Effects of Ice and Snow Cover on the Chemistry of Nearshore Lake Water During Spring Melt

Open Access
Publisher Website
Google Scholar
Abstract
Snow and ice played important roles in determining the occurrence and timing of pH depressions in the shallow (∼1 m) nearshore waters of a small lake of the Canadian Shield. The influences of the terrestrial snowpack and lake-surface snow on the chemical composition of under-ice water were distinctly different. On land, acidic meltwater from snow was enriched with lithological elements in the soil/litter layer during lateral movement to the lake shoreline. The resulting run-off water was of relatively high ionic strength (X conductivity 55 μS cm−1), low pH (X 4.1) and contained high concentrations of Al (X 1786 μg 1−1), an element potentially toxic to aquatic biota. Snow cover on the ice surface controlled thermal conditions in the underlying water, dictating the depth to which run-off water penetrated. Uniformly cold conditions (<2°C) allowed penetration of run-off water to the substrate while under-ice warming to 4°C resulted in surface layering of less dense run-off water. flooding of the ice with lake water and melting of the ice and snow-surface cover served to counteract the effects of the run-off water through dilution.