Health Risk Assessment Of Characteristic Pollutants In Contaminated Site Left Behind By A Typical Coal Chemical Enterprise In Shanxi Province

With the expansion of China's urbanization,large chemical companies once built in the city center are ordered to move out of the urban area.The pollution of the site left behind is not optimistic.This paper takes a contaminated site left behind by a coal chemical enterprise in Shanxi Province as an example.Through a series of investigations on the site investigation,plant distribution,and data analysis of the contaminated site,the land is divided into four regions?Zone A:the coal washing plant and the coal gangue power plant,Zone B:the coking plant chemical production area and the phenol cyanide wastewater treatment station,Zone C:the coking plant office area,Zone D:the oil depot?according to the type of land use.A total of 342 soil samples of different depths were collected from the 92sampling points laid.The concentrations of various pollutants in the soil were determined and analyzed,and the pollutants that were exceeded were screened as characteristic pollutants in the contaminated sites.Statistical analysis and spatial analysis of the content of characteristic pollutants in different regions were conducted to explore the sources of pollutants.Finally,according to the risk assessment model provided in Technical Guidelines for Risk Assessment of Contaminated Sites?HJ25.3-2014?,the carcinogenic and non-carcinogenic risks of various pollutants in the soil?sensitive land?were evaluated by partitioning stratification,and the contribution rates of the five kinds of exposure pathways were compared.The main conclusions are as follows:?1?A comparison is made between the various types of pollutants and the corresponding screening values.Four categories of 11 pollutants are selected as characteristic pollutants?including the monocyclic aromatic hydrocarbon?in the site:Benzene;PAHs class:FUL,PHE,BaA,Bap,IPY,DBA,Bgp,BbF;Aniline class:Dibenzofuran and TPH class:C₁₀-C₁₆.The pollution of Zone A and Zone C is mainly caused by PAHs.In Zone B and Zone D,the complex pollution characteristics are presented in both regions,the Zone B is mainly o f PAHs and Benzene,and D is dominated by PAHs,Dibenzofuran and C₁₀-C₁₆.?2?According to the vertical distribution map of different pollutants in the four regions and the spatial distribution map of GIS simulation,BaP,BaA,BbF,DBA,IPY are widely distributed,They are mainly distributed in the form of patches in Zone B and Zone D,and the punctiform distribution is mainly in Zone A and Zone C.FLU,PHE,BgP,Ben,Dibenzofuran and C₁₀-C₁₆ are scattered in a small range with a punctiform distribution.All kinds of characteristic pollutants are basically concentrated in shallow soil of0⁰.3m in different regions.?3?The correlation analysis and principal component analysis results show that the high-ring polycyclic aromatic hydrocarbons in the contaminated site mainly come from the coke oven atmospheric deposition,leakage and backfilling of waste residue,and are also affected by the specific regional technology within the contaminated site.FLU,Dibenzofuran and C10-C16are mainly from the leakage of various tanks in oil depots.The chemical production workshop in Zone B and oil depots in Zone D are designated as heavily polluted areas,and Zone A and Zone C were designated as lightly polluted areas.FLU,Dibenzofuran and C₁₀-C₁₆ are mainly from the leakage of various tanks in oil depots.The chemical production workshop in Zone B and oil depots in Zone D are designated as heavily polluted areas,and Zone A and Zone C were designated as lightly polluted areas.?4?The characteristic pollutants in each district are classified into shallow and deep layers according to their depth,and the risk assessment is conducted.The result is:Shallow layer in Zone D>Shallow layer in Zone B>Shallow layer in Zone C>Deep layer in Zone D>Deep layer in Zone B>Shallow layer in Zone A,and each area exceeds the acceptable value of carcinogenic risk of 10^-6.At the same time,the comprehensive non-carcinogenic risk quotients in Zone B and Zone D are both higher than 1,indicating that the pollution sites of the coal chemical companies will have certain carcinogenic and non-carcinogenic risks to future receptors.In the shallow and deep soils in different areas of the contaminated site,the PHAs is the characteristic pollutant,and the contribution of different exposure pathways to the carcinogenic risk is mainly based on oral intake of soil and skin contact with soil.In the deep soil of zone B,the contribution rate of benzene in different exposure pathways to carcinogenic risk is mainly through breath and skin contact.This study can provide valuable reference data for the management and restoration in the subsequent development and utilization of contaminated sites of coal chemical enterprises.