Linking the lithogenic, atmospheric, and biogenic cycles of silicate, carbonate, and organic carbon in the ocean
International audience Geochemical theory describes long term cycling of atmospheric CO 2 between the atmosphere and rocks at the Earth surface in terms of rock weathering and precipitation of sedimentary minerals. Chemical weathering of silicate rocks takes up atmospheric CO 2 , releases cations an...
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ftccsdartic:oai:HAL:hal-04110661v1 2023-11-05T03:44:30+01:00 Linking the lithogenic, atmospheric, and biogenic cycles of silicate, carbonate, and organic carbon in the ocean Smith, S. V. Gattuso, J. -P. Laboratoire d'océanographie de Villefranche (LOV) Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV) Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) 2009 https://hal.science/hal-04110661 https://doi.org/10.5194/bgd-6-6579-2009 en eng HAL CCSD European Geosciences Union info:eu-repo/semantics/altIdentifier/doi/10.5194/bgd-6-6579-2009 hal-04110661 https://hal.science/hal-04110661 BIBCODE: 2009BGD.6.6579S doi:10.5194/bgd-6-6579-2009 ISSN: 1810-6277 EISSN: 1810-6285 Biogeosciences Discussions https://hal.science/hal-04110661 Biogeosciences Discussions, 2009, 6, pp.6579-6599. ⟨10.5194/bgd-6-6579-2009⟩ [SDU]Sciences of the Universe [physics] info:eu-repo/semantics/article Journal articles 2009 ftccsdartic https://doi.org/10.5194/bgd-6-6579-2009 2023-10-07T22:34:05Z International audience Geochemical theory describes long term cycling of atmospheric CO 2 between the atmosphere and rocks at the Earth surface in terms of rock weathering and precipitation of sedimentary minerals. Chemical weathering of silicate rocks takes up atmospheric CO 2 , releases cations and HCO 3 - to water, and precipitates SiO 2 , while CaCO 3 precipitation consumes Ca 2+ and HCO 3 - and releases one mole of CO 2 to the atmosphere for each mole of CaCO 3 precipitated. At steady state, according to this theory, the CO 2 uptake and release should equal one another. In contradiction to this theory, carbonate precipitation in the present surface ocean releases only about 0.6 mol of CO 2 per mole of carbonate precipitated. This is a result of the buffer effect described by Ψ, the molar ratio of net CO 2 gas evasion to net CaCO 3 precipitation from seawater in pCO 2 equilibrium with the atmosphere. This asymmetry in CO 2 flux between weathering and precipitation would quickly exhaust atmospheric CO 2 , posing a conundrum in the classical weathering and precipitation cycle. While often treated as a constant, Ψ actually varies as a function of salinity, pCO 2 , and temperature. Introduction of organic C reactions into the weathering-precipitation couplet largely reconciles the relationship. ψ in the North Pacific Ocean central gyre rises from 0.6 to 0.9, as a consequence of organic matter oxidation in the water column. ψ records the combined effect of CaCO 3 and organic reactions and storage of dissolved inorganic carbon in the ocean, as well as CO 2 gas exchange between the ocean and atmosphere. Further, in the absence of CaCO 3 reactions, Ψ would rise to 1.0. Similarly, increasing atmospheric pCO 2 over time, which leads to ocean acidification, alters the relationship between organic and inorganic C reactions and carbon storage in the ocean. Thus, the carbon reactions and ψ can cause large variations in oceanic carbon storage with little exchange with the atmosphere. Article in Journal/Newspaper Ocean acidification Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
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Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
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ftccsdartic |
language |
English |
topic |
[SDU]Sciences of the Universe [physics] |
spellingShingle |
