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Quantifying the Impact of Biomass Burning on Aerosol Concentration in Bogota, Colombia: Detection of Biomass Burning Tracers
Maria Alejandra Rincon Caro, Amy P. Sullivan, Juan Manuel Rincón Riveros, Juan Felipe Mendez Espinosa, Luis Carlos Belalcazar, Ricardo Morales Betancourt

Última modificación: 14/06/2019


Aerosol particles generated during biomass burning (BB) have shown to significantly deteriorate air quality in many regions around the world and to impact climate through both direct and indirect aerosol effects. Recent studies suggest that a significant portion of the seasonal variations in PM pollution levels in the city of Bogota, Colombia, can be explained by regional transport of BB plumes from agricultural burns and wildfires. This contribution seems to be more important during the dry months (January-April) compared to the wet season (July-September). In this work we aim to quantify the local and regional contributions of BB aerosols to PM concentrations in the city by detecting biomass burning tracers in PM2.5 samples collected in Bogota. We conducted two field campaigns during 2018, one during January-March (dry season) and the other during July-September (dry to rainy transition period). Over 120 PM2.5 24-hour samples were collected in quartz filters. Chemical composition of the samples was carried out to determine carbonaceous fraction (OC, EC), water soluble organic carbon (WSOC), smoke tracers including levoglucosan, as well as other water soluble organic species. In addition, inorganic ions and metals were determined. To interpret the results, MODIS active fire data was used to select those fires with the potential to impact local air quality. Time series of selected fires were analyzed with concentrations of BB tracers within different buffer from Bogota. Mean daily PM2.5concentration during the dry season was 20 µg/m3 and 7.5 µg/m3 during the rainy season. OC was the dominant component of PM2.5 in both field campaigns with a larger contribution during the rainy season. We found a persistent presence of BB tracers in the samples for both field campaigns with higher concentrations of Levoglucosan during the dry season.  This study is the first to report full chemical composition analysis of PM2.5 in the city, highlighting the prevalence of organic aerosols and the large fraction of WSOC. Our results suggest that secondary organic aerosols are significant in this urban environment.