American Association for Aerosol Research - Abstract Submission

AAAR 36th Annual Conference
October 16 - October 20, 2017
Raleigh Convention Center
Raleigh, North Carolina, USA

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Similarities and Differences in Aerosol Optical Properties between Smoke from Biomass Burning and Fireworks

CHRISTIAN CARRICO, Samantha Bixler, Caroline Allen, Manvendra Dubey, Allison Aiken, Sanna Sevanto, Thom Rahn, New Mexico Institute of Mining and Technology

     Abstract Number: 204
     Working Group: Carbonaceous Aerosols in the Atmosphere

Abstract
During the summer of 2017, we conducted a laboratory study of biomass burning emissions at Los Alamos National Laboratory, focusing upon Southwestern U.S. fuels and invasive species in particular. Parallel sampling of ambient air during interim periods showed a clear episode of smoke from fireworks displays associated with the Independence Day holiday. These measurements were focused upon aerosol optical properties and included measurements with a photoacoustic extinctiometer (PAX, DMT, Inc., Model 870nm) and a custom controlled relative humidity nephelometry system (Ecotech, Inc., 450nm Aurora) to measure aerosol hygroscopic response. Fresh biomass smoke emissions showed hygroscopicity ranging from shrinkage to light scattering growth factors exceeding two. The primary driver was the fuel species and its chemical composition, in particular its inorganic salt content, with a secondary effect of combustion efficiency. During the fireworks smoke-dominated period on Independence Day, ambient aerosol hygroscopic response declined to ~one at the peak of the event. Peak light scattering coefficient reached approximately 120 Mm-1, the highest value during the summer and well above the typical background here of ~10 Mm-1. The aerosol single scattering albedo was approximately 0.9, suggesting the aerosol was not dominated black carbon but more so brown carbon species with little water affinity. Lab testing with several sparkler types showed that pyrotechnics smoke can have a strong hygroscopic response, however; again, the fuel was key, as sparklers contain salt species such as potassium and lack the black powder explosives in aerial fireworks. The comparison here yields useful observations on the nature of combustion aerosol properties on atmospheric light extinction.