二次有机气溶胶相态的研究现状与展望

SOA 的体相扩散系数远低于液态 SOA,从而阻碍 SOA 的物质传输和化学转化等物理化学过程.目前,SOA 相态的研究主要集中在有限体系,
例如α-蒎烯、异戊二烯、甲苯等挥发性有机物为前体物产生的 SOA,缺乏实际大气 SOA 的相态信息.此外,对无机盐影响 SOA 相态的认
识也十分有限.本文提出重污染形成过程中,相态可能是二次颗粒物快速增长、转化的重要影响因素之一.因此,结合外场观测、实验室研究
二次有机气溶胶(SOA)在大气颗粒物中的 占 比 可 达 20%~90%[1]. 在 我 国 , 碳 质 气 溶 胶 占
PM2.5 比值平均为 30%,城市地区远高于其它地 区[2].以北京为例, SOA 的背景浓度约为 2μg/m3,
二次有机碳对大气总有机碳的贡献占比为 20%~50%[3].SOA 对区域空气质量和全球气候的 影响十分显著[4].但目前对 SOA 生成机制和环境
Advances in the phase state of secondary organic aerosol. LIU Yue-chen, WU Zhi-jun*, HU Min (State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China). China Environmental Science, 2017,37(5)：1637~1645 Abstract：This review presents an overview of the analytical techniques for detecting the phase state of secondary organic aerosol (SOA), the effects of phase state on mass transport, and the types of SOA being studied. The previous studies showed that SOA could be solid, semi-solid, or liquid. The bulk diffusion coefficients for solid and semi-solid can be much smaller than those for liquid SOA, and therefore lead to limited mass transfer of species and different formation and transformation of SOA compared to liquid systems. However, only several types of SOA precursors have been studied, such as α-pinene, isoprene, and toluene. The phase state of SOA in urban areas as well as the effects of coexisting inorganic species on their phase state is largely unknown. Our analysis shows that the phase state perhaps play an important role in the rapid increase of secondary particle mass concentration during heavily hazed events. Therefore, it is important to study the phase state of SOA and the absorption and transfer of the key active gases at the surface and in the bulk of aerosols in the polluted environments, which will help us to further understand the mechanisms of the formation and evolution of secondary particles in China. Key words：secondary organic aerosol (SOA)；phase state；viscosity；diffusion coefficients
中国环境科学 2017,37(5)：1637~1645
China Environmental Science
二次有机气溶胶相态的研究现状与展望
刘玥晨,吴志军*,胡 敏 (北京大学环境科学与工程学院,环境模拟与污染控制国家重点联合实验室,北京
100871)
摘要：总结了国内外对二次有机气溶胶(SOA)相态的研究进展,结果显示不同条件下 SOA 可能是固态、不定形态、液态.固态和不定形态
以及多层动力学模型研究重污染形成过程中 SOA 的相态及其对关键反应活性气体的吸附、传输等影响机制,有助于深入理解我国复合大
气污染条件下二次颗粒物的生成转化机制.
关键词：二次有机气溶胶(SOA)；相态；粘度；扩散系数
中图分类号：X513
文献标识码：A
Leabharlann Baidu
文章编号：1000-6923(2017)05-1637-09
效应的认识仍然十分有限.相态作为 SOA 的一
个重要性质,与 SOA 生成机制和环境行为密切
相关.
因此,针对 SOA 相态的研究有助于推进对 SOA 生成机制的深入理解[5].
物质存在时的物理状态称为相态[6].根据粘 度可以将颗粒物分为液态(粘度<102Pa⋅s)、半固