AN OCEANOGRAPHIC EXPLANATION FOR THE APPARENT CARBON ISOTOPE-CADMIUM DISCORDANCY IN THE GLACIAL ANTARCTIC

The seeming discordance between the glacial to interglacial changes in the carbon isotope ratio and cadmium content of benthic foraminifera from the deep Antarctic has cast a shadow on the reliability of these proxies as valid of paleocirculation indicators. The problem is that while cadmium content shows little glacial to interglacial change [Lea and Boyle, 1990; Boyle, 1992], the carbon isotope change is larger than at any other place in the ocean [Curry et al., 1988; Ïññü et al., 1990;Charles and Fairbanks, 199O]. Even after correction for the 0.35‰ glacial to interglacial change in the isotope ratio for mean ocean‐atmosphere carbon, a difference of 0.5 to 0.6‰ remains. On the basis of Redfield ratios for today's ocean, this is equivalent to a 25% increase in cadmium content which is not seen. This puzzle has been with us for several years. Copyright 1993 by the American Geophysical Union.