Preprints
https://doi.org/10.5194/egusphere-2023-1401
https://doi.org/10.5194/egusphere-2023-1401
25 Jul 2023
 | 25 Jul 2023

Measurement report: Atmospheric nitrate radical chemistry in the South China Sea influenced by the urban outflow of the Pearl River Delta

Jie Wang, Haichao Wang, Yee Jun Tham, Lili Ming, Zelong Zheng, Guizhen Fang, Cuizhi Sun, Zhenhao Ling, Jun Zhao, and Shaojia Fan

Abstract. Nitrate radical (NO3) is a critical nocturnal atmospheric oxidant in the troposphere, which widely affects the fate of air pollutants and regulates air quality. Many previous works have reported the chemistry of NO3 in inland regions of China, while less study targets marine regions. Here, we present a field measurement of the NO3 reservoir, dinitrogen pentoxide (N2O5), and related species at a typical marine site (Da Wan Shan Island) located in the South China Sea in the winter of 2021. Two patterns of air masses were captured during the campaign, including the dominant airmass from inland China (IAM) with a percentage of ~84 %, and the airmass from eastern coastal areas (CAM) with ~16 %. During the IAM period, the NO3 production rate reached 1.6 ± 0.9 ppbv h−1 due to the transportation of the polluted urban plume with high NOx and O3. While the average nocturnal N2O5 and the calculated NO3 mixing ratio were 119.5 ± 128.6 pptv and 9.9 ± 12.5 pptv, respectively, and the steady state lifetime of NO3 was 0.5 ± 0.7 min on average, indicating intensive nighttime chemistry and rapid NO3 loss at this site. By examining the reaction of NO3 with volatile organic compounds (VOCs) and N2O5 heterogeneous hydrolysis, we revealed that these two reaction pathways were not responsible for the NO3 loss (< 20 %), since the NO3 reactivity (k(NO3)) towards VOCs was 5.2 × 10−3 s−1 and the aerosol loading was low. NO was proposed to significantly contribute to nocturnal NO3 loss at this site, despite the nocturnal NO concentration was always at sub-ppbv level and near the instrument detection limit. It might be from the local soil emission. We infer that the nocturnal chemical NO3 reactions would be largely enhanced once without NO emission in the open ocean after the air mass passes through this site, thus highlighting the strong influences of the urban outflow to the downward marine areas in terms of nighttime chemistry. During the CAM period, nocturnal ozone was higher, while NOx was much lower. The NO3 production was still very fast, with a rate of 1.2 ppbv h−1. With the absence of N2O5 measurement in this period, the NO3 reactivity towards VOCs and N2O5 uptake were calculated to assess NO3 loss processes. We showed that the average k(NO3) from VOCs (56.5 %, 2.6 ± 0.9 × 10−3 s−1) was also higher than N2O5 uptake (43.5 %, 2.0 ± 1.5 × 10−3 s−1) during the CAM period, indicating a longer NO3/N2O5 lifetime compared with that during IAM period. This measurement improves the understanding of the nocturnal NO3 budget and environmental impacts with the interaction of anthropogenic and natural activities in marine regions.

Journal article(s) based on this preprint

23 Jan 2024
Measurement report: Atmospheric nitrate radical chemistry in the South China Sea influenced by the urban outflow of the Pearl River Delta
Jie Wang, Haichao Wang, Yee Jun Tham, Lili Ming, Zelong Zheng, Guizhen Fang, Cuizhi Sun, Zhenhao Ling, Jun Zhao, and Shaojia Fan
Atmos. Chem. Phys., 24, 977–992, https://doi.org/10.5194/acp-24-977-2024,https://doi.org/10.5194/acp-24-977-2024, 2024
Short summary
Jie Wang, Haichao Wang, Yee Jun Tham, Lili Ming, Zelong Zheng, Guizhen Fang, Cuizhi Sun, Zhenhao Ling, Jun Zhao, and Shaojia Fan

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1401', Anonymous Referee #1, 16 Aug 2023
  • RC2: 'Comment on egusphere-2023-1401', Anonymous Referee #2, 31 Aug 2023

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1401', Anonymous Referee #1, 16 Aug 2023
  • RC2: 'Comment on egusphere-2023-1401', Anonymous Referee #2, 31 Aug 2023

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Jie Wang on behalf of the Authors (11 Oct 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (31 Oct 2023) by Eleanor Browne
RR by Anonymous Referee #2 (18 Nov 2023)
ED: Publish as is (29 Nov 2023) by Eleanor Browne
AR by Jie Wang on behalf of the Authors (30 Nov 2023)  Manuscript 

Post-review adjustments

AA: Author's adjustment | EA: Editor approval
AA by Jie Wang on behalf of the Authors (19 Jan 2024)   Author's adjustment   Manuscript
EA: Adjustments approved (19 Jan 2024) by Eleanor Browne

Journal article(s) based on this preprint

23 Jan 2024
Measurement report: Atmospheric nitrate radical chemistry in the South China Sea influenced by the urban outflow of the Pearl River Delta
Jie Wang, Haichao Wang, Yee Jun Tham, Lili Ming, Zelong Zheng, Guizhen Fang, Cuizhi Sun, Zhenhao Ling, Jun Zhao, and Shaojia Fan
Atmos. Chem. Phys., 24, 977–992, https://doi.org/10.5194/acp-24-977-2024,https://doi.org/10.5194/acp-24-977-2024, 2024
Short summary
Jie Wang, Haichao Wang, Yee Jun Tham, Lili Ming, Zelong Zheng, Guizhen Fang, Cuizhi Sun, Zhenhao Ling, Jun Zhao, and Shaojia Fan

Data sets

Measurement report: Atmospheric nitrate radical chemistry in the South China Sea influenced by the urban outflow of the Pearl River Delta Jie Wang, Haichao Wang, Yee Jun Tham, Lili Ming, Zelong Zheng, Guizhen Fang, Cuizhi Sun, Zhenhao Ling, Jun Zhao, and Shaojia Fan https://doi.org/10.5281/zenodo.8089100

Jie Wang, Haichao Wang, Yee Jun Tham, Lili Ming, Zelong Zheng, Guizhen Fang, Cuizhi Sun, Zhenhao Ling, Jun Zhao, and Shaojia Fan

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Latest update: 26 Jan 2024
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Short summary
Many works reported NO3 chemistry in inland regions, while less targeted marine regions. We measured N2O5 and related species on a typical island and found intensive nighttime chemistry and rapid NO3 loss. NO contributed significantly to NO3 loss despite the sub-ppbv level, suggesting nocturnal NO3 reactions would be largely enhanced once without NO emission in the open ocean. This highlights the strong influences of urban outflow on downward marine areas in terms of nighttime chemistry.