Chemistry of Secondary Organic Aerosol Formation from Reactions of Monoterpenes with OH Radicals in the Presence of NO x
Chemistry of Secondary Organic Aerosol Formation from Reactions of Monoterpenes with OH Radicals in the Presence of NO x
复制标题
NO x 存在下单萜与 OH 自由基反应形成二次有机气溶胶的化学
DOI：
10.1021/acs.jpca.2c04605
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Ziemann, Paul J.
中科院分区：
文献类型：
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作者：
DeVault, Marla P.;Ziola, Anna C.;Ziemann, Paul J.
挥发性有机化合物（VOC）从自然和人为来源排放到大气中，其氧化导致臭氧和二次有机气溶胶（SOA）颗粒的形成，从而影响空气质量和气候。在这里报告的研究中，我们研究了五种生物单萜与OH自由基（一种重要的日间氧化剂）在模拟污染空气中发生的化学反应条件下的反应产物，并开发了解释其形成的机制。实验在环境室中进行，并获得使用在线质谱的气相分子产物的身份信息，而液相色谱和两种方法的功能团分析，用于表征SOA的组合物。反应的气相产物与我们以前研究这些单萜与NO3自由基（一种重要的夜间氧化剂）反应形成的产物相似，因为它们都含有硝酸根、羰基、羟基、酯和醚基的各种组合。OH/NOx反应生成的SOA较少，主要由单体组成，而NO3自由基反应生成的SOA主要由颗粒相吸积反应生成的缩醛和半缩醛低聚物组成。此外，它出现了一些单体进行颗粒相水解，而低聚物没有。这些差异主要是由于单体中羟基、羰基、硝酸根和醚基的排列，这又可以通过OH和NO3自由基反应机制的差异来解释。研究结果提供了深入了解VOC结构的影响的量和组成的SOA形成的大气氧化，影响重要的气溶胶特性，如挥发性和吸湿性。
The oxidation of volatile organic compounds (VOCs), which are emitted to the atmosphere from natural and anthropogenic sources, leads to the formation of ozone and secondary organic aerosol (SOA) particles that impact air quality and climate. In the study reported here, we investigated the products of the reactions of five biogenic monoterpenes with OH radicals (an important daytime oxidant) under conditions that mimic the chemistry that occurs in polluted air, and developed mechanisms to explain their formation. Experiments were conducted in an environmental chamber, and information on the identity of gas-phase molecular products was obtained using online mass spectrometry, while liquid chromatography and two methods of functional group analysis were used to characterize the SOA composition. The gas-phase products of the reactions were similar to those formed in our previous studies of the reactions of these monoterpenes with NO3radicals (an important nighttime oxidant), in that they all contained various combinations of nitrate, carbonyl, hydroxyl, ester, and ether groups. But in spite of this, less SOA was formed in OH/NOxreactions and it was composed of monomers, while SOA formed in NO3radical reactions consisted of acetal and hemiacetal oligomers formed by particle-phase accretion reactions. In addition, it appeared that some monomers underwent particle-phase hydrolysis, whereas oligomers did not. These differences are due primarily to the arrangement of hydroxyl, carbonyl, nitrate, and ether groups in the monomers, which can in turn be explained by differences in OH and NO3radical reaction mechanisms. The results provide insight into the impact of VOC structure on the amount and composition of SOA formed by atmospheric oxidation, which influence important aerosol properties such as volatility and hygroscopicity.