coral reefs. As a globally relevant component of the carbon cycle, mangroves sequester approximately 24 million metric tons of carbon each year. Most mangrove carbon is stored in soil and sizable belowground pools of dead roots, aiding in the conservation and recycling of nutrients beneath forests. Although mangroves cover only 0.5% of the earth's coastal area, they account for 10–15% of the coastal sediment carbon storage and 10–11% of the total input of terrestrial carbon into oceans. The disproportionate contribution of mangroves to carbon sequestration is now perceived as an important means to counterbalance greenhouse gas emissions. + +Despite the ecological importance of the mangrove ecosystem, knowledge of mangrove biodiversity is notably limited. Previous reports mainly investigated the biodiversity of mangrove fauna, flora, and bacterial communities. Particularly, little information is available about viral communities and their roles in mangrove soil ecosystems. In view of the importance of viruses in structuring and regulating host communities and mediating element biogeochemical cycles, exploring viral communities in mangrove ecosystems is essential. Additionally, the intermittent flooding of sea water and resulting sharp transition of mangrove environments may result in substantially different genetic and functional diversity of bacterial and viral communities in mangrove soils compared with those of other systems. + +=== Genome sequencing === +Rhizophoreae as revealed by whole-genome sequencing + +== See also == + +Coastal management +Mangrove swamp +Mangrove restoration +Salt marsh +Flooding +Longshore drift +Coastal erosion +Coastal geography +Ecological values of mangrove +Blue carbon +Nursery habitat +Foundation species +Keystone species +Adelaida K. Semesi + +== Sources == + This article incorporates text from a free content work. Licensed under CC BY 4.0 (license statement/permission). Text taken from Global Forest Resources Assessment 2025​, Food and Agriculture Organization of the United Nations (FAO). + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Mangrove-6.md b/data/en.wikipedia.org/wiki/Mangrove-6.md new file mode 100644 index 000000000..1aed76c3a --- /dev/null +++ b/data/en.wikipedia.org/wiki/Mangrove-6.md @@ -0,0 +1,46 @@ +--- +title: "Mangrove" +chunk: 7/7 +source: "https://en.wikipedia.org/wiki/Mangrove" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:22.795957+00:00" +instance: "kb-cron" +--- + +== Further reading == +Saenger, Peter (2002). Mangrove Ecology, Silviculture, and Conservation. Kluwer Academic Publishers, Dordrecht. ISBN 1-4020-0686-1. +Thanikaimoni, Ganapathi (1986). Mangrove Palynology UNDP/UNESCO and the French Institute of Pondicherry, ISSN 0073-8336 (E). +Tomlinson, Philip B. (1986). The Botany of Mangroves. Cambridge University Press, Cambridge, ISBN 0-521-25567-8. +Teas, H. J. (1983). Biology and Ecology of Mangroves. W. Junk Publishers, The Hague. ISBN 90-6193-948-8. +Plaziat, Jean-Claude; Cavagnetto, Carla; Koeniguer, Jean-Claude; Baltzer, Frédéric (2001). "History and biogeography of the mangrove ecosystem, based on a critical reassessment of the paleontological record". Wetlands Ecology and Management. 9 (3): 161–180. Bibcode:2001WetEM...9..161P. doi:10.1023/A:1011118204434. S2CID 24980831. +Jayatissa, L. P.; Dahdouh-Guebas, F.; Koedam, N. (2002). "A review of the floral composition and distribution of mangroves in Sri Lanka" (PDF). Botanical Journal of the Linnean Society. 138: 29–43. doi:10.1046/j.1095-8339.2002.00002.x. +Ellison, Aaron M. (2000). "Mangrove Restoration: Do We Know Enough?". Restoration Ecology. 8 (3): 219–229. Bibcode:2000ResEc...8..219E. doi:10.1046/j.1526-100x.2000.80033.x. S2CID 86352384. +Agrawala, Shardul; Hagestad; Marca; Koshy, Kayathu; Ota, Tomoko; Prasad, Biman; Risbey, James; Smith, Joel; Van Aalst, Maarten. 2003. Development and Climate Change in Fiji: Focus on Coastal Mangroves. Organisation of Economic Co-operation and Development, Paris, Cedex 16, France. +Barbier, E. B.; Sathirathai, S. (2001). "Valuing Mangrove Conservation in Southern Thailand". Contemporary Economic Policy. 19 (2): 109–122. doi:10.1111/j.1465-7287.2001.tb00054.x. +Bosire, J. O.; Dahdouh-Guebas, F.; Jayatissa, L. P.; Koedam, N.; Lo Seen, D.; Nitto, Di D. (2005). "How Effective were Mangroves as a Defense Against the Recent Tsunami?". Current Biology. 15 (12): R443–R447. doi:10.1016/j.cub.2005.06.008. hdl:2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/46641. PMID 15964259. S2CID 8772526. +Bowen, Jennifer L.; Valiela, Ivan; York, Joanna K. (2001). "Mangrove Forests: One of the World's Threatened Major Tropical Environments". BioScience. 51 (10): 807–815. doi:10.1641/0006-3568(2001)051[0807:mfootw]2.0.co;2. +Jin-Eong, Ong (2004). "The Ecology of Mangrove Conservation and Management". Hydrobiologia. 295 (1–3): 343–351. doi:10.1007/BF00029141. S2CID 26686381. +Glenn, C. R. 2006. "Earth's Endangered Creatures" +Lewis, Roy R. III (2004). "Ecological Engineering for Successful Management and Restoration of Mangrove Forest". Ecological Engineering. 24 (4): 403–418. doi:10.1016/j.ecoleng.2004.10.003. +Kuenzer, C.; Bluemel, A.; Gebhardt, S.; Vo Quoc, T. & Dech, S. (2011). "Remote Sensing of Mangrove Ecosystems: A Review". Remote Sensing. 3 (5): 878–928. Bibcode:2011RemS....3..878K. doi:10.3390/rs3050878. +Lucien-Brun, H (1997). "Evolution of world shrimp production: Fisheries and aquaculture". World Aquaculture. 28: 21–33. +Twilley, R. R., V. H. Rivera-Monroy, E. Medina, A. Nyman, J. Foret, T. Mallach, and L. Botero. 2000. Patterns of forest development in mangroves along the San Juan River estuary, Venezuela. Forest Ecology and Management +Murray, M. R.; Zisman, S. A.; Furley, P. A.; Munro, D. M.; Gibson, J.; Ratter, J.; Bridgewater, S.; Mity, C. D.; Place, C. J. (2003). "The Mangroves of Belize: Part 1. Distribution, Composition and Classification". Forest Ecology and Management. 174 (1–3): 265–279. Bibcode:2003ForEM.174..265M. doi:10.1016/s0378-1127(02)00036-1. +Vo Quoc, T.; Kuenzer, C.; Vo Quang, M.; Moder, F. & Oppelt, N. (December 2012). "Review of Valuation Methods for Mangrove Ecosystem Services". Ecological Indicators. 23: 431–446. Bibcode:2012EcInd..23..431V. doi:10.1016/j.ecolind.2012.04.022. +Spalding, Mark; Kainuma, Mami and Collins, Lorna (2010) World Atlas of Mangroves Earthscan, London, ISBN 978-1-84407-657-4; 60 maps showing worldwide mangrove distribution +Warne, Kennedy (2013) Let them eat shrimp: the tragic disappearance of the rainforests of the sea. Island Press, 2012, ISBN 978-1597263344 +Mohammed-Geba, Khaled, Elamin, Ahmed Mohammed, Hassan, Arwa, Mohammed, Essmat, Salah-Eldin, Alaa El-Din, Schott, Eric J., & Galal-Khallaf, Asmaa (2025) Environmental DNA-based metabarcoding reveals a high animal biodiversity level within Red Sea mangrove beds. Frontiers in Marine Science Sec. Marine Molecular Biology and Ecology, Environmental DNA-based metabarcoding reveals a high animal biodiversity level within Red Sea mangrove beds. +Massó; Alemán, S.; Bourgeois, C.; Appeltans, W.; Vanhoorne, B.; De Hauwere, N.; Stoffelen, P.; Heaghebaert, A.; Dahdouh-Guebas, F. (2010). "The 'Mangrove Reference Database and Herbarium'" (PDF). Plant Ecology and Evolution. 143 (2): 225–232. Bibcode:2010PlEcE.143..225M. doi:10.5091/plecevo.2010.439. +Vo Quoc, T.; Oppelt, N.; Leinenkugel, P. & Kuenzer, C. (2013). "Remote Sensing in Mapping Mangrove Ecosystems – An Object-Based Approach". Remote Sensing. 5 (1): 183–201. Bibcode:2013RemS....5..183V. doi:10.3390/rs5010183. + +== External links == + +"Mangrove Factsheet". Waitt Institute. Archived from the original on 4 September 2015. Retrieved 8 June 2015. +"Mangroves". Smithsonian Ocean Portal. 30 April 2018. +Top 10 Mangrove Forest In The World – Travel Mate +"Mangroves Fact Sheet" (PDF). Fisheries Western Australia. 2013. Archived from the original (PDF) on 23 April 2013.* In May 2011, the VOA Special English service of the Voice of America broadcast a 15-minute program on mangrove forests. A transcript and MP3 of the program, intended for English learners, can be found at Mangrove Forests Could Be a Big Player in Carbon Trading +"Water Center for the Humid Tropics of Latin America and the Caribbean". Archived from the original on 5 February 2012. Retrieved 25 January 2014. +"Ocean Data Viewer – UNEP-WCMC". UNEP-WCMC's official website – Ocean Data Viewer. Retrieved 27 November 2020. +Queensland's coastal kidneys: mangroves. Stacey Larner, John Oxley Library Blog. State Library of Queensland. +"Take Shelter - Mangroves work together to protect the Earth and its waters. What can they teach us about community and sacrifice?". Atmos. 16 February 2024. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_botany-0.md b/data/en.wikipedia.org/wiki/Marine_botany-0.md new file mode 100644 index 000000000..caef9c374 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_botany-0.md @@ -0,0 +1,38 @@ +--- +title: "Marine botany" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Marine_botany" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:25.495279+00:00" +instance: "kb-cron" +--- + +Marine botany is the study of plant life in a marine environment. It includes the study of marine algae, seagrasses, and other aquatic plants of the ocean, and their distributions and natural environment. +It is a branch of marine biology and botany. + + +== Marine ecology == +Marine ecology and marine botany's area of study includes: + +Benthic zone +Coral reefs +Kelp forests +Mangroves +Phytoplankton +Salt marshes +Sea grass +Seaweed + + +== See also == + +Aquatic plants +Aquatic ecology +"Aquatic Botany" +Phycology +Index: Marine botany +Marine primary production + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_chemistry-0.md b/data/en.wikipedia.org/wiki/Marine_chemistry-0.md new file mode 100644 index 000000000..b85eceb2f --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_chemistry-0.md @@ -0,0 +1,29 @@ +--- +title: "Marine chemistry" +chunk: 1/2 +source: "https://en.wikipedia.org/wiki/Marine_chemistry" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:26.772908+00:00" +instance: "kb-cron" +--- + +Marine chemistry, also known as ocean chemistry or chemical oceanography, is the study of the chemical composition and processes of the world’s oceans, including the interactions between seawater, the atmosphere, the seafloor, and marine organisms. This field encompasses a wide range of topics, such as the cycling of elements like carbon, nitrogen, and phosphorus, the behavior of trace metals, and the study of gases and nutrients in marine environments. Marine chemistry plays a crucial role in understanding global biogeochemical cycles, ocean circulation, and the effects of human activities, such as pollution and climate change, on oceanic systems. It is influenced by plate tectonics and seafloor spreading, turbidity, currents, sediments, pH levels, atmospheric constituents, metamorphic activity, and ecology. +The impact of human activity on the chemistry of the Earth's oceans has increased over time, with pollution from industry and various land-use practices significantly affecting the oceans. Moreover, increasing levels of carbon dioxide in the Earth's atmosphere have led to ocean acidification, which has negative effects on marine ecosystems. The international community has agreed that restoring the chemistry of the oceans is a priority, and efforts toward this goal are tracked as part of Sustainable Development Goal 14. +Due to the interrelatedness of the ocean, chemical oceanographers frequently work on problems relevant to physical oceanography, geology and geochemistry, biology and biochemistry, and atmospheric science. Many of them are investigating biogeochemical cycles, and the marine carbon cycle in particular attracts significant interest due to its role in carbon sequestration and ocean acidification. Other major topics of interest include analytical chemistry of the oceans, marine pollution, and anthropogenic climate change. + +== Organic compounds in the oceans == + +=== Dissolved Organic Matter (DOM) === + +DOM is a critical component of the ocean's carbon pool and includes many molecules such as amino acids, sugars, and lipids. It represents about 90% of the total organic carbon in marine environments. Colored dissolved organic matter (CDOM) is estimated to range from 20-70% of the carbon content of the oceans, being higher near river outlets and lower in the open ocean. DOM can be recycled and put back into the food web through a process called microbial loop which is essential for nutrient cycling and supporting primary productivity. It also plays a vital role in the global regulation of oceanic carbon storage, as some forms resist microbial degradation and may exist within the ocean for centuries. Marine life is similar mainly in biochemistry to terrestrial organisms, and is the most prolific source of halogenated organic compounds. + +=== Particulate Organic Matter (POM) === +POM includes of large organic particles, such as organisms, fecal pellets, and detritus, which settle through the water column. It is a major component of the biological pump, a process by which carbon is transferred from the surface ocean to the deep sea. As POM sinks, it decomposes by bacterial activity, releasing nutrients and carbon dioxide. The refractory POM fraction can settle on the ocean floor and make relevant contributions to carbon sequestration over a very long period of time + +== Chemical ecology of extremophiles == +The ocean is home to a variety of marine organisms known as extremophiles – organisms that thrive in extreme conditions of temperature, pressure, and light availability. Extremophiles inhabit many unique habitats in the ocean, such as hydrothermal vents, black smokers, cold seeps, hypersaline regions, and sea ice brine pockets. Some scientists have speculated that life may have evolved from hydrothermal vents in the ocean.In hydrothermal vents and similar environments, many extremophiles acquire energy through chemoautotrophy, using chemical compounds as energy sources, rather than light as in photoautotrophy. Hydrothermal vents enrich the nearby environment in chemicals such as elemental sulfur, H2, H2S, Fe2+, and methane. Chemoautotrophic organisms, primarily prokaryotes, derive energy from these chemicals through redox reactions. These organisms then serve as food sources for higher trophic levels, forming the basis of unique ecosystems. +Several different metabolisms are present in hydrothermal vent ecosystems. Many marine microorganisms, including Thiomicrospira, Halothiobacillus, and Beggiatoa, are capable of oxidizing sulfur compounds, including elemental sulfur and the often toxic compound H2S. H2S is abundant in hydrothermal vents, formed through interactions between seawater and rock at the high temperatures found within vents. This compound is a major energy source, forming the basis of the sulfur cycle in hydrothermal vent ecosystems. In the colder waters surrounding vents, sulfur-oxidation can occur using oxygen as an electron acceptor; closer to the vents, organisms must use alternate metabolic pathways or utilize another electron acceptor, such as nitrate. Some species of Thiomicrospira can utilize thiosulfate as an electron donor, producing elemental sulfur. Additionally, many marine microorganisms are capable of iron-oxidation, such as Mariprofundus ferrooxydans. Iron-oxidation can be oxic, occurring in oxygen-rich parts of the ocean, or anoxic, requiring either an electron acceptor such as nitrate or light energy. In iron-oxidation, Fe(II) is used as an electron donor; conversely, iron-reducers utilize Fe(III) as an electron acceptor. These two metabolisms form the basis of the iron-redox cycle and may have contributed to banded iron formations. +At another extreme, some marine extremophiles inhabit sea ice brine pockets where temperature is very low and salinity is very high. Organisms trapped within freezing sea ice must adapt to a rapid change in salinity up to 3 times higher than that of regular seawater, as well as the rapid change to regular seawater salinity when ice melts. Most brine-pocket dwelling organisms are photosynthetic, therefore, these microenvironments can become hyperoxic, which can be toxic to its inhabitants. Thus, these extremophiles often produce high levels of antioxidants. + +== Plate tectonics == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_chemistry-1.md b/data/en.wikipedia.org/wiki/Marine_chemistry-1.md new file mode 100644 index 000000000..8e9b4bb72 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_chemistry-1.md @@ -0,0 +1,52 @@ +--- +title: "Marine chemistry" +chunk: 2/2 +source: "https://en.wikipedia.org/wiki/Marine_chemistry" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:26.772908+00:00" +instance: "kb-cron" +--- + +Seafloor spreading on mid-ocean ridges is a global scale ion-exchange system. Hydrothermal vents at spreading centers introduce various amounts of iron, sulfur, manganese, silicon and other elements into the ocean, some of which are recycled into the ocean crust. Helium-3, an isotope that accompanies volcanism from the mantle, is emitted by hydrothermal vents and can be detected in plumes within the ocean. +Spreading rates on mid-ocean ridges vary between 10 and 200 mm/yr. Rapid spreading rates cause increased basalt reactions with seawater. The magnesium/calcium ratio will be lower because more magnesium ions are being removed from seawater and consumed by the rock, and more calcium ions are being removed from the rock and released to seawater. Hydrothermal activity at ridge crest is efficient in removing magnesium. A lower Mg/Ca ratio favors the precipitation of low-Mg calcite polymorphs of calcium carbonate (calcite seas). +Slow spreading at mid-ocean ridges has the opposite effect and will result in a higher Mg/Ca ratio favoring the precipitation of aragonite and high-Mg calcite polymorphs of calcium carbonate (aragonite seas). +Experiments show that most modern high-Mg calcite organisms would have been low-Mg calcite in past calcite seas, meaning that the Mg/Ca ratio in an organism's skeleton varies with the Mg/Ca ratio of the seawater in which it was grown. +The mineralogy of reef-building and sediment-producing organisms is thus regulated by chemical reactions occurring along the mid-ocean ridge, the rate of which is controlled by the rate of sea-floor spreading. + +== Human impacts == + +=== Marine pollution === + +=== Climate change === + +Increased carbon dioxide levels, mostly from burning fossil fuels, are changing ocean chemistry. Global warming and changes in salinity have significant implications for the ecology of marine environments. + +==== Acidification ==== + +==== Deoxygenation ==== + +== History == + +Early inquiries about marine chemistry usually concerned the origin of salinity in the ocean, including work by Robert Boyle. Modern chemical oceanography began as a field with the 1872–1876 Challenger expedition, led by the British Royal Navy which made the first systematic measurements of ocean chemistry. The chemical analysis of these samples providing the first systematic study of the composition of seawater was conducted by John Murray and George Forchhammer, leading to a better understanding of elements like chloride, sodium, and sulfate in ocean waters +The early 20th century saw significant advancements in marine chemistry, particularly with more accurate analytical techniques. Scientists like Martin Knudsen created the Knudsen Bottle, an instrument used to collect water samples from different ocean depths. Over the past three decades (1970s, 19802, and 1990s), a comprehensive evaluation of advancements in chemical oceanography was compiled through a National Science Foundation initiative known as Futures of Ocean Chemistry in the United States (FOCUS). This project brought together numerous prominent chemical oceanographers, marine chemists, and geochemists to contribute to the FOCUS report. +After World War II, advancements in geochemical techniques propelled marine chemistry into a new era. Researchers began using isotopic analysis to study ocean circulation and the carbon cycle. Roger Revelle and Hans Suess pioneered using radiocarbon dating to investigate oceanic carbon reservoirs and their exchange with the atmosphere. +Since the 1970s, the development of highly sophisticated instruments and computational models has revolutionized marine chemistry. Scientists can now measure trace metals, organic compounds, and isotopic ratios with unprecedented precision. Studies of marine biogeochemical cycles, including the carbon, nitrogen, and sulfur cycles, have become an area of interest to understand global climate change. The use of remote sensing technology and global ocean observation programs, such as the International Geosphere-Biosphere Programme (IGBP), has provided large-scale data on ocean chemistry, allowing scientists to monitor ocean acidification, deoxygenation, and other critical issues affecting the marine environment. + +== Tools used for analysis == +Chemical oceanographers collect and measure chemicals in seawater, using the standard toolset of analytical chemistry as well as instruments like pH meters, electrical conductivity meters, fluorometers, and dissolved CO2 meters. Most data are collected through shipboard measurements and from autonomous floats or buoys, but remote sensing is used as well. On an oceanographic research vessel, a CTD is used to measure electrical conductivity, temperature, and pressure, and is often mounted on a rosette of Nansen bottles to collect seawater for analysis. Sediments are commonly studied with a box corer or a sediment trap, and older sediments may be recovered by scientific drilling. + +Advanced analytical equipment such as mass spectrometers and chromatographs are applied to detect trace elements, isotopes, and organic compounds. This allows for precisely measuring nutrients, gases, and pollutants in marine environments. In recent years, autonomous underwater vehicles (AUVs) and remote sensing technology have enabled continuous, large-scale ocean chemistry monitoring, particularly for tracking changes in ocean acidification and nutrient cycles. + +== Marine chemistry on other planets and their moons == +The chemistry of the subsurface ocean of Europa may be Earthlike. The subsurface ocean of Enceladus vents hydrogen and carbon dioxide to space. + +== See also == +Global Ocean Data Analysis Project +Oceanography +Physical oceanography +World Ocean Atlas +Seawater +RISE project + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_debris-0.md b/data/en.wikipedia.org/wiki/Marine_debris-0.md new file mode 100644 index 000000000..c13e0dcce --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_debris-0.md @@ -0,0 +1,29 @@ +--- +title: "Marine debris" +chunk: 1/5 +source: "https://en.wikipedia.org/wiki/Marine_debris" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:28.009276+00:00" +instance: "kb-cron" +--- + +Marine debris, also known as marine litter, is human-created solid material that has deliberately or accidentally been released in seas or the ocean. Floating oceanic debris tends to accumulate at the center of gyres and on coastlines, frequently washing aground, when it is known as beach litter or tidewrack. Deliberate disposal of wastes at sea is called ocean dumping. Naturally occurring debris, such as driftwood and drift seeds, are also present. With the increasing use of plastic, human influence has become an issue as many types of (petrochemical) plastics do not biodegrade quickly, as would natural or organic materials. The largest single type of plastic pollution (~10%) and majority of large plastic in the oceans is discarded and lost nets from the fishing industry. Waterborne plastic poses a serious threat to fish, seabirds, marine reptiles, and marine mammals, as well as to boats and coasts. +Dumping, container spillages, litter washed into storm drains and waterways and wind-blown landfill waste all contribute to this problem. This increased water pollution has caused serious negative effects such as discarded fishing nets capturing animals, concentration of plastic debris in massive marine garbage patches, and increasing concentrations of contaminants in the food chain. +In efforts to prevent and mediate marine debris and pollutants, laws and policies have been adopted internationally, with the UN including reduced marine pollution in Sustainable Development Goal 14 "Life Below Water". Depending on relevance to the issues and various levels of contribution, some countries have introduced more specified protection policies. Moreover, some non-profits, NGOs, and government organizations are developing programs to collect and remove plastics from the ocean. However, in 2017 the UN estimated that by 2050 there will be more plastic than fish in the oceans if substantial measures are not taken. + +== Types == + +Researchers classify debris as either land- or ocean-based; in 1991, the United Nations Joint Group of Experts on the Scientific Aspects of Marine Pollution estimated that up to 80% of the pollution was land-based, with the remaining 20% originating from catastrophic events or maritime sources. More recent studies have found that more than half of plastic debris found on Korean shores is ocean-based. +A wide variety of man-made objects can become marine debris; plastic bags, balloons, buoys, rope, medical waste, glass and plastic bottles, cigarette stubs, cigarette lighters, beverage cans, polystyrene, lost fishing line and nets, and various wastes from cruise ships and oil rigs are among the items commonly found to have washed ashore. Six-pack rings, in particular, are considered emblematic of the problem. +The U.S. military used ocean dumping for unused weapons and bombs, including ordinary bombs, Unexploded ordnance (UXO), landmines and chemical weapons from at least 1919 until 1970. Millions of pounds of ordnance were disposed of in the Gulf of Mexico and off the coasts of at least 16 states, from New Jersey to Hawaii (although these, of course, do not wash up onshore, and the U.S. is not the only country who has practiced this). +Eighty percent of marine debris is plastic. Plastics accumulate because they typically do not biodegrade as many other substances do. They photodegrade on exposure to sunlight, although they do so only under dry conditions, as water inhibits photolysis. In a 2014 study using computer models, scientists from the group 5 Gyres, estimated 5.25 trillion pieces of plastic weighing 269,000 tons were dispersed in oceans in similar amount in the Northern and Southern Hemispheres. + +=== Persistent industrial marine debris === +Some materials and activities used in industrial activities that do not readily degrade, that persist in the environment, and tend to accumulate over time. The activities can include fishing, boating, and aquaculture industries that harvest or use resources in the marine environment and may lose or discard gear, materials, machinery or solid wastes from industrial processes into the water or onto shorelines. This can include anything as large as a fishing boat or as small as particle from a Styrofoam lobster float. In 2003, a study was conducted to identify types, amounts, sources, and effects of persistent industrial marine debris in the coastal waters and along the shores of Charlotte County, New Brunswick, and examine any relationship between the amount and types of persistent industrial marine debris, and the types and numbers of industrial operations nearby. Materials like plastic or foam can break down into smaller particles and may look like small sea creatures to wildlife such as birds, cetaceans, and fish, and they may eat these particles. Indigestible material may accumulate in the gut creating blockages or a false sense of fullness and eventually death from lack of appropriate nutrient intake. + +=== Ghost nets === + +=== Macroplastic === + +=== Microplastics === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_debris-1.md b/data/en.wikipedia.org/wiki/Marine_debris-1.md new file mode 100644 index 000000000..3d26760de --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_debris-1.md @@ -0,0 +1,28 @@ +--- +title: "Marine debris" +chunk: 2/5 +source: "https://en.wikipedia.org/wiki/Marine_debris" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:28.009276+00:00" +instance: "kb-cron" +--- + +=== Deep-sea debris === +Marine debris is found on the floor of the Arctic ocean. Although an increasing number of studies have been focused on plastic debris accumulation on the coasts, in off-shore surface waters, and that ingested by marine organisms that live in the upper levels of the water column, there is limited information on debris in the mesopelagic and deeper layers. Studies that have been done have conducted research through bottom sampling, video observation via remotely operated vehicles (ROVs), and submersibles. They are also mostly limited to one-off projects that do not extend long enough to show significant effects of deep-sea debris over time. Research thus far has shown that debris in the deep-ocean is in fact impacted by anthropogenic activities, and plastic has been frequently observed in the deep-sea, especially in areas off-shore of heavily populated regions, such as the Mediterranean. +Litter, made from diverse materials that are lighter than surface water (such as glasses, metals and some plastics), have been found to spread over the floor of seas and open oceans, where it can become entangled in corals and interfere with other sea-floor life, or even become buried under sediment, making clean-up extremely difficult, especially due to the wide area of its dispersal compared to shipwrecks. Plastics that are usually negatively buoyant can sink with the adherence of phytoplankton and the aggregation of other organic particles. Other oceanic processes that affect circulation, such as coastal storms and offshore convection, play a part in transferring large volumes of particles and debris. Submarine topographic features can also augment downwelling currents, leading to the retention of microplastics at certain locations. +A Deep-sea Debris database by the Global Oceanographic Data Center of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), showing thirty years of photos and samples of marine debris since 1983, was made public in 2017. From the 5,010 dives in the database, using both ROVs and deep-sea submersibles, 3,425 man-made debris items were counted. The two most significant types of debris were macro-plastic, making up 33% of the debris found – 89% of which was single-use – and metal, making up 26%. Plastic debris was found at the bottom of the Mariana Trench, at a depth of 10,898m, and plastic bags were found entangled in hydrothermal vent and cold seep communities. + +=== Garbage patches (gyres) === + +== Sources == + +The 10 largest emitters of oceanic plastic pollution worldwide are, from the most to the least, China, Indonesia, Philippines, Vietnam, Sri Lanka, Thailand, Egypt, Malaysia, Nigeria, and Bangladesh, largely through the rivers Yangtze, Indus, Yellow, Hai, Nile, Ganges, Pearl, Amur, Niger, and the Mekong, and accounting for "90 percent of all the plastic that reaches the world's oceans." +An estimated 10,000 containers at sea each year are lost by container ships, usually during storms. One spillage occurred in the Pacific Ocean in 1992, when thousands of rubber ducks and other toys (now known as the "Friendly Floatees") went overboard during a storm. The toys have since been found all over the world, providing a better understanding of ocean currents. Similar incidents have happened before, such as when Hansa Carrier dropped 21 containers (with one notably containing buoyant Nike shoes). +In 2007, MSC Napoli beached in the English Channel, dropping hundreds of containers, most of which washed up on the Jurassic Coast, a World Heritage Site. A 2021 study following a 2014 loss of a container carrying printer cartridges calculated that some cartridges had dispersed at an average speed of between 6 cm and 13 cm per second. A 1997 accident of Tokio Express ship off the British coast resulted in loss of cargo container holding 5 million Lego pieces. Some of the pieces became valued among collectors who searched the beaches for Lego dragons. It also provided valuable insight in studying marine plastic degradation. +In Halifax Harbour, Nova Scotia, 52% of items were generated by recreational use of an urban park, 14% from sewage disposal and only 7% from shipping and fishing activities. Around four-fifths of oceanic debris is from rubbish blown onto the water from landfills, and urban runoff. +Some studies show that marine debris may be dominant in particular locations. For example, a 2016 study of Aruba found that debris found the windward side of the island was predominantly marine debris from distant sources. In 2013, debris from six beaches in Korea was collected and analyzed: 56% was found to be "ocean-based" and 44% "land-based". +In the 1987 Syringe Tide, medical waste washed ashore in New Jersey after having been blown from Fresh Kills Landfill. On the remote sub-Antarctic island of South Georgia, fishing-related debris, approximately 80% plastics, are responsible for the entanglement of large numbers of Antarctic fur seals. +Thirteen companies have an individual contribution of 1% or more of the total branded plastic observed in the audit events: The Coca-Cola Company, PepsiCo, Nestlé, Danone, Altria, Bakhresa Group, Wings, Unilever, Mayora Indah, Mondelez International, Mars, Incorporated, Salim Group, and British American Tobacco. All 13 companies produce food, beverage, or tobacco products. The top company, The Coca-Cola Company, was responsible for 11% (CI95% = 10 to 12%), significantly greater than any other company. The top 5 companies were responsible for 24% of the branded plastic; 56 companies were responsible for greater than 50% of the branded plastic; and 19,586 companies were responsible for all of the branded plastic. The contributions of the top companies may be an underestimation because there were brands that were not attributed to a company, and there were many unbranded objects. + +== Environmental impacts == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_debris-2.md b/data/en.wikipedia.org/wiki/Marine_debris-2.md new file mode 100644 index 000000000..ecfd93595 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_debris-2.md @@ -0,0 +1,29 @@ +--- +title: "Marine debris" +chunk: 3/5 +source: "https://en.wikipedia.org/wiki/Marine_debris" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:28.009276+00:00" +instance: "kb-cron" +--- + +Not all anthropogenic artifacts placed in the oceans are harmful. Iron and concrete structures typically do little damage to the environment because they generally sink to the bottom and become immobile, and at shallow depths they can even provide scaffolding for artificial reefs. Ships and subway cars have been deliberately sunk for that purpose. +Additionally, hermit crabs have been known to use pieces of beach litter as a shell when they cannot find an actual seashell of the size they need. + +=== Impacts from plastic pollution === + +Many animals that live on or in the sea consume flotsam by mistake, as it often looks similar to their natural prey. Overall, 1288 marine species are known to ingest plastic debris, with fish making up the largest fraction. Bulky plastic debris may become permanently lodged in the digestive tracts of these animals, blocking the passage of food and causing death through starvation or infection. Tiny floating plastic particles also resemble zooplankton, which can lead filter feeders to consume them and cause them to enter the ocean food chain. In addition, plastic in the marine environment that contaminates the food chain can have repercussions on the viability of fish and shellfish species. + +=== COVID-19 pandemic impacts === +In Kenya, the COVID-19 pandemic has impacted the amount of marine debris found on beaches with around 55% being a pandemic-related trash items. Although the pandemic-related trash has shown up along the beaches of Kenya, it has not made its way into the water. The reduction of litter in the ocean could be a result of the closing of beaches and lack of movement during the pandemic, so less trash was likely to end up in the ocean. Additional impacts of the COVID-19 pandemic have been seen in Hong Kong, where disposable masks have ended up along the beaches of Soko's islands. This may be attributed to the increased production of medical products (masks and gloves) during the pandemic, leading to a rise in unconventional disposal of these products. + +== Removal == + +=== Coastal and river clean ups === +Techniques for collecting and removing marine (or riverine) debris include the use of debris skimmer boats (pictured). Devices such as these can be used where floating debris presents a danger to navigation. For example, the US Army Corps of Engineers removes 90 tons of "drifting material" from San Francisco Bay every month. The Corps has been doing this work since 1942, when a seaplane carrying Admiral Chester W. Nimitz collided with a piece of floating debris and sank, costing the life of its pilot. The Ocean cleanup has also created a vessel for cleaning up riverine debris, called Interceptor. Once debris becomes "beach litter", collection by hand and specialized beach-cleaning machines are used to gather the debris. +There are also projects that stimulate fishing boats to remove any litter they accidentally fish up while fishing for fish. +Elsewhere, "trash traps" are installed on small rivers to capture waterborne debris before it reaches the sea. For example, South Australia's Adelaide operates a number of such traps, known as "trash racks" or "gross pollutant traps" on the Torrens River, which flows (during the wet season) into Gulf St Vincent. +In lakes or near the coast, manual removal can also be used. Project AWARE for example promotes the idea of letting dive clubs clean up litter, for example as a diving exercise. +Once a year there is a diving marine debris removal operation in Scapa Flow in Orkney, run by Ghost Fishing UK, funded by World Animal Protection and Fat Face Foundation. +Cleanup of marine debris can be stymied by inadequate collaboration across levels of government, and a patchwork of regulatory authorities (responsibility often differs for the ocean surface, the seabed, and the shore). For example, there are an estimated 1600 abandoned and derelict boats in the waters of British Columbia. In 2019 Canada's federal government passed legislation to make it illegal to abandon a vessel but enforcement is hampered because it is often difficult to determine who owns an abandoned boat since owners are not required to have a license – licensing is a provincial government responsibility. The Victoria-based non-profit Dead Boats Disposal Society notes that lack of enforcement means abandoned boats are often left to sink, which increases the cleanup cost and compounds the environmental hazard (due to seepage of fuel, oil, plastics, and other pollutants). \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_debris-3.md b/data/en.wikipedia.org/wiki/Marine_debris-3.md new file mode 100644 index 000000000..be11133c4 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_debris-3.md @@ -0,0 +1,35 @@ +--- +title: "Marine debris" +chunk: 4/5 +source: "https://en.wikipedia.org/wiki/Marine_debris" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:28.009276+00:00" +instance: "kb-cron" +--- + +=== Mid-ocean clean ups === +On the sea, the removal of artificial debris (i.e. plastics) is still in its infancy. However, some projects have been started which used ships with nets (Ocean Voyages Institute/Kaisei 2009 & 2010 and New Horizon 2009) to catch some plastics, primarily for research purposes. There is also Bluebird Marine System's SeaVax which was solar- and wind-powered and had an onboard shredder and cargo hold. The Sea Cleaners' Manta ship is similar in concept. +Another method to gather artificial litter has been proposed by The Ocean Cleanup's Boyan Slat. He suggested using platforms with arms to gather the debris, situated inside the current of gyres. The SAS Ocean Phoenix ship is somewhat similar in design. +In June 2019, Ocean Voyages Institute, conducted a cleanup utilizing GPS trackers and existing maritime equipment in the North Pacific Subtropical Convergence Zone setting the record for the largest mid-ocean cleanup accomplished in the North Pacific Gyre and removed over 84,000 pounds of polymer nets and consumer plastic trash from the ocean. +In May/June 2020, Ocean Voyages Institute conducted a cleanup expedition in the Gyre and set a new record for the largest mid-ocean cleanup accomplished in the North Pacific Gyre which removed over 170 tons (340,000 pounds) of consumer plastics and ghostnets from the ocean. Utilizing custom designed GPS satellite trackers which are deployed by vessels of opportunity, Ocean Voyages Institute is able to accurately track and send cleanup vessels to remove ghostnets. The GPS Tracker technology is being combined with satellite imagery increasing the ability to locate plastic trash and ghostnets in real time via satellite imagery which will greatly increase cleanup capacity and efficiency. +Another issue is that removing marine debris from the ocean can potentially cause more harm than good. Cleaning up microplastics could also accidentally take out plankton, which are the main lower level food group for the marine food chain and over half of the photosynthesis on earth. One of the most efficient and cost effective ways to help reduce the amount of plastic entering our oceans is to not participate in using single-use plastics, avoid plastic bottled drinks such as water bottles, use reusable shopping bags, and to buy products with reusable packaging. + +== Laws and treaties == +The ocean is a global common, so negative externalities of marine debris are not usually experienced by the producer. In the 1950s, the importance of government intervention with marine pollution protocol was recognized at the First Conference on the Law of the Sea. +Ocean dumping is controlled by international law, including: + +The London Convention (1972) – a United Nations agreement to control ocean dumping This Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter consisted of twenty two articles addressing expectations of contracting parties. The three annexes defined many compounds, substances, and materials that are unacceptable to deposit into the ocean. Examples of such matter include: mercury compounds, lead, cyanides, and radioactive wastes. +MARPOL 73/78 – a convention designed to minimize pollution of the seas, including dumping, oil and exhaust pollution The original MARPOL convention did not consider dumping from ships, but was revised in 1978 to include restrictions on marine vessels. +UNCLOS – signed in 1982, but effective in 1994, United Nations Convention on the Law of the Sea emphasized the importance of protecting the entire ocean and not only specified coastal regions. UNCLOS enforced restrictions on pollution, including a stress on land-based sources. + +=== Australian law === +One of the earliest anti-dumping laws was Australia's Beaches, Fishing Grounds and Sea Routes Protection Act 1932, which prohibited the discharge of "garbage, rubbish, ashes or organic refuse" from "any vessel in Australian waters" without prior written permission from the federal government. It also required permission for scuttling. The act was passed in response to large amounts of garbage washing up on the beaches of Sydney and Newcastle from vessels outside the reach of local governments and the New South Wales government. It was repealed and replaced by the Environment Protection (Sea Dumping) Act 1981, which gave effect to the London Convention. + +=== European law === +In 1972 and 1974, conventions were held in Oslo and Paris respectively, and resulted in the passing of the OSPAR Convention, an international treaty controlling marine pollution in the north-east Atlantic Ocean. The Barcelona Convention protects the Mediterranean Sea. The Water Framework Directive of 2000 is a European Union directive committing EU member states to free inland and coastal waters from human influence. In the United Kingdom, the Marine and Coastal Access Act 2009 is designed to "ensure clean healthy, safe, productive and biologically diverse oceans and seas, by putting in place better systems for delivering sustainable development of marine and coastal environment". +In 2019, the EU parliament voted for an EU-wide ban on single-use plastic products such as plastic straws, cutlery, plates, and drink containers, polystyrene food and drink containers, plastic drink stirrers and plastic carrier bags and cotton buds. The law will take effect in 2021. + +=== United States law === + +In the waters of the United States, there have been many observed consequences of pollution including: hypoxic zones, harmful agal blooms, and threatened species. In 1972, the United States Congress passed the Ocean Dumping Act, giving the Environmental Protection Agency power to monitor and regulate the dumping of sewage sludge, industrial waste, radioactive waste and biohazardous materials into the nation's territorial waters. The Act was amended sixteen years later to include medical wastes. It is illegal to dispose of any plastic in US waters. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_debris-4.md b/data/en.wikipedia.org/wiki/Marine_debris-4.md new file mode 100644 index 000000000..35facbddd --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_debris-4.md @@ -0,0 +1,51 @@ +--- +title: "Marine debris" +chunk: 5/5 +source: "https://en.wikipedia.org/wiki/Marine_debris" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:28.009276+00:00" +instance: "kb-cron" +--- + +=== Ownership === +Property law, admiralty law and the law of the sea may be of relevance when lost, mislaid, and abandoned property is found at sea. Salvage law rewards salvors for risking life and property to rescue the property of another from peril. On land the distinction between deliberate and accidental loss led to the concept of a "treasure trove". In the United Kingdom, shipwrecked goods should be reported to a Receiver of Wreck, and if identifiable, they should be returned to their rightful owner. + +== Activism == +A large number of groups and individuals are active in preventing or educating about marine debris. For example, 5 Gyres is an organization aimed at reducing plastics pollution in the oceans, and was one of two organizations that recently researched the Great Pacific Garbage Patch. Heal the Bay is another organization, focusing on protecting California's Santa Monica Bay, by sponsoring beach cleanup programs along with other activities. Marina DeBris is an artist focusing most of her recent work on educating people about beach trash. +Interactive sites like Adrift demonstrate where marine plastic is carried, over time, on the worlds ocean currents. +On 11 April 2013 in order to create awareness, artist Maria Cristina Finucci founded the Garbage Patch State at UNESCO –Paris in front of Director General Irina Bokova. First of a series of events under the patronage of UNESCO and of Italian Ministry of the Environment. +Forty-eight plastics manufacturers from 25 countries, are members of the Global Plastic Associations for solutions on Marine Litter, have made the pledge to help prevent marine debris and to encourage recycling. + +=== Mitigation === + +Marine debris is a widespread problem, not only the result of activities in coastal regions. +Plastic debris from inland states come from two main sources: ordinary litter and materials from open dumps and landfills that blow or wash away to inland waterways and wastewater outflows. The refuse finds its way from inland waterways, rivers, streams and lakes to the ocean. Though ocean and coastal area cleanups are important, it is crucial to address plastic waste that originates from inland and landlocked states. +At the systems level, there are various ways to reduce the amount of debris entering our waterways: + +Improve waste transportation to and from sites by utilizing closed container storage and shipping +Restrict open waste facilities near waterways +Promote the use of refuse-derived fuels. Used plastic with low residual value often does not get recycled and is more likely to leak into the ocean. However, turning these unwanted plastics that would otherwise stay in landfills into refuse-derived fuels allows for further use; they can be used as supplement fuels at power plants +Improve recovery rates for plastic (in 2012, the United States generated 11.46 million tons of plastic waste, of which only 6.7% was recovered +Adapt Extended Producer Responsibility strategies to make producers responsible for product management when products and their packaging become waste; encourage reusable product design to minimize negative impacts on the environment. +Ban the use of cigarette filters and establish a deposit-system for e-cigarettes (similar to the one used for propane canisters) +Consumers can help to reduce the amount of plastic entering waterways by reducing usage of single-use plastics, avoiding microbeads, participate in a river or lake beach cleanup. + +== See also == + +== References == + +== External links == + Media related to Marine debris at Wikimedia Commons + +United Nations Environment Programme Marine Litter Publications +UNEP Year Book 2011: Emerging Issues in Our Global Environment Archived 13 February 2012 at the Library of Congress Web Archives Plastic debris, pp. 21–34. ISBN 978-9280731019. +NOAA Marine Debris Program – US National Oceanic and Atmospheric Administration +Marine Research, Education and Restoration – Algalita Marine Research Foundation +UK Marine Conservation Society +Harmful Marine Debris – Australian Government +High Seas GhostNet Survey – US National Oceanic and Atmospheric Administration +Social & Economic Costs of Marine Debris – NOAA Economics +Tiny Plastic Bits Too Small To See Are Destroying The Oceans, Business Insider +Ghost net remediation program – NASA, NOAA and ATI collaborating to detect ghost nets Archived 7 March 2016 at the Wayback Machine +Dunning, Brian (16 December 2008). "Skeptoid #132: The Sargasso Sea and the Pacific Garbage Patch". Skeptoid. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_ecoregion-0.md b/data/en.wikipedia.org/wiki/Marine_ecoregion-0.md new file mode 100644 index 000000000..e603f85be --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_ecoregion-0.md @@ -0,0 +1,74 @@ +--- +title: "Marine ecoregion" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Marine_ecoregion" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:29.187903+00:00" +instance: "kb-cron" +--- + +A marine ecoregion is an ecoregion, or ecological region, of the oceans and seas identified and defined based on biogeographic characteristics. + + +== Introduction == +A more complete definition describes them as “Areas of relatively homogeneous species composition, clearly distinct from adjacent systems” dominated by “a small number of ecosystems and/or a distinct suite of oceanographic or topographic features”. Ecologically they “are strongly cohesive units, sufficiently large to encompass ecological or life history processes for most sedentary species.” + + +== Marine Ecoregions of the World—MEOW == +The global classification system Marine Ecoregions of the World—MEOW was devised by an international team, including major conservation organizations, academic institutions and intergovernmental organizations. The system covers coastal and continental shelf waters of the world, and does not include deep ocean waters. The MEOW system integrated the biogeographic regionalization systems in use at national or continental scale, like Australia's Integrated Marine and Coastal Regionalisation of Australia and the Nature Conservancy’s system in the Americas, although it often uses different names for the subdivisions. +This system has a strong biogeographic basis, but was designed to aid in conservation activities for marine ecosystems. Its subdivisions include both the seafloor (benthic) and shelf pelagic (neritic) biotas of each marine region. +The digital ecoregions layer is available for download as an ArcGIS Shapefile. + + +=== Subdivisions === + + +==== Ecoregions ==== +The Marine Ecoregions of the World classification defines 232 marine ecoregions (e.g. Adriatic Sea, Cortezian, Ningaloo, Ross Sea) for the coastal and shelf waters of the world. + + +==== Provinces ==== +These marine ecoregions form part of a nested system and are grouped into 62 provinces (e.g. the South China Sea, Mediterranean Sea, Central Indian Ocean Islands). + + +==== Realms ==== +The provinces in turn, are grouped into 12 major realms. The latter are considered analogous to the eight terrestrial realms, represent large regions of the ocean basins: + +Arctic +Temperate Northern Atlantic +Temperate Northern Pacific +Tropical Atlantic +Western Indo-Pacific +Central Indo-Pacific +Eastern Indo-Pacific +Tropical Eastern Pacific +Temperate South America +Temperate Southern Africa +Temperate Australasia +Southern Ocean + + +== Other marine ecoregion classifications == +Other classifications of marine ecoregions or equivalent areas have been widely developed at national and regional levels, as well as a small number of global schemes. +Each of these systems, along with numerous regional biogeographic classifications, was used to inform the MEOW system. The WWF Global 200 work also identifies a number of major habitat types that correspond to the terrestrial biomes: polar, temperate shelves and seas, temperate upwelling, tropical upwelling, tropical coral, pelagic (trades and westerlies), abyssal, and hadal (ocean trench). + +Briggs Coastal Provinces +One of the most comprehensive early classifications was the system of 53 coastal provinces developed by Briggs in 1974. The near-global system of 64 large marine ecosystems has a partial biogeographic basis. + +WWF Global 200 +The World Wildlife Fund—WWF identified 43 priority marine ecoregions, as part of its Global 200 initiative. + + +== See also == +List of marine ecoregions +Marine botany +Marine ecosystem + + +== References == + + +== External links == + +Nature.org: Marine Ecoregions of the World—MEOW \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_ecosystem-0.md b/data/en.wikipedia.org/wiki/Marine_ecosystem-0.md new file mode 100644 index 000000000..101cf87dd --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_ecosystem-0.md @@ -0,0 +1,39 @@ +--- +title: "Marine ecosystem" +chunk: 1/4 +source: "https://en.wikipedia.org/wiki/Marine_ecosystem" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:30.386953+00:00" +instance: "kb-cron" +--- + +Marine ecosystems are the largest of Earth's aquatic ecosystems and exist in waters that have a high salt content. These systems contrast with freshwater ecosystems, which have a lower salt content. Marine waters cover more than 70% of the surface of the Earth and account for more than 97% of Earth's water supply and 90% of habitable space on Earth. Seawater has an average salinity of 35 parts per thousand of water. Actual salinity varies among different marine ecosystems. Marine ecosystems can be divided into many zones depending upon water depth and shoreline features. The oceanic zone is the vast open part of the ocean where animals such as whales, sharks, and tuna live. The benthic zone consists of substrates below water where many invertebrates live. The intertidal zone is the area between high and low tides. Other near-shore (neritic) zones can include mudflats, seagrass meadows, mangroves, rocky intertidal systems, salt marshes, coral reefs, kelp forests and lagoons. In the deep water, hydrothermal vents may occur where chemosynthetic sulfur bacteria form the base of the food web. +Marine ecosystems are characterized by the biological community of organisms that they are associated with and their physical environment. Classes of organisms found in marine ecosystems include brown algae, dinoflagellates, corals, cephalopods, echinoderms, and sharks. +Marine ecosystems are important sources of ecosystem services and food and jobs for significant portions of the global population. Human uses of marine ecosystems and pollution in marine ecosystems are significantly threats to the stability of these ecosystems. Environmental problems concerning marine ecosystems include unsustainable exploitation of marine resources (for example overfishing of certain species), marine pollution, climate change, and building on coastal areas. Moreover, much of the carbon dioxide causing global warming and heat captured by global warming are absorbed by the ocean, ocean chemistry is changing through processes like ocean acidification which in turn threatens marine ecosystems. +Because of the opportunities in marine ecosystems for humans and the threats created by humans, the international community has prioritized "Life below water" as Sustainable Development Goal 14. The goal is to "Conserve and sustainably use the oceans, seas and marine resources for sustainable development". + +== Types or locations == + +=== Marine coastal ecosystems === + +==== Coral reefs ==== + +Coral reefs are one of the most well-known marine ecosystems in the world, with the largest being the Great Barrier Reef. These reefs are composed of large coral colonies of a variety of species living together. The corals form multiple symbiotic relationships with the organisms around them. + +==== Mangroves ==== + +Mangroves are trees or shrubs that grow in low-oxygen soil near coastlines in tropical or subtropical latitudes. They are an extremely productive and complex ecosystem that connects the land and sea. Mangroves consist of species that are not necessarily related to each other and are often grouped for the characteristics they share rather than genetic similarity. Because of their proximity to the coast, they have all developed adaptions such as salt excretion and root aeration to live in salty, oxygen-depleted water. Mangroves can often be recognized by their dense tangle of roots that act to protect the coast by reducing erosion from storm surges, currents, wave, and tides. The mangrove ecosystem is also an important source of food for many species as well as excellent at sequestering carbon dioxide from the atmosphere with global mangrove carbon storage is estimated at 34 million metric tons per year. + +==== Seagrass meadows ==== + +Seagrasses form dense underwater meadows which are among the most productive ecosystems in the world. They provide habitats and food for a diversity of marine life comparable to coral reefs. This includes invertebrates like shrimp and crabs, cod and flatfish, marine mammals and birds. They provide refuges for endangered species such as seahorses, turtles, and dugongs. They function as nursery habitats for shrimps, scallops and many commercial fish species. Seagrass meadows provide coastal storm protection by the way their leaves absorb energy from waves as they hit the coast. They keep coastal waters healthy by absorbing bacteria and nutrients, and slow the speed of climate change by sequestering carbon dioxide into the sediment of the ocean floor. +Seagrasses evolved from marine algae which colonized land and became land plants, and then returned to the ocean about 100 million years ago. However, today seagrass meadows are being damaged by human activities such as pollution from land runoff, fishing boats that drag dredges or trawls across the meadows uprooting the grass, and overfishing which unbalances the ecosystem. Seagrass meadows are currently being destroyed at a rate of about two football fields every hour. + +==== Kelp forests ==== + +Kelp forests occur worldwide throughout temperate and polar coastal oceans. In 2007, kelp forests were also discovered in tropical waters near Ecuador. +Physically formed by brown macroalgae, kelp forests provide a unique habitat for marine organisms and are a source for understanding many ecological processes. Over the last century, they have been the focus of extensive research, particularly in trophic ecology, and continue to provoke important ideas that are relevant beyond this unique ecosystem. For example, kelp forests can influence coastal oceanographic patterns and provide many ecosystem services. +However, the influence of humans has often contributed to kelp forest degradation. Of particular concern are the effects of overfishing nearshore ecosystems, which can release herbivores from their normal population regulation and result in the overgrazing of kelp and other algae. This can rapidly result in transitions to barren landscapes where relatively few species persist. Already due to the combined effects of overfishing and climate change, kelp forests have all but disappeared in many especially vulnerable places, such as Tasmania's east coast and the coast of Northern California. The implementation of marine protected areas is one management strategy useful for addressing such issues, since it may limit the impacts of fishing and buffer the ecosystem from additive effects of other environmental stressors. + +==== Estuaries ==== \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_ecosystem-1.md b/data/en.wikipedia.org/wiki/Marine_ecosystem-1.md new file mode 100644 index 000000000..f514a0609 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_ecosystem-1.md @@ -0,0 +1,25 @@ +--- +title: "Marine ecosystem" +chunk: 2/4 +source: "https://en.wikipedia.org/wiki/Marine_ecosystem" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:30.386953+00:00" +instance: "kb-cron" +--- + +Estuaries occur where there is a noticeable change in salinity between saltwater and freshwater sources. This is typically found where rivers meet the ocean or sea. The wildlife found within estuaries is unique as the water in these areas is brackish - a mix of freshwater flowing to the ocean and salty seawater. Other types of estuaries also exist and have similar characteristics as traditional brackish estuaries. The Great Lakes are a prime example. There, river water mixes with lake water and creates freshwater estuaries. Estuaries are extremely productive ecosystems that many humans and animal species rely on for various activities. This can be seen as, of the 32 largest cities in the world, 22 are located on estuaries as they provide many environmental and economic benefits such as crucial habitat for many species, and being economic hubs for many coastal communities. Estuaries also provide essential ecosystem services such as water filtration, habitat protection, erosion control, gas regulation nutrient cycling, and it even gives education, recreation and tourism opportunities to people. + +==== Lagoons ==== + +Lagoons are areas that are separated from larger water by natural barriers such as coral reefs or sandbars. There are two types of lagoons, coastal and oceanic/atoll lagoons. A coastal lagoon is, as the definition above, simply a body of water that is separated from the ocean by a barrier. An atoll lagoon is a circular coral reef or several coral islands that surround a lagoon. Atoll lagoons are often much deeper than coastal lagoons. Most lagoons are very shallow meaning that they are greatly affected by changes in precipitation, evaporation and wind. This means that salinity and temperature are widely varied in lagoons and that they can have water that ranges from fresh to hypersaline. Lagoons can be found in on coasts all over the world, on every continent except Antarctica and is an extremely diverse habitat being home to a wide array of species including birds, fish, crabs, plankton and more. Lagoons are also important to the economy as they provide a wide array of ecosystem services in addition to being the home of so many different species. Some of these services include fisheries, nutrient cycling, flood protection, water filtration, and even human tradition. + +==== Salt marsh ==== + +Salt marshes are a transition from the ocean to the land, where fresh and saltwater mix. The soil in these marshes is often made up of mud and a layer of organic material called peat. Peat is characterized as waterlogged and root-filled decomposing plant matter that often causes low oxygen levels (hypoxia). These hypoxic conditions causes growth of the bacteria that also gives salt marshes the sulfurous smell they are often known for. Salt marshes exist around the world and are needed for healthy ecosystems and a healthy economy. They are extremely productive ecosystems and they provide essential services for more than 75 percent of fishery species and protect shorelines from erosion and flooding. Salt marshes can be generally divided into the high marsh, low marsh, and the upland border. The low marsh is closer to the ocean, with it being flooded at nearly every tide except low tide. The high marsh is located between the low marsh and the upland border and it usually only flooded when higher than usual tides are present. The upland border is the freshwater edge of the marsh and is usually located at elevations slightly higher than the high marsh. This region is usually only flooded under extreme weather conditions and experiences much less waterlogged conditions and salt stress than other areas of the marsh. + +==== Intertidal zones ==== + +Intertidal zones are the areas that are visible and exposed to air during low tide and covered up by saltwater during high tide. There are four physical divisions of the intertidal zone with each one having its distinct characteristics and wildlife. These divisions are the Spray zone, High intertidal zone, Middle Intertidal zone, and Low intertidal zone. The Spray zone is a damp area that is usually only reached by the ocean and submerged only under high tides or storms. The high intertidal zone is submerged at high tide but remains dry for long periods between high tides. Due to the large variance of conditions possible in this region, it is inhabited by resilient wildlife that can withstand these changes such as barnacles, marine snails, mussels and hermit crabs. Tides flow over the middle intertidal zone two times a day and this zone has a larger variety of wildlife. The low intertidal zone is submerged nearly all the time except during the lowest tides and life is more abundant here due to the protection that the water gives. + +=== Ocean surface === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_ecosystem-2.md b/data/en.wikipedia.org/wiki/Marine_ecosystem-2.md new file mode 100644 index 000000000..5160fdb3b --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_ecosystem-2.md @@ -0,0 +1,33 @@ +--- +title: "Marine ecosystem" +chunk: 3/4 +source: "https://en.wikipedia.org/wiki/Marine_ecosystem" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:30.386953+00:00" +instance: "kb-cron" +--- + +Organisms that live freely at the surface, termed neuston, include keystone organisms like the golden seaweed Sargassum that makes up the Sargasso Sea, floating barnacles, marine snails, nudibranchs, and cnidarians. Many ecologically and economically important fish species live as or rely upon neuston. Species at the surface are not distributed uniformly; the ocean's surface harbours unique neustonic communities and ecoregions found at only certain latitudes and only in specific ocean basins. But the surface is also on the front line of climate change and pollution. Life on the ocean's surface connects worlds. From shallow waters to the deep sea, the open ocean to rivers and lakes, numerous terrestrial and marine species depend on the surface ecosystem and the organisms found there. +The ocean's surface acts like a skin between the atmosphere above and the water below, and harbours an ecosystem unique to this environment. This sun-drenched habitat can be defined as roughly one metre in depth, as nearly half of UV-B is attenuated within this first meter. Organisms here must contend with wave action and unique chemical and physical properties. The surface is utilised by a wide range of species, from various fish and cetaceans, to species that ride on ocean debris (termed rafters). Most prominently, the surface is home to a unique community of free-living organisms, termed neuston (from the Greek word, υεω, which means both to swim and to float. Floating organisms are also sometimes referred to as pleuston, though neuston is more commonly used). Despite the diversity and importance of the ocean's surface in connecting disparate habitats, and the risks it faces, not a lot is known about neustonic life. +A stream of airborne microorganisms circles the planet above weather systems but below commercial air lanes. Some peripatetic microorganisms are swept up from terrestrial dust storms, but most originate from marine microorganisms in sea spray. In 2018, scientists reported that hundreds of millions of viruses and tens of millions of bacteria are deposited daily on every square meter around the planet. + +=== Deep sea and sea floor === + +The deep sea contains up to 95% of the space occupied by living organisms. Combined with the sea floor (or benthic zone), these two areas have yet to be fully explored and have their organisms documented. + +=== Large marine ecosystems === + +In 1984, National Oceanic and Atmospheric Administration (NOAA) of the United States developed the concept of large marine ecosystems (sometimes abbreviated to LMEs), to identify areas of the oceans for environmental conservation purposes and to enable collaborative ecosystem-based management in transnational areas, in a way consistent with the 1982 UN Convention on the Law of the Sea. This name refers to relatively large regions on the order of 200,000 km2 (77,000 sq mi) or greater, characterized by their distinct bathymetry, hydrography, productivity, and trophically dependent populations. Such LMEs encompass coastal areas from river basins and estuaries to the seaward boundaries of continental shelves and the outer margins of the major ocean current systems. +Altogether, there are 66 LMEs, which contribute an estimated $3 trillion annually. This includes being responsible for 90% of global annual marine fishery biomass. LME-based conservation is based on recognition that the world's coastal ocean waters are degraded by unsustainable fishing practices, habitat degradation, eutrophication, toxic pollution, aerosol contamination, and emerging diseases, and that positive actions to mitigate these threats require coordinated actions by governments and civil society to recover depleted fish populations, restore degraded habitats and reduce coastal pollution. Five modules are considered when assessing LMEs: productivity, fish and fisheries, pollution and ecosystem health, socioeconomics, and governance. Periodically assessing the state of each module within a marine LME is encouraged to ensure maintained health of the ecosystem and future benefit to managing governments. The Global Environment Facility (GEF) aids in managing LMEs off the coasts of Africa and Asia by creating resource management agreements between environmental, fisheries, energy and tourism ministers of bordering countries. This means participating countries share knowledge and resources pertaining to local LMEs to promote longevity and recovery of fisheries and other industries dependent upon LMEs. + +Large marine ecosystems include: + +== Role in ecosystem services == + +In addition to providing many benefits to the natural world, marine ecosystems also provide social, economic, and biological ecosystem services to humans. Pelagic marine systems regulate the global climate, contribute to the water cycle, maintain biodiversity, provide food and energy resources, and create opportunities for recreation and tourism. Economically, marine systems support billions of dollars' worth of capture fisheries, aquaculture, offshore oil and gas, and trade and shipping. +Ecosystem services fall into multiple categories, including supporting services, provisioning services, regulating services, and cultural services. +The productivity of a marine ecosystem can be measured in several ways. Measurements pertaining to zooplankton biodiversity and species composition, zooplankton biomass, water-column structure, photosynthetically active radiation, transparency, chlorophyll-a, nitrate, and primary production are used to assess changes in LME productivity and potential fisheries yield. Sensors attached to the bottom of ships or deployed on floats can measure these metrics and be used to quantitatively describe changes in productivity alongside physical changes in the water column such as temperature and salinity. This data can be used in conjunction with satellite measurements of chlorophyll and sea surface temperatures to validate measurements and observe trends on greater spatial and temporal scales. +Bottom-trawl surveys and pelagic-species acoustic surveys are used to assess changes in fish biodiversity and abundance in LMEs. Fish populations can be surveyed for stock identification, length, stomach content, age-growth relationships, fecundity, coastal pollution and associated pathological conditions, as well as multispecies trophic relationships. Fish trawls can also collect sediment and inform us about ocean-bottom conditions such as anoxia. + +== Threats == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_ecosystem-3.md b/data/en.wikipedia.org/wiki/Marine_ecosystem-3.md new file mode 100644 index 000000000..9cc30e550 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_ecosystem-3.md @@ -0,0 +1,44 @@ +--- +title: "Marine ecosystem" +chunk: 4/4 +source: "https://en.wikipedia.org/wiki/Marine_ecosystem" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:30.386953+00:00" +instance: "kb-cron" +--- + +=== Human exploitation and development === +Coastal marine ecosystems experience growing population pressures with nearly 40% of people in the world living within 100 km of the coast. Humans often aggregate near coastal habitats to take advantage of ecosystem services. For example, coastal capture fisheries from mangroves and coral reef habitats are estimated to be worth a minimum of $34 billion per year. Yet, many of these habitats are either marginally protected or not protected. Mangrove area has declined worldwide by more than one-third since 1950, and 60% of the world's coral reefs are now immediately or directly threatened. Human development, aquaculture, and industrialization often lead to the destruction, replacement, or degradation of coastal habitats. +Moving offshore, pelagic marine systems are directly threatened by overfishing. Global fisheries landings peaked in the late 1980s, but are now declining, despite increasing fishing effort. Fish biomass and average trophic level of fisheries landing are decreasing, leading to declines in marine biodiversity. In particular, local extinctions have led to declines in large, long-lived, slow-growing species, and those that have narrow geographic ranges. Biodiversity declines can lead to associated declines in ecosystem services. A long-term study reports the decline of 74–92% of catch per unit effort of sharks in Australian coastline from the 1960s to 2010s. Such biodiversity losses impact not just species themselves, but humans as well, and can contribute to climate change across the globe. The National Oceanic and Atmospheric Administration (NOAA) states that managing and protecting marine ecosystems is crucial in attempting to conserve biodiversity in the face of Earth's rapidly changing climate. + +=== Pollution === + +=== Invasive species === + +Global aquarium trade +Ballast water transport +Aquaculture + +=== Climate change === + +Warming temperatures (see ocean heat content, sea surface temperature, and marine heat wave) +Increased frequency/intensity of storms +Ocean acidification +Sea level rise + +== Society and culture == + +=== Global goals === +By integrating socioeconomic metrics with ecosystem management solutions, scientific findings can be utilized to benefit both the environment and economy of local regions. Management efforts must be practical and cost-effective. In 2000, the Department of Natural Resource Economics at the University of Rhode Island has created a method for measuring and understanding the human dimensions of LMEs and for taking into consideration both socioeconomic and environmental costs and benefits of managing Large Marine Ecosystems. +International attention to address the threats of coasts has been captured in Sustainable Development Goal 14 "Life Below Water" which sets goals for international policy focused on preserving coastal ecosystems and supporting more sustainable economic practices for coastal communities. Furthermore, the United Nations has declared 2021-2030 the UN Decade on Ecosystem Restoration, but restoration of coastal ecosystems has received insufficient attention. + +== See also == + +== References == + +== External links == + +U.S. Environmental Protection Agency—EPA: Marine Ecosystems +Smithsonian Institution: Ocean Portal +Marine Ecosystems Research Programme (UK) \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_energy-0.md b/data/en.wikipedia.org/wiki/Marine_energy-0.md new file mode 100644 index 000000000..7d1820634 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_energy-0.md @@ -0,0 +1,51 @@ +--- +title: "Marine energy" +chunk: 1/3 +source: "https://en.wikipedia.org/wiki/Marine_energy" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:31.644809+00:00" +instance: "kb-cron" +--- + +Marine energy, also known as ocean energy, ocean power, or marine and hydrokinetic energy, refers to energy harnessed from waves, tides, salinity gradients, and temperature differences in the ocean. The movement of water in the world's oceans stores vast amounts of kinetic energy, which can be converted into electricity to power homes, transportation, and industries. + +Marine energy includes wave power, which is derived from surface waves, and tidal power, which is obtained from the kinetic energy of moving water. Offshore wind power, however, is not considered marine energy because it is generated from wind, even if the wind turbines are located over water.The oceans have a tremendous amount of energy and are close to many if not most concentrated populations. Ocean energy has the potential of providing a substantial amount of new renewable energy around the world. +While marine energy is a sustainable alternative to fossil fuels, its development can impact marine ecosystems, wildlife, and the physical environment. Potential effects include habitat disruption, noise pollution, and electromagnetic fields from subsea cables, which may require mitigation strategies such as fish-friendly turbine designs and environmental impact assessments. +Government policies, economic incentives, and regulatory frameworks contribute significantly to advancing marine energy, with countries like the UK, Canada, and South Korea leading in tidal and wave energy projects. + +== Global potential == +The global potential for marine energy is significant, with estimates suggesting that 20,000 to 80,000 terawatt-hours per year (TWh/y) of electricity could be generated from ocean temperature differences, salinity gradients, tides, currents, waves, and swells. + +Indonesia, as an archipelagic country that is three quarters ocean, has 49 GW recognized potential ocean energy and has 727 GW theoretical potential ocean energy. + +== Forms of ocean energy == + +The oceans are a vast, largely untapped source of energy, including surface waves, fluid flow, salinity gradients, and thermal differences. +Marine and Hydrokinetic (MHK) or marine energy development in U.S. and international waters includes projects using the following devices: + +Wave power converters in open coastal areas with significant waves; +Tidal turbines placed in coastal and estuarine areas; +In-stream turbines in fast-moving rivers; +Ocean current turbines in areas of strong marine currents; +Ocean thermal energy converters in deep tropical waters. + +=== Marine current power === + +Strong ocean currents are driven by temperature, wind, salinity, bathymetry, and the rotation of the Earth. The Sun acts as the primary driving force, causing winds and temperature differences. Because there are only small fluctuations in current speed and stream location with no changes in direction, ocean currents may be suitable locations for deploying energy extraction devices such as turbines. +Ocean currents are instrumental in determining the climate in many regions around the world. While little is known about the effects of removing ocean current energy, the impacts of removing current energy on the farfield environment may be a significant environmental concern. The typical turbine issues with blade strike, entanglement of marine organisms, and acoustic effects still exists; however, these may be magnified due to the presence of more diverse populations of marine organisms using ocean currents for migration purposes. Locations can be further offshore and therefore require longer power cables that could affect the marine environment with electromagnetic output. + +=== Osmotic power === + +At the mouth of rivers where fresh water mixes with salt water, energy associated with the salinity gradient can be harnessed using pressure-retarded reverse osmosis process and associated conversion technologies. Another system is based on using freshwater upwelling through a turbine immersed in seawater, and one involving electrochemical reactions is also in development. +Significant research took place from 1975 to 1985 and gave various results regarding the economy of PRO and RED plants. Small-scale investigations into salinity power production take place in other countries like Japan, Israel, and the United States. In Europe the research is concentrated in Norway and the Netherlands, in both places small pilots are tested. Salinity gradient energy is the energy available from the difference in salt concentration between freshwater with saltwater. This energy source is not easy to understand, as it is not directly occurring in nature in the form of heat, waterfalls, wind, waves, or radiation. + +=== Ocean thermal energy === + +Water typically varies in temperature from the surface warmed by direct sunlight to greater depths where sunlight cannot penetrate. This differential is greatest in tropical waters, making this technology most applicable in water locations. A fluid is often vaporized to drive a turbine that may generate electricity or produce desalinized water. Systems may be either open-cycle, closed-cycle, or hybrid. + +=== Tidal power === + +The energy from moving masses of water – a popular form of hydroelectric power generation. Tidal power generation comprises three main forms, namely tidal stream power, tidal barrage power, and dynamic tidal power. + +=== Wave power === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_energy-1.md b/data/en.wikipedia.org/wiki/Marine_energy-1.md new file mode 100644 index 000000000..fc4ea2894 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_energy-1.md @@ -0,0 +1,37 @@ +--- +title: "Marine energy" +chunk: 2/3 +source: "https://en.wikipedia.org/wiki/Marine_energy" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:31.644809+00:00" +instance: "kb-cron" +--- + +Solar energy from the Sun creates temperature differentials that result in wind. The interaction between wind and the surface of water creates waves, which are larger when there is a greater distance for them to build up. Wave energy potential is greatest between 30° and 60° latitude in both hemispheres on the west coast because of the global direction of wind. When evaluating wave energy as a technology type, it is important to distinguish between the four most common approaches: point absorber buoys, surface attenuators, oscillating water columns, and overtopping devices. +The wave energy sector is reaching a significant milestone in the development of the industry, with steps towards commercial viability being taken. The more advanced device developers are currently progressing beyond single unit demonstration devices and are proceeding to array development and multi-megawatt projects. The backing of major utility companies is now manifesting itself through partnerships within the development process, unlocking further investment, and in some cases, international co-operation. +At a simplified level, wave energy technology can be located near-shore and offshore. Wave energy converters can also be designed for operation in specific water depth conditions: deep water, intermediate water or shallow water. The fundamental device design will be dependent on the location of the device and the intended resource characteristics. + +== Environmental effects == +Marine energy, harnessed from renewable sources such as waves, tides, and ocean currents, is widely regarded as a sustainable alternative to fossil fuels. However, similar to other energy technologies, marine energy may have environmental impacts that need to be carefully assessed. These effects can be broadly categorized into impacts on marine ecosystems, wildlife, and the physical environment. + +Impacts on Marine Ecosystems +The deployment of marine energy infrastructure can alter local ecosystems by modifying water flow, sediment transport, and habitat structures. For instance, tidal barrages, which block the natural flow of water, can lead to changes in salinity levels and sediment deposition in estuaries. Such alterations can disrupt benthic habitats, affecting species that rely on these environments for survival. Research has shown that tidal energy projects can result in localized habitat loss, particularly for species sensitive to changes in sediment composition and water flow. +Wave energy converters (WECs) can also influence marine ecosystems. While they may create artificial reefs that attract certain species, they can simultaneously displace others, leading to competition for resources. In some cases, these structures have been observed to enhance biodiversity, but the overall impact depends on the specific design and location of the devices. The ecological trade-offs associated with WECs highlight the importance of careful planning and monitoring to balance energy production with environmental conservation. + +Effects on Marine Wildlife + +Marine energy technologies pose risks to marine wildlife, particularly through collisions with underwater turbines, noise pollution, and electromagnetic fields (EMFs) generated by subsea cables. For example, tidal turbines, which operate in high-flow environments, can pose a threat to fish and marine mammals that may collide with rotating blades. While the risk of collision is generally considered low, it can be significant for slow-moving or migratory species, necessitating the development of fish-friendly turbine designs. +Noise pollution is another concern associated with marine energy installations. The construction and operation of devices can generate underwater noise, which may disrupt marine life. Cetaceans, such as whales and dolphins, rely heavily on sound for communication, navigation, and foraging. Prolonged exposure to noise can lead to behavioral changes, increased stress levels, and even habitat abandonment. Mitigation measures, such as noise-reduction technologies and strategic placement of devices, are required to minimize these impacts. +Electromagnetic fields (EMFs) from subsea power cables can also affect marine species, particularly those sensitive to electromagnetic stimuli, such as sharks and rays. + +Physical and Chemical Changes +The installation of marine energy infrastructure can lead to physical changes in the marine environment, such as altered wave patterns and coastal erosion. For example, large-scale wave energy farms can reduce the amount of wave energy reaching the shore, which may impact coastal processes like sediment transport. In some cases, this could exacerbate coastal erosion, particularly in areas already vulnerable to such changes. +Chemical impacts, such as the release of antifouling agents or other pollutants from marine energy devices, are another potential concern. While these impacts are generally minor compared to those associated with fossil fuel extraction, they still require careful management to minimize harm to marine ecosystems. Regular maintenance and the use of environmentally friendly materials can help mitigate these risks. + +Mitigation and Best Practices +Governments and organizations have developed regulatory frameworks and best practices to address these environmental effects. Regulatory bodies typically require environmental impact assessments (EIAs) before deploying marine energy projects. These assessments help identify potential risks and guide mitigation strategies, such as the use of fish-friendly turbine designs, noise-reduction technologies, and strategic placement of devices to minimize ecological disruption. +International organizations, such as the International Renewable Energy Agency (IRENA), have published guidelines for sustainable marine energy development. These guidelines emphasize the importance of stakeholder engagement, adaptive management, and long-term monitoring to ensure that marine energy projects are environmentally responsible. By adhering to these principles, the marine energy industry can balance the need for renewable energy with the protection of marine ecosystems and wildlife. + +== Policies, Economics, and Government Initiatives == +The development of marine energy is heavily influenced by government policies, economic incentives, and regulatory frameworks. These factors play a critical role in fostering innovation, attracting investment, and ensuring the sustainable deployment of marine energy technologies. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_energy-2.md b/data/en.wikipedia.org/wiki/Marine_energy-2.md new file mode 100644 index 000000000..ff5bd1df1 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_energy-2.md @@ -0,0 +1,53 @@ +--- +title: "Marine energy" +chunk: 3/3 +source: "https://en.wikipedia.org/wiki/Marine_energy" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:31.644809+00:00" +instance: "kb-cron" +--- + +Economic Considerations +Marine energy is still in the early stages of commercialization, and its economic viability depends on reducing costs and improving efficiency. The high capital expenditure (CapEx) and operational expenditure (OpEx) associated with marine energy projects have historically been barriers to widespread adoption. However, technological advancements, economies of scale, and government support are helping to drive down costs. For example, the levelized cost of energy (LCOE) for tidal and wave energy has decreased significantly in recent years, though it remains higher than that of more established renewable energy sources like wind and solar. +Government subsidies, grants, and tax incentives are often used to offset the high initial costs of marine energy projects. These financial mechanisms are designed to encourage private sector investment and accelerate the deployment of marine energy technologies. + +Government Policies and Regulatory Frameworks +Government policies significantly influence the development of marine energy. Many countries have implemented renewable energy targets, feed-in tariffs, and renewable portfolio standards (RPS) to promote the development of marine energy. For instance, the European Union has set ambitious renewable energy targets as part of its Green Deal, with marine energy identified as a key component of its strategy to achieve carbon neutrality by 2050. +In the United Kingdom, the Marine Energy Programme has been instrumental in supporting the development of tidal and wave energy. The program provides funding for research and development (R&D), as well as demonstration projects. The UK government has also established the Contracts for Difference (CfD) scheme, which guarantees a fixed price for electricity generated from marine energy, providing long-term revenue certainty for developers. +United States has implemented policies to support marine energy through the Department of Energy's Water Power Technologies Office (WPTO). The WPTO funds R&D initiatives and provides grants for pilot projects. The Marine Renewable Energy Act has also been proposed to create a regulatory framework for the development of marine energy resources in U.S. waters. + +Case Studies +United Kingdom: The UK is a global leader in marine energy, particularly tidal energy. The MeyGen tidal energy project in Scotland is one of the largest tidal stream projects in the world. Supported by government funding and private investment, the project has demonstrated the potential for large-scale tidal energy generation. The UK's supportive policy environment, including the CfD scheme, has played a key role in the project's success. +Canada: Canada has significant marine energy resources, particularly in the Bay of Fundy, which has some of the highest tidal ranges in the world. The Fundy Ocean Research Center for Energy (FORCE) in Nova Scotia serves as a test site for tidal energy technologies. The Canadian government has provided funding for FORCE and established regulatory frameworks to facilitate the deployment of marine energy projects. +South Korea: South Korea has made substantial investments in marine energy as part of its renewable energy strategy. The Sihwa Lake Tidal Power Station is the world's largest tidal power plant, with a capacity of 254 MW. The project was developed with significant government support and is a representative example of large-scale tidal energy deployment. +France: France has a long history of tidal energy development, dating back to the Rance Tidal Power Station, which was commissioned in 1966 and remains one of the oldest and most successful tidal power plants in the world. The French government continues to support marine energy through R&D funding and policy initiatives aimed at expanding renewable energy capacity. + +== See also == + +Energy harvesting +Marine current power +Tidal power +Wave power +Ocean thermal energy conversion +Osmotic power +Renewable energy +Renewable energy commercialization + +== References == + +== Further reading == +Omar Ellabban, Haitham Abu-Rub, Frede Blaabjerg: Renewable energy resources: Current status, future prospects and their enabling technology. Renewable and Sustainable Energy Reviews 39, (2014), 748–764, doi:10.1016/j.rser.2014.07.113. + +== External links == + +The Ocean Energy Systems +European Ocean Energy Association +The European Marine Energy Centre (EMEC) +Ocean Energy Council +SuperGen UK Centre for Marine Energy Research +Portal and Repository for Information on Marine Renewable Energy +Marine Energy Projects Database +Tethys - Environmental Effects of Wind and Marine Renewable Energy +Tethys Engineering - Technical information on marine energy +Marine and Hydrokinetic Data Repository \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_habitat-0.md b/data/en.wikipedia.org/wiki/Marine_habitat-0.md new file mode 100644 index 000000000..e183ad007 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_habitat-0.md @@ -0,0 +1,40 @@ +--- +title: "Marine habitat" +chunk: 1/8 +source: "https://en.wikipedia.org/wiki/Marine_habitat" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:24.136463+00:00" +instance: "kb-cron" +--- + +A marine habitat is a habitat that supports marine life. Marine life depends in some way on the saltwater that is in the sea (the term marine comes from the Latin mare, meaning sea or ocean). A habitat is an ecological or environmental area inhabited by one or more living species. The marine environment supports many kinds of these habitats. +Marine habitats can be divided into coastal and open ocean habitats. Coastal habitats are found in the area that extends from as far as the tide comes in on the shoreline out to the edge of the continental shelf. Most marine life is found in coastal habitats, even though the shelf area occupies only seven percent of the total ocean area. Open ocean habitats are found in the deep ocean beyond the edge of the continental shelf. +Alternatively, marine habitats can be divided into pelagic and demersal zones. Pelagic habitats are found near the surface or in the open water column, away from the bottom of the ocean. Demersal habitats are near or on the bottom of the ocean. An organism living in a pelagic habitat is said to be a pelagic organism, as in pelagic fish. Similarly, an organism living in a demersal habitat is said to be a demersal organism, as in demersal fish. Pelagic habitats are intrinsically shifting and ephemeral, depending on what ocean currents are doing. +Marine habitats can be modified by their inhabitants. Some marine organisms, like corals, kelp, mangroves and seagrasses, are ecosystem engineers which reshape the marine environment to the point where they create further habitat for other organisms. By volume the ocean provides most of the habitable space on the planet. + +== Overview == + +In contrast to terrestrial habitats, marine habitats are shifting and ephemeral. Swimming organisms find areas by the edge of a continental shelf a good habitat, but only while upwellings bring nutrient rich water to the surface. Shellfish find habitat on sandy beaches, but storms, tides and currents mean their habitat continually reinvents itself. +The presence of seawater is common to all marine habitats. Beyond that many other things determine whether a marine area makes a good habitat and the type of habitat it makes. For example: + +temperature – is affected by geographical latitude, ocean currents, weather, the discharge of rivers, and by the presence of hydrothermal vents or cold seeps +sunlight – photosynthetic processes depend on how deep and turbid the water is +nutrients – are transported by ocean currents to different marine habitats from land runoff, or by upwellings from the deep sea, or they sink through the sea as marine snow +salinity – varies, particularly in estuaries or near river deltas, or by hydrothermal vents +dissolved gases – oxygen levels in particular, can be increased by wave actions and decreased during algal blooms +acidity – this is partly to do with dissolved gases above, since the acidity of the ocean is largely controlled by how much carbon dioxide is in the water. +turbulence – ocean waves, fast currents and the agitation of water affect the nature of habitats +cover – the availability of cover such as the adjacency of the sea bottom, or the presence of floating objects +substrate – The slope, orientation, profile and rugosity of hard substrates, and particle size, sorting and density of unconsolidated sediment bottoms can make a big difference to the life forms that can settle on it. +the occupying organisms themselves – since organisms modify their habitats by the act of occupying them, and some, like corals, kelp, mangroves and seagrasses, create further habitats for other organisms. + +There are five major oceans, of which the Pacific Ocean is nearly as large as the rest put together. Coastlines fringe the land for nearly 380,000 kilometres. + +Altogether, the ocean occupies 71 percent of the world surface, averaging nearly four kilometres in depth. By volume, the ocean contains more than 99 percent of the Earth's liquid water. The science fiction writer Arthur C. Clarke has pointed out it would be more appropriate to refer to the planet Earth as the planet Sea or the planet +Ocean. +Marine habitats can be broadly divided into pelagic and demersal habitats. Pelagic habitats are the habitats of the open water column, away from the bottom of the ocean. Demersal habitats are the habitats that are near or on the bottom of the ocean. An organism living in a pelagic habitat is said to be a pelagic organism, as in pelagic fish. Similarly, an organism living in a demersal habitat is said to be a demersal organism, as in demersal fish. Pelagic habitats are intrinsically ephemeral, depending on what ocean currents are doing. +The land-based ecosystem depends on topsoil and fresh water, while the marine ecosystem depends on dissolved nutrients washed down from the land. +Ocean deoxygenation poses a threat to marine habitats, due to the growth of low oxygen zones. + +== Ocean currents == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_habitat-1.md b/data/en.wikipedia.org/wiki/Marine_habitat-1.md new file mode 100644 index 000000000..0870f26dc --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_habitat-1.md @@ -0,0 +1,32 @@ +--- +title: "Marine habitat" +chunk: 2/8 +source: "https://en.wikipedia.org/wiki/Marine_habitat" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:24.136463+00:00" +instance: "kb-cron" +--- + +In marine systems, ocean currents have a key role determining which areas are effective as habitats, since ocean currents transport the basic nutrients needed to support marine life. Plankton are the life forms that inhabit the ocean that are so small (less than 2 mm) that they cannot effectively propel themselves through the water, but must drift instead with the currents. If the current carries the right nutrients, and if it also flows at a suitably shallow depth where there is plenty of sunlight, then such a current itself can become a suitable habitat for photosynthesizing tiny algae called phytoplankton. These tiny plants are the primary producers in the ocean, at the start of the food chain. In turn, as the population of drifting phytoplankton grows, the water becomes a suitable habitat for zooplankton, which feed on the phytoplankton. While phytoplankton are tiny drifting plants, zooplankton are tiny drifting animals, such as the larvae of fish and marine invertebrates. If sufficient zooplankton establish themselves, the current becomes a candidate habitat for the forage fish that feed on them. And then if sufficient forage fish move to the area, it becomes a candidate habitat for larger predatory fish and other marine animals that feed on the forage fish. In this dynamic way, the current itself can, over time, become a moving habitat for multiple types of marine life. +Ocean currents can be generated by differences in the density of the water. How dense water is depends on how saline or warm it is. If water contains differences in salt content or temperature, then the different densities will initiate a current. Water that is saltier or cooler will be denser, and will sink in relation to the surrounding water. Conversely, warmer and less salty water will float to the surface. Atmospheric winds and pressure differences also produces surface currents, waves and seiches. Ocean currents are also generated by the gravitational pull of the sun and moon (tides), and seismic activity (tsunami). + +The rotation of the Earth affects the direction ocean currents take, and explains which way the large circular ocean gyres rotate in the image above left. Suppose a current at the equator is heading north. The Earth rotates eastward, so the water possesses that rotational momentum. But the further the water moves north, the slower the earth moves eastward. If the current could get to the North Pole, the earth would not be moving eastward at all. To conserve its rotational momentum, the further the current travels north the faster it must move eastward. So the effect is that the current curves to the right. This is the Coriolis effect. It is weakest at the equator and strongest at the poles. The effect is opposite south of the equator, where currents curve left. + +== Topography == + +== Biomass == + +One measure of the relative importance of different marine habitats is the rate at which they produce biomass. + +== Coastal == + +Marine coasts are dynamic environments which constantly change, like the ocean which partially shape them. The Earth's natural processes, including weather and sea level change, result in the erosion, accretion and resculpturing of coasts as well as the flooding and creation of continental shelves and drowned river valleys. +The main agents responsible for deposition and erosion along coastlines are waves, tides and currents. The formation of coasts also depends on the nature of the rocks they are made of – the harder the rocks the less likely they are to erode, so variations in rock hardness result in coastlines with different shapes. +Tides often determine the range over which sediment is deposited or eroded. Areas with high tidal ranges allow waves to reach farther up the shore, and areas with lower tidal ranges produce deposition at a smaller elevation interval. The tidal range is influenced by the size and shape of the coastline. Tides do not typically cause erosion by themselves; however, tidal bores can erode as the waves surge up river estuaries from the ocean. + +Waves erode coastline as they break on shore releasing their energy; the larger the wave the more energy it releases and the more sediment it moves. Sediment deposited by waves comes from eroded cliff faces and is moved along the coastline by the waves. Sediment deposited by rivers is the dominant influence on the amount of sediment located on a coastline. +The sedimentologist Francis Shepard classified coasts as primary or secondary. + +Primary coasts are shaped by non-marine processes, by changes in the land form. If a coast is in much the same condition as it was when sea level was stabilised after the last ice age, it is called a primary coast. "Primary coasts are created by erosion (the wearing away of soil or rock), deposition (the buildup of sediment or sand) or tectonic activity (changes in the structure of the rock and soil because of earthquakes). Many of these coastlines were formed as the sea level rose during the last 18,000 years, submerging river and glacial valleys to form bays and fjords." An example of a primary coast is a river delta, which forms when a river deposits soil and other material as it enters the sea. +Secondary coasts are produced by marine processes, such as the action of the sea or by creatures that live in it. Secondary coastlines include sea cliffs, barrier islands, mud flats, coral reefs, mangrove swamps and salt marshes. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_habitat-2.md b/data/en.wikipedia.org/wiki/Marine_habitat-2.md new file mode 100644 index 000000000..f08fb77bd --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_habitat-2.md @@ -0,0 +1,27 @@ +--- +title: "Marine habitat" +chunk: 3/8 +source: "https://en.wikipedia.org/wiki/Marine_habitat" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:24.136463+00:00" +instance: "kb-cron" +--- + +Continental coastlines usually have a continental shelf, a shelf of relatively shallow water, less than 200 metres deep, which extends 68 km on average beyond the coast. Worldwide, continental shelves occupy a total area of about 24 million km2 (9 million sq mi), 8% of the ocean's total area and nearly 5% of the world's total area. Since the continental shelf is usually less than 200 metres deep, it follows that coastal habitats are generally photic, situated in the sunlit epipelagic zone. This means the conditions for photosynthetic processes so important for primary production, are available to coastal marine habitats. Because land is nearby, there are large discharges of nutrient rich land runoff into coastal waters. Further, periodic upwellings from the deep ocean can provide cool and nutrient rich currents along the edge of the continental shelf. +As a result, coastal marine life is the most abundant in the world. It is found in tidal pools, fjords and estuaries, near sandy shores and rocky coastlines, around coral reefs and on or above the continental shelf. Coastal fish include small forage fish as well as the larger predator fish that feed on them. Forage fish thrive in inshore waters where high productivity results from upwelling and shoreline run off of nutrients. Some are partial residents that spawn in streams, estuaries and bays, but most complete their life cycle in the zone. There can also be a mutualism between species that occupy adjacent marine habitats. For example, fringing reefs just below low tide level have a mutually beneficial relationship with mangrove forests at high tide level and sea grass meadows in between: the reefs protect the mangroves and seagrass from strong currents and waves that would damage them or erode the sediments in which they are rooted, while the mangroves and seagrass protect the coral from large influxes of silt, fresh water and pollutants. This additional level of variety in the environment is beneficial to many types of coral reef animals, which for example may feed in the sea grass and use the reefs for protection or breeding. +Coastal habitats are the most visible marine habitats, but they are not the only important marine habitats. Coastlines run for 380,000 kilometres, and the total volume of the ocean is 1,370 million cu km. This means that for each metre of coast, there is 3.6 cu km of ocean space available somewhere for marine habitats. + +=== Intertidal === + +Intertidal zones, those areas close to shore, are constantly being exposed and covered by the ocean's tides. A huge array of life lives within this zone. +Shore habitats range from the upper intertidal zones to the area where land vegetation takes prominence. It can be underwater anywhere from daily to very infrequently. Many species here are scavengers, living off of sea life that is washed up on the shore. Many land animals also make much use of the shore and intertidal habitats. A subgroup of organisms in this habitat bores and grinds exposed rock through the process of bioerosion. + +=== Sandy shores === + +Sandy shores, also called beaches, are coastal shorelines where sand accumulates. Waves and currents shift the sand, continually building and eroding the shoreline. Longshore currents flow parallel to the beaches, making waves break obliquely on the sand. These currents transport large amounts of sand along coasts, forming spits, barrier islands and tombolos. Longshore currents also commonly create offshore bars, which give beaches some stability by reducing erosion. +Sandy shores are full of life. The grains of sand host diatoms, bacteria and other microscopic creatures. Some fish and turtles return to certain beaches and spawn eggs in the sand. Birds habitat beaches, like gulls, loons, sandpipers, terns and pelicans. Aquatic mammals, such sea lions, recuperate on them. Clams, periwinkles, crabs, shrimp, starfish and sea urchins are found on most beaches. +Sand is a sediment made from small grains or particles with diameters between about 60 μm and 2 mm. Mud (see mudflats below) is a sediment made from particles finer than sand. This small particle size means that mud particles tend to stick together, whereas sand particles do not. Mud is not easily shifted by waves and currents, and when it dries out, cakes into a solid. By contrast, sand is easily shifted by waves and currents, and when sand dries out it can be blown in the wind, accumulating into shifting sand dunes. Beyond the high tide mark, if the beach is low-lying, the wind can form rolling hills of sand dunes. Small dunes shift and reshape under the influence of the wind while larger dunes stabilise the sand with vegetation. +Ocean processes grade loose sediments to particle sizes other than sand, such as gravel or cobbles. Waves breaking on a beach can leave a berm, which is a raised ridge of coarser pebbles or sand, at the high tide mark. Shingle beaches are made of particles larger than sand, such as cobbles, or small stones. These beaches make poor habitats. Little life survives because the stones are churned and pounded together by waves and currents. + +=== Rocky shores === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_habitat-3.md b/data/en.wikipedia.org/wiki/Marine_habitat-3.md new file mode 100644 index 000000000..4420fc318 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_habitat-3.md @@ -0,0 +1,36 @@ +--- +title: "Marine habitat" +chunk: 4/8 +source: "https://en.wikipedia.org/wiki/Marine_habitat" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:24.136463+00:00" +instance: "kb-cron" +--- + +The relative solidity of rocky shores seems to give them a permanence compared to the shifting nature of sandy shores. This apparent stability is not real over even quite short geological time scales, but it is real enough over the short life of an organism. In contrast to sandy shores, plants and animals can anchor themselves to the rocks. +Competition can develop for the rocky spaces. For example, barnacles can compete successfully on open intertidal rock faces to the point where the rock surface is covered with them. Barnacles resist desiccation and grip well to exposed rock faces. However, in the crevices of the same rocks, the inhabitants are different. Here mussels can be the successful species, secured to the rock with their byssal threads. +Rocky and sandy coasts are vulnerable because humans find them attractive and want to live near them. An increasing proportion of the humans live by the coast, putting pressure on coastal habitats. + +=== Mudflats === + +Mudflats are coastal wetlands that form when mud is deposited by tides or rivers. They are found in sheltered areas such as bays, bayous, lagoons, and estuaries. Mudflats may be viewed geologically as exposed layers of bay mud, resulting from deposition of estuarine silts, clays and marine animal detritus. Most of the sediment within a mudflat is within the intertidal zone, and thus the flat is submerged and exposed approximately twice daily. + +=== Mangrove forests and salt marshes === + +Mangrove swamps and salt marshes form important coastal habitats in tropical and temperate areas respectively. +Mangroves are species of shrubs and medium size trees that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes 25° N and 25° S. The saline conditions tolerated by various species range from brackish water, through pure seawater (30 to 40 ppt), to water concentrated by evaporation to over twice the salinity of ocean seawater (up to 90 ppt). There are many mangrove species, not all closely related. The term "mangrove" is used generally to cover all of these species, and it can be used narrowly to cover just mangrove trees of the genus Rhizophora. +Mangroves form a distinct characteristic saline woodland or shrubland habitat, called a mangrove swamp or mangrove forest. Mangrove swamps are found in depositional coastal environments, where fine sediments (often with high organic content) collect in areas protected from high-energy wave action. Mangroves dominate three quarters of tropical coastlines. + +=== Estuaries === + +An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and ocean environments and are subject to both marine influences, such as tides, waves, and the influx of saline water; and riverine influences, such as flows of fresh water and sediment. The inflow of both seawater and freshwater provide high levels of nutrients in both the water column and sediment, making estuaries among the most productive natural habitats in the world. +Most estuaries were formed by the flooding of river-eroded or glacially scoured valleys when sea level began to rise about 10,000-12,000 years ago. They are amongst the most heavily populated areas throughout the world, with about 60% of the world's population living along estuaries and the coast. As a result, estuaries are suffering degradation by many factors, including sedimentation from soil erosion from deforestation; overgrazing and other poor farming practices; overfishing; drainage and filling of wetlands; eutrophication due to excessive nutrients from sewage and animal wastes; pollutants including heavy metals, PCBs, radionuclides and hydrocarbons from sewage inputs; and diking or damming for flood control or water diversion. +Estuaries provide habitats for a large number of organisms and support very high productivity. Estuaries provide habitats for salmon and sea trout nurseries, as well as migratory bird populations. Two of the main characteristics of estuarine life are the variability in salinity and sedimentation. Many species of fish and invertebrates have various methods to control or conform to the shifts in salt concentrations and are termed osmoconformers and osmoregulators. Many animals also burrow to avoid predation and to live in the more stable sedimental environment. However, large numbers of bacteria are found within the sediment which have a very high oxygen demand. This reduces the levels of oxygen within the sediment often resulting in partially anoxic conditions, which can be further exacerbated by limited water flux. Phytoplankton are key primary producers in estuaries. They move with the water bodies and can be flushed in and out with the tides. Their productivity is largely dependent on the turbidity of the water. The main phytoplankton present are diatoms and dinoflagellates which are abundant in the sediment. + +=== Kelp forests === + +Kelp forests are underwater areas with a high density of kelp. They form some of the most productive and dynamic ecosystems on Earth. Smaller areas of anchored kelp are called kelp beds. Kelp forests occur worldwide throughout temperate and polar coastal oceans. +Kelp forests provide a unique three-dimensional habitat for marine organisms and are a source for understanding many ecological processes. Over the last century, they have been the focus of extensive research, particularly in trophic ecology, and continue to provoke important ideas that are relevant beyond this unique ecosystem. For example, kelp forests can influence coastal oceanographic patterns and provide many ecosystem services. +However, humans have contributed to kelp forest degradation. Of particular concern are the effects of overfishing nearshore ecosystems, which can release herbivores from their normal population regulation and result in the over-grazing of kelp and other algae. This can rapidly result in transitions to barren landscapes where relatively few species persist. +Frequently considered an ecosystem engineer, kelp provides a physical substrate and habitat for kelp forest communities. In algae (Kingdom: Protista), the body of an individual organism is known as a thallus rather than as a plant (Kingdom: Plantae). The morphological structure of a kelp thallus is defined by three basic structural units: \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_habitat-4.md b/data/en.wikipedia.org/wiki/Marine_habitat-4.md new file mode 100644 index 000000000..dd5c69bea --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_habitat-4.md @@ -0,0 +1,36 @@ +--- +title: "Marine habitat" +chunk: 5/8 +source: "https://en.wikipedia.org/wiki/Marine_habitat" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:24.136463+00:00" +instance: "kb-cron" +--- + +The holdfast is a root-like mass that anchors the thallus to the sea floor, though unlike true roots it is not responsible for absorbing and delivering nutrients to the rest of the thallus; +The stipe is analogous to a plant stalk, extending vertically from the holdfast and providing a support framework for other morphological features; +The fronds are leaf- or blade-like attachments extending from the stipe, sometimes along its full length, and are the sites of nutrient uptake and photosynthetic activity. +In addition, many kelp species have pneumatocysts, or gas-filled bladders, usually located at the base of fronds near the stipe. These structures provide the necessary buoyancy for kelp to maintain an upright position in the water column. +The environmental factors necessary for kelp to survive include hard substrate (usually rock), high nutrients (e.g., nitrogen, phosphorus), and light (minimum annual irradiance dose > 50 E m−2). Especially productive kelp forests tend to be associated with areas of significant oceanographic upwelling, a process that delivers cool nutrient-rich water from depth to the ocean's mixed surface layer. Water flow and turbulence facilitate nutrient assimilation across kelp fronds throughout the water column. Water clarity affects the depth to which sufficient light can be transmitted. In ideal conditions, giant kelp (Macrocystis spp.) can grow as much as 30-60 centimetres vertically per day. Some species such as Nereocystis are annual while others like Eisenia are perennial, living for more than 20 years. In perennial kelp forests, maximum growth rates occur during upwelling months (typically spring and summer) and die-backs correspond to reduced nutrient availability, shorter photoperiods and increased storm frequency. + +=== Seagrass meadows === + +Seagrasses are flowering plants from one of four plant families which grow in marine environments. They are called seagrasses because the leaves are long and narrow and are very often green, and because the plants often grow in large meadows which look like grassland. Since seagrasses photosynthesize and are submerged, they must grow submerged in the photic zone, where there is enough sunlight. For this reason, most occur in shallow and sheltered coastal waters anchored in sand or mud bottoms. +Seagrasses form extensive beds or meadows, which can be either monospecific (made up of one species) or multispecific (where more than one species co-exist). Seagrass beds make highly diverse and productive ecosystems. They are home to phyla such as juvenile and adult fish, epiphytic and free-living macroalgae and microalgae, mollusks, bristle worms, and nematodes. Few species were originally considered to feed directly on seagrass leaves (partly because of their low nutritional content), but scientific reviews and improved working methods have shown that seagrass herbivory is a highly important link in the food chain, with hundreds of species feeding on seagrasses worldwide, including green turtles, dugongs, manatees, fish, geese, swans, sea urchins and crabs. +Seagrasses are ecosystem engineers in the sense that they partly create their own habitat. The leaves slow down water-currents increasing sedimentation, and the seagrass roots and rhizomes stabilize the seabed. Their importance to associated species is mainly due to provision of shelter (through their three-dimensional structure in the water column), and due to their extraordinarily high rate of primary production. As a result, seagrasses provide coastal zones with ecosystem services, such as fishing grounds, wave protection, oxygen production and protection against coastal erosion. Seagrass meadows account for 15% of the ocean's total carbon storage. + +=== Reefs === + +A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes but there are also reefs such as the coral reefs of tropical waters formed by biotic processes dominated by corals and coralline algae. Artificial reefs such as shipwrecks and other anthropogenic underwater structures may occur intentionally or as the result of an accident, and sometimes have a designed role in enhancing the physical complexity of featureless sand bottoms, thereby attracting a more diverse assemblage of organisms. Reefs are often quite near to the surface, but not all definitions require this. Fringing reefs, the most common type of reef, are found close to shorelines and surrounding islands. + +==== Rocky reefs ==== + +Rocky reefs are underwater outcrops of rock projecting above the adjacent unconsolidated surface with varying relief. They can be found in depth ranges from intertidal to deep water and provide a substrate for a large range of sessile benthic organisms, and shelter for a large range of mobile organisms. + +==== Coral reefs ==== + +Coral reefs comprise some of the densest and most diverse habitats in the world. The best-known types of reefs are tropical coral reefs which exist in most tropical waters; however, coral reefs can also exist in cold water. Reefs are built up by corals and other calcium-depositing animals, usually on top of a rocky outcrop on the ocean floor. Reefs can also grow on other surfaces, which has made it possible to create artificial reefs. Coral reefs also support a huge community of life, including the corals themselves, their symbiotic zooxanthellae, tropical fish and many other organisms. +Much attention in marine biology is focused on coral reefs and the El Niño weather phenomenon. In 1998, coral reefs experienced the most severe mass bleaching events on record, when vast expanses of reefs across the world died because sea surface temperatures rose well above normal. Some reefs are recovering, but scientists say that between 50% and 70% of the world's coral reefs are now endangered and predict that global warming could exacerbate this trend. + +== Surface waters == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_habitat-5.md b/data/en.wikipedia.org/wiki/Marine_habitat-5.md new file mode 100644 index 000000000..1dac17a79 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_habitat-5.md @@ -0,0 +1,29 @@ +--- +title: "Marine habitat" +chunk: 6/8 +source: "https://en.wikipedia.org/wiki/Marine_habitat" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:24.136463+00:00" +instance: "kb-cron" +--- + +=== Surface microlayer === +The surface microlayer of the ocean serves as the transitional area between the atmosphere and the ocean. It covers around 70% of the Earth's surface as it covers most of the ocean waters on the planet. The microlayer is known for its unique biological and chemical properties which give it a small ecosystem of its own and serves as a distinct habitat from the deeper ocean waters. +The surface microlayer is not in fact entirely aqueous like the rest of the ocean, but is closer to a kind of hydrated gel composed of concentrated nutrients forming a biological film over the water it covers. This film is rich in microbes which mediate the interactions between the sun, the atmosphere, and the waters below. +Although thin, the surface microlayer is critical for life beneath it. Because of the environment rich in microbes and nutrients, larvae of fish and other aquatic animals are often laid in the microlayer to incubate. The plankton in the microlayer are distinctly adapted to withstand high levels of radiation, and serve as buffers to prevent this potentially harmful radiation from reaching the deeper water. Environmental changes such as aerosols or dust storms can cause these surface plankton to become overproductive, leading to blooms. + +Because of the unique properties of the microlayer, pollutants often accumulate within and use it to reach other parts of the ocean. Hydrophobic compounds, such as petroleum, flame retardants, and heavy metals, have a particular affinity for the surface microlayer. Recently, the abundance of aerosols and microplastics has also had an impact on the SML and their accumulation has led to many problems, such as animal ingestion of these compounds leading to widespread disruption of balance and spread of these compounds among marine communities. + +The surface microlayer is also critical to gas exchange between the atmosphere and the ocean. Because the microlayer is filled with microbes, it is widely theorized that it plays a critical role in gas exchange and uptake of nutrients, but relatively little data on this has been collected. The central feature of the microlayer is the temperature, as it is an indicator of how pollutants and human activity affects the ocean. + +=== Epipelagic zone === +The surface waters are sunlit. The waters down to about 200 metres are said to be in the epipelagic zone. Enough sunlight enters the epipelagic zone to allow photosynthesis by phytoplankton. The epipelagic zone is usually low in nutrients. This partially because the organic debris produced in the zone, such as excrement and dead animals, sink to the depths and are lost to the upper zone. Photosynthesis can happen only if both sunlight and nutrients are present. +In some places, like at the edge of continental shelves, nutrients can upwell from the ocean depth, or land runoff can be distributed by storms and ocean currents. In these areas, given that both sunlight and nutrients are now present, phytoplankton can rapidly establish itself, multiplying so fast that the water turns green from the chlorophyll, resulting in an algal bloom. These nutrient rich surface waters are among the most biologically productive in the world, supporting billions of tonnes of biomass. +"Phytoplankton are eaten by zooplankton - small animals which, like phytoplankton, drift in the ocean currents. The most abundant zooplankton species are copepods and krill: tiny crustaceans that are the most numerous animals on Earth. Other types of zooplankton include jelly fish and the larvae of fish, marine worms, starfish, and other marine organisms". In turn, the zooplankton are eaten by filter-feeding animals, including some seabirds, small forage fish like herrings and sardines, whale sharks, manta rays, and the largest animal in the world, the blue whale. Yet again, moving up the foodchain, the small forage fish are in turn eaten by larger predators, such as tuna, marlin, sharks, large squid, seabirds, dolphins, and toothed whales. + +== Open ocean == + +The open ocean is relatively unproductive because of a lack of nutrients, yet because it is so vast, it has more overall primary production than any other marine habitat. Only about 10 percent of marine species live in the open ocean. But among them are the largest and fastest of all marine animals, as well as the animals that dive the deepest and migrate the longest. In the depths lurk animal that, to our eyes, appear hugely alien. + +=== Deep sea === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_habitat-6.md b/data/en.wikipedia.org/wiki/Marine_habitat-6.md new file mode 100644 index 000000000..f6fd413da --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_habitat-6.md @@ -0,0 +1,34 @@ +--- +title: "Marine habitat" +chunk: 7/8 +source: "https://en.wikipedia.org/wiki/Marine_habitat" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:24.136463+00:00" +instance: "kb-cron" +--- + +The deep sea starts at the aphotic zone, the point where sunlight loses most of its energy in the water. Many life forms that live at these depths have the ability to create their own light a unique evolution known as bio-luminescence. +In the deep ocean, the waters extend far below the epipelagic zone, and support very different types of pelagic life forms adapted to living in these deeper zones. +Much of the aphotic zone's energy is supplied by the open ocean in the form of detritus. In deep water, marine snow is a continuous shower of mostly organic detritus falling from the upper layers of the water column. Its origin lies in activities within the productive photic zone. Marine snow includes dead or dying plankton, protists (diatoms), fecal matter, sand, soot and other inorganic dust. The "snowflakes" grow over time and may reach several centimetres in diameter, travelling for weeks before reaching the ocean floor. However, most organic components of marine snow are consumed by microbes, zooplankton and other filter-feeding animals within the first 1,000 metres of their journey, that is, within the epipelagic zone. In this way marine snow may be considered the foundation of deep-sea mesopelagic and benthic ecosystems: As sunlight cannot reach them, deep-sea organisms rely heavily on marine snow as an energy source. +Some deep-sea pelagic groups, such as the lanternfish, ridgehead, marine hatchetfish, and lightfish families are sometimes termed pseudoceanic because, rather than having an even distribution in open water, they occur in significantly higher abundances around structural oases, notably seamounts and over continental slopes. The phenomenon is explained by the likewise abundance of prey species which are also attracted to the structures. +The fish in the different pelagic and deep water benthic zones are physically structured, and behave in ways, that differ markedly from each other. Groups of coexisting species within each zone all seem to operate in similar ways, such as the small mesopelagic vertically migrating plankton-feeders, the bathypelagic anglerfishes, and the deep water benthic rattails. " + +Ray finned species, with spiny fins, are rare among deep sea fishes, which suggests that deep sea fish are ancient and so well adapted to their environment that invasions by more modern fishes have been unsuccessful. The few ray fins that do exist are mainly in the Beryciformes and Lampriformes, which are also ancient forms. Most deep sea pelagic fishes belong to their own orders, suggesting a long evolution in deep sea environments. In contrast, deep water benthic species, are in orders that include many related shallow water fishes. +The umbrella mouth gulper is a deep sea eel with an enormous loosely hinged mouth. It can open its mouth wide enough to swallow a fish much larger than itself, and then expand its stomach to accommodate its catch. + +== Sea floor == + +=== Vents and seeps === +Hydrothermal vents along the mid-ocean ridge spreading centers act as oases, as do their opposites, cold seeps. Such places support unique marine biomes and many new marine microorganisms and other lifeforms have been discovered at these locations. + +=== Trenches === +The deepest recorded oceanic trenches measure to date is the Mariana Trench, near the Philippines, in the Pacific Ocean at 10,924 m (35,838 ft). At such depths, water pressure is extreme and there is no sunlight, but some life still exists. A white flatfish, a shrimp and a jellyfish were seen by the American crew of the bathyscaphe Trieste when it dove to the bottom in 1960. + +=== Seamounts === +Marine life also flourishes around seamounts that rise from the depths, where fish and other sea life congregate to spawn and feed. + +== Anthropogenic impacts == + +Mudflats are typically important regions for wildlife, supporting a large population, although levels of biodiversity are not particularly high. They are of particular importance to migratory birds as well as crabs, shrimp, and shellfish. These areas along the coast act as a nursery for these animals by providing an area for reproduction and feeding. However, this can pose as an issue due to the high trafficking of the birds migrating for nesting, then leaving to return to their seasonal homes. Whatever pollutants the birds take in while breeding are brought back with them to their next location, thus polluting that area as well. In the United Kingdom mudflats have been classified as a Biodiversity Action Plan priority habitat. European countries such as France have also found it beneficial to use the Marine Influence Index (MII) to be able to monitor the responses to pollution the local plant and animal species may have as well as monitor any type of deviation from the natural patterns displayed previously. +Although many parts of the seafloor have yet to be explored, researchers have found that parts of it have been greatly affected by human activity. Bottom trawling, microplastic pollution, and industrial metals have slowly changed and altered the composition of the sea floor. Bottom trawling refers to a commercial deep sea fishing technique in which the equipment drags across the sea floor. This has had an adverse effect on the seafloor as it changes the surface structure and composition. In addition, microplastic pollution has become an increasing problem to the seafloor as plastics and other debris are found in many of the sediments. Due to the build up of litter, the habitats and environments of organisms on the seafloor are being impacted and changed. This includes industrial facilities dumping new metals and minerals, such as cadmium, onto the seafloor that change the chemical composition of the water and poison the inhabitants. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_habitat-7.md b/data/en.wikipedia.org/wiki/Marine_habitat-7.md new file mode 100644 index 000000000..c18a59073 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_habitat-7.md @@ -0,0 +1,32 @@ +--- +title: "Marine habitat" +chunk: 8/8 +source: "https://en.wikipedia.org/wiki/Marine_habitat" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:24.136463+00:00" +instance: "kb-cron" +--- + +There are also negative anthropogenic impacts on deep sea habitats, including trash pollution and chemical pollution. Plastic pollution in particular, is one of the greatest forms of uncontrolled human activity that is visible in our oceans today. Researchers in the Northwestern south China Sea recorded large plastic-dominated litter piles in submarine canyons. These durable plastics can diffuse into smaller organisms and are then inadvertently consumed by humans in the food we eat and water we drink. Another threat to organisms lurking in the deep ocean is ghost fishing, and bycatch. Ghost fishing is the term that refers to any abandoned fishing gear in the ocean that continues to entangle and trap marine organisms. Gill nets for example, have been recorded tangled around deep sea corals and continue ghost fishing for extended periods of time. + +== Gallery == + +== See also == + +Effects of climate change on oceans +Future of Marine Animal Populations +Maritime forest +Seashore wildlife +Underwater habitat (underwater habitats for humans) + +== References == + +=== Sources === +Kritzer JP; Sale PF (2006). Marine metapopulations. Academic Press. ISBN 978-0-12-088781-1. +Moyle, PB and Cech, JJ (2004) Fishes, An Introduction to Ichthyology. 5th Ed, Benjamin Cummings. ISBN 978-0-13-100847-2. +Nybakken JW; Bertness MD (2005) Marine biology: an ecological approach. Sixth edition. Pearson/Benjamin Cummings. ISBN 978-0-8053-4582-7 – organized by habitat, not classification +Pidwirny, Michael (2006). "Fundamentals of Physical Geography (2nd Edition)". PhysicalGeography.net. Retrieved 19 April 2011. + +== External links == +Missouri Botanical Garden: Marine ecosystems \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_pollution-0.md b/data/en.wikipedia.org/wiki/Marine_pollution-0.md new file mode 100644 index 000000000..72f449e9e --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_pollution-0.md @@ -0,0 +1,26 @@ +--- +title: "Marine pollution" +chunk: 1/7 +source: "https://en.wikipedia.org/wiki/Marine_pollution" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:11.497461+00:00" +instance: "kb-cron" +--- + +Marine pollution occurs when substances used or spread by humans, such as industrial, agricultural, and residential waste; particles; noise; excess carbon dioxide; or invasive organisms enter the ocean and cause harmful effects there. The majority of this waste (80%) comes from land-based activity, although marine transportation significantly contributes as well. It is a combination of chemicals and trash, most of which comes from land sources and is washed or blown into the ocean. This pollution results in damage to the environment, to the health of all organisms, and to economic structures worldwide. Since most inputs come from land, via rivers, sewage, or the atmosphere, it means that continental shelves are more vulnerable to pollution. Air pollution is also a contributing factor, as it carries iron, carbonic acid, nitrogen, silicon, sulfur, pesticides, and dust particles into the ocean. The pollution often comes from nonpoint sources such as agricultural runoff, wind-blown debris, and dust. These nonpoint sources are largely due to runoff that enters the ocean through rivers, but wind-blown debris and dust can also play a role, as these pollutants can settle into waterways and oceans. Pathways of pollution include direct discharge, land runoff, ship pollution, bilge pollution, dredging (which can create dredge plumes), atmospheric pollution and, potentially, deep sea mining. +Different types of marine pollution can be grouped as pollution from marine debris, plastic pollution, including microplastics, ocean acidification, nutrient pollution, toxins, and underwater noise. Plastic pollution in the ocean is a type of marine pollution by plastics, ranging in size from large original material such as bottles and bags, down to microplastics formed from the fragmentation of plastic materials. Marine debris is mainly discarded human rubbish which floats on, or is suspended in the ocean. Plastic pollution is harmful to marine life. +Another concern is the runoff of nutrients (nitrogen and phosphorus) from intensive agriculture, and the disposal of untreated or partially treated sewage to rivers and subsequently oceans. These nitrogen and phosphorus nutrients (which are also contained in fertilizers) stimulate phytoplankton and macroalgal growth, which can lead to harmful algal blooms (eutrophication) which can be harmful to humans as well as marine creatures. Excessive algal growth can also smother sensitive coral reefs and lead to loss of biodiversity and coral health. A second major concern is that the degradation of algal blooms can lead to consumption of oxygen in coastal waters, a situation that may worsen with climate change as warming reduces vertical mixing of the water column. +Many potentially toxic chemicals adhere to tiny particles which are then taken up by plankton and benthic animals, most of which are either deposit feeders or filter feeders. In this way, the toxins are concentrated upward within ocean food chains. When pesticides are incorporated into the marine ecosystem, they quickly become absorbed into marine food webs. Once in the food webs, these pesticides can cause mutations, as well as diseases, which can be harmful to humans as well as the entire food web. Toxic metals can also be introduced into marine food webs. These can cause a change to tissue matter, biochemistry, behavior, reproduction, and suppress growth in marine life. Also, many animal feeds have a high fish meal or fish hydrolysate content. In this way, marine toxins can be transferred to land animals, and appear later in meat and dairy products. + +== Pathways of pollution == + +There are many ways to categorize and examine the inputs of pollution into marine ecosystems. There are three main types of inputs of pollution into the ocean: direct discharge of waste into the oceans, runoff into the waters due to rain, and pollutants released from the atmosphere. +One common path of entry by contaminants to the sea are rivers. The evaporation of water from oceans exceeds precipitation. The balance is restored by rain over the continents entering rivers and then being returned to the sea. The Hudson River in New York State and the Raritan River in New Jersey, which empty at the northern and southern ends of Staten Island, are a source of mercury contamination of zooplankton (copepods) in the open ocean. The highest concentration in the filter-feeding copepods is not at the mouths of these rivers but 70 miles (110 km) south, nearer Atlantic City, because water flows close to the coast. It takes a few days before toxins are taken up by the plankton. Ohio River and Tennessee River both join Mississippi River ultimately drains organic contaminants from several northern states into the Gulf of Mexico. +Pollution is often classed as point source or nonpoint source pollution. Point source pollution occurs when there is a single, identifiable, localized source of the pollution. An example is directly discharging sewage and industrial waste into the ocean. Pollution such as this occurs particularly in developing nations. Nonpoint source pollution occurs when the pollution is from ill-defined and diffuse sources. These can be difficult to regulate. Agricultural runoff and wind blown debris are prime examples. + +=== Direct discharge === + +Pollutants enter rivers and the sea directly from urban sewerage and industrial waste discharges, sometimes in the form of hazardous and toxic wastes, or in the form of plastics. +In a study published by Science, Jambeck et al. (2015) estimated that the 10 largest emitters of oceanic plastic pollution worldwide are, from the most to the least, China, Indonesia, Philippines, Vietnam, Sri Lanka, Thailand, Egypt, Malaysia, Nigeria, and Bangladesh. +Inland mining for copper, gold, etc., is another source of marine pollution. Most of the pollution is simply soil, which ends up in rivers flowing to the sea. However, some minerals discharged in the course of the mining can cause problems, such as copper, a common industrial pollutant, which can interfere with the life history and development of coral polyps. Mining has a poor environmental track record. For example, according to the United States Environmental Protection Agency, mining has contaminated portions of the headwaters of over 40% of watersheds in the western continental US. Much of this pollution ends up in the sea. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_pollution-1.md b/data/en.wikipedia.org/wiki/Marine_pollution-1.md new file mode 100644 index 000000000..94e860764 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_pollution-1.md @@ -0,0 +1,29 @@ +--- +title: "Marine pollution" +chunk: 2/7 +source: "https://en.wikipedia.org/wiki/Marine_pollution" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:11.497461+00:00" +instance: "kb-cron" +--- + +=== Land runoff === + +Surface runoff from farming, as well as urban runoff and runoff from the construction of roads, buildings, ports, channels, and harbours, can carry soil and particles laden with carbon, nitrogen, phosphorus, and minerals. This nutrient-rich water can cause fleshy algae and phytoplankton to thrive in coastal areas; known as algal blooms, which have the potential to create hypoxic conditions by using all available oxygen. In the coast of southwest Florida, harmful algal blooms have existed for over 100 years. These algal blooms have been a cause of species of fish, turtles, dolphins, and shrimp to die and cause harmful effects on humans who swim in the water. +Polluted runoff from roads and highways can be a significant source of water pollution in coastal areas. About 75% of the toxic chemicals that flow into Puget Sound are carried by stormwater that runs off paved roads and driveways, rooftops, yards and other developed land. In California, there are many rainstorms that runoff into the ocean. These rainstorms occur from October to March, and these runoff waters contain petroleum, heavy metals, pollutants from emissions, etc. +In China, there is a large coastal population that pollutes the ocean through land runoff. This includes sewage discharge and pollution from urbanization and land use. In 2001, more than 66,795 mi2 of the Chinese coastal ocean waters were rated less than Class I of the Sea Water Quality Standard of China. Much of this pollution came from Ag, Cu, Cd, Pb, As, DDT, PCBs, etc., which occurred from contamination through land runoff. + +=== Ship pollution === + +Ships can pollute waterways and oceans in many ways including through their ballast, bilge, and fuel tanks. Oil spills can have devastating effects. In addition to being toxic to marine life, polycyclic aromatic hydrocarbons (PAHs), found in crude oil, are very difficult to clean up, and last for years in the sediment and marine environment. Additionally, bilge pollution can be toxic to the surrounding environment when bilge water is released from a ship's bilge. +Oil spills are one of the most emotive of marine pollution events. However, while a tanker wreck may result in extensive newspaper headlines, much of the oil in the world's seas comes from other smaller sources, such as tankers discharging ballast water from oil tanks used on return ships, leaking pipelines or engine oil disposed of down sewers. +Discharge of cargo residues from bulk carriers can pollute ports, waterways, and oceans. In many instances vessels intentionally discharge illegal wastes despite foreign and domestic regulation prohibiting such actions. An absence of national standards provides an incentive for some cruise liners to dump waste in places where the penalties are inadequate. It has been estimated that container ships lose over 10,000 containers at sea each year (usually during storms). Ships also create noise pollution that disturbs natural wildlife, and water from ballast tanks can spread harmful algae and other invasive species. +Ballast water taken up at sea and released in port is a major source of unwanted exotic marine life. The invasive freshwater zebra mussels, native to the Black, Caspian, and Azov seas, were probably transported to the Great Lakes via ballast water from a transoceanic vessel. Meinesz believes that one of the worst cases of a single invasive species causing harm to an ecosystem can be attributed to a seemingly harmless jellyfish. Mnemiopsis leidyi, a species of comb jellyfish that spread so it now inhabits estuaries in many parts of the world, was first introduced in 1982, and thought to have been transported to the Black Sea in a ship's ballast water. The population of the jellyfish grew exponentially and, by 1988, it was wreaking havoc upon the local fishing industry. "The anchovy catch fell from 204,000 tons in 1984 to 200 tons in 1993; sprat from 24,600 tons in 1984 to 12,000 tons in 1993; horse mackerel from 4,000 tons in 1984 to zero in 1993." Now that the jellyfish have exhausted the zooplankton, including fish larvae, their numbers have fallen dramatically, yet they continue to maintain a stranglehold on the ecosystem. +Invasive species can take over once occupied areas, facilitate the spread of new diseases, introduce new genetic material, alter underwater seascapes, and jeopardize the ability of native species to obtain food. Invasive species are responsible for about $138 billion annually in lost revenue and management costs in the US alone. + +=== Atmospheric pollution === + +Another pathway of pollution occurs through the atmosphere. The ocean has long been affected by the passage of chemicals from the atmosphere (e.g. nutrient source; pH influence). Wind-blown dust and debris, including plastic bags, are blown seaward from landfills and other areas. Dust from the Sahara moving around the southern periphery of the subtropical ridge moves into the Caribbean and Florida during the warm season as the ridge builds and moves northward through the subtropical Atlantic. Dust can also be attributed to a global transport from the Gobi and Taklamakan deserts across Korea, Japan, and the Northern Pacific to the Hawaiian Islands. +Since 1970, dust outbreaks have worsened due to periods of drought in Africa. There is a large variability in dust transport to the Caribbean and Florida from year to year; however, the flux is greater during positive phases of the North Atlantic Oscillation. The USGS links dust events to a decline in the health of coral reefs across the Caribbean and Florida, primarily since the 1970s. +Climate change is raising ocean temperatures and raising levels of carbon dioxide in the atmosphere. These rising levels of carbon dioxide are acidifying the oceans. This, in turn, is altering aquatic ecosystems and modifying fish distributions, with impacts on the sustainability of fisheries and the livelihoods of the communities that depend on them. Healthy ocean ecosystems are also important for the mitigation of climate change. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_pollution-2.md b/data/en.wikipedia.org/wiki/Marine_pollution-2.md new file mode 100644 index 000000000..09216e538 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_pollution-2.md @@ -0,0 +1,31 @@ +--- +title: "Marine pollution" +chunk: 3/7 +source: "https://en.wikipedia.org/wiki/Marine_pollution" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:11.497461+00:00" +instance: "kb-cron" +--- + +=== Deep sea mining === +Some of the potential toxic metals include copper, zinc, cadmium, lead as well as rare earth elements such as lanthanum and yttrium. Following the release of toxins there is an increase of noise, light, sediment le dan plumes and elements that have the potential to impact the ecosystems. +Deep sea minerals (DSM) can be extremely beneficial, it can cause wealth, raising living standards as well as economic opportunities for both current and future generations. In addition, if the wealth is poorly managed it can have the potential to cause great economic and social damage. The instability of price and production levels of minerals can cause an external economic shock leading to a significant backlash on the domestic economy. + +== Types of pollution == + +=== Marine debris pollution === + +=== Plastic pollution === + +=== Ocean acidification === + +=== Nutrient pollution === + +Eutrophication is an increase in chemical nutrients, typically compounds containing nitrogen or phosphorus, in an ecosystem. It can result in an increase in the ecosystem's primary productivity (excessive plant growth and decay), and further effects including lack of oxygen and severe reductions in water quality, fish, and other animal populations. Nutrient pollution, a form of water pollution, refers to contamination by excessive inputs of nutrients. It is a primary cause of eutrophication of surface waters, in which excess nutrients, usually nitrates or phosphates, stimulate algae growth. Such blooms are naturally occurring but may be increasing as a result of anthropogenic inputs or alternatively may be something that is now more closely monitored and so more frequently reported. +The biggest culprit are rivers that empty into the ocean, and with it the many chemicals used as fertilizers in agriculture as well as waste from livestock and humans. An excess of oxygen-depleting chemicals in the water can lead to hypoxia and the creation of a dead zone. +Estuaries tend to be naturally eutrophic because land-derived nutrients are concentrated where runoff enters the marine environment in a confined channel. The World Resources Institute has identified 375 hypoxic coastal zones around the world, concentrated in coastal areas in Western Europe, the Eastern and Southern coasts of the US, and East Asia, particularly in Japan. In the ocean, there are frequent red tide algae blooms that kill fish and marine mammals and cause respiratory problems in humans and some domestic animals when the blooms reach close to shore. +In addition to land runoff, atmospheric anthropogenic fixed nitrogen can enter the open ocean. A study in 2008 found that this could account for around one third of the ocean's external (non-recycled) nitrogen supply and up to three per cent of the annual new marine biological production. It has been suggested that accumulating reactive nitrogen in the environment may have consequences as serious as putting carbon dioxide in the atmosphere. +One proposed solution to eutrophication in estuaries is to restore shellfish populations, such as oysters. Oyster reefs remove nitrogen from the water column and filter out suspended solids, subsequently reducing the likelihood or extent of harmful algal blooms or anoxic conditions. Filter feeding activity is considered beneficial to water quality by controlling phytoplankton density and sequestering nutrients, which can be removed from the system through shellfish harvest, buried in the sediments, or lost through denitrification. Foundational work toward the idea of improving marine water quality through shellfish cultivation to was conducted by Odd Lindahl et al., using mussels in Sweden. + +=== Industrial pollution and toxic chemicals === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_pollution-3.md b/data/en.wikipedia.org/wiki/Marine_pollution-3.md new file mode 100644 index 000000000..2c0f62293 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_pollution-3.md @@ -0,0 +1,29 @@ +--- +title: "Marine pollution" +chunk: 4/7 +source: "https://en.wikipedia.org/wiki/Marine_pollution" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:11.497461+00:00" +instance: "kb-cron" +--- + +Apart from plastics, there are particular problems with other toxic pollutants that either do not break down or only very slowly in the marine environment. Examples of persistent toxicants are PCBs, DDT, TBT, pesticides, furans, dioxins, phenols, radioactive waste, and PFAS. Heavy metals are metallic chemical elements that have a relatively high density and are toxic or poisonous at low concentrations. Examples are mercury, lead, copper and cadmium. Some toxicants can accumulate in the tissues of many species of aquatic life in a process called bioaccumulation. They are also known to accumulate in benthic environments, such as estuaries and bay muds: a geological record of human activities of the last century. +DDT is a very toxic chemical that was used as a pesticide in mass quantities throughout the United States and is known to be neurotoxic, a reproductive toxin, an endocrine disruptor, and a carcinogen. DDT is a major focus of the book Silent Spring published by Rachel Carson in 1962. This is often attributed to launching the modern environmental movement and setting the stage for the creation of the EPA in 1970. DDT was banned in the U.S. two years later in 1972. Unfortunately, large quantities had already entered the ocean through runoff and had been dumped directly into the ocean. This toxin impacts marine ecosystems by accumulating from lower trophic levels and up the food chain into higher trophic levels such as from arctic cod into seals, from fish then eaten by dolphins, and from cod and eels into seals. +Shortly after Rachel Carson's publication of Silent Spring, PCBs were identified as another persistent, toxic chemical that has been released in extensive quantities to the environment. PCBs are a very well-studied class of chemicals that are manufactured from oil. These chemicals are banned in the United States under the Toxic Substance Control Act, but are still found in the soil, air, sediments, and biota. PCBs are known to accumulate in the fatty tissues of animals. In particular, PCBs build up and are stored in the blubber of marine mammals including dolphins and killer whales. These chemicals cause reproductive issues for many species. In mud crabs, PCBs have been discovered to be immunotoxic by reducing resistance to bacterial disease, reducing antioxidant enzyme activity, and damaging DNA responsible for immune system functions. +PFAS are an important emerging class of man-made persistent toxicants that contain extremely strong carbon-fluorine bonds which make these chemicals extremely difficult to break down. They have unique properties that make them useful for manufacturing a wide variety of products such as firefighting foams, clothing, carpets, and fast food wrappers. These useful properties in manufacturing unfortunately translate to problematic properties in the environment and organisms from plants to people. Because PFAS are not broken down in the environment, they have been circulated through the air and water to essentially all regions of the atmosphere, land, and ocean. These chemicals have many negative effects on marine life, such as significantly inhibited growth of phytoplankton over time and accumulation in seals, polar bears, and dolphins. Current research is underway investigating the full extent of the harm to marine ecosystems caused by PFAS. + +Specific examples + +Chinese and Russian industrial pollution such as phenols and heavy metals in the Amur River have devastated fish stocks and damaged its estuary soil. +Acute and chronic pollution events have been shown to impact southern California kelp forests, though the intensity of the impact seems to depend on both the nature of the contaminants and duration of exposure. +Due to their high position in the food chain and the subsequent accumulation of heavy metals from their diet, mercury levels can be high in larger species such as bluefin and albacore. As a result, in March 2004 the United States FDA issued guidelines recommending that pregnant women, nursing mothers and children limit their intake of tuna and other types of predatory fish. +Some shellfish and crabs can survive polluted environments, accumulating heavy metals or toxins in their tissues. For example, mitten crabs have a remarkable ability to survive in highly modified aquatic habitats, including polluted waters. The farming and harvesting of such species needs careful management if they are to be used as a food. +Surface runoff of pesticides can alter the gender of fish species genetically, transforming male into female fish. +Heavy metals enter the environment through oil spills – such as the Prestige oil spill on the Galician coast and Gulf of Mexico which unleashed an estimated 3.19 million barrels of oil – or from other natural or anthropogenic sources. +In 2005, the 'Ndrangheta, an Italian mafia syndicate, was accused of sinking at least 30 ships loaded with toxic waste, much of it radioactive. This has led to widespread investigations into radioactive waste disposal rackets. +Since the end of World War II, various nations, including the Soviet Union, the United Kingdom, the United States, and Germany, have disposed of chemical weapons in the Baltic Sea, raising concerns of environmental contamination. +The Fukushima Daiichi nuclear disaster in 2011 caused radioactive toxins from the damaged power plant to leak into the air and ocean. There are still many isotopes in the ocean, which directly affects the benthic food web and also affects the whole food chain. The concentration of 137Cs in the bottom sediment that was contaminated by water with high concentrations in April–May 2011 remains quite high and is showing signs of very slow decrease with time. +During the 20th century, large amounts of DDT, petroleum products, radioactive materials, sulphuric acid, and other toxins were dumped in the Pacific Ocean off the coast of Southern California. + +=== Underwater noise === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_pollution-4.md b/data/en.wikipedia.org/wiki/Marine_pollution-4.md new file mode 100644 index 000000000..593d636fe --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_pollution-4.md @@ -0,0 +1,19 @@ +--- +title: "Marine pollution" +chunk: 5/7 +source: "https://en.wikipedia.org/wiki/Marine_pollution" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:11.497461+00:00" +instance: "kb-cron" +--- + +Marine life can be susceptible to noise or the sound pollution from sources such as passing ships, oil exploration seismic surveys, and naval low-frequency active sonar. Sound travels more rapidly and over larger distances in the sea than in the atmosphere. Between 1950 and 1975, ambient noise at one location in the Pacific Ocean increased by about ten decibels (that is a tenfold increase in intensity). Underwater noise pollution is unevenly distributed across marine environments, with the highest con-centrations occurring in shipping lanes, port areas, and densely trafficked ocean routes. These areas experience sustained high ambient noise levels due to the dominance of older and larger vessels, which emit significant low-frequency noise (10 to 500 Hz) caused by engine vibrations, propeller cavitation, and hull turbulence. While advancements in ship design have shown potential to reduce noise emissions, older, noisier vessels remain prevalent in major shipping routes, largely due to economic and logistical constraints. Additionally, the overall increase in global shipping activity in the 20th century contributed to a rise of approximately 12 decibels in ambient noise levels in the Northern Hemisphere, particularly in the low-frequency range, which propagates over long distances with minimal attenuation. Studies in the Southern Hemisphere do not show a continuation of this trend in the 21st century. The cumulative effects of concentrated noise pollution pose a unique risk to localised ecosystems, particularly for species with limited mobility or specific habitat requirements, as they are unable to escape these high-noise regions. Research also highlights variations in noise behaviour across marine environments, with factors such as water depth, salinity, and seabed composition influencing how noise propagates in coastal areas versus open seas. The localised nature of underwater noise pollution amplifies its ecological consequences, particularly for species that rely on sound for survival. +The ecological impacts of underwater noise are most prevalent for marine mammals like whales and dolphins, which rely heavily on sound for communication, navigation, and foraging. Cetaceans, such as whales and dolphins, are especially vulnerable because they rely on echolocation and acoustic signals for communication and navigation. They experience disrupted communication patterns, altered migration routes, and stress-related behavioural changes as some of the consequences of chronic exposure to ship noise. For example, endangered whale populations in the Saguenay–St. Lawrence Marine Park experience considerable acoustic space reduction, limiting their communication ranges and altering their natural behaviours. Studies have shown that underwater noise can reduce communication ranges, impairing essential behaviours such as mating and social cohesion. Beyond marine mammals, fish and invertebrates are also affected, though they are less frequently studied. Fish use acoustic signals for mating, predator avoidance, and territory defence. Noise interference can cause habitat avoidance, reduced reproductive success, and disrupted predator-prey relationships, destabilising local food webs. These cumulative effects of URN contribute to the destabilisation of nutrient cycling and broader eco-system processes. +Noise also makes species communicate louder, which is called the Lombard vocal response. Whale songs are longer when submarine-detectors are on. If creatures don't "speak" loud enough, their voice can be masked by anthropogenic sounds. These unheard voices might be warnings, finding of prey, or preparations of net-bubbling. When one species begins speaking louder, it will mask other species voices, causing the whole ecosystem to eventually speak louder. Noise from ships and human activity can damage Cnidarians and Ctenophora, which are very important organisms in the marine ecosystem. They promote high diversity and they are used as models for ecology and biology because of their simple structures. When there is underwater noise, the vibrations in the water damage the cilia hairs in the Coelenterates. In a study, the organisms were exposed to sound waves for different numbers of times and the results showed that damaged hair cells were extruded or missing or presented bent, flaccid or missed kinocilia and stereocilia. Ships can be certified to meet certain noise criteria. +According to the oceanographer Sylvia Earle, "Undersea noise pollution is like the death of a thousand cuts. Each sound in itself may not be a matter of critical concern, but taken all together, the noise from shipping, seismic surveys, and military activity is creating a totally different environment than existed even 50 years ago. That high level of noise is bound to have a hard, sweeping impact on life in the sea." +Sources of noise below 100 Hz in the ocean include ships and airgun arrays. Other sources of ocean ambient sound in the same frequency range include earthquakes, volcanic eruptions, baleen whale calls, ice calving and winter storms. +Efforts to address underwater noise pollution remain limited. The International Maritime Organisation (IMO) introduced voluntary guidelines in 2014, encouraging measures such as the adoption of quieter ship designs, optimized propellers, and improved hull forms to reduce noise emissions. However, the non-mandatory nature of these guidelines has resulted in inconsistent adoption across the shipping industry. In contrast, the European Union's Marine Strategy Framework Directive (MSFD) mandates the management of underwater noise levels as part of achieving or maintaining Good Environmental Status (GES). Scholars argue that a combination of technical and economic measures is needed to tackle the issue effectively. These include mandatory noise limits, subsidies for retrofitting ships with quieter technologies, and spatially informed policies, such as the creation of quiet zones or Marine Protected Areas (MPAs), to safeguard sensitive ecosystems. + +=== Other === +There are a variety of secondary effects stemming not from the original pollutant, but a derivative condition. An example is silt-bearing surface runoff, which can inhibit the penetration of sunlight through the water column, hampering photosynthesis in aquatic plants. Dredge plumes can contain silt and thus have similar effects on aquatic life. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_pollution-5.md b/data/en.wikipedia.org/wiki/Marine_pollution-5.md new file mode 100644 index 000000000..679462268 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_pollution-5.md @@ -0,0 +1,31 @@ +--- +title: "Marine pollution" +chunk: 6/7 +source: "https://en.wikipedia.org/wiki/Marine_pollution" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:11.497461+00:00" +instance: "kb-cron" +--- + +== Mitigation == +Much anthropogenic pollution ends up in the ocean. The 2011 edition of the United Nations Environment Programme Year Book identifies as the main emerging environmental issues the loss to the oceans of massive amounts of phosphorus, "a valuable fertilizer needed to feed a growing global population", and the impact billions of pieces of plastic waste are having globally on the health of marine environments. +Bjorn Jennssen (2003) notes in his article, "Anthropogenic pollution may reduce biodiversity and productivity of marine ecosystems, resulting in reduction and depletion of human marine food resources". There are two ways the overall level of this pollution can be mitigated: either the human population is reduced, or a way is found to reduce the ecological footprint left behind by the average human. If the second way is not adopted, then the first way may be imposed as the world ecosystems falter. +The second way is for humans, individually, to pollute less. That requires social and political will, together with a shift in awareness so more people respect the environment and are less disposed to abuse it. At an operational level, regulations, and international government participation is needed. It is often very difficult to regulate marine pollution because pollution spreads over international barriers, thus making regulations hard to create as well as enforce. +Without appropriate awareness of marine pollution, the necessary global will to effectively address the issues may prove inadequate. Balanced information on the sources and harmful effects of marine pollution need to become part of general public awareness, and ongoing research is required to fully establish, and keep current, the scope of the issues. As expressed in Daoji and Dag's research, one of the reasons why environmental concern is lacking among the Chinese is because the public awareness is low and therefore should be targeted. + +The amount of awareness on marine pollution is vital to the support of keeping the prevention of trash from entering waterways and ending up in our oceans. The EPA reports that in 2014 Americans generated about 258 million tons of waste, and only a third was recycled or composted. In 2015, there was over 8 million tons of plastic that made it into the ocean. The Ocean Conservancy reported that China, Indonesia, Philippines, Thailand, and Vietnam dump more plastic in the sea than all other countries combined. Through more sustainable packing this could lead to; eliminating toxic constituents, using fewer materials, making more readily available recyclable plastic. However, awareness can only take these initiatives so far. The most abundant plastic is PET (Polyethylene terephthalate) and is the most resistant to biodegradables. Researchers have been making great strides in combating this problem. In one way has been by adding a special polymer called a tetrablock copolymer. The tetrablock copolymer acts as a laminate between the PE and iPP which enables for an easier breakdown but still be tough. Through more awareness, individuals will become more cognizant of their carbon footprints. Also, from research and technology, more strides can be made to aid in the plastic pollution problem.Jellyfish have been considered a potential mitigating organism for pollution. + +=== Global goals === +In 2017, the United Nations adopted a resolution establishing Sustainable Development Goals, including reduced marine pollution as a measured goal under Goal 14. The international community has agreed that reducing pollution in the oceans is a priority, which is tracked as part of Sustainable Development Goal 14 which actively seeks to undo these human impacts on the oceans. The title of Target 14.1 is: "By 2025, prevent and significantly reduce marine pollution of all kinds, in particular from land-based activities, including marine debris and nutrient pollution." + +== History == + +Although marine pollution has a long history, significant international laws to counter it were not enacted until the twentieth century. Marine pollution was a concern during several United Nations Conventions on the Law of the Sea beginning in the 1950s. Most scientists believed that the oceans were so vast that they had unlimited ability to dilute, and thus render pollution harmless. +In the late 1950s and early 1960s, there were several controversies about dumping radioactive waste off the coasts of the United States by companies licensed by the Atomic Energy Commission, into the Irish Sea from the British reprocessing facility at Windscale, and into the Mediterranean Sea by the French Commissariat à l'Energie Atomique. After the Mediterranean Sea controversy, for example, Jacques Cousteau became a worldwide figure in the campaign to stop marine pollution. Marine pollution made further international headlines after the 1967 crash of the oil tanker Torrey Canyon, and after the 1969 Santa Barbara oil spill off the coast of California. +Marine pollution was a major area of discussion during the 1972 United Nations Conference on the Human Environment, held in Stockholm. That year also saw the signing of the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, sometimes called the London Convention. The London Convention did not ban marine pollution, but it established black and gray lists for substances to be banned (black) or regulated by national authorities (gray). Cyanide and high-level radioactive waste, for example, were put on the black list. The London Convention applied only to waste dumped from ships, and thus did nothing to regulate waste discharged as liquids from pipelines. + +== Society and culture == + +=== Laws and policies === +There are different ways for the ocean to get polluted, therefore there have been multiple laws, policies, and treaties put into place throughout history. In order to protect the ocean from marine pollution, policies have been developed internationally. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_pollution-6.md b/data/en.wikipedia.org/wiki/Marine_pollution-6.md new file mode 100644 index 000000000..632519e15 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_pollution-6.md @@ -0,0 +1,26 @@ +--- +title: "Marine pollution" +chunk: 7/7 +source: "https://en.wikipedia.org/wiki/Marine_pollution" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:11.497461+00:00" +instance: "kb-cron" +--- + +In 1948, Harry Truman signed a law formerly known as the Federal Water Pollution Control Act that allowed the federal government to control marine pollution in United States of America. +In 1972, the Marine Protection, Research, and Sanctuaries Act of 1972 (MPRSA) was passed by the United States Congress, and regulates ocean dumping of waste in US waters. +The 1954 Convention for the Prevention of Pollution of the Sea by Oil and the 1973 International Convention for the Prevention of Pollution by Ships were weakly enforced due to a lack of respect for the laws from flag states. +In 1973 and 1978, MARPOL 73/78 was a treaty written to control vessel pollution, especially regarding oil. In 1983, the International Convention for the Prevention of Pollution from Ships enforced the MARPOL 73/78 treaty internationally. +The 1982 United Nations Convention on the Law of the Sea (UNCLOS) was established to protect the marine environment by governing states to control their pollution to the ocean. It put restrictions on the amount of toxins and pollutants that come from all ships internationally. +In 2006, the Marine Debris Research, Prevention and Reduction Ac. It was established by the National Oceanic and Atmospheric Administration (NOAA) to help identify, determine the source of, reduce and prevent marine debris. +In December 2017, the UN Environmental Agency (UNEA) established the Ad Hoc Open-Ended Expert Group on Marine Litter and Microplastics with the purpose of examining marine plastic pollutions and to evaluate ways to handle the issue. +In August 2023, the International Maritime Organization introduced Revised guidelines for the reduction of underwater radiated noise from shipping to address adverse impacts on marine life containing provisions to help limit the noise resulting from the ships, to ensure the impact of noise on the marine life is addressed. + +== See also == + +== References == + +== External links == +UN Ocean Decade +US NOAA Marine Debris Program \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_regression-0.md b/data/en.wikipedia.org/wiki/Marine_regression-0.md new file mode 100644 index 000000000..1bc8a6b09 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_regression-0.md @@ -0,0 +1,33 @@ +--- +title: "Marine regression" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Marine_regression" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:32.922810+00:00" +instance: "kb-cron" +--- + +A marine regression is a geological process occurring when areas of submerged seafloor are exposed during a drop in sea level. The opposite event, marine transgression, occurs when flooding from the sea covers previously-exposed land. + + +== Description == +According to one hypothesis, regressions may be linked to a "slowdown in sea-floor spreading, leading to a generalized drop in sea level (as the mid-ocean ridges would take up less space)...." That view considers major marine regressions to be one aspect of a normal variation in rates of plate tectonic activity, which leads to major episodes of global volcanism like the Siberian Traps and the Deccan Traps, which in turn cause large extinction events. +Evidence of marine regressions and transgressions occurs throughout the fossil record, and the fluctuations are thought to have caused or contributed to several mass extinctions, such as the Permian–Triassic extinction event (250 million years ago, Ma) and Cretaceous–Paleogene extinction event (66 Ma). During the Permian-Triassic extinction, the largest extinction event in the Earth's history, the global sea level fell 250 m (820 ft). +A major regression could cause marine organisms in shallow seas to go extinct, but mass extinctions tend to involve both terrestrial and aquatic species, and it is harder to see how a marine regression could cause widespread extinctions of land animals. Regressions are, therefore, seen as correlates or symptoms of major extinctions, rather than primary causes. The Permian regression might have been related to the formation of Pangaea. The accumulation of all major landmasses into one body could have facilitated a regression by providing "a slight enlargement of the ocean basins as the great continents coalesced." However, that cause could not have applied in all or even many of the other cases. + + +== Ice ages == +During the ice ages of the Pleistocene, a clear correlation existed between marine regressions and episodes of glaciation. As the balance shifts between the global cryosphere and hydrosphere, more of the planet's water in ice sheets means less in the oceans. At the height of the last ice age, around 18,000 years ago, the global sea level was 120 to 130 m (390-425 ft) lower than today. A cold spell around 6 million years ago was linked to an advance in glaciation, a marine regression, and the start of the Messinian salinity crisis in the Mediterranean basin. Some major regressions of the past, however, seem unrelated to glaciation episodes, with the regression that accompanied the mass extinction at the end of the Cretaceous being one example. + + +== See also == +8.2-kiloyear event – Rapid global cooling about 8,200 years ago +Marine terrace – Emergent coastal landform + + +== References == + + +== External links == +Marine Transgression and Marine Regression: World of Earth Science \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_snow-0.md b/data/en.wikipedia.org/wiki/Marine_snow-0.md new file mode 100644 index 000000000..4656524e6 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_snow-0.md @@ -0,0 +1,35 @@ +--- +title: "Marine snow" +chunk: 1/2 +source: "https://en.wikipedia.org/wiki/Marine_snow" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:34.238748+00:00" +instance: "kb-cron" +--- + +In the deep ocean, marine snow is a continuous shower of mostly organic detritus falling from the upper layers of the water column. It is a significant means of exporting energy from the light-rich photic zone to the aphotic zone below, which is referred to as the biological pump. Export production is the amount of organic matter produced in the ocean by primary production that is not recycled (remineralised) before it sinks into the aphotic zone. Because of the role of export production in the ocean's biological pump, it is typically measured in units of carbon (e.g. mg C m−2 d−1). The term was coined by explorer William Beebe as observed from his bathysphere. As the origin of marine snow lies in activities within the productive photic zone, the prevalence of marine snow changes with seasonal fluctuations in photosynthetic activity and ocean currents. Marine snow can be an important food source for organisms living in the aphotic zone, particularly for organisms that live very deep in the water column. + +== Composition == + +Marine snow is made up of a variety of mostly organic matter, including dead or dying animals and phytoplankton, protists, fecal matter, sand, and other inorganic dust. Most trapped particles are more vulnerable to grazers than they would be as free-floating individuals. Aggregates can form through abiotic processes (i.e. extrapolymeric substances). These are natural polymers exuded as waste products mostly by phytoplankton and bacteria. Mucus secreted by zooplankton (mostly salps, appendicularians, and pteropods) also contributes to the constituents of marine snow aggregates. These aggregates grow over time and may reach several centimeters in diameter, traveling for weeks before reaching the ocean floor. +Marine snow often forms during algal blooms. As phytoplankton accumulate, they aggregate or get captured in other aggregates, both of which accelerate the sinking rate. Aggregation and sinking is actually thought to be a large component of sources for algae loss from surface water. Most organic components of marine snow are consumed by microbes, zooplankton and other filter-feeding animals within the first 1,000 metres of their journey. In this way marine snow may be considered the foundation of deep-sea mesopelagic and benthic ecosystems: As sunlight cannot reach them, deep-sea organisms rely heavily on marine snow as an energy source. The small percentage of material not consumed in shallower waters becomes incorporated into the muddy "ooze" blanketing the ocean floor, where it is further decomposed through biological activity. +Marine snow aggregates exhibit characteristics that fit Goldman's "aggregate spinning wheel hypothesis". This hypothesis states that phytoplankton, microorganisms and bacteria live attached to aggregate surfaces and are involved in rapid nutrient recycling. Phytoplankton have been shown to be able to take up nutrients from small local concentrations of organic material (e.g. fecal matter from an individual zooplankton cell, regenerated nutrients from organic decomposition by bacteria). As the aggregates slowly sink to the bottom of the ocean, the many microorganisms residing on them are constantly respiring and contribute greatly to the microbial loop. + +== Aggregate dynamics == +Aggregates begin as the colloidal fraction, which typically contains particles sized between one nanometer and several micrometers. The colloidal fraction of the ocean contains a large amount of organic matter unavailable to grazers. This fraction has a much higher total mass than either phytoplankton or bacteria but is not readily available due to size characteristics of the particles in relation to potential consumers. The colloidal fraction must aggregate in order to be more bioavailable. + +=== Ballasting effect === + +Aggregates that sink more quickly to the bottom of the ocean have a greater chance of exporting carbon to the deep sea floor. The longer the residence time in the water column the greater the chance of being grazed upon. Aggregates formed in high dust areas are able to increase their densities faster and in more superficial layers compared to aggregates formed without dust particles present and these aggregates with increased lithogenic material have also been correlated with particulate organic carbon fluxes, however when they become heavily ballasted with lithogenic material they cannot scavenge any additional minerals during their descent, which suggests that carbon export to the deep ocean in regions with high dust deposition is strongly controlled by dust input to the surface ocean while suspended dust particles in deeper water layers do not significantly interact with sinking aggregates. + +=== Fragmentation === +Once particles have aggregated to several micrometers in diameter, they begin to accumulate bacteria, since there is sufficient site space for feeding and reproduction. At this size, it is large enough to undergo sinking. It also has the components necessary to fit the "aggregate spinning wheel hypothesis". Evidence for this has been found by Alldredge and Cohen (1987) who found evidence of both respiration and photosynthesis within aggregates, suggesting the presence of both autotrophic and heterotrophic organisms. During zooplankton's vertical migration, the abundances of aggregates increased while size distributions decreased. Aggregates were found in the abdomen in zooplankton indicating their grazing will fragment larger aggregates. + +=== Surface coagulation === +Aggregates may also form from colloids trapped on the surface of rising bubbles. For example, Kepkay et al. found that bubble coagulation leads to an increase in bacterial respiration since more food is available to them. + +=== Filtration === +Particles and small organisms floating through the water column can become trapped within aggregates. Marine snow aggregates are porous, however, and some particles are able to pass through them. + +== Particle-associated microorganisms == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Marine_snow-1.md b/data/en.wikipedia.org/wiki/Marine_snow-1.md new file mode 100644 index 000000000..19a93ac3a --- /dev/null +++ b/data/en.wikipedia.org/wiki/Marine_snow-1.md @@ -0,0 +1,53 @@ +--- +title: "Marine snow" +chunk: 2/2 +source: "https://en.wikipedia.org/wiki/Marine_snow" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:34.238748+00:00" +instance: "kb-cron" +--- + +Planktonic prokaryotes are further defined into two categories, free-living or particle associated. The two are separated by filtration. Particle-associated bacteria are often difficult to study because marine snow aggregates are often ranging in sizes from 0.2 to 200 μm, often rendering sampling efforts difficult. These aggregates are hotspots for microbial activity. Marine bacteria are the most abundant organisms in aggregates followed by cyanobacteria and then nanoflagellates. Aggregates can be enriched about one thousand times more than the surrounding seawater. Seasonal variability can also have an effect on microbial communities of marine snow aggregates with concentrations being the highest during the summer. +As illustrated in the diagram, phytoplankton fix carbon dioxide in the euphotic zone using solar energy and produce particulate organic carbon. The particulate organic carbon formed in the euphotic zone is processed by marine microorganisms (microbes), zooplankton and their consumers into organic aggregates (marine snow), which is then exported to the mesopelagic (200–1000 m depth) and bathypelagic zones by sinking and vertical migration by zooplankton and fish. +Export flux is defined as the sedimentation out of the surface layer (at approximately 100 m depth) and sequestration flux is the sedimentation out of the mesopelagic zone (at approximately 1000 m depth). A portion of the particulate organic carbon is respired back to CO2 in the oceanic water column at depth, mostly by heterotrophic microbes and zooplankton, thus maintaining a vertical gradient in concentration of dissolved inorganic carbon (DIC). This deep-ocean DIC returns to the atmosphere on millennial timescales through thermohaline circulation. Between 1% and 40% of the primary production is exported out of the euphotic zone, which attenuates exponentially towards the base of the mesopelagic zone and only about 1% of the surface production reaches the sea floor. +The largest component of biomass are marine protists (eukaryotic microorganisms). Marine snow aggregates collected from the bathypelagic zone were found to consist largely of fungi and labyrinthulomycetes. Smaller aggregates do not harbor as many eukaryotic organisms which is similar to what is found in the deep ocean. The bathypelagic aggregates mostly resembled those found in the surface ocean. It implies higher rates of remineralization in the bathypelagic zone. +Numerically, the largest component of marine snow are the prokaryotes that colonize the aggregates. Bacteria are largely responsible for the remineralisation and fragmentation of aggregates. Remineralization occurs typically below 200 m depth. +Microbial communities that form on the aggregates vary from the communities in the water column. The concentration of attached microbes are typically orders of magnitude larger than free-living microbes. Isolated bacterial cultures have up to 20 times more enzymatic activity within 2 hours of aggregate attachment. The dark ocean harbors around 65% of all pelagic Bacteria and Archaea.(Whitman et al., 1998) +It was previously thought that due to fragmentation, bacterial communities would shift as they travel down the water column. As seen in experiments, it now appears that the communities that form during aggregation remain associated with the aggregate and any community changes are due to grazing or fragmentation rather than new bacterial colony formation. + +=== Carbon cycling === +The deep ocean harbors more than 98% of the dissolved inorganic carbon pool, along with a rapid sedimentation rate that results in low particulate organic carbon inputs. It is yet to be resolved what effect microbes have on the global carbon cycle. Studies show that microbes in the deep ocean are not dormant, but are metabolically active and must be participating in nutrient cycling by not only heterotrophs but by autotrophs as well. There is a mismatch from the microbial carbon demand in the deep ocean and the carbon export from the surface ocean. Dissolved inorganic carbon fixation is on similar orders of magnitude as heterotrophic microbes in the surface ocean. Model-based data reveal that dissolved inorganic carbon fixation ranges from 1 mmol C m−2 d−1 to 2.5 mmol C m−2 d−1. + +==== Microenvironments ==== +Large aggregates can become anoxic which gives rise to anaerobic metabolisms. Typically anaerobic metabolisms are confined to areas where it is more energetically favorable. Given the abundance of denitrifying and sulfate-reducing bacteria, it is thought that these metabolisms are able to thrive within marine snow aggregates. In a model developed by Bianchi et al., it shows the various redox potentials within an aggregate. + +== Implications == +Because of the relatively long residence time of the ocean's thermohaline circulation, carbon transported as marine snow into the deep ocean by the biological pump can remain out of contact with the atmosphere for more than 1000 years. That is, when the marine snow is finally decomposed to inorganic nutrients and dissolved carbon dioxide, these are effectively isolated from the surface ocean for relatively long time scales related to ocean circulation. Consequently, enhancing the quantity of marine snow that reaches the deep ocean is the basis of several geoengineering schemes to enhance carbon sequestration by the ocean. Ocean nourishment and iron fertilisation seek to boost the production of organic material in the surface ocean, with a concomitant rise in marine snow reaching the deep ocean. These efforts have not yet produced a sustainable fertilization that effectively transports carbon out of the system. +Increases in ocean temperatures, a projected indicator of climate change, may result in a decrease in the production of marine snow due to the enhanced stratification of the water column. Increasing stratification decreases the availability of phytoplankton nutrients such as nitrate, phosphate and silicic acid, and could lead to a decrease in primary production and, thus, marine snow. +The microbial communities associated with marine snow are also interesting to microbiologists. Recent research indicates transported bacteria may exchange genes with previously thought to be isolated populations of bacteria inhabiting the breadth of the ocean floor. In such an immense area there may be as yet undiscovered species tolerant of high pressures and extreme cold, perhaps finding use in bioengineering and pharmacy. + +== See also == + +Biological pump +Detritivore +Diffusion-limited aggregation +f-ratio +Martin curve +Particulate organic matter +Sea snot +Sediment trap +Whale fall +Vampire squid +Seston + +== References == + +== Further reading == +Mary Wilcox Silver (2015). "Marine Snow: A Brief Historical Sketch". Limnology and Oceanography Bulletin, 24:5-10. https://doi.org/10.1002/lob.10005 + +== External links == +U. Georgia, Marine Snow and Particles +U. Bangor, Marine Snow: Formation and composition +NIWA, What grows up must fall down: the potential impact of climate change on plankton and carbon export +Primary production and vertical export \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Mediterranean_seas-0.md b/data/en.wikipedia.org/wiki/Mediterranean_seas-0.md new file mode 100644 index 000000000..55b7ec893 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Mediterranean_seas-0.md @@ -0,0 +1,72 @@ +--- +title: "Mediterranean seas" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Mediterranean_seas" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:35.481636+00:00" +instance: "kb-cron" +--- + +In oceanography, a mediterranean sea ( MED-ih-tə-RAY-nee-ən) is a mostly enclosed sea that has limited exchange of water with outer oceans and whose water circulation is dominated by salinity and temperature differences rather than by winds or tides. The eponymous Mediterranean Sea, for example, is almost completely enclosed by Africa, Asia, and Europe. + + +== List of mediterranean seas by ocean == + + +=== Atlantic Ocean === +The Arctic Ocean (a.k.a. the Arctic Mediterranean Sea) +The American Mediterranean Sea (the combination of the Caribbean Sea and the Gulf of Mexico) +Baffin Bay +The Baltic Sea +The namesake Mediterranean Sea (including the Adriatic Sea, the Aegean Sea (including the Sea of Crete and the Thracian Sea), the Alboran Sea, the Balearic Sea, the Sardinian Sea, the Black Sea, the Ionian Sea, the Ligurian Sea, the Sea of Azov, the Sea of Marmara, and the Tyrrhenian Sea) + + +=== Indian Ocean === +The Persian Gulf +The Red Sea + + +=== Pacific Ocean === +The Australasian Mediterranean Sea (including the Banda Sea, the Java Sea, the Sulawesi Sea, and the Sulu Sea) + + +== List of mediterranean seas by type == +There are two types of mediterranean sea. + + +=== Concentration basin === +A concentration basin has a higher salinity than the outer ocean due to evaporation, and its water exchange consists of inflow of the fresher oceanic water in the upper layer and outflow of the saltier mediterranean water in the lower layer of the connecting channel. + +The Eurafrican Mediterranean Sea (a concentration basin as a whole, but the Adriatic Sea and the Black Sea are dilution basins (see below) owing to the Po River, and the Danube, Dnieper, and Don rivers respectively) +The Persian Gulf +The Red Sea + + +=== Dilution basin === +A dilution basin has a lower salinity due to freshwater gains such as rainfall and rivers, and its water exchange consists of outflow of the fresher mediterranean water in the upper layer and inflow of the saltier oceanic water in the lower layer of the channel. Renewal of deep water may not be sufficient to supply oxygen to the bottom. + +The Adriatic Sea +The American Mediterranean Sea +The Arctic Ocean (a.k.a. the Arctic Mediterranean Sea) +The Australasian Mediterranean Sea +Baffin Bay +The Baltic Sea +The Black Sea + + +== Exceptions == +Hudson Bay is so shallow it functions like a huge estuary. +Having shallow channels and deep basins, the Sea of Japan could form a mediterranean sea, but the strong currents from the Pacific prevent it from having an independent water circulation. + + +== See also == + +Inland sea +Marginal sea + + +== References == + + +== Further reading == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Megatsunami-0.md b/data/en.wikipedia.org/wiki/Megatsunami-0.md new file mode 100644 index 000000000..de43b8680 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Megatsunami-0.md @@ -0,0 +1,15 @@ +--- +title: "Megatsunami" +chunk: 1/10 +source: "https://en.wikipedia.org/wiki/Megatsunami" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:36.838495+00:00" +instance: "kb-cron" +--- + +A megatsunami is an extremely large wave created by a substantial and sudden displacement of material into a body of water. +Megatsunamis have different features from ordinary tsunamis. Ordinary tsunamis are caused by underwater tectonic activity (movement of the earth's plates) and therefore occur along plate boundaries and as a result of earthquakes and the subsequent rise or fall in the sea floor that displaces a volume of water. Ordinary tsunamis exhibit shallow waves in the deep waters of the open ocean that increase dramatically in height upon approaching land to a maximum run-up height of around 30 metres (100 ft) in the cases of the most powerful earthquakes. By contrast, megatsunamis occur when a large amount of material suddenly falls into water or anywhere near water (such as via a landslide, meteor impact, or volcanic eruption). They can have extremely large initial wave heights in the hundreds of metres, far beyond the height of any ordinary tsunami. These giant wave heights occur because the water is "splashed" upwards and outwards by the displacement. +Examples of modern megatsunamis include the one associated with the 1883 eruption of Krakatoa (volcanic eruption), the 1958 Lituya Bay earthquake and megatsunami (a landslide which resulted in wave runup up to an elevation of 524.6 metres (1,721 ft)), and the 1963 Vajont Dam landslide (caused by human activity destabilizing sides of valley). Prehistoric examples include the Storegga Slide (landslide), and the Chicxulub, Chesapeake Bay, and Eltanin meteor impacts. + +== Overview == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Megatsunami-1.md b/data/en.wikipedia.org/wiki/Megatsunami-1.md new file mode 100644 index 000000000..0ff83abaf --- /dev/null +++ b/data/en.wikipedia.org/wiki/Megatsunami-1.md @@ -0,0 +1,17 @@ +--- +title: "Megatsunami" +chunk: 2/10 +source: "https://en.wikipedia.org/wiki/Megatsunami" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:36.838495+00:00" +instance: "kb-cron" +--- + +A megatsunami is a tsunami with an initial wave amplitude (height) measured in many tens or hundreds of metres. The term "megatsunami" has been defined by media and has no precise definition, although it is commonly taken to refer to tsunamis over 100 metres (328 ft) high. A megatsunami is a separate class of event from an ordinary tsunami and is caused by different physical mechanisms. +Normal tsunamis result from displacement of the sea floor due to movements in the Earth's crust (plate tectonics). Powerful earthquakes may cause the sea floor to displace vertically on the order of tens of metres, which in turn displaces the water column above and leads to the formation of a tsunami. Ordinary tsunamis have a small wave height offshore and generally pass unnoticed at sea, forming only a slight swell on the order of 30 centimetres (12 in) above the normal sea surface. In deep water it is possible that a tsunami could pass beneath a ship without the crew of the vessel noticing. As it approaches land, the wave height of an ordinary tsunami increases dramatically as the sea floor slopes upward and the base of the wave pushes the water column above it upwards. Ordinary tsunamis, even those associated with the most powerful strike-slip earthquakes, typically do not reach heights in excess of 30 m (100 ft). +By contrast, megatsunamis are caused by landslides and massive earthquakes that displace large volumes of water, resulting in waves that may exceed the height of an ordinary tsunami by tens or even hundreds of metres. Underwater earthquakes or volcanic eruptions do not normally generate megatsunamis, but landslides next to bodies of water resulting from earthquakes or volcanic eruptions can, since they cause a much larger amount of water displacement. If the landslide or impact occurs in a limited body of water, as happened in Lituya Bay (1958) and at the Vajont Dam (1963), then the water may be unable to disperse and one or more exceedingly large waves may result. +Submarine landslides can pose a significant hazard when they cause a tsunami. Although a variety of different types of landslides can cause tsunami, all the resulting tsunami have similar features such as large run-ups close to the tsunami, but quicker attenuation compared to tsunami caused by earthquakes. An example of this was the 17 July 1998 Papua New Guinean landslide tsunami, in which waves up to 15 metres (49 ft) high struck a 20-kilometre (12.4-mile) section of the coast, killing 2,200 people, yet at greater distances the tsunami was not a major hazard. This is due to the comparatively small source area of most landslide tsunami (relative to the area affected by large earthquakes) which causes the generation of waves with shorter wavelengths. These waves are greatly affected by coastal amplification (which amplifies the local effect) and radial damping (which reduces the distal effect). +The size of landslide-generated tsunamis depends both on the geological details of the landslide (such as its Froude number) and also on assumptions about the hydrodynamics of the model used to simulate tsunami generation, thus they have a large margin of uncertainty. Generally, landslide-induced tsunamis decay more quickly with distance than earthquake-induced tsunamis, as the former, often having a dipole structure at the source, tend to spread out radially and have a shorter wavelength (the rate at which a wave loses energy is inversely proportional to its wavelength, so the longer the wavelength of a wave, the more slowly it loses energy) while the latter disperses little as it propagates away perpendicularly to the source fault. Testing whether a given tsunami model is correct is complicated by the rarity of giant collapses. +Recent findings show that the nature of a tsunami depends upon the volume, velocity, initial acceleration, length, and thickness of the landslide generating it. Volume and initial acceleration are the key factors which determine whether a landslide will form a tsunami. A sudden deceleration of the landslide may also result in larger waves. The length of the slide influences both the wavelength and the maximum wave height. Travel time or run-out distance of the slide also will influence the resulting tsunami wavelength. In most cases, submarine landslides are noticeably subcritical, that is, the Froude number (the ratio of slide speed to wave propagation) is significantly less than one. This suggests that the tsunami will move away from the wave-generating slide, preventing the buildup of the wave. Failures in shallow waters tend to produce larger tsunamis because the wave is more critical as the speed of propagation is less. Furthermore, shallower waters are generally closer to the coast, meaning that there is less radial damping by the time the tsunami reaches the shore. Conversely tsunamis triggered by earthquakes are more critical when the seabed displacement occurs in the deep ocean, as the first wave (which is less affected by depth) has a shorter wavelength and is enlarged when travelling from deeper to shallower waters. +Determining a height range typical of megatsunamis is a complex and scientifically debated topic. This complexity is increased by the two different heights often reported for tsunamis – the height of the wave itself in open water and the height to which it surges when it encounters land. Depending upon the locale, this second height, the "run-up height," can be several times larger than the wave's height just before it reaches shore. While there is no minimum or average height classification for megatsunamis that the scientific community broadly accepts, the limited number of observed megatsunami events in recent history have all had run-up heights that exceeded 100 metres (300 ft). The megatsunami in Spirit Lake in Washington in the United States generated by the 1980 eruption of Mount St. Helens reached 260 metres (853 ft), while the tallest megatsunami ever recorded (in Lituya Bay in 1958) reached a run-up height of 520 metres (1,720 ft). It is also possible that much larger megatsunamis occurred in prehistory; researchers analyzing the geological structures left behind by prehistoric asteroid impacts have suggested that these events could have resulted in megatsunamis that exceeded 1,500 metres (4,900 ft) in height. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Megatsunami-2.md b/data/en.wikipedia.org/wiki/Megatsunami-2.md new file mode 100644 index 000000000..2e8462e78 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Megatsunami-2.md @@ -0,0 +1,27 @@ +--- +title: "Megatsunami" +chunk: 3/10 +source: "https://en.wikipedia.org/wiki/Megatsunami" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:36.838495+00:00" +instance: "kb-cron" +--- + +== Recognition of the concept of megatsunami == + +Before the 1950s, scientists had theorized that tsunamis orders of magnitude larger than those observed with earthquakes could have occurred as a result of ancient geological processes, but no concrete evidence of the existence of these "monster waves" had yet been gathered. Geologists searching for oil in Alaska in 1953 observed that in Lituya Bay, mature tree growth did not extend to the shoreline as it did in many other bays in the region. Rather, there was a band of younger trees closer to the shore. Forestry workers, glaciologists, and geographers call the boundary between these bands a trim line. Trees just above the trim line showed severe scarring on their seaward side, while those from below the trim line did not. This indicated that a large force had impacted all of the elder trees above the trim line, and presumably had killed off all the trees below it. Based on this evidence, the scientists hypothesized that there had been an unusually large wave or waves in the deep inlet. Because this is a recently deglaciated fjord with steep slopes and crossed by a major fault (the Fairweather Fault), one possibility was that this wave was a landslide-generated tsunami. +On 9 July 1958, a 7.8 Mw strike-slip earthquake in Southeast Alaska caused 80,000,000 metric tons (90,000,000 short tons) of rock and ice to drop into the deep water at the head of Lituya Bay. The block fell almost vertically and hit the water with sufficient force to create a wave that surged up the opposite side of the head of the bay to a height of 520 metres (1,710 feet), and was still many tens of metres high further down the bay when it carried eyewitnesses Howard Ulrich and his son Howard Jr. over the trees in their fishing boat. They were washed back into the bay and both survived. + +== Analysis of mechanism == +The mechanism giving rise to megatsunamis was analysed for the Lituya Bay event in a study presented at the Tsunami Society in 1999; this model was considerably developed and modified by a second study in 2010. +Although the earthquake which caused the megatsunami was considered very energetic, it was determined that it could not have been the sole contributor based on the measured height of the wave. Neither water drainage from a lake, nor a landslide, nor the force of the earthquake itself were sufficient to create a megatsunami of the size observed, although all of these may have been contributing factors. +Instead, the megatsunami was caused by a combination of events in quick succession. The primary event occurred in the form of a large and sudden impulsive impact when about 40 million cubic yards of rock several hundred metres above the bay was fractured by the earthquake, and fell "practically as a monolithic unit" down the almost-vertical slope and into the bay. The rockfall also caused air to be "dragged along" due to viscosity effects, which added to the volume of displacement, and further impacted the sediment on the floor of the bay, creating a large crater. The study concluded that: + +The giant wave runup of 1,720 feet (524 m) at the head of the Bay and the subsequent huge wave along the main body of Lituya Bay which occurred on July 9, 1958, were caused primarily by an enormous subaerial rockfall into Gilbert Inlet at the head of Lituya Bay, triggered by dynamic earthquake ground motions along the Fairweather Fault. +The large monolithic mass of rock struck the sediments at bottom of Gilbert Inlet at the head of the bay with great force. The impact created a large crater and displaced and folded recent and Tertiary deposits and sedimentary layers to an unknown depth. The displaced water and the displacement and folding of the sediments broke and uplifted 1,300 feet of ice along the entire front face of the Lituya Glacier at the north end of Gilbert Inlet. Also, the impact and the sediment displacement by the rockfall resulted in an air bubble and in water splashing action that reached the 1,720-foot (524 m) elevation on the other side of the head of Gilbert Inlet. The same rockfall impact, in combination with the strong ground movements, the net vertical crustal uplift of about 3.5 feet, and an overall tilting seaward of the entire crustal block on which Lituya Bay was situated, generated the giant solitary gravity wave which swept the main body of the bay. + +This was the most likely scenario of the event – the "PC model" that was adopted for subsequent mathematical modeling studies with source dimensions and parameters provided as input. Subsequent mathematical modeling at the Los Alamos National Laboratory (Mader, 1999, Mader & Gittings, 2002) supported the proposed mechanism and indicated that there was indeed sufficient volume of water and an adequately deep layer of sediments in the Lituya Bay inlet to account for the giant wave runup and the subsequent inundation. The modeling reproduced the documented physical observations of runup. +A 2010 model that examined the amount of infill on the floor of the bay, which was many times larger than that of the rockfall alone, and also the energy and height of the waves, and the accounts given by eyewitnesses, concluded that there had been a "dual slide" involving a rockfall, which also triggered a release of 5 to 10 times its volume of sediment trapped by the adjacent Lituya Glacier, as an almost immediate and many times larger second slide, a ratio comparable with other events where this "dual slide" effect is known to have happened. + +== Examples == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Megatsunami-3.md b/data/en.wikipedia.org/wiki/Megatsunami-3.md new file mode 100644 index 000000000..e566eda01 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Megatsunami-3.md @@ -0,0 +1,26 @@ +--- +title: "Megatsunami" +chunk: 4/10 +source: "https://en.wikipedia.org/wiki/Megatsunami" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:36.838495+00:00" +instance: "kb-cron" +--- + +=== Prehistoric === +An astronomical object between 37 and 58 kilometres (23 and 36 mi) wide traveling at 20 kilometres (12.4 mi) per second struck the Earth 3.26 billion years ago east of what is now Johannesburg, South Africa, near South Africa's border with Eswatini, in what was then an Archean ocean that covered most of the planet, creating a crater about 500 kilometres (310 mi) wide. The impact generated a megatsunami that probably extended to a depth of thousands of meters beneath the surface of the ocean and probably rose to the height of a skyscraper when it reached shorelines. The resultant event created the Barberton Greenstone Belt. +The asteroid linked to the extinction of dinosaurs, which created the Chicxulub crater in the Yucatán Peninsula approximately 66 million years ago, would have caused a megatsunami over 100 metres (330 ft) tall. The height of the tsunami was limited due to relatively shallow sea in the area of the impact; had the asteroid struck in the deep sea the megatsunami would have likely been 4.6 kilometres (2.9 mi) tall. Among the mechanisms triggering megatsunamis were the direct impact, shockwaves, returning water in the crater with a new push outward and seismic waves with a magnitude up to ~11. A more recent simulation of the global effects of the Chicxulub megatsunami showed an initial wave height of 1.5 kilometres (0.9 mi), with later waves up to 100 metres (330 ft) in height in the Gulf of Mexico, and up to 14 metres (46 ft) in the North Atlantic and South Pacific; the discovery of mega-ripples in Louisiana via seismic imaging data, with average wavelengths of 600 metres (2,000 ft) and average wave heights of 16 metres (52 ft), looks like to confirm it. David Shonting and Cathy Ezrailson propose an "Edgerton effect" mechanism generating the megatsunami, similar to a milk drop falling on water that triggers a crown-shape water column, with a comparable height to the Chicxulub impactor's, that means over 10–12 kilometres (6–7 mi) for the initial seawater forced outward by the explosion and blast waves; then, its collapse triggers megatsunamis changing their height according to the different water depth, raising up to 500 metres (1,600 ft). Furthermore, the initial shock wave via impact triggered seismic waves producing giant landslides and slumping around the region (the largest known event deposits on Earth) with subsequent megatsunamis of various sizes, and seiches of 10 to 100 metres (30 to 300 ft) in Tanis, 3,000 kilometres (1,900 mi) away, part of a vast inland sea at the time and directly triggered via seismic shaking by the impact within a few minutes. +During the Messinian (ca. 7.25–ca. 5.3 million years ago) various megatsunamis likely struck the coast of northern Chile. +Reservoir-induced seismicity at the end of or shortly after the Zanclean Flood (ca. 5.33 million years ago), which rapidly filled the Mediterranean Basin with water from the Atlantic Ocean, created a megatsunami with a height of nearly 100 metres (330 ft) which struck the coast of Spain near what is now Algeciras. +A megatsunami affected the coast of south–central Chile in the Pliocene as evidenced by the sedimentary record of the Ranquil Formation. +The Eltanin impact in the southeast Pacific Ocean 2.5 million years ago caused a megatsunami that was over 200 metres (660 ft) high in southern Chile and the Antarctic Peninsula; the wave swept across much of the Pacific Ocean. +The northern half of the East Molokai Volcano on Molokai in Hawaii suffered a catastrophic collapse about 1.5 million years ago, generating a megatsunami, and now lies as a debris field scattered northward across the ocean bottom, while what remains on the island are the highest sea cliffs in the world. The megatsunami may have reached a height of 610 metres (2,000 ft) near its origin and reached California and Mexico. +The existence of large scattered boulders in only one of the four marine terraces of Herradura Bay south of the Chilean city of Coquimbo has been interpreted by Roland Paskoff as the result of a mega-tsunami that occurred in the Middle Pleistocene. +In Hawaii, a megatsunami at least 400 metres (1,312 ft) in height deposited marine sediments at a modern-day elevation of 326 metres (1,070 ft) – 375 to 425 metres (1,230 to 1,394 ft) above sea level at the time the wave struck – on Lanai about 105,000 years ago. The tsunami also deposited such sediments at an elevation of 60 to 80 metres (197 to 262 ft) on Oahu, Molokai, Maui, and the island of Hawaii. +The collapse of the ancestral Mount Amarelo on Fogo in the Cape Verde Islands about 73,000 years ago triggered a megatsunami which struck Santiago, 55 kilometres (34 mi; 30 nmi) away, with a height of 170 to 240 metres (558 to 787 ft) and a run-up height of over 270 metres (886 ft). The wave swept 770-tonne (760-long-ton; 850-short-ton) boulders 600 metres (2,000 ft) inland and deposited them 200 metres (656 ft) above sea level +A major collapse of the western edge of the Lake Tahoe basin, a landslide with a volume of 12.5 cubic kilometres (3.0 cu mi) which formed McKinney Bay between 21,000 and 12,000 years ago, generated megatsunamis/seiche waves with an initial height of probably about 100 m (330 ft) and caused the lake's water to slosh back and forth for days. Much of the water in the megatsunamis washed over the lake's outlet at what is now Tahoe City, California, and flooded down the Truckee River, carrying house-sized boulders as far downstream as the California-Nevada border at what is now Verdi, California. +In the North Sea, the Storegga Slide caused a megatsunami approximately 8,200 years ago. It is estimated to have completely flooded the remainder of Doggerland. +Around 6370 BCE, a 25-cubic-kilometre (6 cu mi) landslide on the eastern slope of Mount Etna in Sicily into the Mediterranean Sea triggered a megatsunami in the Eastern Mediterranean with an initial wave height along the eastern coast of Sicily of 40 metres (131 ft). It struck the Neolithic village of Atlit Yam off the coast of Israel with a height of 2.5 metres (8 ft 2 in), prompting the village's abandonment. +Around 5650 B.C., a landslide in Greenland created a megatsunami with a run-up height on Alluttoq Island of 41 to 66 metres (135 to 217 ft). +Around 5350 B.C., a landslide in Greenland created a megatsunami with a run-up height on Alluttoq Island of 45 to 70 metres (148 to 230 ft). \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Megatsunami-4.md b/data/en.wikipedia.org/wiki/Megatsunami-4.md new file mode 100644 index 000000000..aed04a1aa --- /dev/null +++ b/data/en.wikipedia.org/wiki/Megatsunami-4.md @@ -0,0 +1,49 @@ +--- +title: "Megatsunami" +chunk: 5/10 +source: "https://en.wikipedia.org/wiki/Megatsunami" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:36.838495+00:00" +instance: "kb-cron" +--- + +=== Historic === + +==== c. 2000 BC: Réunion ==== +A landslide on Réunion island, to the east of Madagascar, may have caused a megatsunami. + +==== c. 1600 BC: Santorini ==== + +The Thera volcano erupted, the force of the eruption causing megatsunamis which affected the whole Aegean Sea and the eastern Mediterranean Sea. + +==== c. 1100 BC: Lake Crescent ==== +An earthquake generated the 7,200,000-cubic-metre (9,400,000 cu yd) Sledgehammer Point Rockslide, which fell from Mount Storm King in what is now Washington in the United States and entered waters at least 140 metres (459 ft) deep in Lake Crescent, generating a megatsunami with an estimated maximum run-up height of 82 to 104 metres (269 to 341 ft). + +=== Modern === + +==== 1674: Ambon Island, Banda Sea ==== + +On 17 February 1674, between 19:30 and 20:00 local time, an earthquake struck the Maluku Islands. Ambon Island received run-up heights of 100 metres (328 ft), making the wave far too large to be caused by the quake itself. Instead, it was probably the result of an underwater landslide triggered by the earthquake. The quake and tsunami killed 2,347 people. + +==== 1731: Storfjorden, Norway ==== +At 10:00 p.m. on 8 January 1731, a landslide with a volume of possibly 6,000,000 cubic metres (7,800,000 cu yd) fell from the mountain Skafjell from a height of 500 metres (1,640 ft) into the Storfjorden opposite Stranda, Norway. The slide generated a megatsunami 30 metres (100 ft) in height that struck Stranda, flooding the area for 100 metres (330 ft) inland and destroying the church and all but two boathouses, as well as many boats. Damaging waves struck as far away as Ørskog. The waves killed 17 people. + +==== 1741: Oshima-Ōshima, Sea of Japan ==== + +An eruption of Oshima-Ōshima occurred that lasted from 18 August 1741 to 1 May 1742. On 29 August 1741, a devastating tsunami occurred. It killed at least 1,467 people along a 120-kilometre (75 mi) section of the coast, excluding native residents whose deaths were not recorded. Wave heights for Gankakezawa have been estimated at 34 metres (112 ft) based on oral histories, while an estimate of 13 metres (43 ft) is derived from written records. At Sado Island, over 350 kilometres (217 mi; 189 nmi) away, a wave height of 2 to 5 metres (6 ft 7 in to 16 ft 5 in) has been estimated based on descriptions of the damage, while oral records suggest a height of 8 metres (26 ft). Wave heights have been estimated at 3 to 4 metres (9.8 to 13.1 ft) even as far away as the Korean Peninsula. There is still no consensus in the debate as to what caused it but much evidence points to a landslide and debris avalanche along the flank of the volcano. An alternative hypothesis holds that an earthquake caused the tsunami. The event reduced the elevation of the peak of Hishiyama from 850 to 722 metres (2,789 to 2,369 ft). An estimated 2.4-cubic-kilometre (0.58 cu mi) section of the volcano collapsed onto the seafloor north of the island; the collapse was similar in size to the 2.3-cubic-kilometre (0.55 cu mi) collapse which occurred during the 1980 eruption of Mount St. Helens. + +==== 1756: Langfjorden, Norway ==== +Just before 8:00 p.m. on 22 February 1756, a landslide with a volume of 12,000,000 to 15,000,000 cubic metres (16,000,000 to 20,000,000 cu yd) travelled at high speed from a height of 400 metres (1,300 ft) on the side of the mountain Tjellafjellet into the Langfjorden about 1 kilometre (0.6 mi) west of Tjelle, Norway, between Tjelle and Gramsgrø. The slide generated three megatsunamis in the Langfjorden and the Eresfjorden with heights of 40 to 50 metres (130 to 160 ft). The waves flooded the shore for 200 metres (660 ft) inland in some areas, destroying farms and other inhabited areas. Damaging waves struck as far away as Veøya, 25 kilometres (16 mi) from the landslide – where they washed inland 20 metres (66 ft) above normal flood levels – and Gjermundnes, 40 kilometres (25 mi) from the slide. The waves killed 32 people and destroyed 168 buildings, 196 boats, large amounts of forest, and roads and boat landings. + +==== 1792: Mount Unzen, Japan ==== + +On 21 May 1792, a flank of the Mayamaya dome of Mount Unzen collapsed after two large earthquakes. This had been preceded by a series of earthquakes coming from the mountain, beginning near the end of 1791. Initial wave heights were 100 metres (330 ft), but when they hit the other side of Ariake Bay, they were only 10 to 20 metres (33 to 66 ft) in height, though one location received 57-metre (187 ft) waves due to seafloor topography. The waves bounced back to Shimabara, which, when they hit, accounted for about half of the tsunami's victims. According to estimates, 10,000 people were killed by the tsunami, and a further 5,000 were killed by the landslide. As of 2011, it was the deadliest known volcanic event in Japan. + +==== 1853–1854: Lituya Bay, Alaska ==== +Sometime between August 1853 and May 1854, a megatsunami occurred in Lituya Bay in what was then Russian America. Studies of Lituya Bay between 1948 and 1953 first identified the event, which probably occurred because of a large landslide on the south shore of the bay near Mudslide Creek. The wave had a maximum run-up height of 120 metres (394 ft), flooding the coast of the bay up to 230 metres (750 ft) inland. + +==== 1874: Lituya Bay, Alaska ==== +A study of Lituya Bay in 1953 concluded that sometime around 1874, perhaps in May 1874, another megatsunami occurred in Lituya Bay in Alaska. Probably occurring because of a large landslide on the south shore of the bay in the Mudslide Creek Valley, the wave had a maximum run-up height of 24 metres (80 ft), flooding the coast of the bay up to 640 metres (2,100 ft) inland. + +==== 1883: Krakatoa, Sunda Strait ==== \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Megatsunami-5.md b/data/en.wikipedia.org/wiki/Megatsunami-5.md new file mode 100644 index 000000000..305b7d8e2 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Megatsunami-5.md @@ -0,0 +1,30 @@ +--- +title: "Megatsunami" +chunk: 6/10 +source: "https://en.wikipedia.org/wiki/Megatsunami" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:36.838495+00:00" +instance: "kb-cron" +--- + +The massive explosion of Krakatoa created pyroclastic flows which generated megatsunamis when they hit the waters of the Sunda Strait on 27 August 1883. The waves reached heights of up to 24 metres (79 feet) along the south coast of Sumatra and up to 42 metres (138 feet) along the west coast of Java. The tsunamis were powerful enough to kill over 30,000 people, and their effect was such that an area of land in Banten had its human settlements wiped out, and they never repopulated. (This area rewilded and was later declared a national park.) The steamship Berouw, a colonial gunboat, was flung over a mile (1.6 km) inland on Sumatra by the wave, killing its entire crew. Two thirds of the island collapsed into the sea after the event. Groups of human skeletons were found floating on pumice numerous times, up to a year after the event. The eruption also generated what is often called the loudest sound in history, which was heard 4,800 kilometres (3,000 mi; 2,600 nmi) away on Rodrigues in the Indian Ocean. + +==== 1905: Lovatnet, Norway ==== +On 15 January 1905, a landslide on the slope of the mountain Ramnefjellet with a volume of 350,000 cubic metres (460,000 cu yd) fell from a height of 500 metres (1,600 ft) into the southern end of the lake Lovatnet in Norway, generating three megatsunamis of up to 40.5 metres (133 ft) in height. The waves destroyed the villages of Bødal and Nesdal near the southern end of the lake, killing 61 people – half their combined population – and 261 farm animals and destroying 60 houses, all the local boathouses, and 70 to 80 boats, one of which – the tourist boat Lodalen – was thrown 300 metres (1,000 ft) inland by the last wave and wrecked. At the northern end of the 11.7-kilometre (7.3 mi) long lake, a wave measured at almost 6 metres (20 ft) destroyed a bridge. + +==== 1905: Disenchantment Bay, Alaska ==== +On 4 July 1905, an overhanging glacier – since known as the Fallen Glacier – broke loose, slid out of its valley, and fell 300 metres (1,000 ft) down a steep slope into Disenchantment Bay in Alaska, clearing vegetation along a path 0.8 kilometres (0.5 mi) wide. When it entered the water, it generated a megatsunami which broke tree branches 34 metres (110 ft) above ground level 0.8 kilometres (0.5 mi) away. The wave killed vegetation to a height of 20 metres (65 ft) at a distance of 5 kilometres (3 mi) from the landslide, and it reached heights of 15 to 35 metres (50 to 115 ft) at different locations on the coast of Haenke Island. At a distance of 24 kilometres (15 mi) from the slide, observers at Russell Fjord reported a series of large waves that caused the water level to rise and fall 5 to 6 metres (15 to 20 ft) for a half-hour. + +==== 1934: Tafjorden, Norway ==== +On 7 April 1934, a landslide on the slope of the mountain Langhamaren with a volume of 3,000,000 cubic metres (3,900,000 cu yd) fell from a height of about 730 metres (2,395 ft) into the Tafjorden in Norway, generating three megatsunamis, the last and largest of which reached a height of between 62 and 63.5 metres (203 and 208 ft) on the opposite shore. Large waves struck Tafjord and Fjørå. At Tafjord, the last and largest wave was 17 metres (56 ft) tall and struck at an estimated speed of 160 kilometres per hour (100 mph), flooding the town for 300 metres (328 yd) inland and killing 23 people. At Fjørå, waves reached 13 metres (43 ft), destroyed buildings, removed all soil, and killed 17 people. Damaging waves struck as far as 50 kilometres (31 mi) away, and waves were detected at a distance of 100 kilometres (62 mi) from the landslide. One survivor suffered serious injuries requiring hospitalization. + +==== 1936: Lovatnet, Norway ==== +On 13 September 1936, a landslide on the slope of the mountain Ramnefjellet with a volume of 1,000,000 cubic metres (1,300,000 cu yd) fell from a height of 800 metres (3,000 ft) into the southern end of the lake Lovatnet in Norway, generating three megatsunamis, the largest of which reached a height of 74 metres (243 ft). The waves destroyed all farms at Bødal and most farms at Nesdal – completely washing away 16 farms – as well as 100 houses, bridges, a power station, a workshop, a sawmill, several grain mills, a restaurant, a schoolhouse, and all boats on the lake. A 12.6-metre (41 ft) wave struck the southern end of the 11.7-kilometre (7.3 mi) long lake and caused damaging flooding in the Loelva River, the lake's northern outlet. The waves killed 74 people and severely injured 11. + +==== 1936: Lituya Bay, Alaska ==== +On 27 October 1936, a megatsunami occurred in Lituya Bay in Alaska with a maximum run-up height of 150 metres (490 ft) in Crillon Inlet at the head of the bay. The four eyewitnesses to the wave in Lituya Bay itself all survived and described it as between 30 and 76 metres (100 and 250 ft) high. The maximum inundation distance was 610 metres (2,000 ft) inland along the north shore of the bay. The cause of the megatsunami remains unclear, but may have been a submarine landslide. + +==== 1958: Lituya Bay, Alaska, US ==== + +On 9 July 1958, a giant landslide at the head of Lituya Bay in Alaska, caused by an earthquake, generated a wave that washed out trees to a maximum elevation of 520 metres (1,710 ft) at the entrance of Gilbert Inlet. The wave surged over the headland, stripping trees and soil down to bedrock, and surged along the fjord which forms Lituya Bay, destroying two fishing boats anchored there and killing two people. This was the highest wave of any kind ever recorded. The subsequent study of this event led to the establishment of the term "megatsunami," to distinguish it from ordinary tsunamis. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Megatsunami-6.md b/data/en.wikipedia.org/wiki/Megatsunami-6.md new file mode 100644 index 000000000..be27b4471 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Megatsunami-6.md @@ -0,0 +1,36 @@ +--- +title: "Megatsunami" +chunk: 7/10 +source: "https://en.wikipedia.org/wiki/Megatsunami" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:36.838495+00:00" +instance: "kb-cron" +--- + +==== 1963: Vajont Dam, Italy ==== + +On 9 October 1963, a landslide above Vajont Dam in Italy produced a 250 m (820 ft) surge that overtopped the dam and destroyed the villages of Longarone, Pirago, Rivalta, Villanova, and Faè, killing nearly 2,000 people. This is currently the only known example of a megatsunami that was indirectly caused by human activities. + +==== 1964: Valdez Arm, Alaska ==== +On 27 March 1964, the 1964 Alaska earthquake triggered a landslide that generated a megatsunami which reached a height of 70 metres (230 ft) in the Valdez Arm of Prince William Sound in Southcentral Alaska. + +==== 1980: Spirit Lake, Washington, US ==== + +On 18 May 1980, the upper 400 metres (1,300 ft) of Mount St. Helens collapsed, creating a landslide. This released the pressure on the magma trapped beneath the summit bulge which exploded as a lateral blast, which then released the pressure on the magma chamber and resulted in a plinian eruption. +One lobe of the avalanche surged onto Spirit Lake, causing a megatsunami which pushed the lake waters in a series of surges, which reached a maximum height of 260 metres (850 ft) above the pre-eruption water level (about 975 m (3,199 ft) ASL). Above the upper limit of the tsunami, trees lie where they were knocked down by the pyroclastic surge; below the limit, the fallen trees and the surge deposits were removed by the megatsunami and deposited in Spirit Lake. + +==== 2000: Paatuut, Greenland ==== +On 21 November 2000, a landslide composed of 90,000,000 cubic metres (120,000,000 cu yd) of rock with a mass of 260,000,000 tons fell from an elevation of 1,000 to 1,400 metres (3,300 to 4,600 ft) at Paatuut on the Nuussuaq Peninsula on the west coast of Greenland, reaching a speed of 140 kilometres per hour (87 mph). About 30,000,000 cubic metres (39,000,000 cu yd) of material with a mass of 87,000,000 tons entered Sullorsuaq Strait (known in Danish as Vaigat Strait), generating a megatsunami. The wave had a run-up height of 50 metres (164 ft) near the landslide and 28 metres (92 ft) at Qullissat, the site of an abandoned settlement across the strait on Disko Island, 20 kilometres (11 nmi; 12 mi) away, where it inundated the coast as far as 100 metres (328 ft) inland. Refracted energy from the tsunami created a wave that destroyed boats at the closest populated village, Saqqaq, on the southwestern coast of the Nuussuaq Peninsula 40 kilometres (25 mi) from the landslide. + +==== 2007: Chehalis Lake, British Columbia, Canada ==== +On 4 December 2007, a landslide composed of 3,000,000 cubic metres (3,900,000 cu yd) of rock and debris fell from an elevation of 550 metres (1,804 ft) on the slope of Mount Orrock on the western short of Chehalis Lake. The landslide entered the 175-metre (574 ft) deep lake, generating a megatsunami with a run-up height of 37.8 metres (124 ft) on the opposite shore and 6.3 metres (21 ft) at the lake's exit point 7.5 kilometres (4.7 mi) away to the south. The wave then continued down the Chehalis River for about 15 kilometres (9.3 mi). + +==== 2015: Taan Fiord, Alaska, US ==== + +At 8:19 p.m. Alaska Daylight Time on 17 October 2015, the side of a mountain collapsed at the head of Taan Fiord, a finger of Icy Bay in Alaska. Some of the resulting landslide came to rest on the toe of Tyndall Glacier, but about 180,000,000 short tons (161,000,000 long tons; 163,000,000 metric tons) of rock with a volume of about 50,000,000 cubic metres (65,400,000 cu yd) fell into the fjord. The landslide generated a megatsunami with an initial height of about 100 metres (330 feet) that struck the opposite shore of the fjord, with a run-up height there of 193 metres (633 feet). +Over the next 12 minutes, the wave traveled down the fjord at a speed of up to 97 kilometres per hour (60 mph), with run-up heights of over 100 metres (328 feet) in the upper fjord to between 30 and 100 metres (98 and 330 feet) or more in its middle section, and 20 metres (66 feet) or more at its mouth. Still probably 12 metres (40 feet) tall when it entered Icy Bay, the tsunami inundated parts of Icy Bay's shoreline with run-ups of 4 to 5 metres (13 to 16 feet) before dissipating into insignificance at distances of 5 kilometres (3.1 mi) from the mouth of Taan Fiord, although the wave was detected 140 kilometres (87 miles) away. +Occurring in an uninhabited area, the event was unwitnessed, and several hours passed before the signature of the landslide was noticed on seismographs at Columbia University in New York City. + +==== 2017: Karrat Fjord, Greenland ==== +On 17 June 2017, 35,000,000 to 58,000,000 cubic metres (46,000,000 to 76,000,000 cu yd) of rock on the mountain Ummiammakku fell from an elevation of roughly 1,000 metres (3,280 ft) into the waters of the Karrat Fjord. The event was thought to be caused by melting ice that destabilised the rock. It registered as a magnitude 4.1 earthquake and created a 100-metre (328 ft) wave. The settlement of Nuugaatsiaq, 32 kilometres (20 mi) away, saw run-up heights of 9 metres (30 ft). Eleven buildings were swept into the sea, four people died, and 170 residents of Nuugaatsiaq and Illorsuit were evacuated because of a danger of additional landslides and waves. The tsunami was noted at settlements as far as 100 kilometres (62 mi) away. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Megatsunami-7.md b/data/en.wikipedia.org/wiki/Megatsunami-7.md new file mode 100644 index 000000000..987ffd101 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Megatsunami-7.md @@ -0,0 +1,27 @@ +--- +title: "Megatsunami" +chunk: 8/10 +source: "https://en.wikipedia.org/wiki/Megatsunami" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:36.838495+00:00" +instance: "kb-cron" +--- + +==== 2020: Elliot Creek, British Columbia, Canada ==== +On 28 November 2020, unseasonably heavy rainfall triggered a landslide of 18,000,000 m3 (24,000,000 cu yd) into a glacial lake at the head of Elliot Creek. The sudden displacement of water generated a 100 m (330 ft) high megatsunami that cascaded down Elliot Creek and the Southgate River to the head of Bute Inlet, covering a total distance of over 60 km (37 mi). The event generated a magnitude 5.0 earthquake and destroyed over 8.5 km (5.3 mi) of salmon habitat along Elliot Creek. The slope had been gradually weakened over time by the retreat of West Grenville Glacier, causing the weight distribution in this area to change. + +==== 2023: Dickson Fjord, Greenland ==== + +On 16 September 2023 a large landslide originating 300–400 m (980–1,310 ft) above sea level entered Dickson Fjord, triggering a tsunami exceeding 200 m (660 ft) in run-up. Run-up of 60 m (200 ft) was observed along a 10 km (6.2 mi) stretch of coast. There was no major damage and there were no casualties. The tsunami was followed by a seiche that lasted for a week. The seiche produced a nine-day disturbance recorded by seismic instruments globally. + +==== 2025: Tracy Arm, Alaska ==== +On 10 August 2025, a large landslide consisting of approximately 100,000,000 m3 (130,000,000 cu yd) of material occurred near the terminus of South Sawyer Glacier in Tracy Arm, a fjord in Southeast Alaska. A 470-to-500-metre (1,542-to-1,640-foot) run-up occurred on the shore of Tracy Arm opposite the landslide and a run-up of at least 30 metres (98 ft) took place at nearby Sawyer Island in Tracy Arm. At the mouth of Tracy Arm, waves estimated at 3 to 5 metres (10 to 15 ft) in height struck Harbour Island, where water rose at least 25 feet (7.6 m) above the high tide line. Tsunami waves of up to 36 centimetres (14 in) reached a gauge 80 miles (129 km) from the landslide at Juneau, Alaska. According to the Alaska Earthquake Center, the event had a magnitude of Mw 5.4. + +== Potential future megatsunamis == +In a BBC television documentary broadcast in 2000, experts said that they thought that a landslide on a volcanic ocean island is the most likely future cause of a megatsunami. The size and power of a wave generated by such means could produce devastating effects, travelling across oceans and inundating up to 25 kilometres (16 mi) inland from the coast. This research was later found to be flawed. The documentary was produced before the experts' scientific paper was published and before responses were given by other geologists. There have been megatsunamis in the past, and future megatsunamis are possible but current geological consensus is that these are only local. A megatsunami in the Canary Islands would diminish to a normal tsunami by the time it reached the continents. Also, the current consensus for La Palma is that the region conjectured to collapse is too small and too geologically stable to do so in the next 10,000 years, although there is evidence for past megatsunamis local to the Canary Islands thousands of years ago. Similar remarks apply to the suggestion of a megatsunami in Hawaii. + +=== British Columbia === +Some geologists consider an unstable rock face at Mount Breakenridge, above the north end of the giant fresh-water fjord of Harrison Lake in the Fraser Valley of southwestern British Columbia, Canada, to be unstable enough to collapse into the lake, generating a megatsunami that might destroy the town of Harrison Hot Springs (located at its south end). + +=== Canary Islands === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Megatsunami-8.md b/data/en.wikipedia.org/wiki/Megatsunami-8.md new file mode 100644 index 000000000..21b6d39e1 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Megatsunami-8.md @@ -0,0 +1,29 @@ +--- +title: "Megatsunami" +chunk: 9/10 +source: "https://en.wikipedia.org/wiki/Megatsunami" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:36.838495+00:00" +instance: "kb-cron" +--- + +Geologists Dr. Simon Day and Dr. Steven Neal Ward consider that a megatsunami could be generated during an eruption of Cumbre Vieja on the volcanic ocean island of La Palma, in the Canary Islands, Spain. Day and Ward hypothesize that if such an eruption causes the western flank to fail, a megatsunami could be generated. +In 1949, an eruption occurred at three of the volcano's vents – Duraznero, Hoyo Negro, and Llano del Banco. A local geologist, Juan Bonelli-Rubio, witnessed the eruption and recorded details on various phenomenon related to the eruption. Bonelli-Rubio visited the summit area of the volcano and found that a fissure about 2.5 kilometres (1.6 mi) long had opened on the east side of the summit. As a result, the western half of the volcano – which is the volcanically active arm of a triple-armed rift – had slipped approximately 2 metres (7 ft) downwards and 1 metre (3 ft) westwards towards the Atlantic Ocean. +In 1971, an eruption occurred at the Teneguía vent at the southern end of the sub-aerial section of the volcano without any movement. The section affected by the 1949 eruption is currently stationary and does not appear to have moved since the initial rupture. +Cumbre Vieja remained dormant until an eruption began on 19 September 2021. +It is likely that several eruptions would be required before failure would occur on Cumbre Vieja. The western half of the volcano has an approximate volume of 500 cubic kilometres (120 cu mi) and an estimated mass of 1.5 trillion metric tons (1.7×1012 short tons). If it were to catastrophically slide into the ocean, it could generate a wave with an initial height of about 1,000 metres (3,300 ft) at the island, and a likely height of around 50 metres (200 ft) at the Caribbean and the Eastern North American seaboard when it runs ashore eight or more hours later. Tens of millions of lives could be lost in the cities and/or towns of St. John's, Halifax, Boston, New York, Baltimore, Washington, D.C., Miami, Havana and the rest of the eastern coasts of the United States and Canada, as well as many other cities on the Atlantic coast in Europe, South America and Africa. The likelihood of this happening is a matter of vigorous debate. +Geologists and volcanologists are in general agreement that the initial study was flawed. The current geology does not suggest that a collapse is imminent. Indeed, it seems to be geologically impossible right now – the region conjectured as prone to collapse is too small and too stable to collapse within the next 10,000 years. A closer study of deposits left in the ocean from previous landslides suggests that a landslide would likely occur as a series of smaller collapses rather than a single landslide. A megatsunami does seem possible locally in the distant future as there is geological evidence from past deposits suggesting that a megatsunami occurred with marine material deposited 41 to 188 metres (135 to 617 ft) above sea level between 32,000 and 1.75 million years ago. This seems to have been local to Gran Canaria. +Day and Ward have admitted that their original analysis of the danger was based on several worst case assumptions. A 2008 study examined this scenario and concluded that while it could cause a megatsunami, it would be local to the Canary Islands and would diminish in height, becoming a smaller tsunami by the time it reached the continents as the waves interfered and spread across the oceans. + +=== Hawaii === +Sharp cliffs and associated ocean debris at the Kohala Volcano, Lanai and Molokai indicate that landslides from the flank of the Kilauea and Mauna Loa volcanoes in Hawaii may have triggered past megatsunamis, most recently at 120,000 BP. A tsunami event is also possible, with the tsunami potentially reaching up to about 1 kilometre (3,300 ft) in height. According to the documentary National Geographic's Ultimate Disaster: Tsunami, if a big landslide occurred at Mauna Loa or the Hilina Slump, a 30-metre (98 ft) tsunami would take only thirty minutes to reach Honolulu. There, hundreds of thousands of people could be killed as the tsunami could level Honolulu and travel 25 kilometres (16 mi) inland. Also, the West Coast of America and the entire Pacific Rim could potentially be affected. +Other research suggests that such a single large landslide is not likely. Instead, it would collapse as a series of smaller landslides. +In 2018, shortly after the beginning of the 2018 lower Puna eruption, a National Geographic article responded to such claims with "Will a monstrous landslide off the side of Kilauea trigger a monster tsunami bound for California? Short answer: No." +In the same article, geologist Mika McKinnon stated: + +there are submarine landslides, and submarine landslides do trigger tsunamis, but these are really small, localized tsunamis. They don't produce tsunamis that move across the ocean. In all likelihood, it wouldn't even impact the other Hawaiian islands. +Another volcanologist, Janine Krippner, added: + +People are worried about the catastrophic crashing of the volcano into the ocean. There's no evidence that this will happen. It is slowly – really slowly – moving toward the ocean, but it's been happening for a very long time. +Despite this, evidence suggests that catastrophic collapses do occur on Hawaiian volcanoes and generate local tsunamis. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Megatsunami-9.md b/data/en.wikipedia.org/wiki/Megatsunami-9.md new file mode 100644 index 000000000..a9cbf576b --- /dev/null +++ b/data/en.wikipedia.org/wiki/Megatsunami-9.md @@ -0,0 +1,53 @@ +--- +title: "Megatsunami" +chunk: 10/10 +source: "https://en.wikipedia.org/wiki/Megatsunami" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:36.838495+00:00" +instance: "kb-cron" +--- + +=== Norway === +Although known earlier to the local population, a crack 2 metres (6.6 ft) wide and 500 metres (1,640 ft) in length in the side of the mountain Åkerneset in Norway was rediscovered in 1983 and attracted scientific attention. Located at (62°10'52.28"N, 6°59'35.38"E), it since has widened at a rate of 4 centimetres (1.6 in) per year. Geological analysis has revealed that a slab of rock 62 metres (203 ft) thick and at an elevation stretching from 150 to 900 metres (492 to 2,953 ft) is in motion. Geologists assess that an eventual catastrophic collapse of 18,000,000 to 54,000,000 cubic metres (24,000,000 to 71,000,000 cu yd) of rock into Sunnylvsfjorden is inevitable and could generate megatsunamis of 35 to 100 metres (115 to 328 ft) in height on the fjord′s opposite shore. The waves are expected to strike Hellesylt with a height of 35 to 85 metres (115 to 279 ft), Geiranger with a height of 30 to 70 metres (98 to 230 ft), Tafjord with a height of 14 metres (46 ft), and many other communities in Norway's Sunnmøre district with a height of several metres, and to be noticeable even at Ålesund. The predicted disaster is depicted in the 2015 Norwegian film The Wave. + +== See also == +2004 Indian Ocean earthquake and tsunami +List of tsunamis +Teletsunami +Tsunamis in lakes +Volcanic tsunami + +== References == + +=== Footnotes === + +=== Bibliography === +Day, S.J.; Carracedo, J.C.; Guillou, H.; Gravestock, P. (1999). "Recent structural evolution of the Cumbre Vieja volcano, La Palma, Canary Islands: volcanic rift zone re-configuration as a precursor to flank instability" (PDF). J. Volcanol. Geotherm. Res. 94 (1–4): 135–167. Bibcode:1999JVGR...94..135D. CiteSeerX 10.1.1.544.8128. doi:10.1016/S0377-0273(99)00101-8. +Lander, James F. Tsunamis Affecting Alaska 1737–1996. Boulder, Colorado: NOAA National Geophysical Data Center, September 1996. +Pararas-Carayannis, G. (2002). "Evaluation of the Threat of Mega Tsunami Generation from Postulated Massive Slope Failure of Island Stratovolcanoes on La Palma, Canary Islands, and on The Island of Hawaii, George" (PDF). Science of Tsunami Hazards. 20 (5): 251–277. +Voight, B.; Janda, R.; Glicken, H.; Douglass, P.M. (1983). "Nature and mechanics of the Mount St Helens rockslide-avalanche of 18 May 190". Géotechnique. 33 (10): 243–273. Bibcode:1983Getq...33..243V. doi:10.1680/geot.1983.33.3.243. +Ward, S.N.; Day, S. (2001). "Cumbre Vieja Volcano – Potential collapse and tsunami at La Palma, Canary Islands" (PDF). Geophysical Research Letters. 28 (17): 3397–3400. Bibcode:2001GeoRL..28.3397W. doi:10.1029/2001GL013110. + +== Further reading == +Bonelli Rubio, J.M. (1950). Contribucion al estudio de la erupcion del Nambroque o San Juan. Madrid: Inst. Geografico y Catastral. +BBC 2 TV; 2000. Transcript "Mega-tsunami; Wave of Destruction", Horizon. First screened 21.30 hrs, Thursday, 12 October 2000. +Carracedo, J.C. (1994). "The Canary Islands: an example of structural control on the growth of large oceanic-island volcanoes". J. Volcanol. Geotherm. Res. 60 (3–4): 225–241. Bibcode:1994JVGR...60..225C. doi:10.1016/0377-0273(94)90053-1. +Carracedo, J.C. (1996). "A simple model for the genesis of large gravitational landslide hazards in the Canary Islands". In McGuire, W; Jones; Neuberg, J.P. (eds.). Volcano Instability on the Earth and Other Planets. Special Publication. Vol. 110. London: Geological Society. pp. 125–135. +Carracedo, J.C. (1999). "Growth, Structure, Instability and Collapse of Canarian Volcanoes and Comparisons with Hawaiian Volcanoes". J. Volcanol. Geotherm. Res. 94 (1–4): 1–19. Bibcode:1999JVGR...94....1C. doi:10.1016/S0377-0273(99)00095-5. +Moore, J.G. (1964). Giant Submarine Landslides on the Hawaiian Ridge. US Geologic Survey. pp. D95–8. Professional Paper 501-D. +Pinter, N.; Ishman, S.E. (2008). "Impacts, mega-tsunami, and other extraordinary claims". GSA Today. 18 (1): 37–38. Bibcode:2008GSAT...18a..37P. doi:10.1130/GSAT01801GW.1. +Rihm, R; Krastel, S. & CD109 Shipboard Scientific Party; 1998. "Volcanoes and landslides in the Canaries". National Environment Research Council News. Summer, 16–17. +Siebert, L. (1984). "Large volcanic debris avalanches: characteristics of source areas, deposits and associated eruptions". J. Volcanol. Geotherm. Res. 22 (3–4): 163–197. Bibcode:1984JVGR...22..163S. doi:10.1016/0377-0273(84)90002-7. +Vallely, G.A. (2005). "Volcanic edifice instability and tsunami generation: Montaña Teide, Tenerife, Canary Islands (Spain)". Journal of the Open University Geological Society. 26 (1): 53–64. +Sandom, J.G., 2010, The Wave – A John Decker Thriller, Cornucopia Press, 2010. A thriller in which a megatsunami is intentionally created when a terrorist detonates a nuclear bomb on La Palma in the Canary Islands. +Ortiz, J.R., Bonelli Rubio, J.M., 1951. La erupción del Nambroque (junio-agosto de 1949). Madrid: Talleres del Instituto Geográfico y Catastral, 100 p., 1h. pleg.;23 cm + +== External links == + +Mega Tsunami: history, causes, effects +World's Biggest Tsunami: The largest recorded tsunami with a wave 1720 feet tall in Lituya Bay, Alaska. +Benfield Hazard Research Centre +BBC – Mega-tsunami: Wave of Destruction BBC Two program broadcast 12 October 2000 +La Palma threat "over-hyped" Archived 24 March 2017 at the Wayback Machine, BBC News, 29 October 2004 +Mega-hyped Tsunami story A detailed of analysis demolishing the La Palma Tsunami speculation. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Meroplankton-0.md b/data/en.wikipedia.org/wiki/Meroplankton-0.md new file mode 100644 index 000000000..38434cacd --- /dev/null +++ b/data/en.wikipedia.org/wiki/Meroplankton-0.md @@ -0,0 +1,54 @@ +--- +title: "Meroplankton" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Meroplankton" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:38.143793+00:00" +instance: "kb-cron" +--- + +Meroplankton are a wide variety of aquatic organisms which have both a planktonic stage and at least one other component, such as benthic or nektonic, in their life cycles. Much of the meroplankton consists of larval stages of larger organisms. Meroplankton can be contrasted with holoplankton, which are planktonic organisms that stay in the pelagic zone as plankton throughout their entire life cycle. +After a period of time in the plankton, many meroplankton graduate to the nekton or adopt a benthic (often sessile) lifestyle on the seafloor. The larval stages of benthic invertebrates make up a significant proportion of planktonic communities. The planktonic larval stage is particularly crucial to many benthic invertebrate in order to disperse their young. Depending on the particular species and the environmental conditions, larval or juvenile-stage meroplankton may remain in the pelagic zone for durations ranging from hour to months. +Not all meroplankton are larvae or juvenile stages of larger organisms. Many dinoflagellates are meroplanktonic, undergoing a seasonal cycle of encystment and dormancy in the benthic zone followed by excystment and reproduction in the pelagic zone before returning to the benthic zone once more. There also exist meroplanktonic diatoms; these have a seasonal resting phase below the photic zone and can be found commonly amongst the benthos of lakes and coastal zones. + + +== Spatial distribution == + +Meroplankton species composition depends on spatial distribution and reproductive habits of adults in a given area. Biotic and abiotic factors such as tidal and lunar cycles and availability of food determine adult spawning schedules, in turn, determining subsequent meroplankton populations. Behavioural factors, such as predator avoidance are also important. Freshwater inputs play a key role in meroplankton species composition in estuarine environments. Effects of tides contribute greatly to meroplankton species distribution. One study conducted in a Patagonian Fjord found that species composition of the meroplankton community depended on the seasonally varying input levels from the Baker river as well as vertical and horizontal stratification of the water column. Events such as wind driven upwelling and downwelling also affect meroplankton species distribution. Most species are swept in the direction of the flow of water, either off shore during an upwelling or near shore during a downwelling. Some species, such as bivalve larvae, have the ability to maintain their nearshore position during these events. +The distribution of meroplankton is also highly seasonal. Many meroplankton have short residence times in the pelagic zone which follow seasonal reproduction patterns. The timing of meroplankton population rises can be used as a proxy to estimate the timing of seasonal reproduction of the species in question. + + +== Dispersal == +Survival rate of Meroplankton is critical to successful development of adult organisms. One factor which often determines meroplankton survival is larval dispersal. Most species within the meroplankton community rely on ocean currents for dispersal. Currents play a key role in delivering larval organisms to specific settlement locations, where they are able to transition and mature into adult forms. Organisms which do not make it to the right settlement site are unlikely to complete their lifecycle. + + +== Food availability == +A major factor affecting meroplankton survival is food availability. While some larval or juvenile stage organisms are lecitotrophic, many members of the meroplankton community are heterotrophic. In order to ensure that larvae have sufficient sources of nutrition, many species coordinate larval release with times of algal blooms. This synchronicity between release of larvae and algal blooms often leads to meroplankton making up the largest percentage of the planktonic community during such reproductive periods. It has been demonstrated that certain species are able to commence spawning as they come into contact with phytoplankton cells. These species store embryos in the mantle cavity until they detect algal blooms. This adaptation allows for better larval survival. + + +== Diversity and abundance == +Meroplankton diversity and abundance are affected by many factors. Seasonal and spatial variations are among some of the main causes of such variability. A study which was conducted in Dunkellin Estuary, determined that spawning times of many species are timed to maximise food availability at a particular time of year, while minimising presence of other species which exploit the same food source Diversity and abundance are depth dependent qualities. Generally, shallow coastal waters contain far greater numbers of meroplankton than deep, open ocean waters. Most abundant regions occur at depths between 0 and 200 meters of the water column, where light penetration is highest. Availability of sunlight allows for proliferation of phytoplankton, which serves as one of the major food sources for meroplankton. Deep oceanic waters show significantly lower abundance than shelf regions, due to poor light penetration. + + +== Effects of pollution == +Water and benthos pollution from industrial sources has been demonstrated to have varying effects on biological diversity and survival potential of meroplankton. One study conducted in the Vostok Bay region in Russia, demonstrated that even in the presence of industrial pollutants, most species of meroplankton were able to proliferate almost unaffected. The authors of this study attribute these findings to the fact that meroplankton are transported by ocean currents generally from cleaner open waters inshore. Furthermore, the same study also concluded that even in heavily polluted areas, meroplankton populations were able to reestablish if pollution was brought under control and sufficient time was allowed to pass. However, the rate of recolonization was demonstrated to be notably slow, on average taking about 10 years before the abundance and diversity of meroplankton returned to its original levels. This is in part due to the slow nature of detoxification of benthic sediments, which retain much of the heavy metal pollution. + + +== Meroplankton and climate change == +A study conducted in the North Sea between 1958 and 2005, collected samples of meroplankton using a CPR survey. These samples consisted of larval echinoderms, decapods, bivalves, cirripedes, and ectoprocts. Meroplankton abundance as well as PCI levels (amount of chlorophyll in each sample in relation to sea surface temperature) were examined. Researchers concluded that echinoderm larvae increased in abundance throughout the study, with the largest increase occurring in the Northern and Central regions. Decapod larvae were found to increase in abundance as well, and were found to appear earlier in the year. Bivalve larvae showed an overall decline in abundance. It was also concluded that PCI levels increased throughout the study, particularly during the summer months. It was determined that climate, particularly sea surface temperature, drives meroplankton abundance. Warmer sea surface temperature shortens developmental time of the larvae, increasing their survival rate. + + +== See also == +Plankton +Holoplankton +Ichthyoplankton +Zooplankton +Nekton + + +== References == + + +== Sources == +Meroplankton (Australian Museum) \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Metaphysical_Foundations_of_Natural_Science-0.md b/data/en.wikipedia.org/wiki/Metaphysical_Foundations_of_Natural_Science-0.md new file mode 100644 index 000000000..81b552963 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Metaphysical_Foundations_of_Natural_Science-0.md @@ -0,0 +1,28 @@ +--- +title: "Metaphysical Foundations of Natural Science" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Metaphysical_Foundations_of_Natural_Science" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:46.180367+00:00" +instance: "kb-cron" +--- + +Metaphysical Foundations of Natural Science (German: Metaphysische Anfangsgründe der Naturwissenschaft) is a 1786 book by the philosopher Immanuel Kant. + + +== Summary == +The book is divided into four chapters. The chapters are concerned with the metaphysical foundations of phoronomy (now called kinematics), dynamics, mechanics, and phenomenology. + + +== Reception == +Kant's book was a basic influence on the rise of science departments of the universities in the German-speaking countries in the nineteenth century. +Hans Christian Ørsted wrote "Differential and integral calculus consist of nothing but .. thought experiments and considerations of them. ... In his Metaphysical Foundations of Natural Science, Kant has given us the most beautiful examples of this kind of presentation, without, however, drawing attention to it himself." +Kurt Gödel was influenced by Metaphysische Anfangsgründe der Naturwissenschaft. Gödel studied it while a member of the Vienna Circle. + + +== Notes == + + +== External links == + Works related to The Metaphysical Foundations of Natural Science at Wikisource \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Mid-ocean_ridge-0.md b/data/en.wikipedia.org/wiki/Mid-ocean_ridge-0.md new file mode 100644 index 000000000..a8da7d2ef --- /dev/null +++ b/data/en.wikipedia.org/wiki/Mid-ocean_ridge-0.md @@ -0,0 +1,23 @@ +--- +title: "Mid-ocean ridge" +chunk: 1/3 +source: "https://en.wikipedia.org/wiki/Mid-ocean_ridge" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:39.450676+00:00" +instance: "kb-cron" +--- + +A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics. It typically has a depth of about 2,600 meters (8,500 ft) and rises about 2,000 meters (6,600 ft) above the deepest portion of an ocean basin. This feature is where seafloor spreading takes place along a divergent plate boundary. The rate of seafloor spreading determines the morphology of the crest of the mid-ocean ridge and its width in an ocean basin. +The production of new seafloor and oceanic lithosphere results from mantle upwelling in response to plate separation. The melt rises as magma at the linear weakness between the separating plates, and emerges as lava, creating new oceanic crust and lithosphere upon cooling. +The first discovered mid-ocean ridge was the Mid-Atlantic Ridge, which is a spreading center that bisects the North and South Atlantic basins; its location was the reason for the name "mid-ocean ridge". Most oceanic spreading centers are not in the middle of their hosting ocean basins, but are traditionally called mid-ocean ridges regardless. + +Mid-ocean ridges around the globe are linked by plate tectonic boundaries and the trace of the ridges across the ocean floor appears similar to the seam of a baseball. Most mid-ocean ridges of the world are connected and form the Ocean Ridge, a global mid-oceanic ridge system that is part of every ocean, making it the longest mountain range in the world. The continuous mountain range is 65,000 km (40,400 mi) long (several times longer than the Andes, the longest continental mountain range), and the total length of the oceanic ridge system is 80,000 km (49,700 mi) long. + +== Description == + +=== Morphology === +At the spreading center on a mid-ocean ridge, the depth of the seafloor is approximately 2,600 meters (8,500 ft). On the ridge flanks, the depth of the seafloor (or the height of a location on a mid-ocean ridge above a base-level) is correlated with its age (age of the lithosphere where depth is measured). The depth-age relation can be modeled by the cooling of a lithosphere plate or mantle half-space. A good approximation is that the depth of the seafloor at a location on a spreading mid-ocean ridge is proportional to the square root of the age of the seafloor. The overall shape of ridges results from Pratt isostasy: close to the ridge axis, there is a hot, low-density mantle supporting the oceanic crust. As the oceanic plate cools, away from the ridge axis, the oceanic mantle lithosphere (the colder, denser part of the mantle that, together with the crust, comprises the oceanic plates) thickens, and the density increases. Thus older seafloor is underlain by denser material and is deeper. +Spreading rate is the rate at which an ocean basin widens due to seafloor spreading. Rates can be computed by mapping marine magnetic anomalies that span mid-ocean ridges. As crystallized basalt extruded at a ridge axis cools below Curie points of appropriate iron-titanium oxides, magnetic field directions parallel to the Earth's magnetic field are recorded in those oxides. The orientations of the field preserved in the oceanic crust comprise a record of directions of the Earth's magnetic field with time. Because the field has reversed directions at known intervals throughout its history, the pattern of geomagnetic reversals in the ocean crust can be used as an indicator of age; given the crustal age and distance from the ridge axis, spreading rates can be calculated. +Spreading rates range from approximately 10–200 mm/yr. Slow-spreading ridges such as the Mid-Atlantic Ridge have spread much less far (showing a steeper profile) than faster ridges such as the East Pacific Rise (gentle profile) for the same amount of time and cooling and consequent bathymetric deepening. Slow-spreading ridges (less than 40 mm/yr) generally have large rift valleys, sometimes as wide as 10–20 km (6.2–12.4 mi), and very rugged terrain at the ridge crest that can have relief of up to 1,000 m (3,300 ft). By contrast, fast-spreading ridges (greater than 90 mm/yr) such as the East Pacific Rise lack rift valleys. The spreading rate of the North Atlantic Ocean is ~ 25 mm/yr, while in the Pacific region, it is 80–145 mm/yr. The highest known rate is over 200 mm/yr in the Miocene on the East Pacific Rise. Ridges that spread at rates <20 mm/yr are referred to as ultraslow spreading ridges (e.g., the Gakkel Ridge in the Arctic Ocean and the Southwest Indian Ridge). +The spreading center or axis commonly connects to a transform fault oriented at right angles to the axis. The flanks of mid-ocean ridges are in many places marked by the inactive scars of transform faults called fracture zones. At faster spreading rates the axes often display overlapping spreading centers that lack connecting transform faults. The depth of the axis changes in a systematic way with shallower depths between offsets such as transform faults and overlapping spreading centers dividing the axis into segments. One hypothesis for different along-axis depths is variations in magma supply to the spreading center. Ultra-slow spreading ridges form both magmatic and amagmatic (currently lack volcanic activity) ridge segments without transform faults. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Mid-ocean_ridge-1.md b/data/en.wikipedia.org/wiki/Mid-ocean_ridge-1.md new file mode 100644 index 000000000..fa5feafcc --- /dev/null +++ b/data/en.wikipedia.org/wiki/Mid-ocean_ridge-1.md @@ -0,0 +1,36 @@ +--- +title: "Mid-ocean ridge" +chunk: 2/3 +source: "https://en.wikipedia.org/wiki/Mid-ocean_ridge" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:39.450676+00:00" +instance: "kb-cron" +--- + +=== Volcanism === +Mid-ocean ridges exhibit active volcanism and seismicity. The oceanic crust is in a constant state of 'renewal' at the mid-ocean ridges by the processes of seafloor spreading and plate tectonics. New magma steadily emerges onto the ocean floor and intrudes into the existing ocean crust at and near rifts along the ridge axes. The rocks making up the crust below the seafloor are youngest along the axis of the ridge and age with increasing distance from that axis. New magma of basalt composition emerges at and near the axis because of decompression melting in the underlying Earth's mantle. The isentropic upwelling solid mantle material exceeds the solidus temperature and melts. +The crystallized magma forms a new crust of basalt known as MORB for mid-ocean ridge basalt, and gabbro below it in the lower oceanic crust. Mid-ocean ridge basalt is a tholeiitic basalt and is low in incompatible elements. Hydrothermal vents fueled by magmatic and volcanic heat are a common feature at oceanic spreading centers. A feature of the elevated ridges is their relatively high heat flow values, of about 1–10 μcal/cm2s, or roughly 0.04–0.4 W/m2. +Most crust in the ocean basins is less than 200 million years old, which is much younger than the 4.54 billion year age of Earth. This fact reflects the process of lithosphere recycling into the Earth's mantle during subduction. As the oceanic crust and lithosphere moves away from the ridge axis, the peridotite in the underlying mantle lithosphere cools and becomes more rigid. The crust and the relatively rigid peridotite below it make up the oceanic lithosphere, which sits above the less rigid and viscous asthenosphere. + +== Driving mechanisms == + +The oceanic lithosphere is formed at an oceanic ridge, while the lithosphere is subducted back into the asthenosphere at ocean trenches. Two processes, ridge-push and slab pull, are thought to be responsible for spreading at mid-ocean ridges. Ridge push refers to the gravitational sliding of the ocean plate that is raised above the hotter asthenosphere, thus creating a body force causing sliding of the plate downslope. In slab pull the weight of a tectonic plate being subducted (pulled) below an overlying plate at a subduction zone drags the rest of the plate along behind it. The slab pull mechanism is considered to be contributing more than the ridge push. +A process previously proposed to contribute to plate motion and the formation of new oceanic crust at mid-ocean ridges is the "mantle conveyor" due to deep convection (see image). However, some studies have shown that the upper mantle (asthenosphere) is too plastic (flexible) to generate enough friction to pull the tectonic plate along. Moreover, mantle upwelling that causes magma to form beneath the ocean ridges appears to involve only its upper 400 km (250 mi), as deduced from seismic tomography and observations of the seismic discontinuity in the upper mantle at about 400 km (250 mi). On the other hand, some of the world's largest tectonic plates such as the North American plate and South American plate are in motion, yet only are being subducted in restricted locations such as the Lesser Antilles Arc and Scotia Arc, pointing to action by the ridge push body force on these plates. Computer modeling of the plates and mantle motions suggest that plate motion and mantle convection are not connected, and the main plate driving force is slab pull. + +== Impact on global sea level == +Increased rates of seafloor spreading (i.e. the rate of expansion of the mid-ocean ridge) have caused the global (eustatic) sea level to rise over very long timescales (millions of years). Increased seafloor spreading means that the mid-ocean ridge will then expand and form a broader ridge with decreased average depth, taking up more space in the ocean basin. This displaces the overlying ocean and causes sea levels to rise. +Sealevel change can be attributed to other factors (thermal expansion, ice melting, and mantle convection creating dynamic topography). Over very long timescales, however, it is the result of changes in the volume of the ocean basins which are, in turn, affected by rates of seafloor spreading along the mid-ocean ridges. +The 100 to 170 meters higher sea level of the Cretaceous Period (144–65 Ma) is partly attributed to plate tectonics because thermal expansion and the absence of ice sheets only account for some of the extra sea level. + +== Impact on seawater chemistry and carbonate deposition == + +Seafloor spreading on mid-ocean ridges is a global scale ion-exchange system. Hydrothermal vents at spreading centers introduce various amounts of iron, sulfur, manganese, silicon, and other elements into the ocean, some of which are recycled into the ocean crust. Helium-3, an isotope that accompanies volcanism from the mantle, is emitted by hydrothermal vents and can be detected in plumes within the ocean. +Fast spreading rates will expand the mid-ocean ridge causing basalt reactions with seawater to happen more rapidly. The magnesium/calcium ratio will be lower because more magnesium ions are being removed from seawater and consumed by the rock, and more calcium ions are being removed from the rock and released into seawater. Hydrothermal activity at the ridge crest is efficient in removing magnesium. A lower Mg/Ca ratio favors the precipitation of low-Mg calcite polymorphs of calcium carbonate (calcite seas). +Slow spreading at mid-ocean ridges has the opposite effect and will result in a higher Mg/Ca ratio favoring the precipitation of aragonite and high-Mg calcite polymorphs of calcium carbonate (aragonite seas). +Experiments show that most modern high-Mg calcite organisms would have been low-Mg calcite in past calcite seas, meaning that the Mg/Ca ratio in an organism's skeleton varies with the Mg/Ca ratio of the seawater in which it was grown. +The mineralogy of reef-building and sediment-producing organisms is thus regulated by chemical reactions occurring along the mid-ocean ridge, the rate of which is controlled by the rate of sea-floor spreading. + +== History == + +=== Discovery === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Mid-ocean_ridge-2.md b/data/en.wikipedia.org/wiki/Mid-ocean_ridge-2.md new file mode 100644 index 000000000..83b2b86c6 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Mid-ocean_ridge-2.md @@ -0,0 +1,75 @@ +--- +title: "Mid-ocean ridge" +chunk: 3/3 +source: "https://en.wikipedia.org/wiki/Mid-ocean_ridge" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:39.450676+00:00" +instance: "kb-cron" +--- + +The first indications that a ridge bisects the Atlantic Ocean basin came from the results of the British Challenger expedition in the nineteenth century. Soundings from lines dropped to the seafloor were analyzed by oceanographers Matthew Fontaine Maury and Charles Wyville Thomson and revealed a prominent rise in the seafloor that ran down the Atlantic basin from north to south. Sonar echo sounders confirmed this in the early twentieth century. +It was not until after World War II, when the ocean floor was surveyed in more detail, that the full extent of mid-ocean ridges became known. The Vema, a ship of the Lamont–Doherty Earth Observatory of Columbia University, traversed the Atlantic Ocean, recording echo sounder data on the depth of the ocean floor. A team led by Marie Tharp and Bruce Heezen concluded that there was an enormous mountain chain with a rift valley at its crest, running up the middle of the Atlantic Ocean. Scientists named it the 'Mid-Atlantic Ridge'. Other research showed that the ridge crest was seismically active and fresh lavas were found in the rift valley. Also, crustal heat flow was higher here than elsewhere in the Atlantic Ocean basin. +At first, the ridge was thought to be a feature specific to the Atlantic Ocean. However, as surveys of the ocean floor continued around the world, it was discovered that every ocean contains parts of the mid-ocean ridge system. The German Meteor expedition traced the mid-ocean ridge from the South Atlantic into the Indian Ocean early in the twentieth century. Although the first-discovered section of the ridge system runs down the middle of the Atlantic Ocean, it was found that most mid-ocean ridges are located away from the center of other ocean basins. + +=== Impact of discovery: seafloor spreading === +Alfred Wegener proposed the theory of continental drift in 1912. He stated: "the Mid-Atlantic Ridge ... zone in which the floor of the Atlantic, as it keeps spreading, is continuously tearing open and making space for fresh, relatively fluid and hot sima [rising] from depth". However, Wegener did not pursue this observation in his later works and his theory was dismissed by geologists because there was no mechanism to explain how continents could plow through ocean crust, and the theory became largely forgotten. +Following the discovery of the worldwide extent of the mid-ocean ridge in the 1950s, geologists faced a new task: explaining how such an enormous geological structure could have formed. In the 1960s, geologists discovered and began to propose mechanisms for seafloor spreading. The discovery of mid-ocean ridges and the process of seafloor spreading allowed for Wegener's theory to be expanded so that it included the movement of oceanic crust as well as the continents. Plate tectonics was a suitable explanation for seafloor spreading, and the acceptance of plate tectonics by the majority of geologists resulted in a major paradigm shift in geological thinking. +It is estimated that along Earth's mid-ocean ridges every year 2.7 km2 (1.0 mi2) of new seafloor is formed by this process. With a crustal thickness of 7 km (4.3 mi), this amounts to about 19 km3 (4.6 mi3) of new ocean crust formed every year. + +== List of mid-ocean ridges == + +Aden Ridge – Rift portion in Gulf of Aden +Cocos Ridge – Aseismic ridge within the Cocos plate +Explorer Ridge – Mid-ocean ridge west of British Columbia, Canada +Cocos–Nazca spreading centre – Spreading centre under central eastern Pacific Ocean +Galápagos spreading centre – Western part of the Cocos–Nazca spreading centre +Gorda Ridge – Tectonic spreading center off the northern coast of California and southern Oregon +Juan de Fuca Ridge – Divergent plate boundary off the coast of the Pacific Northwest region of North America +South American–Antarctic Ridge – Mid-ocean ridge in the South Atlantic +Chile Rise – Submarine oceanic ridge in the Pacific OceanPages displaying short descriptions of redirect targets +East Pacific Rise – Ridge on the floor of the Pacific Ocean +Gakkel Ridge – Mid-oceanic ridge under the Arctic Ocean (Mid-Arctic Ridge) +Pacific-Antarctic Ridge – Tectonic plate boundary in the South Pacific OceanPages displaying short descriptions of redirect targets +Central Indian Ridge – North-south-trending mid-ocean ridge in the western Indian Ocean +Carlsberg Ridge – Tectonic plate ridge +Southeast Indian Ridge – Mid-ocean ridge in the southern Indian Ocean +Southwest Indian Ridge – Mid-ocean ridge in the Indian and Atlantic Oceans +Mid-Atlantic Ridge – Atlantic Ocean tectonic plate boundary +Kolbeinsey Ridge – Segment of the Mid-Atlantic Ridge north of Iceland in the Arctic Ocean +Mohns Ridge – Geographical region in the Atlantic basin +Knipovich – Russian zoologistPages displaying short descriptions of redirect targets Ridge (between Greenland and Spitsbergen) +Reykjanes Ridge – Atlantic Ocean tectonic plate boundaryPages displaying short descriptions of redirect targets (south of Iceland) + +=== List of ancient oceanic ridges === +Aegir Ridge – Extinct mid-ocean ridge in the far-northern Atlantic Ocean +Alpha Ridge – Major volcanic ridge under the Arctic Ocean +Galápagos Rise – Fossil divergent boundary +Kula-Farallon Ridge – Ancient mid-ocean ridgePages displaying short descriptions of redirect targets +Mid-Labrador Ridge – Mid-ocean ridge in the Labrador Sea +Pacific-Farallon Ridge – Spreading ridge during the Late CretaceousPages displaying short descriptions of redirect targets +Pacific-Kula Ridge – Former mid-ocean ridgePages displaying short descriptions of redirect targets +Phoenix Ridge – Ancient mid-ocean ridge between the Phoenix and Pacific platesPages displaying short descriptions of redirect targets + +== See also == + +Afar Triangle – Geological depression caused by the Afar triple junction +Aseismic ridge – Geologic feature below some oceans +Geography of Iceland +List of oceanic landforms +Ocean chemistry +Oceanic crust +Petrological Database of the Ocean Floor +Project FAMOUS – first crewed submersible study of the rift valley of the Mid-Atlantic Ridge +RISE project – discovery of black smokers hydrothermal systems on the East Pacific Rise +Slab window – Type of gap in a subducted oceanic plate +Submarine volcano – Underwater vents or fissures in the Earth's surface from which magma can erupt +Vine-Matthews-Morely hypothesis; explains relation of marine magnetic anomalies to seafloor spreading. + +== References == + +== External links == + +An explanation of relevant tectonic forces +Mid-Oceanic ridge, like baseball seam (The Dynamic Earth, USGS) +Ridge2000, Studying Mid-Ocean Ridges from Mantle to Microbe \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Mission b/data/en.wikipedia.org/wiki/Mission new file mode 100644 index 000000000..e69de29bb diff --git a/data/en.wikipedia.org/wiki/Modular_Ocean_Model-0.md b/data/en.wikipedia.org/wiki/Modular_Ocean_Model-0.md new file mode 100644 index 000000000..870eb874c --- /dev/null +++ b/data/en.wikipedia.org/wiki/Modular_Ocean_Model-0.md @@ -0,0 +1,42 @@ +--- +title: "Modular Ocean Model" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Modular_Ocean_Model" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:41.867801+00:00" +instance: "kb-cron" +--- + +The Modular Ocean Model (MOM) is a three-dimensional ocean circulation model designed primarily for studying the ocean climate system. The model is developed and supported primarily by researchers at the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory (NOAA/GFDL) in Princeton, NJ, USA. + + +== Overview == +MOM has traditionally been a level-coordinate ocean model, in which the ocean is divided into boxes whose bottoms are located at fixed depths. Such a representation makes it easy to solve the momentum equations and the well-mixed, weakly stratified layer known as the ocean mixed layer near the ocean surface. However, level coordinate models have problems when it comes to the representation of thin bottom boundary layers (Winton et al., 1998) and thick sea ice. Additionally, because mixing in the ocean interior is largely along lines of constant potential density rather than along lines of constant depth, mixing must be rotated relative to the coordinate grid- a process that can be computationally expensive. By contrast, in codes which represent the ocean in terms of constant-density layers (which represent the flow in the ocean interior much more faithfully)- representation of the ocean mixed layer becomes a challenge. +MOM3, MOM4, and MOM5 are used as a code base for the ocean component of the GFDL coupled models used in the IPCC assessment reports, including the GFDL CM2.X physical climate model series and the ESM2M Earth System Model. Versions of MOM have been used in hundreds of scientific papers by authors around the world. MOM4 is used as the basis for the El Nino prediction system employed by the National Centers for Environmental Prediction. + + +== History == +MOM owes its genesis to work at GFDL in the late 1960s by Kirk Bryan and Michael Cox. This code, along with a version generated at GFDL and UCLA/NCAR by Bert Semtner, is the ancestor of many of the level-coordinate ocean model codes run around the world today. In the late 1980s, Ron Pacanowski, Keith Dixon, and Tony Rosati at GFDL rewrote the Bryan-Cox-Semtner code in a modular form, enabling different options and configurations to be more easily generated and new physical parameterizations to be more easily included. This version, released on December 5, 1990, became known as Modular Ocean Model v1.0 (MOM1). Further development by Pacanowski, aided by Charles Goldberg and encouraged by community feedback, led to the release of v2.0 (MOM2) in 1995. Pacanowski and Stephen Griffies released v3.0 (MOM3) in 1999. Griffies, Matthew Harrison, Rosati and Pacanowski, with considerable input from a scientific community of hundreds of users, resulted in significant evolution of the code released as v4.0 (MOM4) in 2003. An update, v4.1 (MOM4p1) was released by Griffies in 2009, as was the latest version v5.0 (MOM5), which was released in 2012. + + +== See also == + +Geophysical Fluid Dynamics Laboratory + + +== References == + + +== External links == +MOM6 project +MOM5 community website +NOAA/GFDL Modular Ocean Model home page +History of MOM +MOM5 manual +MOM4p1 manual +MOM4 manual +MOM3 manual +MOM2 manual +MOM1 manual +Cox code technical report \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Mycoplankton-0.md b/data/en.wikipedia.org/wiki/Mycoplankton-0.md new file mode 100644 index 000000000..41b5391f5 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Mycoplankton-0.md @@ -0,0 +1,54 @@ +--- +title: "Mycoplankton" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Mycoplankton" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:43.130580+00:00" +instance: "kb-cron" +--- + +Mycoplankton are saprotrophic or parasitic members of the plankton communities of marine and freshwater ecosystems. They are composed of filamentous free-living fungi and yeasts that are associated with planktonic particles or phytoplankton. Similar to bacterioplankton, these aquatic fungi play a significant role in heterotrophic mineralization and nutrient cycling. Mycoplankton can be up to 20 mm in diameter and over 50 mm in length. +In a typical milliliter of seawater, there are approximately 103 to 104 fungal cells. This number is greater in coastal ecosystems and estuaries due to nutritional runoff from terrestrial communities. Aquatic fungi are found in a myriad of ecosystems, from mangroves, to wetlands, to the open ocean. The greatest diversity and number of species of mycoplankton is found in surface waters (< 1000 m), and the vertical profile depends on the abundance of phytoplankton. Furthermore, this difference in distribution may vary between seasons due to nutrient availability. Aquatic fungi survive in a constant oxygen deficient environment, and therefore depend on oxygen diffusion by turbulence and oxygen generated by photosynthetic organisms. + + +== Classification == +There is a large amount of diversity among aquatic fungi. These fungi were traditionally classified using the groupings "lower" and "higher" fungi. +This has frequently been replaced with using the more precise phyla names, with "higher" fungi now roughly corresponding to the Dikarya subkingdom, which has the majority of the mycoplankton +Genome sequencing is a common way to assess and categorize aquatic fungi. Fungi are Eukaryotes, and as such it is often the 18s rDNA which is sequenced. +According to fossil records, fungi date back to the late Proterozoic era, 900-570 million years ago. It is hypothesized that mycoplankton evolved from terrestrial fungi, likely in the Paleozoic era (390 million years ago). It is likely that the transition from terrestrial to aquatic lifestyle has occurred many different times, as many taxa have been found with both terrestrial and marine species. + + +== Biogeochemical contributions == +There are multiple biogeochemical cycles in the Earth's oceans in which Mycoplankton play a role. They are a part of the microbial loop and other forms of nutrient cycling, including the mycoplankton specific mycoflux and mycoloop. + + +=== Cycling of organic nutrients === +Mycoplankton, like all fungi, play an essential roll in the degradation of detritus and organic matter from plants, as well as other larger organisms. By working with other microbial communities, mycoplankton efficiently convert particulate organic matter to dissolved organic matter as part of biogeochemical cycling. Mycoplankton and heterotrophic bacteria mediate carbon, nitrogen, oxygen, and other nutrient fluxes in marine ecosystems. The incorporation of dissolved organic carbon into microbe biomass is what is known as the microbial loop. +Mycoplankton are often found in higher abundances near the surface, as well as in shallow waters. This is indicative of a connection between mycoplankton and the upwelling of organic matter. Phytoplankton communities are also abundant in the euphotic zone, which provides further evidence for the role of Mycoplankton in consumption of organic matter. + + +=== Mycoloop and mycoflux === +Mycoplankton are important in controlling phytoplankton and zooplankton populations. The mycoloop is very similar to the microbial loop, as the basis of both is for microbes to make material accessible to organisms that occupy higher trophic levels. Through the mycoloop phytoplankton are transformed such that they are able to be grazed upon by zooplankton. This function is performed by parasitic marine fungi (mycoplankton). +The mycoflux is understudied, but believed to be a part of carbon capture in aquatic habitats. Functionally, this process involves aquatic fungi breaking down organic matter. + + +=== Benthic shunt === +Another process which mycoplankton take part in is known as the benthic shunt. This process takes place in the benthic zone, the sediments at the bottom of the water. The benthic shunt is typically referred to in relation to freshwater aquatic environments, but the concept is relevant and takes place in marine habitats as well. The benthic shunt is basically energy and nutrient flow as directed by lower trophic level organisms, such as mycoplankton. + + +== Role in food webs == +Due to their significant contributions to nutrient cycling, mycoplankton play a large role in regulation of food webs. Aquatic fungi such as mycoplankton degrade and convert organic matter into other forms. In a way, mycoplankton contributions to aquatic food webs are the biogeochemical services that they perform. The grazer food chain and the microbial food chain are inherently intertwined, as the dissolved organic carbon at the base of the microbial food chain originally comes from material excreted by grazers from the grazer food chain. Not only are the new forms of organic matter more palatable by macro plankton, but the process of conversion releases substrates which support bacterial growth. This in turn allows for the bacteria and macro plankton to support even higher trophic levels. This is a form of bottom-up control of aquatic food webs. + + +== Communities == +While mycoplankton are found in a variety of aquatic environments, their distribution, abundance, and diversity vary throughout these environments. There is typically a greater amount of diversity and a larger abundance of mycoplankton in coastal waters, due to the extra availability of nutrients. There also exists variation in community composition and diversity at different depths. The control factors for the distribution of mycoplankton is thought to be variable. + + +== See also == +Algae – Diverse group of photosynthetic organisms +Biological pump – Carbon capture process in oceans +Marine fungi + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Nekton-0.md b/data/en.wikipedia.org/wiki/Nekton-0.md new file mode 100644 index 000000000..1dd2fa8a9 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Nekton-0.md @@ -0,0 +1,51 @@ +--- +title: "Nekton" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Nekton" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:44.358378+00:00" +instance: "kb-cron" +--- + +Nekton or necton (from the Ancient Greek: νηκτόν, romanized: nekton, lit. 