Articles

The composition of water extracts of soils developing within the het erolithic geochemical landscape of the Klyazma river basin in its upper reaches has been studied. The main factor that determines the content of water-soluble components is the genesis of soils and the position of the soil in a series of elementary landscapes. The specifics of the content of water soluble macro- and microelements in the soil profile outside the zone of anthropogenic influence and developing according to the eluvial- illuvial type is due to their natural organization, with the combination of podzolization in combination with texture organization. Under the con ditions of a supersquale landscape that has emerged from the flood regime, characterized by the complexity of the soil cover, the distribution of water soluble components in the soil profile is determined by the carbonate content and proximity to the surface of soil ground water. An additional factor determining the composition of soil water on the lowered elements of the relief is the underlying soil with peat bogs. It is shown that calcium is among the most important elements that determine the specificity of the studied heterolithic landscape. The composition of water-soluble components for each of the soils is specific, which is confirmed on the basis of the results of cluster analysis.

This article provides an analysis of structural and functional indicators of bacterial complexes taken for examination from the complete profile of the fens that form part of “Klukvennoye” and “Karbyshevskoye” wetland systems in the Tomsk Region. In the fens bacteria was found throughout all the profile. The number of bacteria was high and varied from 27 to 78 ´ 10⁹ cells/g of dry peat. This data was obtained by direct method using fluorescence microscopy. The high count of the saprotrophic bacteria (reaching up to 10⁸-10⁹ CFU/g of dry peat) was found by the plate method. Those results allowed to identify a trend, showing that the number of saprotrophic bacteria increased down the fen profile.  The results of this study give an opportunity to state for the first time that the index k ( k is a dimensionless universal characteristic of natural prokaryotic communities, k stands for microscopy/plate) in fen profiles does not increase, but decreases with depth. The following bacterial cultures were identified and isolated from the fens studied (those cultures were attributed to 10 taxa): Bacillus, Streptomyces, Arthrobacter, Microbacterium, Pseudomonas, Pedobacter, Flavobacterium, Dyadobacter, Janthinobacterium, Myxobacteriales. Bacterial cultures, representing Bacillus and Streptomyces genera, were dominant in the acrotelm. At the same time Pseudo-monas, Dyadobacter and Arthrobacter dominated in the catotelm. The functions of bacterial genera and species, identified by molecular biological methods, were described. A study of nitogen fixation, nitrogen decline and methanogenesis showed that bacteria were in a viable state and were able to remain active throughout the entire peat profile.

The features of the modern radioecological situation in forest (pine, spruce, birch) and fallow ecosystems in the contaminated (southern part) and background (northern part) territories of the Kaluga region are analyzed in this article. The density of soil contamination of the studied region by natural radionuclides (²²⁶Ra, ²³²Th, ⁴⁰K) corresponds to background levels, while technogenic radionuclide (¹³⁷Cs) significantly exceeds the background value (3 kBq/m²) and ranges from 60,8 to 273,8 kBq/m². Forest ecosystems (especially coniferous) are the most contaminated by ¹³⁷Cs, and fallow ones are the least contaminated. The density of ¹³⁷Cs soil contamination has decreased on average by more than 3 times compared to the initial period after fallouts (1986), but still significantly exceeds the permissible level (37 kBq/m²). The main contribution to the total specific activity of soils, as well as the power of the equivalent absorbed dose, is made by ¹³⁷Cs in the ecosystems of the contaminated areas, and by ⁴⁰K - in the ecosystems of background areas.

Soil is the basis of food systems at all levels. Preservation of the ecological functions of the soil cover, its condition in the territories newly introduced or withdrawn from agricultural use determines the degree and time of the onset of environmental risks, as well as risks and threats to food security.

The global value and cost of soil resources is increasing. Russia has a maximum soil cover of approximately 14,5 million km2—one sixth of the planetary. Soils, which are a unique national wealth and strategic resource, are underestimated. The volumes of applied agrochemicals are insufficient for the reproduction of fertility.

The achievement of food security indicators in the country and the export of food pro ducts occur due to non-reimbursable expenses of soil fertility reserves. There are no state documents that would clearly and unequivocally determine how many arable soils and agricultural land are needed to conduct modern agricultural production and fulfill tasks for sustain able development goals.

The composition of bottom sediment in the estuarine part of the Simmi River, a small tributary of the Amur River (Bolon State Nature Reserve, Russian Far East), was studied using X-ray fluorescence, electron microscopy, sedimentation analysis, and laser diffractometry. It is established that the formation of labile components in the bottom sediments (vivianite–clay microaggregates, gypsum microcrystals, and vaterite mesocrystals) is linked with effects of the pyrogenous factor in the Simmi River basin and the level regime of the main river. The formations are mobile due to their small size (<100 μm). The bottom deposits are primarily formed by such suspended sediments (particle size <100 μm), which is consistent with the lacustrine–alluvial genesis of the area. Two vivianite formation mechanisms have been identified in the bottom sediments in periods following fires, when the concentration of phosphate ions in the river water is elevated. Vivianite is formed on the surface of ferruginous–clay microaggregates, due to the reduction of Fe (III) in the presence of organic matter and on biological templates (organic residues and single-celled microorganisms).

