State Environmental Protection Key Laboratory of Vehicle Emission Control and Simulation, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; State Key Joint Laboratory of ESPC, State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, School of Environment, Tsinghua University, Beijing, 100084, China; State Key Laboratory of Plateau Ecology and Agriculture, College of Eco-environmental Engineering, Qinghai University, Xining, 810016, China.
State Key Joint Laboratory of ESPC, State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, School of Environment, Tsinghua University, Beijing, 100084, China.
Environ Pollut. 2021 Dec 1;290:117984. doi: 10.1016/j.envpol.2021.117984. Epub 2021 Aug 16.
Continuous tightening emission standards (ESs) facilitate the reduction of organic gas emissions from gasoline vehicles. Correspondingly, it is essential to update the emissions and chemical speciation of total organic gases (TOGs), including volatile organic compounds (VOCs), intermediate volatility organic compounds (IVOCs), CH, and unidentified non-methane hydrocarbons (NMHCs) for assessing the formation of ozone and secondary organic aerosol (SOA). In this study, TOG and speciation emissions from 12 in-use light-duty gasoline vehicle (LDGV) exhausts, covering the ESs from China II to China V, were investigated on a chassis dynamometer under the Worldwide Harmonized Light-duty Test Cycle (WLTC) in China. The results showed that the most effectively controlled subgroup in TOG emissions from LDGVs was VOCs, followed by the unidentified NMHCs and IVOCs. The mass fraction of VOCs in TOGs also reduced from 61 ± 9% to 46 ± 18% while the IVOCs gently increased from 2 ± 0.4% to 8 ± 4% along with the more stringent ESs. For the VOC subsets, the removal efficiency of oxygenated VOCs (OVOCs) was lower than those of other VOC subsets in the ESs from China IV to V, suggesting the importance of OVOC emission controls for relatively new LDGVs. The IVOC emissions were mainly subject to the ESs, then driving cycles and fuel use. The formation potentials of ozone and SOA from LDGVs decreased separately 96% and 90% along with the restricted ESs from China II-III to China IV. The major contributor of SOA formation transformed from aromatics in the VOC subsets for China II-III vehicles to IVOCs for China IV/V vehicles, highlighting that IVOC emissions from LDGVs are also needed more attentions to control in future.
不断收紧的排放标准（ES）有助于减少汽油车的有机气体排放。相应地，更新总有机气体（TOG）的排放和化学形态，包括挥发性有机化合物（VOCs）、中等挥发性有机化合物（IVOCs）、CH 和未识别的非甲烷碳氢化合物（NMHCs），对于评估臭氧和二次有机气溶胶（SOA）的形成至关重要。本研究在底盘测功机上采用中国轻型车行驶工况（WLTC）对 12 辆在用轻型汽油车（LDGV）的尾气 TOG 和形态排放进行了研究，涵盖了中国 II 至 V 阶段的 ES。结果表明，LDGV 尾气 TOG 排放中控制效果最显著的亚组是 VOCs，其次是未识别的 NMHCs 和 IVOCs。随着 ES 更加严格，TOG 中 VOCs 的质量分数从 61±9%降低到 46±18%，而 IVOCs 则从 2±0.4%缓慢增加到 8±4%。对于 VOC 亚组，在从中国 IV 到 V 的 ES 中，含氧 VOCs（OVOCs）的去除效率低于其他 VOC 亚组，这表明 OVOC 排放控制对于相对较新的 LDGV 很重要。IVOC 排放主要受 ES、驾驶循环和燃料使用的影响。随着中国 II-III 到 IV 阶段 ES 的限制，LDGV 产生臭氧和 SOA 的形成潜力分别降低了 96%和 90%。对于中国 II-III 车辆，VOC 亚组中 SOA 形成的主要贡献者是芳香烃，而对于中国 IV/V 车辆，则是 IVOCs，这突出表明未来也需要更多关注控制 LDGV 的 IVOC 排放。
