Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , 1,2 , C. Warneke , and 1,2,a 3,b , P. D. Goldan , I. R. Burling 1,2,a 1,2 21714 21713 , W. C. Kuster , J. A. de Gouw 1,2 2 , B. M. Lerner 3 , J. M. Roberts 1,2 1,2 This discussion paper is/has beenand under Physics review (ACP). for Please the refer journal to Atmospheric the Chemistry corresponding final paper in ACP if available. CIRES at University of Colorado,NOAA Boulder, CO, Earth USA System Research Laboratory,Department Boulder, CO, of USA Chemistry, University ofnow Montana, retired Missoula, Montana, USA now at: Cytec Canada, Niagara Falls, Ontario, Canada P. R. Veres R. J. Yokelson 1 2 3 a b Received: 2 July 2015 – Accepted: 28Correspondence July to: 2015 J. – B. Published: Gilman 12 ([email protected]) August 2015 Published by Copernicus Publications on behalf of the European Geosciences Union. Biomass burning emissions and potential air quality impacts of volatilecompounds organic and other trace gasestemperate from fuels common in theStates United J. B. Gilman Atmos. Chem. Phys. Discuss., 15, 21713–21763,www.atmos-chem-phys-discuss.net/15/21713/2015/ 2015 doi:10.5194/acpd-15-21713-2015 © Author(s) 2015. CC Attribution 3.0 License. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | e and ), and ff • NO is the principal emissions; however, ), alkoxy (RO + • x • 2 O); carcinogens such as 2 0.07 % of emissions by mass , and NO ) and reactive volatile organic ± 4 2 NO + erent biomass fuel types common in the , CO, CH ff NO ect both climate and air quality (Ja 2 ff = x 21716 21715 ected Boulder, Colorado in September 2010 al- ), and nitrous oxide (N ff 4 16) % to OH reactivity and were the only measured gas- produced from the reaction of RO ± ), a hazardous air pollutant, and secondary organic aerosol 2 erent chemical ionization-mass spectrometers. These mea- 3 ff by OH leads to the formation of alkyl (R and/or SOA formation. 4 ), methane (CH , aldehydes, hydroperoxides, or nitrous acid (HONO). OH is a key 3 2 may be formed in the atmosphere from the interactions of VOCs, 3 ) radicals, where R represents a carbon-containing derivative. These 3 erent US fuel regions presented here. VOCs contributed less than • ff 2 . Photolysis of NO 0.12 % of emissions by mole and less than 0.95 2 ± , and a radical source such as the hydroxyl radical (OH), which is formed from x Tropospheric O alkylperoxy (RO radicals are important, but short-lived,to intermediaries NO that aid in the conversion of NO compounds (VOCs, also known as non-methaneof organic compounds) biomass from may combustion degrade localof and tropospheric regional ozone air (O quality(SOA) by (Alvarado the et photochemical formation al.,burning 2015). emissions This of work organic and ismay contribute inorganic aimed to gases at O in characterizing order primary to identify biomass key speciesNO that the photolysis of O oxidant in the tropospherelifetimes and of it reactive organic plays andsuch a inorganic as pivotal gases. role CO Oxidation in and of determining VOCs CH and the other atmospheric gases formaldehyde and benzene; and otherparticulate components harmful matter, to carbon human monoxideAndreae, health 1990; (CO) including Hegg et and al., isocyanic 1990;2009; Andreae acid and Estrellan Merlet, (HNCO) and 2001; (Crutzen DemirbasThe Iino, and and Demirbas, 2010; co-emission Roberts of nitrogen et oxides al., (NO 2010, 2011; Sommers et al., 2014). Wigder, 2012; Sommers etcarbon al., dioxide 2014). (CO Emissions include greenhouse gases such as sources (i.e., urban and biogenic emissions)including and benzofuran, identify 2-furaldehyde, several promising 2-methylfuran, BB furan, markers and benzonitrile. 1 Introduction Biomass burning (BB) emissionsparticles that are may composed directly and/or of indirectly a a complex mixture of gases and Abstract A comprehensive suite of instrumentsorganic was gases, including used methane to and quantifyganic volatile the gases organic emissions from compounds 56 of (VOCs), laboratory and over burns 9 200 of inor- 18 di southeastern, southwestern, orspectrometer northern (GC-MS) United provided extensive States. chemicallected A detail during gas of a discrete chromatograph-mass laboratory air burnorganic samples and and col- was inorganic complemented by specieseter real-time via measurements (OP-FTIR) an of and open-path 3 Fourier di transform infrared spectrom- 0.78 surements were conducted inFire February Sciences 2009 Laboratory at in thesition Missoula, U.S. of Montana. Department the The of gasesgeographic relative Agriculture’s emitted fuel magnitude varied regions and by being compo- individual(CO) simulated. were fuel Emission used ratios type relative to and,with to characterize more the carbon the broadly, hydroxyl monoxide composition by radical, of the OH;sors gases 3 and for emitted potential the by secondary 3 mass; organic reactivity di aerosol (SOA) precur- (on average) due to the predominance of CO VOCs contributed 70–90 ( emissions by mole were unsaturatedaromatics compounds including and highly photolabile reactive oxygenated alkenes VOCs and contributed (OVOCs) such 57–68 as % formaldehyde. of OVOCs aromatic-OVOCs the such VOC as mass benzenediols,nant emitted, phenols, potential 42–57 and % SOA benzaldehyde of precursors.from were VOC-OH the In the reactivity, Fourmile addition, domi- and Canyon ambient Fire that air a measurements of emissions phase source of SOA precursors from combustion of biomass. Over 82 % of the VOC lowed us to investigate biomass burning (BB) emissions in the presence of other VOC 5 5 25 15 20 10 10 15 25 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 2 NO from 2 + ciently • ffi 2 , peroxyni- 3 ) to a double bond cient partitioning to 3 ffi cient SOA precursors ffi formed is dependent on the 3 radicals formed from hydrogen • precursors); however, these species formation pathway involves the forma- 3 3 e and Wigder, 2012). and/or RO ff formation in fresh BB plumes due to the initial • 21718 21717 2 , or the nitrate radical (NO 3 downwind formation via production of NO 3 3 formation from the combustion of biomass (Akagi et al., 3 and VOCs (Carter, 1994). Biomass burning is a large, pri- , and HONO (i.e., O ; however, the amount of O x x 3 , but enhance O 2 cult to predict O ffi e and Wigder, 2012). An additional O ff In order to merge and compare datasets from multiple instruments, we report mean For this study, a comprehensive suite of gas-phase measurement techniques was SOA is organic particulate mass that is formed in the atmosphere from the chemi- Advances in instrumentation and complementary measurement approaches have southeastern, and northern fuelERs regions. for Previous publications the present real-time2011), fire-integrated fuel-based measurement emissions techniques factors (Verescomparisons (Burling et between et al., laboratory al., 2010; 2010; and Warneke Yokelson field et et al., measurements al., 2013), of and BB emissions (Burling discrete emission ratios (ER) of the measured gases relative to CO for southwestern, the potential atmospheric impactsfires sampled of by a these gas gaseous chromatograph-masssampling spectrometer a emissions. (GC-MS), relatively which We short, is discrete focus limited segmenting to of on mixing a the laboratory ratios burn. measured 56 We by beginand the by proton-transfer-reaction GC-MS compar- mass to spectrometry, both those of measured whichsampling by provide infrared of near-continuous spectroscopy laboratory fires.representing We the then entirety compare of discretepotential emissions ERs bias from that and a resulted laboratory fire-integrated from burn, ERs, discrete in vs. order “continuous” sampling to techniques. quantify any used to quantify theand emissions 9 of inorganic 200 gasesgraphic organic regions from gases, in laboratory including the methane biomass US (hereafter and burns referred VOCs, of to 18 as “fuel fuel regions”) types in from order 3 to examine geo- trates, and organic aerosol (Trentmann etand al., Prinn, 2003, 2005; 2009; Mason Heilman etessential et al., to 2006; al., Alvarado understanding 2014; impacts Urbanski, on 2014; chemistry, Alvarado clouds, et climate, and al., air 2015) quality. and are tion may occur via addition of OH,abstraction O of the parent compound.that These contain polar pathways functional may groups result suchcarboxylic in as acids oxidation ketones, that products aldehydes, can alcohols, have nitrates, vaporthan and pressures their approximately parent 10 compounds to (Pankow, 10 1994) 000 times allowing lower for more e cal evolution of primary emissionsto of a organic complex species. series Here,the of formation chemical of reactions evolution relatively refers of lowreadily a volatility and/or partition large high to, number solubility or oxidation of products remain organic that in, species will the that particle results phase in (Kroll and Seinfeld, 2008). Oxida- sequestration of NO biomass burning experimentsSchauer (Yokelson et et al., al., 1996,Stockwell 2001; et 2013; Christian al., McDonald et 2015).surements et al., of This BB al., 2003; emissions information 2000; reported Veres supplements inet et the several al., literature al., decades (Andreae 2001; and 2010; of Akagi Merlet,tative et Hatch 2001; field Friedli measurements al., mea- et 2011; of al., Simpson VOCscritical et 2015; input and al., to other 2011). photochemical trace Chemically transportwind models detailed, gases changes aimed represen- in from at the reproducing biomass concentrations observed combustion of down- reactive are species including VOCs, O reaction. This pathway may diminish O thermal dissociation of peroxynitrates (Ja or result from the reactions of the RO the particulate phase. Thus, VOCs that are considered to be e are emitted at varyingmaking relative it ratios di depending on2011; Ja the fuel typetion and of burn peroxynitrates, such conditions as peroxyacetic nitric anhydride (PAN), via R(O)O relative abundances of NO mary source of VOCs, NO are relatively reactive organic compoundslow volatility whose and/or oxidation higher products solubility than aresions the of parent is su VOC. highly SOA formation variable from andlarge BB chemical emis- source modeling of results SOA” suggestsuch precursors that as there that toluene is cannot (Alvarado a be et “missing al., explained 2015). by known SOAenabled precursors chemical analyses of a wide range of species emitted during laboratory-based source of tropospheric O 5 5 25 20 15 10 20 10 15 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | × 12.5m × ected Boulder, ff 5 to 17 s depend- ∼ formation, and utilize 3 21720 21719 and/or SOA. We compare the chemical composition 3 and SOA formation pathways, which