Salinity ( / s ə ˈ l ɪ n ɪ t i / ) is the saltiness or amount of salt dissolved in a body of water , called saline water (see also soil salinity ). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal to ‰).
80-554: Caspian can refer to: The Caspian Sea The Caspian Depression , surrounding the northern part of the Caspian Sea The Caspians , the ancient people living near the Caspian Sea The Caspian languages spoken in northern Iran and southeastern Azerbaijan The Northeast Caucasian languages , also referred to as 'Caspian languages,' spoken in
160-704: A cave in Georgia. Discoveries in the Hotu cave and the adjacent Kamarband cave , near the town of Behshahr , Mazandaran south of the Caspian in Iran, suggest human habitation of the area as early as 11,000 years ago. Ancient Greeks focused on the civilization on the south shore – they call it the (H)yr(c/k)anian Sea ( Ancient Greek : Υρκανία θάλαττα , with sources noting the latter word was evolving then to today's Thelessa : late Ancient Greek : θάλασσα ). Hafiz-i Abru ,
240-588: A complex mixture of many different elements from different sources (not all from dissolved salts) in different molecular forms. The chemical properties of some of these forms depend on temperature and pressure. Many of these forms are difficult to measure with high accuracy, and in any case complete chemical analysis is not practical when analyzing multiple samples. Different practical definitions of salinity result from different attempts to account for these problems, to different levels of precision, while still remaining reasonably easy to use. For practical reasons salinity
320-498: A factor of 10. The Caspian Sea is the largest inland body of water in the world by area and accounts for 40–44% of the total lake waters of the world, and covers an area larger than Germany . The coastlines of the Caspian are shared by Azerbaijan , Iran , Kazakhstan , Russia , and Turkmenistan . The Caspian is divided into three distinct physical regions: the Northern, Middle, and Southern Caspian. The Northern–Middle boundary
400-490: A few percent (%). Physical oceanographers working in the abyssal ocean , however, are often concerned with precision and intercomparability of measurements by different researchers, at different times, to almost five significant digits . A bottled seawater product known as IAPSO Standard Seawater is used by oceanographers to standardize their measurements with enough precision to meet this requirement. Measurement and definition difficulties arise because natural waters contain
480-683: A fourteenth century Timurid Empire geographer, recorded that the destruction of the Oxus river dam and irrigation works diverted the river flow towards the Caspian Sea, which caused the Aral sea to nearly disappear. Later, in the Tang dynasty (618–907), the sea was the western limit of the Chinese Empire. The area is rich in fossil fuels . Oil wells were being dug in the region as early as
560-456: A measured density. Marine waters are those of the ocean, another term for which is euhaline seas . The salinity of euhaline seas is 30 to 35 ‰. Brackish seas or waters have salinity in the range of 0.5 to 29 ‰ and metahaline seas from 36 to 40 ‰. These waters are all regarded as thalassic because their salinity is derived from the ocean and defined as homoiohaline if salinity does not vary much over time (essentially constant). The table on
640-488: A result of the petrochemical industry; this has significantly decreased the number of species of marine birds in the area. Existing and planned oil and gas pipelines under the sea further increase the potential threat to the environment. The high concentration of mud volcanoes under the Caspian Sea were thought to be the cause of a fire that broke out 75 kilometers from Baku on July 5, 2021. The State oil company of Azerbaijan SOCAR said preliminary information indicated it
720-432: A third of the salinity of average seawater . It is bounded by Kazakhstan to the northeast, Russia to the northwest, Azerbaijan to the southwest, Iran to the south, and Turkmenistan to the southeast. The name of the Caspian sea is derived from the ancient Iranic Caspi people. The sea stretches 1,200 km (750 mi) from north to south, with an average width of 320 km (200 mi). Its gross coverage
800-573: A tug that never actually served in the United States Navy Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title Caspian . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Caspian&oldid=1186878213 " Category : Disambiguation pages Hidden categories: Short description
