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A comprehensive quantitative and qualitative characterization of prokaryotic communities of solid atmospheric fallout (dust aerosol) and soils in the areas with different anthropogenic loads within the territory of Moscow was obtained. The total number of bacteria in the studied samples of solid atmospheric fallouts (SAF) was lower than the number of bacteria in soil samples; actinomycete mycelium was not found in dust samples, although it was found in soil samples. The number of culturable saprotrophic bacteria in dust samples was an order of magnitude lower than in Urbic Technosols taken at the same plots. Representatives of the genus Micrococcus dominated the culturable bacteria in the dust aerosols, while representatives of the phylum Proteobacteria dominated in soils. Representatives of the Enterobacteriaceae family were found in the dust samples, among which there were species that are potential human pathogens. The maximum biodiversity of bacteria of the Enterobacteriaceae family was recorded in the dust samples taken in areas with increased anthropogenic and transport load. The sanitary-indicative bacterium Escherichia coli was found in all samples of the dust and Urbic Technosols; its content varied from 10 to 100 CFU/g, which corresponds to the moderate degree of epidemic danger. Ecological indices calculated for prokaryotic communities in situ (barcoding of the 16S rRNA gene) indicate a lower taxonomic diversity of SAF prokaryotic communities in comparison with communities of closely spaced Urbic Technosols.

Crop exposure to stress during cultivation is known to reduce the yield and to cause the release of allelotoxins from plants into soil. It was assumed that allelotoxin release may considerably affect the vegetable growth in greenhouses and that a decrease in the allelotoxin concentration in greenhouse substrates may improve the plant growth. To verify the assumptions, allelotoxicity and microbial contents were determined in greenhouse substrates in which cucumber, tomato, and pepper plants grew well or poorly. The allelotoxin content was found to be higher and the prokaryote content, lower in the substrates of poorly growing plants. The finding confirmed the assumption that allelotoxins significantly influence the cultivation of vegetables in greenhouses. Treating the plant root zone with humate solutions having a high allelotoxin absorption capacity appreciably improved the cucumber plant growth and was assumed to provide a promising means to increase the vegetable yields in greenhouses.

Ferrihydrite—an ephemeral mineral—is the most active Fe-hydroxide in soils. According to modern data, the ferrihydrite structure contains tetrahedral lattice in addition to the main octahedral lattice, with 10–20% of Fe being concentrated in the former. The presence of Fe tetrahedrons influences the surface properties of this mineral. The chemical composition of ferrihydrite samples depends largely on the size of lattice domains ranging from 2 to 6 nm. Chemically pure ferrihydrite rarely occurs in the soil; it usually contains oxyanion (SiO1 4 4- , PO 4 3- ) and cation (Al 3+ ) admixtures. Aluminum replace Fe 3+ in the structure with a decrease in the mineral particle size. Oxyanions slow down polymerization of Fe 3+ aquahydroxomonomers due to the films at the surface of mineral nanoparticles. Si- and Al-ferrihydrites are more resistant to the reductive dissolution than the chemically pure ferrihydrite. In addition, natural ferrihydrite contains organic substance that decreases the grain size of the mineral. External organic ligands favor ferrihydrite dissolution. In the European part of Russia, ferrihydrite is more widespread in the forest soils than in the steppe soils. Poorly crystallized nanoparticles of ferrihydrite adsorb different cations (Zn, Cu) and anions (phosphate, uranyl, arsenate) to immobilize them in soils; therefore, ferrihydrite nanoparticles play a significant role in the biogeochemical cycle of iron and other elements.

Ephemeral green rust is formed seasonally in some hydromorphic soils. It consists of Fe(II)/Fe(III) layered double hydroxides with different types of interlayer anions and different oxidation degrees of iron (x). In synthetized stoichiometric green rust, x = 0.25–0.33; in soil fougerite, it may reach 0.50–0.66. The mineral stability is provided by the partial substitution of Mg²⁺for Fe²⁺. The ephemeral properties of the green rust are manifested in the high sensitivity to the varying redox regime in hydromorphic soils. Green rust disappears during oxidation stages, which complicates its diagnostics in soils. For green rust formation, excessively moist mineral soil needs organic matter as a source of energy for the vital activity of iron-reducing bacteria. In a gleyed Cambisol France, where fougerite is formed in the winter, the index of hydrogen partial pressure rH₂is 7.0–8.2, which corresponds to highly reducing conditions; upon the development of oxidation, fougerite is transformed into lepidocrocite. In the mineral siderite horizon of peatbogs in Belarus, where green rust is formed in the summer, rH₂is 11–14, which corresponds to the lower boundary of reducing conditions (rH₂= 10–18); magnetite is formed in these soils in the winter season upon dehydration of the soil mass.

