Vehicular emission of volatile organic compounds (VOCs) from a tunnel study in Hong Kong

摘要

Vehicle emissions of volatile organic compounds (VOCs) were determined atthe Shing Mun Tunnel, Hong Kong in summer and winter of 2003. One hundredand ten VOCs were quantified in this study. The average concentration of thetotal measured VOCs at the inlet and outlet of the tunnel were 81 250 pptvand 117 850 pptv, respectively. Among the 110 compounds, ethene, ethyne andtoluene were the most abundant species in the tunnel. The total measured VOCemission factors ranged from 67 mg veh−1 km−1 to 148 mg veh−1 km−1,with an average of 115 mg veh−1 km−1. The five mostabundant VOCs observed in the tunnel were, in decreasing order, ethene,toluene, n-butane, propane and i-pentane. These five most abundant speciescontributed over 38% of the total measured VOCs emitted. The high propaneand n-butane emissions were found to be associated with liquefied petroleumgas (LPG)-fueled taxis. Fair correlations were observed between markerspecies (ethene, i-pentane, n-nonane, and benzene, toluene, ethylbenzene andxylenes – BTEX) with fractions of gasoline-fueled or diesel-fueled vehicles.Moreover, ethene, ethyne, and propene are the key species that were abundantin the tunnel but not in gasoline vapors or LPG. The ozone formationpotential from the VOCs in Hong Kong was evaluated by the maximum incrementreactivity (MIR). It was found to be 568 mg of ozone per vehicle perkilometer traveled. Among them, ethene, propene and toluene contribute mostto the ozone-formation reactivity.