880-464: A wide range of salinities is euryhaline . Salts are expensive to remove from water, and salt content is an important factor in water use, factoring into potability and suitability for irrigation . Increases in salinity have been observed in lakes and rivers in the United States, due to common road salt and other salt de-icers in runoff. The degree of salinity in oceans is a driver of
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#1732758191952960-478: Is 386,400 km (149,200 sq mi) and the surface is about 27 m (89 ft) below sea level . Its main freshwater inflow , Europe's longest river, the Volga , enters at the shallow north end. Two deep basins form its central and southern zones. These lead to horizontal differences in temperature, salinity, and ecology. The seabed in the south reaches 1,023 m (3,356 ft) below sea level, which
1040-484: Is a wholly freshwater species. The zebra mussel is native to the Caspian and Black Sea basins, but has become an invasive species elsewhere, when introduced. The area has given its name to several species, including the Caspian gull and the Caspian tern . The Caspian seal ( Pusa caspica ) is the only aquatic mammal endemic to the Caspian Sea, being one of very few seal species that live in inland waters, but it
1120-405: Is different from those inhabiting freshwaters due to the hydrological environment of the sea. A century ago the Caspian was home to more than one million seals . Today, fewer than 10% remain. Archeological studies of Gobustan Rock Art have identified what may be oceanic species including cetaceans from baleen whales to dolphins , and auks most likely Brunnich's Guillemot , although
1200-472: Is different from Wikidata All article disambiguation pages All disambiguation pages Caspian Sea The Caspian Sea is the world's largest inland body of water , described as the world's largest lake and usually referred to as a full-fledged sea . An endorheic basin , it lies between Europe and Asia : east of the Caucasus , west of the broad steppe of Central Asia , south of
1280-414: Is home to a wide range of species and is famous for its caviar and oil industries. Pollution from the oil industry and dams on rivers that drain into it have harmed its ecology. It is predicted that during the 21st century, the depth of the sea will decrease by 9–18 m (30–60 ft) due to global warming and the process of desertification , leading to an ecocide . The sea's name stems from Caspi ,
1360-520: Is pulled in to replace the sinking water, which in turn eventually becomes cold and salty enough to sink. Salinity distribution contributes to shape the oceanic circulation. Limnologists and chemists often define salinity in terms of mass of salt per unit volume, expressed in units of mg/L or g/L. It is implied, although often not stated, that this value applies accurately only at some reference temperature because solution volume varies with temperature. Values presented in this way are typically accurate to
1440-651: Is referred to as brine . Salinity is an ecological factor of considerable importance, influencing the types of organisms that live in a body of water. As well, salinity influences the kinds of plants that will grow either in a water body, or on land fed by a water (or by a groundwater ). A plant adapted to saline conditions is called a halophyte . A halophyte which is tolerant to residual sodium carbonate salinity are called glasswort or saltwort or barilla plants. Organisms (mostly bacteria) that can live in very salty conditions are classified as extremophiles , or halophiles specifically. An organism that can withstand
1520-466: Is sometimes referred to as chlorinity. Operationally, dissolved matter is defined as that which can pass through a very fine filter (historically a filter with a pore size of 0.45 μm, but later usually 0.2 μm). Salinity can be expressed in the form of a mass fraction , i.e. the mass of the dissolved material in a unit mass of solution. Seawater typically has a mass salinity of around 35 g/kg, although lower values are typical near coasts where rivers enter
1600-623: Is the Mangyshlak Threshold, which runs through Chechen Island and Cape Tiub-Karagan. The Middle–Southern boundary is the Apsheron Threshold , a sill of tectonic origin between the Eurasian continent and an oceanic remnant, that runs through Zhiloi Island and Cape Kuuli. The Garabogazköl Bay is the saline eastern inlet of the Caspian, which is part of Turkmenistan and at times has been a lake in its own right due to
