Geochemical Features of Cryogenic and Al-Fe-Humus Soilsof Mountain Taiga in Northern Mongolia
Geochemical features of cryogenic soils (Folic ProticLeptic Cryosols, Histic Protic Leptic Cryosols) and Al‑Fe-Humus (Folic Leptic Entic Podzols, Histic Leptic Entic Podzols) have been considered. These soils are widespread in the soil cover of taiga forests forming the upper boundary of forest belt in Khentei, Prikhubsugulie and Khangai mountainous massives. Data on the microelement composition of parent rocks are given as well. The dispersion coefficients of the most studied microelements in parent rocks relative to the lithosphere exceed 1.0, which indicates the predominance of removal processes in them. Difference in the concentrations of microelements is related to the particle-size composition of parent rocks. Data on soil morphology, soil physicochemical and chemical properties, in particular, on the concentrations of microelements and their radial distribution in soils are discussed. It was shown that the studied soils differ both by the absolute amounts of microelements involved in the biological cycle, and by the intensity of their involving in biogenic migration. The intensive biogenic migration of elements results in their accumulation in organic and raw-humus soil horizons and in the accumulative profile patterns in soils of the altitudinal-belt complexes of forest types. In contrast to cryozems, the organic and raw-humus horizons of podzols are characterized by a lesser accumulation of microelements. It was noted that in the middle-profile Al-Fe-Humus (spodic) horizon of podzols, the concentration of Pb, Cr, Mo and B is higher than 1.0. Al-Fe-Humus horizons of studied soils can serve as a sorption geochemical barrier for some elements belonging to the groups of biophiles and of iron.