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 language | English |
|---|---|
| Pages (from-to) | 3645-3657 |
| Number of pages | 13 |
| Journal | Environmental Science and Technology |
| Volume | 56 |
| Issue number | 6 |
| DOIs | |
| State | Published - Mar 15 2022 |
Funding
This research was supported by the U.S. National Science Foundation (Grant #AGS-1829803 to UC Davis and 1650275 to U Montana), the U.S. Department of Energy’s Atmospheric System Research Program (Grant #DE-SC0014620 and DE-SC0022140), and the California Agricultural Experiment Station (Project CA-D-ETX-2102-H). R.F. also acknowledges funding from the Jastro-Shields Research Award and the Matsumura Memorial Fellowship from the University of California at Davis. The authors thank Wade Permar, Ahsan Mozaffar, and Dr. Joel Thornton for their help during the field deployment. The Mt. Bachelor Observatory is supported by the National Science Foundation (grant #AGS-1447832) and the National Oceanic and Atmospheric Administration (contract #RA-133R-16-SE-0758).
| Funders | Funder number |
|---|---|
| -1829803, #AGS-1447832 | |
| -SC0014620, DE-SC0022140 | |
| National Oceanic and Atmospheric Administration | -133R-16-SE-0758 |
| University of California Division of Agriculture and Natural Resources | CA-D-ETX-2102-H |
| University of California at Davis | 1650275 |
Keywords
- aerosol mass spectrometry
- atmospheric aging
- biomass burning organic aerosols (BBOAs)
- long-range transport
- soot-particle aerosol mass spectrometer (SP-AMS)
- submicrometer aerosols (PM)
