Analysis of chemical forms of heavy metals in contaminated soil by sequential extraction methods

Abstract

The samples collected from soils and sediments near the mouth of a river (samples A, B, and C), port (sample D), or shooting range (samples E and F) were investigated with Tessier's sequential extraction method to design the remediation process for contaminated sites. This method was chosen to determine the chemical forms of heavy metal contaminants, which consists of five fractions such as 'exchangeable', 'bound to carbonate', 'bound to oxide', 'bound to organic matter', and 'residue'. In the case of samples from sediments near the mouth of a river, zinc (Zn) distributes in the fractions 'bound to oxide' and 'bound to organic matter', while copper is observed in the fractions 'bound to organic matter' and 'residue', respectively. When the sample obtained from the sediment near a port was examined, most of Zn distributes in the fractions 'bound to organic matter' and 'residue'. In sites E and F, lead, Zn, and copper distributed in the fractions 'bound to carbonate' and 'bound to oxide'. On the basis of results, physical treatment followed by chemical leaching for sites A, B, and C, physical separation process for site D, and chemical treatment process for sites E and F would be required to remediate the contaminated sites.