is out of the scope of this study. In 3 erent fuels studied. These fuels are categorized into 3 geographic fuel ff All biomass burns were conducted inside the large burn chamber (12.5m 20 m height), whichhaust contains stack, a and an fuel elevated sampling bedmately platform 17 under m surrounding above the an the exhaust fuel emissions-entraining stackfuel bed approxi- hood, sample (Christian et was an al., arranged ex- 2003, onentation 2004; the and Burling fuel et fuel al., bed loading 2010). in(Burling when Each a et possible manner al., and that 2010). was mimicked Duringoutside ignited their each air natural using fire, conditioned the ori- a burn to smallair chamber a propane was inside similar torch slightly the temperature pressurized with burn andconditioned ambient relative chamber. air humidity The and as subsequent continuouslyThe the vented residence emissions through ambient time were the of top entrained emissions of in by the the the exhaust exhaust stack stack. pre- ranged from 9 southwestern fuels frommesquite, southern and California oak and savanna/woodland; Arizonavanna/shrub 6 including complexes southeastern indigenous chaparral to fuels shrub, coastal represented Northgia; the Carolina and and pine 3 pine sa- litter northern frompine fuels Geor- needles including from an Montana. Englemann AllFire spruce, fuels Sciences a were Laboratory grand harvested fir, inexperiments. where and January they ponderosa 2009 were and sent stored to in the a walk-in cooler prior to these transfer-reaction ion-trap masschemical-ionization spectrometer mass (PIT-MS), spectrometer negative-ion (NI-PT-CIMS), proton-transfer and open-path Fourier trans- 2.2 Instrumentation and sampling A list of theherent gas-phase sampling instruments limitations, usedgraph and in mass references this spectrometer appears (GC-MS) study, and a inter the (PTR-MS) brief Table proton-transfer-reaction were 1. description mass located spectrome- The of in their gas a in- laboratory chromato- adjacent to the burn chamber. The proton- Colorado in September 2010. The latterspecific measurements to revealed the BB markers BB that emissions,sources, were minimally and influenced by were urban emitted oruseful biogenic even in in VOC detectable emission aged, transported quantities BB with plumes. long enough lifetimes to2 be Experimental 2.1 Fuel and biomass burn descriptions The laboratory-based measurementsary 2009 of at the BB U.S. DepartmentMontana. of emissions A Agriculture’s detailed Fire were list Sciencesand Laboratory of conducted in the the Missoula, biomass in carbon fuel andvious Febru- types, nitrogen paper species content by names, of Burling fuelof et the source al. the origin, fuels (2010). studied 18 Up here di regions to are 5 based included replicate on in burns where a were the conducted pre- for fuels each were collected. The data presented here include ing on the flow/ventnatural rate. extinction. Each burn lasted approximately 20–40 min from ignition to et al., 2010, 2011;an Yokelson et improved al., set 2013). of emission Yokelsonbut et factors al. for they prescribed (2013) performed fires focused only byprovides on coupling retrieving a a lab more cursory and field detailed analysisfrom work, fires examination of simulating of the each theair atmospheric fuel chemical quality region impacts. through composition in formation This order of ofof paper O to BB the identify emissions mass key species emitted,in that the order may reactivities to impact of identify the the measured key gases reactive species with that the may hydroxyl lead radical to O addition to the laboratory fire measurements,reported we VOCs present in field-measurements of ambient rarely- air during the Fourmile Canyon Fire that a a model-derived metric to compareeach relative fuel SOA region. potentials Detailed (Derwent chemical et modelsthe al., are various required 2010) O to from more accurately account for 5 5 10 15 25 15 20 20 25 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 1 − erent ff /KCl PLOT column 3 O 2 ort to best characterize ff ), butenyne (vinyl acetylene, 2 H 4 uent to a linear quadrupole mass , which could lead to dry ice form- 2 ffl 21721 21722 ciencies of high-volatility VOCs (channel 1) or ffi ort to reduce the amount of particles pulled into the ff was continuously sub-sampled from the high volume ’s. The majority of the samples were analyzed in selec- ) from 25 to 150 atomic mass units; or in selective ion 1 − m/z m/z in order to reduce any potential interferences from co-eluting erent stages of replicate burns in an e ff m/z and water in each sample (Goldan et al., 2004; Gilman et al., 2010). 2 ) sample stream for 20 to 300 s resulting in sample volumes from 23–350 mL 1 − , CO may not have been scanned in selective ion mode. The entire GC-MS sampling 3 Sampling inlets for the four mass spectrometers were located on a bulkhead plate The open optical path of the OP-FTIR spanned the full width of the exhaust stack Each VOC was identified by its retention time and quantified by the integrated peak 4-port valve that sequentially directed the column e the emissions of each fuel type. area of a distinctive compounds. Identities of newthis GC-MS compounds were that confirmed had bymass (1) never spectrum matching when before the operated been associated inand measured electron total Technology’s mass impact ion spectral by database, ionization mode and to (2)times the comparing and National their respective boiling Institute retention of pointsExamples Standards to of a these list species of include: compounds 1,3-butadiyne previously (C measured by the GC-MS. inlet residence times andFTIR to instrument a PTR-MS response with times.at a the moveable Previous inlet height confirmed comparisons of the the ofartifacts, stack sampling such emissions OP- platform as are (Christian losses well-mixed to etand the al., walls in-situ 2004). of Other instrument the possible inlets, comparisons sampling et were (Burling al., investigated via 2010; et laboratory Warneke al., tests et 2010; al., 2011). Roberts et2.3 al., 2010; Veres Discrete sampling by in-situ GC-MS A custom-built, dual-channel GC-MS was usedof to VOCs. identify For and each quantify biomass an burn,for extensive each the set channel, GC-MS and simultaneously analyzed collected them 2 in samples, series one using either an Al VOCs of lesser volatility and/or higherof polarity (channel O 2) while minimizingFor the amount each channel, 70 mLmin(7 Lmin each. Smaller sample volumescombustion were in often order collected to during avoid trapping periods excessive of CO intense flaming spectrometer (Agilent 5973N).to The maximize sample the traps cryogenic for trapping e each channel were configured sample line. A sample pump continuously flushed the 25 m sample line with 7 Lmin so that the emissionsAll could measurements be were measured time instantaneously aligned without with the the OP-FTIR use in of order an to inlet. account for di (channel 1) or a semi-polar DB-624 capillary column (channel 2) plumbed to a heated ing in the sample trap,for thereby restricting detection sample of flow. Larger traceoverloaded. sample species, The volumes allowed but mass peak spectrometerall was resolution mass-to-charge operated would ratios in degrade ( eithermode, if scanning total the a ion subset column of mode, was tive scanning ion mode for improvedtype signal-to-noise; was however, analyzed at in leastm/z total one ion sample of mode each toand analysis fuel aid cycle identification required 30 and min;laboratory therefore, quantify burn the species GC-MS only was whose once limited perples to were fire sampling collected each for at burns di that lasted less than 30 min. GC-MS sam- on the side ofshared the a exhaust stack common 17roalkoxy m inlet, Teflon above tubing which the (Warneke consisted fuelexhaust et bed. of stack al., (40 The 20 cm) 2011). m GC-MS was Theextended sheathed and of portion by 30 PTR-MS cm unheated a of from stainless 3.97 the mm steelfrom the i.d. inlet tube the wall perfluo- line (40 fuel cm, of inside 6.4 bed the mm the i.d.) below) exhaust that in stack an and e was pointing upwards (away form infrared (OP-FTIR) opticalinside the spectrometer burn were chamber. located on the elevated platform flow of stack airboth reducing the the inlet PIT-MS residence andlengths time NI-PT-CIMS further to were reducing less of inlet thanNI-PT-CIMS (Roberts similar residence 3 et s. times materials al., Separate and and 2010; inlets allowing Veres design, for et for al., sample but 2010). dilution shorter for the 5 5 25 20 20 25 10 15 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ), 2 (1) N 6 , were H 4 X , are equal ). For some 2 CO for a rela- bknd O ∆ 3 or CO, respectively, 91, and elute within X and CO m/z relative to bknd X CO over the entirety of a fire X ), methyl pyrazole (C ∆ 2 ∆ 1.21 ppbv) compared to a mean X/ NO = ∆ 3 21723 21724 t 42 ppbv) in the fires. The large standard deviation t )d = 0.33 ppbv (median )d ± bknd bknd CO X ONO), nitromethane (CH − − 3 ), and tricarbon dioxide (carbon suboxide, C 2 fire fire N X ( 8 H (CO end start 6 CO are the excess mixing ratios of compound t t R 460 ppbv (median end start ∆ t t R ± = and X X CO ∆ ∆ ∆ 1000 s) (Burling et al., 2010; Veres et al., 2010; Warneke et al., 2011) as well ), methylnitrite (CH 4 = ≥ H The type of emission ratio, discrete or fire-integrated, is determined by the sampling Of the 187 gases quantified by the GC-MS in this study, 95 were individually cal- t 4 calculated as follows: ER 2.4 Calculation of emission ratios Emission ratios (ER) to carbon monoxide (CO) for each gas-phase compound, where during a fire above the background. Background values, to the average mixingexhaust ratio stack of a in species thePT-CIMS, backgrounds in absence were the determined of pre-conditioned from a ambientinside the fire. air the mean inside For responses exhaust the the ofleast stack the OP-FTIR, one for ambient PTR-MS, background air a PIT-MS sample minimumtion and was and of NI- average collected mixing 60 for s ratiosthe the of prior VOCs GC-MS course in to each the of the stack day.observed the backgrounds The ignition during were campaign composi- of consistent biomass over and each burns.sured were For fire. by generally example, the At the GC-MS much was average lower 1.22 background than ethyne mea- the mixing ratios C ethyne of 150 species, we were able toand identify common the chemical chemical familythese (defined moiety) cases, by but we its present not molecular the formula ticular the emissions chemical as exact family a chemical (see sumthe Table structure of 2). limits the or We of unidentified report identity. isomers detection onlyformula for For for could the a the be par- compounds majority identified. that of were the above biomass burnsibrated and where with the commercially molecular availablepressed gas and/or calibration custom-made standards. gravimetrically-basedcompound The com- limit dependent, of but detection, arerespectively precision, (Gilman conservatively and et accuracy better al., are than 2009,was 2010). 