1680-481: Is the deepest, with oceanic depths of over 1,000 m (3,300 ft), greatly exceeding the depth of other regional seas, such as the Persian Gulf . The Middle and Southern Caspian account for 33% and 66% of the total water volume, respectively. The northern portion of the Caspian Sea typically freezes in the winter, and in the coldest winters ice forms in the south as well. Over 130 rivers provide inflow to
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#17327581919521760-459: Is the third-lowest natural non-oceanic depression on Earth after Baikal and Tanganyika lakes. Written accounts from the ancient inhabitants of its coast perceived the Caspian Sea as an ocean, probably because of its salinity and large size. With a surface area of 371,000 square kilometres (143,000 sq mi), the Caspian Sea is nearly five times as big as Lake Superior (82,000 square kilometres (32,000 sq mi)). The Caspian Sea
1840-470: Is usually related to the sum of masses of a subset of these dissolved chemical constituents (so-called solution salinity ), rather than to the unknown mass of salts that gave rise to this composition (an exception is when artificial seawater is created). For many purposes this sum can be limited to a set of eight major ions in natural waters, although for seawater at highest precision an additional seven minor ions are also included. The major ions dominate
1920-683: The Azerbaijan Academy of Sciences estimated that the level of the sea was dropping by more than six centimetres per year due to increased evaporation due to rising temperatures caused by climate change . The Volga River , the longest river in Europe, drains 20% of the European land area and is the source of 80% of the Caspian's inflow. Heavy development in its lower reaches has caused numerous unregulated releases of chemical and biological pollutants. The UN Environment Programme warns that
2000-629: The Black Sea , a remnant of the ancient Paratethys Sea . Its seafloor is, therefore, a standard oceanic basalt and not a continental granite body. It is estimated to be about 30 million years old, and became landlocked in the Late Miocene , about 5.5 million years ago, due to tectonic uplift and a fall in sea level . The Caspian Sea was a comparatively small endorheic lake during the Pliocene , but its surface area increased fivefold around
2080-655: The Black Sea . In the late Pontian stage , a mountain arch rose across the south basin and divided it into the Khachmaz and Lankaran Lakes (or early Balaxani ). The period of restriction to the south basin was reversed during the Akchagylian – the lake became more than three times its size today and took again the first of a series of contacts with the Black Sea and Aral Sea . A recession of Lake Akchagyl completed stage one. The earliest hominid remains found around
2160-613: The Reaper (DC Comics) Other uses [ edit ] Caspian horse , a small horse breed native to Northern Iran Caspian tiger , a Panthera tigris population native Northern Iran and Caucasus Caspian Airlines , an airline based in Tehran, Iran Caspian (band) , an instrumental post-rock band Caspian, Michigan , a small city in the United States USS Caspian (ID-1380) , proposed designation for
2240-471: The Ural River discharge into the Caspian Sea, but it has 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 sea level of the Caspian has fallen and risen, often rapidly, many times over the centuries. Some Russian historians, such as Lev Gumilev , claim that
2320-653: The ancient people who lived to the southwest of the sea in Transcaucasia . Strabo (died circa AD 24) wrote that "to the country of the Albanians ( Caucasian Albania , not to be confused with the country of Albania ) belongs also the territory called Caspiane, which was named after the Caspian tribe, as was also the sea; but the tribe has now disappeared". Moreover, the Caspian Gates , part of Iran 's Tehran province , may evince such people migrated to
2400-529: The density and heat capacity of the water. A contour line of constant salinity is called an isohaline , or sometimes isohale . Salinity in rivers, lakes, and the ocean is conceptually simple, but technically challenging to define and measure precisely. Conceptually the salinity is the quantity of dissolved salt content of the water. Salts are compounds like sodium chloride , magnesium sulfate , potassium nitrate , and sodium bicarbonate which dissolve into ions. The concentration of dissolved chloride ions
