Deeper Horizons Research Articles

Preliminary studies on radon concentration in CO2-rich mineral waters of the Elbrus area (Caucasus, Russia)

The geological and geochemical conditions as well as radon concentrations of ten manifestations of СО2-rich waters in the Elbrus area are considered in this paper. Also, content of uranium and thorium were measured in waters and in host rocks. The data were compared with chemical and isotopic composition of associated gases. It is established that water bearing rocks are classified into rocks of low and normal radioactivity. The contents of uranium (<1.37 μg/L) and thorium (<0.3 μg/L) in the water are low. Measurements of radon concentrations in water and gas flux of mineral springs in the Elbrus area indicate that most of them are weakly radioactive (6–33 Bq/L, 25-350 Bq/m3, respectively). The CO2-rich mineral waters of the Tyrnyauz exhibit the highest level of radioactivity (33 Bq/L) within the Elbrus area. Isotopical gas studies have shown that within the Elbrus region there is a connection with the deep horizons of the Earth's crust, from which various fluids (water and gases) can rise to the surface. Although Rn values are low and cannot be used for medical purposes, natural objects with similar characteristics can be used to observe the state of the geological environment (e.g. earthquakes) and as natural laboratories to establish the mechanisms of deep gas migration to the surface.

Forecast of the future prospects of drilling ultra-deep wells in difficult mining and geological conditions of Western Turkmenistan

The article defines the prospects for drilling wells in difficult and extreme mining and geological conditions of the Western part of Turkmenistan. The assessment of the current state of prospecting and exploration works in Western Turkmenistan is given. The main problems that drillers will face when drilling complex deep horizons of the red-colored stratum are considered, and general principles and recommendations for overcoming these problems are provided. The applied technical and technological innovations that meet international standards have ensured the successful completion of a number of deep and ultra-deep wells in the fields of the West Turkmen Depression, but have not completely solved the existing drilling problems. The article also provides a number of recommendations for solving these problems. This work contributes to the beginning of the development of a new geological and technological discipline - reservoir pressure management during drilling, and its introduction into practice, which will serve as technical re–equipment and organizational restructuring of deep drilling on a scientific basis. Keywords: hydraulic fracturing; collector; sedimentation; gas generation; tectonics; clay solution; reservoir pressure; section; permeability.

Prospect forecast for drilling ultra-deep wells in difficult geological conditions of western Turkmenistan

The relevance of the study is related to the growing need for efficient production of hydrocarbons in the difficult geological conditions of western Turkmenistan to ensure energy security and economic development of the region in the changing global oil and gas market. The purpose of the study is to conduct a comprehensive analysis of the geological, technical, and economic aspects of drilling ultra-deep wells in difficult geological conditions of western Turkmenistan to assess their potential feasibility and contribution to the energy infrastructure of the region. The study used analytical, functional, and statistical methods, classification, and synthesis. The prospects for drilling wells in difficult and extreme geological conditions of western Turkmenistan were identified. The analysis of the current state of prospecting and exploration in this region was carried out, while the main attention was paid to the investigation of the main difficulties faced by drillers when working with deep horizons of the reedbeds. As a result of the conducted research, general principles and recommendations aimed at overcoming these problems were developed. Despite the successful introduction of modern technical and technological innovations that meet international standards when drilling deep and ultra-deep wells in the West Turkmen depression, the study emphasized that the existing drilling problems have not yet been eliminated. This study will provide valuable recommendations and information for making informed decisions when developing and implementing projects for drilling ultra-deep wells in difficult geological conditions, contributing to effective resource management and development of the oil and gas industry in western Turkmenistan.

FLUID MIGRATION IS THE MAIN CRITERION OF THE GAS-BEARING CAPACITY OF THE CLOSED AREA OF MINES OF THE COAL-BEARING FIELDS OF THE DONBAS

