Inter-annual variability of trace elements in seawater from the western Ross Sea, Antarctica

Total dissolved content of some trace elements (Cd, Cr, Cu, Mn, Pb, Zn), nutrients (nitrate, phosphate and silicate), fluorescence, salinity, dissolved oxygen and temperature were measured on several samples collected during 2 oceanographic surveys from 2001 to 2003 within the framework of the Italian expedition in Antarctica on board the R.V. Italica. The mean concentrations measured are consistent with literature data for seawater at high latitude. The concentration value of some elements, never detected in high latitude seawater before, were compared with the expected values for oceanic water: the results are in agreement with literature data. As for all the oceans, also in the Ross sea the relationship between Cd and phosphate is evident. Some trace elements like copper, cadmium and zinc may have the double role of micronutrient and toxicant. The geochemical cycle of some trace elements, like manganese, is principally controlled by the oxidation-reduction reaction. The obtained results were discussed taking in account the distribution of such trace elements as a function of the different water masses present during the austral summer in the western sector of the Ross Sea.