基于PCA和ArcGIS的县域土壤重金属生态风险评估及来源解析

Ecological Risk Assessment and Source Analysis of Heavy Metals in County Soil Based on PCA and ArcGIS

为了量化思南县农用地土壤重金属污染特征和生态风险程度,采集了65个土壤样品,采用单因子污染指数、内梅罗综合污染指数和潜在生态风险评价法,对Cd、Hg、As、Pb、Cr、Cu、Ni和Zn 8种重金属的含量特征和生态风险进行了评价,并用PCA主成分分析法对其来源进行了识别。结果表明:Cd、Hg、As、Pb、Cr、Cu、Ni和Zn的含量分别是贵州省A层土壤背景值的1.02、2.36、1.25、1.44、1.07、1.03、1.01、1.09倍,出现了不同程度的累积;单因子评价结果表明,Cd是研究区农用地土壤主要的污染元素;思南县轻度污染、中度污染和重度污染点位分别占70.77%、7.69%、4.62%;综合生态风险指数结果表明,95.48%的点位处于轻度风险等级,4.52%的点位处于中度风险等级;通过PCA主成分分析得出,Cr、Cu、Ni为自然源,贡献率为34.22%,Hg、As、Pb、Zn为混合源,包括矿产资源开发、交通排放和生活源等,贡献率为28.31%,Cd、Zn为农业源,贡献率为13.68%。

In order to quantify the heavy metal pollution and ecological risk degree of agricultural land in Sinan County,65 soil samples were collected.The content and ecological risk of 8 heavy metals(Cd,Hg,As,Pb,Cr,Cu,Ni and Zn)were evaluated by single factor pollution index,Nemero index and potential ecological risk evaluation method,and their sources were identified by PCA principal component analysis method.The results showed that the contents of Cd,Hg,As,Pb,Cr,Cu,Ni and Zn were 1.02,2.36,1.25,1.44,1.07,1.03,1.01 and 1.09 times of thebackground value of layer A soil in Guizhou Province,respectively;The results of single factor evaluation showed that Cd was the main pollution element of agricultural land soil in the study area;The light pollution[],moderate pollution and severe pollution points in Sinan County accounted for 70.77%,7.69%and 4.62%respectively;The results of comprehensive ecological risk index showed that 95.48%of the sites were at the level of mild risk and 4.52%were at the level of moderate risk;Through PCA principal component analysis,it is concluded that Cr,Cu and Ni are natural sources,with a contribution rate of 34.22%,Hg,As,Pb and Zn are mixed sources,including mineral resource development,traffic emissions and domestic sources,with a contribution rate of 28.31%,Cd and Zn are agricultural sources,with a contribution rate of 13.68%.