CHEMICAL ELEMENTS IN SOILS AND SURFACE WATERS OF THE UKOK PLATEAU (SOUTH-EASTERN ALTAI)
The relevance of the research is in the poorly studied chemical composition of soils and surface waters of the Ukok plateau - the UNESCO world heritage site. The aim of the research is to study chemical elements content level in soils and surface waters of the central, southern and south-eastern parts of the Ukok plateau, to give an ecological and biogeochemical assessment of this little-studied area. Objects: main soil types (Mollic Leptosols Eutric, Umbric Leptosols Dystric, Lithic Leptosols Brunic) and surface water (rivers Zhumaly, Kalguty, Argamzhi, Ak-Alakh, Tarkhat and lake Ukok) of the plateau Ukok (Altai Republic, Russian Federation). Methods. Metal content in soils was determined by the approximate-quantitative emission spectral analysis at the Institute of Geochemistry and Mineralogy of SB RAS, while the content of trace elements in natural waters was defined by means of the atomic absorption spectrometry using electrothermal atomization at the Chemical Analytical Center of IWEP SB RAS. Results. The paper presents the results of studying chemical composition of different types of soils and surface waters of the high-mountain plateau Ukok. The concentrations of chemical elements in soils of the plateau do not exceed their Clarks in the soil cover and correspond to those in the mountain-tundra soils of Altai, except for the soils and parent rocks above the Kalguty W-Mo-V-Cu deposit distinguished by the abnormally high content of tungsten (up to 30-60 mg/kg). The increased content of Cu in the waters of the river Kalguty (16 μg/dm<sup>3</sup>) and the soils of the basin is related to the halos and the influence of pilings and tailings of the concentration plant. The plateau soils are characterized by low gross content of P and Ca needed for plants, but enriched with potassium, the content of which exceeds 2 % in more than half of the samples. In soils of the Ukok plateau, P content increases from west to east, from true surface (central) part to the edging mountains that is due to phosphor presence in indigenous rocks of the Altai-Sayan mountain country. At present, low eluvial-accumulative ratios of metals in the studied soils of the plateau are evidence of the lack of pronounced anthropogenic pollution. The content of most elements in soils increases with depth. In mountain-tundra peat soils, the biogenic accumulation of Mn was found under dwarf birches. For steppe soils, some accumulation of Zn, Cr, V and Ni was observed in surface horizons. Pb and Zn had the most uniform distribution. The initial heterogeneity of moraine and lake-glacial deposits determines the diversity of intra-profile distribution of metals in the formed soils. Clear dependence of most macro-and microelements content in surface waters on their concentrations in soils was not established. Nevertheless, there was an increase in the intensity of water migration of iron in wetlands of the Bertek part of the Ak-Alakh river basin, where its content was the highest.