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{{biogeochemical cycle sidebar}}
A '''biogeochemical cycle''', or more generally a '''cycle of matter''',<ref>{{Cite web |title=CK12-Foundation |url=https://flexbooks.ck12.org/cbook/ck-12-college-human-biology-flexbook-2.0/section/24.7/primary/lesson/cycles-of-matter-chumbio/ |access-date=2022-03-21 |website=flexbooks.ck12.org}}</ref>
For example, in the carbon cycle, atmospheric [[carbon dioxide]] is absorbed by plants through [[photosynthesis]], which converts it into [[organic compound]]s that are used by organisms for energy and growth. [[Carbon]] is then released back into the atmosphere through [[Photorespiration|respiration]] and [[decomposition]]. Additionally, carbon is stored in [[fossil fuel]]s and is released into the atmosphere through human activities such as burning [[fossil fuels]]. In the nitrogen cycle, atmospheric [[nitrogen gas]] is converted by plants into usable forms such as [[ammonia]] and [[nitrate]]s through the process of [[nitrogen fixation]]. These compounds
There are biogeochemical cycles for many other elements, such as for [[oxygen cycle|oxygen]], [[hydrogen cycle|hydrogen]], [[phosphorus cycle|phosphorus]], [[calcium cycle|calcium]], [[iron cycle|iron]], [[sulfur cycle|sulfur]], [[mercury cycle|mercury]] and [[selenium cycle|selenium]]. There are also cycles for molecules, such as [[water cycle|water]] and [[silica cycle|silica]]. In addition there are macroscopic cycles such as the [[rock cycle]], and human-induced cycles for synthetic compounds such as for [[polychlorinated biphenyl]]s (PCBs). In some cycles there are geological reservoirs where
Biogeochemical cycles involve the interaction of biological, geological, and chemical processes. Biological processes include the influence of [[microorganism]]s, which are critical drivers of biogeochemical cycling.
==Overview==
[[File:Generalized biogeochemical cycle.jpg|thumb|upright=1.2|
[[File:The Nitrogen Cycle (1).png|thumb|upright=1.2|
Energy flows directionally through ecosystems, entering as sunlight (or inorganic molecules for [[chemoautotroph]]s) and leaving as heat during the many transfers between [[trophic level]]s. However, the matter that makes up living organisms is conserved and recycled. The six most common elements associated with organic molecules — carbon, nitrogen, hydrogen, oxygen, phosphorus, and sulfur — take a variety of chemical forms and may exist for long periods in the atmosphere, on land, in water, or beneath the Earth's surface. Geologic processes, such as [[weathering]], [[erosion]], [[water drainage]], and the [[subduction]] of the [[continental plate]]s, all play a role in this recycling of materials. Because [[geology]] and [[chemistry]] have major roles in the study of this process, the recycling of inorganic matter between living organisms and their environment is called a biogeochemical cycle.<ref name=OpenStax>[https://cnx.org/contents/ZdFkREJc@7/Biogeochemical-Cycles Biogeochemical Cycles] {{Webarchive|url=https://web.archive.org/web/20210927040316/https://cnx.org/contents/ZdFkREJc@7/Biogeochemical-Cycles |date=2021-09-27 }}, ''OpenStax'', 9 May 2019. [[File:CC-BY icon.svg|50px]] Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License] {{Webarchive|url=https://web.archive.org/web/20171016050101/https://creativecommons.org/licenses/by/4.0/ |date=2017-10-16 }}.</ref>
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The living factors of the planet can be referred to collectively as the [[biosphere]]. All the nutrients — such as [[carbon]], [[nitrogen]], [[oxygen]], [[phosphorus]], and [[sulfur]] — used in ecosystems by living organisms are a part of a ''closed system''; therefore, these chemicals are recycled instead of being lost and replenished constantly such as in an open system.<ref name="enviroliteracy.org"/>
The major parts of the biosphere are connected by the flow of chemical elements and compounds in biogeochemical cycles. In many of these cycles, the [[biota (ecology)|biota]] plays an important role. Matter from the Earth's interior is released by volcanoes. The atmosphere exchanges some compounds and elements rapidly with the biota and oceans. Exchanges of materials between rocks, soils, and the oceans are generally slower by comparison.<ref name=Moses2012>Moses, M. (2012) [http://editors.eol.org/eoearth/wiki/biogeochemical_cycles Biogeochemical cycles] {{Webarchive|url=https://web.archive.org/web/20211122221017/https://editors.eol.org/eoearth/wiki/Biogeochemical_cycles |date=2021-11-22 }}. ''[[Encyclopedia of Earth]]''.</ref>
The flow of energy in an ecosystem is an ''open system''; the
Sunlight is required to combine carbon with hydrogen and oxygen into an energy source, but ecosystems in the [[deep sea]], where no sunlight can penetrate, obtain energy from sulfur. [[Hydrogen sulfide]] near [[hydrothermal vent]]s can be utilized by organisms such as the [[giant tube worm]]. In the [[sulfur cycle]], sulfur can be forever recycled as a source of energy. Energy can be released through the [[oxidation]] and [[redox|reduction]] of sulfur compounds (e.g., oxidizing elemental sulfur to [[sulfite]] and then to [[sulfate]]).
