浙北嘉善地区土壤重金属空间分布特征与污染评价

Chemical Speciation and Evaluation of Some Heavy Metal in Jiashan,Zhejiang Province

本文对浙江省嘉善县基本农田中重金属元素含量及部分元素的形态进行了分析测定,结果表明,嘉善表层土壤中,Cd,Cu,Hg,Ni,Zn等元素含量与嘉兴市、浙北区相比较高,As较嘉兴市低、比浙北高,Cr与嘉兴市相近但高于浙北区,Pb与嘉兴市、浙北背景值相近;不同类型土壤中重金属含量不同;Hg、Cr主要以残渣态存在,而As、Cd主要以有效态存在;综合污染评价显示,嘉善县表层土壤主要为轻度污染区,占80.0%,无污染区零星出现,占9.15%,中度污染区在西塘工业区和魏塘的设施农业区具较大面积出现,占9.31%,重度污染区主要在西塘工业区,占评价区的1.5%;嘉善基本农田区生态风险较大的元素为As、Cd、Ni等,应引起足够重视,Hg虽然全量较高,由于其主要以残渣态存在,生态风险并不大。

Samples were collected from agricultural soils in Jiashan,Zhejiang Province.By measuring the concentrations of heavy metals and revealing the chemical speciation distribution,it is concluded that the concentrations of Cd,Cu,Hg,Ni,and Zn in Jiashan are higher than those in Jiaxing and the north of Zhejiang Province.Meanwhile the concentrations of As are between Jiaxing and North Zhejiang Province;the concentrations of Cr in JIashan are highest,and the concentrations of Pb in these areas are almost the same.Also the values differ in different types of soils.Hg and Cr occur in the form of residues,whereas As and Cd occur in the form of available state.Integrated pollution evaluation shows that the surface soil in Jiashan was dominantly slightly polluted,accounting for 80.0% of the total region.The remaining region is free from pollution or of moderate or serious pollution,which accounts for 9.15%,9.31% and 1.5%,respectively.The region that was moderately polluted is located in the Xitang Industrial Garden and Weitang Farming Area,while the most seriously polluted region is located in the Xitang Industrial Garden.Attention should be paid to As and Cd,especially Ni,for they had some potential ecological risks.Though Hg is of high concentration,it is has a poor ecological risk because of its residual state.