2480-564: The hydrography is such that a possible cause of reduced circulation is the production of stratified oceans. In such cases, it is more difficult to subduct water through the thermohaline circulation. Not only is salinity a driver of ocean circulation, but changes in ocean circulation also affect salinity, particularly in the subpolar North Atlantic where from 1990 to 2010 increased contributions of Greenland meltwater were counteracted by increased northward transport of salty Atlantic waters. However, North Atlantic waters have become fresher since
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2560-553: The tidal areas of the Volga delta and riparian forests of the Samur River delta. The shoreline is also a unique refuge for plants adapted to the loose sands of the Central Asian Deserts . The principal limiting factors to successful establishment of plant species are hydrological imbalances within the surrounding deltas, water pollution , and various land reclamation activities. The water level change within
2640-401: The twelfth largest by nominal GDP and sixth largest by purchasing power parity in 2015. Russia's extensive mineral and energy resources are the largest such reserves in the world, making it the second leading producer of oil and natural gas globally. Caspian littoral states join efforts to develop infrastructure, tourism and trade in the region. The first Caspian Economic Forum
2720-413: The world's ocean circulation , where density changes due to both salinity changes and temperature changes at the surface of the ocean produce changes in buoyancy, which cause the sinking and rising of water masses. Changes in the salinity of the oceans are thought to contribute to global changes in carbon dioxide as more saline waters are less soluble to carbon dioxide. In addition, during glacial periods,
2800-411: The 10th century to reach oil "for use in everyday life, both for medicinal purposes and for heating and lighting in homes". By the 16th century, Europeans were aware of the rich oil and gas deposits locally. English traders Thomas Bannister and Jeffrey Duckett described the area around Baku as "a strange thing to behold, for there issueth out of the ground a marvelous quantity of oil, which serveth all
2880-408: The 1980s. Titration with silver nitrate could be used to determine the concentration of halide ions (mainly chlorine and bromine ) to give a chlorinity . The chlorinity was then multiplied by a factor to account for all other constituents. The resulting 'Knudsen salinities' are expressed in units of parts per thousand (ppt or ‰ ). The use of electrical conductivity measurements to estimate
2960-433: The Black Sea basin or widespread Palearctic species such as crucian carp , Prussian carp , common carp , common bream , common bleak , asp , white bream , sunbleak , common dace , common roach , common rudd , European chub , sichel , tench , European weatherfish , wels catfish , northern pike , burbot , European perch and zander . Almost 30 non-indigenous, introduced fish species have been reported from
3040-573: The Caspi(an) descriptor; in Kazakh it is called Каспий теңізі , Kaspiy teñizi , Kyrgyz : Каспий деңизи , romanized : Kaspiy deñizi , Uzbek : Kaspiy dengizi . Others refer to it as the Khazar sea : Turkmen : Hazar deňzi ; Azerbaijani : Xəzər dənizi , Turkish : Hazar Denizi . In all these the first word refers to the historical Khazar Khaganate , a large empire based to
3120-515: The Caspian "suffers from an enormous burden of pollution from oil extraction and refining, offshore oil fields, radioactive wastes from nuclear power plants and huge volumes of untreated sewage and industrial waste introduced mainly by the Volga River". The magnitude of fossil fuel extraction and transport activity in the Caspian also poses a risk to the environment. The island of Vulf off Baku , for example, has suffered ecological damage as
3200-546: The Caspian Sea are from Dmanisi dating back to around 1.8 Ma and yielded a number of skeletal remains of Homo erectus or Homo ergaster . More later evidence for human occupation of the region came from a number of caves in Georgia and Azerbaijan such as Kudaro and Azykh Caves . There is evidence for Lower Palaeolithic human occupation south of the Caspian from western Alburz. These are Ganj Par and Darband Cave sites. Neanderthal remains also have been discovered at
