Pollutant lead sources and deposition in the western mediterranean

Long term measurements of atmospheric fluxes of contaminants such as lead are difficult to sustain in terms of logistic and experimental strategy. We collected a soil core in the Camargue (Rhone Delta) and used multiple geochemical tracers (²¹⁰Pb, ²³⁹Pu, ²³⁹Pu and stable lead isotopes) to estimate the atmospheric supply of pollutant lead at 93 μg.cm^-2). We compared this inventory to pollutant lead inventorie in sediment cores from the Gulf of Lions continental margin and the Alboran Sea. The results showed the atmospheric value in the former area while the latter area showed enhanced inventories. We hypothesize that the large inventory in the Alboran Sea is due to specific hydrographic conditions (including up-welling and a geostrophic front) in this region of the Western Mediterranean that result in enhanced scavenging of lead and other reactive tracers. Despite these different level of accumulations, lead isotope imprints in surficial sediments demonstrate the dominance of atmospheric deposition to the sites.