银川市农田土壤中多环芳烃污染及风险评价

Contamination and Risk Assessment of PAHs in Farmland Soil of Yinchuan

为准确了解银川市农田土壤中多环芳烃的污染状况、空间分布特征及其生态风险,文章采集银川市农田表层土壤样品共91个,采用高效液相色谱法检测了样品中16种多环芳烃(PAHs)含量,分析其污染特征及空间分布状况,对PAHs来源进行分析,并对土壤中PAHs潜在的生态风险和健康风险进行了评价。结果表明:土壤中∑PAHs含量在ND~1517.37μg/kg之间,平均值为241.49μg/kg,16种PAHs单体变异系数均大于1,区域分异显著;未污染、轻度污染、中度污染和重度污染的样品分别占到样品总数的60.44%、32.97%、2.19%和4.40%;16种PAHs单体的空间分布差异较大,东南部和西南部含量较高;源解析结果显示银川市农田土壤中PAHs的主要来源为煤、化石燃料等的高温燃烧以及汽车尾气排放和汽油源;生态风险评价结果显示,PAHs毒性当量范围为0~1.1×10^(3)μg/kg,平均值为52.04μg/kg,整体潜在生态风险较低,但部分样品具有较高的生态风险;健康风险评价结果显示,非致癌风险均在可接受的标准范围,但是有7个样品的BaP致癌风险超过美国环境保护局推荐的致癌水平,存在潜在的致癌风险,需引起重视。

In order to accurately understand the pollution status,spatial distribution characteristics and ecological risk of polycyclic aromatic hydrocarbons(PAHs)in farmland soil of Yinchuan,a total of 91 surface soil samples were collected from Yinchuan farmland and high performance liquid chromatography(HPLC)method were used to detect the contents of 16 kinds of PAHs.The contamination characteristics and spatial distribution of PAHs in Yinchuan farmland soil were analyzed,the sources of PAHs were discussed,the potential ecological and health risk were evaluated.The results showed that the total PAHs concentrations in farmland soil ranged from ND to 1517.37μg/kg,and the average concentration was 241.49μg/kg,the variation coefficients of 16 PAHs monomers were all larger than one,which indicated significant regional differentiation.Non-contaminated,lightly contaminated,moderately contaminated and heavily contaminated samples accounted for 60.44%,32.97%,2.19%,and 4.40%respectively.The concentrations of PAHs were higher in the southwest and southeast,and the spatial distribution of 16 PAHs monomers was quite different.The source apportionment showed that the main sources of PAHs in farmland soil in Yinchuan were high temperature combustion of coal and fossil fuels,automobile exhaust emission and gasoline.The ecological risk assessment results showed that the toxic equivalent range of PAHs was 0~1.1×10^(3)μg/kg,the average value was 52.04μg/kg,the overall potential ecological risk level was low,but some samples had higher ecological risk.The health risk assessment indicated that the non-carcinogenic risk were all within the acceptable standard range,but the carcinogenic risk of children and adults caused by BaP in 7 samples exceeded carcinogenic level recommended by EPA;There were potential carcinogenic risk in the study area,which should be paid attention to.