ANTHROPOGENIC VS LITHOGENIC ORIGINS OF TRACE-ELEMENTS (AS, CD, PB, RB, SB, SC, SN, ZN) IN WATER COLUMN PARTICLES - NORTHWESTERN MEDITERRANEAN-SEA

The distribution of heavy metal was analyzed in water column particles collected in autumn (October 1985) and spring (March 1986) by two ser ies of sediment traps from a mooring located in the northeastern Medit erranean Sea continental slope. Four traps were set, at 50, 100, 300, 600 m depths on the mooring in 645 m deep water in the Lacaze-Duthier canyon. The total metal concentrations were determined by ICP-MS. Resu lts show that Rb and Sc contents display typical shale values. As, Cd, Pb, Sb, Zn, (normalized to Sc) display high enrichment factors (up to 50) over shale compositions. Distinctive temporal variability as well as the respective contributions of local (Tet, Aude) and remote (Rhon e) rivers and Sahara-derived aerosols have been identified. Fluxes of most elements observed in the upper 100 m can be attributed to atmosph eric fluxes. In the deepest traps (300 and 600 m) these fluxes are, ho wever, mostly dominated by riverine particles advected from the contin ental shelf. Most of the trace-element enrichments are more likely to be related to the anthropogenic input, rather than to biological cycli ng. Isotopic composition of lead determined by ICP-MS enabled to evalu ate that the proportion of anthropogenic lead derived from European ga soline consumption ranged between 50 and 100%.