Abstract Volatile organic compounds (VOCs) of motor vehicles contribute greatly to ground-level ozone formation, especially in the megacity regions. While the variations of tailpipe VOC emissions along with the vehicle technologies and road conditions are rarely investigated systematically. Thus, on-road tailpipe VOC emissions from in-use vehicles, including light-duty gasoline vehicles (LDGV), light-duty diesel trucks (LDDT), heavy-duty diesel truck (HDDT) and liquefied petroleum gas-electric hybrid bus (LPGB), were sampled with a combined portable emission measurement system (PEMS). A total of 102 individual VOC species were quantified by a gas chromatography mass spectrometry detector (GC-MSD), and the maximum incremental reactivity (MIR) scale was used to calculate the ozone formation potentials (OFPs). Results showed that aromatics and alkanes were the major VOC groups regardless of the vehicle type, accounting for 68.1–98.0%. For the LDGV, i-pentane, acetone, and propane were the top three VOC species. Naphthalene, dodecane and n-undecane were main VOC constituents in the diesel exhaust. Acetone was the most abundant VOC species for the LPGB, followed by i-pentane, i-butane and n-butane. Road conditions had a significant impact on the VOC emission factors. Specifically, emission factors on urban roads were 3.3–7.0 times those on the highway. The OFPs were 70.7, 128.1, 2189.4 and 124.7 mg O3/km for the LDGV, LDDT, HDDT and LPGB, respectively; aromatics were the main contributors, occupying 49.6–93.4% of the total OFPs. Results indicated that emission factors and dominant species of VOCs were strongly affected by vehicle technologies and road conditions, but aromatics were the major group for both VOC composition and OFPs.

中文翻译：

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汽油、柴油和液化石油气燃料汽车 VOCs 的道路尾气排放特性和臭氧形成潜力

摘要 机动车辆的挥发性有机化合物 (VOCs) 对地面臭氧的形成有很大贡献，尤其是在大城市地区。虽然很少有系统地研究尾气 VOC 排放随车辆技术和道路条件的变化。因此，在用车辆的道路尾气VOC排放量，包括轻型汽油车（LDGV）、轻型柴油卡车（LDDT）、重型柴油卡车（HDDT）和液化石油气-电动混合动力公交车（ LPGB)，使用组合式便携式排放测量系统 (PEMS) 进行采样。通过气相色谱质谱检测器 (GC-MSD) 对总共 102 种单独的 VOC 物种进行量化，并使用最大增量反应性 (MIR) 标度来计算臭氧形成潜力 (OFP)。结果表明，无论车辆类型如何，芳烃和烷烃都是主要的 VOC 组别，占 68.1-98.0%。对于 LDGV，异戊烷、丙酮和丙烷是前三种 VOC 种类。萘、十二烷和正十一烷是柴油机尾气中的主要 VOC 成分。丙酮是 LPGB 中最丰富的 VOC 种类，其次是异戊烷、异丁烷和正丁烷。道路状况对VOC排放因子有显着影响。具体而言，城市道路的排放因子是高速公路的 3.3-7.0 倍。LDGV、LDDT、HDDT和LPGB的OFP分别为70.7、128.1、2189.4和124.7 mg O3/km；芳烃是主要贡献者，占总 OFP 的 49.6-93.4%。