Geochemical proxies foraminifera

In order to estimate paleoceanographic nutrient levels, and thereby explore links between nutrient variability, atmospheric CO2 and climate change, a range of nutrient proxies have been developed. The ratio of cadmium (Cd) to calcium (Ca) in benthic foraminifera has been used as a proxy for dissolved phosphate, based on the observation that dissolved cadmium and phosphate concentrations are linearly correlated in modern oceanic waters (Boyle, 1988). While the basis of the Cd PO4 relationship is not understood, from either a biochemical or geochemical standpoint (e.g., Cullen et al., 2003),... 

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