No 5 (2023)

The history of microbiological research in various geological sciences is analyzed in brief. Development of the doctrine about underground microorganisms and its use in various engineering geological schools is shown on the basis of experimental studies, including modern metagenomic analysis. The primary sources of the microorganisms’ penetration into the underground space of St. Petersburg have been identified and systematized according to different principles. The analysis of engineering geological processes as a result of microorganisms and products of their vital activity provides the main aspects that control safety of subsurface exploration and use for various purposes, including the design, construction and operation of underground structures (subway tunnels) at different depths, as well as running deep foundation pits for ground structures. The results of experimental studies of the subsurface microorganisms’ activity make it possible to infer that it is necessary to extend engineering geological, hydrogeological and engineering ecological research of the urban underground space in order to assess the hazard of the underground microorganisms’ activity and to mitigate emergency cases for engineering structures.

The article presents the results of a comprehensive study of the conditions for the development and spread of natural and technogenic suffusion by the Belarus territory. It is noted that in insignificantly disturbed natural geoenvironment, the most favorable conditions for the development of suffusion have developed within the moraine and water-glacial plains and lowlands of the eastern part of the country, as well as marginal ice ridges and uplands with a cover of loess and loess-like formations with increased silt content, relatively low density of the soil skeleton, easy soakability and thixotropy, which contribute to the intensive development of the suffusion process. Active natural factors, conditions for the development and spread of suffusion, as well as forms of its manifestation in loess and loess-like soil massifs are considered. Suffusion manifestation in technogenically disturbed geoenvironment is analyzed, and its negative impact on functioning of natural-anthropogenic systems of various organization levels is shown by specific examples. In the authors’ opinion, the creation of a monitoring system for the development of suffusion, as well as other exogenous geological and engineering geological processes, will provide up-to-date information on the distribution and manifestation activity of these processes and the factors that determine them.

The comprehensive assessment of possible degradation of soils under the influence of long-term cyclic load caused by the movement of ice fields included several stages. First, the procedure of calculating the expected parameters of the amplitude-frequency spectrum of impacts and the corresponding shear forces was performed. In the course of experiments using the calculated parameters and loads, the so-called Wohler curves characterizing the change in the strength of dispersed soils under cyclic influences were obtained. The following factors control the decrease in strength: the cyclic nature of loading, its amplitude and duration; whereas, its mechanism consists in the possible redistribution of stress between the mineral skeleton and the pore water. The final analysis of soil behavior was completed taking into account the cyclic ice load in winter period of the accepted duration. The results of soil-stability assessment in the ground base at the site in the northern part of the Caspian Sea shelf are presented.

The article provides an assessment of the current state of groundwater and shows the dynamics of its transformation based on the analysis of geoenvironment monitoring results for 2008–2022. The geological environment monitoring program included hydrodynamic and hydrogeochemical observations on the Chita thermal power plant № 1 ash dump territory placed in the west of the city. Regime observations were carried out over the aquifer of the Lower Cretaceous sediments of the Doronin formation using hydrogeology boreholes. The hydrodynamic data correlation analysis indicates the relationship of groundwater levels in boreholes located at a considerable distance from the ash dump with the water level in the nearest borehole. The expansion of technogenic object influence zone in the southwest direction is confirmed by this circumstance, together with the appearance of an ascending spring and the previous studies results of the filtration properties of soils which lie at the ash dump bowl base. As revealed earlier, the ash dump appeared to be the source of significant contamination of groundwater in this area. Nowadays, the polluted area is estimated approximately at 12 km². The concentrations of sulfates, boron, total dissolved solids, as well as total hardness exceed the norms for drinking water within the area of about 12 km² in the boreholes on the filtration flow route in the southeast direction from the ash dump. The chemical composition of water taken from boreholes in the southwest direction is currently close to the background values of the water quality indices for the Chita-Ingoda intermountain artesian basin. Meanwhile, the composition of the spring located 1 km southwest from the third ash dump bowl indicates worsening of groundwater quality. As proceeds from the study performed, the operation of the third ash dump bowl will create conditions for the spread of the groundwater contamination front in a new direction with flooding of previously unaffected areas.

Incineration is a common method for treating municipal solid waste, which reduces its mass by 70% and volume by up to 90%. However, most of the non-combustible components are subsequently concentrated in a relatively small amount of incineration residues – bottom ash and fly ash – which must be further processed and / or landfilled. The article describes the formation and composition of incineration residues, issues of recycling and environmental regulation, leaching of pollutants and the problems of its testing, methods of treating incineration residues to reduce environmental impact.

The article discusses modern approaches to planning urban areas in the context of implementing the Federal Project “Formation of a comfortable urban environment”. It is proposed to create a “geoenvironmental profile of the city” for the system integration of heterogeneous information about the city and geoenvironmental processes, which often limit the development of urban space. The formation of such a profile will allow integrating geoenvironmental data into strategic documents of territorial development and planning urban areas. This will contribute to effective planning to achieve sustainable and safe urban development.