Abstract SOA formation is not well predicted in current models in urban area. The interaction among multiple anthropogenic volatile organic compounds is essential for the SOA formation in the complex urban atmosphere. Secondary organic aerosol (SOA) from the photooxidation of naphthalene, 1-methylnaphthalene, and 2-methylnaphthalene as well as individual polycyclic aromatic hydrocarbons (PAHs) mixed with m-xylene or an atmospheric surrogate mixture was explored in the UCR CE-CERT environmental chamber under urban relevant low NOx and extremely low NOx (H2O2) conditions. Addition of m-xylene suppressed SOA formation from the individual PAH precursor. A similar suppression effect on SOA formation was observed during the surrogate mixture photooxidation suggesting the importance of gas-phase chemical reactivity to SOA formation. The SOA growth rate for different PAH-m-xylene mixtures was strongly correlated with initial [HO2]/[RO2] ratio but negatively correlated with initial m-xylene/NO ratio. Decreasing SOA formation was observed for increasing m-xylene/PAHs ratios and increasing initial m-xylene/NO ratio. The SOA chemical composition characteristics such as f44 versus f43, H/C ratio, O/C ratio, and the oxidation state of the carbon OS ¯ c were consistent with a continuously aging with the SOA exhibiting characteristics of both individual precursors. SOA formation from PAHs was also suppressed within an atmospheric surrogate mixture compared to the SOA formed from individual PAHs, indicating that atmospheric reactivity directly influences SOA formation from PAHs.

中文翻译：

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萘和甲基萘与间二甲苯和替代混合物的光氧化形成 SOA

摘要 当前的城市地区模型不能很好地预测 SOA 的形成。多种人为挥发性有机化合物之间的相互作用对于复杂城市大气中 SOA 的形成至关重要。在 UCR CE-CERT 环境室中对萘、1-甲基萘和 2-甲基萘以及与间二甲苯或大气替代混合物混合的单个多环芳烃 (PAH) 进行光氧化产生的二次有机气溶胶 (SOA) 进行了探索在城市相关的低氮氧化物和极低氮氧化物 (H2O2) 条件下。添加间二甲苯抑制了单个 PAH 前体的 SOA 形成。在替代混合物光氧化过程中观察到对 SOA 形成的类似抑制作用，表明气相化学反应对 SOA 形成的重要性。不同 PAH-间二甲苯混合物的 SOA 增长率与初始 [HO2]/[RO2] 比率密切相关，但与初始间二甲苯/NO 比率呈负相关。随着间二甲苯/PAHs 比率的增加和初始间二甲苯/NO 比率的增加，观察到 SOA 形成减少。SOA 的化学成分特征，例如 f44 与 f43、H/C 比、O/C 比和碳 OS ¯c 的氧化态与持续老化一致，SOA 表现出两种单独前驱体的特性。与由单个多环芳烃形成的 SOA 相比，大气替代物混合物中多环芳烃形成的 SOA 也受到抑制，表明大气反应性直接影响多环芳烃形成 SOA。