Chemical Composition of Gas-Phase Organic Carbon Emissions from Motor Vehicles and Implications for Ozone Production
Chemical Composition of Gas-Phase Organic Carbon Emissions from Motor Vehicles and Implications for Ozone Production
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DOI：
10.1021/es401470e
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发表时间：
2013-10-15
影响因子：
11.4
通讯作者：
Harley, Robert A.
中科院分区：
文献类型：
--
作者：
Gentner, Drew R.;Worton, David R.;Harley, Robert A.
机动车是气相有机碳的主要来源，其中包括挥发性有机化合物（VOCs）和其他蒸气压较低的化合物。这些排放物在大气中发生反应，导致臭氧和二次有机气溶胶（SOA）的形成。我们通过两种方法报告了汽油和柴油车辆中超过230种化合物的排放因子，比以前的研究更详细。首先，我们对2010年夏季公路车辆的废气排放进行了专门的测量。其次，我们使用基于燃料成分的方法，使用废气中总未燃烧燃料的排放因子以及液体燃料样品的详细化学特征来量化废气中未燃烧燃料成分。除了不完全燃烧的产物外，两种方法之间有很好的一致性，不完全燃烧的产物不存在于未燃烧的燃料中，按质量计算占汽油废气的32 +/- 2%和柴油废气的26 +/- 1%。我们计算并比较了柴油废气、汽油废气和非尾气管汽油排放的臭氧生产潜力。按排放质量计算，汽油废气中的气相有机化合物对臭氧产生的潜在影响最大，超过一半的臭氧形成是由于不完全燃烧的产物（例如烯烃和含氧挥发性有机化合物）。当结合美国汽油和柴油燃料销售数据时，这些结果表明汽油源负责69-96%的排放量和79-97%的臭氧形成潜力由机动车排放的气相有机碳。
Motor vehicles are major sources of gas-phase organic carbon, which includes volatile organic compounds (VOCs) and other compounds with lower vapor pressures. These emissions react in the atmosphere, leading to the formation of ozone and secondary organic aerosol (SOA). With more chemical detail than previous studies, we report emission factors for over 230 compounds from gasoline and diesel vehicles via two methods. First we use speciated measurements of exhaust emissions from on-road vehicles in summer 2010. Second, we use a fuel composition-based approach to quantify uncombusted fuel components in exhaust using the emission factor for total uncombusted fuel in exhaust together with detailed chemical characterization of liquid fuel samples. There is good agreement between the two methods except for products of incomplete combustion, which are not present in uncombusted fuels and comprise 32 +/- 2% of gasoline exhaust and 26 +/- 1% of diesel exhaust by mass. We calculate and compare ozone production potentials of diesel exhaust, gasoline exhaust, and nontailpipe gasoline emissions. Per mass emitted, the gas-phase organic compounds in gasoline exhaust have the largest potential impact on ozone production with over half of the ozone formation due to products of incomplete combustion (e.g., alkenes and oxygenated VOCs). When combined with data on gasoline and diesel fuel sales in the U.S., these results indicate that gasoline sources are responsible for 69-96% of emissions and 79-97% of the ozone formation potential from gas-phase organic carbon emitted by motor vehicles.