Suppression of the phenolic SOA formation in the presence of electrolytic inorganic seed
Suppression of the phenolic SOA formation in the presence of electrolytic inorganic seed
复制标题
存在电解无机种子时抑制酚类 SOA 的形成
DOI：
10.1016/j.scitotenv.2022.158082
复制
发表时间：
2022
影响因子：
9.8
通讯作者：
Jang, Myoseon
中科院分区：
文献类型：
--
作者：
Choi, Jiwon;Jang, Myoseon
酚类化合物在很大程度上归因于野火气体，并迅速与大气氧化剂反应形成持久的苯氧基自由基，影响大气化学和二次有机气溶胶（SOA）的形成。在这项研究中，苯酚oro-cresol光化学氧化在各种条件下（NOx水平，湿度和种子条件）在室外光化学反应器。出乎意料的是，SOA的增长，这两种酚抑制在盐水气溶胶的存在下相比，非种子SOA。这一发现不同于典型的SOA形成的芳烃或生物烃，其显示出显着更高的SOA产率通过有机水溶液反应。苯酚、邻甲酚及其酚类产品（例如，儿茶酚）被吸收在含水气溶胶中，并在阳光下通过多相反应形成苯氧基自由基。所产生的苯氧基自由基在气相和颗粒相之间重新分布。气态苯氧基自由基与臭氧快速反应形成过氧化苯自由基，并通过NOx循环再生，以阻止苯酚氧化和SOA形成。推导了无水相存在下苯酚邻甲酚的明确氧化机理，包括主化学机理（MCM v3.3.1）和过氧自由基加合物的路径，所述过氧自由基加合物来源于向苯酚添加OH自由基以形成低挥发性产物（例如，多羟基芳族化合物）。苯酚oro-cresol产生的气体机制，然后，适用于统一分配气溶胶相反应（UNIPAR）模型预测SOA的形成，通过多相分配的有机物和气溶胶相低聚。该模型很好地模拟了室产生的酚SOA在没有湿无机种子，但显着高估了SOA的质量存在的湿种子。这项研究表明，异构化学形成苯氧基自由基需要包括从酚类，以提高SOA预测。湿无机气溶胶中的苯氧基自由基对大气氧化的抑制可以解释野火期间低SOA的形成。
Phenolic compounds are largely attributed to wildfire gases and rapidly react with atmospheric oxidants to form persistent phenoxy free radicals, which influence atmospheric chemistry and secondary organic aerosol (SOA) formation. In this study, phenol oro-cresol was photochemically oxidized under various conditions (NOxlevels, humidity, and seed conditions) in an outdoor photochemical reactor. Unexpectedly, SOA growth of both phenols was suppressed in the presence of salted aqueous aerosol compared to non-seed SOA. This discovery is different from the typical SOA formation of aromatic or biogenic hydrocarbons, which show noticeably higher SOA yields via organic aqueous reactions. Phenol,o-cresol, and their phenolic products (e.g., catechols) are absorbed in aqueous aerosol and form phenoxy radicals via heterogeneous reactions under sunlight. The resulting phenoxy radicals are redistributed between the gas and particle phases. Gaseous phenoxy radicals quickly react with ozone to form phenyl peroxide radicals and regenerated through a NOxcycle to retard phenol oxidation and SOA formation. The explicit oxidation mechanisms of phenol oro-cresol in the absence of aqueous phase were derived including the Master Chemical Mechanism (MCM v3.3.1) and the path for peroxy radical adducts originating from the addition of an OH radical to phenols to form low volatility products (e.g., multi-hydroxy aromatics). The resulting gas mechanisms of phenol oro-cresol were, then, applied to the Unified Partitioning Aerosol Phase Reaction (UNIPAR) model to predict SOA formation via multiphase partitioning of organics and aerosol-phase oligomerization. The model well simulated chamber-generated phenolic SOA in absence of wet-inorganic seed, but significantly overestimated SOA mass in presence of wet seed. This study suggests that heterogeneous chemistry to form phenoxy radicals needs to be included to improve SOA prediction from phenols. The suppression of atmospheric oxidation due to phenoxy radicals in wet inorganic aerosol can explain the low SOA formation during wildfire episodes.