Organic composition of carbonaceous aerosols in an aged prescribed fire plume B. Yan1, M. Zheng1, Y. T. Hu2, S. Lee1,*, H. K. Kim2, and A. G. Russell2 1School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA 2School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, USA *currently at: Measurement Support Center, Division of Quality of Life, Korea Research Institute of Standards and Science, Daejeon, Republic of Korea
Abstract. Aged smoke from a prescribed fire (dominated by conifers) impacted
Atlanta, GA on 28 February 2007 and dramatically increased hourly
ambient concentrations of PM2.5 and organic carbon (OC) up to 140 and
72 μg m−3, respectively. It was estimated that over 1 million
residents were exposed to the smoky air lasting from the late afternoon to
midnight. To better understand the processes impacting the aging of fire
plumes, a detailed chemical speciation of carbonaceous aerosols was
conducted by gas chromatography/mass spectrometry (GC/MS) analysis. Ambient
concentrations of many organic species (levoglucosan, resin acids, retene,
n-alkanes and n-alkanoic acids) associated with wood burning emission were
significantly elevated on the event day. Levoglucosan increased by a factor
of 10, while hopanes, steranes, cholesterol and major polycyclic aromatic
hydrocarbons (PAHs) did not show obvious increases. Strong odd over even
carbon number predominance was found for n-alkanes versus even over odd
predominance for n-alkanoic acids. Alteration of resin acids during
transport from burning sites to monitors is suggested by the observations.
Our study also suggests that large quantities of biogenic volatile organic
compounds (VOCs) and semivolatile organic compounds (SVOCs) were released
both as products of combustion and unburned vegetation heated by the fire.
Higher leaf temperature can stimulate biogenic VOC and SVOC emissions, which
enhanced formation of secondary organic aerosols (SOA) in the atmosphere.
This is supported by elevated ambient concentrations of secondary organic
tracers (dicarboxylic acids, 2-methyltetrols, pinonic acid and pinic acid).
An approximate source profile was built for the aged fire plume to help
better understand evolution of wood smoke emission and for use in source
Citation: Yan, B., Zheng, M., Hu, Y. T., Lee, S., Kim, H. K., and Russell, A. G.: Organic composition of carbonaceous aerosols in an aged prescribed fire plume, Atmos. Chem. Phys., 8, 6381-6394, doi:10.5194/acp-8-6381-2008, 2008.