Indicators of Oxic and Anoxic Conditions in the System of the Current Sedimentation of Saline Lake Shira (Khakassia), According to High-Resolution SR XRF Data on Bottom Sediments Frozen In Situ

Frozen upper layers of the bottom sediment of Lake Shira are selected using special sampling equipment. Frozen samples and solid samples prepared from the upper layers of a sediment core are examined by means of X-ray fluorescence at the Local and Scanning X-Ray Fluorescence Elemental Analysis Station of the Siberian Synchrotron and Terahertz Radiation Center’s Shared Resource Center. Analytical data on the initial frozen and processed solid samples demonstrate the good repeatability of the results. Quantitative estimates of the sedimentation regimes are obtained, and geochemical indicators of the change in redox conditions are determined from the analysis data. Lithological and geochemical records are synchronized with regional seasonal and annual variations in weather and climate, and with the hydrological regime of the lake for the last 50 years.