Brine rejection that drains from the newly formed ice is replaced by a weak flow of relatively fresh water, from the liquid region below it. The new water partially freezes within the pores of the ice, increasing the solidity of the ice. As sea ice ages and thickens, the initial salinity of the ice decreases due to the rejection of brine over time [Fig. 2]. While the sea ice ages, desalinization occurs to such a degree that some multiyear ice has a salinity of less than 1 PSU. This occurs in three different ways: Brine rejection occurs in the sea ice packs
Salt been laid down over the millennia from the evaporation of seas and lakes. These are either mined directly, producing rock salt, or are extracted in solution by pumping water into the deposit. In either case, the salt may be purified by mechanical evaporation of brine. Traditionally, this was done in shallow open pans which were heated to increase the rate of evaporation. More recently, the process is performed in pans under vacuum. The raw salt is refined to purify it and improve its storage and handling characteristics. This usually involves recrystallization during which a brine solution is treated with chemicals