Salt evaporation pond
Encyclopedia
Salt evaporation ponds, also called salterns or salt pans, are shallow artificial pond
Pond
A pond is a body of standing water, either natural or man-made, that is usually smaller than a lake. A wide variety of man-made bodies of water are classified as ponds, including water gardens, water features and koi ponds; all designed for aesthetic ornamentation as landscape or architectural...
s designed to produce salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...
s from sea water or other brine
Brine
Brine is water, saturated or nearly saturated with salt .Brine is used to preserve vegetables, fruit, fish, and meat, in a process known as brining . Brine is also commonly used to age Halloumi and Feta cheeses, or for pickling foodstuffs, as a means of preserving them...
s. The seawater or brine is fed into large ponds and water is drawn out through natural evaporation
Evaporation
Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid....
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. The ponds are commonly separated by levee
Levee
A levee, levée, dike , embankment, floodbank or stopbank is an elongated naturally occurring ridge or artificially constructed fill or wall, which regulates water levels...
s.
Algae and colour of evaporation ponds
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 salinitySalinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
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
Dunaliella salina
Dunaliella salina is a type of halophile green micro-algae especially found in sea salt fields. Known for its anti-oxidant activity because of its ability to create large amount of carotenoids, it is used in cosmetics and dietary supplements. Few organisms can survive in such highly saline...
shifts the color to red. Millions of tiny brine shrimp
Brine shrimp
Artemia is a genus of aquatic crustaceans known as brine shrimp. Artemia, the only genus in the family Artemiidae, has changed little externally since the Triassic period...
create an orange cast in mid-salinity ponds. Other bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
such as Stichococcus
Stichococcus
In taxonomy, Stichococcus is a genus of algae, specifically of the Microthamniales.-Scientific databases:* * *...
also contribute tint
Tint
In color theory, a tint is the mixture of a color with white.Tint may also refer to:* Tint control, an adjustment to correct for phase error in the picture color on a NTSC television set* Tint , an album by Merzbow...
s.
Notable salt ponds
Notable salt ponds include:- the San Francisco BaySan Francisco BaySan Francisco Bay is a shallow, productive estuary through which water draining from approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean...
salt ponds in the United StatesUnited StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
, operated by CargillCargillCargill, Incorporated is a privately held, multinational corporation based in Minnetonka, Minnesota. Founded in 1865, it is now the largest privately held corporation in the United States in terms of revenue. If it were a public company, it would rank, as of 2011, number 13 on the Fortune 500,...
; - the Dead SeaDead SeaThe Dead Sea , also called the Salt Sea, is a salt lake bordering Jordan to the east and Israel and the West Bank to the west. Its surface and shores are below sea level, the lowest elevation on the Earth's surface. The Dead Sea is deep, the deepest hypersaline lake in the world...
salt ponds in IsraelIsraelThe State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...
and JordanJordanJordan , officially the Hashemite Kingdom of Jordan , Al-Mamlaka al-Urduniyya al-Hashemiyya) is a kingdom on the East Bank of the River Jordan. The country borders Saudi Arabia to the east and south-east, Iraq to the north-east, Syria to the north and the West Bank and Israel to the west, sharing...
; - the Useless LoopUseless Loop, Western AustraliaUseless Loop is located in the Southern Region of Shark Bay, Western Australia. Shark Bay is a UNESCO World Heritage Site which also home to the more famous Monkey Mia. Useless Loop is a closed company town, servicing the Solar Salt Operation Shark Bay Salt which has been in operation since 1968...
and OnslowOnslow, Western AustraliaOnslow is a coastal town in the Pilbara region of Western Australia, north of Perth. It currently has a population of around 573 people and is in the Shire of Ashburton Local Government Area....
salt ponds in Western AustraliaWestern AustraliaWestern Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
. - the salt works north of Pondicherry, IndiaIndiaIndia , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
.
Up until World War Two, salt was extracted from sea water in a unique way in Egypt near Alexandria
Alexandria
Alexandria is the second-largest city of Egypt, with a population of 4.1 million, extending about along the coast of the Mediterranean Sea in the north central part of the country; it is also the largest city lying directly on the Mediterranean coast. It is Egypt's largest seaport, serving...
. 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 stuck to the post where it was easier to harvest.
Salt pans
Salt pans are shallow open, often metal, pans used to evaporate brineBrine
Brine is water, saturated or nearly saturated with salt .Brine is used to preserve vegetables, fruit, fish, and meat, in a process known as brining . Brine is also commonly used to age Halloumi and Feta cheeses, or for pickling foodstuffs, as a means of preserving them...
for the production of salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...
s. 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.
http://www.flickr.com/photos/christophersammut/5831946988/in/photostream/Salt Pans at Xwieni Bay in Gozo
Gozo
Gozo is a small island of the Maltese archipelago in the Mediterranean Sea. The island is part of the Southern European country of Malta; after the island of Malta itself, it is the second-largest island in the archipelago...
]
See also
- Concentrating solar power
- Seawater GreenhouseSeawater GreenhouseThe Seawater Greenhouse is a technology that enables the growth of crops in arid regions, using a greenhouse structure, seawater and solar energy...
- EvaporiteEvaporiteEvaporite is a name for a water-soluble mineral sediment that result from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporate deposits, marine which can also be described as ocean deposits, and non-marine which are found in standing bodies of...
- Open pan salt makingOpen pan salt makingIn Europe virtually all domestic salt is obtained by solution mining of underground salt formations although some is still obtained by the solar evaporation of sea water. Salt is extracted from the Brine using vacuum pans, where brine is heated in a partial vacuum in order to lower the boiling...
- SalternSalternSaltern is a word with a number of differing meanings. In English archaeology, a saltern is an area used for salt making, especially in the East Anglian fenlands....