2020年成都市典型臭氧污染过程特征及敏感性

2020年4月24日至5月6日成都市臭氧(O3)和细颗粒物(PM2.5)复合污染过程期间,在成都市城区开展大气臭氧及其前体物(NO,、VOCs)和气象参数观测实验,基于观测数据采用OBM模型对市区臭氧敏感性和主控因子进行识别,并采用PMF模型对关键VOCs物种进行来源解析.结果表明,臭氧超标日各污染物浓度均有所上升,VOCs物种中芳香烃和含氧(氮)化合物上升幅度较大;成都市城区O3超标天对应的臭氧处于显著VOCs控制区,芳香烃和烯烃对O3生成最为敏感,且存在削减NOx的不利效应;结合VOCs来源解析,城区VOCs主要来源:移动源(22.4％)、餐饮及生物质燃烧源(21.8％)、工业源(15.1％)和溶剂使用源(9.3％),臭氧超标天溶剂使用源、餐饮及生物质类燃烧源贡献率明显上升.成都市城区春季应以VOCs减排为重点,并加大芳香烃和烯烃相关源控制力度.

Chemical Characteristics and Contaminant Sensitivity During the Typical Ozone Pollution Processes of Chengdu in 2020

The online monitoring of meteorology and ozone (O₃) level and its precursors and parameters was carried out in the urban areas of Chengdu City during the combined ozone (O₃) pollution process and fine particulate matter (PM_2.5) from April to May, 2020. The pollution characteristics of O₃ and its precursors and the sensitivity of O₃ generation to its precursors were analyzed based on the OBM model and PMF. The study showed that the concentration of pollutants increased on the day when the ozone exceeded the standard, and the aromatic hydrocarbons and oxygen-containing (nitrogen) compounds in volatile organic compound (VOCs) species increased greatly. In the urban area of Chengdu, the ozone corresponding to the excessive O₃ days was during the significant VOCs control, and aromatic hydrocarbons and olefin were the most sensitive to O₃ generation and had the adverse effect of reducing NO_x. Combined with the analysis of the source of VOCs, it was found that the main sources of VOCs in the urban areas were mobile sources (22.4%), catering and biomass combustion sources (21.8%), industrial sources (15.1%), solvent sources (9.3%), and solvent sources when the ozone level exceeded the standard. The contribution rate of catering and biomass combustion sources have increased significantly. It is suggested that Chengdu urban areas should focus on VOC emission reduction in the spring and strengthen the control of aromatic hydrocarbon-and olefin-related sources.