Planktonic foraminiferal Cd/Ca: Paleonutrients or paleotemperature?

摘要: Records of Cd/Ca in planktonic foraminiferal calcite Globigerinoides bulloides cores from the Subantarctic region Southern Ocean show large glacial-interglacial variations with lower (by 0.06–0.10 µmol mol−1) at glacial times. Interpretation these records terms dissolved phosphate and inferred higher nutrient utilization has significant implications for atmospheric carbon dioxide (pCO2) draw-down. However, box core-top data G. North Atlantic suggest that incorporation Cd into foraminifera relative to seawater (DCd) is temperature sensitive (DCd=0.637 exp 0.15T). When are corrected this dependence, they little or no diferences. If, as seems likely, observation can be interpreted indicate a minimal change (< 0.5 kg−1) surface water concentrations, then explanation lowered pCO2 must looked elsewhere.