Stabilization of Cadmium- and Lead-Contaminated Sites Using Sodium Tetraethylenepentamine-Multi Dithiocarbamate

Two soil amendments, KH2PO4 and sodium tetraethylenepentamine–multi dithiocarbamate (TEPA/CSSNa), were applied to heavy metal-contaminated sites, and their corresponding stabilization effects were compared. Three kinds of procedures, namely, sequential extraction procedure (SEP), toxicity characteristic leaching procedure (TCLP), and diethylenetriaminepentaacetic acid (DTPA) extraction procedure, were adopted to examine the potential of using TEPA/CSSNa to stabilize Cd and Pb in polluted sites. Simplified bioaccessibility extraction test (SBET) was used to investigate the bioaccessibility of Cd and Pb. TCLP and DTPA results showed that TEPA/CSSNa was more efficient than KH2PO4 in reducing the mobility of Cd and Pb. SBET results indicated that the bioaccessibility of Cd and Pb decreased with increasing dose of TEPA/CSSNa. The mobility rates of Cd and Pb decreased to 0.26 and 0 %, respectively, when using 3 % TEPA/CSSNa. The exchangeable and carbonate fractions of Cd and Pb were gradually converted into organic matter–sulfate compounds. After 1 year, natural aging tests revealed that organic matter–sulfate fractions of Cd and Pb increased and the labile fractions (exchangeable and carbonate fractions) decreased in the treated soil.