The impact of heterogeneous flow paths on snowmelt runoff chemistry

The role of heterogeneous flow paths in determining the chemical composition of meltwater was examined in a field experiment north of Inuvik, NWT. The concentration of major anions were determined for the pre-melt snowcover and for daily flow in 16 separate compartments within a 0.25 m² lysimeter. Daily melt water samples were retained for chemical analysis from four compartments representative of the total range of flows. Early in the melt period the daily flow volume varied from 0.2 to 2.5 times the daily mean flow for the entire lysimeter, while the solute concentrations were typically 2 to 5 times higher in the compartments with low flow than in those with the highest flows. The concentration factors (CF) [ratio of the solute concentration in the flow to initial snowpack solute concentration] early in the melt varied from 1.5 to 10, and then decreased to between 0.1 and 0.5 and after 50% of the melt there was no relationship between flow and concentration.