U.S. JGOFS SMP

U.S. JGOFS Synthesis & Modeling Project
Kitack Lee Collaborators: Frank J. Millero Richard A. Feely Rik Wanninkhof
Degree of saturation state of CaCO₃ in the oceans NOAA/DOE OACES, 2 years
PROJECT DESCRIPTION:	Over the last eight years (1990-1998) a large global database of high quality total alkalinity (TA) and total inorganic carbon (TCO₂) measurements in the Atlantic, Pacific, and Indian Oceans has been obtained through a multi-national and a multi-agency effort for the global CO₂ surveys. The measurement campaigns included parts of the NOAA/OACES, the DOE/WOCE, and the JGOFS CO₂ survey programs. This carbon database is unprecedented in terms of quality (2 mol kg^-1in TA and 1 mol kg^-1 in TCO₂) and spatial coverage. The previous studies on the degree of saturation of CaCO₃ in the oceans (Li et al., 1969; Archer, 1996) using the historical measurements (GEOSECS) suffered from spatially insufficient data coverage, less precise and less accurate carbonate measurements, and inaccurate thermodynamic constants. Therefore, it is worthwhile to revisit this issue with recently collected global carbon data. Another interesting aspect of this proposed research is to examine the effect of oceanic uptake of anthropogenic CO₂ on the degree of saturation state of seawater with respect to aragonite and calcite, since the amount of anthropogenic CO₂ taken up by the oceans since the Industrial Revolution can be detectable with presently available techniques. The rising atmospheric CO₂concentration due to burning of fossil fuels is likely to reduce the concentration of surface water of carbonate ion (CO₃^2-) by about 30% relative to the pre-industrial level as the atmospheric CO₂ concentration doubles the pre-industrial level by the middle of 21st century. A recent pioneering study (Langdon et al., 1998) suggests that changes in the degree of saturation-state of surface seawater with respect to CaCO₃ will reduce calcification rate of coral community proportionally as the concentration of surface carbonate ion ([CO₃^2-]) decreases. If this provocative finding can be extrapolated to all CaCO₃ bearing organisms this would mean that global production of hard tissue would decrease with increasing pCO₂, which in turn might lead to greater oceanic uptake of CO₂. Four tangible goals below will be pursued for the execution period of this proposal: 1. Globally consistent databases for total alkalinity and total inorganic carbon; 2. A critical evaluation of the effect of anthropogenic CO₂ on the calcite and aragonite saturation horizons in the oceans; 3. Construction of a global seawater [CO₃^2-] field; 4. Comparison of the saturation horizon with the compensation depth horizon.
DATA:	- no data submitted -
PUBLICATIONS:	Lee, K. 2001. Global net community production estimated from the annual cycle of surface water total dissolved inorganic carbon. Limnol. Oceanogr. Limnology and Oceanography 46(6): 1287-1297. Lee, K.; Millero, F.J.; Byrne, R.H.; Feely, R.A.; Wanninkhof, R. 2000. The recommended dissociation constants of carbonic acid in seawater, Geophys. Res. Lett. 27: 229-232.
RELATED PROJECTS:	Sabine; Key; Feely; Millero; Wanninkhof; Kozyr "Synthesis and interpretation of the NOAA/DOE global CO2 survey data" Wanninhkof; Wallace; Baringer "Meridional transport of carbon dioxide in the North Atlantic Ocean"
INVESTIGATOR INFORMATION:	Kitack Lee School of Environmental Science and Engineering Pohang University of Science and Technology San 31, Hyoja-dong, Nam-gu Pohang, 790-784 Republic of Korea (formerly NOAA/AOML/OCD) tel: 82-054-279-2285 fax: 82-279-8299 ktl@postech.ac.kr http://www.aoml.noaa.gov/ocd/people/lee/ Frank J. Millero RSMAS/MAC University of Miami 4600 Rickenbacker Causeway Miami, FL 33149 tel: (305) 361-4707 fax: (305) 361-4144 fmillero@rsmas.miami.edu http://www.rsmas.miami.edu/divs/mac/people/fmillero.html Richard A. Feely NOAA/PMEL 7600 Sand Point Way NE Seattle, WA 98115 tel : (206) 526-6214 fax : (206) 526-6744 feely@pmel.noaa.gov Rik Wanninkhof NOAA/AOML 4301 Rickenbacker Causeway Miami, FL 33149 tel: (305) 361-4379 fax: (305) 361-4392 wanninkhof@.aoml.noaa.gov http://www.aoml.noaa.gov/ocd/people/wanninkhof/