Impact of air transport and secondary formation on haze pollution in the Yangtze River Delta: In situ online observations in Shanghai and Nanjing
Impact of air transport and secondary formation on haze pollution in the Yangtze River Delta: In situ online observations in Shanghai and Nanjing
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航空运输和二次形成对长三角雾霾污染的影响：上海和南京的现场在线观测
DOI：
10.1016/j.atmosenv.2020.117350
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发表时间：
2020
影响因子：
5
通讯作者：
Aijun Ding
中科院分区：
文献类型：
--
作者：
Peng Sun;Wei Nie;Tianyi Wang;Xuguang Chi;Xin Huang;Zheng Xu;Caijun Zhu;Lei Wang;Ximeng Qi;Qi Zhang;Aijun Ding
尽管近年来中国经常发生雾霾污染，但我们对与空气输送和天气系统相关的区域污染事件的了解有限。在这项研究中，我们同时进行了两次密集的活动，以测量2017年冬季和2018年夏季上海和南京郊区细颗粒物（PM2.5）的高时间分辨率化学成分。上海（南京）冬、夏季PM2.5平均质量浓度分别为53.9（65.7）μg m− 3和32.8（37.3）μg m− 3。在冬季，极端灰霾事件同步观测到的增强的贡献，硝酸盐在两个站点和低挥发性氧化有机气溶胶（LV-OOA）在上海。来自中国北方的远距离输送在两个站点同时发生的事件中起着重要作用。受冷锋影响，南京的污染持续时间较长，而上海的PM上升较快。在夏季，空气质量通过城市群的长三角负责污染事件。低风速有利于一次气溶胶的积累，高臭氧水平所指示的强光化学活性促进二次气溶胶的形成，导致硝酸盐、类烃有机气溶胶（HOA）和半挥发性氧化有机气溶胶（SV-OOA）对PM的贡献增加。此外，在上海清洁的情况下，两天后在南京观察到以硝酸盐和有机气溶胶增加为主的污染事件。我们的研究结果强调了区域或次区域排放控制对减轻城市群（如中国东部的长三角）雾霾污染的重要性。
Despite frequent haze pollution in China in recent years, our knowledge of regional pollution episodes associated with air transport and synoptic weather systems is limited. In this study, we conducted two intensive campaigns simultaneously to measure the highly time-resolved chemical composition of fine particles (PM2.5) in suburban Shanghai and Nanjing during the winter of 2017 and the summer of 2018. The average PM2.5mass concentrations were 53.9 (65.7) μg m−3and 32.8 (37.3) μg m−3in Shanghai (Nanjing) in winter and summer, respectively. In winter, extreme haze episodes were observed synchronously with enhanced contributions of nitrate at both sites and of low-volatile oxidized organic aerosol (LV-OOA) in Shanghai. Long-range transport from Northern China was demonstrated to play an important role in the episodes, which occurred simultaneously at both sites. Influenced by the cold fronts, Nanjing had a relatively longer pollution duration, whereas Shanghai exhibited faster PM increases. In summer, air masses passing through the city-clusters of the YRD were responsible for the pollution episodes. Low wind speeds, which favored the accumulation of primary aerosols, and strong photochemical activity indicated by high ozone level, which promoted the formation of secondary aerosols, resulted in elevated contributions of nitrate, Hydrocarbon-like organic aerosol (HOA) and semi-volatile oxidized organic aerosol (SV-OOA) to PM in Shanghai. In addition, a pollution episode dominated by increases of nitrate and organic aerosols was observed in Nanjing two days later despite the clean situation in Shanghai. Our results highlight the importance of regional or sub-regional emission control to mitigate haze pollution in city clusters, such as the YRD in Eastern China.