On the marine geochemistry of cadmium

STUDIES of the geochemistry of trace metals in sea water are of great potential importance, given the wide diversity in their properties. Knowledge of their distribution provides information not only about the specific chemical processes in which they are involved but also about the formation, destruction and diagenesis of the major solid phases in which they become incorporated by biological and authigenic processes. Previous efforts to elucidate the behaviour of cadmium in the ocean have produced no systematic correlations with other oceano-graphic properties¹. At the low levels encountered (< 0.1 parts per 10⁹), problems with analysis and with contamination during sampling can be severe. Recent advances in analytical and handling techniques have led to progress in our understanding of other trace metals^2-4, hence a re-examination of the marine geochemistry of cadmium is now appropriate. This note describes the general distribution of cadmium in the ocean, based on three detailed vertical profiles from the Pacific.