0.010 not ppbv, For available, compounds 15, the whereof calibration and a compounds factors 25 calibration in %, were standard a estimated similarsible using chemical a measured family similar with calibrations mass aaccuracy similar fragmentation retention of pattern. time, un-calibrated In and species, order when wexylene, to pos- and use estimate the measured the sum calibrations of uncertainty ofsimilar m- in ethyl mass and benzene, the fragmentation p-xylenes o- patterns, as1 a are min test all of case. quantified These each using aromatic otherwas species used signifying have for similar all physical theseby properties. isomers, up then If to the a reported 34 %. singlespecies mixing We as calibration ratios therefore 50 could factor %. conservatively be estimate miscalculated the accuracy of all un-calibrated measuring discrete ERs, whichtively represent short the portion average of aOP-FTIR, fire PTR-MS, corresponding and to NI-PT-CIMS the areery GC-MS fast-response 1 sample instruments to acquisition 10 that time. scalculate sampled The over both ev- the fire-integrated entire ERs duration that represent of to each fire. These measurements were used to frequency of the instrument and sampling duration. The GC-MS is only capable of for ethyne in the biomassthan burns uncertainty reflects in the the large measurement. variability in ethyne emissions rather ethyl pyrazine (C (d 5 5 10 15 10 15 20 20 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 2 erent , were ff ciency, r ) mixed ffi Cercocar- emissions 2 cients, emissions and for VOCs mea- 20 to 300 s) as emissions. The ffi x 2 = X t ∆ Pinus ponderosa and NO 2 ), mountain mahogany ( ) periodically brought biomass burn- 1 , measured by the fast-response in- − X ∆ 3.5 ms communis 21726 21725 = ) and ponderosa pine ( and (mean 1 − ) indicative of vigorous flaming combustion. This tran- ], which is a proxy for the relative amounts of flaming 2 2 ). 1 − NO 0.99 signifying good overall agreement between the di CO + + ∆ < r < (NO CO x ∆ Pseudotsuga menziesii [ / Juniperius scopulorum 2 measured by the PTR-MS. The slopes and correlation coe CO and NO 2 m/z 0.2 and 0.93 = ∆ ), and various shrubs and grasses common to the mountain zone of the Colorado ± In order to compare measurements from multiple instruments, we calculated the 2 s) attached to an exterior port on the western side of the building. CO was mea- MCE and smoldering combustion (Yokelsonof et the al., fire, 1996). theMCE During MCE gradually decreases approaches the during smoldering unity initial combustionprominent. due when flaming CO to emissions phase are the more dominance of CO average excess mixing ratiosstruments over of the a corresponding GC-MS species, burns. sample We acquisition compare times the forsured measurements all by 56 using the biomass correlation GC-MS plots vs.gous the of same compound measureddetermined by the by OP-FTIR linear orFig. an orthogonal 2a. analo- distance The regression average1.0 slope analysis and and standard are deviation compiled of the in instrument comparison is 3 Results and discussion 3.1 Calculation of emission ratios Temporal profiles of laboratorybustion biomass chemistry burns and provide processes that valuableson lead insight et to into the al., the emissionsillustrate 1996). com- of (i) Figure various flaming, species 1 mixed, (Yokel- andsampling shows smoldering temporal frequencies combustion phases/processes profiles and andpared of temporal (ii) to an the overlap the example of GC-MS.in burn Upon the CO in ignition, fast-response order there instruments to is com- an immediate and substantial increase sitions to a mixed-phase characterized by diminishing CO a second increase inperiod CO. The of fire mostly eventually smolderingFigure evolves combustion to 1 (Yokelson a et weakly-emitting, also al., protracted 1996; includes Burling the et temporal al., 2010). profile of the modified combustion e as discrete ERs coincident with the GC-MS sample acquisition (d from 7–9 September 2010. Over the course of the Fourmile Fire, approximately 25 km 2.5 Fourmile Canyon Fire in Boulder,Ambient Colorado air measurements ofFire biomass that burning occurred emissions from in the the Fourmile foothills Canyon 10 km west of Boulder, Colorado were conducted discussed in Sect. 2.3. WeCO reference are all ERs co-emitted to by COoccur smoldering because mostly combustion the from during majority flaming of the (seeported VOCs fire Sect. and in whereas 3.1). the CO Additionally, literature ratios forpresented to biomass here CO burning are are and in commonly urban unitsratio re- VOC of (mmolVOC(molCO) emission ppbv sources. VOC All per data ppmv CO, which is equivalent to a molar of land includingof 168 Douglas-fir structures ( burned. The burned vegetation consisted primarily Front Range (Grahamwinds et ranging from al., 1 2012). to 12 ms During the measurement period, down-sloping with juniper ( pus ing emissions to NOAA’s Earthedge of Systems the Research city Laboratory ofthe Boulder. located The laboratory at previously and described the in-situ sampled western GC-MS< outside was air housed inside via asured 15 via m a Teflon sample co-located1999). line vacuum-UV (residence resonance fluorescence time instrument (Gerbig et al., 5 5 15 20 25 10 10 15 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | times cor- end t 69 has the low- set is more likely 0.2 indicating that ff and ect the comparison ± ff m/z start t 69 response of the PTR-MS. 1000 s in Fig. 1) when absolute ≥ t m/z ) has also been shown to contribute to 2 furan) vs. PTR-MS O 3 69 response of the PTR-MS in fresh smoke + , of discrete vs. fire-integrated ERs for select r 21728 21727 erent measurement strategies, discrete vs. fire- m/z ff cient of 0.99 suggests that the o cients, 0.64) indicating the contribution of other VOCs, e.g. ffi ect the comparison. ffi (isoprene ff = Σ erence that remains unresolved. The possibility of a species with ff 1.36) indicating that the GC-MS response is greater than the OP- erence between the GC-MS and the OP-FTIR observations was for ff = 0.77) indicating that the GC-MS may be biased low for furan or that the OP- 1001 s to extinction). For VOCs emitted during the later stages of a fire (e.g., = = 69 response for the PTR-MS technique (Stockwell et al., 2015). Direct compar- The slopes and correlation coe Comparison of the GC-MS The largest di 1,3-benzenediol), the discrete ERsCO. will For likely example, underestimate the the discrete emissions ERs relative for to benzenediol for the southeastern and south- emissions and ERs are lower95 for % most of species. the Using emissions the ofmean data benzene ER in (in during Fig. ppbv) this 1 occur time as is between(time an twice ignition example, as and large 1000 as s, the and mean the ER in the later portion of the fire the discrete ERs are generallyThis higher than positive the bias fire-integrated is ERscluded a by samples 20 consequence % collected of on at average. the the end GC-MS of sampling a burn strategy (e.g., which rarely in- VOCs are summarized in Fig.onal 2b. distance These regression values analysis were of calculatedas correlation shown using plots in of a Fig. discrete linear 3. vs. orthog- The fire-integrated average ERs slope and standard deviation is 1.2 respond to the GC-MS samplefire-integrated acquisition. The ERs discrete measured ERs by aremeasurement the then artifacts compared same will to fast-response not the instrument a so that potential m/z isons of the real-time measurementsGC-MS for a (e.g., variety formaldehyde, of formic other acid, specieset and not al., HONO) measured 2010; can by Veres be the et found al., elsewhere 2010; (Burling Warneke et al., 2011). 3.2 Comparison of discrete and fire-integratedFire-integrated ERs ERs represent emissions fromburn whereas all discrete combustion ERs processes capture ofcombustion a relatively processes a brief during biomass snapshot a of particularries emissions from sampling of mixed period. VOC Figure tolect 1 CO gases. includes Here ERs time we se- measured compareintegrated, by the in 2 the order di real-time to measurementbe (i) biased techniques determine by if for the the se- sampleof discrete acquisition a ERs laboratory times measured burn which when by typicallyhow emissions the occurred well for within GC-MS most the the may gases discrete first-half generallyemissions GC-MS “peaked” relative and samples to (ii) are assess CO. able WePTR-MS to for do capture each this of the by the fire-to-fire determining 56 variability biomass discrete burns of ERs using for Eq. the (1) where OP-FTIR or est slope (GC-MS vs.cis- PTR-MS and trans-1,3-pentadienes, to the from a calibration di the same retentionco-emitted time at and a consistent similarbe ratio fragmentation completely relative ruled pattern to out.(slope propene as For seems propene furan, highly the that unlikely,FTIR GC-MS but is may had cannot also have a spectral lowerprofiles interferences of response that these than bias measurements shown OP-FTIR the inference measurement Fig. with high. 1 the suggest The OP-FTIR that temporal measurement therein was of the a furan spectral flaming as inter- phase evidencedThese by that early the was “spurious” large not OP-FTIR emissions capturedfor furan by responses the the would GC-MS (i) samples onlybeen a observed collected in in other the biomasset burning flaming al., experiments 2004; phase utilizing Stockwell of this et OP-FTIR al., the (Christian 2014). fires and (ii) have not (Warneke et al., 2011). Carbon suboxide (C propene (slope FTIR; however, a correlation coe measurement techniques for thediscussed in species more detail investigated below. here. A few comparisons are 5 5 25 20 15 25 10 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 3 erent for ff erences in ff , between the discrete and 0.88) do not show a strong r r > 2, where C, N, and H denote the number / 2] + 21730 21729 H − N + [2C = D each of the 3each geographic fuel fuel region. regions, i.e., the distribution of ERs are unique to i. ERs are highly variable and span more than 4 orders of magnitude. ii. The relative magnitude and composition of the gases emitted are di Figure 4 is a pictograph of all ERs presented in Table 2 as well as a histogram of the In summary, the discrete GC-MS samples best characterize the fire-integrated emis- The ability of the GC-MS to capture the fire-to-fire variability in VOC emissions rela- the magnitudes and generaldistribution chemical composition of of ERs each aredegree simulated of fuel shown unsaturation region. as ( The aof function carbon, nitrogen, of and threeand hydrogen simple atoms, molecular respectively); properties the weight including numberVOCs (MW) the of will of oxygen depend, atoms; in individual part,reactivity VOCs. on (D), Atmospheric these solubility properties, lifetimes (O-atoms), whichwe and and highlight we several volatility use fates key (MW). features as that of simplified Usingsections: will proxies this be for explored general in framework, further detail in the subsequent ERs for each of the 3 fuel regions in order to highlight commonalities and di 3.3 Characterization of laboratory BB emissions In order to mergeof datasets over 200 from organic multipleative gases, instruments, to including we CO methane for report and theStates mean VOCs, southwestern, (Table discrete and southeastern, 2). 