State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China; Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
J Environ Sci (China). 2019 May;79:256-263. doi: 10.1016/j.jes.2018.11.011. Epub 2018 Nov 30.
Current atmospheric quality models usually underestimate the level of ambient secondary organic aerosol (SOA), one of the possible reasons is that the precursors at different concentrations may undergo different oxidation processes and further affect SOA formation. Therefore, there is a need to perform more chamber studies to disclose the influence. In this work, SOA formation over a wide range of initial precursor concentrations (tens of ppb to hundreds of ppb levels) was investigated in a 30 m indoor smog chamber, and mainly through the analysis of multiple generations of VOCs detected from HR-ToF-PTRMS to expound the difference in the oxidation process between low and high precursor concentrations. Compared to high initial concentrations, gas-phase intermediates formed at low concentrations had a higher intensity by about one order of magnitude, and the low-volatility compounds also had a higher formation potential due to the competition between semi-volatile intermediates and precursors with oxidants. In addition, the formed SOA was more oxidized with higher f value (0.14 ± 0.02) and more relevant to real atmosphere than that formed at high concentrations. This work should help to deeply understand SOA formation and improve the performance of air quality models for SOA simulation.
目前的大气质量模型通常低估了环境二次有机气溶胶（SOA）的水平，其中一个可能的原因是不同浓度的前体可能经历不同的氧化过程，并进一步影响 SOA 的形成。因此，需要进行更多的腔室研究来揭示这种影响。在这项工作中，在一个 30 米的室内烟雾箱中研究了初始前体浓度（几十 ppb 到几百 ppb 水平）范围内的 SOA 形成，并主要通过从 HR-ToF-PTRMS 检测到的多代 VOCs 的分析来阐述低浓度和高浓度前体之间氧化过程的差异。与高初始浓度相比，低浓度下形成的气相中间产物的强度约高一个数量级，由于半挥发性中间产物和与氧化剂竞争的前体之间的竞争，低挥发性化合物也具有更高的形成潜力。此外，形成的 SOA 具有更高的 f 值（0.14±0.02），并且比在高浓度下形成的 SOA 更氧化，与实际大气更相关。这项工作应该有助于深入了解 SOA 的形成，并提高空气质量模型对 SOA 模拟的性能。
