淮河流域高潜水位农用地重金属特征及风险评价

Characteristics and Risk Assessment of Heavy Metals in Farmland Soil with High Groundwater Level in Huaihe River Basin

为查明淮河流域典型高潜水位农用地土壤重金属污染物特征及其影响范围,保证土壤环境及农产品质量安全,以淮南市毛集实验区焦岗湖镇某村农用地土壤为研究对象,分析了土壤中镉(Cd)、铬(Cr)、铅(Pb)、砷(As)、铜(Cu)、锌(Zn)和镍(Ni)等7种重金属元素的含量特征。运用内梅罗综合污染指数法(Pn)、污染负荷指数法(PLI)和潜在生态风险评价法(RI)评价土壤重金属污染水平和潜在生态风险程度,并应用ArcGIS软件中地统计分析模块探讨土壤重金属空间分布特征。结果表明:该区域土壤7种重金属含量平均值和中值均低于淮南市土壤元素背景值和农用地土壤污染风险筛选值,空间分布上重金属含量总体上呈现从南到北、从西至东逐渐升高的趋势;内梅罗污染指数和污染负荷指数法评价表明,重金属元素污染等级分别处于清洁和无污染水平;潜在生态风险指数评价表明,总体上生态风险等级轻微;在空间分布上,重金属污染指数值呈现由南至北逐渐增大趋势,As和Cd元素是最主要的生态风险贡献因子。

In order to find out the characteristics and impact range of heavy metal pollutants in the soil of agricultural land with typical high water table in the Huaihe River basin,and ensure the quality and safety of soil environment and agricultural products,taking the agricultural soil of a village in Jiaoganghu Town,Maoji Experimental Area,Huainan City as the research object,the content characteristics of seven heavy metal elements in the soil,such as cadmium(Cd),chromium(Cr),lead(Pb),arsenic(As),copper(Cu),zinc(Zn)and nickel(Ni),were analyzed,the level of soil heavy metal pollution and potential ecological risk were evaluated with the Nemerow pollution index method(P n),the pollution load index(PLI)and potential ecological risk assessment(RI),and the spatial distribution characteristics of soil heavy metals were discussed by using the geostatistical analysis module of ArcGIS software.The results showed that the average and median contents of seven heavy metals in the soil of the region were lower than the background values of soil elements in Huainan City and the screening values of soil pollution risk in agricultural land.The contents of heavy metals in the spatial distribution showed a trend of gradually increasing from south to north and from west to east.The evaluation of the Pn index and the PLI index method showed that the pollution level of heavy metal elements was at the clean and non-polluting levels,respectively.The evaluation of RI index showed that the overall ecological risk level was slight.In terms of spatial distribution,the value of heavy metal pollution index gradually increased from south to north,and As and Cd were the main ecological risk contribution factors.