<gallery mode="packed
File:BIOGEOCHEMICAL CYCLING OF ELEMENTS.svg|
File:WhalePump.jpg|The oceanic [[whale pump]] showing how whales cycle nutrients through the ocean [[water column]]
File:Global carbon cycle.webp|The implications of shifts in the [[global carbon cycle]] due to human activity are concerning scientists.<ref>Avelar, S., van der Voort, T.S. and Eglinton, T.I. (2017) "Relevance of carbon stocks of marine sediments for national greenhouse gas inventories of maritime nations". ''Carbon balance and management'', '''12'''(1): 10.{{doi|10.1186/s13021-017-0077-x}}. [[File:CC-BY icon.svg|50px]] Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License]. {{Webarchive|url=https://web.archive.org/web/20171016050101/https://creativecommons.org/licenses/by/4.0/ |date=2017-10-16 }}.</ref>
</gallery>
Although the Earth constantly receives energy from the
▲Although the Earth constantly receives energy from the sun, its chemical composition is essentially fixed, as the additional matter is only occasionally added by meteorites. Because this chemical composition is not replenished like energy, all processes that depend on these chemicals must be recycled. These cycles include both the living biosphere and the nonliving [[lithosphere]], [[atmosphere]], and [[hydrosphere]].
Biogeochemical cycles can be contrasted with [[geochemical cycle]]s. The latter deals only with [[Earth's crust|crustal]] and subcrustal reservoirs even though some process from both overlap.
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{{main|Hydrosphere}}
{{see also|Marine biogeochemical cycles}}
[[File:90 mile beach.jpg|thumb|upright=1.6|
[[File:Role of marine organisms in biogeochemical cycling.jpg|thumb|upright=1.6|
▲[[File:Role of marine organisms in biogeochemical cycling.jpg|thumb|upright=1.6| {{center|Some roles of marine organisms in biogeochemical cycling in the Southern Ocean{{hsp}}<ref name=Henley2020>{{cite journal |title = Changing Biogeochemistry of the Southern Ocean and Its Ecosystem Implications|year = 2020|doi = 10.3389/fmars.2020.00581|doi-access = free|last1 = Henley|first1 = Sian F.|last2 = Cavan|first2 = Emma L.|last3 = Fawcett|first3 = Sarah E.|last4 = Kerr|first4 = Rodrigo|last5 = Monteiro|first5 = Thiago|last6 = Sherrell|first6 = Robert M.|last7 = Bowie|first7 = Andrew R.|last8 = Boyd|first8 = Philip W.|last9 = Barnes|first9 = David K. A.|last10 = Schloss|first10 = Irene R.|last11 = Marshall|first11 = Tanya|last12 = Flynn|first12 = Raquel|last13 = Smith|first13 = Shantelle|journal = Frontiers in Marine Science|volume = 7}} [[File:CC-BY icon.svg|50px]] Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License] {{Webarchive|url=https://web.archive.org/web/20171016050101/https://creativecommons.org/licenses/by/4.0/ |date=2017-10-16 }}.</ref>}}]]
The global ocean covers more than 70% of the Earth's surface and is remarkably heterogeneous. Marine productive areas, and [[coastal ecosystem]]s comprise a minor fraction of the ocean in terms of surface area, yet have an enormous impact on global biogeochemical cycles carried out by [[microbial communities]], which represent 90% of the ocean's biomass.<ref>{{cite journal |doi = 10.1007/s12526-011-0084-1|title = The Census of Marine Life—evolution of worldwide marine biodiversity research|year = 2011|last1 = Alexander|first1 = Vera|last2 = Miloslavich|first2 = Patricia|last3 = Yarincik|first3 = Kristen|journal = Marine Biodiversity|volume = 41|issue = 4|pages = 545–554|s2cid = 25888475|doi-access = free| bibcode=2011MarBd..41..545A }}</ref> Work in recent years has largely focused on cycling of carbon and macronutrients such as nitrogen, phosphorus, and silicate: other important elements such as sulfur or trace elements have been less studied, reflecting associated technical and logistical issues.