HR: 1330h
AN: C42A-1006    [PDF]
TI: Flowpath Transformations of Precipitation Chemistry in an Arctic Tundra Catchment
AU: * Quinton, W L
EM: bquinton@sfu.ca
AF: Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6 Canada
AU: Pomeroy, J W
EM: pomeroy@usask.ca
AF: University of Saskatchewan, 9 Campus Drive, Saskatoon, SK S7N 5A5 Canada
AB: This paper traces the drainage pathways followed by rainfall and snowmelt in an actic tundra basin. The major hydrological processes operating within each flowpath segment from the surface of melting snow to the basin outlet are related to changes in the ion chemistry of the water flowing from each segment. In so doing, this paper offers physically-based explanations for the transformation of major ion concentrations and loads of snowmelt water as it travels to the stream outlet in this environment. Despite representing only five percent of the basin water equivalent, snow drifts were found to control the ion chemistry of the water in hillslope flowpaths and in the stream channel. As the initial pulse of ion-rich meltwater was conveyed through hillslope flowpaths, the concentrations of most ions increased, and the duration of peak ionic pulse lengthened. The hillslope runoff process also replaced Na+ and Cl-, the major ions in the percolate with Ca2+ and Mg2+. Over the first three metres of surface flow, concentrations of most ions increased by one to two orders of magnitude, which was roughly equivalent to the concentration increase that resulted from percolation of relatively dilute water through 0.25 m of unsaturated soil. On slopes below a large melting snowdrift, ion concentrations of meltwater flowing in the saturated layer of the soil were very similar to the relatively dilute concentrations found in surface runoff. However, once the snowdrift ablated, sub-surface flow ion concentrations rose steadily above parent meltwater concentrations. Water chemistry in the stream channel strongly resembled that of drainage from adjacent hillslopes. In-channel geochemical processes increased the concentration of most ions with flow distance in the major channel.
DE: 1851 Plant ecology
DE: 1860 Runoff and streamflow
DE: 1863 Snow and ice (1827)
SC: Cryosphere [C]
MN: 2003 Fall Meeting