AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Chemical Characterization of Brown Carbon from Primary and Aged Biomass Burning Emissions during 2016 FIREX Campaign
TIANQU CUI, Sophie Tomaz, Yuzhi Chen, Shiva Tarun, Shantanu Jathar, Barbara Turpin, Jason Surratt, University of North Carolina at Chapel Hill
Abstract Number: 116 Working Group: Aerosol Chemistry
Abstract An important portion of light-absorbing carbonaceous constituents of organic aerosol (OA), referred to as brown carbon (BrC), can efficiently absorb near-UV and visible radiation, potentially altering Earth’s radiative forcing and cloud formation. In some instances, BrC can also contribute a considerable mass fraction of OA. Since BrC comprises a wide range of poorly characterized compounds and can be emitted primarily from biomass burning (BB), molecular-level characterization of OA derived from BB emissions becomes imperative to evaluate the impacts of BrC species on air quality and climate.
The study presented here involves the determination of the identities, quantities, and other key properties of BrC emitted directly by 107 “stack” or “room” combustion events of 39 fuel types (mostly biomass from western North America), systematically performed at the Fire Science Lab, Missoula, MT, during the 2016 Fire Influence on Regional and Global Environments Experiment (FIREX) campaign. In addition, select primary BB emissions of certain fuel types were aged in the Colorado State University (CSU) portable smog chamber to determine how photochemical reactions may alter primary BrC or produce new types of BrC not found in the original primary fraction. Teflon filter and particle-into-liquid sampler (PILS) samples of PM2.5 were collected from all the controlled combustion emissions and chemically characterized at the molecular level by (1) ultra performance liquid chromatography (UPLC) coupled to diode array detection (DAD), and to electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (ESI-HR-QTOFMS) operated in both positive and negative ion modes; and (2) gas chromatography interfaced with electron ionization mass spectrometry (GC/MS) with prior trimethylsilylation. Preliminary findings show excellent identification of well-established BB-derived products and a number of known BrC species from primary emissions, enabling us to further investigate their quantities, composition, contribution and other properties associated with varying fuel types and burn conditions.