Fluid migration is determined, first of all, by different in shape and rank types of dislocations that control compression and rarefaction zones as the main regulators of the distribution of matter and energy in the Earth's crust, represented mainly by Phanerozoic formations, and in our studies by carbon deposits. Gas migration through the newly formed fractures in the massif, due to the impact of mine workings on the upper layers of the lithosphere, allows for the formation of gas accumulations in the near-surface and surface areas. As a result, a significant amount of gas is concentrated in relatively small areas, which will contribute to gas-dynamic phenomena on the surface and can cause significant damage to buildings and human life. Mass transfer of deep fluids is associated with the formation of mineral deposits, including the most explored ones, ore and oil and gas. At the same time, the distribution of gas in coal-bearing massifs is related to their tectonic structure, especially to faulting, which is a way for hydrocarbon-hydrogen mixtures to migrate from deeper horizons. The study of the signs of uneven distribution of fluids under the influence of tectonic and anthropogenic factors was based on observations of new formations in the post-sedimentary geological environment: textural and structural characteristics based on the study of samples, grinds and laboratory observations, which determine the sequence of changes in the material composition of consedimentary and post-sedimentary formations and their relationship in space and time. Unsaturated hydrocarbons, such as ethylene, propylene and acetylene, can be characterised as adventitious gases of hydrocarbon massifs that have taken their current position in the gas component of the hydrocarbon gas mixture by being transported by fractures from deep horizons to the surface.

Современные подходы к реализации проектов по бурению скважин различной классификации на разных стадиях геолого-разведочных работ

The problem of obsolescence and irrelevance of the standard classification of drilling wells for the intended purpose and a new interpretation of this classification within the framework of modern reality are considered. It is noted that the search for new ways to obtain information during geological exploration leads to the understanding that drilling some types of wells is already completely impractical. In the current situation, projects should be implemented that, on the one hand, will ensure the solution of the set geological tasks, on the other hand, minimize the costs of drilling wells, reduce industrial and environmental risks, with the unconditional receipt of the entire set of required geological information. The complex of works applied in the waters of the inland seas, for the purpose of prospecting, exploration and development of oil and gas fields, can become an example of rational money savings and the efficiency of geological data collection. Currently, the share of large structural deposits of simple structure is completely insignificant, and there are practically no promising oil and gas-bearing areas on land. Current realities are such that geological exploration works penetrate deep horizons of the Earth's crust with a complex geological structure and cover oil and gas-bearing regions located in remote and remote parts of the land. The complex implemented at sea may well be applicable for such sites and will successfully compensate for anachronistic drilling methods.

The Short-Term Effect of Olive Mill Wastewater Application on Humic Acid in Subsurface Soil Layers of the Arid Region of Tunisia

ABSTRACT Few studies have assessed the changes in soil quality based on humic acids (HA) in relation to the fresh olive mill wastewater (OMW) application. Qualitative changes to soil organic matter (SOM) under the application of OMW in real conditions have been little investigated. To make a contribution in this context, an experimental field was established in an arid Tunisian area, which included a control soil, a soil treated with 10 L m˗ 2 OMW and another amended with 10 kg m˗ 2 manure. Soil samples were collected from soil depths: 0–20 cm, 20–40 cm and 40–60 cm on the first day of OMW and manure application (day 0) and after 4 months (120 days). Results revealed that soil treated with OMW had the highest SOM content (1.42 ± 0.13%), cation exchange capacity (CEC) (3.03 ± 0.51 (cmol(c) kg−1)) and soil pH value. OMW mineralization supplied soluble ions which enhanced the electrical conductivity (EC) (1.44 ± 0.34 dS m−1). Infrared (IR) spectroscopy showed higher aliphatic, aromatic and phenolic groups in OMW amended soil than the manured soil for initial and final dates. Spreading OMW on soils provides a favorable environment for improving soil humic acids (HAs), recycling organic matter (OM) and enhancing soil properties by transferring aromatic and aliphatic structures into deeper horizons, which in turn increased the sequestration of soil organic carbon (SOC).

Characterization of a biofilm-forming, amylase-producing, and heavy-metal-bioremediating strain Micrococcus sp. BirBP01 isolated from oligotrophic subsurface lateritic soil.

Lateritic soil is the reddish to brown-colored soil composed mainly of iron or aluminium oxides, hydroxides, or oxyhydroxides. Information on bacteria that inhabit this soil type, their ecological role, and metabolic potential are scarce. We have isolated and partially characterized a bacterial strain BirBP01 from a lead, calcium, and magnesium-rich, oligotrophic subsurface lateritic soil-sample collected from 12-feet deep horizon of a laterite mining pit in Birbhum district, India. The isolate is a biofilm-forming, Gram-positive bacterium having a sarcinae arrangement, mesophilic, slightly alkaliphilic, able to produce amylase, and resistant against multiple heavy-metals. BirBP01 has the ability to bioremediate 51% of Pb, 30% of Zn, and 22% of Cu through biosorption, possibly into the biofilm matrix. The bioremediating ability of the bacterium alleviated the inhibitory effect of heavy-metals on the germination of chickpea (Cicer arietinum L.) seeds. 16S rRNA gene-based phylogenetic analysis revealed that BirBP01 is a member of the genus Micrococcus. It showed more than 99% identity of the 16S rRNA gene sequence, and clustered within the same branch of the phylogenetic tree, with strains of M. yunnanensis, M. endophyticus, and M. luteus. The ability to produce amylase, and bioremediate heavy-metals signify that Micrococcus sp. BirBP01 could bepotentially a good candidate for industrial applications, and to clean up heavy-metal contaminated sites.