'to swim') is any aquatic organism that can actively and persistently propel itself through a water column (i.e. swim) without touching the bottom. They are generally aquatic animals with powerful tails and appendages (e.g. fins, pleopods, flippers or jets) that make them strong enough swimmers to counter ocean currents, and have mechanisms for sufficient lift and/or buoyancy to prevent sinking. Examples of extant nekton include most fish (especially pelagic fish like tuna and sharks), marine mammals (cetaceans, sirenia and pinnipeds) and reptiles (specifically sea turtles), penguins, coleoid cephalopods (squids and cuttlefish) and several species of decapod crustaceans (specifically prawns, shrimp and krill). +The term was proposed by German biologist Ernst Haeckel to differentiate between the active swimmers in a body of water, and the plankton that are passively carried along by the current. As a guideline, nektonic organisms have a high Reynolds number (greater than 1000) and planktonic organisms a low one (less than 10) . Some organisms begin their life cycle as planktonic eggs and larvae, and transition to nektonic juveniles and adults later in life. This may make distinction difficult when attempting to classify certain plankton-to-nekton species as one or the other. For this reason, some biologists avoid using this term. + + +== History == + +The term was first proposed and used by the German biologist Ernst Haeckel in 1891 in his article Plankton-Studien where he contrasted it with plankton, the aggregate of passively floating, drifting, or somewhat motile organisms present in a body of water, primarily tiny algae and bacteria, small eggs and larvae of marine organisms, and protozoa and other minute consumers. Today it is sometimes considered an obsolete term because it often does not allow for a meaningful quantifiable distinction between these two groups. The colonization of the water column is very important for the evolution of marine animals. The Devonian Nekton Revolution (DNR), well known as the Age of Fishes, accounted for more than eighty-five percent of nekton, which were widespread during the Carboniferous period that took place during the Paleozoic era. Some biologists no longer use the term. + + +== Definition == +As a guideline, nekton are larger and tend to swim largely at biologically high Reynolds numbers (Re) from >1000 to beyond 109, where inertial flows are the rule, and eddies (vortices) are easily shed. On the other hand, plankton are small, and if swimming actively at all, do so at biologically low Reynolds numbers (0.001 to 10), where the viscous behavior of water dominates, and reversible flows are the rule. Organisms such as jellyfish and others are considered plankton when they are very small and swim at low Reynolds numbers, and considered nekton as they grow large enough to swim at high Reynolds numbers. Many animals considered classic examples of nekton (e.g., fishes and squids) start out life as tiny planktonic eggs and larvae and then, it is argued, gradually transition to nektons as they grow bigger and physically stronger. +In 1977, Soviet ichthyologist Yuriy Aleyev (1926-1991) further classified nektons into four natatorial ecomorphological categories: + +Eunekton — "true nekton"; actively swimming pelagic organisms that can locomote against turbulent flows and strong currents, and do not possess morphologies indicating an obligatory connection to terrestrial or benthic environments; typically Re >105; e.g. most fish, decapodiform cephalopods, cetaceans and sirenians; +Planktonekton — “nekton tending towards plankton”; smaller, poorer-swimming pelagic animals that frequently allow themselves to be passively carried by currents but possess moderately-streamlined morphologies more typical of nektic instead of planktonic lifestyles, and do not indicate an obligatory connection to terrestrial or benthic environments; typically Re between 5.0×103 and 105; e.g. lampreys, many forage fishes and most prawns; +Benthonekton — active swimming organisms restricted to near-benthic environments; e.g. chimaeras and nautilids; +Xeronekton — mainly aquatic and actively swimming air-breathing organisms that maintain an obligatory connection to terrestrial environments; e.g. pinnipeds, sea turtles and some aquatic insects. +Later publications on nektons such as Klugs et al. (2010) and Whalen & Briggs (2018) also accepted Aleyev's terminologies, although the latter Yale article more specifically defined nektons (referred to as "nektic taxa") as having laterally compressed and tapering morphologies, and thus renamed benthonekton as eudemersus and reclassified it into the demersal taxa instead of nektons due to their usually dorsoventrally depressed morphologies, while adding nektoxeron (primarily terrestrial but routinely swimming semiaquatic organisms that possess significant aquatic specializations, e.g.frogs, crocodilians, water birds, otters, most aquatic insects, etc.) in replacement. + + +== Oceanic nekton == +Oceanic nekton comprises aquatic animals largely from three clades: + +Vertebrates (phylum Chordata), particularly pelagic fish, cetaceans and sea turtles, form the largest contribution; these animals have endoskeletons made of bones and cartilage and propel themselves via a powerful muscular tail and paddle/fan-shaped appendages such as fins, flippers or webbed feet. +Cephalopods (phylum Mollusca), specifically decapodiform coleoids such as squids and cuttlefish, are pelagic nekton that swim using a combination of jet propulsion and fins. Octopodiform coleoids such as octopuses can also swim quite robustly over short distances, but they are mostly benthic ambush predators using arms to crawl around. +Crustaceans (phylum Arthropoda), especially decapod eucarids such as prawns, shrimp and krill that can swim actively using specialized legs known as pleopods (a.k.a. swimmerets) and a tail fan formed by the telson and uropods. Benthic decapods such as lobsters and crayfish, though normally moving by walking, can also temporarily swim quickly backwards as an escape response. Some crab species can also swim in open waters using their last pair of legs (pereiopods) for paddling. +There are organisms whose initial life stage is identified as planktonic, but when they grow and increase in body size they become gradually more nektonic. Typical examples are the juveniles of fish (fries) and squids, as well as the medusa of jellyfish, which can actively propel itself though generally insufficient to overcome strong currents. + + +== See also == +Neuston (organisms, including microscopic, living at the surface of the water) +Benthos (organisms, including microscopic, living at the bottom of a body of water) +Micronekton + + +== References == + + +== External links == + +Stefan Nehring and Ute Albrecht (1997): "Benthos und das redundante Benthon: Neologismen in der deutschsprachigen Limnologie". In: Lauterbornia H. 31: 17–30, Dinkelscherben, December 1997 E-Text (PDF-Datei) \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Neritic_zone-0.md b/data/en.wikipedia.org/wiki/Neritic_zone-0.md new file mode 100644 index 000000000..b7f63662f --- /dev/null +++ b/data/en.wikipedia.org/wiki/Neritic_zone-0.md @@ -0,0 +1,48 @@ +--- +title: "Neritic zone" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Neritic_zone" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:45.614344+00:00" +instance: "kb-cron" +--- + +The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately 200 meters (660 ft) in depth. +From the point of view of marine biology it forms a relatively stable and well-illuminated environment for marine life, from plankton up to large fish and corals, while physical oceanography sees it as where the oceanic system interacts with the coast. + + +== Definition (marine biology), context, extra terminology == +In marine biology, the neritic zone, also called coastal waters, the coastal ocean or the sublittoral zone, refers to the zone of the ocean where sunlight reaches the ocean floor, that is where the water is never so deep as to take it out of the photic zone. +It extends from the low tide mark to the edge of the continental shelf, with a relatively shallow depth extending to about 200 meters (660 feet). +Above the neritic zone lie the intertidal (or eulittoral) and supralittoral zones; below it the continental slope begins, descending from the continental shelf to the abyssal plain and the pelagic zone. +Within the neritic, marine biologists also identify: + +The infralittoral zone is the algal-dominated zone down to around five metres below the low water mark. +The circalittoral zone is the region beyond the infralittoral, which is dominated by sessile animals such as oysters. +The subtidal zone is the region of the neritic zone which is below the intertidal zone, therefore never exposed to the atmosphere. + + +== Physical characteristics == +The neritic zone is covered with generally well-oxygenated water, receives plenty of sunlight, is relatively stable temperature, has low water pressure and stable salinity levels, making it highly suitable for photosynthetic life. +There are several different areas or zones in the ocean. The area along the bottom of any body of water from the shore to the deepest abyss is called the benthic zone. It is where decomposed organic debris (also known as ocean 'snow') has settled to form a sediment layer. All photosynthetic life needs light to grow and how far out into the ocean light can still penetrate through the water column to the floor or benthic zone is what defines the neritic zone. That photic zone, or area where light can penetrate through the water column, is usually above ~100 meters (~328 feet). Some coastal areas have a long area of shallow water that extends far out beyond the landmass into the water and others, for example islands that have formed from ancient volcanos where the 'shelf' or edge of the land mass is very steep, have a very short neritic zone. + + +== Life forms == +The above characteristics make the neritic zone the location of the majority of sea life. +The result is high primary production by photosynthetic life such as phytoplankton and floating sargassum; +zooplankton, free-floating creatures ranging from microscopic foraminiferans to small fish and shrimp, feed on the phytoplankton (and one another); +both trophic levels in turn form the base of the food chain (or, more properly, web) which supports most of the world's great wild fisheries. +Corals are also mostly found in the neritic zone, where they are more common than in the intertidal zone as they have less change with which to deal. + + +== Definition (physical oceanography) == +In physical oceanography, the sublittoral zone refers to coastal regions with significant tidal flows and energy dissipation, including non-linear flows, internal waves, river outflows and ocean fronts. +As in marine biology, the zone typically extends to the edge of the continental shelf. + + +== See also == +Coastal fish + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_acidification-0.md b/data/en.wikipedia.org/wiki/Ocean_acidification-0.md new file mode 100644 index 000000000..cb15e99c2 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_acidification-0.md @@ -0,0 +1,22 @@ +--- +title: "Ocean acidification" +chunk: 1/9 +source: "https://en.wikipedia.org/wiki/Ocean_acidification" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:46.998480+00:00" +instance: "kb-cron" +--- + +Ocean acidification is the ongoing decrease in the pH of the Earth's ocean. Between 1950 and 2020, the average pH of the ocean surface fell from approximately 8.15 to 8.05. Carbon dioxide emissions from human activities are the primary cause of ocean acidification, with atmospheric carbon dioxide (CO2) levels exceeding 422 ppm (as of 2024). CO2 from the atmosphere is absorbed by the oceans. This chemical reaction produces carbonic acid (H2CO3) which dissociates into a bicarbonate ion (HCO−3) and a hydrogen ion (H+). The presence of free hydrogen ions (H+) lowers the pH of the ocean, increasing acidity (this does not mean that seawater is acidic yet; it is still alkaline, with a pH higher than 8). Marine calcifying organisms, such as mollusks and corals, are especially vulnerable because they rely on calcium carbonate to build shells and skeletons. +A change in pH by 0.1 represents a 26% increase in hydrogen ion concentration in the world's oceans (the pH scale is logarithmic, so a change of one in pH units is equivalent to a tenfold change in hydrogen ion concentration). Sea-surface pH and carbonate saturation states vary depending on ocean depth and location. Colder and higher latitude waters are capable of absorbing more CO2. This can cause acidity to rise, lowering the pH and carbonate saturation levels in these areas. There are several other factors that influence the atmosphere-ocean CO2 exchange, and thus local ocean acidification. These include ocean currents and upwelling zones, proximity to large continental rivers, sea ice coverage, and atmospheric exchange with nitrogen and sulfur from fossil fuel burning and agriculture. +A lower ocean pH has a range of potentially harmful effects for marine organisms. Scientists have observed for example reduced calcification, lowered immune responses, and reduced energy for basic functions such as reproduction. Ocean acidification can impact marine ecosystems that provide food and livelihoods for many people. About one billion people are wholly or partially dependent on the fishing, tourism, and coastal management services provided by coral reefs. Ongoing acidification of the oceans may therefore threaten food chains linked with the oceans. +One of the only solutions that would address the root cause of ocean acidification is reducing carbon dioxide emissions. This is one of the main objectives of climate change mitigation measures. The removal of carbon dioxide from the atmosphere would also help to reverse ocean acidification. In addition, there are some specific ocean-based mitigation methods, for example ocean alkalinity enhancement and enhanced weathering. These strategies are under investigation, but generally have a low technology readiness level and many risks. +Ocean acidification has happened before in Earth's geologic history. The resulting ecological collapse in the oceans had long-lasting effects on the global carbon cycle and climate. + +== Cause == + +In 2021, atmospheric carbon dioxide (CO2) levels of around 415 ppm were around 50% higher than preindustrial concentrations. According to the National Oceanic and Atmospheric Administration in 2023, atmospheric CO2 levels have risen from approximately 280 parts per million (ppm) in the pre-industrial era to over 410 ppm today, primarily due to human activities such as fossil fuel combustion and deforestation. The current elevated levels and rapid growth rates are unprecedented in the past 55 million years of the geological record. The sources of this excess CO2 are clearly established as human driven: they include anthropogenic fossil fuel, industrial, and land-use/land-change emissions. One source of this is fossil fuels, which are burned for energy. When burned, CO2 is released into the atmosphere as a byproduct of combustion, which is a significant contributor to the increasing levels of CO2 in the Earth's atmosphere. The ocean acts as a carbon sink for anthropogenic CO2 and takes up roughly a quarter of total anthropogenic CO2 emissions. However, the additional CO2 in the ocean results in a wholesale shift in seawater acid-base chemistry toward more acidic, lower pH conditions and lower saturation states for carbonate minerals used in many marine organism shells and skeletons. +Accumulated since 1850, the ocean sink holds up to 175±35 gigatons of carbon, with more than two-thirds of this amount (120 Gt C) being taken up by the global ocean since 1960. Over the historical period, the ocean sink increased in pace with the exponential anthropogenic emissions increase. From 1850 until 2022, the ocean has absorbed 26% of total anthropogenic emissions. Emissions during the period 1850–2021 amounted to 670±65 gigatons of carbon and were partitioned among the atmosphere (41%), ocean (26%), and land (31%). +The carbon cycle describes the fluxes of carbon dioxide (CO2) between the oceans, terrestrial biosphere, lithosphere, and atmosphere. The carbon cycle involves both organic compounds such as cellulose and inorganic carbon compounds such as carbon dioxide, carbonate ion, and bicarbonate ion, together referenced as dissolved inorganic carbon (DIC). These inorganic compounds are particularly significant in ocean acidification, as they include many forms of dissolved CO2 present in the Earth's oceans. +When CO2 dissolves, it reacts with water to form a balance of ionic and non-ionic chemical species: dissolved free carbon dioxide (CO2(aq)), carbonic acid (H2CO3), bicarbonate (HCO−3) and carbonate (CO2−3). The ratio of these species depends on factors such as seawater temperature, pressure and salinity (as shown in a Bjerrum plot). These different forms of dissolved inorganic carbon are transferred from an ocean's surface to its interior by the ocean's solubility pump. The resistance of an area of ocean to absorbing atmospheric CO2 is known as the Revelle factor. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_acidification-1.md b/data/en.wikipedia.org/wiki/Ocean_acidification-1.md new file mode 100644 index 000000000..2230450c0 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_acidification-1.md @@ -0,0 +1,95 @@ +--- +title: "Ocean acidification" +chunk: 2/9 +source: "https://en.wikipedia.org/wiki/Ocean_acidification" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:46.998480+00:00" +instance: "kb-cron" +--- + +== Main effects == +The ocean's chemistry is changing due to the uptake of anthropogenic carbon dioxide (CO2). Ocean pH, carbonate ion concentrations ([CO32−]), and calcium carbonate mineral saturation states (Ω) have been declining as a result of the uptake of approximately 30% of the anthropogenic carbon dioxide emissions over the past 270 years (since around 1750). This process, commonly referred to as "ocean acidification", is making it harder for marine calcifiers to build a shell or skeletal structure, endangering coral reefs and the broader marine ecosystems. +Ocean acidification has been called the "evil twin of global warming" and "the other CO2 problem". Increased ocean temperatures and oxygen loss act concurrently with ocean acidification and constitute the "deadly trio" of climate change pressures on the marine environment. The impacts of this will be most severe for coral reefs and other shelled marine organisms, as well as those populations that depend on the ecosystem services they provide. + +=== Reduction in pH value === + +Dissolving CO2 in seawater increases the hydrogen ion (H+) concentration in the ocean, and thus decreases ocean pH, as follows: +In shallow coastal and shelf regions, a number of factors interplay to affect air-ocean CO2 exchange and resulting pH change. These include biological processes, such as photosynthesis and respiration, as well as water upwelling. Also, ecosystem metabolism in freshwater sources reaching coastal waters can lead to large, but local, pH changes. +Freshwater bodies also appear to be acidifying, although this is a more complex and less obvious phenomenon. +The absorption of CO2 from the atmosphere does not affect the ocean's alkalinity. This is important to know in this context as alkalinity is the capacity of water to resist acidification. Ocean alkalinity enhancement has been proposed as one option to add alkalinity to the ocean and therefore buffer against pH changes. + +=== Decreased calcification in marine organisms === + +Changes in ocean chemistry can have extensive direct and indirect effects on organisms and their habitats. One of the most important repercussions of increasing ocean acidity relates to the production of shells out of calcium carbonate (CaCO3). This process is called calcification and is important to the biology and survival of a wide range of marine organisms. Calcification involves the precipitation of dissolved ions into solid CaCO3 structures, structures for many marine organisms, such as coccolithophores, foraminifera, crustaceans, mollusks, etc. After they are formed, these CaCO3 structures are vulnerable to dissolution unless the surrounding seawater contains saturating concentrations of carbonate ions (CO2−3). +Very little of the extra carbon dioxide that is added into the ocean remains as dissolved carbon dioxide. The majority dissociates into additional bicarbonate and free hydrogen ions. The increase in hydrogen is larger than the increase in bicarbonate, creating an imbalance in the reaction: + +HCO−3 ⇌ CO2−3 + H+ +To maintain chemical equilibrium, some of the carbonate ions already in the ocean combine with some of the hydrogen ions to make further bicarbonate. Thus the ocean's concentration of carbonate ions is reduced, removing an essential building block for marine organisms to build shells, or calcify: + +Ca2+ + CO2−3 ⇌ CaCO3 +The increase in concentrations of dissolved carbon dioxide and bicarbonate, and reduction in carbonate, are shown in the Bjerrum plot. +Disruption of the food chain is also a possible effect as many marine organisms rely on calcium carbonate-based organisms at the base of the food chain for food and habitat. This can potentially have detrimental effects throughout the food web and potentially lead to a decline in availability of fish stocks which would have an impact on human livelihoods. + +=== Decrease in saturation state === + +The saturation state (known as Ω) of seawater for a mineral is a measure of the thermodynamic potential for the mineral to form or to dissolve, and for calcium carbonate is described by the following equation: + + + + + + Ω + + = + + + + + [ + + + Ca + + 2 + + + + + + ] + + + [ + + + CO + + 3 + + + 2 + − + + + + ] + + + + K + + s + p + + + + + + + {\displaystyle {\Omega }={\frac {\left[{\ce {Ca^2+}}\right]\left[{\ce {CO3^2-}}\right]}{K_{sp}}}} + + +Here Ω is the product of the concentrations (or activities) of the reacting ions that form the mineral (Ca2+ and CO32−), divided by the apparent solubility product at equilibrium (Ksp), that is, when the rates of precipitation and dissolution are equal. In seawater, dissolution boundary is formed as a result of temperature, pressure, and depth, and is known as the saturation horizon. Above this saturation horizon, Ω has a value greater than 1, and CaCO3 does not readily dissolve. Most calcifying organisms live in such waters. Below this depth, Ω has a value less than 1, and CaCO3 will dissolve. The carbonate compensation depth is the ocean depth at which carbonate dissolution balances the supply of carbonate to sea floor, therefore sediment below this depth will be void of calcium carbonate. Increasing CO2 levels, and the resulting lower pH of seawater, decreases the concentration of CO32− and the saturation state of CaCO3 therefore increasing CaCO3 dissolution. +Calcium carbonate most commonly occurs in two common polymorphs (crystalline forms): aragonite and calcite. Aragonite is much more soluble than calcite, so the aragonite saturation horizon, and aragonite compensation depth, is always nearer to the surface than the calcite saturation horizon. This also means that those organisms that produce aragonite may be more vulnerable to changes in ocean acidity than those that produce calcite. Ocean acidification and the resulting decrease in carbonate saturation states raise the saturation horizons of both forms closer to the surface. This decrease in saturation state is one of the main factors leading to decreased calcification in marine organisms because the inorganic precipitation of CaCO3 is directly proportional to its saturation state and calcifying organisms exhibit stress in waters with lower saturation states. + +=== Natural variability and climate feedbacks === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_acidification-2.md b/data/en.wikipedia.org/wiki/Ocean_acidification-2.md new file mode 100644 index 000000000..477e78af4 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_acidification-2.md @@ -0,0 +1,25 @@ +--- +title: "Ocean acidification" +chunk: 3/9 +source: "https://en.wikipedia.org/wiki/Ocean_acidification" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:46.998480+00:00" +instance: "kb-cron" +--- + +Already now large quantities of water undersaturated in aragonite are upwelling close to the Pacific continental shelf area of North America, from Vancouver to Northern California. These continental shelves play an important role in marine ecosystems, since most marine organisms live or are spawned there. Other shelf areas may be experiencing similar effects. +At depths of 1000s of meters in the ocean, calcium carbonate shells begin to dissolve as increasing pressure and decreasing temperature shift the chemical equilibria controlling calcium carbonate precipitation. The depth at which this occurs is known as the carbonate compensation depth. Ocean acidification will increase such dissolution and shallow the carbonate compensation depth on timescales of tens to hundreds of years. Zones of downwelling are being affected first. +In the North Pacific and North Atlantic, saturation states are also decreasing (the depth of saturation is getting more shallow). Ocean acidification is progressing in the open ocean as the CO2 travels to deeper depth as a result of ocean mixing. In the open ocean, this causes carbonate compensation depths to become more shallow, meaning that dissolution of calcium carbonate will occur below those depths. In the North Pacific these carbonate saturations depths are shallowing at a rate of 1–2 m/year. +It is expected that ocean acidification in the future will lead to a significant decrease in the burial of carbonate sediments for several centuries, and even the dissolution of existing carbonate sediments. + +== Measured and estimated values == + +=== Present day and recent history === + +Between 1950 and 2020, the average pH value of the ocean surface is estimated to have decreased from approximately 8.15 to 8.05. This represents an increase of around 26% in hydrogen ion concentration in the world's oceans (the pH scale is logarithmic, so a change of one in pH unit is equivalent to a tenfold change in hydrogen ion concentration). For example, in the 15-year period 1995–2010 alone, acidity has increased 6 percent in the upper 100 meters of the Pacific Ocean from Hawaii to Alaska. +The IPCC Sixth Assessment Report in 2021 stated that "present-day surface pH values are unprecedented for at least 26,000 years and current rates of pH change are unprecedented since at least that time. The pH value of the ocean interior has declined over the last 20–30 years everywhere in the global ocean. The report also found that "pH in open ocean surface water has declined by about 0.017 to 0.027 pH units per decade since the late 1980s". +The rate of decline differs by region. This is due to complex interactions between different types of forcing mechanisms: "In the tropical Pacific, its central and eastern upwelling zones exhibited a faster pH decline of minus 0.022 to minus 0.026 pH unit per decade." This is thought to be "due to increased upwelling of CO2-rich sub-surface waters in addition to anthropogenic CO2 uptake". Some regions exhibited a slower acidification rate: a pH decline of minus 0.010 to minus 0.013 pH unit per decade has been observed in warm pools in the western tropical Pacific. +The rate at which ocean acidification will occur may be influenced by the rate of surface ocean warming, because warm waters will not absorb as much CO2. Therefore, greater seawater warming could limit CO2 absorption and lead to a smaller change in pH for a given increase in CO2. The difference in changes in temperature between basins is one of the main reasons for the differences in acidification rates in different localities. +Current rates of ocean acidification have been likened to the greenhouse event at the Paleocene–Eocene boundary (about 56 million years ago), when surface ocean temperatures rose by 5–6 °C. In that event, surface ecosystems experienced a variety of impacts, but bottom-dwelling organisms in the deep ocean actually experienced a major extinction. Currently, the rate of carbon addition to the atmosphere-ocean system is about ten times the rate that occurred at the Paleocene–Eocene boundary. +Extensive observational systems are now in place or being built for monitoring seawater CO2 chemistry and acidification for both the global open ocean and some coastal systems. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_acidification-3.md b/data/en.wikipedia.org/wiki/Ocean_acidification-3.md new file mode 100644 index 000000000..ceab0f645 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_acidification-3.md @@ -0,0 +1,32 @@ +--- +title: "Ocean acidification" +chunk: 4/9 +source: "https://en.wikipedia.org/wiki/Ocean_acidification" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:46.998480+00:00" +instance: "kb-cron" +--- + +=== Geologic past === +Ocean acidification has occurred previously in Earth's history. It happened during the Capitanian mass extinction, at the end-Permian extinction, during the end-Triassic extinction, and during the Cretaceous–Palaeogene extinction event. +Three of the big five mass extinction events in the geologic past were associated with a rapid increase in atmospheric carbon dioxide, probably due to volcanism and/or thermal dissociation of marine gas hydrates. Elevated CO2 levels impacted biodiversity. Decreased CaCO3 saturation due to seawater uptake of volcanogenic CO2 has been suggested as a possible kill mechanism during the marine mass extinction at the end of the Triassic. The end-Triassic biotic crisis is still the most well-established example of a marine mass extinction due to ocean acidification, because (a) carbon isotope records suggest enhanced volcanic activity that decreased the carbonate sedimentation which reduced the carbonate compensation depth and the carbonate saturation state, and a marine extinction coincided precisely in the stratigraphic record, and (b) there was pronounced selectivity of the extinction against organisms with thick aragonitic skeletons, which is predicted from experimental studies. Ocean acidification has also been suggested as a one cause of the end-Permian mass extinction and the end-Cretaceous crisis. Overall, multiple climatic stressors, including ocean acidification, was likely the cause of geologic extinction events. +The most notable example of ocean acidification is the Paleocene–Eocene Thermal Maximum (PETM), which occurred approximately 56 million years ago when massive amounts of carbon entered the ocean and atmosphere, and led to the dissolution of carbonate sediments across many ocean basins. Relatively new geochemical methods of testing for pH in the past indicate the pH dropped 0.3 units across the PETM. One study that solves the marine carbonate system for saturation state shows that it may not change much over the PETM, suggesting the rate of carbon release at our best geological analogy was much slower than human-induced carbon emissions. However, stronger proxy methods to test for saturation state are needed to assess how much this pH change may have affected calcifying organisms. + +== Predicted future values == + +Importantly, the rate of change in ocean acidification is much higher than in the geological past. This faster change prevents organisms from gradually adapting, and prevents climate cycle feedbacks from kicking in to mitigate ocean acidification. Ocean acidification is now on a path to reach lower pH levels than at any other point in the last 300 million years. The rate of ocean acidification (i.e. the rate of change in pH value) is also estimated to be unprecedented over that same time scale. These expected changes are considered unprecedented in the geological record. In combination with other ocean biogeochemical changes, this drop in pH value could undermine the functioning of marine ecosystems and disrupt the provision of many goods and services associated with the ocean, beginning as early as 2100. +The extent of further ocean chemistry changes, including ocean pH, will depend on climate change mitigation efforts taken by nations and their governments. Different scenarios of projected socioeconomic global changes are modelled by using the Shared Socioeconomic Pathways (SSP) scenarios. +Under a very high emission scenario (SSP5-8.5), model projections estimate that surface ocean pH could decrease by as much as 0.44 units by the end of this century, compared to the end of the 19th century. This would mean a pH as low as about 7.7, and represents a further increase in H+ concentrations of two to four times beyond the increase to date. + +== Impacts on oceanic calcifying organisms == + +=== Complexity of research findings === +The full ecological consequences of the changes in calcification due to ocean acidification are complex but it appears likely that many calcifying species will be adversely affected by ocean acidification. Increasing ocean acidification makes it more difficult for shell-accreting organisms to access carbonate ions, essential for the production of their hard exoskeletal shell. Oceanic calcifying organism span the food chain from autotrophs to heterotrophs and include organisms such as coccolithophores, corals, foraminifera, echinoderms, crustaceans and molluscs. +Overall, all marine ecosystems on Earth will be exposed to changes in acidification and several other ocean biogeochemical changes. Ocean acidification may force some organisms to reallocate resources away from productive endpoints in order to maintain calcification. For example, the oyster Magallana gigas is recognized to experience metabolic changes alongside altered calcification rates due to energetic tradeoffs resulting from pH imbalances. +Under normal conditions, calcite and aragonite are stable in surface waters since the carbonate ions are supersaturated with respect to seawater. However, as ocean pH falls, the concentration of carbonate ions also decreases. Calcium carbonate thus becomes undersaturated, and structures made of calcium carbonate are vulnerable to calcification stress and dissolution. In particular, studies show that corals, coccolithophores, coralline algae, foraminifera, shellfish and pteropods experience reduced calcification or enhanced dissolution when exposed to elevated CO2. Even with active marine conservation practices it may be impossible to bring back many previous shellfish populations. +Some studies have found different responses to ocean acidification, with coccolithophore calcification and photosynthesis both increasing under elevated atmospheric pCO2, and an equal decline in primary production and calcification in response to elevated CO2, or the direction of the response varying between species. +Similarly, the sea star, Pisaster ochraceus, shows enhanced growth in waters with increased acidity. +Reduced calcification from ocean acidification may affect the ocean's biologically driven sequestration of carbon from the atmosphere to the ocean interior and seafloor sediment, weakening the so-called biological pump. Seawater acidification could also reduce the size of Antarctic phytoplankton, making them less effective at storing carbon. Such changes are being increasingly studied and synthesized through the use of physiological frameworks, including the Adverse Outcome Pathway (AOP) framework. + +=== Coccolithophores === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_acidification-4.md b/data/en.wikipedia.org/wiki/Ocean_acidification-4.md new file mode 100644 index 000000000..accb6e3b6 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_acidification-4.md @@ -0,0 +1,40 @@ +--- +title: "Ocean acidification" +chunk: 5/9 +source: "https://en.wikipedia.org/wiki/Ocean_acidification" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:46.998480+00:00" +instance: "kb-cron" +--- + +A coccolithophore is a unicellular, eukaryotic phytoplankton (alga). Understanding calcification changes in coccolithophores may be particularly important because a decline in the coccolithophores may have secondary effects on climate: it could contribute to global warming by decreasing the Earth's albedo via their effects on oceanic cloud cover. A study in 2008 examined a sediment core from the North Atlantic and found that the species composition of coccolithophorids remained unchanged over the past 224 years (1780 to 2004). But the average coccolith mass had increased by 40% during the same period. + +=== Corals === + +Warm water corals are clearly in decline, with losses of 50% over the last 30–50 years due to multiple threats from ocean warming, ocean acidification, pollution and physical damage from activities such as fishing, and these pressures are expected to intensify. +The fluid in the internal compartments (the coelenteron) where corals grow their exoskeleton is also extremely important for calcification growth. When the saturation state of aragonite in the external seawater is at ambient levels, the corals will grow their aragonite crystals rapidly in their internal compartments, hence their exoskeleton grows rapidly. If the saturation state of aragonite in the external seawater is lower than the ambient level, the corals have to work harder to maintain the right balance in the internal compartment. When that happens, the process of growing the crystals slows down, and this slows down the rate of how much their exoskeleton is growing. Depending on the aragonite saturation state in the surrounding water, the corals may halt growth because pumping aragonite into the internal compartment will not be energetically favorable. Under the current progression of carbon emissions, around 70% of North Atlantic cold-water corals will be living in corrosive waters by 2050–60. +Acidified conditions primarily reduce the coral's capacity to build dense exoskeletons, rather than affecting the linear extension of the exoskeleton. The density of some species of corals could be reduced by over 20% by the end of this century. +An in situ experiment, conducted on a 400 m2 patch of the Great Barrier Reef, to decrease seawater CO2 level (raise pH) to near the preindustrial value showed a 7% increase in net calcification. A similar experiment to raise in situ seawater CO2 level (lower pH) to a level expected soon after the 2050 found that net calcification decreased 34%. +However, a field study of the coral reef in Queensland and Western Australia from 2007 to 2012 found that corals are more resistant to the environmental pH changes than previously thought, due to internal homeostasis regulation; this makes thermal change (marine heatwaves), which leads to coral bleaching, rather than acidification, the main factor for coral reef vulnerability due to climate change. + +==== Studies at carbon dioxide seep sites ==== +In some places carbon dioxide bubbles out from the sea floor, locally changing the pH and other aspects of the chemistry of the seawater. Studies of these carbon dioxide seeps have documented a variety of responses by different organisms. Coral reef communities located near carbon dioxide seeps are of particular interest because of the sensitivity of some corals species to acidification. In Papua New Guinea, declining pH caused by carbon dioxide seeps is associated with declines in coral species diversity. However, in Palau carbon dioxide seeps are not associated with reduced species diversity of corals, although bioerosion of coral skeletons is much higher at low pH sites. + +=== Pteropods and brittle stars === +Pteropods and brittle stars both form the base of the Arctic food webs and are both seriously damaged from acidification. Pteropods shells dissolve with increasing acidification and the brittle stars lose muscle mass when re-growing appendages. For pteropods to create shells they require aragonite which is produced through carbonate ions and dissolved calcium and strontium. Pteropods are severely affected because increasing acidification levels have steadily decreased the amount of water supersaturated with carbonate. The degradation of organic matter in Arctic waters has amplified ocean acidification; some Arctic waters are already undersaturated with respect to aragonite. +The brittle star's eggs die within a few days when exposed to expected conditions resulting from Arctic acidification. Similarly, when exposed in experiments to pH reduced by 0.2 to 0.4, larvae of a temperate brittle star, a relative of the common sea star, fewer than 0.1 percent survived more than eight days. + +== Other impacts on ecosystems == + +=== Other biological impacts === +Aside from the slowing and/or reversal of calcification, organisms may suffer other adverse effects, either indirectly through negative impacts on food resources, or directly as reproductive or physiological effects. For example, the elevated oceanic levels of CO2 may produce CO2-induced acidification of body fluids, known as hypercapnia. +Increasing acidity has been observed to reduce metabolic rates in jumbo squid and depress the immune responses of blue mussels. +Atlantic longfin squid eggs took longer to hatch in acidified water, and the squid's statolith was smaller and malformed in animals placed in sea water with a lower pH. However, these studies are ongoing and there is not yet a full understanding of these processes in marine organisms or ecosystems. + +==== Acoustic properties ==== +Another potential route to ecosystem impacts is through bioacoustics. This may occur as ocean acidification can alter the acoustic properties of seawater, allowing sound to propagate further, and increasing ocean noise. This impacts all animals that use sound for echolocation or communication. + +==== Algae and seagrasses ==== + +Another possible effect would be an increase in harmful algal bloom events, which could contribute to the accumulation of toxins (domoic acid, brevetoxin, saxitoxin) in small organisms such as anchovies and shellfish, in turn increasing occurrences of amnesic shellfish poisoning, neurotoxic shellfish poisoning and paralytic shellfish poisoning. Although algal blooms can be harmful, other beneficial photosynthetic organisms may benefit from increased levels of carbon dioxide. Most importantly, seagrasses will benefit. Research found that as seagrasses increased their photosynthetic activity, calcifying algae's calcification rates rose, likely because localized photosynthetic activity absorbed carbon dioxide and elevated local pH. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_acidification-5.md b/data/en.wikipedia.org/wiki/Ocean_acidification-5.md new file mode 100644 index 000000000..74ac68fe0 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_acidification-5.md @@ -0,0 +1,31 @@ +--- +title: "Ocean acidification" +chunk: 6/9 +source: "https://en.wikipedia.org/wiki/Ocean_acidification" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:46.998480+00:00" +instance: "kb-cron" +--- + +==== Fish larvae ==== +Ocean acidification can also have effects on marine fish larvae. It internally affects their olfactory systems, which is a crucial part of their early development. Orange clownfish larvae mostly live on oceanic reefs that are surrounded by vegetative islands. Larvae are known to use their sense of smell to detect the differences between reefs surrounded by vegetative islands and reefs not surrounded by vegetative islands. Clownfish larvae need to be able to distinguish between these two destinations to be able to find a suitable area for their growth. Another use for marine fish olfactory systems is to distinguish between their parents and other adult fish, in order to avoid inbreeding. +In an experimental aquarium facility, clownfish were sustained in non-manipulated seawater with pH 8.15 ± 0.07, which is similar to our current ocean's pH. To test for effects of different pH levels, the seawater was modified to two other pH levels, which corresponded with climate change models that predict future atmospheric CO2 levels. In the year 2100 the model projects possible CO2 levels of 1,000 ppm, which correlates with the pH of 7.8 ± 0.05. +This experiment showed that when larvae are exposed to a pH of 7.8 ± 0.05 their reaction to environmental cues differs drastically from their reaction to cues at pH equal to current ocean levels. At pH 7.6 ± 0.05 larvae had no reaction to any type of cue. However, a meta-analysis published in 2022 found that the effect sizes of published studies testing for ocean acidification effects on fish behavior have declined by an order of magnitude over the past decade, and have been negligible for the past five years. +Eel embryos, a "critically endangered" species yet profound in aquaculture, are also being affected by ocean acidification, specifically the European eel. Although they spend most of their lives in fresh water, usually in rivers, streams, or estuaries, they go to spawn and die in the Sargasso Sea. Here is where European eels are experiencing the effects of acidification in one of their key life stages. +Fish embryos and larvae are usually more sensitive to pH changes than adults, as organs for pH regulation are not full developed. Because of this, European eel embryos are more vulnerable to changes in pH in the Sargasso Sea. A study of the European Eel in the Sargasso Sea was conducted in 2021 to analyze the specific effects of ocean acidification on embryos. The study found that exposure to predicted end-of-century ocean pCO2 conditions may affect normal development of this species in nature during sensitive early life history stages with limited physiological response capacities, while extreme acidification would negatively influence embryonic survival and development under hatchery conditions. + +=== Compounded effects of acidification, warming and deoxygenation === + +There is a substantial body of research showing that a combination of ocean acidification and elevated ocean temperature have a compounded effect on marine life and the ocean environment. This effect far exceeds the individual harmful impact of either. In addition, ocean warming, along with increased productivity of phytoplankton from higher CO2 levels exacerbates ocean deoxygenation. Deoxygenation of ocean waters is an additional stressor on marine organisms that increases ocean stratification therefore limiting nutrients over time and reducing biological gradients. +Meta analyses have quantified the direction and magnitude of the harmful effects of combined ocean acidification, warming and deoxygenation on the ocean. These meta-analyses have been further tested by mesocosm studies that simulated the interaction of these stressors and found a catastrophic effect on the marine food web: thermal stress more than negates any primary producer to herbivore increase in productivity from elevated CO2. + +== Impacts on the economy and societies == +The increase of ocean acidity decelerates the rate of calcification in salt water, leading to smaller and slower growing coral reefs which supports approximately 25% of marine life. Impacts are far-reaching from fisheries and coastal environments down to the deepest depths of the ocean. The increase in ocean acidity is not only killing the coral, but also the wildly diverse population of marine inhabitants which coral reefs support. + +=== Fishing and tourism industry === +The threat of acidification includes a decline in commercial fisheries and the coast-based tourism industry. Several ocean goods and services are likely to be undermined by future ocean acidification potentially affecting the livelihoods of some 470 to 870 million of the world's poorest people, depending upon the greenhouse gas emission scenario. +Some 1 billion people are completely or partially dependent on the fishing, tourism, and coastal management services provided by coral reefs. Ongoing acidification of the oceans may therefore threaten future food chains linked with the oceans. + +==== Arctic ==== +In the Arctic, commercial fisheries are threatened because acidification harms calcifying organisms which form the base of the Arctic food webs (pteropods and brittle stars, see above). Acidification threatens Arctic food webs from the base up. Arctic food webs are considered simple, meaning there are few steps in the food chain from small organisms to larger predators. For example, pteropods are "a key prey item of a number of higher predators – larger plankton, fish, seabirds, whales". Both pteropods and sea stars serve as a substantial food source and their removal from the simple food web would pose a serious threat to the whole ecosystem. The effects on the calcifying organisms at the base of the food webs could potentially destroy fisheries. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_acidification-6.md b/data/en.wikipedia.org/wiki/Ocean_acidification-6.md new file mode 100644 index 000000000..ec517ad60 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_acidification-6.md @@ -0,0 +1,37 @@ +--- +title: "Ocean acidification" +chunk: 7/9 +source: "https://en.wikipedia.org/wiki/Ocean_acidification" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:46.998480+00:00" +instance: "kb-cron" +--- + +==== United Kingdom commercial fisheries ==== +The shellfish industry is an important part of the United Kingdom economy. In 2013, the shellfish industry contributed 37% of total landings by value. England and Scotland are the highest producers of shellfish within the United Kingdom. It has been found that annually fishers catch 66,000 t and 61,000 t. In terms of value, the wild-captured shellfish are worth 203 million pounds per year. However, ocean acidification is causing a decrease in the growth of many shellfish species. This is causing a drastic economic loss in the United Kingdom economy. +It is predicted that by 2100 there will be an economy-wide economic loss of shellfish production in the United Kingdom. The direct potential loss ranges from 14 to 28 percent of fishery output. That is a total loss of about 23 to 88 million pounds. The financial losses vary regionally due to different patterns of wild-caught shellfish and the exploitation of species with differing sensitivities to ocean acidification. Shellfish resources in the United Kingdom will require regional, national, or international solutions to reduce the impacts of ocean acidification on shellfish species and stabilize the economy. + +==== US commercial fisheries ==== + +The value of fish caught from US commercial fisheries in 2007 was valued at $3.8 billion and of that 73% was derived from calcifiers and their direct predators. Other organisms are directly harmed as a result of acidification. For example, decrease in the growth of marine calcifiers such as the American lobster, ocean quahog, and scallops means there is less shellfish meat available for sale and consumption. Red king crab fisheries are also at a serious threat because crabs are also calcifiers. Baby red king crab when exposed to increased acidification levels experienced 100% mortality after 95 days. In 2006, red king crab accounted for 23% of the total guideline harvest levels and a serious decline in red crab population would threaten the crab harvesting industry. + +== Possible responses == + +=== Climate change mitigation === + +Reducing carbon dioxide emissions (i.e. climate change mitigation measures) is the only solution that addresses the root cause of ocean acidification. For example, some mitigation measures focus on carbon dioxide removal (CDR) from the atmosphere (e.g. direct air capture (DAC), bioenergy with carbon capture and storage (BECCS)). These would also slow the rate of acidification. +Approaches that remove carbon dioxide from the ocean include ocean nutrient fertilization, artificial upwelling/downwelling, seaweed farming, ecosystem recovery, ocean alkalinity enhancement, enhanced weathering and electrochemical processes. All of these methods use the ocean to remove CO2 from the atmosphere to store it in the ocean. These methods could assist with mitigation but they can have side-effects on marine life. The research field for all CDR methods has grown a lot since 2019. +In total, "ocean-based methods have a combined potential to remove 1–100 gigatons of CO2 per year". Their costs are in the order of US$40–500 per ton of CO2. For example, enhanced weathering could remove 2–4 gigatons of CO2 per year. This technology comes with a cost of US$50–200 per ton of CO2. + +=== Carbon removal technologies which add alkalinity === + +Some carbon removal techniques add alkalinity to the ocean and therefore immediately buffer pH changes which might help the organisms in the region that the extra alkalinity is added to. The two technologies that fall into this category are ocean alkalinity enhancement and electrochemical methods. Eventually, due to diffusion, that alkalinity addition will be quite small to distant waters. This is why the term local ocean acidification mitigation is used. Both of these technologies have the potential to operate on a large scale and to be efficient at removing carbon dioxide. However, they are expensive, have many risks and side effects and currently have a low technology readiness level. + +==== Ocean alkalinity enhancement ==== +Ocean alkalinity enhancement (OAE) is a proposed "carbon dioxide removal (CDR) method that involves deposition of alkaline minerals or their dissociation products at the ocean surface". The process would increase surface total alkalinity. It would work to increase ocean absorption of CO2. The process involves increasing the amount of bicarbonate (HCO3-) through accelerated weathering (enhanced weathering) of rocks (silicate, limestone and quicklime). This process mimics the silicate-carbonate cycle. The CO2 either becomes bicarbonate, remaining in that form for more than 100 years, or may precipitate into calcium carbonate (CaCO3). When calcium carbonate is buried in the deep ocean, it can hold the carbon indefinitely when utilizing silicate rocks. +Enhanced weathering is one type of ocean alkalinity enhancement. Enhanced weathering increases alkalinity by scattering fine rock particles. This can happen on land and in the ocean (even though the outcome eventually affects the ocean). +In addition to sequestering CO2, alkalinity addition buffers the pH of the ocean therefore reducing ocean acidification. However, little is known about how organisms respond to added alkalinity, even from natural sources. For example, weathering of some silicate rocks could release a large amount of trace metals at the weathering site. +Cost and energy consumed by ocean alkalinity enhancement (mining, pulverizing, transport) is high compared to other CDR techniques. The cost is estimated to be US$20–50 per ton of CO2 (for "direct addition of alkaline minerals to the ocean"). +Carbon sequestered as bicarbonate in the ocean amounts to about 30% of carbon emissions since the Industrial Revolution. +Experimental materials include limestone, brucite, olivine and alkaline solutions. Another approach is to use electricity to raise alkalinity during desalination to capture waterborne CO2. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_acidification-7.md b/data/en.wikipedia.org/wiki/Ocean_acidification-7.md new file mode 100644 index 000000000..5f0ac6740 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_acidification-7.md @@ -0,0 +1,35 @@ +--- +title: "Ocean acidification" +chunk: 8/9 +source: "https://en.wikipedia.org/wiki/Ocean_acidification" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:46.998480+00:00" +instance: "kb-cron" +--- + +==== Electrochemical methods ==== +Electrochemical methods, or electrolysis, can strip carbon dioxide directly from seawater. Electrochemical process are a type of ocean alkalinity enhancement, too. Some methods focus on direct CO2 removal (in the form of carbonate and CO2 gas) while others increase the alkalinity of seawater by precipitating metal hydroxide residues, which absorbs CO2 in a matter described in the ocean alkalinity enhancement section. The hydrogen produced during direct carbon capture can then be upcycled to form hydrogen for energy consumption, or other manufactured laboratory reagents such as hydrochloric acid. +However, implementation of electrolysis for carbon capture is expensive and the energy consumed for the process is high compared to other CDR techniques. In addition, research to assess the environmental impact of this process is ongoing. Some complications include toxic chemicals in wastewaters, and reduced DIC in effluents; both of these may negatively impact marine life. + +== Policies and goals == + +=== Global policies === +As awareness about ocean acidification grows, policies geared towards increasing monitoring efforts of ocean acidification have been drafted. Previously in 2015, ocean scientist Jean-Pierre Gattuso had remarked that "The ocean has been minimally considered at previous climate negotiations. Our study provides compelling arguments for a radical change at the UN conference (in Paris) on climate change". +International efforts, such as the Wider Caribbean's Cartagena Convention (entered into force in 1986), may enhance the support provided by regional governments to highly vulnerable areas in response to ocean acidification. Many countries, for example in the Pacific Islands and Territories, have constructed regional policies, or National Ocean Policies, National Action Plans, National Adaptation Plans of Action and Joint National Action Plans on Climate Change and Disaster Risk Reduction, to help work towards SDG 14. Ocean acidification is now starting to be considered within those frameworks. + +==== UN Ocean Decade ==== + +The UN Ocean Decade has a program called "Ocean acidification research for sustainability". It was proposed by the Global Ocean Acidification Observing Network (GOA-ON) and its partners, and has been formally endorsed as a program of the UN Decade of Ocean Science for Sustainable Development. The OARS program builds on the work of GOA-ON and has the following aims: to further develop the science of ocean acidification; to increase observations of ocean chemistry changes; to identify the impacts on marine ecosystems on local and global scales; and to provide decision makers with the information needed to mitigate and adapt to ocean acidification. + +==== Global Climate Indicators ==== +The importance of ocean acidification is reflected in its inclusion as one of seven Global Climate Indicators. These Indicators are a set of parameters that describe the changing climate without reducing climate change to only rising temperature. The Indicators include key information for the most relevant domains of climate change: temperature and energy, atmospheric composition, ocean and water as well as the cryosphere. The Global Climate Indicators have been identified by scientists and communication specialists in a process led by Global Climate Observing System (GCOS). The Indicators have been endorsed by the World Meteorological Organization (WMO). They form the basis of the annual WMO Statement of the State of the Global Climate, which is submitted to the Conference of Parties (COP) of the United Nations Framework Convention on Climate Change (UNFCCC). Additionally, the Copernicus Climate Change Service (C3S) of the European Commission uses the Indicators for their annual "European State of the Climate". + +==== Sustainable Development Goal 14 ==== +In 2015, the United Nations adopted the 2030 Agenda and a set of 17 Sustainable Development Goals (SDG), including a goal dedicated to the ocean, Sustainable Development Goal 14, which calls to "conserve and sustainably use the oceans, seas and marine resources for sustainable development". Ocean acidification is directly addressed by the target SDG 14.3. The full title of Target 14.3 is: "Minimize and address the impacts of ocean acidification, including through enhanced scientific cooperation at all levels". This target has one indicator: Indicator 14.3.1 which calls for the "Average marine acidity (pH) measured at agreed suite of representative sampling stations". +The Intergovernmental Oceanographic Commission (IOC) of UNESCO was identified as the custodian agency for the SDG 14.3.1 Indicator. In this role, IOC-UNESCO is tasked with developing the SDG 14.3.1 Indicator Methodology, the annual collection of data towards the SDG 14.3.1 Indicator and the reporting of progress to the United Nations. + +=== Policies at country level === + +==== United States ==== +In the United States, the Federal Ocean Acidification Research And Monitoring Act of 2009 supports government coordination, such as the National Oceanic Atmospheric Administration's (NOAA) "Ocean Acidification Program". In 2015, USEPA denied a citizens petition that asked EPA to regulate CO2 under the Toxic Substances Control Act of 1976 in order to mitigate ocean acidification. In the denial, the EPA said that risks from ocean acidification were being "more efficiently and effectively addressed" under domestic actions, e.g., under the Presidential Climate Action Plan, and that multiple avenues are being pursued to work with and in other nations to reduce emissions and deforestation and promote clean energy and energy efficiency. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_acidification-8.md b/data/en.wikipedia.org/wiki/Ocean_acidification-8.md new file mode 100644 index 000000000..2b80c9687 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_acidification-8.md @@ -0,0 +1,36 @@ +--- +title: "Ocean acidification" +chunk: 9/9 +source: "https://en.wikipedia.org/wiki/Ocean_acidification" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:46.998480+00:00" +instance: "kb-cron" +--- + +== History == +Research into the phenomenon of ocean acidification, as well as awareness raising about the problem, has been going on for several decades. The fundamental research really began with the creation of the pH scale by Danish chemist Søren Peder Lauritz Sørensen in 1909. By around the 1950s the massive role of the ocean in absorbing fossil fuel CO2 was known to specialists, but not appreciated by the greater scientific community. Throughout much of the 20th century, the dominant focus has been the beneficial process of oceanic CO2 uptake, which has enormously ameliorated climate change. The concept of "too much of a good thing" has been late in developing and was triggered only by some key events, and the oceanic sink for heat and CO2 is still critical as the primary buffer against climate change. +In the early 1970s questions over the long-term impact of the accumulation of fossil fuel CO2 in the sea were already arising around the world and causing strong debate. Researchers commented on the accumulation of fossil CO2 in the atmosphere and sea and drew attention to the possible impacts on marine life. By the mid-1990s, the likely impact of CO2 levels rising so high with the inevitable changes in pH and carbonate ion became a concern of scientists studying the fate of coral reefs. +By the end of the 20th century the trade-offs between the beneficial role of the ocean in absorbing some 90% of all heat created, and the accumulation of some 50% of all fossil fuel CO2 emitted, and the impacts on marine life were becoming more clear. By 2003, the time of planning for the "First Symposium on the Ocean in a High-CO2 World" meeting to be held in Paris in 2004, many new research results on ocean acidification were published. +In 2009, members of the InterAcademy Panel called on world leaders to "Recognize that reducing the build up of CO2 in the atmosphere is the only practicable solution to mitigating ocean acidification". The statement also stressed the importance to "Reinvigorate action to reduce stressors, such as overfishing and pollution, on marine ecosystems to increase resilience to ocean acidification". +For example, research in 2010 found that in the 15-year period 1995–2010 alone, acidity had increased 6 percent in the upper 100 meters of the Pacific Ocean from Hawaii to Alaska. +According to a statement in July 2012 by Jane Lubchenco, head of the U.S. National Oceanic and Atmospheric Administration "surface waters are changing much more rapidly than initial calculations have suggested. It's yet another reason to be very seriously concerned about the amount of carbon dioxide that is in the atmosphere now and the additional amount we continue to put out." +A 2013 study found acidity was increasing at a rate 10 times faster than in any of the evolutionary crises in Earth's history. +The "Third Symposium on the Ocean in a High-CO2 World" took place in Monterey, California, in 2012. The summary for policy makers from the conference stated that "Ocean acidification research is growing rapidly". +In a synthesis report published in Science in 2015, 22 leading marine scientists stated that CO2 from burning fossil fuels is changing the oceans' chemistry more rapidly than at any time since the Great Dying (Earth's most severe known extinction event). Their report emphasized that the 2 °C maximum temperature increase agreed upon by governments reflects too small a cut in emissions to prevent "dramatic impacts" on the world's oceans. +A study done in 2020 argues that ocean acidification is not only negatively affecting marine life, but also human health. Food quality, respiratory issues, and human health are all negatively affected by ocean acidification. + +== See also == + +Estuarine acidification – Reducing pH values in coastal marine ecosystems +Ocean acidification in the Arctic Ocean – Aspect of climate change +Ocean acidification in the Great Barrier Reef – Threat to the reef which harms corals +Ocean deoxygenation – Reduction of the oxygen content of the oceans +Marine pollution – Pollution of oceans from substances discarded by humans + +== References == + +== External links == +Global Ocean Acidification Observing Network (GOA-ON) +United Nations Decade of Ocean Science for Sustainable Development (2021–2030) +US NOAA Ocean Acidification Program \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_acoustic_tomography-0.md b/data/en.wikipedia.org/wiki/Ocean_acoustic_tomography-0.md new file mode 100644 index 000000000..ffca7409a --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_acoustic_tomography-0.md @@ -0,0 +1,32 @@ +--- +title: "Ocean acoustic tomography" +chunk: 1/2 +source: "https://en.wikipedia.org/wiki/Ocean_acoustic_tomography" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:48.279270+00:00" +instance: "kb-cron" +--- + +Ocean acoustic tomography is a technique used to measure temperatures and currents over large regions of the ocean. On ocean basin scales, this technique is also known as acoustic thermometry. The technique relies on precisely measuring the time it takes sound signals to travel between two instruments, one an acoustic source and one a receiver, separated by ranges of 100–5,000 kilometres (54–2,700 nmi). If the locations of the instruments are known precisely, the measurement of time-of-flight can be used to infer the speed of sound, averaged over the acoustic path. Changes in the speed of sound are primarily caused by changes in the temperature of the ocean, hence the measurement of the travel times is equivalent to a measurement of temperature. A 1 °C (1.8 °F) change in temperature corresponds to about 4 metres per second (13 ft/s) change in sound speed. An oceanographic experiment employing tomography typically uses several source-receiver pairs in a moored array that measures an area of ocean. + +== Motivation == +Seawater is an electrical conductor, so the oceans are opaque to electromagnetic energy (e.g., light or radar). The oceans are fairly transparent to low-frequency acoustics, however. The oceans conduct sound very efficiently, particularly sound at low frequencies, i.e., less than a few hundred hertz. These properties motivated Walter Munk and Carl Wunsch to suggest "acoustic tomography" for ocean measurement in the late 1970s. The advantages of the acoustical approach to measuring temperature are twofold. First, large areas of the ocean's interior can be measured by remote sensing. Second, the technique naturally averages over the small scale fluctuations of temperature (i.e., noise) that dominate ocean variability. +From its beginning, the idea of observations of the ocean by acoustics was married to estimation of the ocean's state using modern numerical ocean models and the techniques assimilating data into numerical models. As the observational technique has matured, so too have the methods of data assimilation and the computing power required to perform those calculations. + +== Multipath arrivals and tomography == + +One of the intriguing aspects of tomography is that it exploits the fact that acoustic signals travel along a set of generally stable ray paths. From a single transmitted acoustic signal, this set of rays gives rise to multiple arrivals at the receiver, the travel time of each arrival corresponding to a particular ray path. The earliest arrivals correspond to the deeper-traveling rays, since these rays travel where sound speed is greatest. The ray paths are easily calculated using computers ("ray tracing"), and each ray path can generally be identified with a particular travel time. The multiple travel times measure the sound speed averaged over each of the multiple acoustic paths. These measurements make it possible to infer aspects of the structure of temperature or current variations as a function of depth. The solution for sound speed, hence temperature, from the acoustic travel times is an inverse problem. + +== The integrating property of long-range acoustic measurements == +Ocean acoustic tomography integrates temperature variations over large distances, that is, the measured travel times result from the accumulated effects of all the temperature variations along the acoustic path, hence measurements by the technique are inherently averaging. This is an important, unique property, since the ubiquitous small-scale turbulent and internal-wave features of the ocean usually dominate the signals in measurements at single points. For example, measurements by thermometers (i.e., moored thermistors or Argo drifting floats) have to contend with this 1-2 °C noise, so that large numbers of instruments are required to obtain an accurate measure of average temperature. For measuring the average temperature of ocean basins, therefore, the acoustic measurement is quite cost effective. Tomographic measurements also average variability over depth as well, since the ray paths cycle throughout the water column. + +== Reciprocal tomography == +"Reciprocal tomography" employs the simultaneous transmissions between two acoustic transceivers. A "transceiver" is an instrument incorporating both an acoustic source and a receiver. The slight differences in travel time between the reciprocally traveling signals are used to measure ocean currents, since the reciprocal signals travel with and against the current. The average of these reciprocal travel times is the measure of temperature, with the small effects from ocean currents entirely removed. Ocean temperatures are inferred from the sum of reciprocal travel times, while the currents are inferred from the difference of reciprocal travel times. Generally, ocean currents (typically 10 cm/s (3.9 in/s)) have a much smaller effect on travel times than sound speed variations (typically 5 m/s (16 ft/s)), so "one-way" tomography measures temperature to good approximation. + +== Applications == +In the ocean, large-scale temperature changes can occur over time intervals from minutes (internal waves) to decades (oceanic climate change). Tomography has been employed to measure variability over this wide range of temporal scales and over a wide range of spatial scales. Indeed, tomography has been contemplated as a measurement of ocean climate using transmissions over antipodal distances. +Tomography has come to be a valuable method of ocean observation, exploiting the characteristics of long-range acoustic propagation to obtain synoptic measurements of average ocean temperature or current. One of the earliest applications of tomography in ocean observation occurred in 1988-9. A collaboration between groups at the Scripps Institution of Oceanography and the Woods Hole Oceanographic Institution deployed a six-element tomographic array in the abyssal plain of the Greenland Sea gyre to study deep water formation and the gyre circulation. Other applications include the measurement of ocean tides, +and the estimation of ocean mesoscale dynamics by combining tomography, satellite altimetry, and +in situ data with ocean dynamical models. +In addition to the decade-long measurements obtained in the North Pacific, acoustic thermometry has been employed to measure temperature changes of the upper layers of the Arctic Ocean basins, which continues to be an area of active interest. Acoustic thermometry was also recently been used to determine changes to global-scale ocean temperatures using data from acoustic pulses sent from one end of the Earth to the other. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_acoustic_tomography-1.md b/data/en.wikipedia.org/wiki/Ocean_acoustic_tomography-1.md new file mode 100644 index 000000000..6601fe375 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_acoustic_tomography-1.md @@ -0,0 +1,55 @@ +--- +title: "Ocean acoustic tomography" +chunk: 2/2 +source: "https://en.wikipedia.org/wiki/Ocean_acoustic_tomography" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:48.279270+00:00" +instance: "kb-cron" +--- + +== Acoustic thermometry == +Acoustic thermometry is an idea to observe the world's ocean basins, and the ocean climate in particular, using trans-basin acoustic transmissions. "Thermometry", rather than "tomography", has been used to indicate basin-scale or global scale measurements. Prototype measurements of temperature have been made in the North Pacific Basin and across the Arctic Basin. +Starting in 1983, John Spiesberger of the Woods Hole Oceanographic Institution, and Ted Birdsall and Kurt Metzger of the University of Michigan developed the use of sound to infer information about the ocean's large-scale temperatures, and in particular to attempt the detection of global warming in the ocean. This group transmitted sounds from Oahu that were recorded at about ten receivers stationed around the rim of the Pacific Ocean over distances of 4,000 km (2,500 mi). +These experiments demonstrated that changes in temperature could be measured with an accuracy of about 20 millidegrees. Spiesberger et al. did not detect global warming. Instead they discovered that other natural climatic fluctuations, such as El Nino, were responsible in part +for substantial fluctuations in temperature that may have masked any slower and smaller trends that may have occurred from global warming. +The Acoustic Thermometry of Ocean Climate (ATOC) program was implemented in the North Pacific Ocean, with acoustic transmissions from 1996 through fall 2006. The measurements terminated when agreed-upon environmental protocols ended. The decade-long deployment of the acoustic source showed that the observations are sustainable on even a modest budget. The transmissions have been verified to provide an accurate measurement of ocean temperature on the acoustic paths, with uncertainties that are far smaller than any other approach to ocean temperature measurement. +Repeating earthquakes acting as naturally occurring acoustic sources have also been used in acoustic thermometry, which may be particularly useful for inferring temperature variability in the deep ocean which is presently poorly sampled by in-situ instruments. + +== Acoustic transmissions and marine mammals == + +The ATOC project was embroiled in issues concerning the effects of acoustics on marine mammals (e.g. whales, porpoises, sea lions, etc.). Public discussion was complicated by technical issues from a variety of disciplines (physical oceanography, acoustics, marine mammal biology, etc.) that makes understanding the effects of acoustics on marine mammals difficult for the experts, let alone the general public. Many of the issues concerning acoustics in the ocean and their effects on marine mammals were unknown. Finally, there were a variety of public misconceptions initially, such as a confusion of the definition of sound levels in air vs. sound levels in water. If a given number of decibels in water are interpreted as decibels in air, the sound level will seem to be orders of magnitude larger than it really is - at one point the ATOC sound levels were erroneously interpreted as so loud the signals would kill 500,000 animals. The sound power employed, 250 W, was comparable those made by blue or fin whales, although those whales vocalize at much lower frequencies. The ocean carries sound so efficiently that sounds do not have to be that loud to cross ocean basins. Other factors in the controversy were the extensive history of activism where marine mammals are concerned, stemming from the ongoing whaling conflict, and the sympathy that much of the public feels toward marine mammals. +As a result of this controversy, the ATOC program conducted a $6 million study of the effects of the acoustic transmissions on a variety of marine mammals. The acoustic source was mounted on the bottom about a half mile deep, hence marine mammals, which are bound to the surface, were generally further than a half mile from the source. The source level was modest, less than the sound level of large whales, and the duty cycle was 2% (i.e., the sound is on only 2% of the day). After six years of study the official, formal conclusion from this study was that the ATOC transmissions have "no biologically significant effects". +Other acoustics activities in the ocean may not be so benign insofar as marine mammals are concerned. Various types of man-made sounds have been studied as potential threats to marine mammals, such as airgun shots for geophysical surveys, or transmissions by the U.S. Navy for various purposes. The actual threat depends on a variety of factors beyond noise levels: sound frequency, frequency and duration of transmissions, the nature of the acoustic signal (e.g., a sudden pulse, or coded sequence), depth of the sound source, directionality of the sound source, water depth and local topography, reverberation, etc. + +== Types of transmitted acoustic signals == +Tomographic transmissions consist of long coded signals (e.g., "m-sequences") lasting 30 seconds or more. The frequencies employed range from 50 to 1000 Hz and source powers range from 100 to 250 W, depending on the particular goals of the measurements. With precise timing such as from GPS, travel times can be measured to a nominal accuracy of 1 millisecond. While these transmissions are audible near the source, beyond a range of several kilometers the signals are usually below ambient noise levels, requiring sophisticated spread-spectrum signal processing techniques to recover them. + +== See also == + +Acoustical oceanography +Ray tracing +SOFAR channel +SOSUS +Speed of sound +TOPEX/Poseidon satellite altimetry +Underwater acoustics + +== References == + +== Further reading == +B. D. Dushaw, 2013. "Ocean Acoustic Tomography" in Encyclopedia of Remote Sensing, E. G. Njoku, Ed., Springer, Springer-Verlag Berlin Heidelberg, 2013. ISBN 978-0-387-36698-2. +W. Munk, P. Worcester, and C. Wunsch (1995). Ocean Acoustic Tomography. Cambridge: Cambridge University Press. ISBN 0-521-47095-1. +P. F. Worcester, 2001: "Tomography," in Encyclopedia of Ocean Sciences, J. Steele, S. Thorpe, and K. Turekian, Eds., Academic Press Ltd., 2969–2986. + +== External links == +[1] Oceans toolbox for Matlab by Rich Pawlowicz. +Ocean Acoustics Lab (OAL) - the Woods Hole Oceanographic Institution. +The North Pacific Acoustic Laboratory (NPAL) - the Scripps Institution of Oceanography, La Jolla, CA. +Acoustic Thermometry of Ocean Climate - the Scripps Institution of Oceanography, La Jolla, CA. +Discovery of Sound in the Sea - DOSITS is an educational website concerned with acoustics in the ocean. +Sounds of acoustic signals employed for tomography - the DOSITS web page. +A day in the life of a tomography mooring - University of Washington, Seattle, WA. +Sounding Out the Ocean's Secrets - National Academy of Sciences. +Sound Measures the Ocean's Secrets - Acoustical Society of America. +The Acoustic Thermometry of Ocean Climate/Marine Mammal Research Program Cornell University Laboratory of Ornithology, Bioacoustics Research Program \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_current-0.md b/data/en.wikipedia.org/wiki/Ocean_current-0.md new file mode 100644 index 000000000..97026f943 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_current-0.md @@ -0,0 +1,33 @@ +--- +title: "Ocean current" +chunk: 1/4 +source: "https://en.wikipedia.org/wiki/Ocean_current" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:49.743977+00:00" +instance: "kb-cron" +--- + +An ocean current is a continuous, directed movement of seawater generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, shoreline configurations, and interactions with other currents influence a current's direction and strength. Ocean currents move both horizontally, on scales that can span entire oceans, as well as vertically, with vertical currents (upwelling and downwelling) playing an important role in the movement of nutrients and gases, such as carbon dioxide, between the surface and the deep ocean. +Ocean currents are classified by temperature as either warm currents or cold currents. They are also classified by their velocity, dimension, and direction as either drifts, currents, or streams. Drifts, such as the North Atlantic Drift Current, involve the forward movement of surface ocean water under the influence of the prevailing wind. Currents, such as the Labrador Current, +involve the movement of oceanic water in a more definite direction at a greater velocity than drifts. Streams, such as the Gulf Stream, involve movement of larger masses of ocean water with greater velocity than drifts or currents. +Ocean currents are patterns of water movement that influence climate zones and weather patterns around the world. They are primarily driven by winds and by seawater density, although many other factors influence them, including the shape and configuration of the oceanic basin they flow through. The two basic types of currents – surface and deep-water currents – help define the character and flow of ocean waters across the planet. +Ocean currents flow for great distances, and together they create the global conveyor belt, which plays a dominant role in determining the climate of many of Earth's regions. More specifically, ocean currents influence the temperature of the regions through which they travel. For example, warm currents traveling along more temperate coasts increase the temperature of the area by warming the sea breezes that blow over them. Perhaps the most striking example is the Gulf Stream, which, together with its extension the North Atlantic Drift, makes northwest Europe much more temperate for its high latitude than other areas at the same latitude. Another example is Lima, Peru, whose cooler subtropical climate contrasts with that of its surrounding tropical latitudes because of the Humboldt Current. +The largest ocean current is the Antarctic Circumpolar Current (ACC), a wind-driven current which flows clockwise uninterrupted around Antarctica. The ACC connects all the oceanic basins together, and also provides a link between the atmosphere and the deep ocean due to the way water upwells and downwells on either side of it. + +== Causes == + +Ocean currents are driven by the wind, by the gravitational pull of the Moon in the form of tides, and by the effects of variations in water density. Ocean dynamics define and describe the motion of water within the oceans. +Ocean temperature and motion fields can be separated into three distinct layers: mixed (surface) layer, upper ocean (above the thermocline), and deep ocean. Ocean currents are measured in units of sverdrup (Sv), where 1 Sv is equivalent to a volume flow rate of 1,000,000 m3 (35,000,000 ft3) per second. +There are two main types of currents, surface currents and deep-water currents. Generally surface currents are driven by wind systems and deep-water currents are driven by differences in water density due to variations in water temperature and salinity. + +=== Wind-driven circulation === +Surface oceanic currents are driven by wind currents, the large scale prevailing winds drive major persistent ocean currents, and seasonal or occasional winds drive currents of similar persistence to the winds that drive them, and the Coriolis effect plays a major role in their development. The Ekman spiral velocity distribution results in the currents flowing at an angle to the driving winds, and they develop typical clockwise spirals in the Northern Hemisphere and counter-clockwise rotation in the Southern Hemisphere. +In addition, the areas of surface ocean currents move somewhat with the seasons; this is most notable in equatorial currents. +Deep ocean basins generally have a non-symmetric surface current, in that the eastern equator-ward flowing branch is broad and diffuse whereas the pole-ward flowing western boundary current is relatively narrow. + +=== Thermohaline circulation === + +Large scale currents are driven by gradients in water density, which in turn depend on variations in temperature and salinity. This thermohaline circulation is also known as the ocean's conveyor belt. Where significant vertical movement of ocean currents is observed, this is known as upwelling and downwelling. The adjective thermohaline derives from thermo- referring to temperature and -haline referring to salt content, factors which together determine the density of seawater. +The thermohaline circulation is a part of the large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes. Wind-driven surface currents (such as the Gulf Stream) travel polewards from the equatorial Atlantic Ocean, cooling en route, and eventually sinking at high latitudes (forming North Atlantic Deep Water). This dense water then flows into the ocean basins. While the bulk of it upwells in the Southern Ocean, the oldest waters (with a transit time of around 1000 years) upwell in the North Pacific. Extensive mixing therefore takes place between the ocean basins, reducing differences between them and making the Earth's oceans a global system. On their journey, the water masses transport both energy (in the form of heat) and matter (solids, dissolved substances and gases) around the globe. As such, the state of the circulation has a large impact on the climate of the Earth. The thermohaline circulation is sometimes called the ocean conveyor belt, the great ocean conveyor, or the global conveyor belt. On occasion, it is imprecisely used to refer to the meridional overturning circulation, (MOC). +Since the 2000s an international program called Argo has been mapping the temperature and salinity structure of the ocean with a fleet of automated platforms that float with the ocean currents. The information gathered will help explain the role the oceans play in the Earth's climate. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_current-1.md b/data/en.wikipedia.org/wiki/Ocean_current-1.md new file mode 100644 index 000000000..52a0f695f --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_current-1.md @@ -0,0 +1,34 @@ +--- +title: "Ocean current" +chunk: 2/4 +source: "https://en.wikipedia.org/wiki/Ocean_current" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:49.743977+00:00" +instance: "kb-cron" +--- + +== Effects on climate and ecology == +Ocean currents affect temperatures throughout the world. For example, the ocean current that brings warm water up the north Atlantic to northwest Europe also cumulatively and slowly blocks ice from forming along the seashores, which would also block ships from entering and exiting inland waterways and seaports, hence ocean currents play a decisive role in influencing the climates of regions through which they flow. Ocean currents are important in the study of marine debris. + +Upwellings and cold ocean water currents flowing from polar and sub-polar regions bring in nutrients that support plankton growth, which are crucial prey items for several key species in marine ecosystems. +Ocean currents are also important in the dispersal and distribution of many organisms, including those with pelagic egg or larval stages. An example is the life-cycle of the European Eel. Terrestrial species, for example tortoises and lizards, can be carried on floating debris by currents to colonise new terrestrial areas and islands. + +== Ocean currents and climate change == +The continued rise of atmospheric temperatures is anticipated to have various effects on the strength of surface ocean currents, wind-driven circulation and dispersal patterns. Ocean currents play a significant role in influencing climate, and shifts in climate in turn impact ocean currents. + +Over the last century, reconstructed sea surface temperature data reveal that western boundary currents are heating at double the rate of the global average. These observations indicate that the western boundary currents are likely intensifying due to this change in temperature, and may continue to grow stronger in the near future. There is evidence that surface warming due to anthropogenic climate change has accelerated upper ocean currents in 77% of the global ocean. Specifically, increased vertical stratification due to surface warming intensifies upper ocean currents, while changes in horizontal density gradients caused by differential warming across different ocean regions results in the acceleration of surface zonal currents. +There are suggestions that the Atlantic meridional overturning circulation (AMOC) is in danger of collapsing due to climate change, which would have extreme impacts on the climate of northern Europe and more widely, although this topic is controversial and remains an active area of research. The "State of the cryosphere" report, dedicates significant space to AMOC, saying it may be en route to collapse because of ice melt and water warming. In the same time, the Antarctic Circumpolar Current (ACC) is also slowing down and is expected to lose 20% of its power by the year 2050, "with widespread impacts on ocean circulation and climate". UNESCO mentions that the report in the first time "notes a growing scientific consensus that melting Greenland and Antarctic ice sheets, among other factors, may be slowing important ocean currents at both poles, with potentially dire consequences for a much colder northern Europe and greater sea-level rise along the U.S. East Coast." +In addition to water surface temperatures, the wind systems are a crucial determinant of ocean currents. Wind wave systems influence oceanic heat exchange, the condition of the sea surface, and can alter ocean currents. In the North Atlantic, equatorial Pacific, and Southern Ocean, increased wind speeds as well as significant wave heights have been attributed to climate change and natural processes combined. In the East Australian Current, global warming has also been accredited to increased wind stress curl, which intensifies these currents, and may even indirectly increase sea levels, due to the additional warming created by stronger currents. +As ocean circulation changes due to climate, typical distribution patterns are also changing. The dispersal patterns of marine organisms depend on oceanographic conditions, which as a result, influence the biological composition of oceans. Due to the patchiness of the natural ecological world, dispersal is a species survival mechanism for various organisms. With strengthened boundary currents moving toward the poles, it is expected that some marine species will be redirected to the poles and greater depths. The strengthening or weakening of typical dispersal pathways by increased temperatures are expected to not only impact the survival of native marine species due to inability to replenish their meta populations but also may increase the prevalence of invasive species. In Japanese corals and macroalgae, the unusual dispersal pattern of organisms toward the poles may destabilize native species. + +== Economic importance == +Knowledge of surface ocean currents is essential in reducing costs of shipping, since traveling with them reduces fuel costs. In the wind powered sailing-ship era, knowledge of wind patterns and ocean currents was even more essential. Using ocean currents to help their ships into harbor and using currents such as the gulf stream to get back home. The lack of understanding of ocean currents during that time period is hypothesized to be one of the contributing factors to exploration failure. The Gulf Stream and the Canary current keep western European countries warmer and less variable, while at the same latitude North America's weather was colder. A good example of this is the Agulhas Current (down along eastern Africa), which long prevented sailors from reaching India. +In recent times, around-the-world sailing competitors make good use of surface currents to build and maintain speed. +Ocean currents can also be used for marine power generation, with areas of Japan, Florida and Hawaii being considered for test projects. The utilization of currents today can still impact global trade, it can reduce the cost and emissions of shipping vessels. + +Ocean currents can also impact the fishing industry, examples of this include the Tsugaru, Oyashio and Kuroshio currents all of which influence the western North Pacific temperature, which has been shown to be a habitat predictor for the Skipjack tuna. It has also been shown that it is not just local currents that can affect a country's economy, but neighboring currents can influence the viability of local fishing industries. + +== Distribution == + +Currents of the Arctic Ocean \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_current-2.md b/data/en.wikipedia.org/wiki/Ocean_current-2.md new file mode 100644 index 000000000..4a45f5510 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_current-2.md @@ -0,0 +1,98 @@ +--- +title: "Ocean current" +chunk: 3/4 +source: "https://en.wikipedia.org/wiki/Ocean_current" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:49.743977+00:00" +instance: "kb-cron" +--- + +Baffin Island Current – Arctic Ocean current +Beaufort Gyre – Wind-driven ocean current in the Arctic Ocean polar region +East Greenland Current – Current from Fram Strait to Cape Farewell off the eastern coat of Greenland +East Iceland Current – Cold water ocean current that forms as a branch of the East Greenland Current +Labrador Current – Western North Atlantic Ocean current +North Icelandic Jet – Deep-reaching current that flows along the continental slope of Iceland +Norwegian Current – Current that flows northeasterly along the Atlantic coast of Norway +Transpolar Drift Stream – Current in the Arctic Ocean +West Greenland Current – Weak cold water current that flows to the north along the west coast of Greenland +West Spitsbergen Current – Warm, salty current that runs poleward just west of Spitsbergen +Currents of the Atlantic Ocean + +Angola Current – Temporary ocean surface current +Antilles Current – Ocean current +Atlantic meridional overturning circulation – System of surface and deep currents in the Atlantic Ocean +Azores Current – Ocean current in the North Atlantic Ocean +Benguela Current – Ocean current in the South Atlantic +Brazil Current – Water current along Brazil's southern coast +Canary Current – Wind-driven surface current that is part of the North Atlantic Gyre +Cape Horn Current – Cold water current that flows west-to-east around Cape Horn +Caribbean Current – Atlantic Ocean current +East Greenland Current – Current from Fram Strait to Cape Farewell off the eastern coat of Greenland +East Iceland Current – Cold water ocean current that forms as a branch of the East Greenland Current +Equatorial Counter Current – Shallow eastward flowing current found in the Atlantic, Indian, and Pacific Oceans +Falkland Current – Northward cold water Atlantic Ocean current +Florida Current – Thermal ocean current +Guinea Current – Atlantic warm-water current off West Africa +Gulf Stream – Warm Atlantic Ocean current +Irminger Current – North Atlantic ocean current +Labrador Current – Western North Atlantic Ocean current +Lomonosov Current – Deep current in the Atlantic Ocean. from the coast of Brazil to the Gulf of Guinea +Loop Current – Ocean current between Cuba and Yucatán Peninsula +North Atlantic Current – Current of the Atlantic Ocean +North Brazil Current – North Atlantic ocean current +North Equatorial Current – Current in the Pacific and Atlantic Oceans +Norwegian Current – Current that flows northeasterly along the Atlantic coast of Norway +Portugal Current – Weak ocean current that flows south along the coast of Portugal +South Atlantic Current – Eastward ocean current, fed by the Brazil Current +South Equatorial Current – Ocean current in the Pacific, Atlantic, and Indian Ocean +West Greenland Current – Weak cold water current that flows to the north along the west coast of Greenland +West Spitsbergen Current – Warm, salty current that runs poleward just west of Spitsbergen +Currents of the Indian Ocean + +Agulhas Current – Southwest Indian Ocean current off Africa's east coast +Agulhas Return Current – Ocean current in the southern Indian Ocean +East Madagascar Current – Oceanic flow feature near Madagascar +Equatorial Counter Current – Shallow eastward flowing current found in the Atlantic, Indian, and Pacific Oceans +Indian Monsoon Current – Seasonally-varying ocean current regime in the northern Indian Ocean +Indonesian Throughflow – Ocean current +Leeuwin Current – Ocean current off Western Australia +Madagascar Current – Ocean current in the West Indian Ocean +Mozambique Current – Warm ocean current in the Indian Ocean +North Madagascar Current – Ocean current near Madagascar that flows into the South Equatorial Current +Somali Current – Boundary current in the Indian Ocean +South Equatorial Current – Ocean current in the Pacific, Atlantic, and Indian Ocean +Southwest Madagascar Coastal Current – Warm poleward ocean current flowing in the south-west of Madagascar +West Australian Current – Cool oceanic current +Currents of the Pacific Ocean + +Alaska Current – Warm-water current west of North America +Aleutian Current – Eastward-flowing ocean current which lies north of the North Pacific Current; +California Current – Pacific Ocean current +Cape Horn Current – Cold water current that flows west-to-east around Cape Horn +Cromwell Current – Eastward-flowing subsurface current that extends along the equator in the Pacific Ocean +Davidson Current – Countercurrent of the Pacific Ocean +East Australian Current – Currents of the Pacific Ocean +East Korea Warm Current – Ocean current in the Sea of Japan +Equatorial Counter Current – Shallow eastward flowing current found in the Atlantic, Indian, and Pacific Oceans +Humboldt Current – Current of the Pacific Ocean +Indonesian Throughflow – Ocean current +Kamchatka Current – Pacific Ocean current +Kuroshio Current – North-flowing current in the northwest Pacific Ocean +Mindanao Current – Narrow, southward-flowing ocean current along the southeastern coast of the Philippines +Mindanao Eddy – Semi-permanent cold-ring ocean eddy near the Philippines +North Equatorial Current – Current in the Pacific and Atlantic Oceans +North Korea Cold Current – Cold water current in the Sea of Japan +North Pacific Current – Ocean current, Japan to British Columbia +Oyashio Current – Cold subarctic ocean current in the Pacific Ocean +South Equatorial Current – Ocean current in the Pacific, Atlantic, and Indian Ocean +Subtropical Countercurrent – Narrow eastward ocean current in the central North Pacific Ocean +Tasman Front – Pacific Ocean current +Tasman Outflow – Deepwater current that flows from the Pacific Ocean past Tasmania into the Indian Ocean +Currents of the Southern Ocean + +Antarctic Circumpolar Current – Ocean current that flows clockwise from west to east around Antarctica +Tasman Outflow – Deepwater current that flows from the Pacific Ocean past Tasmania into the Indian Ocean +Kerguelen deep western boundary current +Oceanic gyres \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_current-3.md b/data/en.wikipedia.org/wiki/Ocean_current-3.md new file mode 100644 index 000000000..77b6713bc --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_current-3.md @@ -0,0 +1,48 @@ +--- +title: "Ocean current" +chunk: 4/4 +source: "https://en.wikipedia.org/wiki/Ocean_current" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:49.743977+00:00" +instance: "kb-cron" +--- + +Beaufort Gyre – Wind-driven ocean current in the Arctic Ocean polar region +Indian Ocean Gyre – Major oceanic gyre in the Indian Ocean +North Atlantic Gyre – Major circular system of ocean currents +North Pacific Gyre – Major circulating system of ocean currents +Ross Gyre – Circulating system of ocean currents in the Ross Sea +South Atlantic Gyre – Subtropical gyre in the south Atlantic Ocean +South Pacific Gyre – Major circulating system of ocean currents +Weddell Gyre – One of two gyres within the Southern Ocean + +== See also == + +Currentology – Science that studies the internal movements of water masses +Deep ocean water – Cold, salty water deep below the surface of Earth's oceans +Fish migration – Movement of fishes from one part of a water body to another on a regular basis +Geostrophic current – Oceanic flow in which the pressure gradient force is balanced by the Coriolis effect +Latitude of the Gulf Stream and the Gulf Stream north wall index +List of ocean circulation models +Marine habitats § Ocean currents +Marine current power – Extraction of power from ocean currents +Ocean gyre – Any large system of circulating ocean surface currents +Physical oceanography – Study of physical conditions and processes within the ocean +Subsurface ocean current – Oceanic currents that flow beneath surface currents +Thermohaline circulation – Part of large-scale ocean circulation +Tidal current – Flow of water induced by astronomical gravitational effects +Volta do mar – Archaic navigational technique + +== References == + +== Further reading == +Hansen, B.; Østerhus, S; Quadfasel, D; Turrell, W (2004). "Already the day after tomorrow?". Science. 305 (5686): 953–954. doi:10.1126/science.1100085. PMID 15310882. S2CID 12968045. +Kerr, Richard A. (2004). "A slowing cog in the North Atlantic ocean's climate machine". Science. 304 (5669): 371–372. doi:10.1126/science.304.5669.371a. PMID 15087513. S2CID 42150417. +Munday, Phillip L.; Jones, Geoffrey P.; Pratchett, Morgan S.; Williams, Ashley J. (2008). "Climate change and the future for coral reef fishes". Fish and Fisheries. 9 (3): 261–285. Bibcode:2008AqFF....9..261M. doi:10.1111/j.1467-2979.2008.00281.x. +Rahmstorf, S. (2003). "Thermohaline circulation: The current climate". Nature. 421 (6924): 699. Bibcode:2003Natur.421..699R. doi:10.1038/421699a. PMID 12610602. S2CID 4414604. +Roemmich, D. (2007). "Physical oceanography: Super spin in the southern seas". Nature. 449 (7158): 34–35. Bibcode:2007Natur.449...34R. doi:10.1038/449034a. PMID 17805284. S2CID 2951110. + +== External links == + +Current global map of sea surface currents \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_deoxygenation-0.md b/data/en.wikipedia.org/wiki/Ocean_deoxygenation-0.md new file mode 100644 index 000000000..4cad2ad78 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_deoxygenation-0.md @@ -0,0 +1,30 @@ +--- +title: "Ocean deoxygenation" +chunk: 1/4 +source: "https://en.wikipedia.org/wiki/Ocean_deoxygenation" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:51.047511+00:00" +instance: "kb-cron" +--- + +Ocean deoxygenation is the reduction of the oxygen content in different parts of the ocean due to human activities. There are two areas where this occurs. Firstly, it occurs in coastal zones where eutrophication has driven some quite rapid (in a few decades) declines in oxygen to very low levels. This type of ocean deoxygenation is also called dead zones. Secondly, ocean deoxygenation occurs also in the open ocean. In that part of the ocean, there is nowadays an ongoing reduction in oxygen levels. As a result, the naturally occurring low oxygen areas (so called oxygen minimum zones (OMZs)) are now expanding slowly. This expansion is happening as a consequence of human caused climate change. The resulting decrease in oxygen content of the oceans poses a threat to marine life, as well as to people who depend on marine life for nutrition or livelihood. A decrease in ocean oxygen levels affects how productive the ocean is, how nutrients and carbon move around, and how marine habitats function. +As the oceans become warmer this increases the loss of oxygen in the oceans. This is because the warmer temperatures increase ocean stratification. The reason for this lies in the multiple connections between density and solubility effects that result from warming. As a side effect, the availability of nutrients for marine life is reduced, therefore adding further stress to marine organisms. +The rising temperatures in the oceans also cause a reduced solubility of oxygen in the water, which can explain about 50% of oxygen loss in the upper level of the ocean (>1000 m). Warmer ocean water holds less oxygen and is more buoyant than cooler water. This leads to reduced mixing of oxygenated water near the surface with deeper water, which naturally contains less oxygen. Warmer water also raises oxygen demand from living organisms; as a result, less oxygen is available for marine life. +Studies have shown that oceans have already lost 1-2% of their oxygen since the middle of the 20th century, and model simulations predict a decline of up to 7% in the global ocean O2 content over the next hundred years. The decline of oxygen is projected to continue for a thousand years or more. + +== Terminology == +The term ocean deoxygenation has been used increasingly by international scientific bodies because it captures the decreasing trend of the world ocean's oxygen inventory. Oceanographers and others have discussed what phrase best describes the phenomenon to non-specialists. Among the options considered have been ocean suffocation, marine deoxygenation, ocean oxygen depletion and ocean hypoxia. + +== Types and mechanisms == +There are two types of ocean deoxygenation, taking place in two different zones and having different causes: the reduction of oxygen in coastal zones versus in the open ocean as well as deep ocean (oxygen minimum zones). These are coupled but different. + +=== Coastal zones === + +=== Open and deep ocean zones (oxygen minimum zones) === + +In the open ocean there are natural low oxygen areas and these are expanding slowly. These oceanic oxygen minimum zones (OMZ) generally occur in the middle depths of the ocean, from 100 – 1000 m deep. They are natural phenomena that result from respiration of sinking organic material produced in the surface ocean. However, as the oxygen content of the ocean decreases, oxygen minimum zones are expanding both vertically and horizontally. In these low oxygen areas the water circulation is slow. This stability means it is easier to see quite small changes in oxygen, such as a decline of 1-2%. In many of these areas, this decline does not mean these low oxygen regions become uninhabitable for fish and other marine life but over many decades may do, particularly in the Pacific and Indian Ocean. +Oxygen is input into the ocean at the surface, through the processes of photosynthesis by phytoplankton and mixing with the atmosphere. Organisms, both microbial and multicellular, use oxygen in respiration throughout the entire depth of the ocean, so when the supply of oxygen from the surface is less than the utilization of oxygen in deep water, oxygen loss occurs. +This phenomenon is natural, but is exacerbated with increased stratification and increasing ocean temperature. Stratification occurs when water masses with different properties, primarily temperature and salinity, are layered, with lower density water on top of higher density water. The larger the differences in the properties between layers, the less mixing occurs between the layers. Stratification is increased when the temperature of the surface ocean or the amount of freshwater input into the ocean from rivers and ice melt increases, enhancing ocean deoxygenation by reducing supply. Another factor that can reduce supply is the solubility of oxygen. As temperature and salinity increase, the solubility of oxygen decreases, meaning that less oxygen can be dissolved into water as it warms and becomes more salty. + +== Role of climate change == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_deoxygenation-1.md b/data/en.wikipedia.org/wiki/Ocean_deoxygenation-1.md new file mode 100644 index 000000000..82d068d84 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_deoxygenation-1.md @@ -0,0 +1,29 @@ +--- +title: "Ocean deoxygenation" +chunk: 2/4 +source: "https://en.wikipedia.org/wiki/Ocean_deoxygenation" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:51.047511+00:00" +instance: "kb-cron" +--- + +While oxygen minimum zones (OMZs) occur naturally, they can be exacerbated by human impacts like climate change and land-based pollution from agriculture and sewage. The prediction of current climate models and climate change scenarios is that substantial warming and loss of oxygen throughout the majority of the upper ocean will occur. Global warming increases ocean temperatures, especially in shallow coastal areas. As water temperature increases, its ability to hold oxygen decreases, resulting in lower oxygen concentrations. This compounds the effects of eutrophication in coastal zones described above. +Open ocean areas with no oxygen have grown more than 1.7 million square miles in the last 50 years, and coastal waters have seen a tenfold increase in low-oxygen areas in the same time. +Measurements of dissolved oxygen in coastal and open-ocean waters over the past 50 years have revealed a marked decline in oxygen content. This decline is associated with expanding spatial extent, expanding vertical extent, and prolonged duration of oxygen-poor conditions in all regions of the global oceans. Examinations of the spatial extent of OMZs in the past through paleoceanographical methods clearly show that the spatial extent of OMZs has expanded through time, and this expansion is coupled to ocean warming and reduced ventilation of thermocline waters. +Research has sought to model potential changes to OMZs driven by rising global temperatures and human impacts. This is challenging due to the many factors that could contribute to changes in OMZs. The factors used for modeling change in OMZs are numerous, and in some cases hard to measure or quantify. Some of the processes being studied are changes in oxygen gas solubility as a result of rising ocean temperatures, as well as changes in the amount of respiration and photosynthesis occurring around OMZs. Many studies have concluded that OMZs are expanding in multiple locations, but fluctuations of modern OMZs are still not fully understood. Existing Earth system models project considerable reductions in oxygen and other physical-chemical variables in the ocean due to climate change, with potential ramifications for ecosystems and humans. +The global decrease in oceanic oxygen content is statistically significant and emerging beyond the envelope of natural fluctuations. This trend of oxygen loss is accelerating, with widespread and obvious losses occurring after the 1980s. The rate and total content of oxygen loss varies by region, with the North Pacific emerging as a particular hotspot of deoxygenation due to the increased amount of time since its deep waters were last ventilated (see thermohaline circulation) and related high apparent oxygen utilization (AOU). Estimates of total oxygen loss in the global ocean range from 119 to 680 T mol decade−1 since the 1950s. These estimates represent 2% of the global ocean oxygen inventory. +Melting of gas hydrates in the bottom layers of water may result in the release of more methane from sediments and subsequent consumption of oxygen by aerobic respiration of methane to carbon dioxide. Another effect of climate change on oceans that causes ocean deoxygenation is circulation changes. As the ocean warms from the surface, stratification is expected to increase, slowing ocean circulation and further deoxygenating the ocean. + +=== Estimates for the future === +The results from mathematical models show that global ocean oxygen loss rates will continue to accelerate up to 125 T mol year−1 by 2100 due to persistent warming, a reduction in ventilation of deeper waters, increased biological oxygen demand, and the associated expansion of OMZs into shallower areas. + +== Variations == + +=== Expanding oxygen minimum zones (OMZ) === +Several areas of the open ocean have naturally low oxygen concentration due to biological oxygen consumption that cannot be supported by the rate of oxygen input to the area from physical transport, air-sea mixing, or photosynthesis. These areas are called oxygen minimum zones (OMZs), and there is a wide variety of open ocean systems that experience these naturally low oxygen conditions, such as upwelling zones, deep basins of enclosed seas, and the cores of some mode-water eddies. +Ocean deoxygenation has led to suboxic, hypoxic, and anoxic conditions in both coastal waters and the open ocean. Since 1950, more than 500 sites in coastal waters have reported oxygen concentrations below 2 mg liter−1, which is generally accepted as the threshold of hypoxic conditions. +The extent of OMZs has expanded in tropical oceans during the past half century. +Oxygen-poor waters of coastal and open ocean systems have largely been studied in isolation of each other, with researchers focusing on eutrophication-induced hypoxia in coastal waters and naturally occurring (without apparent direct input of anthropogenic nutrients) open ocean OMZs. However, coastal and open ocean oxygen-poor waters are highly interconnected and therefore both have seen an increase in the intensity, spatial extent, and temporal extent of deoxygenated conditions. + +The spatial extent of deoxygenated conditions can vary widely. In coastal waters, regions with deoxygenated conditions can extend from less than one to many thousands of square kilometers. Open ocean OMZs exist in all ocean basins and have similar variation in spatial extent; an estimated 8% of global ocean volume is within OMZs. The largest OMZ is in the eastern tropical north Pacific and comprises 41% of this global volume, and the smallest OMZ is found in the eastern tropical North Atlantic and makes up only 5% of the global OMZ volume. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_deoxygenation-2.md b/data/en.wikipedia.org/wiki/Ocean_deoxygenation-2.md new file mode 100644 index 000000000..209bb23cc --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_deoxygenation-2.md @@ -0,0 +1,31 @@ +--- +title: "Ocean deoxygenation" +chunk: 3/4 +source: "https://en.wikipedia.org/wiki/Ocean_deoxygenation" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:51.047511+00:00" +instance: "kb-cron" +--- + +=== Vertical extent of low oxygen conditions === +The vertical extent of low oxygen conditions is also variable, and areas of persistent low oxygen have annual variation in the upper and lower limits of oxygen-poor waters. Typically, OMZs are expected to occur at depths of about 200 to 1,000 meters. The upper limit of OMZs is characterized by a strong and rapid gradient in oxygenation, called the oxycline. The depth of the oxycline varies between OMZs, and is mainly affected by physical processes such as air-sea fluxes and vertical movement in the thermocline depth. The lower limit of OMZs is associated with the reduction in biological oxygen consumption, as the majority of organic matter is consumed and respired in the top 1,000 m of the vertical water column. Shallower coastal systems may see oxygen-poor waters extend to bottom waters, leading to negative effects on benthic communities. +Many persistent OMZs have increased in thickness over the last five decades. This happened because the upper limit of the OMZ became shallower and also because the OMZ expanded downward. + +=== Variations in temporal duration === +The temporal duration of oxygen-poor conditions can vary on seasonal, annual, or multi-decadal scales. Hypoxic conditions in coastal systems like the Gulf of Mexico are usually tied to discharges of rivers, thermohaline stratification of the water column, wind-driven forcing, and continental shelf circulation patterns. As such, there are seasonal and annual patterns in the initiation, persistence, and break down of intensely hypoxic conditions. Oxygen concentrations in open oceans and the margins between coastal areas and the open ocean may see variation in intensity, spatial extent, and temporal extent from multi-decadal oscillations in climatic conditions. +Coastal regions have also seen expanded spatial extent and temporal duration due to increased anthropogenic nutrient input and changes in regional circulation. Areas that have not previously experienced low oxygen conditions, like the coastal shelf of Oregon on the West coast of the United States, have recently and abruptly developed seasonal hypoxia. + +== Impacts == + +=== Ocean productivity === +Ocean deoxygenation poses implications for ocean productivity, nutrient cycling, carbon cycling, and marine habitats. Studies have shown that oceans have already lost 1-2% of their oxygen since the middle of the 20th century, and model simulations predict a decline of up to 7% in the global ocean O2 content over the next hundred years. The decline of oxygen is projected to continue for a thousand years or more. +Ocean deoxygenation results in the expansion of oxygen minimum zones in the oceans. Along with this ocean deoxygenation is caused by an imbalance of sources and sinks of oxygen in dissolved water. The change has been fairly rapid and poses a threat to fish and other types of marine life, as well as to people who depend on marine life for nutrition or livelihood. +As low oxygen zones expand vertically nearer to the surface, they can affect coastal upwelling systems such as the California Current on the coast of Oregon (US). These upwelling systems are driven by seasonal winds that force the surface waters near the coast to move offshore, which pulls deeper water up along the continental shelf. As the depth of the deoxygenated deeper water becomes shallower, more of the deoxygenated water can reach the continental shelf, causing coastal hypoxia and fish kills. Impacts of massive fish kills on the aquaculture industry are projected to be profound. + +=== Marine organisms and biodiversity === +The viability of species is being disrupted throughout the ocean food web due to changes in ocean chemistry. As the ocean warms, mixing between water layers decreases, resulting in less oxygen and nutrients being available for marine life. +Short term effects can be seen in acutely fatal circumstances, but other sublethal consequences can include impaired reproductive ability, reduced growth, and increase in diseased population. These can be attributed to the co-stressor effect. When an organism is already stressed, for example getting less oxygen than it would prefer, it does not do as well in other areas of its existence like reproduction, growth, and warding off disease. Additionally, warmer water not only holds less oxygen, but it also causes marine organisms to have higher metabolic rates, resulting in them using up available oxygen more quickly, lowering the oxygen concentration in the water even more and compounding the effects seen. Finally, for some organisms, habitat reduction will be a problem. Habitable zones in the water column are expected to compress and habitable seasons are expected to be shortened. If the water an organism's regular habitat sits in has oxygen concentrations lower than it can tolerate, it will not want to live there anymore. This leads to changed migration patterns as well as changed or reduced habitat area. +Long term effects can be seen on a broader scale of changes in biodiversity and food web makeup. Due to habitat change of many organisms, predator-prey relationships will be altered. For example, when squeezed into a smaller well-oxygenated area, predator-prey encounter rates will increase, causing an increase in predation, potentially putting strain on the prey population. Additionally, diversity of ecosystems in general is expected to decrease due to decrease in oxygen concentrations. + +=== Effects on fisheries === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_deoxygenation-3.md b/data/en.wikipedia.org/wiki/Ocean_deoxygenation-3.md new file mode 100644 index 000000000..93e41aecc --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_deoxygenation-3.md @@ -0,0 +1,28 @@ +--- +title: "Ocean deoxygenation" +chunk: 4/4 +source: "https://en.wikipedia.org/wiki/Ocean_deoxygenation" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:51.047511+00:00" +instance: "kb-cron" +--- + +Vertical expansion of tropical OMZs has reduced the area between the OMZ and surface. This means that many species that live near the surface, such as fish, could be affected periodically. Ongoing research is investigating how OMZ expansion affects food webs in these areas. Studies on OMZ expansion in the tropical Pacific and Atlantic have observed negative effects on fish populations and commercial fisheries that likely occurred from reduced habitat when the OMZ moved to a shallower depth. +A fish's behavior in response to ocean deoxygenation is based upon their tolerance to oxygen poor conditions. Species with low anoxic tolerance tend to undergo habitat compression in response to the expansion of OMZs. Fish species with a low tolerance for low oxygen conditions may move to live nearer the ocean surface where oxygen concentration will usually be higher. Biological responses to habitat compression can be varied. Some species of billfish, predatory pelagic predators such as sailfish and marlin, that have undergone habitat compression actually have increased growth since their prey, smaller pelagic fish, experienced the same habitat compression, resulting in increased prey vulnerability to billfishes. Fish with tolerance to anoxic conditions, such as jumbo squid and lanternfish, can remain active in anoxic environments at a reduced level, which can improve their survival by increasing avoidance of anoxia intolerant predators and have increased access to resources that their anoxia intolerant competitors cannot. +The relationship between zooplankton and low oxygen zones is complex and varies by species and life stage. Some gelatinous zooplankton reduce their growth rates when exposed to hypoxia while others utilize this habitat to forage on high prey concentrations with their growth rates unaffected. The ability of some gelatinous zooplankton to tolerate hypoxia may be attributed to the ability to store oxygen in intragel regions. The movements of zooplankton as a result of ocean deoxygenation can affect fisheries, global nitrogen cycling, and trophic relationships. These changes have the potential to have large economic and environmental consequences through overfishing or collapsed food webs. + +== See also == + +Anoxic event – Historic oxygen depletion events in Earth's oceans +Anoxic waters – Areas of seawater, freshwater, or groundwater that are depleted of dissolved oxygen +Ocean acidification – Decrease of pH levels in the ocean +Seaweed – Macroscopic marine algae +Special Report on the Ocean and Cryosphere in a Changing Climate – 2019 IPCC report + +== References == + +== External links == + +Ocean Deoxygenation +NASA: Ocean Deoxygenation: Past, Present, and Future \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_dynamics-0.md b/data/en.wikipedia.org/wiki/Ocean_dynamics-0.md new file mode 100644 index 000000000..ccebb39a6 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_dynamics-0.md @@ -0,0 +1,384 @@ +--- +title: "Ocean dynamics" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Ocean_dynamics" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:52.277542+00:00" +instance: "kb-cron" +--- + +Ocean dynamics define and describe the flow of water within the oceans. Ocean temperature and motion fields can be separated into three distinct layers: mixed (surface) layer, upper ocean (above the thermocline), and deep ocean. +Ocean dynamics has traditionally been investigated by sampling from instruments in situ. +The mixed layer is nearest to the surface and can vary in thickness from 10 to 500 meters. This layer has properties such as temperature, salinity and dissolved oxygen which are uniform with depth reflecting a history of active turbulence (the atmosphere has an analogous planetary boundary layer). Turbulence is high in the mixed layer. However, it becomes zero at the base of the mixed layer. Turbulence again increases below the base of the mixed layer due to shear instabilities. At extratropical latitudes this layer is deepest in late winter as a result of surface cooling and winter storms and quite shallow in summer. Its dynamics is governed by turbulent mixing as well as Ekman transport, exchanges with the overlying atmosphere, and horizontal advection. +The upper ocean, characterized by warm temperatures and active motion, varies in depth from 100 m or less in the tropics and eastern oceans to in excess of 800 meters in the western subtropical oceans. This layer exchanges properties such as heat and freshwater with the atmosphere on timescales of a few years. Below the mixed layer the upper ocean is generally governed by the hydrostatic and geostrophic relationships. Exceptions include the deep tropics and coastal regions. +The deep ocean is both cold and dark with generally weak velocities (although limited areas of the deep ocean are known to have significant recirculations). The deep ocean is supplied with water from the upper ocean in only a few limited geographical regions: the subpolar North Atlantic and several sinking regions around the Antarctic. Because of the weak supply of water to the deep ocean the average residence time of water in the deep ocean is measured in hundreds of years. In this layer as well the hydrostatic and geostrophic relationships are generally valid and mixing is generally quite weak. + + +== Primitive equations == +Ocean dynamics are governed by Newton's equations of motion expressed as the Navier-Stokes equations for a fluid element located at (x,y,z) on the surface of our rotating planet and moving at velocity (u,v,w) relative to that surface: + +the zonal momentum equation: + + + + + + + D + u + + + D + t + + + + = + − + + + 1 + ρ + + + + + + ∂ + p + + + ∂ + x + + + + + + f + v + + + + + 1 + ρ + + + + + + ∂ + + τ + + x + + + + + ∂ + z + + + + + + {\displaystyle {\frac {Du}{Dt}}=-{\frac {1}{\rho }}{\frac {\partial p}{\partial x}}+fv+{\frac {1}{\rho }}{\frac {\partial \tau _{x}}{\partial z}}} + + +the meridional momentum equation: + + + + + + + D + v + + + D + t + + + + = + − + + + 1 + ρ + + + + + + ∂ + p + + + ∂ + y + + + + − + f + u + + + + + 1 + ρ + + + + + + ∂ + + τ + + y + + + + + ∂ + z + + + + + + {\displaystyle {\frac {Dv}{Dt}}=-{\frac {1}{\rho }}{\frac {\partial p}{\partial y}}-fu+{\frac {1}{\rho }}{\frac {\partial \tau _{y}}{\partial z}}} + + +the vertical momentum equation (assumes the ocean is in hydrostatic balance): + + + + + + + ∂ + p + + + ∂ + z + + + + = + − + ρ + g + + + {\displaystyle {\frac {\partial p}{\partial z}}=-\rho g} + + +the continuity equation (assumes the ocean is incompressible): + + + + + + + ∂ + u + + + ∂ + x + + + + + + + + + ∂ + v + + + ∂ + y + + + + + + + + + ∂ + w + + + ∂ + z + + + + = + 0 + + + {\displaystyle {\frac {\partial u}{\partial x}}+{\frac {\partial v}{\partial y}}+{\frac {\partial w}{\partial z}}=0} + + +the temperature equation: + + + + + + + ∂ + T + + + ∂ + t + + + + + + u + + + + ∂ + T + + + ∂ + x + + + + + + v + + + + ∂ + T + + + ∂ + y + + + + + + w + + + + ∂ + T + + + ∂ + z + + + + = + Q + . + + + {\displaystyle {\frac {\partial T}{\partial t}}+u{\frac {\partial T}{\partial x}}+v{\frac {\partial T}{\partial y}}+w{\frac {\partial T}{\partial z}}=Q.} + + +the salinity equation: + + + + + + + ∂ + S + + + ∂ + t + + + + + + u + + + + ∂ + S + + + ∂ + x + + + + + + v + + + + ∂ + S + + + ∂ + y + + + + + + w + + + + ∂ + S + + + ∂ + z + + + + = + ( + E + − + P + ) + S + ( + z + = + 0 + ) + . + + + {\displaystyle {\frac {\partial S}{\partial t}}+u{\frac {\partial S}{\partial x}}+v{\frac {\partial S}{\partial y}}+w{\frac {\partial S}{\partial z}}=(E-P)S(z=0).} + + +Here "u" is zonal velocity, "v" is meridional velocity, "w" is vertical velocity, "p" is pressure, "ρ" is density, "T" is temperature, "S" is salinity, "g" is acceleration due to gravity, "τ" is wind stress, and "f" is the Coriolis parameter. "Q" is the heat input to the ocean, while "P-E" is the freshwater input to the ocean. + + +== Mixed layer dynamics == +Mixed layer dynamics are quite complicated; however, in some regions some simplifications are possible. The wind-driven horizontal transport in the mixed layer is approximately described by Ekman Layer dynamics in which vertical diffusion of momentum balances the Coriolis effect and wind stress. This Ekman transport is superimposed on geostrophic flow associated with horizontal gradients of density. + + +== Upper ocean dynamics == +Horizontal convergences and divergences within the mixed layer due, for example, to Ekman transport convergence imposes a requirement that ocean below the mixed layer must move fluid particles vertically. But one of the implications of the geostrophic relationship is that the magnitude of horizontal motion must greatly exceed the magnitude of vertical motion. Thus the weak vertical velocities associated with Ekman transport convergence (measured in meters per day) cause horizontal motion with speeds of 10 centimeters per second or more. The mathematical relationship between vertical and horizontal velocities can be derived by expressing the idea of conservation of angular momentum for a fluid on a rotating sphere. This relationship (with a couple of additional approximations) is known to oceanographers as the Sverdrup relation. Among its implications is the result that the horizontal convergence of Ekman transport observed to occur in the subtropical North Atlantic and Pacific forces southward flow throughout the interior of these two oceans. Western boundary currents (the Gulf Stream and Kuroshio) exist in order to return water to higher latitude. + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_fertilization-0.md b/data/en.wikipedia.org/wiki/Ocean_fertilization-0.md new file mode 100644 index 000000000..1b81fd386 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_fertilization-0.md @@ -0,0 +1,25 @@ +--- +title: "Ocean fertilization" +chunk: 1/4 +source: "https://en.wikipedia.org/wiki/Ocean_fertilization" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:53.616567+00:00" +instance: "kb-cron" +--- + +Ocean fertilization or ocean nourishment refers to both natural and intentional processes that replenish iron and other nutrients in the upper ocean, which in turn stimulate the growth of phytoplankton and in some circumstances draw down large amounts of carbon dioxide (CO2) through photosynthesis. Intentional ocean fertilization is biomimicry of natural processes that have removed atmospheric CO2 before ice ages as well as after volcanic eruptions, whale defecation, and near hydrothermal vents. The introduction of nutrients to the upper ocean increases marine food production as well as removing carbon dioxide from the atmosphere. + +Ocean nutrient fertilization, for example iron fertilization, (OIF) can stimulate photosynthesis in phytoplankton. The phytoplankton converts the ocean's dissolved carbon dioxide into carbohydrate, some of which has been shown to sink into the deeper ocean. More than a dozen open-sea experiments confirmed that adding iron to the ocean increases photosynthesis in phytoplankton by up to 30 times. +Ocean iron fertilization is one of the more well-researched carbon dioxide removal (CDR) approaches, and supported by climate restoration proponents. However, there is uncertainty about this approach regarding the duration of the effective oceanic carbon sequestration. A National Academies of Science, Engineering and Medicine (NASEM) 2021 study on marine CDR (mCDR) concludes that OIF has among the highest potential of mCDR approaches. +NASEM also calculates the cost of OIF at 40 cents per ton of CO2 removed, although attendant research efforts would add additional cost. The report indicates that there is medium-high confidence that the technique could be efficient and scalable at low cost, with medium environmental risks. "This biotic approach has relatively high scalability and low costs for deployment, though challenges would include verifiable C accounting and, as for most ocean CDR at scale, careful monitoring of intended and unexpected ecological effects up and down the food chain." +Peter Fiekowsky and Carole Douglis write, "I consider iron fertilization an important item on our list of potential climate restoration solutions. Given the fact that iron fertilization is a natural process that has taken place on a massive scale for millions of years, it is likely that most of the side effects are familiar ones that pose no major threat." +A number of techniques, including fertilization by the micronutrient iron (called iron fertilization) or with nitrogen and phosphorus (both macronutrients), have been proposed. Some research in the early 2020s suggested that it could only permanently sequester a small amount of carbon. More recent research publications sustain that iron fertilization shows promise. A NOAA special report rated iron fertilization as having "a moderate potential for cost, scalability and how long carbon might be stored compared to other marine sequestration ideas" + +== Rationale == +The marine food chain is based on photosynthesis by marine phytoplankton that combine carbon with inorganic nutrients to produce organic matter. Production is limited by the availability of nutrients, most commonly nitrogen or iron. Numerous experiments have demonstrated how iron fertilization can increase phytoplankton productivity. Nitrogen is a limiting nutrient over much of the ocean and can be supplied from various sources, including fixation by cyanobacteria. Carbon-to-iron ratios in phytoplankton are much larger than carbon-to-nitrogen or carbon-to-phosphorus ratios, so iron has the highest potential for sequestration per unit mass added. +Oceanic carbon naturally cycles between the surface and the deep via two "pumps" of similar scale. The "solubility" pump is driven by ocean circulation and the solubility of CO2 in seawater. The "biological" pump is driven by phytoplankton and subsequent settling of detrital particles or dispersion of dissolved organic carbon. The former has increased as a result of increasing atmospheric CO2 concentration. This CO2 sink is estimated to be approximately 2 GtC yr−1. +The global phytoplankton population fell about 40 percent between 1950 and 2008 or about 1 percent per year. The most notable declines took place in polar waters and in the tropics. The decline is attributed to sea surface temperature increases. A separate study found that diatoms, the largest type of phytoplankton, declined more than 1 percent per year from 1998 to 2012, particularly in the North Pacific, North Indian and Equatorial Indian oceans. The decline appears to reduce pytoplankton's ability to sequester carbon in the deep ocean. +Fertilization offers the prospect of both reducing the concentration of atmospheric greenhouse gases with the aim of slowing climate change and at the same time increasing fish stocks via increasing primary production. The reduction reduces the ocean's rate of carbon sequestration in the deep ocean. +Each area of the ocean has a base sequestration rate on some timescale, e.g., annual. Fertilization must increase that rate, but must do so on a scale beyond the natural scale. Otherwise, fertilization changes the timing, but not the total amount sequestered. However, accelerated timing may have beneficial effects for primary production separate from those from sequestration. +Biomass production inherently depletes all resources (save for sun and water). Either they must all be subject to fertilization or sequestration will eventually be limited by the one mostly slowly replenished (after some number of cycles) unless the ultimate limiting resource is sunlight and/or surface area. Generally, phosphate is the ultimate limiting nutrient. As oceanic phosphorus is depleted (via sequestration) it would have to be included in the fertilization cocktail supplied from terrestrial sources. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_fertilization-1.md b/data/en.wikipedia.org/wiki/Ocean_fertilization-1.md new file mode 100644 index 000000000..59ddfba56 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_fertilization-1.md @@ -0,0 +1,170 @@ +--- +title: "Ocean fertilization" +chunk: 2/4 +source: "https://en.wikipedia.org/wiki/Ocean_fertilization" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:53.616567+00:00" +instance: "kb-cron" +--- + +== Approaches == +Phytoplankton require a variety of nutrients. These include macronutrients such as nitrate and phosphate (in relatively high concentrations) and micronutrients such as iron and zinc (in much smaller quantities). Nutrient requirements vary across phylogenetic groups (e.g., diatoms require silicon) but may not individually limit total biomass production. Co-limitation (among multiple nutrients) may also mean that one nutrient can partially compensate for a shortage of another. Silicon does not affect total production, but can change the timing and community structure with follow-on effects on remineralization times and subsequent mesopelagic nutrient vertical distribution. +High-nutrient, low-chlorophyll (HNLC) waters occupy the oceans' subtropical gyre systems, approximately 40 per cent of the surface, where wind-driven downwelling and a strong thermocline impede nutrient resupply from deeper water. Nitrogen fixation by cyanobacteria provides a major source of N. In effect, it ultimately prevents the ocean from losing the N required for photosynthesis. Phosphorus has no substantial supply route, making it the ultimate limiting macronutrient. The sources that fuel primary production are deep water stocks and runoff or dust-based. + +=== Iron === + +=== Phosphorus === +In the very long term, phosphorus "is often considered to be the ultimate limiting macronutrient in marine ecosystems" and has a slow natural cycle. Where phosphate is the limiting nutrient in the photic zone, addition of phosphate is expected to increase primary phytoplankton production. This technique can give 0.83 W/m2 of globally averaged negative forcing, which is sufficient to reverse the warming effect of about half the current levels of anthropogenic CO2 emissions. One water-soluble fertilizer is diammonium phosphate (DAP), (NH4)2HPO4, that as of 2008 had a market price of 1700/tonne−1 of phosphorus. Using that price and the C : P Redfield ratio of 106 : 1 produces a sequestration cost (excluding preparation and injection costs) of some $45 /tonne of carbon (2008), substantially less than the trading price for carbon emissions. + +=== Nitrogen (urea) === +This technique proposes to fertilize the ocean with urea, a nitrogen rich substance, to encourage phytoplankton growth. Concentrations of macronutrients per area of ocean surface would be similar to large natural upwellings. Once exported from the surface, the carbon remains sequestered for a long time. +An Australian company, Ocean Nourishment Corporation (ONC), planned to inject hundreds of tonnes of urea into the ocean, in order to boost the growth of CO2-absorbing phytoplankton, as a way to combat climate change. In 2007, Sydney-based ONC completed an experiment involving one tonne of nitrogen in the Sulu Sea off the Philippines. This project was criticized by many institutions, including the European Commission, due to lack of knowledge of side effects on the marine ecosystem. +Macronutrient nourishment can give 0.38 W/m2 of globally averaged negative forcing, which is sufficient to reverse the warming effect of current levels of around a quarter of anthropogenic CO2 emissions. +The two dominant costs are manufacturing the nitrogen and nutrient delivery. + +In waters with sufficient iron micro nutrients, but a deficit of nitrogen, urea fertilization is the better choice for algae growth. Urea is the most used fertilizer in the world, due to its high content of nitrogen, low cost and high reactivity towards water. When exposed to ocean waters, urea is metabolized by phytoplankton via urease enzymes to produce ammonia. + + + + + + CO + + + ( + + NH + + 2 + + + + + + ) + + + 2 + + + + + + + + + H + + 2 + + + + + + O + + + → + + u + r + e + a + s + e + + + + + NH + + 3 + + + + + + + + + NH + + 2 + + + + + + COOH + + + + {\displaystyle {\ce {CO(NH_2)_2 + H_2O ->[urease] NH_3 + NH_2COOH}}} + + + + + + + + NH + + 2 + + + + + + COOH + + + + H + + 2 + + + + + + O + ⟶ + + NH + + 3 + + + + + + + + + H + + 2 + + + + + + + CO + + 3 + + + + + + + + + {\displaystyle {\ce {NH_2COOH + H_2O -> NH_3 + H_2CO_3}}} + + +The intermediate product carbamate also reacts with water to produce a total of two ammonia molecules. +Another cause of concern is the sheer amount of urea needed to capture the same amount of carbon as eq. iron fertilization. The nitrogen to iron ratio in a typical algae cell is 16:0.0001, meaning that for every iron atom added to the ocean a substantial larger amount of carbon is captured compared to adding one atom of nitrogen. Scientists also emphasize that adding urea to ocean waters could reduce oxygen content and result in a rise of toxic marine algae. This could potentially have devastating effects on fish populations, which others argue would be benefiting from the urea fertilization (the argument being that fish populations would feed on healthy phytoplankton). + +=== Pelagic pumping === +Local wave power could be used to pump nutrient-rich water from hundred- metre-plus depths to the euphotic zone. However, deep water concentrations of dissolved CO2 could be returned to the atmosphere. +The supply of DIC in upwelled water is generally sufficient for photosynthesis permitted by upwelled nutrients, without requiring atmospheric CO2. Second-order effects include how the composition of upwelled water differs from that of settling particles. More nitrogen than carbon is remineralized from sinking organic material. Upwelling of this water allows more carbon to sink than that in the upwelled water, which would make room for at least some atmospheric CO2 to be absorbed. the magnitude of this difference is unclear. No comprehensive studies have yet resolved this question. Preliminary calculations using upper limit assumptions indicate a low value. 