Chen Dongyang, Zhou Li, Wang Chen, Liu Hefan, Qiu Yang, Shi Guangming, Song Danlin, Tan Qinwen, Yang Fumo
College of Architecture and Environment, Sichuan University, Chengdu 610065, China.
College of Architecture and Environment, Sichuan University, Chengdu 610065, China.
J Environ Sci (China). 2022 Apr;114:115-125. doi: 10.1016/j.jes.2021.08.014. Epub 2022 Jan 14.
Surface ozone (O) has become a critical pollutant impeding air quality improvement in many Chinese megacities. Chengdu is a megacity located in Sichuan Basin in southwest China, where O pollution occurs frequently in both spring and summer. In order to understand the elevated O during spring in Chengdu, we conducted sampling campaign at three sites during O pollution episodes in April. Volatile organic compounds (VOCs) compositions at each site were similar, and oxygenated VOCs (OVOCs) concentrations accounted for the highest proportion (35%-45%), followed by alkanes, alkens (including acetylene), halohydrocarbons, and aromatics. The sensitivity of O to its precursors was analyzed using an observation based box model. The relative incremental reactivity of OVOCs was larger than other precursors, suggesting that they also played the dominant role in O formation. Furthermore, the positive matrix factorization model was used to identify the dominant emission sources and to evaluate their contribution to VOCs in the city. The main sources of VOCs in spring were from combustion (27.75%), industrial manufacturing (24.17%), vehicle exhaust (20.35%), and solvent utilization (18.35%). Discussions on VOCs and NO reduction schemes suggested that Chengdu was typical in the VOC-limited regime, and VOC emission reduction would help to prevent and control O. The analysis of emission reduction scenarios based on VOCs sources showed that the emission reduction ratio of VOCs to NO needs to reach more than 3 in order to achieve O prevention. Emission reduction from vehicular exhaust source and solvent utilization source may be more effective.
地表臭氧（O）已成为阻碍中国许多大城市空气质量改善的关键污染物。成都是位于中国西南部四川盆地的一座大城市，春夏季经常出现臭氧污染。为了解成都春季臭氧浓度升高的情况，我们于4月臭氧污染事件期间在三个地点开展了采样活动。各地点的挥发性有机化合物（VOCs）组成相似，氧化挥发性有机化合物（OVOCs）浓度占比最高（35%-45%），其次是烷烃、烯烃（包括乙炔）、卤代烃和芳烃。利用基于观测的箱式模型分析了臭氧对其前体物的敏感性。OVOCs的相对增量反应活性大于其他前体物，表明它们在臭氧形成中也起主导作用。此外，利用正定矩阵因子分解模型识别主要排放源并评估其对城市VOCs的贡献。春季VOCs的主要来源是燃烧（27.75%）、工业制造（24.17%）、汽车尾气（20.35%）和溶剂使用（18.35%）。对VOCs和氮氧化物减排方案的讨论表明，成都处于典型的VOCs限制状态，减少VOCs排放将有助于预防和控制臭氧污染。基于VOCs来源的减排情景分析表明，VOCs与氮氧化物的减排比需要达到3以上才能实现臭氧预防。减少汽车尾气源和溶剂使用源的排放可能更有效。
