Heavy metals in sediments of the Venice Lagoon

Abstract

The horizontal distributions (ppmfdry weight) of Hg, Pb, Zn, Cd, Cu, Fe, Ni, Co and Cr in the sediments of the Venice Lagoon indicate that the source of these metals is the Marghera industrial zone.The highest concentrations of Hg (3.46 ppm), Pb (164 ppm), Co (199.8 ppm), Cu (180 ppm), Zn (3000 ppm) and Cd (20.8 ppm) are found in the lagoon area between Venice and the Marghera industrial area.White Hg seems to be transported mainly in association with particles, soluble species of Fe, Zn and Cu presumably responsible for the high concentrations in the south-western part of the lagoon, where high organic carbon levels have also been observed.Chromium does not originate from local industries, but enters the lagoon from the sea, transported by tidal currents.Quantitative estima tes of the antropogenic heavy metals in the upper 1 0 cm of the lagoon sediments are: Hg, 35 t; Cd, 200 t; Pb, 1300 t; Cu, 1600 t; Zn, 16 500 t; Fe, 600 000 t; Ni, 240 t; Co, 550 t; Cr, 480 t.