Study of sediments can provide valuable data to assess the degree of sea water pollution. Herein, we investigate two toxic elements: cadmium and lead. Their analysis requires a highly-sensitive analytical method. ETAAS, with a thermal program adapted to the nature of the sample, has been used. The determination of the total amount of metals does not provide data to indicate the risk of toxicity, or even to understand the various geochemical processes. For these reasons, chemical fractionating (or speciation) is now widely used. It is important to determinate the sediment fractions with which the metals are associated. In this study, a comparison of three and five-step sequential extraction schemes has been established. For ETAAS, the use of calibration curves and thermal programs for each fraction is necessary to give satisfactory results. The procedures of analysis is applied to Pb and Cd in two reference sediments with certified total Pb and Cd content and to different sediments from ports of the Gulf of Tunis. The results show that the three step sequential extraction gives better recoveries.
N. Mzoughi, A. El Abed, M.S. Medimagh
Sequential extraction, ETAAS, lead, cadmium, marine sediments