Editing Carbon cycle (section)

== Processes within fast carbon cycle ==

=== Terrestrial carbon in the water cycle ===
[[File:Where carbon goes when water flows.jpg|thumb|upright=2| {{center|Where terrestrial carbon goes when water flows{{hsp}}<ref name=Ward2017>{{cite journal |last1=Ward |first1=Nicholas D. |last2=Bianchi |first2=Thomas S. |last3=Medeiros |first3=Patricia M. |last4=Seidel |first4=Michael |last5=Richey |first5=Jeffrey E. |last6=Keil |first6=Richard G. |last7=Sawakuchi |first7=Henrique O. |title=Where Carbon Goes When Water Flows: Carbon Cycling across the Aquatic Continuum |journal=Frontiers in Marine Science |date=31 January 2017 |volume=4 |doi=10.3389/fmars.2017.00007 |doi-access=free }}{{Creative Commons text attribution notice|cc=by4|url=|author(s)=|vrt=|from this source=yes}}</ref>}}]]

The movement of terrestrial carbon in the water cycle is shown in the diagram on the right and explained below:{{hsp}}<ref name=Ward2017 />

# Atmospheric particles act as [[cloud condensation nuclei]], promoting cloud formation.<ref name=Kerminen2000>{{cite journal |last1=Kerminen |first1=Veli-Matti |last2=Virkkula |first2=Aki |last3=Hillamo |first3=Risto |last4=Wexler |first4=Anthony S. |last5=Kulmala |first5=Markku |title=Secondary organics and atmospheric cloud condensation nuclei production |journal=Journal of Geophysical Research: Atmospheres |date=16 April 2000 |volume=105 |issue=D7 |pages=9255–9264 |doi=10.1029/1999JD901203 |bibcode=2000JGR...105.9255K }}</ref><ref name=Riipinen2011>{{cite journal |last1=Riipinen |first1=I. |last2=Pierce |first2=J. R. |last3=Yli-Juuti |first3=T. |last4=Nieminen |first4=T. |last5=Häkkinen |first5=S. |last6=Ehn |first6=M. |last7=Junninen |first7=H. |last8=Lehtipalo |first8=K. |last9=Petäjä |first9=T. |last10=Slowik |first10=J. |last11=Chang |first11=R. |last12=Shantz |first12=N. C. |last13=Abbatt |first13=J. |last14=Leaitch |first14=W. R. |last15=Kerminen |first15=V.-M. |last16=Worsnop |first16=D. R. |last17=Pandis |first17=S. N. |last18=Donahue |first18=N. M. |last19=Kulmala |first19=M. |title=Organic condensation: a vital link connecting aerosol formation to cloud condensation nuclei (CCN) concentrations |journal=Atmospheric Chemistry and Physics |date=27 April 2011 |volume=11 |issue=8 |pages=3865–3878 |doi=10.5194/acp-11-3865-2011 |doi-access=free |bibcode=2011ACP....11.3865R }}</ref>
#Raindrops absorb [[organic carbon|organic]] and [[inorganic carbon]] through particle scavenging and adsorption of organic vapors while falling toward Earth.<ref name=Waterloo2006>{{cite journal |last1=Waterloo |first1=Maarten J. |last2=Oliveira |first2=Sylvia M. |last3=Drucker |first3=Debora P. |last4=Nobre |first4=Antonio D. |last5=Cuartas |first5=Luz A. |last6=Hodnett |first6=Martin G. |last7=Langedijk |first7=Ivar |last8=Jans |first8=Wilma W. P. |last9=Tomasella |first9=Javier |last10=de Araújo |first10=Alessandro C. |last11=Pimentel |first11=Tania P. |last12=Múnera Estrada |first12=Juan C. |title=Export of organic carbon in run-off from an Amazonian rainforest blackwater catchment |journal=Hydrological Processes |date=15 August 2006 |volume=20 |issue=12 |pages=2581–2597 |doi=10.1002/hyp.6217 |bibcode=2006HyPr...20.2581W }}</ref><ref name=Neu2016>{{cite journal |last1=Neu |first1=Vania |last2=Ward |first2=Nicholas D. |last3=Krusche |first3=Alex V. |last4=Neill |first4=Christopher |title=Dissolved Organic and Inorganic Carbon Flow Paths in an Amazonian Transitional Forest |journal=Frontiers in Marine Science |date=28 June 2016 |volume=3 |doi=10.3389/fmars.2016.00114 |doi-access=free }}</ref>
