Preprints
https://doi.org/10.5194/egusphere-2024-2098
https://doi.org/10.5194/egusphere-2024-2098
19 Aug 2024
 | 19 Aug 2024

Significant role of biomass burning in heavy haze formation in a megacity: Molecular-level insights from intensive PM2.5 sampling on winter hazy days

Mingjie Kang, Mengying Bao, Wenhuai Song, Aduburexiati Abulimiti, Fang Cao, Sönke Szidat, and Yanlin Zhang

Abstract. Reports on molecular-level characterization of primary and secondary constituents in PM2.5 at high-time resolution are limited to date, especially during haze events. The study explored molecular composition and source contributions of PM2.5 with comprehensive analytical methods by conducting intensive sampling at roughly 2-hour intervals during hazy days in winter. Results show that organic matters were the predominant species, followed by NO3-. Biomass burning (BB) was the biggest contributor to organic carbon (OC), both in concentration and in proportion. Radiocarbon analysis of carbonaceous fractions reflects that fossil fuels dominate water-soluble organic carbon (WSOC) (61–82 %) likely resulting from increased coal combustion for residential cooking and heating and the coal-fired industry in cold times. Interestingly, the contribution of non-fossils instead of fossil fuels to WSOC enhanced with aggravating haze pollution, coinciding with significantly intensified BB during that time. Other non-fossil sources, including fungal spores and plant debris, showed a larger contribution to OC in light haze episodes. For secondary sources, naphthalene-derived secondary organic carbon (SOC) contributed more to OC in PM2.5 (0.27–2.46 %) compared to biogenic emissions (0.05–1.10 %), suggesting fossil fuels may dominate SOC formation during urban haze events. SOC declined with rising haze pollution and presented high levels on days with high temperature and low relative humidity due to elevated photooxidation. Additionally, BB can raise secondary formation as well as the emissions of other sources, as demonstrated by the significant relationships between BB tracers and many other source tracers. These findings illustrate that BB likely plays a significant role in the heavy winter haze.

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Mingjie Kang, Mengying Bao, Wenhuai Song, Aduburexiati Abulimiti, Fang Cao, Sönke Szidat, and Yanlin Zhang

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-2098', Anonymous Referee #1, 27 Aug 2024
  • RC2: 'Comment on egusphere-2024-2098', Anonymous Referee #2, 29 Aug 2024
  • RC3: 'Comment on egusphere-2024-2098', Anonymous Referee #3, 29 Aug 2024
  • RC4: 'Comment on egusphere-2024-2098', Anonymous Referee #4, 01 Sep 2024
  • RC5: 'Comment on egusphere-2024-2098', Anonymous Referee #5, 02 Sep 2024
  • CC1: 'Comment on egusphere-2024-2098', Yingjun Chen, 05 Sep 2024
  • RC6: 'Comment on egusphere-2024-2098', Anonymous Referee #6, 05 Sep 2024

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-2098', Anonymous Referee #1, 27 Aug 2024
  • RC2: 'Comment on egusphere-2024-2098', Anonymous Referee #2, 29 Aug 2024
  • RC3: 'Comment on egusphere-2024-2098', Anonymous Referee #3, 29 Aug 2024
  • RC4: 'Comment on egusphere-2024-2098', Anonymous Referee #4, 01 Sep 2024
  • RC5: 'Comment on egusphere-2024-2098', Anonymous Referee #5, 02 Sep 2024
  • CC1: 'Comment on egusphere-2024-2098', Yingjun Chen, 05 Sep 2024
  • RC6: 'Comment on egusphere-2024-2098', Anonymous Referee #6, 05 Sep 2024
Mingjie Kang, Mengying Bao, Wenhuai Song, Aduburexiati Abulimiti, Fang Cao, Sönke Szidat, and Yanlin Zhang
Mingjie Kang, Mengying Bao, Wenhuai Song, Aduburexiati Abulimiti, Fang Cao, Sönke Szidat, and Yanlin Zhang

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Short summary
Reports on the molecular level knowledge of high temporal resolution PM2.5 components on hazy days are still limited. This study investigated many individual PM2.5 species and sources. The results show biomass burning (BB) was the main source of organic carbon. Moreover, BB enhanced fungal spore emissions and secondary aerosol formation. The contribution of non-fossils increased with increasing haze pollution. These findings suggest BB may be an important driver of haze events in winter.