The results of studying the effect of fires on the biological properties of brown soils of xerophytic forests (Skeletic Leptic Cambisol) of the Utrish State Nature Reserve, Krasnodar Territory (crown fire of 2020), and burozem of mesophytic forests (Haplic Cambisol (Loamic)) of the Khamyshinsky forestry, Republic of Adygea (ground fire of 2018) are presented. Changes in the reaction of the soil environment, the content of organic carbon, and the activity of such enzymes as catalase, urease, phosphatase, and invertase involved in the cycle of carbon, phosphorus, and nitrogen have been studied. The reaction of enzymes to pyrogenic effects depends on the type of enzyme and the type of soil. A factor analysis was also carried out. The activity of catalase and invertase for two types of soils in a layer of 0–3 cm decreased by an average of 47%, while the reaction of phosphatase and urease differed depending on the soil type. Two years after the fire, the phosphatase activity of the surface layer of post-pyrogenic brown soils approached the control values; urease activity recovered more slowly compared to other enzymes. Four years after the fire, in the 0–3 cm layer, for the post-pyrogenic acid burozem, on the contrary, the values of urease activity approached the control values. An increase in pH values by an average of 30% and a decrease in the content of Corg by an average of 12% were also established for two types of soils. In the 3–10 cm layer, for brown soils, an average increase in the activity of all the studied enzymes was noted, while for acid burozem, on the contrary, a decrease. Factor analysis showed the presence of a relationship between the reaction of the soil environment, the content of organic carbon and the activity of enzymes, while the tightness and nature of the relationship differed depending on the type of soil. The results obtained indicate the influence of the edaphic features of the studied soils on the response of enzymatic activity to pyrogenic exposure.
The carbon reserves (C) and the rates of emission of greenhouse gases (CO₂and CH4) in peat soils of Western Siberia have been studied. The peat soils are typical for region oligotrophic ones (Histosols), but they develop in two contrasting bog ecosystems (a forested bog and an open bog), therefore, they differ significantly in modern vegetation cover, soil profile structure, hydrological and temperature conditions. It has been shown that the carbon reserves in the studied peat soils in the 0–50 cm layer are 9.3 and 6.8 kg/m² in the forested and open bogs, respectively. Measurements of CO₂and CH4 emissions were carried out by the chamber static method during the growing seasons from 1999 to 2014. The results showed that the studied soils release into the atmosphere the same number of CO₂(116.1 and 123.4 mg/(m² h) for soil in a forested and open bog, respectively), but at the same time significantly differ number of CH4 (0.57 and 2.66 mg/(m² h), respectively). This research has highlighted an important role of vegetation species composition and hydrological regime in estimates of carbon deposition and greenhouse gas fluxes from peat oligotrophic soils of bog ecosystems in the region.
The biomass and functional diversity of microbial communities were studied in the watershed, transit, and accumulative positions in catenas of virgin gray soils (Luvic Retic Phaeozems) and chernozems (Haplic Chernozems) of the “Belogorye” nature reserve and arable variants outside the reserve. Microbial biomass was determined by the substrate induced respiration (SIR) and the determination of the content of phospholipids. Multisubstrate testing of respiratory responses in the MicroResp system after the addition of amino acids, carboxylic acids and carbohydrates was carried out. It was established that in the virgin chernozem, microbial biomass decreased in from the watershed towards the accumulative part of the slope; in the gray forest soil, minimal values were in the transit part of the catena. In the plowed horizon of agrochernozems, it was close in all parts of the catena and 2–3.5 times less than in virgin chernozems. For the agro-gray soils, an increase in microbial biomass was fixed in the soils of the transit and accumulative parts of the catena. Cluster analysis of respiratory responses in the 0–10 and 10–20 cm layers identified two groups of the most demanded substrates. The first group in both layers included citric and ketoglutaric acids, the second – fructose and succinic acid. Ascorbic acid, sucrose, and glutamine were included in the first group in the 0–10 cm layer and in the second group (along with asparagine and glycine) in the 10–20 cm layer. In all virgin and arable catenas, an increase in metabolic diversity was noted from the watershed to the accumulative part of the catena. At the same time, plowing led to its decrease in the 0–10 cm layer: up to 1.5 times in chernozems and up to 4 times in gray soils. In the 10–20 cm layer, similar trend was observed, except for the agro-gray soil in the transit part of the catena, where the number of significant responses increased 3.6 times in comparison with the virgin variant.
