Combined Smog Chamber/Oxidation Flow Reactor Study on Aging of Secondary Organic Aerosol from Photooxidation of Aromatic Hydrocarbons.
Combined Smog Chamber/Oxidation Flow Reactor Study on Aging of Secondary Organic Aerosol from Photooxidation of Aromatic Hydrocarbons.
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DOI：
10.1021/acs.est.3c04089
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发表时间：
2023-09
影响因子：
11.4
通讯作者：
Tianzeng Chen;Jun Liu;Biwu Chu;Y. Ge;P. Zhang;Qingxin Ma;Hong S. He
中科院分区：
文献类型：
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作者：
Tianzeng Chen;Jun Liu;Biwu Chu;Y. Ge;P. Zhang;Qingxin Ma;Hong S. He
二次有机气溶胶（SOA）是大气细颗粒物（PM2.5）的重要组成部分，其理化性质在老化过程中会发生显著变化。在本研究中，我们采用烟雾室（SC）和氧化流反应器（OFR）组成的组合研究了由典型芳香烃甲苯光氧化形成的气相有机中间体和SOA的连续老化过程。结果表明，当OH暴露从2.6 × 1011增加到6.3 × 1011分子cm-3 s（等效老化时间2.01 ~ 4.85 d）时，SOA质量浓度（2.9±0.05 ~ 28.7±0.6 μg cm-3）和校正后的SOA产率（0.073 ~ 0.26）显著提高。随着老化过程的进行，气相有机中间体（主要是半挥发性和中间挥发性物质，S/IVOCs）的光化学老化过程不断产生有机酸和多种含氧氧化产物。随后，多代氧化产物分裂到气溶胶阶段，而光化学老化过程中SOA的功能化而不是碎片化占主导地位，导致老化后的SOA产率比在SC中高得多。我们的研究表明，在空气质量模型中应考虑SOA产率作为OH暴露的函数，以改进SOA模拟，从而准确评估对SOA特性和区域空气质量的影响。
Secondary organic aerosol (SOA) is a significant component of atmospheric fine particulate matter (PM2.5), and their physicochemical properties can be significantly changed in the aging process. In this study, we used a combination consisting of a smog chamber (SC) and oxidation flow reactor (OFR) to investigate the continuous aging process of gas-phase organic intermediates and SOA formed from the photooxidation of toluene, a typical aromatic hydrocarbon. Our results showed that as the OH exposure increased from 2.6 × 1011 to 6.3 × 1011 molecules cm-3 s (equivalent aging time of 2.01-4.85 days), the SOA mass concentration (2.9 ± 0.05-28.7 ± 0.6 μg cm-3) and corrected SOA yield (0.073-0.26) were significantly enhanced. As the aging process proceeds, organic acids and multiple oxygen-containing oxidation products are continuously produced from the photochemical aging process of gas-phase organic intermediates (mainly semi-volatile and intermediate volatility species, S/IVOCs). The multigeneration oxidation products then partition to the aerosol phase, while functionalization of SOA rather than fragmentation dominated in the photochemical aging process, resulting in much higher SOA yield after aging compared to that in the SC. Our study indicates that SOA yields as a function of OH exposure should be considered in air quality models to improve SOA simulation, and thus accurately assess the impact on SOA properties and regional air quality.