Simultaneous observation of atmospheric peroxyacetyl nitrate and ozone in the megacity of Shanghai, China: Regional transport and thermal decomposition
Simultaneous observation of atmospheric peroxyacetyl nitrate and ozone in the megacity of Shanghai, China: Regional transport and thermal decomposition
复制标题
中国上海特大城市大气过氧乙酰硝酸盐和臭氧的同步观测：区域传输和热分解
DOI：
10.1016/j.envpol.2021.116570
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发表时间：
2021
影响因子：
8.9
通讯作者：
Hongli Wang
中科院分区：
文献类型：
--
作者：
Gen Zhang;Shengao Jing;Wanyun Xu;Yang Gao;Chao Yan;Linlin Liang;Cheng Huang;Hongli Wang
大气中的过氧乙酰硝酸盐（PAN）和臭氧（O3）是光化学污染的两个典型指示物，对生态系统和人类健康都有不利影响。这些污染物的观测网络在中国的发达地区不断扩大，如华北平原（NCP）和珠江三角洲（PRD），但在长江三角洲（YRD）却很稀疏，这意味着对它们的浓度和影响因素仍然知之甚少。在此，我们对上海市2016年12月至2017年11月的大气PAN、O3、空气动力学直径小于2.5 μm的颗粒物（PM2.5）、氮氧化物（NOx）、一氧化碳（CO）和气象参数进行了为期一年的测量。总的来说，高小时最大PAN和O3被发现在夏季分别为7.0和185 ppbv，6.2和146 ppbv在秋季，5.8和137 ppbv在春季，和6.0和76.7 ppbv在冬季。大陆气团可能将大气污染物带到采样地点，而频繁的海风则带来污染较少的气团。此外，夏季PAN与O3之间呈正相关（R：0.72-0.85），表明光化学在其形成中起主导作用。与夏季不同的是，在其他季节，尤其是冬季，PAN和O3之间的相关性较弱或没有相关性，这是由于它们的损失途径不同。出乎意料的是，PAN和PM 2.5之间的正相关关系，发现在所有的季节。在夏季，中等的相关性可以归因于强烈的光化学作用作为一个共同的驱动器在二次气溶胶和PAN的形成。在冬季，高PM 2.5可能通过HONO的产生促进PAN的产生，从而产生良好的正相关性。此外，PAN的热分解损失（TPAN）仅占一小部分（约10%）。在典型的冬季事件中，总的（PAN + TPAN）为14.4ppbv（占总量的71.1%），而在夏季则显著达到14.4ppbv。·夏季PAN和O3的小时最大值分别为7.0和185 ppbv。·大陆气团携带高负荷的大气污染物到采样点。·夏季PAN热分解损失大。
Atmospheric peroxyacetyl nitrate (PAN) and ozone (O 3 ) are two typical indicators for photochemical pollution that have adverse effects on the ecosystem and human health. Observation networks for these pollutants have been expanding in developed regions of China, such as North China Plain (NCP) and Pearl River Delta (PRD), but are sparse in Yangtze River Delta (YRD), meaning their concentration and influencing factors remain poorly understood. Here, we performed a one-year measurement of atmospheric PAN, O 3 , particulate matter with aerodynamic diameter smaller than 2.5 μm (PM 2.5 ), nitrogen oxides (NO x ), carbon monoxide (CO), and meteorological parameters from December 2016 to November 2017 in Shanghai. Overall, high hourly maximum PAN and O 3 were found to be 7.0 and 185 ppbv in summer, 6.2 and 146 ppbv in autumn, 5.8 and 137 ppbv in spring, and 6.0 and 76.7 ppbv in winter, respectively. Continental air masses probably carried atmospheric pollutants to the sampling site, while frequent maritime winds brought in less polluted air masses. Furthermore, positive correlations (R: 0.72–0.85) between PAN and O 3 were found in summer, indicating a predominant role of photochemistry in their formation. Unlike in summer, weak or no correlations between PAN and O 3 were featured during the other seasons, especially in winter, due to their different loss pathways. Unexpectedly, positive correlations between PAN and PM 2.5 were found in all seasons. During summer, moderate correlation could be attributed to the strong photochemistry acting as a common driver in the formation of secondary aerosols and PAN. During winter, high PM 2.5 might promote PAN production through HONO production, hence resulting in a good positive correlation. Additionally, the loss of PAN by thermal decomposition (TPAN) only accounted for a small fraction (ca. 1%) of the total (PAN + TPAN) during a typical winter episode, while it significantly reached 14.4 ppbv (71.1% of the total) in summer. • Hourly maximum PAN and O 3 were measured as 7.0 and 185 ppbv in summer, respectively. • Continent air masses carried high loadings of atmospheric pollutants to sample site. • Large loss of PAN by thermal decomposition was found in summer.