There are only few studies in the world on ecotoxicity of urban dust as its ability to cause adverse effects to living organisms. The aim of the research is to assess the ecotoxicity of dust by the reaction of higher plants using a new approach, as well as to analyze the differentiation of microbial reaction on dust from recreational, residential and transport functional areas of three Moscow districts. The proposed approach of the urban dust ecotoxicity assessment by the modeling of dust transfer on urban soils proved its consistency and resolved the main methodological difficulty of biotesting – the issue of control choosing. Applying ryegrass (Lollium perenne L.), it was found that the annual volume of dust deposition on soils in Moscow does not perform toxicity, while a three-year volume suppresses plants up to 27% relative to the control. No significant differences between the phytotoxicity of dust in different functional areas was found, and phytotoxicity did not correlate with any of the studied properties of dust (organic carbon content, pH, electrical conductivity, moisture capacity, particle size distribution). In contrast to plants, the parameters of the vital activity of microorganisms in dust revealed differences between functional areas. Basal respiration and microbial dust biomass were maximal in the recreational areas of the city (3.1–7.2 μg C–CO₂g–1 h–1 and 314–435 μg g–1 respectively), decreasing by 27–71% in residential and 76–81% in the transport ones. Significant correlations of basal respiration and microbial biomass with organic carbon content were observed.
A comprehensive assessment of the structural and functional state of microbial communities of multi-temporal buried ancient soloids (a soil-like formation similar to soil but without genetically formed horizons) in open archaeological pits of ancient human sites located in the middle reaches of the Mzymta River on the Sochi Black Sea coast in the Akhtsu Grotto and Akhshtyrskaya Cave was carried out. Changes in the functional biodiversity of ancient soloids compared to the background (alluvial soils that form in close proximity to the studied soloids and have similar mesomorphological properties) are noted: a decrease in the specific metabolic work (W) of microbial communities by 1.2 times according to the method of multisubstrate testing and an increase in the instability of paleomicrobial systems according to the index of the rank distribution of the spectra of consumption of substrates d 1, which is typical for irreversibly damaged systems. The microbial community of ancient soloids has undergone a number of changes associated with anthropogenic activity. The analysis of the main absorption spectrum of substrates (MST method) showed that the microbial community of the soloid of the Akhtsu Grotto is oriented towards more intensive consumption of alcohols and amino acids, which suggests that organic matter of animal origin entered the cultural layer of the ancient human site. In the microbiome of the soloid of the Akhshtyrskaya cave the presence of lactotococci and bifidobacteria was found, which are extremely rare in soil and develop in conditions of excess carbohydrates on rich complex media, such as fermented meat and plant residues. Also, an increase in the content of keratinolytic fungi capable of decomposing keratin of hair, wool, feathers, etc. was found in the cultural layer of the cave site. Prokaryotic taxonomy in all the studied soils, with or without anthropogenic impact, was characterized by the predominance of the members of the Thermoleophilia clade and the families Gaiellaceae and Solirubrobacterales. Considering that these species require positive temperatures to develop, it suggests that the soils were formed in a mild climate. The Akhtsu grotto paleosols are a promising source of bacteria (genera Janthinobacterium, Lysobacter, Chitinophaga) that may have biotechnological potential.
