Secondary organic aerosols produced from photochemical oxidation of secondarily evaporated biomass burning organic gases: Chemical composition, toxicity, optical properties, and climate effect
Secondary organic aerosols produced from photochemical oxidation of secondarily evaporated biomass burning organic gases: Chemical composition, toxicity, optical properties, and climate effect
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DOI：
10.1016/j.envint.2021.106801
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发表时间：
2021-07-31
影响因子：
11.8
通讯作者：
Rudich, Yinon
中科院分区：
文献类型：
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作者：
Fang, Zheng;Li, Chunlin;Rudich, Yinon
生物质燃烧（BB）是初级有机气溶胶（POA）的重要来源。这些 POA 含有很大一部分半挥发性有机化合物，并且可以在运输稀释过程中将它们释放到气相中。这种蒸发的化合物被称为“二次蒸发的 BB 有机气体 (SBB-OG)”，以将其与更多研究的初级排放物区分开来。 SBB-OG 通过与大气氧化剂反应形成二次有机气溶胶 (SOA)，从而可能影响人类健康和地球的辐射预算。在这项研究中，从木材热解中收集的焦油材料被用作阴燃阶段 BB 中 POA 的替代品，并用于在实验室中不断释放 SBB-OG。使用氧化流反应器研究了在不存在 NOx 的情况下 SBB-OG 的 OH 引发氧化，并对 SOA 的化学、光学和毒理学特性进行了全面表征。羰基化合物是已识别的 SOA 物种中最丰富的物种。暴露于环境相关剂量的最老化 SOA 的人肺上皮细胞没有表现出可检测到的细胞死亡率。采用二硫苏糖醇(DTT)测定法表征SOA的氧化电位，其DTT消耗率为15.5+/-0.5pmol·min·1μg(-1)。 SOA的光散射性能与BB-POA相当，但光吸收率较低，在360-600 nm波长范围内虚折射率小于0.01。基于米氏理论的计算表明，大气相关尺寸为50-400 nm的纯机载SOA具有冷却效果；当作为涂层材料时，这些SOA可以抵消空气中的黑碳气溶胶带来的变暖效应。
Biomass burning (BB) is an important source of primary organic aerosols (POA). These POA contain a significant fraction of semivolatile organic compounds, and can release them into the gas phase during the dilution process in transport. Such evaporated compounds were termed "secondarily evaporated BB organic gases (SBB-OGs)" to distinguish them from the more studied primary emissions. SBB-OGs contribute to the formation of secondary organic aerosols (SOA) through reactions with atmospheric oxidants, and thus may influence human health and the Earth's radiation budget. In this study, tar materials collected from wood pyrolysis were taken as proxies for POA from smoldering-phase BB and were used to release SBB-OGs constantly in the lab. OH-initiated oxidation of the SBB-OGs in the absence of NOx was investigated using an oxidation flow reactor, and the chemical, optical, and toxicological properties of SOA were comprehensively characterized. Carbonyl compounds were the most abundant species in identified SOA species. Human lung epithelial cells exposed to an environmentally relevant dose of the most aged SOA did not exhibit detectable cell mortality. The oxidative potential of SOA was characterized with the dithiothreitol (DTT) assay, and its DTT consumption rate was 15.5 +/- 0.5 pmol min 1 mu g(-1). The SOA present comparable light scattering to BB-POA, but have lower light absorption with imaginary refractive index less than 0.01 within the wavelength range of 360-600 nm. Calculations based on Mie theory show that pure airborne SOA with atmospherically relevant sizes of 50-400 nm have a cooling effect; when acting as the coating materials, these SOA can counteract the warming effect brought by airborne black carbon aerosol.