On average, the Atlantic is the saltiest major ocean ; surface water salinity in the open ocean ranges from 33 to 37 parts per thousand ( 3. 3 – 3. 7 %) by mass and varies with latitude and season.

Within the North Atlantic, ocean currents isolate the Sargasso Sea, a large elongated body of water, with above average salinity.

Alligators differ from crocodiles principally in having wider and shorter heads, with more obtuse snouts ; in having the fourth, enlarged tooth of the under jaw received, not into an external notch, but into a pit formed for it within the upper one ; in lacking a jagged fringe which appears on the hind legs and feet of the crocodile ; in having the toes of the hind feet webbed not more than half way to the tips ; and an intolerance to salinity, alligators strongly preferring fresh water, while crocodiles can tolerate salt water due to specialized glands for filtering out salt.

Due to the difference in salinity, a sub-surface layer of more saline water moving in the opposite direction brings in 475 km³ per year.

It mixes very slowly with the upper waters, resulting in a salinity gradient from top to bottom, with most of the salt water remaining below 40 to 70 m deep.

The Baltic Sea's salinity is much lower than that of ocean water ( which averages 35 ‰), as a result of abundant freshwater runoff from the surrounding land, combined with the shallowness of the sea itself ; indeed, runoff contributes roughly one-fortieth its total volume per year, as the volume of the basin is about 21, 000 km³ and yearly runoff is about 500 km³.

The flow of fresh water into the sea from approximately two-hundred rivers and the introduction of salt from the South builds up a gradient of salinity in the Baltic Sea.

Near the Danish straits the salinity is close to that of the Kattegat, but still not fully oceanic, because the saltiest water that passes the straits is still already mixed with considerable amounts of outflow water.

Another disadvantage of saline aquifers is that as the salinity of the water increases, less CO < sub > 2 </ sub > can be dissolved into aqueous solution.

With 33. 7 % salinity, it is also one of the world's saltiest bodies of water, though Lake Assal ( Djibouti ), Garabogazköl and some hypersaline lakes of the McMurdo Dry Valleys in Antarctica ( such as Don Juan Pond ) have reported higher salinities.

Until the winter of 1978-79, when a major mixing event took place, the Dead Sea was composed of two stratified layers of water that differed in temperature, density, age, and salinity.

The reduction in annual silt deposits has contributed to rising water tables and increasing soil salinity in the Delta, the erosion of the river's banks in Upper Egypt, and the erosion of the alluvial fan along the shore of the Mediterranean Sea.

Because of the large influx of fresh water from rivers, especially from the Neva River ( two thirds of the total runoff ), the gulf water has very low salinity – between 0. 2 and 5. 8 ‰ at the surface and 0. 3 – 8. 5 ‰ near the bottom.

For example, the Makgadikgadi Pans in Botswana is a vast seasonal high salinity water body that manifests halophilic species within the diatom genus Nitzschia in the family Bacillariaceae as well as species within the genus Lovenula in the family Diaptomidae.

Surface water salinity ranges from 32 to 37 parts per 1000, the highest occurring in the Arabian Sea and in a belt between southern Africa and south-western Australia.

Water pollution ; many people get their water directly from contaminated streams and wells ; as a result, water-borne diseases are prevalent ; increasing soil salinity from faulty irrigation practices.

When over deep the lake is no more salty than the sea, but salinity increases as the water evaporates, with saturation occurring at about a depth.

Evaporation is especially high in its eastern half, causing the water level to decrease and salinity to increase eastward.

The water of the Murray flows through several lakes that fluctuate in salinity ( and were often fresh until recent decades ) including Lake Alexandrina and The Coorong before emptying through the Murray Mouth into the southeastern portion of the Indian Ocean, often referenced on Australian maps as the Southern Ocean, near Goolwa.

These changes ensured the availability of water for irrigation and made the Murray Valley Australia's most productive agricultural region, but have seriously disrupted the life cycles of many ecosystems both inside and outside the river, and the irrigation has led to dryland salinity that now threatens the agricultural industries.