1,000 square kilometres (390 sq mi) could sequester 1  gigatonne/year. +Sequestration thus depends on the upward flux and the rate of lateral surface mixing of the surface water with denser pumped water. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_fertilization-2.md b/data/en.wikipedia.org/wiki/Ocean_fertilization-2.md new file mode 100644 index 000000000..6fc5527f8 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_fertilization-2.md @@ -0,0 +1,38 @@ +--- +title: "Ocean fertilization" +chunk: 3/4 +source: "https://en.wikipedia.org/wiki/Ocean_fertilization" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:53.616567+00:00" +instance: "kb-cron" +--- + +=== Volcanic ash === +Volcanic ash adds nutrients to the surface ocean. This is most apparent in nutrient-limited areas. Research on the effects of anthropogenic and aeolian iron addition to the ocean surface suggests that nutrient-limited areas benefit most from a combination of nutrients provided by anthropogenic, eolian and volcanic deposition. Some oceanic areas are comparably limited in more than one nutrient, so fertilization regimes that includes all limited nutrients is more likely to succeed. Volcanic ash supplies multiple nutrients to the system, but excess metal ions can be harmful. The positive impacts of volcanic ash deposition are potentially outweighed by their potential to do harm. +Clear evidence documents that ash can be as much as 45 percent by weight in some deep marine sediments. In the Pacific Ocean estimates claim that (on a millennial-scale) the atmospheric deposition of air-fall volcanic ash was as high as the deposition of desert dust. This indicates the potential of volcanic ash as a significant iron source. +In August 2008 the Kasatochi volcanic eruption in the Aleutian Islands, Alaska, deposited ash in the nutrient-limited northeast Pacific. This ash (including iron) resulted in one of the largest phytoplankton blooms observed in the subarctic. Fisheries scientists in Canada linked increased oceanic productivity from the volcanic iron to subsequent record returns of salmon in the Fraser River two years later + +=== Monitored nutrients === +The approach advocated by Ocean Nutrition Corporation is to limit the distribution of added nutrients to allow phytoplankton concentrations to rise only to the values seen in upwelling regions (5–10 mg Chl/m3). Maintaining healthy phytoplankton levels is claimed to avoid harmful algal blooms and oxygen depletion. Chlorophyll concentration is an easily measured proxy for phytoplankton concentration. The company stated that values of approximately 4 mg Chl/m3 meet this requirement. SS + +== Complications == +While manipulation of the land ecosystem in support of agriculture for the benefit of humans has long been accepted (despite its side effects), directly enhancing ocean productivity has not. Among the reasons are: + +=== Outright opposition === +According to Lisa Speer of the Natural Resources Defense Council, "There is a limited amount of money, of time, that we have to deal with this problem....The worst possible thing we could do for climate change technologies would be to invest in something that doesn't work and that has big impacts that we don't anticipate." +In 2009 Aaron Strong, Sallie Chisholm, Charles Miller and John Cullen opined in Nature "...fertilizing the oceans with iron to stimulate phytoplankton blooms, absorb carbon dioxide from the atmosphere and export carbon to the deep sea – should be abandoned." +In Science, Warren Cornwall mentions "Tests have shown the iron does stimulate plankton growth. But key questions remain, says Dave Siegel, a marine scientist at the University of California, Santa Barbara, who served on the NASEM panel. How much of the absorbed carbon makes it to the deep +ocean is uncertain", while Wil Burns, an ocean law expert at Northwestern University declares that "...making iron fertilization a research priority is "barking mad" since "...a recent survey of 13 past fertilization experiments found only one that increased carbon levels deep in the ocean." + +=== Efficiency === +Algal cell chemical composition is often assumed to respect a ratio where atoms are 106 carbon: 16 nitrogen: 1 phosphorus (Redfield ratio): 0.0001 iron. Thus, each atom of iron in an iron-constrained environment helps capture 1,060,000 atoms of carbon, while a nitrogen atom in a nitrogen-constrained environment would only capture 6. In large areas of the ocean, such organic growth (and hence nitrogen fixation) is thought to be limited by the lack of iron rather than nitrogen, although direct measures are hard. +On the other hand, experimental iron fertilisation in HNLC regions has been supplied with excess iron which cannot be utilized before it is scavenged. Thus the organic material produced was much less than if the ratio of nutrients above were achieved. Only a fraction of the available nitrogen (because of iron scavenging) is drawn down. In culture bottle studies of oligotrophic water, adding nitrogen and phosphorus can draw down considerably more nitrogen per dosing. The export production is only a small percentage of the new primary production and in the case of iron fertilization, iron scavenging means that regenerative production is small. With macronutrient fertilisation, regenerative production is expected to be large and supportive of larger total export. Other losses can also reduce efficiency. +In addition, the efficiency of carbon sequestration through ocean fertilisation is heavily influenced by factors such as changes in stoichiometric ratios and gas exchange make accurately predicting the effectiveness of ocean feralization projects. +Fertilisation also does not create a permanent carbon sink. "Ocean fertilisation options are only worthwhile if sustained on a millennial timescale and phosphorus addition may have greater long-term potential than iron or nitrogen fertilisation." + +=== Side effects === +Beyond biological impacts, evidences suggests that plankton blooms can affect the physical properties of surface waters simply by absorbing light and heat from the sun. Watson added that if fertilization is done in shallow coastal waters, a dense layer of phytoplankton clouding the top 30 metres or so of the ocean could hinder corals, kelps or other deeper sea life from carrying out photosynthesis (Watson et al. 2008). In addition, as the bloom declines, nitrous oxide is released, potentially counteracting the effects from the sequestering of carbon. + +==== Algal blooms ==== +Toxic algal blooms are common in coastal areas. Fertilization could trigger such blooms. Chronic fertilization could risk the creation of dead zones, such as the one in the Gulf of Mexico. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_fertilization-3.md b/data/en.wikipedia.org/wiki/Ocean_fertilization-3.md new file mode 100644 index 000000000..73606357c --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_fertilization-3.md @@ -0,0 +1,52 @@ +--- +title: "Ocean fertilization" +chunk: 4/4 +source: "https://en.wikipedia.org/wiki/Ocean_fertilization" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:53.616567+00:00" +instance: "kb-cron" +--- + +==== Impact on fisheries ==== +Adding urea to the ocean can cause phytoplankton blooms that serve as a food source for zooplankton and in turn feed for fish. This may increase fish catches. However, if cyanobacteria and dinoflagellates dominate phytoplankton assemblages that are considered poor quality food for fish then the increase in fish quantity may not be large. Some evidence links iron fertilization from volcanic eruptions to increased fisheries production. Other nutrients would be metabolized along with the added nutrient(s), reducing their presence in fertilized waters. +Krill populations have declined dramatically since whaling began. Sperm whales transport iron from the deep ocean to the surface during prey consumption and defecation. Sperm whales have been shown to increase the levels of primary production and carbon export to the deep ocean by depositing iron-rich faeces into surface waters of the Southern Ocean. The faeces causes phytoplankton to grow and take up carbon. The phytoplankton nourish krill. Reducing the abundance of sperm whales in the Southern Ocean, whaling resulted in an extra 2 million tonnes of carbon remaining in the atmosphere each year. + +==== Ecosystem disruption ==== +Many locations, such as the Tubbataha Reef in the Sulu Sea, support high marine biodiversity. Nitrogen or other nutrient loading in coral reef areas can lead to community shifts towards algal overgrowth of corals and ecosystem disruption, implying that fertilization must be restricted to areas in which vulnerable populations are not put at risk. +As the phytoplankton descend the water column, they decay, consuming oxygen and producing greenhouse gases methane and nitrous oxide. Plankton-rich surface waters could warm the surface layer, affecting circulation patterns. + +==== Cloud formation ==== +Many phytoplankton species release dimethyl sulfide (DMS), which escapes into the atmosphere where it forms sulfate aerosols and encourages cloud formation, which could reduce warming. However, substantial increases in DMS could reduce global rainfall, according to global climate model simulations, while halving temperature increases as of 2100. + +== Reactions == +In 2007 Working Group III of the United Nations Intergovernmental Panel on Climate Change examined ocean fertilization methods in its fourth assessment report and noted that the field-study estimates of the amount of carbon removed per ton of iron was probably over-estimated and that potential adverse effects had not been fully studied. +In June 2007 the London Dumping Convention issued a statement of concern noting 'the potential for large scale ocean iron fertilization to have negative impacts on the marine environment and human health', but did not define 'large scale'. It is believed that the definition would include operations. +In 2008, the London Convention/London Protocol noted in resolution LC-LP.1 that knowledge on the effectiveness and potential environmental impacts of ocean fertilization was insufficient to justify activities other than research. This non-binding resolution stated that fertilization, other than research, "should be considered as contrary to the aims of the Convention and Protocol and do not currently qualify for any exemption from the definition of dumping". +In May 2008, at the Convention on Biological Diversity, 191 nations called for a ban on ocean fertilization until scientists better understand the implications. +In August 2018, Germany banned the sale of ocean seeding as carbon sequestration system while the matter was under discussion at EU and EASAC levels. + +== International law == +International law presents some dilemmas for ocean fertilization. The United Nations Framework Convention on Climate Change (UNFCCC 1992) has accepted mitigation actions. + +=== Law of the sea === +According to United Nations Convention on the Law of the Sea (LOSC 1982), all states are obliged to take all measures necessary to prevent, reduce and control pollution of the marine environment, to prohibit the transfer of damage or hazards from one area to another and to prohibit the transformation of one type pollution to another. How this relates to fertilization is undetermined. + +== Solar radiation management == + +Fertilization may create sulfate aerosols that reflect sunlight, modifying the Earth's albedo, creating a cooling effect that reduces some of the effects of climate change. Enhancing the natural sulfur cycle in the Southern Ocean by fertilizing with iron in order to enhance dimethyl sulfide production and cloud reflectivity may achieve this. + +== See also == +Carbon dioxide sink +Climate engineering +Effects of climate change on oceans +Iron fertilization +Planetary engineering +Soil fertilization + +== References == + +== External links == +Williamson, Phillip; Wallace, Douglas W. R.; Law, Cliff S.; Boyd, Philip W.; Collos, Yves; Croot, Peter; Denman, Ken; Riebesell, Ulf; Takeda, Shigenobu (1 November 2012). "Ocean fertilization for geoengineering: A review of effectiveness, environmental impacts and emerging governance". Process Safety and Environmental Protection. 90 (6): 475–488. Bibcode:2012PSEP...90..475W. doi:10.1016/j.psep.2012.10.007. ISSN 0957-5820. +Dean, Jennie (2009). "Iron Fertilization: A Scientific Review with International Policy Recommendations" (PDF). Retrieved 4 June 2017. +"Ocean fertilization" (PDF). geoengineeringmonitor.org. January 2021. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-0.md b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-0.md new file mode 100644 index 000000000..2684fcd80 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-0.md @@ -0,0 +1,29 @@ +--- +title: "Ocean thermal energy conversion" +chunk: 1/10 +source: "https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:54.854158+00:00" +instance: "kb-cron" +--- + +Ocean thermal energy conversion (OTEC) is a renewable energy technology that harnesses the temperature difference between the warm surface waters of the ocean and the cold depths to run a heat engine to produce electricity. It is a unique form of clean energy generation that has the potential to provide a consistent and sustainable source of power. Although it has challenges to overcome, OTEC has the potential to provide a consistent and sustainable source of clean energy, particularly in tropical regions with access to deep ocean water. + +== Description == +OTEC uses the ocean thermal gradient between cooler deep and warmer shallow or surface seawaters to run a heat engine and produce useful work, usually in the form of electricity. OTEC can operate with a very high capacity factor and so can operate in base load mode. +The denser cold water masses, formed by ocean surface water interaction with cold atmosphere in quite specific areas of the North Atlantic and the Southern Ocean, sink into the deep sea basins and spread in entire deep ocean by the thermohaline circulation. Upwelling of cold water from the deep ocean is replenished by the downwelling of cold surface sea water. +Among ocean energy sources, OTEC is one of the continuously available renewable energy resources that could contribute to base-load power supply. The resource potential for OTEC is considered to be much larger than for other ocean energy forms. Up to 10,000 TWh/yr of power could be generated from OTEC without affecting the ocean's thermal structure. +Systems may be either closed-cycle or open-cycle. Closed-cycle OTEC uses working fluids that are typically thought of as refrigerants such as ammonia or R-134a. These fluids have low boiling points, and are therefore suitable for powering the system's generator to generate electricity. The most commonly used heat cycle for OTEC to date is the Rankine cycle, using a low-pressure turbine. Open-cycle engines use vapor from the seawater itself as the working fluid. +OTEC can also supply quantities of cold water as a by-product. This can be used for air conditioning and refrigeration and the nutrient-rich deep ocean water can feed biological technologies. Another by-product is fresh water distilled from the sea. +OTEC theory was first developed in the 1880s and the first bench size demonstration model was constructed in 1926. Currently operating pilot-scale OTEC plants are located in Japan, overseen by Saga University, and in Hawaii operated by Makai Ocean Engineering. + +== History == + +Attempts to develop and refine OTEC technology started in the 1880s. In 1881, Jacques Arsene d'Arsonval, a French physicist, proposed tapping the thermal energy of the ocean. D'Arsonval's student, Georges Claude, built the first OTEC plant, in Matanzas, Cuba in 1930. The system generated 22 kW of electricity with a low-pressure turbine. The plant was later destroyed in a storm. +In 1935, Claude constructed a plant aboard a 10,000-ton cargo vessel moored off the coast of Brazil. Weather and waves destroyed it before it could generate net power. (Net power is the amount of power generated after subtracting power needed to run the system). +In 1956, French scientists designed a 3 MW plant for Abidjan, Ivory Coast. The plant was never completed, because new finds of large amounts of cheap petroleum made it uneconomical. +In 1962, J. Hilbert Anderson and James H. Anderson, Jr. focused on increasing component efficiency. They patented their new "closed cycle" design in 1967. This design improved upon the original closed-cycle Rankine system, and included this in an outline for a plant that would produce power at lower cost than oil or coal. At the time, however, their research garnered little attention since coal and nuclear were considered the future of energy. +Japan is a major contributor to the development of OTEC technology. Beginning in 1970 the Tokyo Electric Power Company successfully built and deployed a 100 kW closed-cycle OTEC plant on the island of Nauru. The plant became operational on 14 October 1981, producing about 120 kW of electricity; 90 kW was used to power the plant and the remaining electricity was used to power a school and other places. This set a world record for power output from an OTEC system where the power was sent to a real (as opposed to an experimental) power grid. +1981 also saw a major development in OTEC technology when Russian engineer, Dr. Alexander Kalina, used a mixture of ammonia and water to produce electricity. This new ammonia-water mixture greatly improved the efficiency of the power cycle. In 1994, the Institute of Ocean Energy at Saga University designed and constructed a 4.5 kW plant for the purpose of testing a newly invented Uehara cycle, also named after its inventor Haruo Uehara. This cycle included absorption and extraction processes that allow this system to outperform the Kalina cycle by 1–2%. +The 1970s saw an uptick in OTEC research and development during the post 1973 Arab-Israeli War, which caused oil prices to triple. The U.S. federal government poured $260 million into OTEC research after President Carter signed a law that committed the US to a production goal of 10,000 MW of electricity from OTEC systems by 1999. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-1.md b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-1.md new file mode 100644 index 000000000..1b3e1d37c --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-1.md @@ -0,0 +1,22 @@ +--- +title: "Ocean thermal energy conversion" +chunk: 2/10 +source: "https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:54.854158+00:00" +instance: "kb-cron" +--- + +In 1974, The U.S. established the Natural Energy Laboratory of Hawaii Authority (NELHA) at Keahole Point on the Kona coast of Hawaii. Hawaii is the best US OTEC location, due to its warm surface water, access to very deep, very cold water, and high electricity costs. The laboratory has become a leading test facility for OTEC technology. In the same year, Lockheed received a grant from the U.S. National Science Foundation to study OTEC. This eventually led to an effort by Lockheed, the US Navy, Makai Ocean Engineering, Dillingham Construction, and other firms to build the world's first and only net-power producing OTEC plant, dubbed "Mini-OTEC" For three months in 1979, a small amount of electricity was generated. NELHA operated a 250 kW demonstration plant for six years in the 1990s. With funding from the United States Navy, a 105 kW plant at the site began supplying energy to the local power grid in 2015. +A European initiative EUROCEAN - a privately funded joint venture of 9 European companies already active in offshore engineering - was active in promoting OTEC from 1979 to 1983. Initially a large scale offshore facility was studied. Later a 100 kW land based installation was studied combining land based OTEC with Desalination and Aquaculture nicknamed ODA. This was based on the results from a small scale aquaculture facility at the island of St Croix that used a deepwater supply line to feed the aquaculture basins. Also a shore based open cycle plant was investigated. +The location of the case of study was the Dutch Kingdom related island Curaçao. +Research related to making open-cycle OTEC a reality began earnestly in 1979 at the Solar Energy Research Institute (SERI) with funding from the US Department of Energy. Evaporators and suitably configured direct-contact condensers were developed and patented by SERI (see). An original design for a power-producing experiment, then called the 165-kW experiment was described by Kreith and Bharathan and as the Max Jakob Memorial Award Lecture. The initial design used two parallel axial turbines, using last stage rotors taken from large steam turbines. Later, a team led by Dr. Bharathan at the National Renewable Energy Laboratory (NREL) developed the initial conceptual design for up-dated 210 kW open-cycle OTEC experiment (). This design integrated all components of the cycle, namely, the evaporator, condenser and the turbine into one single vacuum vessel, with the turbine mounted on top to prevent any potential for water to reach it. The vessel was made of concrete as the first process vacuum vessel of its kind. Attempts to make all components using low-cost plastic material could not be fully achieved, as some conservatism was required for the turbine and the vacuum pumps developed as the first of their kind. Later Dr. Bharathan worked with a team of engineers at the Pacific Institute for High Technology Research (PICHTR) to further pursue this design through preliminary and final stages. It was renamed the Net Power Producing Experiment (NPPE) and was constructed at the Natural Energy Laboratory of Hawaii (NELH) by PICHTR by a team led by Chief Engineer Don Evans and the project was managed by Dr. Luis Vega. + +In 2002, India tested a 1 MW floating OTEC pilot plant near Tamil Nadu. The plant was ultimately unsuccessful due to a failure of the deep sea cold water pipe. Its government continues to sponsor research. +In 2006, Makai Ocean Engineering was awarded a contract from the U.S. Office of Naval Research (ONR) to investigate the potential for OTEC to produce nationally significant quantities of hydrogen in at-sea floating plants located in warm, tropical waters. Realizing the need for larger partners to actually commercialize OTEC, Makai approached Lockheed Martin to renew their previous relationship and determine if the time was ready for OTEC. And so in 2007, Lockheed Martin resumed work in OTEC and became a subcontractor to Makai to support their SBIR, which was followed by other subsequent collaborations +In March 2011, Ocean Thermal Energy Corporation signed an Energy Services Agreement (ESA) with the Baha Mar resort, Nassau, Bahamas, for the world's first and largest seawater air conditioning (SWAC) system. In June 2015, the project was put on pause while the resort resolved financial and ownership issues. In August 2016, it was announced that the issues had been resolved and that the resort would open in March 2017. It is expected that the SWAC system's construction will resume at that time. + +In July 2011, Makai Ocean Engineering completed the design and construction of an OTEC Heat Exchanger Test Facility at the Natural Energy Laboratory of Hawaii. The purpose of the facility is to arrive at an optimal design for OTEC heat exchangers, increasing performance and useful life while reducing cost (heat exchangers being the #1 cost driver for an OTEC plant). And in March 2013, Makai announced an award to install and operate a 105 kilowatt turbine on the OTEC Heat Exchanger Test Facility, this marked the first time that OTEC power was connected to the U.S. grid. +In July 2016, the Virgin Islands Public Services Commission approved Ocean Thermal Energy Corporation's application to become a Qualified Facility. The company is thus permitted to begin negotiations with the Virgin Islands Water and Power Authority (WAPA) for a Power Purchase Agreement (PPA) pertaining to an Ocean Thermal Energy Conversion (OTEC) plant on the island of St. Croix. This would be the world's first commercial OTEC plant. +A project is set to be installed in the African country of São Tomé and Príncipe, which will be the first commercial-scale floating OTEC platform in the world. Developed by Global OTEC, the structure named Dominique will generate 1.5MW, with subsequent barges being installed to help supply the full demand of the country. In 2022, an MoU was signed between the government and British startup Global OTEC. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-2.md b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-2.md new file mode 100644 index 000000000..9eba78fec --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-2.md @@ -0,0 +1,32 @@ +--- +title: "Ocean thermal energy conversion" +chunk: 3/10 +source: "https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:54.854158+00:00" +instance: "kb-cron" +--- + +== Currently operating OTEC plants == +In March 2013, Saga University with various Japanese industries completed the installation of a new OTEC plant. Okinawa Prefecture announced the start of the OTEC operation testing at Kume Island on April 15, 2013. The main aim is to prove the validity of computer models and demonstrate OTEC to the public. The testing and research will be conducted with the support of Saga University until the end of FY 2016. IHI Plant Construction Co. Ltd, Yokogawa Electric Corporation, and Xenesys Inc were entrusted with constructing the 100 kilowatt class plant within the grounds of the Okinawa Prefecture Deep Sea Water Research Center. The location was specifically chosen in order to utilize existing deep seawater and surface seawater intake pipes installed for the research center in 2000. The pipe is used for the intake of deep sea water for research, fishery, and agricultural use. +The plant consists of two 50 kW units in double Rankine configuration. The OTEC facility and deep seawater research center are open to free public tours by appointment in English and Japanese. Currently, this is one of only two fully operational OTEC plants in the world. This plant operates continuously when specific tests are not underway. +In 2011, Makai Ocean Engineering completed a heat exchanger test facility at NELHA. Used to test a variety of heat exchange technologies for use in OTEC, Makai has received funding to install a 105 kW turbine. Installation will make this facility the largest operational OTEC facility, though the record for largest power will remain with the Open Cycle plant also developed in Hawaii. +In July 2014, DCNS group partnered with Akuo Energy announced NER 300 funding for their NEMO project. If the project was successful, the 16 MW gross 10 MW net offshore plant would have been the largest OTEC facility to date. DCNS planned to have NEMO operational by 2020. Early in April 2018, Naval Energies shut down the project indefinitely due to technical difficulties relating to the main cold-water intake pipe. +An ocean thermal energy conversion power plant built by Makai Ocean Engineering went operational in Hawaii in August 2015. The governor of Hawaii, David Ige, "flipped the switch" to activate the plant. This is the first true closed-cycle ocean Thermal Energy Conversion (OTEC) plant to be connected to a U.S. electrical grid. It is a demo plant capable of generating 105 kilowatts, enough to power about 120 homes. + +== Thermodynamic efficiency == +A heat engine gives greater efficiency when run with a large temperature difference. In the oceans the temperature difference between surface and deep water is greatest in the tropics, although still a modest 20 to 25 °C. It is therefore in the tropics that OTEC offers the greatest possibilities. OTEC has the potential to offer global amounts of energy that are 10 to 100 times greater than other ocean energy options such as wave power. +OTEC plants can operate continuously providing a base load supply for an electrical power generation system. +The main technical challenge of OTEC is to generate significant amounts of power efficiently from small temperature differences. It is still considered an emerging technology. Early OTEC systems were 1 to 3 percent thermally efficient, well below the theoretical maximum 6 and 7 percent for this temperature difference. Modern designs allow performance approaching the theoretical maximum Carnot efficiency. + +== Power cycle types == +Cold seawater is an integral part of each of the three types of OTEC systems: closed-cycle, open-cycle, and hybrid. To operate, the cold seawater must be brought to the surface. The primary approaches are active pumping and desalination. Desalinating seawater near the sea floor lowers its density, which causes it to rise to the surface. +The alternative to costly pipes to bring condensing cold water to the surface is to pump vaporized low boiling point fluid into the depths to be condensed, thus reducing pumping volumes and reducing technical and environmental problems and lowering costs. + +=== Closed === + +Closed-cycle systems use fluid with a low boiling point, such as ammonia (having a boiling point around -33 °C at atmospheric pressure), to power a turbine to generate electricity. Warm surface seawater is pumped through a heat exchanger to vaporize the fluid. The expanding vapor turns the turbo-generator. Cold water, pumped through a second heat exchanger, condenses the vapor into a liquid, which is then recycled through the system. +In 1979, the Natural Energy Laboratory and several private-sector partners developed the "mini OTEC" experiment, which achieved the first successful at-sea production of net electrical power from closed-cycle OTEC. The mini OTEC vessel was moored 1.5 miles (2.4 km) off the Hawaiian coast and produced enough net electricity to illuminate the ship's light bulbs and run its computers and television. + +=== Open === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-3.md b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-3.md new file mode 100644 index 000000000..b397c5a52 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-3.md @@ -0,0 +1,32 @@ +--- +title: "Ocean thermal energy conversion" +chunk: 4/10 +source: "https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:54.854158+00:00" +instance: "kb-cron" +--- + +Open-cycle OTEC uses warm surface water directly to make electricity. The warm seawater is first pumped into a low-pressure container, which causes it to boil. In some schemes, the expanding vapor drives a low-pressure turbine attached to an electrical generator. The vapor, which has left its salt and other contaminants in the low-pressure container, is pure fresh water. It is condensed into a liquid by exposure to cold temperatures from deep-ocean water. This method produces desalinized fresh water, suitable for drinking water, irrigation or aquaculture. +In other schemes, the rising vapor is used in a gas lift technique of lifting water to significant heights. Depending on the embodiment, such vapor lift pump techniques generate power from a hydroelectric turbine either before or after the pump is used. +In 1984, the Solar Energy Research Institute (now known as the National Renewable Energy Laboratory) developed a vertical-spout evaporator to convert warm seawater into low-pressure steam for open-cycle plants. Conversion efficiencies were as high as 97% for seawater-to-steam conversion (overall steam production would only be a few percent of the incoming water). In May 1993, an open-cycle OTEC plant at Keahole Point, Hawaii, produced close to 80 kW of electricity during a net power-producing experiment. This broke the record of 40 kW set by a Japanese system in 1982. + +=== Hybrid === +A hybrid cycle combines the features of the closed- and open-cycle systems. In a hybrid, warm seawater enters a vacuum chamber and is flash-evaporated, similar to the open-cycle evaporation process. The steam vaporizes the ammonia working fluid of a closed-cycle loop on the other side of an ammonia vaporizer. The vaporized fluid then drives a turbine to produce electricity. The steam condenses within the heat exchanger and provides desalinated water (see heat pipe). + +=== Working fluids === +A popular choice of working fluid is ammonia, which has superior transport properties, easy availability, and low cost. Ammonia, however, is toxic and flammable. Fluorinated carbons such as CFCs and HCFCs are not toxic or flammable, but they contribute to ozone layer depletion. Hydrocarbons too are good candidates, but they are highly flammable; in addition, this would create competition for use of them directly as fuels. The power plant size is dependent upon the vapor pressure of the working fluid. With increasing vapor pressure, the size of the turbine and heat exchangers decreases while the wall thickness of the pipe and heat exchangers increase to endure high pressure especially on the evaporator side. + +== Land, shelf and floating sites == +OTEC has the potential to produce gigawatts of electrical power, and in conjunction with electrolysis, could produce enough hydrogen to completely replace all projected global fossil fuel consumption. Reducing costs remains an unsolved challenge, however. OTEC plants require a long, large diameter intake pipe, which is submerged a kilometer or more into the ocean's depths, to bring cold water to the surface. + +=== Land-based === +Land-based and near-shore facilities offer three main advantages over those located in deep water. Plants constructed on or near land do not require sophisticated mooring, lengthy power cables, or the more extensive maintenance associated with open-ocean environments. They can be installed in sheltered areas so that they are relatively safe from storms and heavy seas. Electricity, desalinated water, and cold, nutrient-rich seawater could be transmitted from near-shore facilities via trestle bridges or causeways. In addition, land-based or near-shore sites allow plants to operate with related industries such as mariculture or those that require desalinated water. +Favored locations include those with narrow shelves (volcanic islands), steep (15–20 degrees) offshore slopes, and relatively smooth sea floors. These sites minimize the length of the intake pipe. A land-based plant could be built well inland from the shore, offering more protection from storms, or on the beach, where the pipes would be shorter. In either case, easy access for construction and operation helps lower costs. +Land-based or near-shore sites can also support mariculture or chilled water agriculture. Tanks or lagoons built on shore allow workers to monitor and control miniature marine environments. Mariculture products can be delivered to market via standard transport. +One disadvantage of land-based facilities arises from the turbulent wave action in the surf zone. OTEC discharge pipes should be placed in protective trenches to prevent subjecting them to extreme stress during storms and prolonged periods of heavy seas. Also, the mixed discharge of cold and warm seawater may need to be carried several hundred meters offshore to reach the proper depth before it is released, requiring additional expense in construction and maintenance. +One way that OTEC systems can avoid some of the problems and expenses of operating in a surf zone is by building them just offshore in waters ranging from 10 to 30 meters deep (Ocean Thermal Corporation 1984). This type of plant would use shorter (and therefore less costly) intake and discharge pipes, which would avoid the dangers of turbulent surf. The plant itself, however, would require protection from the marine environment, such as breakwaters and erosion-resistant foundations, and the plant output would need to be transmitted to shore. + +=== Shelf based === +To avoid the turbulent surf zone as well as to move closer to the cold-water resource, OTEC plants can be mounted to the continental shelf at depths up to 100 meters (330 ft). A shelf-mounted plant could be towed to the site and affixed to the sea bottom. This type of construction is already used for offshore oil rigs. The complexities of operating an OTEC plant in deeper water may make them more expensive than land-based approaches. Problems include the stress of open-ocean conditions and more difficult product delivery. Addressing strong ocean currents and large waves adds engineering and construction expense. Platforms require extensive pilings to maintain a stable base. Power delivery can require long underwater cables to reach land. For these reasons, shelf-mounted plants are less attractive. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-4.md b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-4.md new file mode 100644 index 000000000..1eb89f156 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-4.md @@ -0,0 +1,34 @@ +--- +title: "Ocean thermal energy conversion" +chunk: 5/10 +source: "https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:54.854158+00:00" +instance: "kb-cron" +--- + +=== Floating === +Floating OTEC facilities operate off-shore. Although potentially optimal for large systems, floating facilities present several difficulties. The difficulty of mooring plants in very deep water complicates power delivery. Cables attached to floating platforms are more susceptible to damage, especially during storms. Cables at depths greater than 1000 meters are difficult to maintain and repair. Riser cables, which connect the sea bed and the plant, need to be constructed to resist entanglement. +As with shelf-mounted plants, floating plants need a stable base for continuous operation. Major storms and heavy seas can break the vertically suspended cold-water pipe and interrupt warm water intake as well. To help prevent these problems, pipes can be made of flexible polyethylene attached to the bottom of the platform and gimballed with joints or collars. Pipes may need to be uncoupled from the plant to prevent storm damage. As an alternative to a warm-water pipe, surface water can be drawn directly into the platform; however, it is necessary to prevent the intake flow from being damaged or interrupted during violent motions caused by heavy seas. +Connecting a floating plant to power delivery cables requires the plant to remain relatively stationary. Mooring is an acceptable method, but current mooring technology is limited to depths of about 2,000 meters (6,600 ft). Even at shallower depths, the cost of mooring may be prohibitive. + +== Political concerns == +Because OTEC facilities are more-or-less stationary surface platforms, their exact location and legal status may be affected by the United Nations Convention on the Law of the Sea treaty (UNCLOS). This treaty grants coastal nations 12-and-200-nautical-mile (22 and 370 km) zones of varying legal authority from land, creating potential conflicts and regulatory barriers. OTEC plants and similar structures would be considered artificial islands under the treaty, giving them no independent legal status. OTEC plants could be perceived as either a threat or potential partner to fisheries or to seabed mining operations controlled by the International Seabed Authority. + +== Cost and economics == +Because OTEC systems have not yet been widely deployed, cost estimates are uncertain. A 2010 study by University of Hawaii estimated the cost of electricity for OTEC at 94.0 cents per kilowatt hour (kWh) for a 1.4 MW plant, 44.0 cents per kWh for a 10 MW plant, and 18.0 cents per kWh for a 100 MW plant. A 2015 report by the organization Ocean Energy Systems under the International Energy Agency gave an estimate of about 20.0 cents per kWh for 100 MW plants. Another study estimated power generation costs as low as 7.0 cents per kWh. Comparing to other energy sources, a 2019 study by Lazard estimated the unsubsidized cost of electricity to 3.2 to 4.2 cents per kWh for Solar PV at utility scale and 2.8 to 5.4 cents per kWh for wind power. +A report published by IRENA in 2014 claimed that commercial use of OTEC technology can be scaled in a variety of ways. "...small-scale OTEC plants can be made to accommodate the electricity production of small communities (5,000–50,000 residents), but would require the production of valuable by-products – like fresh water or cooling – to be economically viable". Larger scaled OTEC plants would have a much higher overhead and installation costs. +Beneficial factors that should be taken into account include OTEC's lack of waste products and fuel consumption, the area in which it is available (often within 20° of the equator), the geopolitical effects of petroleum dependence, compatibility with alternate forms of ocean power such as wave energy, tidal energy and methane hydrates, and supplemental uses for the seawater. + +== Some proposed projects == +OTEC projects under consideration include a small plant for the U.S. Navy base on the British overseas territory island of Diego Garcia in the Indian Ocean. Ocean Thermal Energy Corporation (formerly OCEES International, Inc.) is working with the U.S. Navy on a design for a proposed 13-MW OTEC plant, to replace the current diesel generators. The OTEC plant would also provide 1.25 million gallons per day of potable water. This project is currently waiting for changes in US military contract policies. OTE has proposed building a 10-MW OTEC plant on Guam. + +=== Bahamas === +Ocean Thermal Energy Corporation (OTE) currently has plans to install two 10 MW OTEC plants in the US Virgin Islands and a 5–10 MW OTEC facility in The Bahamas. OTE has also designed the world's largest Seawater Air Conditioning (SWAC) plant for a resort in The Bahamas, which will use cold deep seawater as a method of air-conditioning. In mid-2015, the 95%-complete project was temporarily put on hold while the resort resolved financial and ownership issues. On August 22, 2016, the government of the Bahamas announced that a new agreement had been signed under which the Baha Mar resort will be completed. On September 27, 2016, Bahamian Prime Minister Perry Christie announced that construction had resumed on Baha Mar, and that the resort was slated to open in March 2017. +This is on hold, and may never resume. + +=== Hawaii === +Lockheed Martin's Alternative Energy Development team has partnered with Makai Ocean Engineering +to complete the final design phase of a 10-MW closed cycle OTEC pilot system which planned to become operational in Hawaii in the 2012–2013 time frame. This system was designed to expand to 100-MW commercial systems in the near future. In November, 2010 the U.S. Naval Facilities Engineering Command (NAVFAC) awarded Lockheed Martin a US$4.4 million contract modification to develop critical system components and designs for the plant, adding to the 2009 $8.1 million contract and two Department of Energy grants totaling over $1 million in 2008 and March 2010. +A small but operational ocean thermal energy conversion (OTEC) plant was inaugurated in Hawaii in August 2015. The opening of the research and development 100-kilowatt facility marked the first time a closed-cycle OTEC plant was connected to the U.S. grid. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-5.md b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-5.md new file mode 100644 index 000000000..6baf4989a --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-5.md @@ -0,0 +1,42 @@ +--- +title: "Ocean thermal energy conversion" +chunk: 6/10 +source: "https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:54.854158+00:00" +instance: "kb-cron" +--- + +=== Hainan === +On April 13, 2013, Lockheed contracted with the Reignwood Group to build a 10 megawatt plant off the coast of southern China to provide power for a planned resort on Hainan island. A plant of that size would power several thousand homes. The Reignwood Group acquired Opus Offshore in 2011 which forms its Reignwood Ocean Engineering division which also is engaged in development of deepwater drilling. + +=== Japan === +Currently the only continuously operating OTEC system is located in Okinawa Prefecture, Japan. The Governmental support, local community support, and advanced research carried out by Saga University were key for the contractors, IHI Plant Construction Co. Ltd, Yokogawa Electric Corporation, and Xenesys Inc, to succeed with this project. Work is being conducted to develop a 1MW facility on Kume Island requiring new pipelines. In July 2014, more than 50 members formed the Global Ocean reSource and Energy Association (GOSEA) an international organization formed to promote the development of the Kumejima Model and work towards the installation of larger deep seawater pipelines and a 1MW OTEC Facility. The companies involved in the current OTEC projects, along with other interested parties have developed plans for offshore OTEC systems as well. - For more details, see "Currently Operating OTEC Plants" above. + +=== United States Virgin Islands === +On March 5, 2014, Ocean Thermal Energy Corporation (OTEC) and the 30th Legislature of the United States Virgin Islands (USVI) signed a Memorandum of Understanding to move forward with a study to evaluate the feasibility and potential benefits to the USVI of installing on-shore Ocean Thermal Energy Conversion (OTEC) renewable energy power plants and Seawater Air Conditioning (SWAC) facilities. The benefits to be assessed in the USVI study include both the baseload (24/7) clean electricity generated by OTEC, as well as the various related products associated with OTEC and SWAC, including abundant fresh drinking water, energy-saving air conditioning, sustainable aquaculture and mariculture, and agricultural enhancement projects for the Islands of St Thomas and St Croix. +On July 18, 2016, OTE's application to be a Qualifying Facility was approved by the Virgin Islands Public Services Commission. OTE also received permission to begin negotiating contracts associated with this project. + +=== Kiribati === +South Korea's Research Institute of Ships and Ocean Engineering (KRISO) received approval in principle from Bureau Veritas for their 1MW offshore OTEC design. No timeline was given for the project which will be located 6 km offshore of the Republic of Kiribati. + +=== Martinique === +Akuo Energy and DCNS were awarded NER300 funding on July 8, 2014 for their NEMO (New Energy for Martinique and Overseas) project which is expected to be a 10.7MW-net offshore facility completed in 2020. The award to help with development totaled 72 million Euro. + +=== Maldives === +On February 16, 2018, Global OTEC Resources announced plans to build a 150 kW plant in the Maldives, designed bespoke for hotels and resorts. "All these resorts draw their power from diesel generators. Moreover, some individual resorts consume 7,000 litres of diesel a day to meet demands which equates to over 6,000 tonnes of CO2 annually," said Director Dan Grech. The EU awarded a grant and Global OTEC resources launched a crowdfunding campaign for the rest. + +== Related activities == +OTEC has uses other than power production. + +=== Desalination === +Desalinated water can be produced in open- or hybrid-cycle plants using surface condensers to turn evaporated seawater into potable water. System analysis indicates that a 2-megawatt plant could produce about 4,300 cubic metres (150,000 cu ft) of desalinated water each day. Another system patented by Richard Bailey creates condensate water by regulating deep ocean water flow through surface condensers correlating with fluctuating dew-point temperatures. This condensation system uses no incremental energy and has no moving parts. +On March 22, 2015, Saga University opened a Flash-type desalination demonstration facility on Kumejima. This satellite of their Institute of Ocean Energy uses post-OTEC deep seawater from the Okinawa OTEC Demonstration Facility and raw surface seawater to produce desalinated water. Air is extracted from the closed system with a vacuum pump. When raw sea water is pumped into the flash chamber it boils, allowing pure steam to rise and the salt and remaining seawater to be removed. The steam is returned to liquid in a heat exchanger with cold post-OTEC deep seawater. The desalinated water can be used in hydrogen production or drinking water (if minerals are added). +The NELHA plant established in 1993 produced an average of 7,000 gallons of freshwater per day. KOYO USA was established in 2002 to capitalize on this new economic opportunity. KOYO bottles the water produced by the NELHA plant in Hawaii. With the capacity to produce one million bottles of water every day, KOYO is now Hawaii's biggest exporter with $140 million in sales.[81] + +=== Air conditioning === + +The 41 °F (5 °C) cold seawater made available by an OTEC system creates an opportunity to provide large amounts of cooling to industries and homes near the plant. The water can be used in chilled-water coils to provide air conditioning for buildings. It is estimated that a pipe 1 foot (0.30 m) in diameter can deliver 4,700 gallons of water per minute. Water at 43 °F (6 °C) could provide more than enough air conditioning for a large building. Operating 8,000 hours per year in lieu of electrical conditioning selling for 5–10¢ per kilowatt-hour, it would save $200,000-$400,000 in energy bills annually. +The InterContinental Resort and Thalasso-Spa on the island of Bora Bora uses an SWAC system to air-condition its buildings. The system passes seawater through a heat exchanger where it cools freshwater in a closed loop system. This freshwater is then pumped to buildings and directly cools the air. +In 2010, Copenhagen Energy opened a district cooling plant in Copenhagen, Denmark. The plant delivers cold seawater to commercial and industrial buildings, and has reduced electricity consumption by 80 percent. Ocean Thermal Energy Corporation (OTE) has designed a 9800-ton SDC system for a vacation resort in The Bahamas. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-6.md b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-6.md new file mode 100644 index 000000000..532273d3b --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-6.md @@ -0,0 +1,30 @@ +--- +title: "Ocean thermal energy conversion" +chunk: 7/10 +source: "https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:54.854158+00:00" +instance: "kb-cron" +--- + +=== Chilled-soil agriculture === +OTEC technology supports chilled-soil agriculture. When cold seawater flows through underground pipes, it chills the surrounding soil. The temperature difference between roots in the cool soil and leaves in the warm air allows plants that evolved in temperate climates to be grown in the subtropics. Dr. John P. Craven, Dr. Jack Davidson and Richard Bailey patented this process and demonstrated it at a research facility at the Natural Energy Laboratory of Hawaii Authority (NELHA). The research facility demonstrated that more than 100 different crops can be grown using this system. Many normally could not survive in Hawaii or at Keahole Point. +Japan has also been researching agricultural uses of Deep Sea Water since 2000 at the Okinawa Deep Sea Water Research Institute on Kume Island. The Kume Island facilities use regular water cooled by Deep Sea Water in a heat exchanger run through pipes in the ground to cool soil. Their techniques have developed an important resource for the island community as they now produce spinach, a winter vegetable, commercially year round. An expansion of the deep seawater agriculture facility was completed by Kumejima Town next to the OTEC Demonstration Facility in 2014. The new facility is for researching the economic practicality of chilled-soil agriculture on a larger scale. + +=== Aquaculture === +Aquaculture is the best-known byproduct, because it reduces the financial and energy costs of pumping large volumes of water from the deep ocean. Deep ocean water contains high concentrations of essential nutrients that are depleted in surface waters due to biological consumption. This artificial upwelling mimics the natural upwellings that are responsible for fertilizing and supporting the world's largest marine ecosystems, and the largest densities of life on the planet. +Cold-water sea animals, such as salmon and lobster, thrive in this nutrient-rich, deep seawater. Microalgae such as Spirulina, a health food supplement, also can be cultivated. Deep-ocean water can be combined with surface water to deliver water at an optimal temperature. +Non-native species such as salmon, lobster, abalone, trout, oysters, and clams can be raised in pools supplied by OTEC-pumped water. This extends the variety of fresh seafood products available for nearby markets. Such low-cost refrigeration can be used to maintain the quality of harvested fish, which deteriorate quickly in warm tropical regions. In Kona, Hawaii, aquaculture companies working with NELHA generate about $40 million annually, a significant portion of Hawaii's GDP. + +=== Hydrogen production === +Hydrogen can be produced via electrolysis using OTEC electricity. Generated steam with electrolyte compounds added to improve efficiency is a relatively pure medium for hydrogen production. OTEC can be scaled to generate large quantities of hydrogen. The main challenge is cost relative to other energy sources and fuels. + +=== Mineral extraction === +The ocean contains 57 trace elements in salts and other forms and dissolved in solution. In the past, most economic analyses concluded that mining the ocean for trace elements would be unprofitable, in part because of the energy required to pump the water. Mining generally targets minerals that occur in high concentrations, and can be extracted easily, such as magnesium. With OTEC plants supplying water, the only cost is for extraction. +The Japanese investigated the possibility of extracting uranium and found developments in other technologies (especially materials sciences) were improving the prospects. + +=== Climate control === + +Ocean thermal gradient can be used to enhance rainfall and moderate the high ambient summer temperatures in tropics to benefit enormously the mankind and the flora and fauna. When sea surface temperatures are relatively high on an area, lower atmospheric pressure area is formed compared to atmospheric pressure prevailing on the nearby land mass inducing winds from the landmass towards the ocean. Oceanward winds are dry and warm which would not contribute to good rainfall on the landmass compared to landward moist winds. For adequate rainfall and comfortable summer ambient temperatures (below 35 °C) on the landmass, it is preferred to have landward moist winds from the ocean. Creating high pressure zones by artificial upwelling on sea area selectively can also be used to deflect / guide the normal monsoon global winds towards the landmass. Artificial upwelling of nutrient-rich deep ocean water to the surface also enhances fisheries growth in areas with tropical and temperate weather. It would also lead to enhanced carbon sequestration by the oceans from improved algae growth and mass gain by glaciers from the extra snow fall mitigating sea level rise or global warming process. Tropical cyclones also do not pass through the high pressure zones as they intensify by gaining energy from the warm surface waters of the sea. +The cold deep sea water (<10 °C) is pumped to the sea surface area to suppress the sea surface temperature (>26 °C) by artificial means using electricity produced by mega scale floating wind turbine plants on the deep sea. The lower sea water surface temperature would enhance the local ambient pressure so that atmospheric landward winds are created. For upwelling the cold sea water, a stationary hydraulically driven propeller (≈50 m diameter) is located on the deep sea floor at 500 to 1000 m depth with a flexible draft tube extending up to the sea surface. The draft tube is anchored to the sea bed at its bottom side and top side to floating pontoons at the sea surface. The flexible draft tube would not collapse as its inside pressure is more compared to outside pressure when the colder water is pumped to the sea surface. Middle east, north east Africa, Indian subcontinent and Australia can get relief from hot and dry weather in summer season, also prone to erratic rainfall, by pumping deep sea water to the sea surface from the Persian gulf, Red sea, Indian Ocean and Pacific Ocean respectively. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-7.md b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-7.md new file mode 100644 index 000000000..995ac1738 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-7.md @@ -0,0 +1,471 @@ +--- +title: "Ocean thermal energy conversion" +chunk: 8/10 +source: "https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:54.854158+00:00" +instance: "kb-cron" +--- + +== Thermodynamics == +A rigorous treatment of OTEC reveals that a 20 °C temperature difference will provide as much energy as a hydroelectric plant with 34 m head for the same volume of water flow. +The low temperature difference means that water volumes must be very large to extract useful amounts of heat. A 100MW power plant would be expected to pump on the order of 12 million gallons (44,400 tonnes) per minute. For comparison, pumps must move a mass of water greater than the weight of the battleship Bismarck, which weighed 41,700 tonnes, every minute. This makes pumping a substantial parasitic drain on energy production in OTEC systems, with one Lockheed design consuming 19.55 MW in pumping costs for every 49.8 MW net electricity generated. For OTEC schemes using heat exchangers, to handle this volume of water the exchangers need to be enormous compared to those used in conventional thermal power generation plants, making them one of the most critical components due to their impact on overall efficiency. A 100 MW OTEC power plant would require 200 exchangers each larger than a 20-foot shipping container making them the single most expensive component. + +=== Variation of ocean temperature with depth === + +The total insolation received by the oceans (covering 70% of the earth's surface, with clearness index of 0.5 and average energy retention of 15%) is: 5.45×1018 MJ/yr × 0.7 × 0.5 × 0.15 = 2.87×1017 MJ/yr +We can use Beer–Lambert–Bouguer's law to quantify the solar energy absorption by water, + + + + + − + + + + d + I + ( + y + ) + + + d + y + + + + = + μ + I + + + {\displaystyle -{\frac {dI(y)}{dy}}=\mu I} + + +where, y is the depth of water, I is intensity and μ is the absorption coefficient. +Solving the above differential equation, + + + + + I + ( + y + ) + = + + I + + 0 + + + exp + ⁡ + ( + − + μ + y + ) + + + + {\displaystyle I(y)=I_{0}\exp(-\mu y)\,} + + +The absorption coefficient μ may range from 0.05 m−1 for very clear fresh water to 0.5 m−1 for very salty water. +Since the intensity falls exponentially with depth y, heat absorption is concentrated at the top layers. Typically in the tropics, surface temperature values are in excess of 25 °C (77 °F), while at 1 kilometer (0.62 mi), the temperature is about 5–10 °C (41–50 °F). The warmer (and hence lighter) waters at the surface means there are no thermal convection currents. Due to the small temperature gradients, heat transfer by conduction is too low to equalize the temperatures. The ocean is thus both a practically infinite heat source and a practically infinite heat sink. +This temperature difference varies with latitude and season, with the maximum in tropical, subtropical and equatorial waters. Hence the tropics are generally the best OTEC locations. + +=== Open/Claude cycle === +In this scheme, warm surface water at around 27 °C (81 °F) enters an evaporator at pressure slightly below the saturation pressures causing it to vaporize. + + + + + + H + + 1 + + + = + + H + + f + + + + + + {\displaystyle H_{1}=H_{f}\,} + + +Where Hf is enthalpy of liquid water at the inlet temperature, T1. + +This temporarily superheated water undergoes volume boiling as opposed to pool boiling in conventional boilers where the heating surface is in contact. Thus the water partially flashes to steam with two-phase equilibrium prevailing. Suppose that the pressure inside the evaporator is maintained at the saturation pressure, T2. + + + + + + H + + 2 + + + = + + H + + 1 + + + = + + H + + f + + + + + + x + + 2 + + + + H + + f + g + + + + + + {\displaystyle H_{2}=H_{1}=H_{f}+x_{2}H_{fg}\,} + + +Here, x2 is the fraction of water by mass that vaporizes. The warm water mass flow rate per unit turbine mass flow rate is 1/x2. +The low pressure in the evaporator is maintained by a vacuum pump that also removes the dissolved non-condensable gases from the evaporator. The evaporator now contains a mixture of water and steam of very low vapor quality (steam content). The steam is separated from the water as saturated vapor. The remaining water is saturated and is discharged to the ocean in the open cycle. The steam is a low pressure/high specific volume working fluid. It expands in a special low pressure turbine. + + + + + + H + + 3 + + + = + + H + + g + + + + + + {\displaystyle H_{3}=H_{g}\,} + + +Here, Hg corresponds to T2. For an ideal isentropic (reversible adiabatic) turbine, + + + + + + s + + 5 + , + s + + + = + + s + + 3 + + + = + + s + + f + + + + + + x + + 5 + , + s + + + + s + + f + g + + + + + + {\displaystyle s_{5,s}=s_{3}=s_{f}+x_{5,s}s_{fg}\,} + + +The above equation corresponds to the temperature at the exhaust of the turbine, T5. x5,s is the mass fraction of vapor at state 5. +The enthalpy at T5 is, + + + + + + H + + 5 + , + s + + + = + + H + + f + + + + + + x + + 5 + , + s + + + + H + + f + g + + + + + + {\displaystyle H_{5,s}=H_{f}+x_{5,s}H_{fg}\,} + + +This enthalpy is lower. The adiabatic reversible turbine work = H3-H5,s . +Actual turbine work WT = (H3-H5,s) x polytropic efficiency + + + + + + H + + 5 + + + = + + H + + 3 + + + − + + + a + c + t + u + a + l + + + + w + o + r + k + + + + {\displaystyle H_{5}=H_{3}-\ \mathrm {actual} \ \mathrm {work} } + + +The condenser temperature and pressure are lower. Since the turbine exhaust is to be discharged back into the ocean, a direct contact condenser is used to mix the exhaust with cold water, which results in a near-saturated water. That water is now discharged back to the ocean. +H6=Hf, at T5. T7 is the temperature of the exhaust mixed with cold sea water, as the vapor content now is negligible, + + + + + + H + + 7 + + + ≈ + + H + + f + + + + + a + t + + + T + + 7 + + + + + + {\displaystyle H_{7}\approx H_{f}\,\ at\ T_{7}\,} + + +The temperature differences between stages include that between warm surface water and working steam, that between exhaust steam and cooling water, and that between cooling water reaching the condenser and deep water. These represent external irreversibilities that reduce the overall temperature difference. +The cold water flow rate per unit turbine mass flow rate, + + + + + + + + + + m + + c + + + = + + + + + H + + 5 + + + − + + + H + + 6 + + + + + + H + + 6 + + + − + + + H + + 7 + + + + + + + ˙ + + + + + + + {\displaystyle {\dot {m_{c}={\frac {H_{5}-\ H_{6}}{H_{6}-\ H_{7}}}}}\,} + + +Turbine mass flow rate, + + + + + + + + M + + T + + + ˙ + + + + = + + + + + t + u + r + b + i + n + e + + + + w + o + r + k + + + + r + e + q + u + i + r + e + d + + + + W + + T + + + + + + + {\displaystyle {\dot {M_{T}}}={\frac {\mathrm {turbine} \ \mathrm {work} \ \mathrm {required} }{W_{T}}}} + \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-8.md b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-8.md new file mode 100644 index 000000000..0724d6a62 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-8.md @@ -0,0 +1,334 @@ +--- +title: "Ocean thermal energy conversion" +chunk: 9/10 +source: "https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:54.854158+00:00" +instance: "kb-cron" +--- + +Warm water mass flow rate, + + + + + + + + M + + w + + + ˙ + + + + = + + + + + + M + + T + + + + + + + m + + w + + + ˙ + + + + + ˙ + + + + + + + {\displaystyle {\dot {M_{w}}}={\dot {M_{T}{\dot {m_{w}}}}}\,} + + +Cold water mass flow rate + + + + + + + + + + + + M + + c + + + ˙ + + + + = + + + + + + M + + T + + + + m + + C + + + + ˙ + + + + + ˙ + + + + + + + {\displaystyle {\dot {{\dot {M_{c}}}={\dot {M_{T}m_{C}}}}}\,} + + +=== Closed Anderson cycle === +As developed starting in the 1960s by J. Hilbert Anderson of Sea Solar Power, Inc., in this cycle, QH is the heat transferred in the evaporator from the warm sea water to the working fluid. The working fluid exits the evaporator as a gas near its dew point. +The high-pressure, high-temperature gas then is expanded in the turbine to yield turbine work, WT. The working fluid is slightly superheated at the turbine exit and the turbine typically has an efficiency of 90% based on reversible, adiabatic expansion. +From the turbine exit, the working fluid enters the condenser where it rejects heat, -QC, to the cold sea water. The condensate is then compressed to the highest pressure in the cycle, requiring condensate pump work, WC. Thus, the Anderson closed cycle is a Rankine-type cycle similar to the conventional power plant steam cycle except that in the Anderson cycle the working fluid is never superheated more than a few degrees Fahrenheit. Owing to viscosity effects, working fluid pressure drops in both the evaporator and the condenser. This pressure drop, which depends on the types of heat exchangers used, must be considered in final design calculations but is ignored here to simplify the analysis. Thus, the parasitic condensate pump work, WC, computed here will be lower than if the heat exchanger pressure drop was included. The major additional parasitic energy requirements in the OTEC plant are the cold water pump work, WCT, and the warm water pump work, WHT. Denoting all other parasitic energy requirements by WA, the net work from the OTEC plant, WNP is + + + + + + W + + N + P + + + = + + W + + T + + + − + + W + + C + + + − + + W + + C + T + + + − + + W + + H + T + + + − + + W + + A + + + + + + {\displaystyle W_{NP}=W_{T}-W_{C}-W_{CT}-W_{HT}-W_{A}\,} + + +The thermodynamic cycle undergone by the working fluid can be analyzed without detailed consideration of the parasitic energy requirements. From the first law of thermodynamics, the energy balance for the working fluid as the system is + + + + + + W + + N + + + = + + Q + + H + + + − + + Q + + C + + + + + + {\displaystyle W_{N}=Q_{H}-Q_{C}\,} + + +where WN = WT + WC is the net work for the thermodynamic cycle. For the idealized case in which there is no working fluid pressure drop in the heat exchangers, + + + + + + Q + + H + + + = + + ∫ + + H + + + + T + + H + + + d + s + + + + {\displaystyle Q_{H}=\int _{H}T_{H}ds\,} + + +and + + + + + + Q + + C + + + = + + ∫ + + C + + + + T + + C + + + d + s + + + + {\displaystyle Q_{C}=\int _{C}T_{C}ds\,} + + +so that the net thermodynamic cycle work becomes + + + + + + W + + N + + + = + + ∫ + + H + + + + T + + H + + + d + s + − + + ∫ + + C + + + + T + + C + + + d + s + + + + {\displaystyle W_{N}=\int _{H}T_{H}ds-\int _{C}T_{C}ds\,} + + +Subcooled liquid enters the evaporator. Due to the heat exchange with warm sea water, evaporation takes place and usually superheated vapor leaves the evaporator. This vapor drives the turbine and the 2-phase mixture enters the condenser. Usually, the subcooled liquid leaves the condenser and finally, this liquid is pumped to the evaporator completing a cycle. + +== Environmental impact == +Carbon dioxide dissolved in deep cold and high pressure layers is brought up to the surface and released as the water warms. +Mixing of deep ocean water with shallower water brings up nutrients and makes them available to shallow water life. This may be an advantage for aquaculture of commercially important species, but may also unbalance the ecological system around the power plant. +OTEC plants use very large flows of warm surface seawater and cold deep seawater to generate constant renewable power. The deep seawater is oxygen deficient and generally 20–40 times more nutrient rich (in nitrate and nitrite) than shallow seawater. When these plumes are mixed, they are slightly denser than the ambient seawater. Though no large scale physical environmental testing of OTEC has been done, computer models have been developed to simulate the effect of OTEC plants. + +=== Hydrodynamic modeling === +In 2010, a computer model was developed to simulate the physical oceanographic effects of one or several 100 megawatt OTEC plant(s). The model suggests that OTEC plants can be configured such that the plant can conduct continuous operations, with resulting temperature and nutrient variations that are within naturally occurring levels. Studies to date suggest that by discharging the OTEC flows downwards at a depth below 70 meters, the dilution is adequate and nutrient enrichment is small enough so that 100-megawatt OTEC plants could be operated in a sustainable manner on a continuous basis. + +=== Biological modeling === +The nutrients from an OTEC discharge could potentially cause increased biological activity if they accumulate in large quantities in the photic zone. In 2011 a biological component was added to the hydrodynamic computer model to simulate the biological response to plumes from 100 megawatt OTEC plants. In all cases modeled (discharge at 70 meters depth or more), no unnatural variations occurs in the upper 40 meters of the ocean's surface. The picoplankton response in the 110 - 70 meter depth layer is approximately a 10–25% increase, which is well within naturally occurring variability. The nanoplankton response is negligible. The enhanced productivity of diatoms (microplankton) is small. The subtle phytoplankton increase of the baseline OTEC plant suggests that higher-order biochemical effects will be very small. + +=== Studies === +A previous Final Environmental Impact Statement (EIS) for the United States' NOAA from 1981 is available, but needs to be brought up to current oceanographic and engineering standards. Studies have been done to propose the best environmental baseline monitoring practices, focusing on a set of ten chemical oceanographic parameters relevant to OTEC. Most recently, NOAA held an OTEC Workshop in 2010 and 2012 seeking to assess the physical, chemical, and biological impacts and risks, and identify information gaps or needs. +The Tethys database provides access to scientific literature and general information on the potential environmental effects of OTEC. + +== Technical difficulties == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-9.md b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-9.md new file mode 100644 index 000000000..18fe7e6b9 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_thermal_energy_conversion-9.md @@ -0,0 +1,54 @@ +--- +title: "Ocean thermal energy conversion" +chunk: 10/10 +source: "https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:54.854158+00:00" +instance: "kb-cron" +--- + +=== Dissolved gases === +The performance of direct contact heat exchangers operating at typical OTEC boundary conditions is important to the Claude cycle. Many early Claude cycle designs used a surface condenser since their performance was well understood. However, direct contact condensers offer significant disadvantages. As cold water rises in the intake pipe, the pressure decreases to the point where gas begins to evolve. If a significant amount of gas comes out of solution, placing a gas trap before the direct contact heat exchangers may be justified. Experiments simulating conditions in the warm water intake pipe indicated about 30% of the dissolved gas evolves in the top 8.5 meters (28 ft) of the tube. The trade-off between pre-deaeration of the seawater and expulsion of non-condensable gases from the condenser is dependent on the gas evolution dynamics, deaerator efficiency, head loss, vent compressor efficiency and parasitic power. Experimental results indicate vertical spout condensers perform some 30% better than falling jet types. + +=== Microbial fouling === +Because raw seawater must pass through the heat exchanger, care must be taken to maintain good thermal conductivity. Biofouling layers as thin as 25 to 50 micrometres (0.00098 to 0.00197 in) can degrade heat exchanger performance by as much as 50%. A 1977 study in which mock heat exchangers were exposed to seawater for ten weeks concluded that although the level of microbial fouling was low, the thermal conductivity of the system was significantly impaired. The apparent discrepancy between the level of fouling and the heat transfer impairment is the result of a thin layer of water trapped by the microbial growth on the surface of the heat exchanger. +Another study concluded that fouling degrades performance over time, and determined that although regular brushing was able to remove most of the microbial layer, over time a tougher layer formed that could not be removed through simple brushing. The study passed sponge rubber balls through the system. It concluded that although the ball treatment decreased the fouling rate it was not enough to completely halt growth and brushing was occasionally necessary to restore capacity. The microbes regrew more quickly later in the experiment (i.e. brushing became necessary more often) replicating the results of a previous study. The increased growth rate after subsequent cleanings appears to result from selection pressure on the microbial colony. +Continuous use of 1 hour per day and intermittent periods of free fouling and then chlorination periods (again 1 hour per day) were studied. Chlorination slowed but did not stop microbial growth; however chlorination levels of 0.1 mg per liter for 1 hour per day may prove effective for long term operation of a plant. The study concluded that although microbial fouling was an issue for the warm surface water heat exchanger, the cold water heat exchanger suffered little or no biofouling and only minimal inorganic fouling. +Besides water temperature, microbial fouling also depends on nutrient levels, with growth occurring faster in nutrient rich water. The fouling rate also depends on the material used to construct the heat exchanger. Aluminium tubing slows the growth of microbial life, although the oxide layer which forms on the inside of the pipes complicates cleaning and leads to larger efficiency losses. In contrast, titanium tubing allows biofouling to occur faster but cleaning is more effective than with aluminium. + +=== Sealing === +The evaporator, turbine, and condenser operate in partial vacuum ranging from 3% to 1% of atmospheric pressure. The system must be carefully sealed to prevent in-leakage of atmospheric air that can degrade or shut down operation. In closed-cycle OTEC, the specific volume of low-pressure steam is very large compared to that of the pressurized working fluid. Components must have large flow areas to ensure steam velocities do not attain excessively high values. + +=== Parasitic power consumption by exhaust compressor === +An approach for reducing the exhaust compressor parasitic power loss is as follows. After most of the steam has been condensed by spout condensers, the non-condensible gas steam mixture is passed through a counter current region which increases the gas-steam reaction by a factor of five. The result is an 80% reduction in the exhaust pumping power requirements. + +== Cold air/warm water conversion == + +In winter in coastal Arctic locations, the temperature difference between the seawater and ambient air can be as high as 40 °C (72 °F). Closed-cycle systems could exploit the air-water temperature difference. Eliminating seawater extraction pipes might make a system based on this concept less expensive than OTEC. This technology is due to H. Barjot, who suggested butane as cryogen, because of its boiling point of −0.5 °C (31.1 °F) and its non-solubility in water. Assuming a realistic level of efficiency of 4%, calculations show that the amount of energy generated with one cubic meter water at a temperature of 2 °C (36 °F) in a place with an air temperature of −22 °C (−8 °F) equals the amount of energy generated by letting this cubic meter water run through a hydroelectric plant of 4000 feet (1,200 m) height. +Barjot Polar Power Plants could be located on islands in the polar region or designed as swimming barges or platforms attached to the ice cap. The weather station Myggbuka at Greenlands east coast for example, which is only 2,100 km away from Glasgow, detects monthly mean temperatures below −15 °C (5 °F) during 6 winter months in the year. + +== Application of the thermoelectric effect == +In 1979 SERI proposed using the Seebeck effect to produce power with a total conversion efficiency of 2%. +In 2014 Liping Liu, Associate Professor at Rutgers University, envisioned an OTEC system that utilises the solid state thermoelectric effect rather than the fluid cycles traditionally used. + +== See also == + +Deep water source cooling +Geothermal power +Heat engine +Floating wind turbine +Ocean engineering +Seawater air conditioning +Thermogalvanic cell +Marine energy +Tidal power +Wave power +Osmotic power + +== References == + +== Sources == +William H. Avery; Chih Wu (17 March 1994). Renewable Energy From the Ocean: A Guide to OTEC. Johns Hopkins University Applied Physics Laboratories Series in Science and Engineering. Oxford, New York: Oxford University Press. ISBN 978-0-19-507199-3. + +== External links == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Ocean_zoning-0.md b/data/en.wikipedia.org/wiki/Ocean_zoning-0.md new file mode 100644 index 000000000..4c69519f4 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ocean_zoning-0.md @@ -0,0 +1,21 @@ +--- +title: "Ocean zoning" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Ocean_zoning" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:56.233356+00:00" +instance: "kb-cron" +--- + +Ocean zoning is a policy approach for environmental resource management in oceanic environments. This, often big picture, approach to ocean management allocates areas for various ocean uses. Types of zones can include areas designated for marine protected areas (including marine reserves), aquaculture, various types of fishing, shipping, recreation (including scuba diving), mooring/anchoring, and energy production (including offshore wind power). The process of marine spatial planning can result in ocean zones being legally established. +Benefits of ocean zoning can include reducing conflict between users, safeguarding ecologically important areas, enabling commercial activity to develop with certainty, and supporting international cooperation. Balancing environmental, economic, security, social, and cultural interests in delineation of zone boundaries remains a key challenge of ocean zoning. + + +== References == + + +== External links == + +Open Channels - Forum for Ocean Planning and Management +SeaSketch - Software tools to support collaborative ocean planning \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Oceanic_basin-0.md b/data/en.wikipedia.org/wiki/Oceanic_basin-0.md new file mode 100644 index 000000000..ca6853698 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Oceanic_basin-0.md @@ -0,0 +1,29 @@ +--- +title: "Oceanic basin" +chunk: 1/2 +source: "https://en.wikipedia.org/wiki/Oceanic_basin" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:57.426803+00:00" +instance: "kb-cron" +--- + +In hydrology, an oceanic basin (or ocean basin) is anywhere on Earth that is covered by seawater. Geologically, most of the ocean basins are large geologic basins that are below sea level. +Most commonly the ocean is divided into basins following the continents distribution: the North and South Atlantic (together approximately 75 million km2/ 29 million mi2), North and South Pacific (together approximately 155 million km2/ 59 million mi2), Indian Ocean (68 million km2/ 26 million mi2) and Arctic Ocean (14 million km2/ 5.4 million mi2). Also recognized is the Southern Ocean (20 million km2/ 7 million mi2). All ocean basins collectively cover 67% of the Earth's surface, and together they contain almost 97% of all water on the planet. They have an average depth of almost 4 km (about 2.5 miles). + +== Definitions of boundaries == + +=== Boundaries based on continents === +"Limits of Oceans and Seas", published by the International Hydrographic Office in 1953, is a document that defined the ocean's basins as they are largely known today. The main ocean basins are the ones named in the previous section. These main basins are divided into smaller parts. Some examples are: the Baltic Sea (with three subdivisions), the North Sea, the Greenland Sea, the Norwegian Sea, the Laptev Sea, the Gulf of Mexico, the South China Sea, and many more. The limits were set for convenience of compiling sailing directions but had no geographical or physical ground and to this day have no political significance. For instance, the line between the North and South Atlantic is set at the equator. The Antarctic or Southern Ocean, which reaches from 60° south to Antarctica had been omitted until 2000, but is now also recognized by the International Hydrographic Office. Nevertheless, and since ocean basins are interconnected, many oceanographers prefer to refer to one single ocean basin instead of multiple ones. +Older references (e.g., Littlehales 1930) consider the oceanic basins to be the complement to the continents, with erosion dominating the latter, and the sediments so derived ending up in the ocean basins. This vision is supported by the fact that oceans lie lower than continents, so the former serve as sedimentary basins that collect sediment eroded from the continents, known as clastic sediments, as well as precipitation sediments. Ocean basins also serve as repositories for the skeletons of carbonate- and silica-secreting organisms such as coral reefs, diatoms, radiolarians, and foraminifera. More modern sources (e.g., Floyd 1991) regard the ocean basins more as basaltic plains, than as sedimentary depositories, since most sedimentation occurs on the continental shelves and not in the geologically defined ocean basins. + +=== Definition based on surface connectivity === +The flow in the ocean is not uniform but varies with depth. Vertical circulation in the ocean is very slow compared to horizontal flow and observing the deep ocean is difficult. Defining the ocean basins based on connectivity of the entire ocean (depth and width) is therefore not possible. Froyland et al. (2014) defined ocean basins based on surface connectivity. This is achieved by creating a Markov Chain model of the surface ocean dynamics using short term time trajectory data from a global ocean model. These trajectories are of particles that move only on the surface of the ocean. The model outcome gives the probability of a particle at a certain grid point to end up somewhere else on the ocean's surface. With the model outcome a matrix can be created from which the Eigenvectors and Eigenvalues are taken. These Eigenvectors show regions of attraction, aka regions where things on the surface of the ocean (plastic, biomass, water etc.) become trapped. One of these regions is for example the Atlantic garbage patch. With this approach the five main ocean basins are still the North and South Atlantic, North and South Pacific and the Arctic Ocean, but with different boundaries between the basins. These boundaries show the lines of very little surface connectivity between the different regions which means that a particle on the ocean surface in a certain region is more likely to stay in the same region than to pass over to a different one. + +== Formation of oceanic crusts and basins == + +=== Earth's structure === +Depending on the chemical composition and the physical state, the Earth can be divided into three major components: the mantle, the core, and the crust. The crust is referred to as the outside layer of the Earth. It is made of solid rock, mostly basalt and granite. The crust that lies below sea level is known as the oceanic crust, while on land it is known as the continental crust. The former is thinner and is composed of relatively dense basalt, while the latter is less dense and mainly composed of granite. The lithosphere is composed of the crust (oceanic and continental) and the uppermost part of the mantle. The lithosphere is broken into sections called plates. + +=== Processes of tectonic plates === +Tectonic plates move very slowly (5 to 10 cm (2 to 4 inches) per year) relative to each other and interact along their boundaries. This movement is responsible for most of the Earth's seismic and volcanic activity. Depending on how the plates interact with each other, there are three types of boundaries. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Oceanic_basin-1.md b/data/en.wikipedia.org/wiki/Oceanic_basin-1.md new file mode 100644 index 000000000..1a6dbdb7d --- /dev/null +++ b/data/en.wikipedia.org/wiki/Oceanic_basin-1.md @@ -0,0 +1,48 @@ +--- +title: "Oceanic basin" +chunk: 2/2 +source: "https://en.wikipedia.org/wiki/Oceanic_basin" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:57.426803+00:00" +instance: "kb-cron" +--- + +Convergent boundary: the plates collide, and eventually the denser one slides underneath the lighter one, a process known as subduction. This type of interaction can take place between an oceanic and an oceanic crust, creating a so-called oceanic trench. It can also take place between an oceanic and a continental crust, forming a mountain range in the continent like the Andes, and it can take place between a continental and continental crust, resulting in large mountain chains, like the Himalayas. +Divergent boundary: the plates move apart from each other. If this occurs on land a rift is formed, which eventually becomes a rift valley. The most active divergent boundaries lie under the sea. In the ocean, if magma or molten rock ascent from the mantle and fill the gap created by two diverging plates, a mid-ocean ridge is formed. +Transform boundary: also called transform fault, occurs when the movement between the plates is horizontal, so no crust is created or destroyed. It can happen both, on land and in the sea, but most of the faults are in the oceanic crust. + +=== Size of trenches === +The Earth's deepest trench is the Mariana Trench which extends for about 2500 km (1600 miles) across the seabed. It is near the Mariana Islands, a volcanic archipelago in the West Pacific. Its deepest point is 10994 m (nearly 7 miles) below the surface of the sea. +The Earth's longest trench runs alongside the coast of Peru and Chile, reaching a depth of 8065 m (26460 feet) and extending for approximately 5900 km (3700 miles). It occurs where the oceanic Nazca plate slides under the continental South American plate and is associated with the upthrust and volcanic activity of the Andes. + +== History and age of oceanic crust == +The oldest oceanic crust is in the far western equatorial Pacific, east of the Mariana Islands. It is located far away from oceanic spreading centers, where oceanic crust is constantly created or destroyed. The oldest crust is estimated to be only around 200 million years old, compared to the age of Earth which is 4.6 billion years. + +200 million years ago nearly all land mass was one large continent called Pangea, which started to split up. During the splitting process of Pangea, some ocean basins shrunk, such as the Pacific, while others were created, such as the Atlantic and Arctic basins. The Atlantic Basin began to form around 180 million years ago, when the continent Laurasia (North America and Eurasia) started to drift away from Africa and South America. The Pacific plate grew, and subduction led to a shrinking of its bordering plates. The Pacific plate continues to move northward. Around 130 million years ago the South Atlantic started to form, as South America and Africa started to separate. At around this time India and Madagascar rifted northwards, away from Australia and Antarctica, creating seafloor around Western Australia and East Antarctica. When Madagascar and India separated between 90 and 80 million years ago, the spreading ridges in the Indian Ocean were reorganized. The northernmost part of the Atlantic Ocean was also formed at this time when Europe and Greenland separated. About 60 million years ago a new rift and oceanic ridge formed between Greenland and Europe, separating them and initiating the formation of oceanic crust in the Norwegian Sea and the Eurasian Basin in the eastern Arctic Ocean. + +== Changes in ocean basins == + +=== State of the current ocean basins === +The area occupied by the individual ocean basins has fluctuated in the past due to, amongst other, tectonic plate movements. Therefore, an oceanic basin can be actively changing size and/or depth or can be relatively inactive. The elements of an active and growing oceanic basin include an elevated mid-ocean ridge, flanking abyssal hills leading down to abyssal plains and an oceanic trench. +Changes in biodiversity, floodings and other climate variations are linked to sea-level, and are reconstructed with different models and observations (e.g., age of oceanic crust). Sea level is affected not only by the volume of the ocean basin, but also by the volume of water in them. Factors that influence the volume of the ocean basins are: + +Plate tectonics and the volume of mid-ocean ridges: the depth of the seafloor increases with distance to a ridge, as the oceanic lithosphere cools and thickens. The volume of ocean basins can be modeled using reconstructions of plate tectonics and using an age-depth relationship (see also Seafloor depth vs age). +Marine sedimentations: these influence global mean depth and volume of the ocean, but they are difficult to determine and reconstruct. +Passive margins and crustal extensions: to compensate the extension of continents due to continental rifting, oceanic crust decreases and therefore so does the volume of the ocean basin. However, the increase in continental area leads to a stretching and thinning of the continental crust, much of which ends up below sea level, thus again leading to an increase in ocean basin volume. +The Atlantic Ocean and the Arctic Ocean are good examples of active, growing oceanic basins, whereas the Mediterranean Sea is shrinking. The Pacific Ocean is also an active, shrinking oceanic basin, even though it has both spreading ridge and oceanic trenches. Perhaps the best example of an inactive oceanic basin is the Gulf of Mexico, which formed in Jurassic times and has been doing nothing but collecting sediments since then. The Aleutian Basin is another example of a relatively inactive oceanic basin. The Japan Basin in the Sea of Japan which formed in the Miocene, is still tectonically active although recent changes have been relatively mild. + +== See also == + +List of abyssal plains and oceanic basins +List of oceanic landforms +Trough (geology) +Solid Earth + +== Notes == + +== Further reading == +Wright, John; et al. (January 26, 1998). The Ocean Basins: Their Structure and Evolution (Second ed.). Oxford, England: Open University, Butterworth-Heinemann. ISBN 978-0-08-053793-1. + +== External links == +Global Solid Earth Topography \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Oceanic_crust-0.md b/data/en.wikipedia.org/wiki/Oceanic_crust-0.md new file mode 100644 index 000000000..96af3ae10 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Oceanic_crust-0.md @@ -0,0 +1,25 @@ +--- +title: "Oceanic crust" +chunk: 1/2 +source: "https://en.wikipedia.org/wiki/Oceanic_crust" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:58.651013+00:00" +instance: "kb-cron" +--- + +Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic cumulates. The crust lies above the rigid uppermost layer of the mantle. The crust and the rigid upper mantle layer together constitute oceanic lithosphere. +Oceanic crust is primarily composed of mafic rocks, or sima, which is rich in iron and magnesium. It is thinner than continental crust, or sial, generally less than 10 kilometers thick; however, it is denser, having a mean density of about 3.0 grams per cubic centimeter as opposed to continental crust which has a density of about 2.7 grams per cubic centimeter. +The uppermost crust is the result of the cooling of magma derived from mantle material below the plate. The magma is injected into the spreading center, which consists mainly of a partly solidified crystal mush derived from earlier injections, forming magma lenses that are the source of the sheeted dikes that feed the overlying pillow lavas. As the lavas cool they are, in most instances, modified chemically by seawater. These eruptions occur mostly at mid-ocean ridges, but also at scattered hotspots, and also in rare but powerful occurrences known as flood basalt eruptions. But most magma crystallises at depth, within the lower oceanic crust. There, newly intruded magma can mix and react with pre-existing crystal mush and rocks. + +== Composition == + +Although a complete section of oceanic crust has not yet been drilled, geologists have several pieces of evidence that help them understand the ocean floor. Estimations of composition are based on analyses of ophiolites (sections of oceanic crust that are thrust onto and preserved on the continents), comparisons of the seismic structure of the oceanic crust with laboratory determinations of seismic velocities in known rock types, and samples recovered from the ocean floor by submersibles, dredging (especially from ridge crests and fracture zones) and drilling. Oceanic crust is significantly simpler than continental crust and generally can be divided in three layers. According to mineral physics experiments, at lower mantle pressures, oceanic crust becomes denser than the surrounding mantle. + +Layer 1 is on an average 0.4 km thick. It consists of unconsolidated or semiconsolidated sediments, usually thin or even not present near the mid-ocean ridges but thicker farther away from the ridge. Near the continental margins sediment is terrigenous, meaning derived from the land, unlike deep sea sediments which are made of tiny shells of marine organisms, usually calcareous and siliceous, or it can be made of volcanic ash and terrigenous sediments transported by turbidity currents. +Layer 2 could be divided into two parts: Layer 2A is a 0.5 km thick uppermost volcanic layer of glassy to finely crystalline basalt, usually in the form of pillow basalt. Layer 2B is a 1.5 km thick layer composed of diabase dikes. +Layer 3 is formed by slow cooling of magma beneath the surface and consists of coarse grained gabbro and cumulate ultramafic rocks. It constitutes over two-thirds of oceanic crust volume with almost 5 km thickness. + +=== Geochemistry === +The most voluminous volcanic rocks of the ocean floor are the mid-oceanic ridge basalts, which are derived from low-potassium tholeiitic magmas. These rocks have low concentrations of large ion lithophile elements (LILE), light rare earth elements (LREE), volatile elements and other highly incompatible elements. There can be found basalts enriched with incompatible elements, but they are rare and associated with mid-ocean ridge hot spots such as surroundings of Galapagos Islands, the Azores and Iceland. +Prior to the Neoproterozoic Era 1000 million years ago, the world's oceanic crust was more mafic than the current crust. The more mafic nature of the crust meant that higher amounts of water molecules (OH) could be stored in the altered parts of the crust. At subduction zones this mafic crust was prone to metamorphose into greenschist instead of blueschist at ordinary blueschist facies. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Oceanic_crust-1.md b/data/en.wikipedia.org/wiki/Oceanic_crust-1.md new file mode 100644 index 000000000..61c964dde --- /dev/null +++ b/data/en.wikipedia.org/wiki/Oceanic_crust-1.md @@ -0,0 +1,35 @@ +--- +title: "Oceanic crust" +chunk: 2/2 +source: "https://en.wikipedia.org/wiki/Oceanic_crust" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:58.651013+00:00" +instance: "kb-cron" +--- + +=== Life cycle === +Oceanic crust is continuously being created at mid-ocean ridges. As continental plates diverge at these ridges, magma rises into the upper mantle and crust. As the continental plates move away from the ridge, the newly formed rocks cool and start to erode with sediment gradually building up on top of them. The youngest oceanic rocks are at the oceanic ridges, and they get progressively older away from the ridges. +As the mantle rises it cools and melts, as the pressure decreases and it crosses the solidus. The amount of melt produced depends only on the temperature of the mantle as it rises. Hence most oceanic crust is the same thickness (7±1 km). Very slow spreading ridges (<1 cm·yr−1 half-rate) produce thinner crust (4–5 km thick) as the mantle has a chance to cool on upwelling and so it crosses the solidus and melts at lesser depth, thereby producing less melt and thinner crust. An example of this is the Gakkel Ridge under the Arctic Ocean. Thicker than average crust is found above plumes as the mantle is hotter and hence it crosses the solidus and melts at a greater depth, creating more melt and a thicker crust. An example of this is Iceland which has crust of thickness ~20 km. +The age of the oceanic crust can be used to estimate the (thermal) thickness of the lithosphere, where young oceanic crust has not had enough time to cool the mantle beneath it, while older oceanic crust has thicker mantle lithosphere beneath it. The oceanic lithosphere subducts at what are known as convergent boundaries. These boundaries can exist between oceanic lithosphere on one plate and oceanic lithosphere on another, or between oceanic lithosphere on one plate and continental lithosphere on another. In the second situation, the oceanic lithosphere always subducts because the continental lithosphere is less dense. The subduction process consumes older oceanic lithosphere, so oceanic crust is seldom more than 200 million years old. +The process of super-continent formation and destruction via repeated cycles of creation and destruction of oceanic crust is known as the Wilson Cycle. +The oldest large-scale oceanic crust is in the west Pacific and north-west Atlantic — both are about up to 180-200 million years old. However, parts of the eastern Mediterranean Sea could be remnants of the much older Tethys Ocean, at about 270 and up to 340 million years old. + +== Magnetic anomalies == + +The oceanic crust displays a pattern of magnetic lines, parallel to the ocean ridges, frozen in the basalt. A symmetrical pattern of positive and negative magnetic lines emanates from the mid-ocean ridge. New rock is formed by magma at the mid-ocean ridges, and the ocean floor spreads out from this point. When the magma cools to form rock, its magnetic polarity is aligned with the then-current positions of the magnetic poles of the Earth. New magma then forces the older cooled magma away from the ridge. This process results in parallel sections of oceanic crust of alternating magnetic polarity. + +== See also == + +Continental crust +Lithosphere +Mohorovičić discontinuity +Plate tectonics +Seabed 2030 +Seafloor depth versus age + +== Notes == + +== References == +Marshak, Stephen (2005). Earth: Portrait of a Planet. pp. 41–42. +McDuff, Russell E.; Heath, G. Ross. "Ocean 540: Oceanic Lithosphere; Plate Tectonics; Seafloor Topography". School of Oceanography, University of Washington. Archived from the original on 2 March 2009. Retrieved 9 August 2009. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Oceanic_plateau-0.md b/data/en.wikipedia.org/wiki/Oceanic_plateau-0.md new file mode 100644 index 000000000..3651db710 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Oceanic_plateau-0.md @@ -0,0 +1,76 @@ +--- +title: "Oceanic plateau" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Oceanic_plateau" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:35:59.916062+00:00" +instance: "kb-cron" +--- + +An oceanic or submarine plateau is a large, relatively flat elevation that is higher than the surrounding relief with one or more relatively steep sides. +There are 184 oceanic plateaus in the world, covering an area of 18,486,600 km2 (7,137,700 sq mi) or about 5.11% of the oceans. The South Pacific region around Australia and New Zealand contains the greatest number of oceanic plateaus (see map). +Oceanic plateaus produced by large igneous provinces are often associated with hotspots, mantle plumes, and volcanic islands — such as Iceland, Hawaii, Cape Verde, and Kerguelen. The three largest plateaus, the Caribbean, Ontong Java, and Mid-Pacific Mountains, are located on thermal swells. Other oceanic plateaus, however, are made of rifted continental crust, for example the Falkland Plateau, Lord Howe Rise, and parts of Kerguelen, Seychelles, and Arctic ridges. +Plateaus formed by large igneous provinces were formed by the equivalent of continental flood basalts such as the Deccan Traps in India and the Snake River Plain in the United States. +In contrast to continental flood basalts, most igneous oceanic plateaus erupt through young and thin (6–7 km (3.7–4.3 mi)) mafic or ultra-mafic crust and are therefore uncontaminated by felsic crust and representative for their mantle sources. +These plateaus often rise 2–3 km (1.2–1.9 mi) above the surrounding ocean floor and are more buoyant than oceanic crust. They therefore tend to withstand subduction, more-so when thick and when reaching subduction zones shortly after their formations. As a consequence, they tend to "dock" to continental margins and be preserved as accreted terranes. Such terranes are often better preserved than the exposed parts of continental flood basalts and are therefore a better record of large-scale volcanic eruptions throughout Earth's history. This "docking" also means that oceanic plateaus are important contributors to the growth of continental crust. Their formations often had a dramatic impact on global climate, such as the most recent plateaus formed, the three, large, Cretaceous oceanic plateaus in the Pacific and Indian Ocean: Ontong Java, Kerguelen, and Caribbean. + + +== Role in crust–mantle recycling == +Geologists believe that igneous oceanic plateaus may well represent a stage in the development of continental crust as they are generally less dense than oceanic crust while still being denser than normal continental crust. +Density differences in crustal material largely arise from different ratios of various elements, especially silicon. Continental crust has the highest amount of silicon (such rock is called felsic). Oceanic crust has a smaller amount of silicon (mafic rock). Igneous oceanic plateaus have a ratio intermediate between continental and oceanic crust, although they are more mafic than felsic. +However, when a plate carrying oceanic crust subducts under a plate carrying an igneous oceanic plateau, the volcanism which erupts on the plateau as the oceanic crust heats up on its descent into the mantle erupts material which is more felsic than the material which makes up the plateau. This represents a step toward creating crust which is increasingly continental in character, being less dense and more buoyant. If an igneous oceanic plateau is subducted underneath another one, or under existing continental crust, the eruptions produced thereby produce material that is yet more felsic, and so on through geologic time. + + +== List of oceanic plateaus == + + +=== Continental oceanic plateaus === +Campbell Plateau (South Pacific) +Challenger Plateau (South Pacific) +Exmouth Plateau (Indian) +Falkland Plateau (South Atlantic) +Lord Howe Rise (South Pacific) +Rockall Plateau (North Atlantic) + + +=== Igneous oceanic plateaus === +Agulhas Plateau (Southwest Indian) +Azores Plateau (North Atlantic) +Broken Plateau (Indian) +Caribbean-Colombian Plateau (Caribbean) +Exmouth Plateau (Indian) +Hikurangi Plateau (Southwest Pacific) +Iceland Plateau (North Atlantic) +Kerguelen Plateau (Indian) +Magellan Rise (Pacific) +Manihiki Plateau (Southwest Pacific) +Mascarene Plateau (Indian) +Naturaliste Plateau (Indian) +Ontong Java Plateau (Southwest Pacific) +Shatsky Rise (North Pacific) +Vøring Plateau (North Atlantic) +Wrangellia Terrane (Northeast Pacific) +Yermak Plateau (Arctic) + + +== See also == + +Abyssal plain +Bathymetry +Glossary of landforms +Ocean bank + + +== References == + + +=== Notes === + + +=== Sources === + + +== External links == +Gsa.confex.com: "Oceanic Plateaus: Nuclei for Archean Cratons" Archived 2012-02-06 at the Wayback Machine +Tristan.ferroir.free.fr: "On the oceanic plateaux"—(in French) \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Oceanic_trench-0.md b/data/en.wikipedia.org/wiki/Oceanic_trench-0.md new file mode 100644 index 000000000..f18b53188 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Oceanic_trench-0.md @@ -0,0 +1,28 @@ +--- +title: "Oceanic trench" +chunk: 1/6 +source: "https://en.wikipedia.org/wiki/Oceanic_trench" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:01.226469+00:00" +instance: "kb-cron" +--- + +Oceanic trenches are prominent, long, narrow topographic depressions of the ocean floor. They are typically 50 to 100 kilometers (30 to 60 mi) wide and 3 to 4 km (1.9 to 2.5 mi) below the level of the surrounding oceanic floor, but can be thousands of kilometers in length. There are about 50,000 km (31,000 mi) of oceanic trenches worldwide, mostly around the Pacific Ocean, but also in the eastern Indian Ocean and a few other locations. The greatest ocean depth measured is in the Challenger Deep of the Mariana Trench, at a depth of 10,994 m (36,070 ft) below sea level. +Oceanic trenches are a feature of the Earth's distinctive plate tectonics. They mark the locations of convergent plate boundaries, along which lithospheric plates move towards each other at rates that vary from a few millimeters to over ten centimeters per year. Oceanic lithosphere moves into trenches at a global rate of about 3 km2 (1.2 sq mi) per year. A trench marks the position at which the flexed, subducting slab begins to descend beneath another lithospheric slab. Trenches are generally parallel to and about 200 km (120 mi) from a volcanic arc. +Much of the fluid trapped in sediments of the subducting slab returns to the surface at the oceanic trench, producing mud volcanoes and cold seeps. These support unique biomes based on chemotrophic microorganisms. There is concern that plastic debris is accumulating in trenches and threatening these communities. + +== Geographic distribution == + +There are approximately 50,000 km (31,000 mi) of convergent plate margins worldwide. These are mostly located around the Pacific Ocean, but are also found in the eastern Indian Ocean, with a few shorter convergent margin segments in other parts of the Indian Ocean, in the Atlantic Ocean, and in the Mediterranean. They are found on the oceanward side of island arcs and Andean-type orogens. Globally, there are over 50 major ocean trenches covering an area of 1.9 million km2 or about 0.5% of the oceans. +Trenches are geomorphologically distinct from troughs. Troughs are elongated depressions of the sea floor with steep sides and flat bottoms, while trenches are characterized by a V-shaped profile. Trenches that are partially infilled are sometimes described as troughs, for example the Makran Trough. Some trenches are completely buried and lack bathymetric expression as in the Cascadia subduction zone, which is completely filled with sediments. Despite their appearance, in these instances the fundamental plate-tectonic structure is still an oceanic trench. Some troughs look similar to oceanic trenches but possess other tectonic structures. One example is the Lesser Antilles Trough, which is the forearc basin of the Lesser Antilles subduction zone. Also not a trench is the New Caledonia trough, which is an extensional sedimentary basin related to the Tonga-Kermadec subduction zone. Additionally, the Cayman Trough, which is a pull-apart basin within a transform fault zone, is not an oceanic trench. +Trenches, along with volcanic arcs and Wadati–Benioff zones (zones of earthquakes under a volcanic arc) are diagnostic of convergent plate boundaries and their deeper manifestations, subduction zones. Here, two tectonic plates are drifting into each other at a rate of a few millimeters to over 10 centimeters (4 in) per year. At least one of the plates is oceanic lithosphere, which plunges under the other plate to be recycled in the Earth's mantle. +Trenches are related to, but distinct from, continental collision zones, such as the Himalayas. Unlike in trenches, in continental collision zones continental crust enters a subduction zone. When buoyant continental crust enters a trench, subduction comes to a halt and the area becomes a zone of continental collision. Features analogous to trenches are associated with collision zones. One such feature is the peripheral foreland basin, a sediment-filled foredeep. Examples of peripheral foreland basins include the floodplains of the Ganges River and the Tigris-Euphrates river system. + +== History of the term "trench" == +Trenches were not clearly defined until the late 1940s and 1950s. The bathymetry of the ocean was poorly known prior to the Challenger expedition of 1872–1876, which took 492 soundings of the deep ocean. At station No. 225, the expedition discovered Challenger Deep, now known to be the southern end of the Mariana Trench. The laying of transatlantic telegraph cables on the seafloor between the continents during the late 19th and early 20th centuries provided further motivation for improved bathymetry. The term trench, in its modern sense of a prominent elongated depression of the sea bottom, was first used by Johnstone in his 1923 textbook An Introduction to Oceanography. +During the 1920s and 1930s, Felix Andries Vening Meinesz measured gravity over trenches using a newly developed gravimeter that could measure gravity from aboard a submarine. He proposed the tectogene hypothesis to explain the belts of negative gravity anomalies that were found near island arcs. According to this hypothesis, the belts were zones of downwelling of light crustal rock arising from subcrustal convection currents. The tectogene hypothesis was further developed by Griggs in 1939, using an analogue model based on a pair of rotating drums. Harry Hammond Hess substantially revised the theory based on his geological analysis. +World War II in the Pacific led to great improvements of bathymetry, particularly in the western Pacific. In light of these new measurements, the linear nature of the deeps became clear. There was a rapid growth of deep sea research efforts, especially the widespread use of echosounders in the 1950s and 1960s. These efforts confirmed the morphological utility of the term "trench." Important trenches were identified, sampled, and mapped via sonar. +The early phase of trench exploration reached its peak with the 1960 descent of the Bathyscaphe Trieste to the bottom of the Challenger Deep. Following Robert S. Dietz' and Harry Hess' promulgation of the seafloor spreading hypothesis in the early 1960s and the plate tectonic revolution in the late 1960s, the oceanic trench became an important concept in plate tectonic theory. + +== Morphology == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Oceanic_trench-1.md b/data/en.wikipedia.org/wiki/Oceanic_trench-1.md new file mode 100644 index 000000000..5bd675406 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Oceanic_trench-1.md @@ -0,0 +1,19 @@ +--- +title: "Oceanic trench" +chunk: 2/6 +source: "https://en.wikipedia.org/wiki/Oceanic_trench" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:01.226469+00:00" +instance: "kb-cron" +--- + +Oceanic trenches are 50 to 100 kilometers (30 to 60 mi) wide and have an asymmetric V-shape, with the steeper slope (8 to 20 degrees) on the inner (overriding) side of the trench and the gentler slope (around 5 degrees) on the outer (subducting) side of the trench. The bottom of the trench marks the boundary between the subducting and overriding plates, known as the basal plate boundary shear or the subduction décollement. The depth of the trench depends on the starting depth of the oceanic lithosphere as it begins its plunge into the trench, the angle at which the slab plunges, and the amount of sedimentation in the trench. Both starting depth and subduction angle are greater for older oceanic lithosphere, which is reflected in the deep trenches of the western Pacific. Here the bottoms of the Marianas and the Tonga–Kermadec trenches are up to 10–11 kilometers (6.2–6.8 mi) below sea level. In the eastern Pacific, where the subducting oceanic lithosphere is much younger, the depth of the Peru-Chile trench is around 7 to 8 kilometers (4.3 to 5.0 mi). +Though narrow, oceanic trenches are remarkably long and continuous, forming the largest linear depressions on earth. An individual trench can be thousands of kilometers long. Most trenches are convex towards the subducting slab, which is attributed to the spherical geometry of the Earth. +The trench asymmetry reflects the different physical mechanisms that determine the inner and outer slope angle. The outer slope angle of the trench is determined by the bending radius of the subducting slab, as determined by its elastic thickness. Since oceanic lithosphere thickens with age, the outer slope angle is ultimately determined by the age of the subducting slab. The inner slope angle is determined by the angle of repose of the overriding plate edge. This reflects frequent earthquakes along the trench that prevent oversteepening of the inner slope. +As the subducting plate approaches the trench, it bends slightly upwards before beginning its plunge into the depths. As a result, the outer trench slope is bounded by an outer trench high. This is subtle, often only tens of meters high, and is typically located a few tens of kilometers from the trench axis. On the outer slope itself, where the plate begins to bend downward into the trench, the upper part of the subducting slab is broken by bending faults that give the outer trench slope a horst and graben topography. The formation of these bending faults is suppressed where oceanic ridges or large seamounts are subducting into the trench, but the bending faults cut right across smaller seamounts. Where the subducting slab is only thinly veneered with sediments, the outer slope will often show seafloor spreading ridges oblique to the horst and graben ridges. + +=== Sedimentation === +Trench morphology is strongly modified by the amount of sedimentation in the trench. This varies from practically no sedimentation, as in the Tonga-Kermadec trench, to completely filled with sediments, as with the Cascadia subduction zone. Sedimentation is largely controlled by whether the trench is near a continental sediment source. The range of sedimentation is well illustrated by the Chilean trench. The north Chile portion of the trench, which lies along the Atacama Desert with its very slow rate of weathering, is sediment-starved, with from 20 to a few hundred meters of sediments on the trench floor. The tectonic morphology of this trench segment is fully exposed on the ocean bottom. The central Chile segment of the trench is moderately sedimented, with sediments onlapping onto pelagic sediments or ocean basement of the subducting slab, but the trench morphology is still clearly discernible. The southern Chile segment of the trench is fully sedimented, to the point where the outer rise and slope are no longer discernible. Other fully sedimented trenches include the Makran Trough, where sediments are up to 7.5 kilometers (4.7 mi) thick; the Cascadia subduction zone, which is completed buried by 3 to 4 kilometers (1.9 to 2.5 mi) of sediments; and the northernmost Sumatra subduction zone, which is buried under 6 kilometers (3.7 mi) of sediments. +Sediments are sometimes transported along the axis of an oceanic trench. The central Chile trench experiences transport of sediments from source fans along an axial channel. Similar transport of sediments has been documented in the Aleutian trench. +In addition to sedimentation from rivers draining into a trench, sedimentation also takes place from landslides on the tectonically steepened inner slope, often driven by megathrust earthquakes. The Reloca Slide of the central Chile trench is an example of this process. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Oceanic_trench-2.md b/data/en.wikipedia.org/wiki/Oceanic_trench-2.md new file mode 100644 index 000000000..ee5686d8d --- /dev/null +++ b/data/en.wikipedia.org/wiki/Oceanic_trench-2.md @@ -0,0 +1,27 @@ +--- +title: "Oceanic trench" +chunk: 3/6 +source: "https://en.wikipedia.org/wiki/Oceanic_trench" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:01.226469+00:00" +instance: "kb-cron" +--- + +=== Erosive versus accretionary margins === +Convergent margins are classified as erosive or accretionary, and this has a strong influence on the morphology of the inner slope of the trench. Erosive margins, such as the northern Peru-Chile, Tonga-Kermadec, and Mariana trenches, correspond to sediment-starved trenches. The subducting slab erodes material from the lower part of the overriding slab, reducing its volume. The edge of the slab experiences subsidence and steepening, with normal faulting. The slope is underlain by relative strong igneous and metamorphic rock, which maintains a high angle of repose. Over half of all convergent margins are erosive margins. +Accretionary margins, such as the southern Peru-Chile, Cascadia, and Aleutians, are associated with moderately to heavily sedimented trenches. As the slab subducts, sediments are "bulldozed" onto the edge of the overriding plate, producing an accretionary wedge or accretionary prism. This builds the overriding plate outwards. Because the sediments lack strength, their angle of repose is gentler than the rock making up the inner slope of erosive margin trenches. The inner slope is underlain by imbricated thrust sheets of sediments. The inner slope topography is roughened by localized mass wasting. Cascadia has practically no bathymetric expression of the outer rise and trench, due to complete sediment filling, but the inner trench slope is complex, with many thrust ridges. These compete with canyon formation by rivers draining into the trench. Inner trench slopes of erosive margins rarely show thrust ridges. +Accretionary prisms grow in two ways. The first is by frontal accretion, in which sediments are scraped off the downgoing plate and emplaced at the front of the accretionary prism. As the accretionary wedge grows, older sediments further from the trench become increasingly lithified, and faults and other structural features are steepened by rotation towards the trench. The other mechanism for accretionary prism growth is underplating (also known as basal accretion) of subducted sediments, together with some oceanic crust, along the shallow parts of the subduction decollement. The Franciscan Group of California is interpreted as an ancient accretionary prism in which underplating is recorded as tectonic mélanges and duplex structures. + +=== Earthquakes === +Frequent megathrust earthquakes modify the inner slope of the trench by triggering massive landslides. These leave semicircular landslide scarps with slopes of up to 20 degrees on the headwalls and sidewalls. +Subduction of seamounts and aseismic ridges into the trench may increase aseismic creep and reduce the severity of earthquakes. Contrariwise, subduction of large amounts of sediments may allow ruptures along the subduction décollement to propagate for great distances to produce megathrust earthquakes. + +== Trench rollback == +Trenches seem positionally stable over time, but scientists believe that some trenches—particularly those associated with subduction zones where two oceanic plates converge—move backward into the subducting plate. This is called trench rollback or retreat, hinge rollback or retreat, slab rollback or retreat and is one explanation for the existence of back-arc basins. +Forces perpendicular to the slab (the portion of the subducting plate within the mantle) are responsible for steepening of the slab and, ultimately, the movement of the hinge and trench at the surface. These forces arise from the negative buoyancy of the slab with respect to the mantle modified by the geometry of the slab itself. The extension in the overriding plate, in response to the subsequent subhorizontal mantle flow from the displacement of the slab, can result in formation of a back-arc basin. + +=== Processes involved === +Several forces are involved in the process of slab rollback. Two forces acting against each other at the interface of the two subducting plates exert forces against one another. The subducting plate exerts a bending force (FPB) that supplies pressure during subduction, while the overriding plate exerts a force against the subducting plate (FTS). The slab pull force (FSP) is caused by the negative buoyancy of the plate driving the plate to greater depths. The resisting force from the surrounding mantle opposes the slab pull forces. Interactions with the 660-km discontinuity cause a deflection due to the buoyancy at the phase transition (F660). The unique interplay of these forces is what generates slab rollback. When the deep slab section obstructs the down-going motion of the shallow slab section, slab rollback occurs. The subducting slab undergoes backward sinking due to the negative buoyancy forces causing a retrogradation of the trench hinge along the surface. Upwelling of the mantle around the slab can create favorable conditions for the formation of a back-arc basin. +Seismic tomography provides evidence for slab rollback. Results demonstrate high temperature anomalies within the mantle suggesting subducted material is present in the mantle. Ophiolites are viewed as evidence for such mechanisms as high pressure and temperature rocks are rapidly brought to the surface through the processes of slab rollback, which provides space for the exhumation of ophiolites. +Slab rollback is not always a continuous process suggesting an episodic nature. The episodic nature of the rollback is explained by a change in the density of the subducting plate, such as the arrival of buoyant lithosphere (a continent, arc, ridge, or plateau), a change in the subduction dynamics, or a change in the plate kinematics. The age of the subducting plates does not have any effect on slab rollback. Nearby continental collisions have an effect on slab rollback. Continental collisions induce mantle flow and extrusion of mantle material, which causes stretching and arc-trench rollback. In the area of the Southeast Pacific, there have been several rollback events resulting in the formation of numerous back-arc basins. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Oceanic_trench-3.md b/data/en.wikipedia.org/wiki/Oceanic_trench-3.md new file mode 100644 index 000000000..d69e68738 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Oceanic_trench-3.md @@ -0,0 +1,36 @@ +--- +title: "Oceanic trench" +chunk: 4/6 +source: "https://en.wikipedia.org/wiki/Oceanic_trench" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:01.226469+00:00" +instance: "kb-cron" +--- + +=== Mantle interactions === +Interactions with the mantle discontinuities play a significant role in slab rollback. Stagnation at the 660-km discontinuity causes retrograde slab motion due to the suction forces acting at the surface. Slab rollback induces mantle return flow, which causes extension from the shear stresses at the base of the overriding plate. As slab rollback velocities increase, circular mantle flow velocities also increase, accelerating extension rates. Extension rates are altered when the slab interacts with the discontinuities within the mantle at 410 km and 660 km depth. Slabs can either penetrate directly into the lower mantle, or can be retarded due to the phase transition at 660 km depth creating a difference in buoyancy. An increase in retrograde trench migration (slab rollback) (2–4 cm/yr) is a result of flattened slabs at the 660-km discontinuity where the slab does not penetrate into the lower mantle. This is the case for the Japan, Java and Izu–Bonin trenches. These flattened slabs are only temporarily arrested in the transition zone. The subsequent displacement into the lower mantle is caused by slab pull forces, or the destabilization of the slab from warming and broadening due to thermal diffusion. Slabs that penetrate directly into the lower mantle result in slower slab rollback rates (~1–3 cm/yr) such as the Mariana arc, Tonga arcs. + +== Hydrothermal activity and associated biomes == +As sediments are subducted at the bottom of trenches, much of their fluid content is expelled and moves back along the subduction décollement to emerge on the inner slope as mud volcanoes and cold seeps. Methane clathrates and gas hydrates also accumulate in the inner slope, and there is concern that their breakdown could contribute to global warming. +The fluids released at mud volcanoes and cold seeps are rich in methane and hydrogen sulfide, providing chemical energy for chemotrophic microorganisms that form the base of a unique trench biome. Cold seep communities have been identified in the inner trench slopes of the western Pacific (especially Japan), South America, Barbados, the Mediterranean, Makran, and the Sunda trench. These are found at depths as great as 6,000 meters (20,000 ft). The genome of the extremophile Deinococcus from Challenger Deep has sequenced for its ecological insights and potential industrial uses. +Because trenches are the lowest points in the ocean floor, there is concern that plastic debris may accumulate in trenches and endanger the fragile trench biomes. + +== Deepest oceanic trenches == +Recent measurements, where the salinity and temperature of the water was measured throughout the dive, have uncertainties of about 15 m (49 ft). Older measurements may be off by hundreds of meters. + +== Notable oceanic trenches == + +(*) The five deepest trenches in the world + +== Ancient oceanic trenches == + +== See also == + +Glossary of landforms +List of submarine topographical features +Mid-ocean ridge +Physical oceanography +Ring of Fire + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Oceanic_trench-4.md b/data/en.wikipedia.org/wiki/Oceanic_trench-4.md new file mode 100644 index 000000000..0966923e8 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Oceanic_trench-4.md @@ -0,0 +1,48 @@ +--- +title: "Oceanic trench" +chunk: 5/6 +source: "https://en.wikipedia.org/wiki/Oceanic_trench" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:01.226469+00:00" +instance: "kb-cron" +--- + +== Bibliography == +Allwrardt, Allan O. (1993). "Evolution of the tectogene concept, 1930–1965" (PDF). Proceedings of the Fifth International Congress on the History of Oceanography. Retrieved 29 September 2021. +Amos, Jonathan (11 May 2021). "Oceans' extreme depths measured in precise detail". News. BBC. Retrieved 2 October 2021. +Bangs, N. L.; Morgan, J. K.; Tréhu, A. M.; Contreras-Reyes, E.; Arnulf, A. F.; Han, S.; Olsen, K. M.; Zhang, E. (November 2020). "Basal Accretion Along the South Central Chilean Margin and Its Relationship to Great Earthquakes". Journal of Geophysical Research: Solid Earth. 125 (11). Bibcode:2020JGRB..12519861B. doi:10.1029/2020JB019861. S2CID 225154312. +Bodine, J.H.; Watts, A.B (1979). "On lithospheric flexure seaward of the Bonin and Mariana trenches". Earth and Planetary Science Letters. 43 (1): 132–148. Bibcode:1979E&PSL..43..132B. doi:10.1016/0012-821X(79)90162-6. +Christensen, UR (1996). "The Influence of Trench Migration on Slab Penetration into the Lower Mantle". Earth and Planetary Science Letters. 140 (1–4): 27–39. Bibcode:1996E&PSL.140...27C. doi:10.1016/0012-821x(96)00023-4. +Dastanpour, Mohammad (March 1996). "The Devonian System in Iran: a review". Geological Magazine. 133 (2): 159–170. Bibcode:1996GeoM..133..159D. doi:10.1017/S0016756800008670. S2CID 129199671. +Dvorkin, Jack; Nur, Amos; Mavko, Gary; Ben-Avraham, Zvi (1993). "Narrow subducting slabs and the origin of backarc basins". Tectonophysics. 227 (1–4): 63–79. Bibcode:1993Tectp.227...63D. doi:10.1016/0040-1951(93)90087-Z. +Einsele, Gerhard (2000). Sedimentary Basins: Evolution, Facies, and Sediment Budget (2nd ed.). Springer. p. 630. ISBN 978-3-540-66193-1. +Eiseley, Loren (1946). "The Great Deeps". The Immense Journey (1959 ed.). United States: Vintage Books. p. 38–41. ISBN 0-394-70157-7. {{cite book}}: ISBN / Date incompatibility (help) +Fujikura, K.; Lindsay, D.; Kitazato, H.; Nishida, S.; Shirayama, Y. (2010). "Marine Biodiversity in Japanese Waters". PLOS One. 5 (8) e11836. Bibcode:2010PLoSO...511836F. doi:10.1371/journal.pone.0011836. PMC 2914005. PMID 20689840. +"Deep-sea trench". McGraw-Hill Encyclopedia of Science & Technology (8th ed.). 1997. +Flower, MFJ; Dilek, Y (2003). "Arc–trench Rollback and Forearc Accretion: 1. A Collision–Induced Mantle Flow Model for Tethyan Ophiolites". Pub. Geol. Soc. Lond. 218 (1): 21–41. Bibcode:2003GSLSP.218...21F. doi:10.1144/gsl.sp.2003.218.01.03. S2CID 128899276. +Gallo, N.D.; Cameron, J; Hardy, K.; Fryer, P.; Bartlett, D.H.; Levin, L.A. (2015). "Submersible- and lander-observed community patterns in the Mariana and New Britain trenches: Influence of productivity and depth on epibenthic and scavenging communities". Deep Sea Research Part I: Oceanographic Research Papers. 99: 119–133. Bibcode:2015DSRI...99..119G. doi:10.1016/j.dsr.2014.12.012. +Garfunkel, Z; Anderson, C. A.; Schubert, G (10 June 1986). "Mantle circulation and the lateral migration of subducted slabs". Journal of Geophysical Research: Solid Earth. 91 (B7): 7205–7223. Bibcode:1986JGR....91.7205G. doi:10.1029/JB091iB07p07205. +Geersen, Jacob; Voelker, David; Behrmann, Jan H. (2018). "Oceanic Trenches". Submarine Geomorphology. Springer Geology. pp. 409–424. doi:10.1007/978-3-319-57852-1_21. ISBN 978-3-319-57851-4. +Goldfinger, Chris; Nelson, C. Hans; Morey, Ann E.; Johnson, Joel E.; Patton, Jason R.; Karabanov, Eugene B.; Gutierrez-Pastor, Julia; Eriksson, Andrew T.; Gracia, Eulalia; Dunhill, Gita; Enkin, Randolph J.; Dallimore, Audrey; Vallier, Tracy (2012). Kayen, Robert (ed.). "Turbidite event history—Methods and implications for Holocene paleoseismicity of the Cascadia subduction zone". U.S. Geological Survey Professional Paper. Professional Paper. 1661-E: 4. Bibcode:2012usgs.rept....4G. doi:10.3133/pp1661F. +Hackney, Ron; Sutherland, Rupert; Collot, Julien (June 2012). "Rifting and subduction initiation history of the New Caledonia Trough, southwest Pacific, constrained by process-oriented gravity models: Gravity modelling of the New Caledonia Trough". Geophysical Journal International. 189 (3): 1293–1305. doi:10.1111/j.1365-246X.2012.05441.x. +Hall, R; Spakman, W (2002). "Subducted Slabs Beneath the Eastern Indonesia–Tonga Region: Insights from Tomography". Earth and Planetary Science Letters. 201 (2): 321–336. Bibcode:2002E&PSL.201..321H. CiteSeerX 10.1.1.511.9094. doi:10.1016/s0012-821x(02)00705-7. S2CID 129884170. +Harris, P.T.; MacMillan-Lawler, M.; Rupp, J.; Baker, E.K. (2014). "Geomorphology of the oceans". Marine Geology. 352: 4–24. Bibcode:2014MGeol.352....4H. doi:10.1016/j.margeo.2014.01.011. +Jamieson, A.J.; Fujii, T.; Mayor, D.J.; Solan', M.; Priede, I.G. (2010). "Hadal trenches: the ecology of the deepest places on Earth". Trends in Ecology & Evolution. 25 (3): 190–197. Bibcode:2010TEcoE..25..190J. doi:10.1016/j.tree.2009.09.009. PMID 19846236. +Johnstone, James (1923). An Introduction to Oceanography, With Special Reference to Geography and Geophysics. Creative Media Partners, LLC. ISBN 978-1-340-39958-0. {{cite book}}: ISBN / Date incompatibility (help) +Kearey, P.; Klepeis, K.A.; Vine, F.J. (2009). Global tectonics (3rd ed.). Oxford: Wiley-Blackwell. pp. 184–188. ISBN 978-1-4051-0777-8. +McConnell, A. (1990). "The art of submarine cable- laying: its contribution to physical oceanography". Deutsche hydrographische Zeitschrift, Erganzungs-heft, B. 22: 467–473. +Nakakuki, T; Mura, E (2013). "Dynamics of Slab Rollback and Induced Back-Arc Basin Formation". Earth and Planetary Science Letters. 361 (B11): 287–297. Bibcode:2013E&PSL.361..287N. doi:10.1016/j.epsl.2012.10.031. +Peng, Guyu; Bellerby, Richard; Zhang, Feng; Sun, Xuerong; Li, Daoji (January 2020). "The ocean's ultimate trashcan: Hadal trenches as major depositories for plastic pollution". Water Research. 168 115121. Bibcode:2020WatRe.16815121P. doi:10.1016/j.watres.2019.115121. hdl:11250/2677323. PMID 31605833. S2CID 204122125. +Rowley, David B. (2002). "Rate of plate creation and destruction: 180 Ma to present". Geological Society of America Bulletin. 114 (8): 927–933. Bibcode:2002GSAB..114..927R. doi:10.1130/0016-7606(2002)114<0927:ROPCAD>2.0.CO;2. +Schellart, WP; Lister, GS; Toy, VG (2006). "A Late Cretaceous and Cenozoic Reconstruction of the Southwest Pacific Region: Tectonics Controlled by Subduction and Slab Rollback Processes". Earth-Science Reviews. 76 (3–4): 191–233. Bibcode:2006ESRv...76..191S. doi:10.1016/j.earscirev.2006.01.002. +Schellart, WP; Moresi, L (2013). "A New Driving Mechanism for Backarc Extension and Backarc Shortening Through Slab Sinking Induced Toroidal and Poloidal Mantle Flow: Results from dynamic subduction models with an overriding plate". Journal of Geophysical Research. 118 (6): 3221–3248. Bibcode:2013JGRB..118.3221S. doi:10.1002/jgrb.50173. +Stern, R.J. (2005). "TECTONICS | Ocean Trenches". Encyclopedia of Geology. pp. 428–437. doi:10.1016/B0-12-369396-9/00141-6. ISBN 978-0-12-369396-9. +Thomas, C.; Burbidge, D.; Cummins, P. (2007). A preliminary study into the tsunami hazard faced by southwest Pacific nations. Risk and Impact Analysis Group, Geoscience Australia. Retrieved 26 September 2021. +Thomson, C.W.; Murray, J. (1895). "Report on the scientific results of the voyage of H.M.S. Challenger during the years of 1872–76 (page 877)". 19thcenturyscience.org. Archived from the original on 17 April 2012. Retrieved 26 March 2012. +Völker, David; Geersen, Jacob; Contreras-Reyes, Eduardo; Sellanes, Javier; Pantoja, Silvio; Rabbel, Wolfgang; Thorwart, Martin; Reichert, Christian; Block, Martin; Weinrebe, Wilhelm Reimer (October 2014). "Morphology and geology of the continental shelf and upper slope of southern Central Chile (33°S–43°S)" (PDF). International Journal of Earth Sciences. 103 (7): 1765–1787. Bibcode:2014IJEaS.103.1765V. doi:10.1007/s00531-012-0795-y. S2CID 129460412. +Völker, D.; Weinrebe, W.; Behrmann, J. H.; Bialas, J.; Klaeschen, D. (2009). "Mass wasting at the base of the south central Chilean continental margin: The Reloca Slide". Advances in Geosciences. 22: 155–167. Bibcode:2009AdG....22..155V. doi:10.5194/adgeo-22-155-2009. +Völker, David; Geersen, Jacob; Contreras-Reyes, Eduardo; Reichert, Christian (2013). "Sedimentary fill of the Chile Trench (32–46°S): Volumetric distribution and causal factors". Journal of the Geological Society. 170 (5): 723–736. Bibcode:2013JGSoc.170..723V. doi:10.1144/jgs2012-119. S2CID 128432525. +Weyl, Peter K. (1969). Oceanography: an introduction to the marine environment. New York: Wiley. ISBN 978-0-471-93744-9. +Westbrook, G.K.; Mascle, A.; Biju-Duval, B. (1984). "Geophysics and the structure of the Lesser Antilles forearc" (PDF). Initial Reports of the Deep Sea Drilling Project. 78: 23–38. Retrieved 26 September 2021. +Zhang, Ru-Yi; Huang, Ying; Qin, Wen-Jing; Quan, Zhe-Xue (June 2021). "The complete genome of extracellular protease-producing Deinococcus sp. D7000 isolated from the hadal region of Mariana Trench Challenger Deep". Marine Genomics. 57 100832. Bibcode:2021MarGn..5700832Z. doi:10.1016/j.margen.2020.100832. PMID 33867118. S2CID 229392459. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Oceanic_trench-5.md b/data/en.wikipedia.org/wiki/Oceanic_trench-5.md new file mode 100644 index 000000000..0552cda87 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Oceanic_trench-5.md @@ -0,0 +1,29 @@ +--- +title: "Oceanic trench" +chunk: 6/6 +source: "https://en.wikipedia.org/wiki/Oceanic_trench" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:01.226469+00:00" +instance: "kb-cron" +--- + +== Further reading == +Ellouz-Zimmermann, N.; Deville, E.; Müller, C.; Lallemant, S.; Subhani, A. B.; Tabreez, A. R. (2007). "Impact of Sedimentation on Convergent Margin Tectonics: Example of the Makran Accretionary Prism (Pakistan)". Thrust Belts and Foreland Basins. Frontiers in Earth Sciences. pp. 327–350. doi:10.1007/978-3-540-69426-7_17. ISBN 978-3-540-69425-0. +Fisher, R. L.; Hess, H. H. (1963). "Trenches". In M. N. Hill (ed.). The Sea v. 3 The Earth Beneath the Sea. New York: Wiley-Interscience. pp. 411–436. +Hamilton, W. B. (1988). "Plate tectonics and island arcs". Geological Society of America Bulletin. Vol. 100, no. 10. pp. 1503–1527. +Hawkins, J. W.; Bloomer, S. H.; Evans, C. A.; Melchior, J. T. (1984). "Evolution of Intra-Oceanic Arc-Trench Systems". Tectonophysics. 102 (1–4): 175–205. Bibcode:1984Tectp.102..175H. doi:10.1016/0040-1951(84)90013-1. +Jarrard, R. D. (1986). "Relations among subduction parameters". Reviews of Geophysics. 24 (2): 217–284. Bibcode:1986RvGeo..24..217J. doi:10.1029/RG024i002p00217. +Ladd, J.W.; Holcombe, T. L.; Westbrook, G. K.; Edgar, N. T. (1990). "Caribbean Marine Geology: Active margins of the plate boundary". In Dengo, G.; Case, J. (eds.). The Geology of North America. Vol. H: The Caribbean Region. Geological Society of America. pp. 261–290. +Lemenkova, Paulina (2021). "Topography of the Aleutian Trench south-east off Bowers Ridge, Bering Sea, in the context of the geological development of North Pacific Ocean". Baltica. 34 (1): 27–46. doi:10.5200/baltica.2021.1.3. hdl:2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/363968. S2CID 247031368. SSRN 3854076. +Schellart, WP; Lister, GS (2004). "Orogenic Curvature: Paleomagnetic and Structural Analyses". Geological Society of America: 237–254. +Scholl, D. W.; Scholl, D (1993). "The return of sialic material to the mantle indicated by terrigeneous material subducted at convergent margins". Tectonophysics. 219 (1–3): 163–175. Bibcode:1993Tectp.219..163V. doi:10.1016/0040-1951(93)90294-T. +Sibuet, M.; Olu, K. (1998). "Biogeography, biodiversity and fluid dependence of deep-sea cold-seep communities at active and passive margins". Deep-Sea Research. II (45): 517–567. Bibcode:1998DSRII..45..517S. doi:10.1016/S0967-0645(97)00074-X. +Smith, W. H. F.; Sandwell, D. T. (1997). "Global sea floor topography from satellite altimetry and ship depth soundings". Science. 277 (5334): 1956–1962. doi:10.1126/science.277.5334.1956. +Stern, R. J. (2002). "Subduction Zones". Reviews of Geophysics. 40 (4): 1012–1049. Bibcode:2002RvGeo..40.1012S. doi:10.1029/2001RG000108. S2CID 247695067. +Watts, A.B. (2001). Isostasy and Flexure of the Lithosphere. Cambridge University Press. 458p. +Wright, D. J.; Bloomer, S. H.; MacLeod, C. J.; Taylor, B.; Goodlife, A. M. (2000). "Bathymetry of the Tonga Trench and Forearc: a map series". Marine Geophysical Researches. 21 (489–511): 2000. Bibcode:2000MarGR..21..489W. doi:10.1023/A:1026514914220. S2CID 6072675. + +== External links == +"HADEX: Research project to explore ocean trenches". Woods Hole Oceanographic Institution. +"Ocean Trenches". Woods Hole Oceanographic Institution. