i have searched protocols for the estimation of a salinity of a sea water.but i need to know the widely used method please refer me good method
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. The distinctions between these different descriptions are important to physical oceanographers, but are obscure and confusing to nonspecialists.
Salinities were largely measured using titration-based techniques before 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 the ionic content of seawater led to the development of the so-called practical salinity scale 1978 (PSS-78). Salinities measured using PSS-78 do not have units. The 'unit' of PSU (denoting practical salinity unit) is sometimes added to PSS-78 measurements, however this is officially discouraged.
In 2010 a new standard for the properties of seawater was introduced, the so-called thermodynamic equation of seawater 2010 (TEOS-10). This standard includes a new scale, the so-called 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 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.
Ecologists commonly measure the electrical conductivity of seawater using an EC probe.
http://www.swrcb.ca.gov/water_issues/programs/swamp/docs/cwt/guidance/3130en.pdf
Apart from the above ones,there are 2 more physical methods also.
One is to make a standard graph for values of salinities vs.specific gravity.Having made that,from unknown sp.gr. salinity readings can be obtained.
Another method is through the Beaume meter,which works on similar principle as a say a Lactometer.Such a meter is usually used in solar salt pans.But the same can be made having taller column for greater clarity.
Chandravadan Trivedi ·using as a probe says EC, or try a refractometer with proper salinity level
The easiest method to estimate salinity is by measuring the EC (Electric Conductivity) of the water. Moreover, There is a "rule of thumb" that says that if you multiply the EC value, when expressed in units of decisiemens/m, by a factor of 10 you have a yough estimation of the concentration of chlorides in meq/l.
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