The Optical Properties of Limonene Secondary Organic Aerosols: The Role of NO3, OH, and O-3 in the Oxidation Processes
The Optical Properties of Limonene Secondary Organic Aerosols: The Role of NO3, OH, and O-3 in the Oxidation Processes
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柠檬烯二次有机气溶胶的光学性质：NO3、OH 和 O-3 在氧化过程中的作用
DOI：
10.1002/2017jd028090
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发表时间：
2018
影响因子：
4.4
通讯作者：
Ge Maofa
中科院分区：
文献类型：
--
作者：
Peng Chao;Wang Weigang;Li Kun;Li Junling;Zhou Li;Wang Lingshu;Ge Maofa
柠檬烯是生物源排放的单萜类化合物的典型代表，在二次有机气溶胶（SOA）的形成中发挥着重要作用。然而，在各种氧化途径下由柠檬烯产生的SOA的光学性质仍然知之甚少。在这项研究中，我们研究了柠檬烯SOA的折射率（RI），从四个氧化条件下产生的腔衰荡光谱仪（CRDS）和光声折射率仪在532和375 nm处操作。我们的研究结果表明，有一个显着的差异，从NO3氧化产生的SOA的RI值相比，其他氧化途径。NO 3氧化、NO x氧化、无NOx的OH氧化和O3氧化实验产生的SOA的RI平均值在532 nm处分别为1.578、1.469、1.495和1.494;在375 nm处分别为1.591、1.527、1.513和1.537，而在所有氧化条件下均未发现可检测的吸收。我们将NO3氧化SOA的高RI值归因于两个因素：SOA中大比例的有机硝酸盐和高分子量二聚体/低聚体。我们的研究结果表明，夜间化学可能会显着影响柠檬烯氧化产物的光学性质。在我们的实验室实验中检索到的在不同氧化条件下在不同波长下产生的柠檬烯SOA的RI值，可以帮助改进模型预测，用于评估生物SOA对全球辐射强迫以及气候变化的影响。
Limonene, a typical proxy of monoterpenes emitted from biogenic sources, plays an important role in secondary organic aerosol (SOA) formation. However, the optical properties of SOA generated from limonene under various oxidation pathways remain poorly understood. In this study, we investigate the refractive index (RI) of limonene SOA produced from four oxidation conditions with cavity ring‐down spectrometer (CRDS) and photoacoustic extinctiometer operated at 532 and 375 nm. Our results show that there is a significant difference in RI values of SOA produced from NO3oxidation compared to other oxidation pathways. The mean values of RI of SOA produced from NO3oxidation, NOxoxidation, OH oxidation with NOx‐free, and O3oxidation experiments are 1.578, 1.469, 1.495, and 1.494 at 532 nm; and 1.591, 1.527, 1.513, and 1.537 at 375 nm, respectively, while no detectable absorption is found in all oxidation conditions. We attribute the high RI values of SOA by NO3oxidation to two factors: a large proportion of organic nitrates and high‐molecular‐weight dimers/oligomers in the SOA. Our study results indicate that the nighttime chemistry may significantly influence the optical properties of limonene oxidation products. The RI values of limonene SOA generated under various oxidation conditions at different wavelengths retrieved in our laboratory experiments could help improve the model predictions for evaluating the effect of biogenic SOA on the global radiative forcing as well as climate change.