Source Apportionment Of Soil Heavy Metals And Identification Of Risk Areas In Industrial Agglomeration Areas:A Case Study In Xiangjiang River Basin

The heavy metals in the soil can pose a huge threat to the ecosystem and human health.The rapid development of industrialization has brought serious risks of heavy metal pollution to the soil.Understanding the spatial distribution characteristics and influencing factors of soil heavy metals in industrial agglomeration areas,and clarifying risk areas of pollution are of great significance to soil pollution prevention and control work.This paper takes the industrial-intensive Dahetan sub-watershed as a typical research area,and takes Cd,Hg,As,Pb,and Cr as the research objects.Through statistical analysis,spatial analysis,source analysis and other methods,the soil heavy metals in the research area The pollution characteristics,sources of pollution,spatial distribution and influencing factors of pollution were explored.On this basis,the analysis results are extended to the Xiangjiang River Basin to predict risk areas of soil heavy metal pollution.New ideas for identifying high-risk areas of soil pollution in large-scale areas are proposed,which can provide references for the regional prevention and control of soil pollution.The main conclusions are as follows:(1)The average concentration of the five heavy metals in the soil of the study area is higher than the local background value,and the five heavy metals are enriched in varying degrees.Taking the screening values of GB 15618-2018 "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standards(Trial)" as the standard,the Hg and Cr concentrations in the soil almost did not exceed the standard,while the excess points of Cd,As and Pb accounted for respectively 78.6%,36.3% and 23.3%.(2)The distribution trends of Cd,As and Pb in the soil of the study area are similar.The high value areas are distributed in the southeast and southwest of the study area where polluting enterprises are concentrated.The distribution trends of Hg and Cr are relatively scattered,with a wide range of high value areas,which has little to do with the distribution of enterprises.The results of the pollution evaluation show that in the densely distributed areas of the southeast and southwest of the study area,Cd,As and Pb are heavily polluted.Among them,Cd has the largest pollution range and the most serious degree.The concentration of Hg and Cr in the study area is basically at a pollution-free level.(3)Soil heavy metals in the study area mainly come from natural sources and industrial sources.The contribution of natural sources to Hg and Cr reaches more than90%.Cd,As,and Pb are mainly affected by industrial production,and industrial sources contribute 65.5%,86.5% and 85.6% to them,respectively.Among the natural factors,the soil p H and soil type have a greater impact on the concentration distribution of soil heavy metals.Enterprise distance and industry category are the most influential industrial factors.The industry categories that contribute significantly to the concentration of Cd,As and Pb mainly involve the mining,smelting and processing of ferrous and non-ferrous metals.In addition,compared with single factors,the interaction between factors has significantly increased explanatory power for the concentration of heavy metals.Among them,the interaction between natural and man-made factors has a higher explanatory power for the distribution of Cd and Pb.It is worthy of special attention in the management and control work,and the actual prevention and control measures can consider the difference of natural conditions.(4)The risk areas of soil heavy metal pollution in the Xiangjiang River Basin are mainly located in the upper and middle reaches.The upstream areas are mainly risk areas of Hg and Cr,and the risk areas of Cd,As and Pb are mainly distributed in the middle and lower reaches of the basin.In the western,central and southern parts of the basin,there is an overlap of multiple heavy metal pollution risk areas,and these areas can be used as priority areas for soil heavy metal pollution prevention and control.After inspection,it can be proved that the method of determining the main influencing factors of the distribution of soil heavy metals through geographic detectors and delimiting risk areas according to their dominant types or ranges is reasonable.This method points out the priority areas for soil pollution prevention and control while avoiding large-scale sampling,and provides a new idea for identifying risk areas on a large scale,and has reference significance for the formulation of key soil pollution control areas and control methods.