9 ERs and Mean inorganichttp://www.esrl.noaa.gov/csd/groups/csd7/measurements/2009firelab/. northern ERs gases This fuel for rel- study types each uti- inlizes of the discrete United ERs the to 18 characterize thethe individual chemical VOC-OH fuel composition of reactivity, types the and molar aresimulating the mass each available emitted, fuel SOA at region potential in ofemissions order and to the compare identify measured potential key atmospheric species emissionsand/or impacts that from SOA. of may these fires impact air quality through formation of O integrated ERs forreached the by majority comparing of discreteYokelson the ERs et measured al. species (2013). during measured. While theemissions, A fire-integrated these same ERs analyses similar fire are suggest to conclusion that consideredat each collecting to was various and other best stages averaging by represent multiple of discrete BB thesubstitute ERs same when or fire-integrated replicate burns,commonly ERs as used cannot presented to here, be determine aretaken fuel-based determined. an converting emission adequate discrete Fire-integrated factors ERs ERs for intoYokelson et a are emission al. fire, factors, (2013). as but also care discussed must for be this data in sions and fire-to firetion. variability We of conservatively species estimate produced these primarily values by to smoldering be combus- within a factor of 1.5 of the fire- dependence on the MCE.tion Since (Yokelson CO et is al.,phase strongly 1996; associated will Burling with be et smolderingfire-integrated more al., combus- will tightly be 2010), minimized. correlated VOCs with emitted primarily CO during and this the variability in the discrete vs. tive to CO is evaluated by the strength of the correlation, western fuels (Table 2) areVeres et 30 % al. lower (2010). than the mean fire-integrated ERs reported by fire-integrated ERs (Fig. 2b).and Species benzene, show with a thecrete distinct weakest samples bifurcation (Fig. correlations, that 3). such These isthe as compounds dependent flaming have ethyne and upon significant smoldering portion the phases of of MCEdiscrete a emissions samples of fire in collected (see the both in Fig. dis- 1). theresent For smoldering these phase the types (low of fire-integrated MCE) compounds, emissions didMCE) not that resulting adequately in include rep- poor thespecies. correlation intense In between contrast, flaming VOCs discrete that emissions and hadfire-integrated the (high fire-integrated strongest ERs ERs correlations (e.g., between for the methanol these discrete and and toluene where 5 5 25 15 20 10 25 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | (2) and SOA 0.07 % for 3 ± or in other unmea- 2) and populate the 2 ≤ D C). For all 3 fuel regions, ◦ 0.03, and 0.95 ± and the inorganic gases (e.g., 4 0.03, 0.34 ± ONO). The addition of all nitrogen-containing 21732 21731 3 1), which contribute 29–40 % of the total mo- ) emitted per ppmv CO is equal to: 3 ≤ − D ) is 3.5 times greater than the southwestern fuels 1 ) and most contain at least one oxygen atom (e.g., − 1 ) and/or those that contain 1 or more oxygen atom(s). − 1 −  ). For all 3 fuel regions, the emissions are dominated by 1 − MW · 1) defined as having one or more pi-bonds (e.g., C-C or C-O ppmv CO MV 3 100 gmol 80 gmol ≥ − ER ≥ < D  , etc.) comprised over 99.05 % of all gaseous molar mass emitted and ppmv CO X x 3 CN), and methylnitrite (CH 22 µgm 3 = − ± ), and MV is molar volume (24.5 L at 1 atm and 25 1 − 9 µgm These species also have lower degrees of unsaturation ( species (MW upper left quadrants of Fig. 4.are VOCs formaldehyde, with ethene, the acetic largest acid, ERs and common methanol to all (Table 2). fuel types compounds ( double bonds, cyclic orlikely aromatic to rings, react with etc.). atmospheric In oxidantschemical and/or general, photo-dissociate moiety, these depending making on species the unsaturated are speciesprecursors. more VOCs potentially that important contain O tripleas bonds they (e.g., tend ethyne) to are be a less notable reactive. exception degree of unsaturation)ern is fuels. greatest Many for ofweights the northern VOCs (MW fuels in this andbenzenediol quadrant least and also benzofuran). for have The relatively southwest- combination highcate of that molecular these these species physical are properties relativelyto indi- reactive, make soluble, them and potentially of low important enough SOA volatility precursors. ERs. Collectively, the molar emission ratiosern are fuels a than factor the of southwestern. 3 greater for the north- was the overwhelmingly dominant gas-phase emission and singularly contributed , CO, NO ± 2 2 v. Over 82 % of the molar emissions of VOCs from biomass burning are unsaturated Figure 5a–c shows the fractional composition and total molar mass of measured iv. The largest ERs for all three fuel regions are associated with low molecular weight iii. Southwestern fuels generally have lower ERs and northern fuels have the largest vi. The number of VOCs in the upper right quadrants of Fig. 4 (increasing ERs and with low degrees oflar unsaturation mass ( emitted.and This methanol chemical emissions (Table family 2).containing Compared VOCs is are to emitted dominated hydrocarbons in substantially and by smallerDominant OVOCs, fractions, nitrogen nitrogen- acetic less VOCs than include acid, 8 hydrocyanic % acid oftonitrile formaldehyde, (HCN), the isocyanic (CH total. acid (HNCO), ace- organics presented heresented would in add Burling approximatelynitrogen et 5 % potentially al. ending to (2010); upsured the in however, gases nitrogen this the based budget ash, would1.3 on or pre- %. still being the leave emitted nitrogen over as content half N of of the the fuels fuel which ranged from 0.48 to oxygen-containing VOCs (OVOCs), whichmass collectively emissions. comprise The 57–68 largest % contribution of by the a total single chemical class is from OVOCs tify BB emissions. Molar mass (µgm Molar Mass VOCs emitted per ppmv COfuels for each (324 fuel region. The molar mass emitted by northern where ER is the(gmol mean discrete emission ratio of a gas, MW is the molecular weight measured, while VOCs contributed onlythe 0.27 southeastern, southwestern, and northern fuels, respectively. (92 over 95 % of the molar mass emitted. Collectively, CH CO CO 3.3.1 Molar mass emitted Here we compare thea magnitude function of and molar composition mass, which of is biomass a readily burning calculated emissions physical as property used to quan- 5 5 20 25 15 10 10 25 15 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , CO, cients 4 ffi and perox- OH), in the • 3 cient of a gas ffi 16) % of the total calculated C). Reaction rate coe ± ◦ OH) with all reactive gases and • ), which is 4.4 times greater than 1 in a BB plume. Total OH reactivity − 3 ciently high molecular weight, high is a molar concentration conversion ffi A ). Collectively, OVOCs provide the majority ppmv CO 1 ), and − 1 1 21733 21734 − − ratios and peroxynitrates, we use OH reactivity at 1 atm and 25 is the first-order reaction rate coe s x 1 1 − − 10 s OH cult to assess, so we roughly estimate an additional NO k ± ffi / ), ) (3) 1 ppmv CO ppbv − molec A 3 1 ) leads to the photochemical formation of O · 3 − − 2 3 s OH NO k ± · + moleccm (ER (NO 5 % to the total mass emitted could be from un-observed unknown 10 x ∼ X ; ppbv(ppmCO) 10 2 = production and VOC × 3 , and SO 2 One limitation of this analysis is the exclusion of “unknown” species, which are (i) Figure 5d–f shows the fractional contributions and total VOC-OH reactivities per 2. By extension, all of the totals presented in Fig. 5 should also be considered lower NO where ER is the discrete emission ratio for each measured gases (VOCs, CH with the hydroxyl radical (cm southwestern fuels (14 factor (2.46 OH reactivity even thoughmass emitted. non-methane VOCs were only 0.27–0.95 %ppmv of CO the for molar eachhave of the highest the OH 3 reactivity fuel (62 regions. The fresh BBof the emissions OH from reactivity northern ofsouthwestern the fuels (52 southeastern %) fuels and (57 northern %),bution while fuels from hydrocarbons (56 highly %). dominate Northern reactive the terpenes fuelsaverage, (14 have a %) the factor due largest of to contri- 5southwestern the fuels. greater ERs of than these southeastern species fuels being, and on a factor of 40 greater than were compiled using theKinetics Database National and Institute the of referencesculated therein Standards OH (Manion and reactivities et of Technology’s al., Chemical nant all 2015). sink measured Based of on species the OH listed cal- for in all Table 2, fuel VOCs regions are contributing the 70–90 domi- ( ynitrates, including peroxyacetic nitric anhydride (PAN). Duebetween to O the complex relationship is equal to: OHreactivity as a simplified metric tobustion of (i) fuels compare characteristic the of each magnitudemay region contribute of and to reactive to the gases (ii) photochemical identify emittedrepresents formation key by the of reactive com- species sum O that of all sinks of the hydroxyl radical ( polarity, and/or low volatility andriety thermal stability of to chemical escape ionization detectionemissions mass by of GC-MS, spectrometers, species a such and va- as theamines glyoxal, OP-FTIR. glycoaldehyde, have acetol, For been guaiacols, example, reported syringols,2001; BB and McMeeking in et the al., literaturenot 2009; (McDonald Akagi be et detectable et al., by al.,of 2011, any 2000; these 2012; of types Schauer Hatch the of et instruments compounds et is al., used al., di 2015) in but this would experiment. The contribution presence of NO 