Li Pan, Gemayel Rachel, Li Xue, Liu Jiangping, Tang Mingjin, Wang Xinming, Yang Yan, Al-Abadleh Hind A, Gligorovski Sasho
State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.
Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou, 510640, China.
Commun Chem. 2023 Sep 16;6(1):198. doi: 10.1038/s42004-023-01003-3.
Heterogeneous reaction of gas phase NO with atmospheric humic-like substances (HULIS) is potentially an important source of volatile organic compounds (VOCs) including nitrogen (N)-containing compounds, a class of brown carbon of emerging importance. However, the role of ubiquitous water-soluble aerosol components in this multiphase chemistry, namely nitrate and iron ions, remains largely unexplored. Here, we used secondary electrospray ionization ultrahigh-resolution mass spectrometry for real-time measurements of VOCs formed during the heterogeneous reaction of gas phase NO with a solution containing gallic acid (GA) as a proxy of HULIS at pH 5 relevant for moderately acidic aerosol particles. Results showed that the number of detected N-containing organic compounds largely increased from 4 during the NO reaction with GA in the absence of nitrate and iron ions to 55 in the presence of nitrate and iron ions. The N-containing compounds have reduced nitrogen functional groups, namely amines, imines and imides. These results suggest that the number of N-containing compounds is significantly higher in deliquescent aerosol particles due to the influence of relatively higher ionic strength from nitrate ions and complexation/redox reactivity of iron cations compared to that in the dilute aqueous phase representative of cloud, fog, and rain water.
气相一氧化氮（NO）与大气中类腐殖质（HULIS）的非均相反应可能是挥发性有机化合物（VOCs）的一个重要来源，这些挥发性有机化合物包括含氮化合物，这是一类新出现且日益重要的棕碳。然而，普遍存在的水溶性气溶胶成分（即硝酸盐和铁离子）在这种多相化学反应中的作用在很大程度上仍未得到探索。在此，我们使用二次电喷雾电离超高分辨率质谱对气相NO与含有没食子酸（GA）的溶液在pH 5条件下发生非均相反应过程中形成的VOCs进行实时测量，该溶液作为pH 5时中等酸性气溶胶颗粒的HULIS替代物。结果表明，检测到的含氮有机化合物数量大幅增加，从在没有硝酸盐和铁离子时NO与GA反应过程中的4种增加到存在硝酸盐和铁离子时的55种。这些含氮化合物具有还原型氮官能团，即胺、亚胺和酰亚胺。这些结果表明，与代表云、雾和雨水的稀水相相比，由于硝酸盐离子相对较高的离子强度以及铁阳离子的络合/氧化还原反应性的影响，潮解性气溶胶颗粒中含氮化合物的数量明显更高。
