The migration of liquid inclusions in single ice crystals

Abstract

The migration of brine pockets of KCl and NaCl under the influence of a temperature gradient was investigated in single ice crystals. The observed migration velocities were compared with velocities calculated from a simple diffusion model using the data on electrolytic solutions available in the literature. Although the relative movements of the KCl and NaCl pockets were consistent with the diffusion theory, the observed velocities were always less than the calculated. Neither the direction of the gravitational field nor the crystallographic orientation of the host crystal significantly influenced the rate of migration. It was also shown that the migration of solid KCl particles occurs at temperatures below the eutectic point. Two mechanisms are proposed that would impede the mechanical differentiation of salts that crystallize at high temperatures relative to salts that remain in the brine of sea ice. These mechanisms explain recent observations that the SO4/Cl ratio of sea ice does not increase with the age of the ice.