Fluxes of selected trace metals from the Seine estuary to the eastern English Channel during the period August 1994 to July 1995

Two sampling cruises conducted in the Seine estuary (France) under low-wate r and flood conditions produced high resolution profiles for dissolved cadm ium, lead, copper, zinc and nickel concentrations versus salinity. The dist ribution of dissolved trace metals differed depending on hydrologic conditi ons, partly because of the dilution of upstream inputs during flood periods , Daily fluxes of these dissolved trace metals were estimated for the two s ampling periods (September 1994 and February 1995) by extrapolating the dil ution lines observed in higher salinity waters to salinity = 0 and then mul tiplying the effective freshwater concentrations thus obtained by the corre sponding freshwater flow. Several procedures were subsequently applied to d educe each daily flux for the year studied from data for these two periods. A consensus was found among these procedures, allowing the determination o f net fluxes of dissolved trace metals with a precision of 20-35 %, The net fluxes thus estimated were 4 T yr(-1) for Cd, 4 T yr(-1) for Pb, 40 T yr(- 1) for Cu, 130 T yr(-1) for Zn and 50 T yr(-1) for Ni. (C) 1999 Elsevier Sc ience Ltd. All rights reserved.