Agricultural fires in the southeastern U.S. during SEAC⁴RS: Emissions of trace gases and particles and evolution of ozone, reactive nitrogen, and organic aerosol
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Date
2016-05-28
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Citation of Original Publication
Liu, X., et al. (2016), Agricultural fires inthe southeastern U.S. during SEAC⁴RS:Emissions of trace gases and particlesand evolution of ozone, reactive nitro-gen, and organic aerosol, J. Geophys.Res. Atmos., 121, 7383–7414,doi:10.1002/2016JD025040
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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
Public Domain Mark 1.0
This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Abstract
Emissions from 15 agricultural fires in the southeastern U.S. were measured from the NASA DC‐8 research aircraft during the summer 2013 Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC⁴RS) campaign. This study reports a detailed set of emission factors (EFs) for 25 trace gases and 6 fine particle species. The chemical evolution of the primary emissions in seven plumes was examined in detail for ~1.2 h. A Lagrangian plume cross‐section model was used to simulate the evolution of ozone (O₃), reactive nitrogen species, and organic aerosol (OA). Observed EFs are generally consistent with previous measurements of crop residue burning, but the fires studied here emitted high amounts of SO₂ and fine particles, especially primary OA and chloride. Filter‐based measurements of aerosol light absorption implied that brown carbon (BrC) was ubiquitous in the plumes. In aged plumes, rapid production of O₃, peroxyacetyl nitrate (PAN), and nitrate was observed with ΔO₃/ΔCO, ΔPAN/ΔNOy, and Δnitrate/ΔNOy reaching ~0.1, ~0.3, and ~0.3. For five selected cases, the model reasonably simulated O₃ formation but underestimated PAN formation. No significant evolution of OA mass or BrC absorption was observed. However, a consistent increase in oxygen‐to‐carbon (O/C) ratios of OA indicated that OA oxidation in the agricultural fire plumes was much faster than in urban and forest fire plumes. Finally, total annual SO₂, NOₓ , and CO emissions from agricultural fires in Arkansas, Louisiana, Mississippi, and Missouri were estimated (within a factor of ~2) to be equivalent to ~2% SO₂ from coal combustion and ~1% NOₓ and ~9% CO from mobile sources.