In Russia, iron is chemically fractionated according to a parallel scheme. Pyrophosphate-soluble iron (Feₚyᵣ) is considered to participate in organomineral complexes, oxalate-soluble iron (Feₒₓ) is believed to enter amorphous + poorly crystallized compounds, and dithionite-soluble iron (Fedᵢₜ) is meant to represent the free (nonsilicate) compounds. However, the investigations prove that the commonly used subtraction operations (Feₒₓ − Feₚyᵣ) and (Fedᵢₜ − Feₒₓ) are invalid because of the nonadditive action of the reagents in the parallel scheme of extraction. The low selectivity of reagents requires a new interpretation of chemically extracted iron compounds. In automorphic soils, the content of oxalate-soluble iron should be interpreted as the amount of Fe(III) capable of complexing with organic ligands; in hydromorphic soils with a stagnant moisture regime, it should be interpreted as the amount of iron (III) capable of being reduced in a short time. The content of dithionite-soluble compounds should be regarded as the amount of iron (III) within both (hydr)oxides and silicates potentially prone to reduction.

The structural organization of the organic matrix of humic substances in soils has been analyzed, and the conclusion has been drawn that the existence of humic matrix is determined by contacts between the hydrophilic sites of humic particles in dry soils and between their hydrophobic sites in wet soils. It follows from the advanced supposition that the wetting–drying process should cause a structural transition (reorganization of the humic matrix), which should affect the properties of soils. To verify this supposition, the effect of soil moisture on the electrical resistivity of soil–water extracts, suspensions, and pastes has been studied. It follows from the studies performed that soil electrolytes are fixed in dry soils during drying and are gradually released into solution. However, beginning from a specific soil water content, the release of electrolytes occurs almost immediately after their contact with water. The obtained data suggest that an energy barrier should be overcome for the release of electrolytes from the soils with water content below the specific limit. There is no energy barrier for the soils with water content higher than this limit. The existence of structural transition in the humic matrix of soil gels well explains these results. The effect of energetic impacts on the structural transition has been studied. It has been shown that the study of structural transition should avoid operations that increase the number and amplitude of energy fluctuations in the systems.

The history of soil-geographical zoning in Russia and the role of G.V. Dobrovol’skii in the development of this direction of soil science are elucidated. It is shown that the principles and methods of soilgeographical zoning have been refined since the 1960s. A new map of soil-ecological zoning of the Russian Federation on a scale of 1: 2.5 M is presented, and the principles and methods of its compilation are discussed. The information content of this map, its taxonomic units, legend, and specific features of the design are described. The lithogeomorphic specificity of the separated soil okrugs and the climatic parameters of the air and soil regimes for the plain and mountainous provinces are briefly characterized. This map has contributed to the theory of soil-geographical zoning. It has a great practical meaning as the basis for the organization of rational land use with due account for the zonal and regional diversity of soil cover in Russia. It can also be used for the development of target-specific kinds of zoning. The role of this map in the cartographic block of the soil-geographical database of Russia is specified.

Soils are self-purified from oil slowly, in the north, in particular, where hydromorphic conditions and low temperatures hinder the process. Oxidation of oil hydrocarbons depends on the type of electron acceptors and decreases in the following sequence: denitrification > Mn⁴⁺ reduction > Fe³⁺ reduction > sulfate reduction > methanogenesis. Usually, not all of these redox reactions develop in contaminated excessively moistened soils and sediments. Fe(III) reduction and methanogenesis are the most common: the latter is manifested near the contamination source, while the former develops in less contaminated areas. Fe reduction hinders the methanogenesis. In oil-contaminated areas, Fe reduction is also combined with sulfate reduction, the latter intensifying Fe reduction due to the formation of iron sulfides. Concurrently with oil degradation in excessively moistened soils and sediments, the composition of iron compounds changes due to the increasing Fe(II) share magnetite, as well as siderite and ferrocalcite (in calcareous deposits), and iron sulfides (in S-containing medium) are formed.

In the current approach to the study of humic substances (HSs), they are usually considered as complex chemical polymeric compounds with a specific combination of properties. This concept of HSs cannot explain their role in soils as a depot of nutrients for microorganisms and some experimental data. The main problem is related to the low energy efficiency of this depot of nutrients, because microorganisms have to consume energy for synthesizing enzymes that destroy HS polymers (macromolecules). At the same time, the recently proposed consideration of HSs as a system of supramolecular compounds completely eliminates this contradiction. In this work, an attempt has been made to consider HSs from other positions based on their possible functional role in soils and entire ecosystems. A scheme has been proposed for the transformation of the litterfall that is based on the supramolecular nature of the HSs and confirmed by reported experimental results.

Soils and waters are affected by oil spills in the course of oil production and hydrocarbon leakages because of the corrosion of underground reservoirs, as well as the filtration of hydrocarbons from the tailing ponds formed during the extraction of oil from oil sands. The conventional technology for the withdrawal of contaminated water and its purification on the surface is low-efficient and expensive. New approaches are proposed for the in situ purification of soils and groundwater. To accelerate the oxidation, active substances atypical for the supergenesis zone are used: peroxides of metals and hydrogen. The efficiency of hydrogen peroxide significantly increases when the oxidation is catalyzed by Fe 2+ or Fe 3+ (Fenton reaction). The effects of Fe(III), sulfates, and carbon dioxide as electron acceptors are studied under anaerobic conditions (with oxygen deficit).