#Burning and volcanic eruptions produce highly condensed [[Polycyclic aromatic hydrocarbon|polycyclic aromatic molecules]] (i.e. [[black carbon]]) that is returned to the atmosphere along with greenhouse gases such as CO<sub>2</sub>.<ref name=Baldock2004>{{cite journal |last1=Baldock |first1=J.A. |last2=Masiello |first2=C.A. |last3=Gélinas |first3=Y. |last4=Hedges |first4=J.I. |title=Cycling and composition of organic matter in terrestrial and marine ecosystems |journal=Marine Chemistry |date=December 2004 |volume=92 |issue=1–4 |pages=39–64 |doi=10.1016/j.marchem.2004.06.016 |bibcode=2004MarCh..92...39B }}</ref><ref name=Myers-Pigg2016>{{cite journal |last1=Myers-Pigg |first1=Allison N. |last2=Griffin |first2=Robert J. |last3=Louchouarn |first3=Patrick |last4=Norwood |first4=Matthew J. |last5=Sterne |first5=Amanda |last6=Cevik |first6=Basak Karakurt |title=Signatures of Biomass Burning Aerosols in the Plume of a Saltmarsh Wildfire in South Texas |journal=Environmental Science & Technology |date=6 September 2016 |volume=50 |issue=17 |pages=9308–9314 |doi=10.1021/acs.est.6b02132 |pmid=27462728 |bibcode=2016EnST...50.9308M }}</ref> 
#Terrestrial plants fix atmospheric CO<sub>2</sub> through [[photosynthesis]], returning a fraction back to the atmosphere through [[respiration (physiology)|respiration]].<ref name=Field1998>{{cite journal |last1=Field |first1=Christopher B. |last2=Behrenfeld |first2=Michael J. |last3=Randerson |first3=James T. |last4=Falkowski |first4=Paul |title=Primary Production of the Biosphere: Integrating Terrestrial and Oceanic Components |journal=Science |date=10 July 1998 |volume=281 |issue=5374 |pages=237–240 |doi=10.1126/science.281.5374.237 |pmid=9657713 |bibcode=1998Sci...281..237F |url=https://escholarship.org/uc/item/9gm7074q }}</ref> [[Lignin]] and [[cellulose]]s represent as much as 80% of the organic carbon in forests and 60% in pastures.<ref name=Martens2004>{{cite journal |last1=Martens |first1=Dean A. |last2=Reedy |first2=Thomas E. |last3=Lewis |first3=David T. |title=Soil organic carbon content and composition of 130-year crop, pasture and forest land-use managements |journal=Global Change Biology |date=January 2004 |volume=10 |issue=1 |pages=65–78 |doi=10.1046/j.1529-8817.2003.00722.x |bibcode=2004GCBio..10...65M |url=https://digitalcommons.unl.edu/agronomyfacpub/124 }}</ref><ref name=Bose2009>{{cite journal |last1=Bose |first1=Samar K. |last2=Francis |first2=Raymond C. |last3=Govender |first3=Mark |last4=Bush |first4=Tamara |last5=Spark |first5=Andrew |title=Lignin content versus syringyl to guaiacyl ratio amongst poplars |journal=Bioresource Technology |date=February 2009 |volume=100 |issue=4 |pages=1628–1633 |doi=10.1016/j.biortech.2008.08.046 |pmid=18954979 |bibcode=2009BiTec.100.1628B }}</ref> 
#[[Litterfall]] and root organic carbon mix with sedimentary material to form organic soils where plant-derived and petrogenic organic carbon is both stored and transformed by microbial and fungal activity.<ref name=Schlesinger2000>{{cite journal |last1=Schlesinger |first1=William H. |last2=Andrews |first2=Jeffrey A. |title=Soil respiration and the global carbon cycle |journal=Biogeochemistry |date=2000 |volume=48 |issue=1 |pages=7–20 |doi=10.1023/A:1006247623877 |bibcode=2000Biogc..48....7S }}</ref><ref name=Schmidt2011>{{cite journal |last1=Schmidt |first1=Michael W. I. |last2=Torn |first2=Margaret S. |last3=Abiven |first3=Samuel |last4=Dittmar |first4=Thorsten |last5=Guggenberger |first5=Georg |last6=Janssens |first6=Ivan A. |last7=Kleber |first7=Markus |last8=Kögel-Knabner |first8=Ingrid |author8-link=Ingrid Kögel-Knabner|last9=Lehmann |first9=Johannes |last10=Manning |first10=David A. C. |last11=Nannipieri |first11=Paolo |last12=Rasse |first12=Daniel P. |last13=Weiner |first13=Steve |last14=Trumbore |first14=Susan E. |title=Persistence of soil organic matter as an ecosystem property |journal=Nature |date=October 2011 |volume=478 |issue=7367 |pages=49–56 |doi=10.1038/nature10386 |pmid=21979045 |bibcode=2011Natur.478...49S |url=https://digital.library.unt.edu/ark:/67531/metadc844476/ }}</ref><ref name=Lehmann2015>{{cite journal |last1=Lehmann |first1=Johannes |last2=Kleber |first2=Markus |title=The contentious nature of soil organic matter |journal=Nature |date=December 2015 |volume=528 |issue=7580 |pages=60–68 |doi=10.1038/nature16069 |pmid=26595271 |bibcode=2015Natur.528...60L }}</ref>
