Preprints
https://doi.org/10.5194/egusphere-2023-2593
https://doi.org/10.5194/egusphere-2023-2593
03 Jan 2024
 | 03 Jan 2024

Non-negligible secondary contribution to brown carbon in autumn and winter: inspiration from particulate nitrated and oxygenated aromatic compounds in urban Beijing

Yanqin Ren, Zhenhai Wu, Yuanyuan Ji, Fang Bi, Junling Li, Haijie Zhang, Hao Zhang, Hong Li, and Gehui Wang

Abstract. Nitrated aromatic compounds (NACs) and oxygenated derivatives of polycyclic aromatic hydrocarbons (OPAHs) play vital roles within brown carbon (BrC), influencing both climate dynamics and human health to a certain degree. The concentrations of these drug classes were analyzed in PM2.5 from an urban area in Beijing during the autumn and winter of 2017–2018. There were four heavy haze episodes during the campaign; two of which happened prior to heating whereas the other two after heating. During the entire course of sampling, the mean total concentrations of the nine NACs and the eight OPAHs were 1.2–263 and 2.1–234 ng m-3, respectively. The concentrations of both NACs and OPAHs were approximately 2–3 times higher in the heating period than before heating. For NACs, the relative molecular composition did not change significantly before and during heating, with 4-nitrocatechol and 4-nitrophenol demonstrating the highest abundance. For OPAHs, 1-Naphthaldehyde was the most abundant species before and during heating, while the relative proportion of Anthraquinone increased by more than twice, from 13 % before heating to 31 % during the heating. In Beijing's urban area during autumn and winter, significant sources of NACs and OPAHs have been traced back to automobile emissions and biomass-burning activities. Interestingly, it was observed that the contribution from coal combustion increased notably with the onset of heating during this period. It is worth noticing that the secondary generation of BrC was important throughout the whole sampling period, which was manifested by the photochemical reaction before heating and the aqueous reaction during heating. It was further found that the haze in autumn and winter was nitrate-driven before heating and SOC-driven when heating began, and the secondary formation of BrC increased significantly in pollution events, particularly during heating.

Yanqin Ren, Zhenhai Wu, Yuanyuan Ji, Fang Bi, Junling Li, Haijie Zhang, Hao Zhang, Hong Li, and Gehui Wang

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-2593', Anonymous Referee #1, 22 Jan 2024
  • RC2: 'Comment on egusphere-2023-2593', Anonymous Referee #3, 27 Jan 2024
  • RC3: 'Comment on egusphere-2023-2593', Anonymous Referee #2, 30 Jan 2024
Yanqin Ren, Zhenhai Wu, Yuanyuan Ji, Fang Bi, Junling Li, Haijie Zhang, Hao Zhang, Hong Li, and Gehui Wang
Yanqin Ren, Zhenhai Wu, Yuanyuan Ji, Fang Bi, Junling Li, Haijie Zhang, Hao Zhang, Hong Li, and Gehui Wang

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Short summary
Nitrated aromatic compounds (NACs) and oxygenated derivatives of polycyclic aromatic hydrocarbons (OPAHs) in PM2.5 were examined from an urban area in Beijing during the autumn and winter. The OPAHs and NACs concentrations were much higher during heating than those before heating. They majorly originated from the combustion of biomass and automobile emissions, and the secondary generation was the major contributor throughout the whole sampling period.