Annual mean sea surface salinity for the World Ocean. Data from the World Ocean Atlas 2005.^[1]

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. Salinity in Australian English and North American English may also refer to the salt content of soil (see soil salinity).

Definitions[link]

Salinity in the ocean refers to the water's "saltiness". In oceanography, it has been traditional to express salinity not as percent, but as permille (parts per thousand) (‰), which is approximately grams of salt per kilogram of solution. Other disciplines use chemical analyses of solutions, and thus salinity is frequently reported in mg/L or ppm (parts per million). Prior to 1978, salinity or halinity was expressed as Cl ‰, usually based on comparison with IAPSO Standard Seawater ("Copenhagen water"), a natural sea water distributed to serve as a world standard.^[2] In 1978, oceanographers redefined salinity in the Practical Salinity Scale (PSS) as the conductivity ratio of a sea water sample to a standard KCl solution.^[3][4] Although PSS is a dimensionless quantity, its "unit" is usually called PSU. It is not the case that a salinity of 35 exactly equals 35 grams of salt per liter of solution.^[5]

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 also 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).

Contour lines of constant salinity are called isohales.

Systems of classification of water bodies based upon salinity[link]

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 the right, modified from Por (1972),^[6] follows the "Venice system" (1959).^[7]

In contrast to homoiohaline environments are certain poikilohaline environments (which may also be thallassic) in which the salinity variation is biologically significant.^[8] 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), is referred to as brine.

Environmental considerations[link]

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).^[9] A plant adapted to saline conditions is called a halophyte. Organisms (mostly bacteria) that can live in very salty conditions are classified as extremophiles, or halophiles specifically. An organism that can withstand a wide range of salinities is euryhaline.

Salt is expensive to remove from water, and salt content is an important factor in water use (such as potability).

The degree of salinity in oceans is a driver of 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, the hydrography is such that a possible cause of reduced circulation is the production of stratified oceans. Hence it is difficult in this case to subduct water through the thermohaline circulation.

See also[link]

References[link]

Further reading[link]

• Mantyla, A.W. 1987. Standard Seawater Comparisons updated. J. Phys. Ocean., 17: 543–548.
• Equations and algorithms to calculate fundamental properties of sea water.
• History of salinity.
• Practical Salinity Scale 1978.
• Practical salinity calculator.
• Lewis, E. L. 1982. The practical salinity scale of 1978 and its antecedents. Marine Geodesy. 5(4):350–357.
• Equations and algorithms to calculate salinity of inland waters

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Do or Die
Background information
Origin	Chicago, Illinois
Genres	Hip hop
Years active	1995–present
Labels	Rap-A-Lot Records
Associated acts	Twista The Legendary Traxster Johnny P. Crucial Conflict
Members
AK-47 Belo Zero N.A.R.D.

Do or Die is an American rap trio originally from Southside of Chicago, Illinois, consisting of group members Belo Zero, N.A.R.D. and AK-47. The trio has sold more than 3 million albums. The group experienced mainstream success with the gold single "Po Pimp", Produced by The Legendary Traxster off of their 1996 debut album Picture This The song, which featured fellow Chicago rapper Twista, peaked at #22 on the Billboard Hot 100.^[1]. The songs "Playa Like Me and You" and "Alpha and Omega" made the album "Picture This" a classic and made Do or Die an instant success. Do or Die's success with "Picture This" helped launched the careers of Legendary Traxtster, Twista and Johnny P who sang the hooks on several Do or Die songs.

Alongside Crucial Conflict, another Chicago group with a similar vocal and lyrical style, they helped launch one of the city's first national hip hop movements. They rapped with a signature fast flow over silky smooth rhythm blues beats. Their rapping and musical style influenced Twista]]. The group's second album Headz or Tailz Produced mainly by producers Mr. Lee and Mike Dean debuted in 1998 and went Gold. Its lead single was a follow-up to the group's previous hit titled "Still Po Pimpin'". It peaked at #68 on the Billboard Hot 100.

The group continued to release several albums during the 2000s decade. The album entitled " Pimpin Aint Dead" includes "I Wish I Could Fly" and smash hit "Do You" featuring Twista. "Do You" which was regarded as the number one song downloaded on Youtube in 2010. In 2005, Do or Die released their 7th album entitled D.O.D. which featured the hit single "Higher" produced by fellow Chicagoan Kanye West. In 2009, Do or Die gave Twista a boost with the single "Yo Body" which is featured on Twista's album entitled "Category 5". "Yo Body" became an instant Youtube sensation with over 2 million hits.

The group's 8th album, was released as a mixtape entitled Trunk Music, in 2010.

For the past decade Do or Die has been touring the country giving their fans the signature Do or Die sound and stage performance fans can't get anywhere else. Do or Die is currently working on their next album to be released on their own label in late 2012.

Discography[link]

• Picture This (1996)
• Headz or Tailz (1998)
• Victory (2000)
• Back 2 the Game (2002)
• Pimpin' Ain't Dead (2003)
• D.O.D. (2005)
• Get That Paper (2006)
• Trunk Music Mixtape (2010)

References[link]

External links[link]

• Do or Die on Myspace
• [1] Do or Die- Pimp On