<ref name=Murillo2019 /> Increasingly, these marine areas, and the taxa that form their ecosystems, are subject to significant anthropogenic pressure, impacting marine life and recycling of energy and nutrients.<ref>Galton, D. (1884) [https://www.proquest.com/openview/792c496cb0a1bdf11778db87c126ff44/1?pq-origsite=gscholar&cbl=1816417 10th Meeting: report of the royal commission on metropolitan sewage] {{Webarchive|url=https://web.archive.org/web/20210924063154/https://www.proquest.com/openview/792c496cb0a1bdf11778db87c126ff44/1?pq-origsite=gscholar&cbl=1816417 |date=2021-09-24 }}. ''J. Soc. Arts'', '''33''': 290.</ref><ref>{{cite journal |doi = 10.2307/1294478|jstor = 1294478|last1 = Hasler|first1 = Arthur D.|title = Cultural Eutrophication is Reversible|journal = BioScience|year = 1969|volume = 19|issue = 5|pages = 425–431}}</ref><ref>{{cite journal |doi = 10.1002/2016GB005586|title = A reevaluation of the magnitude and impacts of anthropogenic atmospheric nitrogen inputs on the ocean|year = 2017|last1 = Jickells|first1 = T. D.|last2 = Buitenhuis|first2 = E.|last3 = Altieri|first3 = K.|last4 = Baker|first4 = A. R.|last5 = Capone|first5 = D.|last6 = Duce|first6 = R. A.|last7 = Dentener|first7 = F.|last8 = Fennel|first8 = K.|last9 = Kanakidou|first9 = M.|last10 = Laroche|first10 = J.|last11 = Lee|first11 = K.|last12 = Liss|first12 = P.|last13 = Middelburg|first13 = J. J.|last14 = Moore|first14 = J. K.|last15 = Okin|first15 = G.|last16 = Oschlies|first16 = A.|last17 = Sarin|first17 = M.|last18 = Seitzinger|first18 = S.|last19 = Sharples|first19 = J.|last20 = Singh|first20 = A.|last21 = Suntharalingam|first21 = P.|last22 = Uematsu|first22 = M.|last23 = Zamora|first23 = L. M.|journal = Global Biogeochemical Cycles|volume = 31|issue = 2|page = 289|bibcode = 2017GBioC..31..289J|hdl = 1874/348077| s2cid=5158406 |hdl-access = free}}</ref> A key example is that of [[cultural eutrophication]], where [[agricultural runoff]] leads to nitrogen and phosphorus enrichment of coastal ecosystems, greatly increasing productivity resulting in [[algal bloom]]s, [[Ocean deoxygenation|deoxygenation]] of the water column and seabed, and increased greenhouse gas emissions,<ref name=Bouwman2005>{{cite journal |doi = 10.1029/2004GB002314|title = Exploring changes in river nitrogen export to the world's oceans|year = 2005|last1 = Bouwman|first1 = A. F.|last2 = Van Drecht|first2 = G.|last3 = Knoop|first3 = J. M.|last4 = Beusen|first4 = A. H. W.|last5 = Meinardi|first5 = C. R.|journal = Global Biogeochemical Cycles|volume = 19|issue = 1|bibcode = 2005GBioC..19.1002B| s2cid=131163837 |doi-access = free}}</ref> with direct local and global impacts on [[nitrogen cycle|nitrogen]] and [[carbon cycle]]s. However, the runoff of [[organic matter]] from the mainland to [[coastal ecosystem]]s is just one of a series of pressing threats stressing microbial communities due to global change. Climate change has also resulted in changes in the [[cryosphere]], as glaciers and permafrost melt, resulting in intensified [[Ocean stratification|marine stratification]], while shifts of the [[redox|redox-state]] in different biomes are rapidly reshaping [[microbial assemblage]]s at an unprecedented rate.<ref>{{cite journal |doi = 10.1111/gcb.12754|title = Climate change and dead zones|year = 2015|last1 = Altieri|first1 = Andrew H.|last2 = Gedan|first2 = Keryn B.|journal = Global Change Biology|volume = 21|issue = 4|pages = 1395–1406|pmid = 25385668|bibcode = 2015GCBio..21.1395A| s2cid=24002134 }}</ref><ref name=Breitburg2018>{{cite journal |doi = 10.1126/science.aam7240|title = Declining oxygen in the global ocean and coastal waters|year = 2018|last1 = Breitburg|first1 = Denise|last2 = Levin|first2 = Lisa A.