AI Article Synopsis

  • - This study analyzed the emissions of 120 different volatile organic compounds (VOCs) from 40 types of nonroad machines, finding that diesel engines emit an average of 4.18 g of VOCs per kg of fuel, mainly consisting of alkanes and oxygenated VOCs.
  • - Various factors such as machine type, power rating, and operating conditions influenced VOC emissions, with combustion efficiency being a key determinant.
  • - The research highlighted the significant potential for these VOCs to form secondary organic aerosols and ozone, suggesting that targeting specific VOC species could effectively reduce air pollution from nonroad mobile sources, particularly in China's construction and agricultural sectors.

Article Abstract

Volatile organic compound (VOC) emissions originating from nonroad mobile sources constitute an important but uncertain source of secondary organic aerosols (SOAs) and ozone (O). In this study, we investigated the emission factors (EFs) of 120 individual VOC species for 40 machines via gas chromatography-mass spectrometry/flame ionization detection and high-performance liquid chromatography. The results showed that the diesel-based VOC EF for the tested machines was 4.18 ± 2.55 (average ± standard deviation) g/kg fuel, dominated by alkanes (38.20 % ± 18.08 %) and oxygenated VOCs (OVOCs; 30.94 % ± 15.71 %). The machine type, rated power, emission standards, and operating conditions affected the emissions of VOCs and their components, and this effect maybe mostly depends on the fuel combustion efficiency. The VOC species were primarily distributed in the C-C and C-C (based on the carbon number) and B-B (based on the saturated vapor concentration) intervals. Furthermore, the estimated formation potential (FP) values of SOAs and O from VOCs were 21.02 ± 15.57 mg/kg fuel and 15.96 ± 11.87 g/kg fuel, respectively. VOC control based on the SOA formation potential (SOAFP) and ozone formation potential (OFP) could be more effective in the mitigation of fine particulate matter (PM) and O pollution because the top 5 species ranked by percentage contribution accounted for 83.09 % ± 9.59 % and 51.78 % ± 14.38 % of the estimated SOAFP and OFP, respectively. Finally, the emission estimates showed that the VOC emissions originating from construction and agricultural machinery in China (2020) reached 64.05 and 95.24 Gg, respectively. We provide species-specific VOC EFs and detailed emission characteristics to facilitate a comprehensive understanding of gas emissions originating from nonroad mobile sources and an update of emission inventories and atmospheric chemistry models.

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Source
http://dx.doi.org/10.1016/j.scitotenv.2023.164993DOI Listing

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