HR: 09:30h
AN: C31A-07    [Abstracts]
TI: An Increase in Rates of Retrogressive Thaw Slumping and Implications to Lake Water Quality, Western Arctic, Canada.
AU: * Kokelj, S V
EM: kokeljsv@inac.gc.ca
AF: Water Resources Division, Indian and Northern Affairs Canada, Bellanca Building, 2nd Floor P.O. Box 1500, 4914-50th Street, Yellowknife, NT X1A 2R3, Canada
AU: Lantz, T C
AF: Centre for Applied Conservation Research, University of British Columbia, 3041–2424 Main Mall, Vancouver, BC V6T 1Z4, Canada
AB: The growth rates of retrogressive thaw slumps in the Mackenzie Delta region Northwest Territories, Canada have increased significantly since 1973 in concert with accelerated climate warming. To evaluate change over time, we analyzed historical temperature records and mapped all slumps on 23, 49 km2 study plots using 1950, 1973 and 2004 aerial photographs. The aerial extent of slumping since 1950 had increased 15 percent by 1973 and 36 percent by 2004. The mean rate of slump expansion from 1973 to 2004 was about 1.5 times greater than that estimated from 1950 to 1973, whereas the mean maximum rates of headwall retreat from the lakeshore more than doubled. Degrading permafrost releases soluble materials, which are transported by surface runoff from ion-rich slump soils into adjacent aquatic systems, elevating ionic concentrations in the water of small tundra lakes. A positive association between lake water ionic concentrations and the proportion of catchment area influenced by thaw slumping suggests that degradation of ice-rich permafrost will be an important factor influencing chemistry of thousands of lakes in a warming western Arctic.
DE: 0702 Permafrost (0475)
DE: 0708 Thermokarst
DE: 0710 Periglacial processes
DE: 0746 Lakes (9345)
SC: Cryosphere [C]
MN: 2007 Fall Meeting