AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Characterization of Transboundary Biomass Burning Smoke on Organic Aerosols in a Tropical Urban Environment: Dicarboxylic Acids, Malic Acid, and Photooxidation Intermediates of Levoglucosan
Liming Yang, Wei Hong Fan, Shiguo Jia, Duc Minh Nguyen, Jeffrey Reid, LIYA YU, National University of Singapore
Abstract Number: 49 Working Group: Remote and Regional Atmospheric Aerosols
Abstract Biomass burning (BMB) smoke in Southeast Asia has been reported to contain unique chemical composition, which could be due to special composition of peatland in this region. Biomass burning in Southeast (SE) Asia occurs annually, depending on weather and countries, intensity and chemical composition of the smoke in SE Asia vary significantly, so as the transboundary smoke reaching Singapore, an urban receptor site. This work investigates impacts of the transboundary smoke on urban aerosols based on the observations in 2008. Data obtained in this year represent “light” presence of transboundary BMB smoke in the urban environment and can serve as a lower bound of impacts imposed by the transboundary BMB smoke.
Daily ambient PM2.5 was collected during 8 September to 5 October (Julian Days, JDs 252–279), 2008 in Singapore; based on backward trajectory analysis of smoke and fire counts of in the region, Singapore was affected by the smoke for 12 out of the 28 sampling days. Although PM2.5 varied marginally, the smoke increased C2–C5 total dicarboxylates (TDCAS, summation of dicarboxylic acids and dicarboxylate salts) on average more than two times, and levoglucosan, more than five times. During the presence of the transboundary smoke, C2-TDCAS accounted for around 80% of the C2–C5 TDCAS; oxalate salts exhibited the highest concentration (355.0 ng/m$^3), which is more than 13 times of oxalic acid. The transboundary smoke increased malic acid concentration more than 3.5 times, the largest relative increase among the quantified TDCAS, indicating more prominent photooxidation incurred by the smoke. Quantifiable photooxidation intermediates of levoglucosan, including malic acid, show consistent temporal trends with levoglucosan throughout the study period. Among the identifiable intermediates, ribonolactone concentration exhibits the highest linear correlation with levoglucosan during the presence of the smoke with R$^2 of 0.8.