Distribution and Diffusion of Organochlorine Pesticides in Soils from an Abandoned Manufacturing Site

In past decades, large amounts of organochlorine pesticides (OCPs) were produced and used in China. These abandoned OCPs manufacturer sites have become high-risk areas. Previous studies have investigated the contamination status of OCPs in these sites. However, most of the available data focused only on the inside of the factory and few studies consider the pollutions and risks of OCPs in the surrounding area. Levels and distributions of hexachlorocylohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs) and DDT metabolites were investigated in surface soils from an abandoned manufacturing site, in Chongqing, southwest China, in order to better understand the contamination status and environmental impact on the surrounding area. In this study, the potential human health risks were also assessed from within the factory and from the surrounding area. Concentrations of ΣHCHs ranged from 3.89 to 13385.78 ng/g in surface soils from inside the factory, which were generally lower than those reported in other contaminated sites. Levels of ΣDDTs ranged from 22.74 ng/g to 11186.10 ng/g in surface soils, which were consistent with previous observations in contaminated sites located in Zhangjiakou and Yangzhou city, but lower than those in Xingtai, Taiyuan and Qingdao city. The results of health risk assessment showed that the carcinogenic risk of OCP contaminants exceeded the acceptable risk in soils from inside the factory, which contributed to the heavily-polluted area. Within 400 meters from the manufacturing facility, the levels of OCPs in soils were also high although they were lower than those inside the factory. To children, the carcinogenic risk of HCHs and DDTs in surface soils is still higher than the standard recommended by some research institutions. With the distance increasing to the site, levels of HCHs and DDTs decreased with the trend of the power function, which indicated that the pollution of OCPs only occurred in a certain region outside the factory. Therefore, the OCP pollutions and risks should be considered from not only inside contaminated sites but also certain regions outside sites.