Home – Home – Jornals – Geography and Natural Resources 2020 number 5S

Ultra-fresh waters belonging to the hydrocarbonate class, the calcium group and the the second type (after Alekin). The study revealed dif ferences in the value of water mineralization between the northern and southern parts of the coast; it reaches 190 mg/L or higher in the north and only rarely exceeds 80 g/L in the south. It is shown that the ionic composition of the waters in the Bugul’deiskii and Slyudyanskii districts differs greatly from the water composition in the other districts: the former are character ized by an increased hydrocarbonate content (up to 99 %-eq of the sum of ions), and the latter-by an increased sulfate content (up to 50 %-eq of the sum of anions). A discrepancy was determined between the taxonomic uniformity of the waters and the variety of the values of the concentration ratios of cations ((Ca²⁺ + Mg²⁺)/K⁺) and anions (SO4^2-/ HCO^-3) which represent tracers of the sources of dissolved matter. It is concluded that there is a need to develop the classification principles for the wa ters at the level of subclass es or subgroups, and the criteria for identifying them can be provided by the values of the contributions - from the sources of dissolved matter calculated on the basis of the (Ca²⁺ + Mg²⁺)/K⁺ and SO4^2-/ HCO3 ratios.