Using luminescent microscopy and real-time PCR, the microbiome of soils and supraglacial objects in the background and oil-contaminated ecosystems of the island was studied Hayes Island, part of the Franz Josef Land archipelago. Biomass of microorganisms ranged from 81 to 666 µg/g of substrate; most of it (up to 88%) is represented by fungi. Length of fungal mycelium reached more than 360 m/g of substrate. The number of prokaryotes varied from 4.0 × 107 to 3.75 × 10⁹ cells/g of substrate; the length of actinomycete hyphae reached 40 m/g of substrate. Up to 78% of the detected prokaryotic cells are represented by small nanoforms, which is typical for extreme ecosystems. Share of viable cells of microorganisms is maximum (74–86%) for surface organogenic horizons and minimum (29–54%) for mineral suprapermafrost layers. Prokaryotic complex was dominated by bacteria (from 5.14×105 to 5.05 × 10¹⁰ 16S rRNA copies/g of soil), but not by archaea, from 8.46 × 10⁵ to 2.28 × 10⁹ 16S rRNA copies/g of substrate. Amount of FJL fungal genetic material ranged from 6.47 × 10⁴ to 8.67 × 10¹⁰ ITS rRNA copies/g soil. Number of copies of the alkB gene (synthesis of alkane monooxygenase for the destruction of hydrocarbon n-alkanes) varied from 1.2 × 10¹ to 1.8 × 10⁵/g of substrate and sharply decreased from the surface horizons to the deep ones. Oil-contaminated soils and supraglacial objects contained a smaller biomass, however, a greater number of ribosomal genes of microorganisms compared to the background ecosystems. An exponential decrease in the analyzed quantitative parameters of microorganisms from surface to deep soil horizons was registered.
Humic substances effect on a number of soil properties: structure formation, formation of cation exchange capacity, increase in water retention capacity, etc. At the same time, humic substances in soils and solutions do not exist in the form of individual molecules, but in the form of molecular associations having a fractal-cluster organization (F-clusters). Therefore, F-clusters should exert their influence on the properties of soils. Since these formations are strongly interconnected, their separation is necessary to assess their influence on soil properties. This can be done by mechanical activation – increasing the reactivity (activity) of substances during their mechanical processing. The aim of the paper was to study the effect of mechanical activation on some soil properties and on the development of plants in activated soils. It is shown that the field moisture capacity of samples of zonal soil types when using mechanical activation increases to 35% of the initial value. The results are explained from the standpoint of reducing the mobility of gravitational water by F-clusters in macrocapillaries. The optical density of aqueous extracts from chernozem increased by 75%, the viscosity of soil pastes increased by 57% due to an increase in the number of F–clusters in the soil solution. Activated soils stimulated wheat seed germination by 26%. This effect may be associated with the formation of films of F-clusters on the surface of seeds, which fix soil allelotoxins that slow down the development of seeds.
The paleosol (MIS 5e), Late Moscow loess (MIS 6), and buried small erosional landforms in the Taneyev quarry of the Kursk region were studied. Determination of the age and conditions of formation of the parent rock and a texturally differentiated soil was made for the Ryshkovo paleosol of the Mikulino Interglacial (MIS 5e) in the center of the East European Plain. Macro- and micromorphological analysis of the selected profile, spore-pollen analysis were carried out, the OSL age and physico-chemical properties were determined, and a facial analysis for a catena was carried out, making it possible to detail the history of the development of small erosional landforms, soils and landscapes. It can conclude that the differentiation of the profile of the studied paleosol into Ah–E–Bt horizons is a product of the Mikulino interglacial, but the prerequisites for such differentiation – the formation of parent rock, were created by slope and permafrost processes back in the Moscow Late Glacial. The lithological matrix of the Ryshkovo paleosol did not remain unchanged due to the different history of interaction of such groups of processes as aeolian, slope (solifluction and colluvial) sedimentation, initial and interglacial soil formation.
