EVOLUTION OF CADMIUM AND LEAD CONTENTS IN ANTARCTIC COASTAL SEAWATER DURING THE AUSTRAL SUMMER

The seasonal evolution of the cadmium and lead distribution in the wat er column of the Gerlache Inlet (Ross Sea) was studied during the 1990 -91 austral summer. Measurements were carried out by Anodic Stripping Voltammetry in Antarctica immediately after the collection and filtrat ion of samples. The concentrations of both metals were homogeneous bef ore the phytoplankton bloom with mean values of 0.71 (SD 0.10) and 0.1 16 (SD 0.014) nmol/l for cadmium and lead respectively. A subsequent d epletion in metal concentration was observed in the shallow waters. Th e surface concentration of cadmium decreased to about 0.1 nmol/l at th e end of the season. The vertical distribution of lead was less affect ed by the seasonal evolution and the mean surface concentration decrea sed to 0.044 nmol/l in the same period. The results are evaluated with respect to physical and biological processes in the area examined and compared with those obtained on previous expeditions in the same area .