The trace element geochemistry of planktonic foraminifera

The trace element composition of planktonic foraminifera provides important information about chemical and physical properties of the surface ocean. Reconstructing glacial-interglacial changes in surface waters lends insight into the mechanisms controlling global climate change. Southern Ocean surface waters play a particularly important role in climate change because they are the link between the atmosphere and the deep ocean carbon reservoir.;Culturing studies with living planktonic foraminifera provide an important means of calibrating the relationship between seawater and shell chemistry, and assessing the reliability of planktonics as recorders of surface water chemical and physical properties. Through culturing experiments with both Orbulina universa and Globigerina bulloides, we have calibrated Cd, Mg and Sr uptake. Cd experiments suggest that G. bulloides is a more reliable recorder of seawater Cd concentrations than O. universa. The partition coefficient for Cd uptake (D;Multi-element analysis of fossil Globigerina bulloides and Neogloboquadrina pachyderma (s) from Southern Ocean cores RC11-120 and E11-2 indicate significant glacial-interglacial changes in Subantarctic surface waters. Cd/Ca records suggest that surface water nutrients were 35-70% lower during glacial episodes. Lower glacial nutrients indicates increased efficiency of the biological pump and lends support to the polar nutrient hypothesis. Mg/Ca records indicate that sea surface temperatures were 4...