Estimation of Water-rock Interaction during the Vertical Profiles of Prairie Brackish Lakes of the Altay Region, Western Siberia: Preliminary Results

The article presents the comparative characteristic of lake water and pore water of bottom sediments of saline lakes located in the South of Western Siberia. Studied lakes are mostly Cl-Na composition and rarely Cl-HCO3-Na. The values of pH vary from 7.6 to 9.9, TDS from 5 to 300 g/L. It is shown that redox conditions change from oxic in the upper water layer to anoxic in pore water and the bottom layer. As a result, there is dissimilarity in interaction between water layer, bottom sediment and secondary minerals caused by differences in biological and geochemical processes in these two environments. According to thermodynamic calculations, lake water is in equilibrium with calcite, quartz, kaolinite, illite, Mg-montmorillonite, barely with respect to gypsum, thenardite and halite. Simultaneous formation of evaporite minerals and bacterial mats, CH4 and H2S accumulation lead to microbial sediment development.