CHARACTERIZING ICELAND LAKE SEDIMENTS: LAKE SYSTEM CHANGES FROM MARINE VS. FRESHWATER

Under ever-mounting concerns about the effects of climate change, geoscientists often turn to past climates and environments to better understand and predict future conditions. Lake sediments from sensitive environments, such as northern latitude Iceland lakes, provide a unique window into these paleoenvironments through the multiple proxy investigation of lacustrine sediments and watershed soils. The sediment record of Rekavíkurvatn, a back-barrier lake in northwest Iceland (66°24'50.40"N, 23° 1'47.06"W, 1m), is ideally situated for the investigation of regional climate and environmental sensitivity because of its close proximity to the North Atlantic and frequent marine incursions over the barrier beach.

Although currently a freshwater lake, in the past, Rekavíkurvatn has been fully marine, evidenced by marine bivalve shells at particular depths in the sediment core Rek 96-6. Alternating fresh and marine environments suggest that the lake and its sediments have undergone significant regime changes over time. Furthermore, compiled historical records also suggest major flood events and storm surges have impacted this area. Analyses of magnetic susceptibility, particle size distributions, geochemistry and geochronology in lake sediments and watershed soils, reveal further changes in sediment character linked to water regime. Dominantly marine vs. freshwater regimes of the lake are compared with storm events from the historical records and correlated with northern hemisphere climate patterns, such as the NAO, to further understanding of regional climates and impacts of climate change.