Gas-dynamic processes and causes of accidents at mines

Geodynamic phenomena that occur during the exploitation of a coal-bearing massif lead to human casualties, reduce the speed of penetration, and significantly complicate the operation of the mine.The article analyzes existing views on geodynamic processes occurring within mining fields located in coal-bearing formations. A safe technology for identifying potential outburst locations during coal mining is characterized. The technology has been tested during prospecting and environmental studies within the mining workings at active mines and abandoned mining fields. The results of profile and planar investigations in he areas exhibiting geodynamic outbursts in coal deposits and mines are presented.When sampling subsoil air using the technology of structural-thermo-atmospheric-hydrogeochemical research (STAHGS), which is carried out on the surface of the earth in profile and planar versions, the authors came to the conclusion about the possibility of predicting fault zones of increased permeability and zones of low fluid permeability. The first affect the rate of destruction of rocks under pressure, and in the second case, the possibility of gas emissions into the mine, which can be accompanied by an explosion and fire. Such zones are dangerous, because the most destructive events occur in places of collision. Early identification of places of geodynamic stress of rocks, fault zones of increased permeability, accumulation of gases – all this will allow to make a decision in advance about changing the conditions of conducting mining operations and degassing of the coal massif.In addition, the authors draw attention to hydrogen gas as one of the causes of initiation of explosions and fires during underground mining operations in mines, which is not taken into account at the current stage of safety control of mining operations. The possible cause of a hydrogen explosion is not taken into account in coal mine accidents. The appearance of hydrogen and helium in coal samples taken from the mine may indicate the deformation of the massif, which leads to the opening of cracks and the outflow of gas from deeper horizons. And then an increase in the concentration of hydrogen, not methane, creates the conditions for explosions and fires.

Prospects for the oil and gas potential of the zone of abnormally high reservoir pressures in the Yamalo-Nenets Autonomous Okrug assuming deep fluid dynamics

In Western Siberia, the zone of abnormally high reservoir pressures (AHRP) covers an area of more than 500 thousand km2 in the north of the basin. It begins with a clay layer above the Achimov formation of Neocomian sandy-silty formation, covers the Achimov formation, Upper–Lower Jurassic, Triassic and partially Paleozoic and is subject to tectonic control, which indicates the deep origin of this phenomenon. Gas-pressure, or gas-dynamic, theory of AHRP, proposed by K.A. Anikiev in the 70s of the 20th century, allows us to assess the prospects for oil and gas content of the AHRP zone higher than it is commonly-accepted. Analysis of the results of previously completed geological exploration work on the deep horizons of the Yamalo-Nenets Autonomous Okrug indicates that their relatively low efficiency (50–60%) is associated with the insufficiently high quality of well operations, primarily cementing, which is also due to the influence of AHRP. In all wells drilled to deep horizons, direct signs of oil and gas potential were obtained and cementing defects were identified. It is concluded that deep fluid-dynamic processes (active, pressure degassing of the Earth’s interior) are responsible both for the saturation of reservoir rocks with hydrocarbons and for the dynamics of their filling (ultra-high pressures and velocities), which determine the main characteristics of reservoir rocks. Recognition of a deep source of hydrocarbons will not only make it possible to fundamentally increase the resource base of the AHRP zone, but will also require a revision of ideas about the formation and structure of hydrocarbon deposits in this zone and the petrophysical substantiation of their models. However, to realize the unique hydrocarbon potential of the AHRP zone, it is necessary, first of all, to improve the quality of deep wells construction and appropriate information content.

