AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Indonesian Peatland Fires Contribution to Haze Pollution over Singapore in 2015
SRI HAPSARI BUDISULISTIORINI, Matthieu Riva, Michael Williams, Takuma Miyakawa, Jing Chen, Jason Surratt, Mikinori Kuwata, Nanyang Technological University
Abstract Number: 154 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Transboundary haze from widespread fires in the forests and peatlands of Indonesia that has been recurring in the last decade, significantly elevated particulate matter (PM) concentration in the Southeast Asia, particularly during the 2015 El Niño. Previous studies have investigated chemical composition of particles emitted during peatland fires, however, they were limited to time-integrated samples and number of identified compounds. During October 10-31, 2015, Aerodyne Time-of-Flight Aerosol Chemical Speciation Monitor (ToF-ACSM) was deployed for real-time chemical characterization of ambient submicron PM (NR-PM$_1) in Singapore. Simultaneously, PM$_(2.5) samples were collected for molecular-level organic aerosol (OA) constituents, organic carbon (OC), elemental carbon (EC) and water soluble OC (WSOC). OA molecular-level tracers were quantified by gas chromatography interfaced to electron ionization mass spectrometry (GC/EI-MS) and ultra-performance liquid chromatography interfaced to high-resolution quadrupole time-of-flight mass spectrometer equipped with electrospray ionization operated in negative ion mode (UPLC/(-)ESI-HR-Q-TOFMS). Aerosol size distributions were measured by the NanoScan Scanning Mobility Particle Sizer and Optical Particle Sizer. OA and SO$_4$^(2-) are dominant components of the haze particles, accounting for 77% and 12% of the total NR-PM$_1 mass, respectively. OA mass mainly composes of OC, giving ratio of ~1.5. OA is generally oxidized as indicated by prevalent contribution of ion signals at m/z 44 (mostly CO$_2$^+) compared to m/z 43 (mostly C$_2H$_3O$^+). However, during a highly elevated NR-PM$_1 period, OA is less oxidized as showed by intense signals at m/z 43. OA from the TOF-ACSM were analyzed for factor analysis using positive matrix factorization (PMF). The biomass burning OA (BBOA) factor is confirmed with known biomass burning tracers (i.e. levoglucosan and mannosan). Significant amount of nitroaromatics were identified, indicating the formation of brown carbon (BrC) chromophores during wildfires.