Diagnosis of Aged Prescribed Burning Plumes Impacting an Urban Area

Abstract

An unanticipated wind shift led to the advection of plumes from two prescribed burning sites that impacted Atlanta, GA, producing a heavy smoke event late in the afternoon on February 28, 2007. Observed PM2.5 concentrations increased to over 140 microg/m3 and O3 concentrations up to 30 ppb in a couple of hours, despite the late hour in February when photochemistry is less vigorous. A detailed investigation of PM2.5 chemical composition and source apportionment analysis showed that the increase in PM2.5 mass was driven mainly by organic carbon (OC). However, both results from source apportionment and an observed nonlinear relationship between OC and PM2.5 potassium (K) indicate that the increased OC was not due solely to primary emissions. Most of the OC was water-soluble organic carbon (WSOC) and was dominated by hydrophobic compounds. The data are consistent with large enhancements in isoprenoid (isoprene and monoterpenes) and other volatile organic compounds emitted from prescribed burning that led to both significant O3 and secondary organic aerosol (SOA) production. Formation of oligomers from oxidation products of isoprenoid compounds or condensation of volatile organic compounds (VOCs) with multiple functional groups emitted during prescribed burning appears to be a major component of the secondary organic contributor of the SOA. The results from this study imply that enhanced emissions due to the fire itself and elevated temperature in the burning region should be considered in air quality models (e.g., receptor and emission-based models) to assess impacts of prescribed burning emissions on ambient air quality.

Observations and impacts of transported Canadian wildfire smoke on ozone and aerosol air quality in the Maryland region on June 9–12, 2015

“…Isoprene has been identified as a leading VOC in Maryland O 3 production (Halliday et al, 2015) and is primarily related to biosphere releases due to atmospheric heat stress (Seinfeld and Pandis, 1998) but can also be caused by heat from fires (Simpson et al, 2011;Lee et al, 2008). Isoprene showed a significant increase on June 11 compared to adjacent days and other VOC species during ozone production hours (Table 2) and Note.…”

Particulate matter, air quality and climate: lessons learned and future needs

“…The aging of emissions from open biomass combustion yielded OA enhancement ratios ranging from 0.7 to 2.9, depending on fuel type and burn conditions Ortega et al, 2013). Ambient estimates of aging-induced OA enhancement in wildfire plumes include no detectable enhancement (Akagi et al, 2012;Capes et al, 2008;Cubison et al, 2011;Hecobian et al, 2011;Jolleys et al, 2012), enhancements of 20-50 % Reid et al, 1998) and increases of a factor of 2 or more (Lee et al, 2008;Yokelson et al, 2009). Explanations for these differences include fuel type and burn conditions but also the evaporation of primary emissions following dilution (Robinson et al, 2007) and the gas-phase oxidation of repartitioning semivolatile species (Donahue et al, 2012a).…”

Aged boreal biomass-burning aerosol size distributions from BORTAS 2011

“…Coagulation is a driving factor in size-distribution evolution due to the high concentrations of particles within plumes (Andreae and Merlet, 2001;Capes et al, 2008). Production of secondary organic aerosol (SOA) in-plume has been observed in chamber studies Grieshop et al, 2009;Hennigan et al, 2011;Heringa et al, 2011;Ortega et al, 2013) and in the field (DeCarlo et al, 2010;Lee et al, 2008;Reid et al, 1998;Yokelson et al, 2009), and this SOA will condense onto the particles, increasing their size. In addition, the primary organic aerosol (POA) emitted by the fires may evaporate during the dilution of the plume (Huffman et al, 2009;May et al, 2013).…”