Технологическая эффективность методов модифицирования свойств ферросилиция и водных систем в процессах тяжелосредной сепарации труднообогатимого алмазосодержащего материала

Introduction. Taking into account the results of experimental bench studies previously carried out at ICEMR RAS on the effectiveness of the use of physical, physico-chemical and electrochemical influences to increase the corrosion resistance of ferrosilicon in the technology of DMS of diamond-containing raw materials of weakly altered kimberlites of the primary deposits of the Mirny ore field, at this stage, their pilot industrial testing was carried out under processing conditions intensively altered ores of deep horizons with the involvement of alluvial and technogenic deposits in the processing of diamond-containing raw materials. Research methods. In accordance with the testing methodology, the tests were carried out in two directions, the ultimate task of which was to create process conditions that ensure the protection of ferrosilicon granules from corrosion destruction caused by their oxidation upon contact with corrosive aqueous systems: 1. Modification of the properties of the liquid phase of the ferrosilicon suspension to values that reduce its corrosiveness towards the surface of ferrosilicon granules (variable factor – properties of the aqueous process medium). 2. Modification of the surface properties of ferrosilicon granules by creating a protective shell on it, preventing their oxidation during contact with corrosive aqueous systems (the variable factor is the surface of the ferrosilicon used: original and coated). Research results. The article presents the results of pilot industrial tests of technical solutions, the implementation of which made it possible to reduce the consumption of ferrosilicon in the dense medium separation cycle of diamondcontaining material using the above methods for modifying the properties of the aqueous medium and ferrosilicon used for the preparation of the ferrosilicon suspension, by increasing the corrosion resistance of the components of the ferrosilicon suspension. Discussion of research results. A comparative assessment of the technological efficiency of the applied methods for modifying the properties of the aqueous phase and ferrosilicon under experimental test conditions was carried out with the determination of ferrosilicon losses in the regeneration cycle of the ferrosilicon suspension and its content in the volume of the ferrosilicon suspension. The use of electrochemically treated water as a reagent for modifying the properties of the components of a ferrosilicon suspension provides a reduction in ferrosilicon consumption by 1.9 times, but is limited by the fairly high power consumption required for processing large volumes of water in the DMS process. The use of inert nitrogen gas as a bubbling agent instead of oxygen-containing air in the ferrosilicon suspension preparation cycle reduces ferrosilicon consumption by 2.5 times while increasing its service life by 1.5 times. However, the use of this method is limited to use only in part of the DMS process – the cycle for preparing a ferrosilicon suspension. The use of the method of nitriding ferrosilicon granules ensures a reduction in ferrosilicon losses by 2.7 times while increasing its service life by 2.2 times. At the same time, the entire volume of ferrosilicon in the process retains its anticorrosion properties in relation to the corrosive components of the surrounding water system. Conclusion on the article. A comparative analysis of the results obtained using mathematical processing methods has established the maximum technological efficiency of using the method of nitriding the surface of ferrosilicon, which causes the creation of a protective nitride layer on it, ensuring high corrosion resistance of ferrosilicon granules under the conditions of active processes of dense medium separation of diamond-containing raw materials of the material composition under consideration. Nitrided ferrosilicon has parameters that make it possible to increase its service life by no less than 2.2 times while reducing losses in the regeneration cycle by 2.7 times. Suggestions for practical applications and directions for future research. The experimentally established advantages of the technological efficiency of using nitrided ferrosilicon in DMS processes of diamond-containing raw materials are recommended for industrial implementation in the conditions of ALROSA’s processing plants and can be used in similar schemes for dense medium separation of mineral raw materials of various compositions. Tests are planned under industrial conditions at one of the processing plants of PJSC ALROSA.

Results of deep horizons exploration of the Mir kimberlite pipe

The first results on the geological structure of the deep horizons of a diamond deposit – the Mir kimberlite pipe are presented. According to the results of exploration of deep horizons, new data on the geological structure of the deposit was obtained. The morphology of the pipe with depth has a definite tendency to increase the volume of the ore body in comparison with the results of previous explorations. The material composition of kimberlites and their productivity to a depth of more than 1,500 m vary slightly. In general, the results of the exploration allowed us to obtain a significant increase in the reserves of kimberlite ore and diamonds with a total volume of over 40 million carats.

Impact of agricultural management on salts accumulation in dryland soils of central Tunisia

Drylands represent about one-third of the global land and mainly occur in Africa and Asia. Because of the arid conditions, dryland soils are characterized by salt accumulation. Although salt-affected soils are unsuitable for agriculture, some arid lands have been cultivated for a long time. However, especially in the last decades, because of the increasingly warmer climatic conditions and human migration toward favorable environments, a progressive abandonment and degradation of drylands has occurred. Therefore, it is necessary to assess the effects of cultivation on saline soils to develop appropriate soil management techniques to ensure their fertility. This work aims to evaluate the evolution of salinization from currently cultivated soils to soils that have been abandoned for different lengths of time in arid areas of central Tunisia. Morphological and physicochemical properties of the studied soils indicated that the cultivation, through irrigation and the presence of soil cover, reduced salt accumulation in the upper soil horizons. Salt leaching towards deeper horizons and depressed evaporation, which reduced capillary rising, maintained electrical conductivity within tolerable values for most crops. Conversely, the abandonment of previously cultivated fields compromised soil fertility, threatening soil conservation and stabilization of agricultural production in the medium to long term.

