Comparison of three sequential extraction procedures for trace element partitioning in three contaminated Mediterranean soils.

The sequential extraction procedures described by Tessier et al., McGrath and Cegarra, and Gimeno-García et al. were compared to investigate trace element (As, Cr, Cu, Pb, and Zn) partitioning patterns and extraction efficiency in three contaminated soils from Mediterranean regions of Spain. Soils were selected from Onda (Castellón) (S1), Aznalcóllar (Sevilla) (S2), and Silla (Valencia) (S3). S1 was a soil contaminated with Pb and Zn after dumping of wastes from the manufacture of ceramic tiles, S2 was polluted accidentally with a highly acid and As-concentrated sludge from mining activities, and S3 was a soil with a high Cr content from tannery sludge disposal. Trace element distribution in the soils--soluble, exchangeable, organically bound, precipitated with carbonates, bound to iron and manganese oxides, and precipitated with sulfides fractions--varied significantly according to the extraction procedure used. In addition, different extraction efficiencies were found for the three sequential extraction procedures compared. Finally, the trace elements studied showed different and specific distribution patterns between the various soil fractions examined.