基于稳定氢同位素的太原市大气单环芳烃来源

Stable hydrogen isotope analyses and source apportionments of mono-aromatic compounds in Taiyuan, China

采集太原市城北和城南区域环境空气和5类污染源挥发性有机物样品,测定样品中典型单环芳烃稳定氢同位素(δD)组成,基于同位素质量平衡原理计算单环芳烃从源到环境空气受体的δD初始混合值,探讨单环芳烃来源.结果表明,柴油挥发源、溶剂挥发源、汽油挥发源(97#)、汽油挥发源(95#)、机动车尾气(97#)、机动车尾气(95#)和民用燃煤源中单环芳烃δD范围依次为:(−138.7‰~−115.5‰)、(−147.0‰~−121.0‰)、(−150.8‰~−117.6‰)、(−131.8‰~−113.8‰)、(−171.2‰~−120.0‰)、(−138.9‰~−102.7‰)和(−168.3‰~−142.3‰),民用燃煤源中单环芳烃δD显著贫重氢同位素(D)组成,机动车尾气源与汽油挥发源中苯的δD相比显著贫D,可用于探索污染物转化过程;城北和城南环境空气中δD范围为(−131.7‰~−115.1‰)和(−131.9‰~−74.9‰),δD初始混合值为−138.4‰和−173.9‰,体现了其来源差异.

Mono-aromatic compounds samples from five various emission sources and ambient air of two areas(south area of the city and north area of the city)were collected in Taiyuan.The stable hydrogen isotope(δD)composition characteristics and conversion processes of samples was identified and analyzed.The source apportionment was discussed on the basis of the initial mixedδD value calculated through the hydrogen isotope mass balance equation.The results revealed that theδD values of mono-aromatic in samples of five emission sources were with a range of(−138.7‰~−115.5‰)of diesel volatilization,(−147.0‰~−121.0‰)of solvent evaporation,(−150.8‰~−117.6‰)of gasoline volatilization(97^#),(−131.8‰~−113.8‰)of gasoline volatilization(95^#),(−171.2‰~−120.0‰)of vehicle exhaust(97^#),(−138.9‰~−102.7‰)of vehicle exhaust(95^#),and(−168.3‰~−142.3‰)of domestic coal combustion.TheδD value of benzene was significantly lower in vehicle exhaust than in gasoline volatilization.The δD values of mono-aromatic in the north area of the city ranged from −131.7‰ to−115.1‰,while−131.9‰to−74.9‰ in the south area Taiyuan city.The initial mixed values ofδD in the north of city and the south of city were−138.4‰ and−173.9‰,respectively.The results showed that the sources of mono-aromatic compounds in the atmosphere were different in the south area and north area of Taiyuan city.