In soils developing within a monolithic soilgeochemical catena, the composition of water-soluble macro-, microelements and anions has been studied. It has been shown that, as hydromorphism increases from eluvial to accumulative landscapes, the carbon and nitrogen contents naturally increase. The nature of the distribution of water-soluble forms of macro$ and microelements is due to bioaccumulative processes and features of eluvial-illuvial differentiation of soils. In the marginal parts of the watershed depression, the combination of eluvial$illuvial differentiation of the soil and intensive lateral removal in the spring determines the maximum leaching of the upper soil horizons. The use of cluster analysis confirms in the system of geochemical catena the relationship of genetic affiliation and soil position with the composition of water extracts.

In laboratory conditions, the decomposition of glyphosate with the formation of aminomethylphosphonic acid (AMPA) and its effect on the total abundance of bacteria and fungi, as well as the number of copies of genes encoding the enzymes C-P lyase of a-proteobacteria ( phnJ ), acid and alkaline phosphatase ( phoC and phoD ) and Fe-protein nitrogenase ( nifH ). It is shown that when applying glyphosate in recommended doses (5-10 mg/kg) 5-7% of the introduced herbicide is detected after 14 days, but when the dose is increased to 100 mg/kg, this value increases to 23%. Slowing down the rate of degradation of the herbicide appears only in the first week of incubation and is accompanied by a decrease in the number of copies of the phoC, phoD, nifH genes and an increase in the abundance of fungi. The obtained results indicate a predominant degradation of glyphosate with the C-P bond breaking and the formation of phosphates, as well as a possible inhibition of the nitrogen fixation process. It is shown that at an application dose of glyphosate 100 mg/kg, the accumulation of the first metabolite AMPA can occur during the degradation of the herbicide with a break in the C—N bond. Bioassay using wheat showed that when applying glyphosate at a dose of 100 mg/kg, there is an inhibition of plant development: the length of the roots and the biomass of the shoots reduced by 60 and 20% compared to the control, respectively. Based on the obtained data, it is proposed to use the reduction in the content of copies of the phoC gene and the growth of copies of ITS rRNA as indicators of the predominant decomposition of glyphosate through the sarcosin pathway. A reduction of copies of ITS rRNA gene by 40% or more can be used as an indicator of the possibility of AMPA accumulation during glyphosate degradation.

The laboratory study of the solid phase of salted peat by X-ray fluorescence analysis revealed the presence of some halogen-organic compounds. Cl-organic compounds were formed in one third of peat samples, while their share is small: 14-15% of the total Cl. On the contrary, Br-organic compounds are formed more often and Br_org proportion is higher: from 12 to 23% of total Br. Relatively weak development of halogenisation of the organic matter in salted peat bog is explained by the recovery conditions that prevent the synthesis of halogen-organic compounds. In X-ray diffraction analysis of peat ash, errors are possible, both due to the growth of minerals, and due to incomplete identification of the number of phases in high-ash peat samples. The second type of error can be corrected using data on the content of chlorine in peat by X-ray fluorescence analysis. In the characteristic of peat bog contamination, in addition to salt profiles in the solution, it is necessary to determine the number and composition of halogen-organic compounds, some of which have herbicide properties.

The process of natural remediation of oil-polluted and salt-polluted raised bogs of KhMAO - Yugra reclaimed 14-16 years ago is analyzed. In general, the revegetation is proceeding successfully, although mesophytic grasses sown during reclamation have almost completely fallen out of the grass stand. In salt-contaminated areas, there is a gradual desalination of peat soil, accompanied by a succession of halophytic (hemigalophytic) plant communities dominated by Calamagrostis epigeios, Eriophorum angustifolium and Phragmites australis with the participation of sphagnum and brown mosses, as well as liverworts. A characteristic feature of these habitats is the settlement of a number of rare protected species ( Heterogemma laxa, Thelypteris palustris, Triglochin maritimum ). In oil-polluted bogs, during the re-vegetation, hydrocarbons often flow from the underlying peat soil horizons to form the surface crust. At the same time, grass stands from Eriophorum angustifolium and some other species with powerful root systems are replacing grass-sedge-cotton grass communities. Sphagnum riparium and Warnstorfia fluitans play also a certain role in the overgrowth of crusted surfaces. Unsuccessful recovery is typical for hollows with difficult runoff in the case of salt-contaminated bogs and the most dry locations in the case of oil - contaminated ones.

Sewage sludge introduced 28 years ago in sod-podzolic sandy loam soils determines the increased content and mobility of Zn, Cd, Cu, and Ni compounds, and it is the most characteristic for Cd and Zn. The most polluted are the arable horizons of soils. The contaminated layer is within the arable horizon, which indicates on the low rate of heavy metals (HM) migration, which were introduced into the studied soils as part of SS. Heavy metals are washed out of soils with intrasoil runoff insignificantly. This is determined by their chemical properties: low solubility of their compounds, adsorption by mineral and organic components of soils, as well as neutral pH values of the soils themselves. Plants grown on contaminated soils are characterized by an increased content of HM, which varies in 5-7 times depending on the type of plants and their ability to accumulate HM.