长江三角洲典型县域耕地土壤重金属污染生态风险评价

Ecological Risk Assessment of Heavy Metal Pollution in Cultivated Soil at Typical County Level in Yangtze River Delta

为全面掌握长江三角洲地区典型县域耕地土壤重金属污染状况与生态风险特征,通过野外实地采样和室内土壤重金属含量化验分析,采用单因子污染指数法、内梅罗综合污染指数法和潜在生态风险指数法对宜兴市县域耕地土壤中As、Cd、Cu、Hg、Pb、Zn 6种重金属元素进行污染和生态风险评价。结果表明,宜兴市耕地土壤重金属土壤污染总体较轻,耕地土壤重金属污染点位超标率为10.27%,Cd、Cu、As、Hg、Pb、Zn的超标率分别为10.11%、0.88%、0.44%、1.49%、0.10%、0.35%,从超标率来看Cd和Hg为宜兴市主要污染元素,其中Cd的样本超标率高于全国耕地Cd的超标率。宜兴市耕地土壤重金属污染总体呈现“轻微”生态风险,生态风险贡献率较高的为Cd,达到57.46%,生态风险等级较高区域为丁蜀镇的东北部、张渚镇的东南部和徐舍镇的东北部区域。宜兴市耕地土壤重金属污染源可能主要来源于人为的化工生产活动。研究可为耕地土壤重金属污染预防控制治理提供理论依据,提高耕地资源安全利用水平。

For a comprehensive understanding of the pollution characteristics and ecological risk of heavy metals of farmland soil in Yingxing County of Yangtze River Delta,China,the cadmium(Cd),arsenic(As),copper(Cu),zinc(Zn),mercury(Hg)and lead(Pb)pollution situations were evaluated by using the single factor index,Nemerow pollution index and Hakanson potential ecological risk index,and the theoretical basis was provided for the safe use of regional cultivated land.The results showed that the heavy metal pollution of cultivated soil in Yixing County was generally light,and 10.27%of the soil samples had heavy metals concentrations higher than the risk screening values for soil contamination of agricultural land.The over standard rates of Cd,Cu,As,Hg,Pb and Zn were 10.11%,0.88%,0.44%,1.49%,0.10%and 0.35%,respectively.Cd and Hg were the main contaminants in Yixing County,the over standard rate of Cd was higher than that of cultivated land in China.In terms of the ecological risk,heavy metals of farmland soil in Yixing County showed a“light”ecological risk,with Cd accounting for 57.46%of the total ecological risk.The north-east of Dingshu Town,Xushe Town and the south-east of Zhangzhu Town were three areas with high ecological risk in Yixing County.The contamination of farmland soils in Yixing County may mainly come from man-made chemical production activities.Based on the ecological risk assessment of heavy metal pollution in cultivated soil of counties in the Yangtze River Delta region,the research result can provide the basis for the prevention and control of heavy metal pollution in cultivated soil,and improve the level of safe utilization of cultivated land resources.