What value of salt concentration demarcates fresh from saline water?
The term salinity needs careful definition to avoid confusion with the oceanographic definition: for limnologists, salinity is the sum total of ions! A conventional value, now widely accepted, and with atleast some physico-chemical and biological basis, is 3 g/L or 3 o/oo. This salinity is near, i) the calcite branch point, ii) the low points between modes when the frequency distribution of salinity of all lakes over 100 sq.km area is plotted logarithmically, iii) the salinity at which most humans first begin to taste salt, and iv) the salinity below which biota typical of higher salinities are not found and above which the freshwater biota begins quickly to disappear or not extend. • Salt lakes are a good deal more varied in many physico-chemical features than freshwater lakes. Salinities are between 3 and >300 g/L (not <1-3 g/L as in freshwater lakes); salinity may vary widely on a seasonal (<50 - >300 g/L) or secular basis or, as in freshwater lakes, scarcely at all; and major ions
