Solubilities of gypsum and halite in the Dead Sea and in its mixtures with seawater1

The solubilities of gypsum (CaSO4·2H2O) and halite (NaCl) in aqueous solutions with ionic strengths between 3 and 13 were studied under ambient conditions. Mixtures of Mediterranean seawater and Dead Sea brines, evaporated to various degrees, served as experimental solutions. The practical solubility constant of gypsum [KGsp = (mCa × mSO4) eq] was found to be related to the ionic strength (I) of the solution by the empirical expression urn:x-wiley:00243590:media:lno19812640709:lno19812640709-math-0001 This relationship was then applied to calculate the degree of saturation with respect to gypsum (DSG) of the present Dead Sea water column. Calculations indicate that the entire Dead Sea water column (ionic strength = 9–10) is saturated or even slightly oversaturated with respect to both minerals studied.