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The Monitoring and Modeling of Mercury Species in Support of Local, Regional, and Global Modeling

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Abstract: Cyrill Brosset, as early as 1979, recognized through research on the chemical forms of mercury in rain and in the air in Sweden and the Baltic States that (i) coal fired utility boilers in Eastern Europe were sources of mercury contaminating lakes in Sweden, and (ii) that both elemental and mercury halides (e.g., HgCl2) were being transported to these sites. His methods of measuring the various forms of mercury, were at the time extremely innovative, but required at least 24 hour sampling and subsequent complex laboratory analysis. Brosset recognized at that time a need to speiciate the forms of mercury being emitted from power plants and incinerators and the importance of developing near real time atmospheric mercury measurements.

It was not until the late 1990's that reliable techniques for speciation of mercury emissions and ambient air became available. Subsequent field studies confirmed Brosset's earlier work that, indeed, fossil fueled combustion sources emit both elemental and divalent forms of mercury, referred to as reactive gaseous mercury (RGM). RGM in stack emissions is most likely in the form of mercuric chloride (HgCl2). Atmospheric mercury studies in the Florida Everglades and Great Lakes during the 1990's demonstrated the relative importance of RGM dry deposition as a significant contributor of total mercury loading to these aquatic ecosystems. More recent studies including aircraft measurements off the coast of Florida (60-3500 m), at the Mauna Loa high altitude research station (3500 m), and in the Polar regions have shown elemental mercury is oxidized into RGM and particulate phase mercury via halide/photochemical reactions.

Since a significant portion of the atmospheric chemistry of mercury is poorly understood, contemporary atmospheric mercury models do not adequately simulate halide oxidation mechanisms observed in during polar mercury depletion events or in the marine free troposphere. This reality coupled to a lack of a comprehensive global emissions inventory that includes speciated anthropogenic and natural mercury sources limit the present reliability of deterministic models in predicting atmospheric behavior and deposition of mercury over short temporal and large spatial scales. To investigate the transport and deposition of atmospheric mercury and to elucidate the local, regional and global impact of industrial emissions, appropriate source and receptor site chemical monitoring and characterization is required.

The purpose of this paper is to provide information on contemporary mercury speciation and associated air quality monitoring methodologies required to generate the data necessary to conduct a robust source apportionment/receptor modeling study.

Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.
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Citation:Landis, M. S., and R. K. Stevens. The Monitoring and Modeling of Mercury Species in Support of Local, Regional, and Global Modeling. Presented at Harmonization of Mercury Measurement Methods and Models, Maratea, Italy, May 23-26, 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: 05/24/2004
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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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Bullet Item Assessing the Condition of Freshwater Ecosystems: the Great Lakes and Great Rivers
spacer Relationship Reason:   A Project of the Product
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Last Updated on Monday, October 22, 2007
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