Articles

A comparative quantitative analysis of croplands masks of the Bryansk region was conducted by an expert method using the archive of remote sensing data from Google Earth. The first mask, with a spatial resolution of 250 m per pixel, was exported as part of the FAO GSNmap project. This mask is a product of the Land Cover global map provided by the Copernicus Global Land Service and is based on PROBA-V satellite images. The second mask was obtained from the Land Use/Land Cover (LULC) global map which is derived from Sentinel-2 satellite data. The mask was exported at a spatial resolution of 250 m per pixel. The overall accuracy of the Agrochemical Service, FAO, and LULC masks was calculated based on the visual interpretation of 900 randomly selected land plots in the Bryansk region. The accuracy values were 88.11% for the FAO and 88.00% for the LULC mask, and the kappa indices were 0.68 for FAO, and 0.67 for LULC mask. A comparative analysis of the FAO and LULC masks revealed a similarity of 81% between them. The conducted research indicates a high level of reliability of the cropland masks of the Bryansk region, based on satellite data from PROBA-V and Sentinel-2.

The paper evaluates the effect of erosion processes on the agrochemical and microbiological properties of the soil in different seasons of the annual cycle. The objects of the study are agro-gray soil of varying degrees of water erosion (uneroded, slightly and moderately eroded) and gray soil under woody forest plantations (south of the Moscow region). It was found that the content of alkaline hydrolyzable nitrogen, exchangeable potassium and mobile forms of phosphorus in the soil depended both on the degree of soil erosion and on seasonal fluctuations. Analysis of the chemical composition of soil organic matter showed that in the summer there was an increase in carboxylic, carbonyl and aromatic components, and in other periods – carbohydrate fractions. In the agro-gray soil, bacterial biomass stocks ranged from 27 to 96 kgha‒1, fungal biomass – from 10 to 357 kgha‒1, their dynamics were determined to a greater extent by the degree of washout and to a lesser extent by the season. With an increase in the degree of washing, both fungal and bacterial biomass decreased in the series unwashed>slightly washed>medium washed. Washed-away soils lost an average of 50% of bacterial and 59% of fungal biomass relative to non-washed soils. In the gray soil, bacterial biomass stocks varied seasonally from 43 to 107 kgha‒1, and fungal biomass from 171 to 621 kgha‒1. The gray soil under forest was superior in microbial pool to all variants of agro-gray soil, and was also characterized by a high content of mycelium, both actinomycete and fungal. In the studied soils, the level of potential respiration (SIR) exceeded the level of actual respiration (BR) by 2‒33 times. Microbial biomass reacted most actively to the introduction of glucose in the average washed soil in the spring and summer periods.

Thermal properties of the upper arable horizon of urban soil sampled on the territory of the Experimental soil station of Moscow State University, birch biochar, and their mixtures were studied. Soil from the Ap horizon was sieved through a 1 mm sieve and then mixed with biochar in various proportions; the biochar content in the mixtures ranged from 1 to 15% by dry weight. Plastic cylinders 5.1 cm high and 7.7 cm in diameter were filled with soil, biochar, and their mixtures. The bulk density of the samples varied from 1.34 g·cm–3 for the Ap horizon to 0.28 g·cm–3 for biochar. Thermal properties were measured with a probe method using a TEMPOS device with an SH-3 probe; the distance between the probe needles was 0,6 cm. A series of measurements were performed for each of the six samples with a stepwise change in sample moisture content from the maximum one after capillary saturation to the minimum one in an air-dry state. At each moisture content for each sample, the thermal properties were measured in tenfold repetition, successively placing the probe in different positions within the central zone of the sample. The heat capacity, thermal conductivity, and thermal diffusivity of the substrates consistently decreased with increasing biochar content over the entire moisture content range; the highest values of all thermal properties were obtained for the Ap horizon, and the lowest for biochar. All samples demonstrated a linear growth of volumetric heat capacity with moisture content, and the slopes of the obtained curves were quite similar. The specific heat capacity of soil moisture calculated from the experimental data was equal to 3406.8 J·kg–1·K–1, which confirms the concept that the heat capacity of water in the soil is less than the heat capacity of free water. The thermal conductivity of biochar increased almost linearly with moisture content. The thermal conductivity of soil and mixtures increased rapidly with moisture content in the range of 0.03–0.20 cm3·cm–3, then the growth slowed down, and with an increase in moisture above 0.45 cm3·cm–3, the thermal conductivity decreased. The thermal diffusivity of biochar was very low and almost constant over the entire moisture range. The thermal diffusivity vs. moisture content dependences for soil and mixtures were similar to the curves for thermal conductivity, but had two weakly expressed maxima, the first of which was observed at moisture content below 0.20 cm3·cm–3. It is concluded that the introduction of biochar into loamy soil reduces its thermal diffusivity and thereby stabilizes the soil temperature regime, reducing the range of diurnal temperature fluctuations and slowing down seasonal warming. For urban conditions with high summer temperatures, this effect can be regarded as positive; for regions with low heat supply, the introduction of biochar into the soil is rather undesirable, at least in the context of soil temperature regime.

