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摘要: Sedimentological studies of beach ridge sequences that are commonly present along the coastline of Lake Superior indicate large and relatively rapid lake-level fluctuations over the past 4,700 years, which resulted from the interplay of climate, differential isostatic rebound, and outlet dynamics. The presence of peat deposits in swales between the beach ridges offers an opportunity to assess the role of climate because the isotopic composition of cellulose extracted from peat can be used to assess changes in water balance, moisture sources, and/or local hydrological conditions. Despite its great potential as a paleoclimatic proxy, the factors that control the isotopic composition of cellulose in modern plants are still uncertain.Because the enrichment of oxygen-18 in moss cellulose may reflect site-specific conditions, we collected modern Sphagnum mosses in the Lake Superior area and samples of their potential water sources, namely rainwater, swale water, and groundwater. To assess the regional and temporal variability of isotope values, samples were collected in three locations along the shoreline of Lake Superior throughout two entire growing seasons.