The composition of soil organic carbon (SOC) is an important soil quality indicator. We investigated the effect of site-specific soil-forming factors on plant debris and SOC properties along a soil catena with Retisols and Stagnosols in a mixed coniferous–deciduous forest. We examined sites at the summit and middle slope positions with relatively well-aerated soils and sites at footslope positions with waterlogged soils. The concentrations of labile and stable pools of SOC were determined using the method of three-stage chemodestruction. The degree of litter decomposition was calculated, and ash content was determined in the folic and histic soil horizons. The results of our study showed that SOC mostly accumulated in the forest litter and histic horizons of Stagnosols at the footslope positions. The forest litter, folic, and histic horizons were dominated by labile carbon. Equal concentrations of labile and stable carbon were typical of the mineral horizons. The location of the soil in the catena affects the partition and characteristics of SOC in umbric and albic soil horizons. SOC was found to be more stable in the soils at the footslope positions compared to the soils in other locations, because of the lower decomposition of plant remains. Larger stocks of organic carbon, including labile carbon, were restricted to the footslope catena positions.

Late Holocene landscape evolution at the southern frontier of the forest belt of European Russia is studied based on detailed morphological, analytical and microbiomorphic research of a soil chronosequence that included a surface soil and a soil buried under the Bronze Age kurgan. Both soils (Folic Eutric Cambisols) are formed on similar geomorphic surfaces in the same parent material and in close proximity to each other. The soil morphology and the key analytical features are controlled by low-reactive parent material and imply close similarity of the present landscapes and those of the Bronze age. At the same time the morphological features show that the buried soil was influenced by the phase of weak aridization, which led to the formation of a dark mull humus horizon. Microbiomorphic assemblages (phytoliths, pollen) support the earlier conclusion that the soils of the study area had being developed mostly under forest vegetation.

Partitioning of metals in soil particles of various size classes has been receiving greater significance due to the necessity to predict the behaviour and pathways of the potentially toxic elements in the environment. In this study the analysis of metals’ distribution in various particle size fractions was performed to characterize and compare geochemical features of the topsoil horizons of two small erosional landforms located in uncontaminated area of the central part of European Russia (the Middle Protva basin, mixed forest zone). The landforms represent two typical lithological types of gullies in the study area. Soil samples were fractionated and the concentrations of Fe, Mn, Ti, Zr, Ni, Co, Cr, Zn, Cu, Pb were determined in five particle size fractions: 1–0.25, 0.25-0.05, 0.05−0.01, 0.01–0.001 and <0.001 mm. The metals’ concentrations and their distribution in various particle sizes were found to be related to gully litho-type. The contribution of the clay to the total amount of metals was the greatest for Mn, Zn, Ni and Co in both systems. The highest mass loading for Ti, Zr and Cr came from the coarse silt, while for Cu and Pb it was made by different particle size fractions: the medium and fine silt or the coarse silt. The highest contribution of Fe also came from different fractions, either from the coarse sand or the clay depending on the system.

The pathways and behavior of rare earth elements (REEs) in the soil environment have been receiving greater significance due to their wide use in technological applications, agriculture, and medicine over the last two decades and insufficient information on their health effect and participation in soil and geochemical processes. In this paper, we report original data on rare earth elements in various particle size fractions separated from the topsoil horizons of two small erosional landforms located in an uncontaminated area of the central part of European Russia (the Middle Protva basin, the Kaluga region). Soil samples were collected from the top 10 cm along several soil transects. Soils were sampled at the landforms sides, bottoms, detrital fans and catchment areas considered as sources of solid matter. The sampling scheme used makes it possible to assess the REEs distribution from catchments to bottoms of the erosional landforms, as well as along their thalwegs. The collected bulk samples (n = 22) were physically fractionated and the concentrations of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu were determined in five particle size fractions (1000-250, 250-50, 50-10, 10-1 and <1 µm, n = 100) by ICP-MS using Elan-6100 spectrometer (Perkin Elmer Inc., USA). The data obtained also include the concentrations of Fe and Mn (ICP-AES), as well as the information on the total content of organic carbon (TOC), pH and particle size distribution of the bulk samples. The obtained dataset can be used for various purposes: it is suitable as a baseline for the assessment of pollution levels, exploring natural and anthropogenic anomalies, for revealing the association of REEs with specific particle size fractions and detecting the effect of parent material and lateral translocations of soil material and soil particles on the REEs levels.