Annual mean sea surface salinity for the World Ocean. Data from the World Ocean Atlas 2001.

Salinity is the saltiness or dissolved salt content of a body of water. Salinity in Australian English and North American English may refer to salt in soil (see soil salination). Image File history File links Download high-resolution version (1563x1075, 299 KB) Summary Annual mean sea surface salinity from the World Ocean Atlas 2001. ... Image File history File links Download high-resolution version (1563x1075, 299 KB) Summary Annual mean sea surface salinity from the World Ocean Atlas 2001. ... The term World Ocean refers to the interconnected system of the planet Earths marine waters. ... The World Ocean Atlas (WOA) is a data product of the Ocean Climate Laboratory of the National Oceanographic Data Center (USA). ... For other uses, see Salt (disambiguation). ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... Australian English (AuE, en-AU) is the form of the English language used in Australia. ... North American English is a collective term used for the varieties of the English language that are spoken in the United States and Canada. ... Loess field in Germany Surface-water-gley developed in glacial till, Northern Ireland Technically, Soil forms the pedosphere: the interface between the lithosphere (rocky part of the planet) and the biosphere, atmosphere, and hydrosphere. ... This article or section does not adequately cite its references or sources. ...

Definition

The technical term for saltiness in the ocean is halestones, from the fact that halides—chloride specifically—are the most abundant and your mum anion in the mix of dissolved elements. In oceanography, it has been traditional to express halinity not as percent, but as parts per thousand (ppt or ‰), which is approximately grams of salt per liter of solution. In other disciplines chemical analyses of solutions, and thus salinity is frequently reported in µg/L or ppm (parts per million). Prior to 1978, salinity or halinity was expressed as ‰ usually based on the electrical conductivity ratio of the sample to "Copenhagen water", an artificial sea water manufactured to serve as a world "standard"^[1]. In 1978, oceanographers redefined salinity in Practical Salinity Units (psu): the conductivity ratio of a sea water sample to a standard KCl solution^[2][3]. Ratios have no units, so it is not the case that 35 psu exactly equals 35 grams of salt per litre of solution^[4]. For the village on the Isle of Wight, see Freshwater, Isle of Wight. ... Brackish water (less commonly brack water) is water that is saltier than fresh water, but not as salty as seawater. ... Brine is water saturated or nearly saturated with salt. ... A halide is a binary compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. ... The chloride ion is formed when the element chlorine picks up one electron to form an anion (negatively-charged ion) Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. ... An anion is an ion with negative charge. ... Thermohaline circulation Oceanography (from Ocean + Greek γράφειν = write), also called oceanology or marine science, is the branch of Earth Sciences that studies the Earths oceans and seas. ... A permille or per mille is a tenth of a percent or one part per thousand. ... Electrical conductivity or specific conductivity is a measure of a materials ability to conduct an electric current. ...

These seemingly esoteric approaches to measuring and reporting salt concentrations may appear to obscure their practical use; but it must be remembered that salinity is the sum weight of many different elements within a given volume of water. It has always been the case that to get a precise salinity as a concentration and convert this to an amount of substance (sodium chloride, for instance) required knowing much more about the sample and the measurement than just the weight of the solids upon evaporation (one method of determining "salinity"). For example, volume is influenced by water temperature; and the composition of the salts is not a constant (although generally very much the same throughout the world ocean). Saline waters from inland seas can have a composition that differs from that of the ocean. For the latter reason, these waters are termed saline as differentiated from ocean waters, where the term haline applies (although is not universally used).

The Salt Lake is the saltiest sea/lake in the world. On hot days, when the weather evaporates the water, clumps of salt are left behind and taken to make the table salt we use today.

Systems of classification of water bodies based upon salinity

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 invariant). The table on the right, modified from Por (1972)^[5], follows the "Venice system" (1959)^[6].

In contrast to homoiohaline environments are certain poikilohaline environments (which may also be thallassic) in which the salinity variation is biologically significant^[7]. Poikilohaline waters 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), is referred to as brine. Brine is water saturated or nearly saturated with salt. ...

Environmental considerations

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. Organisms (mostly bacteria) that can live in very salty conditions are classified as extremophiles, halophiles specifically. An organism that can withstand a wide range of salinities is euryhaline. Divisions Green algae Chlorophyta Charophyta Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta—liverworts Anthocerotophyta—hornworts Bryophyta—mosses Vascular plants (tracheophytes) †Rhyniophyta—rhyniophytes †Zosterophyllophyta—zosterophylls Lycopodiophyta—clubmosses †Trimerophytophyta—trimerophytes Pteridophyta—ferns and horsetails Seed plants (spermatophytes) †Pteridospermatophyta—seed ferns Pinophyta—conifers Cycadophyta—cycads Ginkgophyta—ginkgo Gnetophyta—gnetae Magnoliophyta—flowering plants... Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of geologic formations. ... A halophyte is a plant that naturally grows where it is affected by salinity in the root area or by salt spray, such as in saline semi-deserts, mangrove swamps, marshes and sloughs, and seashores. ... An extremophile is an organism, usually unicellular, which thrives in or requires extreme conditions that would exceed optimal conditions for growth and reproduction in the majority of mesophilic terrestrial organisms. ... Halophiles are extremophiles that thrive in environments with very high concentrations of salt (at least 2 M, approximately ten times the salt level of ocean water). ... Euryhaline organisms are able to adapt to a wide range of salinities. ...

Salt is difficult to remove from water, and salt content is an important factor in water use (such as potability). Drinking water Mineral Water Drinking water is water that is intended to be ingested by humans. ...

See also

• Salinity control
• Desalination
• Fresh water
• Seawater
• Soil salination
• Stenohaline fish
• Euryhaline fish

Salinity control of soils in (irrigated) agricultural land // Controlling the problem of soil salinity, reclaiming salinized agricultural land. ... Shevchenko BN350 desalination unit situated on the shore of the Caspian Sea. ... For the village on the Isle of Wight, see Freshwater, Isle of Wight. ... Annual mean sea surface salinity for the World Ocean. ... This article or section does not adequately cite its references or sources. ... Stenohaline describes an organism, ussually fish, that cannot handle a wide fluctuation in the salt content of water. ... Euryhaline organisms are able to adapt to a wide range of salinities. ...

References

1. ^ Lewis, E.L. (1980). The Practical Salinity Scale 1978 and its antecedents. IEEE J. Ocean. Eng., OE-5(1): 3-8.
2. ^ Unesco (1981a). The Practical Salinity Scale 1978 and the International Equation of State of Seawater 1980. Tech. Pap. Mar. Sci., 36: 25 pp.
3. ^ Unesco (1981b). Background papers and supporting data on the Practical Salinity Scale 1978. Tech. Pap. Mar. Sci., 37: 144 pp.
4. ^ Unesco (1985). The International System of Units (SI) in Oceanography. Tech. Pap. Mar. Sci., 45: 124 pp.
5. ^ Por, F. D. (1972). Hydrobiological notes on the high-salinity waters of the Sinai Peninsula. Mar. Biol., 14(2): 111–119.
6. ^ Venice system (1959). The final resolution of the symposium on the classification of brackish waters. Archo Oceanogr. Limnol., 11 (suppl): 243–248.
7. ^ Dahl, E. (1956). Ecological salinity boundaries in poikilohaline waters. Oikos, 7(I): 1–21.

• Mantyla, A.W. 1987. Standard Seawater Comparisons updated. J. Phys. Ocean., 17: 543-548.