|last3 = Oschlies|first3 = Andreas|last4 = Grégoire|first4 = Marilaure|last5 = Chavez|first5 = Francisco P.|last6 = Conley|first6 = Daniel J.|last7 = Garçon|first7 = Véronique|last8 = Gilbert|first8 = Denis|last9 = Gutiérrez|first9 = Dimitri|last10 = Isensee|first10 = Kirsten|last11 = Jacinto|first11 = Gil S.|last12 = Limburg|first12 = Karin E.|last13 = Montes|first13 = Ivonne|last14 = Naqvi|first14 = S. W. A.|last15 = Pitcher|first15 = Grant C.|last16 = Rabalais|first16 = Nancy N.|last17 = Roman|first17 = Michael R.|last18 = Rose|first18 = Kenneth A.|last19 = Seibel|first19 = Brad A.|last20 = Telszewski|first20 = Maciej|last21 = Yasuhara|first21 = Moriaki|last22 = Zhang|first22 = Jing|journal = Science|volume = 359|issue = 6371|pages = eaam7240|pmid = 29301986|bibcode = 2018Sci...359M7240B|s2cid = 206657115|doi-access = free}}</ref><ref name=Cavicchioli2019>{{cite journal |doi = 10.1038/s41579-019-0222-5|title = Scientists' warning to humanity: Microorganisms and climate change|year = 2019|last1 = Cavicchioli|first1 = Ricardo|last2 = Ripple|first2 = William J.|last3 = Timmis|first3 = Kenneth N.|last4 = Azam|first4 = Farooq|last5 = Bakken|first5 = Lars R.|last6 = Baylis|first6 = Matthew|last7 = Behrenfeld|first7 = Michael J.|last8 = Boetius|first8 = Antje|last9 = Boyd|first9 = Philip W.|last10 = Classen|first10 = Aimée T.|last11 = Crowther|first11 = Thomas W.|last12 = Danovaro|first12 = Roberto|last13 = Foreman|first13 = Christine M.|last14 = Huisman|first14 = Jef|last15 = Hutchins|first15 = David A.|last16 = Jansson|first16 = Janet K.|last17 = Karl|first17 = David M.|last18 = Koskella|first18 = Britt|last19 = Mark Welch|first19 = David B.|last20 = Martiny|first20 = Jennifer B. H.|last21 = Moran|first21 = Mary Ann|last22 = Orphan|first22 = Victoria J.|last23 = Reay|first23 = David S.|last24 = Remais|first24 = Justin V.|last25 = Rich|first25 = Virginia I.|last26 = Singh|first26 = Brajesh K.|last27 = Stein|first27 = Lisa Y.|last28 = Stewart|first28 = Frank J.|last29 = Sullivan|first29 = Matthew B.|last30 = Van Oppen|first30 = Madeleine J. H.|journal = Nature Reviews Microbiology|volume = 17|issue = 9|pages = 569–586|pmid = 31213707|pmc = 7136171|display-authors = 1}}</ref><ref name=Hutchins2019>{{cite journal |doi = 10.1038/s41579-019-0178-5|title = Climate change microbiology — problems and perspectives|year = 2019|last1 = Hutchins|first1 = David A.|last2 = Jansson|first2 = Janet K.|last3 = Remais|first3 = Justin V.|last4 = Rich|first4 = Virginia I.|last5 = Singh|first5 = Brajesh K.|last6 = Trivedi|first6 = Pankaj|journal = Nature Reviews Microbiology|volume = 17|issue = 6|pages = 391–396|pmid = 31092905|s2cid = 155102440}}</ref><ref name=Murillo2019>{{cite journal |doi = 10.3389/fmars.2019.00657|doi-access = free|title = Editorial: Marine Microbiome and Biogeochemical Cycles in Marine Productive Areas|year = 2019|last1 = Murillo|first1 = Alejandro A.|last2 = Molina|first2 = Verónica|last3 = Salcedo-Castro|first3 = Julio|last4 = Harrod|first4 = Chris|journal = Frontiers in Marine Science|volume = 6}} [[File:CC-BY icon.svg|50px]] Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License] {{Webarchive|url=https://web.archive.org/web/20171016050101/https://creativecommons.org/licenses/by/4.0/ |date=2017-10-16 }}.</ref>