#Water absorbs plant and settled aerosol-derived [[dissolved organic carbon]] (DOC) and [[dissolved inorganic carbon]] (DIC) as it passes over forest canopies (i.e. [[throughfall]]) and along plant trunks/stems (i.e. [[stemflow]]).<ref>{{cite journal |last1=Qualls |first1=Robert G. |last2=Haines |first2=Bruce L. |title=Biodegradability of Dissolved Organic Matter in Forest Throughfall, Soil Solution, and Stream Water |journal=Soil Science Society of America Journal |date=March 1992 |volume=56 |issue=2 |pages=578–586 |doi=10.2136/sssaj1992.03615995005600020038x |bibcode=1992SSASJ..56..578Q }}</ref> Biogeochemical transformations take place as water soaks into soil solution and groundwater reservoirs<ref name=Grøn1992>{{cite journal |last1=Grøn |first1=Christian |last2=Tørsløv |first2=Jens |last3=Albrechtsen |first3=Hans-Jørgen |last4=Jensen |first4=Hanne Møller |title=Biodegradability of dissolved organic carbon in groundwater from an unconfined aquifer |journal=Science of the Total Environment |date=May 1992 |volume=117-118 |pages=241–251 |doi=10.1016/0048-9697(92)90091-6 |bibcode=1992ScTEn.117..241G }}</ref><ref name=Pabich2001>{{cite journal |last1=Pabich |first1=Wendy J. |last2=Valiela |first2=Ivan |last3=Hemond |first3=Harold F. |title=Relationship between DOC concentration and vadose zone thickness and depth below water table in groundwater of Cape Cod, U.S.A. |journal=Biogeochemistry |date=2001 |volume=55 |issue=3 |pages=247–268 |doi=10.1023/A:1011842918260 |bibcode=2001Biogc..55..247P }}</ref> and [[overland flow]] occurs when soils are completely saturated,<ref name=Linsley1975>{{cite book |last1=Linsley |first1=Ray K. |title=Solutions Manual to Accompany Hydrology for Engineers |date=1975 |publisher=McGraw-Hill |oclc=24765393 }}{{pn|date=July 2024}}</ref> or rainfall occurs more rapidly than saturation into soils.<ref name=Horton1933>{{cite journal |title=The Rôle of infiltration in the hydrologic cycle |journal=Eos, Transactions American Geophysical Union |date=June 1933 |volume=14 |issue=1 |pages=446–460 |doi=10.1029/TR014i001p00446 |bibcode=1933TrAGU..14..446H |last1=Horton |first1=Robert E. }}</ref>
#Organic carbon derived from the terrestrial biosphere and ''in situ'' [[primary production]] is decomposed by microbial communities in rivers and streams along with physical decomposition (i.e. [[photo-oxidation]]), resulting in a flux of CO<sub>2</sub> from rivers to the atmosphere that are the same order of magnitude as the amount of carbon sequestered annually by the terrestrial biosphere.<ref name=Richey2002>{{cite journal |last1=Richey |first1=Jeffrey E. |last2=Melack |first2=John M. |last3=Aufdenkampe |first3=Anthony K. |last4=Ballester |first4=Victoria M. |last5=Hess |first5=Laura L. |title=Outgassing from Amazonian rivers and wetlands as a large tropical source of atmospheric CO2 |journal=Nature |date=April 2002 |volume=416 |issue=6881 |pages=617–620 |doi=10.1038/416617a |pmid=11948346 }}</ref><ref name=Cole2007>{{cite journal |last1=Cole |first1=J. J. |last2=Prairie |first2=Y. T. |last3=Caraco |first3=N. F. |last4=McDowell |first4=W. H. |last5=Tranvik |first5=L. J. |last6=Striegl |first6=R. G. |last7=Duarte |first7=C. M. |last8=Kortelainen |first8=P. |last9=Downing |first9=J. A. |last10=Middelburg |first10=J. J. |last11=Melack |first11=J. |title=Plumbing the Global Carbon Cycle: Integrating Inland Waters into the Terrestrial Carbon Budget |journal=Ecosystems |date=February 2007 |volume=10 |issue=1 |pages=172–185 |doi=10.1007/s10021-006-9013-8 |bibcode=2007Ecosy..10..172C }}</ref><ref name=Raymond2013>{{cite journal |last1=Raymond |first1=Peter A. |last2=Hartmann |first2=Jens |last3=Lauerwald |first3=Ronny |last4=Sobek |first4=Sebastian |last5=McDonald |first5=Cory |last6=Hoover |first6=Mark |last7=Butman |first7=David |last8=Striegl |first8=Robert |last9=Mayorga |first9=Emilio |last10=Humborg |first10=Christoph |last11=Kortelainen |first11=Pirkko |last12=Dürr |first12=Hans |last13=Meybeck |first13=Michel |last14=Ciais |first14=Philippe |last15=Guth |first15=Peter |title=Global carbon dioxide emissions from inland waters |journal=Nature |date=21 November 2013 |volume=503 |issue=7476 |pages=355–359 |doi=10.1038/nature12760 |pmid=24256802 |bibcode=2013Natur.503..355R |url=http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-213816 }}</ref> Terrestrially-derived macromolecules such as lignin{{hsp}}<ref name=Ward2013>{{cite journal |last1=Ward |first1=Nicholas D. |last2=Keil |first2=Richard G. |last3=Medeiros |first3=Patricia M. |last4=Brito |first4=Daimio C. |last5=Cunha |first5=Alan C. |last6=Dittmar |first6=Thorsten |last7=Yager |first7=Patricia L. |last8=Krusche |first8=Alex V. |last9=Richey |first9=Jeffrey E. |title=Degradation of terrestrially derived macromolecules in the Amazon River |journal=Nature Geoscience |date=July 2013 |volume=6 |issue=7 |pages=530–533 |doi=10.1038/ngeo1817 |bibcode=2013NatGe...6..530W }}</ref> and [[black carbon]]{{hsp}}<ref name=Myers-Pigg2015>{{cite journal |last1=Myers-Pigg |first1=Allison N. |last2=Louchouarn |first2=Patrick |last3=Amon |first3=Rainer M. W. |last4=Prokushkin |first4=Anatoly |last5=Pierce |first5=Kayce |last6=Rubtsov |first6=Alexey |title=Labile pyrogenic dissolved organic carbon in major Siberian Arctic rivers: Implications for wildfire-stream metabolic linkages |journal=Geophysical Research Letters |date=28 January 2015 |volume=42 |issue=2 |pages=377–385 |doi=10.1002/2014GL062762 |bibcode=2015GeoRL..42..377M |doi-access=free }}</ref> are decomposed into smaller components and [[monomer]]s, ultimately being converted to CO<sub>2</sub>, metabolic intermediates, or [[Biomass (ecology)|biomass]].
#Lakes, reservoirs, and [[floodplain]]s typically store large amounts of organic carbon and sediments, but also experience net [[heterotrophy]] in the water column, resulting in a net flux of CO<sub>2</sub> to the atmosphere that is roughly one order of magnitude less than rivers.<ref name=Tranvik2009>{{cite journal |last1=Tranvik |first1=Lars J. |last2=Downing |first2=John A. |last3=Cotner |first3=James B. |last4=Loiselle |first4=Steven A. |last5=Striegl |first5=Robert G. |last6=Ballatore |first6=Thomas J. |last7=Dillon |first7=Peter |last8=Finlay |first8=Kerri |last9=Fortino |first9=Kenneth |last10=Knoll |first10=Lesley B. |last11=Kortelainen |first11=Pirkko L. |last12=Kutser |first12=Tiit |last13=Larsen |first13=Soren. |last14=Laurion |first14=Isabelle |last15=Leech |first15=Dina M. |last16=McCallister |first16=S. Leigh |last17=McKnight |first17=Diane M. |last18=Melack |first18=John M. |last19=Overholt |first19=Erin |last20=Porter |first20=Jason A. |last21=Prairie |first21=Yves |last22=Renwick |first22=William H. |last23=Roland |first23=Fabio |last24=Sherman |first24=Bradford S. |last25=Schindler |first25=David W. |last26=Sobek |first26=Sebastian |last27=Tremblay |first27=Alain |last28=Vanni |first28=Michael J. |last29=Verschoor |first29=Antonie M. |last30=von Wachenfeldt |first30=Eddie |last31=Weyhenmeyer |first31=Gesa A. |title=Lakes and reservoirs as regulators of carbon cycling and climate |journal=Limnology and Oceanography |date=November 2009 |volume=54 |issue=6part2 |pages=2298–2314 |doi=10.4319/lo.2009.54.6_part_2.2298 |bibcode=2009LimOc..54.2298T }}</ref><ref name=Raymond2013 /> Methane production is also typically high in the [[anoxic waters|anoxic]] sediments of floodplains, lakes, and reservoirs.<ref name=Bastviken2004>{{cite journal |last1=Bastviken |first1=David |last2=Cole |first2=Jonathan |last3=Pace |first3=Michael |last4=Tranvik |first4=Lars |title=Methane emissions from lakes: Dependence of lake characteristics, two regional assessments, and a global estimate |journal=Global Biogeochemical Cycles |date=December 2004 |volume=18 |issue=4 |doi=10.1029/2004GB002238 |bibcode=2004GBioC..18.4009B }}</ref>