3280-725: The Caspian Sea is an indirect reason for which plants may not get established. These affect aquatic plants of the Volga Delta, such as Aldrovanda vesiculosa and the native Nelumbo caspica . About 11 plant species are found in the Samur River delta, including the unique liana forests that date back to the Tertiary period . Since 2019 UNESCO has admitted the lush Hyrcanian forests of Mazandaran , Iran as World Heritage Site under category (ix). The Caspian turtle ( Mauremys caspica ), although found in neighboring areas,
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3360-488: The Caspian Sea, but only a few have become established. Six sturgeon species, the Russian , bastard , Persian , sterlet , starry and beluga , are native to the Caspian Sea. The last of these is arguably the largest freshwater fish in the world . The sturgeon yield roe (eggs) that are processed into caviar . Overfishing has depleted a number of the historic fisheries. In recent years, overfishing has threatened
3440-431: The Caspian region economies are highly dependent on this type of mineral wealth. The world energy markets were influenced by Azerbaijan and Kazakhstan, as they became strategically crucial in this sphere, thus attracting the largest share of foreign direct investment (FDI). All of the countries are rich in solar energy and harnessing potential, with the highest rainfall much less than the mountains of central Europe in
3520-704: The Caspian, the Volga River being the largest. A second affluent, the Ural River , flows in from the north, and the Kura River from the west. In the past, the Amu Darya (Oxus) of Central Asia in the east often changed course to empty into the Caspian through a now-desiccated riverbed called the Uzboy River , as did the Syr Darya farther north. The Caspian has several small islands, primarily located in
3600-645: The North Caspian, the majority of the islands are small and uninhabited, like the Tyuleniy Archipelago , an Important Bird Area (IBA). The climate of the Caspian Sea is variable, with the cold desert climate (BWk), cold semi-arid climate (BSk), and humid continental climate (Dsa, Dfa) being present in the northern portions of the Caspian Sea, while the Mediterranean climate (Csa) and humid subtropical climate (Cfa) are present in
3680-529: The Protection of the Caspian Sea against Pollution from Land-based Sources in order to ensure better protection for the biodiversity of the Caspian Sea. The rising level of the Caspian Sea between 1995 and 1996 reduced the number of habitats for rare species of aquatic vegetation. This has been attributed to a general lack of seeding material in newly formed coastal lagoons and water bodies. Many rare and endemic plant species of Russia are associated with
3760-657: The Russian Caucasus and northern Azerbaijan In fiction [ edit ] Prince Caspian , a book in the Chronicles of Narnia series by C. S. Lewis Caspian X , "Prince Caspian", a prince of the Telmarines The Chronicles of Narnia: Prince Caspian , a film based on the novel by C. S. Lewis Caspian (Highlander) , a fictional character on Highlander: The Series Judson Caspian, alter-ego of one of three characters named
3840-641: 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 kilometres to the northwest. The last short-term sea-level cycle started with a sea-level fall of 3 m (10 ft) from 1929 to 1977, followed by a rise of 3 m (10 ft) from 1977 until 1995. Since then smaller oscillations have taken place. A study by
3920-457: The climate to the southwest and south are generally warm with uneven elevation due to a mix of highlands and mountain ranges ; the drastic changes in climate alongside the Caspian have led to a great deal of biodiversity in the region. The Caspian Sea has numerous islands near the coasts, but none in the deeper parts of the sea. Ogurja Ada is the largest island. The island is 37 km (23 mi) long, with gazelles roaming freely on it. In
4000-417: The composition of seawater. They can also be determined by making direct density measurements. A sample of seawater from most locations with a chlorinity of 19.37 ppt will have a Knudsen salinity of 35.00 ppt, a PSS-78 practical salinity of about 35.0, and a TEOS-10 absolute salinity of about 35.2 g/kg. The electrical conductivity of this water at a temperature of 15 °C is 42.9 mS/cm. On
