Articles

Complexes of cultured saprotrophic bacteria and yeasts from different components of soil constructions (humus soil horizon and peat) were studied simultaneously with the assessment of auxin-producing activity (synthesis of 3-indolylacetic acid, IAA), of some bacteria and yeast strains isolated. The study was conducted at the stage of laying two variants of constructions in Syktyvkar, formed from components of local origin (variant 1) and imported (humus soil horizon, Moscow, peat "Seliger-agro", Tver region) (variant 2).

The taxonomic structure of microbial complexes isolated from the studied substrates had significant features of similarity. At the same time, components of variant 1 revealed a greater diversity of cultivated saprotrophic bacteria (Bacillus species) species resistant to adverse environmental conditions as well as the presence of psychrophilic basidiomycete yeast Leucosporidium scottii, which was not found in the components of variant 2.

The average IAA production by the yeast strains studied was 647.6 µg/L and by saprotrophic bacteria - 741.3 µg/L. The highest values of IAA concentration were found in the culture liquid of the yeast Tausonia pullulans (strain Y-6) - 3362.6 µg/l, isolated from the humus soil layer of variant 1, and of the two saprotrophic bacteria Flavobacterium рsychrophilum (strain B-7 - 2616.8 µg/L and B-5 - 1056.3 µg/L), isolated from the humus soil horizon in variant 1 and from peat of variant 2. For strains of the yeast Leucosporidium scottii and the cultured saprotrophic bacteria Flavobacterium psychrophilum the ability to synthesize IAA was found for the first time. 

We used sequential static chemical extraction methods for studying soil pollution with heavy metals. This allowed determining the amount of metals extracted with this reagent. The new equipment for dynamic extraction of HM and obtaining extractograms, opens up additional possibilities: to determine the number of particles’ groups that differ in resistance to this reagent and to determine the statistical indicators of each group of particles. The technique for decrypting extractograms is based on their deconvolution into a series of asymmetric Gaussians corresponding to a separate group of particles – carriers of HM. The statistical indicators of Gaussians include the relative stability of each group of particles to this reagent, their dispersion D, asymmetry As, and excess Ex. Statistical indicators of Ca-Mg particles of HM carriers in urban soils show a high heterogeneity in the resistance of particles to acetic acid compared to particles in non-urban soils. The probable reason for the difference between urban and non-urban soils is a different composition of Ca-Mg minerals: , most Ca-Mg minerals in non-urban soils are carbonates. Urban, initially carbon-free soils are contaminated with Ca-Mg-containing construction waste: cement, lime and asbestos, and also contain secondary carbonates formed from Ca-Mg-waste. Urban acetic soluble pollutants belong to the following groups of minerals: technogenic hydroxides, silicates and aluminates of calcium and magnesium, which greatly distinguishes their chemical properties from the properties of carbonates. The abundance of pollutant forms as carriers of HM determines the diversity and heterogeneity of groups of particles soluble by acetic acid in urban soils.

The article discusses the existing methodological approaches used in Russian and foreign studies of urban soils. The analysis of methods for studying the soil cover as an object of landscape design, considering its formation and functioning on the example of the Moscow city. Information is provided on the territorial and functional organization of urban space. From the point of view of methodological approaches for the study of urban soils, it is proposed to divide them into two groups: uneven-aged soils with bulk surface horizons from various recultivants, formed according to design documents, and natural and surface-transformed soils without filling layer. The features of methodological approaches for studying each soil group are considered. It is noted that the material composition of the ground materials from which urban soils are formed has a significant impact on their structure, properties and functioning. The use of ground materials of different composition and properties for the formation of the upper part of urban soils, sometimes an unknown history of their functioning and land use, and possible numerous violations cause extremely high and most often unsystematic spatial and temporal variability of urban soils. With the increasing interest of the scientific community in the qualitative assessment of the urban environment, the most promising is the development of methods for studying the resulting ecological functions of urban soils using integral indicators, as well as the development of approaches, methods and technologies for creating urban soils that meet the criteria of green environmental management.

