APPLICATION OF THE SEQUENTIAL EXTRACTION PROCEDURE FOR TRACE METALS SPECIATION IN SEDIMENTS AND DUMP MATERIALS (EAST MARITSA BASIN, BULGARIA)

The selective sequential extraction procedure using the five-stage Tessier protocol was applied to study 2 samples of clayey sediments and 4 samples of clayey dump materials from East Maritsa Basin, Bulgaria. The study showed significantly different trends for the trace metals Cr, Ni, Co, V, Mo, Cu, Pb, and Zn distribution. It indicates that the elements are present unevenly in the sediments and dump materials, and hints the chemical affinity of the elements to various constituents. The results obtained suggest that the trace metals (except Pb) in the samples studied are bound mainly to the aluminosilicate phases. Lead shows different from the other elements behaviour; it is present mainly in carbonate and oxidizable (sulphide and organic matter) fractions. The second dominant phase and the third one is a carbonate fraction in exchange with the oxidizable fraction. A significant proportion of Ni, Zn, Co, Mo, and Pb in a small extent is present as water-soluble and exchangeable species in the samples studied. These elements could be released by desorption and ion-exchange reactions in the surface environment.