Characterization of organic functional groups, water-soluble ionic species and carbonaceous compounds in PM10 from various emission sources in Songkhla Province, Thailand

Abstract

PM10 samples were collected at nine sampling stations using a high volume (hivol) air sampler during the period of June-November 2007. Using the ATR-FTIR technique, the chemical compositions of organic and water-soluble ionic species (WSIS) PM10 aerosols from each emission source were identified. WSIS such as SO42-, NO3-, CO32- , NH4+ were mainly found in PM10 aerosols. The highest concentrations of NO 3-, NH4+ and CO32- were detected in aerosols collected from sampling sites adjacent to traffic roads. This can be explained by the heterogeneous reaction of SO 2/NO2 mixtures with carbon soot that lead to the highest contribution of WSIS in combustion particles from vehicle exhausts. In addition, the ratios of organic carbon/elemental carbon (OC/EC) collected at heavy traffic road, bus terminal and traffic demonstrated the lowest values of 1.677 ± 0.198, 2.329 ± 0.570 and 2.770 ± 1.234 respectively. This indicates that the fine aerosols originating from vehicular emission are fresh particles. The relative contribution of organic functional groups like organic nitrate was highly detected in aerosols collected from industrial sampling sites. This could be ascribed to the intensive use of heavy oil and wood materials during the manufacturing process of animal feed and rubber sheet drying, respectively. More important it should be noted that from biomass burning sampling sites the relatively high intensity of carbonyl bands and aliphatic hydrocarbon IR absorption band illustrated the highest values in those PM10 associated with high OC/EC ratios. In this study, the oxidation state of sulfate aerosols were detected by using X-ray absorption near edge spectroscopy (XANES). The results show only S6+ peak of S-K edge at 2481 eV observed in all samples. © 2009 WIT Press.