Aerosol Chemical Characterization and Contribution of Biomass Burning to Particulate Matter at a Residential Site in Islamabad, Pakistan

Air pollution creates a very serious problem in developing countries, and scarce information is available about the nature of pollutants. This study describes the chemical composition of particulate matter (TSP and PM10), including marker compounds pointing to pollution sources, and estimates the contribution of biomass smoke to organic carbon (OC) and particulate matter (PM) at a residential site in Islamabad during the winter period in December 2007. Levoglucosan and its relationship with other anhydrosaccharides were used to estimate the biomass burning contribution, and polyols and primary and secondary saccharides were investigated regarding biological aerosol. Polyols and primary saccharides contribute a small fraction of the total PM10 and TSP mass, whereas anhydrosaccharides contribute more than 90% in both the PM10 and TSP. A significant contribution from biomass smoke has also been found in Islamabad, forming 10% of the TSP and 18% of the PM10 mass. The analysis of the distributions of saccharide concentrations between the TSP and PM10 fractions shows that anhydrosaccharides, viz., levoglucosan, mannosan and galactosan, all of which are directly related to the combustion of biomass, are mainly present in the PM10 The concentration of TSP varied from 218 mu g m(-3) to 468 mu g m(-3) (mean: 343 mu g m(3)), and PM10 concentrations were in the range of 89-304 mu g m(3) (mean: 194 mu g m(3)). A good correlation was observed between PM10, TSP and Ca2+, which implies that mineral/road dust may be a major contributor to the PM in Islamabad.