Composition of aerosol particles generated at different phases of biomass burning processes; laboratory and field investigations

Abstract

This study is focused on the investigations of bushfire-originated smoke particle released during different prescribed burning events conducted between May 2018 and August 2019 in Toohey forest region, Queensland, Australia. Particle size/mass distribution along with corresponding elemental content had been comprehensively measured and the results were compared against outcomes obtained during the combustion of similar vegetation under controlled laboratory conditions. It was found that the concentration of coarse particle with the sizes above 1 μm was higher during natural bushfire events, whereas the contributions of PM1 was higher in the laboratory burns. Elemental analysis of different size fractions (<0.96 μm, 0.96–2.5 μm, and >2.5 μm) confirmed eight mutual elements determined for both cases (Na, K, Mg, Ca, Zn, Al, Fe, S), however, level of elements such as Ca, Mg, Al, and S were significantly higher in cases of prescribed fires. Such discrepancies between field and laboratory results could be attributed to the presence of soil and duff layers unavoidable in natural bushfires and absence thereof in the laboratory burns, which confirms substantial influence of such layers on the general air quality situation across bushfires affected regions.