Global change is, therefore, affecting key processes including [[Marine primary production|primary productivity]], CO<sub>2</sub> and N<sub>2</sub> fixation, organic matter respiration/[[remineralization]], and the sinking and burial deposition of fixed CO<sub>2</sub>.<ref name=Hutchins2019 /> In addition to this, oceans are experiencing an [[Ocean acidification|acidification process]], with a change of ~0.1 [[pH]] units between the pre-industrial period and today, affecting [[carbonate]]/[[bicarbonate]] [[Buffering agent|buffer]] chemistry. In turn, acidification has been reported to impact [[planktonic]] communities, principally through effects on calcifying taxa.<ref>{{cite journal |doi = 10.1242/jeb.115584|title = Biochemical adaptation to ocean acidification|year = 2015|last1 = Stillman|first1 = Jonathon H.|last2 = Paganini|first2 = Adam W.|journal = Journal of Experimental Biology|volume = 218|issue = 12|pages = 1946–1955|pmid = 26085671|s2cid = 13071345|doi-access = free}}</ref> There is also evidence for shifts in the production of key intermediary volatile products, some of which have marked greenhouse effects (e.g., N<sub>2</sub>O and CH<sub>4</sub>, reviewed by Breitburg in 2018,<ref name=Breitburg2018 /> due to the increase in global temperature, ocean stratification and deoxygenation, driving as much as 25 to 50% of nitrogen loss from the ocean to the atmosphere in the so-called [[oxygen minimum zone]]s
===Lithosphere===
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== Reservoirs ==
The chemicals are sometimes held for long periods of time in one place. This place is called a ''reservoir'', which, for example, includes such things as [[coal]] deposits that are storing [[carbon]] for a long period of time.<ref name="carbon">{{cite web|last1=Baedke|first1=Steve J.|last2=Fichter|first2=Lynn S.|title=Biogeochemical Cycles: Carbon Cycle|url=http://csmgeo.csm.jmu.edu/geollab/idls/carboncycle.htm|website=
Plants and animals utilize carbon to produce carbohydrates, fats, and proteins, which can then be used to build their internal structures or to obtain energy. Plants and animals temporarily use carbon in their systems and then release it back into the air or surrounding medium. Generally, reservoirs are abiotic factors whereas exchange pools are biotic factors. Carbon is held for a relatively short time in plants and animals in comparison to coal deposits. The amount of time that a chemical is held in one place is called its [[residence time]] or [[turnover time]] (also called the renewal time or exit age).<ref name="carbon" />
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==Box models==
{{see also|Climate box models}}
[[File:Simple box model.png|thumb|upright=1|right|
Box models are widely used to model biogeochemical systems.<ref name=Sarmiento1984>{{cite journal| author = Sarmiento, J.L.|author2=Toggweiler, J.R.| year = 1984| title = A new model for the role of the oceans in determining atmospheric P CO 2| journal = Nature| volume = 308| pages = 621–24| doi = 10.1038/308621a0| issue=5960 |bibcode = 1984Natur.308..621S |s2cid=4312683}}</ref><ref name=Bianchi2007>[[Thomas S. Bianchi|Bianchi, Thomas]] (2007) [https://books.google.com/books?id=3no8DwAAQBAJ&q=%22Biogeochemistry+of+Estuaries%22 ''Biogeochemistry of Estuaries''] {{Webarchive|url=https://web.archive.org/web/20210925012739/https://books.google.com/books?id=3no8DwAAQBAJ&printsec=frontcover&dq=%22Biogeochemistry+of+Estuaries%22&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwixq4PYm_brAhXYILcAHUVzBf0QuwUwAHoECAIQBw#v=onepage&q=%22Biogeochemistry%20of%20Estuaries%22&f=false |date=2021-09-25 }} page 9, Oxford University Press. {{ISBN|9780195160826}}.</ref> Box models are simplified versions of complex systems, reducing them to boxes (or storage [[Thermodynamics#Instrumentation|reservoir]]s) for chemical materials, linked by material [[flux]]es (flows). Simple box models have a small number of boxes with properties, such as volume, that do not change with time. The boxes are assumed to behave as if they were mixed homogeneously.<ref name=Bianchi2007 /> These models are often used to derive analytical formulas describing the dynamics and steady-state abundance of the chemical species involved.
