[Assessment of toxicity of heavy metal contaminated soils by toxicity characteristic leaching procedure].

The contents of heavy metals (Cu, Zn, Pb and Cd) in soils from a lead-zinc mine in Shangyu, Zhejiang Province, China, were analyzed and their toxicity was assessed by toxicity characteristic leaching procedure (TCLP), which was developed by US EPA. The TCLP method is a currently recognized international method for evaluation of heavy metal pollution in soils. The available levels of Cu, Zn, Pb and Cd were 8.2-36 mg x kg(-1), 23-143 mg x kg(-1), 6.4-1367 mg x kg(-1) and 0.41-2.2 mg x kg(-1), respectively, while the international standard were 15 mg x kg(-1), 25 mg x kg(-1), 5 mg x kg(-1) and 0.5 mg x kg(-1), respectively. The results show that soils around the mine are polluted with heavy metals Cu, Zn, Pb and Cd, especially polluted by Zn and Pb, followed by Cd and Cu. Moreover, the heavy metals in the soils extracted by TCLP indicate that fluid 2 is more effective than fluid 1 in extracting the heavy metals from the polluted soils and there is a positive correlation between fluid 1 and fluid 2. The contents of available heavy metals by TCLP are correlated with contents of total heavy metals.