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, PR China.
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, PR China.
Sci Total Environ. 2020 Sep 15;735:139317. doi: 10.1016/j.scitotenv.2020.139317. Epub 2020 May 11.
Nitrous Acid (HONO) is an important precursor of hydroxyl radical (OH) and has significant impacts on the formation of Ozone (O) and Secondary Organic Aerosol (SOA). The atmospheric concentrations of HONO were measured during early autumn in downtown, Beijing (China). This study investigated HONO pollution characteristics and potential sources during day and night. The maximum hourly HONO levels reached 5.16 ppb, with 1.23 ppb on average. HONO concentration exhibited typical diurnal variation characteristics, with maximum at nighttime and minimum at daytime. The potential sources mainly included vehicle emission, heterogeneous reaction of NO on aerosol surfaces (Photo-enhanced at the daytime) and photolysis of particulate nitrate (NO) in Beijing. Vehicle emission was an important HONO source, particular at the morning rush period and lower HONO concentration. The simulated results highlighted that the main contribution of HONO was NO heterogeneous reaction on aerosol surfaces. The photolysis of particulate NO was also an important daytime HONO source, particularly in the pollution period. The main loss routine was the photolysis of HONO and dry deposition at day and night, respectively.
亚硝酸（HONO）是羟基自由基（OH）的重要前体，对臭氧（O）和二次有机气溶胶（SOA）的形成有重大影响。本研究在北京市区初秋进行大气亚硝酸浓度的测量，研究其在白天和黑夜的污染特征和潜在来源。亚硝酸的最大小时浓度达到 5.16 ppb，平均值为 1.23 ppb。亚硝酸浓度呈现出典型的日变化特征，夜间最高，白天最低。潜在来源主要包括汽车排放、气溶胶表面上的 NO 异相反应（白天光增强）和颗粒态硝酸盐（NO）的光解。汽车排放是亚硝酸的重要来源，特别是在早高峰期间和较低的亚硝酸浓度下。模拟结果强调，亚硝酸的主要来源是气溶胶表面上的 NO 异相反应。颗粒态 NO 的光解也是重要的白天亚硝酸源，特别是在污染期间。亚硝酸的主要损失途径分别是白天和黑夜的光解和干沉降。
