Cui Yumeng, Chen Kunpeng, Zhang Haofei, Lin Ying-Hsuan, Bahreini Roya
Department of Environmental Sciences, University of California, Riverside, Riverside, California 92521, United States.
Department of Chemistry, University of California, Riverside, Riverside, California 92521, United States.
ACS EST Air. 2024 Feb 29;1(4):247-258. doi: 10.1021/acsestair.3c00041. eCollection 2024 Apr 12.
The chemical and optical properties of secondary organic aerosols (SOA) have been widely studied through environmental chamber experiments, and some of the results have been parametrized in atmospheric models to help understand their radiative effects and climate influence. While most chamber studies investigate the aerosol formed from a single volatile organic compound (VOC), the potential interactions between reactive intermediates derived from VOC mixtures are not well understood. In this study, we investigated the SOA formed from pure and mixtures of anthropogenic (phenol and 1-methylnaphthalene) and/or biogenic (longifolene) VOCs using continuous-flow, high-NO photooxidation chamber experiments to better mimic ambient conditions. SOA optical properties, including single scattering albedo (SSA), mass absorption coefficient (MAC), and refractive index (RI) at 375 nm, and chemical composition, including the formation of oxygenated organic compounds, organic-nitrogen compounds (including organonitrates and nitro-organics), and the molecular structure of the major chromophores, were explored. Additionally, the imaginary refractive index values of SOA in the multi-VOC system were predicted using a linear-combination assumption and compared with the measured values. When two VOCs were oxidized simultaneously, we found evidence for changes in SOA chemical composition compared to SOA formed from single-VOC systems, and this change led to nonlinear effects on SOA optical properties. The nonlinear effects were found to vary between different systems.
通过环境舱实验，对二次有机气溶胶（SOA）的化学和光学性质进行了广泛研究，部分结果已在大气模型中参数化，以帮助理解其辐射效应和气候影响。虽然大多数舱内研究调查的是由单一挥发性有机化合物（VOC）形成的气溶胶，但对于VOC混合物衍生的反应中间体之间的潜在相互作用，人们还了解得不够充分。在本研究中，我们使用连续流动、高NO光氧化舱实验，研究了由人为源（苯酚和1-甲基萘）和/或生物源（长叶烯）VOCs的纯物质及其混合物形成的SOA，以更好地模拟环境条件。我们探究了SOA的光学性质，包括375nm处的单次散射反照率（SSA）、质量吸收系数（MAC）和折射率（RI），以及化学成分，包括含氧有机化合物、有机氮化合物（包括有机硝酸盐和硝基有机物）的形成，以及主要发色团的分子结构。此外，还使用线性组合假设预测了多VOC系统中SOA的虚折射率值，并与测量值进行了比较。当两种VOC同时被氧化时，我们发现与单VOC系统形成的SOA相比，SOA的化学成分发生了变化，这种变化导致了对SOA光学性质的非线性影响。发现不同系统之间的非线性效应有所不同。