[SDU]Sciences of the Universe [physics] Smith, S. V. Gattuso, J. -P. Linking the lithogenic, atmospheric, and biogenic cycles of silicate, carbonate, and organic carbon in the ocean |
topic_facet |
[SDU]Sciences of the Universe [physics] |
description |
International audience Geochemical theory describes long term cycling of atmospheric CO 2 between the atmosphere and rocks at the Earth surface in terms of rock weathering and precipitation of sedimentary minerals. Chemical weathering of silicate rocks takes up atmospheric CO 2 , releases cations and HCO 3 - to water, and precipitates SiO 2 , while CaCO 3 precipitation consumes Ca 2+ and HCO 3 - and releases one mole of CO 2 to the atmosphere for each mole of CaCO 3 precipitated. At steady state, according to this theory, the CO 2 uptake and release should equal one another. In contradiction to this theory, carbonate precipitation in the present surface ocean releases only about 0.6 mol of CO 2 per mole of carbonate precipitated. This is a result of the buffer effect described by Ψ, the molar ratio of net CO 2 gas evasion to net CaCO 3 precipitation from seawater in pCO 2 equilibrium with the atmosphere. This asymmetry in CO 2 flux between weathering and precipitation would quickly exhaust atmospheric CO 2 , posing a conundrum in the classical weathering and precipitation cycle. While often treated as a constant, Ψ actually varies as a function of salinity, pCO 2 , and temperature. Introduction of organic C reactions into the weathering-precipitation couplet largely reconciles the relationship. ψ in the North Pacific Ocean central gyre rises from 0.6 to 0.9, as a consequence of organic matter oxidation in the water column. ψ records the combined effect of CaCO 3 and organic reactions and storage of dissolved inorganic carbon in the ocean, as well as CO 2 gas exchange between the ocean and atmosphere. Further, in the absence of CaCO 3 reactions, Ψ would rise to 1.0. Similarly, increasing atmospheric pCO 2 over time, which leads to ocean acidification, alters the relationship between organic and inorganic C reactions and carbon storage in the ocean. Thus, the carbon reactions and ψ can cause large variations in oceanic carbon storage with little exchange with the atmosphere. |
author2 |
Laboratoire d'océanographie de Villefranche (LOV) Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV) Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) |
format |
Article in Journal/Newspaper |
author |
Smith, S. V. Gattuso, J. -P. |
author_facet |
Smith, S. V. Gattuso, J. -P. |
author_sort |
Smith, S. V. |
title |
Linking the lithogenic, atmospheric, and biogenic cycles of silicate, carbonate, and organic carbon in the ocean |
title_short |
Linking the lithogenic, atmospheric, and biogenic cycles of silicate, carbonate, and organic carbon in the ocean |
title_full |
Linking the lithogenic, atmospheric, and biogenic cycles of silicate, carbonate, and organic carbon in the ocean |
title_fullStr |
Linking the lithogenic, atmospheric, and biogenic cycles of silicate, carbonate, and organic carbon in the ocean |
title_full_unstemmed |
Linking the lithogenic, atmospheric, and biogenic cycles of silicate, carbonate, and organic carbon in the ocean |
title_sort |
linking the lithogenic, atmospheric, and biogenic cycles of silicate, carbonate, and organic carbon in the ocean |
publisher |
HAL CCSD |
publishDate |
2009 |
url |
https://hal.science/hal-04110661 https://doi.org/10.5194/bgd-6-6579-2009 |
genre |
Ocean acidification |
genre_facet |
Ocean acidification |
op_source |
ISSN: 1810-6277 EISSN: 1810-6285 Biogeosciences Discussions https://hal.science/hal-04110661 Biogeosciences Discussions, 2009, 6, pp.6579-6599. ⟨10.5194/bgd-6-6579-2009⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.5194/bgd-6-6579-2009 hal-04110661 https://hal.science/hal-04110661 BIBCODE: 2009BGD.6.6579S doi:10.5194/bgd-6-6579-2009 |
op_doi |
https://doi.org/10.5194/bgd-6-6579-2009 |
_version_ |
1781704527425044480 |