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Oceanic_zone-0.md b/data/en.wikipedia.org/wiki/Oceanic_zone-0.md new file mode 100644 index 000000000..93af1a620 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Oceanic_zone-0.md @@ -0,0 +1,30 @@ +--- +title: "Oceanic zone" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Oceanic_zone" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:02.393656+00:00" +instance: "kb-cron" +--- + +The oceanic zone is typically defined as the area of the ocean lying beyond the continental shelf (e.g. the neritic zone), but operationally is often referred to as beginning where the water depths drop to below 200 metres (660 ft), seaward from the coast into the open ocean with its pelagic zone. +It is the region of open sea beyond the edge of the continental shelf and includes 65% of the ocean's completely open water. The oceanic zone has a wide array of undersea terrain, including trenches that are often deeper than Mount Everest is tall, as well as deep-sea volcanoes and basins. While it is often difficult for life to sustain itself in this type of environment, many species have adapted and do thrive in the oceanic zone. +The open ocean is vertically divided into four zones: the sunlight zone, twilight zone, midnight zone, and abyssal zone. + + +== Sub zones == +The Mesopelagic (disphotic) zone, which is where only small amounts of light penetrate, lies below the Epipelagic zone. This zone is often referred to as the "Twilight Zone" due to its scarce amount of light. Temperatures in the Mesopelagic zone range from 5 to 4 °C (41 to 39 °F). The pressure is higher here, it can be up to 10,100 kilopascals (1,460 psi) and increases with depth. +54% of the ocean lies in the Bathypelagic (aphotic) zone into which no light penetrates. This is also called the midnight zone and the deep ocean. Due to the complete lack of sunlight, photosynthesis cannot occur and the only light source is bioluminescence. Water pressure is very intense and the temperatures are near freezing (range 0 to 6 °C (32 to 43 °F)). + + +== Marine life == + +Oceanographers have divided the ocean into zones based on how far light reaches. All of the light zones can be found in the oceanic zone. The epipelagic zone is the one closest to the surface and is the best lit. It extends to 100 meters and contains both phytoplankton and zooplankton that can support larger organisms like marine mammals and some types of fish. Past 100 meters, not enough light penetrates the water to support life, and no plant life exists. +There are creatures, however, which thrive around hydrothermal vents, or geysers located on the ocean floor that expel superheated water that is rich in minerals. These organisms feed off of chemosynthetic bacteria, which use the superheated water and chemicals from the hydrothermal vents to create energy in place of photosynthesis. The existence of these bacteria allow creatures like squids, hatchet fish, octopuses, tube worms, giant clams, spider crabs and other organisms to survive. + +Due to the total darkness in the zones past the epipelagic zone, many organisms that survive in the deep oceans do not have eyes, and other organisms make their own light with bioluminescence. Often the light is blue-green in color, because many marine organisms are sensitive to blue light. Two chemicals, luciferin, and luciferase that react with one another to create a soft glow. The process by which bioluminescence is created is very similar to what happens when a glow stick is broken. Deep-sea organisms use bioluminescence for everything from luring prey to navigation. +Animals such as fish, whales, and sharks are found in the oceanic zone. + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Omics-0.md b/data/en.wikipedia.org/wiki/Omics-0.md new file mode 100644 index 000000000..53d8a58e3 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Omics-0.md @@ -0,0 +1,52 @@ +--- +title: "Omics" +chunk: 1/2 +source: "https://en.wikipedia.org/wiki/Omics" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:51.894950+00:00" +instance: "kb-cron" +--- + +Omics is the collective characterization and quantification of entire sets of biological molecules and the investigation of how they translate into the structure, function, and dynamics of an organism or group of organisms. The branches of science known informally as omics are various disciplines in biology whose names end in the suffix -omics, such as genomics, proteomics, metabolomics, metagenomics, phenomics and transcriptomics. +The related suffix -ome is used to address the objects of study of such fields, such as the genome, proteome or metabolome respectively. The suffix -ome as used in molecular biology refers to a totality of some sort; it is an example of a "neo-suffix" formed by abstraction from various Greek terms in -ωμα, a sequence that does not form an identifiable suffix in Greek. +Functional genomics aims at identifying the functions of as many genes as possible of a given organism. It combines +different -omics techniques such as transcriptomics and proteomics with saturated mutant collections. + +== Origin == + +The Oxford English Dictionary (OED) distinguishes three different fields of application for the -ome suffix: + +in medicine, forming nouns with the sense "swelling, tumour" +in botany or zoology, forming nouns in the sense "a part of an animal or plant with a specified structure" +in cellular and molecular biology, forming nouns with the sense "all constituents considered collectively" +The -ome suffix originated as a variant of -oma, and became productive in the last quarter of the 19th century. It originally appeared in terms like sclerome or rhizome. All of these terms derive from Greek words in -ωμα, a sequence that is not a single suffix, but analyzable as -ω-μα, the -ω- belonging to the word stem (usually a verb) and the -μα being a genuine Greek suffix forming abstract nouns. +The OED suggests that its third definition originated as a back-formation from mitome, Early attestations include biome (1916) and genome (first coined as German Genom in 1920). +The association with chromosome in molecular biology is by false etymology. The word chromosome derives from the Greek stems χρωμ(ατ)- "colour" and σωμ(ατ)- "body". While σωμα "body" genuinely contains the -μα suffix, the preceding -ω- is not a stem-forming suffix but part of the word's root. Because genome refers to the complete genetic makeup of an organism, a neo-suffix -ome suggested itself as referring to "wholeness" or "completion". +Bioinformaticians and molecular biologists figured amongst the first scientists to apply the "-ome" suffix widely. Early advocates included bioinformaticians in Cambridge, UK, where there were many early bioinformatics labs such as the MRC centre, Sanger centre, and EBI (European Bioinformatics Institute); for example, the MRC centre carried out the first genome and proteome projects. + +== Current usage == +Many "omes" beyond the original "genome" have become useful and have been widely adopted by research scientists. "Proteomics" has become well-established as a term for studying proteins at a large scale. "Omes" can provide an easy shorthand to encapsulate a field; for example, an interactomics study is clearly recognisable as relating to large-scale analyses of gene-gene, protein-protein, or protein-ligand interactions. Researchers are rapidly taking up omes and omics, as shown by the explosion of the use of these terms in PubMed since the mid-1990s. + +== Kinds of omics studies == + +=== Genomics === +Genomics: Study of the genomes of organisms. +Cognitive genomics: Study of the changes in cognitive processes associated with genetic profiles. +Comparative genomics: Study of the relationship of genome structure and function across different biological species or strains. +Functional genomics: Describes gene and protein functions and interactions (often uses transcriptomics). +Metagenomics: Study of metagenomes, i.e., genetic material recovered directly from environmental samples. +Neurogenomics: Study of genetic influences on the development and function of the nervous system. +Pangenomics: Study of the entire collection of genes or genomes found within a given species. +Personal genomics: Branch of genomics concerned with the sequencing and analysis of the genome of an individual. Once the genotypes are known, the individual's genotype can be compared with the published literature to determine likelihood of trait expression and disease risk. Helps in Personalized Medicine +Electromics: Branch of genomics concerned with the role of exogenous electric fields in potentiating the gene expression profiles of cells, tissues, and organoids. + +=== Epigenomics === +The epigenome is the supporting structure of the genome, including protein and RNA binders, alternative DNA structures, and chemical modifications on DNA. + +Epigenomics: Modern technologies include chromosome conformation by Hi-C, various ChIP-seq and other sequencing methods combined with proteomic fractionations, and sequencing methods that find chemical modification of cytosines, like bisulfite sequencing. +Nucleomics: Study of the complete set of genomic components which form "the cell nucleus as a complex, dynamic biological system, referred to as the nucleome". The 4D Nucleome Consortium officially joined the IHEC (International Human Epigenome Consortium) in 2017. + +=== Microbiomics === +The microbiome is a microbial community occupying a well-defined habitat with distinct physio-chemical properties. It includes the microorganisms involved and their theatre of activity, forming ecological niches. Microbiomes form dynamic and interactive micro-ecosystems prone to spaciotemporal change. They are integrated into macro-ecosystems, such as eukaryotic hosts, and are crucial to the host's proper function and health. The interactive host-microbe systems make up the holobiont. +Microbiomics is the study of microbiome dynamics, function, and structure. This area of study employs several techniques to study the microbiome in its host environment: \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Omics-1.md b/data/en.wikipedia.org/wiki/Omics-1.md new file mode 100644 index 000000000..7205aa548 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Omics-1.md @@ -0,0 +1,94 @@ +--- +title: "Omics" +chunk: 2/2 +source: "https://en.wikipedia.org/wiki/Omics" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:51.894950+00:00" +instance: "kb-cron" +--- + +Sampling methods focused on collecting representative samples of the local environment, either from oral swabs or stool. +Culturomics (microbiology) is the high-throughput cell culture of bacteria that aims to comprehensively identify strains or species in samples obtained from tissues such as the human gut or from the environment. +Microfluidics gut-on-a-chip devices, which simulate the conditions of the gut and allow analysis of changes to the microbiome that can be more accurately monitored than in situ. +Mechanical DNA extraction techniques and gene amplification methods, such as PCR, to analyze the genomic profile of the entire microbiome. +DNA fingerprinting using microarrays and hybridization techniques allow analysis of shifts in microbiota populations. +Multi-omics studies allow for functional analysis of microbiota. +Animal models can be used to take more accurate samples of the in situ microbiome. Germ-free animals are used to implant a specific microbiome from another organism to yield a gnotobiotic model. These can be studied to see how it changes under different environmental conditions. + +=== Lipidomics === +The lipidome is the entire complement of cellular lipids, including the modifications made to a particular set of lipids, produced by an organism or system. + +Lipidomics: Large-scale study of pathways and networks of lipids. Mass spectrometry techniques are used. + +=== Proteomics === +The proteome is the entire complement of proteins, including the modifications made to a particular set of proteins, produced by an organism or system. + +Proteomics: Large-scale study of proteins, particularly their structures and functions. Mass spectrometry techniques are used. +Chemoproteomics: An array of techniques used to study protein-small molecule interactions +Immunoproteomics: Study of large sets of proteins (proteomics) involved in the immune response +Nutriproteomics: Identifying the molecular targets of nutritive and non-nutritive components of the diet. Uses proteomics mass spectrometry data for protein expression studies +Proteogenomics: An emerging field of biological research at the intersection of proteomics and genomics. Proteomics data used for gene annotations. +Structural genomics: Study of the three-dimensional structure of every protein encoded by a given genome using a combination of experimental and modeling approaches. + +=== Glycomics === +Glycomics is the comprehensive study of the glycome i.e. sugars and carbohydrates. + +=== Foodomics === +Foodomics was defined by Alejandro Cifuentes in 2009 as "a discipline that studies the food and nutrition domains through the application and integration of advanced omics technologies to improve consumer's well-being, health, and knowledge." + +=== Transcriptomics === +Transcriptome is the set of all RNA molecules, including mRNA, rRNA, tRNA, and other non-coding RNA, produced in one or a population of cells. + +Transcriptomics: Study of transcriptomes, their structures and functions. + +=== Metabolomics === +The metabolome is the ensemble of small molecules found within a biological matrix. + +Metabolomics: Scientific study of chemical processes involving metabolites. It is a "systematic study of the unique chemical fingerprints that specific cellular processes leave behind", the study of their small-molecule metabolite profiles +Metabonomics: The quantitative measurement of the dynamic multiparametric metabolic response of living systems to pathophysiological stimuli or genetic modification + +=== Nutrition, pharmacology, and toxicology === +Nutritional genomics: A science studying the relationship between human genome, nutrition and health. +Nutrigenetics studies the effect of genetic variations on the interaction between diet and health with implications to susceptible subgroups +Nutrigenomics: Study of the effects of foods and food constituents on gene expression. Studies the effect of nutrients on the genome, proteome, and metabolome +Pharmacogenomics investigates the effect of the sum of variations within the human genome on drugs; +Pharmacomicrobiomics investigates the effect of variations within the human microbiome on drugs and vice versa. +Toxicogenomics: a field of science that deals with the collection, interpretation, and storage of information about gene and protein activity within particular cell or tissue of an organism in response to toxic substances. + +=== Culture === +Inspired by foundational questions in evolutionary biology, a Harvard team around Jean-Baptiste Michel and Erez Lieberman Aiden created the American neologism culturomics for the application of big data collection and analysis to cultural studies. + +=== Miscellaneous === + +Mitointeractome +Psychogenomics: Process of applying the powerful tools of genomics and proteomics to achieve a better understanding of the biological substrates of normal behavior and of diseases of the brain that manifest themselves as behavioral abnormalities. Applying psychogenomics to the study of drug addiction, the ultimate goal is to develop more effective treatments for these disorders as well as objective diagnostic tools, preventive measures, and eventually cures. +Stem cell genomics: Helps in stem cell biology. Aim is to establish stem cells as a leading model system for understanding human biology and disease states and ultimately to accelerate progress toward clinical translation. +Connectomics: The study of the connectome, the totality of the neural connections in the brain. +Cellomics: The quantitative cell analysis and study using bioimaging methods and bioinformatics. +Tomomics: A combination of tomography and omics methods to understand tissue or cell biochemistry at high spatial resolution, typically using imaging mass spectrometry data. +Viral metagenomics: Using omics methods in soil, ocean water, and humans to study the Virome and Human virome. +Ethomics: The high-throughput machine measurement of animal behaviour. +Videomics (or vide-omics): A video analysis paradigm inspired by genomics principles, where a continuous image sequence (or video) can be interpreted as the capture of a single image evolving through time through mutations revealing 'a scene'. +Multiomics: Integration of different omics in a single study or analysis pipeline. + +== Unrelated words in -omics == +The word "comic" does not use the "omics" suffix; it derives from Greek "κωμ(ο)-" (merriment) + "-ικ(ο)-" (an adjectival suffix), rather than presenting a truncation of "σωμ(ατ)-". +Similarly, the word "economy" is assembled from Greek "οικ(ο)-" (household) + "νομ(ο)-" (law or custom), and "economic(s)" from "οικ(ο)-" + "νομ(ο)-" + "-ικ(ο)-". The suffix -omics is sometimes used to create names for schools of economics, such as Reaganomics. + +== See also == +Systems biology +Multiomics +Panomics +Ology + +== Notes == + +== Further reading == +Lederberg, Joshua; McCray, Alexa T. (April 2, 2001). "Commentary: 'Ome Sweet 'Omics — A Genealogical Treasury of Words". The Scientist. 15 (7): 8. Retrieved 1 June 2014. +Hotz, Robert Lee (13 August 2012). "Here's an Omical Tale: Scientists Discover Spreading Suffix". The Wall Street Journal. + +== External links == + +Omics.org Archived 2014-01-02 at the Wayback Machine Omics terms and concepts home page. Probably the first omics web page created. +List of omics Archived 2015-07-09 at the Wayback Machine, including references/origins. Maintained by the (CHI) Cambridge Health Institute. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/On_Gaia b/data/en.wikipedia.org/wiki/On_Gaia new file mode 100644 index 000000000..e69de29bb diff --git a/data/en.wikipedia.org/wiki/Paleoceanography-0.md b/data/en.wikipedia.org/wiki/Paleoceanography-0.md new file mode 100644 index 000000000..bfdbf8cd2 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Paleoceanography-0.md @@ -0,0 +1,68 @@ +--- +title: "Paleoceanography" +chunk: 1/2 +source: "https://en.wikipedia.org/wiki/Paleoceanography" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:03.665799+00:00" +instance: "kb-cron" +--- + +Paleoceanography is the study of the history of the oceans in the geologic past with regard to biology, chemistry, circulation, geology, and patterns of biological productivity and sedimentation. Paleoceanographic studies using environment models and different proxies enable the scientific community to assess the role of the oceanic processes in the global climate by the re-construction of past climate at various intervals. Paleoceanographic research is also intimately tied to paleoclimatology. + +== Source and methods of information == + +Paleoceanography makes use of so-called proxy methods as a way to infer information about the past state and evolution of the world's oceans. Several geochemical proxy tools include long-chain organic molecules (e.g. alkenones), stable and radioactive isotopes, and trace metals. Additionally, sediment cores rich with fossils and shells (tests) can also be useful; the field of paleoceanography is closely related to sedimentology and paleontology. + +=== Sea-surface temperature === +Sea-surface temperature (SST) records can be extracted from deep-sea sediment cores using oxygen isotope ratios and the ratio of magnesium to calcium (Mg/Ca) in shell secretions from plankton, from long-chain organic molecules such as alkenone, from tropical corals near the sea surface, and from mollusk shells. +Oxygen isotope ratios (δ18O) are useful in reconstructing SST because of the influence temperature has on the isotope ratio. Plankton take up oxygen in building their shells and will be less enriched in their δ18O when formed in warmer waters, provided they are in thermodynamic equilibrium with the seawater. When these shells precipitate, they sink and form sediments on the ocean floor whose δ18O can be used to infer past SSTs. Oxygen isotope ratios are not perfect proxies, however. The volume of ice trapped in continental ice sheets can have an impact of the δ18O. Freshwater characterized by lower values of δ18O becomes trapped in the continental ice sheets, so that during glacial periods seawater δ18O is elevated and calcite shells formed during these times will have a larger δ18O value. +The substitution of magnesium in place of calcium in CaCO3 shells can be used as a proxy for the SST in which the shells formed. Mg/Ca ratios have several other influencing factors other than temperature, such as vital effects, shell-cleaning, and postmortem and post-depositional dissolution effects, to name a few. Other influences aside, Mg/Ca ratios have successfully quantified the tropical cooling that occurred during the last glacial period. +Alkenones are long-chain, complex organic molecules produced by photosynthetic algae. They are temperature sensitive and can be extracted from marine sediments. Use of alkenones represents a more direct relationship between SST and algae and does not rely on knowing biotic and physical-chemical thermodynamic relationships needed in CaCO3 studies. Another advantage of using alkenones is that they are a product of photosynthesis, necessitating formation in the sunlight of the upper surface layers. As such, it better records near-surface SST. + +=== Bottom-water temperature === +The most commonly used proxy to infer deep-sea temperature history are the Mg/Ca ratios in benthic foraminifera and ostracodes. The temperatures inferred from the Mg/Ca ratios have confirmed an up to 3 °C cooling of the deep ocean during the late Pleistocene glacial periods. One notable study is that by Lear et al. [2002] who worked to calibrate bottom water temperature to Mg/Ca ratios in 9 locations covering a variety of depths from up to six different benthic foraminifera (depending on location). The authors found an equation calibrating bottom water temperature of Mg/Ca ratios that takes on an exponential form: + + + + + + M + g + + / + + C + a + + = + 0.867 + ± + 0.049 + ∗ + exp + ⁡ + ( + 0.109 + ± + 0.007 + ∗ + + B + W + T + + ) + : + + + {\displaystyle \mathrm {Mg/Ca} =0.867\pm 0.049*\exp(0.109\pm 0.007*\mathrm {BWT} ):} + + +where Mg/Ca is the Mg/Ca ratio found in the benthic foraminifera and BWT is the bottom water temperature. + +=== Sediment Records === +Sediment records have been used to make inferences about the past and predictions about the future, and has been used in Paleoceanography research since the 1930s. Modern time scale reconstructive research has advanced using sediment core-scanning methods. These methods have enabled research similar to that conducted with ice core records in Antarctica. These records can inform on the relative abundance of organisms present at a given time using paleoproductivity methods such as measuring the total diatom abundance. Records can also inform on historic weather patterns and ocean circulation such as Deschamps et al. described with their research into sediment records from the Chukchi-Alaskan and Canadian Beaufort Margins. + +=== Salinity === +Salinity is a more challenging quantity to infer from paleorecords. Deuterium excess in core records can provide a better inference of sea-surface salinity than oxygen isotopes, and certain species, such as diatoms, can provide a semiquantitative salinity record due to the relative abundances of diatoms that are limited to certain salinity regimes. There have been changes to global water cycle and the salinity balance of the oceans with the North Atlantic and becoming more saline and the sub-tropical Indian and pacific oceans becoming less so. With changes to the water cycle, there have also been variations with the vertical distribution of salt and haloclines. Large incursions of freshwater and changing salinity can also contribute to a reduction in sea ice extent. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Paleoceanography-1.md b/data/en.wikipedia.org/wiki/Paleoceanography-1.md new file mode 100644 index 000000000..4c401994c --- /dev/null +++ b/data/en.wikipedia.org/wiki/Paleoceanography-1.md @@ -0,0 +1,27 @@ +--- +title: "Paleoceanography" +chunk: 2/2 +source: "https://en.wikipedia.org/wiki/Paleoceanography" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:03.665799+00:00" +instance: "kb-cron" +--- + +=== Ocean circulation === +Several proxy methods have been used to infer past ocean circulation and changes to it. They include carbon isotope ratios, cadmium/calcium (Cd/Ca) ratios, protactinium/thorium isotopes (231Pa and 230Th), radiocarbon activity (δ14C), neodymium isotopes (143Nd and 144Nd), and sortable silt (fraction of deep-sea sediment between 10 and 63 μm). Carbon isotope and cadmium/calcium ratio proxies are used because variability in their ratios is due partly to changes in bottom-water chemistry, which is in turn related the source of deep-water formation. These ratios, however, are influenced by biological, ecological, and geochemical processes which complicate circulation inferences. +All proxies included are useful in inferring the behavior of the meridional overturning circulation. For example, McManus et al. [2004] used protactinium/thorium isotopes (231Pa and 230Th) to show that the Atlantic Meridional Overturning Circulation had been nearly (or completely) shut off during the last glacial period. 231Pa and 230Th are both formed from the radioactive decay of dissolved uranium in seawater, with 231Pa able to remain supported in the water column longer than 230Th: 231Pa has a residence time ~100–200 years while 230Th has one ~20–40 years. In today's Atlantic Ocean and current overturning circulation, 230Th transport to the Southern Ocean is minimal due to its short residence time, and 231Pa transport is high. This results in relatively low 231Pa / 230Th ratios found by McManus et al. [2004] in a core at 33N 57W, and a depth of 4.5 km. When the overturning circulation shuts down (as hypothesized) during glacial periods, the 231Pa / 230Th ratio becomes elevated due to the lack of removal of 231Pa to the Southern Ocean. McManus et al. [2004] also note a small raise in the 231Pa / 230Th ratio during the Younger Dryas event, another period in climate history thought to have experienced a weakening overturning circulation. + +=== Acidity, pH, and alkalinity === +Boron isotope ratios (δ11B) can be used to infer both recent as well as millennial time scale changes in the acidity, pH, and alkalinity of the ocean, which is mainly forced by atmospheric CO2 concentrations and bicarbonate ion concentration in the ocean. δ11B has been identified in corals from the southwestern Pacific to vary with ocean pH, and shows that climate variabilities such as the Pacific decadal oscillation (PDO) can modulate the impact of ocean acidification due to rising atmospheric CO2 concentrations. Another application of δ11B in plankton shells can be used as an indirect proxy for atmospheric CO2 concentrations over the past several million years. + +== See also == +Oceanography – Scientific study of the ocean +Paleoclimatology – Study of changes in ancient climate +Paleogeography – Study of physical geography of past landscapesPages displaying short descriptions of redirect targets +Paleothermometer — Study of ancient temperatures + +== References == + +== External links == + Media related to Paleoceanography at Wikimedia Commons \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Pelagic_sediment-0.md b/data/en.wikipedia.org/wiki/Pelagic_sediment-0.md new file mode 100644 index 000000000..77005edef --- /dev/null +++ b/data/en.wikipedia.org/wiki/Pelagic_sediment-0.md @@ -0,0 +1,50 @@ +--- +title: "Pelagic sediment" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Pelagic_sediment" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:04.868239+00:00" +instance: "kb-cron" +--- + +Pelagic sediment or pelagite is a fine-grained sediment that accumulates as the result of the settling of particles to the floor of the open ocean, far from land. These particles consist primarily of either the microscopic, calcareous or siliceous shells of phytoplankton or zooplankton; clay-size siliciclastic sediment; or some mixture of these, along with detritus (marine snow) included. Trace amounts of meteoric dust and variable amounts of volcanic ash also occur within pelagic sediments. +Based upon the composition of the ooze, there are three main types of pelagic sediments: siliceous oozes, calcareous oozes, and red clays. +The composition of pelagic sediments is controlled by three main factors. The first factor is the distance from major landmasses, which affects their dilution by terrigenous, or land-derived, sediment. The second factor is water depth, which affects the preservation of both siliceous and calcareous biogenic particles as they settle to the ocean bottom. The final factor is ocean fertility, which controls the amount of biogenic particles produced in surface waters. + + +== Oozes == +In case of marine sediments, ooze does not refer to a sediment's consistency, but to its composition, which directly reflects its origin. Ooze is pelagic sediment that consists of at least 30% of microscopic remains of either calcareous or siliceous planktonic debris organisms. The remainder typically consists almost entirely of clay minerals. As a result, the grain size of oozes is often bimodal with a well-defined biogenic silt- to sand-size fraction and siliciclastic clay-size fraction. Oozes can be defined by and classified according to the predominant organisms that compose them. For example, there are diatom, coccolith, foraminifera, globigerina, pteropod, and radiolarian oozes. Oozes are also classified and named according to their mineralogy, i.e. calcareous or siliceous oozes. Whatever their composition, all oozes accumulate extremely slowly, at no more than a few centimeters per millennium. +Calcareous ooze is ooze that is composed of at least 30% of the calcareous microscopic shells—also known as tests—of foraminifera, coccolithophores, and pteropods. This is the most common pelagic sediment by area, covering 48% of the world ocean's floor. This type of ooze accumulates on the ocean floor at depths above the carbonate compensation depth. It accumulates more rapidly than any other pelagic sediment type, with a rate that varies from 0.3–5 cm/1000 yr. +Siliceous ooze is ooze that is composed of at least 30% of the siliceous microscopic "shells" of plankton, such as diatoms and radiolaria. Siliceous oozes often contain lesser proportions of either sponge spicules, silicoflagellates or both. This type of ooze accumulates on the ocean floor at depths below the carbonate compensation depth. Its distribution is also limited to areas with high biological productivity, such as the polar oceans, and upwelling zones near the equator. The least common type of sediment, it covers only 15% of the ocean floor. It accumulates at a slower rate than calcareous ooze: 0.2–1 cm/1000 yr. + + +== Red and brown clays == + +Red clay, also known as either brown clay or pelagic clay, accumulates in the deepest and most remote areas of the ocean. It covers 38% of the ocean floor and accumulates more slowly than any other sediment type, at only 0.1–0.5 cm/1000 yr. Containing less than 30% biogenic material, it consists of sediment that remains after the dissolution of both calcareous and siliceous biogenic particles while they settled through the water column. These sediments consist of aeolian quartz, clay minerals, volcanic ash, subordinate residue of siliceous microfossils, and authigenic minerals such as zeolites, limonite and manganese oxides. The bulk of red clay consists of eolian dust. Accessory constituents found in red clay include meteorite dust, fish bones and teeth, whale ear bones, and manganese micro-nodules. +These pelagic sediments are typically bright red to chocolate brown in color. The color results from coatings of iron and manganese oxide on the sediment particles. In the absence of organic carbon, iron and manganese remain in their oxidized states and these clays remain brown after burial. When more deeply buried, brown clay may change into red clay due to the conversion of iron-hydroxides to hematite. +These sediments accumulate on the ocean floor within areas characterized by little planktonic production. The clays which comprise them were transported into the deep ocean in suspension, either in the air over the oceans or in surface waters. Both wind and ocean currents transported these sediments in suspension thousands of kilometers from their terrestrial source. As they were transported, the finer clays may have stayed in suspension for a hundred years or more within the water column before they settled to the ocean bottom. The settling of this clay-size sediment occurred primarily by the formation of clay aggregates by flocculation and by their incorporation into fecal pellets by pelagic organisms. + + +== Distribution and average thickness of marine sediments == + + +== Classification of marine sediments by source of particles == + + +== See also == +Chalk +Diatomaceous earth +Marine geology +Petrological Database of the Ocean Floor +Radiolarite +SedDB, online database for sediment geochemistry +Biogenous ooze + + +== Footnotes == + + +== External links == +http://www.odp.usyd.edu.au +Total Sediment Thickness of the World's Oceans and Marginal Seas, Version 2 \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Pelagic_zone-0.md b/data/en.wikipedia.org/wiki/Pelagic_zone-0.md new file mode 100644 index 000000000..3fa948750 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Pelagic_zone-0.md @@ -0,0 +1,42 @@ +--- +title: "Pelagic zone" +chunk: 1/3 +source: "https://en.wikipedia.org/wiki/Pelagic_zone" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:06.087361+00:00" +instance: "kb-cron" +--- + +The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word pelagic is derived from Ancient Greek πέλαγος (pélagos) 'open sea'. The pelagic zone can be thought of as an imaginary cylinder or water column between the surface of the sea and the bottom. +Conditions in the water column change with depth: pressure increases; temperature and light decrease; salinity, oxygen, micronutrients (such as iron, magnesium and calcium) all change. In a manner analogous to stratification in the Earth's atmosphere, the water column can be divided vertically into up to five different layers (illustrated in the diagram), with the number of layers depending on the depth of the water. +Marine life is affected by bathymetry (underwater topography) such as the seafloor, shoreline, or a submarine seamount, as well as by proximity to the boundary between the ocean and the atmosphere at the ocean surface, which brings light for photosynthesis, predation from above, and wind stirring up waves and setting currents in motion. The pelagic zone refers to the open, free waters away from the shore, where marine life can swim freely in any direction unhindered by topographical constraints. +The oceanic zone is the deep open ocean beyond the continental shelf, which contrasts with the inshore waters near the coast, such as in estuaries or on the continental shelf. Waters in the oceanic zone plunge to the depths of the abyssopelagic and further to the hadopelagic. Coastal waters are generally the relatively shallow epipelagic. Altogether, the pelagic zone occupies 1.33 billion km3 (320 million cu mi), with a mean depth of 3.68 km (2.29 mi) and maximum depth of 11 km (6.8 mi). Pelagic life decreases as depth increases. +The pelagic zone also contrasts with the benthic and demersal zones at the bottom of the sea. The benthic zone is the ecological region at the very bottom, including the sediment surface and some subsurface layers. Marine organisms such as clams and crabs living in this zone are called benthos. Just above the benthic zone is the demersal zone. Demersal fish can be divided into benthic fish, which are denser than water and rest on the bottom, and benthopelagic fish, which swim just above the bottom. Demersal fish are also known as bottom feeders and groundfish. + +== Depth and layers == + +The pelagic zone is subdivided into five vertical regions. From the top down, these are: + +=== Epipelagic (sunlight) === + +The illuminated zone at the surface of the sea, and the only zone with sufficient light for photosynthesis. This zone is just above the continental shelf and has the lowest atmospheric pressure on the oceans surface, at 1 atm for every 10 meters. Nearly all primary production in the ocean occurs here, and about 90% marine life is concentrated in this zone, including: plankton, floating seaweed, jellyfish, tuna, whales, sharks, dolphins, and many more diverse species. + +=== Mesopelagic (twilight) === + +The thermocline serves as the boundary from the warmer top zone to the much colder mesopelagic zone, which is also located right under the continental shelf. This zone contains a very trace amount of sunlight and has a pressure of about 20 - 100 atm. A variety of creatures live in this zone, including species of swordfish, squid, wolffish and some species of cuttlefish. Many organisms living here have evolved adaptations, such as bioluminescence, due to the lack of sunlight. Some mesopelagic creatures rise to the epipelagic zone at night to feed. Heterotrophic bacteria are among the more abundant organisms in this zone, and they primarily feed and break down falling matter from the upper zone. + +=== Bathypelagic (midnight) === + +The name stems from Ancient Greek βαθύς 'deep'. In this zone, the environment is pitch black at this depth and contains no trace of sunlight, apart from occasional bioluminescent organisms, such as anglerfish. The temperature and salinity of this zone is stable. No plants live here. Most creatures survive on detritus known as "marine snow" falling from the zones above or, like the marine hatchetfish, by preying on other inhabitants of this zone. + +=== Abyssopelagic (abyssal zone) === + +The name is derived from Ancient Greek ἄβυσσος 'bottomless'. The ocean floor is next to this zone, and it forms volcanos, mountains, and vents from the movement of the tectonic plates. Among the very few creatures living in the cold temperatures, high pressures and complete darkness there are several species of squid; echinoderms including the basket star, swimming cucumber, and the sea pig; and marine arthropods including the sea spider. Many species at these depths are transparent and eyeless. + +=== Hadopelagic (hadal zone) === + +The name is derived from the realm of Hades, the Greek underworld. This is the deepest part of the ocean at more than 6,000 m (20,000 ft) . Such depths are generally located in trenches.This zone contains 13 short narrow troughs and 33 trenches. The deepest trenches stretch to 10,924 m deep, while average trenches are usually 5 - 10 kilometers deep. This zone can have an atmospheric pressure of 1,100 atm. In this zone, there is an increase in temperature from adiabatic heating. Very few creatures live in this zone. Some of the recorded species are coelenterate, polychaetas, amphipods, echinoderms, and mollusks. + +== Pelagic ecosystem == +The pelagic ecosystem is based on phytoplankton. Phytoplankton manufacture their own food using a process of photosynthesis. Because they need sunlight, they inhabit the upper, sunlit epipelagic zone, which includes the coastal or neritic zone. Biodiversity diminishes markedly in the deeper zones below the epipelagic zone as dissolved oxygen diminishes, water pressure increases, temperatures become colder, food sources become scarce, and light diminishes and finally disappears. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Pelagic_zone-1.md b/data/en.wikipedia.org/wiki/Pelagic_zone-1.md new file mode 100644 index 000000000..895e900ed --- /dev/null +++ b/data/en.wikipedia.org/wiki/Pelagic_zone-1.md @@ -0,0 +1,46 @@ +--- +title: "Pelagic zone" +chunk: 2/3 +source: "https://en.wikipedia.org/wiki/Pelagic_zone" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:06.087361+00:00" +instance: "kb-cron" +--- + +=== Pelagic invertebrates === +Some examples of pelagic invertebrates include krill, copepods, jellyfish, decapod larvae, hyperiid amphipods, rotifers and cladocerans. +Thorson's rule states that benthic marine invertebrates at low latitudes tend to produce large numbers of eggs developing to widely dispersing pelagic larvae, whereas at high latitudes such organisms tend to produce fewer and larger lecithotrophic (yolk-feeding) eggs and larger offspring. + +=== Pelagic fish === + +Pelagic fish live in the water column of coastal, ocean, and lake waters, but not on or near the bottom of the sea or the lake. They can be contrasted with demersal fish, which do live on or near the bottom, and coral reef fish. +Pelagic fish are often migratory forage fish, which feed on plankton, and the larger predatory fish that follow and feed on the forage fish. Migratory fish come up to the more dense prey areas of the pelagic zones to feed, and then descend at night to avoid predators. Examples of migratory forage fish are herring, anchovies, capelin, and menhaden. Examples of larger pelagic fish which prey on the forage fish are billfish, tuna, and oceanic sharks. + +=== Pelagic reptiles === +Hydrophis platurus, the yellow-bellied sea snake, is the only one of the 65 species of marine snakes to spend its entire life in the pelagic zone. It bears live young at sea and is helpless on land. The species sometimes forms aggregations of thousands along slicks in surface waters. The yellow-bellied sea snake is the world's most widely distributed snake species. +Many species of sea turtles spend the first years of their lives in the pelagic zone, moving closer to shore as they reach maturity. + +=== Pelagic birds === + +Pelagic birds, also called oceanic birds or seabirds, live on open seas and oceans rather than inland or around more restricted waters such as rivers and lakes. Many of these birds have very long wings which give them the ability to fly for long periods of time. Some pelagic birds dive deep into the water to catch prey. Pelagic birds feed on planktonic crustaceans, squid and forage fish. Examples are the Atlantic puffin, macaroni penguins, sooty terns, razorbills, shearwaters, and Procellariiformes such as the albatross, Procellariidae and petrels. + +== Food web == + +Compared to terrestrial environments, marine environments have biomass pyramids which are inverted at the base. In particular, the biomass of consumers (copepods, krill, shrimp, forage fish) is larger than the biomass of primary producers. This happens because the ocean's primary producers are tiny phytoplankton which tend to have a fast life history (are r-strategists that grow and reproduce rapidly) so a small mass can have a fast rate of primary production. In contrast, terrestrial primary producers, such as mature forests, often have a slow life history (are K-strategists that grow and reproduce slowly) so a much larger mass is needed to achieve the same rate of primary production. +Because of this inversion, it is the zooplankton that make up most of the marine animal biomass. As primary consumers, they are the crucial link between the primary producers (mainly (phytoplankton) and the rest of the marine food web (secondary consumers). +If phytoplankton dies before it is eaten, it descends from the euphotic zone down through the pelagic water column as part of the marine snow, and settles into the depths of sea. In this way, phytoplankton sequester about 2 billion tons of carbon dioxide in the ocean each year, causing the ocean to become a sink of carbon dioxide holding about 90% of all sequestered carbon. +In 2010 researchers found whales carry nutrients from the depths of the ocean back up the pelagic water column to the surface using a process they called the whale pump. Whales feed at deeper levels in the ocean where krill is found, but return regularly to the surface to breathe. There whales defecate a liquid rich in nitrogen and iron. Instead of sinking, the liquid stays at the surface where phytoplankton consume it. In the Gulf of Maine the whale pump provides more nitrogen than the rivers. + +== Observing and sampling methods == +Exploring and learning more about the ocean is a main factor to ocean resource management, which sustainably manages how much and how fast we use the ocean’s resources. Ocean exploration also observes patterns in the ocean’s weather and climate, and the means by which they were affected. With this data, researchers are better able to understand and see natural phenomena such as earthquakes and tsunamis and react accordingly. Scientists and researchers have developed many methods to sample the ocean biome and pelagic fish. + +=== Trawling === + +This method can be used from a boat to capture organisms like deep pelagic fish. A mesh net is dragged at different depths to collect for recording the captured organisms. This method can produce large amounts of specimen. However it is costly, time consuming, and mostly used by research groups with a lot of support and funding. There are also many fish that are able to out swim the net, which limits data. + +=== Active acoustics === + +This method analyzes fish that are detected by sound pulses that are emitted from the surface, where the pelagic fish's biomass in the reflected signal is analyzed. This method of sampling cannot reach deep depths in the ocean. The pulses cover a broad area of the ocean and cause little harm or distress. The received data from this method is complicated to interpret due to specific variations of swim bladders in fish, such as having little gas or not having a swim bladder. + +=== Remotely operated vehicles === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Pelagic_zone-2.md b/data/en.wikipedia.org/wiki/Pelagic_zone-2.md new file mode 100644 index 000000000..70ffb87b4 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Pelagic_zone-2.md @@ -0,0 +1,22 @@ +--- +title: "Pelagic zone" +chunk: 3/3 +source: "https://en.wikipedia.org/wiki/Pelagic_zone" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:06.087361+00:00" +instance: "kb-cron" +--- + +Remotely operated vehicles (ROVs) are used for sampling and examining the deep pelagic sea in ways that other techniques cannot match. An ROV is an unoccupied machine equipped with lights, cameras, sensors, or arms, which allows for detailed and live observations of its surroundings and of pelagic organisms. It can conduct experiments and collect samples. These machine are limited in ground coverage, as well as expensive and hard to control, so few research groups use them. They can also be loud, bright, and big, causing organisms to avoid them. + +=== Additional methods === +Some other sampling and observation methods are: predator gut examinations, analysis of environmental DNA, organisms that get washed up on shore from upwelling, analyzing sediments cores, and pelagic longline fishing. + +== References == + +== Further reading == +Ryan, Paddy "Deep-sea creatures" Te Ara – the Encyclopedia of New Zealand, updated 21 September 2007 +"Pelagic-zone (oceanography)" Encyclopædia Britannica Online. 21 March 2009. +Grantham HS, Game ET, Lombard AT, et al. (2011) "Accommodating Dynamic Oceanographic Processes and Pelagic Biodiversity in Marine Conservation Planning" PLOS One 6(2): e16552. doi:10.1371/journal.pone.0016552. +Wrobel, David; Mills, Claudia (2003) [1998]. Pacific Coast Pelagic Invertebrates: A Guide to the Common Gelatinous Animals. Sea Challengers and Monterey Bay Aquarium. ISBN 0-930118-23-5. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Photic_zone-0.md b/data/en.wikipedia.org/wiki/Photic_zone-0.md new file mode 100644 index 000000000..680b962e8 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Photic_zone-0.md @@ -0,0 +1,27 @@ +--- +title: "Photic zone" +chunk: 1/3 +source: "https://en.wikipedia.org/wiki/Photic_zone" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:08.714083+00:00" +instance: "kb-cron" +--- + +The photic zone (or euphotic zone, epipelagic zone, or sunlight zone) is the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis. It undergoes a series of physical, chemical, and biological processes that supply nutrients into the upper water column. The photic zone is home to the majority of aquatic life due to the activity (primary production) of the phytoplankton. The thicknesses of the photic and euphotic zones vary with the intensity of sunlight as a function of season and latitude and with the degree of water turbidity. The bottommost, or aphotic, zone is the region of perpetual darkness that lies beneath the photic zone and includes most of the ocean waters. + +== Photosynthesis in photic zone == +In the photic zone, the photosynthesis rate exceeds the respiration rate. This is due to the abundant solar energy which is used as an energy source for photosynthesis by primary producers such as phytoplankton. These phytoplankton grow extremely quickly because of sunlight's heavy influence, enabling it to be produced at a fast rate. In fact, ninety five percent of photosynthesis in the ocean occurs in the photic zone. Therefore, if we go deeper, beyond the photic zone, such as into the compensation point, there is little to no phytoplankton, because of insufficient sunlight. The zone which extends from the base of the euphotic zone to the aphotic zone is sometimes called the dysphotic zone. + +== Life in the photic zone == + +Ninety percent of marine life lives in the photic zone, which is approximately two hundred meters deep. This includes phytoplankton (plants), including dinoflagellates, diatoms, cyanobacteria, coccolithophores, and cryptomonads. It also includes zooplankton, the consumers in the photic zone. There are carnivorous meat eaters and herbivorous plant eaters. Next, copepods are the small crustaceans distributed everywhere in the photic zone. Finally, there are nekton (animals that can propel themselves, like fish, squids, and crabs), which are the largest and the most obvious animals in the photic zone, but their quantity is the smallest among all the groups. Phytoplankton are microscopic plants living suspended in the water column that have little or no means of motility. They are primary producers that use solar energy as a food source. +"Detritivores and scavengers are rare in the photic zone. Microbial decomposition of dead organisms begins here and continues once the bodies sink to the aphotic zone where they form the most important source of nutrients for deep sea organisms." The depth of the photic zone depends on the transparency of the water. If the water is very clear, the photic zone can become very deep. If it is very murky, it can be only fifty feet (fifteen meters) deep. +Animals within the photic zone use the cycle of light and dark as an important environmental signal, migration is directly linked to this fact, fishes use the concept of dusk and dawn when its time to migrate, the photic zone resembles this concept providing a sense of time. These animals can be herrings and sardines and other fishes that consistently live within the photic zone. + +== Nutrient uptake in the photic zone == +Due to biological uptake, the photic zone has relatively low levels of nutrient concentrations. As a result, phytoplankton doesn't receive enough nutrients when there is high water-column stability. The spatial distribution of organisms can be controlled by a number of factors. Physical factors include: temperature, hydrostatic pressure, turbulent mixing such as the upward turbulent flux of inorganic nitrogen across the nutricline. Chemical factors include oxygen and trace elements. Biological factors include grazing and migrations. Upwelling carries nutrients from the deep waters into the photic zone, strengthening phytoplankton growth. The remixing and upwelling eventually bring nutrient-rich wastes back into the photic zone. The Ekman transport additionally brings more nutrients to the photic zone. Nutrient pulse frequency affects the phytoplankton competition. Photosynthesis produces more of it. Being the first link in the food chain, what happens to phytoplankton creates a rippling effect for other species. Besides phytoplankton, many other animals also live in this zone and utilize these nutrients. The majority of ocean life occurs in the photic zone, the smallest ocean zone by water volume. The photic zone, although small, has a large impact on those who reside in it. + +== Photic zone depth == + +The depth is, by definition, where radiation is degraded down to 1% of its surface strength. Accordingly, its thickness depends on the extent of light attenuation in the water column. As incoming light at the surface can vary widely, this says little about the net growth of phytoplankton. Typical euphotic depths vary from only a few centimetres in highly turbid eutrophic lakes, to around 200 meters in the open ocean. It also varies with seasonal changes in turbidity, which can be strongly driven by phytoplankton concentrations, such that the depth of the photic zone often decreases as primary production increases. Moreover, the respiration rate is actually greater than the photosynthesis rate. The reason why phytoplankton production is so important is because it plays a prominent role when interwoven with other food webs. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Photic_zone-1.md b/data/en.wikipedia.org/wiki/Photic_zone-1.md new file mode 100644 index 000000000..375685c39 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Photic_zone-1.md @@ -0,0 +1,25 @@ +--- +title: "Photic zone" +chunk: 2/3 +source: "https://en.wikipedia.org/wiki/Photic_zone" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:08.714083+00:00" +instance: "kb-cron" +--- + +== Photic zone darkening == +A study done by the University of Pittsburgh found that in recent years there was a significant darkening of the photic zone between the years 2003 and 2022 with the ocean becoming more green, especially in low-latitude oceans. Though researchers are uncertain of the cause, it's been widely proposed this is due to Climate change, there are conflicted conclusions on whether the raised temperatures and increased carbon dioxide emissions lead to a decrease or an increase of primary productivity. Though this change in ocean color was predicted through modeling in 2010, it was not confirmed until new satellite-based technologies made it possible in 2023. +Though climate change may be the root cause, researchers have formulated theories for what specifically is causing this greening and consequential change in the photic zone depth, including unbalanced Phytoplankton, zooplankton, algae, and other microorganism populations; increase in Ocean stratification; and changes to the ocean current circulation. Combined, these changes may also increase the amount of Colored dissolved organic matter which would account for the ocean greening. Researchers are conflicted on whether runoff from land has any significant effect on the greening with some arguing it is too widespread for runoff to be a leading factor. + +== Light attenuation == + +Most of the solar energy reaching the Earth is in the range of visible light, with wavelengths between about 400–700 nm. Each colour of visible light has a unique wavelength, and together they make up white light. The shortest wavelengths are on the violet and ultraviolet end of the spectrum, while the longest wavelengths are at the red and infrared end. In between, the colours of the visible spectrum comprise the familiar “ROYGBIV”; red, orange, yellow, green, blue, indigo, and violet. +Water is very effective at absorbing incoming light, so the amount of light penetrating the ocean declines rapidly (is attenuated) with depth. At one metre depth only 45% of the solar energy that falls on the ocean surface remains. At 10 metres depth only 16% of the light is still present, and only 1% of the original light is left at 100 metres. No light penetrates beyond 1000 metres. +In addition to overall attenuation, the oceans absorb the different wavelengths of light at different rates. The wavelengths at the extreme ends of the visible spectrum are attenuated faster than those wavelengths in the middle. Longer wavelengths are absorbed first; red is absorbed in the upper 10 metres, orange by about 40 metres, and yellow disappears before 100 metres. Shorter wavelengths penetrate further, with blue and green light reaching the deepest depths. + +This is why things appear blue underwater. How colours are perceived by the eye depends on the wavelengths of light that are received by the eye. An object appears red to the eye because it reflects red light and absorbs other colours. So the only colour reaching the eye is red. Blue is the only colour of light available at depth underwater, so it is the only colour that can be reflected back to the eye, and everything has a blue tinge under water. A red object at depth will not appear red to us because there is no red light available to reflect off of the object. Objects in water will only appear as their real colours near the surface where all wavelengths of light are still available, or if the other wavelengths of light are provided artificially, such as by illuminating the object with a dive light. +Water in the open ocean appears clear and blue because it contains much less particulate matter, such as phytoplankton or other suspended particles, and the clearer the water, the deeper the light penetration. Blue light penetrates deeply and is scattered by the water molecules, while all other colours are absorbed; thus the water appears blue. On the other hand, coastal water often appears greenish. Coastal water contains much more suspended silt and algae and microscopic organisms than the open ocean. Many of these organisms, such as phytoplankton, absorb light in the blue and red range through their photosynthetic pigments, leaving green as the dominant wavelength of reflected light. Therefore the higher the phytoplankton concentration in water, the greener it appears. Small silt particles may also absorb blue light, further shifting the colour of water away from blue when there are high concentrations of suspended particles. +The ocean can be divided into depth layers depending on the amount of light penetration, as discussed in pelagic zone. The upper 200 metres is referred to as the photic or euphotic zone. This represents the region where enough light can penetrate to support photosynthesis, and it corresponds to the epipelagic zone. From 200 to 1000 metres lies the dysphotic zone, or the twilight zone (corresponding with the mesopelagic zone). There is still some light at these depths, but not enough to support photosynthesis. Below 1000 metres is the aphotic (or midnight) zone, where no light penetrates. This region includes the majority of the ocean volume, which exists in complete darkness. + +== Paleoclimatology == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Photic_zone-2.md b/data/en.wikipedia.org/wiki/Photic_zone-2.md new file mode 100644 index 000000000..e946c07d3 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Photic_zone-2.md @@ -0,0 +1,29 @@ +--- +title: "Photic zone" +chunk: 3/3 +source: "https://en.wikipedia.org/wiki/Photic_zone" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:08.714083+00:00" +instance: "kb-cron" +--- + +Phytoplankton are unicellular microorganisms which form the base of the ocean food chains. They are dominated by diatoms, which grow silicate shells called frustules. When diatoms die their shells can settle on the seafloor and become microfossils. Over time, these microfossils become buried as opal deposits in the marine sediment. Paleoclimatology is the study of past climates. Proxy data is used in order to relate elements collected in modern-day sedimentary samples to climatic and oceanic conditions in the past. Paleoclimate proxies refer to preserved or fossilized physical markers which serve as substitutes for direct meteorological or ocean measurements. An example of proxies is the use of diatom isotope records of δ13C, δ18O, δ30Si (δ13Cdiatom, δ18Odiatom, and δ30Sidiatom). In 2015, Swann and Snelling used these isotope records to document historic changes in the photic zone conditions of the north-west Pacific Ocean, including nutrient supply and the efficiency of the soft-tissue biological pump, from the modern day back to marine isotope stage 5e, which coincides with the last interglacial period. Peaks in opal productivity in the marine isotope stage are associated with the breakdown of the regional halocline stratification and increased nutrient supply to the photic zone. + +The initial development of the halocline and stratified water column has been attributed to the onset of major Northern Hemisphere glaciation at 2.73 Ma, which increased the flux of freshwater to the region, via increased monsoonal rainfall and/or glacial meltwater, and sea surface temperatures. The decrease of abyssal water upwelling associated with this may have contributed to the establishment of globally cooler conditions and the expansion of glaciers across the Northern Hemisphere from 2.73 Ma. While the halocline appears to have prevailed through the late Pliocene and early Quaternary glacial–interglacial cycles, other studies have shown that the stratification boundary may have broken down in the late Quaternary at glacial terminations and during the early part of interglacials. + +== Phytoplankton == +An increase in the amount of phytoplankton also creates an increase in zooplankton, the zooplankton feeds on the phytoplankton as they are at the bottom of the food chain. +Phytoplankton are largely restricted to the photic zone, as their growth is primarily dependent upon photosynthesis. This results in phytoplankton primarily occupying the uppermost 50-100 m of the water column. However, diatoms can survive after sinking, and cells have been observed alive thousands of meters down in the water column. They are generally not actively photosynthesizing at these depths due to lack of light availability, but are able to persist in a resting stage. Phytoplankton growth within the photic zone can also be influenced by terrestrial factors, like the weathering of crustal rocks or nutrients from the respiration of plants and animals on land that are carried to the ocean via runoff or riverine input. +Phytoplankton move within the photic zone, and many sink over time, with an average sinking rate of 150 m per day. Light access can affect phytoplankton sinking rates through its involvement in photosynthetic activity and energy regulation. Phytoplankton utilize light energy for growth, and where that energy is allocated has been found to change as light availability increases. In areas of higher light, phytoplankton can invest energy in storage compounds, such as lipids. Lipids have a lower density and are involved in buoyancy regulation. With more lipids present, the cellular weight decreases, enabling the sinking rate of the phytoplankton to slow. While migration is more common in zooplankton, some motile phytoplankton will engage in diel vertical migration (DVM), where they migrate upwards in the water column during the day to maximize photosynthetic activity, and descend in dark hours. + +Phytoplankton play a central role in the biological carbon pump (BCP). They fix CO2 at the surface, and through sinking, transport this carbon out of the photic zone. About 10–20% of this carbon sinks below the photic zone, and less than 1% reaches the seafloor. +Dimethylsulfide loss within the photic zone is controlled by microbial uptake and photochemical degradation. + +== See also == +Aquatic photosynthesis +Electromagnetic absorption by water +Epipelagic fish +Mesophotic coral reef + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Physics_arXiv_Blog-0.md b/data/en.wikipedia.org/wiki/Physics_arXiv_Blog-0.md new file mode 100644 index 000000000..72f6ea7ac --- /dev/null +++ b/data/en.wikipedia.org/wiki/Physics_arXiv_Blog-0.md @@ -0,0 +1,25 @@ +--- +title: "Physics arXiv Blog" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Physics_arXiv_Blog" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:18.508294+00:00" +instance: "kb-cron" +--- + +The Physics arXiv Blog aims to offer an alternative view of new ideas in science. It is based on, although independent of, the arXiv pre-print repository run by the Cornell University. Started in 2007, in 2009 it was hosted by the MIT Technology Review. In 2013, it was moved to the platform Medium. In 2015, it moved back to the MIT Technology Review. +The Physics arXiv Blog has been said to offer “the best physics coverage around" by the Wired journal in May of 2008. It was included among the "Five great physics blogs" by The Guardian. + + +== Publication model == + +Content appears to be crowd sourced from within the physics community. Similar to The Economist, articles seem to lack specific author bylines. + + +== Notes == + + +== External links == +The Physics arXiv Blog official webpage +The Physics arXiv Blog webpage on Facebook \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Plankton-0.md b/data/en.wikipedia.org/wiki/Plankton-0.md new file mode 100644 index 000000000..3886ed581 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Plankton-0.md @@ -0,0 +1,24 @@ +--- +title: "Plankton" +chunk: 1/7 +source: "https://en.wikipedia.org/wiki/Plankton" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:10.175954+00:00" +instance: "kb-cron" +--- + +Plankton (from the Greek planktos, meaning "drifter" or "wanderer") are organisms that drift in water (or air) but are unable to actively propel themselves against currents (or wind). Marine plankton include drifting organisms that inhabit the saltwater of oceans and the brackish waters of estuaries. Freshwater plankton are similar to marine plankton, but are found in lakes and rivers. An individual plankton organism in the plankton is called a plankter. +Plankton includes organisms from species across all the major biological kingdoms, ranging in size from the microscopic (such as bacteria, archaea, protozoa and microscopic algae and fungi) to larger organisms (such as jellyfish and ctenophores). This is because plankton are defined by their ecological niche and level of motility rather than by any phylogenetic or taxonomic classification. The plankton category differentiates organisms from those that can swim against a current, called nekton, and those that live on the deep sea floor, called benthos. Organisms that float on or near the water's surface are called neuston. Neuston that drift as water currents or wind take them, and lack the swimming ability to counter this, form a special subgroup of plankton. Mostly plankton just drift where currents take them, though some, like jellyfish, swim slowly but not fast enough to generally overcome the influence of currents. +Plankton are a diverse group, which traditionally were divided into two trophic (feeding) groups: phytoplankton and zooplankton. Phytoplankton (autotrophic plant-like producers such as diatoms and cyanobacteria) synthesize their own food, while zooplankton (heterotrophic consumers such as radiolarians and copepods) get their food like animals do, by predating and eating other life forms. In recent years research has shown unicellular plankton often combine photosynthesis and ingestion within their single cell, such as Mesodinium and many dinoflagellates, which means they can act in both the above feeding modes. This has resulted in the recognition of a third group, called the mixoplankton. A fourth group are planktonic decomposers, which include microscopic fungi (mycoplankton and mobile zoospores), bacterioplankton and aquatic viruses. These decomposers recycle organic nutrients so they can be used again as food by other plankton through processes such as the mycoloop, microbial loop and viral shunt. +Microscopic plankton, smaller than about one millimetre in size, play crucial roles maintaining the health and balance of aquatic ecosystems. Phytoplankton (generally microscopic) are responsible for roughly half of Earth's oxygen production through photosynthesis and play a major role in carbon sequestration. Together, these largely unseen microplankton drive primary production, support local food webs and cycle nutrients. Marine microorganisms have been variously estimated to make up between 70 and 90 percent of the ocean biomass. They influence global biogeochemical processes and largely drive the biological pump (which removes carbon dioxide from the atmosphere and exports carbon to deeper waters). Altogether, plankton form the foundation of the marine food web, supporting many commercially important species from forage fish to baleen whales. Although plankton are usually thought of as inhabiting water, there are also airborne versions that live part of their lives drifting in the atmosphere. These aeroplankton can include plant spores, pollen and wind-scattered seeds. They can also include microorganisms swept into the air from terrestrial dust storms and oceanic plankton swept into the air by sea spray. + +== Overview == + +Apart from aeroplankton, plankton inhabits oceans, seas, estuaries, rivers, lakes and ponds. Local abundance varies horizontally, vertically and seasonally. The primary cause of this variability is the availability of light. Nearly all plankton ecosystems are driven by the input of solar energy (but see chemosynthesis), confining nearly all primary production to surface waters, and to geographical regions and seasons having abundant light. +A secondary variable is nutrient availability. The amount and distribution of plankton depends on available nutrients, the state of water and a large amount of other plankton. The local distribution of plankton can be affected by wind-driven Langmuir circulation and the biological effects of this physical process. Although large areas of the tropical and sub-tropical oceans have abundant light, they experience relatively low primary production because they offer limited nutrients such as nitrate, phosphate and silicate. This results from large-scale ocean circulation and water column stratification. In such regions, primary production usually occurs at greater depth, although at a reduced level (because of reduced light). +While plankton are most abundant in surface waters, they live throughout the water column. At depths where no primary production occurs, zooplankton and bacterioplankton instead consume organic material sinking from more productive surface waters above. This flux of sinking material, so-called marine snow, can be especially high following the termination of spring blooms. +Despite significant macronutrient concentrations, some ocean regions are unproductive (so-called HNLC regions). The micronutrient iron is deficient in these regions, and adding it can lead to the formation of phytoplankton algal blooms. Iron primarily reaches the ocean through the deposition of dust on the sea surface. Paradoxically, oceanic areas adjacent to unproductive, arid land thus typically have abundant phytoplankton (e.g., the eastern Atlantic Ocean, where trade winds bring dust from the Sahara Desert in north Africa). +Within the plankton, holoplankton spend their entire life cycle as plankton (e.g. most algae, copepods, salps, and some jellyfish). By contrast, meroplankton are only planktic for part of their lives (usually the larval stage), and then graduate to either a nektic (swimming) or benthic (sea floor) existence. Examples of meroplankton include the larvae of sea urchins, starfish, crustaceans, marine worms, and most fish. + +=== Microscopic plankton === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Plankton-1.md b/data/en.wikipedia.org/wiki/Plankton-1.md new file mode 100644 index 000000000..35b1a615a --- /dev/null +++ b/data/en.wikipedia.org/wiki/Plankton-1.md @@ -0,0 +1,38 @@ +--- +title: "Plankton" +chunk: 2/7 +source: "https://en.wikipedia.org/wiki/Plankton" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:10.175954+00:00" +instance: "kb-cron" +--- + +Plankton is mostly made up of planktonic microorganisms less than one millimetre across, most visible only through a microscope. Microorganisms have been variously estimated to make up about 70%, or about 90%, of the total ocean biomass. Taken together they form the marine microbiome. Over billions of years this microbiome has evolved many life styles and adaptations and come to participate in the global cycling of almost all chemical elements. +Microplankton are ecological linchpins in the marine food web. They are crucial to nutrient recycling in the way they act as decomposers. They are also responsible for nearly all photosynthesis that occurs in the ocean, as well as the cycling of carbon, nitrogen, phosphorus and other nutrients and trace elements. Microplankton sequesters large amounts of carbon and produce much of the world's oxygen. +It is estimated marine viruses kill 20% of ocean microplankton biomass every day. Viruses are the main agents responsible for the rapid destruction of harmful algal blooms which often kill other marine life. The number of viruses in the plankton decreases further offshore and deeper into the water, where there are fewer host organisms. + +=== Terminology === + +The name plankton was coined by German marine biologist Victor Hensen in 1887 from shortening the word halyplankton from Greek ἅλς háls "sea" and πλανάομαι planáomai "(I) drift" or "(I) wander". Some forms of plankton are capable of independent vertically movement, and can swim hundreds of meters vertically in a single day (a behavior called diel vertical migration). However their horizontal position is primarily determined by the surrounding water movement, so plankton typically flow with the ocean currents. This is in contrast to nekton organisms, such as fish, squid and marine mammals, which can swim against the ambient flow and control their position in the environment. +The study of plankton is termed planktology and a planktonic individual is referred to as a plankter. The adjective planktonic is widely used in both the scientific and popular literature, and is a generally accepted term. However, from the standpoint of prescriptive grammar, the less-commonly used planktic is more strictly the correct adjective. When deriving English words from their Greek or Latin roots, the gender-specific ending (in this case, "-on" which indicates the word is neuter) is normally dropped, using only the root of the word in the derivation. + +== By habitat == + +=== Aeroplankton === + +Aeroplankton are tiny lifeforms that float and drift in the air, carried by the current of the wind; they are the atmospheric analogue to oceanic plankton. Most of the living things that make up aeroplankton are very small to microscopic in size, and many can be difficult to identify because of their tiny size. Scientists can collect them for study in traps and sweep nets from aircraft, kites or balloons. Aeroplankton is made up of numerous microbes, including viruses, about 1000 different species of bacteria, around 40,000 varieties of fungi, and hundreds of species of protists, algae, mosses and liverworts that live some part of their life cycle as aeroplankton, often as spores, pollen, and wind-scattered seeds. Additionally, peripatetic microorganisms are swept into the air from terrestrial dust storms, and an even larger amount of airborne marine microorganisms are propelled high into the atmosphere in sea spray. Aeroplankton deposits hundreds of millions of airborne viruses and tens of millions of bacteria every day on every square meter around the planet. This means similar mixes of microscopic plankton taxon can be found in open bodies of water around the world. +The sea surface microlayer, compared to the sub-surface waters, contains elevated concentration of bacteria and viruses. These materials can be transferred from the sea-surface to the atmosphere in the form of wind-generated aqueous aerosols due to their high vapour tension and a process known as volatilisation. When airborne, these microbes can be transported long distances to coastal regions. If they hit land they can have an effect on animal, vegetation and human health. Marine aerosols that contain viruses can travel hundreds of kilometers from their source and remain in liquid form as long as the humidity is high enough (over 70%). These aerosols are able to remain suspended in the atmosphere for about 31 days. Evidence suggests that bacteria can remain viable after being transported inland through aerosols. Some reached as far as 200 meters at 30 meters above sea level. The process which transfers this material to the atmosphere causes further enrichment in both bacteria and viruses in comparison to either the SML or sub-surface waters (up to three orders of magnitude in some locations). + +=== Freshwater plankton === +Freshwater plankton parallel marine plankton (below), but are found inland in the freshwaters of lakes and rivers. + +=== Geoplankton === + +Many animals live in terrestrial environments by thriving in transient often microscopic bodies of water and moisture, these include rotifers and gastrotrichs which lay resilient eggs capable of surviving years in dry environments, and some of which can go dormant themselves. Nematodes are usually microscopic with this lifestyle. Water bears, despite only having lifespans of a few months, famously can enter suspended animation during dry or hostile conditions and survive for decades. This allows them to be ubiquitous in terrestrial environments despite needing water to grow and reproduce. Many microscopic crustacean groups like copepods and amphipods (of which sandhoppers are members) and seed shrimp are known to go dormant when dry and live in transient bodies of water too + +=== Marine plankton === + +Marine plankton includes marine protists (algae and protozoa), drifting and floating animals (particularly microanimals), marine prokaryotes (bacteria and archaea), and marine viruses that inhabit the saltwater of oceans and the brackish waters of estuaries. + +==== At the ocean surface ==== \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Plankton-2.md b/data/en.wikipedia.org/wiki/Plankton-2.md new file mode 100644 index 000000000..22d7d8aa7 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Plankton-2.md @@ -0,0 +1,37 @@ +--- +title: "Plankton" +chunk: 3/7 +source: "https://en.wikipedia.org/wiki/Plankton" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:10.175954+00:00" +instance: "kb-cron" +--- + +Plankton are also found at the ocean surface. Organisms that live at or just below the air-sea interface are called neuston. They float either on the water's surface (epineuston) or swim in the top few centimeters (hyponeuston). Many neuston qualify to be categorised as part of the broader plankton community, because they drift largely as currents or wind dictate, lacking strong enough swimming ability to counter them. +Neustonic animals are primarily adapted to float upside-down on the ocean surface, similar to an inverted benthos, and form a unique subset of the zooplankton community, which plays a pivotal role in the functioning of marine ecosystems. Neustonic zooplankton are partially responsible for the active energy flux between superficial and deep layers of the ocean.Neustonic plankton is also a food source for marine zooplankton and fish migrating from the deep layers and seabirds. + +==== In deep ocean ==== +In 2025, researchers discovered microbial communities inhabiting the ocean conveyor belt, even at great depths in the ocean. Ocean currents are generated by surface wind and storms down to about 500 m (1,600 ft) below the surface. But the average depth of the ocean goes far below to 3.7 km (2.3 mi). At these greater depths, currents are driven by differences in water density, which in turn are controlled by differences in water temperature and salinity. This mechanism results in a circulation which behaves like a conveyor belt, carrying water and microorganisms to great depths and around the world. +Water samples were taken along the full depth of the water column in the South Pacific Ocean, from Easter Island to Antarctica. They found marked increases in microbial diversity about 300 m (1,000 ft) deep, in a layer they call the prokaryotic phylocline. This zone, similar to the pycnocline, represents a shift from less diverse surface waters to abundant microbial ecosystems in the deep ocean. For instance, a group they called the Antarctic Bottom Water contains microbes suited to cold and high pressure, while another group they called the Ancient Water Group, located in slowly circulating water isolated from the surface for over a millennium, contains microbes with genes adapted to low oxygen. + +== By taxon == +Plankton contains representatives from all major divisions of life. This is because plankton are defined by habitat (water/air) and behaviour (drifting), and not by any phylogenetic or taxonomic considerations. So plankton are not a taxon, but they can be divided into broad taxonomic groups, as follows: + +planktonic animals (metazoa) : – mostly predators (zooplankton) of smaller plankton. Examples are arrow worms, sea butterfly, ostracods, and salps. There are also planktonic microanimals typically smaller than one mm, such as copepods, water fleas, rotifers, and larval stages of various crustaceans and corals. +planktonic protists: – single-celled eukaryote microorganisms, mostly invisible to the naked eye, such as diatoms, dinoflagellates, coccolithophores, foraminifera, radiolarians, and ciliates. Planktonic protists include algae (phytoplankton), protozoa (zooplankton), and many mixoplankton. +planktonic fungi: – known also as mycoplankton, play important roles in remineralisation and nutrient cycling. For example, in the mycoloop, parasitic chytrids facilitate the transfer of nutrients from large, inedible phytoplankton to zooplankton. +planktonic prokaryotes: planktonic bacteria and archaea known also as bacterioplankton and archaeoplankton. These play important roles as primary producers, or in remineralising organic material like mycoplankton down the water column. Photosynthetic cyanobacteria are important members of the phytoplankton. The unusually small Pelagibacter ubique, perhaps the most abundant bacterium on Earth, makes up about one third of microbial cells in the surface ocean, and plays important roles recycling nutrients in the microbial loop. The Roseobacter clade are significantly connected to phytoplankton. +planktonic viruses: – known also as virioplankton, though not always classified as living organisms, are abundant in planktonic communities and influence microbial dynamics. Viruses are small infectious agents that can replicate only inside the living cells of a host organism, because they need the replication machinery of the host to do so. They are more abundant in the plankton than bacteria and archaea, though much smaller. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea. In the viral shunt, viruses infect and break down (lyse) bacteria, releasing their nutrients and organic matter back into the water instead of allowing them to be consumed by larger organisms like zooplankton. This "shunts" nutrients away from higher trophic levels, keeping them in the microbial loop for reuse by other microorganisms. + +== By size == +Plankton are also often described in terms of size. Usually the following divisions are used:  + +However, some of these terms may be used with very different boundaries, especially on the larger end. The term microplankton is sometimes used more broadly to cover plankton that cannot really be seen without using a microscope, say plankton less than about one millimetre across. The existence and importance of nano- and even smaller plankton was only discovered during the 1980s, but they are thought to make up the largest proportion of all plankton in number and diversity. It is the largely unseen microplankton that are the main drivers of the marine food web. +Microplankton and smaller groups are microorganisms that operate at low Reynolds numbers, where the viscosity of water is more important than its mass or inertia. + +== By trophic mode == +Trophic mode describes the role of a planktonic organism in the food web based on how it obtains energy and nutrients to sustain its growth, reproduction, and survival. By trophic mode, plankton can be divided into four broad functional groups: phytoplankton, zooplankton, mixoplankton and decomposers. + +=== Phytoplankton === +Phytoplankton (from Greek phyton, or plant) are autotrophic prokaryotic or eukaryotic algae that live near the water surface where there is sufficient light to support photosynthesis. Among the more important groups are the diatoms, cyanobacteria, dinoflagellates, and coccolithophores. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Plankton-3.md b/data/en.wikipedia.org/wiki/Plankton-3.md new file mode 100644 index 000000000..e02dd69e0 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Plankton-3.md @@ -0,0 +1,37 @@ +--- +title: "Plankton" +chunk: 4/7 +source: "https://en.wikipedia.org/wiki/Plankton" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:10.175954+00:00" +instance: "kb-cron" +--- + +=== Zooplankton === +Zooplankton (from Greek zoon, or animal) are small protozoans or metazoans (e.g. crustaceans and other animals) that feed on other plankton. Some of the eggs and larvae of larger nektonic animals, such as fish, crustaceans, and annelids, are included here. + +=== Mixoplankton === +Mixoplankton (from Greek mixis, or mixture) have a mixed trophic strategy. In recent years, there has been a growing recognition that perhaps the majority of plankton can act in both the above modes. +Traditionally, plankton were divided into just the first two broad trophic groups: plant-like phytoplankton which make their own food, usually by photosynthesis, and animal-like zooplankton that eat other plankton. In recent years, there has been a recognition that many plankton, perhaps over half, are mixotrophic. Plankton have traditionally been categorized as producer, consumer, and recycler groups, but some plankton are able to benefit from more than just one trophic level. This mixed trophic strategy means mixoplankton can act as both producers and consumers, either at the same time or switching between modes of nutrition in response to ambient conditions. In this manner, mixoplankton can use photosynthesis for growth when nutrients and light are abundant, but switch to eating phytoplankton, zooplankton or each other when growing conditions are poor. +As a result of these findings, many unicellular plankton formally categorized as phytoplankton, including coccolithophores and dinoflagellates, are longer included as strictly phytoplankton, as they not only produce their own food through phototrophy but can also ingest other organisms. These organisms are now more correctly termed mixoplankton. This recognition has important consequences for how the functioning of the planktonic food web is viewed. + +Mixotrophs can be further divided into two groups; constitutive mixotrophs which are able to perform photosynthesis on their own, and non-constitutive mixotrophs which use phagocytosis to engulf phototrophic prey that are either kept alive inside the host cell, which benefits from its photosynthesis, or they digested, except for the plastids, which continue to perform photosynthesis (kleptoplasty). Recognition of the importance of mixotrophy as an ecological strategy is increasing, as well as the wider role this may play in marine biogeochemistry. Studies have shown that mixoplankton are much more important for marine ecology than previously assumed. Their presence acts as a buffer that prevents the collapse of ecosystems during times with little to no light. Mixoplankton have ancient origins and have been recognized by scientists for over a century. However, it is only in recent years that the widespread significance of mixoplankton has been gaining recognition in mainstream marine science. + +=== Decomposers === +Instead of directly building biomass, decomposers break organic nutrients down into inorganic forms which can be recycled (an approach which metabolically can be costly). +Fungi: Mostly tiny mycoplankton (microfungi), yeast, or mobile zoospores, that can recycle organic matter through a process called the mycoloop which involves parasiting plankton. +Bacteria/Archaea: often called bacterioplankton. These minute prokaryotes (typically <0.001mm) return organic nutrients to inorganic forms by breaking down particulate and dissolved organic matter through the process called the microbial loop. This process recycles nutrients, like nitrogen and phosphorus, back into the water for primary producers like phytoplankton to use again. Some convert ammonium in animal waste to nitrate, while others transform nitrate to nitrogen gas. Viral infections likely destroy many, while others are eaten by protist zooplankton and mixoplankton, which use their nutrients for photosynthesis. However details of their ecology is complex and it is not clear what sustains them. +Viruses: Typically 10 to 100 times smaller than bacteria and also the most abundant (~100 billion per litre), viruses infect other plankton and larger organisms. It is thought they efficiently halt vast plankton blooms within days, by turning biomass into dissolved organic matter that supports bacterial growth through a process called the viral shunt. Being host-specific, they also likely influence the biological and microbial carbon pumps. + +== Other groups == + +=== Gelatinous zooplankton === + +Gelatinous zooplankton are fragile animals that live in the water column in the ocean. Their delicate bodies have no hard parts and are easily damaged or destroyed. Gelatinous zooplankton are often transparent. All jellyfish are gelatinous zooplankton, but not all gelatinous zooplankton are jellyfish. The most commonly encountered organisms include ctenophores, medusae, salps, and Chaetognatha in coastal waters. However, almost all marine phyla, including Annelida, Mollusca and Arthropoda, contain gelatinous species, but many of those odd species live in the open ocean and the deep sea and are less available to the casual ocean observer. + +=== Ichthyoplankton === + +Ichthyoplankton are the eggs and larvae of fish. They are mostly found in the sunlit zone of the water column, less than 200 metres deep, which is sometimes called the epipelagic or photic zone. Ichthyoplankton are planktonic, meaning they cannot swim effectively under their own power, but must drift with the ocean currents. Fish eggs cannot swim at all, and are unambiguously planktonic. Early stage larvae swim poorly, but later stage larvae swim better and cease to be planktonic as they grow into juveniles. Fish larvae are part of the zooplankton that eat smaller plankton, while fish eggs carry their own food supply. Both eggs and larvae are themselves eaten by larger animals. Fish can produce high numbers of eggs which are often released into the open water column. Fish eggs typically have a diameter of about 1 millimetre (0.039 in). The newly hatched young of oviparous fish are called larvae. They are usually poorly formed, carry a large yolk sac (for nourishment), and are very different in appearance from juvenile and adult specimens. The larval period in oviparous fish is relatively short (usually only several weeks), and larvae rapidly grow and change appearance and structure (a process termed metamorphosis) to become juveniles. During this transition larvae must switch from their yolk sac to feeding on zooplankton prey, a process which depends on typically inadequate zooplankton density, starving many larvae. In time fish larvae become able to swim against currents, at which point they cease to be plankton and become juvenile fish. + +=== Pseudoplankton === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Plankton-4.md b/data/en.wikipedia.org/wiki/Plankton-4.md new file mode 100644 index 000000000..668b6729f --- /dev/null +++ b/data/en.wikipedia.org/wiki/Plankton-4.md @@ -0,0 +1,51 @@ +--- +title: "Plankton" +chunk: 5/7 +source: "https://en.wikipedia.org/wiki/Plankton" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:10.175954+00:00" +instance: "kb-cron" +--- + +Pseudoplankton are organisms that attach themselves to planktonic organisms or other floating objects, such as drifting wood, buoyant shells of organisms such as Spirula, or man-made flotsam. Examples include goose barnacles and the bryozoan Jellyella. By themselves these animals cannot float, which contrasts them with true planktonic organisms, such as Velella and the Portuguese Man o' War, which are buoyant. Pseudoplankton are often found in the guts of filtering zooplankters. + +=== Tychoplankton === + +Tychoplankton are organisms, such as free-living or attached benthic organisms and other non-planktonic organisms, that are carried into the plankton through a disturbance of their benthic habitat, or by winds and currents. This can occur by direct turbulence or by disruption of the substrate and subsequent entrainment in the water column. Tychoplankton are, therefore, a primary subdivision for sorting planktonic organisms by duration of lifecycle spent in the plankton, as neither their entire lives nor particular reproductive portions are confined to planktonic existence. Tychoplankton are sometimes called accidental plankton. + +=== Mineralized plankton === + +=== By life cycle === + +==== Holoplankton ==== + +Holoplankton are organisms that are planktic for their entire life cycle. Holoplankton can be contrasted with meroplankton, which are planktic organisms that spend part of their life cycle in the benthic zone. Examples of holoplankton include some diatoms, radiolarians, some dinoflagellates, foraminifera, amphipods, copepods, and salps, as well as some gastropod mollusk species. Holoplankton dwell in the pelagic zone as opposed to the benthic zone. Holoplankton include both phytoplankton and zooplankton and vary in size. The most common plankton are protists. + +==== Meroplankton ==== + +Meroplankton are a wide variety of aquatic organisms that have both planktonic and benthic stages in their life cycles. Much of the meroplankton consists of larval stages of larger organisms. Meroplankton can be contrasted with holoplankton, which are planktonic organisms that stay in the pelagic zone as plankton throughout their entire life cycle. After some time in the plankton, many meroplankton graduate to the nekton or adopt a benthic (often sessile) lifestyle on the seafloor. The larval stages of benthic invertebrates make up a significant proportion of planktonic communities. The planktonic larval stage is particularly crucial to many benthic invertebrates in order to disperse their young. Depending on the particular species and the environmental conditions, larval or juvenile-stage meroplankton may remain in the pelagic zone for durations ranging from hours to months. + +== Ecology == + +=== Food webs === + +As well as representing the lower levels of a food chain that supports commercially important fisheries, plankton ecosystems play a role in the biogeochemical cycles of many important chemical elements, including the ocean's carbon cycle. Fish larvae mainly eat zooplankton, which in turn eat phytoplankton +The microbial loop: Bacteria play central roles in aquatic food webs. The microbial loop refers to a process in aquatic ecosystems where bacteria consume dissolved organic matter (DOM) and are then consumed by larger microorganisms, effectively cycling nutrients and energy within the ecosystem. +The viral shunt: Viruses also play central roles in aquatic food webs. The viral shunt is a process where viruses infect and lyse (burst) host cells, releasing cellular contents (including dissolved organic matter) that can be utilized by other microplankton like bacteria, effectively bypassing the traditional food web pathways. This process plays a significant role in nutrient cycling and carbon flow within aquatic ecosystems. +Fungi have a role as well. The mycoloop is a specific aquatic food web pathway where parasitic chytrid fungi infect large, inedible phytoplankton, and their zoospores (a type of spore) become a food source for zooplankton. In this manner, the chytrid fungi transfer nutrients from otherwise unusable phytoplankton to zooplankton. + +=== Carbon cycle === + +Primarily by grazing on phytoplankton, zooplankton provide carbon to the planktic foodweb, either respiring it to provide metabolic energy, or upon death as biomass or detritus. Organic material tends to be denser than seawater, so it sinks into open ocean ecosystems away from the coastlines, transporting carbon along with it. This process, called the biological pump, is one reason that oceans constitute the largest carbon sink on Earth. However, it has been shown to be influenced by increments of temperature. In 2019, a study indicated that at ongoing rates of seawater acidification, Antarctic phytoplanktons could become smaller and less effective at storing carbon before the end of the century. +It might be possible to increase the ocean's uptake of carbon dioxide (CO2) generated through human activities by increasing plankton production through iron fertilization – introducing amounts of iron into the ocean. However, this technique may not be practical at a large scale. Ocean oxygen depletion and resultant methane production (caused by the excess production remineralising at depth) is one potential drawback. + +=== Great Calcite Belt === + +The Great Calcite Belt is a region in the Southern Ocean characterized by high concentrations of coccolithophores, a type of calcite-producing phytoplankton. It plays a significant role in ocean biogeochemistry and the global carbon cycle. Coccolithophores in the belt produce calcium carbonate (calcite or chalk) plates called coccoliths. This process, known as calcification, affects the ocean's carbon cycle by lowering alkalinity and releasing CO2. However, when coccolithophores die, their calcite shells sink, contributing to the biological pump by transporting carbon to the deep ocean, sequestering it for centuries or longer and mitigating atmospheric CO2 levels. + +=== Oxygen production === + +Phytoplankton absorb energy from the Sun and nutrients from the water to produce their own nourishment or energy. In the process of photosynthesis, phytoplankton release molecular oxygen (O2) into the water as a waste byproduct. It is estimated that about 50% of the world's oxygen is produced via phytoplankton photosynthesis. The rest is produced via photosynthesis on land by plants. Furthermore, phytoplankton photosynthesis has controlled the atmospheric CO2/O2 balance since the early Precambrian Eon. + +=== Absorption efficiency === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Plankton-5.md b/data/en.wikipedia.org/wiki/Plankton-5.md new file mode 100644 index 000000000..449842c28 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Plankton-5.md @@ -0,0 +1,33 @@ +--- +title: "Plankton" +chunk: 6/7 +source: "https://en.wikipedia.org/wiki/Plankton" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:10.175954+00:00" +instance: "kb-cron" +--- + +The absorption efficiency (AE) of plankton is the proportion of food absorbed by the plankton that determines how available the consumed organic materials are in meeting the required physiological demands. Depending on the feeding rate and prey composition, variations in absorption efficiency may lead to variations in fecal pellet production, and thus regulates how much organic material is recycled back to the marine environment. Low feeding rates typically lead to high absorption efficiency and small, dense pellets, while high feeding rates typically lead to low absorption efficiency and larger pellets with more organic content. Another contributing factor to dissolved organic matter (DOM) release is respiration rate. Physical factors such as oxygen availability, pH, and light conditions may affect overall oxygen consumption and how much carbon is loss from zooplankton in the form of respired CO2. The relative sizes of zooplankton and prey also mediate how much carbon is released via sloppy feeding. Smaller prey are ingested whole, whereas larger prey may be fed on more "sloppily", that is more biomatter is released through inefficient consumption. There is also evidence that diet composition can impact nutrient release, with carnivorous diets releasing more dissolved organic carbon (DOC) and ammonium than omnivorous diets. + +== Biomass variability == + +The growth of phytoplankton populations is dependent on light levels and nutrient availability. The chief factor limiting growth varies from region to region in the world's oceans. On a broad scale, growth of phytoplankton in the oligotrophic tropical and subtropical gyres is generally limited by nutrient supply, while light often limits phytoplankton growth in subarctic gyres. Environmental variability at multiple scales influences the nutrient and light available for phytoplankton, and as these organisms form the base of the marine food web, this variability in phytoplankton growth influences higher trophic levels. For example, at interannual scales phytoplankton levels temporarily plummet during El Niño periods, influencing populations of zooplankton, fishes, sea birds, and marine mammals. +The effects of anthropogenic warming on the global population of phytoplankton is an area of active research. Changes in the vertical stratification of the water column, the rate of temperature-dependent biological reactions, and the atmospheric supply of nutrients are expected to have important impacts on future phytoplankton productivity. Additionally, changes in the mortality of phytoplankton due to rates of zooplankton grazing may be significant. + +== Planktonic relationships == + +=== Fish and plankton === +Zooplankton are the initial prey item for almost all fish larvae as they switch from their yolk sacs to external feeding. Fish rely on the density and distribution of zooplankton to match that of new larvae, which can otherwise starve. Natural factors (e.g., current variations, temperature changes) and man-made factors (e.g. river dams, ocean acidification, rising temperatures) can strongly affect zooplankton populations, which can in turn strongly affect fish larval survival, and therefore breeding success. +It has been shown that plankton can be patchy in marine environments where there aren't significant fish populations and additionally, where fish are abundant, zooplankton dynamics are influenced by the fish predation rate in their environment. Depending on the predation rate, they could express regular or chaotic behavior. +A negative effect that fish larvae can have on planktonic algal blooms is that the larvae will prolong the blooming event by diminishing available zooplankton numbers; this in turn permits excessive phytoplankton growth allowing the bloom to flourish . +The importance of both phytoplankton and zooplankton is also well-recognized in extensive and semi-intensive pond fish farming. Plankton population-based pond management strategies for fish rearing have been practiced by traditional fish farmers for decades, illustrating the importance of plankton even in man-made environments. + +=== Whales and plankton === +Of all animal fecal matter, it is whale feces that is the 'trophy' in terms of increasing nutrient availability. Phytoplankton are the powerhouse of open ocean primary production and they can acquire many nutrients from whale feces. In the marine food web, phytoplankton are at the base of the food web and are consumed by zooplankton & krill, which are preyed upon by larger and larger marine organisms, including whales, so it can be said that whale feces fuels the entire food web. + +=== Humans and plankton === +Plankton have many direct and indirect effects on humans. +Around 70% of the oxygen in the atmosphere is produced in the oceans from phytoplankton performing photosynthesis, meaning that the majority of the oxygen available for humans and other organisms that respire aerobically is produced by plankton. +Plankton also make up the base of the marine food web, providing food for all the trophic levels above. Recent studies have analyzed the marine food web to see if the system runs on a top-down or bottom-up approach. Essentially, this research is focused on understanding whether changes in the food web are driven by nutrients at the bottom of the food web or predators at the top. The general conclusion is that the bottom-up approach seemed to be more predictive of food web behavior. This indicates that plankton have more sway in determining the success of the primary consumer species that prey on them than do the secondary consumers that prey on the primary consumers. +In some cases, plankton act as an intermediate host for deadly parasites in humans. One such case is that of cholera, an infection caused by several pathogenic strains of Vibrio cholerae. These species have been shown to have a symbiotic relationship with chitinous zooplankton species like copepods. These bacteria benefit not only from the food provided by the chiton from the zooplankton, but also from the protection from acidic environments. Once the copepods have been ingested by a human host, the chitinous exterior protects the bacteria from the stomach acids in the stomach and proceed to the intestines. Once there, the bacteria bind with the surface of the small intestine and the host will start developing symptoms, including extreme diarrhea, within five days. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Plankton-6.md b/data/en.wikipedia.org/wiki/Plankton-6.md new file mode 100644 index 000000000..f3184832e --- /dev/null +++ b/data/en.wikipedia.org/wiki/Plankton-6.md @@ -0,0 +1,46 @@ +--- +title: "Plankton" +chunk: 7/7 +source: "https://en.wikipedia.org/wiki/Plankton" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:10.175954+00:00" +instance: "kb-cron" +--- + +== Plankton Manifesto == +In 2024, the United Nations Global Compact's Ocean Stewardship Coalition launched the Plankton Manifesto, collaboratively developed by over 30 international experts. It outlines strategic recommendations to guide global efforts at safeguarding plankton and harnessing their potential to address planetary climate change issues, as well as pollution and biodiversity loss. It emphasizes plankton's critical role as the foundation of marine ecosystems, producing about 50% of Earth's oxygen and sequestering 30–50 billion metric tonnes of carbon annually. +Key recommendations include: + +Enhanced research and monitoring: Leveraging technologies like DNA sequencing, bioinformatics, satellite monitoring, and AI image analysis to improve understanding of plankton dynamics and create a global plankton atlas. +Plankton-based solutions: Promoting innovative applications, such as using plankton for water purification, bioplastics, fertilizers, and animal feed to support sustainable industries. +Policy integration: Urging governments, United Nations agencies, and businesses to include plankton in climate and biodiversity frameworks, with endorsements sought at COP29, COP16, and the 2025 United Nations Ocean Conference. +Public awareness: Fostering "plankton literacy" through education and interdisciplinary initiatives to highlight their role in food security and ecosystem health. +Collaboration: Encouraging cross-sectoral partnerships among academia, industry, and governments to fund research and protect plankton from threats like nutrient pollution and ocean warming. + +== See also == +Paradox of the plankton +Seston +Veliger + +== References == + +== Further reading == +Dolan, J.R., Agatha, S., Coats, D.W., Montagnes, D.J.S., Stocker, D.K., eds. (2013).Biology and Ecology of Tintinnid Ciliates: Models for Marine Plankton. Wiley-Blackwell, Oxford, UK ISBN 978-0-470-67151-1. +Dusenbery, David B. (2009). Living at Micro Scale: The Unexpected Physics of Being Small. Harvard University Press, Cambridge, Massachusetts ISBN 978-0-674-03116-6. +Kiørboe, Thomas (2008). A Mechanistic Approach to Plankton Ecology. Princeton University Press, Princeton, N.J. ISBN 978-0-691-13422-2. +Kirby, Richard R. (2010). Ocean Drifters: A Secret World Beneath the Waves. Studio Cactus Ltd, UK. ISBN 978-1-904239-10-9. + +== External links == + +Ocean Drifters – Short film narrated by David Attenborough about the varied roles of plankton +Plankton Chronicles Archived 2020-07-28 at the Wayback Machine – Short documentary films and photos +COPEPOD: The Global Plankton Database – Global coverage database of zooplankton biomass and abundance data +Plankton*Net Archived 2006-08-21 at the Wayback Machine – Taxonomic database of images of plankton species +Guide to the marine zooplankton of south-eastern Australia – Tasmanian Aquaculture and Fisheries Institute +Sir Alister Hardy Foundation for Ocean Science – Continuous Plankton Recorder Survey +Australian Continuous Plankton Recorder Project – Integrated Marine Observing System +Sea Drifters – BBC Audio slideshow +Aquaparadox: the diversity of planktonic microorganisms – Images of planktonic microorganisms +Plankton, planktic, planktonic – Essays on nomenclature +Journal of Plankton Research – Scientific periodical devoted to plankton \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Raised_beach-0.md b/data/en.wikipedia.org/wiki/Raised_beach-0.md new file mode 100644 index 000000000..2c959009d --- /dev/null +++ b/data/en.wikipedia.org/wiki/Raised_beach-0.md @@ -0,0 +1,32 @@ +--- +title: "Raised beach" +chunk: 1/3 +source: "https://en.wikipedia.org/wiki/Raised_beach" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:12.792673+00:00" +instance: "kb-cron" +--- + +A raised beach, coastal terrace, or perched coastline is a relatively flat, horizontal or gently inclined surface of marine origin, mostly an old abrasion platform which has been lifted out of the sphere of wave activity (sometimes called "tread"). Thus, it lies above or under the current sea level, depending on the time of its formation. It is bounded by a steeper ascending slope on the landward side and a steeper descending slope on the seaward side (sometimes called "riser"). Due to its generally flat shape, it is often used for anthropogenic structures such as settlements and infrastructure. +A raised beach is an emergent coastal landform. Raised beaches and marine terraces are beaches or wave-cut platforms raised above the shoreline by a relative fall in the sea level. + +Around the world, a combination of tectonic coastal uplift and Quaternary sea-level fluctuations has resulted in the formation of marine terrace sequences, most of which were formed during separate interglacial highstands that can be correlated to marine isotope stages (MIS). +A marine terrace commonly retains a shoreline angle or inner edge, the slope inflection between the marine abrasion platform and the associated paleo sea cliff. The shoreline angle represents the maximum shoreline of a transgression and therefore a paleo-sea level. + +== Morphology == + +The platform of a marine terrace usually has a gradient between 1°–5° depending on the former tidal range with, commonly, a linear to concave profile. The width is quite variable, reaching up to 1,000 metres (3,300 ft), and seems to differ between the northern and southern hemispheres. The cliff faces that delimit the platform can vary in steepness depending on the relative roles of marine and subaerial processes. At the intersection of the former shore (wave-cut/abrasion-) platform and the rising cliff face the platform commonly retains a shoreline angle or inner edge (notch) that indicates the location of the shoreline at the time of maximum sea ingression and therefore a paleo-sea level. Sub-horizontal platforms usually terminate in a low-tide cliff, and it is believed that the occurrence of these platforms depends on the tidal activity. Marine terraces can extend for several tens of kilometers parallel to the coast. +Older terraces are covered by marine and/or alluvial or colluvial materials while the uppermost terrace levels usually are less well preserved. While marine terraces in areas of relatively rapid uplift rates (> 1 mm/year) can often be correlated to individual interglacial periods or stages, those in areas of slower uplift rates may have a polycyclic origin with stages of returning sea levels following periods of exposure to weathering. +Marine terraces can be covered by a wide variety of soils with complex histories and different ages. In protected areas, allochthonous sandy parent materials from tsunami deposits may be found. Common soil types found on marine terraces include planosols and solonetz. + +== Formation == +It is now widely thought that marine terraces are formed during the separated high stands of interglacial stages correlated to marine isotope stages (MIS). + +=== Causes === + +The formation of marine terraces is controlled by changes in environmental conditions and by tectonic activity during recent geological times. Changes in climatic conditions have led to eustatic sea-level oscillations and isostatic movements of the Earth's crust, especially with the changes between glacial and interglacial periods. +Processes of eustasy lead to glacioeustatic sea level fluctuations due to changes in the water volume in the oceans, and hence to regressions and transgressions of the shoreline. At times of maximum glacial extent during the last glacial period, the sea level was about 100 metres (330 ft) lower compared to today. Eustatic sea level changes can also be caused by changes in the void volume of the oceans, either through sedimento-eustasy or tectono-eustasy. +Processes of isostasy involve the uplift of continental crusts along with their shorelines. Today, the process of glacial isostatic adjustment mainly applies to Pleistocene glaciated areas. In Scandinavia, for instance, the present rate of uplift reaches up to 10 millimetres (0.39 in)/year. +In general, eustatic marine terraces were formed during separate sea-level highstands of interglacial stages and can be correlated to marine oxygen isotopic stages (MIS). Glacioisostatic marine terraces were mainly created during stillstands of the isostatic uplift. When eustasy was the main factor for the formation of marine terraces, derived sea level fluctuations can indicate former climate changes. This conclusion has to be treated with care, as isostatic adjustments and tectonic activities can be extensively overcompensated by a eustatic sea level rise. Thus, in areas of both eustatic and isostatic or tectonic influences, the course of the relative sea level curve can be complicated. Hence, most of today's marine terrace sequences were formed by a combination of tectonic coastal uplift and Quaternary sea level fluctuations. +Jerky tectonic uplifts can also lead to marked terrace steps while smooth relative sea level changes may not result in obvious terraces, and their formations are often not referred to as marine terraces. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Raised_beach-1.md b/data/en.wikipedia.org/wiki/Raised_beach-1.md new file mode 100644 index 000000000..0d65c0116 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Raised_beach-1.md @@ -0,0 +1,34 @@ +--- +title: "Raised beach" +chunk: 2/3 +source: "https://en.wikipedia.org/wiki/Raised_beach" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:12.792673+00:00" +instance: "kb-cron" +--- + +=== Processes === +Marine terraces often result from marine erosion along rocky coastlines in temperate regions due to wave attacks and sediment carried in the waves. Erosion also takes place in connection with weathering and cavitation. The speed of erosion is highly dependent on the shoreline material (hardness of rock), the bathymetry, and the bedrock properties and can be between only a few millimeters per year for granitic rocks and more than 10 metres (33 ft) per year for volcanic ejecta. The retreat of the sea cliff generates a shore (wave-cut/abrasion-) platform through the process of abrasion. A relative change in the sea level leads to regressions or transgressions and eventually forms another terrace (marine-cut terrace) at a different altitude, while notches in the cliff face indicate short stillstands. +It is believed that the terrace gradient increases with tidal range and decreases with rock resistance. In addition, the relationship between terrace width and the strength of the rock is inverse, and higher rates of uplift and subsidence as well as a higher slope of the hinterland increase the number of terraces formed during a certain time. +Furthermore, shore platforms are formed by denudation and marine-built terraces arise from accumulations of materials removed by shore erosion. Thus, a marine terrace can be formed by both erosion and accumulation. However, there is an ongoing debate about the roles of wave erosion and weathering in the formation of shore platforms. +Reef flats or uplifted coral reefs are another kind of marine terrace found in intertropical regions. They are a result of biological activity, shoreline advance and accumulation of reef materials. +While a terrace sequence can date back hundreds of thousands of years, its degradation is a rather fast process. A deeper transgression of cliffs into the shoreline may destroy previous terraces; but older terraces might be decayed or covered by deposits, colluvia or alluvial fans. Erosion and backwearing of slopes caused by incisive streams play another important role in this degradation process. + +=== Land and sea level history === +The total displacement of the shoreline relative to the age of the associated interglacial stage allows the calculation of a mean uplift rate or the calculation of eustatic level at a particular time if the uplift is known. +To estimate vertical uplift, the eustatic position of the considered paleo sea levels relative to the present one must be known as precisely as possible. Current chronology relies principally on relative dating based on geomorphologic criteria, but in all cases, the shoreline angle of the marine terraces is associated with numerical ages. The best-represented terrace worldwide is the one correlated to the last interglacial maximum (MIS 5e). The age of MISS 5e is arbitrarily fixed to range from 130 to 116 ka but is demonstrated to range from 134 to 113 ka in Hawaii and Barbados with a peak from 128 to 116 ka on tectonically stable coastlines. Older marine terraces well represented in worldwide sequences are those related to MIS 9 (~303–339 ka) and 11 (~362–423 ka). Compilations show that sea level was 3 ± 3 meters higher during MIS 5e, MIS 9 and 11 than during the present one and −1 ± 1 m to the present one during MIS 7. Consequently, MIS 7 (~180-240 ka) marine terraces are less pronounced and sometimes absent. When the elevations of these terraces are higher than the uncertainties in paleo-eustatic sea level mentioned for the Holocene and Late Pleistocene, these uncertainties don't affect on overall interpretation. +The sequence can also occur where the accumulation of ice sheets has depressed the land so that when the ice sheets melt the land readjusts with time thus raising the height of the beaches (glacial-isostatic rebound) and in places where co-seismic uplift occurs. In the latter case, the terrace is not correlated with sea-level highstands even if co-seismic terraces are known only for the Holocene. + +== Mapping and surveying == + +For exact interpretations of the morphology, extensive datings, surveying and mapping of marine terraces are applied. This includes stereoscopic aerial photographic interpretation (ca. 1 : 10,000 – 25,000), on-site inspections with topographic maps (ca. 1 : 10,000) and analysis of eroded and accumulated material. Moreover, the exact altitude can be determined with an aneroid barometer or preferably with a levelling instrument mounted on a tripod. It should be measured with an accuracy of 1 cm (0.39 in) and at about every 50–100 metres (160–330 ft), depending on the topography. In remote areas, the techniques of photogrammetry and tacheometry can be applied. + +== Correlation and dating == +Different methods for dating and correlation of marine terraces can be used and combined. + +=== Correlational dating === +The morphostratigraphic approach focuses especially in regions of marine regression on the altitude as the most important criterion to distinguish coastlines of different ages. Moreover, individual marine terraces can be correlated based on their size and continuity. Also, paleo-soils as well as glacial, fluvial, eolian and periglacial landforms and sediments may be used to find correlations between terraces. On New Zealand's North Island, for instance, tephra and loess were used to date and correlate marine terraces. At the terminus advance of former glaciers marine terraces can be correlated by their size, as their width decreases with age due to the slowly thawing glaciers along the coastline. +The lithostratigraphic approach uses typical sequences of sediment and rock strata to prove sea-level fluctuations based on an alternation of terrestrial and marine sediments or littoral and shallow marine sediments. Those strata show typical layers of transgressive and regressive patterns. However, an unconformity in the sediment sequence might make this analysis difficult. +The biostratigraphic approach uses remains of organisms which can indicate the age of a marine terrace. For that, often mollusc shells, foraminifera or pollen are used. Especially Mollusca can show specific properties depending on their depth of sedimentation. Thus, they can be used to estimate former water depths. +Marine terraces are often correlated to marine oxygen isotopic stages (MIS) and can also be roughly dated using their stratigraphic position. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Raised_beach-2.md b/data/en.wikipedia.org/wiki/Raised_beach-2.md new file mode 100644 index 000000000..19bc37292 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Raised_beach-2.md @@ -0,0 +1,40 @@ +--- +title: "Raised beach" +chunk: 3/3 +source: "https://en.wikipedia.org/wiki/Raised_beach" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:12.792673+00:00" +instance: "kb-cron" +--- + +=== Direct dating === +There are various methods for the direct dating of marine terraces and their related materials. The most common method is 14C radiocarbon dating, which has been used, for example, on the North Island of New Zealand to date several marine terraces. It utilizes terrestrial biogenic materials in coastal sediments, such as mollusc shells, by analyzing the 14C isotope. In some cases, however, dating based on the 230Th/234U ratio was applied, in case detrital contamination or low uranium concentrations made finding a high-resolution dating difficult. In a study in southern Italy, paleomagnetism was used to carry out paleomagnetic datings and luminescence dating (OSL) was used in different studies on the San Andreas Fault and on the Quaternary Eupcheon Fault in South Korea. In the last decade, the dating of marine terraces has been enhanced since the arrival of the terrestrial cosmogenic nuclides method, particularly through the use of 10Be and 26Al cosmogenic isotopes produced on site. These isotopes record the duration of surface exposure to cosmic rays. This exposure age reflects the age of abandonment of a marine terrace by the sea. +To calculate the eustatic sea level for each dated terrace, it is assumed that the eustatic sea-level position corresponding to at least one marine terrace is known and that the uplift rate has remained essentially constant in each section. + +== Relevance for other research areas == + +Marine terraces play an important role in the research on tectonics and earthquakes. They may show patterns and rates of tectonic uplift and thus may be used to estimate the tectonic activity in a certain region. In some cases the exposed secondary landforms can be correlated with known seismic events such as the 1855 Wairarapa earthquake on the Wairarapa Fault near Wellington, New Zealand which produced a 2.7-metre (8 ft 10 in) uplift. This figure can be estimated from the vertical offset between raised shorelines in the area. +Furthermore, with the knowledge of eustatic sea level fluctuations, the speed of isostatic uplift can be estimated and eventually the change of relative sea levels for certain regions can be reconstructed. Thus, marine terraces also provide information for the research on climate change and trends in future sea level changes. +When analyzing the morphology of marine terraces, it must be considered, that both eustasy and isostasy can influence on the formation process. This way can be assessed, whether there were changes in sea level or whether tectonic activities took place. + +== Prominent examples == + +Raised beaches are found in a wide variety of coast and geodynamical backgrounds such as subduction on the Pacific coasts of South and North America, passive margin of the Atlantic coast of South America, collision context on the Pacific coast of Kamchatka, Papua New Guinea, New Zealand, Japan, passive margin of the South China Sea coast, on west-facing Atlantic coasts, such as Donegal Bay, County Cork and County Kerry in Ireland; Bude, Widemouth Bay, Crackington Haven, Tintagel, Perranporth and St Ives in Cornwall, the Vale of Glamorgan, Gower Peninsula, Pembrokeshire and Cardigan Bay in Wales, Jura and the Isle of Arran in Scotland, Finistère in Brittany and Galicia in Northern Spain and at Squally Point in Eatonville, Nova Scotia within the Cape Chignecto Provincial Park. +Other important sites include various coasts of New Zealand, e.g. Turakirae Head near Wellington being one of the world's best and most thoroughly studied examples. Also along the Cook Strait in New Zealand, there is a well-defined sequence of uplifted marine terraces from the late Quaternary at Tongue Point. It features a well-preserved lower terrace from the last interglacial, a widely eroded higher terrace from the penultimate interglacial and another still higher terrace, which is nearly completely decayed. Furthermore, on New Zealand's North Island at the eastern Bay of Plenty, a sequence of seven marine terraces has been studied. + +Along many coasts of the mainland and islands around the Pacific, marine terraces are typical coastal features. An especially prominent marine terraced coastline can be found north of Santa Cruz, near Davenport, California, where terraces probably have been raised by repeated slip earthquakes on the San Andreas Fault. Hans Jenny famously researched the pygmy forests of the Mendocino and Sonoma county marine terraces. The marine terrace's "ecological staircase" of Salt Point State Park is also bound by the San Andreas Fault. +Along the coasts of South America marine terraces are present, where the highest ones are situated where plate margins lie above subducted oceanic ridges and the highest and most rapid rates of uplift occur. At Cape Laundi, Sumba Island, Indonesia an ancient patch reef can be found at 475 m (1,558 ft) above sea level as part of a sequence of coral reef terraces with eleven terraces being wider than 100 m (330 ft). The coral marine terraces at Huon Peninsula, New Guinea, which extend over 80 km (50 mi) and rise over 600 m (2,000 ft) above present sea level are currently on UNESCO's tentative list for world heritage sites under the name Houn Terraces - Stairway to the Past. +Other considerable examples include marine terraces rising to 360 m (1,180 ft) on some Philippine Islands and along the Mediterranean Coast of North Africa, especially in Tunisia, rising to 400 m (1,300 ft). + +== Related coastal geography == +Uplift can also be registered through tidal notch sequences. Notches are often portrayed as lying at sea level; however, notch types form a continuum from wave notches formed in quiet conditions at sea level to surf notches formed in more turbulent conditions and as much as 2 m (6.6 ft) above sea level. As stated above, there was at least one higher sea level during the Holocene, so some notches may not contain a tectonic component in their formation. + +== See also == + +== References == + +== External links == + +Notes at NAHSTE +US Geological Survey Marine Terrace Fact Sheet - Wikimedia link, USGS link \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Rauk-0.md b/data/en.wikipedia.org/wiki/Rauk-0.md new file mode 100644 index 000000000..d1ecf7c2a --- /dev/null +++ b/data/en.wikipedia.org/wiki/Rauk-0.md @@ -0,0 +1,42 @@ +--- +title: "Rauk" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Rauk" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:14.055844+00:00" +instance: "kb-cron" +--- + +A rauk is a column-like landform in Sweden, often equivalent to a stack. Rauks often occur in groups called raukfält 'rauk fields'. The limestone rauks of Gotland in the Baltic Sea are among the best known examples. + + +== Sweden == +Rauks are common on the island of Gotland, Sweden and on the smaller islands belonging to Gotland County. Fårö island in Gotland, is particularly rich in rauks. While Fårö is on the northern end of Gotland Holmhällars raukfält at Vamlingbo in the southern end of Gotland is also rich in rauks. Rauks in Gotland often occur in groups or fields, so-called raukfält. Rauks can be found both near Gotland's many cliffs or far away from these. +Other localities with rauks include Byrum on northwestern Öland neighboring Blå Jungfrun island, Hovs Hallar and Kullaberg in northwestern Scania and Härnön in northern Sweden's High Coast. Rauks on Öland are made up of limestone. A few rauks are located in the Scandinavian Mountains in northern Sweden's Sarek and Padjelanta national parks. + + +== Norway == + +In Norway, there are rauks in Trollholmsund where, according to local lore, the rauks are petrified trolls. In Trollholmsund, rauks are made up of dolomite rock. Varanger Peninsula in northern Norway is rich in rauks and they also occur elsewhere along the Finnmark coastline. +In Norway the term rauk is also applied to isolated residual mountains in the flat strandflat landscape along the coast. + + +== Geology == + +Rauks are usually formed by wave erosion. On Öland and Gotland, rauks are chiefly formed along or near the escarpment known as the Baltic Klint. Gotland rauks consist of limestone representing reefs that existed in the Silurian period. As waves batter against limestone cliffs, pre-existing vertical fractures begin to erode and widen. Eventually this leads to the formation of caves that merge, and the remaining central rock has now become rauks. +The rauks of Gotland formed after the last ice age. It is unclear to which extent different rauks in Gotland started to form from a cliffed coast, a dissected coast or from glacial landforms. A comparison of photographs from 1900 and from 1966 has shown that some rauks had been destroyed during that period. +Carl Linnaeus, who visited Gotland in 1741, was the first scientist to describe rauks. He called them stenjättar (stone giants) while also noting the ruiniform shape of same rauks. +In Sarek National Park rauks originate as aeolian landforms, thus, contrary to other rauks, they are shaped more by wind than by water. These rauks are made of sandstone that belongs to the Sierggavággenappe (Swedish: Sierggavággeskollan) of the Scandinavian Caledonides. + + +== See also == +Byrums raukar +Hoburgen + + +== References == + + +== External links == + The dictionary definition of Rauk at Wiktionary \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Redox_gradient-0.md b/data/en.wikipedia.org/wiki/Redox_gradient-0.md new file mode 100644 index 000000000..c97f8285f --- /dev/null +++ b/data/en.wikipedia.org/wiki/Redox_gradient-0.md @@ -0,0 +1,68 @@ +--- +title: "Redox gradient" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Redox_gradient" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:15.330873+00:00" +instance: "kb-cron" +--- + +A redox gradient is a series of reduction-oxidation (redox) reactions sorted according to redox potential. The redox ladder displays the order in which redox reactions occur based on the free energy gained from redox pairs. These redox gradients form both spatially and temporally as a result of differences in microbial processes, chemical composition of the environment, and oxidative potential. Common environments where redox gradients exist are coastal marshes, lakes, contaminant plumes, and soils. +The Earth has a global redox gradient with an oxidizing environment at the surface and increasingly reducing conditions below the surface. Redox gradients are generally understood at the macro level, but characterization of redox reactions in heterogeneous environments at the micro-scale require further research and more sophisticated measurement techniques. + + +== Measuring redox conditions == +Redox conditions are measured according to the redox potential (Eh) in volts, which represents the tendency for electrons to transfer from an electron donor to an electron acceptor. Eh can be calculated using half reactions and the Nernst equation. An Eh of zero represents the redox couple of the standard hydrogen electrode H+/H2, a positive Eh indicates an oxidizing environment (electrons will be accepted), and a negative Eh indicates a reducing environment (electrons will be donated). In a redox gradient, the most energetically favorable chemical reaction occurs at the "top" of the redox ladder and the least energetically favorable reaction occurs at the "bottom" of the ladder. +Eh can be measured by collecting samples in the field and performing analyses in the lab, or by inserting an electrode into the environment to collect in situ measurements. Typical environments to measure redox potential are in bodies of water, soils, and sediments, all of which can exhibit high levels of heterogeneity. Collecting a high number of samples can produce high spatial resolution, but at the cost of low temporal resolution since samples only reflect a singular a snapshot in time. In situ monitoring can provide high temporal resolution by collecting continuous real-time measurements, but low spatial resolution since the electrode is in a fixed location. +Redox properties can also be tracked with high spatial and temporal resolution through the use of induced-polarization imaging, however, further research is needed to fully understand contributions of redox species to polarization. + + +== Environmental conditions == +Redox gradients are commonly found in the environment as functions of both space and time, particularly in soils and aquatic environments. Gradients are caused by varying physiochemical properties including availability of oxygen, soil hydrology, chemical species present, and microbial processes. Specific environments that are commonly characterized by redox gradients include waterlogged soils, wetlands, contaminant plumes, and marine pelagic and hemipelagic sediments. +The following is a list of common reactions that occur in the environment in order from oxidizing to reducing (organisms performing the reaction in parentheses): + +Aerobic respiration (aerobes: aerobic organisms) +Denitrification (denitrifiers: denitrifying bacteria) +Manganese reduction (Manganese reducers) +Iron reduction (iron reducers: iron-reducing bacteria) +Sulfate reduction (sulfate reducers: Sulfur-reducing bacteria) +Methanogenesis (methanogens) + + +=== Aquatic environments === +Redox gradients form in water columns and their sediments. Varying levels of oxygen (oxic, suboxic, hypoxic) within the water column alter redox chemistry and which redox reactions can occur. Development of oxygen minimum zones also contributes to formation of redox gradients. +Benthic sediments exhibit redox gradients produced by variations in mineral composition, organic matter availability, structure, and sorption dynamics. Limited transport of dissolved electrons through subsurface sediments, combined with varying pore sizes of sediments creates significant heterogeneity in benthic sediments. Oxygen availability in sediments determines which microbial respiration pathways can occur, resulting in a vertical stratification of redox processes as oxygen availability decreases with depth. + + +=== Terrestrial environments === +Soil Eh is also largely a function of hydrological conditions. In the event of a flood, saturated soils can shift from oxic to anoxic, creating a reducing environment as anaerobic microbial processes dominate. Moreover, small anoxic hotspots may develop within soil pore spaces, creating reducing conditions. With time, the starting Eh of a soil can be restored as water drains and the soil dries out. Soils with redox gradients formed by ascending groundwater are classified as gleysols, while soils with gradients formed by stagnant water are classified as stagnosols and planosols. +Soil Eh generally ranges from −300 to +900 mV. The table below summarizes typical Eh values for various soil conditions: + +Generally accepted Eh limits that are tolerable by plants are +300 mV < Eh < +700 mV. 300 mV is the boundary value that separates aerobic from anaerobic conditions in wetland soils. Redox potential (Eh) is also closely tied to pH, and both have significant influence on the function of soil-plant-microorganism systems. The main source of electrons in soil is organic matter. Organic matter consumes oxygen as it decomposes, resulting in reducing soil conditions and lower Eh. + + +== Role of microorganisms == +Redox gradients form based on resource availability and physiochemical conditions (pH, salinity, temperature) and support stratified communities of microbes. Microbes carry out differing respiration processes (methanogenesis, sulfate reduction, etc.) based on the conditions around them and further amplify redox gradients present in the environment. However, distribution of microorganisms cannot solely be determined from thermodynamics (redox ladder), but is also influenced by ecological and physiological factors. +Redox gradients form along contaminant plumes, in both aquatic and terrestrial settings, as a function of the contaminant concentration and the impacts it has on relevant chemical processes and microbial communities. The highest rates of organic pollutant degradation along a redox gradient are found at the oxic-anoxic interface. In groundwater, this oxic-anoxic environment is referred to as the capillary fringe, where the water table meets soil and fills empty pores. Because this transition zone is both oxic and anoxic, electron acceptors and donors are in high abundance and there is a high level of microbial activity, leading to the highest rates of contaminant biodegradation. +Benthic sediments are heterogeneous in nature and subsequently exhibit redox gradients. Due to this heterogeneity, gradients of reducing and oxidizing chemical species do not always overlap enough to support electron transport needs of niche microbial communities. Cable bacteria have been characterized as sulfide-oxidizing bacteria that assist in connecting these areas of undersupplied and excess electrons to complete the electron transport for otherwise unavailable redox reactions. +Biofilms, found in tidal flats, glaciers, hydrothermal vents, and at the bottoms of aquatic environments, also exhibit redox gradients. The community of microbes—often metal- or sulfate-reducing bacteria—produces redox gradients on the micrometer scale as a function of spatial physiochemical variability. +See sulfate-methane transition zone for coverage of microbial processes in SMTZs. + + +== See also == + +Anaerobic respiration +Chemocline +Gibbs free energy +Dead zone (ecology) +Hypoxia (environmental) +Marine sediment +Redox +Redox potential +Remineralization +Sediment-water interface +Sulfate-methane transition zone + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Retraction_Watch-0.md b/data/en.wikipedia.org/wiki/Retraction_Watch-0.md index 556bd99d8..8d548f727 100644 --- a/data/en.wikipedia.org/wiki/Retraction_Watch-0.md +++ b/data/en.wikipedia.org/wiki/Retraction_Watch-0.md @@ -4,7 +4,7 @@ chunk: 1/1 source: "https://en.wikipedia.org/wiki/Retraction_Watch" category: "reference" tags: "science, encyclopedia" -date_saved: "2026-05-05T07:02:47.716596+00:00" +date_saved: "2026-05-05T07:37:19.724506+00:00" instance: "kb-cron" --- diff --git a/data/en.wikipedia.org/wiki/Ridge_push-0.md b/data/en.wikipedia.org/wiki/Ridge_push-0.md new file mode 100644 index 000000000..0272ac816 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Ridge_push-0.md @@ -0,0 +1,45 @@ +--- +title: "Ridge push" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Ridge_push" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:16.692410+00:00" +instance: "kb-cron" +--- + +Ridge push (also known as gravitational slides or sliding plate force) is a proposed driving force for plate motion in plate tectonics that occurs at mid-ocean ridges as the result of the rigid lithosphere sliding down the hot, raised asthenosphere below mid-ocean ridges. Although it is called ridge push, the term is somewhat misleading; it is actually a body force that acts throughout an ocean plate, not just at the ridge, as a result of gravitational pull. The name comes from earlier models of plate tectonics in which ridge push was primarily ascribed to upwelling magma at mid-ocean ridges pushing or wedging the plates apart. + + +== Mechanics == + +Ridge push is the result of gravitational forces acting on the young, raised oceanic lithosphere around mid-ocean ridges, causing it to slide down the similarly raised but weaker asthenosphere and push on lithospheric material farther from the ridges. +Mid-ocean ridges are long underwater mountain chains that occur at divergent plate boundaries in the ocean, where new oceanic crust is formed by upwelling mantle material as a result of tectonic plate spreading and relatively shallow (above ~60 km) decompression melting. The upwelling mantle and fresh crust are hotter and less dense than the surrounding crust and mantle, but cool and contract with age until reaching equilibrium with older crust at around 90 Ma. This produces an isostatic response that causes the young regions nearest the plate boundary to rise above older regions and gradually sink with age, producing the mid-ocean ridge morphology. The greater heat at the ridge also weakens rock closer to the surface, raising the boundary between the brittle lithosphere and the weaker, ductile asthenosphere to create a similar elevated and sloped feature underneath the ridge. +These raised features produce ridge push; gravity pulling down on the lithosphere at the mid-ocean ridge is mostly opposed by the normal force from the underlying rock, but the remainder acts to push the lithosphere down the sloping asthenosphere and away from the ridge. Because the asthenosphere is weak, ridge push and other driving forces are enough to deform it and allow the lithosphere to slide over it, opposed by drag at the lithosphere-asthenosphere boundary and resistance to subduction at convergent plate boundaries. Ridge push is mostly active in lithosphere younger than 90 Ma, after which it has cooled enough to reach thermal equilibrium with older material and the slope of the lithosphere-asthenosphere boundary becomes effectively zero. + + +== History == + + +=== Early ideas (1912–1962) === +Despite its current status as one of the driving forces of plate tectonics, ridge push was not included in any of Alfred Wegener's 1912-1930 proposals of continental drift, which were produced before the discovery of mid-ocean ridges and lacked any concrete mechanisms by which the process might have occurred. Even after the development of acoustic depth sounding and the discovery of global mid-ocean ridges in the 1930s, the idea of a spreading force acting at the ridges was not mentioned in scientific literature until Harry Hess's proposal of seafloor spreading in 1960, which included a pushing force at mid-ocean ridges as a result of upwelling magma wedging the lithosphere apart. + + +=== Gravitational models === +In 1964 and 1965, Egon Orowan proposed the first gravitational mechanism for spreading at mid-ocean ridges, postulating that spreading can be derived from the principles of isostasy. In Orowan's proposal, pressure within and immediately under the elevated ridge is greater than the pressure in the oceanic crust to either side due to the greater weight of overlying rock, forcing material away from the ridge, while the lower density of the ridge material relative to the surrounding crust would gradually compensate for the greater volume of rock down to the depth of isostatic compensation. Similar models were proposed by Lliboutry in 1969, Parsons and Richer in 1980, and others. In 1969, Hales proposed a model in which the raised lithosphere of the mid-ocean ridges slid down the elevated ridge, and in 1970 Jacoby proposed that the less dense material and isostasy of Orowan and others' proposals produced uplift which resulted in sliding similar to Hales' proposal. The term "ridge push force" was coined by Forsyth and Uyeda in 1975. + + +== Significance == +Early models of plate tectonics, such as Harry Hess's seafloor spreading model, assumed that the motions of plates and the activity of mid-ocean ridges and subduction zones were primarily the result of convection currents in the mantle dragging on the crust and supplying fresh, hot magma at mid-ocean ridges. Further developments of the theory suggested that some form of ridge push helped supplement convection in order to keep the plates moving, but in the 1990s, calculations indicated that slab pull, the force that a subducted section of plate exerts on the attached crust on the surface, was an order of magnitude stronger than ridge push. As of 1996, slab pull was generally considered the dominant mechanism driving plate tectonics. Modern research, however, indicates that the effects of slab pull are mostly negated by resisting forces in the mantle, limiting it to only 2-3 times the effective strength of ridge push forces in most plates, and that mantle convection is probably much too slow for drag between the lithosphere and the asthenosphere to account for the observed motion of the plates. This restores ridge push as one of the dominant factors in plate motion. + + +=== Opposing forces === +Ridge push is primarily opposed by plate drag, which is the drag force of the rigid lithosphere moving over the weaker, ductile asthenosphere. Models estimate that ridge push is probably just sufficient to overcome plate drag and maintain the motion of the plate in most areas. Slab pull is similarly opposed by resistance to the subduction of the lithosphere into the mantle at convergent plate boundaries. + + +=== Notable qualifications === +Research by Rezene Mahatsente indicates that the driving stresses caused by ridge push would be dissipated by faulting and earthquakes in plate material containing large quantities of unbound water, but they conclude that ridge push is still a significant driving force in existing plates because of the rarity of intraplate earthquakes in the ocean. +In plates with particularly small or young subducting slabs, ridge push may be the predominant driving force in the plate's motion. According to Stefanick and Jurdy, the ridge push force acting on the South American plate is approximately 5 times the slab pull forces acting at its subducting margins because of the small size of the subducting slabs at the Scotia and Caribbean margins. The Nazca plate also experiences relatively small slab pull, approximately equal to its ridge push, because the plate material is young (no more than 50 million years old) and therefore less dense, with less tendency to sink into the mantle. This also causes the subducting Nazca slab to experience flat slab subduction, one of the few places in the world where this currently occurs. + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Rip_current-0.md b/data/en.wikipedia.org/wiki/Rip_current-0.md new file mode 100644 index 000000000..0148fea03 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Rip_current-0.md @@ -0,0 +1,23 @@ +--- +title: "Rip current" +chunk: 1/3 +source: "https://en.wikipedia.org/wiki/Rip_current" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:18.065557+00:00" +instance: "kb-cron" +--- + +A rip current (or just rip) is a specific type of water current that can occur near beaches where waves break. A rip is a strong, localized, and narrow current of water that moves directly away from the shore, cutting through the lines of breaking waves, like a river flowing out to sea. The force of the current in a rip is strongest and fastest next to the surface of the water. +Rip currents can be hazardous to people in the water. Swimmers who are caught in a rip current and who do not understand what is happening, or who may not have the necessary water skills, may panic, or they may exhaust themselves by trying to swim directly against the flow of water. Because of these factors, rip currents are the leading cause of rescues by lifeguards at beaches. In the United States they have caused an average of 71 deaths by drowning per year between 2013 and 2022. +A rip current is not the same thing as undertow, although that term is used incorrectly when referred to a rip current. Contrary to popular belief, neither rip nor undertow can pull a person down and hold them under the water. A rip simply carries floating objects, including people, out to just beyond the zone of the breaking waves, at which point the current dissipates and releases everything it is carrying. + +== Causes and occurrence == +A rip current forms because wind and breaking waves push surface water towards the land. This causes a slight rise in the water level along the shore. This excess water will tend to flow back to the open water via the route of least resistance. When there is a local area which is slightly deeper, such as a break in an offshore sand bar or reef, this can allow water to flow offshore more easily, and this will initiate a rip current through that gap. +Water that has been pushed up near the beach flows along the shore towards the outgoing rip as "feeder currents". The excess water flows out at a right angle to the beach, in a tight current called the "neck" of the rip. The "neck" is where the flow is most rapid. When the water in the rip current reaches outside of the lines of breaking waves, the flow disperses sideways, loses power, and dissipates in what is known as the "head" of the rip. +Rip currents can form by the coasts of oceans, seas, and large lakes, whenever there are waves of sufficient energy. Rip currents often occur on a gradually shelving shore, where breaking waves approach the shore parallel to it, or where underwater topography encourages outflow at one specific area. Baïnes are one of the patterns identified to be producing rip currents. The location of rip currents can be difficult to predict. Some tend to recur always in the same places, but others can appear and disappear suddenly at various locations along the beach. The appearance and disappearance of rip currents is dependent upon the bottom topography and the direction from which the surf and swells are coming. +Rip currents occur wherever there is strong longshore variability in wave breaking. This variability may be caused by such features as sandbars, by piers and jetties, and even by crossing wave trains. They are often located in places where there is a gap in a reef, or low area on a sandbar. Rip currents, once they have formed, may deepen the channel through a sandbar. +Rip currents are usually quite narrow, but they tend to be more common, wider, and faster, when and where breaking waves are large and powerful. Local underwater topography makes some beaches more likely to have rip currents. A few beaches, such as the Hanakāpīʻai Beach, are notorious in this respect. +Although "rip tide" is a misnomer, in areas of significant tidal range, rip currents may only occur at certain stages of the tide, when the water is shallow enough to cause the waves to break over a sand bar, but deep enough for the broken wave to flow over the bar. In parts of the world with a big difference between high tide and low tide, and where the shoreline shelves gently, the distance between a bar and the shoreline may vary from a few meters to a kilometer or more, depending whether it is high tide or low tide. +A fairly common misconception is that rip currents can pull a swimmer down, under the surface of the water. This is not true, and in reality a rip current is strongest close to the surface, as the flow near the bottom is slowed by friction. +The surface of a rip current can often appear to be a relatively smooth area of water, without any breaking waves, and this deceptive appearance may cause some beach-goers to believe that it is a suitable place to enter the water. