AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Light-absorbing Organic Carbon from Prescribed and Laboratory Biomass Burning and Gasoline Vehicle Emissions
MINGJIE XIE, Michael Hays, Amara Holder, U.S. EPA
Abstract Number: 238 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Light-absorbing organic carbon (OC), i.e. brown carbon (BrC), from laboratory-based biomass burning (BB) has been studied intensively to understand the contribution of BB to radiative forcing. However, few measurements have been conducted on field burns and even fewer measurements have been done on BrC from other combustion sources like motor vehicle emissions. In this work, we examined the light absorption of methanol-extractable OC from prescribed and laboratory BB and gasoline vehicle emissions from spectrophotometric measurements. The light absorption by the methanol extracts had a strong wavelength dependence for both BB and gasoline vehicle emissions. The mass absorption coefficients at 365 nm (MAC365, m2 g-1C) – a measure of BrC – were significantly correlated (p < 0.05) with the ratios of elemental carbon (EC) to OC for BB from identical fuels, while no significant correlation could be observed across multiple fuels, indicating that both burn conditions and fuel types might impact BB BrC characteristics. The average MAC365 of all gasoline vehicle emission samples is 0.61 ± 0.76 m2 g-1C, the same magnitude as all BB samples (1.27 ± 0.76 m2 g-1C). These results suggested that in addition to BB, gasoline vehicle emissions might also be an important BrC source in urban areas.