In situ measurements and modeling of reactive trace gases in a small biomass burning plume

Abstract

Abstract. An instrumented NASA P-3B aircraft was used for airborne sampling of trace gases in a plume that had emanated from a small forest understory fire in Georgia, USA. The plume was sampled at its origin to derive emission factors and followed ∼ 13.6 km downwind to observe chemical changes during the first hour of atmospheric aging. The P-3B payload included a proton-transfer-reaction timeof-flight mass spectrometer (PTR-ToF-MS), which measured non-methane organic gases (NMOGs) at unprecedented spatiotemporal resolution (10 m spatial / 0.1 s temporal). Quantitative emission data are reported for CO 2 , CO, NO, NO 2 , HONO, NH 3 , and 16 NMOGs (formaldehyde, methanol, acetonitrile, propene, acetaldehyde, formic acid, acetone plus its isomer propanal, acetic acid plus its isomer glycolaldehyde, furan, isoprene plus isomeric pentadienes and cyclopentene, methyl vinyl ketone plus its isomers crotonaldehyde and methacrolein, methylglyoxal, hydroxy acetone plus its isomers methyl acetate and propionic acid, benzene, 2,3-butanedione, and 2-furfural) with molar emission ratios relative to CO larger than 1 ppbV ppmV −1 . Formaldehyde, acetaldehyde, 2-furfural, and methanol dominated NMOG emissions. No NMOGs with more than 10 carbon atoms were observed at mixing ratios larger than 50 pptV ppmV −1 CO. Downwind plume chemistry was investigated using the observations and a 0-D photochemical box model simulation. The model was run on a nearly explicit chemical mechanism (MCM v3.3) and initialized with measured emission data. Ozone formation during the first hour of atmospheric aging was well captured by the model, with carbonyls (formaldehyde, acetaldehyde, 2,3-butanedione, methylglyoxal, 2-furfural) in addition to CO and CH 4 being the main drivers of peroxy radical chemistry. The model also accurately reproduced the sequestration of NO x into peroxyacetyl nitrate (PAN) and the OH-initiated degradation of furan and 2-furfural at an average OH concentration of 7.45 ± 1.07 × 10 6 cm −3 in the plume. Formaldehyde, acetone/propanal, acetic acid/glycolaldehyde, and maleic acid/maleic anhydride (tentatively identified) were found to be the main NMOGs to increase during 1 h of atmospheric plume processing, with the model being unable to capture the observed increase. A mass balance analysis suggests that about 50 % of the aerosol mass formed in the downwind plume is organic in nature.

Open burning of rice, corn and wheat straws: primary emissions, photochemical aging, and secondary organic aerosol formation

“…The increase in tropospheric ozone (O 3 ) in aged biomass burning plumes could last for days and even months (Thompson et al, 2001;Duncan et al, 2003;Real et al, 2007) with complex atmospheric chemistry (Arnold et al, 2015;Müller et al, 2016). Moreover, biomass and biofuel burning could contribute up to 70 % of the global secondary organic aerosol (SOA) burden (Shrivastava et al, 2015) and hence influence the seasonal variation of global SOA (Tsigaridis et al, 2014).…”

Non-methane organic gas emissions from biomass burning: identification, quantification, and emission factors from PTR-ToF during the FIREX 2016 laboratory experiment

“…Several recent papers have reported the use of highresolution PTR-ToF to measure biomass burning NMOGs in the laboratory Bruns et al, 2017) and the environment (Brilli et al, 2014;Müller et al, 2016). Hatch et al (2017) suggest that PTR-ToF measures a substantial fraction (50-80 %) of total NMOG carbon mass.…”

“…R. Koss et al: Non-methane organic gas emissions contribute to the formation of secondary pollutants including ozone and secondary organic aerosol (SOA; Alvarado et al, 2009Alvarado et al, , 2015Yokelson et al, 2009;Jaffe and Wigder, 2012). Because NMOGs from biomass burning are a complex mixture of many species that can change considerably depending on fuel and fire characteristics, many modeling and inventory efforts have had difficulty capturing subsequent chemistry in fire plumes (Alvarado et al, 2009;Grieshop et al, 2009;Wiedinmyer et al, 2011;Heald et al, 2011;Müller et al, 2016;Reddington et al, 2016;Shrivastava et al, 2017). Additionally, a substantial portion of gas-phase carbon may be missing from many field measurements (Warneke et al, 2011;Yokelson et al, 2013;Hatch et al, 2017) and the gas-phase precursors of SOA are not sufficiently understood (Jathar et al, 2014;Alvarado et al, 2015;Hatch et al, 2017).…”

Aerosol optical properties and trace gas emissions by PAX and OP-FTIR for laboratory-simulated western US wildfires during FIREX

“…Many of these EFs are critically important to represent wildfire emissions well: e.g. NH 3 (Benedict et al, 2017) and SOA or PAN precursors (Alvarado et al, 2015;Müller et al, 2016 factorization was found to be a very useful method to predict field EF from the lab data for NMOG as discussed elsewhere (Sekimoto et al, in preparation). Finally, given the small amount of field sampling, more field work is clearly needed.…”

“…To date, most of the research on the emissions and evolution of smoke from US fires has targeted prescribed fires (Burling et al, 2011;Akagi et al, 2013;May et al, 2014;Müller et al, 2016). However, wildfires burn a different mix of fuels in a different season that has more intense photochemistry and different smoke dispersion scenarios, and they typically consume more fuel per unit area than prescribed fires and can have different emission factors (EF, g compound 15 emitted/kg fuel burned ) (Campbell et al, 2007;Urbanski, 2013).…”