太原市采暖期PM10中PAHs的碳同位素组成及源贡献率

在太原市7个点位采集采暖期PM10样品,用气相色谱-同位素质谱仪测定环境空气PM10和污染源(煤烟尘和机动车尾气)中9种多环芳烃(PAHs)的碳同位素组成(δ13C),并根据碳同位素质量平衡原理定量环境空气PAHs的源贡献率.结果表明:煤烟尘中PAHs随环数增加贫13C,机动车尾气中PAHs随环数增加富13C;各点位PAHs的δ13C值差别不大,变化趋势与煤烟尘基本一致,煤烟尘是城市PAHs的主要污染源;煤烟尘对各点位荧蒽和苯并a]蒽的贡献率都大于机动车尾气,对 的贡献率与机动车尾气相当,煤烟尘是各点位荧蒽和苯并a]蒽的主要来源, 是二者共同作用的结果;煤烟尘和机动车尾气对全市环境空气中荧蒽、苯并ghi]荧蒽、苯并a]蒽和苯并b+k]荧蒽贡献率比都约为7:3,太原市环境空气PAHs污染属于煤烟尘和机动车尾气的复合污染.

Carbon isotope compositions and source apportionments of PAHs in PM10 of Taiyuan City during heating period.

Atmospheric particulates with the aerodynamical diameter ￡10mm (PM10) were collected during heating period in Taiyuan City. The carbon isotopic compositions of 9 polycyclic aromatic hydrocarbons (PAHs) on particulates associated with atmosphere and pollution sources (soot and vehicle exhaust) were measured using the gas chromatography-isotope ration mass spectrograph, and then the contributions of the two sources to atmospheric PAHs were calculated based on the notion of carbon isotope mass balance. The PAHs from soot were 13C-depleted with increasing ring size, but the ones from vehicle exhaust were in inverse. The δ13C values of PAHs in Taiyuan city were almost identical, and the variation trend was the same as the one of soot, which indicated that the soot was the primary pollution source of PAHs in this city. For each sampling sites, the apportionments of soot to Fluoranthene and Benza]anthracene were all larger than that of vehicle exhaust, but the contribution of soot to Chrysene was the same as the one of vehicle exhaust, so the soot was the primary pollution source of Fluoranthene and Benza]anthracene, and the Chrysene was the combined effect of soot and vehicle exhaust. The contributions of soot versus the ones of vehicle exhaust to Fluoranthene, Benzoghi]fluoranthene, Benza]anthracene and Benzob+k]fluoranthene were all in proportion of 7:3, which based on the city’s average δ13C values of PAHs, that is, the atmospheric pollution of PAHs in Taiyuan city was combined pollution of coal soot and vehicle exhaust.