Source profiles of molecular structure and light absorption of PM2.5 brown carbon from residential coal combustion emission in Northwestern China

Qian Zhang; Ziyi Li; Zhenxing Shen; Tian Zhang; Yujie Zhang; Jian Sun; Yaling Zeng; Hongmei Xu; Qiyuan Wang; Steven Sai Hang Ho; Junji Cao

doi:10.1016/j.envpol.2022.118866

Source profiles of molecular structure and light absorption of PM_2.5 brown carbon from residential coal combustion emission in Northwestern China

Environ Pollut. 2022 Apr 15:299:118866. doi: 10.1016/j.envpol.2022.118866. Epub 2022 Jan 22.

Authors

Qian Zhang¹, Ziyi Li², Zhenxing Shen³, Tian Zhang⁴, Yujie Zhang², Jian Sun⁴, Yaling Zeng⁵, Hongmei Xu⁴, Qiyuan Wang⁶, Steven Sai Hang Ho⁷, Junji Cao⁶

Affiliations

¹ Key Laboratory of Northwest Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, China; Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an, 710049, China.
² Key Laboratory of Northwest Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, China.
³ Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an, 710049, China; International Joint Research Center for Persistent Toxic Substances (IJRC-PTS), School of Water Conservancy and Civil Engineering, Northeast Agricultural University, Harbin, China. Electronic address: zxshen@mail.xjtu.edu.cn.
⁴ Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an, 710049, China.
⁵ School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China.
⁶ Key Lab of Aerosol Chemistry & Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China.
⁷ Division of Atmospheric Sciences, Desert Research Institute, Reno, NV89512, United States.

PMID: 35077839
DOI: 10.1016/j.envpol.2022.118866

Abstract

Residential coal combustion is a prominent source of brown carbon (BrC) aerosols, but knowledge of their molecular structures and optical absorption were limited, which have notable used in ambient BrC source identification and radiative forcing calculation. In this study, the Fourier transform-ion cyclotron resonance mass spectrometry combined with partial least squares regression analysis as well as Fourier transform infrared spectroscopy analysis were used to insight the molecular compounds and structures of BrC from anthracite and bituminous coal combustions between traditional and improved stoves. The absorption Ångström exponents (AAE) and mass absorption efficiency (MAE) values for the BrC emitted from the combinations of bituminous were both 1.2-2.5 times lower than those of anthracite, interpreting that the BrC from the anthracite emissions had greater light-absorbing capacity. In contrast, the emission factor of light absorption (EF_Abs) at 365 nm for the bituminous coal combusted in the traditional stove was the highest among all the tested scenarios, which revealed that the incomplete combustion of bituminous coal could emit more BrC. It was noted that primary BrC emitted from the coal combustion with traditional stoves contains higher aromaticity groups of C-C and C＝O and higher S containing organics, whereas more aliphatic groups were found in BrC using the improved stoves. N-containing (CHON and CHONS) compounds were dominated in the total molecular formula of BrC, whereas the sum of CHON and CHO groups had high double-bond equivalent (DBE) values contributed 53.5%-87.1% to the total BrC absorption. Moreover, for CHOS, the lowest of estimated molecular absorption, DBE, and DBE/C should attribute to the non-chromophoric or weak absorptive S-containing compounds. This study supplied an effective evaluation method to compare BrC emissions and their absorption for coal combustion on regional scale.

Keywords: Molecular compositions; Optical properties; Residential coal combustion; brown carbon.

MeSH terms

Aerosols / analysis
Air Pollutants* / analysis
Carbon / analysis
China
Coal* / analysis
Environmental Monitoring
Molecular Structure
Particulate Matter / analysis

Substances

Aerosols
Air Pollutants
Coal
Particulate Matter
Carbon