Atmospheric Transport and Deposition of Chemical Constituents at Summit, Greenland: Interpretation of the GISP-2 Ice Core

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This project is the continuation of an investigation of the transport of chemical trace elements and species from source regions through the atmosphere to the Greenland ice sheet. Its goal is to provide information for the interpretation of the trace element distribution in the long ice core that has been obtained through the Greenland Ice Sheet Program (GISP- 2) drilling effort. The ice core will provide a detailed record spanning 200,000 years. The project has three specific objectives: (1) the identification of source regions and atmospheric pathways for the chemical constituents reaching the drill site, including the possible changes in air mass characteristics during transit, (2) the quantification of relationships between chemical species in the atmosphere and those in the ice sheet, and (3) the interpretation of the deep ice core data using this information. Prior field work has resulted in the collecting of samples of air, aerosol, precipitation, and deposited snow, which will be analyzed for various anions and cations, trace elements, carbon compounds, and trace gases. This project will emphasize the deposition mechanisms. The first objective will be achieved by measuring concentrations of chemical species in air and snow, and then combining this information with meteorological data of other investigators. Concentrations of major anions and cations will be determined by ion chromatography in our laboratories, while concentrations of trace elements and other species will be obtained by collaboration with other groups. The second objective involves measurement of wet, dry, and fog deposition, as well as changes that occur in the snow pack after deposition of chemical species. The third objective will be achieved by developing models to explain the processes influencing air and snow chemistry at the site in collaboration with GISP-2 researchers who are actively working with the core data. The results will be a better interpretation of the ice c ore data, and the reduction of uncertainties involved in using the core data to determine past atmospheric conditions. ***