Ion flux through a shallow snowpack: Effects of initial and melt conditions

Six intermediate-scale experiments were performed to determine the effects of melt rate, melt-freeze cycles, and initial chemical distribution on the timing and magnitude of the ionic pulse from a physically homogeneous snowpack. The greatest ionic concentration in the initial snowmelt resulted when long melt-freeze cycles were applied to a chemically homogeneous snowpack. Low melt rates resulted in faster initial ion removal than did high melt rates. Chemical species applied in a layer at mid pack were removed slower than species applied as a layer on the top. Sulfate and NO₃⁻ were consistently removed in preference to Cl⁻. Three ice-sphere experiments showed that the preferential release of SO₄⁻ and NO₃⁻ over Cl⁻ is influenced by microscale effects. In each case, SO₄⁻ and NO₃⁻ were rejected from the ice-crystal lattice to a greater extent than was Cl⁻, facilitating their early removal at the onset of melt