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PRELIMINARY RESULTS FROM THE US EPA MERCURY SPECIATION NETWORK AND AIRCRAFT MEASUREMENT CAMPAIGNS
Citation:
Landis, M S. AND R. K. STEVENS. PRELIMINARY RESULTS FROM THE US EPA MERCURY SPECIATION NETWORK AND AIRCRAFT MEASUREMENT CAMPAIGNS. Presented at 223rd American Chemical Society National Meeting, Orlando, FL, April 7-11, 2002.
Impact/Purpose:
The overall research objective of this task is to improve our understanding of the emission, transport, transformation, and deposition of atmospheric mercury. Information garnered from this research is used to improve and evaluate EPA deterministic models that are used to investigate the (i) relative impact to local, regional, and global sources to atmospheric mercury deposition, and (ii) benefits of various emission reduction scenarios.
Specifically, individual research project objectives are listed below:
(1) Evaluate the ability of speciated mercury (Hg0, Hg2+, HgP) measurements to aid source apportionment models in identifying anthropogenic source contributions to atmospheric mercury deposition
(2) Elucidate the contribution of coal combustion sources to observed mercury wet deposition in the Ohio River Valley
(3) Obtain atmospheric profiles (200 - 12,000 ft) of speciated ambient mercury off the south Florida Coast
- Evaluate the role of long range transport of RGM to Florida in the marine free troposphere.
- Identify any vertical mercury gradients that might indicate the presence of rapid mercury chemistry in air or in cloud water.
(4) Conduct research at Mauna Loa Observatory to elucidate elemental mercury oxidation in the remote marine free troposphere.
(5) Conduct laboratory kinetics experiments to determine the rate constants of elemental mercury oxidation to gaseous inorganic divalent mercury species from atmospheric halide species (e.g. BrO, ClO).
Description:
Since EPA measured high concentrations of reactive gaseous mercury (RGM) in emissions from municipal and hospital waste incinerators in 1995, we have been working to elucidate the role of RGM on atmospheric mercury deposition. EPA has recently established automated speciated mercury monitoring sites in Coral Springs, Florida; Cheeka Peak, Washington; Barrow, Alaska; and Mauna Loa, Hawaii. In addition, EPA has conducted over thirty mercury research aircraft sorties off Florida's Atlantic coast and in Barrow, Alaska. At each site or study, specific sets of measurements will contribute to our overall understanding of the mechanisms of transformation of Hg0 to RGM and to particulate phase mercury. We will present data from all our studies and discuss the results in terms of homogenous and heterogeneous atmospheric oxidation mechanisms, long-range transport, source receptor relationships and long-term global baseline measurements and modeling.
This work has been funded wholly or in part by the United States Environmental Protection Agency. It has been subjected to peer review and approved for publication.