Investigation And Environmental Risk Assessment Of Soil Heavy Metal Pollution In An Abandoned Chemical Site

With the rapid development of China's economy and society,the scale of the city is expanding,and many old and old chemical enterprises in urban areas are under pressure to relocate.As an aspect of sustainable development,the reuse of waste chemical sites has become an important topic for researchers.After many years of production operations,factory emissions such as waste gas,waste water and waste residue of pile have heavily polluted soil.Heavy metals accumulation and retention in soil which are far higher than that of soil background value not only make harm to animals,plants,microorganisms,even is a threat to human health when it is reused.In this study,site investigation and environment risk assessment was carried out.The work was based on“Technical guidelines for environment site investigation”,“Technical guidelines for risk assessment of contaminated sites”and other standard specifications,and referred to the domestic and foreign related risk assessment method as well.According to the statistical analysis of pollutant concentration,the main pollutants in the site are arsenic and barium.From the perspective of the plane distribution of pollutants,the pollution range was concentrated in the local area of the mud pool and the raw material base of barium carbonate and barium sulfate production area and the local area of the strontium carbonate production area.In the longitudinal distribution,the concentration of pollutants in excess of the screening value was only in the depth of less than 4m.In this study,the spot of the superfiltration value of arsenic was S15,S21,S22 and S24.The maximum concentration appears at 1.0m depth of S22 was 87.4 mg·kg^-1,exceeded the screening value was 3.37 fold.The spot of the superfiltration value of barium was S14,and the maximum concentration at 1.2m depth of S14 was 121000 mg·kg^-1,the frequency of over screening value was 0.31%,and exceeded the screening value was 7.07 fold.According to the calculated results of the risk calculation of various sampling points,it can be seen that the carcinogenic hazard entropy of pollutant arsenic was higher than the acceptable level,and the cancer risk of other pollutants was not more than 10^-6.The non-carcinogenic entropy of barium in individual points was higher than acceptable level 1.The results showed that the soil of the site was obviously polluted by arsenic and barium,and arsenic was the most important contributor to human health risk.Therefore,we suggest that the site must be conducted for certain pollution level soil remediation and comprehensive treatment,and reduce risk to human health acceptable levels before the residential land utilization.This study aimed at site soil health risk assessment of heavy metals pollution and select reasonable pollution control scheme to provide reference basis for land use planning,land pollution of the environment safety.