Soil-Geochemical Characteristics of Landscapes in the Upper Reaches of the Klyaz’ma River

The distribution patterns of microelements in soils along two soil-geochemical catenas within the Chashnikovo Training and Experimental Soil Ecology Center (TESEC) of Moscow State University in Moscow oblast have been studied. The first catena, Klyaz’ma, is allocated to the northeastern slope of the Klyaz’ma River valley and includes eluvial, transit, transit–accumulative, and superaquatic landscapes. A carbonate double-sided biogeochemical barrier was diagnosed on this catena at the contact zone between the transit and the transit–accumulative landscapes. A distinctive feature of this catena consists in the modern functioning of the superaquatic landscape at its posthydromorphic stage of development. This catena is of the heterolithic type, because there is a transition from mantle loams on moraine to alluvial deposits within its boundaries. The second catena, Kirpichnoe Pole, consists of eluvial and a series of transit–accumulative landscapes of various hydromorphism rates. The eluvial landscape is located on the well-drained upper part of the northeastern slope. The second site within the transit–accumulative landscape is situated in the contact zone of the partially drained lower part of the slope influenced by the Krasnyi Voin gully. The third and fourth sites of this landscape are characterized by increasing hydromorphism. Soils throughout the entire length of the catena are formed on mantle loams underlain by moraine, which enables us to assign it to the monolithic type. The relevance of this study is determined by the fact that the typological differences between the catenas and the presence of a carbonate biogeochemical barrier in one of them enable us to determine similarities and differences in the behavior of elements under different conditions. It reflects general features common to soils within southern taiga landscapes of Moscow oblast. The distribution pattern of elements in soils is explained by soil-forming processes, past agricultural activities, bioaccumulation processes, and the influx of pollutants due to the proximity of these landscapes to the M-10 highway (Moscow–St. Petersburg) and to residential buildings. There is a correlation between the content of silt fraction and of elements V, Cr, Fe, Ni, Cu, and As in texture-differentiated soils and between medium silt fraction and Mn, Fe, As, Mo, Cd, and Hg in alluvial soils. The increase in hydromorphism on the studied catenas results in the accumulation of iron-manganese concretions in soils. The carbonate barrier reduces the overall migration flow, primarily of elements of the iron family.