铅同位素示踪在大气降尘重金属污染来源解析中的应用

Tracing Heavy Metal Sources in the Atmospheric Dustfall Using Stable Lead Isotope

为了分析大气降尘中铅的污染来源,解析各污染源对大气降尘铅的相对贡献值,在厦门市不同功能区采集了29个大气降尘样品。用热电质谱仪测定了大气降尘的总铅同位素组成,用ICP-MS测定样品酸可溶相铅同位素组成。结果表明,厦门市大气降尘铅同位素^(206)Pb/^(207)Pb值变化较大,为1.111 9~1.173 8;酸可溶相铅^(206)Pb/^(207)Pb值与福建土壤残渣相^(206)Pb/^(207)Pb值相差较大,表明厦门市大气降尘受人类活动来源铅的影响较大;酸可溶相铅^(206)Pb/^(207)Pb值明显小于总量铅^(206)Pb/^(207)Pb值。铅同位素示踪表明,厦门市大气降尘铅主要来源是燃煤,其次是自然来源和汽车尾气。三元混合模型分析表明,燃煤、自然来源、汽车尾气对厦门市大气降尘总量铅的贡献率分别为48.57%、20.29%、31.14%。

In order to identify the sources of lead pollution in the atmospheric dustfall, as well as comfirm the contribution of each source to such pollution. We obtained 29 atmospheric dustfall samples in the different areas of Xiamen City. Total Pb isotopic composition of each sample was analyzed by thermal mass spectrometry and acid soluble Pb isotopic ratios were determined by ICP-MS. The results indicated that dustfall Pb isotope of ^206Pb/^207Pb in Xiamen City varied widely with the ranges of 1.111 9 to 1.173 8.Pb isotope of ^206Pb/^207Pb in acid solution was different from the ratios in residual form soil of Fujian, indicating the powerful impact of external lead sources. Pb isotopic composition of acid solution decreased significantly than total Pb isotopic composition. Lead isotope tracing techniques showed coal-fired was the main source of lead pollution in Xiamen City dustfall, followed by nature source and vehicle exhaust. Total and acid soluble Pb isotope composition of coal pile was closed to coal-fired, suggesting coal pile was a potential source. The results of ternary hybrid model were as follows： the contribution of coal-fired, nature source and vehicle exhaust to total lead in dustfall were 48.57%, 20.29% and 31.14%, respectively.