Persistent Influence of Wildfire Emissions in the Western United States and Characteristics of Aged Biomass Burning Organic Aerosols under Clean Air Conditions

Ryan Farley, Noah Bernays, Daniel A. Jaffe, Damien Ketcherside, Lu Hu, Shan Zhou, Sonya Collier, Qi Zhang

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Wildfire-influenced air masses under regional background conditions were characterized at the Mt. Bachelor Observatory (∼2800 m a.s.l.) in summer 2019 to provide a better understanding of the aging of biomass burning organic aerosols (BBOAs) and their impacts on the remote troposphere in the western United States. Submicron aerosol (PM1) concentrations were low (average ± 1σ = 2.2 ± 1.9 μg sm-3), but oxidized BBOAs (average O/C = 0.84) were constantly detected throughout the study. The BBOA correlated well with black carbon, furfural, and acetonitrile and comprised above 50% of PM1 during plume events when the peak PM1 concentration reached 18.0 μg sm-3. Wildfire plumes with estimated transport times varying from ∼10 h to >10 days were identified. The plumes showed ΔOA/ΔCO values ranging from 0.038 to 0.122 ppb ppb-1 with a significant negative relation to plume age, indicating BBOA loss relative to CO during long-range transport. Additionally, increases of average O/C and aerosol sizes were seen in more aged plumes. The mass-based size mode was approximately 700 nm (Dva) in the most oxidized plume that likely originated in Siberia, suggesting aqueous-phase processing during transport. This work highlights the widespread impacts that wildfire emissions have on aerosol concentration and properties, and thus climate, in the western United States.

Original languageEnglish
Pages (from-to)3645-3657
Number of pages13
JournalEnvironmental Science and Technology
Volume56
Issue number6
DOIs
StatePublished - Mar 15 2022

Keywords

  • aerosol mass spectrometry
  • atmospheric aging
  • biomass burning organic aerosols (BBOAs)
  • long-range transport
  • soot-particle aerosol mass spectrometer (SP-AMS)
  • submicrometer aerosols (PM)

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