The effect of long-term use of mineral fertilizers on changes in the content of total phosphorus, its organic, mineral and mobile compounds in soddy-podzolic heavy loamy soil (Albiс Retisol (Abruptic, Aric, Loamic)) was studied. The studies were carried out in a long-term stationary experiment established in the Perm region in 1978. Options – 0 (without fertilizers), N90, P90, K90, N90P90, N90K90, P90K90, N90P90K90, N30P30K30, N60P60K60, N120P120K120, N150P150K1 50. Ammonium nitrate or urea, double or simple superphosphate and potassium chloride were used in the experiment. It was established that long-term use of superphosphate during five rotations of a field eight-field crop rotation (P90, P90K90, N90P90, N90P90K90) led to a significant increase in the total content of phosphorus in the arable soil layer (0–20 cm), its mineral part by 1.3–1.8 times, mobile connections by 1.9–2.7 times. The use of nitrogen fertilizers (N90, N90K90, N90Р90 N90Р90K90) influenced the accumulation of organic phosphorus compounds in the soil. A significant increase in the soil content and reserves of both mineral and organic phosphorus compounds was observed only when using complete mineral fertilizer N90P90K90. Different combinations of superphosphate with nitrogen fertilizers and potassium chloride, as well as the dose of fertilizers, influenced the intensity of accumulation of mobile phosphorus compounds in the soil by rotation and changes in its amount along the profile. The application of low doses (NPK) 30–60 led to an increase in mobile phosphorus compounds mainly in the arable soil layer; when higher doses (NPK) 90–150 were used, changes were noted in the 0–80 cm layer. Long-term use of nitrogen and potassium fertilizers over time led to an increase in mobile phosphorus compounds in the arable soil layer.
Using the method of high-throughput sequencing of the 16S rRNA gene, the taxonomic composition of soil bacterial communities (Technosol and Retisol) near the salt dump of a potassium enterprise (Solikamsk, Perm region) was analyzed. Soil samples without plants and the rhizosphere of plants of the species Calamagrostis epigeios (L.) Roth) from areas located 1–1.5, 8, 780 m and 11 km from the salt dump were studied. It was found that bacteria from the phyla Pseudomonadota, Bacteroidota, Actinomycetota, Acidobacteriota, Verrucomicrobiota and Gemmatimonadota predominated in all soil samples. Halite waste had the greatest impact on the taxonomic composition of bacterial communities on the soils of areas (in the salinity zone) located in the immediate vicinity of the salt dump (1–1.5 m). In soil samples without plants collected in these areas, relative to soils samples without salinity (at a distance of 8, 780 m, 11 km from the salt dump), bacteria of the order “Candidatus Actinomarinales” predominated; the proportion in the bacterial communities of representatives of the phyla Acidobacteriota, Verrucomicrobiota, class Actinobacteria and the Chitinophagaceae family, the proportion of bacteria of the family Xanthomonadaceae increased. In rhizosphere bacterial communities of the plants growing in the salinity zone, the proportion of representatives of the phylum Acidobacteriota and the families Chitinophagaceae, Enterobacteriaceae decreased, and the proportion of the families Xanthomonadaceae and Flavobacteriaceae increased. The influence of the salt dump on the soil bacterial communities from areas located 8 m and 730 m from the salt dump was revealed, manifested in the presence of representatives of the order “Candidatus Actinomarinales” (1.4–1.6%), families Nitrosomonadaceae (3.0–6.1%), Saprospiraceae (1.0–1.9%), the genus Ilumatobacter (1.6–2.8%) and unculturable bacteria of the family Rhodanobacteraceae (1.3–1.5%).
