Variabilidade espaço-temporal do material particulado fino (MP2,5) na Bacia Amazônica e sua relação com queimadas e El Niño Oscilação Sul (ENOS)

Abstract

This study analyzed the spatiotemporal variability of fine particulate matter (PM2.5) concentrations in the Amazon Basin between 2003 and 2023, using modeled data from the SatPM2.5 product, fire hotspot data from the MODIS sensor, and the Niño 3.4 index as an indicator of climate variability associated with the El Niño–Southern Oscillation (ENSO). Spatial and temporal patterns of PM2.5 concentrations were eval-uated, as well as trends, change points, and the relative contribution of seasonality, fires, and ENSO to the variability of this pollutant. The results revealed a heteroge-neous spatial pattern, with higher concentrations in the southern and southwestern portions of the basin, especially in areas associated with the arc of deforestation, northern Bolivia, Rondônia, Mato Grosso, southern Amazonas, and southern Pará. The lowest concentrations occurred in the northern and northwestern portions of the basin, where there is less direct influence from the main fire source regions. From a seasonal perspective, a well-defined annual cycle was observed, with lower values between May and July and a marked increase from August onward, reaching maxi-mum concentrations in the ASO quarter, especially in September. The regional anal-ysis indicated that areas more strongly influenced by fires show higher concentra-tions and critical pollution episodes, while central areas, although less associated with local fire sources, may be affected by aerosol transport during years of extreme drought. The trends showed spatially distinct behavior, with increases in the western, southwestern, northwestern, and central sectors of the basin, and decreases in southeastern areas. Multiple linear regression indicated that seasonality and fires are the main explanatory factors of PM2.5 variability, while ENSO exerts a complementary and indirect influence, mainly on interannual anomalies. ENSO also showed a sea-sonally concentrated influence in ASO and NDJ, especially in the northern Amazon Basin, contributing complementarily to the interannual variability of PM2.5. The results reinforce the importance of continuous air quality monitoring and the integration of climate, fire, and environmental management information in the Amazon, to ade-quately protect the region’s vulnerable populations from this growing threat.