Spatial Variation And Distribution Prediction Of Soil Heavy Metals In Fujiang River

With the rapid development of economy and the continuous promotion of industrialization,urbanization and agricultural modernization,the soil has been polluted especially in heavy metals.Therefore,under the background of the increasingly severe problem of soil pollution,based on the research object of heavy metals in the soil of Fujiang river,this paper analyzed the spatial variation of heavy metals(Cd、Hg、As、Pb、Cr)and predictd their spatial distribution,which lays a solid foundation for the optimal utilization and remediation of soil resources.Firstly,This paper described statistical characteristics of five soil heavy metals in study area with the risk screening and intervention value(GB15618—2018),and then analyzed the correlation in the whole region and the cold and hot points and outliers in the local range through the Global Moran’s I and the Anselin Local Moran’s I Also analyzed the spatial structure using semi-variance function cloud and fitting model.Finally,predicted the spatial distribution through IDW,RBF,DK,EBK.The following conclusions are drawn from the above studies:(1)The mean and median values of the five heavy metals in soil did not exceed the risk screening value(GB 15618—2018),only the maximum values of Cd,Hg,As exceeded the risk screening value but were below their risk intervention values.On the whole,the soil environmental quality in the study area is good.(2)In the global scope,the Global Moran’s I of five heavy metals soil in the study area gradually decreased with the increase of sampling point distance,and the spatial correlation changed from positive to negative.In the localscope,the majority of samples showed no significance,followed by cold hot spots,and the distribution of outliers was the least.The spatial variation of Pb,Cr is mainly related to natural factors,the spatial correlation of Cd,Hg,As were weak and the spatial variation is short,and the spatial variation is mainly influenced by human factors.(3)Judging from the prediction of heavy metals distribution in soil,degree pollution of Cd,Hg,As were mainly distributed upstream,caused by the accumulation of landfill waste,raw and auxiliary materials in enterprise processing,and irregular discharge of sewage;The mild pollution is widely distributed throughout the basin,traffic factors and atmospheric deposition were likely to be one of the causes of pollution;For non-polluting areas,the distributions of Cd,Hg more dispersed,As mainly distributed downstream,mainly related to geological background.Pb、Cr were mostly alert level,only a few mild pollution in the upper and middle reaches,and its distribution is mainly related to geological background.