The aim of the work is to reveal the correlations between the spectral characteristics of the open soil surface in the Pleiades image (04/25/2020) and soils in a key plot with a complex soil cover pattern in the southern part of the Volga upland (Volga-Don irrigation system, Volgograd oblast). The territory is characterized by high lithological heterogeneity: Paleogene and Neogene sands and loams are overlain by a cover of Quaternary brown loams of variable thickness from 1–2 m to complete wedging. The soil cover is represented by light chestnut solonetzic complexes complicated by a mosaic of lithological variants and erosion-accumulative combinations. Basing on digital methods of processing the spectral characteristics of the satellite image and the use of ground-based soil information, eight soil groups were separated and a map of their distribution was created for a key plot of 343 ha. Soil groups differ in general features of the soil surface due to the presence and amount of rubble and stones, the texture of the surface horizon (from sand to medium loam), the presence of brightened crusts on the surface, the presence or absence of HCl effervescence from the surface, depending on the thickness of the first lithological layer. Within individual groups, soils with different profile structures (agro chestnut, agrozems, agrosolonetzes) are combined. Soils of the same type and sometimes subtype fall into different groups according to spectral characteristics. This is due to the incomplete correspondence of the properties of the soil surface, which affect the spectral characteristics, and the internal structure of the soil profile as a whole.
The article presents data on the content of eleven polycyclic aromatic hydrocarbons (PAHs) in soils under burnt areas of various ages, single and repeated, in the taiga landscapes of the middle mountains of the Khamar-Daban ridge. Morphological features of soils inherited from the fire were identified, such as: layers of coals (pyr), ashes (Cpyr), charred forest litter (Opyr) and pyrogenic humus horizon (Apyr). The post-fire variability of the soil cover, formed due to the presence of areas inside the burnt area with six degrees of burning of forest litter material, is characterised. A decrease in the content of PAHs has been shown with an increase in the intensity of the fire, as well as in the case of repeated fire on the already burnt area. Background soils have a higher content of PAHs compared to 42-year-old burnt areas and to areas of intense burning in one-year-old burnt areas. By factor analysis, four groups of PAHs were identified, differing in origin: polyarenes of pyrogenic autochthonous origin, formed in situ – naphthalene, tetraphene, pyrene, chrysene, anthracene, naphthalene, and to a lesser extent benzo(a)pyrene, and benzo(ghi)perylene; a group of polyarenes of pyrogenic allochthonous origin that accumulate in soils due to atmospheric transport of ash – benzo(a)pyrene and benzo(ghi)perylene; a group of polyarenes of biochemical origin – fluorene and biphenyl; polyarenes of biochemical and petrogenic origin, accumulating at the depth of the soil – phenanthrene.
The ecological and toxicological assessment of the of the soil and vegetation cover at the Streletskaya Steppe site of the V.V. Alekhin Central Chernozem Reserve is presented. The contents of a number of heavy metals (HM) and radionuclides in the typical chernozem are determined. The values of concentration clarks of HM (Cc), geoaccumulation indices (Igeo) for As, Cd, Co, Cs, Cu, K, Pb, Sr, Zn, 232Th, 238U and pollution indices (PI) for individual HM in chernozem were calculated. It is shown that increased values of the pedogeochemical background in comparison with clark values in the lithosphere are observed only with respect to Cd and As. At the same time, for the studied HM (As, Cd, Cu, Pb, Zn), it can be argued that they do not pollute the soil. The content of radionuclides (40K, 137Cs, 232Th, 238U), HM and potassium in various types of natural steppe vegetation was determined. Based on the plant accumulation coefficients of HM and radionuclides, the degree of biophilicity of radionuclides and HM was estimated. The values of the aggregated transfer factors (Cag) 137Cs and 40K from soil to plants were also determined and a comparative analysis of the bioavailability of cesium and potassium during root uptake was carried out. The vertical distribution of 137Cs and 40K radionuclides in the root-inhabited soil layer of 0–20 cm was studied. It was established that 40K is evenly distributed in the root layer of the soil The features of the vertical distribution of 137Cs in the soil profile are noted, consisting in the displacement of the maximum from a depth of 0–5 to 5–10 cm. Based on the data obtained, the value of the migration coefficient 137Cs is calculated, taking into account the convective and diffusion components of the radionuclide translocation process in a typical chernozem.
