The contributions of non-methane hydrocarbon emissions by different fuel type on-road vehicles based on tests in a heavily trafficked urban tunnel

Shaoxuan Xiao; Yanli Zhang; Zhou Zhang; Wei Song; Chenglei Pei; Duohong Chen; Xinming Wang

doi:10.1016/j.scitotenv.2023.162432

The contributions of non-methane hydrocarbon emissions by different fuel type on-road vehicles based on tests in a heavily trafficked urban tunnel

Sci Total Environ. 2023 May 15:873:162432. doi: 10.1016/j.scitotenv.2023.162432. Epub 2023 Feb 24.

Authors

Shaoxuan Xiao¹, Yanli Zhang², Zhou Zhang³, Wei Song¹, Chenglei Pei⁴, Duohong Chen⁵, Xinming Wang¹

Affiliations

¹ State 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; CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China.
² State 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; CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: zhang_yl86@gig.ac.cn.
³ State 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.
⁴ State 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; Guangdong Province Guangzhou Ecological Environment Monitoring Center Station, Guangzhou 510030, China.
⁵ Guangdong Provincial Ecological Environment Monitoring Center, Guangzhou 510308, China.

PMID: 36841415
DOI: 10.1016/j.scitotenv.2023.162432

Abstract

Automobile exhaust is a major source of volatile organic compounds (VOCs) in metropolitan areas, yet it is difficult to accurately determine the contributions of different types of on-road vehicles. Tunnel tests are an effective way to measure real-world vehicle emissions, and the data collected are also suitable for receptor modeling to analyze the contributions of non-methane hydrocarbons (NMHCs) from different types of vehicles, as the closed environment ensures good mixing and minimal aging. In this study, tunnel tests were conducted inside a heavily trafficked city tunnel in Guangzhou in south China, and the positive matrix factorization (PMF) model was applied to the inlet-outlet incremental NMHC data. The results revealed that gasoline vehicles (GVs), Liquefied Petroleum Gas vehicles (LPGVs), and diesel vehicles (DVs) were responsible for 39 %, 45 % and 16 % of NMHCs, and 52 %, 23 %, and 24 % of the ozone formation potentials, respectively. LPGVs were the largest contributor of (56 %) alkanes, and GVs were the largest contributor of aromatics (61 %) and C₂-C₄ alkenes (55 %). With the video-recorded traffic counts the emissions of different fuel types are further compared on a per-vehicle-per-kilometer basis, and the results reveal that LPGVs and GVs were comparable in the OFPs of NMHCs emitted per kilometer, while on average a DV emitted 2.0 times more NMHCs than a GV with 2.4 times more OFPs. This study highlights substantial contribution of reactive alkenes and aromatics by DVs and the benefits of strengthening diesel exhaust control in terms of preventing ozone pollution.

Keywords: Non-methane hydrocarbons (NMHCs); Ozone formation potentials (OFPs); Positive matrix factorization (PMF); Tunnel test; Vehicle exhausts.