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The diagram at the right shows a basic one-box model. The reservoir contains the amount of material ''M'' under consideration, as defined by chemical, physical or biological properties. The source ''Q'' is the flux of material into the reservoir, and the sink ''S'' is the flux of material out of the reservoir. The budget is the check and balance of the sources and sinks affecting material turnover in a reservoir. The reservoir is in a [[steady state]] if ''Q'' = ''S'', that is, if the sources balance the sinks and there is no change over time.<ref name=Bianchi2007 />
The residence or turnover time is the average time material spends resident in the reservoir. If the reservoir is in a steady state, this is the same as the time it takes to fill or drain the reservoir. Thus, if τ is the turnover time, then τ = ''M''/''S''.<ref name=Bianchi2007 /> The equation describing the rate of change of content in a reservoir is
:
When two or more reservoirs are connected, the material can be regarded as cycling between the reservoirs, and there can be predictable patterns to the cyclic flow.<ref name=Bianchi2007 /> More complex [[multi-compartment model|multibox models]] are usually solved using numerical techniques.
[[File:Simplified budget of carbon flows in the ocean.png|thumb|upright=0.9|left|
[[File:Simplified diagram of the global carbon cycle.jpg|thumb|upright=2.2|right| {{center|'''More complex model with many interacting boxes'''<br /><small>export and burial rates of terrestrial organic carbon in the ocean{{hsp}}<ref name=Kandasamy2016 /></small>}}]]▼
{{Quote box
|title = Measurement units
|quote = Global biogeochemical box models usually measure:
* ''reservoir masses'' in [[petagram]]s (Pg)
* ''flow fluxes'' in petagrams per year {{nobr|(Pg yr<sup>−1</sup>)}}
|source =
|align = right
|width =
}}
The diagram on the left
▲[[File:Simplified diagram of the global carbon cycle.jpg|thumb|upright=2.2|right|
▲The diagram on the left above shows a simplified budget of ocean carbon flows. It is composed of three simple interconnected box models, one for the [[euphotic zone]], one for the [[Aphotic zone|ocean interior]] or dark ocean, and one for [[ocean sediment]]s. In the euphotic zone, net [[phytoplankton production]] is about 50 Pg C each year. About 10 Pg is exported to the ocean interior while the other 40 Pg is respired. Organic carbon degradation occurs as [[Particulate organic carbon|particles]] ([[marine snow]]) settle through the ocean interior. Only 2 Pg eventually arrives at the seafloor, while the other 8 Pg is respired in the dark ocean. In sediments, the time scale available for degradation increases by orders of magnitude with the result that 90% of the organic carbon delivered is degraded and only 0.2 Pg C yr<sup>−1</sup> is eventually buried and transferred from the biosphere to the geosphere.<ref name=Middelburg2019 />
The diagram on the right
{{clear}}
==Fast and slow cycles==
There are fast and slow biogeochemical cycles. Fast cycle operate in the [[biosphere]] and slow cycles operate in [[rock (geology)|rocks]]. Fast or biological cycles can complete within years, moving substances from atmosphere to biosphere, then back to the atmosphere. Slow or geological cycles can take millions of years to complete, moving substances through the Earth's [[Earth's crust|crust]] between rocks, soil, ocean and atmosphere.<ref name=Libes2015>Libes, Susan M. (2015). [https://books.google.com/books?id=5tC9CgAAQBAJ&dq=%22blue+planet%22+libes&pg=PA89 Blue planet: The role of the oceans in nutrient cycling, maintain the atmosphere system, and modulating climate change] {{Webarchive|url=https://web.archive.org/web/20210120070507/https://books.google.com/books?hl=en&lr=&id=5tC9CgAAQBAJ&oi=fnd&pg=PA89&dq=%22blue+planet%22+libes&ots=oesDSXq1NZ&sig=B7HrLG0Y6iE9p_AqfDfSVktQGN4#v=onepage&q=%22blue%20planet%22%20libes&f=false |date=2021-01-20 }} In: ''Routledge Handbook of Ocean Resources and Management'', Routledge, pages 89–107. {{isbn|9781136294822}}.</ref>▼
[[File:Carbon cycle.jpg|thumb|upright=1.
