Synthesis & Modeling Project
Kitack Lee

Frank J. Millero
Richard A. Feely
Rik Wanninkhof

Degree of saturation state of CaCO3 in the oceans


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 CO2 concentration due to burning of fossil fuels is likely to reduce the concentration of surface water of carbonate ion (CO32-) 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 ([CO32-]) 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 [CO32-] 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"


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

Frank J. Millero
University of Miami
4600 Rickenbacker Causeway
Miami, FL 33149
tel: (305) 361-4707
fax: (305) 361-4144

Richard A. Feely
7600 Sand Point Way NE
Seattle, WA 98115
tel : (206) 526-6214
fax : (206) 526-6744

Rik Wanninkhof
4301 Rickenbacker Causeway
Miami, FL 33149
tel: (305) 361-4379
fax: (305) 361-4392