Jiangxi Province Key Laboratory of the Causes and Control of Atmospheric Pollution, East China University of Technology, Nanchang, 330013, China; School of Water Resources and Environmental Engineering, East China University of Technology, Nanchang, 330013, China.
School of Environmental Science and Engineering, Shandong University, Jinan, China.
Environ Pollut. 2020 Jan;256:113428. doi: 10.1016/j.envpol.2019.113428. Epub 2019 Nov 1.
As the most important gas-phase alkaline species, atmospheric ammonia (NH) contributes considerably to the formation and development of fine-mode particles (PM), which affect air quality and environmental health. Recent satellite-based observations suggest that the North China Plain is the largest agricultural NH emission source in China. However, our isotopic approach shows that the surface NH in the intraregional urban environment of Beijing-Tianjin-Shijiazhuang is contributed primarily by combustion-related processes (i.e., coal combustion, NH slip, and vehicle exhaust). Specifically, the Batch fractionation model was used to describe the partitioning of gaseous NH into particles and to trace the near-ground atmospheric NH sources. With the development of haze pollution, the dynamics of δN-NH were generally consistent with the fractionation model. The simulated initial δN-NH values ranged from -22.6‰ to -2.1‰, suggesting the dominance of combustion-related sources for urban NH. These emission sources contributed significantly (92% on hazy days and 67% on clean days) to the total ambient NH in urban cities, as indicated by a Bayesian mixing model. Based on the Batch fractionation model, we concluded the following: 1) δN-NH can be used to model the evolution of fine-mode aerosols and 2) combustion-related sources dominate the near-ground atmospheric NH in urban cities. These findings highlight the need for regulatory controls on gaseous NH emissions transported from local and surrounding industrial sources.
作为最重要的气相碱性物质，大气氨（NH）对细颗粒（PM）的形成和发展有重要贡献，从而影响空气质量和环境健康。最近基于卫星的观测表明，华北平原是中国最大的农业 NH 排放源。然而，我们的同位素方法表明，北京-天津-石家庄的区域内城市环境中的地表 NH 主要来源于燃烧相关过程（即煤炭燃烧、NH 逸出和车辆尾气）。具体而言，使用批量分馏模型来描述气态 NH 向颗粒中的分配，并追踪近地面大气 NH 的来源。随着霾污染的发展，δN-NH 的动力学通常与分馏模型一致。模拟的初始 δN-NH 值范围为-22.6‰至-2.1‰，表明城市 NH 的主要来源为燃烧相关源。贝叶斯混合模型表明，这些排放源对城市环境中总环境 NH 有显著贡献（霾天 92%，晴天 67%）。基于批量分馏模型，我们得出以下结论：1）δN-NH 可用于模拟细颗粒气溶胶的演变，2）燃烧相关源主导城市近地面大气 NH。这些发现强调需要对来自当地和周边工业源的气态 NH 排放进行监管控制。
