Salinization of Permafrost Terrain Due to Natural Geomorphic Disturbance, Fosheim Peninsula, Ellesmere Island

Аннотация

Efflorescences (surface salt accumulations) are common on the Fosheim Peninsula and elsewhere in the Canadian Arctic Archipelago, especially at elevations below the Holocene marine limit, and cover up to 9% of the terrain in the vicinity of lower Hot Weather Creek. They are most extensive on naturally disturbed slopes and in floodplain locations. More than 75% of efflorescences are related to geomorphic disturbances (active-layer detachment sliding, retrogressive thaw slumping, and gullying), which initiate the causal chain of (1) surface erosion; (2) local degradation of permafrost; (3) contact between supra-permafrost groundwater and soluble ions previously held within frozen sediments; (4) increase in total dissolved-solids concentrations in slope surface runoff; and (5) depending on the degree of channelization of drainage and the slope profile, transport of dissolved solids directly to the stream system or their redistribution and accumulation downslope. Concentrations of Na+ in surface runoff reached almost 5 g/l during summer 1996 at a recent (1988) detachment slide scar in marine sediments. These concentrations are sufficiently high to negatively affect most terrestrial arctic plant species. Soluble Na+ levels within the active layer suggest that concentrations in slope runoff will remain elevated for several decades. Climatic warming, if it causes an increase in annual thaw depths or in the frequency and extent of geomorphic disturbances, could also result in active layer salinization within areas of salt-rich permafrost, such as in marine surficial deposits.