Spatial Distribution Characteristics And Temporal Dynamic Simulation Of Heavy Metals In Soil Of A Typical E-waste Disassembly Area In Guangdong Province

Due to the increasingly serious pollution problems caused by industrial development,the heavy metals and organic matter being produced have seriously damaged the ecological environment of the region.While the electronic waste dismantling industry brings economic benefits to the locality,the heavy metals that accompany the dismantling activities also pose a threat to the local environment.The heavy metals in the environment can never degrade and have bioconcentration,which brings great risk to human health.In this study,Guiyu Town,belongs to Shantou City,Guangdong Province was taken as the study area.Based on the sampling of local farmland,road and other soil,the total amount of heavy metals Cr,Ni,Cu,Zn,Cd and Pb in the surface soil of each sample and the content of various forms were analyzed.The distribution characteristics of heavy metals in the soil of the study area were studied and characterized by using Arc GIS.The source analysis of six heavy metals was carried out and the ecological risk level was evaluated.In order to understand the future pollution status of the area,a soil nutrient loss model was used to simulate the migration and concentration of heavy metals and predict the future degree of pollution in the area.The results show that the average contents of heavy metals Cr,Ni,Cu,Zn,Cd and Pb were 43.3,20.1,50.9,108,0.42 and 123 mg/kg,respectively.And the cadmium content in 80% of the samples in the study area is higher than the first-level standard of soil environmental quality standards.The coefficients of variation of Cr,Ni,Cu,and Cd are 63%,49%,83%,and 45%,respectively,indicating that the treatment of electronic waste has an impact on heavy metal pollution.Correlation analysis results show that Ni,Cu,Zn and Pb pollution is closely related to local human activities.The spatial distribution map of heavy metals based on Arc GIS shows that pollution spots are roughly distributed in Guiyu Town and its surrounding areas.The order of the value of six heavy metals' geostatistical index(Igeo)is Pb> Cd> Cu> Ni> Cr> Zn,indicating that the lead in the study area is seriously polluted.According to Hakanson's ecological risk index method,the soil in Guiyu Town and its surrounding areas is in a strong ecological hazard due to the decomposition of electronic waste.The simulation results of heavy metal concentration migration show that,compared with the measured values in 2010,the concentrations of Cr,Zn,Cd of measured values in 2017 show a downward trend,while the concentrations of Ni,Cu,Pb have increased.The simulation results of Ni,Cu and Cd are close to the measured values in 2017,and good fitting effect shows that the model is practical.In this paper,the status quo,spatial distribution,possible pollution sources and concentration simulation of heavy metal pollution in the study area were studied,which provided reference information for regional environmental governance.In this paper,pollution status,spatial distribution,possible pollution sources and concentration simulation of heavy metal pollution in soil of the study area were studied,which provided reference information for regional environmental governance.