宝鸡市长青镇冶炼厂周边居住区土壤重金属污染特征与风险评估

Pollution and health risk assessment of heavy metals in soil neighborhoods around a smelter in Changqing town of Baoji city

采用实地采样与室内测试方法对宝鸡市长青镇冶炼厂周边居住区土壤重金属（Pb、Zn、Cd、Cr）的含量进行了测定分析,利用地质累积指数法和改进的综合污染指数法对其土壤环境质量进行了评价,应用美国环境保护署（USEPA）推荐的健康风险评价模型对研究区土壤重金属在3种暴露途径下的健康风险做出了初步评价,并用相关性分析法和聚类分析法对污染源进行了解析。结果表明,研究区域13个采样点表层土壤中重金属元素Pb、Zn、Cd和Cr的质量浓度分别为52.43-96.42、82.54-151.32、0.065-0.309、59.26-104.13mg/kg,平均值分别为67.55、107.20、0.120、75.23mg/kg,其值均高于陕西和中国的背景值,说明土壤受到不同程度污染;地质累积指数法进一步证实研究区域土壤已经受到4种重金属不同程度的污染,且处于中等污染及以内;而4种重金属的综合污染评价显示,除4号村庄、7号村庄处于中等污染外,其余均处于轻污染至中污染;研究区域中,4种重金属在3种暴露途径下对儿童的非致癌健康风险均大于成人,但对成人和儿童均不存在显著的非致癌健康影响和非致癌健康总风险,其风险顺序是经口摄入〉经皮肤接触〉经呼吸吸入;其次,Cd对成人和儿童经呼吸暴露途径均不存在致癌健康风险,而Cr对成人和儿童经呼吸暴露所致的致癌健康风险处于不可接受状态;另外,源解析结果显示,Pb和Zn具有相同的污染源,而Cd和Cr具有不同的污染源。

The concentrations of soil heavy metals in neighborhoods around a smelter in Changqing Town of Baoji City in northwest China were analyzed using field sampling and laboratory test.Environmental quality was evaluated by using the index of geoaccumulation and improved comprehensive pollution index method.The health risks of Pb,Zn,Cd and Cr caused by three exposure ways were assessed using USEPA health risk assessment model.The pollution sources were discriminated by correlation analysis and cluster analysis.The results showed that the concentration ranges of Pb,Zn,Cd and Cr were 52.43-96.42,82.54-151.32,0.065-0.309 and 59.26-104.13mg/kg in topsoil（0-20cm）,respectively,and the average concentration were 67.55,107.20,0.120 and 75.23mg/kg.The concentrations of Pb,Zn,Cd and Cr were higher than Shaanxi Province background values and China background values,which indicated the soils in the studied area had been polluted by the heavy metals of Pb,Zn,Cd and Cr in different degrees.The results of the index of geoaccumulation further confirm that the soils in the research area were polluted by heavy metals,and belonging to the moderately polluted and below.The comprehensive evaluation of pollution showed that the others were in light contaminated to moderately contaminated except for four sampling site and seven sampling site moderately contaminated.The health risk assessment showed that children were more vulnerable than adults for single factor non-carcinogenic risk and composite non-carcinogenic risk of three exposure ways of four heavy metals in soil,which meant there was no single factor non-carcinogenic risk and composite non-carcinogenic risk for adults and children.Non-carcinogenic risk of corresponding different exposure routes for adults and children were in the following order：oral intake〉dermal contact intake〉inhalation intake.The carcinogenic risk levels of Cd were no carcinogenic risk for adults and children,the carcinogenic risk levels of Cr were unacceptable.The pollution sources discrimination indicated Pb and Zn were a common source,Cd and Cr were different source.