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- Title
Impact of Nitrate and Iron Ions on Uptake Coefficients and Condensed Phase Products From the Reaction of Gaseous NO<sub>2</sub> With HULIS Proxies.
- Authors
Li, Pan; Mekic, Majda; Wang, Yiqun; He, Bowen; Deng, Huifan; Xu, Jinli; Pang, Hongwei; Jiang, Bin; Tang, Mingjin; Wang, Xinming; Al‐Abadleh, Hind A.; Gligorovski, Sasho
- Abstract
Humic‐like substances (HULIS) are a ubiquitous reactive component of atmospheric aerosol. They participate in the formation of secondary organic aerosols via chemical reactions with atmospheric oxidants. Here, we assess the influence of transition metal ions (namely ferric iron, Fe(III)), and nitrate ions (NO3− ${{\text{NO}}_{3}}^{-}$) on the heterogeneous reaction of gaseous NO2 with an aqueous film containing gallic acid (GA) or tannic acid (TA) as proxies for HULIS. Using a vertical wetted wall flow tube technique, the uptake coefficients of gaseous NO2 on GA and TA increased nonlinearly with increasing [Fe(III)], in dark and under light irradiation. However, the combined effect of both ions, Fe(III) and NO3− ${{\text{NO}}_{3}}^{-}$, led to a substantial decrease in NO2 uptake in the dark and under simulated near‐UV sunlight irradiation (300 < λ < 400 nm). The lifetime of GA in dilute aqueous phase, which corresponds to cloud water, due to reaction with NO2 would be 6 hr during both nighttime and daytime. However, the lifetime of GA in aerosol particles which contain both ions, that is, Fe(III) and NO3− ${{\text{NO}}_{3}}^{-}$, would increase to 27 hr during nighttime and 11 days and 6 hr due to light‐induced reaction with NO2. Also, we observed, using Fourier transform ion cyclotron resonance mass spectrometry, the formation of nitrocatechols compounds (e.g., methyl‐nitrocatechol), which contribute to brown carbon. Compounds with reduced functional groups such as amines were also observed in the presence of iron and nitrate ions in the dark and under irradiation, indicating that Fe(III) and NO3− ${{\text{NO}}_{3}}^{-}$, can influence the kinetics and product distribution in deliquescent aerosol particles. Plain Language Summary: Biomass burning is one of the main sources of humic‐like substances (HULIS) in the aerosol particles covering a large fraction of the water‐soluble organic carbon. Here we assessed the impact of nitrate and iron ions on the uptake coefficients of NO2 on gallic acid (GA) and tannic acid (TA) as HULIS proxies. The uptake coefficients and consequently the atmospheric lifetimes were dramatically impacted by the presence of nitrate and iron ions. The analysis of the formed product compounds in the condensed phase by Fourier transform ion cyclotron resonance mass spectrometry indicates that the presence of nitrate and iron ions largely impact the observed nitrogen‐containing organic compounds formed during the reaction of NO2 with GA. Majority of the formed compounds contain reduced nitrogen‐functional groups such as amines, amides, and imines. We identified the formation of nitroaromatics with at least one nitro functional group attached directly to a benzene ring, like 5‐Nitroguaiacol, 4‐methyl‐5‐nitrocatechol. These compounds, can cause positive radiative forcing of aerosols due to their light‐absorbing properties. Key Points: Uptake coefficients of gas phase NO2 on humic‐like substances proxies in aerosol particles are largely impacted by nitrate and iron ionsFormation of nitrogen containing product compounds in aerosols are impacted by nitrate and iron ions compared to that in cloud waterFormation of nitrocatechols like methyl‐nitrocatechol, which contribute to brown carbon is observed upon influence of nitrate and iron ions
- Subjects
FERRIC nitrate; IRON ions; CARBONACEOUS aerosols; ION cyclotron resonance spectrometry; CONDENSED matter; IRRADIATION; NITROGEN compounds; TRANSITION metal ions; ATMOSPHERIC nucleation
- Publication
Journal of Geophysical Research. Atmospheres, 2024, Vol 129, Issue 3, p1
- ISSN
2169-897X
- Publication type
Article
- DOI
10.1029/2023JD039698