贵州黔西北铅锌矿区土壤重金属污染及生物有效性研究

Research on the Heavy Metal Contamination and Bioavailability of Contaminated Soils in Pb-Zn Mining Areas of Northwestern Guizhou Province

对贵州省黔西北铅锌矿区18个矿渣和污染土壤样品中Zn、Pb、Cu、Cd 4种重金属的总量、生物有效态含量以及对应的植物样(根和茎叶)中的重金属含量分别进行了测定,其测定结果表明:土壤中除Cu污染较轻外,Zn、Pb、Cd均大大超过了土壤环境阀值;土壤中重金属生物有效态含量最高为Cd,占总量的50%,对环境构成了潜在威胁;植物中重金属含量与土壤中重金属总量、有效态重金属含量呈现很好的正相关性,植物根中的重金属含量与土壤中有效态重金属含量之间的相关性更为显著,分别为RZn=0.871 3、RCu=0.883 3、RPb=0.783 2、RCd=0.8937,说明土壤中的重金属已经威胁到植物生长,且在植物中产生了富集,因此在评价土壤重金属的生物有效性和环境效应时,应将重金属总量和生物有效态含量结合起来加以研究,并对土壤中重金属的含量与植物中该元素含量之间作相关分析,根据其相关系数的大小来判断其生物有效性的程度。

The total concentrations of four heavy metals of Zn, Pb, Cu and Cd and the bioavailability were measured for 18 soil samples from Pb-Zn mining areas of northwestern Guizhou Province, and the heavy metal contents were also measured for 18 corresponding plant samples. The experiment results show that the total concentrations of Pb, Cd and Zn exceed the maximum of soil environment and that the pollution of Cu is less severe. The bioavailable concentrations are usually 20-30% of the total, with the maximum up to 50% for Cd, which shows obvious variance and potential threats to the environment. The study of heavy metals in plant also shows that the heavy metals in soil have accumulated in plants and threatened their growth. There exist significant correlations between the total heavy metal concentrations of soil samples and those of plant samples, and the significant positive correlations are found between the total heavy metal concentrations of plant samples and the bioavailable metal concentrations of soil samples. The correlations are more positive between the total heavy metal concentrations of plant root samples and the hioavailable metal concentrations of soil samples, and the Pearson correlation coefficients are as follows：Zn（R =0. 871 3 study tween ty and ）, Cu（R=0. 883 3） , Pb（R=0. 783 2） , and Cd（R=0. 893 7）. This indicates it is necessary to bioavailability and total heavy metal concentrations of soil, and make a correlative analysis beheavy metal concentrations of soil samples and those of plants samples to assess the bioavailabiliironmental effects of the heavy metals in soils.