Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, PR China.
Collaborative Innovation Centre of Atmospheric Environment and Equipment Technology (CICAEET), Nanjing University of Information Science and Technology, Nanjing 210044, PR China.
Environ Sci Technol. 2024 Apr 30;58(17):7516-7528. doi: 10.1021/acs.est.3c10980. Epub 2024 Apr 17.
Field observations of daytime HONO source strengths have not been well explained by laboratory measurements and model predictions up until now. More efforts are urgently needed to fill the knowledge gaps concerning how environmental factors, especially relative humidity (RH), affect particulate nitrate photolysis. In this work, two critical attributes for atmospheric particles, i.e., phase state and bulk-phase acidity, both influenced by ambient RH, were focused to illuminate the key regulators for reactive nitrogen production from typical internally mixed systems, i.e., NaNO and dicarboxylic acid (DCA) mixtures. The dissolution of only few oxalic acid (OA) crystals resulted in a remarkable 50-fold increase in HONO production compared to pure nitrate photolysis at 85% RH. Furthermore, the HONO production rates () increased by about 1 order of magnitude as RH rose from <5% to 95%, initially exhibiting an almost linear dependence on the amount of surface absorbed water and subsequently showing a substantial increase in once nitrate deliquescence occurred at approximately 75% RH. NaNO/malonic acid (MA) and NaNO/succinic acid (SA) mixtures exhibited similar phase state effects on the photochemical HONO production. These results offer a new perspective on how aerosol physicochemical properties influence particulate nitrate photolysis in the atmosphere.
迄今为止，实验室测量和模型预测都未能很好地解释日间 HONO 源强度的实地观测结果。迫切需要更多的努力来填补有关环境因素（特别是相对湿度 (RH)）如何影响颗粒态硝酸盐光解的知识空白。在这项工作中，我们关注了两个影响大气颗粒物的关键属性，即相态和体相酸度，这两个属性都受到环境 RH 的影响，以阐明来自典型内部混合体系（即 NaNO 和二羧酸 (DCA) 混合物）的反应性氮生成的关键调节剂。仅溶解几个草酸 (OA) 晶体，在 85% RH 下，HONO 的生成量就比纯硝酸盐光解增加了 50 倍。此外，随着 RH 从 <5%增加到 95%，HONO 的生成速率 () 增加了约 1 个数量级，最初几乎呈线性依赖于表面吸收水的量，随后在大约 75% RH 时硝酸盐潮解发生后，迅速增加。NaNO/丙二酸 (MA) 和 NaNO/琥珀酸 (SA) 混合物对光化学 HONO 生成表现出相似的相态效应。这些结果提供了一个新的视角，说明气溶胶物理化学性质如何影响大气中颗粒态硝酸盐的光解。
