Brine

Brine is a high-concentration saltwater solution. The term most often refers to sodium chloride dissolved in water, but brines can also contain other dissolved salts. Brine occurs naturally in salt lakes, saline springs, and underground aquifers, and it is produced commercially by evaporating seawater or by dissolving mined halite.

Common uses include food processing and preservation: brining meats and vegetables, pickling, and flavoring through osmosis. Industrially, brines serve as a de-icer on roads, a heat-transfer fluid in cooling systems, and a medium in chemical production. In the energy sector, lithium and other mineral brines are pumped from underground reservoirs to extract metals.

Concentrations are typically expressed as a percent by weight of salt in the solution. Seawater is about 3.5% NaCl, whereas brines used for preservation or industrial purposes may be 5% to 20% or more. Brines can be highly corrosive to metals and require appropriate materials and handling practices, as well as careful waste management.

Ecologically, natural brine environments such as salt flats and brine pools harbor specialized organisms, including halophiles and certain crustaceans like brine shrimp. Brine discharges can impact aquatic ecosystems if not managed properly, and disposal practices are regulated in many regions.