Editing Carbon cycle (section)

=== 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>
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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" />