No 2 (2024)

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.

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 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.

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.

The influence of sowing cereal-legume grass mixtures and application of mineral fertilizers on technozem created after the liquidation of the tailing dump of the Dzhida tungsten-molybdenum combine (Republic of Buryatia) on the change of trace element concentrations in plants and formation of turf, limiting the spread of pollutants and reducing environmental risks was assessed. The content of gross and mobile forms of some trace elements in the upper sandy loam layer of technozem was higher than in the background soil, exceeded the median background for the soils of Transbaikalia and in some cases the maximum permissible concentrations, and by the coefficient of total pollution (Z_c = 18.8) it was characterized as moderately hazardous, the lower loam – non-hazardous (Z_c = 4). It was revealed that the application of fertilizers reduced the concentration of trace elements and their accumulation coefficients in plants. According to the intensity of biological uptake, most of the elements in the aboveground phytomass belonged to the group of medium capture, in the underground – medium and intensive uptake, which indicates its phytostabilizing role. It was found that bioproductivity of grass mixtures in the control was low. Fertilizer application increased this indicator in the second year of grasses life to the average level, in the third year – to a high level, and in the fourth year turf was formed, fixing the surface layers and contributing to the increase of organic matter compared to its initial amount. Тhe research results can be used on technozems created from overburden dumps for phytostabilization and initiation of organic matter accumulation in them by sowing high-yielding perennial grasses and applying mineral fertilizers.

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.