Mr Fedor Darin (Budker Institute of Nuclear Physics SB RAS)
Samples of modern bottom sediments of Lake Shira (Khakassia) was obtained in the form of frozen bulk contained the upper 20cm of bottom sediments using special sampling equipment (ice-corer). This procedure guaranteed the receiving of the unmixed and undamaged upper sediment layers. The preparation of solid samples for measurements was carried out by a vacuum drying technique and impregnated with epoxy resin . Measurements of the distribution of rock-forming and trace elements in cores of bottom sediments were carried out on XRF station at VEPP-3 and by method described in the article  at an excitation energy of 22 keV with a scanning step of 200 μm. Investigations of individual annual layers with a width of 0.5 - 1.5 mm were carried out on experimental module X-ray Confocal Microscopy  situated on NRC “Kurchatov Institute”. The experimental parameters are excitation energy 20 keV, the size of the excitation radiation spot on the sample is 20 μm, the scanning step is 20 μm, the measurement time at the point is 10 sec. Each investigated annual layer was crossed by a profile of 25-75 points which made it possible to create a model for the accumulation of microelements during the annual cycle of sedimentation. This work was partially supported by Comprehensive program of fundamental scientific research of the SB RAS project №0330-2018-0021. 1. Dar’in, A.V., Kalugin, I.A., Maksimov, M.A. et al.// Scanning X-ray fluorescence microanalysis of annual layers in samples of Lake Shira bottom sediments// Bull. Russ. Acad. Sci. Phys. (2013) 77: 185. 2. Sorokoletov D.S., Rakshun Y.V., Darin F.A. // The spread function of a polycapillary lens and a confocal x-ray microscope in retuning its confocal volume// Optoelectronics, Instrumentation and Data Processing. 2015. Т. 51. № 3. С. 293-301.
Dr Andrey Darin (Sobolev Institute of Geology and Mineralogy SB RAS)
Dr Alexey Seregin (NRC «Kurchatov Institute») Dr Denis Rogozin (Institute of Biophysics of SB RAS) Mr Dmitry Sorokoletov (Budker Institute of Nuclear Physics SB RAS) Mr Fedor Darin (Budker Institute of Nuclear Physics SB RAS) Dr Ivan Kalugin (Sobolev Institute of Geology and Mineralogy SB RAS) Dr Roman Senin (NRC «Kurchatov Institute») Dr Tatyana Markovich (Sobolev Institute of Geology and Mineralogy SB RAS) Dr Yakov Rakshun (Budker Institute of Nuclear Physics)