基于铅同位素解析技术的土壤铅污染来源研究

On the lead pollution source identification and the apportionment in the regional soil via the Pb isotope analysis method

通过分析耕层土壤铅污染的程度,分析耕层土壤铅污染的来源,解析各污染源对土壤铅污染的相对贡献率。以陕西某工业区为研究区域,采集大气降尘、耕层土壤(0~20 cm)和背景土壤样品,用ICPMS测定铅元素质量比及同位素比率(^(206)Ph/^(207)Pb和^(208)Pb/^(206)Pb),分析耕层土壤铅污染的来源,结合二元混合模型计算各污染源对耕层土壤铅的贡献率。结果表明,耕层土壤铅质量比范围为21.8~40.0mg/kg,平均值为27.1 mg/kg;背景土壤铅质量比范围为19.1~22.1mg/kg,平均值为21.4 mg/kg;大气降尘铅质量比范围为570.2~2 221.7 mg/kg,平均值为1 062.36 mg/kg。该区域铅锌冶炼括动对耕层土壤铅的贡献率约为18.43%,焦化厂燃煤对耕层土壤铅的贡献率约为9.36%,热电厂燃煤对耕层土壤铅的贡献率约为19.71%,背景土壤对耕层土壤的贡献率约为52.5%。背景土壤是耕层土壤铅污染的主要来源。

The present paper intends to identify the Pb pollution origin in the regional soil and its scattering situation in the regional soil via the Pb isotope analysis method in some industrial areas in Shaanxi in hoping to ascertain the pollution level and the Pb source in the soil as well as to affirm the concentration rate of each source to such soils.Based on the study of an industrial area in Shaanxi,we have collected some atmospheric deposit samples,the background soil samples and the tilled soil samples respectively in a number of ways.A careful investigation and analysis help us to make clear and confirm the Pb content and isotope composition（^（206）Pb/^（207）Pb and ^（208）Pb/^（206）Pb）of all the samples by using a set of inductive plasma mass spectrometry（ICP-MS） for the pollution source analysis.And,then,in comparison with the Pb isotope content rate in the tilled land soil with those in contrast background soil and atmospheric deposits,we have successfully worked out the Pb source in the tilled land soil.What is more,we have also made clear the contribution rate of each Pb source to the tilled soil samples with the help of the ternary hybrid model.The results of our investigation can be stated as follows：the Pb content rate of the tilled soil stands for 21.8-40.0 mg/kg,with the average value being 27.1 mg/kg.As to the Pb content rate in the atmospheric deposits,it turns out to be 570.2-2 221.7 mg/kg,with the average value being 1 062.36 mg/kg.On the other hand,the Pb content rate of the background soil has been found equal to 19.1-22.1 mg/kg,with the average value being 21.4 mg/kg.In addition,the Pb contribution rate to the background soil,the ore from the leadzinc smelter,the coal exhaust from the thermal power plant and that from the coking plant to tilled soil,they are responsible for 52.5%,18.43%,9.36%,and 19.71%,respectively.Thus,it can be concluded that the Pb contamination situation in the tilled soil samples comes mainly from the background soil in the area under study.