Lateral and Radial Differentiation of Cryogenic Soils Chemical Composition in the Vilyuy River valley, Central Yakutia

Abstract

The subject of the study is the soil-geochemical features of cryogenic mid-taiga landscapes of the Vilyuy River valley in its middle course, located near Mahatta and the village of Kysyl-Syr of the Republic of Sakha (Yakutia). Morphological descriptions of soil profiles were compiled. Chemical and analytical laboratory work was carried out in order to establish the values of the physico-chemical parameters of soil horizons - pH, the content of easily soluble salts, the content of organic carbon, granulometric composition, fractional composition of iron. The main aspect of the soil-geochemical properties of the landscapes of the middle Vilyui River is the gross chemical composition of cryogenic soils. The gross contents of chemical elements were determined by X–ray fluorescence using portable X-ray diffraction, after which the geochemical coefficients of radial (profile) and lateral (catenary) differentiation of concentrations of chemical elements R and were calculated. In automorphic soils, most of the chemical elements are removed from their surface organic horizons, and in mineral ones they are concentrated. Ca, Ti, Mn, Fe, Zn and Zr differ by the highest values of the coefficients R (R reaches 20). The radial differentiation is significantly influenced by acidity, organic carbon content and other soil properties, for example, the increased content of Si, Ca, V and Zn (R up to 1,3–3,7) relative to the horizon of soil parent rocks which is associated with the content of Sorghum. In terms of lateral differentiation, most of the studied elements are characterized by accumulation in the upper part of the soil-geochemical catena. The catenae Ca, Mn, Fe, Zn and Y are most widely distributed in soils (LCa = 0.3–1.8; LMn = 0.1–2.0; LFe = 0.6–2.1; LZn = 0.9–2.9 and LY = 0.3–1.4).