Salt water provides for greater organic activity than freshwater, and in particular, the shipworm, terredo navalis, lives only in salt water, so some of the best preservation in the absence of sediments has been found in the cold, dark waters of the Great Lakes in North America and in the ( low salinity ) Baltic Sea ( where the Vasa was preserved ).

At the semi-enclosed bays with major freshwater inflows, such as head of Finnish Gulf with Neva mouth and head of Bothnian gulf with close mouths of Lule, Tornio and Kemi, the salinity is considerably lower.

For example, the clearing of trees for agriculture is a major reason for dryland salinity in some areas, since deep rooting of trees has been replaced by shallow rooting of annual crops.

In the north irrigated fruit ( primarily oranges and grapes ) growing is a huge earner of money and supports Mildura and nearby towns ; however, salinity in the Murray River is a major threat to the long-term sustainability of these activities, as is competition from overseas citrus growers.

Investigation by the U. S. National Academy of Sciences found major errors in salinity and temperature controls that had caused serious variations in published values.

In spite of the high salinity, it is a major river in the region and serves as a primary source of irrigation. It is not saline up to balotara district but when it meets the saline land in this area it get also saline.

At the bottom of the sea, conditions are more stable and salinity is always oceanic (> 30 PSU ) below a certain depth that varies between 10 and 15 meters.

Here, current induced turbulence causes mixing of the whole water column such that salinity varies more longitudinally rather than vertically, leading to a moderately stratified condition.

The speed of sound in seawater is about 1, 500 metres / second, and varies with water temperature, salinity, and pressure.

The average salinity varies between 28 ‰ and 32 ‰ ( parts per thousand ) from south to north.

Water salinity increases toward the delta ; it normally varies between 50 and 400 mg / L and may reach 1000 mg / L in some areas.

Although salinity varies throughout the lake system, it approximates a one third fresh, two-thirds sea water mixture, and hence may be termed brackish water.

Typical characteristics for the EGC Polar water are a temperature between 0 ° C and – 1. 7 ° C ( e. g. freezing point of low-salinity sea water ), and the salinity varies greatly from 30 psu ( near the surface ) to 34 psu at a 150 meter depth.

The salinity varies with water volume.

Actual salinity varies among different marine ecosystems.

The sea is called " dead " because its high salinity prevents macroscopic aquatic organisms, such as fish and aquatic plants, from living in it, though minuscule quantities of bacteria and microbial fungi are present.

In general, the salinity of the soil increases from Baghdad south to the Persian Gulf and severely limits productivity in the region south of Al Amarah.

Increasing salinity and reduced habitat have killed the Aral Sea's fish, hence destroying its once-active fishing industry, and the receding shoreline has left the former port of Aral ' sk more than seventy kilometers from the water's edge.

The Kara receives a large amount of freshwater from the Ob, Yenisei, Pyasina, and Taimyra rivers, so its salinity is variable.

Over time the southernmost parts of Sumerian Mesopotamia suffered from increased salinity of the soils, leading to a slow urban decline and a centring of power in Akkad, further north.

Only salt-tolerant micro-algae survive in the high salinity ponds, and impart a deep red color to these ponds from the pigment within the algae protoplasm.

Water from the Susurluk, Biga ( Granicus ) and Gonen Rivers also reduces the salinity of the sea, though with less influence than on the Black Sea.

The Bitter Lakes, which were hypersaline natural lakes, blocked the migration of Red Sea species into the Mediterranean for many decades, but as the salinity of the lakes gradually equalised with that of the Red Sea, the barrier to migration was removed, and plants and animals from the Red Sea have begun to colonise the eastern Mediterranean.

Environment-current issues: inadequate sanitation facilities ; increasing levels of soil salinity ; industrial pollution ; excessive pesticides ; part of the basin of the shrinking Aral Sea suffers from severe overutilization of available water for irrigation and associated pollution

There are three main types of water masses in the Barents Sea: Warm, salty Atlantic water ( temperature > 3 ° C, salinity > 35 ) from the North Atlantic drift, cold Arctic water ( temperature < 0 ° C, salinity < 35 ) from the north, and warm, but not very salty coastal water ( temperature > 3 ° C, salinity < 34. 7 ).