The relationship between δ13C of organic matter and [CO2(aq)] in ocean surface water: Data from a JGOFS site in the northeast Atlantic Ocean and a model

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Rau, G. H., Takahashi, T., Des Marais, D. J., Repeta, D. J., & Martin, J. H. (1992). The relationship between δ13C of organic matter and [CO2(aq)] in ocean surface water: Data from a JGOFS site in the northeast Atlantic Ocean and a model. Geochimica et Cosmochimica Acta, 56(3), 1413-1419.
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TitleThe relationship between δ13C of organic matter and [CO2(aq)] in ocean surface water: Data from a JGOFS site in the northeast Atlantic Ocean and a model
AuthorsG. Rau, T. Takahashi, D. Des Marais, D. Repeta, J. Martin
AbstractThe δ13C of suspended particulate organic matter (SPOM) in surface waters increased from -22.9 to -18.1‰ during April 25-May 31, 1989 at the JGOFS North Atlantic Bloom Experiment Site (NABE Site; 47°N, 20°W). During the same period, nearly parallel increases in sinking POM δ13C were also found, although these values were usually lower than those of the corresponding SPOM. Consistent with the hypothesis that plankton δ13C and [CO2(aq)] are inversely related, the increases in both sinking and suspended POM δ13C were highly negatively correlated with mixed-layer [CO2(aq)] that generally decreased from 10.1-13.2 μmoles/kg during the five weeks. The change in SPOM δ13C per change in [CO2(aq)], however, appears to be somewhat greater than that expected from previous, though less direct, ocean and laboratory evidence. By adapting a model of plant δ13C by Farquhar et al. (1982), it is shown that under a constant phytoplankton demand for CO2 an inverse, nonlinear SPOM δ13C response to ambient [CO2(aq)] is expected. Such trends are unlike the negative linear relationships indicated by data from the NABE Site and or from Southern Hemisphere waters. Such differences between predicted and observed SPOM δ13C vs. [CO2(aq)] trends and among observed relationships can be reconciled, however, if biological CO2 demand is allowed to vary. This has significant implications for the use of the δ13C of plankton (or their organic subfractions or sedimentary remains) as a proxy for past or present ocean CO2 concentrations and biological productivity. © 1992.
JournalGeochimica et Cosmochimica Acta
Date1992
Volume56
Issue3
Start page1413
End page1419
ISSN00167037
Subjectscarbon, carbon dioxide, sea water, article, Atlantic Ocean, chemical model, chemistry, ecosystem, geology, metabolism, NASA Center ARC, NASA Discipline Exobiology, NASA Discipline Number 52-80, NASA Program Exobiology, photosynthesis, physiology, phytoplankton, Carbon Isotopes, Models, Chemical, Seawater, Support, U.S. Gov't, Non-P.H.S., particulate organic matter, Atlantic, (Northeast)
NoteCited By (since 1996):148, Oceanography

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