4080-475: The country to burn in their houses. This oil is black and is called nefte . There is also by the town of Baku, another kind of oil which is white and very precious [i.e., petroleum ]." Today, oil and gas platforms abound along the edges of the sea. During the rule of Peter I the Great , Fedor I. Soimonov was a pioneering explorer of the sea. He was a hydrographer who charted and greatly expanded knowledge of
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#17327581919524160-486: The current Caspian Sea and either the Arctic Ocean or North Sea , or the Black Sea . This is supported by the existences of current endemic, oceanic species such as lagoon cockles which was genetically identified to originate in the Caspian and Black Seas regions. The sea's basin (including associated waters such as rivers) has 160 native species and subspecies of fish in more than 60 genera . About 62% of
4240-476: The fertile plains of Southern Russia in Eastern Europe , and north of the mountainous Iranian Plateau . It covers a surface area of 371,000 km (143,000 sq mi) (excluding the highly saline lagoon of Garabogazköl to its east), an area approximately equal to that of Japan , with a volume of 78,200 km (19,000 cu mi). It has a salinity of approximately 1.2% (12 g/L), about
4320-586: The fish stocks, since it targets reproductive females. Reptiles native to the region include the spur-thighed tortoise ( Testudo graeca buxtoni ) and Horsfield's tortoise . The main geologic history locally had two stages. The first is the Miocene , determined by tectonic events that correlate with the closing of the Tethys Sea . The second is the Pleistocene noted for its glaciation cycles and
4400-491: The form of silicic acid , which usually appears as a neutral molecule in the pH range of most natural waters, may also be included for some purposes (e.g., when salinity/density relationships are being investigated). The term 'salinity' is, for oceanographers, usually associated with one of a set of specific measurement techniques. As the dominant techniques evolve, so do different descriptions of salinity. Salinities were largely measured using titration -based techniques before
4480-656: The full run of the present Volga. During the first stage, the Tethys Sea had evolved into the Sarmatian Lake, that was created from the modern Black Sea and south Caspian, when the collision of the Arabian peninsula with West Asia pushed up the Kopet Dag and Caucasus Mountains , lasting south and west limits to the basin. This orogenic movement was continuous, while the Caspian was regularly disconnected from
4560-411: The global scale, it is extremely likely that human-caused climate change has contributed to observed surface and subsurface salinity changes since the 1950s, and projections of surface salinity changes throughout the 21st century indicate that fresh ocean regions will continue to get fresher and salty regions will continue to get saltier. Salinity is serving as a tracer of different masses. Surface water
4640-421: The inorganic composition of most (but by no means all) natural waters. Exceptions include some pit lakes and waters from some hydrothermal springs . The concentrations of dissolved gases like oxygen and nitrogen are not usually included in descriptions of salinity. However, carbon dioxide gas, which when dissolved is partially converted into carbonates and bicarbonates , is often included. Silicon in
4720-412: The ionic content of seawater led to the development of the scale called the practical salinity scale 1978 (PSS-78). Salinities measured using PSS-78 do not have units. The suffix psu or PSU (denoting practical salinity unit ) is sometimes added to PSS-78 measurement values. The addition of PSU as a unit after the value is "formally incorrect and strongly discouraged". In 2010 a new standard for
4800-485: The isthmus that cuts it off from the Caspian. Differences between the three regions are dramatic. The Northern Caspian only includes the Caspian shelf, and is very shallow; it accounts for less than 1% of the total water volume with an average depth of only 5–6 m (16–20 ft). The sea noticeably drops off towards the Middle Caspian, where the average depth is 190 m (620 ft). The Southern Caspian
4880-409: The measured conductivity at 5 °C might only be in the range of 50–80 μS/cm. Direct density measurements are also used to estimate salinities, particularly in highly saline lakes . Sometimes density at a specific temperature is used as a proxy for salinity. At other times an empirical salinity/density relationship developed for a particular body of water is used to estimate the salinity of samples from
