The Roles of Snow, Lake Ice and Lake Water in the Distribution of Major Ions in the Ice Cover of a Lake

Abstract

The stratigraphic variability of ion concentration in lake ice was examined and related to the processes of lake-ice formation. Ice blocks obtained from Elizabeth Lake, Labrador and Knob Lake, Quebec showed marked vertical variation in the concentration of major ions, with peaks in conductivity occurring in the white ice and an overall increase in conductivity upwards from the black-ice/white-ice interface to the top of the block. Exsolution of ions from the black ice into the water body appears to be very efficient, producing low concentrations of ions in the black ice and high concentrations in the immediate sub-ice layer of water. This sub-ice concentration of ions appears to influence the entire water column, possibly via density-induced movements. Changes in snow depth, white- and black-ice growth, and the vertical distribution of conductivity in the water column were found to be related to slushing events. A controlled slushing experiment suggested that a marked concentration of ions does occur during white-ice formation.