巢湖北部土壤重金属污染特征及生态风险评价

摘要

以巢湖北部为研究对象,分析了165个表层土壤样品中As,Cd,Cr,Cu,Hg,Ni,Pb和Zn含量及污染特征,并与其他地区土壤重金属元素含量进行了对比.利用污染指数法和潜在生态风险指数法对土壤重金属污染和潜在生态风险进行了评价.结果表明,8种重金属平均含量顺序依次为:Cr＞Zn＞Ni＞Pb＞Cu＞As＞Cd＞ Hg,Cd和Hg变异系数较大,且对深层土壤元素有较明显的富集作用.单因子污染指数评价结果显示土壤各重金属均为清洁水平,污染程度依次为:Pb＞ Cr＞As=Ni＞Cu＞Cd＞Zn＞ Hg;综合污染指数表明土壤总体为清洁水平.在8种重金属中,Cd和Hg是研究区土壤重金属处于强生态风险的主要因子,贡献率分别为19.40％和72.87％.%The surface soil in the north of Chaohu was studied and a total of 165 samples were collected and the concentrations and pollution characteristics of As,Cd,Cr,Cu,Hg,Ni,Pb,and Zn were analyzed.The heavy metal concentrations in this area were compared with those of other areas.Then,pollution index and potential ecological risk index were used respectively for assessing the pollution status and ecological risk of soil heavy metals in this area.Results suggest that the average concentrations of eight heavy metals rank as follows:Cr＞Zn＞Ni＞Pb＞Cu＞As＞Cd＞Hg.The coefficent variations of Cd and Hg are higher than the other six heavy metals.Furthermore,higher enrichment coefficients occur also in Cd and Hg when compared with the deep soils.Single factor pollution index indicates that eight heavy metals in the soils of this area are all at a clear level,and the pollution degree is in the following order:Pb ＞Cr＞As=Ni＞Cu＞Cd＞Zn＞ Hg.Accordingly,a clear level in this area is shown by Nemerow integrated pollution index.Calculation of the potential ecological risk index shows that,among the eight tested heavy metals,Cd and Hg are the main potential ecological risk factors,and their contribution is 19.40％ and 72.87 ％,respectively.