喀什市学校土壤重金属污染及健康风险

Heavy metal pollution and human health risk assessment of school soils in Kashgar City,Xinjiang,China

目的了解喀什市学校表层土壤重金属的污染现状及其对人体产生的健康风险。方法于2017年7—8月,选取覆盖喀什市不同功能区的8所学校,分别采集并检测了校园代表性区域表层土壤重金属Cd、Cr、Zn、Pb和Cu的含量,通过地质累积指数法、主成分分析法和健康风险表征模型评价其污染状况。结果喀什市学校土壤Cd、Pb、Zn和Cu的平均含量超过了喀什土壤背景值,其中,Cd超过了《土壤环境质量标准》(GB 15618—1995)中的二级标准。地质累积污染指数表明,土壤重金属的污染程度为Cd>Cu>Zn>Pb>Cr,其中,Cd达到了强污染甚至极强污染程度。主成分分析结果表明,在第1主成分上有较高载荷的是Cd、Pb和Cu;在第2主成分上有较高载荷的是Cr和Zn。健康风险表征模型表明,重金属对儿童的总非致癌风险(HI)和总致癌风险(TCR)均大于成人;土壤Cr、Cd和Pb是喀什市学校土壤非致癌风险最主要的3个贡献因子;土壤Cd是致癌风险最主要的贡献因子。结论喀什市学校土壤Cd污染较严重,且是健康风险最主要的贡献因子,应该引起重视。

Objective To know the pollution status and human health risk of heavy metals from school soils in Kashgar city,Xinjiang,China.Methods From July to August 2017,the contents of heavy metals,including Cd,Cr,Zn,Pb and Cu in the surface soil of eight schools covering different functional areas of Kashgar were determined.The level of heavy metal pollution and human health risk were assessed by the geological accumulation index,principal component analysis and health risk assessment model.Results The average contents of Cd,Pb,Zn and Cu in school soils in Kashgar exceeded the background values of Kashgar soils,and the level of Cd in soil also was higher than the limit for levelⅡof Environmental Quality Standard for Soil(GB 15618-1995).Geoaccumulation index(Igeo)showed that pollution level of heavy metals ranked as Cd>Cu>Zn>Pb>Cr,and the pollution of Cd in soil was very serious.Principal component analysis showed that Cd,Pb and Cu in soil had higher loads in the first principal component;Cr and Zn had higher loads on the second principal component.Health risk assessment model showed that HI and TCR values of heavy metals for children were higher than those for adults.Among the heavy metals,Cr,Cd and Pb in soil were the three most important contributing factors of HI,and Cd was the most important contributing factors of TCR in school soils in Kashgar.Conclusion The pollution of Cd in school soils is serious in Kashgar,and it is the most important contributing factor to health risk,which should be paid attention to.