Acta Chimica Sinica ›› 2020, Vol. 78 ›› Issue (6): 516-527.DOI: 10.6023/A20020036 Previous Articles     Next Articles

Review

基于实验室模拟研究二次有机气溶胶生成及老化机制

王辉a, 俞颖a, 唐荣志a, 郭松a,b   

  1. a 北京大学环境模拟与污染控制国家重点实验室 北京大学环境科学与工程学院 北京 100871;
    b 江苏省大气环境与装备技术协同创新中心 南京信息工程大学 南京 210044
  • 收稿日期:2020-02-16 发布日期:2020-05-30
  • 通讯作者: 郭松 E-mail:songguo@pku.edu.cn
  • 作者简介:王辉,博士研究生,2017年进入北京大学环境科学与工程学院.主要研究方向:大气细颗粒物的来源及化学组成,实验室模拟研究二次有机气溶胶的生成机制;俞颖,硕士研究生.2019年获得北京大学环境科学与工程学院本科学位.主要研究方向:挥发性有机物来源与活性研究、典型源的二次气溶胶生成潜势和特征研究;唐荣志,博士研究生.2016年进入北京大学环境科学与工程学院.主要研究方向:大气中的半挥发性有机物的测量及对二次有机气溶胶的生成的贡献,二次有机气溶胶的组成及来源分析;郭松,博士,北京大学环境科学与工程学院青年千人计划研究员,博士生导师.2005年和2011年分别获得北京大学学士学位和博士学位,2015年获得北京大学职位.主要研究方向为大气气溶胶二次转化机制及其环境效应,具体包括二次有机气溶胶组成及生成机制、黑碳气溶胶老化机制及其环境效应等.承担和参与多项国家自然科学基金委项目和国家重点研发计划项目.
  • 基金资助:
    项目受国家重点研发计划(No.2016YFC0202000)、国家自然科学基金(Nos.51636003,41977179,21677002,91844301)和多相复杂系统国家重点实验室开放课题(No.MPCS-2019-D-09)资助.

Research on Formation and Aging of Secondary Organic Aerosol Based on Simulation Methods

Wang Huia, Yu Yinga, Tang Rongzhia, Guo Songa,b   

  1. a State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871;
    b Cooperative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Engineering, Jiangsu, Nanjing 210044
  • Received:2020-02-16 Published:2020-05-30
  • Supported by:
    Project supported by the National Key R&D Program of China (No. 2016YFC0202000), the National Natural Science Foundation of China (Nos. 51636003, 41977179, 21677002, 91844301) and the Open Research Fund of State Key Laboratory of Multi-phase Complex Systems (No. MPCS-2019-D-09).

Secondary organic aerosol (SOA) is a major component of aerosols in the atmosphere, which plays a crucial role in climate change, regional pollution and human health. Laboratory simulations are usually used to mimic SOA formation. The most commonly used simulation facilities are environmental chambers and potential aerosol mass (PAM) reactors. Here in this work, we review the studies about influencing factors and mechanisms of SOA formation, as well as the evolution of SOA aging. We summarize the influencing factors on SOA yields, i.e. OH exposure, NOx level, and the loading and chemical composition of seed particles. The effects of NOx level (i.e. VOCs/NOx) and OH exposure are nonmonotonic. The NOx level influences the fate of RO2 radicals, so SOA yields will increase and then decrease with the addition of NOx. Similarly, the increase of OH exposure affects the major oxidation mechanism from functionalization to fragmentation, leading to the up and down trend of SOA yields. The higher seed particle loading provides more surface area for condensable products and then increases the SOA yields. The particle acidity favors the uptake process for gas-phase products and promote the SOA formation via further reactions in the condense phase. Trace components e.g. transition metals and minerals can be involved in the SOA formation and aging by catalysis or affecting the uptake of oxidants and their products. Chambers and PAM reactors are usually used to explore SOA formation potential of different sources. SOA formation potential from vehicles will be influenced by engine types, engine loading and composition of fuel. The highest SOA enhancement ratio (SOA/POA) from gasoline engines is about 4~14, when the equivalent photochemical days are 2~3 d. The SOA production mass from gasoline vehicles is from about 10~40 to 400~500 mg/kg fuel. The SOA formation potential is about 400~500 mg/kg fuel. The largest SOA enhancement ratio for biomass burning is 1.4~7.6, which occurs at 3~4 photochemical days. The SOA enhancement ratio from ambient air differs from region to region. However, the highest ratios all occur at the photochemical age of about 2~4 d. We summarize the SOA characteristics evolution with aging. Oxidation state of particles will increase with OH exposure. Changes of H/C and O/C with increasing OH exposure can be plotted in the Van Krevelen diagrams. The slopes of fitted curve range from -1 to 0, indicating OA evolution chemistry involving addition of carboxylic acids or addition of alcohols/peroxides. In addition, the volatility and hygroscopicity of oxidized OA will be higher than primary organic aerosols. In the future, more studies should be focused on developing new technologies to measuring the oxidized intermediate products at a molecular level. Also the researches on the mechanism of SOA formation from complex precursors are also crucial to understand the SOA formation at real atmosphere.

Key words: secondary organic aerosols, yield, formation potential, chambers, oxidation flow tube