Definition

A measure of the quantity of dissolved salts in SEA WATER. It is normally defined as the total amount of dissolved solids in SEA WATER in parts per thousand (‰) by WEIGHT when all the carbonate has been converted to oxide, the bromide and iodide to chloride, and all organic matter is completely oxidiz­ed. These qualifications result from the chemical diffi­culty in drying the salts in SEA WATER. In practice, salinity is not determined directly but is computed from CHLORIN­ITY, electrical conductivity, refractive index, or some other property whose rela­tionship to salinity is well established. Because of the Law of Constancy of Proportions, the amount of CHLORINITY in a sea water sample is used to establish the sample's salinity. The relationship between chlorinity Cl and salinity S as set forth in Knudsen's Tables is S = 0.03 + 1.805 Cl. A joint committee of IAPO, UNESCO, ICES, and SCOR proposed the universal adoption of the following equation for determining salinity from CHLORINITY: S = 1.80655 Cl. It was adopted by IAPO in 1963 and ICES in 1964.