Weathering implications of water chemistry in an arctic–alpine environment, northern Sweden

This paper reports on some of the chemical characteristics of late melt-season water from Kärkevagge (“valley of the boulders”) above the Arctic Circle in northern Sweden. Included in the analyses were temperature, electrical conductivity, pH, SO4, NO3, K, SiO2, Mg, Mn, Na, Fe, and Al. These were measured in rain, late-lying snow, and water from the major stream and lake, as well as from pond, tributary, and seep sources in the valley. A total of 71 samples was collected at 57 sites between August 6 and August 23, 1996 for the purpose of characterizing the present weathering regime within this classic U-shaped glacial valley. Evidence of chemical weathering included increases in solute concentrations over precipitation inputs and a source-related, wide variation in water chemistry. The dominant anion measured in surface water was SO4. That, along with the presence of CaSO4 coatings on streambeds, indicates that pyrite oxidation may contribute to the weathering regime. High SO4 concentrations were associated with gypsum-coated streambeds and seeps that emerge from the bedrock. Low SO4 concentrations were associated with tributaries flowing primarily on fresh rock and originating from melting snow. Estimated chemical denudation rate for the valley, corrected for atmospheric inputs, was 19.2 tons/km2/yr. Although this is lower than previously reported, our research supports earlier work indicating that chemical weathering is a major component of mass wasting in this arctic–alpine environment.