Accumulation of Excess Ground Ice in an Age Sequence of Drained Thermokarst Lake Basins, Arctic Alaska
Article first published online: 2 AUG 2012
Copyright © 2012 John Wiley & Sons, Ltd.
Permafrost and Periglacial Processes
Volume 23, Issue 3, pages 231–236, July 2012
How to Cite
Bockheim, J. G. and Hinkel, K. M. (2012), Accumulation of Excess Ground Ice in an Age Sequence of Drained Thermokarst Lake Basins, Arctic Alaska. Permafrost Periglac. Process., 23: 231–236. doi: 10.1002/ppp.1745
- Issue published online: 5 SEP 2012
- Article first published online: 2 AUG 2012
- Manuscript Accepted: 7 JUL 2012
- Manuscript Received: 17 MAY 2012
- National Science Foundation (NSF). Grant Numbers: OPP-9912035 and OPP-0240338, OPP-9732051, OPP-0094769 and OPP-0713813
- ground ice;
- ice wedges;
- pore ice
The excess ice content of near-surface permafrost near Barrow, Alaska, was estimated using cores collected from 57 drained thermokarst-lake basins and additional cores from a nearby landform unaffected by thaw-lake processes. The excess ice content, estimated using soil cryostructures, increased with surface age: from 20 per cent in young basins < 50 years in age to 40 per cent in ancient basins that drained 2000–5500 years ago. The frequency of ice wedges encountered during coring increased from 0 per cent in young basins to 50 per cent in ancient basins. These results indicate that the volume of ground ice increases rapidly immediately following lake drainage, as permafrost aggrades into unfrozen basin sediments. Ice enrichment continues over time by incorporating meteoric water as ice veins and lenses, and expanding networks of ice wedges. To test the efficacy of visually estimating excess ice content, the ice content was measured on a subsample of cores; measured volumetric values were strongly correlated (r2 = 0.72; p < 0.001) to the estimated excess ice content. The results of this study have important implications for estimating soil organic carbon content of soils with abundant excess ice, and for evaluating the susceptibility of these soils to thermokarst. Copyright © 2012 John Wiley & Sons, Ltd.