COMPARATIVE STUDY ON PHYSICO-CHEMICAL SEDIMENTATION OF CHEMICAL COMPONENTS IN LAKES NASSER AND BARDAWIL WATER, EGYPT. MAHMOUD M. HASSAAN Faculty of Science, Al-Azhar University, Cairo The present work is a comparative study on the geochemistry of sedimentation processes of chemical components in fresh and saline-hypersaline water of Lakes Nasser and Bardawil in Egypt. The study indi-cated the following results: 1. Pronounced combined role of thermal stratification, alkalinity, oxidising surface and reducing bottom water of Lake Nasser and colloidal matter in deposition of chemical major and trace anions and cations. 2. Combined and integrated interaction of salinity, evaporation, alkalinity, adsorption arid oxidation potential in deposition of chemical major and trace components in Lake Bardawil saline-hypersaline water.