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

Abstract

Abstract. Volatile and intermediate-volatility non-methane organic gases (NMOGs) released from biomass burning were measured during laboratory-simulated wildfires by protontransfer-reaction time-of-flight mass spectrometry (PTRToF). We identified NMOG contributors to more than 150 PTR ion masses using gas chromatography (GC) preseparation with electron ionization, H 3 O + chemical ionization, and NO + chemical ionization, an extensive literature review, and time series correlation, providing higher certainty for ion identifications than has been previously available. Our interpretation of the PTR-ToF mass spectrum accounts for nearly 90 % of NMOG mass detected by PTR-ToF across all fuel types. The relative contributions of different NMOGs to individual exact ion masses are mostly similar across many fires and fuel types. The PTR-ToF measurements are compared to corresponding measurements from open-path Fourier transform infrared spectroscopy (OP-FTIR), broadband cavity-enhanced spectroscopy (ACES), and iodide ion chemical ionization mass spectrometry (I − CIMS) where possible. The majority of comparisons have slopes near 1 and values of the linear correlation coefficient, R 2 , of > 0.8, including compounds that are not frequently reported by PTR-MS such as ammonia, hydrogen cyanide (HCN), nitrous acid (HONO), and propene. The exceptions include methylglyoxal and compounds that are known to be difficult to measure with one or more of the deployed instruments. The fireintegrated emission ratios to CO and emission factors of NMOGs from 18 fuel types are provided. Finally, we provide an overview of the chemical characteristics of detected species. Non-aromatic oxygenated compounds are the most abundant. Furans and aromatics, while less abundant, comprise a large portion of the OH reactivity. The OH reactivity, its major contributors, and the volatility distribution of emissions can change considerably over the course of a fire.

Speciated and total emission factors of particulate organics from burning western U.S. wildland fuels and their dependence on combustion efficiency

“…In general, biomass burning, which includes wildfires, is the main global source of fine carbonaceous aerosol particles (~75%) in the atmosphere (Andreae and Merlet, 2001;Bond and Bergstrom, 2006;IPCC, 2014;Park et al, 2007). Individual and categorized organic emissions from wildfires have previously been 15 identified and quantified (Akagi et al, 2011;Andreae and Merlet, 2001;Hatch et al, 2015;Kim et al, 2013;Koss et al, 2018;Liu et al, 2017;Mazzoleni et al, 2007;Naeher et al, 2007;Oros et al, 2006;Oros and Simoneit, 2001a;Simoneit, 2002;Stockwell et al, 2015;Yokelson et al, 2013). The bulk of previous studies on speciated organic compound emissions focused on gas-phase volatile organic compounds (VOCs).…”

Primary emissions of glyoxal and methylglyoxal from laboratory measurements of open biomass burning

“…The PTR-ToF was used to measure VOCs with a proton affinity greater than that of water, including formaldehyde, 2,3-butanedione, 2,3-pentanedione, and several other carbonyl species, with a time resolution of 1 Hz (Yuan et al, 2016;Koss et al, 2018). For some species, such as formaldehyde and acetaldehyde, calibration factors were determined via the addition 25 of standards, but for other compounds such as 2,3-butanedione the calibration factors were calculated using the method of Sekimoto et al (2017).…”

“…8, and at these methylglyoxal concentrations the small features can be resolved, indicating that at least part of the signal attributed to methylglyoxal is indeed from that molecule. However, previous work has shown that the other substituted α-dicarbonyls are emitted from biomass burning in amounts comparable to the 25 methylglyoxal emissions we measured at the FSL (Gilman et al, 2015;Stockwell et al, 2015;Koss et al, 2018), and the contribution of these species to the measured extinction needs to be taken into account to properly retrieve the methylglyoxal concentrations.…”

“…Akagi et al, 2011;Stockwell et al, 2015;Koss et al, 2018). While methylglyoxal's absorption cross section is relatively weak and unstructured, the cross sections of glyoxal and formaldehyde in the visible and ultraviolet respectively are large and structured, enabling the detection of those two molecules from space using remote sensing instruments such as the Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY, Wittrock et al, 2006;Myriokefalitakis et al, 2008), the Global Ozone Monitoring Experiment-2 (GOME-2, Lerot et al, 2010), the Ozone Monitoring Instru-20 ment (OMI, Alvarado et al, 2014;Chan Miller et al, 2014) or the Tropospheric emissions: Monitoring pollution instrument (TEMPO, Zoogman et al, 2017).…”

“…, is due to 2,3-pentanedione) (Stockwell et al, 2015;Koss et al, 2018), so the only optical interference that we will consider is that from 2,3-butanedione.…”