FEATURES OF DISTRIBUTION OF RARE EARTH ELEMENTS IN THE WATERS AND BOTTOM SEDIMENTS OF SMALL LAKES OF THE BARABINSK LOWLAND AND THE KULUNDINSKY PLAIN

Abstract

The relevance of the study is caused by the need to increase the raw material base of sapropel raw materials in the Siberian region. In the Barabinsk lowland and the Kulundinsky plain, drainless lakes strongly predominate, among which the dominant position is occupied by small reservoirs (97,5 %) with sapropel deposits at the bottom. This is due to the presence of a peculiar mountain relief for these territories, which is genetically associated with suffusion-deflation processes. Taken into account the diversity of lakes, it is important to study the factors that determine the geochemical composition of the resulting sapropels. The main aim of the research is to determine the geochemical features of REE migration and fractionation in the waters and bottom sediments of the small lakes of the Barabinsk lowland and the Kulundinsky plain and, based on the study of lanthanides, to reconstruct the main sources of the substance entering the emerging sapropel deposits. Objects: waters and organomineral deposits of small lakes of the Barabinsk lowland and the Kulundinsky plain. REE distribution in the components of lake systems in the south of Western Siberia is poorly studied, especially in the waters. Methods. Field methods – bottom sediment core, waters were sampled from the catamaran according to standard methods using a cylindrical sampler with a vacuum gate designed by NPO Typhun, Russia (diameter 82 mm, length 120 cm) and a 1-liter bathometer. All variable physical and chemical parameters of water and bottom sediments were determined in the field. The entire volume of water was filtered by vacuum filtration using filters with a pore diameter of 0,45 microns. Analytical methods – water samples were analyzed for macro- and microelements in the Primorsky Center for Local Elemental and Isotope Analysis of the Far Eastern Branch of the Russian Academy of Sciences and the Analytical Center for multi-elemental and isotope research SB RAS, Novosibirsk. The main cations and anions were determined by liquid ion chromatography (HPLC-10AVp, SHIMADZU), and organic carbon was determined by IR detection on a TOC – V analyzer (Shimadzu, Japan). Trace elements were determined by the inductively coupled plasma method (ICP-MS Agilent 7500 and 7500c) (analyst E.V. Elovsky) and by the atomic absorption method of IGM SB RAS (analyst L.N. Bukreeva). The morphology and phase composition of sediment samples of various classes were studied using a scanning electron microscope (SEM) TESCAN MIRA 3 (Tescan, Czech Republic) equipped with an energy spectrometer «OXFORD XMAX 450+» (Oxford Instruments, UK). The REE content was determined in 112 samples of bottom sediments by the ICP-MS method. Results. The application of a unique methodological approach, expressed in modern biogeochemical, mineralogical, geochemical studies of a single lake in close relationship with the entire system of compactly located lakes (lake system) on the carefully selected lake systems: Barabinskaya, Kuibyshevskaya (Baraba) and Tanatarskaya, Petukhovskaya (Kulunda), gave an idea of the relationship of the modern formation of the composition of bottom sediments with the biogeochemistry of lake waters, with the composition of soils and soil-forming rocks of the catchment areas of the lake, the chemical composition of the autochthonous biota and the landscape conditions. The use of modern analytical methods allowed us to estimate the levels of concentrations and patterns of distribution of rare earth elements in the waters and bottom sediments of lakes from different landscape zones with different geochemical types of water (from ultra-fresh to brine) and sapropel class (silica, calcium, mixed with different genetic types).

Keywords

• small lakes of the south of western siberia
• geochemistry
• mineralogy
• rare earth elements
• water
• bottom sediments