AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Quantifying the Impact of Biomass Burning on Aerosol Concentrations in Bogota, Colombia: Detection of Biomass Burning Tracers and Model Simulations
Maria Alejandra Rincón, Amy P. Sullivan, Juan Manuel Rincón, Juan Felipe Mendez, Karen Ballesteros, RICARDO MORALES BETANCOURT, Universidad de los Andes
Abstract Number: 673 Working Group: Biomass Combustion: Emissions, Chemistry, Air Quality, Climate, and Human Health
Abstract Biomass burning (BB) aerosol particles significantly deteriorate air quality in many regions around the world and 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. Chemical transport modelling with WRF-Chem and back trajectory analysis are also performed to further apportion the local versus regional contributions. We conducted two field campaigns during 2018 simultaneously at two sites in the city of Bogota, one during the dry season and the other during the rainy season. 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 some 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 PM2.5 concentration 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. A large WSOC/OC ratio of 0.63 was observed in the dry season samples. We found a persistent presence of BB tracers in the samples for both field campaigns with higher concentrations of Levoglucosan during the dry season. A stronger association between BB tracers was observed in the dry season compared to the rainy season samples. Regional chemical transport model simulations with WRF-Chem including fire emissions further confirm the seasonal impact of BB to PM 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.