image: This is the anthropogenic fraction of the total calcite dissolution at the seafloor in 2002. view more
Credit: Olivier Sulpis
A study explores human impacts on the composition of deep-sea sediments and, consequently, the geological record. Dissolution of calcium carbonate (CaCO3) from sediments on the seafloor converts excess carbon dioxide (CO2) in the ocean into bicarbonate, preventing runaway ocean acidification and regulating atmospheric CO2 levels over timescales of centuries to millennia. Numerous examples exist in the geological record of increased CaCO3 dissolution in response to ocean acidification. Olivier Sulpis, Bernard Boudreau, and colleagues compared preindustrial and modern seafloor dissolution rates to estimate the impact of anthropogenic CO2 on dissolution rates. The authors estimated the spatial distributions of the rates based on databases of dissolved inorganic carbon in the deep ocean, the CaCO3 content of sediments, and sea-bottom current speeds, and a model of carbonate ion transport across the sediment-water interface. The difference between present-day and preindustrial dissolution rates corresponds to the anthropogenic contribution to dissolution. Although this difference was minimal throughout most of the oceans, the authors identified localized hot spots of pronounced anthropogenic dissolution, most notably in the western North Atlantic Ocean, where the anthropogenic component contributed 40-100% of the total dissolution rate. Additional hot spots were found in the southern Atlantic, Indian, and Pacific Oceans, in locations reflecting high anthropogenic CO2 intrusions and fast bottom currents. According to the authors, the results provide evidence of a significant anthropogenic contribution to CaCO3 dissolution at the seafloor, suggesting that human activity is altering the deep-sea geological record.
Article #18-04250: "Current CaCO3 dissolution at the seafloor caused by anthropogenic CO2," by Olivier Sulpis et al.
MEDIA CONTACT: Olivier Sulpis, McGill University, Montreal, CANADA; tel: 438-926-7009; e-mail: olivier.sulpis@mcgill.ca; Bernard P. Boudreau, Dalhousie University, Halifax, CANADA; tel: 902-494-8895; e-mail: bernie.boudreau@dal.ca
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Journal
Proceedings of the National Academy of Sciences