| With the rapid development of electronic information technology, a large amount of electrical and electronic wastes have been generated. In the process of electrical and electronic waste recycling, the crude and unregulated recycling activities can release the pollutants into the soil. As an agricultural country, the quality of cultivated land is related to food security and agricultural sustainable development, cultivated land pollution has become a hot environmental problem.Wenling City in Zhejiang province was selected as the representative research area and 129 paddy soil samples were collected from paddy fields. Concentrations of the 16 polycyclic aromatic hydrocarbons (PAHs) listed by the USEPA as priority control pollutants were analyzed. With the source apportionment, geospatial interpolation and risk assessment methods, we studied the PAHs pollution level, sources, dirtribution and environmental risks. It’s very useful and helpful to offer theoretical bases for environment management.The ∑PAHs concentration in Wenling rice paddies ranged from 190.76～1636.49 μg kg-1, with an average of 568.64 μg kg-1, and the predominant PAHs were HMW (high molecular weight,4-6 rings) PAHs. There were significant correlations in most of the HMW PAHs, which indicated that the HMW PAHs had the similar sources. Except for NAP and BkF, the correlation between PAHs monomer and ∑PAHs was significant, FLU, CHR, BbF and IND could be used as the main representative PAHs in the paddy soils. The pollution sources of PAHs were identified based on relative abundance, the isomeric ratios of PAHs and principal component analysis (PCA) methods. The results suggested that the concentrations of PAHs of rice paddies in the study area were from a number of multiple sources of PAHs pollution, the dominated sources were combustion sources including the combustion of various biomass fuel and e-waste.Based on Bayesian maximum entropy (BME) estimation, spatial distribution of the PAHs was analyzed. Results showed that the northwest and southwest parts were the highly contanminated regions, and the central and east parts were the low contanminated regions. The spatial distribution trend of carcinogenic PAHs (BaA, CHR, BbF, BkF, BaP, IND, and DBA) was similar to the former, but the highly contanminated regions were relatively more dense. Soil organic matter and socio-economic factors were significantly correlated with the PAHs positively, which played important roles in determining the spatial distribution of soil PAHs.Two memods for ecological risk assessment were used to evaluate the ecological risk level of the rice paddy PAHs in Wenling. Based on the Toxic Equivalence Factor (TEF) method, the total TEQBaP ranged from 23.14～258.76μg kg-1, with an average of 90.41 μg kg-1. With the Dutch agricultural soil standard as reference,88% of the sample point TEQBaP exceeded the limit for soil in the Netherlands. The areas with high potential ecological risk included mainly in Chengnan, Zeguo, Hengfeng and Chengbei townships. Based on the risk quotient method, the ecological risk level of ∑PAHs in the paddy soils was low. However, it is still considered that the pollution of PAHs in Wenling paddy soils has posed a potential ecological risk based on above assessment results comprehensively.The health risk of PAHs in Wenling rice paddies was estimated with the method of probabilistic incremental lifetime cancer risks assessment (ILCR), and it was found that the health risk was at low level with the USEPA standard and there was no great risk to human body. Out of the three different exposure pathways, the ILCRs were mainly caused by ingestion and dermal contact, while that by inhalation of resuspended particles was almost negligible. The health risk of children was higher than those of adults. In addition, the maximum ILCRs of children exceeded 10-6, it posed a potential health risk. |
PDF Full Text Request