C:N RATIO IN LAKE SEDIMENTS FROM BAFFIN ISLAND

The C:N ratio of lake core sediments can provide valuable information about the source of the sediment. Sediment rich in aquatic organic matter, such as plankton and aquatic plants, will have a higher percentage of nitrogen and therefore a lower C:N ratio. In lake systems where much of the sediment is derived from terrestrial inwash the C:N ratio is expected to be higher than for lake sediments that acquire most of their carbon from aquatic sources, reflecting the nitrogen poor condition of the terrestrial soils. During climate shifts, changes in aquatic productivity or changes in the stability of the surrounding landscape can alter the C:N ratio of accumulated lake sediment. The temporal evolution of C:N ratio archived in lake sediments provides a robust proxy for climate change. In this study, several lake sediment cores from Baffin Island along with terrestrial soil samples from each watershed are used to develop a binary mixing model for determining the percent aquatic and terrestrial inputs of sediment and to track the evolution of aquatic versus terrestrial carbon sources through the middle to late Holocene. Comparisons are drawn between Baffin Island coastal lakes (Qivitu Forelands of NE Cumberland Peninsula) and continental lakes from southern Baffin Island (Amadjuak Lake region). From the Amadjuak Lake region a comparison is also conducted between lakes developed on carbonate versus granitic bedrock at similar elevation and current climate conditions.