Polycyclic aromatic hydrocarbons in size-selected particulate matter in the air environment of Bangkok

Abstract

Samples of particulate matter less than 10 micro PM10, were collected from six sites (Chulalongkorn University, Chulalongkorn Hospital, Dindaeng, Office of Environment Policy and Panning, Singharat School and Bangkok University) in Bangkok, from November 1999 to November 2000, using high volume air-samples, Both PM 10 and size Fractionating Particulate Matter, SFPM, sampling using a multi-slit Anderson cascade impactor was undertaken at Chualongkorn University to identify paticulate size dirtribution. Samplings of particulate emission from various types of vehicles, industrial stacks and road dust have also been performed. The 24-hour PM10 concentrations varied from 23 micro g./cubic m. tp 160 micro g./cubic m. at Bangkok University and Chulalongkorn Hospital, respectively. The seasonal variation and traffic densities affected the particulate concentration in ambient air. All filter samples were extracted ultrasonically in acetonitrile and analysed for PAHs using High Performance Liquid Chromatography with UV-vis and Fluorescence detector. The total of 20 species of PAHs had an average concentration of 60 ng/cubic m. Benzo[e]pyrene(BeP), Indeno[123cd]pyrene (Ind) and Benzo[ghi]perylene (Bghip) were the major PAH in the ambient samples. There were more than 97% of PAHs found in the particulate matter<0.95 micro m. The low molecular weight PAHs were found in the heavy diesel emission. BghiP was the dominant PAH of the gosoline vehicles. BeP, Pyrene(Pyr) were dominant PAHs of stack emissions. The PAH profiles from ambient air samples were compared with the patterns obtained from different emission sources. The results indicate that PAHs were primarily for mobile sources.