Salt evaporation pond

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Salt evaporation pond in Ile de Ré, France

Salt evaporation ponds are shallow man-made ponds designed to produce salts from sea water or other brines. The seawater or brine is fed into large ponds and water is drawn out through natural evaporation which allows the salt to be subsequently harvested. The ponds also provide a productive resting and feeding ground for many species of waterbirds, including several endangered species. The ponds are commonly separated by levees.

Due to variable algal concentrations, vivid colors, from pale green to bright red, are created in the evaporation ponds. The color indicates the salinity of the ponds. Micro-organisms change their hues as the salinity of the pond increases. In low to mid-salinity ponds, green algae are predominant. In middle to high salinity ponds, an algae called Dunaliella salina shifts the color to red. Millions of tiny brine shrimp create an orange cast in mid-salinity ponds. Other bacteria such as Stichococcus also contribute tints.

Notable salt ponds include:

• the San Francisco Bay salt ponds in the United States, operated by Cargill;
• the Dead Sea salt ponds in Israel and Jordan;
• the Useless Loop and Onslow salt ponds in Western Australia.

Salt pans are shallow open pans used to evaporate brine for the production of salts. The pans are usually found close to the source of the salt. For example pans used in the solar evaporation of salt from sea water are usually found on the coast, while those used to extract salt from solution mined brine will be found near to the brine shaft. In this case extra heat is often provided by lighting fires underneath.

San Francisco Bay salt ponds.

Salt evaporation ponds at a Lithium mine in Argentina. The brine in this salar is rich in lithium, and the mine concentrates the brine in the ponds.

Contemporary solar evaporation salt pans on the island of Lanzarote.

Solar Evaporation Ponds in the Atacama Desert.

See also

• Concentrating solar power
• Evaporite
• Open pan salt making
• Saltern

External links

Wikimedia Commons has media related to: Salt evaporation pond

• NASA page on salt ponds
• Information on the San Francisco Bay salt ponds
• Interactive satellite view