Aerosol characterization in a Central-West site of Brazil: influence of farming activities and toxicity

The Central-West region of Brazil presents three important and large ecosystems: the Amazon, the Cerrado, and the Pantanal biomes. Different anthropogenic activities (e.g., biomass burning and land use) affect this area, emitting particulate matter (PM) that can be transported to urban sites, adding to the local vehicular sources. Sampling of atmospheric particulate material with a size less than and equal to 10 μm (PM₁₀) was carried out in the medium-sized city of Cuiabá (Brazil), between 2008 and 2014. The maximum concentrations of PM₁₀ were found in the dry season, surpassing the recommended levels by the World Health Organization. A slight seasonal variation was found between the concentrations of organic carbon, elemental carbon, elements, and water-soluble ions (WSI), with higher levels in the dry season, enhanced by biomass burning and dust resuspension. Polycyclic aromatic hydrocarbons, their nitrated and oxygenated derivatives (nitro and oxy-PAHs), and some n-alkanes showed similar behaviors in the dry and rainy seasons, with higher abundance of carcinogenic PAHs compared to the rest of the polyaromatics. Total incremental lifetime cancer risks due to exposure to PAHs were found to exceed the safety level. Based on the application of diagnostic ratios and the positive matrix factorization receptor model, biomass burning, soil and road dust resuspension, vehicular exhaust, and mining activities were pointed out as emission sources. These results allow us to better understand the aerosol sources that contribute to the worsening of air quality in a growing urban area.