#Primary production is typically enhanced in [[river plume]]s due to the export of [[fluvial]] nutrients.<ref name=Cooley2007>{{cite journal |last1=Cooley |first1=S. R. |last2=Coles |first2=V. J. |last3=Subramaniam |first3=A. |last4=Yager |first4=P. L. |title=Seasonal variations in the Amazon plume-related atmospheric carbon sink |journal=Global Biogeochemical Cycles |date=September 2007 |volume=21 |issue=3 |doi=10.1029/2006GB002831 |bibcode=2007GBioC..21.3014C }}</ref><ref name=Subramaniam2008>{{cite journal |last1=Subramaniam |first1=A. |last2=Yager |first2=P. L. |last3=Carpenter |first3=E. J. |last4=Mahaffey |first4=C. |last5=Björkman |first5=K. |last6=Cooley |first6=S. |last7=Kustka |first7=A. B. |last8=Montoya |first8=J. P. |last9=Sañudo-Wilhelmy |first9=S. A. |last10=Shipe |first10=R. |last11=Capone |first11=D. G. |title=Amazon River enhances diazotrophy and carbon sequestration in the tropical North Atlantic Ocean |journal=Proceedings of the National Academy of Sciences |date=29 July 2008 |volume=105 |issue=30 |pages=10460–10465 |doi=10.1073/pnas.0710279105 |doi-access=free |pmid=18647838 |pmc=2480616 }}</ref> Nevertheless, [[estuarine]] waters are a source of CO<sub>2</sub> to the atmosphere, globally.<ref name=Cai2011>{{cite journal |last1=Cai |first1=Wei-Jun |title=Estuarine and Coastal Ocean Carbon Paradox: CO 2 Sinks or Sites of Terrestrial Carbon Incineration? |journal=Annual Review of Marine Science |date=15 January 2011 |volume=3 |issue=1 |pages=123–145 |doi=10.1146/annurev-marine-120709-142723 |pmid=21329201 |bibcode=2011ARMS....3..123C }}</ref>
#[[Coastal marsh]]es both store and export [[blue carbon]].<ref name=Odum1979>{{cite book |doi=10.1007/978-1-4615-9146-7 |title=Ecological Processes in Coastal and Marine Systems |date=1979 |isbn=978-1-4615-9148-1 |editor-last1=Livingston |editor-first1=Robert J. }}{{pn|date=July 2024}}</ref><ref name=Dittmar2001>{{cite journal |last1=Dittmar |first1=Thorsten |last2=Lara |first2=Rubén José |last3=Kattner |first3=Gerhard |title=River or mangrove? Tracing major organic matter sources in tropical Brazilian coastal waters |journal=Marine Chemistry |date=March 2001 |volume=73 |issue=3–4 |pages=253–271 |doi=10.1016/s0304-4203(00)00110-9 |bibcode=2001MarCh..73..253D }}</ref><ref name=Moore2011>{{cite journal |last1=Moore |first1=W.S. |last2=Beck |first2=M. |last3=Riedel |first3=T. |last4=Rutgers van der Loeff |first4=M. |last5=Dellwig |first5=O. |last6=Shaw |first6=T.J. |last7=Schnetger |first7=B. |last8=Brumsack |first8=H.-J. |title=Radium-based pore water fluxes of silica, alkalinity, manganese, DOC, and uranium: A decade of studies in the German Wadden Sea |journal=Geochimica et Cosmochimica Acta |date=November 2011 |volume=75 |issue=21 |pages=6535–6555 |doi=10.1016/j.gca.2011.08.037 |bibcode=2011GeCoA..75.6535M }}</ref> [[Marsh]]es and [[wetland]]s are suggested to have an equivalent flux of CO<sub>2</sub> to the atmosphere as rivers, globally.<ref name=Wehrli2013>{{cite journal |last1=Wehrli |first1=Bernhard |title=Conduits of the carbon cycle |journal=Nature |date=November 2013 |volume=503 |issue=7476 |pages=346–347 |doi=10.1038/503346a |pmid=24256800 }}</ref>
#[[Continental shelves]] and the [[open ocean]] typically absorb CO<sub>2</sub> from the atmosphere.<ref name=Cai2011 /> 
#The marine [[biological pump]] sequesters a small but significant fraction of the absorbed CO<sub>2</sub> as organic carbon in [[marine sediment]]s ([[#The marine biological pump|see below]]).<ref name=Moran2016>{{cite journal |last1=Moran |first1=Mary Ann |last2=Kujawinski |first2=Elizabeth B. |last3=Stubbins |first3=Aron |last4=Fatland |first4=Rob |last5=Aluwihare |first5=Lihini I. |last6=Buchan |first6=Alison |last7=Crump |first7=Byron C. |last8=Dorrestein |first8=Pieter C. |last9=Dyhrman |first9=Sonya T. |last10=Hess |first10=Nancy J. |last11=Howe |first11=Bill |last12=Longnecker |first12=Krista |last13=Medeiros |first13=Patricia M. |last14=Niggemann |first14=Jutta |last15=Obernosterer |first15=Ingrid |last16=Repeta |first16=Daniel J. |last17=Waldbauer |first17=Jacob R. |title=Deciphering ocean carbon in a changing world |journal=Proceedings of the National Academy of Sciences |date=22 March 2016 |volume=113 |issue=12 |pages=3143–3151 |doi=10.1073/pnas.1514645113 |doi-access=free |pmid=26951682 |pmc=4812754 |bibcode=2016PNAS..113.3143M }}</ref><ref name=Ward2017 />

