“…However, the chemical composition of seawater is not exactly constant. Regional deviations of seawater composition and properties were occasionally investigated, in particular in the 1970s (Rohde, 1966;Cox et al, 1967;Kremling, 1969Kremling, , 1970Kremling, , 1972Connors and Kester, 1974;Brewer and Bradshaw, 1975;Millero et al, 1978;Poisson et al, 1981;Millero, 2000), but were generally considered of minor relevance and ignored by previous international oceanographic standards (Forch et al, 1902;Jacobsen and Knudsen, 1940;Lewis, 1981;Millero, 2010). However, the effects of these compositional variations are measureable, and are easily the largest single factor currently limiting the accuracy of empirical formulas for the thermodynamic properties of seawater.…”