基于同位素解析技术的大气降尘铅污染来源研究

Pb pollution source identification and apportionment in the atmospheric deposits based on the lead isotope analysis technique

为了分析大气降尘铅污染的来源,解析各污染源对大气降尘铅的相对贡献率,以陕西某工业区为目标区域,采集24份大气降尘样品以及2份铅锌冶炼厂矿石、2份热电厂燃煤和1份焦化厂燃煤等端元介质,用ICP-MS测定铅质量比及同位素组成(206Pb/207Pb和208Pb/206Pb)。通过比较大气降尘和矿石、燃煤等介质的同位素特征值,分析大气铅污染的来源,结合三元混合模型计算各污染源对大气降尘铅的贡献率。结果表明:大气降尘铅质量比平均值为(1104.1±458.0)mg/kg;铅锌冶炼厂矿石对大气降尘铅的贡献率约为38.8%,热电厂燃煤对大气降尘铅的贡献率约为41.5%,焦化厂燃煤对大气降尘铅的贡献率约为19.7%。研究表明,在大气降尘收集时间段内,大气降尘铅主要来自热电厂燃煤和铅锌冶炼厂铅锌冶炼排放。铅同位素指纹分析技术是一种解析大气降尘铅污染来源的有效手段。

The present paper deals with the Pb pollution in the atmospheric aerosol and the lead source identification and apportionment in some industrial area in Shaanxi in hoping to ascertain the pollution level and the Pb source in the atmospheric deposits,as well as to affirm the contribution rate of each source to such deposits.Based on an industrial area in Shaanxi,we have obtained 24 atmospheric deposit samples,2 ore samples in a lead-zinc smelter,and 2 coal samples in a thermal-power plant and another coal sample in a coking plant,respectively.After careful investigation and analysis,we have found the Pb content and isotope composition（206Pb/207Pb and 208Pb/206Pb） of all the samples by using the inductive plasma mass spectrometry（ICP-MS） for the pollution source analysis.Comparing Pb isotope ratios in atmospheric deposition with those in coal samples in a thermal-power plant and that in a coking plant,we have successfully identified the Pb source in the atmospheric deposit as well as in the smelter-derived materials in the area under investigation.And then we have worked out the contribution rate of each Pb source to the atmospheric deposits in combination with the ternary hybrid model.The results of our investigation can be stated as follows： The average Pb content of the atmospheric deposits was（1104.1±458.0） mg/kg.The Pb contribution rate to the ore from the lead-zinc smelter,the coal exhaust from the thermal power plant and that from the coking plant to atmospheric deposits are 38.8%,41.5% and 19.7%,respectively.Thus,it can be concluded that the Pb pollution in the atmospheric deposits comes mainly from the emission of the thermal power plant and the lead-zinc smelter in the study area during the atmospheric deposits-collecting period.The Pb isotope ratio proves to be a useful means to identify the Pb pollution source in the atmospheric deposits.