{{clear}}

=== Terrestrial runoff to the ocean ===
[[File:Terrestrial carbon escaping from inland waters.jpg|thumb|upright=2| {{center|'''How carbon moves from inland waters to the ocean'''}} Carbon dioxide exchange, photosynthetic production and respiration of terrestrial vegetation, rock weathering, and sedimentation occur in terrestrial ecosystems. Carbon transports to the ocean through the land-river-estuary continuum in the form of organic carbon and inorganic carbon. Carbon exchange at the air-water interface, transportation, transformation and sedimentation occur in oceanic ecosystems..<ref name="Gao2022">{{cite journal |last1=Gao |first1=Yang |last2=Lu |first2=Yao |last3=Dungait |first3=Jennifer A. J. |last4=Liu |first4=Jianbao |last5=Lin |first5=Shunhe |last6=Jia |first6=Junjie |last7=Yu |first7=Guirui |title=The 'Regulator' Function of Viruses on Ecosystem Carbon Cycling in the Anthropocene |journal=Frontiers in Public Health |date=29 March 2022 |volume=10 |doi=10.3389/fpubh.2022.858615 |pmid=35425734 |doi-access=free |pmc=9001988 }}{{Creative Commons text attribution notice|cc=by4|url=|author(s)=|vrt=|from this source=yes}}</ref>
]]

Terrestrial and marine ecosystems are chiefly connected through [[riverine]] transport, which acts as the main channel through which erosive terrestrially derived substances enter into oceanic systems. Material and energy exchanges between the terrestrial [[biosphere]] and the [[lithosphere]] as well as [[organic carbon]] fixation and oxidation processes together regulate ecosystem carbon and [[dioxygen]] (O<sub>2</sub>) pools.<ref name="Gao2022" />

Riverine transport, being the main connective channel of these pools, will act to transport [[net primary productivity]] (primarily in the form of [[dissolved organic carbon]] (DOC) and [[particulate organic carbon]] (POC)) from terrestrial to oceanic systems.<ref>{{cite journal |last1=Schlünz |first1=B. |last2=Schneider |first2=R. R. |date=2000-03-22 |title=Transport of terrestrial organic carbon to the oceans by rivers: re-estimating flux- and burial rates |journal=International Journal of Earth Sciences |publisher=Springer Science and Business Media LLC |volume=88 |issue=4 |pages=599–606 |bibcode=2000IJEaS..88..599S |doi=10.1007/s005310050290 |s2cid=128411658 }}</ref> During transport, part of DOC will rapidly return to the atmosphere through [[redox reaction]]s, causing "carbon degassing" to occur between land-atmosphere storage layers.<ref>{{cite journal |last1=Blair |first1=Neal E. |last2=Leithold |first2=Elana L. |last3=Aller |first3=Robert C. |year=2004 |title=From bedrock to burial: The evolution of particulate organic carbon across coupled watershed-continental margin systems |journal=Marine Chemistry |volume=92 |issue=1–4 |pages=141–156 |doi=10.1016/j.marchem.2004.06.023|bibcode=2004MarCh..92..141B }}</ref><ref>{{cite journal |last1=Bouchez |first1=Julien |last2=Beyssac |first2=Olivier |last3=Galy |first3=Valier |last4=Gaillardet |first4=Jérôme |last5=France-Lanord |first5=Christian |last6=Maurice |first6=Laurence |last7=Moreira-Turcq |first7=Patricia |year=2010 |title=Oxidation of petrogenic organic carbon in the Amazon floodplain as a source of atmospheric CO2 |journal=Geology |publisher=Geological Society of America |volume=38 |issue=3 |pages=255–258 |bibcode=2010Geo....38..255B |doi=10.1130/g30608.1 |s2cid=53512466 }}</ref> The remaining DOC and [[dissolved inorganic carbon]] (DIC) are also exported to the ocean.<ref>{{cite journal |last1=Regnier |first1=Pierre |last2=Friedlingstein |first2=Pierre |last3=Ciais |first3=Philippe |last4=Mackenzie |first4=Fred T. |last5=Gruber |first5=Nicolas |last6=Janssens |first6=Ivan A. |last7=Laruelle |first7=Goulven G. |last8=Lauerwald |first8=Ronny |last9=Luyssaert |first9=Sebastiaan |last10=Andersson |first10=Andreas J. |last11=Arndt |first11=Sandra |last12=Arnosti |first12=Carol |last13=Borges |first13=Alberto V. |last14=Dale |first14=Andrew W. |last15=Gallego-Sala |first15=Angela |last16=Goddéris |first16=Yves |last17=Goossens |first17=Nicolas |last18=Hartmann |first18=Jens |last19=Heinze |first19=Christoph |last20=Ilyina |first20=Tatiana |last21=Joos |first21=Fortunat |last22=LaRowe |first22=Douglas E. |last23=Leifeld |first23=Jens |last24=Meysman |first24=Filip J. R. |last25=Munhoven |first25=Guy |last26=Raymond |first26=Peter A. |last27=Spahni |first27=Renato |last28=Suntharalingam |first28=Parvadha |last29=Thullner |first29=Martin |title=Anthropogenic perturbation of the carbon fluxes from land to ocean |journal=Nature Geoscience |date=August 2013 |volume=6 |issue=8 |pages=597–607 |doi=10.1038/ngeo1830 |bibcode=2013NatGe...6..597R |hdl=10871/18939 |url=https://archimer.ifremer.fr/doc/00264/37508/36764.pdf |hdl-access=free }}</ref><ref name="Bauer2013">{{cite journal |last1=Bauer |first1=James E. |last2=Cai |first2=Wei-Jun |last3=Raymond |first3=Peter A. |last4=Bianchi |first4=Thomas S. |last5=Hopkinson |first5=Charles S. |last6=Regnier |first6=Pierre A. G. |title=The changing carbon cycle of the coastal ocean |journal=Nature |date=5 December 2013 |volume=504 |issue=7478 |pages=61–70 |doi=10.1038/nature12857 |pmid=24305149 |bibcode=2013Natur.504...61B |s2cid=4399374 }}</ref><ref>{{cite journal |last1=Cai |first1=Wei-Jun |title=Estuarine and Coastal Ocean Carbon Paradox: CO 2 Sinks or Sites of Terrestrial Carbon Incineration? |journal=Annual Review of Marine Science |date=15 January 2011 |volume=3 |issue=1 |pages=123–145 |doi=10.1146/annurev-marine-120709-142723 |bibcode=2011ARMS....3..123C |pmid=21329201 }}</ref> In 2015, inorganic and organic carbon export fluxes from global rivers were assessed as 0.50–0.70 [[petagram|Pg]] C y<sup>−1</sup> and 0.15–0.35 Pg C y<sup>−1</sup> respectively.<ref name="Bauer2013" /> On the other hand, POC can remain buried in sediment over an extensive period, and the annual global terrestrial to oceanic POC flux has been estimated at 0.20<small> (+0.13,-0.07)</small> [[gigagram|Gg]] C y<sup>−1</sup>.<ref>{{cite journal |last1=Galy |first1=Valier |last2=Peucker-Ehrenbrink |first2=Bernhard |last3=Eglinton |first3=Timothy |title=Global carbon export from the terrestrial biosphere controlled by erosion |journal=Nature |date=May 2015 |volume=521 |issue=7551 |pages=204–207 |doi=10.1038/nature14400 |pmid=25971513 |bibcode=2015Natur.521..204G |s2cid=205243485 }}</ref><ref name="Gao2022" />