CONTROLLING STRESS-DEFORMED TALNAKH ARRAYS BY STRESS UNLOADING

Link for citation: Golik V.I. Controlling stress-deformed Talnakh arrays by stress unloading. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 7, рр. 59-65. In Rus. Relevance. Underground mining of rock massifs of powerful deposits on deep horizons is accompanied by geomechanical phenomena, which are prevented by the construction of artificial structures made of solid mixtures in the developed space. Controlling geomechanics of the massif increases the completeness of subsoil use and is an actual direction of mining production. Objective: detailing the array state management technology by rationally regulating the voltages in the array. Object: arrays of deposits of the Talnakh ore node. Methods: modeling and experiment, the results of which are the basis for the development of a model and recommendations. Results. The paper introduces the assessment of the behavior of natural and artificial massifs differentially for the main deposits of the ore node. The regularities of combining options for unloading arrays from critical stresses are established: with overworking and with a protective layer underworking. The principles of optimization of ore mining technology taking into account the geomechanical features of the arrays are summarized. Measures to increase the volumetric compression of filling mixtures for variants of chamber systems of development are recommended. The results of modeling the influence of the volumes of rock inclusions on the efficiency of field development are presented. A model of ecological and economic assessment of technologies is proposed, taking into account the costs of creating protective layers and reducing the dilution of ores. Unloading of arrays from stresses provides an opportunity to regulate the stress level with a decrease in deformations, including during selective excavation of ores with the abandonment of rock layers in the bowels. Conclusions. Unloading arrays from operating stresses is an effective measure to solve the main problems of subsurface use at the same time. The implementation of this direction in the conditions of localization of the Talnakh ore deposits can be carried out by advanced excavation of the soil layer. The efficiency of working out stress-deformed arrays is achieved by the rational interaction of natural and technological factors of development.

Stemflow infiltration hotspots near-tree stems along a soil depth gradient in a mixed oak–beech forest

In an upland forested micro-catchment during the growing season, we tested soil responses to precipitation events as well as soil water content (SWC). We asked ourselves if what is the difference of SWC response to precipitation events depending on the presence and proximity of a tree? The environmental heterogeneity of the small 7.5-ha headwater area was captured by soil probes at specific locations: (i) probe measurements of SWC at 10-, 30-, 60-, and 100-cm depths; (ii) resolution of near-tree (NT) and between-tree (BT) positions; and (iii) resolution of four slope classes. The results revealed significant differences between the hydrological responses of the soil. NT soils had faster infiltration but were also faster to dry out when compared to BT soils, which were less affected by the presence of trees. Water input threshold values, measured as the precipitation amount needed to cause a significant increase in SWC, were also significantly different, with NT positions always lower than BT positions. Total infiltration of the topmost NT and BT soil layers reached 185 and 156 mm during the study period, corresponding to 43% and 36% of the total 434 mm of precipitation, respectively. Infiltration into the deepest horizon was significantly higher in NT soils, where it reached 114 mm (26%) as opposed to 9 mm (2%) in BT soils, and was indicative of significant vertical hydraulic bypass flow in the proximity of trees. These observations contribute to better understanding the hydrological processes, their nonlinearity, and the expansion of conceptual hydrological models.

Geochemical peculiarities of accompanying elements Filizchai pyrite-polymetallic deposit (southern slope of the Greater Caucasus)

