Preprints
https://doi.org/10.5194/egusphere-2023-895
https://doi.org/10.5194/egusphere-2023-895
20 Jun 2023
 | 20 Jun 2023

Measurement Report: Optical Characterization, Seasonality, and Sources of Brown Carbon in Fine Aerosols from Tianjin, North China: Year-round Observations

Zhichao Dong, Chandra Mouli Pavuluri, Peisen Li, Zhanjie Xu, Junjun Deng, Xueyan Zhao, Xiaomai Zhao, Pingqing Fu, and Cong-Qiang Liu

Abstract. To investigate the physicochemical characteristics and sources of brown carbon (BrC) in North China, we collected fine aerosols (PM2.5) at an urban site in Tianjin over a 1-year period. We measured the ultraviolet (UV) light absorption and excitation emission matrix (EEM) fluorescence of the water-soluble BrC (WSBrC) and the water-insoluble but methanol-soluble BrC (WI-MSBrC) in the PM2.5 using a three-dimensional fluorescence spectrometer. Average light absorption efficiency of both WSBrC (Abs365, WSBrC) and WI-MSBrC (Abs365, WI-MSBrC) at 365 nm was found to be highest in winter and distinct from season to season. The biological index (BIX) and fluorescence index (FI) of WSBrC showed an opposite seasonal pattern to that of the humification index (HIX) with lower values in summer, implying that the secondary formation and further chemical processing of aerosols were intensive in summer than in other seasons. Whereas in winter, the higher HIX together with the higher BIX and FI of WI-MSBrC suggested that the BrC loading was mainly influenced by primary emissions and was relatively water-soluble. Based on EEM, the types of chromophores in BrC were divided into humic-like substances (HULIS), including low-oxygenated and high-oxygenated species, and protein like compounds (PLOM). The direct radiation absorption caused by WSBrC and WI-MSBrC combinedly in the range of 300–400 nm was accounted for about 40 % to the total radiation (range, 300–700 nm), which emphasizes that the radiation balance of the Earth's climate system is substantially affects by the BrC and should be considered in the radiative forcing models.

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Zhichao Dong, Chandra Mouli Pavuluri, Peisen Li, Zhanjie Xu, Junjun Deng, Xueyan Zhao, Xiaomai Zhao, Pingqing Fu, and Cong-Qiang Liu

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-895', Luis Miguel Feijo Barreira, 11 Jul 2023
  • RC2: 'Comment on egusphere-2023-895', Anonymous Referee #2, 24 Sep 2023

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-895', Luis Miguel Feijo Barreira, 11 Jul 2023
  • RC2: 'Comment on egusphere-2023-895', Anonymous Referee #2, 24 Sep 2023
Zhichao Dong, Chandra Mouli Pavuluri, Peisen Li, Zhanjie Xu, Junjun Deng, Xueyan Zhao, Xiaomai Zhao, Pingqing Fu, and Cong-Qiang Liu

Data sets

Year-round observations of the optical properties of brown carbon in fine aerosols at Tianjin, North China - Data set Zhichao Dong, Chandra Mouli Pavuluri, Peisen Li, Zhanjie Xu, Junjun Deng, Xueyan Zhao, Xiaomai Zhao, Pingqing Fu, and Cong-Qiang Liu https://doi.org/10.5281/zenodo.7316371

Year-round observations of bulk components and 13C and 15N isotope ratios of fine aerosols at Tianjin, North China – Data set Zhichao Dong, Chandra Mouli Pavuluri, Zhanjie Xu, Yu Wang, Peisen Li, Pingqing Fu, and Cong-Qiang Liu https://doi.org/10.5281/zenodo.5140861

Zhichao Dong, Chandra Mouli Pavuluri, Peisen Li, Zhanjie Xu, Junjun Deng, Xueyan Zhao, Xiaomai Zhao, Pingqing Fu, and Cong-Qiang Liu

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Short summary
A comprehensive study of optical properties of brown carbon (BrC) in fine aerosols from Tianjin, China implied that biological emissions are major sources of BrC in summer whereas, fossil fuel combustion and biomass burning emissions in cold period. The direct radiation absorption caused by BrC in the short wavelength contributed about 40 % to that caused by BrC in the 300–700nm. Water-insoluble but methanol soluble BrC contain more protein-like chromophores (PLOM) than that of water-soluble BrC.