Preprints
https://doi.org/10.5194/acp-2022-130
https://doi.org/10.5194/acp-2022-130
 
18 Feb 2022
18 Feb 2022
Status: a revised version of this preprint is currently under review for the journal ACP.

Oxygenated VOCs as significant but varied contributors to VOC emissions from vehicles

Sihang Wang1,2, Bin Yuan1,2, Caihong Wu1,2, Chaomin Wang1,2, Tiange Li1,2, Xianjun He1,2, Yibo Huangfu1,2, Jipeng Qi1,2, Xiaobing Li1,2, Junyu Zheng1,2, Qing'e Sha1,2, Manni Zhu1,2, Shengrong Lou3, Hongli Wang3, Thomas Karl4, Martin Graus4, Zibing Yuan5, and Min Shao1,2 Sihang Wang et al.
  • 1Institute for Environmental and Climate Research, Jinan University, Guangzhou 511443, China
  • 2Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou 511443, China
  • 3State Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental Sciences, Shanghai 200233, China
  • 4Department of Atmospheric and Cryospheric Sciences, University of Innsbruck, Innsbruck, Austria
  • 5College of Environment and Energy, South China University of Technology, University Town, Guangzhou 510006, China

Abstract. Vehicular emission is an important source for volatile organic compounds (VOCs) in urban and downwind regions. In this study, we conducted a chassis dynamometer study to investigate VOC emissions from vehicles using gasoline, diesel, and liquefied petroleum gas (LPG) as fuel. Time-resolved VOC emissions from vehicles are chemically characterized by a proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) with high frequency. Our results show that emission factors of VOCs generally decrease with the improvement of emission standard for gasoline vehicles, whereas variations of emission factors for diesel vehicles with emission standards are more diverse. Mass spectra analysis of PTR-ToF-MS suggest that cold start significantly influence VOCs emission of gasoline vehicles, while the influences are less important for diesel vehicles. Large differences of VOC emissions between gasoline and diesel vehicles are observed with emission factors of most VOC species from diesel vehicles were higher than gasoline vehicles, especially for most oxygenated volatile organic compounds (OVOCs) and heavier aromatics. These results indicate quantification of heavier species by PTR-ToF-MS may be important in characterization of vehicular exhausts. Our results suggest that VOC pairs (e.g. C14 aromatics/toluene ratio) could potentially provide good indicators for distinguishing emissions from gasoline and diesel vehicles. The fractions of OVOCs in total VOC emissions are determined by combining measurements of hydrocarbons from canisters and online observations of PTR-ToF-MS. We show that OVOCs contribute 7.7 % ± 6.2 % of gasoline vehicles of the total VOC emissions, while the fractions are significantly higher for diesel vehicles (40–77 %), highlighting the importance to detect these OVOC species in diesel emissions. Our study demonstrated that the large number of OVOC species measured by PTR-ToF-MS are important in characterization of VOC emissions from vehicles.

Sihang Wang et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-130', Anonymous Referee #1, 12 Mar 2022
  • RC2: 'Comment on acp-2022-130', Anonymous Referee #2, 24 Mar 2022

Sihang Wang et al.

Sihang Wang et al.

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Short summary
VOC emissions from vehicles are measured using online mass spectrometers. Large differences between gasoline and diesel vehicles are observed, with higher emission factors of most OVOCs and heavier aromatics from diesel vehicles. We proposed higher aromatics/toluene ratio could potentially provide good indicators for distinguishing emissions from gasoline and diesel vehicles. We show that OVOCs account for significant contributions to VOCs emissions from vehicles, especially diesel vehicles.
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