ANALYSIS OF SEDIMENT TRAPS IN LINNÉVATNET, SVALBARD FOR RECONSTRUCTION OF ANNUAL SEDIMENT FLUX AND LACUSTRINE PROCESSES

The warming trend of the 20^th century has caused significant environmental changes to the cryosphere in the arctic regions. Because the arctic plays an important role in the global climate system, it is necessary to understand how glaciers have responded to climate variation in the past in order to predict how they will react to warming in the future. Linnévatnet is a high arctic glacier-fed lake in Svalbard that serves as an excellent environmental observatory for glacial-fluvial and lacustrine processes. Recent research on annually laminated lake sediments in Linnévatnet has yielded high-resolution records of past climate that extends back at least 1,000 years. Analysis of sediment traps in the lake provides a calibration for interpreting these long-term sediment records by linking modern watershed and climatic processes to annual sediment yield.

Since 2003, arrays of sediment traps, temperature loggers, and other environmental instrumentation have been deployed in a network of six moorings in Linnévatnet at depths ranging from 15 to 35 meters. The moorings are recovered annually in late summer and receiving tubes on the traps are collected and instrumentation downloaded before redeployment. In the laboratory, the receiving tubes are split, and visual logs are recorded. Magnetic susceptibility was measured at 0.5 cm intervals in the split cores and the sediment is subsampled in continuous 0.25 cm slices for grain size analysis.

The annual sedimentation history in Linnévatnet and its controls will be reconstructed through detailed analysis of trap stratigraphy and environmental data from Linnédalen including weather data, time lapse photography, snow melt, and water column temperature profiles. Preliminary results from 2013-2014 sediment traps reveal two distinct coarser-grained events separated by the fine-grained “winter” layer. The first event is most likely associated with a significant late melt season rainfall in mid-August 2013. The later post-winter event is attributed to onset and peak nival melt in late spring to early summer 2014.