上海市大气气溶胶中铅污染的综合研究

Comprehensive Study of Lead Pollution in Atmospheric Aerosol of Shanghai

采用质子激发X荧光分析(PIXE)、质子微探针、电感耦合等离子质谱(ICP-MS)和扩展X-射线吸收精细结构谱(EXAFS)等分析手段研究上海市大气气溶胶PM10中铅的浓度、化学种态和铅的源解析.研究发现2002年冬天和2003年上海地区大气气溶胶PM10中铅的平均浓度分别为369ng/m3和224ng/m3,铅的化学种态主要是PbCl2、PbSO4和PbO,燃煤烟尘、钢铁烟尘和汽车尾气是主要排放源,它们对气溶胶中铅的贡献率分别为50%、35%和15%.

The lead contamination, lead species and source assignment were studied by a combination of several analytical techniques such as Proton-induced X-ray emission analysis （PIXE）, Proton microprobe （μ-PIXE）, Inductively coupled plasma-mass spectrometry （ICP-MS） and extended X-ray absorption fine structure （EXAFS） techniques. The results indicate that the lead concentration in the air of Shanghai gradually decreased over the last years. The atmospheric lead concentration of PM10 in the winter of 2002 was 369ng·m^-3 which had declined by 28% in 2001, and in the winter of 2003 it decreased further to 237ng·m^-3. The main lead species in the samples collected in the winter of 2003 were probably PbCI2, PbSO4 and PbO. The source apportionment was calculated in terms of the combination of lead isotope ratios and lead mass balance method, assisted by single particle analysis with μPIXE and pattern recognition. The results suggest that the major contributors of atmospheric lead pollution in Shanghai are the coal combustion dust; the metallurgic dust and vehicle exhaust particles, with a contribution around 50% , 35 % and 15 % , respectively. It probably is the first time to give a city a quantitative estimation of lead pollution contribution from emission sources. The influence from leaded gasoline was still present in the atmosphere by four or five years after the phasing out of leaded gasoline.