Review of chemical properties of inland soda and saline waters in East Africa (rift valley region)

Study region: Inland soda and saline lakes of the East African Rift Valley (EARV).Study focus: This study reviews the chemical properties of inland soda-saline lakes of the EARV, classifies lake water chemical types, and assesses the spatial distribution of the major ions. The chemical data were collected from published articles (1968-2022) where the salinity (TDS) exceeded 1 g/l concentration. Based on the total alkalinity and pH, the modified formula was used to estimate the concrete proportions of CO32-and HCO3-. The lake's water chemical type was classified using (Boros and Kolpakova, 2018) classification criteria. ESRI ArcMap 10.2 GIS soft-ware was used to analyze the spatial distributions of major ions.New hydrological insight of the region: Following the critical review of the EARV soda saline lakes the dominance of cations and anions followed the order: Na+ > K+ > Ca2+ > Mg2+ and HCO3-+ CO3-> Cl-> SO42-. Tanzania had the most soda-chemical type lakes (20), followed by Ethiopia (9), Kenya (8), and Uganda (4). Soda-saline lakes were the most common in Tanzania (5). Saline lakes were mostly found in Uganda (4), Tanzania (3), and Ethiopia (1). Except for Afrera Lake in North Ethiopia and Uganda (Western Rift), the concentration of Na+, Cl-, CO3-ions, and TDS showed an increasing concentration gradient tendency from north to south in the Eastern Rift.