Category Ranking
98%
Total Visits
921
Avg Visit Duration
2 minutes
Citations
20
Article Abstract
Resolving the sources of HONO formation is an indispensable aspect in understanding the enhancement of atmospheric oxidation. However, the contributing sources of high HONO formation rate remain unclear during humid haze episodes. The photochemical conversion of surface nitrate (NO ), considered as the dominant contributor to the daytime HONO generation, exhibits severe constraint under high relative humidity (RH) conditions. Unexpectedly, ammonium (NH ) on the surface of photoactive mineral dust shows a gradual acceleration of HONO generation with increasing RH under simulated solar irradiation, especially at high RH. This reversed observation stems from a change in the photochemical pathway for the HONO formation from NO and NH . The photochemical conversion of surface NO is determined by photogenerated electrons (NO →NO→NO →HONO), while the superoxide radical (∙O ) generated during photochemical reaction drives the surface NH to directly form HONO with the pathway (NH ∙+∙O →NO + HO→HONO). Under high RH conditions, oxygen molecules (O) have greatly better access to photogenerated electrons than NO, resulting in an interruption of the procedure from NO to NO during NO conversion. Therefore, the favorably generated ∙O fuels the photochemical conversion of surface NH while inhibiting the conversion of NO to diurnal HONO formation. This work highlights the overlooked contribution of HONO formation from NH , especially under high RH conditions, and advances the understanding of a renewed role for O in atmospheric chemical processes.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC12340223 | PMC |
| http://dx.doi.org/10.34133/research.0819 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Aerosol iodide accelerates reactive nitrogen cycling in the marine atmosphere.
Nat Commun
September 2025
Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, China.
Reactive nitrogen plays critical roles in atmospheric chemistry, climate, and geochemical cycles, yet its sources in the marine atmosphere, particularly the cause of the puzzling daytime peaks of nitrous acid (HONO), remain unexplained. Here we reveal that iodide enhances HONO production during aqueous nitrate photolysis by over tenfold under typical marine conditions. Laboratory experiments and molecular simulations confirm that HONO formation from nitrate photolysis is a surface-dependent process, and the extreme surface propensity of iodide facilitates nitrate enrichment at interfaces, reducing the solvent cage effect and promoting HONO release.
View Article and Find Full Text PDFPhotochemical reaction of 4-chlorobiphenyl with nitrous acid in atmospheric aqueous solution.
RSC Adv
August 2025
School of Resource and Environmental Engineering, Hefei University of Technology Hefei 230009 P.R. China +86 551 62901649 +86 551 62901523.
The photochemical reaction of 4-chlorobiphenyl (4-PCB) and HONO in atmospheric aqueous phase was studied by 355 nm laser flash photolysis combined with 365 nm UV steady-state irradiation technique. The steady-state study showed that the conversion rate of 4-PCB was affected by the initial concentration of 4-PCB, pH value and HONO concentration, while chloride ions had little effect on the conversion of 4-PCB. HONO produces an HO˙ attack on 4-PCB to form a 4-PCB-OH adduct with the second-order reaction rate constant of (9.
View Article and Find Full Text PDFInconsistent capacity of potential HONO sources to enhance secondary pollutants: Evidence from WRF-Chem modeling.
J Environ Sci (China)
December 2025
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences, Beijing 100029, China; College of Earth and Planetary Sciences, University of the Chinese Academy of Sciences, Beijing 100049, China. Elec
Nitrous acid (HONO) is a crucial source of OH radicals in the troposphere, significantly enhancing secondary pollutants like secondary organic aerosols (SOA) and peroxyacetyl nitrates (PAN). While prior research has examined HONO sources and their total impacts on secondary pollution, the specific enhancement capacity of each individual HONO source remains underexplored. This study uses observational data from 2015 to 2018 for HONO, SOA, and PAN across six sites in China, combined with WRF-Chem model adding six potential HONO sources to evaluate their capacity: traffic emissions (E_traffic), soil emissions (E_soil), indoor-outdoor exchange (E_indoor), nitrate photolysis (P_nit), and NO heterogeneous reactions on aerosol and ground surfaces (Het_a, Het_g).
View Article and Find Full Text PDFImpact of biomass burning on HONO chemistry and atmospheric oxidation capacity in the Yangtze River delta, China.
Environ Pollut
August 2025
Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230031, China; University of Science and Technology of China, Hefei, 230026, China; Institute of Environment, Hefei Comprehen
Extensive research confirms that biomass burning (BB) significantly contributes to particulate matter and gaseous pollutant emissions. Open burning of wheat straw is particularly common during the harvest season, directly affecting air quality and atmospheric oxidation capacity. In this study, nitrous acid (HONO) and associated atmospheric species were investigated during the BB season at a suburban station, as part of the 2018 EXPLORE-YRD campaign.
View Article and Find Full Text PDFSignificant but Overlooked: Atmospheric HONO Formation from Surface Ammonium Oxidation with Superoxide Radicals.
Research (Wash D C)
August 2025
Research Center for Carbon-Neutral Environmental & Energy Technology, Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 611731, China.
Resolving the sources of HONO formation is an indispensable aspect in understanding the enhancement of atmospheric oxidation. However, the contributing sources of high HONO formation rate remain unclear during humid haze episodes. The photochemical conversion of surface nitrate (NO ), considered as the dominant contributor to the daytime HONO generation, exhibits severe constraint under high relative humidity (RH) conditions.
View Article and Find Full Text PDF