Evaluation Of Heavy Metal Pollution Of Soil In Lean River Basin And Analysis Of Influencing Factors

Soil heavy metal pollution has obvious regional differences.Carrying out studies on soil heavy metal pollution in watersheds where the source-sink relationship is relatively clear is of great significance for objectively grasping the distribution law of soil pollution and analyzing the factors affecting soil pollution.In this paper,the Lean River Basin was selected as the research area,and the contents of Cd,Hg,As,Pb,and Cr in 488 samples were detected.Using single-factor pollution index evaluation,Nemelo comprehensive pollution index evaluation,heavy metal pollution degree evaluation,potential ecological risk evaluation,etc.,with the help of ARCGIS and related analysis tools,it is divided into three sections:different river sections,different enterprise types,and different land types.The pollution status and potential ecological risk assessment of heavy metal elements Cd,Hg,As,Pb,Cr in the study area were studied.Based on the research results,single-factor analysis of variance was used to analyze the differences in the content of each element in different river segments,different types of businesses,and different types of land to determine the main factors affecting the distribution of each element in the study area.The evaluation results show:(1)The number of Cd element super-screening points is large,and the Hg,As,Pb,Cr,Cu,Zn element super-screening points are few.(2)The results of PCA and Pearson Correlation Coefficient show that all the information of the seven heavy metal elements in the agricultural surface soil in the watershed can be reflected by the three principal components,with contribution rates of 45.90%,19.92%,and 14.60%,respectively.Cd,As,Pb,Cu,Zn are mainly affected by the component 1,Cr and Ni are mainly affected by the component 2,and Hg is mainly affected by the component 3;(3)The content of each element in different river sections,different types of enterprises,and different types of land is obviously different,but the difference of heavy metal elements in different river sections is actually caused by the production activities of nearby enterprises,and has nothing to do with the flow direction of the river.The sources of heavy metals on paddy fields and dry land are contaminated river water.However,due to the different irrigation methods in paddy fields and dry land,and the different absorption capacities of rice and wheat for various heavy metal elements,the content of some heavy metal elements in paddy fields is significantly higher than that in dry land.