THE STATE OF THE CARBONATE-CALCIUM EQUILIBRIUM OF THE KAZAKH PART OF THE ERTIS RIVER BASIN

The materials of our own studies of the carbonate-calcium equilibrium in the Kazakh part of the Ertis river basin, conducted in July 2023, are presented. It has been established that the rivers and lakes of the Ertis basin differ in the state of carbonate-calcium equilibrium. This difference is due to a number of factors: carbonate alkalinity, total mineralization, pH value, water temperature, which in turn depend on the physical and geographical conditions of the region. The Kara Ertis River, its tributaries and Ertis itself in all areas have water unsaturated with calcium carbonate, containing aggressive CO2 in concentrations (0.02...5.50 mg/dm3), which do not pose a danger to concrete structures on Portland cement. The amount of supersaturation of CaCO3 water in rivers ranges from 0.03...0.92. In the isolated lakes Orlovskoye, Kurkol and Eski Ertis, an excess of the main equilibrium indicators was noted compared to rivers, the water in them becomes supersaturated with calcium carbonate by an average of 1.16...5.82 times. The water of the Balkyldak wastewater storage lake does not contain aggressive CO2, however, according to the content of normalized magnesium ions, chloride and sulfate ions, the water shows an aggressive effect on the cement stone of hydraulic structures of varying degrees.