Preprints
https://doi.org/10.5194/acp-2021-904
https://doi.org/10.5194/acp-2021-904

  26 Nov 2021

26 Nov 2021

Review status: this preprint is currently under review for the journal ACP.

Chemical composition and mixing state of BC-containing particles and the implications on light absorption enhancement

Jiaxing Sun1,2, Yele Sun1,2,3, Conghui Xie1,2,a, Weiqi Xu1, Chun Chen1,2, Zhe Wang1, Lei Li4, Xubing Du4,5, Fugui Huang6, Yan Li1,2, Zhijie Li1,2, Xiaole Pan1, Nan Ma7, Wanyun Xu8, Pingqing Fu9, and Zifa Wang1,2,3 Jiaxing Sun et al.
  • 1State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
  • 2College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
  • 3Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
  • 4Institute of Mass Spectrometer and Atmospheric Environment, Jinan University, Guangzhou, 510632, China
  • 5Guangdong Provincial Engineering Research Center for On-Line Source Apportionment System of Air Pollution, Guangzhou, 510632, China
  • 6Guangzhou Hexin Analytical Instrument Company Limited, Guangzhou, 510530, China
  • 7Institute for Environmental and Climate Research, Jinan University, Guangzhou 511443, China
  • 8State Key Laboratory of Severe Weather & Key Laboratory for Atmospheric Chemistry, Institute of Atmospheric Composition, Chinese Academy of Meteorological Sciences, Beijing, 100081, China
  • 9Institute of Surface-Earth System Science, Tianjin University, Tianjin 300072, China
  • anow at: State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China

Abstract. The radiative forcing of black carbon (BC) depends strongly on its mixing state in different chemical environments. Here, we analyzed the chemical composition and mixing state of BC-containing particles by using a single particle aerosol mass spectrometer and investigated their impacts on light absorption enhancement (Eabs) at an urban (Beijing) and a rural site (Gucheng) in North China Plain. While the BC was dominantly mixed with organic carbon (OC), nitrate and sulfate at both urban and rural sites, the rural site showed much higher fraction of BC coated with OC and nitrate (36 % vs. 15 – 20 %). Moreover, the BC mixing state evolved significantly as a function of relative humidity with largely increased coatings of OC-nitrate and nitrate at high RH levels. By linking with the bulk composition of organic aerosol (OA), we found that the OC coated on BC comprised dominantly secondary OA in Beijing, while primary and secondary OA were similarly important in Gucheng. Furthermore, Eabs was highly dependent on the secondary inorganic aerosol coated on BC at both sites, while the coated primary OC also resulted in an Eabs of ~1.2 for relatively fresh BC particles at the rural site. Positive matrix factorization analysis was performed to quantify the impact of different mixing state on Eabs. Our results showed the small Eabs (1.06 ~ 1.11) for BC particles from fresh primary emissions, while the Eabs increased significantly above 1.3 when BC was aged rapidly with increased coatings of OC-nitrate or nitrate, and it can reach above 1.4 as sulfate was involved in BC aging.

Jiaxing Sun et al.

Status: open (extended)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-904', Anonymous Referee #1, 20 Dec 2021 reply

Jiaxing Sun et al.

Jiaxing Sun et al.

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Short summary
We analyzed chemical composition and mixing state of BC-containing particles at urban and rural sites in winter in North China Plain and evaluated their impacts on light absorption enhancement. BC was dominantly mixed with organic carbon, nitrate and sulfate and the mixing state evolved significantly as a function of RH at both sites. The absorption enhancement depended strongly on coated secondary inorganic aerosol and was up to ~1.3–1.4 during ageing processes.
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