Реконструирована история деградации оледенения в бассейне высокогорного озера Сылтранкёль (Приэльбрусье, Северный Кавказ) с конца XIX до конца XX в. В 2022 г. произведено комплексное обследование котловины озера, включавшее отбор отложений и их последующее радиоизотопное датирование, анализ структур, текстур и гранулометрического состава, подсчет варв. Параллельно проанализирована совокупность литературных источников, топографических карт, наземных фотографий, космо- и аэрофотоснимков и собственных полевых наблюдений для определения положения краев ледников на разных временных этапах. Выделены четыре этапа в формировании донных осадков, коррелирующие с состоянием горного оледенения и изменениями конфигурации озерного водосбора. Сходимость результатов, полученных на основании независимых источников, подтверждает высокую методическую ценность исследования донных осадков горных озер как одного из немногочисленных архивов природной среды, фиксирующих изменения оледенения в динамичных природных условиях высокогорий. Deglaciation history of the Syltrankel high-mountain lake basin (Mt. Elbrus region, Northern Caucasus) from the end of the 19th to the end of the 20th centuries was reconstructed. In 2022, a comprehensive examination of the area was carried out, including sampling of the bottom sediments and following radioisotope dating, structural and textural analysis. Simultaneously, a set of published sources; topographic maps; ground, satellite, and aerial photographs; and field observations was analyzed to determine the positions of the edges of glaciers at different times. In the formation of bottom sediments, four stages were identified correlating with the state of mountain glaciation and changes in the configuration of the lake’s drainage area. Converging results obtained on the basis of independent sources indicate the high methodological value of studying bottom sediments of mountain lakes as one of the few environmental archives that record glaciation changes in the dynamic conditions of high mountains.

The potential of application of 232Th daughter radionuclides as tracer in lithodinamic and geomorphic investigations was explored. It was analyzed geochemical particularities of this radionuclide, its occurrence in rocks and sediments and ways of migration. A series of samples of sediments and river waters was collected within the Hackman canyon in the Khibiny Massif (the Kola Peninsula) and analyzed by a semiconductor gamma spectrometer to recognize activity of 232Th daughter radionuclides: 228Ac and 212Pb. In the 1930-s there was a lovchorrite mining within Hackman canyon, which tailings were enriched in 232Th. Their material is moved by different natural processes: mudflows, snow-water flows, erosion and complex slope processes. The spatial heterogeneity of radionuclide composition of loose sediments is detected, the analysis of which allowed to identify promising areas of geological-geomorphological studies and environmental risk assessment in the areas of production of radioactive thorium-containing rocks in the mountain conditions of Subarctic and protection of the natural environment.