广西珊瑚矿区土壤重金属污染特征与健康风险评价

Characteristics and health risk assessment of heavy metal pollution in soil around Shanhu Mining Area in Guangxi

  • 摘要: 为总结锡矿区周边土壤重金属污染与健康风险规律,以广西典型石英脉型锡矿床周边表层土壤样品(244件)为研究对象,采用单项污染指数法、内梅罗综合污染指数法、主成分分析法、Pb同位素及人体健康风险模型开展系统的评价工作。结果表明:珊瑚锡矿区周边土壤重金属平均浓度由高到低依次为As>Zn>Cr>Pb>Cu>Ni>Cd>Hg,其中,Pb、Zn、Cr、As超出广西土壤环境背景值;重金属污染评价显示As为区内污染最严重的元素,其次为Cd,余下元素均以未污染和轻度污染为主;所有样品内梅罗综合污染指数为0.53~340.35,以警戒值和轻度污染为主,重度污染占总样本的26.2%,证实区内存在一定的重金属污染现象。Pb同位素与溯源分析表明,研究区土壤中Cu、Pb、Zn、Ni、Cd、As污染主要来自矿化体的风化作用,矿业开发的贡献可以忽略;Cr、Hg代表背景值,为自然源。健康风险评估显示,土壤中As为主要风险因子,经口摄入为最主要的暴露途径,儿童健康更易受到重金属污染的威胁。珊瑚矿区周边土壤重金属污染整体受控于自然过程,建议加强对As、Cd元素的监测工作,避免对居民健康产生不利影响。

     

    Abstract: To summarize the patterns of heavy metal pollution in soil around tin mining areas and the associated health risks, we investigated 244 surface soil samples collected around typical quartz-vein-type tin deposits in Guangxi. A systematic evaluation was conducted using the single pollution index method, Nemerow comprehensive pollution index method, principal component analysis (PCA), Pb isotope analysis, and human health risk assessment model. The results showed that the average contents of heavy metals in the soil around Shanhu Tin Mining Area followed the order of As > Zn > Cr > Pb > Cu > Ni > Cd > Hg from highest to lowest. Among these heavy metals, the contents of Pb, Zn, Cr, and As exceeded the soil environmental background values of the Guangxi Zhuang Autonomous Region. The heavy metal pollution assessment indicated that As was the most severely polluting element in the study area, followed by Cd, while the remaining elements were mainly characterized by no pollution or mild pollution. The Nemerow comprehensive pollution index of all samples ranged from 0.53 to 340.35, with most samples falling into the categories of "warning level" and "mild pollution", and severely polluted samples accounting for 26.2% of the total. These results confirmed the existence of certain heavy metal pollution in the study area. Pb isotope analysis and source identification revealed that the pollution of Cu, Pb, Zn, Ni, Cd, and As in the soil was mainly derived from the weathering of mineralized bodies, while the contribution of mining activities was negligible. Cr and Hg represented background values and were of natural origin. The health risk assessment indicated that As in the soil was the primary risk factor, oral ingestion was the dominant exposure pathway, and children were more vulnerable to the threats of heavy metal pollution. In conclusion, the heavy metal pollution in the soil around Shanhu Mining Area was generally controlled by natural processes. It was therefore recommended to strengthen the monitoring of As and Cd to prevent adverse effects on residents' health.

     

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