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ENVIRONMENTAL CHAMBER STUDIES OF MERCURY REACTIONS IN THE ATMOSPHERE
Citation:
Sumner, A. L., C. W. Spicer, J. Satola, R. Mangaraj, M S. Landis, R. K. STEVENS, AND T. D. Atkeson. ENVIRONMENTAL CHAMBER STUDIES OF MERCURY REACTIONS IN THE ATMOSPHERE. Presented at American Geophysical Union's Fall Meeting, San Francisco, CA, December 13-17, 2004.
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:
Mercury is released into the environment through both natural and anthropogenic pathways. The cycling and fate of mercury in atmospheric, soil, and water ecosystems is impacted by various factors, including chemical transformation and transport. An understanding of these processes is critical for predicting the impact of mercury emission controls and future mercury concentrations. The chemical transformations of elemental mercury in the atmosphere were studied to determine the role of atmospheric chemistry in the mercury cycle. The rates of the gas phase reactions of elemental mercury with molecular bromine, chlorine, and fluorine, the atomic halogens, BrO, ClO, ozone, and the nitrate radical were studied at room temperature in a 17.3 m3 environmental chamber. The fate of elemental mercury resulting from these chemical reactions was addressed by measurement of reactive gaseous mercury, article-phase mercury, and reactive mercury lost to the chamber surfaces during the experiments. The implications of these chemical reactions and others studied in environmental chambers for the cycling of elemental atmospheric mercury will be discussed.
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.