Based on a significant volume of soil samples of various genesis presented on the territory of the Komi Republic, a study of their granulometric composition (GC) was carried out in accordance with the Kachinsky method (MK). Calculated, procedural, random and systematic factors influencing the precision and correctness of measurement results performed in accordance with the MK prescription are considered. The influence of sample preparation (the degree of grinding of soil samples) and procedures for measuring the mass fraction of elementary soil particles (ESP) on the quality of the results of studying soil GS was assessed. The instability of measuring the mass fraction of fine sand (0.05–0.25 mm) and coarse dust (0.01–0.05 mm) fractions when using the MK recipe was shown. The dependence of the uncertainty of measurement results, caused by random factors, on the mass fraction of ECPs included in the granulometric fractions is noted – the lower the mass fraction of ECPs in the composition of the fractions, the higher the uncertainty of the measurement results. A modification of the Kaczynski method (MMK) has been developed to improve the quality of soil HS assessment results. It includes: (1) separation of fine sand particles using a sieve with a mesh diameter of 0.05 mm (instead of calculating this fraction by difference according to the MK recipe); (2) use of scales of the first class of accuracy to measure the mass fraction of dust and sludge particles; (3) control of the HS research process based on the summation of the measured values of the mass fraction of ESP of six fractions and acid-soluble compounds (losses from HCl treatment). The standard for operational control of the mass fraction of the amount of ECP after dividing them into fractions is (100 ± 5)%. A metrological study of the Kaczynski technique and its modifications was carried out. The proposed modification of Kaczynski’s technique made it possible to reduce the uncertainty in the measurement results of the mass fraction of ECP of small fractions (ωn 10%) and shift the lower limit of measurements to 1%.
The results of rheological studies of soils on the modular rheometer MCR 302 (Anton Paar, Austria) by the amplitude sweep method (oscillatory method) are considered. Study objects are represented by semi-hydromorphic soils of taiga zone in the Northeast of European part of Russia. We found that the strongest interactions between soil particles are developed in the horizons with high content of mobile humus compounds (fulvic acids) and Al/Fe-humus complexes (ELhi,g–ELg–CRM horizons). Increased structural durability is due to the cementation of soil particles resulting from the intake of humus substances and Al/Fe-humus compounds with the development of strong interparticle bonds in the soils. Another important factor is the freezing-thawing processes. The impact of seasonal freezing on the soil rheology is clearest in the profile of semihydromorphic variants of light soils (Histic Gleyic Stagnosols), in their cryometamorphic (CRM) horizons, where increased rigidity of soil bonds is due to condensation compaction of soil particles as a result of development of freezing veil with long period of temperatures about 0С (“zero curtain”). High values of structural interrelations – Integral Z in the soil profile may be due to weak aggregation of mineral mass caused by a constant surface moisture stagnation in the soil accompanied by an intensive gley process. Disaggregated soils are most at risk of erosion and washout processes, and yet thick moss-peat horizon forming in the upper part of the profile of semihydromorphic soils protects them from negative deformation phenomena. In the northward direction from the textural-differentiated soils of southern taiga to the cryomethamorphic soils of forest-tundra we observe an increasing of the strength or rigidity of interpartical soil bonds. At the latitudinal scale, the strength or durability of soil bonds in the cryometamorphic soils of northern, far northern taiga and forest-tundra is higher than that in the semihydromorphic texture-differentiated soils of southern and middle taiga. This pattern may be due to more active intake of fulvic acids, including complex Al-FA-humic substances, as well as longer freezing of northern soils. It is shown that rheological parameters can be used as additional indicators in the diagnosis and classification of taiga soils.