3.3.2 OH reactivity of BB emissions Oxidation of VOCs, often initiated by reaction with the hydroxyl radical ( contribution of VOCs. Collectively, we estimate thatFig. the 5a–c species account reported fororganic in approximately gases Table 48–64 emitted 2 % from and of thefor compiled the fuels each in studied fuel expected here. type mass The should∼ of total be non-methane VOC considered molar a mass lowerlimits; emitted limit however, and the additional could contribution increaseto of by the unidentified a following and/or factor discussions un-measured of could species not be determined. gaseous compounds that wereomitted measured from but this remain analysis unidentified becauseerly the and chemical identified were formula or therefore and (ii) familyWe could estimate were not the undetectable be mass prop- bysion contribution the factors from compiled suite the by of Yokelson first etknown” scenario instruments al. masses (2013) using listed observed for the in all by fuel-basedcompounds measured Table the (NMOC, emis- species 1. equivalent including PIT-MS. to These “un- VOCs)for “unidentified” accounted the non-methane for same 31–47 organic % fuels ofobserved studied the unknown mass here species emitted (Yokelson are et likely al., to 2013). be The of second su category of un- 5 5 10 15 10 20 25 20 25 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | N ≡ and 3 radicals that also • cients on the order of ffi CN), can have lifetimes on 3 21736 21735 100). Species such as styrene and benzalde- = ciently low volatility or high solubility under some ffi 200 (i.e., twice as much potential SOA formed compared at 298 K roughly equivalent to that of isoprene and the ma- ∼ 1 − s 1 − cient SOA precursors are relatively reactive organic compounds ffi ratios, oxidant concentrations, etc.). In order to conduct comparisons formation, in addition to being an air toxic. molec x 3 3 cm 10 − 10 × Figure 5g–i shows the composition and mean SOAPs of VOCs emitted for each of For all 3 fuel regions, alkenes have the largest contribution of any singular chemical Other important contributions to OH reactivity of BB emissions include highly un- Nitrogen-containing VOCs contribute less than 4 % of the OH reactivity of all fuels 1 5.1 times greater, respectively.three Unsaturated fuel OVOCs are regions the dueof dominant to 1,2- fraction the and for relatively 1,3-), all large benzaldehyde, ERs and and phenols. SOAPs Schauer of et benzenediols al. (sum (2001) reports signifi- whose oxidation products are of su the 3 fuel regions.CO) Southwestern compared fuels to southeastern have and the northern lowest fuels SOA that have potential estimated (480 SOAPs 2.7 per and ppmv BB plumes (Holzinger etnitrogen-containing al., organics 1999; including de 2-propenenitrile, Gouwspecies et benzonitrile, such al., and as 2003, heterocyclic 2006). pyrroles2001; Other Karl could et more serve al., reactive as 2007). BB markers3.3.3 of fresh plumes SOA potential (Friedli of et BB al., emissions VOCs that are e conditions. Aerosol yield is a measurefrom of this the oxidation mass per of mass condensablethat of compounds VOC aerosol created precursor; yields however, care for must(e.g., various be VOC species : taken NO were to ensure determinedof under SOA comparable potential conditions onoped a by consistent Derwent scale, et wean al. use equal (2010) a mass model-based that basis unitlessinvestigate “reflects relative SOA metric to the potentials toluene”. devel- propensity (SOAPs) The of ofMaster photochemical 113 VOCs Chemical transport VOCs to Mechanism model included (MCM form explicit used vditions SOA chemistry to 3.1) typical on from using of the an a idealized polluteddetermined set urban by of the boundary atmospheric simulated layer mass con- (Derwentexpressed of et relative aerosol al., to formed 2010). toluene per SOAPshyde (SOAP mass were have of SOAP values VOC of reactedto and is toluene) andstituents, were benzofurans, used and benzenediols. to estimate SOAPS for aromatics with unsaturated sub- functional groups. Some nitriles, such as acetonitrile (CH jor oxidation products include2009). dicarbonyls Up (Bierbach to et 27 al., furanPine 1992, isomers (Hatch 1995; have been Alvarez et identified et al., frombe al., 2015), the further combustion indicating explored of this in Ponderosa order is to an better important determine class their of potential contributions species to that O should class due to thewhich large is ERs the of singlesured. the largest Oxidation reactive individual of species contributor alkenes to ethene proceedsabstraction OH and by and reactivity OH propene, often of addition the results to anyhyde latter in and the species of the acetone), double-bond mea- which secondary or are formation hydrogen importantFischer peroxynitrate of et precursors carbonyls (Roberts al., (e.g., et 2014).tributor, al., acetalde- 2007; Primary after propene, emissions to ofFormaldehyde the formaldehyde is OH reactive is with reactivity the OH of second-largest and all is con- VOCs a emitted photolytic for source all of RO 3 fuel regions. contribute to O idation of 1,3-butadieneand results 2-propenal, in a highly precursor1999). of reactive The peroxyacrylic OVOC nitric OH(2-furfural), products anhydride reactivity and including (APAN) (Tuazon of furan. furans et∼ Alkyl furans al., furans is have dominated reaction by rate 2-methylfuran, coe 2-furaldehyde SOA formation. due to the low reactivities of the most abundantthe emissions, order which often of contain months –C making these species good markers of long-range transport of saturated OVOCs (e.g.,unsaturated 2-propenal, alkenes methyl (e.g., 1,3-butadienemajority vinyl and ketone, of 1,3-cyclopentadiene), and and theseand furans. methacrolein), types many The poly- of of their species oxidation are products highly are photochemically reactive active. with For a example, ox- variety of oxidants 5 5 25 10 15 20 20 25 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 0.94, Table 3) and enhance- r > 21738 21737 2 %) contribution to total SOAP. The calculated < orded a unique opportunity to investigate BB emis- ff ected Boulder, Colorado in September 2010. The in-situ GC-MS ff CN), carbon monoxide (CO), and several VOCs. Species such as benzonitrile 3 First we identify the potential emission sources impacting the measurements. Ace- Monoterpenes have a very small ( The largest contributions to SOAP from hydrocarbons include aromatics with sat- ments in ambient mixingdicating ratios that above BB detection was limitisoprene the only and only alpha-pinene occur significant were in sourcelated similarly the of with enhanced BB acetonitrile in these plumes the during compounds. in- BB BB BB VOCs plumes plume episodes; such and however, were as the well generally mixingsunlight-dependent corre- lower ratios emissions observed than of in those isoprene the mulation observed (e.g., of at monoterpenes 09:00–15:00 LT) other in and times theto from nocturnal 9 from the September boundary the 2010 layer accu- natural (e.g.,cantly 06:00 LT). higher 9 3-Carene mixing August was ratios 2010 in the 18:00 the only BB monoterpene plume than that in had biogenic signifi- emissions. Ethene, ethyne, tonitrile is a commonseen BB in tracer Fig. that 6, we BB usetrile plumes (CH to are readily help distinguished clarify by periodsand concurrent of furan increases in BB are acetoni- influence. very As tightly correlated with acetonitrile ( sions measured by this sameissues GC-MS system associated in with simulated the andand real presence fires natural of and biogenic other to emissions explore VOCsmoke during sources measurements both being such the very as daytime rarely urban and reported emissions (Adler nighttime; et with al., nighttime 2011). measurements are shown in Fig.tify 6 and and quantify summarized a in numberobserved Table of 3. in VOCs We the in were fire ambient able emissionsfrom BB to at plumes the iden- the that Fourmile Fire we Canyon Sciences had Fire Laboratory. only Analysis a previously of BB plumes (25 %), phenols (9 %), andbutions furans from (9 benzenediols %); (not however, theirbut measured), not analysis benzaldehyde included did or in not benzofurans estimate). include (measured contri- 3.4 Field measurements of BB emissions Here we presentCanyon field-measurements Fire that of a VOCs in ambient air during the Fourmile et al., 1997; Bahreini etobserved al., 2012), in although ambient predicted air SOA suggestingadditional is that typically SOA the much precursors aerosol lower that than yields remain may unaccounted be for too (de low Gouw or etSOAPs there al., of are 2005). monoterpenes arein only contrast 20 % to that measured ofmonoterpenes toluene aerosol compared (Derwent yields to et toluene whichcreased al., (Pandis are the 2010). et approximately SOAPs This al., of 1.7 is 1992). themonoterpenes times As monoterpenes to higher a by toluene sensitivity for a in test, factormodest line we of increases with in- 10 in that bringing total of thethe SOAP measured SOAP of aerosol largest ratio only yields. increase of 2 This % in resultedthe for total fractional in SW contribution SOAP and of at terpenes 5 %SOAP increased 16 %. for while from 1.8 SE With the % fuels. contribution (Fig. the N 5i)was of adjusted to fuels reduced unsaturated monoterpene 15 had from OVOCs % SOAPs, 67 remained of the to thecontributions total of 58 dominant % monoterpenes class of are but likely thescale underestimated total is for SOAP. northern This used; however, sensitivity fuels the if test largestues the suggests contributions to SOAP to that be SOAP the from for oxygenated thecomparison, aromatics northern Hatch (benzenediols, fuels phenols, et contin- and al. benzaldehyde).bustion For (2015) of estimated Ponderosa that Pine the is SOA dominated mass by formed from aromatic the hydrocarbons com- (45 %), terpenes urated functional groupsunsaturated (if substituents any) such as such styrene.thought as Traditionally, to these benzene be are the the and species largest toluene that contributors and are to SOA aromatics formation with from urban emissions (Odum cant gaseous emissions ofshows benzenediols that from 1,2-benzenediol combustion (o-benzenediol)1,3-benzenediol of is (m-benzenediol) pine the is in dominant primarily gas-phasediscrete a associated ERs isomer fireplace used with while and in the this particletribution comparison of may phase. underestimate several The the compounds emissions emittedemissions and in of SOA the most con- later VOCs and portions CO of were a lower laboratory as burn previously discussed when (Sect. 3.2). 