基于铅稳定同位素的多金属复合污染土壤源解析新思路——以西南地区某矿区农田为例

Fresh Insights into Source Identification of Multi-elements in Soil with Stable Pb Isotope:A Case Study of Mining-affected Agricultural Land

本文以我国西南某矿区典型多金属复合污染农田土壤为例,基于铅(Pb)稳定同位素分析,结合矿物学分析,对土壤Pb来源进行定量解析,并针对其他重金属来源进行外推。同位素源解析结果表明,人为源对于土壤重金属的贡献率高达61%~89%,矿渣浸沥与矿区道路扬尘为主要的污染途径。矿物学分析能够辅助印证Pb稳定同位素分析结果,在一定程度上克服由于污染源信号重叠造成的源解析困难。通过相关分析,可以将Pb同位素源解析的结果合理外推,在一定程度上解释其他重金属元素的来源。本文提出的源解析新思路能够高效、准确地解析多金属复合污染土壤中重金属元素的来源,尤其适用于我国土壤多金属复合污染集中连片存在、成因复杂的现状,具有很强的现实意义。

In this study,an integrated approach for the source identification of multi-elements in soil was proposed.Stable Pb isotopes,with the help of mineralogical approaches,have successfully been applied for the source identification of a multi-metal contaminated agricultural soil in a typical mining district in Southwest China.Quantitative analysis of source contributions revealed that the anthropogenic sources accounted for 61%–89%of soil metal accumulation.Stable isotope analysis indicated that mining waste leaching and mining dust raising from the road both contribute to soil contamination,but the signals of these two processes were overlapped,making it impossible to distinguish the contribution of each.Mineralogical analysis has therefore been used to aid in source identification.Considering that concentrations of other metals correlate well with Pb,it is suggested that the results from Pb isotope analysis could be further extrapolated to reveal the sources of other soil metals.