Puzzling Haze Events in China During the Coronavirus (COVID-19) Shutdown
Puzzling Haze Events in China During the Coronavirus (COVID-19) Shutdown
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冠状病毒 (COVID-19) 停工期间中国令人费解的雾霾事件
DOI：
10.1029/2020gl088533
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发表时间：
2020-06-28
影响因子：
5.2
通讯作者：
Lehmann, Moritz F.
中科院分区：
文献类型：
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作者：
Chang, Yunhua;Huang, Ru-Jin;Lehmann, Moritz F.
令人费解的是，为什么2020年元旦假期(NYH-20)形成的雾霾比2019年(NYH-19)更严重，当时中国正处于前所未有的停机状态，以遏制冠状病毒(CORNAV)的爆发。我们对中国(主要是上海)在NYH-19和NYH-20之前、期间和之后的多个地点的气溶胶化学和物理进行了全面的测量和模拟分析。在NYH-20期间，PM2.5中的二次气溶胶分数(73%)比在NYH-19期间(59%)高得多。在NYH-20期间，PM2.5水平与氮的氧化率显著相关(r(2)=0.77，p<；0.01)，来自中国北部的老化颗粒物阻碍了上海大气中新颗粒物的形成和生长。在NYH-20期间，尽管大气NO2水平总体较低，但沿运输路径观察到的硝酸盐气溶胶形成效率显著增强。简单地说，中国说，有多个案例(例如2008年北京夏季奥运会和2010年上海世博会)与燃烧相关的排放(如NOx)被积极并成功地减少，以暂时改善空气质量。在2020年延长的中国农历新年假期期间(1月24日至2月10日)，整个中国处于前所未有的停机状态，因为大多数人都呆在家里，以减少新型冠状病毒病(新冠肺炎)的传播。机动性、能源需求和工业产出仍远低于正常水平。尽管如此，中国东部地区仍然出现了大面积的灰霾污染。为了阐明雾霾形成的机制，我们分别在2019年和2020年春节假期之前、期间和之后对上海内外的气溶胶化学和物理进行了全面和连续的测量。我们认为，长距离输送和大气化学的协同作用导致NOx有效地转化为颗粒物硝酸盐是上海新冠肺炎春节期间灰霾形成的关键。
It is a puzzle as to why more severe haze formed during the New Year Holiday in 2020 (NYH-20), when China was in an unprecedented state of shutdown to contain the coronavirus (COVID-19) outbreak, than in 2019 (NYH-19). We performed a comprehensive measurement and modeling analysis of the aerosol chemistry and physics at multiple sites in China (mainly in Shanghai) before, during, and after NYH-19 and NYH-20. Much higher secondary aerosol fraction in PM2.5 were observed during NYH-20 (73%) than during NYH-19 (59%). During NYH-20, PM2.5 levels correlated significantly with the oxidation ratio of nitrogen (r(2) = 0.77, p < 0.01), and aged particles from northern China were found to impede atmospheric new particle formation and growth in Shanghai. A markedly enhanced efficiency of nitrate aerosol formation was observed along the transport pathways during NYH-20, despite the overall low atmospheric NO2 levels.Plain Language Summary In China, there are multiple cases (e.g., the 2008 Summer Olympics in Beijing and the 2010 World Expo in Shanghai) when combustion-related emissions (e.g., NOx) were actively, and successfully, reduced to transiently improve air quality. During the extended Chinese Lunar New Year holiday in 2020 (between 24 January and 10 February), whole China was in an unprecedented state of shutdown, because most people were contained in their homes to reduce the spread of the novel coronavirus disease (COVID-19). Mobility, energy demand, and industrial output remained far below their normal levels. Nevertheless, widespread haze pollution still occurred over Eastern China. To elucidate haze formation mechanisms, we performed comprehensive and continuous measurements of aerosol chemistry and physics in and out of Shanghai before, during, and after the Chinese New Year Holiday in 2019 and 2020, respectively. We argue that the synergistic effects of long-range transport and atmospheric chemistry leading to the efficient conversion of NOx to particulate nitrate were the key of haze formation during the Chinese New Year Holiday of the COVID-19 outbreak in Shanghai.