Chen Tian-Zeng, Liu Jun, Ma Qing-Xin, Chu Bi-Wu, Zhang Peng, Liu Yong-Chun, Liu Chang-Geng, He Hong
State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
Huan Jing Ke Xue. 2023 Mar 8;44(3):1201-1213. doi: 10.13227/j.hjkx.202203217.
Although the air quality in China has been greatly improved in recent years, the air pollution remains severe. The annual mean PM concentrations have not met the second grade of the National Ambient Air Quality Standards in China and are still much higher than the guideline value of the World Health Organization. Thus, the PM concentration needs to be further reduced. Secondary organic aerosol (SOA) is an important component of PM and has an important impact on air quality, global climate change, and human health. Therefore, understanding the formation mechanism of SOA is an important basis to control SOA and further reduce PM. As an important precursor of SOA, volatile organic compounds (VOCs) can be oxidized by oxidants such as ·OH, NO[KG-*2/3]·, Cl·, and O to generate low volatile organic compounds and further to form SOA through gas-particle partitioning, homogeneous nucleation, aqueous phase reaction, and heterogeneous reaction processes. The formation of SOA can be affected by many factors, such as the types and initial concentrations of VOCs, VOCs/NO ratios, relative humidity (RH), temperature (), seed aerosols, oxidants, aqueous phase process, and photochemical process. The observed SOA concentration is always underestimated by air quality models because a comprehensive understanding of the complexity of SOA chemical composition and formation mechanisms is still lacking, especially that under the highly complex air pollution conditions in China. Therefore, the formation mechanism and influencing factors of SOA under highly complex air pollution conditions have become an important concern in the field of atmospheric sciences. Recently, much laboratory work has focused on the formation of SOA under complex conditions. The research progress of SOA formation from different anthropogenic VOCs are reviewed here, and the methods used and the impact of different influencing factors on SOA formation are introduced. Finally, the key scientific issues that exist in the research of the SOA mechanism at present are put forward, and the future research direction is projected.
尽管近年来中国空气质量有了很大改善，但空气污染仍然严重。年平均颗粒物浓度未达到中国国家环境空气质量标准二级，仍远高于世界卫生组织的指导值。因此，颗粒物浓度需要进一步降低。二次有机气溶胶（SOA）是颗粒物的重要组成部分，对空气质量、全球气候变化和人类健康有重要影响。因此，了解SOA的形成机制是控制SOA和进一步降低颗粒物的重要基础。挥发性有机化合物（VOCs）作为SOA的重要前体，可被·OH、NO·、Cl·和O等氧化剂氧化生成低挥发性有机化合物，并通过气粒分配、均相成核、水相反应和非均相反应过程进一步形成SOA。SOA的形成会受到许多因素影响，如VOCs的类型和初始浓度、VOCs/NO比值、相对湿度（RH）、温度（）、种子气溶胶、氧化剂、水相过程和光化学过程等。空气质量模型总是低估观测到的SOA浓度，因为对SOA化学成分和形成机制的复杂性仍缺乏全面了解，尤其是在中国高度复杂的空气污染条件下。因此，高复杂空气污染条件下SOA的形成机制及影响因素已成为大气科学领域的重要关注点。近年来，许多实验室工作聚焦于复杂条件下SOA的形成。本文综述了不同人为源VOCs生成SOA的研究进展，介绍了所采用的方法以及不同影响因素对SOA形成的影响。最后，提出了目前SOA机制研究中存在的关键科学问题，并展望了未来的研究方向。
