In this work the received analytical material on bottom sediments more than 200 lakes is generalized in different landscape (climatic) zones of Western Siberia. The bottom sediments were studied by a set of modern methods of geochemistry, mineralogy, and crystal chemistry. We will try to highlight some of the general laws of horizontal and vertical distribution of natural radionuclides (NRN) in different types of bottom sediments of the inland lakes of Siberia. Based on NRN distribution in the bottom sediment of the lake, taking into account the mineral type of the sediment and water total mineralization, it can be argued that terrigenous silts inherit their contents in soils and soil-forming rocks, and correspond to NRN content in the upper continental crust to the greatest degree. Carbonate and organogenic silts are depleted of thorium, potassium and sometimes uranium, but under the certain conditions, there is selective accumulation of uranium. The reduced contents of thorium, uranium, and potassium in the bottom sediments of the in some landscape zones relate to the dilution of the studied sediments and soils by silica (quartz sand) or calcite (biochemical). Variations of the activity values of bottom sediment NRNs in different landscape zones are very small along the core, as well as within the water area of one lake. Exception is the vertical distribution of uranium in the bottom sediments of lakes, especially in the taiga and steppe zones. The estimates of the rates of undisturbed sedimentation during last 100 years, calculated by the model of constant flow (CF) by 210Рb, roughly correspond to the dates obtained through simple extrapolation by 137Cs. Considering the assumptions, we can think that the linear rate of sedimentation at their natural occurrence varies in the lakes of different landscape zones of Siberia: in forest-tundra and steppe landscapes, it is 0,9 – 2,4 mm/year; in taiga and forest-steppe it is 2,5–3,5 mm/year; in foothill-steppe, it is 3.0 - 4.5 mm/year.
|Журнал||International Multidisciplinary Scientific GeoConference Surveying Geology and Mining Ecology Management, SGEM|
|Состояние||Опубликовано - 1 янв 2017|