VERTICAL-DISTRIBUTION OF CADMIUM, COPPER AND LEAD IN THE EASTERN ALBORAN SEA - ENRICHMENT OF METALS IN SURFACE WATERS

The vertical distribution of cadmium, copper and lead was studied in t he 0-500 m layer of the Eastern Alboran Sea. The concentrations measur ed compare favourably with recent data for the neighbouring area (53 p M < Cd < 124 pM; 1.4 nM < Cu < 2.8 nM, and 90 pM < Pb < 310 pM). The a nalysis of six profiles showed the presence. of a sub-surface water ma ss, the northwestern Mediterranean Water (NWMW, 75-300 m), with high c oncentrations of trace metals. Metal-salinity relationships, typified by cadmium, showed that the Atlantic surface waters (ASW) with low met al concentrations before entering the Mediterranean Sea become enriche d with metals from some as yet not clearly understood source near the Straits of Gibraltar. The salinity-Cd relationship, taken together wit h flux rates of salt and Cd, however, shows that the Modified Atlantic water (MAW) gains its high metal concentrations during its transit in the Alboran Sea principally from a mixing with the underlying metal-r ich NWMW.