TCLP法评价矿区土壤重金属的生态环境风险

对浙江上虞某铅锌矿区中污染土壤的重金属(Cu、Zn、Pb、Cd)含量进行分析测定,采用美国最新的法定重金属污染评价方法TCLP(Toxicitycharacteristicleachingprocedure)法对土壤重金属污染状况进行评价,以国际规定的TCLP法标准评价重金属生态环境风险.结果表明:土壤中Cu、Zn、Pb、Cd的有效含量分别在8.2～36mg·kg^-1 、23～143mg·kg^-1 、6.4～1.367mg·kg^-1 和0.41～2.2mg·kg^-1 之间,而与之相对应的国际标准分别为15mg·kg^-1、25mg·kg^-1、5mg·kg^-1 和0.5mg·kg^-1,因此这个矿区附近土壤不同程度地受到Cu、Zn、Pb、Cd的污染,其中以Zn、Pb污染最为严重,其次为Cd ,而Cu的污染程度最轻.此外,用TCLP试剂提取土壤中的重金属后表明,TCLP试剂2能更有效地提取土壤中的重金属,并且两者之间存在一定的正相关.TCLP提取液中的重金属浓度与全量之间存在一定的关系.

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.