Principal Parameters Controlling Water Composition in Saline and Brackish Lakes in Eastern Transbaikalia

Abstract

Extensive field hydrogeochemical data and thermodynamic simulations demonstrate that the composition of lacustrine waters is controlled not only by evaporation but also by interaction between the waters and rocks. This interaction begins in the catchment areas of the lakes and continues in these lakes themselves, because the waters (regardless of their salinity) do not occur in equilibrium with many of the endogenic minerals. These processes are the most intense in soda lakes, as follows from the highest pH of their waters (9.0–10.7). These values provide evidence that these waters most intensely interact with primary aluminosilicates. The two processes responsible for sulfur behavior in these lakes are sulfate reduction and sulfide oxidation. Different geochemical environments produced in lakes of different type are favorable for the selective enrichment of some elements, which are mobile in these environments and whose concentrations can significantly increase.