Distribution of the major ions in Lake Nasser. II. Major cations

Abstract

       Seasonal and local variations of major cations in Lake Nasser were stu­died. Among the factors responsible for the irregularity in the vertical distribu­tion of cations are the movement of water masses, adsorption on and desorption from suspended matter and transport of eroded materials into the lake. The increase in the rate of evaporation in August caused the accumulation of the dissolved salts, as indicated by the high seasonal average values of sodium, magnesium and potassium. However, the minimum seasonal average calcium concentration was found in August, as the solubility of calcium carbonate con­centration was found in August, as the solubility of calcium carbonate decreases with elevation of temperature. The minimum seasonal potassium value in No­vember coincided with the highest level of flood and the great tendency of potassium to be adsorbed on the suspended and colloidal matter enriched in the flood waters. The gradual increase in the regional average values of sodium, magnesium and potassium towards the Hith Dam coincided with the influence of the flood waters, loaded with suspended matter and containing low salt content, first on the southern part of the lake.