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Rip_current-1.md b/data/en.wikipedia.org/wiki/Rip_current-1.md new file mode 100644 index 000000000..d04eacfba --- /dev/null +++ b/data/en.wikipedia.org/wiki/Rip_current-1.md @@ -0,0 +1,35 @@ +--- +title: "Rip current" +chunk: 2/3 +source: "https://en.wikipedia.org/wiki/Rip_current" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:18.065557+00:00" +instance: "kb-cron" +--- + +=== Technical description === +A more detailed and technical description of rip currents requires understanding the concept of radiation stress. Radiation stress is the force (or momentum flux) that is exerted on the water column by the presence of the wave. When a wave reaches shallow water and shoals, it increases in height prior to breaking. During this increase in height, radiation stress increases, because of the force exerted by the weight of the water that has been pushed upwards. +To balance this, the local mean surface level drops. This is known as the "setdown". When the wave breaks and starts reducing in height, the radiation stress decreases as the amount of water that is elevated decreases. When this happens, the mean surface level increases—this is known as the "setup". +In the formation of a rip current, a wave propagates over a sandbar with a gap in it. When this happens, most of the wave breaks on the sandbar, leading to setup. The part of the wave that propagates over the gap does not break, and the setdown continues in that part. Because of this phenomenon, the mean water surface over the rest of the sandbar is higher than that which is over the gap. The result is a strong flow outward through the gap. This strong flow is the rip current. +The vorticity and inertia of rip currents have been studied. From a model of the vorticity of a rip current done at Scripps Institute of Oceanography, it was found that as a fast rip current extends away from shallow water, the vorticity of the current increases, and the width of the current decreases. This model acknowledges that friction plays a role and waves are irregular in nature. From data from Sector-Scanning Doppler Sonar at Scripps Institute of Oceanography, it was found that rip currents in La Jolla, California, lasted several minutes, that they reoccurred one to four times per hour, and that they created a wedge with a 45° arch and a radius of 200–400 meters (660–1,310 ft). + +== Visible characteristics == + +Rip currents have a characteristic appearance, and, with some experience, they can be visually identified from the shore before entering the water. This is helpful to lifeguards, swimmers, surfers, boaters, divers and other water users, who may need to avoid a rip, or in some cases make use of the flow. +Rip currents often look somewhat like a road or river running straight out to sea. They are easiest to notice and identify when the zone of breaking waves is viewed from a high vantage point. The following are some visual characteristics that can be used to identify a rip: + +A noticeable break in the pattern of the waves – the water often looks flat at the rip, in contrast to the lines of breaking waves on either side of the rip. +A "river" of foam – the surface of the rip sometimes looks foamy, because the current is carrying foam from the surf out to open water. +Different color – the rip may differ in color from the surrounding water. It is often more opaque, cloudier, or muddier, and so, depending on the angle of the sun, the rip may show as darker or lighter than the surrounding water. +It is sometimes possible to see that foam or floating debris on the surface of the rip is moving out, away from the shore. In contrast, in the surrounding areas of breaking waves, floating objects and foam are being pushed towards the shore. +These characteristics are helpful in learning to recognize and understand the nature of rip currents. Learning these signs can enable a person to recognize the presence and position of rips before entering the water, which is an important skill as studies show the majority of people are unable to identify a rip current and therefore unable to identify safe places to swim. +In the United States, some beaches have signs created by the National Oceanic and Atmospheric Administration (NOAA) and United States Lifesaving Association, explaining what a rip current is and how to escape one. These signs are titled, "Rip Currents; Break the Grip of the Rip". Two of these signs are shown in the image at the top of this article. Beachgoers can get information from lifeguards, who are always watching for rip currents, and who will move their safety flags so that swimmers can avoid rips. + +== Danger to swimmers == + +Rip currents are a potential source of danger for people in shallow water with breaking waves, whether this is in seas, oceans or large lakes. Rip currents are the proximate cause of 80% of rescues carried out by beach lifeguards. +Rip currents typically flow at about 0.5 m/s (1.6 ft/s). They can be as fast as 2.5 m/s (8.2 ft/s), which is faster than any human can swim. Most rip currents are fairly narrow, and even the widest rip currents are not very wide. Swimmers can usually exit the rip easily by swimming at a right angle to the flow, parallel to the beach. Swimmers who are unaware of this fact may exhaust themselves trying unsuccessfully to swim directly against the flow. The flow of the current fades out completely at the head of the rip, outside the zone of the breaking waves, so there is a definite limit to how far the swimmer will be taken out to sea by the flow of a rip current. +In a rip current, death by drowning occurs when a person has limited water skills and panics, or when a swimmer persists in trying to swim to shore against a strong rip current, and eventually becomes exhausted and drowns. +According to the NOAA rip currents caused an average of 71 deaths annually in the United States over the ten years ending in 2022 (with 69 in 2022). +A 2013 Australian study found that rips killed more people in Australia than bushfires, floods, cyclones and shark attacks combined. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Rip_current-2.md b/data/en.wikipedia.org/wiki/Rip_current-2.md new file mode 100644 index 000000000..fe54dc067 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Rip_current-2.md @@ -0,0 +1,37 @@ +--- +title: "Rip current" +chunk: 3/3 +source: "https://en.wikipedia.org/wiki/Rip_current" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:18.065557+00:00" +instance: "kb-cron" +--- + +=== Survival === +People caught in a rip current may notice that they are moving away from the shore quite rapidly. Often, it is not possible to swim directly back to shore against a rip current, so this is not recommended. Contrary to popular misunderstanding, a rip does not pull a swimmer under the water. It carries the swimmer away from the shore in a narrow band of moving water. +A rip current is like a moving treadmill. Safety guidance commonly emphasizes remaining calm and avoiding exhausting attempts to swim directly against the current. Instead, swimmers are advised to swim parallel to the shoreline until free of the narrow offshore flow, then return to shore at an angle. If unable to escape by swimming, floating or treading water and signaling for help is often recommended until the current weakens or assistance arrives. +As an alternative, people who are caught in a strong rip can simply relax, either floating or treading water, and allow the current to carry them until it dissipates completely once it is beyond the surf line. Then the person can signal for help, or swim back through the surf, doing so diagonally, away from the rip and towards the shore. +It is necessary for coastal swimmers to understand the danger of rip currents, to learn how to recognize them, and how to deal with them. And when possible, it is necessary that people enter the water only in areas where lifeguards are on duty. +In a planned trial in a large rip current at Muriwai Beach in New Zealand, an Australian researcher from the School of Biological, Earth and Environmental Sciences, UNSW Sydney found that "just swim to the side" would not work as the rip current was too wide to see its sides, and said that, despite a rescue boat being near, he was unable to relax and not panic. The current took him 300 meters (980 ft) along the beach in a channel feeding the rip current, and then 400 meters (1,300 ft) offshore at "speeds approaching those of swimming world records". + +== Uses == +Experienced and knowledgeable water users, including surfers, body boarders, divers, surf lifesavers and kayakers, when they wish to get out beyond the breaking waves, will sometimes use a rip current as a rapid and effortless means of transportation. + +== See also == + +Cross sea +Longshore drift +Rip current statement – warnings issued by the U.S. National Weather Service +Undertow (water waves) +Rip tide +Baïne + +== References == + +== External links == + Media related to Rip currents at Wikimedia Commons + +NOAA glossary of terms used in describing rip currents +Example of a Rip Tide on YouTube +How to Spot a Rip Current on YouTube by Surf Life Saving Australia showcasing several signs to spot rips. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Science-Based_Medicine-0.md b/data/en.wikipedia.org/wiki/Science-Based_Medicine-0.md new file mode 100644 index 000000000..df7ed74b4 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Science-Based_Medicine-0.md @@ -0,0 +1,47 @@ +--- +title: "Science-Based Medicine" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Science-Based_Medicine" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:20.913143+00:00" +instance: "kb-cron" +--- + +Science-Based Medicine is a website and blog with articles covering issues in science and medicine, especially medical scams and practices. Founded in 2008, it is owned and operated by the New England Skeptical Society, and run by Steven Novella and David Gorski. + + +== History == +Started as a skeptical medical blog with five writers, Science-Based Medicine (SBM) launched on January 1, 2008. Steven Novella, Harriet Hall, and David Gorski were founding editors, along with Mark Crislip and Kimball Atwood. +Science-Based Medicine is owned and operated by the New England Skeptical Society (NESS), where Novella, a clinical neurologist at Yale University and the executive editor of SBM, has served as president since its inception. Gorski, a surgical oncologist at Wayne State University, is the managing editor for SBM. +The blog was affiliated with the former Society for Science-Based Medicine (SfSBM), an opinionated education and advocacy group, that registered in 2014 as a Florida nonprofit corporation led by Mark Crislip. The SfSBM was dissolved in 2020, with the Center for Inquiry receiving its funds as a donation and considered by the SfSBM's board to continue its work, following a period of time where SfSBM had merged with SBM. +Other key contributors have included writer Paul Ingraham (2010–2016) and Wallace Sampson, an editor and regular contributor to SBM until his death in 2017. + + +== Content and format == +Science-Based Medicine is a website in blog format that examines controversies in science and medicine, especially medical scams and practices. SBM is known for persistently challenging alternative medicine and for opposing university funding from advocates of integrative medicine. David Freedman, writing for The Atlantic in 2011, described SBM as "an influential blog that has tirelessly gone after alternative medicine." +Editorial staff say that the best medicine is based on scientific principles, includes prior plausibility, and is not based on evidence alone. Gorski, Novella, and Atwood have argued that science-based medicine differs in focus from evidence-based medicine and stress that randomized clinical trials should only be conducted when warranted by ample preclinical evidence to justify the effort, time, and expenses involved. For a science-based approach, Novella supports minimizing or eliminating research on implausible treatments, and points out that decades are often required for clinical research to become supported by rigorous, conclusive trials, during which time decisions must be made, preferably guided by and screened by plausibility criteria. +In a systematic survey of web sites providing material on complementary and alternative medicine from 2018, medical education researcher Annie Chen and colleagues listed Science-Based Medicine alongside WebMD as an example of an "information service" providing articles on health and illness. +During the COVID-19 pandemic, Science-Based Medicine collected and debunked misinformation that had spread through social media, such as the false claim that COVID-19 vaccines could cause infertility. + + +== Retractions == +On June 15, 2021, Science-Based Medicine published a book review of Abigail Shrier's Irreversible Damage written by founding editor Harriet Hall. In her review, Hall wrote that Shrier's book had raised legitimate concerns about the science surrounding drug treatments for gender dysphoria in children and that there was a lack of quality scientific studies on the subject. Several days after the review was published, Novella and Gorski replaced the review with a retraction notice and responded with a review of their own, the first of six SBM posts rejecting Shrier's claims and addressing the retraction. +Skeptic magazine republished Hall's review, and she remained one of three editors at SBM along with Novella and Gorski after the retraction until her death in 2023. + + +== Legal == + +In 2014, Novella was sued by Edward Tobinick, a doctor claiming to treat neurological conditions, over two blog posts on Science-Based Medicine critical of off-label use of the drug Etanercept by Tobinick's medical clinic. Novella had said that it was "unethical for physicians to practice outside of their area of competence and expertise". The lawsuit, filed by Tobinick against Novella, the Society for Science-Based Medicine, Inc., and SGU Productions, LLC was resolved after the court ruled in favor of the defendants. + + +== See also == +Evidence-based practice +Quackwatch + + +== References == + + +== External links == +Official website \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/ScienceBlogs-0.md b/data/en.wikipedia.org/wiki/ScienceBlogs-0.md new file mode 100644 index 000000000..b9022e5c5 --- /dev/null +++ b/data/en.wikipedia.org/wiki/ScienceBlogs-0.md @@ -0,0 +1,64 @@ +--- +title: "ScienceBlogs" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/ScienceBlogs" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:22.218337+00:00" +instance: "kb-cron" +--- + +ScienceBlogs was an invitation-only blog network and virtual community that operated initially for 11 years, from 2006 to 2017. It was created by Seed Media Group to enhance public understanding of science. Each blog had its own theme, specialty and author(s) and was not subject to editorial control. Authors included active scientists working in industry, universities and medical schools as well as college professors, physicians, professional writers, graduate students, and post-docs. On 24 January 2015, 19 of the blogs had seen posting in the past month. Eleven of these had been on ScienceBlogs since 2006. ScienceBlogs shut down at the end of October 2017. In late August 2018, the website's front page displayed a notice suggesting it was about to become active once again. + + +== History == +ScienceBlogs was launched in January 2006 with 15 blogs on the network. Seed Media Group had initially contacted the existing science blogging network ScienceBlog.com about a possible partnership, but later launched independently with a similar name and web address. For the launch blogs, Seed invited some of the best-known independent science bloggers and allowed them to blog about whichever subjects they wished. Revenue was generated through advertisements sold to companies who wished to attract "bright, curious consumers who buy products like automobiles, books, cellphones, computers, liquor, music and watches." +As a result of the free rein given to bloggers and the incentive to increase traffic, bloggers on the network often discussed hot topics such as politics and religion in addition to science. These topics frequently incited heated arguments in the comment threads and bloggers on the network sometimes got into arguments with each other over a series of posts. +ScienceBlogs and Seed received some notable awards at the end of their first year of activity, including the 2006 UTNE Independent Press Award for Best Science/Technology Coverage being granted to Seed, in large part due to the success of ScienceBlogs. Additionally, two blogs on the network received Weblog awards: Pharyngula for Best Science Blog and Respectful Insolence for Best Medical/Health Issues Blog. +The creators of ScienceBlogs expanded their collection of hosted blogs in three major waves, supplemented by individual additions along the way. Some of the most trafficked blogs included Pharyngula, Respectful Insolence, Good Math Bad Math, Deltoid, Cognitive Daily, Living the Scientific Life (Scientist, Interrupted) and On Becoming a Domestic and Laboratory Goddess. +According to Technorati, as of 7 July 2007, ScienceBlogs had an "authority" of 9,581 and its number of inbound links ranked it 37th among blogs worldwide. As of 14 March 2008, Quantcast charted it as having over 1.1 million monthly unique visitors, 65% of whom were from the United States. +As of February 2009, ScienceBlogs hosted 75 blogs dedicated to various fields of research. In April 2011, ScienceBlogs was taken over by National Geographic. While Seed would still maintain ownership of the site, National Geographic would acquire editorial control and responsibility for advertising sales on the site. +ScienceBlogs launched a German language edition of the site, ScienceBlogs.de, in 2008 in partnership with Hubert Burda Media. As of 7 December 2010, the site hosted 35 blogs. ScienceBlogs Brazil debuted in March 2009 with 23 Portuguese language blogs. + + +=== "PepsiGate" === +In June 2010, ScienceBlogs started a blog which was sponsored by PepsiCo and was to be written by their employees. This led to backlash by many of the bloggers on ScienceBlogs who considered this to be an unethical mix of advertising and journalism, and the PepsiCo blog was withdrawn from ScienceBlogs. This affair was informally named "PepsiGate". By the middle of July approximately a quarter of the bloggers had left ScienceBlogs. Subsequently, some bloggers such as PZ Myers of Pharyngula announced they were going on strike as part of a general feeling that the people running Seed had failed to respond to concerns surrounding the incident. Seed Media responded by killing off Food Frontiers, the Pepsico sponsored blog, but that didn't stop the defections. According to PZ Myers, "The ship is sinking". A writer at the New York Times Magazine reviewed the incident and commented, "ScienceBlogs has become Fox News for the religion-baiting, peak-oil crowd." Some other science blogging networks were launched, including scientopia.org, scienceseeker.org and one hosted by The Guardian. In early 2015, however, eleven of the network's 2006 founding-generation blogs were still active, including Myers's. + + +=== Demise === +On 14 October 2017, astrophysics blogger Steinn Sigurðsson publicly revealed that ScienceBlogs was due to be shut down, and David Gorski, author of the "Respectful Insolence" blog under his pseudonym Orac, stated that ScienceBlogs had "barely existed as an entity for a few years". + Astrophysics blogger Ethan Siegel reported on 22 October 2017 that ScienceBlogs had informed bloggers it "no longer had the funds to keep the site operational, and so they would be shutting down". + + +=== Revival === +In late August 2018, a note appeared on the home page which said that ScienceBlogs was now part of the Science 2.0 family and that plans were in place to make the site active once again. + + +== Awards == +2012: IQ Award + + +== Content == +ScienceBlogs consisted of ten channels, or categories, of blog entries. Each blog author decided what channel his or her individual post belongs in, and each post was indexed accordingly on the main page. The categories were: + +Life Science +Environment +Brain & Behavior +Humanities & Social Sciences +Medicine & Health +Education and Careers +Physical Science +Planet Earth +Politics +Technology + + +== See also == +Popular science + + +== References == + + +== External links == +ScienceBlogs website \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/ScienceNet-0.md b/data/en.wikipedia.org/wiki/ScienceNet-0.md new file mode 100644 index 000000000..99fee8a02 --- /dev/null +++ b/data/en.wikipedia.org/wiki/ScienceNet-0.md @@ -0,0 +1,47 @@ +--- +title: "ScienceNet" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/ScienceNet" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:23.427099+00:00" +instance: "kb-cron" +--- + +ScienceNet (Chinese: 科学网) is a science virtual community and science blog. It was launched by Science Times Media Group (STMG) and is supported by the Chinese Academy of Sciences, the Chinese Academy of Engineering, and the National Natural Science Foundation of China with the mission of establishing global Chinese science community. Since its launch on January 18, 2007, a total of 5,553 scientists and graduate students have blogged on ScienceNet. +According to the editorial board of ScienceNet, it has been ranking the top one among Chinese science websites. + + +== Bloggers == +Yu-Chi Ho, Professor, Harvard and Tsinghua University +Rao Yi, Professor and Dean, School of Life Sciences, Peking University +Shi Yigong, Professor and Dean, Department of Biological Sciences and Biotechnology, Tsinghua University +Lu Bai, Vice President of Biology R&D center, GlaxoSmithKline +Wang Hongfei, Chief Scientist, Pacific Northwest National Laboratory +Li Xiaowen, Director, Remote Sensing and GIS Research Center, Beijing Normal University +Wu Yishan, Chief Engineer, Institute of Scientific and Technical Information of China +Cao Cong, Senior research associate, State University of New York + + +== History == +January 18, 2007: official launch +April 2008: the selecting blog articles of 2007 year on ScienceNet was published — 《智者不惑》 +September–December 2008: held the first national youth science blogs competition +July 2009: the selecting blog articles of 2008 year on ScienceNet was published — 《流动的科学》 +November 2009: the selecting blog articles of Yu-Chi Ho on ScienceNet was published — 《科学人生纵横》 +April–June 2001: held the second national youth science blogs competition +April 2010: ScienceNet opened an account on Sina Weibo + + +== Influences == +Rao Yi and Cui Keming debated on hiring policies by posting their opinions on ScienceNet and was further featured by the Editorial of magazine Nature. +Professor Chen Yongjiang posted a series of articles on ScienceNet to uncover the academic fraud case happened in Xi'an Jiaotong University. The main criminal Li Lianshen was finally fired by the university after the following report of State Media. + + +== References == + + +== External links == +(in Chinese) Official website +(in Chinese) 科学网博客首页 +(in Chinese) 科学网新浪微博 \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Science_on_the_Verge-0.md b/data/en.wikipedia.org/wiki/Science_on_the_Verge-0.md index 854db36f9..743f29088 100644 --- a/data/en.wikipedia.org/wiki/Science_on_the_Verge-0.md +++ b/data/en.wikipedia.org/wiki/Science_on_the_Verge-0.md @@ -4,7 +4,7 @@ chunk: 1/1 source: "https://en.wikipedia.org/wiki/Science_on_the_Verge" category: "reference" tags: "science, encyclopedia" -date_saved: "2026-05-05T06:28:47.091304+00:00" +date_saved: "2026-05-05T07:37:50.018185+00:00" instance: "kb-cron" --- diff --git a/data/en.wikipedia.org/wiki/Scientific_Knowledge_and_Its_Social_Problems-0.md b/data/en.wikipedia.org/wiki/Scientific_Knowledge_and_Its_Social_Problems-0.md new file mode 100644 index 000000000..c018c4535 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Scientific_Knowledge_and_Its_Social_Problems-0.md @@ -0,0 +1,31 @@ +--- +title: "Scientific Knowledge and Its Social Problems" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Scientific_Knowledge_and_Its_Social_Problems" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:51.283845+00:00" +instance: "kb-cron" +--- + +Scientific Knowledge and Its Social Problems is a 1971 book by Jerome Ravetz. It contains a reasoned illustration of science as a social process with all the failings and imperfections of other human endeavors. + + +== Content == +It is impossible to understand the social and ethical problems confronting science without recognizing the falsity of the assumption, crucial to traditional theories of science, that the results of scientific research must be essentially good and true. Dr. Ravetz demonstrates the role of choice and value-judgment, and the inevitability of error, in scientific research. +Important aspects of the book are the social construction of facts, science as a craft with essential tacit elements, the role of choice and value judgment, and the inevitability of error. The book argues that the internal quality control system of industrialized science will suffer severe problems: "The problem of quality control in science is thus at the centre of the social problems of the industrialized science of the present period." James H. Moor (1973) summarizes the main claims of Ravetz's work are as follows: "First, historically the social character of science has undergone tremendous changes. Secondly, the traditional philosophies of science which conceive of science as an activity in the pursuit of truth are obsolete. And thirdly, it is imperative to develop a new philosophy of science which accounts for the social nature of contemporary science." Ravetz analyzes the transition from basic science to 'industrialized science', with particular attention of issues of degeneration (shoddy science). He also focuses on entrepreneurial science, where a scientist becomes more concerned with research grants and power than with the quality of his scientific research. The need for 'good morale', i.e. for an ethos of science upheld by a community of peers is mentioned in relation to the danger that such an ethos may not survive 'industrialized science'. For Gowing (1974) the main difficulty of this work is the confusion among the different kinds of science addressed by the inquiry: 'natural sciences, pure and applied', versus 'any sort of disciplined inquiry', up to include 'social sciences'. + + +== Reception == +For Rothman (1974) Ravetz elucidates "the processes by which genuine and meaningful scientific knowledge accumulates. These chapters – nine in all – form the most interesting and useful part of the book. His description of the emergence and refinement of scientific facts is articulated by the argument that science is craftman's work." +The work is praised by John Ziman, for whom "we may, through books like this, achieve a new level of self-critical science." For Thomas Gieryn writing in 1998 "Ravetz is impressively prescient, but does a better job anticipating what would happen to science by the 1990s than anticipating its sociological understandings." +Anthony Jackson, takes issue against Ravetz's perceived critique of the social sciences as "immature and ineffective fields of inquiry that may be equated with folk-science". The work of Ravetz was also reviewed by Diana Crane, Ardon Lyon, Nathan Reingold, and Dael +Wolfle. +A German translation appeared in 1973, and a Japanese one in 1977 by historian of science Shigeru Nakayama. In 1996 there was a second edition with a new introduction by the author with Transaction Publishers that was reviewed by Steven Shapin. + + +== References == + + +== External links == +Book's page at Google books \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Scientific_literature-0.md b/data/en.wikipedia.org/wiki/Scientific_literature-0.md new file mode 100644 index 000000000..51ca5aa1b --- /dev/null +++ b/data/en.wikipedia.org/wiki/Scientific_literature-0.md @@ -0,0 +1,55 @@ +--- +title: "Scientific literature" +chunk: 1/3 +source: "https://en.wikipedia.org/wiki/Scientific_literature" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:58.587382+00:00" +instance: "kb-cron" +--- + +Scientific literature encompasses a vast body of academic papers that spans various disciplines within the natural and social sciences. It primarily consists of academic papers that present original empirical research and theoretical contributions. These papers serve as essential sources of knowledge and are commonly referred to simply as "the literature" within specific research fields. +The process of academic publishing involves disseminating research findings to a wider audience. Researchers submit their work to reputable journals or conferences, where it undergoes rigorous evaluation by experts in the field. This evaluation, known as peer review, ensures the quality, validity, and reliability of the research before it becomes part of the scientific literature. Peer-reviewed publications contribute significantly to advancing our understanding of the world and shaping future research endeavors. +Original scientific research first published in scientific journals constitutes primary literature. Patents and technical reports, which cover minor research results and engineering and design efforts, including computer software, are also classified as primary literature. +Secondary sources comprise review articles that summarize the results of published studies to underscore progress and new research directions, as well as books that tackle extensive projects or comprehensive arguments, including article compilations. +Tertiary sources encompass encyclopedias and similar works designed for widespread public consumption. + +== Types of scientific publications == + +Scientific literature can include the following kinds of publications: + +Scientific articles published in scientific journals. +Patents in the relevant subject (for example, biological patents and chemical patents). +Books wholly written by one author or a few co-authors. +Edited volumes, where each chapter is the responsibility of a different author or group of authors, while the editor is responsible for determining the scope of the project, keeping the work on schedule, and ensuring consistency of style and content. +Presentations at academic conferences, especially those organized by learned societies. +Government reports such as a forensic investigation conducted by a government agency such as the NTSB. +Scientific publications on the World Wide Web (although e.g. scientific journals are now commonly published on the web). +Books, technical reports, pamphlets, and working papers issued by individual researchers or research organizations on their own initiative; these are sometimes organized into a series. +Literature may also be published in areas considered to be "grey", as they are published outside of traditional channels. This material is customarily not indexed by major databases and can include manuals, theses and dissertations, or newsletters and bulletins. +The significance of different types of the scientific publications can vary between disciplines and change over time. According to James G. Speight and Russell Foote, peer-reviewed journals are the most prominent and prestigious form of publication. University presses are more prestigious than commercial press publication. The status of working papers and conference proceedings depends on the discipline; they are typically more important in the applied sciences. The value of publication as a preprint or scientific report on the web has in the past been low, but in some subjects, such as mathematics or high energy physics, it is now an accepted alternative. + +=== Scientific papers and articles === +Scientific papers have been categorized into ten types. Eight of these carry specific objectives, while the other two can vary depending on the style and the intended goal. +Papers that carry specific objectives are: + +An original article provides new information from original research supported by evidence and embodies the scientific method. +Case reports are unique events that researchers read to obtain information on the subject. While a case study may focus on only one case, it can account for context rather than an original research article. +A technical note is a description of a technique or piece of equipment that has been modified from an existing one to be new and more effective. +A pictorial essay is a series of high-quality images published for teaching purposes. +A review is a detailed analysis of recent developments on a topic. Three essential elements of performing a review article are the study's purpose, the selection of documents, and the data assessment method. They are interconnected and shape several categories of literature reviews, including a "narrative review", "descriptive review", "scoping review", "meta-analysis", and so on. +A commentary is a short summary of an author's personal experience. +Editorials are short reviews or critiques of original articles. +Letters to the editor are communications directed to the editor of an article to ask questions and provide constructive criticism. +The following two categories are variable, including for example historical articles and speeches: + +Nonscientific material: This type of material comes from the result of an article being published. It does not advance an article scientifically but instead contributes to its reputation as a scientific article. +Other: Other types of papers not listed under non-scientific material or in any of the above eight categories. They can vary depending on the objective and style of the article. + +== Scientific article == + +=== Preparation === +The actual day-to-day records of scientific information are kept in research notebooks or logbooks. These are usually kept indefinitely as the basic evidence of the work, and are often kept in duplicate, signed, notarized, and archived. The purpose is to preserve the evidence for scientific priority, and in particular for priority for obtaining patents. They have also been used in scientific disputes. Since the availability of computers, the notebooks in some data-intensive fields have been kept as database records, and appropriate software is commercially available. +The work on a project is typically published as one or more technical reports, or articles. In some fields both are used, with preliminary reports, working papers, or preprints followed by a formal article. Articles are usually prepared at the end of a project, or at the end of components of a particularly large one. In preparing such an article vigorous rules for scientific writing have to be followed. + +=== Language === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Scientific_literature-1.md b/data/en.wikipedia.org/wiki/Scientific_literature-1.md new file mode 100644 index 000000000..e94ba52cd --- /dev/null +++ b/data/en.wikipedia.org/wiki/Scientific_literature-1.md @@ -0,0 +1,34 @@ +--- +title: "Scientific literature" +chunk: 2/3 +source: "https://en.wikipedia.org/wiki/Scientific_literature" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:58.587382+00:00" +instance: "kb-cron" +--- + +Often, career advancement depends upon publishing in high-impact journals, which, especially in hard and applied sciences, are usually published in English. Consequently, scientists with poor English writing skills are at a disadvantage when trying to publish in these journals, regardless of the quality of the scientific study itself. Yet many international universities require publication in these high-impact journals by both their students and faculty. One way that some international authors are beginning to overcome this problem is by contracting with freelance copy editors who are native speakers of English and specialize in ESL (English as a second language) editing to polish their manuscripts' English to a level that high-impact journals will accept. + +=== Structure and style === + +Although the content of an article is more important than the format, it is customary for scientific articles to follow a standard structure, which varies only slightly in different subjects. Although the IMRAD structure emphasizes the organization of content, and in scientific journal articles, each section (Introduction, Methods, Results, and Discussion) has unique conventions for scientific writing style. +The following are key guidelines for formatting, although each journal etc will to some extent have its own house style: + +The title attracts readers' attention and informs them about the contents of the article. Titles are distinguished into three main types: declarative titles (state the main conclusion), descriptive titles (describe a paper's content), and interrogative titles (challenge readers with a question that is answered in the text). Some journals indicate, in their instructions to authors, the type (and length) of permitted titles. +The names and affiliations of all authors are given. In the wake of some scientific misconduct cases, publishers often require that all co-authors know and agree on the content of the article. +An abstract summarizes the work (in a single paragraph or in several short paragraphs) and is intended to represent the article in bibliographic databases and to furnish subject metadata for indexing services. +The context of previous scientific investigations should be presented, by citation of relevant documents in the existing literature, usually in a section called an "Introduction". +Empirical techniques, laid out in a section usually called "Materials and Methods", should be described in such a way that a subsequent scientist, with appropriate knowledge of and experience in the relevant field, should be able to repeat the observations and know whether he or she has obtained the same result. This naturally varies between subjects, and does not apply to mathematics and related subjects. +Similarly, the results of the investigation, in a section usually called "Results", should be presented in tabular or graphic form (image, chart, schematic, diagram or drawing). These display elements should be accompanied by a caption and should be discussed in the text of the article. +Interpretation of the meaning of the results is usually addressed in a "Discussion" or "Conclusions" section. The conclusions drawn should be based on the new empirical results while taking established knowledge into consideration, in such a way that any reader with knowledge of the field can follow the argument and confirm that the conclusions are sound. That is, acceptance of the conclusions must not depend on personal authority, rhetorical skill, or faith. +Finally, a "References" or "Literature Cited" section lists the sources cited by the authors. + +== Peer review == + +Increasing reliance on digital abstracting services and academic search engines means that the de facto acceptance in the academic discourse is predicted by the inclusion in such selective sources. Commercial providers of proprietary data include Chemical Abstracts Service, Web of Science and Scopus, while open data (and often open source, non-profit and library-led) services include DOAB, DOAJ and (for open access works) Unpaywall (based on CrossRef and Microsoft Academic records enriched with OAI-PMH data from open archives). + +== Ethics == + +The transfer of copyright from author to publisher, used by some journals, can be controversial because many authors want to propagate their ideas more widely and re-use their material elsewhere without the need for permission. Usually an author or authors circumvent that problem by rewriting an article and using other pictures. Some publishers may also want publicity for their journal so will approve facsimile reproduction unconditionally; other publishers are more resistant. +In scientific publishing, a number of key issues include and are not restricted to: \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Scientific_literature-2.md b/data/en.wikipedia.org/wiki/Scientific_literature-2.md new file mode 100644 index 000000000..a5a115cc5 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Scientific_literature-2.md @@ -0,0 +1,43 @@ +--- +title: "Scientific literature" +chunk: 3/3 +source: "https://en.wikipedia.org/wiki/Scientific_literature" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:58.587382+00:00" +instance: "kb-cron" +--- + +Honesty and integrity is a duty of each author and person, expert-reviewer and member of journal editorial boards. +The peer review process contributes to quality control and it is an essential step to ascertain the standing and originality of the research. +Redundant publications: Publications generally should contain new unpublished material. +Data fabrication is the process of purposefully changing data to make the information more in the favor of the author. +Ethical standards: Recent journal editorials presented some experience of unscrupulous activities. +Human welfare concerns: The guidelines for human experimentation started during WWII with the Nuremberg Code. It has evolved into three main principles from The Belmont Report. The subject must be able to make their own choices to protect themselves, benefits must outweigh the risks, and subjects must be evaluated for their selection and benefits must go to all of society. +Animal welfare concerns: Is the ethical care of animals in scientific experiments. The APS has set strict guidelines and regulations to stop animals from being unnecessarily harmed in experiments. These are being updated regularly by the APS and is a federal law in the United States enforced by DHHS. +Authorship: Who may claim a right to authorship? In which order should the authors be listed? +Conflicts of interest: This refers to biases due to private interest. It can be done knowingly or not. This is unethical because it makes data inaccurate. +Authorship disputes: The authorship of an article is simply the author of the article. The ethical issue with this is when there are two people that believe to be the author, but there is only one true author. There are guidelines to help pick which get authorship of the writing. The one that does not get authorship is put in the acknowledgments. The guidelines come from NIH and The Council of Science Editors. + +== History == + +In 1620, Francis Bacon was the first to describe the experimental method in his book Novum Organum. René Descartes was one of the key figures in the Scientific Revolution. He was probably the first to send his texts to colleagues asking their opinions, which became the prototype of peer review. The increased attention to epistemology in the 17th century is also linked to Cartesian views. +The first recorded editorial pre-publication peer-review occurred in 1665 by the founding editor of Philosophical Transactions of the Royal Society, Henry Oldenburg. +The term "peer review" was first used in the early 1970s. +Technical and scientific books were a specialty of David Van Nostrand, and his Engineering Magazine re-published contemporary scientific articles. + +== See also == +Acknowledgment index +Citation index +Digital object identifier +Grey literature +Open access (publishing) +Research paper mill +Scientific communication +UKSG +List of academic databases and search engines + +== References == +Robert G. Bartle (1990) "A brief history of the mathematical literature" Archived 2007-02-07 at the Wayback Machine from American Mathematical Society. + +== Footnotes == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Sea_ice-0.md b/data/en.wikipedia.org/wiki/Sea_ice-0.md new file mode 100644 index 000000000..8d504806e --- /dev/null +++ b/data/en.wikipedia.org/wiki/Sea_ice-0.md @@ -0,0 +1,33 @@ +--- +title: "Sea ice" +chunk: 1/4 +source: "https://en.wikipedia.org/wiki/Sea_ice" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:19.320016+00:00" +instance: "kb-cron" +--- + +Sea ice forms as seawater freezes. Because ice is less dense than liquid water, it floats on the ocean's surface (just like fresh water ice). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oceans. Much of the world's sea ice is enclosed within the polar ice packs in the Earth's polar regions: the Arctic ice pack of the Arctic Ocean and the Antarctic ice pack of the Southern Ocean. Polar packs naturally undergo significant yearly cycling, reaching their greatest surface extent in winter and retreating in summer. +Within the ice, salty brine channels provide habitat for microorganisms that form the base of unique food webs. The presence or absence of sea ice also shapes navigation routes, regional weather, and global ocean circulation. Sea ice plays a key role in Earth's climate. Its white surface reflects the Sun's energy back into space, helping to keep the planet cool in a process known as the albedo effect. Sea ice also insulates the ocean below, limiting the transfer of heat, water vapor, and gases such as carbon dioxide between the sea and the atmosphere. +Satellite records have shown a marked decline in Arctic sea ice extent and thickness in recent decades, a trend linked to global climate change. Antarctic sea ice shows more regional variability but is recently also experiencing declines. +Sea ice is dynamic, due to the action of winds, currents and temperature fluctuations, which lead to a wide variety of ice types and features. Sea ice differs from icebergs, which are chunks of ice shelves or glaciers that calve into the ocean. Depending on location, sea ice may contain embedded icebergs. + +== Features and types == + +Sea ice does not simply grow and melt. During its lifespan, it is very dynamic. Due to the combined action of winds, currents, water temperature and air temperature fluctuations, sea ice expanses typically undergo a significant amount of deformation. Sea ice is classified according to whether or not it is able to drift and according to its age. + +=== Physical properties === +Sea ice is a composite material made up of pure ice, liquid brine, air, and salt. The volumetric fractions of these components—ice, brine, and air—determine the key physical properties of sea ice, including thermal conductivity, heat capacity, latent heat, density, elastic modulus, and mechanical strength. Brine volume fraction depends on sea-ice salinity and temperature, while sea-ice salinity mainly depends on ice age and thickness. During the ice growth period, its bulk brine volume is typically below 5%. Air volume fraction during ice growth period is typically around 1–2 %, but may substantially increase upon ice warming. Air volume of sea ice in can be as high as 15 % in summer and 4 % in autumn. Both brine and air volumes influence sea-ice density values, which are typically around 840–910 kg/m3 for first-year ice. First-year ice has a strong seasonality of its density, with higher values around 910–920 kg/m3 in winter and lower values around 860–880 kg/m3 in summer. Density of second- and multiyear ice typically has a weaker seasonality and lower density than for first-year ice. Sea-ice density is a significant source of errors in sea-ice thickness retrieval using radar and laser satellite altimetry, resulting in uncertainties of 0.3–0.4 m. + +=== Fast ice versus drift (or pack) ice === + +Sea ice can be classified according to whether or not it is attached (or frozen) to the shoreline (or between shoals or to grounded icebergs). If attached, it is called landfast ice, or more often, fast ice (as in fastened). Alternatively and unlike fast ice, drift ice occurs further offshore in very wide areas and encompasses ice that is free to move with currents and winds. The physical boundary between fast ice and drift ice is the fast ice boundary. The drift ice zone may be further divided into a shear zone, a marginal ice zone (MIZ) and a central pack. +MIZ is the transition region between the open ocean and the more consolidated pack ice. It is commonly characterised by fragmented sea ice composed of individual floes that span a wide range of sizes. The statistical distribution of floe sizes, referred to as the floe size distribution (FSD), is an important property of the ice cover influencing processes such as wave–ice interaction, lateral melting, and momentum and heat exchange between the ocean and atmosphere.Drift ice consists of floes, individual pieces of sea ice 20 metres (66 ft) or more across. There are names for various floe sizes: small – 20 to 100 m (66 to 328 ft); medium – 100 to 500 m (330 to 1,640 ft); big – 500 to 2,000 m (1,600 to 6,600 ft); vast – 2 to 10 kilometres (1.2 to 6.2 mi); and giant – more than 10 km (6.2 mi). The term pack ice is used either as a synonym of drift ice, or to designate drift ice zone in which the floes are densely packed. The overall sea ice cover is termed the ice canopy from the perspective of submarine navigation. + +=== Classification by age === +Another classification used by scientists to describe sea ice is based on age, that is, on its development stages. These stages are: new ice, nilas, young ice, first-year and old. + +==== New ice, nilas and young ice ==== + +New ice is a general term used for recently frozen sea water that does not yet make up solid ice. It may consist of frazil ice (plates or spicules of ice suspended in water), slush (water saturated snow), or shuga (spongy white ice lumps a few centimeters across). Other terms, such as grease ice and pancake ice, are used for ice crystal accumulations under the action of wind and waves. When sea ice begins to form on a beach with a light swell, ice eggs up to the size of a football can be created. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Sea_ice-1.md b/data/en.wikipedia.org/wiki/Sea_ice-1.md new file mode 100644 index 000000000..7cd09a011 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Sea_ice-1.md @@ -0,0 +1,30 @@ +--- +title: "Sea ice" +chunk: 2/4 +source: "https://en.wikipedia.org/wiki/Sea_ice" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:19.320016+00:00" +instance: "kb-cron" +--- + +Nilas designates a sea ice crust up to 10 centimetres (3.9 in) in thickness. It bends without breaking around waves and swells. Nilas can be further subdivided into dark nilas – up to 5 cm (2.0 in) in thickness and very dark and light nilas – over 5 cm (2.0 in) in thickness and lighter in color. +Young ice is a transition stage between nilas and first-year ice and ranges in thickness from 10 cm (3.9 in) to 30 cm (12 in), Young ice can be further subdivided into grey ice – 10 cm (3.9 in) to 15 cm (5.9 in) in thickness and grey-white ice – 15 cm (5.9 in) to 30 cm (12 in) in thickness. Young ice is not as flexible as nilas, but tends to break under wave action. Under compression, it will either raft (at the grey ice stage) or ridge (at the grey-white ice stage). + +==== First-year sea ice ==== + +First-year sea ice is ice that is thicker than young ice but has no more than one year growth. In other words, it is ice that grows in the fall and winter (after it has gone through the new ice – nilas – young ice stages and grows further) but does not survive the spring and summer months (it melts away). The thickness of this ice typically ranges from 0.3 m (0.98 ft) to 2 m (6.6 ft). First-year ice may be further divided into thin (30 cm (0.98 ft) to 70 cm (2.3 ft)), medium (70 cm (2.3 ft) to 120 cm (3.9 ft)) and thick (>120 cm (3.9 ft)). + +==== Old sea ice ==== +Old sea ice is sea ice that has survived at least one melting season (i.e. one summer). For this reason, this ice is generally thicker than first-year sea ice. The thickness of old sea ice typically ranges from 2 to 4 m. Old ice is commonly divided into two types: second-year ice, which has survived one melting season and multiyear ice, which has survived more than one. (In some sources, old ice is more than two years old.) Multi-year ice is much more common in the Arctic than it is in the Antarctic. The reason for this is that sea ice in the south drifts into warmer waters where it melts. In the Arctic, much of the sea ice is land-locked. + +=== Leads and polynyas === +Leads and polynyas are areas of open water that occur within sea ice expanses even though air temperatures are below freezing. They provide a direct interaction between the ocean and the atmosphere, which is important for the wildlife. Leads are narrow and linear, varying in width from meters to kilometers. During the winter, the water in leads quickly freezes up. They are also used for navigation purposes – even when refrozen, the ice in leads is thinner, allowing icebreakers access to an easier sail path and submarines to surface more easily. Polynyas are more uniform in size than leads and are also larger – two types are recognized: 1) Sensible-heat polynyas, caused by the upwelling of warmer water and 2) Latent-heat polynyas, resulting from persistent winds from the coastline. + +== Dynamics and cycles == + +=== Formation === +Only the top layer of water needs to cool to the freezing point. Convection of the surface layer involves the top 100–150 m (330–490 ft), down to the pycnocline of increased density. +In calm water, the first sea ice to form on the surface is a skim of separate crystals which initially are in the form of tiny discs, floating flat on the surface and of diameter less than 0.3 cm (0.12 in). Each disc has its c-axis vertical and grows outwards laterally. At a certain point such a disc shape becomes unstable and the growing isolated crystals take on a hexagonal, stellar form, with long fragile arms stretching out over the surface. These crystals also have their c-axis vertical. The dendritic arms are very fragile and soon break off, leaving a mixture of discs and arm fragments. With any kind of turbulence in the water, these fragments break up further into random-shaped small crystals which form a suspension of increasing density in the surface water, an ice type called frazil or grease ice. In quiet conditions the frazil crystals soon freeze together to form a continuous thin sheet of young ice; in its early stages, when it is still transparent – that is the ice called nilas. Once nilas has formed, a quite different growth process occurs, in which water freezes on to the bottom of the existing ice sheet, a process called congelation growth. This growth process yields first-year ice. +In rough water, fresh sea ice is formed by the cooling of the ocean as heat is lost into the atmosphere. The uppermost layer of the ocean is supercooled to slightly below the freezing point, at which time tiny ice platelets (frazil ice) form. With time, this process leads to a mushy surface layer, known as grease ice. Frazil ice formation may also be started by snowfall, rather than supercooling. Waves and wind then act to compress these ice particles into larger plates, of several meters in diameter, called pancake ice. These float on the ocean surface and collide with one another, forming upturned edges. In time, the pancake ice plates may themselves be rafted over one another or frozen together into a more solid ice cover, known as consolidated pancake ice. Such ice has a very rough appearance on top and bottom. +If sufficient snow falls on sea ice to depress the freeboard below sea level, sea water will flow in and a layer of ice will form of mixed snow/sea water. This is particularly common around Antarctica. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Sea_ice-2.md b/data/en.wikipedia.org/wiki/Sea_ice-2.md new file mode 100644 index 000000000..3ad472b0f --- /dev/null +++ b/data/en.wikipedia.org/wiki/Sea_ice-2.md @@ -0,0 +1,37 @@ +--- +title: "Sea ice" +chunk: 3/4 +source: "https://en.wikipedia.org/wiki/Sea_ice" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:19.320016+00:00" +instance: "kb-cron" +--- + +=== Ice motion === +While fast ice is relatively stable (because it is attached to the shoreline or the seabed), drift (or pack) ice undergoes relatively complex deformation processes that ultimately give rise to sea ice's typically wide variety of landscapes. Wind is the main driving force, along with ocean currents. The Coriolis force and sea ice surface tilt have also been invoked. These driving forces induce a state of stress within the drift ice zone. An ice floe converging toward another and pushing against it will generate a state of compression at the boundary between both. The ice cover may also undergo a state of tension, resulting in divergence and fissure opening. If two floes drift sideways past each other while remaining in contact, this will create a state of shear. + +=== Deformation === +Sea ice deformation results from the interaction between ice floes as they are driven against each other. The result may be of three types of features: 1) Rafted ice, when one piece is overriding another; 2) Pressure ridges, a line of broken ice forced downward (to make up the keel) and upward (to make the sail); and 3) Hummock, a hillock of broken ice that forms an uneven surface. A shear ridge is a pressure ridge that formed under shear – it tends to be more linear than a ridge induced only by compression. A new ridge is a recent feature – it is sharp-crested, with its side sloping at an angle exceeding 40 degrees. In contrast, a weathered ridge is one with a rounded crest and with sides sloping at less than 40 degrees. Stamukhi are yet another type of pile-up but these are grounded and are therefore relatively stationary. They result from the interaction between fast ice and the drifting pack ice. +Level ice is sea ice that has not been affected by deformation and is therefore relatively flat. + +=== Yearly freeze and melt cycle === + +The annual freeze and melt cycle is set by the annual cycle of solar insolation and of ocean and atmospheric temperature and of variability in this annual cycle. + +In the Arctic, the area of ocean covered by sea ice increases over winter from a minimum in September to a maximum in March or sometimes February, before melting over the summer. In the Antarctic, where the seasons are reversed, the annual minimum is typically in February and the annual maximum in September or October. The presence of sea ice abutting the calving fronts of ice shelves has been shown to influence glacier flow and potentially the stability of the Antarctic ice sheet.The growth and melt rate are also affected by the state of the ice itself. During growth, the ice thickening due to freezing (as opposed to dynamics) is itself dependent on the thickness, so that the ice growth slows as the ice thickens. Likewise, during melt, thinner sea ice melts faster. This leads to different behaviour between multiyear and first year ice. In addition, melt ponds on the ice surface during the melt season lower the albedo such that more solar radiation is absorbed, leading to a feedback where melt is accelerated. The presence of melt ponds is affected by the permeability of the sea ice (i.e. whether meltwater can drain) and the topography of the sea ice surface (i.e. the presence of natural basins for the melt ponds to form in). First year ice is flatter than multiyear ice due to the lack of dynamic ridging, so ponds tend to have greater area. They also have lower albedo since they are on thinner ice, which blocks less of the solar radiation from reaching the dark ocean below. + +== Monitoring and trends == + +Changes in sea ice conditions are best demonstrated by the rate of melting over time. A composite record of Arctic ice demonstrates that the floes' retreat began around 1900, experiencing more rapid melting beginning within the past 50 years. Satellite study of sea ice began in 1979 and became a much more reliable measure of long-term changes in sea ice. +September Arctic sea ice extent is currently decreasing at about 12% per decade, compared to the 1981-2010 average. In comparison to the extended record, the sea-ice extent in the Arctic region by September 2007 was only half the recorded mass that had been estimated to exist within the 1950–1970 period. In September 2012 Arctic sea ice reached its lowest level ever recorded, covering just 24% of the Arctic Ocean, down from the previous record low of 29% in 2007. A new second-lowest extent was later set in 2020. Predictions of when the first "ice free" Arctic summer might occur vary but are anticipated by mid-century (2035-2067). +Antarctic sea ice extent increased gradually from the start of satellite observations in 1979 until spring 2016, when it began a rapid decline that is still continuing as of 2024. + +== Sea ice and climate == + +=== Effects of sea ice on climate === + +Sea ice helps keep polar regions cool by reflecting incoming solar radiation due to its high albedo. This reflective surface prevents much of the Sun's energy from being absorbed by the darker ocean below. As sea ice melts, the exposed ocean absorbs more heat, further accelerating warming in a positive feedback loop known as the ice–albedo feedback. +Sea ice also influences global ocean circulation. When seawater freezes, most of the salt is excluded from the ice crystals, creating denser, saltier water beneath the ice. This dense water sinks and helps drive thermohaline circulation, a global "conveyor belt" of ocean currents that redistributes heat across the planet. + +=== Effects of climate change on sea ice === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Sea_ice-3.md b/data/en.wikipedia.org/wiki/Sea_ice-3.md new file mode 100644 index 000000000..84cc4f343 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Sea_ice-3.md @@ -0,0 +1,64 @@ +--- +title: "Sea ice" +chunk: 4/4 +source: "https://en.wikipedia.org/wiki/Sea_ice" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:19.320016+00:00" +instance: "kb-cron" +--- + +The polar regions are among the most sensitive areas to climate change, with consequences for ecosystems, weather patterns, and global sea level. Rising global temperatures from human-caused greenhouse gas emissions have led to warming of the atmosphere and oceans, accelerating sea ice melt. +Although the melting of floating sea ice has a small effect on global average sea level (because sea ice is less salty and less dense than the seawater it displaces) it has large indirect effects on global climate systems. Loss of sea ice lowers the albedo of polar regions, amplifying warming and accelerating the melt of the Greenland and Antarctic ice sheets, which contributes substantially to sea level rise. Reduced sea ice alters ocean circulation and wave activity, which can enhance the erosion of coastal ice shelves and glaciers. + +Melting sea ice also introduces large amounts of freshwater into the surface ocean. This reduces salinity, which can alter water density and influence global ocean circulation, including the Atlantic Meridional Overturning Circulation. These changes alter the transport of heat and nutrients, with consequences for marine ecosystems as well as regional and global climate patterns. + +== Modelling == +In order to gain a better understanding about the variability, numerical sea ice models are used to perform sensitivity studies. The two main ingredients are the ice dynamics and the thermodynamical properties (see Sea ice emissivity modelling, Sea ice growth processes and Sea ice thickness). There are many sea ice model computer codes available for doing this, including the CICE numerical suite. +Many global climate models (GCMs) have sea ice implemented in their numerical simulation scheme in order to capture the ice–albedo feedback correctly. Examples include: + +The Louvain-la-Neuve Sea Ice Model is a numerical model of sea ice designed for climate studies and operational oceanography developed at Université catholique de Louvain. It is coupled to the ocean general circulation model OPA (Ocean Parallélisé) and is freely available as a part of the Nucleus for European Modeling of the Ocean. +The MIT General Circulation Model is a global circulation model developed at Massachusetts Institute of Technology includes a package for sea-ice. The code is freely available there. +The University Corporation for Atmospheric Research develops the Community Sea Ice Model. +CICE is run by the Los Alamos National Laboratory. The project is open source and designed as a component of GCM, although it provides a standalone mode. +The Finite-Element Sea-Ice Ocean Model developed at Alfred Wegener Institute uses an unstructured grid. +The neXt Generation Sea-Ice model (neXtSIM) is a Lagrangian model using an adaptive and unstructured triangular mesh and includes a new and unique class of rheological model called Maxwell-Elasto-Brittle to treat the ice dynamics. This model is developed at the Nansen Center in Bergen, Norway. +The Coupled Model Intercomparison Project offers a standard protocol for studying the output of coupled atmosphere-ocean general circulation models. The coupling takes place at the atmosphere-ocean interface where the sea ice may occur. +In addition to global modeling, various regional models deal with sea ice. Regional models are employed for seasonal forecasting experiments and for process studies. + +== Ecology == + +Sea ice provides a unique habitat within the Earth's biosphere. As seawater freezes, it traps pockets of brine, creating a network of channels and pores that host diverse communities of microorganisms, including bacteria, archaea, fungi, algae, protozoa, and viruses. These sympagic organisms form the base of food webs. Ice algae, in particular, are a critical food source for small invertebrates such as copepods and amphipods, which are consumed by larger animals including krill, fish and seabirds. +Life in sea ice must cope with extreme conditions. Temperatures inside the ice are below freezing, while brine channels are often saltier than seawater. For much of the year there is little or no sunlight, followed by months of continuous daylight in summer. Many organisms have evolved special strategies to adapt, such as producing antifreeze compounds, going dormant until light and nutrients return, or timing growth to the summer season. + +The ecology of sea ice is seasonal. In spring and summer, increasing light and melting ice stimulate algal growth, which is released into the water column. This seasonal pulse supports large phytoplankton blooms that fuel productivity across polar marine ecosystems. The timing and extent of sea ice melt therefore influences the availability of food for higher trophic levels. + +In the Southern Ocean, Antarctic krill rely on sea ice algae during their juvenile stages, forming the foundation of food webs that support fish, penguins, seals, and whales. In the Arctic, sea ice also hosts algae that sustain zooplankton which support fish, seals, walruses, and polar bears. +Sea ice also regulates biogeochemical processes. It stores and redistributes nutrients such as iron, and its seasonal melting influences ocean mixing and primary productivity. In this way, sea ice contributes to global carbon cycling and climate regulation. +Declines in sea ice extent and duration due to climate change pose significant ecological risks. Species that depend directly on sea ice for feeding, breeding, or resting are highly impacted. These include ringed seals and polar bears in the Arctic, and Emperor and Adélie penguins in Antarctica. Indirect impacts cascade through food webs, threatening the productivity and stability of entire polar ecosystems. + +== Extraterrestrial presence == +Other elements and compounds have been speculated to exist as oceans and seas on extraterrestrial planets. Scientists notably suspect the existence of "icebergs" of solid diamond and corresponding seas of liquid carbon on the ice giants, Neptune and Uranus. This is due to extreme pressure and heat at the core, that would turn carbon into a supercritical fluid. + +== See also == + +=== Ice types or features === + +=== Physics and chemistry === + +=== Applied sciences and engineering endeavours === + +=== Other === +Vladimir Vize - Russian Arctic ice pack scientist + +== References == + +== External links == + +Daily maps of sea ice concentration from the University of Bremen +Sea ice maps from the National Snow and Ice Data Center + +=== Sea Ice Glossaries === +"Cryosphere Glossary". National Snow and Ice Data Center, University of Colorado, Boulder. +"Ice Glossary". Environment Canada. 27 September 2010. +"WMO Sea-Ice Nomenclature". World Meteorological Organization. WMO/OMM/ВМО – No. 259 • Edition 1970–2004. Archived from the original on 2 May 2023. Retrieved 29 August 2022. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Sea_level-0.md b/data/en.wikipedia.org/wiki/Sea_level-0.md new file mode 100644 index 000000000..141f03fc0 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Sea_level-0.md @@ -0,0 +1,33 @@ +--- +title: "Sea level" +chunk: 1/3 +source: "https://en.wikipedia.org/wiki/Sea_level" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:20.601911+00:00" +instance: "kb-cron" +--- + +Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datum – a standardised geodetic datum – that is used, for example, as a chart datum in cartography and marine navigation, or, in aviation, as the standard sea level at which atmospheric pressure is measured to calibrate altitude and, consequently, aircraft flight levels. A common and relatively straightforward mean sea-level standard is instead a long-term average of tide gauge readings at a particular reference location. +The term above sea level generally refers to the height above mean sea level (AMSL). The term APSL means above present sea level, comparing sea levels in the past with the level today. +Earth's radius at sea level is 6,378.137 km (3,963.191 mi) at the equator. It is 6,356.752 km (3,949.903 mi) at the poles and 6,371.001 km (3,958.756 mi) on average. This flattened spheroid, combined with local gravity anomalies, defines the geoid of the Earth, which approximates the local mean sea level for locations in the open ocean. The geoid includes a significant depression in the Indian Ocean, whose surface dips as much as 106 m (348 ft) below the global mean sea level (excluding minor effects such as tides and currents). It was found in 2026 that sea levels estimated using the geoid used in 90% of published work were about 25cm lower than measured values on average, hence underestimating the effect of sea level rise. + +== Measurement == + +Precise determination of a "mean sea level" is difficult because of the many factors that affect sea level. Instantaneous sea level varies substantially on several scales of time and space. This is because the sea is in constant motion, affected by the tides, tsunamis, wind, atmospheric pressure, local gravitational differences, temperature, salinity, and so forth. The mean sea level at a particular location may be calculated over an extended time period and used as a datum. For example, hourly measurements may be averaged over a full Metonic 19-year lunar cycle to determine the mean sea level at an official tide gauge. +Still-water level or still-water sea level (SWL) is the level of the sea with motions such as wind waves averaged out. +Then MSL implies the SWL further averaged over a period of time such that changes due to, e.g., the tides, also have zero mean. +Global MSL refers to a spatial average over the entire ocean area, typically using large sets of tide gauges and/or satellite measurements. +One often measures the values of MSL with respect to the land; hence a change in relative MSL or (relative sea level) can result from a real change in sea level, or from a change in the height of the land on which the tide gauge operates, or both. +In the UK, the ordnance datum (the 0 metres height on UK maps) is the mean sea level measured at Newlyn in Cornwall between 1915 and 1921. Before 1921, the vertical datum was MSL at the Victoria Dock, Liverpool. +Since the times of the Russian Empire, in Russia and its other former parts, now independent states, the sea level is measured from the zero level of Kronstadt Sea-Gauge. +In Hong Kong, "mPD" is a surveying term meaning "metres above Principal Datum" and refers to height of 0.146 m (5.7 in) above chart datum and 1.304 m (4 ft 3.3 in) below the average sea level. +In France, the Marégraphe in Marseille measures continuously the sea level since 1883 and offers the longest collated data about the sea level. It is used for a part of continental Europe and the main part of Africa as the official sea level. Spain uses the reference to measure heights below or above sea level at Alicante, while the European Vertical Reference System is calibrated to the Amsterdam Peil elevation, which dates back to the 1690s. +Satellite altimeters have been making precise measurements of sea level since the launch of TOPEX/Poseidon in 1992. A joint mission of NASA and CNES, TOPEX/Poseidon was followed by Jason-1 in 2001 and the Ocean Surface Topography Mission on the Jason-2 satellite in 2008. + +=== Height above mean sea level === + +Height above mean sea level (AMSL) is the elevation (on the ground) or altitude (in the air) of an object, relative to a reference datum for mean sea level (MSL). It is also used in aviation, where some heights are recorded and reported with respect to mean sea level (contrast with flight level), and in the atmospheric sciences, and in land surveying. An alternative is to base height measurements on a reference ellipsoid approximating the entire Earth, which is what systems such as GPS do. In aviation, the reference ellipsoid known as WGS84 is increasingly used to define heights; however, differences up to 100 metres (328 feet) exist between this ellipsoid height and local mean sea level. Another alternative is to use a geoid-based vertical datum such as NAVD88 and the global EGM96 (part of WGS84). Details vary in different countries. +When referring to geographic features such as mountains, on a topographic map variations in elevation are shown by contour lines. A mountain's highest point or summit is typically illustrated with the AMSL height in metres, feet or both. In unusual cases where a land location is below sea level, such as Death Valley, California, the elevation AMSL is negative. + +==== Difficulties in use ==== \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Sea_level-1.md b/data/en.wikipedia.org/wiki/Sea_level-1.md new file mode 100644 index 000000000..e05ce456b --- /dev/null +++ b/data/en.wikipedia.org/wiki/Sea_level-1.md @@ -0,0 +1,43 @@ +--- +title: "Sea level" +chunk: 2/3 +source: "https://en.wikipedia.org/wiki/Sea_level" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:20.601911+00:00" +instance: "kb-cron" +--- + +It is often necessary to compare the local height of the mean sea surface with a "level" reference surface, or geodetic datum, called the geoid. In the absence of external forces, the local mean sea level would coincide with this geoid surface, being an equipotential surface of the Earth's gravitational field which, in itself, does not conform to a simple sphere or ellipsoid and exhibits gravity anomalies such as those measured by NASA's GRACE satellites. In reality, the geoid surface is not directly observed, even as a long-term average, due to ocean currents, air pressure variations, temperature and salinity variations, etc. The location-dependent but time-persistent separation between local mean sea level and the geoid is referred to as (mean) ocean surface topography. It varies globally in a typical range of ±1 m (3 ft). +Work published in 2026 analysed 385 peer-reviewed scientific papers published since 2009 and compared the difference between calculations using commonly assumed coastal sea levels using global geoid models with actual measurements. It was found that over 90% of studies used land elevation measurements referenced against global geoid models instead of local direct measurements. This underestimated levels by an average of 24-27cm, with some discrepancies reaching 550-760cm, a discrepancy described as an "interdisciplinary blind spot". The effect of this underestimation is that for a sea level rise of 1m, 37% more coastal areas than previously estimated will fall below sea level, affecting up to 132 million people. + +== Dry land == + +Several terms are used to describe the changing relationships between sea level and dry land. + +"relative" means change relative to a fixed point in the sediment pile. +"eustatic" refers to global changes in sea level relative to a fixed point, such as the centre of the earth, for example as a result of melting ice-caps. +"steric" refers to global changes in sea level due to thermal expansion and salinity variations. +"isostatic" refers to changes in the level of the land relative to a fixed point in the earth, possibly due to thermal buoyancy or tectonic effects, disregarding changes in the volume of water in the oceans. +The melting of glaciers at the end of ice ages results in isostatic post-glacial rebound, when land rises after the weight of ice is removed. Conversely, older volcanic islands experience relative sea level rise, due to isostatic subsidence from the weight of cooling volcanos. The subsidence of land due to the withdrawal of groundwater is another isostatic cause of relative sea level rise. +On planets that lack a liquid ocean, planetologists can calculate a "mean altitude" by averaging the heights of all points on the surface. This altitude, sometimes referred to as a "sea level" or zero-level elevation, serves equivalently as a reference for the height of planetary features. + +== Change == + +=== Local and eustatic === + +Local mean sea level (LMSL) is defined as the height of the sea with respect to a land benchmark, averaged over a period of time long enough that fluctuations caused by waves and tides are smoothed out, typically a year or more. One must adjust perceived changes in LMSL to account for vertical movements of the land, which can occur at rates similar to sea level changes (millimetres per year). +Some land movements occur because of isostatic adjustment to the melting of ice sheets at the end of the last ice age. The weight of the ice sheet depresses the underlying land, and when the ice melts away the land slowly rebounds. Changes in ground-based ice volume also affect local and regional sea levels by the readjustment of the geoid and true polar wander. Atmospheric pressure, ocean currents and local ocean temperature changes can affect LMSL as well. +Eustatic sea level change (global as opposed to local change) is due to change in either the volume of water in the world's oceans or the volume of the oceanic basins. Two major mechanisms are currently causing eustatic sea level rise. First, shrinking land ice, such as mountain glaciers and polar ice sheets, is releasing water into the oceans. Second, as ocean temperatures rise, the warmer water expands. + +=== Short-term and periodic changes === + +Many factors can produce short-term changes in sea level, typically within a few metres, in timeframes ranging from minutes to months: + +=== Recent changes === + +== Aviation == + +Pilots can estimate height above sea level with an altimeter set to a defined barometric pressure. Generally, the pressure used to set the altimeter is the barometric pressure that would exist at MSL in the region being flown over. This pressure is referred to as either QNH or "altimeter" and is transmitted to the pilot by radio from air traffic control (ATC) or an automatic terminal information service (ATIS). Since the terrain elevation is also referenced to MSL, the pilot can estimate height above ground by subtracting the terrain altitude from the altimeter reading. Aviation charts are divided into boxes and the maximum terrain altitude from MSL in each box is clearly indicated. Once above the transition altitude, the altimeter is set to the international standard atmosphere (ISA) pressure at MSL which is 1013.25 hPa or 29.92 inHg. + +== See also == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Sea_level-2.md b/data/en.wikipedia.org/wiki/Sea_level-2.md new file mode 100644 index 000000000..2dd7d60b4 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Sea_level-2.md @@ -0,0 +1,46 @@ +--- +title: "Sea level" +chunk: 3/3 +source: "https://en.wikipedia.org/wiki/Sea_level" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:20.601911+00:00" +instance: "kb-cron" +--- + +Above ground level – Height measured with respect to the underlying ground surfacePages displaying short descriptions of redirect targets +Amsterdam Ordnance Datum, also known as Normaal Amsterdams Peil – Vertical datum +Before Present – Time scale used in scientific disciplines +Chart datum – Level of water from which depths displayed on a nautical chart are measured +Extreme points of Earth +Geopotential height – Type of altitude above mean sea level +Height above average terrain – Height based on large area surrounding object; often used in U.S. for antenna towers +List of places on land with elevations below sea level +Meltwater pulse 1A – Period of rapid post-glacial sea level rise +Metres above the Adriatic – Vertical datum used in parts of Europe +Normal height – Altitude above quasigeoid or mean sea level +Normalhöhennull – Vertical datum used in Germany +Normalnull – Outdated official vertical datum used in Germany +North West Shelf Operational Oceanographic System – Oceanography facility +Ordnance datum – Vertical datum used as the basis for deriving altitudes on maps (UK and Ireland) +Orthometric height – Altitude above geoid or mean sea level +Raised beach, also known as Marine terrace – Emergent coastal landform +Regional Reference Frame Sub-Commission for Europe +Sea level drop – Drop relative to land rebounding from weight of ice +Sea level equation – Rise of land masses after glacial periodPages displaying short descriptions of redirect targets +World Geodetic System – Geodetic reference system + +== References == + +== External links == + +Sea Level Rise:Understanding the past – Improving projections for the future +Permanent Service for Mean Sea Level +Global sea level change: Determination and interpretation +Environment Protection Agency Sea level rise reports +Properties of isostasy and eustasy +Measuring Sea Level from Space +Rising Tide Video: Scripps Institution of Oceanography +Sea Levels Online: National Ocean Service (CO-OPS) +Système d'Observation du Niveau des Eaux Littorales (SONEL) +Sea level rise – How much and how fast will sea level rise over the coming centuries? \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Seafloor_depth_versus_age-0.md b/data/en.wikipedia.org/wiki/Seafloor_depth_versus_age-0.md new file mode 100644 index 000000000..b2d1084c9 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Seafloor_depth_versus_age-0.md @@ -0,0 +1,310 @@ +--- +title: "Seafloor depth versus age" +chunk: 1/2 +source: "https://en.wikipedia.org/wiki/Seafloor_depth_versus_age" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:21.860295+00:00" +instance: "kb-cron" +--- + +The depth of the seafloor on the flanks of a mid-ocean ridge is determined mainly by the age of the oceanic lithosphere; older seafloor is deeper. During seafloor spreading, lithosphere and mantle cooling, contraction, and isostatic adjustment with age cause seafloor deepening. This relationship has come to be better understood since around 1969 with significant updates in 1974 and 1977. Two main theories have been put forward to explain this observation: one where the mantle including the lithosphere is cooling; the cooling mantle model, and a second where a lithosphere plate cools above a mantle at a constant temperature; the cooling plate model. The cooling mantle model explains the age-depth observations for seafloor younger than 80 million years. The cooling plate model explains the age-depth observations best for seafloor older that 20 million years. In addition, the cooling plate model explains the almost constant depth and heat flow observed in very old seafloor and lithosphere. In practice it is convenient to use the solution for the cooling mantle model for an age-depth relationship younger than 20 million years. Older than this the cooling plate model fits data as well. Beyond 80 million years the plate model fits better than the mantle model. + +== Background == +The first theories for seafloor spreading in the early and mid twentieth century explained the elevations of the mid-ocean ridges as upwellings above convection currents in Earth's mantle. +The next idea connected seafloor spreading and continental drift in a model of plate tectonics. In 1969, the elevations of ridges was explained as thermal expansion of a lithospheric plate at the spreading center. This 'cooling plate model' was followed in 1974 by noting that elevations of ridges could be modeled by cooling of the whole upper mantle including any plate. This was followed in 1977 by a more refined plate model which explained data that showed that both the ocean depths and ocean crust heat flow approached a constant value for very old seafloor. These observations could not be explained by the earlier 'cooling mantle model' which predicted increasing depth and decreasing heat flow at very old ages. + +== Seafloor topography: cooling mantle and lithosphere models == +The depth of the seafloor (or the height of a location on a mid-ocean ridge above a base-level) is closely correlated with its age (i.e. the age of the lithosphere at the point where depth is measured). Depth is measured to the top of the ocean crust, below any overlying sediment. The age-depth relation can be modeled by the cooling of a lithosphere plate or mantle half-space in areas without significant subduction. The distinction between the two approaches is that the plate model requires the base of the lithosphere to maintain a constant temperature over time and the cooling is of the plate above this lower boundary. The cooling mantle model, which was developed after the plate model, does not require that the lithosphere base is maintained at a constant and limiting temperature. The result of the cooling mantle model is that seafloor depth is predicted to be proportional to the square root of its age. + +=== Cooling mantle model (1974) === +In the cooling mantle half-space model developed in 1974, the seabed (top of crust) height is determined by the oceanic lithosphere and mantle temperature, due to thermal expansion. The simple result is that the ridge height or seabed depth is proportional to the square root of its age. In all models, oceanic lithosphere is continuously formed at a constant rate at the mid-ocean ridges. The source of the lithosphere has a half-plane shape (x = 0, z < 0) and a constant temperature T1. Due to its continuous creation, the lithosphere at x > 0 is moving away from the ridge at a constant velocity + + + + v + + + {\displaystyle v} + +, which is assumed large compared to other typical scales in the problem. The temperature at the upper boundary of the lithosphere (z = 0) is a constant T0 = 0. Thus at x = 0 the temperature is the Heaviside step function + + + + + T + + 1 + + + ⋅ + Θ + ( + − + z + ) + + + {\displaystyle T_{1}\cdot \Theta (-z)} + +. The system is assumed to be at a quasi-steady state, so that the temperature distribution is constant in time, i.e. + + + + T + = + T + ( + x + , + z + ) + . + + + {\displaystyle T=T(x,z).} + + +By substituting the parameters by their rough estimates into the solution for the height of the ocean floor + + + + h + ( + t + ) + + + {\displaystyle h(t)} + +: + + + + + + + + + κ + + + + ∼ + 8 + ⋅ + + 10 + + − + 7 + + + + + + m + + + 2 + + + ⋅ + + + s + + + − + 1 + + + + + + + for the thermal diffusivity + + + + + + α + + + + ∼ + 4 + ⋅ + + 10 + + − + 5 + + + + + + + + + ∘ + + + + + C + + + − + 1 + + + + + + + for the thermal expansion coefficient + + + + + + + T + + 1 + + + + + + ∼ + 1220 + + + + + + + ∘ + + + + C + + + + + + for the Atlantic and Indian oceans + + + + + + + T + + 1 + + + + + + ∼ + 1120 + + + + + + + ∘ + + + + C + + + + + + for the eastern Pacific + + + + + + + + {\displaystyle {\begin{aligned}\kappa &\sim 8\cdot 10^{-7}\ \mathrm {m} ^{2}\cdot \mathrm {s} ^{-1}&&{\text{for the thermal diffusivity}}\\\alpha &\sim 4\cdot 10^{-5}\ {}^{\circ }\mathrm {C} ^{-1}&&{\text{for the thermal expansion coefficient}}\\T_{1}&\sim 1220\ {}^{\circ }\mathrm {C} &&{\text{for the Atlantic and Indian oceans}}\\T_{1}&\sim 1120\ {}^{\circ }\mathrm {C} &&{\text{for the eastern Pacific}}\end{aligned}}} + + +we have: + + + + + h + ( + t + ) + ∼ + + + { + + + + + h + + 0 + + + − + 390 + + + t + + + + + + for the Atlantic and Indian oceans + + + + + + + h + + 0 + + + − + 350 + + + t + + + + + + for the eastern Pacific + + + + + + + + + + {\displaystyle h(t)\sim {\begin{cases}h_{0}-390{\sqrt {t}}&{\text{for the Atlantic and Indian oceans}}\\h_{0}-350{\sqrt {t}}&{\text{for the eastern Pacific}}\end{cases}}} + \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Seafloor_depth_versus_age-1.md b/data/en.wikipedia.org/wiki/Seafloor_depth_versus_age-1.md new file mode 100644 index 000000000..2e6f6f7cf --- /dev/null +++ b/data/en.wikipedia.org/wiki/Seafloor_depth_versus_age-1.md @@ -0,0 +1,345 @@ +--- +title: "Seafloor depth versus age" +chunk: 2/2 +source: "https://en.wikipedia.org/wiki/Seafloor_depth_versus_age" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:21.860295+00:00" +instance: "kb-cron" +--- + +where the height is in meters and time is in millions of years. To get the dependence on x, one must substitute t = x/ + + + + v + + + {\displaystyle v} + + ~ Ax/L, where L is the distance between the ridge to the continental shelf (roughly half the ocean width), and A is the ocean basin age. +Rather than height of the ocean floor + + + + h + ( + t + ) + + + {\displaystyle h(t)} + + above a base or reference level + + + + + h + + b + + + + + {\displaystyle h_{b}} + +, the depth of the seabed + + + + d + ( + t + ) + + + {\displaystyle d(t)} + + is of interest. Because + + + + d + ( + t + ) + + + h + ( + t + ) + = + + h + + b + + + + + {\displaystyle d(t)+h(t)=h_{b}} + +(with + + + + + h + + b + + + + + {\displaystyle h_{b}} + + measured from the ocean surface) we can find that: + + + + + d + ( + t + ) + = + + h + + b + + + − + + h + + 0 + + + + + 350 + + + t + + + + + {\displaystyle d(t)=h_{b}-h_{0}+350{\sqrt {t}}} + +; for the eastern Pacific for example, where + + + + + h + + b + + + − + + h + + 0 + + + + + {\displaystyle h_{b}-h_{0}} + + is the depth at the ridge crest, typically 2500 m. + +=== Cooling plate model (1977) === +The depth predicted by the square root of seafloor age found by the 1974 cooling mantle derivation is too deep for seafloor older than 80 million years. Depth is better explained by a cooling lithosphere plate model rather than the cooling mantle half-space. The plate has a constant temperature at its base and spreading edge. Derivation of the cooling plate model also starts with the heat flow equation in one dimension as does the cooling mantle model. The difference is in requiring a thermal boundary at the base of a cooling plate. Analysis of depth versus age and depth versus square root of age data allowed Parsons and Sclater to estimate model parameters (for the North Pacific): + +~125 km for lithosphere thickness + + + + + + T + + 1 + + + ∼ + 1350 + + + + + + + ∘ + + + + C + + + + {\displaystyle T_{1}\thicksim 1350\ {}^{\circ }\mathrm {C} } + + at base and young edge of plate + + + + + α + ∼ + 3.2 + ⋅ + + 10 + + − + 5 + + + + + + + + + ∘ + + + + + C + + + − + 1 + + + + + {\displaystyle \alpha \thicksim 3.2\cdot 10^{-5}\ {}^{\circ }\mathrm {C} ^{-1}} + + +Assuming isostatic equilibrium everywhere beneath the cooling plate yields a revised age-depth relationship for older sea floor that is approximately correct for ages as young as 20 million years: + + + + + d + ( + t + ) + = + 6400 + − + 3200 + exp + ⁡ + + + ( + + + − + t + + / + + 62.8 + + + ) + + + + + {\displaystyle d(t)=6400-3200\exp {\bigl (}-t/62.8{\bigr )}} + + meters +Thus older seafloor deepens more slowly than younger and in fact can be assumed almost constant at ~6400 m depth. Their plate model also allowed an expression for conductive heat flow, q(t) from the ocean floor, which is approximately constant at + + + + 1 + ⋅ + + 10 + + − + 6 + + + + c + a + l + + + + + c + m + + + − + 2 + + + + + s + e + c + + + − + 1 + + + + + {\displaystyle 1\cdot 10^{-6}\mathrm {cal} \,\mathrm {cm} ^{-2}\mathrm {sec} ^{-1}} + + beyond 120 million years: + + + + + q + ( + t + ) + = + 11.3 + + / + + + + t + + + + + {\displaystyle q(t)=11.3/{\sqrt {t}}} + + +Parsons and Sclater concluded that some style of mantle convection must apply heat to the base of the plate everywhere to prevent cooling down below 125 km and lithosphere contraction (seafloor deepening) at older ages. Morgan and Smith showed that the flattening of the older seafloor depth can be explained by flow in the asthenosphere below the lithosphere. +The age-depth-heat flow relationship continued to be studied with refinements in the physical parameters that define ocean lithospheric plates. + +== Impacts == +The usual method for estimating the age of the seafloor is from marine magnetic anomaly data and applying the Vine-Matthews-Morley hypothesis. Other ways include expensive deep sea drilling and dating of core material. If the depth is known at a location where anomalies are not mapped or are absent, and seabed samples are not available, knowing the seabed depth can yield an age estimate using the age-depth relationships. +Along with this, if the seafloor spreading rate in an ocean basin increases, then the average depth in that ocean basin decreases and therefore its volume decreases (and vice versa). This results in global eustatic sea level rise (fall) because the Earth is not expanding. Two main drivers of sea level variation over geologic time are then changes in the volume of continental ice on the land, and the changes over time in ocean basin average depth (basin volume) depending on its average age. + +== See also == +Sea level +Sea-level curve +Sea level equation +Sea level rise + +== References == + +== Further reading == +McKenzie, Dan (2018-05-30). "A Geologist Reflects on a Long Career". Annual Review of Earth and Planetary Sciences. 46 (1): 1–20. Bibcode:2018AREPS..46....1M. doi:10.1146/annurev-earth-082517-010111. ISSN 0084-6597. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Seafloor_spreading-0.md b/data/en.wikipedia.org/wiki/Seafloor_spreading-0.md new file mode 100644 index 000000000..03285e06d --- /dev/null +++ b/data/en.wikipedia.org/wiki/Seafloor_spreading-0.md @@ -0,0 +1,26 @@ +--- +title: "Seafloor spreading" +chunk: 1/4 +source: "https://en.wikipedia.org/wiki/Seafloor_spreading" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:23.036062+00:00" +instance: "kb-cron" +--- + +Seafloor spreading, or seafloor spread, is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. + +== History of study == +Earlier theories by Alfred Wegener and Alexander du Toit of continental drift postulated that continents in motion "plowed" through the fixed and immovable seafloor. The idea that the seafloor itself moves and also carries the continents with it as it spreads from a central rift axis was proposed by Harold Hammond Hess from Princeton University and Robert Dietz of the U.S. Naval Electronics Laboratory in San Diego in the 1960s. The phenomenon is known today as plate tectonics. In locations where two plates move apart, at mid-ocean ridges, new seafloor is continually formed during seafloor spreading. + +== Significance == +Seafloor spreading helps explain continental drift in the theory of plate tectonics. When oceanic plates diverge, tensional stress causes fractures to occur in the lithosphere. The motivating force for seafloor spreading ridges is tectonic plate slab pull at subduction zones, rather than magma pressure, although there is typically significant magma activity at spreading ridges. Plates can also be driven by ridge push, where the rigid lithosphere slides down the hot, raised asthenosphere below mid-ocean ridges. At a spreading center, basaltic magma rises up the fractures and cools on the ocean floor to form new seabed. Hydrothermal vents are common at spreading centers. Older rocks will be found farther away from the spreading zone while younger rocks will be found nearer to the spreading zone. +Spreading rate is the rate at which an ocean basin widens due to seafloor spreading. (The rate at which new oceanic lithosphere is added to each tectonic plate on either side of a mid-ocean ridge is the spreading half-rate and is equal to half of the spreading rate). Spreading rates determine if the ridge is fast, intermediate, or slow. As a general rule, fast ridges have spreading (opening) rates of more than 90 mm/year. Intermediate ridges have a spreading rate of 40–90 mm/year while slow spreading ridges have a rate less than 40 mm/year. The highest known rate was over 200 mm/yr during the Miocene on the East Pacific Rise. +In the 1960s, the past record of geomagnetic reversals of Earth's magnetic field was noticed by observing magnetic stripe "anomalies" on the ocean floor. This results in broadly evident "stripes" from which the past magnetic field polarity can be inferred from data gathered with a magnetometer towed on the sea surface or from an aircraft. The stripes on one side of the mid-ocean ridge were the mirror image of those on the other side. By identifying a reversal with a known age and measuring the distance of that reversal from the spreading center, the spreading half-rate could be computed. + +In some locations spreading rates have been found to be asymmetric; the half rates differ on each side of the ridge crest by about five percent. This is thought due to temperature gradients in the asthenosphere from mantle plumes near the spreading center. + +== Spreading centers == +Seafloor spreading occurs at spreading centers, distributed along the crests of mid-ocean ridges. Spreading centers end in transform faults or in overlapping spreading center offsets. A spreading center includes a seismically active plate boundary zone a few kilometers to tens of kilometers wide, a crustal accretion zone within the boundary zone where the ocean crust is youngest, and an instantaneous plate boundary – a line within the crustal accretion zone demarcating the two separating plates. Within the crustal accretion zone is a 1–2 km-wide neovolcanic zone where active volcanism occurs. + +== Incipient spreading == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Seafloor_spreading-1.md b/data/en.wikipedia.org/wiki/Seafloor_spreading-1.md new file mode 100644 index 000000000..6bff9b839 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Seafloor_spreading-1.md @@ -0,0 +1,18 @@ +--- +title: "Seafloor spreading" +chunk: 2/4 +source: "https://en.wikipedia.org/wiki/Seafloor_spreading" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:23.036062+00:00" +instance: "kb-cron" +--- + +In the general case, seafloor spreading starts as a rift in a continental land mass, similar to the Red Sea-East Africa Rift System today. The process starts by heating at the base of the continental crust which causes it to become more plastic and less dense. Because less dense objects rise in relation to denser objects, the area being heated becomes a broad dome (see isostasy). As the crust bows upward, fractures occur that gradually grow into rifts. The typical rift system consists of three rift arms at approximately 120-degree angles. These areas are named triple junctions and can be found in several places across the world today. The separated margins of the continents evolve to form passive margins. Hess' theory was that new seafloor is formed when magma is forced upward toward the surface at a mid-ocean ridge. +If spreading continues past the incipient stage described above, two of the rift arms will open while the third arm stops opening and becomes a 'failed rift' or aulacogen. As the two active rifts continue to open, eventually the continental crust is attenuated as far as it will stretch. At this point basaltic oceanic crust and upper mantle lithosphere begins to form between the separating continental fragments. When one of the rifts opens into the existing ocean, the rift system is flooded with seawater and becomes a new sea. The Red Sea is an example of a new arm of the sea. The East African rift was thought to be a failed arm that was opening more slowly than the other two arms, but in 2005 the Ethiopian Afar Geophysical Lithospheric Experiment reported that in the Afar region, September 2005, a 60 km fissure opened as wide as eight meters. During this period of initial flooding the new sea is sensitive to changes in climate and eustasy. As a result, the new sea will evaporate (partially or completely) several times before the elevation of the rift valley has been lowered to the point that the sea becomes stable. During this period of evaporation large evaporite deposits will be made in the rift valley. Later these deposits have the potential to become hydrocarbon seals and are of particular interest to petroleum geologists. +Seafloor spreading can stop during the process, but if it continues to the point that the continent is completely severed, then a new ocean basin is created. The Red Sea has not yet completely split Arabia from Africa, but a similar feature can be found on the other side of Africa that has broken completely free. South America once fit into the area of the Niger Delta. The Niger River has formed in the failed rift arm of the triple junction. + +== Continued spreading and subduction == + +As new seafloor forms and spreads apart from the mid-ocean ridge it slowly cools over time. Older seafloor is, therefore, colder than new seafloor, and older oceanic basins deeper than new oceanic basins due to isostasy. If the diameter of the earth remains relatively constant despite the production of new crust, a mechanism must exist by which crust is also destroyed. The destruction of oceanic crust occurs at subduction zones where oceanic crust is forced under either continental crust or oceanic crust. Today, the Atlantic basin is actively spreading at the Mid-Atlantic Ridge. Only a small portion of the oceanic crust produced in the Atlantic is subducted. However, the plates making up the Pacific Ocean are experiencing subduction along many of their boundaries which causes the volcanic activity in what has been termed the Ring of Fire of the Pacific Ocean. The Pacific is also home to one of the world's most active spreading centers (the East Pacific Rise) with spreading rates of up to 145 ± 4 mm/yr between the Pacific and Nazca plates. The Mid-Atlantic Ridge is a slow-spreading center, while the East Pacific Rise is an example of fast spreading. Spreading centers at slow and intermediate rates exhibit a rift valley while at fast rates an axial high is found within the crustal accretion zone. The differences in spreading rates affect not only the geometries of the ridges but also the geochemistry of the basalts that are produced. +Since the new oceanic basins are shallower than the old oceanic basins, the total capacity of the world's ocean basins decreases during times of active sea floor spreading. During the opening of the Atlantic Ocean, sea level was so high that a Western Interior Seaway formed across North America from the Gulf of Mexico to the Arctic Ocean. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Seafloor_spreading-2.md b/data/en.wikipedia.org/wiki/Seafloor_spreading-2.md new file mode 100644 index 000000000..5f384d9f8 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Seafloor_spreading-2.md @@ -0,0 +1,580 @@ +--- +title: "Seafloor spreading" +chunk: 3/4 +source: "https://en.wikipedia.org/wiki/Seafloor_spreading" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:23.036062+00:00" +instance: "kb-cron" +--- + +== Debate and search for mechanism == +At the Mid-Atlantic Ridge (and in other mid-ocean ridges), material from the upper mantle rises through the faults between oceanic plates to form new crust as the plates move away from each other, a phenomenon first observed as continental drift. When Alfred Wegener first presented a hypothesis of continental drift in 1912, he suggested that continents plowed through the ocean crust. This was impossible: oceanic crust is both more dense and more rigid than continental crust. Accordingly, Wegener's theory wasn't taken very seriously, especially in the United States. +At first the driving force for spreading was argued to be convection currents in the mantle. Since then, it has been shown that the motion of the continents is linked to seafloor spreading by the theory of plate tectonics, which is driven by convection that includes the crust itself as well. +The driver for seafloor spreading in plates with active margins is the weight of the cool, dense, subducting slabs that pull them along, or slab pull. The magmatism at the ridge is considered to be passive upwelling, which is caused by the plates being pulled apart under the weight of their own slabs. This can be thought of as analogous to a rug on a table with little friction: when part of the rug is off of the table, its weight pulls the rest of the rug down with it. However, the Mid-Atlantic ridge itself is not bordered by plates that are being pulled into subduction zones, except the minor subduction in the Lesser Antilles and Scotia Arc. In this case the plates are sliding apart over the mantle upwelling in the process of ridge push. + +== Seafloor global topography: cooling models == + +The depth of the seafloor (or the height of a location on a mid-ocean ridge above a base-level) is closely correlated with its age (age of the lithosphere where depth is measured). The age-depth relation can be modeled by the cooling of a lithosphere plate or mantle half-space in areas without significant subduction. + +=== Cooling mantle model === +In the mantle half-space model, the oceanic crust height is determined by the oceanic lithosphere and mantle temperature, due to thermal expansion. Note that the seabed height is not the same as the oceanic crust height, as there is also a layer of sediments over the oceanic crust, typically few hundreds meter thick (but can also be few kilometers thick and up to 20 kilometers thick on few near-shore locations). The simple result is that the ridge height or ocean depth is proportional to the square root of its age. Oceanic lithosphere is continuously formed at a constant rate at the mid-ocean ridges. The source of the lithosphere has a half-plane shape (x = 0, z < 0) and a constant temperature T1. Due to its continuous creation, the lithosphere at x > 0 is moving away from the ridge at a constant velocity v, which is assumed large compared to other typical scales in the problem. The temperature at the upper boundary of the lithosphere (z = 0) is a constant T0 = 0. Thus at x = 0 the temperature is the Heaviside step function + + + + + T + + 1 + + + ⋅ + Θ + ( + − + z + ) + + + {\displaystyle T_{1}\cdot \Theta (-z)} + +. The system is assumed to be at a quasi-steady state, so that the temperature distribution is constant in time, i.e. + + + + T + = + T + ( + x + , + z + ) + . + + + {\displaystyle T=T(x,z).} + + +By calculating in the frame of reference of the moving lithosphere (velocity v), which has spatial coordinate + + + + + x + ′ + + = + x + − + v + t + , + + + {\displaystyle x'=x-vt,} + + + + + + T + = + T + ( + + x + ′ + + , + z + , + t + ) + . + + + {\displaystyle T=T(x',z,t).} + + and the heat equation is: + + + + + + + + ∂ + T + + + ∂ + t + + + + = + κ + + ∇ + + 2 + + + T + = + κ + + + + + ∂ + + 2 + + + T + + + + ∂ + + 2 + + + z + + + + + + κ + + + + + ∂ + + 2 + + + T + + + + ∂ + + 2 + + + + x + ′ + + + + + + + {\displaystyle {\frac {\partial T}{\partial t}}=\kappa \nabla ^{2}T=\kappa {\frac {\partial ^{2}T}{\partial ^{2}z}}+\kappa {\frac {\partial ^{2}T}{\partial ^{2}x'}}} + + +where + + + + κ + + + {\displaystyle \kappa } + + is the thermal diffusivity of the mantle lithosphere. +Since T depends on x' and t only through the combination + + + + x + = + + x + ′ + + + + v + t + , + + + {\displaystyle x=x'+vt,} + +: + + + + + + + + ∂ + T + + + ∂ + + x + ′ + + + + + = + + + 1 + v + + + ⋅ + + + + ∂ + T + + + ∂ + t + + + + + + {\displaystyle {\frac {\partial T}{\partial x'}}={\frac {1}{v}}\cdot {\frac {\partial T}{\partial t}}} + + +Thus: + + + + + + + + ∂ + T + + + ∂ + t + + + + = + κ + + ∇ + + 2 + + + T + = + κ + + + + + ∂ + + 2 + + + T + + + + ∂ + + 2 + + + z + + + + + + + + κ + + v + + 2 + + + + + + + + + ∂ + + 2 + + + T + + + + ∂ + + 2 + + + t + + + + + + {\displaystyle {\frac {\partial T}{\partial t}}=\kappa \nabla ^{2}T=\kappa {\frac {\partial ^{2}T}{\partial ^{2}z}}+{\frac {\kappa }{v^{2}}}{\frac {\partial ^{2}T}{\partial ^{2}t}}} + + +It is assumed that + + + + v + + + {\displaystyle v} + + is large compared to other scales in the problem; therefore the last term in the equation is neglected, giving a 1-dimensional diffusion equation: + + + + + + + + ∂ + T + + + ∂ + t + + + + = + κ + + + + + ∂ + + 2 + + + T + + + + ∂ + + 2 + + + z + + + + + + {\displaystyle {\frac {\partial T}{\partial t}}=\kappa {\frac {\partial ^{2}T}{\partial ^{2}z}}} + + +with the initial conditions + + + + + T + ( + t + = + 0 + ) + = + + T + + 1 + + + ⋅ + Θ + ( + − + z + ) + . + + + {\displaystyle T(t=0)=T_{1}\cdot \Theta (-z).} + + +The solution for + + + + z + ≤ + 0 + + + {\displaystyle z\leq 0} + + is given by the error function: + + + + + T + ( + + x + ′ + + , + z + , + t + ) + = + + T + + 1 + + + ⋅ + erf + ⁡ + + ( + + + z + + 2 + + + κ + t + + + + + + ) + + + + {\displaystyle T(x',z,t)=T_{1}\cdot \operatorname {erf} \left({\frac {z}{2{\sqrt {\kappa t}}}}\right)} + +. +Due to the large velocity, the temperature dependence on the horizontal direction is negligible, and the height at time t (i.e. of sea floor of age t) can be calculated by integrating the thermal expansion over z: + + + + + h + ( + t + ) + = + + h + + 0 + + + + + + α + + + e + f + f + + + + + ∫ + + 0 + + + ∞ + + + [ + T + ( + z + ) + − + + T + + 1 + + + ] + d + z + = + + h + + 0 + + + − + + + 2 + + π + + + + + α + + + e + f + f + + + + + T + + 1 + + + + + κ + t + + + + + {\displaystyle h(t)=h_{0}+\alpha _{\mathrm {eff} }\int _{0}^{\infty }[T(z)-T_{1}]dz=h_{0}-{\frac {2}{\sqrt {\pi }}}\alpha _{\mathrm {eff} }T_{1}{\sqrt {\kappa t}}} + \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Seafloor_spreading-3.md b/data/en.wikipedia.org/wiki/Seafloor_spreading-3.md new file mode 100644 index 000000000..0164fb10d --- /dev/null +++ b/data/en.wikipedia.org/wiki/Seafloor_spreading-3.md @@ -0,0 +1,720 @@ +--- +title: "Seafloor spreading" +chunk: 4/4 +source: "https://en.wikipedia.org/wiki/Seafloor_spreading" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:23.036062+00:00" +instance: "kb-cron" +--- + +where + + + + + α + + + e + f + f + + + + + + {\displaystyle \alpha _{\mathrm {eff} }} + + is the effective volumetric thermal expansion coefficient, and h0 is the mid-ocean ridge height (compared to some reference). +The assumption that v is relatively large is equivalent to the assumption that the thermal diffusivity + + + + κ + + + {\displaystyle \kappa } + + is small compared to + + + + + L + + 2 + + + + / + + A + + + {\displaystyle L^{2}/A} + +, where L is the ocean width (from mid-ocean ridges to continental shelf) and A is the age of the ocean basin. +The effective thermal expansion coefficient + + + + + α + + + e + f + f + + + + + + {\displaystyle \alpha _{\mathrm {eff} }} + + is different from the usual thermal expansion coefficient + + + + α + + + {\displaystyle \alpha } + + due to isostasic effect of the change in water column height above the lithosphere as it expands or retracts. Both coefficients are related by: + + + + + + α + + + e + f + f + + + + = + α + ⋅ + + + ρ + + ρ + − + + ρ + + w + + + + + + + + {\displaystyle \alpha _{\mathrm {eff} }=\alpha \cdot {\frac {\rho }{\rho -\rho _{w}}}} + + +where + + + + ρ + ∼ + 3.3 + + + g + + ⋅ + + + c + m + + + − + 3 + + + + + {\displaystyle \rho \sim 3.3\ \mathrm {g} \cdot \mathrm {cm} ^{-3}} + + is the rock density and + + + + + ρ + + 0 + + + = + 1 + + + g + + ⋅ + + + c + m + + + − + 3 + + + + + {\displaystyle \rho _{0}=1\ \mathrm {g} \cdot \mathrm {cm} ^{-3}} + + is the density of water. +By substituting the parameters by their rough estimates: + + + + + + + + + κ + + + + ∼ + 8 + ⋅ + + 10 + + − + 7 + + + + + + m + + + 2 + + + ⋅ + + + s + + + − + 1 + + + + + + + α + + + + ∼ + 4 + ⋅ + + 10 + + − + 5 + + + + + + + + + ∘ + + + + + C + + + − + 1 + + + + + + + + T + + 1 + + + + + + ∼ + 1220 + + + + + + + ∘ + + + + C + + + + + + for the Atlantic and Indian oceans + + + + + + + T + + 1 + + + + + + ∼ + 1120 + + + + + + + ∘ + + + + C + + + + + + for the eastern Pacific + + + + + + + + {\displaystyle {\begin{aligned}\kappa &\sim 8\cdot 10^{-7}\ \mathrm {m} ^{2}\cdot \mathrm {s} ^{-1}\\\alpha &\sim 4\cdot 10^{-5}\ {}^{\circ }\mathrm {C} ^{-1}\\T_{1}&\sim 1220\ {}^{\circ }\mathrm {C} &&{\text{for the Atlantic and Indian oceans}}\\T_{1}&\sim 1120\ {}^{\circ }\mathrm {C} &&{\text{for the eastern Pacific}}\end{aligned}}} + + +gives: + + + + + h + ( + t + ) + ∼ + + + { + + + + + h + + 0 + + + − + 390 + + + t + + + + + + for the Atlantic and Indian oceans + + + + + + + h + + 0 + + + − + 350 + + + t + + + + + + for the eastern Pacific + + + + + + + + + + {\displaystyle h(t)\sim {\begin{cases}h_{0}-390{\sqrt {t}}&{\text{for the Atlantic and Indian oceans}}\\h_{0}-350{\sqrt {t}}&{\text{for the eastern Pacific}}\end{cases}}} + + +where the height is in meters and time is in millions of years. To get the dependence on x, one must substitute t = x/v ~ Ax/L, where L is the distance between the ridge to the continental shelf (roughly half the ocean width), and A is the ocean basin age. +Rather than height of the ocean floor + + + + h + ( + t + ) + + + {\displaystyle h(t)} + + above a base or reference level + + + + + h + + b + + + + + {\displaystyle h_{b}} + +, the depth of the ocean + + + + d + ( + t + ) + + + {\displaystyle d(t)} + + is of interest. Because + + + + d + ( + t + ) + + + h + ( + t + ) + = + + h + + b + + + + + {\displaystyle d(t)+h(t)=h_{b}} + +(with + + + + + h + + b + + + + + {\displaystyle h_{b}} + + measured from the ocean surface): + + + + + d + ( + t + ) + = + + h + + b + + + − + + h + + 0 + + + + + 350 + + + t + + + + + {\displaystyle d(t)=h_{b}-h_{0}+350{\sqrt {t}}} + +; for the eastern Pacific for example, where + + + + + h + + b + + + − + + h + + 0 + + + + + {\displaystyle h_{b}-h_{0}} + + is the depth at the ridge crest, typically 2600 m. + +=== Cooling plate model === +The depth predicted by the square root of seafloor age derived above is too deep for seafloor older than 80 million years. Depth is better explained by a cooling lithosphere plate model rather than the cooling mantle half-space. The plate has a constant temperature at its base and spreading edge. Analysis of depth versus age and depth versus square root of age data allowed Parsons and Sclater to estimate model parameters (for the North Pacific): + +~125 km for lithosphere thickness + + + + + + T + + 1 + + + ∼ + 1350 + + + + + + + ∘ + + + + C + + + + {\displaystyle T_{1}\thicksim 1350\ {}^{\circ }\mathrm {C} } + + at base and young edge of plate + + + + + α + ∼ + 3.2 + ⋅ + + 10 + + − + 5 + + + + + + + + + ∘ + + + + + C + + + − + 1 + + + + + {\displaystyle \alpha \thicksim 3.2\cdot 10^{-5}\ {}^{\circ }\mathrm {C} ^{-1}} + + +Assuming isostatic equilibrium everywhere beneath the cooling plate yields a revised age depth relationship for older sea floor that is approximately correct for ages as young as 20 million years: + + + + + d + ( + t + ) + = + 6400 + − + 3200 + exp + ⁡ + + + ( + + + − + t + + / + + 62.8 + + + ) + + + + + {\displaystyle d(t)=6400-3200\exp {\bigl (}-t/62.8{\bigr )}} + + meters +Thus older seafloor deepens more slowly than younger and in fact can be assumed almost constant at ~6400 m depth. Parsons and Sclater concluded that some style of mantle convection must apply heat to the base of the plate everywhere to prevent cooling down below 125 km and lithosphere contraction (seafloor deepening) at older ages. Their plate model also allowed an expression for conductive heat flow, q(t) from the ocean floor, which is approximately constant at + + + + 1 + ⋅ + + 10 + + − + 6 + + + + c + a + l + + + + + c + m + + + − + 2 + + + + + s + e + c + + + − + 1 + + + + + {\displaystyle 1\cdot 10^{-6}\mathrm {cal} \,\mathrm {cm} ^{-2}\mathrm {sec} ^{-1}} + + beyond 120 million years: + + + + + q + ( + t + ) + = + 11.3 + + / + + + + t + + + + + {\displaystyle q(t)=11.3/{\sqrt {t}}} + + +== See also == + +Divergent boundary – Linear feature between two tectonic plates +Vine–Matthews–Morley hypothesis – Concept in plate tectonics +DSV ALVIN the research submersible that explored spreading centers in the Atlantic (Project FAMOUS) and Pacific Oceans (RISE project). + +== References == + +== External links == + +Animation of a mid-ocean ridge Archived 2009-01-15 at the Wayback Machine \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Seawater-0.md b/data/en.wikipedia.org/wiki/Seawater-0.md new file mode 100644 index 000000000..2a037a4fe --- /dev/null +++ b/data/en.wikipedia.org/wiki/Seawater-0.md @@ -0,0 +1,32 @@ +--- +title: "Seawater" +chunk: 1/6 +source: "https://en.wikipedia.org/wiki/Seawater" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:24.439623+00:00" +instance: "kb-cron" +--- + +Seawater, or sea water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximately 35 grams (1.2 oz) of dissolved salts (predominantly sodium (Na+) and chloride (Cl−) ions). The average density at the surface is 1.025 kg/L. Seawater is denser than both fresh water and pure water (density 1.0 kg/L at 4 °C (39 °F)) because the dissolved salts increase the mass by a larger proportion than the volume. The freezing point of seawater decreases as salt concentration increases. At typical salinity, it freezes at about −2 °C (28 °F). The coldest seawater still in the liquid state ever recorded was found in 2010, in a stream under an Antarctic glacier: the measured temperature was −2.6 °C (27.3 °F). +Seawater pH is typically limited to a range between 7.5 and 8.4. However, there is no universally accepted reference pH-scale for seawater and the difference between measurements based on different reference scales may be up to 0.14 units. + +== Properties == + +=== Salinity === + +Although the vast majority of seawater has a salinity of between 31 and 38 g/kg, that is 3.1–3.8%, seawater is not uniformly saline throughout the world. Where mixing occurs with freshwater runoff from river mouths, near melting glaciers or vast amounts of precipitation (e.g. monsoon), seawater can be substantially less saline. The most saline open sea is the Red Sea, where high rates of evaporation, low precipitation and low river run-off, and confined circulation result in unusually salty water. The salinity in isolated bodies of water can be considerably greater still – about ten times higher in the case of the Dead Sea. Historically, several salinity scales were used to approximate the absolute salinity of seawater. A popular scale was the "Practical Salinity Scale" where salinity was measured in "practical salinity units (PSU)". The current standard for salinity is the "Reference Salinity" scale with the salinity expressed in units of "g/kg". + +=== Density === +The density of surface seawater ranges from about 1020 to 1029 kg/m3, depending on the temperature and salinity. At a temperature of 25 °C, the salinity of 35 g/kg and 1 atm pressure, the density of seawater is 1023.6 kg/m3. Deep in the ocean, under high pressure, seawater can reach a density of 1050 kg/m3 or higher. The density of seawater also changes with salinity. Brines generated by seawater desalination plants can have salinities up to 120 g/kg. The density of typical seawater brine of 120 g/kg salinity at 25 °C and atmospheric pressure is 1088 kg/m3. + +=== pH value === + +The pH value at the surface of oceans in pre-industrial time (before 1850) was around 8.2. Since then, it has been decreasing due to a human-caused process called ocean acidification that is related to carbon dioxide emissions: Between 1950 and 2020, the average pH of the ocean surface fell from approximately 8.15 to 8.05. +The pH value of seawater is naturally as low as 7.8 in deep ocean waters as a result of the degradation of organic matter in these waters. It can be as high as 8.4 in surface waters in areas of high biological productivity. +Measurement of pH is complicated by the chemical properties of seawater, and several distinct pH scales exist in chemical oceanography. There is no universally accepted reference pH-scale for seawater and the difference between measurements based on different reference scales may be up to 0.14 units. + +=== Chemical composition === + +Seawater contains more dissolved ions than all types of freshwater. However, the ratios of solutes differ dramatically. For instance, although seawater contains about 2.8 times more bicarbonate than river water, the percentage of bicarbonate in seawater as a ratio of all dissolved ions is far lower than in river water. Bicarbonate ions constitute 48% of river water solutes but only 0.14% for seawater. Differences like these are due to the varying residence times of seawater solutes; sodium and chloride have very long residence times, while calcium (vital for carbonate formation) tends to precipitate much more quickly. The most abundant dissolved ions in seawater are sodium, chloride, magnesium, sulfate and calcium. Its osmolarity is about 1000 mOsm/L. +Small amounts of other substances are found, including amino acids at concentrations of up to 2 micrograms of nitrogen atoms per liter, which are thought to have played a key role in the origin of life. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Seawater-1.md b/data/en.wikipedia.org/wiki/Seawater-1.md new file mode 100644 index 000000000..51c1c9cce --- /dev/null +++ b/data/en.wikipedia.org/wiki/Seawater-1.md @@ -0,0 +1,25 @@ +--- +title: "Seawater" +chunk: 2/6 +source: "https://en.wikipedia.org/wiki/Seawater" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:24.439623+00:00" +instance: "kb-cron" +--- + +=== Microbial components === +Research in 1957 by the Scripps Institution of Oceanography sampled water in both pelagic and neritic locations in the Pacific Ocean. Direct microscopic counts and cultures were used, the direct counts in some cases showing up to 10 000 times that obtained from cultures. These differences were attributed to the occurrence of bacteria in aggregates, selective effects of the culture media, and the presence of inactive cells. A marked reduction in bacterial culture numbers was noted below the thermocline, but not by direct microscopic observation. Large numbers of spirilli-like forms were seen by microscope but not under cultivation. The disparity in numbers obtained by the two methods is well known in this and other fields. In the 1990s, improved techniques of detection and identification of microbes by probing just small snippets of DNA, enabled researchers taking part in the Census of Marine Life to identify thousands of previously unknown microbes usually present only in small numbers. This revealed a far greater diversity than previously suspected, so that a litre of seawater may hold more than 20,000 species. Mitchell Sogin from the Marine Biological Laboratory feels that "the number of different kinds of bacteria in the oceans could eclipse five to 10 million." +Bacteria are found at all depths in the water column, as well as in the sediments, some being aerobic, others anaerobic. Most are free-swimming, but some exist as symbionts within other organisms – examples of these being bioluminescent bacteria. Cyanobacteria played an important role in the evolution of ocean processes, enabling the development of stromatolites and oxygen in the atmosphere. +Some bacteria interact with diatoms, and form a critical link in the cycling of silicon in the ocean. One anaerobic species, Thiomargarita namibiensis, plays an important part in the breakdown of hydrogen sulfide eruptions from diatomaceous sediments off the Namibian coast, and generated by high rates of phytoplankton growth in the Benguela Current upwelling zone, eventually falling to the seafloor. +Bacteria-like Archaea surprised marine microbiologists by their survival and thriving in extreme environments, such as the hydrothermal vents on the ocean floor. Alkalotolerant marine bacteria such as Pseudomonas and Vibrio spp. survive in a pH range of 7.3 to 10.6, while some species will grow only at pH 10 to 10.6. Archaea also exist in pelagic waters and may constitute as much as half the ocean's biomass, clearly playing an important part in oceanic processes. In 2000 sediments from the ocean floor revealed a species of Archaea that breaks down methane, an important greenhouse gas and a major contributor to atmospheric warming. Some bacteria break down the rocks of the sea floor, influencing seawater chemistry. Oil spills, and runoff containing human sewage and chemical pollutants have a marked effect on microbial life in the vicinity, as well as harbouring pathogens and toxins affecting all forms of marine life. The protist dinoflagellates may at certain times undergo population explosions called blooms or red tides, often after human-caused pollution. The process may produce metabolites known as biotoxins, which move along the ocean food chain, tainting higher-order animal consumers. +Pandoravirus salinus, a species of very large virus, with a genome much larger than that of any other virus species, was discovered in 2013. Like the other very large viruses Mimivirus and Megavirus, Pandoravirus infects amoebas, but its genome, containing 1.9 to 2.5 megabases of DNA, is twice as large as that of Megavirus, and it differs greatly from the other large viruses in appearance and in genome structure. +In 2013, researchers from Aberdeen University announced that they were starting a hunt for undiscovered chemicals in organisms that have evolved in deep sea trenches, hoping to find "the next generation" of antibiotics, anticipating an "antibiotic apocalypse" with a dearth of new infection-fighting drugs. The EU-funded research will start in the Atacama Trench and then move on to search trenches off New Zealand and Antarctica. +The ocean has a long history of human waste disposal on the assumption that its vast size makes it capable of absorbing and diluting all noxious material. +While this may be true on a small scale, the large amounts of sewage routinely dumped has damaged many coastal ecosystems, and rendered them life-threatening. Pathogenic viruses and bacteria occur in such waters, such as Escherichia coli, Vibrio cholerae the cause of cholera, hepatitis A, hepatitis E and polio, along with protozoans causing giardiasis and cryptosporidiosis. These pathogens are routinely present in the ballast water of large vessels, and are widely spread when the ballast is discharged. + +=== Other parameters === +The speed of sound in seawater is about 1,500 m/s (whereas the speed of sound is usually around 330 m/s in air at roughly 101.3 kPa pressure, 1 atmosphere), and varies with water temperature, salinity, and pressure. The thermal conductivity of seawater is 0.6 W/mK at 25 °C and a salinity of 35 g/kg. +The thermal conductivity decreases with increasing salinity and increases with increasing temperature. + +== Origin and history == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Seawater-2.md b/data/en.wikipedia.org/wiki/Seawater-2.md new file mode 100644 index 000000000..2a009ac47 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Seawater-2.md @@ -0,0 +1,23 @@ +--- +title: "Seawater" +chunk: 3/6 +source: "https://en.wikipedia.org/wiki/Seawater" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:24.439623+00:00" +instance: "kb-cron" +--- + +The water in the sea was thought to come from the Earth's volcanoes, starting 4 billion years ago, released by degassing from molten rock. More recent work suggests much of the Earth's water may come from comets. +Scientific theories behind the origins of sea salt started with Sir Edmond Halley in 1715, who proposed that salt and other minerals were carried into the sea by rivers after rainfall washed it out of the ground. Upon reaching the ocean, these salts concentrated as more salt arrived over time (see Hydrologic cycle). Halley noted that most lakes that do not have ocean outlets (such as the Dead Sea and the Caspian Sea, see endorheic basin), have high salt content. Halley termed this process "continental weathering". +Halley's theory was partly correct. In addition, sodium leached out of the ocean floor when the ocean formed. The presence of salts other dominant ion, chloride, results from outgassing of chloride (as hydrochloric acid) with other gases from Earth's interior via volcanos and hydrothermal vents. The sodium and chloride ions subsequently became the most abundant constituents of sea salt. +Ocean salinity has been stable for billions of years, most likely as a consequence of a chemical/tectonic system which removes as much salt as is deposited; for instance, sodium and chloride sinks include evaporite deposits, pore-water burial, and reactions with seafloor basalts. + +== Human impacts == + +Climate change, rising levels of carbon dioxide in Earth's atmosphere, excess nutrients, and pollution in many forms are altering global oceanic geochemistry. Rates of change for some aspects greatly exceed those in the historical and recent geological record. Major trends include an increasing acidity, reduced subsurface oxygen in both near-shore and pelagic waters, rising coastal nitrogen levels, and widespread increases in mercury and persistent organic pollutants. Most of these perturbations are tied either directly or indirectly to human fossil fuel combustion, fertilizer, and industrial activity. Concentrations are projected to grow in coming decades, with negative impacts on ocean biota and other marine resources. +One of the most striking features of this is ocean acidification, resulting from increased CO2 uptake of the oceans related to higher atmospheric concentration of CO2 and higher temperatures, because it severely affects coral reefs, mollusks, echinoderms and crustaceans (see coral bleaching). +Seawater is a means of transportation throughout the world. Every day plenty of ships cross the ocean to deliver goods to various locations around the world. Seawater is a tool for countries to efficiently participate in international commercial trade and transportation, but each ship exhausts emissions that can harm marine life, air quality of coastal areas. Seawater transportation is one of the fastest growing human generated greenhouse gas emissions. The emissions released from ships pose significant risks to human health in nearing areas as the oil and gas released from the operation of merchant ships decreases the air quality and causes more pollution both in the seawater and surrounding areas. +Another human use of seawater that has been considered is the use of seawater for agricultural purposes. In areas with higher regions of sand dunes, such as Israel, the use of seawater for irrigation of plants would eliminate substantial costs associated with fresh water when it is not easily accessible. Although it is not typical to use salt water as a means to grow plants as the salt gathers and ruins the surrounding soil, it has been proven to be successful in sand and gravel soils. Large-scale desalination of seawater is another factor that would contribute to the success of agriculture farming in dry, desert environments. One of the most successful plants in salt water agriculture is the halophyte. The halophyte is a salt tolerant plant whose cells are resistant to the typically detrimental effects of salt in soil. The endodermis forces a higher level of salt filtration throughout the plant as it allows for the circulation of more water through the cells. The cultivation of halophytes irrigated with salt water were used to grow animal feed for livestock; however, the animals that were fed these plants consumed more water than those that did not. Although agriculture from use of saltwater is still not recognized and used on a large scale, initial research has shown that there could be an opportunity to provide more crops in regions where agricultural farming is not usually feasible. + +== Human consumption == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Seawater-3.md b/data/en.wikipedia.org/wiki/Seawater-3.md new file mode 100644 index 000000000..fe7275c40 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Seawater-3.md @@ -0,0 +1,27 @@ +--- +title: "Seawater" +chunk: 4/6 +source: "https://en.wikipedia.org/wiki/Seawater" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:24.439623+00:00" +instance: "kb-cron" +--- + +Accidentally consuming small quantities of clean seawater is not harmful, especially if the seawater is taken along with a larger quantity of fresh water. However, drinking seawater to maintain hydration is counterproductive; more water must be excreted to eliminate the salt (via urine) than the amount of water obtained from the seawater itself. In normal circumstances, it would be considered ill-advised to consume large amounts of unfiltered seawater. +The renal system actively regulates the levels of sodium and chloride in the blood within a very narrow range around 9 g/L (0.9% by mass). +In most open waters, concentrations vary somewhat around typical values of about 3.5%, far higher than the body can tolerate and most beyond what the kidney can process. A point frequently overlooked in claims that the kidney can excrete NaCl in Baltic concentrations of 2% (in arguments to the contrary) is that the gut cannot absorb water at such concentrations, so that there is no benefit in drinking such water. The salinity of Baltic surface water, however, is never 2%; it is 0.9% or less, and thus never higher than that of bodily fluids. Drinking seawater temporarily increases blood's NaCl concentration. This signals the kidney to excrete sodium, but seawater's sodium concentration is above the kidney's maximum concentrating ability. Eventually, the blood's sodium concentration rises to toxic levels, removing water from cells and interfering with nerve conduction, ultimately producing fatal seizure and cardiac arrhythmia. +Survival manuals consistently advise against drinking seawater. A summary of 163 life raft voyages estimated the risk of death at 39% for those who drank seawater, compared to 3% for those who did not. The effect of seawater intake on rats confirmed the negative effects of drinking seawater when dehydrated. +The temptation to drink seawater was greatest for sailors who had expended their supply of fresh water and were unable to capture enough rainwater for drinking. This frustration was described famously by a line from Samuel Taylor Coleridge's The Rime of the Ancient Mariner: + +Although humans cannot survive on seawater in place of normal drinking water, some people claim that up to two cups a day, mixed with fresh water in a 2:3 ratio, produces no ill effect. The French physician Alain Bombard survived an ocean crossing in a small Zodiak rubber boat using mainly raw fish meat, which contains about 40% water (like most living tissues), as well as small amounts of seawater and other provisions harvested from the ocean. His findings were challenged, but an alternative explanation could not be given. In his 1948 book The Kon-Tiki Expedition, Thor Heyerdahl reported drinking seawater mixed with fresh in a 2:3 ratio during the 1947 expedition. A few years later, another adventurer, William Willis, claimed to have drunk two cups of seawater and one cup of fresh per day for 70 days without ill effect when he lost part of his water supply. +During the 18th century, Richard Russell advocated the medical use of this practice in the UK, and René Quinton expanded the advocation of this practice to other countries, notably France, in the 20th century. Currently, it is widely practiced in Nicaragua and other countries, supposedly taking advantage of the latest medical discoveries. + +=== Purification === +Like any other type of raw or contaminated water, seawater can be evaporated or filtered to eliminate salt, germs, and other contaminants that would otherwise prevent it from being considered potable. Most oceangoing vessels desalinate potable water from seawater using processes such as vacuum distillation or multi-stage flash distillation in an evaporator, or, more recently, reverse osmosis. These energy-intensive processes were not usually available during the Age of Sail. Larger sailing warships with large crews, such as Nelson's HMS Victory, were fitted with distilling apparatus in their galleys. +The natural sea salt obtained by evaporating seawater can also be collected and sold as table salt, typically sold separately owing to its unique mineral make-up compared to rock salt or other sources. +A number of regional cuisines across the world traditionally incorporate seawater directly as an ingredient, cooking other ingredients in a diluted solution of filtered seawater as a substitute for conventional dry seasonings. Proponents include world-renowned chefs Ferran Adrià and Quique Dacosta, whose home country of Spain has six different companies sourcing filtered seawater for culinary use. The water is marketed as la sal perfecta, "the perfect salt", containing less sodium with what is considered a superior taste. A restaurant run by Joaquín Baeza sources as much as 60,000 litres a month from supplier Mediterranea +Animals such as fish, whales, sea turtles, and seabirds, such as penguins and albatrosses, have adapted to living in a high-saline habitat. For example, sea turtles and saltwater crocodiles remove excess salt from their bodies through their tear ducts. + +== Mineral extraction == +Minerals have been extracted from seawater since ancient times. Currently the four most concentrated metals – Na, Mg, Ca and K – are commercially extracted from seawater. During 2015 in the US 63% of magnesium production came from seawater and brines. Bromine is also produced from seawater in China and Japan. Lithium extraction from seawater was tried in the 1970s, but the tests were soon abandoned. The idea of extracting uranium from seawater has been considered at least from the 1960s, but only a few grams of uranium were extracted in Japan in the late 1990s. The main issue is not one of technological feasibility but that current prices on the uranium market for uranium from other sources are about three to five times lower than the lowest price achieved by seawater extraction. Similar issues hamper the use of reprocessed uranium and are often brought forth against nuclear reprocessing and the manufacturing of MOX fuel as economically unviable. