AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
The Impact of Biomass Burning on Fine Aerosol Acidity, Water Content and Nitrogen Partitioning
Aikaterini Bougiatioti, Despina Paraskevopoulou, Iasonas Stavroulas, Stelios Myriokefalitakis, Nikos Daskalakis, Rodney J. Weber, Maria Kanakidou, Nikolaos Mihalopoulos, ATHANASIOS NENES, Georgia Institute of Technology
Abstract Number: 544 Working Group: Aerosol Chemistry
Abstract Biomass burning is an important source of regional and global pollution, contributing 44% of the total PM2.5 emissions in the EU. During BB episodes considerable amounts of ammonia, NOx, organics, variable amounts of K+, Na+, Cl- and minor amounts of sulfate are emitted into the atmosphere. All these species can impact on the aerosol liquid water content as well as the particle pH, but to an extent that is currently not known. Motivated by this, we analyze composition measurements conducted in Athens (Greece) during winter 2013, to evaluate the impact of BB on aerosol water and acidity (pH). Acidity and liquid water is obtained by thermodynamic analysis of the observations with the ISORROPIA-II model.
From our analysis we find that BB contributes significantly to the increased organic aerosol loadings, BCwb, particulate nitrates, chloride, and potassium. These increased concentrations strongly impact on fine aerosol water, with Winorg having an average concentration of 11±14 μg m-3 and Worg constituting almost 38% of the total submicron aerosol water content. Particle pH was generally found to be acidic, with average pH during strong BB influence of 2.8±0.5, value similar to the pH observed for regional aerosol influenced by BB episodes at a remote background site (Crete).
During cleaner days without BB influence, submicron aerosol was found to be more acidic, with a pH that was lower by about 1 unit. The reduced acidity of aerosol during BB periods is attributed to the presence of non-volatile cations and co-condensation of nitrate and ammonium. The reduced acidity predisposes the inorganic nitrate and chloride tends to reside in the aerosol. Global model simulations confirm that this is an effect seen in regional and global scales, therefore carrying important implications for public health, climate and ecosystems.