Study On Spatial Variation Characteristics Of Soil Heavy Metals And The Influence Of Key Polluting Enterprises In Xiangjiang River Basin

The Xiangjiang River Basin is the main tributary of the Yangtze River.With the process of urbanization and social progress,heavy metal pollution in the soil of the Xiangjiang River Basin is becoming increasingly prominent.Aiming at the problem of excessive content of heavy metals Cd,Hg,As,Pb and Cr in China’s soil,it is of great significance to clarify the spatial distribution characteristics of heavy metals in soil and the pollution sources.This paper selects the Xiangjiang River Basin as the research object.Descriptive statistical analysis,risk assessment analysis,spatial correlation and heterogeneity analysis,and kriging interpolation analysis were used to explore the pollution status,variation characteristics and spatial distribution of soil Cd,Hg,As,Pb content.And with the help of redundancy analysis(RDA),bivariate local Moran’s index method(Bivariate local Moran’s I),generalized additive model(GAM)to quantify the contribution rate of different industry types to soil Cd content in key industry impact areas.So as to provide a foundation for the governance and improvement of soil environmental quality in xiangjiang river basin.The results show that:(1)In the study area,Cd,Hg,As,Pb and Cr soil heavy metals were enriched to different degrees,and Cd and Pb heavy metals were enriched to a higher degree in the soil,which may be subject to intense human activities.The soil in the study area was slightly acidic as a whole.(2)Among the five soil heavy metals in the study area,Cd pollution was the most serious,As pollution was the second,followed by Pb and Hg,and Cr content pollution risk was the lowest.The accumulation degree of the five heavy metal elements was different,and the accumulation degree of Cd was higher,while the accumulation degree of Pb and Cr was not obvious.(3)The spatial distribution of heavy metals Cd,Hg,As and Pb in the study area is similar,mainly distributed in the central and southern parts of the study area,where traffic,rivers and enterprises are concentrated.The soil heavy metal Cr is mainly distributed in the northern,southern and western regions of the study area,where natural factors and human activities have a certain influence on it.The low-value areas of the five soil heavy metals are mainly distributed in the east of chenzhou city,where the traffic,river network and enterprises are sparse,which are less affected by industrial activities,transportation and sewage irrigation.(4)The results of redundancy analysis show that Cd,Hg,As,Pb and Cr are strongly correlated with industry category,river distance,parent material type,road distance and parent material type,respectively.In the areas affected by enterprises in key industries,the four industry types have different impacts on soil heavy metal Cd pollution.In order of industry influences,the selection industry,>chemical manufacturing industry,>smelting industry,and>rolling processing industry are ranked in order,with the variance interpretation rate of 57.3%,42.7%,46.0%,and 17.5%,respectively.The mining industry has the most significant impact on soil heavy metal Cd pollution.