成都市臭氧重污染成因与来源解析

Causes and sources of heavy ozone pollution in Chengdu

采用来源解析的方法对2020年成都市发生的一次较为严重的臭氧污染事件进行了研究.结果表明,此次污染过程呈现从清洁-污染-清洁的变化趋势,污染持续时间长达9d,最大臭氧小时浓度达到258.8μg/m^(3).气象因素在成都臭氧污染中的影响不可忽略,其中温度与臭氧浓度呈现显著正相关关系,东北风主要出现在污染前和污染后,可能起到稀释扩散臭氧浓度的作用;东南风主要出现在污染时期,存在对臭氧的传输作用.烯烃和芳香烃对成都的臭氧形成贡献显著,是成都臭氧污染治理应注意的重要前体物.汽油车排放(+燃烧源)作为影响成都VOCs的重要来源(27.3%~58.7%),且在污染期间有显著的升高,是成都臭氧污染治理应重点关注的前体物来源.在重污染天气,对污染情景的精准判断是治理污染的前提.通过对成都臭氧污染期间的气象因素及前体物来源进行综合分析,发现成都存在本地生成与传输共同作用和传输主导两种污染情景.在本地生成与传输共同作用污染情景下,应采取控制成都市前体物排放的措施并密切关注臭氧传输情况,加强联防联控;而在传输主导的污染情景下,控制本地前体物排放效果不大,应注重区域联防联控.

Based on the method of source analysis, a relatively serious ozone pollution event in Chengdu in 2020 was studied. The results shown that, the pollution event showed a trend of clean-pollution-clean, and the pollution event lasted for 9 days, with the maximum hourly ozone concentration reaching 258.8μg/m^(3). Meteorological conditions played a vital role in the formation of O;in Chengdu. Among them, temperature and O;concentration shown a significant positive correlation. The northeast wind mainly appeared before and after the pollution event, which might dilute and diffuse the concentration of ozone;the southeast wind mainly appeared during the pollution event and had a transmission effect on O;. Alkenes and aromatics played a leading role in the O;formation in Chengdu which were important precursors for ozone pollution control. Gasoline vehicle emissions(+combustion sources) were the primary source of volatile organic compounds(VOCs) in Chengdu(27.3%~58.7%), and had a significant increase during the pollution event. Chengdu should focus on effective control measures for gasoline vehicle emissions(+ combustion sources)in the treatment of ozone pollution. In the heavy ozone pollution events, accurate identification of the cause of O3 pollution is a prerequisite for pollution control. Based on the comprehensive analysis of meteorological factors and ozone sources in Chengdu, two pollution scenarios were found: scenario of synergy between local production and transport, and scenario of regional transport.Therefore, under the pollution scenario of synergy between local production and transport, it is necessary to take measures to control the emission of precursors, pay close attention to the transmission of ozone, and strengthen joint prevention and control. Under the pollution scenario of regional transport, the control measures should be focused on regional joint prevention and control.