Zhang Xin, Ma Qiang, Chu Wanghui, Ning Miao, Liu Xiaoqiu, Xiao Fanjie, Cai Ningning, Wu Zhijun, Yan Gang
State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China; Chinese Academy of Environmental Planning, Beijing 100041, China.
Chinese Academy of Environmental Planning, Beijing 100041, China.
Sci Total Environ. 2023 Sep 20;892:164703. doi: 10.1016/j.scitotenv.2023.164703. Epub 2023 Jun 7.
Ozone (O) has become the most critical air pollutant in the Yangtze River Delta (YRD) region of China. Research on the O formation mechanism and its precursor sources (including nitrogen oxides (NO) and volatile organic compounds (VOCs)) could provide a theoretical basis for mitigating O pollution in this region. In this study, simultaneous field experiments were conducted for air pollutants in a typical urban area (Suzhou) in the YRD region in 2022. The capacity of in-situ O formation, O-NO-VOCs sensitivities and sources of O precursors were analyzed. The results showed that in-situ formation contributed 20.8 % of the O concentration in the warm season (April to October) of the Suzhou urban area. Compared with the warm season average, the concentrations of various O precursors increased on pollution days. The O-NO-VOCs sensitivity was the VOCs-limited regime based on the average concentrations during the warm season. O formation was most sensitive to anthropogenic VOCs, of which oxygenated VOCs, alkenes and aromatics were the key species. There was a VOCs-limited regime in spring and autumn, while a transitional regime in summer due to the changes in NO concentrations. This study considered NO emission from VOCs sources and calculated the contribution of various sources to O formation. The results of VOCs source apportionment showed that diesel engine exhaust and fossil fuel combustion had a dominant proportion, but O formation presented significant negative sensitivities to the above two sources because of their high NO emissions. There were significant sensitivities of O formation to gasoline vehicle exhaust and VOCs evaporative emissions (gasoline evaporation and solvent usage). The contribution of VOCs evaporative emissions during the O pollution episode was significantly higher than the average; therefore, controlling VOCs evaporative emissions during the O pollution episode is critical. These results provide feasible strategies to mitigate O pollution.
臭氧（O₃）已成为中国长江三角洲（YRD）地区最关键的空气污染物。对O₃形成机制及其前体来源（包括氮氧化物（NOₓ）和挥发性有机化合物（VOCs））的研究可为减轻该地区的O₃污染提供理论依据。本研究于2022年在YRD地区的一个典型市区（苏州）对空气污染物进行了同步实地实验。分析了原位O₃形成能力、O₃-NOₓ-VOCs敏感性及O₃前体的来源。结果表明，原位形成对苏州城区暖季（4月至10月）O₃浓度的贡献为20.8%。与暖季平均水平相比，污染日各种O₃前体的浓度有所增加。基于暖季的平均浓度，O₃-NOₓ-VOCs敏感性处于VOCs限制状态。O₃形成对人为源VOCs最为敏感，其中含氧VOCs、烯烃和芳烃是关键物种。春季和秋季处于VOCs限制状态，而夏季由于NOₓ浓度的变化处于过渡状态。本研究考虑了VOCs源的NOₓ排放，并计算了各种来源对O₃形成的贡献。VOCs源解析结果表明，柴油发动机尾气和化石燃料燃烧占主导比例，但由于其NOₓ排放较高，O₃形成对上述两种来源呈现出显著的负敏感性。O₃形成对汽油车尾气和VOCs蒸发排放（汽油蒸发和溶剂使用）有显著敏感性。O₃污染事件期间VOCs蒸发排放的贡献显著高于平均水平；因此，控制O₃污染事件期间的VOCs蒸发排放至关重要。这些结果为减轻O₃污染提供了可行的策略。