5 5 20 25 15 10 15 20 25 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , 4 erent for ff , CO, CH 2 16) % of the total calculated ± erent from one another, there was no ff erences in the observed enhancement ff 52 %), and also contributed a significant erences in the enhancement ratios and the ff > 21740 21739 0.12 % of total detected gas-phase emissions by ± 0.2 and fire-to-fire variability for VOCs emitted mainly ± erences in the fuel composition, the relative ratio of flam- ff 0.07% by mass due to the predominance of CO ± emissions. However, VOCs contributed 70–90 ( x erent biomass fuel types important in the southwestern, southeastern, and northern 57 %) and potential SOA precursors ( By comparing discrete and fire-integrated ERs for various VOCs relative to CO, we The distribution of VOC emissions (magnitude and composition) was di OVOCs contributed the dominant fraction of both the total VOC mass emitted Observed enhancement ratios of several VOCs relative to acetonitrile and CO are ff > mole and less than 0.95 each fuel region. Thenorthern largest U.S. while total southwestern U.S. VOCVOCs fuels emissions produced contributed the were less lowest from total than VOC fuels 0.78 emissions. representing the and NO show that the discrete GC-MSwithin samples an adequately average represented factor the of fire-integrated 1.2 ER ( US. A complementary suitequantify over of 200 state-of-the-art organic instrumentsof and the 9 was species were inorganic used quantified gases via toconfirmation discrete emitted sampling for identify from by the the and real-time laboratory GC-MS, PIT-MS which burns. and2011). also PTR-MS Most The provided mass variability in assignments emissions (Warneke over et thein al., course detail of by each the biomass fast-response burn instrumentschemistry was providing measured valuable and insight processes into that the combustion govern the emissions of various species. by smoldering, which are theflaming majority and of smoldering VOCs. Discrete were ERs highly foron variable VOCs and the emitted showed mix by a both of clearportance bifurcation combustion depending processes of during collecting multiple sampling.fire-integrated discrete This emissions samples analysis cannot at highlights be various the measuredVOCs. stages im- to of ensure replicate adequate burns measurement of if all OH reactivity and 100 %biomass. of Over 82 the % potential ofhighly SOA the reactive precursors VOC emissions emitted alkenes, by from aromatics moleas combustion and are aldehydes of terpenes unsaturated and species as ketones. including formaldehyde, well VOCs ethene, as with acetic acid, photolabile the and OVOCs largest methanol. such ERs common to all fuel types are clear relationship between the observedrelative di reactivity of the VOCs. Thus, small di the urban and biogenicenhancements sources in impacting BB thetonitrile plumes. measurement may In site, also theory, and be thespecies (iii) used represent relative had as a ratios range large a of of BB-specific(Table reactivities 3). photochemical these that We clock are species compared much since the tofor greater each enhancement the than ace- of ratios two that BB of these of plumes acetonitrile eachage observed VOC of on marker the 9 vs. August two acetonitrile several 2010 VOCs BB in in plumes order each could plume to were determine be statistically if distinguished. di the While relative the enhancement ratios for compiled in Table 3 alongshows a with comparison the of types the ofCanyon VOC Fire to emission acetonitrile and sources ratios the for of laboratory-basedtified each select biomass VOC. species benzofuran, Figure for burns 2-furaldehyde, the 7 of 2-methylfuran, Fourmile tracers all furan, for fuel and BB types. We emissions benzonitrile havelated from as iden- with these both the observations. acetonitrile “best” and These CO species in (i) the BB were plumes, well (ii) corre- had negligible emissions from We report a chemicallydi detailed analysis of the trace gases emitted from burning 18 benzene, styrene, and methanol were enhancedin in urban the emissions. BB plumes An butenhanced urban are in also plume all present at of these 06:00–09:00 LT species 9 and September CO; however, 2010 acetonitrile (Fig. is not 6) enhanced. is ratios more likely relate toing di vs. smoldering emissions inenough each time BB for plume, significant or photochemistrythe variable to source, secondary occur these sources. as ratios Given a could BB be plume more moves useful further to from estimate photochemical ages. 4 Conclusions 5 5 20 15 25 10 15 10 25 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 21742 21741 This work was supported by the Strategic Environmental Research and formation downwind of the source. Furans are a class of OVOCs in BB 3 The Fourmile Canyon Fire in Boulder, CO, allowed us to identify and quantify a num- optical evolution of biomass burning1503, aerosols: doi:10.5194/acp-11-1491-2011, a 2011. case study, Atmos. Chem. Phys., 11, 1491– and Wennberg, P. O.:atmospheric Emission models, factors Atmos. for Chem. open Phys.,2011. 11, and 4039–4072, domestic, doi:10.5194/acp-11-4039-2011 biomass burning for useUrbanski, in S. P., Wold,Evolution of C. trace E., gases and Seinfeld,Phys., particles 12, J. emitted 1397–1421, by H., a doi:10.5194/acp-12-1397-2012, chaparral Coe, 2012. fire H., in California, Alvarado, Atmos. M. Chem. plumes J., from biomass and burning: Weise, 1.D09306, D. Lagrangian, doi:10.1029/2008jd011144 R.: parcel 2009. studies, J. Geophys. Res.-Atmos., 114, cher, E. V., McMeeking,Wold, G. C. R., E.:biomass Seinfeld, Investigating burning J. plume the H., from links15, Soni, a 6667–6688, prescribed between T., doi:10.5194/acp-15-6667-2015, fire Taylor, 2015. ozone in J. California and W., chaparral, Weise, organic Atmos. D. 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J., Kleeman, M. J., Cass, G. R., and Simoneit, B. R. T.: MeasurementSimpson, of I. emissions J., Akagi, S. K., Barletta, B., Blake, N. J., Choi, Y., Diskin, G. S., Fried, A., Fu- Urbanski, S.: Wildland fire emissions, carbon, and climate: emission factors, Forest. Ecol. 5 5 10 15 10 25 15 20 30 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 SD) npnts ± (3.5152) (0.9354) (0.2804) (3.4340) (0.6632) (12.8430) Goldan et al. (2004) Gilman et al. (2010) Warneke et al. (2011) Warneke et al. (2011) Veres et al. (2011) Roberts et al. (2011) Burling et al. (2011) ): 6.8510 1.4633 0.09820.4005 (0.0620) 0.00060.0322 (0.0007) 0.1400 (0.0261) (0.1130) 0.00450.0814 (0.0031) 0.0836 (0.0634) 0.0536 (0.0674) 0.0369 (0.0353) 0.0330 (0.0269) 0.0425 (0.0212) (0.0208) 0.29050.1180 (0.1492) 0.0159 (0.0667) 0.4980 (0.0113) 0.0052 (0.2945) 0.4904 (0.0035) 0.1552 (0.2844) 0.5432 (0.0586) 0.0111 (0.2920) 0.2868 (0.0071) 0.1651 (0.1559) 0.0474 (0.0926) 0.0812 (0.0326) 0.0647 (0.0415) (0.0251) 8.5115 0.31621.5227 (0.3624) 0.23970.2732 (0.1916) 0.0881 (0.2648) 0.0183 (0.0462) 0.1881 (0.0164) 0.0108 (0.0965) 0.2311 (0.0074) (0.1872) m/z 18.3160 ): 20– ): 20– 23 18 20 20 23 23 23 23 0 16 23 14 14 13 14 12 21 14 23 16 14 14 12 16 16 14 14 13 16 16 16 23 23 23 23 23 23 15 14 23 23 m/z m/z C ◦ C ◦ 185 SD) npnts N Avg ( ): 26 to 150 a.m.u that are unique and − ± 220 1 − > (3.8024) (1.2193) (0.2902) (4.2382) (2.1610) (0.3320) < m/z nity greater than wa- nity greater than wa- ffi ffi 4.5311 1.5957 0.29840.3333 (0.4734) 0.0004 (0.0008) 0.05800.0889 (0.0878) 0.0001 (0.0789) (0.0002) 0.00890.0572 (0.0117) 0.0640 (0.0516) (0.0387) 0.04690.0358 (0.0281) 0.0310 (0.0213) 0.0412 (0.0222) (0.0304) 8.1879 0.13960.0422 (0.0883) 0.0147 (0.0304) 0.1782 (0.0139) 0.0052 (0.1162) 0.2039 (0.0028) (0.0943) 0.05220.1788 (0.0443) 0.0097 (0.1376) 0.1168 (0.0063) 0.1013 (0.0721) 0.0196 (0.0482) (0.0153) 0.02600.0279 (0.0228) (0.0292) 3.4917 0.26680.4851 (0.2151) 0.1209 (0.0920) 0.14270.0391 (0.1174) 0.0152 (0.0284) 0.0996 (0.0168) 0.0064 (0.0634) 0.0902 (0.0053) (0.0773) ciently non-polar ffi 9 9 9 9 9 8 8 8 8 9 9 9 8 9 9 8 9 9 9 9 9 25 23 29 29 29 29 29 29 29 25 29 29 29 29 29 29 29 29 29 boiling point su mass frag. ( Melting point Proton a ter; Protonatedor molecular mass240 a.m.u mass fragment ( Proton a ter; Protonatedor molecular mass240 a.m.u mass fragment ( Gas-phase acidity greater than that of acetic acid; Deprotonated molec- ular mass or mass fragment ( 10–225 a.m.u Strong absoprtion features between 600–3400 cm have minimalother strong interferences infrared-absorbers from − ine H) and and ffl SD) npnts SE Avg ( + + − ± O O 3 3 (1.2846) (0.9985) (0.1829) (4.1077) (2.0528) (0.3761) 21750 21749 1.8388 0.6317 0.05220.1038 (0.0813) 0.0003 (0.0008) 0.01670.0271 (0.0585) 0.0002 (0.0427) (0.0008) 0.00090.0159 (0.0010) 0.0218 (0.0225) (0.0176) 0.01380.0085 (0.0128) 0.0083 (0.0079) 0.0111 (0.0060) (0.0054) 5.8525 0.02760.0040 (0.0341) 0.0890 (0.0037) 0.0012 (0.1102) 0.1029 (0.0014) (0.1182) 0.02560.0931 (0.0338) 0.0023 (0.1166) 0.0547 (0.0023) 0.0431 (0.0595) 0.0097 (0.0486) (0.0122) 0.01330.0103 (0.0159) (0.0100) 2.0801 0.10460.2961 (0.1652) 0.0579 (0.0937) 0.06150.0202 (0.1036) 0.0091 (0.0256) 0.0224 (0.0202) 0.0024 (0.0317) 0.0429 (0.0040) (0.0654) 0.0432 (0.0638) SW Avg ( and identification − with ion trap mass 27 27 43 43 57 43 43 71 57 57 43 43 57 57 57 27 55 56 56 84 84 84 84 83 56 55 41 56 55 41 41 41 41 41 55 55 55 42 55 55 with quadrupole mass + + H) H) D m/z C(O)O 3 + + identification via protonated(M ion Discrete sampling via cryogenic pre-concentration,graphic chromato- separation, andfication identi- via retentionelectron impact time ionization mass and spectrum Real-time samplingtransfer via reactions with H proton filter identification via protonated(M ion Real-time samplingtransfer via reactions with H proton spectrometer Real-time samplington viaCH transfer pro- reactions with via deprotonatedwith ion quadrupole mass (M filter Real-time spectral scanning via open pathidentification via White compound spe- cell,cific infrared absorption o features 0) 1) = = D D Gas chromatograph- (Quadrupole) Mass Spectrometer Proton Transfer Reaction- (Quadrupole) Mass Spectrometer Proton Transfer Reaction- (Ion Trap) Mass Spectrometer Negative Ion-Proton Transfer Reaction- (Quadrupole) Mass Spectrometer Open Path-Fourier Transform Infrared Spectrometer NameAlkanes (Saturated, Ethane Formula MW C2H6 30 0 PropaneButane_isoButane_nPropane_22dimethylPentane_isoPentane_nButane_22dimethyl C5H12 C4H10 C3H8 72 C4H10 0 58 C6H14 44 C5H12 0 58 0 86 C5H12 72 0 0 0 72 0 Pentane_3methyl C6H14 86 0 Hexane_nHeptane_nOctane_nNonane_nDecane_nUndecane_nAlkenes (Saturated, C6H14Ethene C7H16 86 C8H18 100 C9H20 0 0 114 C10H22 C11H24 128 0 142 156 0 0 0 C2H4 28Pentene_trans2 1 Cyclopentane_1methylPentene_1_2methylCyclohexane C6H12Hexene_1Hexene_cis2 C5H10 84 C6H12Hexenes (sum of 3 isomers)Cyclohexane_methyl 1 70 C6H12 84Heptene_1 1 Octene_1 1 C6H12 84Nonene_1 C7H14Decene_1 1 C6H12 84 C6H12Undecene_1 98 1 84 84 1 1 1 C7H14 C8H16 98 C9H18 112 1 C10H20 C11H22 126 1 140 154 1 1 1 PropenePropene_2methylButene_1Butene_cis2Butene_trans2Butene_1_2methyl C4H8Butene_1_3methylButene_2_2methylCyclopentane C3H6 56Pentene_1 C5H10 1 C4H8 C4H8 C4H8Pentene_cis2 C5H10 42 C5H10 70 1 56 56 56 70 1 70 1 1 1 1 C5H10 1 70 C5H10 C5H10 1 70 70 1 1 Mean VOC to CO discrete emission ratios (ERs) for the southwestern (SW), south- Instrument description. PTR-MS GC-MS Name Instrument Meas. Description Sampling Limitations References PIT-MS NI-PT-CIMS OP-FTIR Table 2. eastern (SE), and northern (N) fuel regions. Table 1. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 2 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 SD) npnts ± SD) npnts ± (0.9509) (0.4405) (1.1869) (1.2079) (5.6894) (0.6405) (1.3236) (0.5725) (0.2484) (0.1116) (0.0420) (0.2437) 0.0427 (0.0651) 0.08240.0441 (0.1062) 1.8781 (0.0343) 0.06930.5836 (0.0300) 0.0651 (0.3458) (0.0395) 0.04260.2815 (0.0303) 0.1733 (0.1725) 0.2504 (0.0691) 0.0569 (0.0927) (0.0382) 0.18310.0674 (0.1771) 0.0927 (0.0545) 0.1109 (0.0506) 0.0097 (0.0539) 0.0266 (0.0018) (0.0151) 0.19540.0464 (0.0798) 0.0437 (0.0394) 0.1387 (0.0259) 0.0171 (0.0536) 0.0155 (0.0077) (0.0090) 0.6942 0.11930.1578 (0.1459) 0.8384 (0.2107) 0.02370.1313 (0.0206) 0.8105 (0.1849) 0.16380.0310 (0.1545) (0.0336) 0.03390.0915 (0.0435) (0.0659) 5.0910 0.7876 0.04200.0165 (0.0213) 0.0379 (0.0074) (0.0158) 0.0686 (0.0700) 0.1311 0.01350.0236 (0.0074) (0.0103) 0.02320.0414 (0.0129) 0.0865 (0.0176) 0.03140.0261 (0.0122) 0.0215 (0.0108) (0.0122) 0.00790.0277 (0.0059) 0.0339 (0.0106) 0.0140 (0.0120) 0.0436 (0.0048) (0.0270) 0.0196 (0.0085) 0.3361 2.1381 1.3375 0.1766 (0.0919) 0.1429 (0.0579) 0.5088 0.09060.0828 (0.0562) 0.0401 (0.0339) (0.0158) 0.03740.1265 (0.0193) 0.0290 (0.0737) (0.0211) 0.0331 (0.0204) 0.0248 (0.0145) 0.0329 (0.0193) 0.1726 (0.1400) 4 8 16 16 23 23 16 14 16 16 14 14 14 16 16 16 14 13 14 12 16 16 13 16 16 16 23 14 12 23 16 10 15 23 23 23 23 23 23 23 23 23 15 23 15 15 23 14 14 16 16 23 16 16 16 16 16 16 16 16 16 16 16 13 16 16 16 16 16 16 16 23 SD) npnts N Avg ( ± SD) npnts N Avg ( ± (0.3530) (0.1944) (0.1302) (0.1454) (1.3580) (0.1626) (0.3680) (0.4414) (0.1546) (0.0325) (0.0234) (0.1054) 0.0041 (0.0052) 0.01540.0087 (0.0190) 0.4122 (0.0095) 0.01580.1747 (0.0146) 0.0107 (0.0992) (0.0119) 0.01030.1125 (0.0108) 0.0627 (0.0789) 0.1044 (0.0360) 0.0088 (0.0538) (0.0072) 0.05160.0102 (0.0554) 0.0345 (0.0117) 0.0466 (0.0205) 0.0044 (0.0259) 0.0045 (0.0030) (0.0042) 0.05310.0035 (0.0418) 0.0262 (0.0053) 0.0673 (0.0139) 0.0048 (0.0416) 0.0041 (0.0048) (0.0055) 0.2428 0.05380.0289 (0.0979) 0.1232 (0.0303) 0.00940.0068 (0.0109) 0.1013 (0.0055) 0.01940.0118 (0.0220) (0.0066) 0.01310.0669 (0.0163) (0.0786) 1.7412 0.1850 0.7008 0.6196 0.0829 (0.0583) 0.0730 (0.0527) 0.2107 0.06170.0416 (0.0425) 0.0234 (0.0291) (0.0154) 0.01640.0395 (0.0122) 0.0073 (0.0312) (0.0065) 0.0173 (0.0102) 0.0119 (0.0104) 0.0151 (0.0129) 0.1030 (0.0974) 0.02000.0018 (0.0187) 0.0149 (0.0039) (0.0144) 0.0153 (0.0163) 0.0408 0.00390.0097 (0.0045) (0.0080) 0.00490.0153 (0.0050) 0.0297 (0.0140) 0.01430.0155 (0.0116) 0.0040 (0.0069) (0.0050) 0.00040.0099 (0.0011) 0.0099 (0.0103) 0.0027 (0.0113) 0.0179 (0.0038) (0.0179) 0.0063 (0.0105) 0.1067 9 9 9 8 9 9 7 8 9 9 9 9 9 9 9 9 9 9 8 9 9 9 9 8 9 8 9 5 4 29 29 27 29 29 29 29 29 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 8 9 9 9 9 9 9 9 29 29 29 29 29 29 29 29 29 SD) npnts SE Avg ( ± SD) npnts SE Avg ( ± (0.5315) (0.1447) (0.0249) (0.0088) (3.0119) (0.1503) (0.2713) (0.0238) (0.0840) (0.0446) (0.7301) (0.3417) 0.02850.0101 (0.0452) (0.0146) 2.3905 0.2093 0.0080 (0.0054) 0.4065 0.02210.1724 (0.0287) 0.0161 (0.3868) (0.0176) 0.00900.0699 (0.0166) 0.0457 (0.1240) 0.0668 (0.0795) 0.0140 (0.1069) (0.0152) 0.02420.0110 (0.0329) 0.0170 (0.0127) 0.0202 (0.0235) 0.0026 (0.0298) 0.0039 (0.0037) (0.0081) 0.03480.0073 (0.0466) 0.0098 (0.0094) 0.0347 (0.0120) 0.0020 (0.0531) 0.0013 (0.0027) (0.0018) 0.1289 0.00320.0050 (0.0026) 0.0219 (0.0052) 0.00020.0075 (0.0005) 0.0058 (0.0106) 0.0051 (0.0051) 0.0044 (0.0092) (0.0026) 0.00530.0092 (0.0020) SW Avg ( 0.8385 0.3549 0.0495 (0.0498) 0.0391 (0.0418) 0.09810.0150 (0.1136) 0.0172 (0.0137) 0.0090 (0.0217) (0.0083) 0.00940.0186 (0.0114) 0.0041 (0.0228) (0.0042) 0.0081 (0.0096) 0.0056 (0.0065) 0.0065 (0.0078) 0.1081 0.0074 (0.0084) 0.0046 (0.0054) 0.0080 (0.0097) 0.00070.0093 (0.0011) (0.0102) 0.0323 0.0883 0.0358 0.0067 (0.0066) 0.00520.0142 (0.0059) 0.0229 (0.0125) (0.0255) 0.00840.0070 (0.0066) (0.0048) 0.00100.0062 (0.0009) 0.0062 (0.0054) 0.0021 (0.0066) 0.0274 (0.0028) (0.0443) 0.0048 (0.0052) SW Avg ( + IR 52 54 54 54 66 66 67 67 67 67 78 79 80 67 67 67 67 67 91 81 55 54 91 67 93 93 68 68 93 93 93 93 93 39 50 21752 21751 91 91 91 91 91 78 91 91 205 119 105 117 117 119 119 102 104 115 117 118 117 117 117 128 130 130 130 117 117 117 105 105 105 105 105 105 D m/z D m/z 4) 4) D > 0) = D D > 1) D > Continued. Continued. Xylene_o C8H10 106 4 Xylenes_m&p (sum of 2 isomers) C8H10 106 4 Benzene_123trimethyl C9H12 120 4 Benzene_124trimethylBenzene_135trimethylBenzene_1ethyl_2methylBenzene_1ethyl_3&4_methyl (sum of 2 isomers)Benzene_isoPropyl C9H12Benzene_nPropyl 120 4 C9H12 C9H12 C9H12 120 120 120 4 4 4 C9H12 120 C9H12 4 120 4 Benzene_isoButyl C10H14 134 4 Benzene_nButyl C10H14 134 4 Benzene_1methyl_4isopropyl (p-Cymene) C10H14 134 4 Benzene_nPropyl_methyl (sum of 2 isomers) C10H14 134 4 Benzene_1propenylStyrene_4methyl C9H10 118 5 C9H10 118 5 Benzene_14diethylXylene_ethyl (sum of 2 isomers)Aromatics with unsaturated substituents ( Benzene_ethynyl (Phenylethyne)Styrene (Phenylethene)IndeneBenzene_2propenyl C10H14Benzene_isoPropenylStyrene_2methyl 134 C8H6Styrene_3methyl 4 C10H14 134 102IndaneNaphthalene 4 6 Indene_1or3methyl C8H8Naphthalene_12dihydroNaphthalene_13dihydro 104Benzene_1butenyl 5 Benzene_methylpropenyl (2-phenyl-2-butene) C9H10 C9H10Styrene_ethyl 118 C10H12 118 5 132 C9H8 5 C9H10 5 C9H10 118 116 118 5 6 C10H10 5 C10H10 C10H10 130 130 130 C10H8 6 6 6 C9H10 128 C10H12 7 118 132 5 5 C10H12 132 5 NameAromatics with saturated subsituents ( Formula MW BenzeneTolueneBenzene_ethyl C8H10 C6H6 C7H8 106 78 4 4 92 4 Butenyne (Vinylacetylene)Butadiene_12Butadiene_13Butyne (1- or 2-)Cyclopentadiene_13Pentenyne isomer (e.g., propenylacetylene)Butyne_3methylCyclopentenePentadiene_cis13Pentadiene_trans13 C5H6Hexadienyne (e.g., divinylacetylene) C4H4Cyclopentadiene_methyl (sum of 2 isomers)Hexenyne (e.g., 66 2-methyl- 1-penten-3-yne)Cyclohexene 52 3 Cyclopentene_1methyl 3 Hexadiene_cis13 C6H8Hexadiene_trans13 C4H6 C5H6Other C4H6 C6H8 C6H10 C6H6 (sum of C4H6 5Heptadiyne isomers) (sum 80 of 54 2 isomers)Cyclohexene_1methyl 66 3 54 80 2 78Octadiene C5H8 3 54 2 3 4 Nonadiene 2 C5H8 C5H8C10H14 C5H8 non-aromatic (e.g., hexahydronaphthalene) 68 C10H14 2 Terpenes 68 (Polyunsaturated 68 68 134Isoprene 2 2 C6H10 2 4 Camphene C6H10Carene_3 82 C7H8Limonene_D 82 C6H10 C6H10 2 C6H10Limonene_iso 2 Myrcene 92 82 82 82Pinene_alpha C7H12 4 2 Pinene_beta 2 2 Terpinene_gamma 96Terpinolene 2 Sesquiterpenes (sum of all isomers) C8H14 C9H16 110 124 2 2 C5H8 C10H16 C15H24 136 C10H16 C10H16 204 C10H16 3 68 136 136 136 4 2 3 3 C10H16 C10H16 3 C10H16 136 136 C10H16 136 3 3 136 3 3 C10H16 136 3 NameAlkynes and Alkenes (Polyunsaturated, EthynePropyneButadiyne_13 (Diacetylene) C4H2 50 Formula 4 MW C2H2 C3H4 26 40 2 2 Table 2. Table 2. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 3 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 2 4 4 4 4 4 4 4 4 4 4 4 4 4 SD) npnts SD) npnts ± ± (6.2350) (2.2719)(0.2301) 4 2 (0.8811) (8.7348) (1.6919) (1.6182) (1.9126) (0.4337) (0.6550) (0.4806) (10.5410) 4 3.5441 0.5275 (0.1642) 0.5501 (0.3146) 2.1216 (0.8712) 1.2062 (0.5357) 0.0470 (0.0227) 0.0048 (0.0095) 0.0179 (0.0162) 0.0401 (0.0326) 0.9221 (0.6570) 1.4135 (0.6686) 0.7012 (0.2870) 0.0384 (0.0136) 0.1287 (0.0537) 2.4947 3.9631 0.6995 (0.2661) 1.1090 0.0071 (0.0141) 0.0101 (0.0067) 1.2999 0.0687 (0.0330) 1.2105 0.1758 (0.0661) 0.1808 (0.1005) 0.08210.2504 (0.0288) 0.1980 (0.0957) (0.0363) 0.26732.6208 (0.1892) 0.9246 (1.0656) (0.3186) 0.19710.8027 (0.0829) (0.3109) 0.0635 (0.0431) 9.6068 0.2096 (0.0831) 0.65370.0472 (0.3598) (0.0228) 0.16570.0186 (0.0976) 0.1434 (0.0110) 0.1323 (0.0695) 0.1092 (0.0939) 0.1791 (0.0551) 0.1330 (0.0935) 0.0097 (0.0562) (0.0063) 0.04620.1646 (0.0268) (0.0868) 3.0223 1.3360 0.7641 (0.8964) 1.6524 0.3217 (0.2551) 5.4742 (3.5540) 0.0713 (0.0868) 0.1976 (0.2297) 0.09810.1066 (0.0803) 0.0359 (0.1088) 0.1125 (0.0161) 0.0217 (0.0303) 0.0296 (0.0304) 0.1380 (0.0168) (0.0746) 17.9180 13.6981 23 23 23 23 23 16 16 16 16 16 16 16 16 13 21 17 23 23 16 16 16 16 16 23 16 23 16 16 23 23 23 23 23 23 23 15 16 10 15 16 16 13 14 14 15 16 12 13 12 23 23 23 23 16 16 16 16 16 16 16 16 16 SD) npnts N Avg ( SD) npnts N Avg ( ± ± (0.8806) (1.1659) (3.3461) (0.4732) (1.0837) (0.4118) (8.8369) (1.6904)(0.5742) 23 17 (0.5366) (5.5412) (7.2935) 23 1.3107 0.3234 (0.2207) 0.1807 (0.1257) 0.8953 (0.6389) 0.6435 (0.4616) 0.0223 (0.0149) 0.0000 0.0000 0.0043 (0.0059) 0.0265 (0.0337) 0.9873 0.8946 (0.5222) 0.3433 (0.2471) 0.0250 (0.0210) 0.1055 (0.0335) 0.7740 (0.6275) 3.1107 0.4717 (0.3259) 0.7770 (0.6290) 21 2.0703 (1.4093) 0.7302 0.0154 (0.0438) 0.0014 (0.0027) 1.5298 0.0585 (0.0403) 0.6908 0.0776 (0.0582) 0.0857 (0.0587) 0.03870.1366 (0.0285) 0.1078 (0.0734) (0.0938) 0.48171.6035 (0.8472) 0.4497 (1.1498) (0.3177) 0.08500.4143 (0.0641) (0.3061) 0.0342 (0.0224) 0.1031 (0.0626) 0.6741 (0.4345) 0.0349 (0.0160) 0.14260.0081 (0.0933) 0.2327 (0.0082) (0.2540) 0.13980.0780 (0.0760) 0.1095 (0.0394) 0.0869 (0.0537) 0.0558 (0.0483) (0.1431) 0.02690.0834 (0.0092) (0.0317) 2.7807 0.8046 0.5241 (0.5064) 0.9841 0.1199 (0.0754) 7.7807 2.8332 (1.8131) 0.0323 (0.0326) 0.1360 (0.2705) 0.04320.0367 (0.0366) 0.0198 (0.0392) (0.0176) 0.05350.0083 (0.0456) 0.0152 (0.0105) 0.1395 (0.0113) (0.0757) 13.0293 12.2348 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 29 29 29 29 29 25 13 29 25 29 29 29 8 9 5 9 9 8 9 9 8 8 9 8 9 7 9 9 9 9 9 9 9 9 9 29 29 29 29 29 29 29 29 29 29 29 SD) npnts SE Avg ( ± SD) npnts SE Avg ( ± (0.6824) (0.4242) (0.4799) (0.2474) (0.2119) (0.3634) (3.2343) (1.2922)(0.6858)(1.1114) 29 16 (3.1497)(2.9726) 29 0.8189 0.04090.0140 (0.0438)0.1218 (0.0140) (0.1286) 16 15 0.2159 0.1073 (0.1637) (0.1266) 17 17 0.3672 0.0562 (0.3881) (0.0537) 2 2 0.0895 (0.1077) 0.4003 (0.5191) 0.2147 (0.2059) 0.0159 (0.0178) 0.0004 (0.0012) 0.0023 (0.0044) 0.0056 (0.0080) 0.0825 (0.1208) 0.2682 (0.4437) 0.1145 (0.1015) 0.0072 (0.0064) 0.0306 (0.0333) 0.4262 0.24380.2212 (0.1859) (0.1661) 0.4807 0.2680 0.0083 (0.0126) 0.0022 (0.0027) 0.3567 0.0152 (0.0135) 0.2847 0.0272 (0.0311) 0.0328 (0.0472) 0.0167 (0.0218) 0.09020.0599 (0.0666) (0.0444) SW Avg ( 5.3926 0.06750.0068 (0.0390) 0.0498 (0.0061)0.6501 (0.0617) 0.2135 (0.7408) 150.4593 (0.2333) 0.1183 (0.4854) 0.0214 (0.1251)0.0496 (0.0157) 0.1788 (0.0610) 170.0535 (0.2216) 0.0064 (0.0599) 0.01140.8294 (0.0085) (0.0115) (1.6678) 0.04420.0243 (0.0476) 0.0576 (0.0315) 2 0.0381 (0.0457) 0.0024 (0.0366) (0.0041) 0.01920.0101 (0.0223) 0.0314 (0.0063) (0.0315) 1.2331 0.8433 0.8994 0.0272 (0.0237) 0.77310.0636 (0.9389) 0.0869 (0.1324) 0.0314 (0.0731) 0.0393 (0.0380) 0.0074 (0.0591) (0.0073) 0.02920.0202 (0.0312) 0.0062 (0.0299) 0.0622 (0.0092) (0.0334) 5.3939 0.63593.6175 (0.5705)1.5503 (1.1511) 29 1.6007 (1.1054) 23 1.7538 (1.9738) 4 SW Avg ( − − + − + 56 70 41 55 86 85 86 58 96 82 84 84 84 77 68 70 72 95 95 82 82 96 81 − − 100 118 131 71 87 95 21754 21753 IR IR IR IR 60 31 43 58 74 30 72 43 72 88 56 57 43 43 57 74 56 43 43 61 61 41 60 53 54 67 82 94 80 31 44 109 109 108 103 75 42 D m/z D m/z 1) 1) = D > D 1) = D Continued. Continued. NameOVOCs with high degrees ofPropenal_2 unsaturation (Acrolein) ( C3H4O 56 Formula 2 MW Acid_AcrylicAcid_PyruvicButenal_2 (Crotonaldehyde) C4H6O 70 2 C3H4O2 C3H4O3 72 88 2 2 Methacrolein (MACR) C4H6O 70 2 Methylvinylketone (MVK) C4H6O 70 2 Butadione_23 C4H6O2 86 2 Acrylate_methyl (2-Propenoic Acid, methyl ester) C4H6O2 86 2 Acetate_vinyl (Acetic Acid, vinyl ester) C4H6O2 86 2 Dioxin_14_23dihydro C4H6O2 86 2 Cyclopentenedione C5H4O2 96 4 Cyclopentenone C5H6O 82 3 Pentenone (e.g., Ethyl vinyl ketone) C5H8O 84 2 Pentanone_cyclo C5H8O 84 2 Butenal_2_2methyl C5H8O 84 2 Methacrylate_methyl (Methacrylic Acid, methyl ester)Phenol C5H8O2 100 2 C6H6O 94 4 Benzene_12&13diol (sum of 2 isomers)Benzaldehyde C6H6O2 110 4 C7H6O 106 5 Phenol_methyl (sum of cresol isomers’) C7H8O 108 4 Furans (heterocyclic OVOCs, Furan C4H4O 68 3 Furan_25dihydro C4H6O 70 2 Furan_tetrahydro C4H8O 72 1 Furaldehyde_2 (Furfural)Furaldehyde_3 C5H4O2 96 4 C5H4O2 96 4 Furan_2methylFuran_3methyl C5H6O C5H6O 82 82 3 3 Furan_25dimethyl C6H8O 96 3 Furan_2ethyl C6H8O 96 3 BenzofuranBenzofuran_methyl (sum of 4 isomers) C9H8O 132 6 C8H6O 118 6 AcetonePropanalAcetate_methyl (Acetic Acid, methyl ester)Butanone_2 (MEK)Propanal_2methyl C3H6O2 74 1 Hexanone_2 C3H6O C3H6O C4H8O C4H8O 58 58 1 72 1 72 1 1 C6H12O 100 1 Formate_methyl (Formic Acid, methyl ester)Acid_GlycolicEthanol C2H4O2Formate_ethyl (Formic Acid, ethyl 60 ester)Butanal_n 1 Propanoate_methyl (Prop- anoic Acid, methylButanol_1 ester)Butanal_2methyl C4H8O2 C3H6O2Butanone_2_3methylPentanone_2 88 74Pentanone_3 1 1 Butanoate_methyl C2H4O3 (Butryic Acid, methyl ester)Hexanal_n 76Hexanone_3 C2H6O 1 C5H10O2 102 46 1 0 C4H8O C5H10O 72 C5H10O 1 86 C4H10O 86 1 1 C5H10O 74 C5H10O 0 86 86 1 C6H12O 1 C6H12O 100 1 100 1 NitromethaneHydrazine_11dimethylPropanenitrile (Cyanoethane) C3H5N C2H8N2 CH3NO2 60 55Acetaldehyde 61Acid_Acetic 0 2 1 C2H4O C2H4O2 44 1 60 1 Acid_IsocyanicMethylnitrite (Nitrous acid, methyl ester)AcetonitrilePropenenitrile_2 (Acrylonitrile)Pyrrole CH3NO2Pyrazole_1methylDiazine_methyl 61 (sum of 3 isomers)Pyrrole_1methyl 1 Pyrazine_2ethylBenzonitrile (Cyanobenzene)OVOCs with C3H3N low HNCO degrees ofFormaldehyde unsaturation ( 53Methanol C5H6N2 43 3 2 C2H3N 94 4 C4H6N2 41 C7H5N 2 82 103 C5H7N C4H5N 3 6 C6H8N2 81 108 67 3 4 3 CH2O 30 CH4O 1 32 0 NameNitrogen-containing organics Acid_Hydrocyanic (Hydrogen cyanide) HCN 27 2 Formula MW Acid_Formic CH2O2 46 1 Table 2. Table 2. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | b CN cient 3 ffi 4 4 4 2 4 4 4 4 4 Oxy Unsat vs. CH (0) SD) npnts 84 % 54 % ± 0.78 % VOC 0.37 % N a (14000) 4 (24.243) (28.737) ) denotes OH + 81 71 126 150 k 1000 4.9468.408 (5.254) 0.472 (5.347) (0.719) 17999 0.004420.761 (0.0042) 26.530 (16.928) 10.583 (10.218) 96.707 16 23 23 17 23 23 23 23 23 Oxy Unsat (0) SD) npnts N Avg ( 63 % 82 % ± 0.28 % VOC 0.24 % N (71256) 23 (91.842) (32.218) 57 74 90 77 1000 4.5637.901 (6.049) 1.398 (14.488) (4.825) 31170 0.004014.797 (0.0055) 39.695 (6.131) 12.254 (21.246) 62.302 number of points used to calculate average and = 9 29 29 29 16 29 29 29 29 Oxy Unsat OH reaction at STP. + BB Urban Biogenic (0) SD) npnts SE Avg ( 53 % 84 % at STP. ± 0.24 % VOC 0.34 % N r (20970) 29 (51.194) (24.945) 12 ) for VOC to carbon monoxide (CO) and VOC mass fragment used to quantify a species where ( CN Emission Sources Rxn Rate Coe r = 10 3 24 39 46 65 × 1000 21756 21755 7.0512.504 (8.565) 5.600 (2.827) 0.992 (9.993) (2.574) 18202 19356 32403 19317 m/z 12.53038.788 (8.838) 0.0024 (0.0030) 40.911 cient of VOC SW Avg ( ffi CN) 3 standard deviation; and npts − IR IR IR IR IR IR IR IR 68 = 46 cients ( ) 1 ffi − D m/z Slope mean; SD ) denotes measurements by the NI-PT-CIMS, and (IR) denotes measurements by the OP-FTIR. = − r Degrees of unsaturation; = D ); % of total VOC % of total VOC 1 − first order reaction rate coe ) 1 Slope − = 0.0003 0.88 0.04700.0004 0.70 0.95 0.1153 yes 0.950.0003 yes 0.930.0001 0.0491 0.97 0.0210 0.98 yes 0.99 yes0.0003 0.97 0.0415 111 0.97 67 yes0.0003 5550 0.88 0.04990.0062 0.96 3355 48 0.94 1.0000 yes 37 yes 1.00 yes 2400 1860 15 750 1.0 0.020 50 1 % of total emissions CN) ratios observed in biomass burning (BB) plumes from the Fourmile 12 largest 3 ERs for all VOCs. 3 = 10 cients for VOC vs. acetonitrile (CH × ffi largest 3 ERs for each compound class. cient = ffi c molecular weight (gmol = Slopes and correlation coe ERs for oxygenated VOCs and ERs for unsaturated VOCs and ERs for all VOCs and ERs for all nitrogen-containing species (mmol(molCO) Continued. P P P Tricarbon Dioxide (Carbon suboxide)Ammonia C3O2Nitrogen OxideNitrogen Dioxide 68Sulfur Dioxide - Hydrochloric AcidTotal ERs (mmol (mol CO) NO NO2 NH3 HCl 46 30 SO2 17 - - - 36 64 - - P Carbon DioxideNitrous Acid CO2 44 - HONO 47 - NameMethane and Inorganic Gases MethaneCarbon Monoxide CO Formula MW CH4 28 - 16 - standard deviation. Bold ER Bold and italic ER Description of naming scheme: propane_22dimethyldetermined, is then equivalent the to species 2,2-dimethylpropane. are(sum If identified of the using 3 exact general isomers) compound names may identity1-methyl-4-isopropylbenzene, that include or could reflect species common not the such abbreviations be chemical such as family as cis- and MEK and formula for trans-3-hexene. Alternative are Butanone_2 names, used. are such For also example, as included. hexenes p-Cymene for All other measurements are by GC-MS; avg measurements by the PTR-MS or PIT-MS, ( MW face denotes VOCs that are the best available BB markers. Rxn Rate Coe Ratio of rxn rate coe Benzene_1methyl_4isopropyl. VOC NameFuran_2methyl Carene_3 VOC vs. COFuran Butadiene_13 VOC vs. CH StyrenePropene_2methyl 0.0004 0.0002Furaldehyde_2 0.96 0.0004 0.98Benzofuran 0.0654 0.98 0.0296Butene_1 0.0648Propene 0.0001 0.98 0.94Propanal 0.97 yes 0.98 yesPropenal_2 0.0209 yes yesp-Cymene yes 0.0004Benzaldehyde 0.94 0.98 0.0040Ethene yes 0.0571 yes 0.0010 0.0009 0.97Benzene yes 0.95 0.98 0.0010 0.6385Butanone_2 (MEK) 0.99 0.1481 0.1366 0.98Benzonitrile yes 0.0010 yes 0.99 0.1444Butadione_23 0.93 yes 0.90 85 0.98 yesAcetonitrile 67 0.1640 0.0082 yes yes 0.95 51 yes 0.0019 0.97 yes yes yes 0.99 0.0002 0.94 58 1.3526 0.2835 0.77 yes 4250 3330 0.0384 yes 0.92 2570 0.96 yes yes 2900 0.89 yes yes yes yes 31 yes 26 20 19 1.2 14 1570 yes 1315 1000 955 8.5 1.2 700 0.25 60 425 12.5 60 Bold a c b Table 3. to acetonitrile (CH Canyon Fire as identified in Fig. 6. Table 2. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | other, mixing + (a) furan + isoprene = 0.90. 69 , CO, and NOx measured by 2 r > m/z discrete vs. fire-integrated emission (b) , determined from correlation plots of r Mixing ratios of CO 21758 21757 (a) cients, ffi Discrete GC-MS measured mixing ratios are shown as mark- ciency (MCE) for an example laboratory burn of Emory Oak Wood- (b–f) ffi Mixing ratios measured by PTR-MS (benzene, Temporal profiles of mixing ratios and emission ratios (ER) of select gases and the Slopes and correlation coe (b–g) and acetonitrile), OP-FTIR (furan,shown ethyne, as and lines and methanol), the and corresponding NI-PT-CIMS VOC (benzenediol) to are CO ERs are shown as filled traces. Figure 2. ratios of selectdashed VOCs line represents relative slopes to equalis to CO 1. shown The by as average the of measured red the shaded slopes by bands. and the The the standard green OP-FTIR deviation bands represent or PTR-MS. The black ratios measured by the GC-MSMS vs. the during average mixing the ratio measured GC-MS by sample the OP-FTIR acquisition or PTR- time and Figure 1. modified combustion e land fuel from Fort Huachuca, Arizona. ers. OP-FTIR. The MCE traceresent is the colored flaming by combustion theacquisition phase key time of and (grey). the scale laboratory on the burn right. (yellow) The and vertical the bars GC-MS rep- sample Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ciency ffi 21760 21759 2). The histogram on the right summarizes the distribu- = D CO and , for each fuel region. Emission ratios are colored by the correspond- 1 D − Discrete molar emission ratios for all VOCs reported in Table 2 as a function of the Correlation plots of the discrete vs. fire-integrated emission ratios (ER) for ethyne and 0.0427 mmolmol = tion of molar emission ratios for each fuel region. ing molecular weight and(O) the atoms. marker The width dashed(ER lines represents represent the the corresponding median number values of for oxygen all VOCs from all fuel regions Figure 4. degree of unsaturation, Figure 3. methanol measured by the OP-FTIR anddata benzene point and represents toluene measured one by biomass the(MCE) burn PTR-MS. corresponding Each and are to colored theare by the associated discrete modified with combustion sampling flaming e combustion timescombustion. and lower The of MCE linear the values are 2-sided GC-MS.lines associated and MCE regression with the smoldering lines values 1 : near forced 1 through unity ratio is the shown origin by the are dashed shown lines. as red Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | the molar mass (a–c) 21762 21761 relative SOA potential for the southwestern, southeast- (g–i) OH reactivity, and Contributions of (non-methane) VOCs reported in Table 2 to Time series of ambient air measurements in Boulder, Colorado, during the Fourmile (d–f) Figure 6. Canyon Fire. The topplumes (red bar markers). indicates CO and nighttime acetonitrile (grey), are daytime included in (yellow), all and 4 panels. biomass burning emitted, Figure 5. ern, and northern fuel regions. Totals for each fuel region are shown below each pie chart. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 21763 Correlation plots of VOCs vs. acetonitrile for all 56 laboratory biomass burns (grey Figure 7. markers) and FourmileFig. Canyon 6). Fire (red markers correspond to the BB plume identified in