Key words: soils of Moscow city, zoning of urban areas, soil science methods, urban ecology, ecological functions of soils, ground materials.

The estimation of the radial migration of petroleum hydrocarbons (TPH) in soil profile and their inflow into lysimetric leachates was done to establish acceptable TPH limits in main soil types of Sakhalin Island. The maximum concentrations of TPH, especially medium and high-boiling fractions of TPH, were accumulated in peat and humus horizons, as well as in soil horizons, characterized by heavy loam or clay granulometric composition, which could be considered as radial geochemical barriers to the migration of pollutants. Benzene and its homologues were detected in filtrates from soil monoliths, after passing a water volume corresponding to three-quarters of the annual precipitation, yet these compounds were not revealed after passing the annual precipitation rate through the soil. The toxicity of the leachates was assessed in bioassay with ceriodaphnia and ciliates. The criteria for establishing the acceptable TPH norms in soils according water migration index can be: concentration of TPH, the content of monoaromatic compounds in leachates and their toxicity for hydrobionts in lysimetric experiments.

The migration of the water-soluble fraction of petroleum hydrocarbons in typical soils of Bashkortostan is studied. In a lysimetric model experiment, the possibility of water migration of petroleum hydrocarbons in Fluvic Phaeozems, Haplic Phaeozems and Amphiskeletic Pantocalcic Chernozems was revealed. Among the dissolved organic substances that pass into lysimetric waters from oil-contaminated soils, the components that are not extracted by hexane, but have fluorescence in water at the wavelengths typical for petroleum products are revealed. These substances differ from soluble organic matter of background soils by higher HIX humification indices and presumably represent oxidized products of transformation of petroleum hydrocarbons. Lysimetric waters from all oil-contaminated soils are characterized by biotoxicity, regardless of the presence of non-polar petroleum hydrocarbons. The toxicity T-index positively correlates with the content of dissolved organic carbon and chloride ions that accompany soils oil pollution.

Surface waterlogged soils, drained by ceramic and plastic drainage, are an analogue of large-area lysimetric installations, the drainage runoff in which is represented by gravitational waters like lysimetric waters. The drainage runoff module in the spring and autumn periods at landfills drained with plastic and ceramic drainage, and its dependence on the humidity of the year have been established. It is shown that drainage transforms the type of water regime from stagnant-washing to washing. The long-term and spatial dynamics of the removal of the silty fraction of soils and iron compounds has been studied. The removal of chemical elements with drainage runoff and its influence on the intensity of the loessivage process in agro-gray drained soils have been established.

The main components of the CO2 balance - emission from the surface, removal with lysimetric runoff, and dynamics of reserves in a 1.5 m soil layer, taking into account interphase equilibria, were quantitatively assessed in a 2-year soil-lysimetric experiment. A significant (up to 20-90%) contribution of lysimetric runoff to the total gas exchange in cold weather (autumn-winter) against the background of a small (0.3-3.7%) share during the growing season (spring-summer) is shown. Due to the unsteadiness and inertia of gas accumulation / unloading processes inside the soil, emission from the surface does not adequately reflect the gross CO2 production by the soil volume, underestimating in the spring-summer period and overestimating in autumn. The obtained 2-year correlation between emission and gross-production indicates the possibility of a 1.3-1.4-fold underestimation of the dissimilation component of the carbon cycle in the traditional emission assessment of soil respiration.

The theoretical equation of the concentration of trace element compounds entering the soil with atmospheric precipitation as a function of depth and time is tested on the example of data on the long-term dynamics (1965, 1995, 2006, and 2013) of Cu, Ni and Mn compounds in the soil profile under artificial phytocenoses of the MSU soil lysimeters. The obtained results indicate the possibility of using an analytical model for predicting the content of heavy metals in the soil profile.