Salt evaporation ponds, also called salterns or salt pans, are shallow artificial 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, which may include endangered species.[1] The ponds are commonly separated by levees.
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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 alga called Dunaliella salina shifts the color to red. Millions of tiny brine shrimp create an orange cast in mid-salinity ponds.[2] Other bacteria such as Stichococcus also contribute tints.
Notable salt ponds include:
Until World War II, salt was extracted from sea water in a unique way in Egypt near Alexandria.[7] Posts were set out on the salt pans and covered with about seven feet of sea water. In time the sea water evaporated, leaving the salt behind on the post, where it was easier to harvest.
Salt pans are shallow open, often metal, pans used to evaporate brine for the production of salts. They 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.
Salt Pans at Xwieni Bay in Gozo