Concentration, optical characteristics, and emission factors of brown carbon emitted by on-road vehicles

Ru-Jin Huang; Wei Yuan; Lu Yang; Huinan Yang; Wenjuan Cao; Jie Guo; Ningning Zhang; Chongshu Zhu; Yunfei Wu; Renjian Zhang

doi:10.1016/j.scitotenv.2021.151307

Concentration, optical characteristics, and emission factors of brown carbon emitted by on-road vehicles

Sci Total Environ. 2022 Mar 1:810:151307. doi: 10.1016/j.scitotenv.2021.151307. Epub 2021 Nov 5.

Authors

Ru-Jin Huang¹, Wei Yuan², Lu Yang², Huinan Yang³, Wenjuan Cao⁴, Jie Guo⁴, Ningning Zhang⁴, Chongshu Zhu⁴, Yunfei Wu⁵, Renjian Zhang⁵

Affiliations

¹ CAS Center for Excellence in Quaternary Science and Global Change, SKLLQG, and KLACP, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; Open Studio for Oceanic-Continental Climate and Environment Changes, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266061, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: rujin.huang@ieecas.cn.
² CAS Center for Excellence in Quaternary Science and Global Change, SKLLQG, and KLACP, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; University of Chinese Academy of Sciences, Beijing 100049, China.
³ School of Energy and Power Engineering, University of Shanghai for Science and Technology, 200093 Shanghai, China.
⁴ CAS Center for Excellence in Quaternary Science and Global Change, SKLLQG, and KLACP, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China.
⁵ Key Laboratory of Middle Atmosphere and Global Environment Observation, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.

PMID: 34748827
DOI: 10.1016/j.scitotenv.2021.151307

Abstract

Atmospheric brown carbon (BrC) is a light-absorbing component that affects radiative forcing; however, this effect requires further clarification, particularly with respect to BrC emission sources, chromophores, and optical properties. In the present study, the concentrations, optical properties, and emission factors of organic carbon (OC), water-soluble OC (WSOC), and humic-like substances (HULIS) in fine particulate matter (PM_2.5) emitted from vehicles in three road tunnels (the Wucun, Xianyue, and Wenxing tunnels in Xiamen, China) were investigated. The mass concentrations and light absorption of OC, WSOC, and HULIS were higher at the exits of each tunnel than at entrances, demonstrating that vehicle emissions were a BrC source. At each tunnel's exit, the average light absorption contributed by HULIS-BrC to water-soluble BrC (WS-BrC) and total BrC at 365 nm was higher than the corresponding carbon mass concentration contributed by HULIS (HULIS-C) to WSOC and OC, indicating that the chromophores of HULIS emitted from vehicles had a disproportionately high effect on the light absorption characteristics of BrC. The emission factors (EFs) of HULIS-C and WSOC mass concentrations were highest at the Xianyue tunnel; however, the EFs of HULIS-BrC and WS-BrC light absorption were highest at the Wenxing tunnel, indicating that the chromophore composition of BrC was different among the tunnels and that the mass concentration EFs did not correspond directly to the light absorption EFs.

Keywords: Brown carbon; Emission factors; Optical properties; Vehicle emissions.

MeSH terms

Aerosols / analysis
Air Pollutants* / analysis
Carbon* / analysis
Environmental Monitoring
Particulate Matter / analysis

Substances

Aerosols
Air Pollutants
Particulate Matter
Carbon