Abstract:
Twenty five diesel vehicles, 13 heavy duty diesel vehicles (HDDV) and 12 light duty diesel vehicles (LDDV), were tested using chassis dynamometer operated with constant volume sampler system (CVS) and were driven through the Bangkok Driving Cycle in order to study their emission factors. In exhaust of tested vehicles, particulate matters (PM) in different size ranges between 0.18-18 micron were collected by Micro Orifice Uniform Dispersion Impactor (MOUDI), and gas samples were adsorbed with XAD-2 resin in PUF tube accompanied with personal air sampler. Polycyclic aromatic hydrocarbons (PAHs) adsorbed on PM (pPAHs) and those existing in gas samples were quantitatively analyzed by gas chromatography/mass spectrometry (GC/MS). Real-time pPAHs concentration was also measured using Photoelectric Aerosol Sensor (pas 2000CE). For total PM emissions, HDDV samples generated significantly higher than those of LDDV with the average values of 245.2+_56.0 and 518.5+_244.0 g/m[superscript3], respectively. PM size distributions of HDDV were found to be broadly bimodal which mainly distributed in the ranges of 0.1 1.0 and 3.2 10 micron, while the result of LDDV show widely distribution in all size ranges. The average real time pPAHs concentrations measured from HDDV were relatively higher than those of LDDV, and the concentration profiles of both vehicle types corresponded to the driving cycles. Dominant species of PAHs adsorbed on PM emitted form both HDDV and LDDV were Anth, Fla, Pyr, BaA, Chr, BbF, BkF, BaP, BghiP, I(1,2,3-cd)P, and DahA, whereas Naph, Acy, Ace, Flu, Phe, Anth, Fla, and Pyr were predominantly found in the gas samples. The average of total PAHs concentrations (i.e. gas and particulate phases of PAHs) determined from HDDV and LDDV were 9,092.1+_628.0 and 2,959.9+_1,208.2 g/m[superscript3], respectively. Emission factors of total PM for HVVD and LDDV were 223.0+_90.0 and 83.3+_4.5 g/km, respectively. For total PAHs, emission fators of 353.1+_134.0 for HDDV and of 32.6+_11.9 mg/km for LDDV could be obtained.