26 Mar 2021

26 Mar 2021

Review status: this preprint is currently under review for the journal ACP.

Measurement report: Emissions of intermediate-volatility organic compounds from vehicles under real-world driving conditions in an urban tunnel

Hua Fang1,2,4, Xiaoqing Huang1,2,4, Yanli Zhang1,2,3, Chenglei Pei1,4,5, Zuzhao Huang6, Yujun Wang5, Yanning Chen5, Jianhong Yan7, Jianqiang Zeng1,2,4, Shaoxuan Xiao1,2,4, Shilu Luo1,2,4, Sheng Li1,2,4, Jun Wang1,2,4, Ming Zhu1,2,4, Xuewei Fu1,2,4, Zhenfeng Wu1,2,4, Runqi Zhang1,2,4, Wei Song1,2, Guohua Zhang1,2, Weiwei Hu1,2, Mingjin Tang1,2, Xiang Ding1,2, Xinhui Bi1,2, and Xinming Wang1,2,3,4 Hua Fang et al.
  • 1State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
  • 2CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
  • 3Center for Excellence in Urban Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
  • 4University of Chinese Academy of Sciences, Beijing 100049, China
  • 5Guangzhou Ecological and Environmental Monitoring Center of Guangdong Province, Guangzhou 510060, China
  • 6Guangzhou Environmental Technology Center, Guangzhou 510180, China
  • 7Guangzhou Tunnel Development Company, Guangzhou 510133, China

Abstract. Intermediate-volatility organic compounds (IVOCs) emitted from vehicles are important precursors to secondary organic aerosols (SOA) in urban areas, yet vehicular emission of IVOCs, particularly from on-road fleets, is poorly understood. Here we initiated a field campaign to collect IVOCs with sorption tubes at both the inlet and the outlet in a busy urban tunnel (>30,000 vehicles per day) in south China for characterizing emissions of IVOCs from on-road vehicles. The average emission factor of IVOCs (EFIVOCs) was measured to be 16.77 ± 0.89 mg km-1 (Average ± 95% C.I.) for diesel and gasoline vehicles in the fleets, and based on linear regression the average EFIVOCs was derived to be 62.79 ± 18.37 mg km-1 for diesel vehicles and 13.95 ± 1.13 mg km-1 for gasoline vehicles. The EFIVOCs for diesel vehicles from this study was comparable to that reported previously for non-road engines without after-treatment facilities, while the EFIVOCs for gasoline vehicles from this study was much higher than that recently tested for a China V gasoline vehicle. IVOCs from the on-road fleets did not show significant correlation with the primary organic aerosol (POA) or total non-methane hydrocarbons (NMHCs) as results from previous chassis dynamometer tests. Estimated SOA production from the vehicular IVOCs and VOCs surpassed the POA by a factor of ~ 2.4, and IVOCs dominated over VOCs in estimated SOA production by a factor of ~ 7, suggesting that controlling IVOCs is of greater importance to modulate traffic-related OA in urban areas. The results demonstrated that although on-road gasoline vehicles have much lower EFIVOCs, they contribute more IVOCs than on-road diesel vehicles due to its dominance in the on-road fleets. However, due to greater diesel than gasoline fuel consumption in China, emission of IVOCs from diesel engines would be much larger than that from gasoline engines, signaling the overwhelming contribution of IVOC emissions by non-road diesel engines in China.

Hua Fang et al.

Status: open (until 21 May 2021)

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Hua Fang et al.


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Short summary
A tunnel test was initiated to measure the vehicular IVOCs emissions under real-world driving conditions. Higher SOA formations estimated from vehicular IVOCs than that from traditional VOCs emphasized the greater importance of IVOCs in modulating urban SOA. The results also revealed that non-road diesel-fueled engines greatly contributed to IVOCs in China.