=== Biological pump in the ocean ===
[[File:Oceanic Food Web.jpg|thumb|upright=2| {{center|Flow of carbon through the open ocean}}]]
{{main|Biological pump}}

The ocean [[biological pump]] is the ocean's biologically driven sequestration of [[carbon]] from the atmosphere and land runoff to the deep ocean interior and [[seafloor sediments]].<ref name="Sigman DM 2006. pp. 491-528">{{cite book |doi=10.1016/B0-08-043751-6/06118-1 |bibcode=2003TrGeo...6..491S |chapter=The Biological Pump in the Past |title=Treatise on Geochemistry |date=2003 |last1=Sigman |first1=D.M. |last2=Haug |first2=G.H. |volume=6 |pages=491–528 |isbn=978-0-08-043751-4 }}</ref> The biological pump is not so much the result of a single process, but rather the sum of a number of processes each of which can influence biological pumping. The pump transfers about 11 billion tonnes of carbon every year into the ocean's interior. An ocean without the biological pump would result in atmospheric CO<sub>2</sub> levels about 400 [[Parts per million|ppm]] higher than the present day.<ref>{{cite journal |last1=Sanders |first1=Richard |last2=Henson |first2=Stephanie A. |last3=Koski |first3=Marja |last4=De La Rocha |first4=Christina L. |last5=Painter |first5=Stuart C. |last6=Poulton |first6=Alex J. |last7=Riley |first7=Jennifer |last8=Salihoglu |first8=Baris |last9=Visser |first9=Andre |last10=Yool |first10=Andrew |last11=Bellerby |first11=Richard |last12=Martin |first12=Adrian P. |title=The Biological Carbon Pump in the North Atlantic |journal=Progress in Oceanography |date=December 2014 |volume=129 |pages=200–218 |doi=10.1016/j.pocean.2014.05.005 |bibcode=2014PrOce.129..200S }}</ref><ref>{{cite journal |last1=Boyd |first1=Philip W. |title=Toward quantifying the response of the oceans' biological pump to climate change |journal=Frontiers in Marine Science |date=13 October 2015 |volume=2 |doi=10.3389/fmars.2015.00077 |doi-access=free }}</ref><ref name=Basu2018>{{cite journal |last1=Basu |first1=Samarpita |last2=Mackey |first2=Katherine |title=Phytoplankton as Key Mediators of the Biological Carbon Pump: Their Responses to a Changing Climate |journal=Sustainability |date=19 March 2018 |volume=10 |issue=3 |pages=869 |doi=10.3390/su10030869 |doi-access=free }}</ref>

