Lee Ben H, D'Ambro Emma L, Lopez-Hilfiker Felipe D, Schobesberger Siegfried, Mohr Claudia, Zawadowicz Maria A, Liu Jiumeng, Shilling John E, Hu Weiwei, Palm Brett B, Jimenez Jose L, Hao Liqing, Virtanen Annele, Zhang Haofei, Goldstein Allen H, Pye Havala O T, Thornton Joel A
Department of Atmospheric Sciences, University of Washington, Seattle, WA, U.S.A.
Department of Chemistry, University of Washington, Seattle, WA, U.S.A.
ACS Earth Space Chem. 2020 Mar 19;4(3):391-402. doi: 10.1021/acsearthspacechem.9b00302.
Organic aerosol (OA) constitutes a significant fraction of atmospheric fine particle mass. However, the precursors and chemical processes responsible for a majority of OA are rarely conclusively identified. We use online observations of hundreds of simultaneously measured molecular components obtained from 15 laboratory OA formation experiments with constraints on their effective saturation vapor concentrations to attribute the VOC precursors and subsequent chemical pathways giving rise to the vast majority of OA mass measured in two forested regions. We find that precursors and chemical pathways regulating OA composition and volatility are dynamic over hours to days, with their variations driven by coupled interactions between multiple oxidants. The extent of physical and photochemical aging, and its modulation by NO, were key to a uniquely comprehensive combined composition-volatility description of OA. Our findings thus provide some of the most complete mechanistic-level guidance to the development of OA descriptions in air quality and Earth system models.
有机气溶胶（OA）在大气细颗粒物质量中占很大比例。然而，导致大部分OA产生的前体物和化学过程很少能得到最终确定。我们利用从15个实验室OA生成实验中获得的数百种同时测量的分子成分的在线观测数据，并对其有效饱和蒸汽浓度加以限制，以确定导致在两个森林地区测量到的绝大部分OA质量的挥发性有机化合物（VOC）前体物和后续化学途径。我们发现，调节OA组成和挥发性的前体物和化学途径在数小时到数天内是动态变化的，其变化由多种氧化剂之间的耦合相互作用驱动。物理和光化学老化的程度及其受一氧化氮（NO）的调节，是对OA进行独特的综合组成-挥发性描述的关键。因此，我们的研究结果为空气质量和地球系统模型中OA描述的发展提供了一些最完整的机理层面的指导。
