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Modeling the Atmosphere Formation of Reactive Mercury in Florida and the Great Lakes

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Abstract:Reactive mercury in the troposphere is affected by a complex mix of local emissions, global-scale transport, and gas and aqueous-phase chemistry. Here, we describe a modified version of the EPA model for urban/regional air quality (CMAQ) to include the chemistry of mercury, and model applications focusing on the Great Lakes region and on South Florida. The University of Michigan modifications to CMAQ include an integrated numerical solver for gas-phase and aqueous photochemistry, improved representation of in-cloud photolysis rates, and up-to-date reaction schemes for mercury chemistry. Reactive mercury is produced primarily by gas-phase reactions. Aqueous reactions tend to convert reactive mercury back to its elemental form, but the most important aqueous reactions (with HO2 and O2-) are problematic (Gartfeld and Jonnson, 2003). Model results suggest that gas-phase conversion from elemental to reactive mercury can lead to high concentrations of reactive mercury in the middle troposphere. Reactive mercury in the lower troposphere is removed more rapidly through both wet and dry deposition and potentially through aqueous conversion to elemental mercury. Model results are compared with a suite of comprehensive gas and aerosol measurements performed in Michigan and during aircraft measurements in S. Florida. Model results suggest that direct emission of reactive mercury contribute to atmospheric deposition in source regions.

Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.
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Citation:Sillman, S., F. Marsik, K. I. Alwali, M. S. Landis, and G. J. Keeler. Modeling the Atmosphere Formation of Reactive Mercury in Florida and the Great Lakes. Presented at American Geophysical Union's Fall Meeting, San Francisco, CA, December 13-17, 2004.
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Contact: Liz Hope - (919) 541-2785 or hope.elizabeth@epa.gov
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Division: Human Exposure & Atmospheric Sciences Division
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Branch: Environmental Characterization & Apportionment Branch
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Product Type: Abstrct/Oral
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Presented: 12/15/2004
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Related Entries:
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Bullet Item Atmospheric Mercury Research
spacer Relationship Reason:   A Project of the Product
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Last Updated on Monday, October 22, 2007
URL: http://cfpub.epa.gov