Selenium in Lake Sediments: A Measure of the Extent of Sea-Ice Cover

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Abstract ATM-9634345 Norton, Stephen A. Jacobson, George L. University of Maine Title: Selenium in Lake Sediments: A Measure of the Extent of Sea- Ice Cover Several lines of paleolimnological and lake water chemistry research suggest that (1) selenium (Se) in lake sediments is linearly related to the percentage of organic matter for individual lakes and (2) normalized to organic matter concentration for lake districts, Se concentration is related to distance from the open ocean. The linkage is through the delivery of Se in marine aerosols from the open ocean to lake basin catchments and the subsequent incorporation of Se (a chemical analog for S) into organic matter. Marine aerosols are the only significant sources of Se to most aquatic ecosystems. This SGER award supports the investigation of stratigraphic variations in Se concentration in coastal lakes as a record of changing distance to open ocean and as a proxy for sea-ice cover. Methods will involve chemical palynological, and radiometric analyses (the later to establish absolute age) of existing cores spanning the Holocene and core spanning the Little Age to the present. This will enable calibration of the method against known climate variation and historically-documented variation in sea-ice cover.