M. V. Markelov

Spatial and temporal features of soil erosion in the forest-steppe zone of the East-European Plain

Data on the rate of the erosion-accumulation processes within the sloped junctions of soils studied on key plots in Tula, Kursk, and Belgorod oblasts were analyzed. Using the method of different-age tracers characterizing the erosion-aggradation of the soils during the last 140–150 years (the magnetic tracer) and during the last 20–25 years (the radiocesium tracer), the spatial and temporal features of the redistribution of the drifts on typical slopes in different parts of the forest-steppe zone of the East-European Plain were established. A clear trend of an increase in the soil erosion rate in this zone during the last 20–25 years was revealed compared to the average rate for the last 140- to 150-year-long plowing period, which was related to the climate warming, an abrupt reduction of the surface runoff during the spring snowmelt period, and the increasing soil-protecting role of the agricultural plants in the crop rotations because of the decrease in the proportion of row crops. The obtained results confirmed the continuous nature of the soil erosion and accumulation during the transport of the sediments, which was manifested in the alternation of the erosion zones and deposition zones on the slopes.

Chernobyl 137Cs redistribution in the small basin of the Lokna river, Central Russia

Abstract The redistribution of Chernobyl 137Cs within a small drainage basin was studied in the Lokna river basin, Tula region, Central Russia. Sheet erosion on the cultivated part of basin is the main reason for 137Cs horizontal migration. However there is no statistically significant 137Cs redistribution within cultivated field because of relatively low erosion rates. The valley bottom is the main sink of 137Cs, where 73–84% eroded soil is stored. The resulting 137Cs level in the valley bottom is 1.5–2 times that of the initial 137Cs fallout.

Problems in determining spatial inhomogeneity of 137Cs fallout for estimating rates of erosion-accumulative processes

The issues of assessing variability of 137Cs fallout of global and Chernobyl origin at reference sites are discussed with a purpose to use this isotope as a tracer for estimating the rates of erosion-accumulative processes. It is shown that local variability of soil contamination by 137Cs at reference sites is within 7–20%, which makes it possible to use the isotope as a tracer. When studies are conducted within drainage basins, the available trend of the atmospheric 137Cs fallout should be taken into account in assessing the soil and sedimentation redistribution.

Comparative assessment of the contents of magnetic spherules, 137Cs, and 210Pb in soils as applied for the estimation of soil erosion

The contents of magnetic spherules and 137Cs and 210Pb isotopes were determined in gray forest soils of the Novosil Agroforest Experimental Station in Orel oblast (central part of European Russia). The spatial variability in the contents of these substances was studied, and their distribution in the soil profiles and along soil transects within the afforested and cultivated slopes was analyzed. Factors and processes favoring the accumulation of magnetic spherules and 137Cs and 210Pb isotopes in the soils, as well as their removal from the soils, were revealed. Similarities and distinctions in the patterns of their behavior were interpreted. Prospects for the combined use of these three tracers to estimate the rates of soil erosion and sediment deposition on the soil surface were tested.

ОСОБЕННОСТИ ТРАНСФОРМАЦИИ РЕЛЬЕФА МАЛОГО ВОДОСБОРА РАЙОНА ТОРЖОКСКОЙ КОНЕЧНО-МОРЕННОЙ ГРЯДЫ ЗА ПЕРИОД АГРИКУЛЬТУРНОГО ОСВОЕНИЯ

Estimations of erosion-accumulation processes rate during intensive agricultural development were obtained by different methods for one of the small watersheds of secondary-glacial relief (Tverskaya region, Osuga river). Though the watershed has maximum treated area and relatively high field gradient, the average rates of erosion and accumulation are low. This helps to draw a conclusion that agriculture development has little impact on the other watersheds’ relief while they have the same deposits composition (moraine on the surface).