GEOCHEMICAL EVIDENCE OF ANTHROPOGENIC IMPACTS ON SWIFTCURRENT LAKE, GLACIER NATIONAL PARK, MT

We analyzed lacustrine sediments from the northern basin of Swiftcurrent Lake in Glacier National Park, Montana. A 42 cm sediment core was extruded in 0.5 cm increments, which were analyzed for mineralogical and chemical composition. Elemental combustion analysis revealed that both percent carbon and percent nitrogen showed close covariation, and decreased with depth. Both elements show dramatic fluctuations throughout the top 10 cm of the profile, reaching minimum values at 9 cm. This sample corresponds to a notable peak in the C:N ratio, which increases steadily through 25 cm before decreasing through 42 cm. Percent sulfur shows a similar trend—increasing throughout the first 20 cm followed by a steady decrease—yet also displays much more variation in the stratigraphically lower samples. Preliminary XRD and smear slide analyses reveal little mineraological variation through the core samples, which were found to be clastic-rich, diatomaceous, and composed primarily of quartz and illite. Pb-210 dating and subsequent stable isotope analyses should provide insight into the sources of the physical and chemical fluctuations seen in the samples, and should help characterize the anthropogenic impact on Swiftcurrent Lake.