中国典型城市臭氧与二次气溶胶的协同增长作用分析

Analysis of synergistic growth effects between ozone and secondary aerosol in typical cities in China

大气PM2.5和O3是中国城市大气中最受关注的大气污染物,它们之间存在着复杂的影响关系.本文将O3,max作为光化学活性指标,把CO作为一次排放源的示踪剂,对2017年4-10月期间北京、上海和广州的臭氧与二次气溶胶的协同增长关系进行深入分析.研究结果表明,不同光化学活性条件下,3个城市在协同增长时段PM2.5质量浓度增长量的均值与估算二次气溶胶质量浓度的变化趋势基本一致;北京和广州在春季、秋季出现协同增长的小时数较多,且北京在各光化学活性水平下的协同增长时段中PM2.5浓度增长量均最大;出现PM2.5和O3协同增长现象时段中上海市风速最大,广州市气温最高,北京市相对湿度范围最大;随着光化学活性的增强,上海和广州两市二次气溶胶的生成量呈倍数增加,其生成量范围分别为13.6~29.2μg·m^-3和9.1~28.7μg·m^-3,北京市二次气溶胶的生成量则变化不大(25.0~34.0μg·m^-3),但各光化学活性水平下的北京二次气溶胶生成量均高于上海和广州.这些研究结果表明北京、上海和广州3个城市的O3污染对二次气溶胶生成协同增长作用明显,而且北京尤其值得关注.

Fine particulate matters(PM2.5) and ozone have been the most concerned air pollutants in China and there is a complex relationship between them. In this study, daily ozone maximum concentrations(O3, max) was used as an indicator of photochemical activity, and CO was used as a tracer for primary emission. The synergetic relationship between ozone and secondary aerosols in Beijing, Shanghai, and Guangzhou during April-October 2017 was analyzed. The results indicate that under different photochemical activities, the pattern of average growth of PM2.5 mass concentration was consistent with the estimated secondary aerosol formation in these three cities during the synergistic growth period;There were the most hours of synergetic growth in spring and autumn for Beijing and Guangzhou, and Beijing had the largest increase in PM2.5 concentration during the synergistic growth period under various photochemical activity levels;Shanghai had the highest wind speed while Guangzhou and Beijing have the highest temperature and the largest range of change in relative humidity, respectively, during the period of synergistic growth. With the enhancement of photochemical activity, the average concentrations of secondary aerosols generated in Shanghai and Guangzhou increased exponentially, with the ranges of 13.6~29.2 μg·m^-3 and 9.1~28.7 μg·m^-3, respectively, but Beijing did not change much(25.0~34.0 μg·m^-3). Under every photochemical activity level, the average concentration of secondary aerosols produced in Beijing was higher than those in Shanghai and Guangzhou. These results indicate that the synergistic growth effects of O3 on secondary aerosol formation in Beijing, Shanghai, and Guangzhou are significant, and the Beijing is of particular concern.