As an example, the fast carbon cycle is illustrated in the diagram below on the left. This cycle involves relatively short-term [[biogeochemical]] processes between the environment and living organisms in the biosphere. It includes movements of carbon between the atmosphere and terrestrial and marine ecosystems, as well as soils and [[seafloor sediments]]. The fast cycle includes annual cycles involving photosynthesis and decadal cycles involving vegetative growth and decomposition. The reactions of the fast carbon cycle to human activities will determine many of the more immediate impacts of climate change.<ref name=Bush2020 /><ref>{{cite journal |doi = 10.1073/pnas.022055499|title = Atmospheric carbon dioxide levels for the last 500 million years|year = 2002|last1 = Rothman|first1 = D. H.|journal = Proceedings of the National Academy of Sciences|volume = 99|issue = 7|pages = 4167–4171|pmid = 11904360|pmc = 123620|bibcode = 2002PNAS...99.4167R|doi-access = free}}</ref><ref name=Carpinteri2019>{{cite journal |doi = 10.3390/sci1010017|title = Correlation between the Fluctuations in Worldwide Seismicity and Atmospheric Carbon Pollution|year = 2019|last1 = Carpinteri|first1 = Alberto|last2 = Niccolini|first2 = Gianni|journal = Sci|volume = 1|page = 17|doi-access = free}} [[File:CC-BY icon.svg|50px]] Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License] {{Webarchive|url=https://web.archive.org/web/20171016050101/https://creativecommons.org/licenses/by/4.0/ |date=2017-10-16 }}.</ref><ref>{{Cite journal|last=Rothman|first=Daniel|date=January 2015|title=Earth's carbon cycle: A mathematical perspective|url=https://www.ams.org/bull/2015-52-01/S0273-0979-2014-01471-5/|journal=Bulletin of the American Mathematical Society|language=en|volume=52|issue=1|pages=47–64|doi=10.1090/S0273-0979-2014-01471-5|issn=0273-0979|hdl=1721.1/97900|hdl-access=free|access-date=2021-09-27|archive-date=2021-11-22|archive-url=https://web.archive.org/web/20211122221018/https://www.ams.org/journals/bull/2015-52-01/S0273-0979-2014-01471-5/|url-status=live}}</ref>▼
[[File:Rock cycle nps.PNG|thumb|upright=
▲[[File:Carbon cycle.jpg|thumb|upright=1.8|left| The fast cycle operates through the biosphere, including exchanges between land, atmosphere, and oceans. The yellow numbers are natural fluxes of carbon in billions of tons (gigatons) per year. Red are human contributions and white are stored carbon.<ref name="nasacc">{{cite web|last1=Riebeek|first1=Holli|title=The Carbon Cycle|url=http://earthobservatory.nasa.gov/Features/CarbonCycle/?src=eoa-features|website=Earth Observatory|publisher=NASA|access-date=5 April 2018|date=16 June 2011|archive-url=https://web.archive.org/web/20160305010126/http://earthobservatory.nasa.gov/Features/CarbonCycle/?src=eoa-features|archive-date=5 March 2016|url-status=live|df=dmy-all}}</ref>]]
▲There are fast and slow biogeochemical cycles. Fast cycle operate in the [[biosphere]] and slow cycles operate in [[rock (geology)|rocks]]. Fast or biological cycles can complete within years, moving substances from atmosphere to biosphere, then back to the atmosphere. Slow or geological cycles can take millions of years to complete, moving substances through the Earth's [[Earth's crust|crust]] between rocks, soil, ocean and atmosphere.<ref name=Libes2015>Libes, Susan M. (2015). [https://books.google.com/books?id=5tC9CgAAQBAJ&dq=%22blue+planet%22+libes&pg=PA89 Blue planet: The role of the oceans in nutrient cycling, maintain the atmosphere system, and modulating climate change] {{Webarchive|url=https://web.archive.org/web/20210120070507/https://books.google.com/books?hl=en&lr=&id=5tC9CgAAQBAJ&oi=fnd&pg=PA89&dq=%22blue+planet%22+libes&ots=oesDSXq1NZ&sig=B7HrLG0Y6iE9p_AqfDfSVktQGN4#v=onepage&q=%22blue%20planet%22%20libes&f=false |date=2021-01-20 }} In: ''Routledge Handbook of Ocean Resources and Management'', Routledge, pages 89–107. {{isbn|9781136294822}}.</ref>
▲[[File:Rock cycle nps.PNG|thumb|upright=2.25|right| {{center|The slow cycle operates through rocks, including volcanic and tectonic activity}}]]
