The Levels and Sources of Nitrous Acid (HONO) in Winter of Beijing and Sanmenxia

Abstract

HONO concentrations in Beijing (BJ) and Sanmenxia (SMX) were simultaneously measured in winter with a duration of 1 month, and the sources and sinks of HONO in the two cities were comparably analyzed. BJ and SMX had different pollution characteristics. Direct vehicle emission made a contribution to observed HONO of about 28% in BJ, whereas it contributed to HONO only about 12% in SMX. Additionally, direct emission from coal combustion in SMX also made a significant contribution to atmospheric HONO, which could achieve to be 13%. In BJ, nighttime NO2 conversion on the aerosol and ground surfaces contributed to HONO sources of 15% and 27%, respectively. In SMX, nighttime NO2 conversion on the aerosol and ground surfaces contributed to HONO sources of 40% and 30%, respectively. Daytime NO2 heterogeneous conversion (including photo‐enhanced conversion) on the aerosol and ground surfaces was important in SMX. Daytime NO3− photolysis contributed 9% HONO in SMX and 4% in BJ. The primary OH production rates from photolysis of daytime HONO in both BJ and SMX were three orders of magnitude faster than those from photolysis of O3, revealing the dominant role of HONO in local atmospheric chemistry of the two cities in winter.

Elucidating HONO formation mechanism and its essential contribution to OH during haze events

“…The overview of daytime (8:00-16:00), nighttime (18:00-06:00), and daily mean concentrations of HONO, NO2, NO, and PM2.5 during four episodes investigated here and the previously reported data during winter haze events are summarized in table S4. During the four pollution episodes, the average values of HONO, NO, NO2, and PM2.5 were 2.52 ± 1.61 ppb, 35.14 ± 30.27 ppb, 32.23 ± 7.43 ppb, 100 ± 69 μg/m 3 , respectively, which were at an intermediate level compared with previous studies in China [46][47][48] and other countries such as India 8,9 . The ratio of HONO to NOX (i.e., the conversion frequency from NOX to HONO), was around 0.03 among previously reported winter haze events in China before 2018 15,[43][44][45]49 .…”

Impact of Nitrate and Iron Ions on Uptake Coefficients and Condensed Phase Products From the Reaction of Gaseous NO2 With HULIS Proxies

“…The heterogeneous reaction of NO 2 with phenolic compounds (ArOH) can lead to the formation of the corresponding phenoxy type radical or nitrite anions shown as Reaction (Ammann et al., 2005): $$${\text{NO}}_{2}+\text{ArOH}\to \text{HONO}+\text{ArO}$$$ In the acidic aqueous environment, the nitrite anions may be protonated and released to the gas phase as HONO, or undergo secondary chemistry, eventually yielding NO or nitrated organics (Baker et al., 1999; Kleffmann et al., 1998). Laboratory measurements and field studies suggest that HONO in the troposphere is mainly formed through heterogeneous reactions of NO 2 with ground surface (Stemmler et al., 2006; Zhang et al., 2022), urban grime (Liu et al., 2019, 2020, 2022), soil (Donaldson et al., 2014), aerosol particles (Dyson et al., 2021; Stemmler et al., 2007) and cloud droplets (L. Li et al., 2018).…”

“…In the acidic aqueous environment, the nitrite anions may be protonated and released to the gas phase as HONO, or undergo secondary chemistry, eventually yielding NO or nitrated organics (Baker et al, 1999;Kleffmann et al, 1998). Laboratory measurements and field studies suggest that HONO in the troposphere is mainly formed through heterogeneous reactions of NO 2 with ground surface (Stemmler et al, 2006;Zhang et al, 2022), urban grime (Liu et al, 2019(Liu et al, , 2020(Liu et al, , 2022, soil (Donaldson et al, 2014), aerosol particles (Dyson et al, 2021;Stemmler et al, 2007) and cloud droplets (L. Li et al, 2018).…”

Direct Observation of HONO Emissions from Real-World Residential Natural Gas Heating in China

“…42 HONO can be emitted directly in the indoor settings by combustion processes such as burning candles 43 and open fire places. 44 Residential coal combustion is an important source of nocturnal HONO at both suburban and rural sites in China, 34,45 but its contribution will gradually decrease with the acceleration of coal-to-gas projects. 46 Both vehicle emission and solid fuel combustion can contribute to the HONO budget to some extent, but their contributions to the HONO budget vary across emission hotspots, so the HONO budget should take into account the actual source strength at the study site.…”