Fractionation and sequential extraction of heavy metals in the soil of scrapyard of discarded vehicles.

Chemical and physical size fractionation of heavy metals were carried out on 20 soil samples from the scrap yard area. Tessier method was used in sequential extraction. Cadmium showed the highest levels among the other elements studied in the exchangeable fraction (about 33%), while other elements showed low levels in this fraction (> or =1%). Lead and manganese were mostly found in the Fe-Mn oxide fraction, zinc and iron were mostly in residual fraction, while copper was mostly found in the organic fraction of the soil. Soil samples were size-fractionated into four sizes: 1000-500, 500-125, 125-53, and less than 53 microm. The highest levels of Fe, Cu, Pb, Mn, and Cd were found in the medium fraction (500-125 mum), while zinc showed its highest levels in the fine fraction (125-53 microm). The order of heavy metal load in the size fractions was found to be medium > fine > coarse > silt for Fe, Mn, Cu, Pb, and Cd, where it was found as fine > medium > coarse > silt for zinc.