Salt lakes - Caspian Sea
The
salt lake called
Caspian Sea is the largest enclosed body of water on Earth by area, variously classed as the world's largest lake or a full-fledged sea. It has a surface area of 371,000 square kilometers (143,244 sq mi) and a volume of 78,200 cubic kilometers (18,761 cu mi). It is an endorheic body of water and lies between the southern areas of the Russian Federation and northern Iran. It has a maximum depth of about 1025 meters (3,363 ft). It is called a sea because when the Romans first arrived there, they tasted the water and found it to be salty. It has a salinity of approximately 1.2%, about a third the salinity of most seawater.
It is named after the ancient Caspians.
Geography
The Caspian Sea is bordered by five countries:
* Kazakhstan, to the North & North East.
* Turkmenistan on the Southern half of the Eastern shore
* Iran has the southern shore with (Gilan, Mazandaran and Golestan provinces)
* Azerbaijan on the Southern part of the Western shore including its capital Baku.
* Russian Federation to the North West with (Dagestan, Kalmykia, Astrakhan Oblast),
Major natural features around the Caspian sea include:
* The Caspian Depression is north of the Caspian sea
* The central Asian steppes to the north east.
* The Caucasus mountains on the border between Russia and Azerbaijan.
* The Garabogazköl on the eastern shore.
The sea is connected to the Sea of Azov by the Manych Canal and the Volga-Don Canal.
Salinity
Depending on the inflow of fresh water from its effluents, the Caspian Sea is a fresh-water lake in its northern portions. It is more saline on the Iranian shore. The largely dried-up Garabogazköl embayment routinely exceeds oceanic salinity.
Fauna
An aerial view of the southern Caspian coast as viewed from atop the Alborz mountains in Mazandaran, Iran
An aerial view of the southern Caspian coast as viewed from atop the Alborz mountains in Mazandaran, Iran.
The Caspian Sea holds great numbers of sturgeon, which yield eggs that are processed into caviar. In recent years overfishing has threatened the sturgeon population to the point that environmentalists advocate banning sturgeon fishing completely until the population recovers. However, prices for sturgeon caviar are so high that fisherman can afford to pay similarly high bribes to authorities to look the other way, making regulations in many locations ineffective. Caviar harvesting further endangers the fish stocks, since it targets reproductive females.
The Caspian Seal (Phoca caspica, Pusa caspica in some sources) is endemic to the Caspian Sea, one of very few seal species living in inland waters (see also Baikal Seal).
The area has given its name to several species of birds, including the Caspian Gull and the Caspian Tern.
There are several species of fish endemic to the Caspian sea, including Kutum (also known as Caspian White Fish), Caspian Roach, Bream, and a species of salmon. Caspian Salmon is critically endangered.
Oil
The area is rich in energy wealth. As well as recently discovered oil fields, large natural gas supplies are also in evidence, though further exploration is needed to define their full potential. Geopolitical jockeying is taking place amongst Caspian-bordering countries, especially in the light of Middle East instability and the subsequent recasting of many Western countries' energy policies. Another factor influencing this is the new US military deployment to the Central Asian region.
A key problem is the status of the Caspian Sea and the establishment of the water boundaries among the five countries bordering the Caspian. Russia, Azerbaijan and Kazakhstan signed an agreement in 2003 to divide the northern 64% of the sea among themselves, although the other two bordering countries, Iran and Turkmenistan, did not agree to this. This is likely to result in the three agreeing nations proceeding with oil development regardless; Iranian and Turkmen development is likely to stall.
At present, Azerbaijan and Kazakhstan have seen the biggest increase in oil production, an increase of 70% since 1992. Despite this, the region is still achieving less than potential output, with total regional production 1.6 million barrels (250,000 mł) per day, roughly equal to Brazil's production. This is expected to triple by 2010.
The oil in the Caspian basin is estimated to be worth over USD $12 trillion dollars.
Characteristics and ecology
The Caspian has characteristics common to both seas and lakes. It is often listed as the world's largest lake, though it is not a freshwater lake.
The Volga River (about 80% of the inflow) and the Ural River discharge into the Caspian Sea, but it is endorheic, i.e. there is no natural outflow (other than by evaporation). Thus the Caspian ecosystem is a closed basin, with its own sea level history that is independent of the eustatic level of the world's oceans. The Caspian became landlocked about 5.5 million years ago. The level of the Caspian has fallen and risen, often rapidly, many times over the centuries. Some Russian historians claim that a medieval rising of the Caspian caused the coastal towns of Khazaria, such as Atil, to flood. In 2004, the water level was -28 metres, or 28 metres (92 feet) below sea level.
Over the centuries, Caspian Sea levels have changed in synchronicity with the estimated discharge of the Volga, which in turn depends on rainfall levels in its vast catchment basin. Precipitation is related to variations in the amount of North Atlantic depressions that reach the interior, and they in turn are affected by cycles of the North Atlantic Oscillation. Thus levels in the Caspian sea relate to atmospheric conditions in the North Atlantic thousands of miles to the north and west. These factors make the Caspian Sea a valuable place to study the causes and effects of global climate change.
The last short-term sea-level cycle started with a sea-level fall of 3 m from 1929 to 1977, followed by a rise of 3 m from 1977 until 1995. Since then smaller oscillations have taken place. These changes have caused major environmental problems.
Source:
http://en.wikipedia.org23.08.2007. 07:40