Midlatitude Ozone Depletion and Air Quality Impacts from Industrial Halogen Emissions in the Great Salt Lake Basin

• Published in: Environmental science & technology 2023-02, Vol.57 (5), p.1870-1881
• Main Authors: Womack, Caroline C., Chace, Wyndom S., Wang, Siyuan, Baasandorj, Munkhbayar, Fibiger, Dorothy L., Franchin, Alessandro, Goldberger, Lexie, Harkins, Colin, Jo, Duseong S., Lee, Ben H., Lin, John C., McDonald, Brian C., McDuffie, Erin E., Middlebrook, Ann M., Moravek, Alexander, Murphy, Jennifer G., Neuman, J. Andrew, Thornton, Joel A., Veres, Patrick R., Brown, Steven S.
• Format: Article
• Language: English
• Subjects: Aerosol chemistry; Air Pollutants - analysis; Air Pollution - analysis; Air quality; Anthropogenic Impacts on the Atmosphere; Bromine; Chemical modeling; Emission inventories; Emissions; Environmental modeling; Group 17 compounds; Halogens; Industrial emissions; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Lake basins; Lakes; Oxidants; Oxidation; Oxidizing agents; Ozone - analysis; Ozone Depletion; Ozone depletion: Air quality; Particulate emissions; Particulate matter; Particulate Matter - analysis; Photochemical oxidants; Photochemicals; Salts; Three dimensional models; Urban areas; Volatile organic compounds
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.2c05376

We report aircraft observations of extreme levels of HCl and the dihalogens Cl2, Br2, and BrCl in an industrial plume near the Great Salt Lake, Utah. Complete depletion of O3 was observed concurrently with halogen enhancements as a direct result of photochemically produced halogen radicals. Observed fluxes for Cl2, HCl, and NO x agreed with facility-reported emissions inventories. Bromine emissions are not required to be reported in the inventory, but are estimated as 173 Mg year–1 Br2 and 949 Mg year–1 BrCl, representing a major uncounted oxidant source. A zero-dimensional photochemical box model reproduced the observed O3 depletions and demonstrated that bromine radical cycling was principally responsible for the rapid O3 depletion. Inclusion of observed halogen emissions in both the box model and a 3D chemical model showed significant increases in oxidants and particulate matter (PM2.5) in the populated regions of the Great Salt Lake Basin, where winter PM2.5 is among the most severe air quality issues in the U.S. The model shows regional PM2.5 increases of 10%–25% attributable to this single industrial halogen source, demonstrating the impact of underreported industrial bromine emissions on oxidation sources and air quality within a major urban area of the western U.S.