Preprints
https://doi.org/10.5194/egusphere-2022-879
https://doi.org/10.5194/egusphere-2022-879
 
01 Nov 2022
01 Nov 2022
Status: this preprint is open for discussion.

Measurement report: Emission factors of NH3 and NHx for wildfires and agricultural fires in the United States

Laura Tomsche1,2,3,a, Felix Piel4,5,6, Tomas Mikoviny5, Claus J. Nielsen5, Hongyu Guo7, Pedro Campuzano-Jost7, Benjamin A. Nault8, Melinda K. Schueneman7, Jose L. Jimenez7, Hannah Halliday9, Glenn S. Diskin2, Joshua P. DiGangi2, John B. Nowak2, Elizabeth B. Wiggins1,2, Emily Gargulinski10, Amber J. Soja2,10, and Armin Wisthaler4,6 Laura Tomsche et al.
  • 1Universities Space Research Association, Columbia, MD, USA
  • 2NASA Langley Research Center, Hampton, VA, USA
  • 3Institute of Atmospheric Physics, German Aerospace Center, Oberpfaffenhofen, Germany
  • 4Department of Chemistry, University of Oslo, Oslo, Norway
  • 5Department of Chemistry, University of Oslo, Oslo, Norway
  • 6Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
  • 7Department of Chemistry and Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, CO, USA
  • 8Center for Aerosol and Cloud Chemistry, Aerodyne Research, Inc., Billerica, MA, USA
  • 9US Environmental Protection Agency, Durham, NC, USA
  • 10National Institute of Aerospace, Hampton, VA, USA
  • anow at: Institute of Atmospheric Physics, Johannes-Gutenberg University Mainz, Mainz, Germany

Abstract. During the 2019 Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) study, the NASA DC-8 carried out in situ chemical measurements in smoke plumes emitted from wildfires and agricultural fires in the contiguous US. The DC-8 payload included a modified proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) for the fast measurement of gaseous ammonia (NH3) and a high-resolution time-of-flight aerosol mass spectrometer (AMS) for the fast measurement of submicron particulate ammonium (NH4+). We herein report data collected in smoke plumes emitted from six wildfires in the Western US, two prescribed grassland fires in the Central US, one prescribed forest fire in the Southern US, and 66 small agricultural fires in the Southeastern US. Smoke plumes contained double to triple digit ppb levels of NH3. In the wildfire plumes, a significant fraction of NH3 had already been converted to NH4+ at the time of sampling (≥2 h after emission). Substantial amounts of NH4+ were also detected in freshly emitted smoke from corn and rice field fires. We herein present a comprehensive set of emission factors of NH3 and NHx, with NHx = NH3 + NH4+. Average NH3 and NHx emission factors for wildfires in the Western US were 1.86 ± 0.75 g kg-1 of fuel burned and 2.47 ± 0.80 g kg-1, respectively. Average NH3 and NHx emission factors for agricultural fires in the Southeastern US were 0.89 ± 0.58 g kg-1 and 1.74 ± 0.92 g kg-1, respectively. Our data show no clear inverse correlation between modified combustion efficiency (MCE) and NH3 emissions. Importantly, we found that NH3 emissions in ambient sampling were significantly higher than observed in previous laboratory experiments with similar fuel types.

Laura Tomsche et al.

Status: open (until 26 Dec 2022)

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Laura Tomsche et al.

Data sets

Fire Influence on Regional to Global Environments and Air Quality NASA https://doi.org/10.5067/SUBORBITAL/FIREXAQ2019/DATA001

Laura Tomsche et al.

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Short summary
Ammonia (NH3) is an important trace gas in the atmosphere and fires are among the poorly investigated sources. During the FIREX-AQ aircraft campaign in 2019, we measured gaseous ammonia and particulate ammonium (NH4+) in smoke plumes emitted from six wildfires in the Western US and 66 small agricultural fires in the Southeastern US. We herein present a comprehensive set of emission factors of NH3 and NHx, with NHx = NH3 + NH4+.