The ecotoxicity of Ag particles of different sizes was assessed by microbiological, biochemical and phytotoxic indicators of the upper layer (0-20 cm) of ordinary chernozem (Haplic Chernozem) in a laboratory model experiment. We studied the effect of nano- (10 and 100 nm) and microparticles (1000 nm) of Ag at concentrations of 1, 10 and 100 mg/kg on the biological parameters of ordinary chernozem 30 days after contamination: the activity of catalase, dehydrogenases, ferrireductase, urease, peroxidase, poliphenoloxidase, invertase, phosphatase, the total number of bacteria, the abundance of bacteria of the genus Azotobacter, the number of germinated seeds and the length of radish roots. It was found that the ecotoxicity of Ag particles depends on their size: in most cases, Ag particles 10 nm in size had a stronger ecotoxic effect on biological parameters than particles 100 and 1000 nm in size. There were no significant differences in the ecotoxicity of 100 and 1000 nm Ag particles. The difference in the effects of Ag particles of different sizes increased with increasing Ag concentration in the soil: the higher the Ag concentration in the soil (from 1 to 100 mg/kg), the more pronounced the difference in ecotoxicity between 10 nm Ag particles and 100 and 1000 nm Ag particles. Phytotoxic indicators are more sensitive to contamination by Ag nanoparticles at all concentrations studied (1, 10 and 100 mg/ kg); total number of bacteria, invertase and phosphatase activity – at 10 and 100 mg/kg; the abundance of bacteria of the genus Azotobacter and the activity of dehydrogenases – at 100 mg/kg. It is advisable to use these indicators in biodiagnostics of the ecotoxicity of Ag nanoparticles.
First time comprehensive studies of soil erosion were carried out in a 42-hectare catchment area (near the Lomovets, Orel region) in the zone of Luvic Phaeozems with erosion resistance is significantly lower than that of Chernozems. Analysis of archival and historical cartographic materials showed that the duration of plowing of the catchment is 200 ± 10 years. The rates of soil erosion and accumulation over the entire plowing period, post Chernobyl period, last 50 ± 25 years and single erosion event (which occurred on May 31, 2022) were determined based on the use of field methods (soil-morphological, radiocesium, rain rills method, detailed survey using drone) and WaTEM/SEDEM erosion model calculation. The estimates of soil losses and accumulation indicate significant fluctuations in the rates of erosion-accumulative processes over the past 200 years, which are mainly due to the conditions of the formation of melt runoff, the repeatability and distribution of runoff-forming heavy rain within the warm season, the set of crops sown, the frequency and methods of tillage, changes in field boundaries. The average annual estimates of soil erosion for the agricultural period are higher than those for the post-Chernobyl period, since the rates of soil erosion have decreased in the last three decades. Estimates of soil losses using the WaTEM/SEDEM model are generally comparable with the results of determining soil losses based on the soil-morphological method, provided that the redistribution of sediment to the lower boundaries of arable land is taken into account. The spatial structure of a single erosive event turned out to be largely close to the spatial structure of the location of the areas of eroded and aggradational soils formed during the entire agricultural period.
Current medium- and small-scale estimates of soil erosion in Russia are very few. At the same time, a favorable situation has now developed for assessing the rates and volumes of soil erosion losses. Erosion models have been developed that are adapted to available digital elevation models, various farmland masks and climate databases have been created. The paper studies the accuracy of erosion estimates using various maps of arable land. Two maps are public (ESA WC, GLCLU), the third is the official Ministry of Agriculture (MA) of the Russian Federation, the fourth map is an author’s reference map of Alekseevsky district. It has been established that the map of the MA gives the most average arable land areas among the first three maps. Public access maps showed maximum and minimum estimates of arable land area. Comparison with the standard showed that the accuracy of the map of the MA does not exceed 90%, the remaining maps – 84 and 83%. The area of arable land in the Belgorod region varies slightly (from 1,445 to 1,586 thousand hectares); so the region is favorable for erosion modelling. Deviations from the average rates of soil erosion calculated using different maps of arable land in the region as a whole amounted to 7%, and in some areas reached 27%. Thus, today assessments of soil erosion at the regional level can be carried out with an error of at least 10–15% only as a result of the uncertainty in mapping the boundaries of arable land. In the Russia as a whole, data on the area of arable land varies significantly, from 80 to 132 million hectares. Consequently, the use of existing maps of arable land can lead to significant uncertainties in soil erosion estimates averaged at the level of districts and above.
