Volatility of Primary Organic Aerosol Emitted from Light Duty Gasoline Vehicles
Volatility of Primary Organic Aerosol Emitted from Light Duty Gasoline Vehicles
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DOI：
10.1021/es504009w
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发表时间：
2015-02-03
影响因子：
11.4
通讯作者：
Kleeman, Michael J.
中科院分区：
文献类型：
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作者：
Kuwayama, Toshihiro;Collier, Sonya;Kleeman, Michael J.
轻型汽油车 (LDGV) 排放的初级有机气溶胶 (POA) 表现出半挥发性行为，其中加热气溶胶和/或稀释气溶胶导致 POA 部分蒸发。单一挥发性分布可以解释 LDGV 排放的 POA 的中值蒸发行为，但这种方法无法捕获在大气相关浓度（2-5 μ g m(-3)）下进行的热脱漆（TD）实验期间测得的 POA 挥发性的全部范围。对已发布的 TD 数据的重新分析结合对新测量结果的分析表明，汽油车排放的 POA 由两种类型的 POA 组成，它们具有明显不同的挥发性分布：一种是低挥发性分布，一种是中等挥发性分布。它们分别对应于燃料燃烧产生的 POA 和机油 POA。同时包含这两种分布的模型能够比使用单一平均值或中值分布的模型 (R-2 = 0.52) 更好地重现实验结果 (R-2 = 0.94)。这些结果表明，LDGV 排放的部分 POA 在典型的大气稀释水平下基本上是非挥发性的。当前研究中测试的车辆中大约 50% 的 POA 排放主要是燃料燃烧产物（本质上是非挥发性的）。需要进一步测试以确定 LDGV 两种 POA 类型的适当车队平均排放率。
Primary organic aerosol (POA) emitted from light duty gasoline vehicles (LDGVs) exhibits a semivolatile behavior in which heating the aerosol and/or diluting the aerosol leads to partial evaporation of the POA. A single volatility distribution can explain the median evaporation behavior of POA emitted from LDGVs but this approach is unable to capture the full range of measured POA volatility during thermodenuder (TD) experiments conducted at atmospherically relevant concentrations (2-5 mu g m(-3)). Reanalysis of published TD data combined with analysis of new measurements suggest that POA emitted from gasoline vehicles is composed of two types of POA that have distinctly different volatility distributions: one low-volatility distribution and one medium-volatility distribution. These correspond to fuel combustion-derived POA and motor oil POA, respectively. Models that simultaneously incorporate both of these distributions are able to reproduce experimental results much better (R-2 = 0.94) than models that use a single average or median distribution (R-2 = 0.52). These results indicate that some fraction of POA emitted from LDGVs is essentially nonvolatile under typical atmospheric dilution levels. Roughly 50% of the vehicles tested in the current study had POA emissions dominated by fuel combustion products (essentially nonvolatile). Further testing is required to determine appropriate fleet-average emissions rates of the two POA types from LDGVs.