Zhang Wenqian, Tong Shengrui, Jia Chenhui, Ge Maofa, Ji Dongsheng, Zhang Chenglong, Liu Pengfei, Zhao Xiaoxi, Mu Yujing, Hu Bo, Wang Lili, Tang Guiqian, Li Xin, Li Weiran, Wang Zhen
State Key Laboratory for Structural Chemistry of Unstable and Stable Species, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, People's Republic of China.
Environ Sci Technol. 2022 Apr 19;56(8):4828-4837. doi: 10.1021/acs.est.1c07784. Epub 2022 Mar 17.
Atmospheric nitrous acid (HONO) is a dominant precursor of hydroxyl (OH) radicals, and its formation mechanisms are still controversial. Few studies have simultaneously explored effects of different combustion processes on HONO sources. Hereby, synchronous HONO measurement in urban (BJ), suburban (XH) and rural (DBT) areas with different combustion processes is performed in the North China Plain in winter. A box model is utilized to analyze HONO formation mechanisms. HONO concentration is the highest at the DBT site (2.51 ± 1.90 ppb), followed by the XH (2.18 ± 1.95 ppb) and BJ (1.17 ± 1.20 ppb) sites. Vehicle exhaust and coal combustion significantly contribute to nocturnal HONO at urban and rural sites, respectively. During a stagnant pollution period, the NO+OH reaction and combustion emissions are more crucial to HONO in urban and rural areas; meanwhile, the heterogeneous reaction of NO is more significant in suburban areas. Moreover, the production rate of OH from HONO photolysis is about 2 orders of magnitude higher than that from ozone photolysis. Consequently, vehicle exhaust and coal combustion can effectively emit HONO, further causing environmental pollution and health risks. It is necessary to expand the implementation of the clean energy transition policy in China, especially in areas with substantial coal combustion.
大气中的亚硝酸（HONO）是羟基（OH）自由基的主要前体，其形成机制仍存在争议。很少有研究同时探讨不同燃烧过程对HONO来源的影响。在此，冬季在中国华北平原对具有不同燃烧过程的城市（北京）、郊区（香河）和农村（大厂）地区进行了同步HONO测量。利用箱式模型分析HONO的形成机制。大厂站点的HONO浓度最高（2.51±1.90 ppb），其次是香河（2.18±1.95 ppb）和北京（1.17±1.20 ppb）站点。车辆尾气排放和煤炭燃烧分别对城市和农村夜间的HONO有显著贡献。在污染停滞期，NO+OH反应和燃烧排放对城市和农村地区的HONO更为关键；同时，NO的非均相反应在郊区更为显著。此外，HONO光解产生OH的速率比臭氧光解产生OH的速率高约2个数量级。因此，车辆尾气排放和煤炭燃烧会有效排放HONO，进一步造成环境污染和健康风险。有必要在中国扩大清洁能源转型政策的实施，特别是在煤炭燃烧量大的地区。
