HONO Emissions from Western U.S. Wildfires Provide Dominant Radical Source in Fresh Wildfire Smoke

Qiaoyun Peng; Brett B. Palm; Kira E. Melander; Ben H. Lee; Samuel R. Hall; Kirk Ullmann; Teresa Campos; Andrew J. Weinheimer; Eric C. Apel; Rebecca S. Hornbrook; Alan J. Hills; Denise D. Montzka; Frank Flocke; Lu Hu; Wade Permar; Catherine Wielgasz; Jakob Lindaas; Ilana B. Pollack; Emily V. Fischer; Timothy H. Bertram; Joel A. Thornton

doi:10.1021/acs.est.0c00126

HONO Emissions from Western U.S. Wildfires Provide Dominant Radical Source in Fresh Wildfire Smoke

Qiaoyun Peng, Brett B. Palm, Kira E. Melander, Ben H. Lee, Samuel R. Hall, Kirk Ullmann, Teresa Campos, Andrew J. Weinheimer, Eric C. Apel, Rebecca S. Hornbrook, Alan J. Hills, Denise D. Montzka, Frank Flocke, Lu Hu, Wade Permar, Catherine Wielgasz, Jakob Lindaas, Ilana B. Pollack, Emily V. Fischer, Timothy H. BertramJoel A. Thornton

Chemistry

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58 Scopus citations

Abstract

Wildfires are an important source of nitrous acid (HONO), a photolabile radical precursor, yet in situ measurements and quantification of primary HONO emissions from open wildfires have been scarce. We present airborne observations of HONO within wildfire plumes sampled during the Western Wildfire Experiment for Cloud chemistry, Aerosol absorption and Nitrogen (WE-CAN) campaign. Î"HONO/Î"CO close to the fire locations ranged from 0.7 to 17 pptv ppbv^-1 using a maximum enhancement method, with the median similar to previous observations of temperate forest fire plumes. Measured HONO to NO_x enhancement ratios were generally factors of 2, or higher, at early plume ages than previous studies. Enhancement ratios scale with modified combustion efficiency and certain nitrogenous trace gases, which may be useful to estimate HONO release when HONO observations are lacking or plumes have photochemical exposures exceeding an hour as emitted HONO is rapidly photolyzed. We find that HONO photolysis is the dominant contributor to hydrogen oxide radicals (HO_x = OH + HO₂) in early stage (<3 h) wildfire plume evolution. These results highlight the role of HONO as a major component of reactive nitrogen emissions from wildfires and the main driver of initial photochemical oxidation.

Original language	English
Pages (from-to)	5954-5963
Number of pages	10
Journal	Environmental Science and Technology
Volume	54
Issue number	10
DOIs	https://doi.org/10.1021/acs.est.0c00126
State	Published - May 19 2020

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Peng, Q., Palm, B. B., Melander, K. E., Lee, B. H., Hall, S. R., Ullmann, K., Campos, T., Weinheimer, A. J., Apel, E. C., Hornbrook, R. S., Hills, A. J., Montzka, D. D., Flocke, F., Hu, L., Permar, W., Wielgasz, C., Lindaas, J., Pollack, I. B., Fischer, E. V., ... Thornton, J. A. (2020). HONO Emissions from Western U.S. Wildfires Provide Dominant Radical Source in Fresh Wildfire Smoke. Environmental Science and Technology, 54(10), 5954-5963. https://doi.org/10.1021/acs.est.0c00126

@article{dd93e05e67c4484b8d042b12497b3dbc,

title = "HONO Emissions from Western U.S. Wildfires Provide Dominant Radical Source in Fresh Wildfire Smoke",

abstract = "Wildfires are an important source of nitrous acid (HONO), a photolabile radical precursor, yet in situ measurements and quantification of primary HONO emissions from open wildfires have been scarce. We present airborne observations of HONO within wildfire plumes sampled during the Western Wildfire Experiment for Cloud chemistry, Aerosol absorption and Nitrogen (WE-CAN) campaign. {\^I}{"}HONO/{\^I}{"}CO close to the fire locations ranged from 0.7 to 17 pptv ppbv-1 using a maximum enhancement method, with the median similar to previous observations of temperate forest fire plumes. Measured HONO to NOx enhancement ratios were generally factors of 2, or higher, at early plume ages than previous studies. Enhancement ratios scale with modified combustion efficiency and certain nitrogenous trace gases, which may be useful to estimate HONO release when HONO observations are lacking or plumes have photochemical exposures exceeding an hour as emitted HONO is rapidly photolyzed. We find that HONO photolysis is the dominant contributor to hydrogen oxide radicals (HOx = OH + HO2) in early stage (<3 h) wildfire plume evolution. These results highlight the role of HONO as a major component of reactive nitrogen emissions from wildfires and the main driver of initial photochemical oxidation.",

author = "Qiaoyun Peng and Palm, {Brett B.} and Melander, {Kira E.} and Lee, {Ben H.} and Hall, {Samuel R.} and Kirk Ullmann and Teresa Campos and Weinheimer, {Andrew J.} and Apel, {Eric C.} and Hornbrook, {Rebecca S.} and Hills, {Alan J.} and Montzka, {Denise D.} and Frank Flocke and Lu Hu and Wade Permar and Catherine Wielgasz and Jakob Lindaas and Pollack, {Ilana B.} and Fischer, {Emily V.} and Bertram, {Timothy H.} and Thornton, {Joel A.}",