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#17327581919524960-453: The mountains of the west, which are also rich in hydroelectricity sources. Iran has high fossil fuel energy potential. It has reserves of 137.5 billion barrels of crude oil , the fourth largest in the world, producing around four million barrels a day. Iran has an estimated 988.4 trillion cubic feet of natural gas , around 16 percent of world reserves, thus key to current paradigms in global energy security. Russia's economy ranks as
5040-527: The north of the Caspian Sea between the 7th and 10th centuries. In Iran, the lake is referred to as the Mazandaran Sea ( Persian : دریای مازندران ), after the historic Mazandaran Province at its southern shores. Old Russian sources use the Khvalyn or Khvalis Sea ( Хвалынское море / Хвалисское море ) after the name of Khwarezmia . Among Greeks and Persians in classical antiquity it
5120-494: The north with a collective land area of roughly 2,000 km (770 sq mi). Adjacent to the North Caspian is the Caspian Depression , a low-lying region 27 m (89 ft) below sea level . The Central Asian steppes stretch across the northeast coast, while the Caucasus mountains hug the western shore. The biomes to both the north and east are characterized by cold, continental deserts. Conversely,
5200-530: The north, the Caspian Sea water is almost fresh in its northern portions, getting more brackish toward the south. It is most saline on the Iranian shore, where the catchment basin contributes little flow. Currently, the mean salinity of the Caspian is one third that of Earth's oceans. The Garabogazköl lagoon , which dried up when water flow from the main body of the Caspian was blocked in the 1980s but has since been restored, routinely exceeds oceanic salinity by
5280-422: The ocean. Rivers and lakes can have a wide range of salinities, from less than 0.01 g/kg to a few g/kg, although there are many places where higher salinities are found. The Dead Sea has a salinity of more than 200 g/kg. Precipitation typically has a TDS of 20 mg/kg or less. Whatever pore size is used in the definition, the resulting salinity value of a given sample of natural water will not vary by more than
5360-491: The order of 1%. Limnologists also use electrical conductivity , or "reference conductivity", as a proxy for salinity. This measurement may be corrected for temperature effects, and is usually expressed in units of μS/cm . A river or lake water with a salinity of around 70 mg/L will typically have a specific conductivity at 25 °C of between 80 and 130 μS/cm. The actual ratio depends on the ions present. The actual conductivity usually changes by about 2% per degree Celsius, so
5440-598: The properties of seawater called the thermodynamic equation of seawater 2010 ( TEOS-10 ) was introduced, advocating absolute salinity as a replacement for practical salinity, and conservative temperature as a replacement for potential temperature . This standard includes a new scale called the reference composition salinity scale . Absolute salinities on this scale are expressed as a mass fraction, in grams per kilogram of solution. Salinities on this scale are determined by combining electrical conductivity measurements with other information that can account for regional changes in
5520-650: The right, modified from Por (1972), follows the "Venice system" (1959). In contrast to homoiohaline environments are certain poikilohaline environments (which may also be thalassic ) in which the salinity variation is biologically significant. Poikilohaline water salinities may range anywhere from 0.5 to greater than 300 ‰. The important characteristic is that these waters tend to vary in salinity over some biologically meaningful range seasonally or on some other roughly comparable time scale. Put simply, these are bodies of water with quite variable salinity. Highly saline water, from which salts crystallize (or are about to),
5600-518: The rising of the Caspian in the 10th century caused the coastal towns of Khazaria to flood, resulting in the Khazars losing approximately two-thirds of their territory due to flooding. Over the centuries, Caspian Sea levels have changed in synchrony 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
