Particulate Matter, Ozone, and Nitrogen Species in Aged Wildfire Plumes Observed at the Mount Bachelor Observatory

Journal Article · Fri Jan 01 00:00:00 EST 2016 · Aerosol and Air Quality Research

DOI:https://doi.org/10.4209/aaqr.2016.03.0120· OSTI ID:1425944

Briggs, Nicole L. ^[1]; Jaffe, Daniel A. ^[2]; Gao, Honglian ^[3]; Hee, Jonathan R. ^[3]; Baylon, Pao M. ^[2]; Zhang, Qi ^[4]; Zhou, Shan ^[4]; Collier, Sonya C. ^[4]; Sampson, Paul D. ^[5]; Cary, Robert A. ^[6]

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1. Gradient, Seattle, WA (United States); Univ. of Washington, Seattle, WA (United States). Dept. of Atmospheric Sciences
2. Univ. of Washington, Bothell, WA (United States). School of Science, Technology, Engineering and Mathematics; Univ. of Washington, Seattle, WA (United States). Dept. of Atmospheric Sciences
3. Univ. of Washington, Bothell, WA (United States). School of Science, Technology, Engineering and Mathematics
4. Univ. of California, Davis, CA (United States). Dept. of Environmental Toxicology
5. Univ. of Washington, Seattle, WA (United States). Dept. of Statistics
6. Sunset Lab., Inc., Tigard, OR (United States)

During the summer of 2012 and 2013, we measured carbon monoxide (CO), carbon dioxide (CO₂), ozone (O₃), nitrogen oxides (NO_x), reactive nitrogen (NO_y), peroxyacetyl nitrate (PAN), aerosol scattering (σ_sp) and absorption, elemental and organic carbon (EC and OC), and aerosol chemistry at the Mount Bachelor Observatory (2.8 km above sea level, Oregon, US). Here we analyze 23 of the individual plumes from regional wildfires to better understand production and loss of aerosols and gaseous species. We also developed a new method to calculate enhancement ratios and Modified Combustion Efficiency (MCE), which takes into account possible changes in background concentrations during transport. We compared this new method to existing methods for calculating enhancement ratios. The MCE values ranged from 0.79– 0.98, ΔO₃/ΔCO ranged from 0.01–0.07 ppbv ppbv^–1, Δσ_sp/ΔCO ranged from 0.23–1.32 Mm^–1 (at STP) ppbv^–1, ΔNO_y/ΔCO ranged from 2.89–12.82 pptv ppbv^–1, and ΔPAN/ΔCO ranged from 1.46–6.25 pptv ppbv–1. A comparison of three different methods to calculate enhancement ratios (ER) showed that the methods generally resulted in similar Δσ_sp/ΔCO, ΔNO_y/ΔCO, and ΔPAN/ΔCO; however, there was a significant bias between the methods when calculating ΔO₃/ΔCO due to the small absolute enhancement of O₃ in the plumes. The ΔO₃/ΔCO ERs calculated using two common methods were biased low (~20–30%) when compared to the new proposed method. Two pieces of evidence suggest moderate secondary particulate formation in many of the plumes studied: 1) mean observed ΔOC/ΔCO₂ was 0.028 g particulate-C gC^–1 (as CO₂)—27% higher than the midpoint of the biomass burning emission ratio range reported by a recent review—and 2) single scattering albedo (ω) was relatively constant at all MCE values, in contrast with results for fresh plumes. Lastly, the observed NO_x, PAN, and aerosol nitrate represented 6–48%, 25–57%, and 20–69% of the observed NOy in the aged plumes, respectively, and other species represented on average 11% of the observed NO_y.

• Research Organization: Univ. of California, Davis, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Biological and Environmental Research (BER)
• Grant/Contract Number: SC0014620
• OSTI ID: 1425944
• Journal Information: Aerosol and Air Quality Research, Vol. 16, Issue 12; ISSN 1680-8584
• Publisher: Chinese Association for Aerosol Research in Taiwan
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
Particulate matter
Ozone
NOy
Enhancement ratio
Modified Combustion Efficiency