Marine geochemistry of cadmium

Abstract

A detailed study of particulate and dissolved cadmium distributions on 83 seawater samples from six profiles in the open North Atlantic Ocean showed a relatively homogenous distribution. The mean concentration of cadmium was 60 ± 27 ng/kg and the median concentration of particulate cadmium was 0.2 ng/kg. Although there are regional differences in dissolved cadmium concentrations among stations, it is suggested that cadmium behaves essentially as an inert element in sea water. Particulate cadmium is enriched by about a factor of four in samples from less than 400 m compared to samples from deeper than 1000 m. The high concentrations in surface waters are suggested to be due to aeolian transport of anthropogenically derived cadmium. Additional analyses of cadmium in the Gulf of Maine show a mean value of 230 ng/kg. The higher values in the Gulf of Maine are ascribed to the influence of continental runoff. Twelve sediment samples from the open North Atlantic show a relatively homogenous distribution, ranging from 0.13 to 0.21 ppm on a dry-weight basis.