HR: 0800h
AN: C21A-0066    [Abstracts]
TI: Compositional Change of Meltwater Infiltrating Frozen Ground
AU: * Lilbaek, G
EM: g.lilbaek@usask.ca
AF: Centre for Hydrology, University of Saskatchewan, 117 Science Place, Saskatoon, SK S7N 5C8, Canada
AU: Pomeroy, J W
EM: john.pomeroy@usask.ca
AF: Centre for Hydrology, University of Saskatchewan, 117 Science Place, Saskatoon, SK S7N 5C8, Canada
AB: Frozen ground underneath a melting snowpack may constrain infiltration and meltwater reaching the base of the snowpack will either infiltrate the underlying stratum, runoff, or refreeze, forming a basal ice layer. Compositional changes in chemistry will take place for each of these flow paths as a result of contact between meltwater and soil and mixing between meltwater and soil water. It is assumed that chemical alteration takes place soon after contact with a soil layer occurs. Three major flow paths were hypothesized distinguishable based on alterations in ion concentrations: overland flow, organic interflow, and mineral interflow. Laboratory experiments were carried out to identify compositional changes in meltwater, which had sustained contact with a basal ice layer, a forest organic layer, or a forest mineral soil layer. The experimental setup consisted of melting a snowpack in a large insulated box in a temperature-controlled environment. A cooling system at the chemically inert base ensured frozen substrate conditions during snowmelt. Throughout melt, samples of meltwater were collected from within the snowpack using an extraction tube; runoff or interflow samples were collected from the surface or soil along the base of the box. All samples were filtered and analyzed for major anions and cations. Runoff and interflow concentrations were normalized using meltwater concentrations. Results showed an overall enrichment in ion concentrations for overland flow that had sustained contact with a basal ice layer. Organic interflow showed significant increases in H+ and K+ and depletion in Mg2+. Mineral interflow showed an increase in Ca2+ and slight decrease in H+. Repeated flushes of meltwater through each interflow path caused a washout of ions. Similarly, ion concentrations were generally highest the first time meltwater was in contact with the soil. Generally, changes in ion concentrations were most significant for H+, K+, Mg2+, and Ca2+.
DE: 0700 CRYOSPHERE (4540)
DE: 0736 Snow (1827, 1863)
DE: 0740 Snowmelt
DE: 0742 Avalanches
DE: 0764 Energy balance
SC: Cryosphere [C]
MN: 2007 Fall Meeting