Skip common site navigation and headers
United States Environmental Protection Agency
Exposure Research
Begin Hierarchical Links EPA Home > Research & Development > Exposure Research > Publications/Presentations > End Hierarchical Links

 

Investigating Oxidation Mechanisms of Hg0 in the Free Troposphere and Its Influence on Long Range Mercury Transport

spacer
spacer
Abstract:In 2000, the US EPA Office of Research and Development (ORD) initiated a study to evaluate the magnitude of long-range transport of mercury through the marine free troposphere to South Florida via aircraft measurements (200 to 12,000 feet). ORD funded the National Oceanic and Atmospheric Administration (NOAA) to provide a DeHavilland Twin Otter aircraft and personnel to collaborate with the collection of aerosol and trace gas measurements. One study period was conducted from January 18, through February 1, 2000 when the tropospheric winds typically transport air to South Florida from the Gulf of Mexico and the North American continent. Flights for a second study period were conducted from June 3 through June 26, 2000 when South Florida is predominantly influenced from easterly marine transport. Preliminary results from the flights indicate that mercury concentrations were significantly higher within air masses with continental influence. The Hg0 concentrations were observed to be higher below 5000 feet (2.3 +/- 0.4 ng m-3 ) than above 5000 feet (1.5 +/- 0.4 ng m-3). Conversely, the concentrations of Hg2+ were typically higher above 5000 feet (49 +/- 28 pg m-3) than below (12 +/- 7 pg m-3).

ORD subsequently initiated speciated mercury measurements at the NOAA Mauna Loa Observatory (MLO), a high altitude research station (~11,500 feet) in 2001. Observations at MLO are consistent with the aircraft results suggesting that there is a significant Hg0 oxidation mechanism at altitude. These observations are not consistent with the contemporary conceptual atmospheric mercury model that estimates the Hg0 atmospheric lifetime to be approximately 1 year. Meteorological modeling and chemical tracer results will also be presented to investigate the importance of trans-Atlantic and trans-Pacific transport of mercury species.

This work has been funded wholly or in part by the United States Environmental Protection Agency Office of Research and Development. It has been subjected to peer review and approved for publication.
spacer
Citation:Landis, M. S. Investigating Oxidation Mechanisms of Hg0 in the Free Troposphere and Its Influence on Long Range Mercury Transport. Presented at Fourth SETAC World Congress, Portland, OR, November 14-18, 2004.
spacer
spacer
Contact: Liz Hope - (919) 541-2785 or hope.elizabeth@epa.gov
spacer
Division: Human Exposure & Atmospheric Sciences Division
spacer
Branch: Environmental Characterization & Apportionment Branch
spacer
Product Type: Abstrct/Oral
spacer
Presented: 11/16/2004
spacer
Related Entries:
spacer
Bullet Item Atmospheric Mercury Research
spacer Relationship Reason:   A Project of the Product
spacer
spacer
spacer

 

ORD Home | Search EPA | Search NERL | Search EIMS | Contacts | Help

 
Begin Site Footer

EPA Home | Privacy and Security Notice | Contact Us

Last Updated on Monday, October 22, 2007
URL: http://cfpub.epa.gov