Abstract
The article presents materials from our own research on the study of the distribution of the mineralization, ionic composition, hardness, dissolved gases and pH values in various components of the river ecosystem of the Kazakhstan part of the Ertis river basin in the summer of 2023. It has been established that the water of the Black Ertis river is ranked in terms of mineralization to ultra-fresh, the value of total hardness – to soft, the content and ratio of the main ions - to the carbonate class, calcium group, the second type. Within the Pavlodar region, the concentration of the main salt-forming ions in the water of the Ertis River increases on average by 1.7...2.4 times, the water becomes fresh, the Alekin water index remains CCaII throughout the entire flow. The mineralization of water in the floodplain lakes Orlovskoye, Staritsa, Kurkol differs little from the water of the river Irtysh. The value of all studied indicators in the water of the Ertis River, its tributaries and lakes does not exceed the maximum permissible concentration. The water of all studied water bodies, with the exception of the storage lake Balkyldak, in terms of the content of standardized main ions and mineralization, belongs to quality class 1, is suitable for all types of water use and corresponds to “very good” quality. The wastewater storage tank Balkyldak has water of high salinity (19.42 g/dm3), very hard, highly metamorphosed sodium chloride composition of the third type and it can be recommended for the extraction of bischofite, halite and gypsum.