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Seawater-4.md b/data/en.wikipedia.org/wiki/Seawater-4.md new file mode 100644 index 000000000..7deea4695 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Seawater-4.md @@ -0,0 +1,27 @@ +--- +title: "Seawater" +chunk: 5/6 +source: "https://en.wikipedia.org/wiki/Seawater" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:24.439623+00:00" +instance: "kb-cron" +--- + +=== The future of mineral and element extractions === +In order for seawater mineral and element extractions to take place while taking close consideration of sustainable practices, it is necessary for monitored management systems to be put in place. This requires management of ocean areas and their conditions, environmental planning, structured guidelines to ensure that extractions are controlled, regular assessments of the condition of the sea post-extraction, and constant monitoring. The use of technology, such as underwater drones, can facilitate sustainable extractions. The use of low-carbon infrastructure would also allow for more sustainable extraction processes while reducing the carbon footprint from mineral extractions. + +Another practice that is being considered closely is the process of desalination in order to achieve a more sustainable water supply from seawater. Although desalination also comes with environmental concerns, such as costs and resources, researchers are working closely to determine more sustainable practices, such as creating more productive water plants that can deal with larger water supplies in areas where these plans weren't always available. Although seawater extractions can benefit society greatly, it is crucial to consider the environmental impact and to ensure that all extractions are conducted in a way that acknowledges and considers the associated risks to the sustainability of seawater ecosystems. + +== Standard == +ASTM International has an international standard for artificial seawater: ASTM D1141-98 (Original Standard ASTM D1141-52). It is used in a variety of research testing labs as a reproducible solution for seawater such as tests on corrosion, oil contamination, and detergency evaluation. + +== Ecosystems == + +The minerals found in seawater can also play an important role in the ocean and its ecosystem's food cycle. For example, the Southern Ocean contributes greatly to the environmental carbon cycle. Given that this body of water does not contain high levels of iron, the deficiency impacts the marine life living in its waters. As a result, this ocean is not able to produce as much phytoplankton which hinders the first source of the marine food chain. One of the main types of phytoplankton are diatoms which is the primary food source of Antarctic krill. As the cycle continues, various larger sea animals feed off of Antarctic krill, but since there is a shortage of iron from the initial phytoplankton/diatoms, then these larger species also lack iron. The larger sea animals include Baleen Whales such as the Blue Whale and Fin Whale. These whales not only rely on iron for a balance of minerals within their diet, but it also impacts the amount of iron that is regenerated back into the ocean. The whale's excretions also contain the absorbed iron which would allow iron to be reinserted into the ocean’s ecosystem. Overall, one mineral deficiency such as iron in the Southern Ocean can spark a significant chain of disturbances within the marine ecosystems which demonstrates the important role that seawater plays in the food chain. +Upon further analysis of the dynamic relationship between diatoms, krill, and baleen whales, fecal samples of baleen whales were examined in Antarctic seawater. The findings included that iron concentrations were 10 million times higher than those found in Antarctic seawater, and krill was found consistently throughout their feces which is an indicator that krill is in whale diets. Antarctic krill had an average iron level of 174.3mg/kg dry weight, but the iron in the krill varied from 12 to 174 mg/kg dry weight. The average iron concentration of the muscular tissue of blue whales and fin whales was 173 mg/kg dry weight, which demonstrates that the large marine mammals are important to marine ecosystems such as they are to the Southern Ocean. In fact, to have more whales in the ocean could heighten the amount of iron in seawater through their excretions which would promote a better ecosystem. +Krill and baleen whales act as large iron reservoirs in seawater in the Southern Ocean. Krill can retain up to 24% of iron found on surface waters within its range.The process of krill feeding on diatoms releases iron into seawater, highlighting them as an important part of the ocean's iron cycle. The advantageous relationship between krill and baleen whales increases the amount of iron that can be recycled and stored in seawater. A positive feedback loop is created, increasing the overall productivity of marine life in the Southern Ocean. +Organisms of all sizes play a significant role in the balance of marine ecosystems with both the largest and smallest inhabitants contributing equally to recycling nutrients in seawater. Prioritizing the recovery of whale populations because they boost the overall productivity in marine ecosystems as well as increasing iron levels in seawater would allow for a balanced and productive system for the ocean. However, a more in depth study is required to understand the benefits of whale feces as a fertilizer and to provide further insight in iron recycling in the Southern Ocean. Projects on the management of ecosystems and conservation are vital for advancing knowledge of marine ecology. + +== Environmental impact and sustainability == +Like any mineral extraction practices, there are environmental advantages and disadvantages. Cobalt and Lithium are two key metals that can be used for aiding with more environmentally friendly technologies above ground, such as powering batteries that energize electric vehicles or creating wind power. An environmentally friendly approach to mining that allows for more sustainability would be to extract these metals from the seafloor. Lithium mining from the seafloor at mass quantities could provide a substantial amount of renewable metals to promote more environmentally friendly practices in society to reduce humans' carbon footprint. Lithium mining from the seafloor could be successful, but its success would be dependent on more productive recycling practices above ground. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Seawater-5.md b/data/en.wikipedia.org/wiki/Seawater-5.md new file mode 100644 index 000000000..34f8886c2 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Seawater-5.md @@ -0,0 +1,37 @@ +--- +title: "Seawater" +chunk: 6/6 +source: "https://en.wikipedia.org/wiki/Seawater" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:24.439623+00:00" +instance: "kb-cron" +--- + +There are also risks that come with extracting from the seafloor. Many biodiverse species have long lifespans on the seafloor, which means that their reproduction takes more time. Similarly to fish harvesting from the seafloor, the extraction of minerals in large amounts, too quickly, without proper protocols, can result in a disruption of the underwater ecosystems. Contrarily, this would have the opposite effect and prevent mineral extractions from being a long-term sustainable practice, and would result in a shortage of required metals. Any seawater mineral extractions also risk disrupting the habitat of the underwater life that is dependent on the uninterrupted ecosystem within their environment as disturbances can have significant disturbances on animal communities. + +== See also == + +Artificial seawater – Mixture of dissolved salts simulating the mean seawater composition +Brackish water – Water with salinity between freshwater and seawater +Brine – Concentrated solution of salt in water +Brine mining – Extracting materials from saltwater +CORA dataset – Oceanographic temperature and salinity dataset global ocean salinity +Fresh water – Naturally occurring water with low amounts of dissolved salts +Ocean color – Explanation of the color of oceans and ocean color remote sensing +Saline water – Water that contains a high concentration of dissolved salts +Sea ice – Outcome of seawater as it freezes +Seawater pH – Measure of the level of acidity or basicity of an aqueous solution +Surface tension of seawater – Tendency of a liquid surface to shrink to reduce surface area +Thalassotherapy – Form of therapy using seawater +Thermohaline circulation – Part of large-scale ocean circulation + +== References == + +== External links == + +Technical Papers in Marine Science 44, Algorithms for computation of fundamental properties of seawater, ioc-unesco.org, UNESCO 1983 +Tables + +Tables and software for thermophysical properties of seawater, MIT +G. W. C Kaye, T. H. Laby (1995). "Physical properties of sea water". Tables of physical and chemical constants (16th ed.). Bibcode:1995tpcc.book.....K. Archived from the original on 8 May 2019. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Shoal-0.md b/data/en.wikipedia.org/wiki/Shoal-0.md new file mode 100644 index 000000000..2013ab710 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Shoal-0.md @@ -0,0 +1,52 @@ +--- +title: "Shoal" +chunk: 1/2 +source: "https://en.wikipedia.org/wiki/Shoal" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:25.722002+00:00" +instance: "kb-cron" +--- + +A shoal is a natural submerged ridge, bank, or bar that consists of, or is covered by, sand or other unconsolidated material, and rises from the bed of a body of water close to the surface or above it, which poses a danger to navigation. Shoals are also known in oceanography, geomorphology, and geoscience, as sandbanks, sandbars, gravelbars, or bars. Two or more shoals that are either separated by shared troughs or interconnected by past or present sedimentary and hydrographic processes are referred to as a shoal complex. +Other uses of the term shoal either similar to or quite different from its application in geologic, geomorphic, and oceanographic literature, include any relatively shallow place in a stream, lake, sea, or other body of water; a rocky area on the seafloor within an area mapped for navigation purposes; or a growth of vegetation on the bottom of a deep lake, that occurs at any depth, or is used as a verb for the process of proceeding from a greater to a lesser depth of water. + +== Description == +Shoals are characteristically long and narrow (linear) ridges. They can develop where a stream, river, or ocean current promotes deposition of sediment and granular material, resulting in localized shallowing (shoaling) of the water. Marine shoals also develop either by the in-place drowning of barrier islands as the result of episodic sea level rise or by the erosion and submergence of inactive delta lobes. +Shoals can appear as a coastal landform in the sea, where they are classified as a type of ocean bank, or as fluvial landforms in rivers, streams, and lakes. +A shoal–sandbar may seasonally separate a smaller body of water from the sea, such as: + +Marine lagoons +Brackish water estuaries +Freshwater seasonal stream and river mouths and deltas. +The term bar can apply to landform features spanning a considerable range in size, from a length of a few meters in a small stream to marine depositions stretching for hundreds of kilometers along a coastline, often called barrier islands. + +=== Composition === +They are typically composed of sand, although they could be of any granular matter that the moving water has access to and is capable of shifting around (for example, soil, silt, gravel, cobble, shingle, or even boulders). The grain size of the material comprising a bar is related to the size of the waves or the strength of the currents moving the material, but the availability of material to be worked by waves and currents is also important. + +== Formation == + +Wave shoaling is the process when surface waves move towards shallow water, such as a beach, they slow down, their wave height increases and the distance between waves decreases. This behavior is called shoaling, and the waves are said to shoal. The waves may or may not build to the point where they break, depending on how large they were to begin with, and how steep the slope of the beach is. In particular, waves shoal as they pass over submerged sandbanks or reefs. This can be treacherous for boats and ships. +Shoaling can also refract waves, so the waves change direction. For example, if waves pass over a sloping bank which is shallower at one end than the other, then the shoaling effect will result in the waves slowing more at the shallow end. Thus, the wave fronts will refract, changing direction like light passing through a prism. Refraction also occurs as waves move towards a beach if the waves come in at an angle to the beach, or if the beach slopes more gradually at one end than the other. + +=== Types === + +==== Sandbars and longshore bars ==== + +Sandbars, also known as a trough bars, form where the waves are breaking, because the breaking waves set up a shoreward current with a compensating counter-current along the bottom. Sometimes this occurs seaward of a trough (marine landform). +Sand carried by the offshore moving bottom current is deposited where the current reaches the wave break. Other longshore bars may lie further offshore, representing the break point of even larger waves, or the break point at low tide. + +==== Peresyp ==== + +In Russian tradition of geomorphology, a peresyp is a sandbar that rises above the water level (like a spit) and separates a liman or a lagoon from the sea. Unlike tombolo bars, a peresyp seldom forms a contiguous strip and usually has one or several channels that connect the liman and the sea. + +==== Harbor and river bars ==== + +A harbor or river bar is a sedimentary deposit formed at a harbor entrance or river mouth by the deposition of freshwater sediment or by the action of waves on the sea floor or on up-current beaches. +Where beaches are suitably mobile, or the river's suspended or bed loads are large enough, deposition can build up a sandbar that completely blocks a river mouth and dams the river. It can be a seasonally natural process of aquatic ecology, causing the formation of estuaries and wetlands in the lower course of the river. This situation will persist until the bar is eroded by the sea, or the dammed river develops sufficient head to break through the bar. +The formation of harbor bars that prevent access for boats and shipping can be the result of: + +construction up-coast or at the harbor — e.g.: breakwaters, dune habitat destruction. +upriver development — e.g.: dams and reservoirs, riparian zone destruction, river bank alterations, river adjacent agricultural land practices, water diversions. +watershed erosion from habitat alterations — e.g.: deforestation, wildfires, grading for development. +artificially created/deepened harbors that require periodic dredging maintenance. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Shoal-1.md b/data/en.wikipedia.org/wiki/Shoal-1.md new file mode 100644 index 000000000..3337099b0 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Shoal-1.md @@ -0,0 +1,36 @@ +--- +title: "Shoal" +chunk: 2/2 +source: "https://en.wikipedia.org/wiki/Shoal" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:25.722002+00:00" +instance: "kb-cron" +--- + +===== Nautical navigation ===== +In a nautical sense, a bar is a shoal, similar to a reef: a shallow formation of (usually) sand that is a navigation or grounding hazard, with a depth of water of 6 fathoms (11 meters) or less. It therefore applies to a silt accumulation that shallows the entrance to or course of a river, or creek. A bar can form a dangerous obstacle to shipping, preventing access to the river or harbor in poor weather conditions or at some states of the tide. + +== Geological units == + +However, in addition to longshore bars discussed above that are relatively small features of a beach, the term shoal can be applied to larger geological units that form off a coastline as part of the process of coastal erosion, such as spits and baymouth bars that form across the front of embayments and rias. A tombolo is a bar that forms an isthmus between an island or offshore rock and a mainland shore. +In places of reentrance along a coastline (such as inlets, coves, rias, and bays), sediments carried by a longshore current will fall out where the current dissipates, forming a spit. An area of water isolated behind a large bar is called a lagoon. Over time, lagoons may silt up, becoming salt marshes. +In some cases, shoals may be precursors to beach expansion and dunes formation, providing a source of windblown sediment to augment such beach or dunes landforms. + +== Human habitation == +Humans have inhabited shoals since prehistoric times. In some cases the locations provide easy exploitation of marine resources. In modern times, these sites are sometimes chosen for their water access or view, but many such locations are prone to storm damage. +An area in Northwest Alabama is commonly referred to as "The Shoals" by local inhabitants, and one of the cities, Muscle Shoals, is named for such landform and its abundance of mussels. + +== See also == + +Ayre (landform) – Shingle beaches in Orkney and Shetland +Barrier Island – Coastal dune landform that forms by wave and tidal action parallel to the mainland coastPages displaying short descriptions of redirect targets +Bank (geography) – Land alongside a body of water +Coastal Barrier Resources Act — 1982 U.S. law +Reef – Submerged ridge of rock, coral or other material +Tombolo – Deposition landform in which an island is connected to the mainland by a sandy isthmus +The Point of Sangomar – Sand spit located on the Atlantic Ocean at the mouth of the Saloum Delta +Adam's Bridge – Chain of shoals between India and Sri Lanka +List of shoals and sandbanks in the southern North Sea + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Slate_Star_Codex-0.md b/data/en.wikipedia.org/wiki/Slate_Star_Codex-0.md new file mode 100644 index 000000000..46bb3b858 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Slate_Star_Codex-0.md @@ -0,0 +1,37 @@ +--- +title: "Slate Star Codex" +chunk: 1/2 +source: "https://en.wikipedia.org/wiki/Slate_Star_Codex" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:27.225137+00:00" +instance: "kb-cron" +--- + +Astral Codex Ten (ACX), formerly Slate Star Codex (SSC), is a blog focused on science, medicine (especially psychiatry), philosophy, politics, and futurism. The blog is written by Scott Alexander Siskind, a San Francisco Bay Area psychiatrist, under the pen name Scott Alexander. +Slate Star Codex was launched in 2013 and was temporarily discontinued on June 23, 2020. In July 2020 the blog was partially back online, with the content restored but commenting disabled. The successor Substack blog, Astral Codex Ten, was launched on January 21, 2021. + +== Content and author == +The site was a primary venue of the rationalist community and also attracted wider audiences. The New Statesman characterizes it as "a nexus for the rationalist community and others who seek to apply reason to debates about situations, ideas, and moral quandaries." The New Yorker describes Alexander's fiction as "delightfully weird" and his arguments "often counterintuitive and brilliant". Economist Tyler Cowen calls Scott Alexander "a thinker who is influential among other writers". +The New Yorker states that the volume of content Alexander has written on Slate Star Codex makes the blog difficult to summarize, with an e-book of all posts running over nine thousand pages in PDF form. Many posts are book reviews (typically of books in the fields of social sciences or medicine) or reviews of a topic in the scientific literature. For example, the March 2020 blog post "Face Masks: Much More Than You Wanted To Know" analyzes available medical literature and comes to a conclusion that contrary to early guidance by the CDC, masks are likely an effective protection measure against COVID-19 for the general public under certain conditions. Some posts are prefaced with a note on their "epistemic status", an assessment of Alexander's confidence in the material to follow. +Alexander also blogged at the rationalist community blog LessWrong, and wrote a fiction book in blog format named Unsong. Alexander published a revised version of Unsong on May 24, 2024. + +=== Effective altruism === +In 2017, Slate Star Codex ranked fourth on a survey conducted by Rethink Charity of how effective altruists first heard about effective altruism, after "personal contact", "LessWrong", and "other books, articles and blog posts", and just above "80,000 Hours." The blog discusses moral questions and dilemmas relevant to effective altruism, such as moral offsets (the proposition that good acts can cancel out bad acts), ethical treatment of animals, and trade-offs of pursuing systemic change for charities. + +=== Artificial intelligence === +Alexander regularly writes about advances in artificial intelligence and emphasized the importance of AI safety research. +In the long essay "Meditations On Moloch", he analyzes game-theoretic scenarios of cooperation failure like the prisoner's dilemma and the tragedy of the commons that underlie many of humanity's problems and argues that AI risks should be considered in this context. + +=== Controversies and memes === +In "The Toxoplasma of Rage", Alexander discusses how controversies spread in media and social networks. According to Alexander, memes that generate a lot of disagreement spread further, in part because they present an opportunity to members of different groups to send a strong signal of commitment to their cause. For example, he argues that PETA, with its controversial campaigns, is better known than other animal rights organizations such as Vegan Outreach because of this dynamic. Another example of this cited by Alexander is the Rolling Stone article "A Rape on Campus". + +=== Shiri's scissor === +In the short story "Sort By Controversial", Alexander introduces the term "Shiri's scissor" or "scissor statement" to describe a statement that has great destructive power because it generates wildly divergent interpretations that fuel conflict and tear people apart. The term has been used to describe controversial topics widely discussed in social media. + +=== Anti-reactionary FAQ === +The 2013 post "The Anti-Reactionary FAQ" critiques the work and worldview of the neoreactionary movement, arguing against the work of Curtis Yarvin (whose views include a belief in natural racial hierarchies and a desire to restore feudalism). Alexander's essays on neoreaction have been cited by David Auerbach and Dylan Matthews as explanations of the movement. + +=== Lizardman's Constant === +In the 2013 post "Lizardman's Constant is 4%", Alexander coined the term "Lizardman's Constant", referring to the approximate percentage of responses to a poll, survey, or quiz that are not sincere. The post was responding to a Public Policy Polling statement that "four percent of Americans believe lizardmen are running the Earth", which Alexander attributed to people giving a polling company an answer they did not really believe to be true, out of carelessness, politeness, anger, or amusement. +Alexander suggested that polls should include a question with an absurd answer as one of the options, so anyone choosing that option could be weeded out as a troll. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Slate_Star_Codex-1.md b/data/en.wikipedia.org/wiki/Slate_Star_Codex-1.md new file mode 100644 index 000000000..a6e8cb6b7 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Slate_Star_Codex-1.md @@ -0,0 +1,23 @@ +--- +title: "Slate Star Codex" +chunk: 2/2 +source: "https://en.wikipedia.org/wiki/Slate_Star_Codex" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:27.225137+00:00" +instance: "kb-cron" +--- + +== The New York Times controversy == +Alexander used his first and middle name alone for safety and privacy reasons, although he had previously published Slate Star Codex content academically under his real name. In June 2020, he deleted all entries on Slate Star Codex, stating that a technology reporter from The New York Times (NYT) intended to publish an article about the blog using his full name. Alexander said that the reporter told him that it was newspaper policy to use real names, and he referred to it as doxing. The New York Times responded: "We do not comment on what we may or may not publish in the future. But when we report on newsworthy or influential figures, our goal is always to give readers all the accurate and relevant information we can." The Verge cited a source saying that at the time when Alexander deleted the blog, "not a word" of a story about SSC had been written. The Poynter Institute's David Cohn interpreted this event as part of an ongoing clash between the tech and media industries, reflecting a shift from primarily economic conflicts to fundamental disagreements over values, ethics, and cultural norms. +Prior to the article's publication, several commentators argued that The New York Times should not publish Alexander's name without good reason. Writing in National Review, Tobias Hoonhout said that the newspaper had applied its anonymity policy inconsistently. The New Statesman's Jasper Jackson wrote that it was "difficult to see how Scott Alexander's full name is so integral to the NYT's story that it justifies the damage it might do to him", but cautioned that such criticism was based solely on Alexander's own statements and that "before we make that call, it might be a good idea to have more than his word to go on." As reported by The Daily Beast, the criticism by Alexander and his supporters that the paper was doxing him caused internal debate among The New York Times' staff. +Supporters of the site organized a petition against release of the author's name. The petition collected over six thousand signatures in its first few days, including psychologist Steven Pinker, social psychologist Jonathan Haidt, economist Scott Sumner, computer scientist and blogger Scott Aaronson, and philosopher Peter Singer. +According to New Statesman columnist Louise Perry, Scott Alexander wrote that he quit his job and took measures that made him comfortable with revealing his real name, which he published on Astral Codex Ten. +The New York Times published an article about the blog in February 2021, three weeks after Alexander had publicly revealed his name. + +== References == + +== External links == +slatestarcodex.com, the original, now discontinued blog +Astral Codex Ten, the successor blog. +Scott Alexander's writings on LessWrong \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Sociological_Images-0.md b/data/en.wikipedia.org/wiki/Sociological_Images-0.md new file mode 100644 index 000000000..e95559802 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Sociological_Images-0.md @@ -0,0 +1,17 @@ +--- +title: "Sociological Images" +chunk: 1/4 +source: "https://en.wikipedia.org/wiki/Sociological_Images" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:28.621187+00:00" +instance: "kb-cron" +--- + +Sociological Images is a blog that offers image-based sociological commentary and is one of the most widely read social science blogs. Updated daily, it covers a wide range of social phenomena. The aim of the blog is to encourage readers to develop a "sociological imagination" and to learn to see how social institutions, interactions, and ideas affect the individual. +Started in 2007 by sociology professor Lisa Wade as a place to swap material for sociology classes, the site developed into a blog aimed at the general public as it attracted more readers. However, the site still includes a strong teaching component, including sample assignments and syllabi for sociology instructors. The site receives about 500,000 visitors per month, most from social media sites and other blogs, such as Jezebel, which partially syndicate it. Reviewers have praised the blog's ability to make sociology accessible to the general public. + +== History == +Sociological images was founded in 2007 by sociology professor Lisa Wade (Occidental College) and hosted at Blogspot to share ideas and teaching resources with other faculty teaching about sociology. Six professors were invited to serve as the foundational bloggers. Early posts included little text because it was assumed the audience would be academics and thus understand the context of the material. After a few months, Wade and Gwen Sharp (Nevada State College) by dint of being the main content producers took over the blog. While the writers did not originally envision a non-academic audience, the posts started to be shared amongst a large non-academic community, particularly through Facebook and Twitter in the later years of the blog. Wade and Sharp were very surprised to see their posts circulate beyond academics and, initially, a little unsettled to have non-academics commenting. However, seeing their audience grow, they were excited and reimagined the site as a blog devoted to public sociology. In 2008, the editors of Contexts, a magazine published by the American Sociological Association, asked Wade and Sharp if they would be interested in integrating their blog into the website of the magazine and they agreed. In 2010, the editors of the magazine retired but moved the website's content to The Society Pages along with Sociological Images. As Wade and Sharp put it in their history of the blog, "with the help of the technical staff at Contexts and the University of Minnesota-Twin Cities, Sociological Images became increasingly professional, functional, and multidimensional". Wade and Sharp have reflected that as a result of writing and publishing the blog they have become more media literate. For example, they no longer highlight CafePress tshirts, since anyone can put any slogan on one; instead, they choose to highlight influential images. + +== Format and content == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Sociological_Images-1.md b/data/en.wikipedia.org/wiki/Sociological_Images-1.md new file mode 100644 index 000000000..3991e8fa0 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Sociological_Images-1.md @@ -0,0 +1,15 @@ +--- +title: "Sociological Images" +chunk: 2/4 +source: "https://en.wikipedia.org/wiki/Sociological_Images" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:28.621187+00:00" +instance: "kb-cron" +--- + +Hosted by The Society Pages, which is a hub for social science blogs and websites, Sociological Images is a blog that is updated daily and often between two and four times a day. The posts are written by Gwen Sharp, Lisa Wade and guest contributors. Each post usually features an image, such as a graph, advertisement, commercial, video clip, product, or screenshot, as well as commentary about the image; most of these images are taken from mainstream websites, other social science sites, or reader submissions. Around 50% of the blog posts focus on analyzing these visual elements of culture. The blog covers a wide variety of sociological topics, such as gender inequality, data mapping, homelessness, lesbian politics, and the environment. The most common topics are gender, sexuality, class, nationalism, race, ethnicity, marketing, and body image; in particular, the site focuses on how American popular culture perpetuates gender inequities. Many of the posts are based on items sent in by readers which Wade and Sharp then analyze; they receive an average of 15 to 20 items per day. According to Wade and Sharp, "involvement of the readership in this way has undoubtedly been key to the site's success; not only does it ensure a steady stream of content, but it creates a personal connection to the site and engages readers more actively in applying the sociological perspective as they look for relevant examples to submit". The site also collects popular posts under its "trending" tab, recommends posts under "editor's favorites", and references to posts in the media under "In the News". As of May 2012, the site had over 4,000 posts archived. +The tagline of the blog—"Inspiring sociological imaginations everywhere"—is taken from C. Wright Mills, a famous sociologist. As Wade explains, sociology for her is designed "to explain social patterns outside the individual" by looking at how culture and institutions affect individuals. Sharp points out that for readers of the blog, sociology can explain why they and their friends enjoy the same brands or how advertising perpetuates gender stereotypes. +The blog allows for commenting and from these comments discussions emerge, which one reviewer has called "intelligent, respectful, and constructive". Wade and Sharp themselves have reflected on the different expectations readers have for the commenting space on their blog: "While we understand the arguments for creating safe spaces for the constructive discussion of race, gender, sexual orientation, and other issues, particularly for those groups who may face prejudice or discrimination, ensuring a truly safe space has proven impossible". Noting that the blog receives 500 to 750 comments on average per week, they had to make some decisions about how to handle the traffic. As of May 2012, the site used Disqus to moderate its comments. Users must create a profile to comment and other readers can flag comments that are inappropriate. Any comments that insult or threaten other commenters are deleted, but criticisms of Wade and Sharp's posts remain; they often highlight these rebuttals in updates to the posts or subsequent posts. More importantly, any mistakes Wade and Sharp make in the posts remain; they are fixed with updates or comments, but blog post remain in their original published format. As Wade and Sharp explain, they want to model the learning process for their readers. They feel that it is important to be able to admit mistakes and learn from them in public so that their readers will feel comfortable doing this as well. +In her review of Sociological Images, Karen McCormack identifies four different types of posts throughout the blog: visual plus, text plus, open post, and data display. In the visual plus posts, the images dominate and little text is needed to explain the point of the post. For example, she highlights a post from 14 January 2011, "Glamorizing Brutality toward Women", that juxtaposes a series of images and videos "to expose the acceptability of violence against women" and how "the more mundane images of violence are consistent with the more grotesque and disturbing". These kinds of posts are often filled with historical images "to highlight continuity or change over time", such as the ways in which different racial groups have been dehumanized through animal-like caricature. These historical trends are some of the most highlighted and praised posts by reviewers. For example, one interviewer praised The White Woman's Burden, which demonstrated the consistent colonial impulse in advertising. Text plus posts use visuals to augment the words; the majority of these posts make readers aware of sociological arguments in other fora, such as TED talks or New York Times editorials. They summarize and link to these longer form arguments. Open posts "treat the images and videos as polysemic - open to multiple and contradictory interpretations from the audience". These are "less analytic and more provocative", prompting readers to ask and answer questions. For example, in a post about color photos from the Great Depression, images dominate and the post ends with a question: "are we more able to relate to the people in the photographs because they are in colour? Do we experience less distance between their lives and our own because the medium is both more familiar and closer to what we see?" Data display posts visualize complex data so that readers can understand difficult issues in new ways; they also link readers to sites with interactive mapping tools and other kinds of software that enable them to make their own projects. McCormack points to one particularly good example of this kind of post, a video of Hans Rosling explaining the relationship between wealth and life expectancy throughout the world over the past 200 years. +Some of the posts explain specific scholarly theories for the general reader. For example, in Hand Sapolio Soap Will Make You “Welcome Among the Best People”, Sharp uses vintage soap advertisements to explain Joan Jacobs Brumberg's theories about how culture constructs a connection between girls' hygiene and feelings of personal worth. In general, the site builds on the scholarly work of advertising scholars Jean Kilbourne and Sut Jhally. As Wade and Sharp point out, they try to "pull back the curtain" on marketing and advertising in their blog. For example, they discuss how advertising has co-opted the language of "choice" from feminism and pro-choice campaigns in order to sell cosmetics. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Sociological_Images-2.md b/data/en.wikipedia.org/wiki/Sociological_Images-2.md new file mode 100644 index 000000000..c92699baf --- /dev/null +++ b/data/en.wikipedia.org/wiki/Sociological_Images-2.md @@ -0,0 +1,25 @@ +--- +title: "Sociological Images" +chunk: 3/4 +source: "https://en.wikipedia.org/wiki/Sociological_Images" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:28.621187+00:00" +instance: "kb-cron" +--- + +=== Abercrombie & Fitch bikini top === +On 19 March 2011, Sociological Images published a post which reported that Abercrombie & Fitch was marketing push up bikini tops at young girls, asking "so, at what age should girls start trying to enhance their cleavage?" Consumers demanded change from the company; as a result, Abercrombie had changed their campaign, describing their tops as "padded". Wade and Sharp write in an article mentioning this incident that "the Abercrombie post had an unusually powerful effect, but Sociological Images routinely receives e-mails and comments from public relations departments of companies responsible for advertisements or products that are analyzed on the site". + +=== Princess Tiana and watermelon candy === +On 12 March 2012, Sociological Images published a post arguing that using the Disney character Tiana to advertise watermelon candy perpetrated the racist watermelon stereotype. This criticism was reported on some other blogs. + +== Teaching tool == + +Sociological Images is designed to be used as a teaching tool as well as a blog. It is aimed at both lower- and upper-division undergraduates and is a "useful resource to connect classroom work with popular culture and media imagery" as well as "extremely useful for instructors who wish to keep pace with the abundant ways that popular culture reifies discrimination". Its content applies to courses in sociology, social science methods, media studies, gender studies, and courses focused on race, ethnicity and class. Wade and Sharp include sample assignments that allow instructors to integrate the blog into class work. For example, students can write a post and submit it to the blog. They can also select an advertisement that revolves around "sex, race, gender, family roles, nationality or class" and then find additional advertisements on their own, writing an analysis of the implicit messages in the set. In her review of the blog, Karen McCormack describes how well the posts lend themselves to generating class discussion. She cites the post "The Double Standard in Sexualizing Teen Celebrities" as one way to spark discussion; "while students may disagree about differences in male and female vulnerability and sexuality, a class exploring gender could be enhanced by referring to the images as a way of focusing discussion on the larger issue of how different groups are represented differently and unequally". McCormack also points out that the high-quality comments on the blog "provide a strong model for students learning to read and analyse critically". The site also includes course guides that organize posts from the blog around frequently taught sociology concepts. Wade and Sharp have also created a complementary Pinterest board that organizes the images from Sociological Images into 23 topic areas, such as race, heteronormativity, sexy toy makeovers, and gendered parenting and housework. + +== Reception == + +=== Site statistics and publicity === +Sociological Images receives about 500,000 visitors each month. As of 2011, the site was visited over 7 million times with a total of 11.4 million page views. It has over 20,000 RSS subscribers, 16,000 Facebook readers, 7,000 Twitter subscribers, and 10,000 readers on Pinterest. The site is partially syndicated on two high-profile blogs, namely Jezebel and Ms. Posts from Sociological Images have also been reposted at Racialicious, Adios Barbie, Love Isn't Enough, Scientopia, Owni, and Conhecimento Prudente. As a result of the publicity from the blog, Wade and Sharp are often consulted by media outlets as experts. The "In the News" section lists over 100 appearances, including outlets such as NPR and CNN. Wade and Sharp believe that their post Evolution of Evony Video Game Ads is their most popular post. +Readers of Sociological Images tend to be between 18 and 34 years old, female and college educated, with incomes of less than $60,000. Forty-nine percent of readers are in the United States, 10% from Western Europe, 10% from Canada, 5% from India, and 2% from Australia. Readers are drawn to the site in a variety of ways, some as part of their daily reading habits and some through internet searching, such as through the phrase "Disney princess". Social networking sites also account for a significant amount of the site's traffic. Over 700,000 visits in 2011 came from Facebook and 50,000 from Twitter. Reposts on other sites also bring in a significant amount of traffic. For example, Feministing and Jezebel each accounted for 50,000 visitors in 2011. News aggregators also bring in a substantial number as well; reddit brought in 125,000 in 2011. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Sociological_Images-3.md b/data/en.wikipedia.org/wiki/Sociological_Images-3.md new file mode 100644 index 000000000..d1ea1b98e --- /dev/null +++ b/data/en.wikipedia.org/wiki/Sociological_Images-3.md @@ -0,0 +1,26 @@ +--- +title: "Sociological Images" +chunk: 4/4 +source: "https://en.wikipedia.org/wiki/Sociological_Images" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:28.621187+00:00" +instance: "kb-cron" +--- + +=== Reviews === +Sociological Images was reviewed by Karen McCormack in Visual Studies. She praised the blog's ability to explain sociology to those outside academia, writing that "the most exciting thing about Sociological images is that it can truly bring sociology to everyone", but she did point out some "drawbacks" to the blog form itself, such as the lack of space to discuss the original context for some of the images. It was also reviewed by David T. Mayeda in Teaching Sociology, who praised it as "an insightful, thought-provoking site that can be used by sociology instructors and students". He particularly highlights the ways in which the authors "show how discriminatory imagery evolves over time, preserving dominant narratives in society, but manifesting in different ways depending on the social context". He emphasizes that the audience of the site is not other academics, pointing out that the site "tends not to provide deeper theoretical rhetoric in its entries". In their review of the site, MERLOT (Multimedia Educational Resource for Learning and Online Teaching), wrote that the site "strongly encourages us to develop our sociological imaginations by presenting brief discussions of timely and compelling imagery, spanning the breadth of sociological inquiry". +Male privilege and entitlement posts on the site tend to receive the greatest volume of negative reactions. Readers will sometimes argue that gender equity already exists and that Wade and Sharp are reading "too much into" the images. In particular, posts that deconstruct sexual power dynamics and sexual violence are some that receive the most resistance. People are scared to realize, Wade says, that "their body has internalized" these gender expectations. Moreover, while the site's posts on gender inequity are often "routinely praised" by many readers, they are also linked to by men's rights groups, attracting criticism. But it is posts about fat and health related to weight that bring out the most hurtful speech in the comments. Sharp mentions in an interview that she has to take significantly more time out to monitor the site after she posts on these topics to delete and respond to fat-shaming. + +=== Awards === +2009, Pacific Sociological Association +2012, American Sociological Association Section on Communication and Information Technologies +2012, University of Minnesota Sociology Department + +== References == + +== External links == +Official website +Sociological Images on Pinterest +Lisa Wade +Gwen Sharp \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Spice_(oceanography)-0.md b/data/en.wikipedia.org/wiki/Spice_(oceanography)-0.md new file mode 100644 index 000000000..978dde60b --- /dev/null +++ b/data/en.wikipedia.org/wiki/Spice_(oceanography)-0.md @@ -0,0 +1,407 @@ +--- +title: "Spice (oceanography)" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Spice_(oceanography)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:26.905197+00:00" +instance: "kb-cron" +--- + +Spice, spiciness, or spicity, symbol τ, is a term in oceanography referring to variations in the temperature and salinity of seawater over space or time, whose combined effects leave the water's density unchanged. For a given spice, any change in temperature is offset by a change in salinity to maintain unchanged density. An increase in temperature decreases density, but an increase in salinity increases density. Such density-compensated thermohaline variability is ubiquitous in the upper ocean. Warmer, saltier water is more spicy while cooler, less salty water is more minty. For a density ratio of 1, all the thermohaline variability is spice, and there are no density fluctuations. + + +== Mathematical description == +The density of seawater controls much of the movement of water, or the thermohaline flow, in the ocean. The density of seawater is primarily determined by the temperature and salinity of that water. Changes in these two main parameters, potential temperature Θ and salinity S, are multiplied with their thermal expansion + + + + α + + + {\displaystyle \alpha } + + or haline contraction coefficient + + + + β + + + {\displaystyle \beta } + + equal to each other; + + + + α + d + Θ + + + {\displaystyle \alpha d\Theta } + + and + + + + β + d + S + + + {\displaystyle \beta dS} + + are both proportional to a change in density and are both terms of the linearized equation of state of the ocean (TEOS-10). This similarity is supposed to be relevant for understanding the consequences of sea water mixing. + + + + + α + d + Θ + = + β + d + S + + + {\displaystyle \alpha d\Theta =\beta dS} + + +The density + + + + ρ + + + {\displaystyle \rho } + + doesn't change over an isopycnal. However, by mixing a change in temperature and salinity can occur. Therefore spiciness + + + + τ + + + {\displaystyle \tau } + + is introduced as variable that is proportional to thermal expansion and haline contraction. Integration of this variable along an isopycnal leads to the following equation. + + + + + + ∫ + + ρ + + + d + τ + = + + ∫ + + ρ + + + α + d + Θ + = + + ∫ + + ρ + + + β + d + S + + + {\displaystyle \int _{\rho }d\tau =\int _{\rho }\alpha d\Theta =\int _{\rho }\beta dS} + + +Spiciness could be described as the isothermal gradient of the density that equals the isohaline gradient of the density. + + + + + τ + = + 2 + ∫ + + + + d + ρ + + + d + S + + + + + + | + + + Θ + + + + d + S + = + − + 2 + ∫ + + + + d + ρ + + + d + Θ + + + + + + | + + + S + + + + d + Θ + + + {\displaystyle \tau =2\int {\frac {d\rho }{dS}}|_{\Theta }\quad dS=-2\int {\frac {d\rho }{d\Theta }}|_{S}\,d\Theta } + + +The isopycnal gradient of spiciness should equal to the isopycnal gradient of temperature and salinity by multiplication with the derivative in the other variable of the density. + + + + + d + τ + + + | + + + ρ + + + = + 2 + + ρ + + S + + + d + S + + + | + + + ρ + + + = + − + 2 + + ρ + + Θ + + + d + Θ + + + | + + + ρ + + + + + {\displaystyle d\tau |_{\rho }=2\rho _{S}dS|_{\rho }=-2\rho _{\Theta }d\Theta |_{\rho }} + + +Another mathematical implication for the existence of a spiciness influence manifests itself in a + + + + S + , + Θ + + + {\displaystyle S,\Theta } + +-diagram, where the negative slope of the isopleths equals the ratio between the temperature- and salinity derivative of the spiciness. + + + + + + + + d + S + + + d + Θ + + + + + + | + + + τ + + + = + − + + + + τ + + Θ + + + + τ + + S + + + + + + + {\displaystyle {\frac {dS}{d\Theta }}|_{\tau }=-{\frac {\tau _{\Theta }}{\tau _{S}}}} + + + +== Applications == + +A purpose for introducing spiciness is to decrease the amount of state variables needed; the density at constant depth is a function of potential temperature and salinity and of using both, spiciness can be used. If the goal is to only quantify the variation of water parcels along isopycnals, the variation in absolute salinity or temperature can be used instead because it gives the same information with the same amount of variables. +Another purpose is to examine how the stability ratio + + + + + R + + ρ + + + + + {\displaystyle R_{\rho }} + + varies vertically on a water column. The stability ratio is a number determining the involvement of temperature changes relative to the involvement salinity changes in a vertical profile, which yields relevant information about the stability of the water column: + + + + + + R + + ρ + + + = + ( + − + + ρ + + Θ + + + + Θ + + z + + + ) + + / + + ( + + ρ + + S + + + + S + + z + + + ) + + + {\displaystyle R_{\rho }=(-\rho _{\Theta }\Theta _{z})/(\rho _{S}S_{z})} + + +The vertical variation of this number is often shown in a spiciness-potential density diagram and/or plot, where the angle shows the stability. + + +== Computation == +The spiciness can be calculated in several programming languages with the Gibbs SeaWater (GSW) toolbox. It is used to derive thermodynamic seawater properties and is adopted by the Intergovernmental Oceanographic Commission (IOC), International Association for the Physical Sciences of the Oceans (IAPSO) and the Scientific Committee on Oceanic Research (SCOR). They use the definition of spiciness (gsw_spiciness0(), gsw_spiciness1(), gsw_spiciness2() at respectively 0, 1000 and 2000 dbar) provided by. These isobars are chosen because they correspond to commonly used potential density surfaces. Areas with constant density but different spiciness have a net water flow of heat and salinity due to diffusion. + + +== Disagreements == +The exact definition of spiciness is debated. Specifically, the orthogonality of the density with spiciness and the used scaling factor of potential temperature and salinity. McDougall claims that orthogonality should not be imposed because: + +There is no physical reason to impose orthogonality. +Imposing orthogonality would 'necessarily depends on an arbitrary scaling factor of the salinity and temperature axes'. In other words, spiciness would have different meanings for different (chosen) scaling factors. +The meaning of spiciness changes with density. As a result, spiciness may only be useful over small vertical extensions in the surface layer. +McDougall is adopted by the Intergovernmental Oceanographic Commission (IOC), International Association for the Physical Sciences of the Oceans (IAPSO) and the Scientific Committee on Oceanic Research (SCOR) due to their implementation of spiciness in the TEOS-10. +Huang claims that the orthogonal system is superior to the non orthogonal system because the coordinates can be regarded as independent and distances between points can be calculated more easily. +McDougall recommended that the spiciness should not be used. Instead, they recommend that the variation of salinity should be used to differentiate between isopycnal water parcels and the stability ratio + + + + + R + + ρ + + + + + {\displaystyle R_{\rho }} + + on vertical water columns for stability. + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Sponge_ground-0.md b/data/en.wikipedia.org/wiki/Sponge_ground-0.md new file mode 100644 index 000000000..17e095d9e --- /dev/null +++ b/data/en.wikipedia.org/wiki/Sponge_ground-0.md @@ -0,0 +1,19 @@ +--- +title: "Sponge ground" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Sponge_ground" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:28.233816+00:00" +instance: "kb-cron" +--- + +Sponge grounds, also known as sponge aggregations, are intertidal to deep-sea habitats formed by large accumulations of sponges (glass sponges and/or demosponges), often dominated by a few massive species. Sponge grounds were already reported more than 150 years ago, but the habitat was first fully recognized, studied and described in detail around the Faroe Islands during the inter-Nordic BIOFAR 1 programme 1987–90. These were called Ostur (meaning "cheese" and referring to the appearance of the sponges) by the local fishermen and this name has to some extent entered the scientific literature. Sponge grounds were later found elsewhere in the Northeast Atlantic and in the Northwest Atlantic, as well as near Antarctica. They are now known from many other places worldwide and recognized as key marine habitats. +Sponge grounds are important habitats supporting diverse ecosystems. During a study of outer shelf and upper slope sponge grounds at the Faroe Islands, 242 invertebrate species were found in the vicinity and 115 were associated with the sponges. In general, fish fauna associated with sponge grounds are poorly known, but include rockfish and gadiforms. Sponge grounds are threatened, especially by bottom trawling and other fishing gear, dredging, oil and gas exploration and undersea cables, but potentially also by deep sea mining, carbon dioxide sequestration, pollution and climate change. + + +== Prehistoric sponge grounds == +By studying spicules in sediments cores taken from sponge grounds on the slopes of the Flemish Cap and Grand Bank (off Newfoundland, Canada), scientists managed to detect the presence of sponges in the past. The oldest record for Geodiidae sponges in this region was found in a long core collected in the slope of the Grand Bank, where typical sterraster spicules were found in the top of a submarine landslide deposit older than 25 000 BP. Continuous presence of sponges was recorded on the southeastern region of the Flemish Cap as far as 130 000 BP. It seems the distribution range of the Geodiidae in this area significantly expended after the deglaciation. + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Submarine_volcano-0.md b/data/en.wikipedia.org/wiki/Submarine_volcano-0.md new file mode 100644 index 000000000..778306465 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Submarine_volcano-0.md @@ -0,0 +1,56 @@ +--- +title: "Submarine volcano" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Submarine_volcano" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:29.475807+00:00" +instance: "kb-cron" +--- + +Submarine volcanoes are underwater vents or fissures in the Earth's surface from which magma can erupt. Many submarine volcanoes are located near areas of tectonic plate formation, known as mid-ocean ridges. The volcanoes at mid-ocean ridges alone are estimated to account for 75% of the magma output on Earth. Although most submarine volcanoes are located in the depths of seas and oceans, some also exist in shallow water, and these can discharge material into the atmosphere during an eruption. The total number of submarine volcanoes is estimated to be over one million (most are now extinct) of which some 75,000 rise more than 1 kilometre (0.62 miles) above the seabed. Only 119 submarine volcanoes in Earth's oceans and seas are known to have erupted during the last 11,700 years. +Hydrothermal vents, sites of abundant biological activity, are commonly found near submarine volcanoes. + + +== Seamounts == +Many submarine volcanoes are seamounts, typically extinct volcanoes that rise abruptly from a seafloor of 1,000 metres (3,300 ft) - 4,000 metres (13,000 ft) depth. They are defined by oceanographers as independent features that rise to at least 1,000 metres (3,300 ft) above the seafloor. The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea. An estimated 30,000 seamounts occur across the globe, with only a few having been studied. +However, some seamounts are also unusual. For example, while the summits of seamounts are normally hundreds of meters below sea level, the Bowie Seamount in Canada's Pacific waters rises from a depth of about 3,000 metres (9,800 ft) to within 24 metres (79 ft) of the sea surface. + + +== Effect of water on volcanoes == +The presence of water can greatly alter the characteristics of a volcanic eruption and the explosions of underwater volcanoes in comparison to those on land. +For instance, water causes magma to cool and solidify much more quickly than in a terrestrial eruption, often turning it into volcanic glass. The shapes and textures of lava formed by submarine volcanoes are different from lava erupted on land. Upon contact with water, a solid crust forms around the lava. Advancing lava flows into this crust, forming what is known as pillow lava. +Below ocean depths of about 2,200 metres (7,200 ft) where the pressure exceeds the critical pressure of water (22.06 MPa or about 218 atmospheres for pure water), it can no longer boil; it becomes a supercritical fluid. Without boiling sounds, deep-sea volcanoes can be difficult to detect at great distances using hydrophones. +The critical temperature and pressure increase in solutions of salts, which are normally present in the seawater. The composition of aqueous solution in the vicinity of hot basalt, and circulating within the conduits of hot rocks, is expected to differ from that of bulk water (i.e., of sea water away from the hot surfaces). One estimation is that the critical point is 407 °C (765 °F) and 29.9 MPa, while the solution composition corresponds to that of approximately 3.2% of NaCl. + + +== Identifying types of eruptions by sounds == + +There are two types of sound generated by submarine eruptions: One created by the slow release and bursting of large lava bubbles, while quick explosions of gas bubbles create the other one. Using this method to be able to distinguish the two can help measure the related effects on marine animals and ecosystems, the volume and composition of the lava flow can also be estimated and built into a model to extrapolate potential effects. +Scientists have connected sounds to sights in both types of eruptions. In 2009, a video camera and a hydrophone were floating 1,200 metres (3,900 ft) below sea level in the Pacific Ocean near Samoa, watching and listening as the West Mata Volcano erupted in several ways. Putting video and audio together let researchers learn the sounds made by slow lava bursting and the different noises made by hundreds of gas bubbles. + + +== Research == +Scientists still have much to learn about the location and activity of underwater volcanoes. In the first two decades of this century, NOAA's Office of Ocean Exploration has funded exploration of submarine volcanoes, with the Ring of Fire missions to the Mariana Arc in the Pacific Ocean being particularly noteworthy. Using Remote Operated Vehicles (ROV), scientists studied underwater eruptions, ponds of molten sulfur, black smoker chimneys and even marine life adapted to this deep, hot environment. +Research from the ROV KAIKO off the coast of Hawaii has suggested that pahoehoe lava flows occur underwater, and the degree of the submarine terrain slope and rate of lava supply determine the shape of the resulting lobes. +In August 2019, news media reported a large pumice raft floating in the South Pacific between Fiji and Tonga. Subsequent scientific investigations revealed the pumice raft originated from the eruption of a nearby submarine volcano, which was directly observed as a volcanic plume in satellite images. This discovery will help scientists better predict for the precursors of a submarine eruption, such as low-frequency earthquakes or hydrophone data, using machine learning. + + +== Santorini: magma pressure == +Santorini, Greece, is located in the southern Aegean Sea. It is located around 128 nautical miles southeast of the Greek mainland and about 63 nautical miles north of Crete. Crete is the largest of the Greek islands. Santorini is located along the active South Aegean Volcanic Arc. This arc was formed by the subduction of the African Plate beneath the Aegean microplate. This leads to the creation of seismicity and volcanic unrest in the region. One of these cases happened in late January in Santorini. The island of Santorini and neighboring islands experienced a sequence of over 28,000 earthquakes. Several over a magnitude of 5.0. These crisis lasted the duration of a month. Scientists later found that 300 million cubic meters of magma intruded 4km below the seabed. This means that no submarine volcanoes erupted; rather, scientists found that pressure can accumulate between islands and these underwater magmatic systems. This opens a whole new set of questions. Eruptions aren't the only thing to worry about; this buildup of pressure has caused over 20,000 earthquakes and forced locals to flee. These events show that while these underwater volcanoes might not be super dangerous now, they serve as a long-term warning of potential future activity. + + +== See also == +List of submarine volcanoes + + +== References == + + +== External links == + +Volcano Information from the Deep Ocean Exploration Institute, Woods Hole Oceanographic Institution +Volcano World - now maintained by the Department of Geosciences at Oregon State University +Britannica - Submarine Volcanoes +United States Geological Survey +Ring of Fire Exploration Mission \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Supralittoral_zone-0.md b/data/en.wikipedia.org/wiki/Supralittoral_zone-0.md new file mode 100644 index 000000000..51b86d2b3 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Supralittoral_zone-0.md @@ -0,0 +1,25 @@ +--- +title: "Supralittoral zone" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Supralittoral_zone" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:30.721754+00:00" +instance: "kb-cron" +--- + +The supralittoral zone, also known as the splash zone, spray zone or the supratidal zone, sometimes also referred to as the white zone, is the area above the spring high tide line, on coastlines and estuaries, that is regularly splashed, but not submerged by ocean water. Seawater penetrates these elevated areas only during storms with high tides. +Organisms here must cope also with exposure to air, fresh water from rain, cold, heat and predation by land animals and seabirds. At the top of this area, patches of dark lichens can appear as crusts on rocks. Some types of periwinkles, Neritidae and detritus feeding Isopoda commonly inhabit the lower supralittoral. + + +== See also == +Littoral zone +Sublittoral zone + + +== Notes == + + +== References == +Thurman H.V. and Trujillo A.P. 1993.Essentials of Oceanography.Upper Saddle River, NJ:Prentice Hall +Yip, Maricela and Madl, Pierre (1999) Littoral University of Salzburg. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Surf_zone-0.md b/data/en.wikipedia.org/wiki/Surf_zone-0.md new file mode 100644 index 000000000..d5fb5d394 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Surf_zone-0.md @@ -0,0 +1,42 @@ +--- +title: "Surf zone" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Surf_zone" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:32.060457+00:00" +instance: "kb-cron" +--- + +The surf zone or breaker zone is the nearshore part of a body of open water between the line at which the waves break and the shore. As ocean surface waves approach a shore, they interact with the bottom, get taller and steeper, and break, forming the foamy surface called surf. The region of breaking waves defines the surf zone. After breaking in the surf zone, the waves (now reduced in height) continue to move in, and they run up onto the sloping front of the beach, forming an uprush of water called swash. The water then runs back again as backwash. The water in the surf zone is relatively shallow, depending on the height and period of the waves. + + +== Animal life == +The animals that often are found living in the surf zone are crabs, clams, and snails. Surf clams and mole crabs are two species that stand out as inhabitants of the surf zone. Both of these animals are very fast burrowers. The surf clam, also known as the variable coquina, is a filter feeder that uses its gills to filter microalgae, tiny zooplankton, and small particulates out of seawater. The mole crab is a suspension feeder that eats by capturing zooplankton with its antennae. All of these creatures burrow down into the sand to escape from being pulled into the ocean from the tides and waves. They also burrow themselves in the sand to protect themselves from predators. The surf zone is full of nutrients, oxygen, and sunlight which leaves the zone very productive with animal life. + + +== Rip currents == + +The surf zone can contain dangerous rip currents: strong local currents which flow offshore and pose a threat to swimmers. Rip-current outlooks use the following set of qualifications: + +Low-risk rip currents +Wind and/or wave conditions are not expected to support the development of rip currents; however, rip currents can sometimes occur, especially in the vicinity of jetties and piers. Know how to swim and heed the advice of lifeguards. +Moderate-risk rip currents +Wind or wave conditions support stronger or more frequent rip currents. Only experienced surf swimmers should enter the water. +High-risk rip currents +Wind or wave conditions support dangerous rip currents. Rip currents are life-threatening to anyone entering the surf. + + +== See also == +Intertidal zone +Littoral zone +Surf fishing + + +== References == +Pinet, Paul R (2008) Invitation to Oceanography, Chapter 11: The Dynamic Shoreline. Edition 5 revised. Jones & Bartlett Learning, ISBN 0-7637-5993-7 +"Breaker Zone." The Free Dictionary. Farlex Inc, 2012. Web. 18 Apr. 2012. . + + +== External links == +MetEd (2012) Rip currents: Nearshore fundamentals University Corporation for Atmospheric Research. Retrieved 17 April 2012. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Swell_(wave)-0.md b/data/en.wikipedia.org/wiki/Swell_(wave)-0.md new file mode 100644 index 000000000..d537a5fda --- /dev/null +++ b/data/en.wikipedia.org/wiki/Swell_(wave)-0.md @@ -0,0 +1,43 @@ +--- +title: "Swell (wave)" +chunk: 1/3 +source: "https://en.wikipedia.org/wiki/Swell_(wave)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:33.463137+00:00" +instance: "kb-cron" +--- + +A swell, also sometimes referred to as ground swell, in the context of an ocean, sea or lake, is a series of mechanical waves that propagate along the interface between water and air under the predominating influence of gravity, and thus are often referred to as surface gravity waves. These surface gravity waves have their origin as wind waves, but are the consequence of dispersion of wind waves from distant weather systems, where wind blows for a duration of time over a fetch of water, and these waves move out from the source area at speeds that are a function of wave period and length. More generally, a swell consists of wind-generated waves that are not greatly affected by the local wind at that time. Swell waves often have a relatively long wavelength, as short wavelength waves carry less energy and dissipate faster, but this varies due to the size, strength, and duration of the weather system responsible for the swell and the size of the water body, and varies from event to event, and from the same event, over time. Occasionally, swells that are longer than 700 m occur as a result of the most severe storms. +Swell direction is the direction from which the swell is moving. It is given as a geographical direction, either in degrees, or in points of the compass, such as NNW or SW swell, and like winds, the direction given is generally the direction the swell is coming from. Swells have a narrower range of frequencies and directions than locally generated wind waves, because they have dispersed from their generation area and over time tend to sort by speed of propagation with the faster waves passing a distant point first. Swells take on a more defined shape and direction and are less random than locally generated wind waves. + +== Formation == + +Large breakers observed on a shore may result from distant weather systems over the ocean. Five factors work together to determine the size of wind waves which will become ocean swell: + +Wind speed – the wind must be moving faster than the wave crest (in the direction in which the wave crest travels) for net energy transfer from air to water; stronger prolonged winds create larger waves +The uninterrupted distance of open water over which the wind blows without significant change in direction (called the fetch) +Width of water surface in the fetch +Wind duration – the time over which the wind has blown over the fetch +Water depth +A wave is described using the following dimensions: + +Wave height (from trough to crest) +Wave length (from crest to crest) +Wave period (time interval between arrival of consecutive crests at a stationary point) +Wave propagation direction +Wave length is a function of period, and of water depth for depths less than approximately half the wave length, where the wave motion is affected by friction with the bottom. + +A fully developed sea has the maximum wave size theoretically possible for a wind of a specific strength and fetch. Further exposure to that specific wind would result in a loss of energy equal to the energy input giving a steady state, due to the energy dissipation from viscosity and breaking of wave tops as "whitecaps". +Waves in a given area typically have a range of heights. For weather reporting and for scientific analysis of wind wave statistics, their characteristic height over a time interval is usually expressed as significant wave height. This figure represents an average height of the highest one-third of the waves in a given time period (usually chosen somewhere in the range from 20 minutes to twelve hours), or in a specific wave or storm system. The significant wave height is also the value a "trained observer" (e.g. from a ship's crew) would estimate from visual observation of a sea state. Given the variability of wave height, the largest individual waves are likely to be somewhat less than twice the significant wave height. + +=== Sources of wind-wave generation === + +Wind waves are generated by wind. Other kinds of disturbances such as seismic events, can also cause gravity waves, but they are not wind waves, and do not generally result in swell. The generation of wind waves is initiated by the disturbances of the crosswind field on the surface of the water. +For initial conditions of a flat water surface (Beaufort Scale 0) and abrupt crosswind flows on the surface of the water, the generation of surface wind waves can be explained by two mechanisms, which are initiated by normal pressure fluctuations of turbulent winds and parallel wind shear flows. + +=== Surface wave generation by winds === + +From "wind fluctuations": Wind wave formation is started by a random distribution of normal pressure acting on the water from the wind. By this mechanism, proposed by O.M. Phillips in 1957, the water surface is initially at rest, and the generation of the wave is +initiated by turbulent wind flows and then by fluctuations of the wind, normal pressure acting on the water surface. Due to this pressure fluctuation arise normal and tangential stresses that generate wave behavior on the water surface. +The assumptions of this mechanism are as follows: \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Swell_(wave)-1.md b/data/en.wikipedia.org/wiki/Swell_(wave)-1.md new file mode 100644 index 000000000..09b3ce94b --- /dev/null +++ b/data/en.wikipedia.org/wiki/Swell_(wave)-1.md @@ -0,0 +1,221 @@ +--- +title: "Swell (wave)" +chunk: 2/3 +source: "https://en.wikipedia.org/wiki/Swell_(wave)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:33.463137+00:00" +instance: "kb-cron" +--- + +The water is originally at rest; +The water is inviscid; +The water is irrotational; +The normal pressure to the water surface from the turbulent wind is randomly distributed; and +Correlations between air and water motions are neglected. +From "wind shear forces": In 1957, John W. Miles suggested a surface wave generation mechanism that is initiated by turbulent wind shear flows, + + + + U + a + ( + y + ) + + + {\displaystyle Ua(y)} + +, based on the inviscid Orr-Sommerfeld equation. He found that the energy transfer from wind to water surface as a wave speed, + + + + c + + + {\displaystyle c} + +, is proportional to the curvature of the velocity profile of wind, + + + + U + + a + ″ + + ( + y + ) + + + {\displaystyle Ua''(y)} + +, at the point where the mean wind speed is equal to the wave speed ( + + + + U + a + = + c + + + {\displaystyle Ua=c} + +, where + + + + U + a + + + {\displaystyle Ua} + + is the mean turbulent wind speed). Since the wind profile, + + + + U + a + ( + y + ) + + + {\displaystyle Ua(y)} + +, is logarithmic to the water surface, the curvature, + + + + U + + a + ″ + + ( + y + ) + + + {\displaystyle Ua''(y)} + +, has a negative sign at point + + + + U + a + = + c + + + {\displaystyle Ua=c} + +. This relation shows the wind flow transferring its kinetic energy to the water surface at their interface, and thence arises wave speed, + + + + c + + + {\displaystyle c} + +. The growth-rate can be determined by the curvature of the winds ( + + + + ( + + d + + 2 + + + U + a + ) + + / + + ( + d + + z + + 2 + + + ) + + + {\displaystyle (d^{2}Ua)/(dz^{2})} + +) at the steering height ( + + + + U + a + ( + z + = + + z + + h + + + ) + = + c + + + {\displaystyle Ua(z=z_{h})=c} + +) for a given wind speed, + + + + U + a + + + {\displaystyle Ua} + +. +The assumptions of this mechanism are: + +2-dimensional, parallel shear flow, + + + + U + a + ( + y + ) + + + {\displaystyle Ua(y)} + +. +Incompressible, inviscid water/wind. +Irrotational water. +Small slope of the displacement of the surface. +Generally, these wave formation mechanisms occur together on the ocean surface, giving rise to wind waves that eventually grow into fully developed waves. If one supposes a very flat sea surface (Beaufort number, 0), and sudden wind flow blows steadily across it, the physical wave generation process would be like this: + +Turbulent wind flows form random pressure fluctuations at the sea surface. Small waves with a few centimeters order of wavelengths are generated by the pressure fluctuations (Phillips mechanism). +The cross wind keeps acting on the initially fluctuated sea surface. Then the waves become larger, and as they do so, the pressure differences increase, and the resulting shear instability expedites wave growth exponentially (Miles mechanism). +The interaction among the waves on the surface generates longer waves (Hasselmann et al., 1973) and this interaction transfers energy from the shorter waves generated by the Miles mechanism to those that have slightly lower frequencies than at the peak wave magnitudes. Ultimately, the wave speed becomes higher than that of the cross wind (Pierson & Moskowitz). + +(Note: Most of the wave speeds calculated from the wavelength divided by the period are proportional to the square root of the length. Thus, except for the shortest wavelength, the waves follow the deep water theory described in the next section. The 8.5 m long wave must be either in shallow water or between deep and shallow.) + +== Development == +Long swell waves develop from and take energy from the shorter wind waves. The process was first described by Klaus Hasselmann (2021 Nobel prize winner) after investigating the non-linear effects that are most pronounced near the peaks of the highest waves. He showed that, through these non-linearities, two wave trains in deep water can interact to generate two new sets of waves, one generally of longer and the other of shorter wavelength. +The equation that Hasselmann developed to describe this process is now used in the sea state models (for example Wavewatch III) used by all the major weather and climate forecasting centres. This is because both the wind sea and the swell have significant effects on the transfer of heat from the ocean to atmosphere. This affects both large scale climate systems, like the El Niño, and smaller scale systems, such as the atmospheric depressions that develop near the edges of the Gulf Stream. +A good physical description of the Hasselmann process is hard to explain, but the non-linear effects are largest near the peaks of the highest waves and the short waves, which often break near the same position, can be used as an analogy. +This is because each small breaking wave gives a small push to the longer wave on which it is breaking. From the point of view of the long wave, it is receiving a small push on each of its crests just like a swing being given a small push at just the right time. There is also no comparable effect in the wave's trough - a term which would tend to reduce the size of the long wave. +From the point of view of a physicist this effect is of extra interest because it shows how, what starts as a random wave field, can generate the order of a long train of swell waves at the cost of the energy losses and increased disorder affecting all the small breaking waves. The sorting of sand grain sizes, often seen on a beach, is a similar process (as is a lot of life). \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Swell_(wave)-2.md b/data/en.wikipedia.org/wiki/Swell_(wave)-2.md new file mode 100644 index 000000000..dacf42e91 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Swell_(wave)-2.md @@ -0,0 +1,63 @@ +--- +title: "Swell (wave)" +chunk: 3/3 +source: "https://en.wikipedia.org/wiki/Swell_(wave)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:33.463137+00:00" +instance: "kb-cron" +--- + +== Dissipation == +The dissipation of swell energy is much stronger for short waves, which is why swells from distant storms are only long waves. The dissipation of waves with periods larger than 13 seconds is very weak but still significant at the scale of the Pacific Ocean. These long swells lose half of their energy over a distance that varies from over 20,000 km (half the distance round the globe) to just over 2,000 km. +This variation was found to be a systematic function of the swell steepness: the ratio of the swell height to the wavelength. The reason for this behavior is still unclear, but it is possible that this dissipation is due to the friction at the air-sea interface. + +== Swell dispersion and wave groups == + +Swells are often created by storms thousands of nautical miles away from the shores where they break, and the propagation of the longest swells is primarily limited by shorelines. For example, swells generated in the Indian Ocean have been recorded in California after more than half a round-the-world trip. This distance allows the waves comprising the swells to be better sorted and free of chop as they travel toward the coast. Waves generated by storm winds have the same speed and will group together and travel with each other, while others moving at even a fraction of a meter per second slower will lag behind, ultimately arriving many hours later due to the distance covered. The time of propagation from the source t is proportional to the distance X divided by the wave period T. In deep water it is + + + + t + = + 4 + π + X + + / + + ( + g + T + ) + + + {\displaystyle t=4\pi X/(gT)} + + where g is the acceleration of gravity. For a storm located 10,000 km away, swells with a period T=15 s will arrive 10 days after the storm, followed by 14 s swells another 17 hours later, and so forth. +The dispersed arrival of swells, starting with the longest period, with a reduction in the peak wave period over time, can be used to calculate the distance at which swells were generated. +Whereas the sea state in the storm has a frequency spectrum with more or less the same shape (i.e. a well defined peak with dominant frequencies within plus or minus 7% of the peak), the swell spectra are more and more narrow, sometimes as 2% or less, as waves disperse further and further away. The result is that wave groups (called sets by surfers) can have a large number of waves. From about seven waves per group in the storm, this rises to 20 and more in swells from very distant storms. + +== Coastal impacts == +Just like for all water waves, the energy flux is proportional to the significant wave height squared times the group velocity. In deep water, this group velocity is proportional to the wave period. Hence swells with longer periods can transfer more energy than shorter wind waves. Also, the amplitude of infragravity waves increases dramatically with the wave period (approximately the square of the period), which results in +higher run-up. +As swell waves typically have long wavelengths (and thus a deeper wave base), they begin the refraction process (see water waves) at greater distances offshore (in deeper water) than locally generated waves. +Since swell-generated waves are mixed with normal sea waves, they can be difficult to detect with the naked eye (particularly away from the shore) if they are not significantly larger than the normal waves. From a signal analysis point of view, swells can be thought of as a fairly regular (though not continual) wave signal existing in the midst of strong noise (i.e., normal waves and chop). + +== Navigation == + +Swells were used by Micronesian navigators to maintain course when no other clues were available, such as on foggy nights. + +== See also == +Surfing + +== References == + +== External links == +"Global swell/surf forecasts". Surfline. +"Australian swell forecasts)". Coastalwatch. +"UK swell forecasting". Magicseaweed. +"Australian swell forecasts". Seabreeze. +"Australian swell forecasts". Swellnet. +"Wave Basics (How swells are formed and measured)". Stormsurf. +"Australian Swell Measuring Devices". Waverider Buoys. Archived from the original on 2006-12-10. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/The_Beginning_or_the_End-0.md b/data/en.wikipedia.org/wiki/The_Beginning_or_the_End-0.md new file mode 100644 index 000000000..45ef1c578 --- /dev/null +++ b/data/en.wikipedia.org/wiki/The_Beginning_or_the_End-0.md @@ -0,0 +1,25 @@ +--- +title: "The Beginning or the End" +chunk: 1/4 +source: "https://en.wikipedia.org/wiki/The_Beginning_or_the_End" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:00.346150+00:00" +instance: "kb-cron" +--- + +The Beginning or the End is a 1947 American docudrama film about the development of the atomic bomb in World War II, directed by Norman Taurog, starring Brian Donlevy, Robert Walker, and Tom Drake, and released by Metro-Goldwyn-Mayer. The film dramatizes the creation of the atomic bomb in the Manhattan Project and the bombing of Hiroshima. +The film originated in October 1945 as a project of actress Donna Reed and her high school science teacher, Edward R. Tompkins, who was a chemist at the Oak Ridge National Laboratory. Bob Considine wrote the treatment, which was sent to MGM scriptwriters. The title was supplied by President Harry S. Truman. At the time there was a legal requirement that permission be obtained to depict living well-known public figures. Many refused, but others, such as J. Robert Oppenheimer, co-operated. Major General Leslie R. Groves, Jr., the director of the Manhattan Project, was hired as a consultant for $10,000 (equivalent to $165,000 in 2025). +Although the filmmakers put considerable effort into historical accuracy, particularly in details, the film is known for some key distortions of history. An entirely fictional sequence was added in which Truman agonizes over whether to authorize the attack; anti-aircraft shells are shown bursting around the Enola Gay on its bombing run over Hiroshima. The film received generally mixed reviews, and was a box office disappointment. + +== Plot == +A prelude scene in the form of a Newsreel story suggests that the film is part of a package of information about the development of atomic energy and the atomic bomb being placed in a time capsule in California, to be opened in 2446. +Physicist and atomic scientist Dr. J. Robert Oppenheimer praises the discovery of atomic energy but also warns of its dangers. American scientists such as Matt Cochran, working under the guidance of Dr. Enrico Fermi and Dr. Marré, have split the atom, and essentially beaten the Germans in the race to devise an atomic bomb. With the assistance of Albert Einstein, they inform President Franklin D. Roosevelt that a monumental discovery has been made. +In 1941, with the United States at war, Roosevelt authorizes up to two billion dollars for the Manhattan Project to develop an atomic bomb. In December 1942, at the University of Chicago, under the watchful eyes of observers such as Lieutenant Colonel Jeff Nixon and international experts, scientists create the first chain reaction, under a stadium at the campus. +Nixon is assigned to General Leslie Groves , who is placed in charge of the project. Groves has to bring together the scientific, industrial and defense communities to build a working atomic bomb during the war. In 1945, following the death of Roosevelt, the new president, Harry S. Truman, continues to support the atomic project, then moved to Los Alamos, New Mexico. +Facing stiff resistance in the Pacific War, Truman orders the use of the atomic bomb against Japan in July 1945. +Cochran and Nixon are assigned to accompany the crew transporting the bomb to Tinian. While assembling the bomb, Cochran comes into contact with radioactive material and dies. The following day, on August 6, 1945, the Enola Gay, a Boeing B-29 Superfortress, drops an atomic bomb on Hiroshima. After the mission, Nixon returns home to break the news of Cochran's death to his wife. + +== Cast == + +== Production == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/The_Beginning_or_the_End-1.md b/data/en.wikipedia.org/wiki/The_Beginning_or_the_End-1.md new file mode 100644 index 000000000..520bd2dcc --- /dev/null +++ b/data/en.wikipedia.org/wiki/The_Beginning_or_the_End-1.md @@ -0,0 +1,17 @@ +--- +title: "The Beginning or the End" +chunk: 2/4 +source: "https://en.wikipedia.org/wiki/The_Beginning_or_the_End" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:00.346150+00:00" +instance: "kb-cron" +--- + +The idea for The Beginning or the End originated in October 1945 with actress Donna Reed, and her high school science teacher, Edward R. Tompkins, a chemist at the Oak Ridge National Laboratory. According to The Hollywood Reporter issues of December 1945 and January 1946, MGM, Paramount and 20th Century-Fox were all interested in making a film about the Manhattan Project. Paramount's Hal B. Wallis was already working on his own version, titled Top Secret, but agreed to merge his project with MGM's and hand over his story and research, offering to serve as an adviser on the MGM treatment in return for a fixed fee and a percentage of the box office gross. +The Beginning or the End had a number of working titles, including Atom Bomb, The Manhattan Project and Top Secret. Writer Bob Considine was hired to produce a treatment, which was submitted to MGM writers. The script underwent a number of revisions, with contributions +from Robert Smith, Frank "Spig" Wead, Norman Krasna, David Hawkins, John Lee Mahin, Glenn Tryon, and Ayn Rand, who provided the montage of Hitler's conquests, a sequence in which a dying informant sends a message to Albert Einstein, and the scene in which President Franklin Roosevelt authorizes the Manhattan Project. Producer Samuel Marx wrote the opening narration. +Marx and Donna Reed's husband Tony Owen met with President Harry S. Truman to secure his approval. At their meeting, Truman is reported to have said: "Gentlemen, make a motion picture. Tell the people of this nation that for them it is the beginning or the end," his last four words supplying the movie with its title. +H. T. Wensel from the National Bureau of Standards, Tompkins, and W. Bradford Shank from the Los Alamos National Laboratory, acted as technical advisers. Relations between MGM and the scientists soon soured, as the scientists began asking for more accuracy, which required multiple script changes, and Tompkins eventually resigned. Oppenheimer sent David Hawkins, a philosophy professor from the University of California to act as a mediator between Marx and the scientists. Although the original intention was that a substantial sum of money would be donated to scientists' associations like the Federation of Atomic Scientists, in the end, no money was paid out. Tompkins received payment of one hundred dollars (equivalent to $2,000 in 2025). At the time, there was a legal requirement that permission be obtained to depict living well-known public figures in films. Lise Meitner, Niels Bohr and Sir James Chadwick all refused to allow their names to be used in the film, which Marx regarded as unfortunate, as it deprived the film's Manhattan Project scenes of some of their international character. +The loss of Bohr caused important sequences to be deleted. The script originally had Bohr, rescued from the Germans in Denmark, bring a shocked Oppenheimer news that the German nuclear weapon project was supplying expertise to its Japanese counterpart. A German submarine was to be portrayed carrying a fictional scientist to Japan to join the Japanese project in Hiroshima. Vannevar Bush objected to the way the script depicted him as having doubts about whether a bomb that could fit into an aircraft could be built in time. Bush insisted that he had been confident of both, and the script was softened to reflect this. +Oppenheimer raised no objection to the sequence in the film in which he informed Brigadier General Thomas Farrell that the odds of a runaway explosion destroying the planet were less than one in a million, although he told MGM that he never said this. The cultured Oppenheimer's main concern was that the script was poor, with characters that were "stilted, lifeless, and without purpose or insight." \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/The_Beginning_or_the_End-2.md b/data/en.wikipedia.org/wiki/The_Beginning_or_the_End-2.md new file mode 100644 index 000000000..84d117a47 --- /dev/null +++ b/data/en.wikipedia.org/wiki/The_Beginning_or_the_End-2.md @@ -0,0 +1,27 @@ +--- +title: "The Beginning or the End" +chunk: 3/4 +source: "https://en.wikipedia.org/wiki/The_Beginning_or_the_End" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:00.346150+00:00" +instance: "kb-cron" +--- + +Military technical advisers for The Beginning or the End included Colonel William A. Considine, Groves's assistant in charge of Security and Public Relations, Major Glen W. Landreth, Major Paul Van Sloun and Lieutenant Colonel Charles W. Sweeney, the pilot of Bockscar, the bomber that dropped the atomic bomb on Nagasaki. Scientists were alarmed by reports that MGM leading man Clark Gable was being considered for the role of Groves, but were relieved when Brian Donlevy was cast instead. Donlevy usually appeared in villainous supporting roles and indeed, many of the actors cast in the movie appeari films noir: Hume Cronyn for The Postman Always Rings Twice; Joseph Calleia, for Gilda and Deadline at Dawn; and Ludwig Stössel for Fritz Lang's Cloak and Dagger. The portly Groves apparently had no objection to his portrayal by the slim and handsome Donlevy, except for the way in which he was shown bossing industrialists around. He had a scene in which he warned Roosevelt that the invasion of Japan would be opposed by Japanese atomic weapons deleted. +Eleanor Roosevelt objected to the casting of Lionel Barrymore as her late husband, due to political remarks that Barrymore had made about the president in 1944. Marx delayed Barrymore's scenes while she had a chance to read and respond to a letter Barrymore sent her explaining that his remarks had been misinterpreted, but she was not placated, and Barrymore was replaced in the role by Godfrey Tearle. The War Department and the White House reviewed the script, and both asked for changes. The Army had objected to a scene in which an Army major made a pass at a girl and it was cut from the film, as the Army felt that this was poor conduct for an officer. +The casual way that Truman and Groves were shown to decide to use the bomb, with Truman stating that "I think more of our American boys than I do of all our enemies", while accurate, troubled columnist and social commentator Walter Lippmann, who felt that it could lead to foreigners being fearful of atomic weapons being in American hands. It was replaced with a scene where Truman (shown from back only) agonizes over whether to authorize the attack or not. In it, Truman asserts to his press secretary that dropping the bomb will shorten the war, and a "year less of war will mean life for ... from 300,000 to half a million of America's finest youth". +The motion picture censors asked for further cuts. Derogatory references to Mexicans were removed, as was an off-color joke about the effects of exposure to radioactive substances ("Is it true if you fool around with that stuff you don't like girls anymore?" "Not that I've noticed"), and one about politics ("I got it confidential−we're makin' the front ends of horses. We ship 'em to Washington to hook on to the other end.") +Principal photography for The Beginning or the End began on April 29, 1946, and continued until July 25 with retakes beginning on August 9, 1946. The production premiered in Washington, D.C., on February 19, 1947, with the national release of the film following on March 7, 1947. + +== Historical accuracy == +The filmmakers put considerable effort into many details for historical accuracy, such as military uniforms, and the details of the Enola Gay and its crew. Nine of the actors who portrayed the Enola Gay crew were actual veterans of World War II. Guy Williams made his film debut as the bombardier who releases the weapon over Hiroshima. The correct names of the accompanying aircraft are shown, although the photography plane was only named Necessary Evil after the Nagasaki mission. +By comparison, the technical details of atomic processes and the bomb's design are wildly inaccurate by intention. In 1947, these details were highly classified. No mention was made of the rich source of pitchblende supplied from the Congolese Shinkolobwe mine, and all refining of uranium was portrayed as only coming from Canadian mines. Another inaccuracy, introduced purely for dramatic effect, is the portrayal of anti-aircraft shells bursting around the aircraft on the bombing run, as the attack on Hiroshima was not opposed. +The film twice refers to supposed specific leaflet drops on the target for ten days in advance of the mission warning the citizens of the forthcoming raid. "We've been dropping warning leaflets on them for ten days now", one crew member remarks, "That's ten days more warning than they gave us before Pearl Harbor." However, there was no leaflet specifically warning of an atomic attack. In his review in the Bulletin of the Atomic Scientists, physicist Harrison Brown called this "the most horrible falsification of history". Historians have debated whether any leaflets were dropped at all. +This incident in which "Cochran" receives a fatal dose of radiation while assembling the Hiroshima bomb is a highly fictionalized reference to the deaths of Harry Daghlian and Louis Slotin, members of the Manhattan Project who died after contact with radioactive material on 21 August 1945 and 21 May 1946. (The deaths of Daghlian and Slotin were later fictionalized in Dexter Masters’s 1955 novel The Accident.) +In his award-winning book, The Beginning or the End: How Hollywood—and America—Learned to Stop Worrying and Love the Bomb (July 2020), historian and journalist Greg Mitchell explores "the shocking and significant story of how the White House and Pentagon scuttled an epic Hollywood production." + +== Release == + +=== Box office === +According to MGM records, The Beginning or the End was made on a budget of $2,632,000 (equivalent to $43,455,000 in 2025), but earned $1,221,000 (equivalent to $20,159,000 in 2025) in the United States and Canada and $721,000 (equivalent to $11,904,000 in 2025) elsewhere, resulting in a loss to the studio of $1,596,000 (equivalent to $26,350,000 in 2025). \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/The_Beginning_or_the_End-3.md b/data/en.wikipedia.org/wiki/The_Beginning_or_the_End-3.md new file mode 100644 index 000000000..68117e12b --- /dev/null +++ b/data/en.wikipedia.org/wiki/The_Beginning_or_the_End-3.md @@ -0,0 +1,40 @@ +--- +title: "The Beginning or the End" +chunk: 4/4 +source: "https://en.wikipedia.org/wiki/The_Beginning_or_the_End" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:00.346150+00:00" +instance: "kb-cron" +--- + +=== Critical reception === +Although The Beginning or the End was the first film to depict the story of the atomic bomb, both critics and the public were confused by the attempt to merge real events and fiction in a docudrama form. Bosley Crowther of The New York Times commented that "despite its generally able reenactments, this film is so laced with sentiment of the silliest and most theatrical nature that much of its impressiveness is marred." +Variety, however, described the film as a "portentous tale in broad strokes of masterful scripting and production", and a "sum credit of everybody concerned that the documentary values are sufficiently there without becoming static". +Time was less positive, noting that, "even as entertainment ... the picture seldom rises above cheery imbecility." In his Bulletin of the Atomic Scientists review, Harrison Brown considered the movie "poor", with a romantic angle "insipid in the extreme", but was most troubled by way scientific equipment was "over-glamorized" in the film, which he felt gave "a completely false impression of how scientists work." + +== See also == +Day One (1989) +Fat Man and Little Boy (1989) +Nuclear Secrets, TV mini-series (2007) +Manhattan, television series (2014–15) +Oppenheimer (2023) + +== References == + +=== Notes === + +=== Citations === + +=== Bibliography === + +== Further reading == +Mitchell, Greg (July 2020). The Beginning or the End: How Hollywood―and America―Learned to Stop Worrying and Love the Bomb. New York: The New Press. ISBN 978-1-62097-573-2. OCLC 1140359636. + +== External links == + +The Beginning or the End at the TCM Movie Database (archived) +The Beginning or the End at IMDb +The Beginning or the End at AllMovie +The Beginning or the End at the AFI Catalog of Feature Films +Film lobby poster \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/The_Best_of_Men-0.md b/data/en.wikipedia.org/wiki/The_Best_of_Men-0.md new file mode 100644 index 000000000..d88f14364 --- /dev/null +++ b/data/en.wikipedia.org/wiki/The_Best_of_Men-0.md @@ -0,0 +1,51 @@ +--- +title: "The Best of Men" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/The_Best_of_Men" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:01.525844+00:00" +instance: "kb-cron" +--- + +The Best of Men is a 2012 period drama television film, which dramatizes the pioneering work of Dr Ludwig Guttmann with paraplegic patients at Stoke Mandeville Hospital, which led to the foundation of the Paralympic Games. It stars Eddie Marsan and Rob Brydon, and aired on BBC Two. + + +== Plot == +Ludwig Guttmann (Marsan) is a Jewish refugee from Nazi Germany, sponsored to stay in the United Kingdom by CARA, while his patients were injured British servicemen, initially bewildered at finding themselves under the care of one of "the enemy". +On arrival at the hospital, the patients are kept under sedation, and immobile in bed, a regime leading to bedsores, infection, and, in many cases, death. Dr Guttman insists that the best prognosis for the patients is if they are as mobile as possible. This leads him to clash with the existing staff of nurses and doctors at the hospital, who are accustomed to merely managing the decline of their patients. +As he gradually wins the staff over with his determination and optimism, Guttmann faces a further problem in the hopelessness of some of the patients, particularly exemplified by the youngest inmate, William Heath (MacKay), who joined the army from school. William's despair is contrasted with the irrepressible humour of veteran Wynn Bowen (Brydon), who offers a constant stream of irreverent comments from his bed. +Guttman hits on competitive exercise and sport as a way of both encouraging physical exercise and building self-esteem. Now in wheelchairs, the patients compete at hockey and basketball, and begin to re-connect to the outside world. The patients visit a local pub and challenge the regulars to arm-wrestling. The previously suicidal William engages in sport so enthusiastically that he breaks a leg, to the consternation of the other medical staff. Wynn is scheduled for a reunion with his wife in Wales, although this makes his composure crack over worries about his sexual performance. After Dr Guttman tells him "there is more than one way to skin a cat", he returns, jubilantly proclaiming that he "skinned the cat!". +Guttmann organises a national disability sport competition, the first Stoke Mandeville Games, in the hospital grounds. The film closes with captions describing how these developed into the Paralympics, and how Dr Guttmann was awarded a knighthood. + + +== Cast == +Dr Ludwig Guttmann - Eddie Marsan +Private William Heath - George Mackay +Cpl Wynne Bowen - Rob Brydon +Sister Edwards - Niamh Cusack +Dr Cowan - Richard McCabe +Major-General Harold Henry Blake - Nicholas Jones +Sgt "Q" Hills, PTI Instructor - Tristan Sturrock +Mr Heath - Nigel Lindsay +Mrs Heath - Rachael Spence +Nurse Carr - Leigh Quinn + + +== Production == +Written by Lucy Gannon, the show was produced by Whitby Davison for the BBC. The majority of the filming took place at three halls of residence in the University of Bristol: Wills Hall, Goldney Hall and Manor Hall. + + +== Reception == +Lucy Mangan of The Guardian praised the acting, and saying the film 'heart' and 'soul'. Patrick Smith of The Daily Telegraph called it 'rousing, wholesome and upbeat'. + + +=== Awards === +The film won the Philadelphia Jewish Film Festival 34 Best Narrative Audience Award. + + +== References == + + +== External links == +The Best of Men at IMDb \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/The_Challenge_(2023_film)-0.md b/data/en.wikipedia.org/wiki/The_Challenge_(2023_film)-0.md new file mode 100644 index 000000000..5588e752e --- /dev/null +++ b/data/en.wikipedia.org/wiki/The_Challenge_(2023_film)-0.md @@ -0,0 +1,44 @@ +--- +title: "The Challenge (2023 film)" +chunk: 1/3 +source: "https://en.wikipedia.org/wiki/The_Challenge_(2023_film)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:04.208991+00:00" +instance: "kb-cron" +--- + +The Challenge (Russian: Вызов, romanized: Vyzov) is a 2023 Russian space drama film co-written and directed by Klim Shipenko. Filmed on the International Space Station (ISS), it is the first fictional, feature-length film featuring actors to be shot in space. The film stars Yulia Peresild as a surgeon sent to space to help an injured cosmonaut. The cast also includes Miloš Biković and Vladimir Mashkov. The film crew was accompanied by cosmonauts Anton Shkaplerov, Oleg Novitsky, and Pyotr Dubrov, and NASA astronaut Mark T. Vande Hei. +The Challenge marks the first collaboration between the Russian space corporation Roscosmos and the public broadcaster Channel One, with an approximate budget of around 1.155 billion rubles. Filming on the ISS took place for nearly two weeks. +The Challenge premiered on Cosmonautics Day and was theatrically released in Serbia and Russia on 20 April 2023 by Central Partnership, on CosMAX, an analogue of IMAX. +The film generated more than 1 billion rubles at the box office by the thirteenth day of theatrical showings. It holds the record for the highest-grossing Russian film on its opening day, and it grossed over 2 billion rubles against a production budget of 905 million rubles. + +== Plot == +During a spacewalk, Cosmonaut Oleg Bogdanov falls under a stream of debris and sustains a serious lung injury, requiring urgent medical care. Doctors on Earth conclude that Bogdanov needs surgery as soon as possible. The surgery will have to be completed on the International Space Station; otherwise, Bogdanov will almost certainly die from shock during atmospheric re-entry. +Several young thoracic surgeons volunteer to travel to the ISS to conduct the surgery. The evaluators gradually eliminate candidates during accelerated training. After he is removed from consideration, Vladislav Nikolaev proposes his friend, Evgenia Belyaeva, as a candidate without her knowledge. Belyaeva is admitted to the training program at the Yuri Gagarin Cosmonaut Training Center in Star City. +For about two weeks, Belyaeva prepares for the surgery and trains in a simulator of the ISS. Her training also includes periods of oxygen starvation in a pressure chamber, 6-g exercises in a centrifuge, and 25-second periods of weightlessness in a custom-built Il-76 aircraft. Director Volin selects Belyaeva as the best candidate to perform the surgery on the ISS. +Simultaneously, Belyaeva faces various personal problems. Ten years earlier, her husband was killed in a car accident in which she and her daughter were passengers and the husband was the driver; he had driven through a red light to reach the hospital, where she was urgently needed. Belyaeva has not forgiven herself for her husband's death. Due to her demanding career, Belyaeva also has little time to devote to caring for her aging mother and her teenage daughter, Masha. Masha is facing prosecution for assault after getting into a fight at school. +Two Soyuz crew members will assist Belyaeva on her mission: two Roscosmos cosmonauts Anton Shkaplerov, who will accompany her to orbit, and Pyotr Kudryavtsev, who is already stationed on the ISS. Kudryavtsev has been caring for the injured Bogdanov. +Shkaplerov and Belyaeva launch into orbit in a Soyuz spacecraft, which docks with the ISS. Belyaeva begins operating on Boegdanov. After penetrating Bogdanov's chest cavity, Belyaeva encounters unexpected complications. Blood clots and scar tissue have formed a non-expandable "crust" over one of Bogdanov's lungs. Mission Control decides to give the order for an emergency descent, hoping that Bogdanov will survive the journey, despite the risky odds. However, Belyaeva protests, citing the Hippocratic Oath. At first she is overruled, but after much debate, Director Volin gives her permission to continue. +Belyaeva's attempts to complete the surgery by conventional means initially fail. Nikolaev, who has remained on Earth but is watching the broadcast operation, suggests an unexpected and risky solution based upon a shared experience with Belyaeva during training. Improvising both surgical tools and techniques, Belyaeva completes the operation after seven hours. +Tension mounts as Belyaeva and the crew must wait several days to gauge the success of the operation. Bogdanov eventually revives and heals quickly. Before returning to Earth, the astronauts entertain Belyaeva with some zero-gravity games and a clandestine spacewalk. During the spacewalk, she symbolically releases her guilt over her role in her husband's death. +Upon her and Bogdanov's safe return to Earth, Belyaeva renews her connection to her daughter, Masha. Belyaeva meets Nikolaev at the hospital and learns that he is the one who submitted her name for consideration. After confessing their mutual love, they kiss. In the final scene, Belyaeva's mother stares in disbelief as she watches a news report about her daughter's safe return home. + +== Cast == +Yulia Peresild as Evgenia Vladimirovna 'Zhenya' Belyaeva, a thoracic surgeon who is launched on an emergency mission to save the life of an ailing cosmonaut +Miloš Biković as Vladislav Nikolaevich Nikolaev, as Doctor Vlad, one of the surgeons selected to be a candidate for the flight +Vladimir Mashkov as Constructor Konstantin Volin, a flight director at Mission Control +Alexey Grishin as Gennady Simonov, a replacement flight director +Andrey Shchepochkin as Valentin Vershinin, chief surgeon of the Medical Simulation Center at the Botkin Hospital, Belyaeva and Nikolaev's supervisor +Aleksandr Baluev as a general manager at the Roscosmos Space Center +Igor Gordin as Dmitry, the crew physician +Yelena Valyushkina as Galina, Evgenia Belyaeva's mother +Aleksandr Samoylenko as Prosecutor Semyonov +Alexey Barabash +Cameos + +Anton Shkaplerov as a Roscosmos cosmonaut +Oleg Novitsky as Oleg Bogdanov, the injured cosmonaut +Pyotr Dubrov as Pyotr Kudryavtsev, a test cosmonaut on the ISS +Anatoly Zabruskov as Anatoly Kochetkov, an instructor in a zero gravity aircraft +Other cast members \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/The_Challenge_(2023_film)-1.md b/data/en.wikipedia.org/wiki/The_Challenge_(2023_film)-1.md new file mode 100644 index 000000000..808127feb --- /dev/null +++ b/data/en.wikipedia.org/wiki/The_Challenge_(2023_film)-1.md @@ -0,0 +1,52 @@ +--- +title: "The Challenge (2023 film)" +chunk: 2/3 +source: "https://en.wikipedia.org/wiki/The_Challenge_(2023_film)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:04.208991+00:00" +instance: "kb-cron" +--- + +Maxim Stoyanov as Roman Biker, a mission candidate +Benik Arakelyan as Rafik, a mission candidate +Arthur Beschastnyy as Vasily 'Vasya', a mission candidate +Andrey Kuzichev as Valery 'Valera', a mission candidate +Sergey Godin as Pavel, a mission candidate +Simon Steinberg as Kirill, a mission candidate +Mikhail Troynik as Sergey, Zhenya Belyaeva's husband +Varvara Volodina as Masha, Zhenya Belyaeva's daughter +Danila Fedyunin as Borya, Masha's boyfriend +Sofya Skya as Tatiana 'Tanya', an anesthesiologist +Marianna Korobeynikova as Ksenia Bogdanova, wife of cosmonaut Oleg Bogdanov + +== Production == + +=== Background and pre-production === +The screening process began on 15 March 2021, as a joint project between Russia's federal space corporation Roscosmos, the state-controlled television network Channel One and production company Yellow, Black and White. The streaming service START took part in partnership with Tinkoff Bank and MegaFon, a company supported by the Cinema Fund Russia. The filming equipment was launched on Progress MS-17 and returned on Soyuz MS-18. +According to Konstantin Ernst, Director General of Channel One, the filmmakers wanted to confirm Russia's power in the space sector and restore the prestige of the cosmonaut profession in the eyes of the younger generation (as an example, Yulia Peresild herself did not dream of spaceflight as a child). The unique experience of express training for non-professional flight may subsequently be useful for sending scientists or doctors into space on an urgent basis. The development of the project was covered within the framework of the "Evening Urgant" program, whose members moved to the cosmodrome a week before launch. +About three thousand applications were submitted for the main role, for which Peresild was ultimately chosen. The number of which was reduced to 20–30. + +"We selected 20 candidates, and Yulia was not included in this list, because she was filming in another project. As a result, after all the tests of the medical board, all these actresses did not pass the selection. Not because they are ill, but because they are not suitable for flights." +—Konstantin Ernst, at the end of the filming of the series Gloomy River +Aside from Peresild, Ernst offered the role to the Russian singer Polina Gagarina. +On 14 May, the Interagency Committee approved the composition of the ISS main and alternate crews for the period 2021–2023. Cosmonaut Anton Shkaplerov was chosen to be the ship's commander, while Klim Shipenko and Peresild flew as spaceflight participants. The backup crew was cosmonaut Oleg Artemyev, cameraman Alexei Dudin and actress Alyona Mordovina, Mordovina being the first woman to pass the cosmonaut screening since 2012. Due to the allocation of seats on flights to the International Space Station, the flight of the director and actress necessitated rearranging mission lengths of the professional astronauts and cosmonauts, including extending the mission length of the on-orbit crew, U.S. astronaut Mark Vande Hei and his Russian cosmonaut counterparts, from six months to 1 year. +The crew members began training at the Yuri Gagarin Cosmonaut Training Center on 24 May. To prepare for filming, Shipenko trained intensively, dropping 15 kilograms (33 lb) of weight. On 23 July, the prime crew participated in a four-hour simulation inside a Soyuz replica while wearing the Sokol space suit, and on 28 July, the back-up crew completed the same exercise. According to backup commander Artemyev, the performance of the two backup spaceflight participants was outstanding. +The dress rehearsals for the movie took place after the scheduled spaceflight training each day. On 30 July, the spacecraft had its pre-launch preparation started, and on 31 August, the medical committee announced that both the main and reserve crew were healthy for spaceflight. +On 12 September, First Channel aired a reality show called The Challenge: The First in Space, about the specifics of the selection and training of project participants. + +=== In space === + +Principal photography began on 5 October, when Shkaplerov, Peresild, and Shipenko flew to the ISS aboard the Soyuz-2.1a launch vehicle with the Soyuz MS-19 crewed transport spacecraft from the Baikonur Cosmodrome in Baikonur, Kazakhstan. While on the ISS, Klim Shipenko shot about 30 hours of material, and also worked as director, art director, makeup artist, and production designer. Oleg Novitsky and Pyotr Dubrov appear in the film, with Dubrov and Mark Vande Hei assisting in the production. Shkaplerov will also appear in some scenes. +Of all the footage filmed in space, about 30% was filmed in the Nauka module, another third was filmed in the Zvezda module, and the remaining 30% was shot on the rest of the ISS modules. The footage shot in space became approximately 35 minutes of the final runtime of the film. +They left the ISS on 17 October aboard Soyuz MS-18, with Commander Oleg Novitsky. After the successful landing of Soyuz MS-18, Dmitry Rogozin revealed that Ernst had paid Roscosmos for Shipenko and Peresild's seats. + +=== Post-flight === + +The ground-based filming started in Moscow and the region of Moscow Oblast in mid-June 2022 and ended in October, with the last footage filmed at the Baikonur Cosmodrome. Some of the locations the crew filmed were the Yuri Gagarin Cosmonaut Training Center and the Voronovo sanatorium. In addition, a pavilion was erected specifically for the film, imitating the RKA Mission Control Center of the Roscosmos State Corporation. There, Miloš Biković, the star of Klim Shipenko's 2019 film Serf, joined the cast. + +== Reactions == +According to Dmitry Rogozin, then head of Roscosmos, the film was an "experiment to see if Roscosmos can prepare two ordinary people to fly in about 3 or 4 months". However, filming aboard the International Space Station was widely criticized by Russian cosmonauts and space scientists, who argued that it disrupted the Russian space program and misused public funds. +Sergei Krikalev, director of crewed programs at Roscosmos and a veteran of six spaceflights, reportedly lost his position after speaking out against the project, but was reinstated ten days later following protests from cosmonauts both on active duty and retired. + +== Release == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/The_Challenge_(2023_film)-2.md b/data/en.wikipedia.org/wiki/The_Challenge_(2023_film)-2.md new file mode 100644 index 000000000..e7e4975e6 --- /dev/null +++ b/data/en.wikipedia.org/wiki/The_Challenge_(2023_film)-2.md @@ -0,0 +1,63 @@ +--- +title: "The Challenge (2023 film)" +chunk: 3/3 +source: "https://en.wikipedia.org/wiki/The_Challenge_(2023_film)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:04.208991+00:00" +instance: "kb-cron" +--- + +=== Marketing === +On New Year's Eve, Channel One released the first musical number, and the first teaser trailer was released on 1 January 2023. +The second trailer was released on 7 March 2023. +On 6 April 2023, the premiere took place on Okhotny Ryad Street, under the descent module of the Soyuz MS-18 spacecraft that was installed near Manezhnaya Square, Moscow. + +On 10 April, the Cosmos Pavilion No. 32 at the Exhibition of Achievements of National Economy hosted the presentation and cancellation ceremony for a new postage stamp, part of the country's "Modern Russian Cinematography" series, depicting the movie's poster art. The 30-ruble stamp was issued the following Friday to coincide with the film's theatrical release and was accompanied by special postal cancellations at stations in Moscow, Star City and Korolyov in the Moscow Oblast, and elsewhere in Perm, Chelyabinsk and Baikonur. +To minimize competition with other films, foreign films such as The Super Mario Bros. Movie and Dungeons & Dragons: Honor Among Thieves were temporarily removed from the cinema schedule during the rental period. +The tagline is "Become a star, by flying to the stars!" + +=== Theatrical === +The Challenge was released by Central Partnership, which is part of the Gazprom-Media holding in the Russian Federation. As reported by Vedomosti, Central Partnership has developed a new cinema format that contains technical characteristics similar to IMAX, called CosMAX. +The film had a special screening on 12 April 2023 at a solemn event for politicians dedicated to Cosmonautics Day at the State Kremlin Palace, as well as its world premiere at the Karo 11 October cinema center on New Arbat Avenue in Moscow. The film had its Serbian premiere on 20 April at the Cineplexx Galerija in Belgrade, and it was scheduled to be released theatrically at the Baikonur Cosmodrome in Kazakhstan and the Russian Federation on 20 April 2023. +The Challenge premiered on 2 May in a promotional video showing the cast and crew's impressions of space. They were joined by cosmonauts Dmitry Petelin, Sergey Prokopyev and Andrey Fedyaev, and seven other American and Emirati astronauts, all of whom had seen the film onboard the ISS. + +=== Home media === +The Challenge was released on digital rental in Russia on 1 September 2023, on the Start platform. + +== Reception == +The film's advertising budget was 91 million rubles, according to Mediaplus Group Russia. The Challenge was promoted mainly on Channel One, and the state portal Gosuslugi also sent out letters advertising the film. + +=== Box office === +Having been released at the same time as the films John Wick: Chapter 4 and To Catch a Killer, in its first weekend, The Challenge took first place at the Russian box office and the CIS countries, earning a total box office revenue of 426 million rubles. +In its second weekend, the film again became the leader: as of 3 May 2023, the film's box office receipts reached 1 billion rubles. +On 7 August 2023, the film crossed the 2 billion rubles in 15 weeks, which is estimated to be the mark in Russia. + +=== Critical response === +In Russian media, reception was mixed, leaning towards positive. Film critics praised the visuals and Peresild's acting, but were divided about the melodramatic parts of the plot, supposed ideology, and how the movie deals with representation of women in space. Some critics took issue with the very idea of a costly space filming, while others praised it as an achievement. The Challenge was praised in reviews by Nezavisimaya Gazeta, KinoPoisk, and Lenta.ru, among others, while reviews in Kommersant and Film.ru were less enthusiastic, and Afisha was sharply critical. + +=== Accolades === + +During Russia Day festivities in the Grand Kremlin Palace’s St George Hall, President Vladimir Putin, on 12 June 2023, awarded Shipenko and Peresild a state prize in the field of literature and art for the film, though Shipenko could not attend due to work obligations. +In November 2023, the film was recognized as the best project in the nomination of the Event of the Year award by KinoReporter magazine. +In 2023, the film received a nomination at the Golden Trailer Awards in the category Best Foreign Trailer. +The film was nominated for the Golden Rooster Awards in the category of Best Foreign Language Film. +The film was nominated for the Nika Award in the category Best Film, and Yulia Peresild won the award for Best Actress. +The film received five nominations at the Golden Eagle Award: Best Visual Effects, Best Sound, Best Film Editing, Best Actress, and Best Feature Film. +The film received awards from the Russian APKIT Awards (the professional prize of the Association of Film and Television Producers) in the categories Best Feature Film and Special Prize. + +== Notes == + +== See also == +List of movies filmed in space +List of films featuring space stations + +== References == + +=== Bibliography === +Quine, Tony (2022). "Alyona's Adventures in Wonderland". Spaceflight. 64 (3): 27–31. + +== External links == + +Official website (in English) +The Challenge at IMDb \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/The_Challenger_Disaster-0.md b/data/en.wikipedia.org/wiki/The_Challenger_Disaster-0.md new file mode 100644 index 000000000..ddf344883 --- /dev/null +++ b/data/en.wikipedia.org/wiki/The_Challenger_Disaster-0.md @@ -0,0 +1,54 @@ +--- +title: "The Challenger Disaster" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/The_Challenger_Disaster" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:05.437111+00:00" +instance: "kb-cron" +--- + +The Challenger (US title: The Challenger Disaster) is a 2013 TV movie starring William Hurt about Richard Feynman's investigation into the 1986 Space Shuttle Challenger disaster. The film was co-produced by the BBC, the Science Channel, and Open University, and it premiered on 12 May 2013 on BBC2. +It is based on two books What Do You Care What Other People Think? (1988) and Truth, Lies and O-Rings. +The film follows Feynman (William Hurt) as he attempts to expose the truth in the disaster. +It aired in the U.S. on the Discovery Channel and the Science Channel on 16 November 2013. + + +== Plot == +Dr. Richard Feynman, a physics professor at Caltech, gives a guest lecture to students, lamenting on both the power and limitations of science. While driving home, he hears on the radio that the Space Shuttle Challenger exploded on takeoff and that it is very likely the astronauts perished in the accident. Several days later, he receives a phone call from a former student of his, who asks him to sit on the Presidential Commission to determine what caused the accident. Feynman, a vocal opponent of the political games politicians and government play, initially is unsure if he should participate; however, his wife Gwen encourages him that he cannot pass up a puzzle like this, and must sit on the inquiry and figure out what really happened. +Feynman arrives in Washington and quickly realizes the chairman William Rogers wants to protect NASA and may not be seeking the real truth of what caused the accident. Unbeknownst to Feynman, the commission will be in recess for five days before any official work begins. During this time he visits various NASA production facilities on his own to learn and attempt to determine the cause of the accident. There he finds a culture lacking in truth and reality as NASA employees are afraid to openly discuss known issues with the shuttle program out of fear. As a maverick investigator, Feynman discovers many other known issues through research and a surreptitious note that the loss of a shuttle was expected. Feynman's only ally on the commission, General Donald J. Kutyna, attempts to leak information to Feynman as he has a secret source within NASA who knows what really happened. +As Feynman draws closer to the truth his health dramatically changes as he discovers he has cancer. Realizing how important the truth is, he returns to Washington to divulge the reason for the shuttle's failure. In a televised broadcast of the commission hearing, having discovered that the O-rings were the culprit for the explosion, he demonstrates that due to cold temperatures, the O-ring could not expand and caused the explosion. Unable to hide from these findings, the commission issues its report to President Ronald Reagan with Feynman including an appendix with his own findings, citing "for a successful technology, reality must take precedence over public relations, for nature cannot be fooled." The film closes with a montage of several key members in the film and their contributions. + + +== Reception == +The movie scored an overall approval rating of 92% on Rotten Tomatoes. +Neil Genzlinger of The New York Times writes "The Challenger investigation story doesn’t have quite the level of malfeasance or the cloak-and-dagger undertones of other movies about real-life government or business debacles. But it still makes for an absorbing tale, one that seems well timed for our current moment of bungled websites, unrestrained eavesdropping and public skepticism." +Michael Starr of The New York Post writes "It’s both a learning experience and an emotional reminder of what can go wrong in that gray area separating man and machine." +Hank Stuever of The Washington Post writes "The film is an appropriately somber and smoothly told account of the Washington politics and cross-agency obfuscation that nearly derailed the commission's investigation into the disaster, which claimed the lives of seven astronauts, including schoolteacher Christa McAuliffe". + + +== Cast == +William Hurt as Dr. Richard Feynman +Joanne Whalley as Gweneth Feynman +Bruce Greenwood as General Donald Kutyna +Brian Dennehy as Chairman William Rogers +Eve Best as Dr. Sally Ride +Henry Goodman as Dr. Weiss +Kevin McNally as Lawrence Mulloy +Sean Michael as Judson Lovingood + + +== See also == +Rogers Commission Report +Challenger, 1990 film +Challenger: The Final Flight, 2020 documentary miniseries + + +== References == + + +== External links == +The Challenger Disaster at IMDb +The Challenger Disaster at Rotten Tomatoes +The Challenger Disaster at Metacritic +The Challenger on BBC2 \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/The_Food_That_Built_America-0.md b/data/en.wikipedia.org/wiki/The_Food_That_Built_America-0.md new file mode 100644 index 000000000..5668cd033 --- /dev/null +++ b/data/en.wikipedia.org/wiki/The_Food_That_Built_America-0.md @@ -0,0 +1,70 @@ +--- +title: "The Food That Built America" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/The_Food_That_Built_America" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:14.590588+00:00" +instance: "kb-cron" +--- + +The Food That Built America is an American nonfiction docudrama series for the History Channel, that premiered on August 11, 2019. Each episode outlines the development of a popular type of food or restaurant in the United States, typically focusing on the rise of two major companies that become rivals. Historical events in the relevant timelines are re-enacted for dramatic effect and interspersed with commentary by culinary historians, business experts, and food enthusiasts. +The series was first announced in March 2019 and premiered on August 11, 2019. To date, it has aired six complete seasons; a seventh premiered on April 19, 2026. It is the fourth installment of the That Built franchise. + + +== Episodes == + + +=== Series overview === + + +=== Season 1 (2019) === + + +=== Season 2 (2021) === + + +=== Season 3 (2022) === + + +=== Season 4 (2023) === + + +=== Season 5 (2024) === + + +=== Season 6 (2025) === + + +=== Season 7 (2026) === + + +== Production == + +In March 2019, the series was green-lit. In May 2020, the series was renewed for a second season. Yoshi Stone is the series' showrunner. Along with Stone, Kim Woodard, Greg Henry, and Isaac Holub executive produce for Lucky 8. Jim Pasquarella and Mary E. Donahue executive produce for the History Channel. + + +== Reception == +The first season garnered a total of 18.8 million viewers. + + +== Podcast == +In February 2021, the History Channel partnered with Ozy Media to launch a podcast of the same name. The first episode premiered on February 4, 2021. + + +== The Food That Built America Snack Sized == +In 2021, the producers of The Food That Built America created a new series called The Food That Built America Snack Sized by reediting some episodes to approximately half of the original size through the elimination of food historian commentary and some minor scenes to make smaller size episodes with a faster pace. + + +== References == + +59. https://www.memorabletv.com/news/food-that-built-america-new-season/. New season +60. https://www.rottentomatoes.com/tv/the_food_that_built_america/s05/e14. Season 6 Episode 1 +61. https://en.myshows.me/view/episode/18837529/. Season 6 Episode 2 +62.https://www.rottentomatoes.com/tv/the_food_that_built_america/s06/e03. Season 6 Episode 3 + + +== External links == +Official website +The Food That Built America at IMDb +The Food That Built America Snack Sized at IMDb \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/The_Heavy_Water_War-0.md b/data/en.wikipedia.org/wiki/The_Heavy_Water_War-0.md new file mode 100644 index 000000000..a96291175 --- /dev/null +++ b/data/en.wikipedia.org/wiki/The_Heavy_Water_War-0.md @@ -0,0 +1,90 @@ +--- +title: "The Heavy Water War" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/The_Heavy_Water_War" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:38:19.725393+00:00" +instance: "kb-cron" +--- + +The Heavy Water War (original title Kampen om tungtvannet and alternative title The Saboteurs (United Kingdom)) is a six-episode war drama television miniseries written by Petter S. Rosenlund and produced by Norwegian Broadcasting Corporation. It is a Norwegian/Danish/British co-production directed by Per-Olav Sørensen based on the true story of the German nuclear weapon project during the Second World War and the heavy water sabotage in Norway to disrupt it, with a particular emphasis on the role of the Norwegian intelligence officer Leif Tronstad. +The first two episodes were initially broadcast on NRK1, on 4 January 2015. The opening episodes had 1,259,000 viewers, which was a record for the opening of a drama series in Norway. +In Denmark, the initial broadcast was on 4 May 2015 on TV 2 titled Kampen om det tunge vand. +In the UK, the miniseries, retitled The Saboteurs, was aired by More4 from 19 June 2015 and had a good critical reception. The series was released in the UK on DVD and Blu-ray on 10 August 2015. In Poland the show premiered on 15 January 2016 on ipla VOD to very good reviews. Viewing rights for France were bought by Entertainment One, for Benelux by Lumière, for Spain by A Contracorriente, for Poland by Kino Swiat and for the Balkans by Stas Media. Viewing rights for the US were bought by MHz Networks, which announced a DVD release date of 8 March 2016. + + +== Production == +The series was filmed in Norway and the Czech Republic. Production costs were around 75 million Norwegian kroner, or about €7.8 million. The dialogue is in Norwegian, German, English and Danish. + + +== Main cast == +Although the series is based on real events and persons, apart from Aubert, all other Nazi collaborating Hydro directors were purposely not mentioned by name. + +Espen Klouman Høiner as Major Leif Tronstad +Christoph Bach as Werner Heisenberg +Pip Torrens as Colonel John Skinner Wilson, SOE +Anna Friel as Captain Julie Smith (fictitious) +Søren Pilmark as Niels Bohr +Stein Winge as Axel Aubert, Director-General of Norsk Hydro +Dennis Storhøi as Bjørn Henriksen, plant director (fictitious) +Maibritt Saerens as Ellen Henriksen, plant director's wife (fictitious) +Espen Reboli Bjerke as Jomar Brun +David Zimmerschied as Carl Friedrich von Weizsäcker +Andreas Döhler as Kurt Diebner, director of the German nuclear energy project +Robert Hunger-Bühler as General der Artillerie Emil Leeb, Chief of the Waffenamt +Corey Johnson as Major General Pat Pritchard, USAAF (fictitious) +Peri Baumeister as Elisabeth Heisenberg + + +=== Operation "Grouse" === + +Torstein Bjørklund as Sergeant Arne Kjelstrup +Benjamin Helstad as Second Lieutenant Jens-Anton Poulsson +Rolf Kristian Larsen as Einar Skinnarland +Christian Rubeck as Sergeant Claus Helberg +Audun Sandem as Second Lieutenant Knut Haugland + + +=== Operation "Gunnerside" === + +Endre Ellefsen as Sergeant Hans Storhaug +Ole Christoffer Ertvaag as Sergeant Birger Strømsheim +Eirik Evjen as Second Lieutenant Kasper Idland +Frank Kjosås as Second Lieutenant Knut Haukelid +Mads Sjøgård Pettersen as Sergeant Fredrik Kayser +Tobias Santelmann as Second Lieutenant Joachim Rønneberg + + +== Episodes == + + +== Reception == +Norwegian newspaper Verdens Gang gave the series a 5 out of 6, citing "It will enrage some historians, and some concerned will complain, but most television viewers will be engrossed". +The series won the 2015 Prix Italia in the Series and Serials category, with the citation: "A thriller with superb acting, a high-quality production. Great cinematography, outstanding acting, excellent directing." + + +=== Viewer numbers === +The two first episodes were seen by 1.259 million in Norway, the third episode was seen by 1.239 million and the fourth by 1.288 million. The fifth episode was seen by 1.319 million while the last was seen 1.322 million. The last episode was watched by 64% of TV viewers that hour. + + +=== Historicity === +From the première there has been debate over its historical accuracy. Among concerns have been Heisenberg's involvement in the development of nuclear weapons and allusions to his homosexuality. + + +== Previous versions == +The same story was covered in the 1948 Franco-Norwegian film Kampen om tungtvannet (also known as La bataille de l'eau lourde or Operation Swallow: The Battle for Heavy Water). Quite faithful to real events, it even had many of the original Norwegian commandos starring as themselves. +The 1965 British film The Heroes of Telemark, starring Kirk Douglas and Richard Harris, was another version of the story. +Ray Mears presented a documentary called The Real Heroes of Telemark in 2003. Despite mainly sticking to the factual evidence, some scenes in the documentary were partly dramatised, focusing on the survival skills involved in the operation. + + +== See also == +Norwegian heavy water sabotage + + +== References == + + +== External links == +The Heavy Water War at IMDb +Trailer: The Heavy Water War on YouTube \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/The_Incidental_Economist-0.md b/data/en.wikipedia.org/wiki/The_Incidental_Economist-0.md new file mode 100644 index 000000000..ea4baba06 --- /dev/null +++ b/data/en.wikipedia.org/wiki/The_Incidental_Economist-0.md @@ -0,0 +1,29 @@ +--- +title: "The Incidental Economist" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/The_Incidental_Economist" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:13.635645+00:00" +instance: "kb-cron" +--- + +The Incidental Economist is a blog focused on health economics and policy. It was founded in 2009 by Austin Frakt, a health economist at Boston University, who has since been joined by Aaron Carroll, a pediatrician at Indiana University School of Medicine, as co-Editor-in-Chief. The site features posts by the two as well as a number of contributing writers, who are primarily academics based across the United States. The authors often synthesize academic literature as it might relate to contemporary health policy issues. +The blog gained prominence in 2009–10 when it was often cited by journalists, such as Ezra Klein, Kevin Drum, Jonathan Cohn and Andrew Sullivan, who were covering the health care reform process that would eventually culminate in the Patient Protection and Affordable Care Act. The blog remains one of the most widely cited health policy blogs on the Internet. + + +== Regular contributors == +Austin Frakt (founder, co-Editor-in-Chief): health economist at the United States Department of Veterans Affairs, associate professor at Boston University, contributor to The New York Times' The Upshot +Aaron Carroll (co-Editor-in-Chief): professor of pediatrics and dean for research mentoring at Indiana University School of Medicine, contributor to The New York Times' The Upshot +Adrianna McIntyre (Managing Editor): Ph.D student at Harvard University 2016 MPH/MPP dual-degree graduate at the University of Michigan +Kevin Outterson: Professor of law and public health at Boston University +Harold Pollack: professor at the School of Social Service Administration at the University of Chicago +Bill Gardner: child psychologist, professor of epidemiology, chair of child and adolescent psychiatry, and health services researcher at the University of Ottawa +Nicholas Bagley: professor of law at the University of Michigan + + +== References == + + +== External links == +The Incidental Economist \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/The_Intelligent_Man's_Guide_to_Science-0.md b/data/en.wikipedia.org/wiki/The_Intelligent_Man's_Guide_to_Science-0.md new file mode 100644 index 000000000..639bb9761 --- /dev/null +++ b/data/en.wikipedia.org/wiki/The_Intelligent_Man's_Guide_to_Science-0.md @@ -0,0 +1,51 @@ +--- +title: "The Intelligent Man's Guide to Science" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/The_Intelligent_Man's_Guide_to_Science" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:42.250683+00:00" +instance: "kb-cron" +--- + +The Intelligent Man's Guide to Science is a general guide to the sciences by the American writer and scientist Isaac Asimov. It was first published in 1960 by Basic Books. Revised versions were published as The New Intelligent Man's Guide to Science (1965), Asimov's Guide to Science (1972), and Asimov's New Guide to Science (1984). +The book received positive reviews, praising it as a well-written work on science. + + +== Background and publication history == +Asimov was first contacted by Leon Svirsky of Basic Books in 1957 about the possibility of writing a book that would provide an overview of science, and the two met at Asimov's home on 13 May to discuss the details. Six days later, Asimov received a contract for the book, along with a $1500 advance. At this point in his life, it had been just over a year since Asimov had given up his teaching duties at Boston University and taken up writing full-time. He had published 11 nonfiction books, including books on chemistry, physics, astronomy, a college-level biochemistry textbook, and a collection of science essays. However, he was momentarily daunted by the prospect of writing a major book on all of science, and he delayed signing the contract until 15 July, after receiving encouragement from his friend (and future wife) Janet Jeppson. +The book's title was Svirsky's, chosen as a deliberate homage to George Bernard Shaw's The Intelligent Woman's Guide to Socialism and Capitalism (1928). Asimov feared the title would be seen as elitist and condescending, and he suggested Everyone's Guide to Science as an alternative, but Svirsky refused. Years later, when he was confronted by annoyed feminists who asked why the book was restricted to men, Asimov would claim that the "intelligent man" of the title referred to himself; thus anticipating the title Asimov's Guide to Science adopted for the third edition. Svirsky also wanted the book confined to scientific advances made in the 20th century. Asimov, however, preferred to approach each field in a historical manner, starting with the ancient Greeks or, at the very least, Galileo Galilei. As often happened when Asimov was given editorial directions he disagreed with, he ignored them, and wrote the book just as he wanted to. In organizing the various fields of science, Asimov chose to begin with the universe as a whole and work inward in narrowing circles until he was inside the brain at the end. +Asimov began work on the book on 2 October, and found that he had no trouble with it at all, writing anywhere from 6,000 to 10,000 words a day without any sense of strain. By 27 January 1958, Asimov was able to deliver the first half of the completed manuscript to Basic Books, but at a meeting a month later, Svirsky suggested cutting the book in half so it could fit in one volume. At that point, Asimov was only two chapters shy of finishing the book, but saw no reason to complete it if it would be subjected to such radical abridgment, and halted work. He resumed work after being informed on 11 March that Svirsky would not try to reduce the book by half, but would instead publish it in two volumes. Svirsky also insisted that the book include an introduction by the geneticist George Beadle. Asimov felt that his work didn't need an introduction by anyone else, and even though he found Beadle's introduction to be very elegant, he still resented its inclusion. Asimov delivered the final chapters to Basic Books on 21 April, and the appendices on 4 May. +When he began proofing the book's galleys, Asimov was horrified to find that Svirsky still cut out some 30% of the book's material. Asimov reinserted as much information into the galley proofs as he could, but he remained unhappy with the book. +The Intelligent Man's Guide to Science was first published in 1960 by Basic Books. It was published, in revised editions, as The New Intelligent Man's Guide to Science in 1965, Asimov's Guide to Science in 1972, and Asimov's New Guide to Science in 1984. + + +== Reception == + +The Intelligent Man's Guide to Science received positive reviews from the physicist Derek J. de Solla Price in Science and Floyd C. Gale in Galaxy Science Fiction, and a mixed review from John Pfeiffer in The New York Times. +Price considered Asimov's work a novelty in popular science writing. He credited Asimov with surveying the whole of modern science. Gale credited Asimov with writing well and making difficult concepts easy to understand. Gale considered the book well-written and credited Asimov with helping to make even difficult concepts easy to understand. Pfeiffer wrote that Asimov tried to discuss too many aspects of science in the limited space available to him and compressed material "to a point where the result is almost a listing of developments with inadequate transitions in between". He concluded that Asimov had "prepared a good introduction to modern research" that "would have been better if he had allowed himself more space for the unique, imaginative writing of which he is so obviously capable." +The Intelligent Man's Guide to Science was nominated for a National Book Award in the nonfiction category, losing to the journalist William L. Shirer's The Rise and Fall of the Third Reich (1960). Asimov has stated that The Intelligent Man's Guide to Science led to his recognition as a major figure in the field of science writing. +Asimov's Guide to Science was reviewed by John Cheney in Contemporary Physics. Asimov's New Guide to Science received positive reviews from Paul Stuewe in Quill & Quire, Margrett J. McFadden in Voice of Youth Advocates, and Robert H. Bell in Science Books & Films, and a mixed review from E. L. Williams in Choice. The book was also reviewed by Jim Pirie in The Chemical Engineer and the geneticist H. Bentley Glass in The Quarterly Review of Biology. +Stuewe considered the book well-written, and credited Asimov with covering developments in technology since the publication of Asimov's Guide to Science. McFadden considered the book enjoyable to read, and praised Asimov for presenting new information "from dinosaurs to robots, the solar system to new physics discoveries". Bell considered the book thorough and engaging, crediting Asimov with "encyclopedic knowledge of astronomy, geology, physics, and chemistry" and "considerable understanding and knowledge of organic chemistry, cellular function and theory, microbiology, the human body and its needs, evolution, and the mind", and providing useful "figures, sketches, and maps". Williams complimented Asimov for his updated treatment of artificial intelligence, computers, cancer, the solar system, quasars, black holes, evolution, and the energy crisis, but considered it disappointing that there was no update on genetic engineering. Williams also commented that, "There are fewer photographs and their quality is not as good as in the 1972 edition. The table of contents has been divided into very helpful subheadings, making it easy to use as a quick reference. The name and subject indexes are good." + + +== See also == +Isaac Asimov bibliography +Isaac Asimov bibliography (alphabetical) +Isaac Asimov bibliography (chronological) + + +== References == + + +=== Footnotes === + + +=== Bibliography === +Books + +Journals + + +== External links == +Floyd C. Gale's review \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/The_Merger_of_Knowledge_with_Power-0.md b/data/en.wikipedia.org/wiki/The_Merger_of_Knowledge_with_Power-0.md new file mode 100644 index 000000000..ced660426 --- /dev/null +++ b/data/en.wikipedia.org/wiki/The_Merger_of_Knowledge_with_Power-0.md @@ -0,0 +1,31 @@ +--- +title: "The Merger of Knowledge with Power" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/The_Merger_of_Knowledge_with_Power" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:44.878360+00:00" +instance: "kb-cron" +--- + +The Merger of Knowledge with Power: Essays in Critical Science is a book written in 1990 by Jerome Ravetz. +The book contains a series of essays which touch upon science and policy, the role of ideologies in scientific progress, and broader themes of history and philosophy of Science, with critical attention to points of friction between science and society. "We can best understand this anthology as a 20-year continuation of his seminal +study, Scientific Knowledge and Its Social Problems". +In this book Ravetz invites us to consider science and its prodigious achievements on the face of the growing awareness that science is also at the root of many modern problems. In the opening essay "A critical awareness of science" he suggests adopting the perspective of the poor, and considering where science has failed them. +In the essay on "Francis Bacon and the Reform of Philosophy" Ravetz argues that Bacon's audacious reform programme owed much more to his religion views, hopes and expectation than is normally accounted for. The Chapter "Ideological Commitment in the Philosophy of Science' offers Ravetz's first hand reading of the relevance of ideology in the philosophies of science of Karl Popper, +Thomas Kuhn, Imre Lakatos and Paul Feyerabend. +The book has detailed discussions of risks and regulation and science's role therein, and a critique of 'reckless' science ("Hardware and Fantasy in Military Technology"). Ravetz also presents his insight on the use of ignorance ("Usable Knowledge, Usable Ignorance: Incomplete Science with Policy Implications"; the book is credited with having provided the first illustration of ‘science-based ignorance’, p. 26), the Gaia hypothesis, how to constructively tackle the problems of quality control of quantitative information, and the need for "A new social contract for science". For Carrozza (2015) this book (p. 284) investigates the two interrelated processes +of the scientization of politics and of the politicization of expertise "in the spirit of a general call for renewing +the social contract between science and society". + + +== Reviews == +Two reviews are available, one on American Scientist and another on +New Scientist + + +== References == + + +== External links == +Related material \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/The_Oil_Drum-0.md b/data/en.wikipedia.org/wiki/The_Oil_Drum-0.md new file mode 100644 index 000000000..c9dacfa23 --- /dev/null +++ b/data/en.wikipedia.org/wiki/The_Oil_Drum-0.md @@ -0,0 +1,25 @@ +--- +title: "The Oil Drum" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/The_Oil_Drum" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:16.020105+00:00" +instance: "kb-cron" +--- + +The Oil Drum was a website devoted to analysis and discussion of energy and its impact on society that described itself as an "energy, peak oil & sustainability research and news site". The Oil Drum was published by the Institute for the Study of Energy and Our Future, a Colorado non-profit corporation. The site was a resource for information on many energy and sustainability topics, including peak oil, and related concepts such as oil megaprojects, Hubbert linearization, and the Export Land Model. The Oil Drum had over 25 online contributors from all around the globe. In 2013, the site ceased publishing new articles. As of October 2016, the site continues to function as an archive. +The Oil Drum was rated one of the top five sustainability blogs of 2007 by Nielsen Netratings, and was read by a diverse collection of public figures, including Roscoe Bartlett, Paul Krugman, James Howard Kunstler, Richard Rainwater, and Radiohead. In 2008, the site received the M. King Hubbert Award for Excellence in Energy Education from the U.S. chapter of the Association for the Study of Peak Oil and Gas (ASPO). +The Oil Drum was started in March 2005 by Kyle Saunders (username "Prof. Goose"), a professor of political science at Colorado State University, and Dave Summers (username "Heading Out"), a professor of mining engineering at Missouri University of Science and Technology (then known as University of Missouri-Rolla). The site first rose to prominence following its coverage of the impact of Hurricanes Katrina and Rita on oil and gas production. The staff grew by dozens and became well known for rigorous, quantitative analysis of energy production and consumption. A notable example is former editor Stuart Staniford's analysis of the depletion of Saudi Arabia's Ghawar oil field (Depletion Levels in Ghawar). +The site started out on the Blogger platform, moved to Scoop in August 2005, and to Drupal in December 2006. +In 2013, The Oil Drum announced that it would stop publishing new content and would turn into an archive resource. Reasons cited for this change include server costs and a dwindling number of contributors of high-quality content. +Other sources claimed that the site was archived to prevent further embarrassment to contributors as global oil production continued to increase. + + +== References == + + +== External links == +The Oil Drum +"The Oil Drum: $100 a Barrel Quickens the Beat" - Interview with The Oil Drum editor Nate Hagens, January 7, 2008. +"The Oil Drum, peak oil and why some good blogs don’t last" - Retrospective look at The Oil Drum and the circumstances leading to its shutdown, August 29, 2013. