Wang Guoying, Ma Shangrong, Niu Xiuli, Chen Xuefu, Liu Fengshuo, Li Xin, Li Lan, Shi Gaofeng, Wu Zhijun
School of Petrochemical Engineering, Lanzhou University of Technology, Lanzhou 730050, China.
Gansu Food Inspection and Research Institute, Lanzhou 730050, China.
J Phys Chem A. 2021 Apr 1;125(12):2666-2672. doi: 10.1021/acs.jpca.1c00539. Epub 2021 Mar 23.
In the troposphere, the knowledge about nitrous acid (HONO) sources is incomplete. The missing source of sulfate and fine particles cannot be explained during haze events. Air quality models cannot predict high levels of secondary fine-particle pollution. Despite extensive studies, one challenging issue in atmospheric chemistry is identifying the source of HONO. Here, we present direct ab initio molecular dynamics simulation evidence and typical air pollution events of the formation of gaseous HONO, nitrogen dioxide/hydrogen sulfite (HOS(O)2-NO or NO-HSO) from nitrogen dioxide (NO), sulfur dioxide (SO), water (HO), and ammonia (NH) molecules in a proportion of 2:1:3:3. The reactions show a new mechanism for the formation of HONO and NO-HSO in the troposphere, especially when the concentration of NO, SO, HO, and NH is high (e.g., 2:1:3:3 or higher) in the air. Contrary to the proportion NO, SO, HO, and NH equaling to 1:1:3:1 and 1:1:3:2, the proportion (2:1:3:3) enables barrierless reactions and weak interactions between molecules via the formation of HONO, NO-HSO, and NH/HO. In addition, field observations are carried out, and the measured data are summarized. Correlation analysis supported the conversion of NO to HONO during observational studies. The weak interactions promote proton transfer, resulting in the generation of HONO, NO-HSO, and NH/HO pairs.
在对流层中，关于亚硝酸（HONO）来源的认识并不完整。在雾霾事件期间，硫酸盐和细颗粒物缺失的来源无法得到解释。空气质量模型无法预测高浓度的二次细颗粒物污染。尽管进行了广泛研究，但大气化学中的一个具有挑战性的问题是确定HONO的来源。在此，我们展示了直接从头算分子动力学模拟证据以及典型空气污染事件中，由二氧化氮（NO）、二氧化硫（SO）、水（HO）和氨（NH）分子以2:1:3:3的比例形成气态HONO、二氧化氮/亚硫酸氢盐（HOS(O)2-NO或NO-HSO）的过程。这些反应展示了对流层中HONO和NO-HSO形成的新机制，特别是当空气中NO、SO、HO和NH的浓度较高（例如2:1:3:3或更高）时。与NO、SO、HO和NH的比例为1:1:3:1和1:1:3:2的情况相反，该比例（2:1:3:3）通过形成HONO、NO-HSO和NH/HO实现了无障碍反应和分子间的弱相互作用。此外，还进行了实地观测并总结了测量数据。相关性分析支持了观测研究期间NO向HONO的转化。弱相互作用促进了质子转移，导致生成HONO、NO-HSO和NH/HO对。
