Optical properties of vehicular brown carbon emissions: Road tunnel and chassis dynamometer tests

Chung Song Ho; Zongyan Lv; Jianfei Peng; Jinsheng Zhang; Tong-Hyok Choe; Qijun Zhang; Zhuofei Du; Hongjun Mao

doi:10.1016/j.envpol.2023.121037

Optical properties of vehicular brown carbon emissions: Road tunnel and chassis dynamometer tests

Environ Pollut. 2023 Mar 1:320:121037. doi: 10.1016/j.envpol.2023.121037. Epub 2023 Jan 11.

Authors

Chung Song Ho¹, Zongyan Lv², Jianfei Peng³, Jinsheng Zhang², Tong-Hyok Choe⁴, Qijun Zhang², Zhuofei Du², Hongjun Mao²

Affiliations

¹ Tianjin Key Laboratory of Urban Transport Emission Research & State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300071, China; High-Tech Research and Development Center, Kim Il Sung University, Pyongyang, 999093, Democratic People's Republic of Korea.
² Tianjin Key Laboratory of Urban Transport Emission Research & State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300071, China.
³ Tianjin Key Laboratory of Urban Transport Emission Research & State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300071, China. Electronic address: pengjianfei@nankai.edu.cn.
⁴ Faculty of Global Environmental Science, Kim Il Sung University, Pyongyang, 999093, Democratic People's Republic of Korea.

PMID: 36641064
DOI: 10.1016/j.envpol.2023.121037

Abstract

Brown carbon (BrC), as an important light-absorbing aerosol, significantly impacts regional and global climate. Vehicle emission is a nonnegligible source of BrC, but the optical properties of BrC emitted from vehicles remain poorly understood. This study evaluates the absorption Ångström exponent (AAE) of traffic-related light-absorbing aerosols (i.e., AAE_Tr) and the absorption emission factor (EF_abs) of vehicular BrC via chassis dynamometer tests and a road tunnel measurement in Tianjin, China. AAE_Tr are estimated as 0.98-1.33 and 1.11 ± 0.001 for tested vehicles and on-road vehicle fleet, respectively. The AAE of vehicular BrC (AAE_BrC) is 3.83 ± 0.092 for on-road vehicle fleet. The vehicle technology updates effectively reduce the EF_abs of vehicular BrC. Among the four tested China 5 and China 6 gasoline vehicles in the chassis dynamometer tests, BrC EF_abs of China 5 gasoline direct injection vehicle is the highest, while China 6 mixing fuel injection vehicle exhibits the lowest EF_abs. The BrC EF_abs of on-road vehicle fleet at 370 nm wavelength are 0.081 ± 0.0058 m² kg^-1 for mixed fleet, 0.074 ± 0.018 m² kg^-1 for gasoline vehicles (GVs), and 1.66 ± 0.71 m² kg^-1 for diesel vehicles (DVs) in the tunnel measurement. EF_abs of GV fleet in the road tunnel is higher than China 5 and China 6 vehicles, as China 1-4 vehicles accounted for 26.8% of the total vehicle fleet in the tunnel. EF_abs of vehicular BrC are lower than those from biomass burning and coal combustion emissions. The light absorption of BrC from GVs and DVs accounts for 7.2 ± 2.1% and 1.5 ± 0.77% of total traffic-related absorption at 370 nm, respectively. Our study provides optical features of BrC from vehicle source and could contribute to estimating the impacts of vehicular aerosol emissions on global and regional climate change.

Keywords: Absorption Ångström exponent; Black carbon; Brown carbon; Emission factor; Vehicular emission.

MeSH terms

Aerosols / analysis
Air Pollutants* / analysis
Carbon
Environmental Monitoring
Gasoline
Vehicle Emissions* / analysis

Substances

Vehicle Emissions
Air Pollutants
Gasoline
Carbon
Aerosols