Concentration and flux of solutes from snow and forest floor during snowmelt in the West-Central Adirondack region of New York

Decreases in pH and increases in the concentration of Al and NO₃^- have been observed in surface waters draining acid-sensitive regions in the northeastern U.S. during spring snowmelt. To assess the source of this acidity, we evaluated solute concentrations in snowpack, and in meltwater collected from snow and forest floor lysimeters in the west-central Adirondack Mountains of New York during the spring snowmelt period, 29 March through 15 April 1984. During the initial phase of snowmelt, ions were preferentially leached from the snowpack resulting in elevated concentrations in snowmelt water (e.g. H⁺ = 140 μeq.l^-1; NO₄^2- = 123 μeq.l^-1; SO₃^- = 160 μeq.l^-1). Solute concentrations decreased dramatically within a few days of the initial melt (< 50 μeq.l^-1). The concentrations of SO₄^2- and NO₃^- in snowpack and snowmelt water were similar, whereas NO^-₃ in the forest floor leachate was at least two times the concentration of SO₄^2-. Study results suggest that the forest floor was a sink for snowmelt inputs of alkalinity, and a net source of H⁺, NO₃^-, dissolved organic carbon, K⁺ and Al inputs to the mineral soil. The forest floor was relatively conservative with respect to snowmelt inputs of Ca²⁺, SO₄^2- and Cl^-. These results indicate that mineralization of N, followed by nitrification in the forest floor may be an important process contributing to elevated concentrations of H⁺ and NO₃^- in streams during the snowmelt period.