Identification of two main origins of intermediate-volatility organic compound emissions from vehicles in China through two-phase simultaneous characterization

Yuanxiang Liu; Yingjie Li; Zibing Yuan; Hongli Wang; Qing'e Sha; Shengrong Lou; Yuehui Liu; Yuqi Hao; Lejun Duan; Penglin Ye; Junyu Zheng; Bin Yuan; Min Shao

doi:10.1016/j.envpol.2021.117020

Identification of two main origins of intermediate-volatility organic compound emissions from vehicles in China through two-phase simultaneous characterization

Environ Pollut. 2021 Jul 15:281:117020. doi: 10.1016/j.envpol.2021.117020. Epub 2021 Mar 25.

Authors

Yuanxiang Liu¹, Yingjie Li², Zibing Yuan³, Hongli Wang⁴, Qing'e Sha⁵, Shengrong Lou², Yuehui Liu², Yuqi Hao¹, Lejun Duan¹, Penglin Ye⁶, Junyu Zheng⁵, Bin Yuan⁵, Min Shao⁵

Affiliations

¹ School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China.
² State Environmental Protection Key Laboratory of the Cause and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental Sciences, Shanghai, 200233, China.
³ School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China. Electronic address: zibing@scut.edu.cn.
⁴ State Environmental Protection Key Laboratory of the Cause and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental Sciences, Shanghai, 200233, China. Electronic address: wanghl@saes.sh.cn.
⁵ Institute for Environmental and Climate Research, Jinan University, Guangzhou, 511443, China.
⁶ Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai, 200438, China.

PMID: 33813191
DOI: 10.1016/j.envpol.2021.117020

Abstract

Intermediate-volatility organic compounds (IVOCs) emitted from vehicles are generally in the gas phase but may partly partition into particle phase when measured under ambient temperature. To have a complete and accurate picture of IVOC emissions from vehicles, gas- and particle-phase IVOCs from a fleet of gasoline and diesel vehicles were simultaneously characterized by dynamometer testing in Guangzhou, China. The total IVOC emission factors of the diesel vehicles were approximately 16 times those of the gasoline vehicles, and IVOCs were mainly concentrated in the particle phase in the form of the unresolved complex mixture (UCM). The chemical compositions and volatility distributions of the gas-phase IVOCs differed much between gasoline and diesel vehicles, but were similar to those of their respective fuel content. This indicated that vehicle fuel is the main origin for the gas-phase IVOC emissions from vehicles. In comparison, the chemical compositions of the particle-phase IVOCs from gasoline and diesel vehicles were similar and close to lubricating oil content, implying that lubricating oil plays an important role in contributing to particle-phase IVOCs. The highest IVOC fraction in the particle phase occurred from B₁₆-B₁₈ volatility bins, overall accounting for more than half of the particle-phase IVOCs for both the gasoline and diesel vehicles. A conceptual model was developed to articulate the distributions of lubricating oil contents and their evaporation and nucleation/adsorption capabilities in the different volatility bins. The IVOCs-produced secondary organic aerosol (SOA) were 1.4-2.6 and 3.9-11.7 times POAs emitted from the gasoline and diesel vehicles, respectively. The tightening of emission standards had not effectively reduced IVOC emissions and the SOA production until the implementation of China VI emission standard. This underscores the importance of accelerating the promotion of the latest emission standard to alleviate pollution from vehicles in China.

Keywords: Emission standards; Gas-particle partitioning; Intermediate-volatility organic compounds; Lubricating oil; Secondary organic aerosols.

MeSH terms

Aerosols / analysis
Air Pollutants* / analysis
China
Gasoline / analysis
Motor Vehicles
Vehicle Emissions / analysis
Volatile Organic Compounds* / analysis
Volatilization

Substances

Aerosols
Air Pollutants
Gasoline
Vehicle Emissions
Volatile Organic Compounds