ABSTRACT

Experiments were performed to evaluate the effects of advancing freeze fronts on movements of fine-grained sediment particles in seawater- and freshwater-slush ice slurries. In the freshwater experiment, the horizontal migrations of clay-sized particles in response to a laterally advancing freeze front were documented photographically. Differential migration of particles as a function of their size was also noted. In the seawater-slush ice experiment involving downward movement of a freeze front through a sediment-laden slush ice layer, time-series measurements were taken for 1) accumulations of sediment released from the ice into the underlying water column, 2) decreases in temperature in the ice matrix, and 3) increases in salinity in the water beneath the ice. Results of the latter experiment support the contention that a downward congealing slush ice matrix can purge itself of at least a portion of an entrained sediment load during an evolving freezing process. However, most of the sediment load initially carried by the slush ice remained at the conclusion of the experiment. This observation has implications for the importance of spatial transport and deposition of ice-rafted sediments to overall sediment budgets in regions affected by sea ice. In summary, migration of sediment particles in congealing slush ice matrices due to freeze front advances can be important to geological, physical and biological processes as well as commercial activities in arctic marine and nearshore regions.