Publication Date:
2016-05-29
Description:
Emissions from 15 agricultural fires in the southeastern US were measured from the NASA DC-8 research aircraft during the summer 2013 SEAC 4 RS 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 7 plumes was examined in detail for ~1.2 hr. A Lagrangian plume cross-section model was used to simulate the evolution of ozone (O 3 ), 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 SO 2 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 O 3 , peroxyacetyl nitrate (PAN), and nitrate were observed with ΔO 3 /ΔCO, ΔPAN/ΔNO y , and Δnitrate/ΔNO y reaching ~0.1, ~0.3, and ~0.3. For 5 selected cases, the model reasonably simulated O 3 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 SO 2 , NO x , and CO emissions from agricultural fires in Arkansas, Louisiana, Mississippi, and Missouri were estimated (within a factor of ~2) to be equivalent to ~2% SO 2 from coal combustion and ~1% NO x and ~9% CO from mobile sources.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
Permalink