基于稳定同位素与多元素的土壤铅污染源解析

以杭州市富阳区典型工矿企业附近农田为研究对象，基于单因子指数法及内梅罗指数法对土壤重金属污染状况进行了评价，并采用稳定同位素与多元素特征指纹结合多元统计定量解析研究区内农田土壤重金属铅污染的来源，建立基于铅稳定同位素与多元素特征指纹结合主成分-聚类分析的农田土壤铅污染源解析技术.结果表明：研究区域内电镀厂和冼矿场附近的农田土壤受重金属污染很严重，两个地区的铅污染均达到重度污染水平.根据不同污染源及土壤的铅同位素比值（²⁰⁷Pb/²⁰⁶Pb、²⁰⁸Pb/²⁰⁶Pb），利用源解析软件Isosource分析不同潜在污染源对土壤铅污染的贡献率，结果显示电镀废弃物、废水对电镀厂附近农田土壤铅污染的累计贡献率达70.5%，冼矿场堆放的矿石、尾矿对附近农田土壤铅污染的累计贡献率达71.7%.为了进一步解析土壤铅污染来源，对电镀厂和冼矿场污染源样品中28种多元素含量进行主成分-聚类分析，结果显示不同来源样品的多元素组成差别较大，电镀厂附近农田土壤的多元素组成与电镀废弃物和废水相似度最高，冼矿场附近农田土壤的多元素组成与矿石和尾矿相似度最高.因此，基于铅稳定同位素比值与多元素特征指纹结合主成分-聚类分析得出电镀厂排放的固废、废水和冼矿场堆放的矿石、尾矿是造成附近土壤铅污染的主要原因，也证明基于铅稳定同位素与多元素特征进行铅污染源解析具有较高的准确度和可靠性.

Source apportionment of lead pollution in soil based on the stable isotope and multi element characteristics

Farmlands near electroplating factories and mining areas were selected as the research objects in this study, the single factor index method and Nemero index method were used to evaluate the pollution status of soil heavy metals, and the source of soil Pb was investigated based on the Pb stable isotope and multi element characteristics analysis combined with principal component analysis and cluster analysis. The contribution rate of each pollution source was further quantitatively identified. The results indicated that the farmland soil samples near the electroplating factories and mining areas were seriously polluted by heavy metals, and the lead pollution in both areas reached the severe pollution degree. According to the Pb isotope ratios (²⁰⁷Pb/²⁰⁶Pb、²⁰⁸Pb/²⁰⁶Pb) in samples from different pollution sources and the farmland soil, the contribution rates of each pollution source were calculated by Isosource software. The results showed that the cumulative contribution rates of electroplating waste effluents and solid waste to the Pb pollution in farmland soil nearby was 70.5%, the corresponding contribution rate of ore and tailings piled up in mining area was 71.7%. To further identify the sources of lead pollution in soil, the contents of 28 multi-element in samples from different pollution sources and the farmland soil were studied by principal component analysis and cluster analysis. The results revealed that the multi-element composition of different sources was quite different. The multi-element composition of farmland soil near electroplating factory had the highest similarity with electroplating waste effluents and solid waste, and the multi-element composition of farmland soil near mining areas had the highest similarity with the ore and tailings. Therefore, it could be concluded that the waste effluents and solid waste discharged from the electroplating factory, and ore and tailings piled up in the mining area were the major sources of Pb pollution in farmland soils nearby, respectively. Our analysis also suggested that source apportionment of Pb based on Pb stable isotope ratio and multi-element composition combined with principal component analysis and cluster analysis had the high accuracy and reliability.