| The heavy metals, OCPs and PAHs in soils of Jiaogang Lake Basin were the research objects in this study. The soil samples were analyzed by the hydrochloric acid-nitric acid-perchloric acid-hydrofluoric acid digestion method, ICP-AES detection and accelerated solvent extraction method and GC-MSD detection method in order to investigate the concentrations, distributions, pollution characteristics and sources of heavy metals, OCPs and PAHs in soils and to evaluate the ecological risks.The differences of contents among six heavy metals in soil samples of Jiaogang Lake Basin were significant with the descending order as follows:Cr> Zn> As> Cu> Pb> Cd. Significant correlations among six heavy metals may result from the same source. According to the assessment results of heavy metal pollution in farmland soils of study area using the Geoaccumulation Index Method and Potential Ecological Risk Index Method, heavy metals in the soils of study area were in pollution-free to medium pollution level and As and Cd were considered as main heavy metal of pollution. Result of spatial distribution analysis showed that, the contents of heavy metals were not influenced by the surface runoff in the studied area, while the quantity and strength of emissions from industrial and agricultural activities may contributed to the spatial differences of heavy metals in soils.Twenty kinds of OCPs in soils of Jiaogang Lake Basin were detected to varying degrees, with the contents range of 73.07～742.11ng·g-1 and an average of 341.20 ng·g-1. According to the evaluation of Isomer Ratio Method, Lindane was probably applied in soils in recent times while the DDTs and Endosulfan resulted from the previous residues in soils of the study area. Based on the analysis of spatial distribution, high contents of the HCHs in soils mainly distributed in the areas of frequent agricultural activities, which revealed that the spatial distribution of OCPs in soils might be relevant to land use and pesticide applications. In addition, result of health risk assessment showed that, contents of HCHs in the soils of study area posed no harm to human health.The PAHs was widespread in the farmland soils of study area. Contents of 16 kinds of PAHs ranged of 28.60～269.54ng·g-1 with a mean of 101.78 ng·g-1.The average contents of 7 kinds of carcinogenic PAHs accounted for 14.50% of the 16 kinds of PAHs. Contents of PAHs showed significant spatial variation, which were influenced by various natural factors and authropogenic factors. PAHs generally showed a banding distribution with a descending trend along the north-south direction, and the high contents of PAHs appeared the northern areas and the southwestern zones of the study area. According to the source apportionment via Isomer Ratio Method, the PAHs in soils derived from extensive sources, such as the burning of fossil fuel and biochar or oil pollution. Moreover, the potential carcinogenicity of PAHs in soils was regarded as low level on the basis of TEQ evaluation.Comprehensive assessment for farmland soil pollution in Jiaogang Lake Basin showed, the comprehensive pollution index of 41 soil samples were below 0.6. only 2 samples were in the "clean" level and accounted for 4.88% of all samples,20 samples, accounted for 48.78%,were in "light pollution" level, and the other 19 samples(46.34%) were ranked as "moderate pollution". Overall, the soils of study area were assessed in mild to moderate pollution. |
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