The patterns of transformation of n-alkanes as biomarkers were studied to assess the transformation of petroleum products (NP) in oil-contaminated soils of the chestnut range (Stavropol region) in dynamics. The patterns of hydrocarbons conversion in oil-contaminated soils are revealed, and the possibility of launching self-purification processes based on the results of an assessment of the composition of NP was shown. Medium-molecular n-alkanes were dominated in the oil composition. The absence of high-molecular weight n-alkanes (heavy fractions) and the presence of liquid ones (a part of the kerosene fraction) were the main feature of the hydrocarbon state in background uncontaminated soils. This indicated the existing regional background in the content of NP in soils. Homologous series of n-alkanes of freshly oil-contaminated soil samples included compounds with a number of carbon atoms from C11 to C40, which contain markers of organic matter of hydrobiont genesis (C15, C17, C19), markers of organic matter of bacterial genesis (C20–C25) and markers of terrigenous humic organic matter (C27, C29, C31). Normal alkanes with the long carbon chain C20–C25 and C26–C40 were represented in almost equal proportions with a slight predominance of the latter. It was shown that after 4 months from the moment of crude oil contamination, the results of soil self-purification were recorded, leading to a change in the composition of n-alkanes. The biodegradation of n-alkanes in soils was confirmed by an increase in the carbon of microbial biomass in oil-contaminated soils relative to background analogues. The nature of the distribution of even and odd homologues of n-alkanes, the amount of the sum of odd n-alkanes (ΣC27, C29, C31) are advisable to evaluate along with the total content of NP, when choosing background analogues of soils.

Paleopedological studies were conducted on the territory of the Kostenkovsko-Borshchevsky district. The K12 ancient human site is a reference section for regional studies of paleopedology, paleoecology, geological and cultural sequences. K12 contains a complete series of cultural layers related to the first part of MIS-3 in the range of 53–42 thousand years BP. This study is a continuation of previously conducted work on the K1 site, located on the opposite side of the “Pokrovsky Log” balka. In excavation K12, 16 lithological layers were identified, differing in structure, composition and properties. The material composition of the sediments is represented by chalk eluvium, which forms the sides of the balka, and loess-like loams of the watershed. Deposits with different proportions of chalk and loam were formed in the aqueous and aerial phases of sedimentation. In the excavation, about 5 m deep, three buried soils were found. The age of the lower one is about 50 thousand years BP. Cultural layers are confined to paleosols. Paleosols are an indicator of breaks in sedimentation. Four soil-sedimentary complexes were identified in the excavation. A description of the processes and the chronological sequence of their formation is given. The conducted research opens up new aspects in the study of buried soils of gully sedimentary complexes.