C18 SEP-PAK EXTRACTABLE TRACE-METALS IN WATERS FROM THE GULF OF LIONS

Dissolved trace-metal (Cd, Cu, Fe, Ni and Pb) interactions with C18 Se p-Pak extractable organic matter have been investigated in the Rhone m outh and in the Gulf of Lions in July 1989. Pb and Cd do not show any complexation while Ni and Fe are slightly complexed in surface waters near the Rhone mouth. Up to 40% of total dissolved Cu is complexed by the extractable organic matter in coastal waters and, in open sea wate rs a subsurface maximum of 64% of complexed Cu was observed, apparentl y linked to the maximum of primary production. Our results combined wi th other data on the same area suggest that in the euphotic zone of th e western Mediterranean Sea, organic matter directly connected to prim ary production and associated degradation processes is contributing to this complexation as well as to the enrichment of colloidal fraction and the increase of the discrepancy between concentrations of dissolve d organic carbon according to the method of Sugimura and Suzuki (1988) and by traditional techniques.