▲As an example, the fast carbon cycle is illustrated in the diagram below on the left. This cycle involves relatively short-term [[biogeochemical]] processes between the environment and living organisms in the biosphere. It includes movements of carbon between the atmosphere and terrestrial and marine ecosystems, as well as soils and [[seafloor sediments]]. The fast cycle includes annual cycles involving photosynthesis and decadal cycles involving vegetative growth and decomposition. The reactions of the fast carbon cycle to human activities will determine many of the more immediate impacts of climate change.<ref name=Bush2020 /><ref>{{cite journal |doi = 10.1073/pnas.022055499|title = Atmospheric carbon dioxide levels for the last 500 million years|year = 2002|last1 = Rothman|first1 = D. H.|journal = Proceedings of the National Academy of Sciences|volume = 99|issue = 7|pages = 4167–4171|pmid = 11904360|pmc = 123620|bibcode = 2002PNAS...99.4167R|doi-access = free}}</ref><ref name=Carpinteri2019>{{cite journal |doi = 10.3390/sci1010017|title = Correlation between the Fluctuations in Worldwide Seismicity and Atmospheric Carbon Pollution|year = 2019|last1 = Carpinteri|first1 = Alberto|last2 = Niccolini|first2 = Gianni|journal = Sci|volume = 1|page = 17|doi-access = free}} [[File:CC-BY icon.svg|50px]] Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License] {{Webarchive|url=https://web.archive.org/web/20171016050101/https://creativecommons.org/licenses/by/4.0/ |date=2017-10-16 }}.</ref><ref>{{Cite journal|last=Rothman|first=Daniel|date=January 2015|title=Earth's carbon cycle: A mathematical perspective|url=https://www.ams.org/bull/2015-52-01/S0273-0979-2014-01471-5/|journal=Bulletin of the American Mathematical Society|language=en|volume=52|issue=1|pages=47–64|doi=10.1090/S0273-0979-2014-01471-5|issn=0273-0979|hdl=1721.1/97900|hdl-access=free|access-date=2021-09-27|archive-date=2021-11-22|archive-url=https://web.archive.org/web/20211122221018/https://www.ams.org/journals/bull/2015-52-01/S0273-0979-2014-01471-5/|url-status=live}}</ref>
The slow cycle is illustrated in the diagram above on the right. It involves medium to long-term [[geochemical]] processes belonging to the [[rock cycle]]. The exchange between the ocean and atmosphere can take centuries, and the [[weathering]] of rocks can take millions of years. Carbon in the ocean precipitates to the ocean floor where it can form [[sedimentary rock]] and be [[subducted]] into the [[
==Deep cycles==
{{further|Deep carbon cycle}}
The terrestrial subsurface is the largest reservoir of carbon on earth, containing 14–135 [[Orders of magnitude (mass)|Pg]] of carbon
==Some examples==
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File:Phosphorus cycle.png|alt=Diagram of the phosphorus cycle|[[Phosphorus cycle]]
File:Sulfur Cycle (Ciclo do Enxofre).png|alt=Diagram of the sulfur cycle|[[Sulfur cycle]]
File:
File:Water cycle.png|alt=Diagram of the water cycle|[[Water cycle]]
</gallery>
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<gallery mode="packed" style="float:left;" heights="155px">
File:Plagiomnium affine laminazellen.jpeg|[[Chloroplasts]] conduct [[photosynthesis]] in [[plant cell]]s and other [[eukaryote|eukaryotic]] organisms.
File:Organic carbon cycle including the flow of kerogen.png|[[Kerogen]] cycle
File:Coal anthracite.jpg|Coal is a reservoir of carbon
</gallery>
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Biogeochemical cycles always involve active equilibrium states: a balance in the cycling of the element between compartments. However, overall balance may involve compartments distributed on a global scale.
As biogeochemical cycles describe the movements of substances on the entire globe, the study of these is inherently multidisciplinary. The carbon cycle may be related to research in [[ecology]] and [[atmospheric sciences]].<ref>{{cite book|last1=McGuire|
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