Assessment of atmospheric particulate matter (PM10) in Central Brazil: Chemical and morphological aspects

Abstract

We characterized the PM10 sampled in Distrito Federal (DF), Central Brazil, an area close to agricultural processes, the Amazon Forest and impacted by biomass burning. We quantified the water-soluble ions (Na+, K+, Mg2+, Ca2+, Cl−, NO3−, SO42−), elements (Al, Ba, Cu, P, Zn), total carbon, 13C isotope and identified its morphology from January 2018 to September 2019. The sampling was performed at three stations: Fercal - cement industry zone; Rodoviária – bus station; and Zoo – background area. For the whole sampling and station, the mean ions concentrations (in ng.m−3) were in descending order: Ca2+ > SO42− > Na+ > NO3− > Cl− > K+ > Mg2+. The main water-soluble elements (in pg.m−3) were Al (269.91 ± 372.30), Ba (139.50 ± 169.30) and Zn (92.93 ± 141.48). Factor analysis for both dry and rainy seasons showed 3 and 2 factors, respectively, pertaining 83% and 92% of the dataset total variance. Different atmospheric processes in DF could be untangled, such as biomass burning and soil resuspension. Crystallized minerals of Ca and Si oxides were related to natural sources and the cement industry. Biological particles and some spherical ones with adsorbed metals (Ni, Cu, Zn) were associated with the origin of pollen, spores, or plants. According to the δ13C values, ranging from −19.60 to −24.12‰ at the Zoo and Rodoviária stations, the carbon source is closer to burning δ13C values of C3 plants of Cerrado vegetation. Our results indicate that air pollution in DF is influenced by precipitation regimes, and biomass burning.