State Key Laboratory of Severe Weather & Key Laboratory of Atmospheric Chemistry, Chinese Academy of Meteorological Sciences, Beijing, 100081, China; Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control (AEMPC), Nanjing University of Information Science & Technology, Nanjing, 210044, China.
State Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental Sciences, Shanghai, 200233, China.
Environ Pollut. 2021 Apr 1;274:116570. doi: 10.1016/j.envpol.2021.116570. Epub 2021 Jan 23.
Atmospheric peroxyacetyl nitrate (PAN) and ozone (O) 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, particulate matter with aerodynamic diameter smaller than 2.5 μm (PM), nitrogen oxides (NO), carbon monoxide (CO), and meteorological parameters from December 2016 to November 2017 in Shanghai. Overall, high hourly maximum PAN and O 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 were found in summer, indicating a predominant role of photochemistry in their formation. Unlike in summer, weak or no correlations between PAN and O were featured during the other seasons, especially in winter, due to their different loss pathways. Unexpectedly, positive correlations between PAN and PM 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 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.
大气过氧乙酰硝酸酯 (PAN) 和臭氧 (O) 是两种典型的光化学污染指标，对生态系统和人类健康有不利影响。这些污染物的观测网络在中国发达地区（如华北平原和珠江三角洲）不断扩大，但在长江三角洲（YRD）却很稀疏，这意味着它们的浓度和影响因素仍不为人知。在这里，我们对 2016 年 12 月至 2017 年 11 月在上海进行了为期一年的大气 PAN、O、空气动力学直径小于 2.5 μm 的颗粒物（PM）、氮氧化物 (NO)、一氧化碳 (CO) 和气象参数的测量。总的来说，夏季小时最大 PAN 和 O 分别为 7.0 和 185 ppbv，秋季为 6.2 和 146 ppbv，春季为 5.8 和 137 ppbv，冬季为 6.0 和 76.7 ppbv。大陆气团可能将大气污染物带到采样点，而频繁的海风则带来污染较少的气团。此外，夏季 PAN 和 O 之间存在正相关（R：0.72-0.85），表明光化学在它们的形成中起着主要作用。与夏季不同，其他季节，尤其是冬季，PAN 和 O 之间的相关性较弱或没有，这是由于它们不同的损失途径。出乎意料的是，在所有季节中都发现 PAN 和 PM 之间存在正相关。在夏季，中等相关性可能归因于强烈的光化学作用，它是二次气溶胶和 PAN 形成的共同驱动力。在冬季，高 PM 可能通过 HONO 生成促进 PAN 生成，从而导致良好的正相关。此外，PAN 通过热分解（TPAN）的损失仅占典型冬季事件中总（PAN+TPAN）的一小部分（约 1%），而在夏季则显著达到 14.4 ppbv（总 PAN 的 71.1%）。