Most carbon incorporated in organic and inorganic biological matter is formed at the sea surface where it can then start sinking to the ocean floor. The deep ocean gets most of its nutrients from the higher [[water column]] when they sink down in the form of [[marine snow]]. This is made up of dead or dying animals and microbes, fecal matter, sand and other inorganic material.<ref name=Steinberg2002>{{cite journal |last1=Steinberg |first1=Deborah K |last2=Goldthwait |first2=Sarah A |last3=Hansell |first3=Dennis A |title=Zooplankton vertical migration and the active transport of dissolved organic and inorganic nitrogen in the Sargasso Sea |journal=Deep Sea Research Part I: Oceanographic Research Papers |date=August 2002 |volume=49 |issue=8 |pages=1445–1461 |doi=10.1016/S0967-0637(02)00037-7 |bibcode=2002DSRI...49.1445S }}</ref>

The biological pump is responsible for transforming [[dissolved inorganic carbon]] (DIC) into organic biomass and pumping it in [[particulate organic carbon|particulate]] or dissolved form into the deep ocean. Inorganic nutrients and carbon dioxide are fixed during photosynthesis by phytoplankton, which both release [[dissolved organic matter]] (DOM) and are consumed by herbivorous zooplankton. Larger zooplankton - such as [[copepod]]s, [[egest]] [[fecal pellet]]s - which can be reingested, and sink or collect with other organic detritus into larger, more-rapidly-sinking aggregates. DOM is partially consumed by bacteria and respired; the remaining [[refractory DOM]] is [[advected]] and mixed into the deep sea. DOM and aggregates exported into the deep water are consumed and respired, thus returning organic carbon into the enormous deep ocean reservoir of DIC.<ref name=Ducklow2001 />

A single phytoplankton cell has a sinking rate around one metre per day. Given that the average depth of the ocean is about four kilometres, it can take over ten years for these cells to reach the ocean floor. However, through processes such as coagulation and expulsion in predator fecal pellets, these cells form aggregates. These aggregates have sinking rates orders of magnitude greater than individual cells and complete their journey to the deep in a matter of days.<ref name=Rocha2006>{{cite book |last1=de la Rocha |first1=C.L. |chapter=The Biological Pump |pages=83–111 |chapter-url={{GBurl|BnZ77tb18UEC|p=83}} |editor1-last=Elderfield |editor1-first=H. |title=The Oceans and Marine Geochemistry |date=2006 |publisher=Elsevier |isbn=978-0-08-045101-5 }}</ref>

About 1% of the particles leaving the surface ocean reach the seabed and are consumed, respired, or buried in the sediments. The net effect of these processes is to remove carbon in organic form from the surface and return it to DIC at greater depths, maintaining a surface-to-deep ocean gradient of DIC. [[Thermohaline circulation]] returns deep-ocean DIC to the atmosphere on millennial timescales. The carbon buried in the sediments can be [[subducted]] into the [[earth's mantle]] and stored for millions of years as part of the slow carbon cycle (see next section).<ref name=Ducklow2001>{{cite journal |last1=Ducklow |first1=Hugh |last2=Steinberg |first2=Deborah |last3=Buesseler |first3=Ken |title=Upper Ocean Carbon Export and the Biological Pump |journal=Oceanography |date=2001 |volume=14 |issue=4 |pages=50–58 |doi=10.5670/oceanog.2001.06 |doi-access=free }}{{Creative Commons text attribution notice|cc=by4|url=|author(s)=|vrt=|from this source=yes}}</ref>

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===Viruses as regulators===
Viruses act as "regulators" of the fast carbon cycle because they impact the material cycles and energy flows of [[food web]]s and the [[microbial loop]]. The average contribution of viruses to the Earth ecosystem carbon cycle is 8.6%, of which its contribution to marine ecosystems (1.4%) is less than its contribution to terrestrial (6.7%) and freshwater (17.8%) ecosystems. Over the past 2,000 years, anthropogenic activities and climate change have gradually altered the regulatory role of viruses in ecosystem carbon cycling processes. This has been particularly conspicuous over the past 200 years due to rapid industrialization and the attendant population growth.<ref name="Gao2022"/>

[[File:Viral impacts on ecosystem carbon cycles.jpg|thumb|upright=3|left|Comparison of how virus regulate the carbon cycle in terrestrial ecosystems (left) and in marine ecosystems (right). Arrows show the roles viruses play in the traditional food web, the microbial loop and the carbon cycle. Light green arrows represent the traditional food web, white arrows represent the microbial loop, and white dotted arrows represent the contribution rate of carbon produced by [[Lysis|viral lysing]] of bacteria to the ecosystem [[dissolved organic carbon]] (DOC) pool. Freshwater ecosystems are regulated in a manner similar to marine ecosystems, and are not shown separately. The microbial loop is an important supplement to the classic food chain, wherein dissolved organic matter is ingested by [[heterotrophic]] "[[planktonic]]" bacteria during [[secondary production]]. These bacteria are then consumed by [[protozoa]], [[copepod]]s and other organisms, and eventually returned to the classical food chain.<ref name="Gao2022" />]]

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