Carbonaceous Aerosols from Indonesian Peat Land Fires: Sources and Characteristics

RAGHU BETHA, Rajasekhar Balasubramanian, Texas Tech University

     Abstract Number: 377
     Working Group: Source Apportionment

Abstract
The contribution of transboundary smoke haze episodes, caused by peat and above-ground biomass fires in Indonesia, to urban airborne particulate matter (PM) in Southeast Asia (SEA) has received considerable attention from the air quality management viewpoint because of their repeated occurrence in recent years. In this study, we conducted a detailed chemical speciation and carbon isotope analysis of carbonaceous aerosols (CA) during an unprecedented smoke haze episode in Southeast Asia (SEA) in the non-ENSO year of 2013. We also present a novel source apportionment approach using a combination of latin hypercube sampling (LHS) and generalized reduced gradient (GRG) methods to estimate the individual contributions of peat and vegetative biomass to CA. Our results indicate that nearly 82% of the total carbon, as observed in Singapore, is contributed by Indonesian peat fires, with peat accounting for ~68% and vegetative biomass by ~14%. The chemical speciation of organic aerosols indicated that cellulose pyrolysis products, a form of primary organic aerosols, and the secondary dicarboxylic acids increased by a factor of 22 and 10 times, respectively. Additionally, we observed an enhancement in the concentrations of fossil fuel combustion-related compounds such as hopanes and steranes under the haze layer. The findings reveal that peatland fire activities during non-ENSO years could lead to serious haze events, affect the air quality in the SEA region significantly, and imply adverse environmental and health impacts.