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/The_Panda's_Thumb_(blog)-0.md b/data/en.wikipedia.org/wiki/The_Panda's_Thumb_(blog)-0.md new file mode 100644 index 000000000..857309685 --- /dev/null +++ b/data/en.wikipedia.org/wiki/The_Panda's_Thumb_(blog)-0.md @@ -0,0 +1,24 @@ +--- +title: "The Panda's Thumb (blog)" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/The_Panda's_Thumb_(blog)" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:17.273178+00:00" +instance: "kb-cron" +--- + +The Panda's Thumb is a blog on issues of creationism and evolution from a mainstream scientific perspective. In 2006, Nature listed it as one of the top five science blogs, and Mark Pallen has called it "the definitive blog on the evolution versus creationism debate". +It is written by multiple contributors, including Wesley R. Elsberry, Joe Felsenstein, Paul R. Gross, Nick Matzke, and Mark Perakh, many of whom used to have complementary blogs at ScienceBlogs before it went defunct. The blog takes its name from The Panda's Thumb, the pub of the virtual University of Ediacara, which is named after the book of the same name by Stephen Jay Gould, which in turn takes its title from the essay "The Panda's Peculiar Thumb", which discusses the Panda's sesamoid bone, an example of convergent evolution. + + +== See also == +Rejection of evolution by religious groups + + +== References == + + +== External links == +Official website +Status page \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/The_Scientific_Activist-0.md b/data/en.wikipedia.org/wiki/The_Scientific_Activist-0.md index e9a9b74da..2cf6d4ca9 100644 --- a/data/en.wikipedia.org/wiki/The_Scientific_Activist-0.md +++ b/data/en.wikipedia.org/wiki/The_Scientific_Activist-0.md @@ -4,7 +4,7 @@ chunk: 1/1 source: "https://en.wikipedia.org/wiki/The_Scientific_Activist" category: "reference" tags: "science, encyclopedia" -date_saved: "2026-05-05T06:46:47.005972+00:00" +date_saved: "2026-05-05T07:37:24.681403+00:00" instance: "kb-cron" --- diff --git a/data/en.wikipedia.org/wiki/The_Ultimate_Experiment-0.md b/data/en.wikipedia.org/wiki/The_Ultimate_Experiment-0.md new file mode 100644 index 000000000..5149d21af --- /dev/null +++ b/data/en.wikipedia.org/wiki/The_Ultimate_Experiment-0.md @@ -0,0 +1,14 @@ +--- +title: "The Ultimate Experiment" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/The_Ultimate_Experiment" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:52.543867+00:00" +instance: "kb-cron" +--- + +The Ultimate Experiment: Man-Made Evolution is a 1977 book by science writer Nicholas Wade about the then-new and controversial field of recombinant DNA research ("gene splicing"), much of it drawn from his earlier news and commentary as a writer for Science. An updated edition with a new chapter was published in 1979. + + +== Citations == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Tombolo-0.md b/data/en.wikipedia.org/wiki/Tombolo-0.md new file mode 100644 index 000000000..057a0bd08 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Tombolo-0.md @@ -0,0 +1,61 @@ +--- +title: "Tombolo" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Tombolo" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:34.663042+00:00" +instance: "kb-cron" +--- + +A tombolo is a sandy or shingle isthmus. It is a deposition landform by which an island becomes attached to the mainland by a narrow piece of land such as a spit or bar. Once attached, the island is then known as a tied island. The word tombolo is from the Italian tombolo, meaning 'pillow' or 'cushion', and sometimes translated incorrectly as ayre (an ayre is a shingle beach of any kind). +Several islands tied together by bars which rise above the water level are called a tombolo cluster. Two or more tombolos may form an enclosure (called a lagoon) that can eventually fill with sediment. + + +== Formation == + +The shoreline moves toward the island (or detached breakwater) owing to the accretion of sand in the lee of the island, where wave energy and longshore drift are reduced and therefore deposition of sand occurs. + + +=== Wave diffraction and refraction === +True tombolos are formed by wave refraction and diffraction. As waves near an island, they are slowed by the shallow water surrounding it. These waves then bend around the island to the opposite side as they approach. The wave pattern created by this water movement causes a convergence of longshore drift on the opposite side of the island. The beach sediments that are moving by lateral transport on the lee side of the island will accumulate there, conforming to the shape of the wave pattern. In other words, the waves sweep sediment together from both sides. Eventually, when enough sediment has built up, the beach shoreline, known as a spit, will connect with an island and form a tombolo. + + +=== Unidirectional longshore drift === +In the case of longshore drift due to an oblique wave direction, like at Chesil Beach or Spurn Head, the flow of material is along the coast in a movement which is not determined by wave diffraction around the now tied island, such as the Isle of Portland, which it has reached. In this and similar cases like Cádiz, while the strip of beach material connected to the island may be technically called a tombolo because it links the island to the land, it is better thought of in terms of its formation as a spit, because the sand or shingle ridge is parallel rather than at right angles to the coast. + + +== Morphology and sediment distribution == +Tombolos demonstrate the sensitivity of shorelines. A small piece of land, such as an island, or a beached shipwreck can change the way that waves move, leading to different deposition of sediments. Sea level rise may also contribute to accretion, as material is pushed up with rising sea levels. Tombolos are more prone to natural fluctuations of profile and area as a result of tidal and weather events than a normal beach is. +Because of this susceptibility to weathering, tombolos are sometimes made more sturdy through the construction of roads or parking lots. The sediments that make up a tombolo are coarser towards the bottom and finer towards the surface. It is easy to see this pattern when the waves are destructive and wash away finer grained material at the top, revealing coarser sands and cobbles as the base. + + +== Examples == + +Some of these may be simple isthmuses, and not have the deposition creation that defines a true tombolo. + + +=== Image gallery === + + +== See also == + +Ayre (landform) – Shingle beaches in Orkney and Shetland +Bar – Natural submerged sandbank that rises from a body of water to near the surfacePages displaying short descriptions of redirect targets +Causeway – Route raised up on an embankment +Cuspate foreland – Geographical features found on coastlines and lakeshores +Isthmus – Strip of land connecting two larger areas +Peninsula – Land feature +Tied island – Island that is connected to land only by a tombolo +Shoal – Natural submerged sandbank that rises from a body of water to near the surface + + +== References == + + +== External links == + +Geology.About.com's page on tombolos (useful for its descriptive photograph) +Tombolo in Sainte-Marie, Martinique (useful for its photos and description) +further reading on Detached breakwaters from Vlaams Instituut voor de Zee in Belgium +further reading on coastal structures from Prof. Leo van Rijn in Holland \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Trochoidal_wave-0.md b/data/en.wikipedia.org/wiki/Trochoidal_wave-0.md new file mode 100644 index 000000000..4794636c8 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Trochoidal_wave-0.md @@ -0,0 +1,527 @@ +--- +title: "Trochoidal wave" +chunk: 1/2 +source: "https://en.wikipedia.org/wiki/Trochoidal_wave" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:35.869398+00:00" +instance: "kb-cron" +--- + +In fluid dynamics, a trochoidal wave or Gerstner wave is an exact solution of the Euler equations for periodic surface gravity waves. It describes a progressive wave of permanent form on the surface of an incompressible fluid of infinite depth. The free surface of this wave solution is an inverted (upside-down) trochoid – with sharper crests and flat troughs. This wave solution was discovered by Gerstner in 1802, and rediscovered independently by Rankine in 1863. +The flow field associated with the trochoidal wave is not irrotational: it has vorticity. The vorticity is of such a specific strength and vertical distribution that the trajectories of the fluid parcels are closed circles. This is in contrast with the usual experimental observation of Stokes drift associated with the wave motion. Also the phase speed is independent of the trochoidal wave's amplitude, unlike other nonlinear wave-theories (like those of the Stokes wave and cnoidal wave) and observations. For these reasons – as well as for the fact that solutions for finite fluid depth are lacking – trochoidal waves are of limited use for engineering applications. +In computer graphics, the rendering of realistic-looking ocean waves can be done by use of so-called Gerstner waves. This is a multi-component and multi-directional extension of the traditional Gerstner wave, often using fast Fourier transforms to make (real-time) animation feasible. + +== Description of classical trochoidal wave == + +Using a Lagrangian specification of the flow field, the motion of fluid parcels is – for a periodic wave on the surface of a fluid layer of infinite depth: + + + + + + + + + X + ( + a + , + b + , + t + ) + + + + = + a + + + + + + e + + k + b + + + k + + + sin + ⁡ + + ( + + k + ( + a + + + c + t + ) + + ) + + , + + + + + Y + ( + a + , + b + , + t + ) + + + + = + b + − + + + + e + + k + b + + + k + + + cos + ⁡ + + ( + + k + ( + a + + + c + t + ) + + ) + + , + + + + + + + {\displaystyle {\begin{aligned}X(a,b,t)&=a+{\frac {e^{kb}}{k}}\sin \left(k(a+ct)\right),\\Y(a,b,t)&=b-{\frac {e^{kb}}{k}}\cos \left(k(a+ct)\right),\end{aligned}}} + + +where + + + + x + = + X + ( + a + , + b + , + t + ) + + + {\displaystyle x=X(a,b,t)} + + and + + + + y + = + Y + ( + a + , + b + , + t + ) + + + {\displaystyle y=Y(a,b,t)} + + are the positions of the fluid parcels in the + + + + ( + x + , + y + ) + + + {\displaystyle (x,y)} + + plane at time + + + + t + + + {\displaystyle t} + +, with + + + + x + + + {\displaystyle x} + + the horizontal coordinate and + + + + y + + + {\displaystyle y} + + the vertical coordinate (positive upward, in the direction opposing gravity). The Lagrangian coordinates + + + + ( + a + , + b + ) + + + {\displaystyle (a,b)} + + label the fluid parcels, with + + + + ( + x + , + y + ) + = + ( + a + , + b + ) + + + {\displaystyle (x,y)=(a,b)} + + the centres of the circular orbits – around which the corresponding fluid parcel moves with constant speed + + + + c + + exp + ⁡ + ( + k + b + ) + . + + + {\displaystyle c\,\exp(kb).} + + Further + + + + k + = + 2 + π + + / + + λ + + + {\textstyle k=2\pi /\lambda } + + is the wavenumber (and + + + + λ + + + {\displaystyle \lambda } + + the wavelength), while + + + + c + + + {\displaystyle c} + + is the phase speed with which the wave propagates in the + + + + x + + + {\displaystyle x} + +-direction. The phase speed satisfies the dispersion relation: + + + + + + c + + 2 + + + = + + + g + k + + + , + + + {\displaystyle c^{2}={\frac {g}{k}},} + + +which is independent of the wave nonlinearity (i.e. does not depend on the wave height + + + + H + + + {\displaystyle H} + +), and this phase speed + + + + c + + + {\displaystyle c} + + the same as for Airy's linear waves in deep water. +The free surface is a line of constant pressure, and is found to correspond with a line + + + + b + = + + b + + s + + + + + {\displaystyle b=b_{s}} + +, where + + + + + b + + s + + + + + {\displaystyle b_{s}} + + is a (nonpositive) constant. For + + + + + b + + s + + + = + 0 + + + {\displaystyle b_{s}=0} + + the highest waves occur, with a cusp-shaped crest. Note that the highest (irrotational) Stokes wave has a crest angle of 120°, instead of the 0° for the rotational trochoidal wave. +The wave height of the trochoidal wave is + + + + H + = + + + 2 + k + + + exp + ⁡ + ( + k + + b + + s + + + ) + . + + + {\textstyle H={\frac {2}{k}}\exp(kb_{s}).} + + The wave is periodic in the + + + + x + + + {\displaystyle x} + +-direction, with wavelength + + + + λ + ; + + + {\displaystyle \lambda ;} + + and also periodic in time with period + + + + T + = + λ + + / + + c + = + + + 2 + π + λ + + / + + g + + + . + + + {\textstyle T=\lambda /c={\sqrt {2\pi \lambda /g}}.} + + +The vorticity + + + + ϖ + + + {\displaystyle \varpi } + + under the trochoidal wave is: + + + + + ϖ + ( + a + , + b + , + t + ) + = + − + + + + 2 + k + c + + e + + 2 + k + b + + + + + 1 + − + + e + + 2 + k + b + + + + + + , + + + {\displaystyle \varpi (a,b,t)=-{\frac {2kce^{2kb}}{1-e^{2kb}}},} + + +varying with Lagrangian elevation + + + + b + + + {\displaystyle b} + + and diminishing rapidly with depth below the free surface. + +== In computer graphics == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Trochoidal_wave-1.md b/data/en.wikipedia.org/wiki/Trochoidal_wave-1.md new file mode 100644 index 000000000..f037cab50 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Trochoidal_wave-1.md @@ -0,0 +1,1097 @@ +--- +title: "Trochoidal wave" +chunk: 2/2 +source: "https://en.wikipedia.org/wiki/Trochoidal_wave" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:35.869398+00:00" +instance: "kb-cron" +--- + +A multi-component and multi-directional extension of the Lagrangian description of the free-surface motion – as used in Gerstner's trochoidal wave – is used in computer graphics for the simulation of ocean waves. For the classical Gerstner wave the fluid motion exactly satisfies the nonlinear, incompressible and inviscid flow equations below the free surface. However, the extended Gerstner waves do in general not satisfy these flow equations exactly (although they satisfy them approximately, i.e. for the linearised Lagrangian description by potential flow). This description of the ocean can be programmed very efficiently by use of the fast Fourier transform (FFT). Moreover, the resulting ocean waves from this process look realistic, as a result of the nonlinear deformation of the free surface (due to the Lagrangian specification of the motion): sharper crests and flatter troughs. +The mathematical description of the free-surface in these Gerstner waves can be as follows: the horizontal coordinates are denoted as + + + + x + + + {\displaystyle x} + + and + + + + z + + + {\displaystyle z} + +, and the vertical coordinate is + + + + y + + + {\displaystyle y} + +. The mean level of the free surface is at + + + + y + = + 0 + + + {\displaystyle y=0} + + and the positive + + + + y + + + {\displaystyle y} + +-direction is upward, opposing the Earth's gravity of strength + + + + g + . + + + {\displaystyle g.} + + The free surface is described parametrically as a function of the parameters + + + + α + + + {\displaystyle \alpha } + + and + + + + β + , + + + {\displaystyle \beta ,} + + as well as of time + + + + t + . + + + {\displaystyle t.} + + The parameters are connected to the mean-surface points + + + + ( + x + , + y + , + z + ) + = + ( + α + , + 0 + , + β + ) + + + {\displaystyle (x,y,z)=(\alpha ,0,\beta )} + + around which the fluid parcels at the wavy surface orbit. The free surface is specified through + + + + x + = + ξ + ( + α + , + β + , + t + ) + , + + + {\displaystyle x=\xi (\alpha ,\beta ,t),} + + + + + + y + = + ζ + ( + α + , + β + , + t + ) + + + {\displaystyle y=\zeta (\alpha ,\beta ,t)} + + and + + + + z + = + η + ( + α + , + β + , + t + ) + + + {\displaystyle z=\eta (\alpha ,\beta ,t)} + + with: + + + + + + + + + ξ + + + + = + α + − + + ∑ + + m + = + 1 + + + M + + + + + + k + + x + , + m + + + + k + + m + + + + + + + + + a + + m + + + + tanh + ⁡ + + ( + + + k + + m + + + + h + + ) + + + + + + sin + ⁡ + + ( + + θ + + m + + + ) + + , + + + + + η + + + + = + β + − + + ∑ + + m + = + 1 + + + M + + + + + + k + + z + , + m + + + + k + + m + + + + + + + + + a + + m + + + + tanh + ⁡ + + ( + + + k + + m + + + + h + + ) + + + + + + sin + ⁡ + + ( + + θ + + m + + + ) + + , + + + + + ζ + + + + = + + ∑ + + m + = + 1 + + + M + + + + a + + m + + + + cos + ⁡ + + ( + + θ + + m + + + ) + + , + + + + + + θ + + m + + + + + + = + + k + + x + , + m + + + + α + + + + k + + z + , + m + + + + β + − + + ω + + m + + + + t + − + + ϕ + + m + + + , + + + + + + + {\displaystyle {\begin{aligned}\xi &=\alpha -\sum _{m=1}^{M}{\frac {k_{x,m}}{k_{m}}}\,{\frac {a_{m}}{\tanh \left(k_{m}\,h\right)}}\,\sin \left(\theta _{m}\right),\\\eta &=\beta -\sum _{m=1}^{M}{\frac {k_{z,m}}{k_{m}}}\,{\frac {a_{m}}{\tanh \left(k_{m}\,h\right)}}\,\sin \left(\theta _{m}\right),\\\zeta &=\sum _{m=1}^{M}a_{m}\,\cos \left(\theta _{m}\right),\\\theta _{m}&=k_{x,m}\,\alpha +k_{z,m}\,\beta -\omega _{m}\,t-\phi _{m},\end{aligned}}} + + +where + + + + tanh + + + {\displaystyle \tanh } + + is the hyperbolic tangent function, + + + + M + + + {\displaystyle M} + + is the number of wave components considered, + + + + + a + + m + + + + + {\displaystyle a_{m}} + + is the amplitude of component + + + + + m + = + 1 + … + M + + + + {\displaystyle {m=1\dots M}} + + and + + + + + ϕ + + m + + + + + {\displaystyle \phi _{m}} + + its phase. Further + + + + + k + + m + + + = + + + + + k + + x + , + m + + + 2 + + + + + + k + + z + , + m + + + 2 + + + + + + + + {\textstyle k_{m}={\sqrt {\scriptstyle k_{x,m}^{2}+k_{z,m}^{2}}}} + + is its wavenumber and + + + + + ω + + m + + + + + {\displaystyle \omega _{m}} + + its angular frequency. The latter two, + + + + + k + + m + + + + + {\displaystyle k_{m}} + + and + + + + + ω + + m + + + , + + + {\displaystyle \omega _{m},} + + can not be chosen independently but are related through the dispersion relation: + + + + + + ω + + m + + + 2 + + + = + g + + + k + + m + + + tanh + ⁡ + + ( + + + k + + m + + + + h + + ) + + , + + + {\displaystyle \omega _{m}^{2}=g\,k_{m}\tanh \left(k_{m}\,h\right),} + + +with + + + + h + + + {\displaystyle h} + + the mean water depth. In deep water ( + + + + h + → + ∞ + + + {\displaystyle h\to \infty } + +) the hyperbolic tangent goes to one: + + + + + tanh + ⁡ + ( + + k + + m + + + + h + ) + → + 1. + + + + {\displaystyle {\tanh(k_{m}\,h)\to 1.}} + + The components + + + + + k + + x + , + m + + + + + {\displaystyle k_{x,m}} + + and + + + + + k + + z + , + m + + + + + {\displaystyle k_{z,m}} + + of the horizontal wavenumber vector + + + + + + k + + + m + + + + + {\displaystyle {\boldsymbol {k}}_{m}} + + determine the wave propagation direction of component + + + + m + . + + + {\displaystyle m.} + + +The choice of the various parameters + + + + + a + + m + + + , + + k + + x + , + m + + + , + + k + + z + , + m + + + + + {\displaystyle a_{m},k_{x,m},k_{z,m}} + + and + + + + + ϕ + + m + + + + + {\displaystyle \phi _{m}} + + for + + + + m + = + 1 + , + … + , + M + , + + + {\displaystyle m=1,\dots ,M,} + + and a certain mean depth + + + + h + + + {\displaystyle h} + + determines the form of the ocean surface. A clever choice is needed in order to exploit the possibility of fast computation by means of the FFT. See e.g. Tessendorf (2001) for a description how to do this. Most often, the wavenumbers are chosen on a regular grid in + + + + ( + + k + + x + + + , + + k + + z + + + ) + + + {\displaystyle (k_{x},k_{z})} + +-space. Thereafter, the amplitudes + + + + + a + + m + + + + + {\displaystyle a_{m}} + + and phases + + + + + ϕ + + m + + + + + {\displaystyle \phi _{m}} + + are chosen randomly in accord with the variance-density spectrum of a certain desired sea state. Finally, by FFT, the ocean surface can be constructed in such a way that it is periodic both in space and time, enabling tiling – creating periodicity in time by slightly shifting the frequencies + + + + + ω + + m + + + + + {\displaystyle \omega _{m}} + + such that + + + + + ω + + m + + + = + m + + Δ + ω + + + {\displaystyle \omega _{m}=m\,\Delta \omega } + + for + + + + m + = + 1 + , + … + , + M + . + + + {\displaystyle m=1,\dots ,M.} + + +In rendering, also the normal vector + + + + + n + + + + {\displaystyle {\boldsymbol {n}}} + + to the surface is often needed. These can be computed using the cross product ( + + + + × + + + {\displaystyle \times } + +) as: + + + + + + n + + = + + + + ∂ + + s + + + + ∂ + α + + + + × + + + + ∂ + + s + + + + ∂ + β + + + + + + with + + + + s + + ( + α + , + β + , + t + ) + = + + + ( + + + + ξ + ( + α + , + β + , + t + ) + + + + + ζ + ( + α + , + β + , + t + ) + + + + + η + ( + α + , + β + , + t + ) + + + + ) + + + . + + + {\displaystyle {\boldsymbol {n}}={\frac {\partial {\boldsymbol {s}}}{\partial \alpha }}\times {\frac {\partial {\boldsymbol {s}}}{\partial \beta }}\quad {\text{with}}\quad {\boldsymbol {s}}(\alpha ,\beta ,t)={\begin{pmatrix}\xi (\alpha ,\beta ,t)\\\zeta (\alpha ,\beta ,t)\\\eta (\alpha ,\beta ,t)\end{pmatrix}}.} + + +The unit normal vector then is + + + + + + e + + + n + + + = + + n + + + / + + ‖ + + n + + ‖ + , + + + {\displaystyle {\boldsymbol {e}}_{n}={\boldsymbol {n}}/\|{\boldsymbol {n}}\|,} + + with + + + + ‖ + + n + + ‖ + + + {\displaystyle \|{\boldsymbol {n}}\|} + + the norm of + + + + + n + + . + + + {\displaystyle {\boldsymbol {n}}.} + + +== Notes == + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Uncertainty_and_Quality_in_Science_for_Policy-0.md b/data/en.wikipedia.org/wiki/Uncertainty_and_Quality_in_Science_for_Policy-0.md new file mode 100644 index 000000000..f7a926ba2 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Uncertainty_and_Quality_in_Science_for_Policy-0.md @@ -0,0 +1,24 @@ +--- +title: "Uncertainty and Quality in Science for Policy" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Uncertainty_and_Quality_in_Science_for_Policy" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:53.758566+00:00" +instance: "kb-cron" +--- + +Uncertainty and Quality in Science for Policy is a 1990 book by Silvio Funtowicz and Jerome Ravetz, in which the authors explain the notational system NUSAP (numeral, unit, spread, assessment, pedigree) and applies it to several examples from the environmental sciences. The work is considered foundational to the development of post-normal science. + + +== Content == +This work, written by the fathers of post-normal science, discusses the use of science for policy and its problems. The book emphasizes the need for craft skills with numbers – not only in statistics but also in cost-benefit analysis, and on the need of specific skills for policy-related research. It introduces for the first time NUSAP, a new notational system for the management of uncertainty and quality in quantitative information, and presents examples of its application to radiological hazards, the valuation of ecosystems, and to energy technologies. +This work is one of the most quoted in the field of science and technology studies - see also Science, technology and society (STS), especially relation to the issue of "democratization of expertise". For Carrozza (2015) and Gooday (2006) this work, together with Ravetz's Scientific Knowledge and Its Social Problems (1971) constitutes the bedrock for the conceptualization of post-normal science in the first half of the 1990s. + + +== References == + + +== External links == +Related material +Book's page at Google books \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Unsavory_Truth-0.md b/data/en.wikipedia.org/wiki/Unsavory_Truth-0.md new file mode 100644 index 000000000..d17b10155 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Unsavory_Truth-0.md @@ -0,0 +1,46 @@ +--- +title: "Unsavory Truth" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Unsavory_Truth" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:54.902622+00:00" +instance: "kb-cron" +--- + +Unsavory Truth: How Food Companies Skew the Science of What We Eat is a 2018 book by American academic Marion Nestle. +In the book, Nestle heavily criticizes research funded by food companies as motivated by increasing profits through marketing. + + +== Background == +Public awareness of nutrition has risen in recent decades. Companies have been funding nutrition research since at least the 1940s, and until 1990 disclosure policies of conflict of interest for academics were voluntary. +Unsavory Truth was released while potential and actual conflicts of interest in research were being subject to increased attention, particularly around pharmaceutical companies, with relatively limited attention on food. The book was released as Coca-Cola was publicly criticized for pressuring journalists writing about Coca-Cola's health effects, and for its funding of health science for its own gain. + + +=== Marion Nestle === +Nestle has researched food producers for over two decades, publishing works on specific types of foods rather than the entire industry. Her earlier publications included Food Politics (2002) and Safe Food (2003). +In 2016, an email from an Australian public relations company warning Coca-Cola to monitor Nestle's comments was released in the 2016 Democratic National Committee email leak. + + +== Content == +The book covers research into subjects including candy, sweeteners, meat and dairy products, spending an entire chapter discussing Coca-Cola's initially undisclosed funding of the Global Energy Balance Network. +The book highlights how university scientists reliance on research funding for promotions, and offers nutrition scientists advice for navigating conflicts of interest. She says that psychological research has shown effects of funding on scientists can be unconscious and unintentional, and that positive findings are rarely due to fraud. Nestle says that advisory bodies such as the World Health Organization and academic societies such as the American Society for Nutrition have also been co-opted by companies. +Nestle offers solutions for food company's influence on research, while recognizing that these are unrealistic. She is critical of transparency being the entire solution and argues for citizens to be more engaged. + + +== Reception == +Reviews praised Unsavory Truth for its convincing argument and its documentation of evidence. Reviewers praised the writing, with Rebecca Garofano writing that "Nestle’s writing is clear, accessible, and to the point." +Felicity Lawrence, reviewing Unsavory Truth in Nature wrote that she believed that Nestle is too generous in "exonerating" scientists for publishing misleading science due to unconscious bias. +Some industry-funded scientists responded to Nestle's argument by claiming conflict of interest disclosure requirements were an attack on their integrity. Some argued against disclosure by saying that as all scientists are biased, financial conflicts of interest should not be considered a problem. According to reviewer Garofano, the nutrition science field's response to the book appeared to be "almost complete silence." + + +== References == + + +== Sources == + + +=== Journal articles === + + +=== News and magazine articles === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Water_mass-0.md b/data/en.wikipedia.org/wiki/Water_mass-0.md new file mode 100644 index 000000000..2a0155b9e --- /dev/null +++ b/data/en.wikipedia.org/wiki/Water_mass-0.md @@ -0,0 +1,59 @@ +--- +title: "Water mass" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Water_mass" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:37.092878+00:00" +instance: "kb-cron" +--- + +An oceanographic water mass is an identifiable body of water with a common formation history which has physical properties distinct from surrounding water. Properties include temperature, salinity, chemical - isotopic ratios, and other physical quantities which are conservative flow tracers. Water mass is also identified by its non-conservative flow tracers such as silicate, nitrate, oxygen, and phosphate. +Water masses are generally distinguished not only by their respective tracers but also by their location in the Worlds' oceans. Water masses are also distinguished by their vertical position so that there are surface water masses, intermediate water masses and deep water masses. + + +== Global water masses == +Common water masses in the world ocean are: + +Antarctic Bottom Water (AABW): Antarctic Bottom Water is a very important water mass. Antarctic Bottom Water is the left over part when sea ice is being made. It is very cold but, not quite freezing so the water moves down and along the ocean floor. +North Atlantic Deep Water (NADW) +Circumpolar Deep Water (CDW) +Antarctic Intermediate Water (AAIW) +Subantarctic Mode Water (SAMW) +Arctic Intermediate Water (AIW) +North Pacific Intermediate Water (NPIW) +The central waters of various oceanic basins +Various ocean surface waters. + + +== Characteristics of water masses == +Although there are many types of water masses, they all share characteristics. Water Masses are formed from regions of water having different temperatures. When ice is being formed in a cold climate like Antarctica, the cold temperatures separate the molecular bonds of the water causing it to become less dense. However, because water increases its volume by about 9% when frozen, this makes the ice less dense than the water which is why glaciers float. This also in turn causes the salinity of the water to decrease. The salinity of the water makes water freeze at lower temperatures than freshwater. Freshwater freezes at the standard 0 °C (32 °F), while saltwater freezes at an average of -2 °C (28.4 °F). + + +== Water mass classification == + + +=== Temperature and salinity diagram === +The best method of classifying a water mass is through using a T-S diagram. In the diagram pictured at the top, it categorises a water mass by the temperature and salinity of the water and is represented by a single point. However, water masses are not constant. Throughout time climates can change, seasons can drag out, or there could be less rainfall meaning that the water masses might change in temperature or salinity. To have a complete water mass classification, it requires the water type of the source and the standard deviations of the temperature and salinity. It can take many years to establish the standard deviations of the water mass and requires constant surveillance. Once all of the necessary measures are completed, the data will now determine what the current density of the water is and help further classify the water mass. + + +== See also == +Atlantic meridional overturning circulation +Ocean current +Open ocean convection +Ocean stratification +Temperature-salinity diagram +Thermohaline circulation +Upwelling + + +== References == + +"Water masses". www.mt-oceanography.info. Retrieved 2020-12-09. +Emery, W. J.; Meincke, J. (1986). "Global water masses-summary and review" (PDF). Oceanologica Acta. 9 (4): 383–391. Retrieved 16 October 2016. +Bhutia, T. K. Water mass. https://www.britannica.com/science/water-mass. +Toste Tanhua, Mian Liu. “Characteristics of Water Masses in the Atlantic Ocean Based on GLODAPv2 Data .” Characteristics of Water Masses in the Atlantic Ocean Based on GLODAPv2 Data, 2019, os.copernicus.org/preprints/os-2018-139/os-2018-139.pdf. + + +== External links == +Glossary of Physical Oceanography and Related Disciplines water mass \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Watts_Up_With_That-0.md b/data/en.wikipedia.org/wiki/Watts_Up_With_That-0.md new file mode 100644 index 000000000..45009911f --- /dev/null +++ b/data/en.wikipedia.org/wiki/Watts_Up_With_That-0.md @@ -0,0 +1,32 @@ +--- +title: "Watts Up With That?" +chunk: 1/2 +source: "https://en.wikipedia.org/wiki/Watts_Up_With_That?" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:30.032511+00:00" +instance: "kb-cron" +--- + +Watts Up With That? (WUWT) is a blog promoting climate change denial that was created by Anthony Watts in 2006. +The blog predominantly discusses climate issues with a focus on anthropogenic climate change, generally accommodating beliefs that are in opposition to the scientific consensus on climate change. Contributors include Christopher Monckton and Fred Singer as guest authors. In November 2009, the blog was one of the first websites to publish emails and documents from the Climatic Research Unit controversy, and a driving force behind its coverage. +In the early months of 2010, it was reported the site might be "the most read climate blog in the world," and in 2013 Michael E. Mann referred to it as the leading climate change denial blog. + +== Content == +Watts Up With That features material disputing the scientific consensus on climate change, including claims the human role in global warming is insignificant and carbon dioxide is not a driving force of warming. It has hosted several contributors, such as Christopher Monckton and Fred Singer, in addition to Watts. It is among the most prominent climate change denial blogs, and is described by climatologist Michael E. Mann as the most popular, having surpassed Climate Audit. Columbia Journalism School writer Curtis Brainard has written that "scientists have repeatedly criticized [Watts] for misleading readers on subjects such as the reliability of the U.S. surface temperature record." + +== Temperature records == +In 2007 WUWT readers alerted Stephen McIntyre to a discrepancy in temperature records published by the Goddard Institute for Space Studies (GISS) based on data from United States Historical Climate Network. In August 2007, McIntyre notified GISS about the problematic numbers, which GISS acknowledged and promptly corrected. The change did not affect global temperature trends, but did have the marginal effect of changing the hottest year on record for the contiguous United States to 1934, rather than 1998 as had previously been shown. In a formal acknowledgement, GISS stated that the minor data processing error had only affected the years after 2000, and noted that the contiguous United States represents only 1.6% of the Earth's surface. The result was a statistical tie between the years 1934, 1998 and 2005 as the warmest years to date for these U.S. states, with 1934 warmest by only around 0.01 °C which was well within the margin of uncertainty. + +== Involvement in the Climatic Research Unit email controversy == + +In 2009, Watts Up With That was involved in popularizing the Climatic Research Unit email controversy, wherein emails of several climatologists were published by a hacker. The story was initially broken on WUWT and two other blogs when the hacker posted a link to a Russian server containing emails and documents from the Climate Research Unit of the University of East Anglia, and subsequently reproduced on the WUWT blog. Because of WUWT's high traffic count, this was the catalyst which broke the story to the media. The term "Climategate" was originally coined by a commenter in a post on WUWT. +Watts argued that the emails showed the scientists were manipulating data, and while a series of independent investigations cleared the scientists of any wrongdoing, public accusations resulting from the event continued for years. The scientific consensus that global warming is occurring as a result of human activity remained unchanged throughout the investigations, however, the reports may have decreased public confidence in climate scientists and the IPCC, and conclusively altered the Copenhagen negotiations that year. +In a 2010 interview with the Financial Times, Watts said that his blog had become "busier than ever" after the incident and that traffic to the site had tripled. + +== Reception == +According to Alexa Internet statistical analysis, Watts Up With That? is ranked No. 14,882 in the U.S. and No. 40,090 world-wide in 2015. It is reported to receive between half a million and 2 million visits per month between 2010 and 2014. It was described by climatologist Michael E. Mann in The Hockey Stick and the Climate Wars as "the leading climate change denial blog," having surpassed Climate Audit in popularity. +Watts's blog has been criticized for inaccuracy. The Guardian columnist George Monbiot described WUWT as "highly partisan and untrustworthy". Leo Hickman, at The Guardian's Environment Blog, also criticized Watts's blog, stating that Watts "risks polluting his legitimate scepticism about the scientific processes and methodologies underpinning climate science with his accompanying politicised commentary." +Between 2008 and 2013, WUWT asked its readers to vote in several internet voting-based awards, and it won "best science blog" and "best blog" from the Bloggies and the conservative Wizbang Weblog Awards. In 2013, Leo Hickman wrote in The Guardian Environment Blog that 13 of the 17 blogs nominated for the Science or Technology category for the Bloggies "were either run by climate sceptics, or popular with climate sceptics". The Bloggies founder acknowledged in 2013 that "climate sceptic" bloggers had influenced voting. He said "Unfortunately, I have no good solution for it, since they follow proper voting procedures and legitimate science blogs don't want to make an effort to compete." He discontinued the science category in 2014. WUWT did not win "Best Topical Weblog of the Year" 2014 as Watts claimed, but did enter the Hall of Fame that year. + +== Notes == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Watts_Up_With_That-1.md b/data/en.wikipedia.org/wiki/Watts_Up_With_That-1.md new file mode 100644 index 000000000..29fd8fc08 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Watts_Up_With_That-1.md @@ -0,0 +1,41 @@ +--- +title: "Watts Up With That?" +chunk: 2/2 +source: "https://en.wikipedia.org/wiki/Watts_Up_With_That?" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:30.032511+00:00" +instance: "kb-cron" +--- + +== References == +Anders, Hansen; Cox, Robert (2015). The Routledge Handbook of Environment and Communication. Routledge. ISBN 978-1134521319. +Anshelm, Jonas; Hultman, Martin (2014). Discourses of Global Climate Change: Apocalyptic Framing and Political Antagonisms. Routledge. ISBN 978-1317671060. +Brainard, Curtis (2015). Hansen, Anders; Cox, Robert (eds.). The Routledge Handbook of Environment and Communication. Routledge. ISBN 978-1-134-52131-9. +Dunlap, Riley; McCright, Aaron (2011). "Organised Climate Change Denial". In Dryzek, John S.; Norgaard, Richard B.; Schlosberg, David (eds.). The Oxford Handbook of Climate Change and Society. Oxford University Press. ISBN 978-0199566600. +Farmer, Thomas G.; Cook, John (2013). Climate Change Science: A Modern Synthesis: Volume 1-The Physical Climate. Springer Science & Business Media. ISBN 9789400757578. +Grant, John (2011). Denying Science: Conspiracy Theories, Media Distortions, and the War Against Reality. Prometheus Books. ISBN 978-1616144005. Retrieved 26 May 2015. +Kirilenko, Andrei; Stepchenkova, Svetlana (2014). "Public microblogging on climate change: One year of Twitter worldwide". Global Environmental Change. 26: 171–182. doi:10.1016/j.gloenvcha.2014.02.008. +Mann, Michael (1 October 2013). The Hockey Stick and the Climate Wars: Dispatches from the Front Lines. Columbia University Press. ISBN 978-0231152556. +Manne, Robert (August 2012). "A dark victory: How vested interests defeated climate science". The Monthly. pp. 22–29. +Mooney, Chris; Kirshenbaum, Sheril (2010). Summary of Unscientific America: How Scientific Illiteracy Threatens Our Future. Basic Books. ISBN 978-0465019175. +Phelan, Sean (2014). Neoliberalism, Media and the Political. Palgrave Macmillan. ISBN 978-1137308368. +Schneider, Birgit; Nocke, Thomas (2014). Image Politics of Climate Change: Visualizations, Imaginations, Documentations. transcript Verlag. ISBN 9783839426104. + +== Further reading == +Black, Brian C.; Hassenzahl, David M.; Stephens, Jennie C.; Weisel, Gary; Gift, Nancy (2013). Climate Change: An Encyclopedia of Science and History. ABC-CLIO. ISBN 978-1598847628. +Farmer, Thomas G. (2014). Modern Climate Change Science: An Overview of Today's Climate Change Science. Springer. ISBN 978-3319092225. +Henson, Robert (2011). The Rough Guide to Climate Change. Penguin. ISBN 978-1405388672. +IPCC (2007). "IPCC Fourth Assessment Report: Climate Change 2007". Retrieved 26 May 2015. +IPCC (2007). Susan Solomon (ed.). Climate Change 2007 - The Physical Science Basis: Working Group I Contribution to the Fourth Assessment Report of the IPCC. Cambridge University Press. ISBN 978-0521705967. +ISSC; UNESC (2013). World Social Science Report 2013 Changing Global Environments: Changing Global Environments. OECD Publishing. ISBN 978-9264203419. +Menne, Mathew J.; Williams, Claude N.; Palecki, Michael A. (2010). "On the reliability of the U.S. surface temperature record". J. Geophys. Res. 115 (D11). Bibcode:2010JGRD..11511108M. doi:10.1029/2009JD013094. +National Research Council (2010). Advancing the Science of Climate Change. Washington, D.C.: The National Academies Press. ISBN 978-0-309-14588-6. +Powell, James Lawrence (2012). The Inquisition of Climate Science. Columbia University Press. ISBN 978-0231157193. +USGCRP (2009). Karl, T.R.; Melillo. J.; Peterson, T.; Hassol, S.J. (eds.). Global Climate Change Impacts in the United States. Cambridge University Press. ISBN 978-0-521-14407-0. Archived from the original on 2010-04-06. Retrieved 2015-06-24. +Washington, Haydn (2013). Climate Change Denial: Heads in the Sand. Routledge. ISBN 978-1136530050. +Weart, Spencer. "The Discovery of Global Warming". American Institute of Physics. Archived from the original on 22 September 2020. Retrieved 26 May 2015. + +== External links == + +Watts Up With That?, official site. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Wave_shoaling-0.md b/data/en.wikipedia.org/wiki/Wave_shoaling-0.md new file mode 100644 index 000000000..b0ca4c691 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Wave_shoaling-0.md @@ -0,0 +1,578 @@ +--- +title: "Wave shoaling" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Wave_shoaling" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:38.331621+00:00" +instance: "kb-cron" +--- + +In fluid dynamics, wave shoaling is the effect by which surface waves, entering shallower water, increase in wave height. It is caused by the fact that the group velocity, which is also the wave-energy transport velocity, decreases with water depth. Under stationary conditions, a decrease in transport speed must be compensated by an increase in energy density in order to maintain a constant energy flux. Shoaling waves will also exhibit a reduction in wavelength while the frequency remains constant. +In other words, as the waves approach the shore and the water gets shallower, the waves get taller, slow down, and get closer together. +Particularly in a waterbody shallow enough for its surface to be affected by its bottom and where depth contours parallel the shore, a wave packet that does dissipate its energy by breaking will rise in height as it enters yet shallower water. This is plainly evident for tsunamis as they wax in height when approaching a coastline, often with devastating results. + + +== Overview == +Waves nearing the coast experience changes in wave height through different effects. Some of the important wave processes are refraction, diffraction, reflection, wave breaking, wave–current interaction, friction, wave growth due to the wind, and wave shoaling. In the absence of the other effects, wave shoaling is the change of wave height that occurs solely by changes in mean water depth – without alterations in wave propagation direction or energy dissipation. Pure wave shoaling occurs for long-crested waves propagating perpendicular to the parallel depth contour lines of a mildly sloping sea-bed. Then the wave height + + + + H + + + {\displaystyle H} + + at a certain location can be expressed as: + + + + + H + = + + K + + S + + + + + H + + 0 + + + , + + + {\displaystyle H=K_{S}\;H_{0},} + + +with + + + + + K + + S + + + + + {\displaystyle K_{S}} + + the shoaling coefficient and + + + + + H + + 0 + + + + + {\displaystyle H_{0}} + + the wave height in deep water. The shoaling coefficient + + + + + K + + S + + + + + {\displaystyle K_{S}} + + depends on the local water depth + + + + h + + + {\displaystyle h} + + and the wave frequency + + + + f + + + {\displaystyle f} + + (or equivalently on + + + + h + + + {\displaystyle h} + + and the wave period + + + + T + = + 1 + + / + + f + + + {\displaystyle T=1/f} + +). Deep water means that the waves are (hardly) affected by the sea bed, which occurs when the depth + + + + h + + + {\displaystyle h} + + is larger than about half the deep-water wavelength + + + + + L + + 0 + + + = + g + + T + + 2 + + + + / + + ( + 2 + π + ) + . + + + {\displaystyle L_{0}=gT^{2}/(2\pi ).} + + + + +== Physics == + +For non-breaking waves, the energy flux associated with the wave motion, which is the product of the wave energy density with the group velocity, between two wave rays is a conserved quantity (i.e. a constant when following the energy of a wave packet from one location to another). Under stationary conditions the total energy transport must be constant along the wave ray – as first shown by William Burnside in 1915. +For waves affected by refraction and shoaling (i.e. within the geometric optics approximation), the rate of change of the wave energy transport is: + + + + + + + d + + d + s + + + + ( + b + + c + + g + + + E + ) + = + 0 + , + + + {\displaystyle {\frac {d}{ds}}(bc_{g}E)=0,} + + +where + + + + s + + + {\displaystyle s} + + is the co-ordinate along the wave ray and + + + + b + + c + + g + + + E + + + {\displaystyle bc_{g}E} + + is the energy flux per unit crest length. A decrease in group speed + + + + + c + + g + + + + + {\displaystyle c_{g}} + + and distance between the wave rays + + + + b + + + {\displaystyle b} + + must be compensated by an increase in energy density + + + + E + + + {\displaystyle E} + +. This can be formulated as a shoaling coefficient relative to the wave height in deep water. +For shallow water, when the wavelength is much larger than the water depth – in case of a constant ray distance + + + + b + + + {\displaystyle b} + + (i.e. perpendicular wave incidence on a coast with parallel depth contours) – wave shoaling satisfies Green's law: + + + + + H + + + + h + + 4 + + + + = + + constant + + , + + + {\displaystyle H\,{\sqrt[{4}]{h}}={\text{constant}},} + + +with + + + + h + + + {\displaystyle h} + + the mean water depth, + + + + H + + + {\displaystyle H} + + the wave height and + + + + + + h + + 4 + + + + + + {\displaystyle {\sqrt[{4}]{h}}} + + the fourth root of + + + + h + . + + + {\displaystyle h.} + + + +== Water wave refraction == +Following Phillips (1977) and Mei (1989), denote the phase of a wave ray as + + + + + S + = + S + ( + + x + + , + t + ) + , + + 0 + ≤ + S + < + 2 + π + + + {\displaystyle S=S(\mathbf {x} ,t),\qquad 0\leq S<2\pi } + +. +The local wave number vector is the gradient of the phase function, + + + + + + k + + = + ∇ + S + + + {\displaystyle \mathbf {k} =\nabla S} + +, +and the angular frequency is proportional to its local rate of change, + + + + + ω + = + − + ∂ + S + + / + + ∂ + t + + + {\displaystyle \omega =-\partial S/\partial t} + +. +The equations above and the following equation have direct analogues in Hamiltonian mechanics and the Hamilton-Jacobi theory of classical mechanics. Simplifying to one dimension and cross-differentiating it is now easily seen that the above definitions indicate simply that the rate of change of wavenumber is balanced by the convergence of the frequency along a ray; + + + + + + + + ∂ + k + + + ∂ + t + + + + + + + + + ∂ + ω + + + ∂ + x + + + + = + 0 + + + {\displaystyle {\frac {\partial k}{\partial t}}+{\frac {\partial \omega }{\partial x}}=0} + +. +Assuming stationary conditions ( + + + + ∂ + + / + + ∂ + t + = + 0 + + + {\displaystyle \partial /\partial t=0} + +), this implies that wave crests are conserved and the frequency must remain constant along a wave ray as + + + + ∂ + ω + + / + + ∂ + x + = + 0 + + + {\displaystyle \partial \omega /\partial x=0} + +. +As waves enter shallower waters, the decrease in group velocity caused by the reduction in water depth leads to a reduction in wave length + + + + λ + = + 2 + π + + / + + k + + + {\displaystyle \lambda =2\pi /k} + + because the nondispersive shallow water limit of the dispersion relation for the wave phase speed, + + + + + ω + + / + + k + ≡ + c + = + + + g + h + + + + + {\displaystyle \omega /k\equiv c={\sqrt {gh}}} + + +dictates that + + + + + k + = + ω + + / + + + + g + h + + + + + {\displaystyle k=\omega /{\sqrt {gh}}} + +, +i.e., a steady increase in k (decrease in + + + + λ + + + {\displaystyle \lambda } + +) as the phase speed decreases under constant + + + + ω + + + {\displaystyle \omega } + +. + + +== See also == + + +== Notes == + + +== External links == + +Wave transformation at Coastal Wiki \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Wind-wave_dissipation-0.md b/data/en.wikipedia.org/wiki/Wind-wave_dissipation-0.md new file mode 100644 index 000000000..c6109e162 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Wind-wave_dissipation-0.md @@ -0,0 +1,49 @@ +--- +title: "Wind-wave dissipation" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Wind-wave_dissipation" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:42.501498+00:00" +instance: "kb-cron" +--- + +Wind-wave dissipation or "swell dissipation" is process in which a wave generated via a weather system loses its mechanical energy transferred from the atmosphere via wind. Wind waves, as their name suggests, are generated by wind transferring energy from the atmosphere to the ocean's surface, capillary gravity waves play an essential role in this effect, "wind waves" or "swell" are also known as surface gravity waves. + + +== General physics and theory == +The process of wind-wave dissipation can be explained by applying energy spectrum theory in a similar manner as for the formation of wind-waves (generally assuming spectral dissipation is a function of wave spectrum). However, although even some of recent innovative improvements for field observations (such as Banner & Babanin et al. ) have contributed to solve the riddles of wave breaking behaviors, unfortunately there hasn't been a clear understanding for exact theories of the wind wave dissipation process still yet because of its non-linear behaviors. +By past and present observations and derived theories, the physics of the ocean-wave dissipation can be categorized by its passing regions along to water depth. In deep water, wave dissipation occurs by the actions of friction or drag forces such as opposite-directed winds or viscous forces generated by turbulent flows—usually nonlinear forces. In shallow water, the behaviors of wave dissipations are mostly types of shore wave breaking (see Types of wave breaking). +Some of simple general descriptions of wind-wave dissipation (defined by Luigi Cavaleri et al. ) were proposed when we consider only ocean surface waves such as wind waves. By means of the simple, the interactions of waves with the vertical structure of the upper layers of the ocean are ignored for simplified theory in many proposed mechanisms. + + +== Sources of wind-wave dissipation == +In general understanding, the physics of wave dissipation can be categorized by considering with its dissipation sources, such as 1) wave breaking 2) wave–turbulence interaction 3) wave–wave modulation respectively. (descriptions below of this chapter also follow the reference ) +1) dissipation by "wave breaking" +Wind-wave breaking at coastal area is a major source of the wind-wave dissipation. The wind waves lose their energy to the shore or sometimes back to the ocean when those break at the shore. (see more explains -> “Ocean surface wave breaking”) +2) dissipation by "wave–turbulence interaction" +The turbulent wind flows and viscous eddies inside waves can both affect wave dissipation. In the very early understandings, the viscosity could barely affect the wind waves, so that the dissipation of the swells by viscosity was also barely considered. However, recent weather forecasting models begin considering “wave-turbulence interaction” for the wave modeling. It is still arguable how much the turbulent-induced dissipations contribute to change the whole wave profiles, but the ideas of wave-turbulence interaction for surface viscous layers and wave bottom boundary layers are recently accepted. +3) dissipation by "wave-wave modulation" +Wave–wave interactions can affect to the wave dissipation. In the early eras, the ideas that a short wave breaking can take energy from the long waves through the modulation were proposed by Phillips (1963), and Longuett-Higgins (1969) as well. These ideas had been debated (new results that the dissipations by interactions between wave modulations should be much weaker than the theory's of Phillips) by Hasselmann's works (1971), but in the recent understanding, the dissipations of these cases are typically little stronger than the dissipation by “wave-turbulence interactions” when the reasonable modulation transfer functions implemented. Most cases of the swell dissipations are due to this dissipation type. + + +== Ocean-surface wave breaking == +When wind waves approach to coast area from deep water, the waves change their heights and lengths. The wave height becomes higher and the wavelength becomes shorter as the wave velocity is slowed when ocean waves approach to the shore. If the water depth is sufficiently shallow, the wave crest become steeper and the trough gets broader and shallower; finally, the ocean waves break at the shore. The motions of wave breaking are different with along to the steepness of shores and waves, and can be categorized by below three types. +• Spilling breaker +With lower shore slope, the waves lose energy slowly as approaching to the shore. The waves spill sea water down the front of the waves when those are breaking. + +• Plunging breaker +With moderately steep shore slope, the wave loses energy quickly. If the shore slope is steep enough, the crest of wave moves faster than the trough. The crest curls over front of the wave, and after the crest plunges sea water to the trough. (Plunging breakers are good for surfing) +• Surging breaker +With highly steep shore slope (for extreme steepness, such as seawalls), if the shore steepness is very high, the waves can't reach to the critical steepness to break. The waves climb along through the shore slope, and release energy to the backward from the shore. It never shows white-cap breaks, but for extreme steepness case, such as seawall, the waves break with white-foams. + + +== See also == +Dispersion (water waves) + + +== External links == +Breaking and dissipation of ocean surface waves – Alexander V. Babanin + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Wind_generated_current-0.md b/data/en.wikipedia.org/wiki/Wind_generated_current-0.md new file mode 100644 index 000000000..2374cf214 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Wind_generated_current-0.md @@ -0,0 +1,32 @@ +--- +title: "Wind generated current" +chunk: 1/2 +source: "https://en.wikipedia.org/wiki/Wind_generated_current" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:39.758432+00:00" +instance: "kb-cron" +--- + +A Wind generated current is a flow in a body of water that is generated by wind friction on its surface. Wind can generate surface currents on water bodies of any size. The depth and strength of the current depend on the wind strength and duration, and on friction and viscosity losses, but are limited to about 400 m depth by the mechanism, and to lesser depths where the water is shallower. The direction of flow is influenced by the Coriolis effect, and is offset to the right of the wind direction in the Northern Hemisphere, and to the left in the Southern Hemisphere. A wind current can induce secondary water flow in the form of upwelling and downwelling, geostrophic flow, and western boundary currents. + +== Mechanism == +Friction between wind and the upper surface of a body of water will drag the water surface along with the wind The surface layer will exert viscous drag on the water just below, which will transfer some of the momentum. This process continues downward, with a continuous reduction in speed of flow with increasing depth as the energy is dissipated. The inertial effect of planetary rotation causes an offset of flow direction with increasing depth to the right in the northern hemisphere and to the left in the southern hemisphere. The mechanism of deflection is called the Coriolis effect, and the variation of flow velocity with depth is called an Ekman spiral. The effect varies with latitude, being very weak at the equator and increasing in strength with latitude. The resultant flow of water caused by this mechanism is known as Ekman transport. +A steady wind blowing across a long fetch in deep water for long enough to establish a steady state flow causes the surface water to move at 45° to the wind direction. The variation in flow direction with depth has the water moving perpendicular to wind direction by about 100 to 150 m depth, and flow speed drops to about 4% of surface flow speed by the depth of about 330 to 400 m where the flow direction is opposite to wind direction, below which the effect of wind on the current is considered negligible. The net flow of water over the effective thickness of the current in these conditions is perpendicular to wind direction. Consistent prevailing winds set up persistent circulating surface currents in both hemispheres, and where the current is bounded by continental land masses, the resulting gyres are restricted in longitudinal extent. Seasonal and local winds cause smaller scale and generally transient currents, which dissipate after the driving winds die down. +Real conditions often differ, as wind strength and direction vary, and the depth may not be sufficient for the full spiral to develop, so that the angle between wind direction and surface-water movement can be as small as 15°. In deeper water, the angle increases and approaches 45°. A stable pycnocline can inhibit transfer of kinetic energy to deeper waters, providing a depth limit for surface currents. +The net inward shallow water flow in a gyre causes the surface level to gradually slope upwards towards the centre. This induces a horizontal pressure gradient which leads to a balancing geostrophic flow. + +=== Boundary currents === + +Boundary currents are ocean currents with dynamics determined by the presence of a coastline, and fall into two distinct categories: +Eastern boundary currents are relatively shallow, broad and slow-flowing currents on the eastern side of oceanic basins along the western coasts of continents. Subtropical eastern boundary currents flow equatorward, transporting cold water from higher latitudes to lower latitudes; examples include the Benguela Current, the Canary Current, the Humboldt Current, and the California Current. Coastal upwelling caused by offshore flow due to Ekman transport where the prevailing wind parallels the shoreline brings nutrient-rich water into eastern boundary current regions, making them highly productive areas. +Western boundary currents are warm, deep, narrow, and fast flowing currents that form on the west side of ocean basins due to western intensification. They carry warm water from the tropics poleward. Examples include the Gulf Stream, the Agulhas Current, and the Kuroshio. +Western intensification is an effect on the western arm of an oceanic current, particularly a large gyre in an ocean basin. The trade winds blow westward in the tropics. The westerlies blow eastward at mid-latitudes. This applies a stress to the ocean surface with a curl in north and south hemispheres, causing Sverdrup transport toward the tropics. Conservation of mass and potential vorticity cause that transport to be balanced by a narrow, intense poleward current, which flows along the western coast, allowing the vorticity introduced by coastal friction to balance the vorticity input of the wind. The reverse effect applies to the polar gyres – the sign of the wind stress curl and the direction of the resulting currents are reversed. +The principal west side currents (such as the Gulf Stream of the North Atlantic Ocean) are stronger than those opposite (such as the California Current of the North Pacific Ocean). + +=== Wind driven upwelling === +When the net Ekman transport along a coastline is offshore, a compensatory inflow is possible from below, which brings up bottom water, which tends to be nutrient rich as it comes from the poorly lit regions where photosynthesis is insignificant. + +Upwelling at the equator is associated with the Intertropical Convergence Zone (ITCZ) which moves seasonally, and consequently, is often located just north or south of the equator. Easterly trade winds blow from the Northeast and Southeast and converge along the equator blowing West to form the ITCZ. Although there are no Coriolis forces present along the equator, upwelling still occurs just north and south of the equator. This results in a divergence, with denser, nutrient-rich water being upwelled from below. + +=== Oceanic downwelling === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Wind_generated_current-1.md b/data/en.wikipedia.org/wiki/Wind_generated_current-1.md new file mode 100644 index 000000000..9550286e3 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Wind_generated_current-1.md @@ -0,0 +1,66 @@ +--- +title: "Wind generated current" +chunk: 2/2 +source: "https://en.wikipedia.org/wiki/Wind_generated_current" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:39.758432+00:00" +instance: "kb-cron" +--- + +Downwelling occurs at anti-cyclonic places of the ocean where warm core rings cause surface convergence and push the surface water downwards, or wind drives the sea towards a coastline. Regions that have downwelling generally have lower productivity because the nutrients in the water column are utilized but are not resupplied by nutrient-rich water from deeper below the surface. + +== Oceanic wind driven currents == +Western boundary + +Gulf Stream – Warm Atlantic Ocean current +Agulhas Current – Southwest Indian Ocean current off Africa's east coast +Kuroshio Current – North-flowing current in the northwest Pacific Ocean + +Eastern boundary + +Benguela Current – Ocean current in the South Atlantic +Humboldt Current – Current of the Pacific Ocean +California Current – Pacific Ocean current +Equatorial + +North Equatorial Current – Current in the Pacific and Atlantic Oceans +South Equatorial Current – Ocean current in the Pacific, Atlantic, and Indian Ocean + +Arctic + +Atlantic + +Canary Current – Wind-driven surface current that is part of the North Atlantic Gyre +Pacific + +Southern + +Antarctic Circumpolar Current, also known as West Wind Drift – Ocean current that flows clockwise from west to east around Antarctica +Oceanic gyres + +Beaufort Gyre – Wind-driven ocean current in the Arctic Ocean polar region +Indian Ocean Gyre – Major oceanic gyre in the Indian Ocean +North Atlantic Gyre – Major circular system of ocean currents +North Pacific Gyre – Major circulating system of ocean currents +Ross Gyre – Circulating system of ocean currents in the Ross Sea +South Atlantic Gyre – Subtropical gyre in the south Atlantic Ocean +South Pacific Gyre – Major circulating system of ocean currents +Weddell Gyre – One of two gyres within the Southern Ocean + +== Lake currents == + +== Local and transient currents == +Surface currents caused by local wind +Upwellings driven by local and prevailing winds. + +== See also == +Current (stream) – Flow of water in a natural watercourse due to gravity +Downwelling – Downwards movement of one fluid within another +Geostrophic current – Oceanic flow in which the pressure gradient force is balanced by the Coriolis effect +Hydrothermal circulation – Circulation of water driven by heat exchange +Ocean current – Directional mass flow of oceanic water +Thermohaline circulation – Part of large-scale ocean circulation +Upwelling – Oceanographic phenomenon of wind-driven motion of ocean water + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Wind_wave-0.md b/data/en.wikipedia.org/wiki/Wind_wave-0.md new file mode 100644 index 000000000..e55800f05 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Wind_wave-0.md @@ -0,0 +1,48 @@ +--- +title: "Wind wave" +chunk: 1/5 +source: "https://en.wikipedia.org/wiki/Wind_wave" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:41.303167+00:00" +instance: "kb-cron" +--- + +In fluid dynamics, a wind wave, or wind-generated water wave, is a surface wave that occurs on the free surface of bodies of water as a result of the wind blowing over the water's surface. The contact distance in the direction of the wind is known as the fetch. Waves in the oceans can travel thousands of kilometers before reaching land. Wind waves on Earth range in size from small ripples to waves over 30 m (100 ft) high, being limited by wind speed, duration, fetch, and water depth. +When directly generated and affected by local wind, a wind wave system is called a wind sea. Wind waves will travel in a great circle route after being generated – curving slightly left in the southern hemisphere and slightly right in the northern hemisphere. After moving out of the area of fetch and no longer being affected by the local wind, wind waves are called swells and can travel thousands of kilometers. A noteworthy example of this is waves generated south of Tasmania during heavy winds that will travel across the Pacific to southern California, producing desirable surfing conditions. Wind waves in the ocean are also called ocean surface waves and are mainly gravity waves, where gravity is the main equilibrium force. +Wind waves have a certain amount of randomness: subsequent waves differ in height, duration, and shape with limited predictability. They can be described as a stochastic process, in combination with the physics governing their generation, growth, propagation, and decay – as well as governing the interdependence between flow quantities such as the water surface movements, flow velocities, and water pressure. The key statistics of wind waves (both seas and swells) in evolving sea states can be predicted with wind wave models. +Although waves are usually considered in the water seas of Earth, the hydrocarbon seas of Titan may also have wind-driven waves. Waves in bodies of water may also be generated by other causes, both at the surface and underwater (such as watercraft, animals, waterfalls, landslides, earthquakes, bubbles, and impact events). + +== Formation == + +The great majority of large breakers seen at a beach result from distant winds. Five factors influence the formation of the flow structures in wind waves: + +Wind speed or strength relative to wave speed – the wind must be moving faster than the wave crest for energy transfer to the wave. +The uninterrupted distance of open water over which the wind blows without significant change in direction (called the fetch) +Width of the area affected by fetch (at a right angle to the distance) +Wind duration – the time for which the wind has blown over the water. +Water depth +All of these factors work together to determine the size of the water waves and the structure of the flow within them. +The main dimensions associated with wave propagation are: + +Wave height (vertical distance from trough to crest) +Wave length (distance from crest to crest in the direction of propagation) +Wave period (time interval between arrival of consecutive crests at a stationary point) +Wave direction or azimuth (predominantly driven by wind direction) +A fully developed sea has the maximum wave size theoretically possible for a wind of specific strength, duration, and fetch. Further exposure to that specific wind could only cause a dissipation of energy due to the breaking of wave tops and formation of "whitecaps". Waves in a given area typically have a range of heights. For weather reporting and for scientific analysis of wind wave statistics, their characteristic height over a period of time is usually expressed as significant wave height. This figure represents an average height of the highest one-third of the waves in a given time period (usually chosen somewhere in the range from 20 minutes to twelve hours), or in a specific wave or storm system. The significant wave height is also the value a "trained observer" (e.g. from a ship's crew) would estimate from visual observation of a sea state. Given the variability of wave height, the largest individual waves are likely to be somewhat less than twice the reported significant wave height for a particular day or storm. +Wave formation on an initially flat water surface by wind is started by a random distribution of normal pressure of turbulent wind flow over the water. This pressure fluctuation produces normal and tangential stresses in the surface water, which generates waves. It is usually assumed for the purpose of theoretical analysis that: + +The water is originally at rest. +The water is not viscous. +The water is irrotational. +There is a random distribution of normal pressure to the water surface from the turbulent wind. +Correlations between air and water motions are neglected. +The second mechanism involves wind shear forces on the water surface. John W. Miles suggested a surface wave generation mechanism that is initiated by turbulent wind shear flows based on the inviscid Orr–Sommerfeld equation in 1957. He found the energy transfer from the wind to the water surface is proportional to the curvature of the velocity profile of the wind at the point where the mean wind speed is equal to the wave speed. Since the wind speed profile is logarithmic to the water surface, the curvature has a negative sign at this point. This relation shows the wind flow transferring its kinetic energy to the water surface at their interface. +Assumptions: + +two-dimensional parallel shear flow +incompressible, inviscid water and wind +irrotational water +slope of the displacement of the water surface is small +Generally, these wave formation mechanisms occur together on the water surface and eventually produce fully developed waves. +For example, if we assume a flat sea surface (Beaufort state 0), and a sudden wind flow blows steadily across the sea surface, the physical wave generation process follows the sequence: \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Wind_wave-1.md b/data/en.wikipedia.org/wiki/Wind_wave-1.md new file mode 100644 index 000000000..54d7c1a29 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Wind_wave-1.md @@ -0,0 +1,137 @@ +--- +title: "Wind wave" +chunk: 2/5 +source: "https://en.wikipedia.org/wiki/Wind_wave" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:41.303167+00:00" +instance: "kb-cron" +--- + +Turbulent wind forms random pressure fluctuations at the sea surface. Ripples with wavelengths in the order of a few centimeters are generated by the pressure fluctuations. (The Phillips mechanism) +The winds keep acting on the initially rippled sea surface causing the waves to become larger. As the waves grow, the pressure differences get larger causing the growth rate to increase. Finally, the shear instability expedites the wave growth exponentially. (The Miles mechanism) +The interactions between the waves on the surface generate longer waves and the interaction will transfer wave energy from the shorter waves generated by the Miles mechanism to the waves which have slightly lower frequencies than the frequency at the peak wave magnitudes, then finally the waves will be faster than the crosswind speed (Pierson & Moskowitz). + +== Types == + +Three different types of wind waves develop over time: + +Capillary waves, or ripples, dominated by surface tension effects. +Gravity waves, dominated by gravitational and inertial forces. +Seas, raised locally by the wind. +Swells, which have traveled away from where they were raised by the wind, and have to a greater or lesser extent dispersed. +Ripples appear on smooth water when the wind blows, but will die quickly if the wind stops. The restoring force that allows them to propagate is surface tension. Sea waves are larger-scale, often irregular motions that form under sustained winds. These waves tend to last much longer, even after the wind has died, and the restoring force that allows them to propagate is gravity. As waves propagate away from their area of origin, they naturally separate into groups of common direction and wavelength. The sets of waves formed in this manner are known as swells. The Pacific Ocean is 19,800 km (12,300 mi) from Indonesia to the coast of Colombia and, based on an average wavelength of 76.5 m (251 ft), would have ~258,824 swells over that width. +It is sometimes alleged that out of a set of waves, the seventh wave in a set is always the largest; while this isn't the case, the waves in the middle of a given set tend to be larger than those before and after them. +Individual "rogue waves" (also called "freak waves", "monster waves", "killer waves", or "king waves") much higher than the other waves in the sea state can occur. In the case of the Draupner wave, its 25 m (82 ft) height was 2.2 times the significant wave height. Such waves are distinct from tides, caused by the Moon and Sun's gravitational pull, tsunamis that are caused by underwater earthquakes or landslides, and waves generated by underwater explosions or the fall of meteorites—all having far longer wavelengths than wind waves. +The largest ever recorded wind waves are not rogue waves, but standard waves in extreme sea states. For example, 29.1 m (95 ft) high waves were recorded aboard the RRS Discovery, in a sea with 18.5 m (61 ft) significant wave height, so the highest wave was only 1.6 times the significant wave height. +The biggest recorded by a buoy (as of 2011) was 32.3 m (106 ft) high during the 2007 typhoon Krosa near Taiwan. + +== Spectrum == + +Ocean waves can be classified based on: the disturbing force that creates them; the extent to which the disturbing force continues to influence them after formation; the extent to which the restoring force weakens or flattens them; and their wavelength or period. Seismic sea waves have a period of about 20 minutes, and speeds of 760 km/h (470 mph). Wind waves (deep-water waves) have a period up to about 20 seconds. + +The speed of all ocean waves is controlled by gravity, wavelength, and water depth. Most characteristics of ocean waves depend on the relationship between their wavelength and water depth. Wavelength determines the size of the orbits of water molecules within a wave, but water depth determines the shape of the orbits. The paths of water molecules in a wind wave are circular only when the wave is traveling in deep water. A wave cannot "feel" the bottom when it moves through water deeper than half its wavelength because too little wave energy is contained in the water movement below that depth. Waves moving through water deeper than half their wavelength are known as deep-water waves. On the other hand, the orbits of water molecules in waves moving through shallow water are flattened by the proximity of the sea bottom surface. Waves in water shallower than 1/20 their original wavelength are known as shallow-water waves. Transitional waves travel through water deeper than 1/20 their original wavelength but shallower than half their original wavelength. +In general, the longer the wavelength, the faster the wave energy will move through the water. The relationship between the wavelength, period and velocity of any wave is: + + + + + C + = + + L + + + / + + + T + + + + {\displaystyle C={L}/{T}} + + +where C is speed (celerity), L is the wavelength, and T is the period (in seconds). Thus the speed of the wave derives from the functional dependence + + + + L + ( + T + ) + + + {\displaystyle L(T)} + + of the wavelength on the period (the dispersion relation). +The speed of a deep-water wave may also be approximated by: + + + + + C + = + + + + g + L + + + / + + + 2 + π + + + + + + {\displaystyle C={\sqrt {{gL}/{2\pi }}}} + + +where g is the acceleration due to gravity, 9.8 meters (32 feet) per second squared. Because g and π (3.14) are constants, the equation can be reduced to: + + + + + C + = + 1.251 + + + L + + + + + {\displaystyle C=1.251{\sqrt {L}}} + + +when C is measured in meters per second and L in meters. In both formulas the wave speed is proportional to the square root of the wavelength. +The speed of shallow-water waves is described by a different equation that may be written as: + + + + + C + = + + + g + d + + + = + 3.1 + + + d + + + + + {\displaystyle C={\sqrt {gd}}=3.1{\sqrt {d}}} + \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Wind_wave-2.md b/data/en.wikipedia.org/wiki/Wind_wave-2.md new file mode 100644 index 000000000..8b64a248f --- /dev/null +++ b/data/en.wikipedia.org/wiki/Wind_wave-2.md @@ -0,0 +1,720 @@ +--- +title: "Wind wave" +chunk: 3/5 +source: "https://en.wikipedia.org/wiki/Wind_wave" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:41.303167+00:00" +instance: "kb-cron" +--- + +where C is speed (in meters per second), g is the acceleration due to gravity, and d is the depth of the water (in meters). The period of a wave remains unchanged regardless of the depth of water through which it is moving. As deep-water waves enter the shallows and feel the bottom, however, their speed is reduced, and their crests "bunch up", so their wavelength shortens. + +=== Spectral models === +Sea state can be described by the sea wave spectrum or just wave spectrum + + + + S + ( + ω + , + Θ + ) + + + {\displaystyle S(\omega ,\Theta )} + +. It is composed of a wave height spectrum (WHS) + + + + S + ( + ω + ) + + + {\displaystyle S(\omega )} + + and a wave direction spectrum (WDS) + + + + f + ( + Θ + ) + + + {\displaystyle f(\Theta )} + +. Many interesting properties about the sea state can be found from the wave spectra. +WHS describes the spectral density of wave height variance ("power") versus wave frequency, with dimension + + + + { + S + ( + ω + ) + } + = + { + + + length + + + 2 + + + ⋅ + + time + + } + + + {\displaystyle \{S(\omega )\}=\{{\text{length}}^{2}\cdot {\text{time}}\}} + +. +The relationship between the spectrum + + + + S + ( + + ω + + j + + + ) + + + {\displaystyle S(\omega _{j})} + + and the wave amplitude + + + + + A + + j + + + + + {\displaystyle A_{j}} + + for a wave component + + + + j + + + {\displaystyle j} + + is: + + + + + + + 1 + 2 + + + + A + + j + + + 2 + + + = + S + ( + + ω + + j + + + ) + + Δ + ω + + + {\displaystyle {\frac {1}{2}}A_{j}^{2}=S(\omega _{j})\,\Delta \omega } + + +Some WHS models are listed below. + +The International Towing Tank Conference (ITTC) recommended spectrum model for fully developed sea (ISSC spectrum/modified Pierson-Moskowitz spectrum): + + + + + + + + S + ( + ω + ) + + + + H + + 1 + + / + + 3 + + + 2 + + + + T + + 1 + + + + + + = + + + 0.11 + + 2 + π + + + + + + ( + + + + ω + + T + + 1 + + + + + 2 + π + + + + ) + + + − + 5 + + + + e + x + p + + + [ + + − + 0.44 + + + ( + + + + ω + + T + + 1 + + + + + 2 + π + + + + ) + + + − + 4 + + + + ] + + + + {\displaystyle {\frac {S(\omega )}{H_{1/3}^{2}T_{1}}}={\frac {0.11}{2\pi }}\left({\frac {\omega T_{1}}{2\pi }}\right)^{-5}\mathrm {exp} \left[-0.44\left({\frac {\omega T_{1}}{2\pi }}\right)^{-4}\right]} + + +ITTC recommended spectrum model for limited fetch (JONSWAP spectrum) + + + + + S + ( + ω + ) + = + 155 + + + + H + + 1 + + / + + 3 + + + 2 + + + + + T + + 1 + + + 4 + + + + ω + + 5 + + + + + + + e + x + p + + + ( + + + + − + 944 + + + + T + + 1 + + + 4 + + + + ω + + 4 + + + + + + ) + + ( + 3.3 + + ) + + Y + + + , + + + {\displaystyle S(\omega )=155{\frac {H_{1/3}^{2}}{T_{1}^{4}\omega ^{5}}}\mathrm {exp} \left({\frac {-944}{T_{1}^{4}\omega ^{4}}}\right)(3.3)^{Y},} + + +where + + + + + Y + = + exp + ⁡ + + [ + + − + + + ( + + + + 0.191 + ω + + T + + 1 + + + − + 1 + + + + 2 + + 1 + + / + + 2 + + + σ + + + + ) + + + 2 + + + + ] + + + + {\displaystyle Y=\exp \left[-\left({\frac {0.191\omega T_{1}-1}{2^{1/2}\sigma }}\right)^{2}\right]} + + + + + + σ + = + + + { + + + + 0.07 + + + + if + + ω + ≤ + 5.24 + + / + + + T + + 1 + + + , + + + + + 0.09 + + + + if + + ω + > + 5.24 + + / + + + T + + 1 + + + . + + + + + + + + + {\displaystyle \sigma ={\begin{cases}0.07&{\text{if }}\omega \leq 5.24/T_{1},\\0.09&{\text{if }}\omega >5.24/T_{1}.\end{cases}}} + + +(The latter model has since its creation improved based on the work of Phillips and Kitaigorodskii to better model the wave height spectrum for high wavenumbers.) +As for WDS, an example model of + + + + f + ( + Θ + ) + + + {\displaystyle f(\Theta )} + + might be: + + + + + f + ( + Θ + ) + = + + + 2 + π + + + + cos + + 2 + + + ⁡ + Θ + , + + − + π + + / + + 2 + ≤ + Θ + ≤ + π + + / + + 2 + + + {\displaystyle f(\Theta )={\frac {2}{\pi }}\cos ^{2}\Theta ,\qquad -\pi /2\leq \Theta \leq \pi /2} + + +Thus the sea state is fully determined and can be recreated by the following function where + + + + ζ + + + {\displaystyle \zeta } + + is the wave elevation, + + + + + ϵ + + j + + + + + {\displaystyle \epsilon _{j}} + + is uniformly distributed between 0 and + + + + 2 + π + + + {\displaystyle 2\pi } + +, and + + + + + Θ + + j + + + + + {\displaystyle \Theta _{j}} + + is randomly drawn from the directional distribution function + + + + + + f + ( + Θ + ) + + + : + + + {\displaystyle {\sqrt {f(\Theta )}}:} + + + + + + ζ + = + + ∑ + + j + = + 1 + + + N + + + + + 2 + S + ( + + ω + + j + + + ) + Δ + + ω + + j + + + + + + sin + ⁡ + ( + + ω + + j + + + t + − + + k + + j + + + x + cos + ⁡ + + Θ + + j + + + − + + k + + j + + + y + sin + ⁡ + + Θ + + j + + + + + + ϵ + + j + + + ) + . + + + {\displaystyle \zeta =\sum _{j=1}^{N}{\sqrt {2S(\omega _{j})\Delta \omega _{j}}}\;\sin(\omega _{j}t-k_{j}x\cos \Theta _{j}-k_{j}y\sin \Theta _{j}+\epsilon _{j}).} + + +== Shoaling and refraction == + +As waves travel from deep to shallow water, their shape changes (wave height increases, speed decreases, and length decreases as wave orbits become asymmetrical). This process is called shoaling. +Wave refraction is the process that occurs when waves interact with the sea bed to slow the velocity of propagation as a function of wavelength and period. As the waves slow down in shoaling water, the crests tend to realign at a decreasing angle to the depth contours. Varying depths along a wave crest cause the crest to travel at different phase speeds, with those parts of the wave in deeper water moving faster than those in shallow water. This process continues while the depth decreases, and reverses if it increases again, but the wave leaving the shoal area may have changed direction considerably. Rays—lines normal to wave crests between which a fixed amount of energy flux is contained—converge on local shallows and shoals. Therefore, the wave energy between rays is concentrated as they converge, with a resulting increase in wave height. +Because these effects are related to a spatial variation in the phase speed, and because the phase speed also changes with the ambient current—due to the Doppler shift—the same effects of refraction and altering wave height also occur due to current variations. In the case of meeting an adverse current the wave steepens, i.e. its wave height increases while the wavelength decreases, similar to the shoaling when the water depth decreases. + +== Breaking == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Wind_wave-3.md b/data/en.wikipedia.org/wiki/Wind_wave-3.md new file mode 100644 index 000000000..0b3e36adb --- /dev/null +++ b/data/en.wikipedia.org/wiki/Wind_wave-3.md @@ -0,0 +1,163 @@ +--- +title: "Wind wave" +chunk: 4/5 +source: "https://en.wikipedia.org/wiki/Wind_wave" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:41.303167+00:00" +instance: "kb-cron" +--- + +Some waves undergo a phenomenon called "breaking". A breaking wave is one whose base can no longer support its top, causing it to collapse. A wave breaks when it runs into shallow water, or when two wave systems oppose and combine forces. When the slope, or steepness ratio, of a wave, is too great, breaking is inevitable. +Individual waves in deep water break when the wave steepness—the ratio of the wave height H to the wavelength λ—exceeds about 0.17, so for H > 0.17 λ. In shallow water, with the water depth small compared to the wavelength, the individual waves break when their wave height H is larger than 0.8 times the water depth h, that is H > 0.8 h. Waves can also break if the wind grows strong enough to blow the crest off the base of the wave. +In shallow water, the base of the wave is decelerated by drag on the seabed. As a result, the upper parts will propagate at a higher velocity than the base and the leading face of the crest will become steeper and the trailing face flatter. This may be exaggerated to the extent that the leading face forms a barrel profile, with the crest falling forward and down as it extends over the air ahead of the wave. +Three main types of breaking waves are identified by surfers or surf lifesavers. Their varying characteristics make them more or less suitable for surfing and present different dangers. + +Spilling, or rolling: these are the safest waves on which to surf. They can be found in most areas with relatively flat shorelines. They are the most common type of shorebreak. The deceleration of the wave base is gradual, and the velocity of the upper parts does not differ much with height. Breaking occurs mainly when the steepness ratio exceeds the stability limit. +Plunging, or dumping: these break suddenly and can "dump" swimmers—pushing them to the bottom with great force. These are the preferred waves for experienced surfers. Strong offshore winds and long wave periods can cause dumpers. They are often found where there is a sudden rise in the seafloor, such as a reef or sandbar. Deceleration of the wave base is sufficient to cause upward acceleration and a significant forward velocity excess of the upper part of the crest. The peak rises and overtakes the forward face, forming a "barrel" or "tube" as it collapses. +Surging: these may never actually break as they approach the water's edge, as the water below them is very deep. They tend to form on steep shorelines. These waves can knock swimmers over and drag them back into deeper water. +When the shoreline is near vertical, waves do not break but are reflected. Most of the energy is retained in the wave as it returns to seaward. Interference patterns are caused by superposition of the incident and reflected waves, and the superposition may cause localized instability when peaks cross, and these peaks may break due to instability. (see also clapotic waves) + +== Physics of waves == + +Wind waves are mechanical waves that propagate along the interface between water and air; the restoring force is provided by gravity, and so they are often referred to as surface gravity waves. As the wind blows, pressure and friction perturb the equilibrium of the water surface and transfer energy from the air to the water, forming waves. The initial formation of waves by the wind is described in the theory of Phillips from 1957, and the subsequent growth of the small waves has been modeled by Miles, also in 1957. + +In linear plane waves of one wavelength in deep water, parcels near the surface move not plainly up and down but in circular orbits: forward above and backward below (compared to the wave propagation direction). As a result, the surface of the water forms not an exact sine wave, but more a trochoid with the sharper curves upwards—as modeled in trochoidal wave theory. Wind waves are thus a combination of transversal and longitudinal waves. +When waves propagate in shallow water, (where the depth is less than half the wavelength) the particle trajectories are compressed into ellipses. +In reality, for finite values of the wave amplitude (height), the particle paths do not form closed orbits; rather, after the passage of each crest, particles are displaced slightly from their previous positions, a phenomenon known as Stokes drift. +As the depth below the free surface increases, the radius of the circular motion decreases. At a depth equal to half the wavelength λ, the orbital movement has decayed to less than 5% of its value at the surface. The phase speed (also called the celerity) of a surface gravity wave is—for pure periodic wave motion of small-amplitude waves—well approximated by + + + + + c + = + + + + + + g + λ + + + 2 + π + + + + tanh + ⁡ + + ( + + + + 2 + π + d + + λ + + + ) + + + + + + {\displaystyle c={\sqrt {{\frac {g\lambda }{2\pi }}\tanh \left({\frac {2\pi d}{\lambda }}\right)}}} + + +where + +c = phase speed; +λ = wavelength; +d = water depth; +g = acceleration due to gravity at the Earth's surface. +In deep water, where + + + + d + ≥ + + + 1 + 2 + + + λ + + + {\displaystyle d\geq {\frac {1}{2}}\lambda } + +, so + + + + + + + 2 + π + d + + λ + + + ≥ + π + + + {\displaystyle {\frac {2\pi d}{\lambda }}\geq \pi } + + and the hyperbolic tangent approaches + + + + 1 + + + {\displaystyle 1} + +, the speed + + + + c + + + {\displaystyle c} + + approximates + + + + + + c + + deep + + + = + + + + + g + λ + + + 2 + π + + + + + . + + + {\displaystyle c_{\text{deep}}={\sqrt {\frac {g\lambda }{2\pi }}}.} + \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Wind_wave-4.md b/data/en.wikipedia.org/wiki/Wind_wave-4.md new file mode 100644 index 000000000..dd0a60963 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Wind_wave-4.md @@ -0,0 +1,270 @@ +--- +title: "Wind wave" +chunk: 5/5 +source: "https://en.wikipedia.org/wiki/Wind_wave" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:41.303167+00:00" +instance: "kb-cron" +--- + +In SI units, with + + + + + c + + deep + + + + + {\displaystyle c_{\text{deep}}} + + in m/s, + + + + + c + + deep + + + ≈ + 1.25 + + + λ + + + + + {\displaystyle c_{\text{deep}}\approx 1.25{\sqrt {\lambda }}} + +, when + + + + λ + + + {\displaystyle \lambda } + + is measured in metres. +This expression tells us that waves of different wavelengths travel at different speeds. The fastest waves in a storm are the ones with the longest wavelength. As a result, after a storm, the first waves to arrive on the coast are the long-wavelength swells. +For intermediate and shallow water, the Boussinesq equations are applicable, combining frequency dispersion and nonlinear effects. And in very shallow water, the shallow water equations can be used. +If the wavelength is very long compared to the water depth, the phase speed (by taking the limit of c when the wavelength approaches infinity) can be approximated by + + + + + + c + + shallow + + + = + + lim + + λ + → + ∞ + + + c + = + + + g + d + + + . + + + {\displaystyle c_{\text{shallow}}=\lim _{\lambda \rightarrow \infty }c={\sqrt {gd}}.} + + +On the other hand, for very short wavelengths, surface tension plays an important role and the phase speed of these gravity-capillary waves can (in deep water) be approximated by + + + + + + c + + gravity-capillary + + + = + + + + + + g + λ + + + 2 + π + + + + + + + + + 2 + π + S + + + ρ + λ + + + + + + + + {\displaystyle c_{\text{gravity-capillary}}={\sqrt {{\frac {g\lambda }{2\pi }}+{\frac {2\pi S}{\rho \lambda }}}}} + + +where + +S = surface tension of the air-water interface; + + + + + ρ + + + {\displaystyle \rho } + + = density of the water. +When several wave trains are present, as is always the case in nature, the waves form groups. In deep water, the groups travel at a group velocity which is half of the phase speed. Following a single wave in a group one can see the wave appearing at the back of the group, growing, and finally disappearing at the front of the group. +As the water depth + + + + d + + + {\displaystyle d} + + decreases towards the coast, this will have an effect: wave height changes due to wave shoaling and refraction. As the wave height increases, the wave may become unstable when the crest of the wave moves faster than the trough. This causes surf, a breaking of the waves. +The movement of wind waves can be captured by wave energy devices. The energy density (per unit area) of regular sinusoidal waves depends on the water density + + + + ρ + + + {\displaystyle \rho } + +, gravity acceleration + + + + g + + + {\displaystyle g} + + and the wave height + + + + H + + + {\displaystyle H} + + (which, for regular waves, is equal to twice the amplitude, + + + + a + + + {\displaystyle a} + +): + + + + + E + = + + + 1 + 8 + + + ρ + g + + H + + 2 + + + = + + + 1 + 2 + + + ρ + g + + a + + 2 + + + . + + + {\displaystyle E={\frac {1}{8}}\rho gH^{2}={\frac {1}{2}}\rho ga^{2}.} + + +The velocity of propagation of this energy is the group velocity. + +== Models == + +Surfers are very interested in the wave forecasts. There are many websites that provide predictions of the surf quality for the upcoming days and weeks. Wind wave models are driven by more general weather models that predict the winds and pressures over the oceans, seas, and lakes. +Wind wave models are also an important part of examining the impact of shore protection and beach nourishment proposals. For many beach areas there is only patchy information about the wave climate, therefore estimating the effect of wind waves is important for managing littoral environments. +A wind-generated wave can be predicted based on two parameters: wind speed at 10 m above sea level and wind duration, which must blow over long periods of time to be considered fully developed. The significant wave height and peak frequency can then be predicted for a certain fetch length. + +== Seismic signals == + +Ocean water waves generate seismic waves that are globally visible on seismographs. There are two principal constituents of the ocean wave-generated seismic microseism. The strongest of these is the secondary microseism which is created by ocean floor pressures generated by interfering ocean waves and has a spectrum that is generally between approximately 6–12 s periods, or at approximately half of the period of the responsible interfering waves. The theory for microseism generation by standing waves was provided by Michael Longuet-Higgins in 1950 after in 1941 Pierre Bernard suggested this relation with standing waves on the basis of observations. The weaker primary microseism, also globally visible, is generated by dynamic seafloor pressures of propagating waves above shallower (less than several hundred meters depth) regions of the global ocean. Microseisms were first reported in about 1900, and seismic records provide long-term proxy measurements of seasonal and climate-related large-scale wave intensity in Earth's oceans including those associated with anthropogenic global warming. + +== See also == + +== References == + +=== Scientific === +G. G. Stokes (1880). Mathematical and Physical Papers, Volume I. Cambridge University Press. pp. 197–229. +Phillips, O. M. (1977). The dynamics of the upper ocean (2nd ed.). Cambridge University Press. ISBN 978-0-521-29801-8. +Holthuijsen, Leo H. (2007). Waves in oceanic and coastal waters. Cambridge University Press. ISBN 978-0-521-86028-4. +Janssen, Peter (2004). The interaction of ocean waves and wind. Cambridge University Press. ISBN 978-0-521-46540-3. + +=== Other === +Rousmaniere, John (1989). The Annapolis Book of Seamanship (2nd revised ed.). Simon & Schuster. ISBN 978-0-671-67447-2. +Carr, Michael (October 1998). "Understanding Waves". Sail. pp. 38–45. + +== External links == + +Current global map of peak wave periods +Current global map of significant wave heights \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Windwatt-0.md b/data/en.wikipedia.org/wiki/Windwatt-0.md new file mode 100644 index 000000000..a35725086 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Windwatt-0.md @@ -0,0 +1,16 @@ +--- +title: "Windwatt" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Windwatt" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:43.767326+00:00" +instance: "kb-cron" +--- + +Windwatt (German pronunciation: [ˈvɪntvat]) is a mudflat exposed as a result of wind action on water. They occur especially in the Western Pomerania Lagoon Area National Park on Germany's Baltic Sea coast. The term is German. +Unlike the Wadden Sea along Europe's North Sea coast, the shallow water zones of the Western Pomerania Lagoon Area National Park are largely unaffected by oceanic tides. When there are strong winds in a certain direction, however, water is driven out of the lagoons (the so-called bodden) into the Baltic Sea, so that several particularly shallow areas of mud become exposed and dry out. The water flows back when the wind turns again. +These Windwatten are a major source of food for migrating birds in the autumn. For the Crane, which cross Western Pomeranian Bodden country during migration, the Windwatten are one of the most important resting areas in Western Europe. + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/ZooBorns-0.md b/data/en.wikipedia.org/wiki/ZooBorns-0.md new file mode 100644 index 000000000..0e14657a0 --- /dev/null +++ b/data/en.wikipedia.org/wiki/ZooBorns-0.md @@ -0,0 +1,32 @@ +--- +title: "ZooBorns" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/ZooBorns" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:31.737025+00:00" +instance: "kb-cron" +--- + +ZooBorns is a zoology news blog and book line that announces animal births at AZA, EAZA, CAZA, ZAA, and WAZA accredited zoos and aquariums. ZooBorns was founded in 2008 with the mission to "educate while it entertains", and typically shares related conservation information along with pictures and video of baby animals. +ZooBorns has been featured in The Washington Post, NBC News, Discover Magazine, and on the Martha Stewart Show among other media outlets. The site was created by Andrew Bleiman, co-founder of Zooillogix who lives in Chicago, and Chris Eastland, an artist living in Brooklyn. + + +== Content == +ZooBorns showcases baby animals as ambassadors for their species in order to build empathy and awareness for the plight of those species in the wild. Content is written to be accessible to a wide audience and typically provides background on individual animals followed by conservation information about the species. The site is notable for providing easily navigable categories enabling it to serve as a non-exhaustive survey of recent juvenile animals at zoos and aquariums. As of May 2012, the site had documented over 1,250 births, comprising over 200 species from over 200 different zoological institutions. + + +== Books == +In 2010 ZooBorns released two books published by Simon & Schuster: ZooBorns, written for adults and young adults and ZooBorns! +Zoo Babies from Around the World, for young children, age 3-6. Both featured animal babies born at accredited zoos and aquariums around the world. ZooBorns was recognized as a 2012: American Library Association's Quick Pick for Reluctant Young Readers and ZooBorns! +Zoo Babies from Around the World was a 2011–2012: Keystone to Reading Book Award Nominee. +In 2011 ZooBorns released ZooBorns Cats!, which showcased kitten and cub photos of 30 species of the 36 known feline species, including rare photos of the critically endangered Iriomote cat and vulnerable kodkod, also known as the guiña. +In 2012 ZooBorns is slated to release follow-ups to their first two books, ZooBorns The Next Generation, for all ages and ABC ZooBorns, for young children. Two Ready-to-Read books for toddlers will also be released, Welcome to the World, ZooBorns! and I Love You, ZooBorns! + + +== References == + + +== External links == +Official website +Association of Zoos & Aquariums \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Zoobiquity-0.md b/data/en.wikipedia.org/wiki/Zoobiquity-0.md new file mode 100644 index 000000000..a640e7e8e --- /dev/null +++ b/data/en.wikipedia.org/wiki/Zoobiquity-0.md @@ -0,0 +1,43 @@ +--- +title: "Zoobiquity" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Zoobiquity" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:56.141145+00:00" +instance: "kb-cron" +--- + +Zoobiquity is a 2012 non-fiction science book co-written by the cardiologist Barbara Natterson-Horowitz and Kathryn Bowers. It was a New York Times Bestseller. + + +== Content == +The book takes a cross-species approach to medical maladies, highlighting the many afflictions that plague humans as well as animals. +It documents UCLA cardiologist Natterson-Horowitz’s experiences as a cardiovascular consultant to the Los Angeles Zoo. The authors also consulted medical and veterinary journals (such as Journal of the American College of Cardiology, Journal of Applied Animal Welfare Science, The New England Journal of Medicine, and Journal of Experimental Biology), as well as newspapers and science magazines. +The book is divided into twelve chapters, with each focusing on a human condition alongside its animal parallel. Topics cover a broad range of disease-both physical and behavioral. +The authors point out cross-species risk factors, such as the finding that both jaguars and many Ashkenazi Jewish women carry the BRCA1 genetic mutation that increases breast cancer risk. It also discusses practices that reduce risk factors in animals, noting that both dairy cows and spayed dogs are at reduced risk of breast cancer. +The book highlights diseases that are found in both humans and animals, including obsessive-compulsive disorder in dogs, high rates of chlamydia in koalas, and horses plagued by self-harming behavior. Parallels to drug addiction are seen in wallabies and bighorn sheep indulging in hallucinogenic substances. + + +== History == +Natterson-Horowitz’s interest in bridging human and animal medicine began after the Los Angeles Zoo called her to consult on an emperor tamarin suffering from heart failure. While examining the tamarin, a veterinarian warned her against inducing capture myopathy, a term with which the cardiologist was unfamiliar. Further research led Natterson-Horowitz to equate capture myopathy with the human condition Takotsubo cardiomyopathy. From there, the doctor and Bowers began researching other similarities between human and animal health. +The book shares common ground with the One Health Initiative, a movement designed to increase collaboration between various disciplines of medicine, which was formalized in 2007. An international contingent of more than 850 scientists, physicians, and veterinarians has approved the One Health movement. + + +== Critical reception == +Philosopher Julian Baggini, in a review for The Guardian called Zoobiquity a “readable and entertaining manifesto,” but noted, “Interesting though these examples are, the book rarely delivers on its promise that bridging the animal-human divide will reap major health benefits, offering instead a promissory note for future developments.” +In a New York Journal of Books review, Diane Brandley calls Zoobiquity an “ambitious work,” saying, “Not only has Barbara Natterson-Horowitz presented a very credible argument for collaboration between disciplines, but she has done so in a most entertaining and beautifully written manner.” +Zoobiquity has received accolades that include: New York Times bestseller, a Discover Magazine Best Book of 2012, the China Times 2013 Best Book for Translated Title, and a finalist in the AAAS/Subaru SB&F Prize for Excellence in Science Books. + + +== Related events == +A conference named after the book was initiated in 2011 in an attempt to bring together leaders from both human and animal medicine for discussions of diseases that affect both people and non-human animals. The first two Zoobiquity Conferences were hosted in 2011 and 2012 in Los Angeles by the David Geffen School of Medicine at UCLA, School of Veterinary Medicine at the University of California, Davis and the Los Angeles Zoo and Botanical Gardens. The 2013 Zoobiquity Conference was held in New York and organized by the David Geffen School of Medicine at UCLA, the Wildlife Conservation Society and Bronx Zoo and the Animal Medical Center. The 2014 Zoobiquity Conference was hosted in Seattle by the University of Washington School of Medicine, the College of Veterinary Medicine at Washington State University and the Woodland Park Zoo. In 2015, the Cummings School of Veterinary Medicine at Tufts University hosted the 2015 Zoobiquity Conference in Boston. +Zoobiquity Conferences outside of the United States have been hosted by the University of Sydney in Australia and Utrecht University in the Netherlands. +The 6th annual Zoobiquity Conference is scheduled for April 2, 2016 in Philadelphia. This latest installment is a collaboration between the Pennsylvania Veterinary Medicine Association and the College of Veterinary Medicine and Perelmen School of Medicine at the University of Pennsylvania. + + +== Adaptations == +Zoobiquity is in development as a television series by 20th Century Fox TV. The pilot episode will be written and produced by Bones producers, Stephen Nathan and Jon Collier. Spencer Medof will also executive produce the medical drama, which depicts a physician and a veterinarian working together to save human and animal lives. Natterson-Horowitz and Bowers are on board as producers. + + +== References == \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Zooillogix-0.md b/data/en.wikipedia.org/wiki/Zooillogix-0.md new file mode 100644 index 000000000..07b35e31f --- /dev/null +++ b/data/en.wikipedia.org/wiki/Zooillogix-0.md @@ -0,0 +1,28 @@ +--- +title: "Zooillogix" +chunk: 1/1 +source: "https://en.wikipedia.org/wiki/Zooillogix" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:37:33.040021+00:00" +instance: "kb-cron" +--- + +Zooillogix is a zoology blog on the ScienceBlogs network, created and edited by Andrew and Benny Bleiman. The site has been featured on ABC News, in Seed magazine, Mental Floss, FHM, and the Annals of Improbable Research, awarders of the Ig Nobel Prize. The site attracts a diverse readership from notable scientists, such as PZ Myers, to biology students to young children. + + +== Content == +Zooillogix focuses on bizarre zoological news, covering research published in scientific journals, such as the Public Library of Science (PLoS), as well as stories reported in general news outlets. Typical items include the discovery of new species, newly documented animal behavior, zoo and aquarium industry news, and interviews with scientists and researchers. Content is written to be accessible to a non-scientific audience. + + +== See also == +ScienceBlogs +ZooBorns + + +== References == + + +== External links == +Zooillogix +Interview with the Bleiman brothers \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Zooplankton-0.md b/data/en.wikipedia.org/wiki/Zooplankton-0.md new file mode 100644 index 000000000..a649fc52c --- /dev/null +++ b/data/en.wikipedia.org/wiki/Zooplankton-0.md @@ -0,0 +1,24 @@ +--- +title: "Zooplankton" +chunk: 1/5 +source: "https://en.wikipedia.org/wiki/Zooplankton" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:45.054505+00:00" +instance: "kb-cron" +--- + +Zooplankton are the heterotrophic component of the planktonic community, having to consume other organisms to thrive. The name comes from Ancient Greek ζῷον (zōîon), meaning "animal", and πλαγκτός (planktós), meaning "drifter, wanderer, roamer", and thus, "animal drifter". Plankton are aquatic organisms that are unable to swim effectively against currents. Consequently, they drift or are carried along by currents in the ocean, or by currents in seas, lakes or rivers. +Zooplankton can be contrasted with phytoplankton (cyanobacteria and microalgae), which are the plant-like component of the plankton community (the "phyto-" prefix comes from Ancient Greek: φῠτόν, romanized: phutón, lit. 'plant', although taxonomically not plants). Zooplankton are heterotrophic (other-feeding), whereas phytoplankton are autotrophic (self-feeding), often generating biological energy and macromolecules through chlorophyllic carbon fixation using sunlight – in other words, zooplankton cannot manufacture their own food, while phytoplankton can. As a result, zooplankton must acquire nutrients by feeding on other organisms such as phytoplankton, which are generally smaller than zooplankton. Most zooplankton are microscopic but some (such as jellyfish) are macroscopic, meaning they can be seen with the naked eye. +Many protozoans (single-celled protists that prey on other microscopic life) are zooplankton, including zooflagellates, foraminiferans, radiolarians, some dinoflagellates and marine microanimals. Macroscopic zooplankton include pelagic cnidarians, ctenophores, molluscs, arthropods and tunicates, as well as planktonic arrow worms and bristle worms. +The distinction between autotrophy and heterotrophy often breaks down in very small organisms. Recent studies of marine microplankton have indicated over half of microscopic plankton are mixotrophs, which can obtain energy and carbon from a mix of internal plastids and external sources. Many marine microzooplankton are mixotrophic, which means they could also be classified as phytoplankton. + +== Overview == + +Zooplankton (; ) are heterotrophic (sometimes detritivorous) plankton. The word zooplankton is derived from Ancient Greek: ζῷον, romanized: zôion, lit. 'animal'; and πλᾰγκτός, planktós, 'wanderer; drifter'. +Zooplankton is a categorization spanning a range of organism sizes including small protozoans and large metazoans. It includes holoplanktonic organisms whose complete life cycle lies within the plankton, as well as meroplanktonic organisms that spend part of their lives in the plankton before graduating to either the nekton or a sessile, benthic existence. Although zooplankton are primarily transported by ambient water currents, many have locomotion, used to avoid predators (as in diel vertical migration) or to increase prey encounter rate. +Just as any species can be limited within a geographical region, so are zooplankton. However, species of zooplankton are not dispersed uniformly or randomly within a region of the ocean. As with phytoplankton, 'patches' of zooplankton species exist throughout the ocean. Though few physical barriers exist above the mesopelagic, specific species of zooplankton are strictly restricted by salinity and temperature gradients, while other species can withstand wide temperature and salinity gradients. Zooplankton patchiness can also be influenced by biological factors, as well as other physical factors. Biological factors include breeding, predation, concentration of phytoplankton, and vertical migration. The physical factor that influences zooplankton distribution the most is mixing of the water column (upwelling and downwelling along the coast and in the open ocean) that affects nutrient availability and, in turn, phytoplankton production. +Through their consumption and processing of phytoplankton and other food sources, zooplankton play a role in aquatic food webs, as a resource for consumers on higher trophic levels (including fish), and as a conduit for packaging the organic material in the biological pump. Since they are typically small, zooplankton can respond rapidly to increases in phytoplankton abundance, for instance, during the spring bloom. Zooplankton are also a key link in the biomagnification of pollutants such as mercury. + +Ecologically important protozoan zooplankton groups include the foraminiferans, radiolarians and dinoflagellates (the last of these are often mixotrophic). Important metazoan zooplankton include cnidarians such as jellyfish and the Portuguese Man o' War; crustaceans such as cladocerans, copepods, ostracods, isopods, amphipods, mysids and krill; chaetognaths (arrow worms); molluscs such as pteropods; and chordates such as salps and juvenile fish. This wide phylogenetic range includes a similarly wide range in feeding behavior: filter feeding, predation and symbiosis with autotrophic phytoplankton as seen in corals. Zooplankton feed on bacterioplankton, phytoplankton, other zooplankton (sometimes cannibalistically), detritus (or marine snow) and even nektonic organisms. As a result, zooplankton are primarily found in surface waters where food resources (phytoplankton or other zooplankton) are abundant. +Zooplankton can also act as a disease reservoir. Crustacean zooplankton have been found to house the bacterium Vibrio cholerae, which causes cholera, by allowing the cholera vibrios to attach to their chitinous exoskeletons. This symbiotic relationship enhances the bacterium's ability to survive in an aquatic environment, as the exoskeleton provides the bacterium with carbon and nitrogen. \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Zooplankton-1.md b/data/en.wikipedia.org/wiki/Zooplankton-1.md new file mode 100644 index 000000000..8a729513b --- /dev/null +++ b/data/en.wikipedia.org/wiki/Zooplankton-1.md @@ -0,0 +1,42 @@ +--- +title: "Zooplankton" +chunk: 2/5 +source: "https://en.wikipedia.org/wiki/Zooplankton" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:45.054505+00:00" +instance: "kb-cron" +--- + +== Size classification == +Body size has been defined as a "master trait" for plankton as it is a morphological characteristic shared by organisms across taxonomy that characterises the functions performed by organisms in ecosystems. It has a paramount effect on growth, reproduction, feeding strategies and mortality. One of the oldest manifestations of the biogeography of traits was proposed over 170 years ago, namely Bergmann's rule, in which field observations showed that larger species tend to be found at higher, colder latitudes. +In the oceans, size is critical in determining trophic links in planktonic ecosystems and is thus a critical factor in regulating the efficiency of the biological carbon pump. Body size is sensitive to changes in temperature due to the thermal dependence of physiological processes. The plankton is mainly composed of ectotherms which are organisms that do not generate sufficient metabolic heat to elevate their body temperature, so their metabolic processes depends on external temperature. Consequently, ectotherms grow more slowly and reach maturity at a larger body size in colder environments, which has long puzzled biologists because classic theories of life-history evolution predict smaller adult sizes in environments delaying growth. This pattern of body size variation, known as the temperature-size rule (TSR), has been observed for a wide range of ectotherms, including single-celled and multicellular species, invertebrates and vertebrates. +The processes underlying the inverse relationship between body size and temperature remain to be identified. Despite temperature playing a major role in shaping latitudinal variations in organism size, these patterns may also rely on complex interactions between physical, chemical and biological factors. For instance, oxygen supply plays a central role in determining the magnitude of ectothermic temperature-size responses, but it is hard to disentangle the relative effects of oxygen and temperature from field data because these two variables are often strongly inter-related in the surface ocean. +Zooplankton can be broken down into size classes which are diverse in their morphology, diet, feeding strategies, etc. both within classes and between classes: + +=== Microzooplankton === +Microzooplankton are defined as heterotrophic and mixotrophic plankton. They primarily consist of phagotrophic protists, including ciliates, dinoflagellates, and mesozooplankton nauplii. Microzooplankton are major grazers of the plankton community. As the primary consumers of marine phytoplankton, microzooplankton consume ~ 59–75% daily of the marine primary production, much larger than mesozooplankton. That said, macrozooplankton can sometimes have greater consumption rates in eutrophic ecosystems because the larger phytoplankton can be dominant there. Microzooplankton are also pivotal regenerators of nutrients which fuel primary production and food sources for metazoans. +Despite their ecological importance, microzooplankton remain understudied. Routine oceanographic observations seldom monitor microzooplankton biomass or herbivory rate, although the dilution technique, an elegant method of measuring microzooplankton herbivory rate, has been developed for over four decades (Landry and Hassett 1982). The number of observations of microzooplankton herbivory rate is around 1600 globally, far less than that of primary productivity (> 50,000). This makes validating and optimizing the grazing function of microzooplankton difficult in ocean ecosystem models. + +=== Mesozooplankton === +Mesozooplankton are one of the larger size classes of zooplankton. In most regions, mesozooplankton are dominated by copepods, such as Calanus finmarchicus and Calanus helgolandicus. Mesozooplankton are an important prey for fish. +As plankton are rarely fished, it has been argued that mesoplankton abundance and species composition can be used to study marine ecosystems' response to climate change. This is because they have life cycles that generally last less than a year, meaning they respond to climate changes between years. Sparse, monthly sampling will still indicate vacillations. + +== Sampling methods == + +Research vessels collect zooplankton from the ocean using fine mesh nets. The vessels either tow the nets through the sea or pump sea water onboard and then pass it through the net. + +There are many types of plankton tows: + +Neuston net tows are often made at or just below the surface using a nylon mesh net fitted to a rectangular frame +The PairoVET tow, used for collecting fish eggs, drops a net about 70 metres into the sea from a stationary research vessel and then drags it back to the vessel. +Ring net tows involve a nylon mesh net fitted to a circular frame. These have largely been replaced by bongo nets, which provide duplicate samples with their dual-net design. +The bongo tow drags nets shaped like bongo drums from a moving vessel. The net is often lowered to about 200 metres and then allowed to rise to the surface as it is towed. In this way, a sample can be collected across the whole photic zone where most ichthyoplankton is found. +MOCNESS and BIONESS tows and Tucker trawls utilize multiple nets that are mechanically opened and closed at discrete depths in order to provide insights into the vertical distribution of the plankton +The manta trawl tows a net from a moving vessel along the surface of the water, collecting larvae, such as grunion, mahi-mahi, and flying fish which live at the surface. +After the tow the plankton is flushed with a hose to the cod end (bottom) of the net for collection. The sample is then placed in preservative fluid prior to being sorted and identified in a laboratory. +Plankton pumps: Another method of collecting ichthyoplankton is to use a Continuous Underway Fish Egg Sampler (see illustration). Water from a depth of about three metres is pumped onto the vessel and filtered with a net. This method can be used while the vessel is underway. + +== Taxonomic groups == + +=== Protozooplankton === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Zooplankton-2.md b/data/en.wikipedia.org/wiki/Zooplankton-2.md new file mode 100644 index 000000000..5fc273124 --- /dev/null +++ b/data/en.wikipedia.org/wiki/Zooplankton-2.md @@ -0,0 +1,47 @@ +--- +title: "Zooplankton" +chunk: 3/5 +source: "https://en.wikipedia.org/wiki/Zooplankton" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:45.054505+00:00" +instance: "kb-cron" +--- + +Protozooplankton refers to protist zooplankton (planktonic protozoans). All protozooplankton are protozoans, but not all protozoans are protozooplankton, since some live in environments like soil or as parasites. Marine planktonic protozoans include zooflagellates, foraminiferans, radiolarians and some dinoflagellates. +Protozoans are protists that feed on organic matter such as other microorganisms or organic tissues and debris. Historically, the protozoa were regarded as "one-celled animals", because they often possess animal-like behaviours, such as motility and predation, and lack a cell wall, as found in plants and many algae. Although the traditional practice of grouping protozoa with animals is no longer considered valid, the term continues to be used in a loose way to identify single-celled organisms that can move independently and feed by heterotrophy. + +==== Radiolarians ==== + +Radiolarians are unicellular predatory protists encased in elaborate globular shells usually made of silica and pierced with holes. Their name comes from the Latin for "radius". They catch prey by extending parts of their body through the holes. As with the silica frustules of diatoms, radiolarian shells can sink to the ocean floor when radiolarians die and become preserved as part of the ocean sediment. These remains, as microfossils, provide valuable information about past oceanic conditions. + +==== Foraminiferans ==== +Like radiolarians, foraminiferans (forams for short) are single-celled predatory protists, also protected with shells that have holes in them. Their name comes from the Latin for "hole bearers". Their shells, often called tests, are chambered (forams add more chambers as they grow). The shells are usually made of calcite, but are sometimes made of agglutinated sediment particles or chiton, and (rarely) silica. Most forams are benthic, but about 40 species are planktic. They are widely researched with well-established fossil records which allow scientists to infer a lot about past environments and climates. + +==== Amoeba ==== + +==== Ciliates ==== + +==== Dinoflagellates ==== + +Dinoflagellates are a phylum of unicellular flagellates with about 2,000 marine species. Some dinoflagellates are predatory, and thus belong to the zooplankton community. Their name comes from the Greek "dinos" meaning whirling and the Latin "flagellum" meaning a whip or lash. This refers to the two whip-like attachments (flagella) used for forward movement. Most dinoflagellates are protected with red-brown, cellulose armour. Excavates may be the most basal flagellate lineage. + +Dinoflagellates often live in symbiosis with other organisms. Many nassellarian radiolarians house dinoflagellate symbionts within their tests. The nassellarian provides ammonium and carbon dioxide for the dinoflagellate, while the dinoflagellate provides the nassellarian with a mucous membrane useful for hunting and protection against harmful invaders. There is evidence from DNA analysis that dinoflagellate symbiosis with radiolarians evolved independently from other dinoflagellate symbioses, such as with foraminifera. + +=== Mixoplankton === + +Mixoplankton are mixotrophic plankton, capable of both photosynthesis and predation. A mixotroph is an organism that can use a mix of different sources of energy and carbon, instead of having a single trophic mode on the continuum from complete autotrophy at one end to heterotrophy at the other. It is estimated that mixotrophs comprise more than half of all microscopic plankton. There are two types of eukaryotic mixotrophs: those with their own chloroplasts, and those with endosymbionts—and others that acquire them through kleptoplasty or by enslaving the entire phototrophic cell. +The distinction between plants and animals often breaks down in very small organisms. Possible combinations are photo- and chemotrophy, litho- and organotrophy, auto- and heterotrophy or other combinations of these. Mixotrophs can be either eukaryotic or prokaryotic. They can take advantage of different environmental conditions. +Many marine microzooplankton are mixotrophic, which means they could also be classified as phytoplankton. Recent studies of marine microzooplankton found 30–45% of the ciliate abundance was mixotrophic, and up to 65% of the amoeboid, foram and radiolarian biomass was mixotrophic. + +Phaeocystis species are endosymbionts to acantharian radiolarians. Phaeocystis is an important algal genus found as part of the marine phytoplankton around the world. It has a polymorphic life cycle, ranging from free-living cells to large colonies. It has the ability to form floating colonies, where hundreds of cells are embedded in a gel matrix, which can increase massively in size during blooms. As a result, Phaeocystis is an important contributor to the marine carbon and sulfur cycles. + +A number of forams are mixotrophic. These have unicellular algae as endosymbionts, from diverse lineages such as the green algae, red algae, golden algae, diatoms, and dinoflagellates. Mixotrophic foraminifers are particularly common in nutrient-poor oceanic waters. Some forams are kleptoplastic, retaining chloroplasts from ingested algae to conduct photosynthesis. +By trophic orientation, dinoflagellates are all over the place. Some dinoflagellates are known to be photosynthetic, but a large fraction of these are in fact mixotrophic, combining photosynthesis with ingestion of prey (phagotrophy). Some species are endosymbionts of marine animals and other protists, and play an important part in the biology of coral reefs. Others predate other protozoa, and a few forms are parasitic. Many dinoflagellates are mixotrophic and could also be classified as phytoplankton. The toxic dinoflagellate Dinophysis acuta acquires cryptophyte chloroplasts from its ciliate prey who in turn salvage chloroplasts from ingested cryptophytes. Stoecker et al. (2017) state that "[D. acuta] cannot catch the cryptophytes by itself, and instead relies on ingesting ciliates (red Myrionecta spp.), which sequester their chloroplasts from a specific cryptophyte clade (Geminigera/Plagioselmis/Teleaulax)". + +=== Planktonic metazoa (animals) === + +Free-living species in the crustacean class Copepoda are typically 1 to 2 mm long with teardrop-shaped bodies. Like all crustaceans, their bodies are divided into three sections: head, thorax, and abdomen, with two pairs of antennae; the first pair is often long and prominent. They have a tough exoskeleton made of calcium carbonate and usually have a single red eye in the centre of their transparent head. About 13,000 species of copepods are known, of which about 10,200 are marine. They are usually among the more dominant members of the zooplankton. +In addition to copepods the crustacean classes ostracods, branchiopods and malacostracans also have planktonic members. Barnacles are planktonic only during the larval stage. + +==== Holoplankton and meroplankton ==== \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Zooplankton-3.md b/data/en.wikipedia.org/wiki/Zooplankton-3.md new file mode 100644 index 000000000..60fbe1a9b --- /dev/null +++ b/data/en.wikipedia.org/wiki/Zooplankton-3.md @@ -0,0 +1,27 @@ +--- +title: "Zooplankton" +chunk: 4/5 +source: "https://en.wikipedia.org/wiki/Zooplankton" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:45.054505+00:00" +instance: "kb-cron" +--- + +==== Ichthyoplankton ==== +Ichthyoplankton are the eggs and larvae of fish ("ichthyo" comes from the Greek word for fish). They are planktonic because they cannot swim effectively under their own power, but must drift with the ocean currents. Fish eggs cannot swim at all, and are unambiguously planktonic. Early stage larvae swim poorly, but later stage larvae swim better and cease to be planktonic as they grow into juvenile fish. Fish larvae are part of the zooplankton that eat smaller plankton, while fish eggs carry their own food supply. Both eggs and larvae are themselves eaten by larger animals. + +==== Gelatinous zooplankton ==== +Gelatinous zooplankton include ctenophores, medusae, salps, and Chaetognatha in coastal waters. Jellyfish are slow swimmers, and most species form part of the plankton. Traditionally jellyfish have been viewed as trophic dead ends, minor players in the marine food web, gelatinous organisms with a body plan largely based on water that offers little nutritional value or interest for other organisms apart from a few specialised predators such as the ocean sunfish and the leatherback sea turtle. +That view has recently been challenged. Jellyfish, and more gelatinous zooplankton in general, which include salps and ctenophores, are very diverse, fragile with no hard parts, difficult to see and monitor, subject to rapid population swings and often live inconveniently far from shore or deep in the ocean. It is difficult for scientists to detect and analyse jellyfish in the guts of predators, since they turn to mush when eaten and are rapidly digested. But jellyfish bloom in vast numbers, and it has been shown they form major components in the diets of tuna, spearfish and swordfish as well as various birds and invertebrates such as octopus, sea cucumbers, crabs and amphipods. "Despite their low energy density, the contribution of jellyfish to the energy budgets of predators may be much greater than assumed because of rapid digestion, low capture costs, availability, and selective feeding on the more energy-rich components. Feeding on jellyfish may make marine predators susceptible to ingestion of plastics." According to a 2017 study, narcomedusae consume the greatest diversity of mesopelagic prey, followed by physonect siphonophores, ctenophores and cephalopods. + +The importance of the so-called "jelly web" is only beginning to be understood, but it seems medusae, ctenophores and siphonophores can be key predators in deep pelagic food webs with ecological impacts similar to predator fish and squid. Traditionally gelatinous predators were thought ineffectual providers of marine trophic pathways, but they appear to have substantial and integral roles in deep pelagic food webs. + +== Role in food webs == +Grazing by single-celled zooplankton accounts for the majority of organic carbon loss from marine primary production. However, zooplankton grazing remains one of the key unknowns in global predictive models of carbon flux, the marine food web structure and ecosystem characteristics, because empirical grazing measurements are sparse, resulting in poor parameterisation of grazing functions. To overcome this critical knowledge gap, it has been suggested that a focused effort be placed on the development of instrumentation that can link changes in phytoplankton biomass or optical properties with grazing. +Grazing is a central, rate-setting process in ocean ecosystems and a driver of marine biogeochemical cycling. In all ocean ecosystems, grazing by heterotrophic protists constitutes the single largest loss factor of marine primary production and alters particle size distributions. Grazing affects all pathways of export production, rendering grazing important both for surface and deep carbon processes. Predicting central paradigms of ocean ecosystem function, including responses to environmental change requires accurate representation of grazing in global biogeochemical, ecosystem and cross-biome-comparison models. Several large-scale analyses have concluded that phytoplankton losses, which are dominated by grazing are the putative explanation for annual cycles in phytoplankton biomass, accumulation rates and export production. + +== Role in biogeochemistry == +In addition to linking primary producers to higher trophic levels in marine food webs, zooplankton also play an important role as "recyclers" of carbon and other nutrients that significantly impact marine biogeochemical cycles, including the biological pump. This is particularly important in the oligotrophic waters of the open ocean. Through sloppy feeding, excretion, egestion, and leaching of fecal pellets, zooplankton release dissolved organic matter (DOM) which controls DOM cycling and supports the microbial loop. Absorption efficiency, respiration, and prey size all further complicate how zooplankton are able to transform and deliver carbon to the deep ocean. + +=== Sloppy feeding and release of DOM === \ No newline at end of file diff --git a/data/en.wikipedia.org/wiki/Zooplankton-4.md b/data/en.wikipedia.org/wiki/Zooplankton-4.md new file mode 100644 index 000000000..7a302e0ed --- /dev/null +++ b/data/en.wikipedia.org/wiki/Zooplankton-4.md @@ -0,0 +1,33 @@ +--- +title: "Zooplankton" +chunk: 5/5 +source: "https://en.wikipedia.org/wiki/Zooplankton" +category: "reference" +tags: "science, encyclopedia" +date_saved: "2026-05-05T07:36:45.054505+00:00" +instance: "kb-cron" +--- + +Excretion and sloppy feeding (the physical breakdown of food source) make up 80% and 20% of crustacean zooplankton-mediated DOM release respectively. In the same study, fecal pellet leaching was found to be an insignificant contributor. For protozoan grazers, DOM is released primarily through excretion and egestion and gelatinous zooplankton can also release DOM through the production of mucus. Leaching of fecal pellets can extend from hours to days after initial egestion and its effects can vary depending on food concentration and quality. Various factors can affect how much DOM is released from zooplankton individuals or populations. Absorption efficiency (AE) is the proportion of food absorbed by plankton that determines how available the consumed organic materials are in meeting the required physiological demands. Depending on the feeding rate and prey composition, variations in AE may lead to variations in fecal pellet production, and thus regulates how much organic material is recycled back to the marine environment. Low feeding rates typically lead to high AE and small, dense pellets, while high feeding rates typically lead to low AE and larger pellets with more organic content. Another contributing factor to DOM release is respiration rate. Physical factors such as oxygen availability, pH, and light conditions may affect overall oxygen consumption and how much carbon is loss from zooplankton in the form of respired CO2. The relative sizes of zooplankton and prey also mediate how much carbon is released via sloppy feeding. Smaller prey are ingested whole, whereas larger prey may be fed on more "sloppily", that is more biomatter is released through inefficient consumption. There is also evidence that diet composition can impact nutrient release, with carnivorous diets releasing more dissolved organic carbon (DOC) and ammonium than omnivorous diets. + +=== Carbon export === +Zooplankton play a critical role in supporting the ocean's biological pump through various forms of carbon export, including the production of fecal pellets, mucous feeding webs, molts, and carcasses. Fecal pellets are estimated to be a large contributor to this export, with copepod size rather than abundance expected to determine how much carbon actually reaches the ocean floor. The importance of fecal pellets can vary both by time and location. For example, zooplankton bloom events can produce larger quantities of fecal pellets, resulting in greater measures of carbon export. Additionally, as fecal pellets sink, they are reworked by microbes in the water column, which can thus alter the carbon composition of the pellet. This affects how much carbon is recycled in the euphotic zone and how much reaches depth. Fecal pellet contribution to carbon export is likely underestimated; however, new advances in quantifying this production are currently being developed, including the use of isotopic signatures of amino acids to characterize how much carbon is being exported via zooplankton fecal pellet production. Carcasses are also gaining recognition as being important contributors to carbon export. Jelly falls – the mass sinking of gelatinous zooplankton carcasses – occur across the world as a result of large blooms. Because of their large size, these gelatinous zooplankton are expected to hold a larger carbon content, making their sinking carcasses a potentially important source of food for benthic organisms. + +== See also == +Census of Marine Zooplankton +Diel vertical migration +Ocean acidification +Primary production +Thin layers (oceanography) + +== References == + +== External links == +SAHFOS Sir Alister Hardy Foundation for Ocean Science +Ocean Drifters Short film narrated by David Attenborough about the varied roles of plankton +Sea Drifters BBC Audio slideshow +Plankton Chronicles Short documentary films & photos +COPEPOD: The global plankton database. A global coverage database of zooplankton biomass and abundance data. +Guide to the marine zooplankton of south eastern Australia, Tasmanian Aquaculture and Fisheries Institute +Australian Continuous Plankton Recorder Project Archived 2008-12-01 at the Wayback Machine +An Image-Based Key to Zooplankton of North America \ No newline at end of file