| In this paper, a typical waste plastic distribution center, Gengche Town, Suqian City,Jiangsu Province is taken as the object of study. It mainly investigates the status of soil quality in the research area, identifies the main pollutants, expounds the characteristics of pollutant distribution,conducts health risk assessment and environmental benefit assessment. A total of 53 soil indicators has been detected. The results show that the main pollutants in the soil of the study area are phthalate esters (PAEs). This paper examines the influencing factors and regular characteristics of the distribution of PAEs, and clarifies the impact of PAEs pollution in soil on the local social environment. The main conclusions are as follows:(1) The status of soil quality in the research area : suface soil samples were collected in typical waste plastic processing area of Gengche town,surrounding farmland in Wu Zhuang. A total of 52 indicators of soil samples, such as heavy metals, persistent organic compounds, polycyclic aromatic hydrocarbons and phthalates, have been detected. Heavy metal content did not exceed the standard limit, refer to the relevant standards. Only two organic pollutants, PAEs and chloroform were detected. The detection rates of chloroform and PAEs were 21% and 100% respectively. The maximum content of chloroform was 0.01 mg·kg-1 and did not exceed the standard of living land. The content of PAEs was 0.044-14.4 mg·kg-1 and approximately 14 % of the soil samples exceeded the standard of living land for PAEs. Supplemented with the detect of polybrominated diphenyl ethers(PBDEs) at the second sampling, PBDEs were not detected in the soil. It is determined that the study area characteristic pollutanta were PAEs.(2) PAEs pollution status of the research area : the soil samples of Gengche town were collected. At the same time,the urban area of Suqian which was not contaminated was set as control. Four phthalates were detected in research area, they were Dibutyl phthalate (DBP), Bis(2-ethylhexyl)phthalate (DEHP), Diisobutyl phthalate (DIBP) and Diisononyl phthalate (DINP), while only DEHP and DBP detected in the urban area of Suqian. The total concentration of PAEs in the study area ranged from 0.102- 28.513 mg·kg-1, with a mean of 2.481 mg·kg-1. The total concentration of PAEs in the urban area of Suqian ranged from 0.41-0.412 mg kg-1, with a mean of 0.411 mg kg-1. The contents of DEHP and DBP in the study area were higher than those in the urban area of Suqian, and the mean content of PAEs was DEHP> DBP> DINP> DIBP. Comparing with the control and management standards of DEHP and DBP in the United States, neither of them exceeded the soil governance standard, but 8.3% of the soil samples exceeded the control standard for DEHP, and 83.33% of the soil samples exceeded the control standard for DBP.The study area has been varying degrees of PAEs pollution. Among them, the comprehensive pollution index of DEHP and DBP in the settlement was 2.9 and 28.6,respectively, which was under severe pollution. The comprehensive pollution index of DEHP was under 0.7,which was under the cleaning level. On the contrary, the comprehensive pollution index of DBP was over 2.0, which was under moderate pollution.(3 ) The influencing factors and regular characteristics of the distribution of PAEs in the soil: the concentrations of PAEs and their monomers in the soil were related to the source of pollution, the distance to the village and the spatial distribution of the workshop.The concentration of PAEs was higher in the soil which affected by waste gas, waste plastics cleaning water and waste residue, and was lower in the soil which affected only by waste gas. The concentration of PAEs in the farmland soils decreased with the increase of distance away from the village. In the center of study area, the concentration of PAEs and each monomers were higher in the soil where the village households are concentrated and small workshops were relatively intensive, while the concentration of PAEs and each monomers in soils were lower where the village households are scattered and workshops were distributed less.(4)Health risk assessment of Gengche Town : the results of health risk assessment in the study area indicated that the maximum risk of DBP non-carcinogenic risk was 0.0791<1 (non-carcinogenic risk baseline) and the risk of DBP was low. DEHP carcinogenic risk was 3.02x10-8-1.66×10-4,while the baseline was 1.0×10-6. The carcinogenic risk of DEHP was high. There were 91.3% of the samples exceeded the carcinogenic risk evaluation standard for adults, and 52.2% of the samples exceeded the carcinogenic risk evaluation standard for children. DEHP within the village has a higher health risk, the carcinogenic risk exceeded 27.9 times (adults) and 8.66 times (children)which should pay more attention.(5) The comprehensive benefit assessment of Gengche Town : according to the current available data, the comprehensive benefit assessment of the study area showed that the waste plastics processing industry in the region had brought much economic benefits to the local area. However, the environmental cost paid was huge. In 2015, the direct economic benefits of the study area was 150 million yuan, and the environmental economic losses had reached to 115 million yuan after monetizing the environmental impact on air pollution, water loss and land use. In conclusion, the environmental cost should pay more attention in the process of processing waste plastics. |
PDF Full Text Request