Lateral and Radial Differentiation of Cryogenic Soil Chemical Composition in the Vilyuy River Valley, Central Yakutia

Soil-geochemical features of cryogenic mid-taiga landscapes of the Vilyuy River valley in its middle course located near Makhatta sandy aeolian massif (tukulan) and the urban locality of Kysyl-Syr of the Republic of Sakha (Yakutia) have been studied. Morphological descriptions of soil profiles have been compiled. Chemical and analytical laboratory studies have been carried out in order to establish the values of the physical and chemical parameters of soil horizons: pH, the content of total dissolved solids, the content of organic carbon, granulometric composition, and fractional composition of iron. The main aspect of the soil-geochemical properties of the landscapes of the middle Vilyuy River is the gross chemical composition of cryogenic soils. The gross contents of chemical elements have been determined by a portable X-ray fluorescence analyzer. Then the geochemical coefficients of radial (profile) and lateral (catena) differentiation of chemical elements (R and L, respectively) were calculated. In automorphic soils, most of the chemical elements are removed from the surface organogenic horizons and are accumulated in mineral ones. Furthermore, among all elements, Ca, Ti, Mn, Fe, Zn, and Zr are characterized by the highest values of the R coefficient (up to 20). The radial differentiation is significantly influenced by the acidity of the environments, 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 soil parent rocks) is associated with the content of Corg. In terms of lateral differentiation, most of the studied elements are accumulated in the upper part of the soil-geochemical catena. Ca, Mn, Fe, Zn, and Y are most widely distributed in soils of the catena (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).