The study of the structure of peat deposits of the Bolsheberezovskoye and Podkosmovo inundated mires which were formed during the Atlantic – subboreal periods of the Holocene in the valley of the Nepryadva River, in the north-eastern part of the Middle-Russian Upland. The results of the botanical composition of peat deposits showed that the genesis of mires is represented by eutrophic paleocenoses, which accumulated carbon at a rate of 21.8-95 g/m2 per year. The formed eutrophic peat was characterized by a high degree of decomposition (45-55%) and a low rate of vertical growth (on average, 0.3-0.6 mm/year), which is due to the seasonal dynamics of the level of occurrence of mire waters. The carbon content in peat by peat deposit profiles is 14% for the Podkosmovo mire and 31% for the Bolsheberezovskoye mire. The differences are due to the peculiarities of the water-mineral nutrition of the mires, which is manifested in the high content of carbonates and ash content of the Podkosmovo mire. Carbon reserves in peat soils of inundated mires vary from 51.5 up to 125 kg/m2 for horizons with a capacity of 10 cm. This indicator is determined by the intensity of decomposition of plant residues, which depends on the composition and structure of microbial complexes. On the Bolsheberezovskoye mire the microbial complex is dominated by the fungal component, on the Podkosmovo mire – by the bacterial component. This is the reason for the differences in the microbial biomass of the mires: 222 g/ m2 for the Podkosmovo, 898 g/m2 for the Bolsheberezovskoye mire. The reason for the differences in inundated mires is the range of variation in the level of mire waters during the growing season, due to the reclamation measures carried out in the Bolsheberezovskoye mire. Nevertheless, inundated mires are important “depots” of atmospheric carbon and the intensity of its accumulation is determined by a complex of factors.
Microbial biomass, diversity of cultivated bacteria and micromycetes, as well as the number of functional nitrogen cycle genes in the supraglacial systems of the Aldegonde and Bertel glaciers were studied. Biomass of microorganisms varied from 2.54 to 722 µg/g of substrate. It has been shown for the first time that the majority (78.7–99.8%) of the microbial biomass of supraglacial objects is represented by fungi rather than prokaryotes. Main part (from 70 to 90%) of the fungal biomass was mycelium, the length of which varied from 6.70 to 537.51 m/g of substrate. The number of prokaryotes varied from 2.4 × 108 to 1.95 × 109 cells/g of substrate. The length of actinomycete mycelium varied from 2.6 to 62.61 m/g of substrate. The abundance of cultivated bacteria and actinomycetes varied from 3.3 × 104 to 1.2 × 106 CFU/g of substrate, and that of micromycetes varied from 2.2 × 101 to 1.7 × 104 CFU/g of substrate. Bacteria of the genera Arthrobacter, Bacillus, Rhodococcus, and Streptomyces, as well as micromycetes of the genera Antarctomyces, Cadophora, Hyphozyma, Teberdinia and Thelebolus dominated. Micromycetes Antarctomyces psychrotrophicus, Hyphozyma variabilis and Teberdinia hygrophila were found in Svalbard for the first time. The number of amoA genes in ammonium-oxidizing bacteria varied from 5.33×106 to 4.86 × 109; nitrogen fixation genes nifH, from 9.89 × 107 to 9.81 × 1010; nirK denitrification genes, from 4.82 × 107 to 3.34 × 1010 gene copies/g of substrate. The results obtained indirectly indicate the leading role of fungi in the microbiome of the supraglacial objects of Svalbard and the significant contribution of prokaryotes to the emission of greenhouse gases from them.
