Anthropogenic CO 2 in Southern Ocean surface waters: evidence from stable organic carbon isotopes

• Published in: Terra Nova
• Main Authors: Fischer, G., Schneider, R., Müller, P. J., Wefer, G.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1997
• Subjects: Southern Ocean
• Online Access: http://dx.doi.org/10.1046/j.1365-3121.1997.d01-29.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1365-3121.1997.d01-29.x; https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-3121.1997.d01-29.x

We present an approach for tracing the fate of anthropogenic CO 2 , compiling a large data set of stable organic carbon isotope ratios from surface sediments, plankton, and sinking matter in the Atlantic Ocean. The δ 13 C values of sinking matter are generally lower by 0.5–4.6‰ compared to the surface sediments. This difference increases with increasing latitude, which is explained by a stronger modern increase in surface water [CO 2 (aq)] in the Southern Ocean relative to the Tropical/Subtropical Ocean. Preindustrial dissolved CO 2 concentrations in Atlantic surface waters, estimated from the δ 13 C org of surface sediments, are compared to recently measured surface water [CO 2 (aq)] values taken from literature. We obtain only a slight increase in [CO 2 (aq)] at lower latitudes but a significant change of about 7 ± 2 μ m in high latitudinal surface waters which we attribute to anthropogenic perturbation. Our results suggest that CO 2 released by human activities has been stored in Southern Ocean surface waters.