HIGH-SEDIMENTATION EVENTS AND ANNUAL SEDIMENT FLUX IN A SEDIMENT TRAP RECORD FROM LINNÉVATNET, SVALBARD

Linnévatnet is a proglacial lake in the high Arctic, on the western coast of Spitsbergen, Svalbard, Norway. The annually laminated sedimentary record in the lake has yielded high-resolution climate records extending back at least 1,000 years. Climate records such as these are valuable tools for understanding changing climate systems in the Arctic and globally, particularly as the warming trend of the 20^th and 21^st centuries has affected the Arctic climate disproportionately. Analysis of sedimentary records from Linnévatnet is an important component of understanding late-Holocene changes to the high Arctic climate of Svalbard.

Sediment traps and other environmental monitoring equipment have been deployed in and around Linnévatnet since 2003. Sediment traps are placed at varying depths throughout the water column on six moorings around the lake, in water depths from 5 to 35 m. Studies of modern sedimentation patterns in the lake allow for better understanding and interpretation of sedimentary records of past climate.

This study examines the summer 2015-’16 sedimentation year in detail, with magnetic susceptibility, grain size, and XRF analyses performed at 0.5 cm or smaller intervals downcore on the year’s sediment trap cores. Data from these analyses is used in conjunction with weather data, time-lapse photography, other environmental data from Linnévatnet and the surrounding area, and an intervalometer, which records the timing of sedimentation in the lake with 30-minute resolution. Of particular interest in preliminary results is the sedimentation from the period of September 11-12, 2015. Roughly 70% of the annual sedimentation at the intervalometer was recorded during an intense rainstorm over these two days. This heavy influence from a late-season storm event stands in contrast with the classic model of annually varved lake sediments, in which a nival pulse of spring snowmelt is responsible for the greatest portion of sedimentation. The warming Arctic climate may be driving an increasing prevalence of sediment related to late-season storm events in lake sediment climate records.