note = "Publisher Copyright: {\textcopyright} 2020 American Chemical Society.",

year = "2020",

month = may,

day = "19",

doi = "10.1021/acs.est.0c00126",

language = "English",

volume = "54",

pages = "5954--5963",

journal = "Environmental Science and Technology",

issn = "0013-936X",

publisher = "American Chemical Society",

number = "10",

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Peng, Q, Palm, BB, Melander, KE, Lee, BH, Hall, SR, Ullmann, K, Campos, T, Weinheimer, AJ, Apel, EC, Hornbrook, RS, Hills, AJ, Montzka, DD, Flocke, F, Hu, L, Permar, W, Wielgasz, C, Lindaas, J, Pollack, IB, Fischer, EV, Bertram, TH & Thornton, JA 2020, 'HONO Emissions from Western U.S. Wildfires Provide Dominant Radical Source in Fresh Wildfire Smoke', Environmental Science and Technology, vol. 54, no. 10, pp. 5954-5963. https://doi.org/10.1021/acs.est.0c00126

TY - JOUR

T1 - HONO Emissions from Western U.S. Wildfires Provide Dominant Radical Source in Fresh Wildfire Smoke

AU - Peng, Qiaoyun

AU - Palm, Brett B.

AU - Melander, Kira E.

AU - Lee, Ben H.

AU - Hall, Samuel R.

AU - Ullmann, Kirk

AU - Campos, Teresa

AU - Weinheimer, Andrew J.

AU - Apel, Eric C.

AU - Hornbrook, Rebecca S.

AU - Hills, Alan J.

AU - Montzka, Denise D.

AU - Flocke, Frank

AU - Hu, Lu

AU - Permar, Wade

AU - Wielgasz, Catherine

AU - Lindaas, Jakob

AU - Pollack, Ilana B.

AU - Fischer, Emily V.

AU - Bertram, Timothy H.

AU - Thornton, Joel A.

PY - 2020/5/19

Y1 - 2020/5/19

N2 - Wildfires are an important source of nitrous acid (HONO), a photolabile radical precursor, yet in situ measurements and quantification of primary HONO emissions from open wildfires have been scarce. We present airborne observations of HONO within wildfire plumes sampled during the Western Wildfire Experiment for Cloud chemistry, Aerosol absorption and Nitrogen (WE-CAN) campaign. Î"HONO/Î"CO close to the fire locations ranged from 0.7 to 17 pptv ppbv-1 using a maximum enhancement method, with the median similar to previous observations of temperate forest fire plumes. Measured HONO to NOx enhancement ratios were generally factors of 2, or higher, at early plume ages than previous studies. Enhancement ratios scale with modified combustion efficiency and certain nitrogenous trace gases, which may be useful to estimate HONO release when HONO observations are lacking or plumes have photochemical exposures exceeding an hour as emitted HONO is rapidly photolyzed. We find that HONO photolysis is the dominant contributor to hydrogen oxide radicals (HOx = OH + HO2) in early stage (<3 h) wildfire plume evolution. These results highlight the role of HONO as a major component of reactive nitrogen emissions from wildfires and the main driver of initial photochemical oxidation.

AB - Wildfires are an important source of nitrous acid (HONO), a photolabile radical precursor, yet in situ measurements and quantification of primary HONO emissions from open wildfires have been scarce. We present airborne observations of HONO within wildfire plumes sampled during the Western Wildfire Experiment for Cloud chemistry, Aerosol absorption and Nitrogen (WE-CAN) campaign. Î"HONO/Î"CO close to the fire locations ranged from 0.7 to 17 pptv ppbv-1 using a maximum enhancement method, with the median similar to previous observations of temperate forest fire plumes. Measured HONO to NOx enhancement ratios were generally factors of 2, or higher, at early plume ages than previous studies. Enhancement ratios scale with modified combustion efficiency and certain nitrogenous trace gases, which may be useful to estimate HONO release when HONO observations are lacking or plumes have photochemical exposures exceeding an hour as emitted HONO is rapidly photolyzed. We find that HONO photolysis is the dominant contributor to hydrogen oxide radicals (HOx = OH + HO2) in early stage (<3 h) wildfire plume evolution. These results highlight the role of HONO as a major component of reactive nitrogen emissions from wildfires and the main driver of initial photochemical oxidation.

UR - http://www.scopus.com/inward/record.url?scp=85084937164&partnerID=8YFLogxK

U2 - 10.1021/acs.est.0c00126

DO - 10.1021/acs.est.0c00126

M3 - Article

C2 - 32294377

AN - SCOPUS:85084937164

SN - 0013-936X

VL - 54

SP - 5954

EP - 5963

JO - Environmental Science and Technology

JF - Environmental Science and Technology

IS - 10

ER -

HONO Emissions from Western U.S. Wildfires Provide Dominant Radical Source in Fresh Wildfire Smoke

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