太原市工、商业区PM10中PAHs碳同位素组成及来源

利用中流量大气综合采样仪采集太原市工业区和商业区PM₁₀样品,使用GC/IRMS技术分析了PAHs的δ13C值(碳同位素组成),并根据碳同位素质量平衡计算了煤烟尘和机动车尾气对2类功能区的贡献率. 结果表明:工业区PM₁₀中PAHs的δ13C值在-26.0‰~-24.5‰之间,随环数增加呈贫13C趋势,与煤烟尘δ13C值的变化趋势一致,表明煤烟尘是工业区的一个主要污染源；商业区PAHs的δ13C值在-26.6‰~-26.2‰之间,较工业区显著贫13C,商业区与工业区的污染源有明显差异；除机动车尾气和煤烟尘外,工业区和商业区还有其他污染源输入,其中工业区有生物质燃烧排放输入,商业区有机动车曲轴箱润滑油残渣输入；煤烟尘和生物质燃烧对工业区的贡献率分别为59.3%~70.8%和29.2%~40.7%,表明工业区煤烟污染严重；机动车对商业区PAHs的贡献率在86.1%~95.8%之间,是商业区PM₁₀中PAHs的主要排放源,其中润滑油残渣的贡献率(在40.9%~85.3%之间)最大,机动车尾气的贡献率在8.3%~54.9%范围内,而煤烟尘的贡献率(在4.2%~13.9%之间)最小. 

Carbon Isotope Compositions and Source Apportionment of PAHs Associated with PM10 of Industrial and Commercial Districts in Taiyuan City

The carbon isotope technique has became a potential tool for the source apportionment of organic compounds and widely used to identify the specific sources of PAHs (polycyclic aromatic hydrocarbons) associating with soil, sediment and atmospheric particles. In order to address the sources of atmospheric PAHs in the industrial and commercial districts, the atmospheric PM₁₀ samples were collected by the medium volume samplers, the δ13C (carbon isotopic composition) of PAHs associated with PM₁₀, and emission sources (coal soot and vehicle exhaust) were measured by GC/IRMS, and the contributions of such suspected sources to atmospheric PAHs were calculated according to the carbon isotope mass balance. The results showed that δ13C values of PAHs ranged from -26.0‰ to -24.5‰ in industrial district, and became more depleted in 13C with increasing ring size which was the same variation trend as coal soot PAHs. The coal soot was the primary pollution source of industrial district. The δ13C range of atmospheric PAHs in commercial district was from -26.6‰ to -26.2‰, which was more depleted in 13C than that of industrial district PAHs. The pollution sources of industrial and commercial districts were significantly different. The pollution sources of industrial and commercial districts should contain other ones except for the vehicle exhaust and coal soot. Specifically, the so-called other source was the biomass burning for industrial district and the crankcase oil for commercial district. The contributions of coal soot and biomass burning emission to industrial district were 59.3% to 70.8% and 29.2% to 40.7%, respectively. This indicated that the industrial district was seriously polluted by coal soot. The contribution of vehicles to commercial district, ranging from 86.1% to 95.8%, included two parts, which were the range of 40.9% to 85.3% for crankcase oil and the range of 8.3% to 54.9% for vehicle exhaust respectively. The contribution of coal soot was the minimum among pollution sources ranging from 4.2% to 13.9%. This indicated that the vehicle was the primary emission source of atmospheric PAHs in commercial district. In further research, a new method to identify the pollution sources accurately and a comprehensive data base about isotope compositions of organic compounds from pollution sources will be required to reveal the contributions of various sources to the specific receptor.