珠江三角洲机动车挥发性有机物排放化学成分谱研究

根据珠三角地区机动车挥发性有机物排放(VOCs)贡献特征,选取在用轻型汽油车、轻型柴油车、液化石油气(LPG)出租车和摩托车,采用底盘测功机及实际道路测试,获取了以上车型尾气排放的VOCs化学成分(59种非甲烷碳氢化合物)特征谱.轻型汽油车以及摩托车的尾气组成中芳香烃含量最高,其次为烷烃;苯系物、异戊烷以及乙烯占轻型汽油车尾气VOCs组成的54.5%;苯系物、异戊烷以及乙炔占摩托车尾气组成的54.6%.轻型柴油车的尾气组成中烷烃比例最高,其次是芳香烃和烯炔烃.除了苯和甲苯,正十一烷、正十二烷、正癸烷、乙烯、丙烯、1-丁烯亦在柴油车尾气中占有重要比例(41.2%).LPG出租车尾气组成以丙烷、正丁烷、异丁烷为主,并伴有较高比例的1,2,4-三甲基苯、1,2,3-三甲基苯和甲苯.与类似研究比较结果表明:由于在油品、排放标准及采样与分析方法等方面的差异,机动车排放源成分谱相关研究结果仍存在一定的差异性,建议对机动车成分谱研究在尾气采样与分析方法等方面进行规范化和标准化.

Source characteristics of VOCs emissions from vehicular exhaust in the Pearl River Delta region

Based upon VOCs emission contributions from on-road mobile sources in the Pearl River Delta (PRD), light-duty gasoline-fueled vehicles (LDGV), light-duty diesel-fueled vehicles (LDDV), liquefied petroleum gas (LPG)-fueled taxis and motorcycles were chosen to develop VOCs emission source profiles including 59 PAMs compounds by using chassis dynamometer and road measurements. VOCs compositions of LDGV and motorcycles were similar featuring high percentages of aromatics and alkanes. Benzene, toluene, ethyl benzene, xylenes and trimethyl benzene (BTEX),i-pentane and acetylene made up 54.5% of detected VOCs in LDGV exhausts, while BTEX, i-pentane and ethylene were responsible for 41.2% compositions in motorcycle exhaust. For LDDV exhaust, percentage of alkanes was the highest, followed by aromatics and alkenes. In addition to benzene and toluene, n-undecane, n-dodecane, n-decane, ethylene, propylene and 1-butene were also abundant, in diesel-fueled vehicular exhaust. LPG vehicular exhaust were characterized by propane and i/n-butane, as well as 1,2,4 & 1,2,3-trimethylbenzene and toluene. Compared to similar studies, differences in vehicle emission source profiles still exist due to differences in fuel quality and emission standards, and inconsistence in source sampling and chemical analytical standards. Regulations and guidelines on emission source sampling and chemical analysis are needed in future vehicle emission source profile studies.