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Preprints
https://doi.org/10.5194/egusphere-2024-2141
https://doi.org/10.5194/egusphere-2024-2141
12 Aug 2024
 | 12 Aug 2024

Exploring HONO production from particulate nitrate photolysis in Chinese representative regions: characteristics, influencing factors and environmental implications

Bowen Li, Jian Gao, Chun Chen, Liang Wen, Yuechong Zhang, Junling Li, Yuzhe Zhang, Xiaohui Du, Kai Zhang, and Jiaqi Wang

Abstract. The production mechanism of atmospheric nitrous acid (HONO), an important precursor of hydroxyl radical (OH), was still controversial. Few studies have explored the effects of particulate nitrate photolysis on HONO sources in different environment conditions across China. Here, the photolysis rate constants of particulate nitrate for HONO production (JHONO) were determined through photochemical reaction system with PM2.5 samples collected from five representative sites in China. To eliminate the “shadowing effect” — potential light extinction within aerosol layers at heavy PM2.5 loadings on the filters, the relationship between light screening coefficient and EC, the dominant light-absorbing component in PM2.5, was established (R2=0.73). The corrected JHONO values varied with sampling period and location over a wide range, distributing from 1.6×106 s1 to 1.96×104 s1, with a mean (± 1 SD) of (1.71±2.36)×105 s1. Chemical compositions, specifically nitrate loading and organic component, affected the production of HONO through particulate nitrate photolysis: high JHONO values were generally associated with the PM2.5 samples with high OC/NO3 ratio (R2=0.86). We suggested that the parameterization equation between JHONO and OC/NO3 established in this work can be used to estimate JHONO in different aerosol chemical conditions, thus reducing the uncertainty in exploring HONO daytime sources. This study confirms that the photolysis of particulate nitrate can be a potential HONO daytime source in rural or southern urban sites, which were characterized by high proportion of organic matter in PM2.5, while the contribution of this process to HONO daytime formation was still limited.

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Journal article(s) based on this preprint

29 Nov 2024
Exploring HONO production from particulate nitrate photolysis in representative regions of China: characteristics, influencing factors, and environmental implications
Bowen Li, Jian Gao, Chun Chen, Liang Wen, Yuechong Zhang, Junling Li, Yuzhe Zhang, Xiaohui Du, Kai Zhang, and Jiaqi Wang
Atmos. Chem. Phys., 24, 13183–13198, https://doi.org/10.5194/acp-24-13183-2024,https://doi.org/10.5194/acp-24-13183-2024, 2024
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

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The photolysis rate constants of particulate nitrate for HONO production (JHONO) with PM2.5...
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