杭州蔬菜基地重金属污染及风险评价

为掌握杭州市蔬菜基地土壤中重金属污染状况,采用野外调查结合室内分析法,就杭州市10个区县30个蔬菜基地中203个土壤样品进行了Cu、Zn、Pb、Cd、Cr、As和Ni含量的分析及评价,并就重金属含量与土壤理化指标进行了相关分析.结果表明,杭州市菜地土壤中Zn、Cr、As、Ni含量均未超标,但部分土壤中Cu、Pb和Cd含量有超标现象.污染指数评价表明,杭州市菜地土壤重金属综合污染等级多为轻度污染,且主要以Cd污染为主.累积评价表明,杭州市菜地土壤重金属多呈中高度累积,亦主要由土壤Cd累积所致.潜在生态风险评价表明,杭州市菜地土壤中Cu、Zn、Pb、Cr、As和Ni的生态风险轻微,综合潜在生态风险处于中等水平,但Cd存在较强的潜在生态风险.相关分析表明,土壤中Cu、Zn、Pb、As、Cd含量受土壤理化性质影响较大.综上,杭州市要做好菜地土壤重金属的污染防治工作,尤其要防范Cd的污染风险.

Evaluation on Heavy Metal Pollution and Its Risk in Soils from Vegetable Bases of Hangzhou

With the purpose of investigation on heavy metal contamination in soils from vegetable bases of Hangzhou, adopting field investigation and indoor analysis methods, the contents of heavy metals as Cu, Zn, Pb, Cd, Cr, As and Ni, together with their relevance to the physicochemical properties of the 203 soils from 30 vegetable bases in 10 districts of Hangzhou were studied. The results showed that the contents of heavy metals such as Zn,Cr,As,Ni generally didn''t exceed the standard, while the contents of heavy metals such as Cu, Pb, Cd exceeded it. The results from synthetic pollution evaluation showed that the soils were slightly polluted in soils from vegetable bases of Hangzhou, which were mainly caused by Cd pollution. Furthermore, there was slight potential ecological hazard for Cu, Zn, Pb, Cr, As and Ni but strong potential ecological hazard for Cd, and medium comprehensive ecological hazard as a whole for all the heavy metals in soils from vegetable bases of Hangzhou. The correlation analysis indicated that the contents of Cu, Zn, Pb, As, Cd were greatly influenced by the soil physicochemical property. Thus, measures must be taken for the prevention and controlling of heavy metal pollution in the soils from vegetable bases in Hangzhou, especially for that of Cd.