Spatial variability and source apportionment of particulate matter (PM2.5) in Rio de Janeiro: insights from Urban, preserved, and biomass burning areas

Abstract

Air pollution is a critical environmental issue influenced by both natural and anthropogenic sources. We hypothesized that PM_2.5 chemical composition varies spatially due to local anthropogenic sources, soil resuspension, and biomass burning. This study analyzed particulate matter (PM_2.5) concentrations and chemical composition (black carbon (BC), elements, and ions) in three locations in Rio de Janeiro state: Gávea (urban area), PARNASO (environmental preservation area), and Campos dos Goytacazes (urban with burning biomass). The results show that PM_2.5 concentrations varied significantly among the sampled sites, with the average highest values recorded in PARNASO (20 ± 13 µg m^− 3), followed by Gávea (12 ± 7 µg m^− 3), and Campos (8 ± 4 µg m^− 3). Although no daily samples exceeded Brazilian air quality standards, 23% surpassed WHO guidelines. Fe and Al were the most abundant elements in all sites, indicating strong soil resuspension influence, with higher concentrations in Campos. BC was higher in PARNASO (2.2 ± 0.9 µg m^− 3) but contributed more to PM_2.5 in Campos (22–24%), highlighting the biomass-burning influence. Water-soluble ions, particularly Cl⁻, Na⁺, SO₄²⁻, and NO₃⁻, were predominant across all sites, with K⁺ showing statistical differences between seasonality in Campos. A Principal Component Analysis (PCA) identified soil resuspension, vehicular emissions, and biomass burning as major contributors to PM_2.5 pollution. These findings underscore the necessity for region-specific air quality policies and continuous monitoring, emphasizing their global relevance for effective long-term pollution mitigation in urban, and preserved areas.