Site Environmental Investigation And Risk Assessment Of Industrial Solid Waste Disposal Station In Dongguan

With the increase of labor and land costs,the China government emphasis on environmental protection,and the requirements of economic transformation and development in recent years,there were a large number of low-end industries with low energy efficiency and high emissions have been gradually eliminated in China,and many cities are facing the problem that closure and relocation many heavily polluting industrial enterprises.As a "world factory",after decades of rapid development,more and more traditional low-end industries have been difficult to sustain development in Dongguan.There were a large number of industrial enterprises have been eliminated or closed and relocated due to serious pollution,leaving a large number of industrial enterprise sites which may have been contaminated.The sites which have been suffered pollution on different level,which may cause some health risks to the people work in the site and the residents live around the sites in the future.Therefore,it is necessary to investigate the pollution status of these legacy industrial enterprise sites,evaluate the risks caused by pollution,and then take corresponding measures to ensure that they will not cause health hazards to humans before they can be re-developed.The study take an industrial solid waste treatment station in Dongguan as the research object.The contents of eight heavy metals(As,Cd,Cr,Cu,Ni,Pb,Zn,and Hg)at 20 soil sampling points were determined,then used the single factor pollution index evaluation method,Nemero comprehensive pollution index method,potential ecological risk index method and health risk characterization model,to evaluate heavy metal pollution extent,potential ecological risk and human health risk level,and used software ArcGIS and SPSS,the method of inverse distance weighted interpolation and the principal component analysis to draw the spatial distribution map and analyze the sources of pollutants.The results mainly including follow aspects:(1)The results of the risk assessment showed that:(1)The Cu content in the site was generally exceeding the standard,Zn and Ni were exceeding the standard at individual points,indicating that Cu was the main characteristic pollutant in the siteand there were obvious non-point source pollution characteristics;The point exceeding rate of Cu is as high as 80%,which caused the most serious pollution to the site.The average value of the comprehensive pollution index of heavy metals in the site is 3.092,which is a serious pollution level.The pollution concentration of four soil layer is fill layer>surface layer>middle layer>deep layer;(2)The magnitude of the potential ecological risk of the single factor of the eight heavy metals is Cu>Cd>Hg>Ni>As>Pb>Cr>Zn.The potential ecological risk of Cu is high,and the potential ecological risk of Cd and Hg is medium.Risk;the potential ecological risks of the remaining five heavy metals are low risk levels.Judging from the vertical distribution of the potential ecological risk index of heavy metals,the potential ecological risk of each soil layer is fill layer> surface layer> middle layer> deep layer;(3)The health risk assessment results showed that Cu in the site has a high non-carcinogenic health risk,and Ni has a certain carcinogenic risk.(2)The results of the spatial distribution of pollutants at the sampling sites showed that Cu pollution is mainly concentrated in the fill layer and surface layer,and there are local standards in the middle layer.The Cu content in the deep soil is close to the background value,so there is no Cu pollution.The Cu pollution in the fill layer generally exceeds the standard,especially in the eastern area of the storage yard and in the 2 # underground pool area.The surface soil Cu pollution is reduced compared with the soil filling layer,but the degree of pollution in most areas is still heavily polluted level;the copper pollution in the middle soil layer is significantly reduced compared with the soil filling layer and the surface layer,and the pollution concentration in most areas is lower than the screening value.The deep soil does not exceed the screening value,and the health risks are within the safe range.(3)The analysis of the pollution source showed that Cr,Cd,Ni,Pb,Zn,As and Hg are mainly derived from trace impurities contained in the Cu-containing etching waste liquid;Cu pollution sources are distributed throughout the site,Cu and Cu-containing materials as the main production materials and production throughout the entire production operation process in this waste recovery and treatment station,pollution can occur in every process of the production process,especially in the production workshops and warehouses,and in the waste slag storage area,Cu pollution is particularly serious.