5680-470: The rock art on Kichikdash Mountain which is assumed to depict either a beaked whale or a dolphin , it may represent the famous beluga sturgeon instead due to its size (430 cm in length). These petroglyphs may suggest potential presences of oceanic faunas in the Caspian Sea presumably until the Quaternary or even the last glacial period or antiquity due to historic marine inflow between
5760-496: The sea. He drew a set of four maps and wrote Pilot of the Caspian Sea , the first lengthy report and modern maps. These were published in 1720 by the Russian Academy of Sciences . Countries in the Caspian region, particularly Azerbaijan , Kazakhstan and Turkmenistan , have high-value natural-resource-based economies, where the oil and gas compose more than 10 percent of their GDP and 40 percent of their exports. All
5840-580: The south. The Iranian city of Qazvin shares the root of its name with this common name for the sea. The traditional and medieval Arabic name for the sea was Baḥr ('sea') Khazar , but in recent centuries the common and standard name in Arabic language has become بحر قزوين Baḥr Qazvin , the Arabized form of Caspian. In modern Russian language, it is known as Russian : Каспи́йское мо́ре , Kaspiyskoye more . Some Turkic ethnic groups refer to it with
5920-405: The southern portions of the Caspian Sea. The Caspian has characteristics common to both seas and lakes. It is often listed as the world's largest lake, although it is not freshwater : the 1.2% salinity classes it with brackish water bodies. It contains about 3.5 times as much water, by volume, as all five of North America's Great Lakes combined. The Volga River (about 80% of the inflow) and
6000-905: The species and subspecies are endemic , as are 4–6 genera (depending on taxonomic treatment). The lake proper has 115 natives, including 73 endemics (63.5%). Among the more than 50 genera in the lake proper, 3–4 are endemic: Anatirostrum , Caspiomyzon , Chasar (often included in Ponticola ) and Hyrcanogobius . By far the most numerous families in the lake proper are gobies (35 species and subspecies), cyprinids (32) and clupeids (22). Two particularly rich genera are Alosa with 18 endemic species/subspecies and Benthophilus with 16 endemic species. Other examples of endemics are four species of Clupeonella , Gobio volgensis , two Rutilus , three Sabanejewia , Stenodus leucichthys , two Salmo , two Mesogobius and three Neogobius . Most non-endemic natives are either shared with
6080-421: The sturgeon population to the point that environmentalists advocate banning sturgeon fishing completely until the population recovers. The high price of sturgeon caviar – more than 1,500 Azerbaijani manats (US$ 880 as of April 2019 ) per kilo – allows fishermen to afford bribes to ensure the authorities look the other way, making regulations in many locations ineffective. Caviar harvesting further endangers
6160-475: The time of the Pliocene-Pleistocene transition. During warm and dry climatic periods, the landlocked sea almost dried up, depositing evaporitic sediments like halite that were covered by wind-blown deposits and were sealed off as an evaporite sink when cool, wet climates refilled the basin. (Comparable evaporite beds underlie the Mediterranean .) Due to the current inflow of fresh water in
6240-458: Was a mud volcano which spewed both mud and flammable gas. It is calculated that during the 21st century, the water level of the Caspian Sea will decrease by 9–18 m (30–60 ft) due to the acceleration of evaporation due to global warming and the process of desertification , causing an ecocide . On October 23, 2021, Kazakhstan President Kassym-Jomart Tokayev signed the Protocol for
6320-558: Was convened on August 12, 2019, in Turkmenistan and brought together representatives of Kazakhstan, Russia, Azerbaijan, Iran and that state. It hosted several meetings of their ministers of economy and transport. Salinity Salinity is an important factor in determining many aspects of the chemistry of natural waters and of biological processes within it, and is a thermodynamic state variable that, along with temperature and pressure , governs physical characteristics like
6400-686: Was the Hyrcanian ocean. Renaissance European maps labelled it as the Abbacuch Sea (Oronce Fine's 1531 world map), Mar de Bachu (Ortellius' 1570 map), or Mar de Sala (the Mercator 1569 world map ). It was also sometimes called the Kumyk Sea and Tarki Sea (derived from the name of the Kumyks and their historical capital Tarki ). The Caspian Sea is at its South Caspian Basin , like
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