The article considers the distribution of accompanying elements (cadmium, indium, selenium, tellurium, bismuth, etc.) in pyrite-polymetallic ores of the Filizchay deposit. It was found that there is a high correlation between the concentrations of cadmium, zinc and lead (r=+0.790 and r=+0.616). The relationship between the contents of cadmium and copper is negative (r=-0.414). Indium - correlated with zinc and cadmium. In the Filizchaya ore deposit, a relatively high amount of indium is present in the upper depth horizons and the western flank of the deposit. The mineralconcentrator of the element is zinc sulfide. A high correlation was established between antimony and arsenic (r=+0.663). There is a significant correlation coefficient of these elements with zinc, lead, silver, bismuth and cadmium. In connection with the regular arrangement of natural types of ores in the composition of a single ore deposit of the deposit, a regular change in the concentrations of these elements is established. In general, there is a vertical and horizontal zonality in the distribution of harmful impurities in the ore deposit. It has been established that the content of antimony and arsenic gradually decreases from the upper to deep horizons. The concentration of antimony and arsenic decreases from the western flank to the east, and the content of mercury from the western flank to the central part increases slightly, and on the eastern flank its concentration decreases to a minimum, selenium is more concentrated from the central part of the ore deposit of the deposit. It was revealed that the formation of the Filizchay deposit was accompanied by a zonal distribution of chemical elements, consistent with the general scheme of mineralogical zoning. Keywords: Accompanying elements; Correlation; Zonality; Distribution of chemical elements.

Analysis of sediment from an irrigation dam in an agricultural valley impacted by the mega-drought in central Chile

Central Chile has been affected since 2010 by an increasing mega-drought accompanied by a historically low precipitation rate, as a probable consequence of climate change. Additionally, the increasing pressure exerted by the withdrawals of human activities, such as agriculture and metal mining, promotes conditions of hydric scarcity. Despite this intensive use of the watersheds and the sustained and increasing aridity, it has not been explored whether an artificial sedimentary record can trace these changes in the agricultural valleys of the region. To unravel and evaluate the recent environmental/climatic variability, the effects of the mega-drought that has pertained since 2010, extractivist pressures on a Mediterranean valley in central Chile, and sediment records were obtained from an irrigation dam and studied through a multi-proxy analysis. The dam was built and has been in operation since 1975 and is located in the Aconcagua River Valley, Valparaíso, Chile. Magnetic properties, carbon content, mineral composition, and metal content were analyzed from sediments of a 120 cm long core. Changes in vegetation cover from 1990 to 2020 were analyzed through NDVI filters. Horizons associated with drier conditions were observed in the upper zone of the core, which corresponded from the year 2001 to the present, assuming a constant sedimentation rate of 2.72 cm·yr−1. Additionally, the characteristic alternation of dry–wet conditions was observed in the deep horizon of the dam sediments. The concentrations of Cu, Pb, Al, and As have increased over the years, while the concentration of Mo has decreased. Some of these elements are associated with copper mining, existing in the valley. Analysis of Landsat images from the year 2000 to the present has identified a significant decrease in vegetation cover associated with dry/wet periods, which may be related to cycles of El Niño/La Niña events. Although not all the proxies analyzed were sensitive enough to detect changes at the desired resolution, since the dam is very recent, the results shed light on the effects of the interaction between industrial activities and the decrease of water availability in multiple-use watersheds, suggesting variations in metals concentrations and changes in water availability, probably promoted by anthropic activities, climatic events, and increasing aridity in the Aconcagua River Valley.

Topsoil and subsoil bacterial community assemblies across different drainage conditions in a mountain environment

BackgroundHigh mountainous environments are of particular interest as they play an essential role for life and human societies, while being environments which are highly vulnerable to climate change and land use intensification. Despite this, our knowledge of high mountain soils in South America and their microbial community structure is strikingly scarce, which is of more concern considering the large population that depends on the ecosystem services provided by these areas. Conversely, the Central Andes, located in the Mediterranean region of Chile, has long been studied for its singular flora, whose diversity and endemism has been attributed to the particular geological history and pronounced environmental gradients in short distances. Here, we explore soil properties and microbial community structure depending on drainage class in a well-preserved Andean valley on the lower alpine vegetation belt (~2500 m a.s.l.) at 33.5˚S. This presents an opportunity to determine changes in the overall bacterial community structure across different types of soils and their distinct layers in a soil depth profile of a highly heterogeneous environment.MethodsFive sites closely located (<1.5 km) and distributed in a well preserved Andean valley on the lower alpine vegetation belt (~2500 m a.s.l.) at 33.5˚S were selected based on a pedological approach taking into account soil types, drainage classes and horizons. We analyzed 113 soil samples using high-throughput sequencing of the 16S rRNA gene to describe bacterial abundance, taxonomic composition, and co-occurrence networks.ResultsAlmost 18,427 Amplicon Sequence Variant (ASVs) affiliated to 55 phyla were detected. The bacterial community structure within the same horizons were very similar validating the pedological sampling approach. Bray-Curtis dissimilarity analysis revealed that the structure of bacterial communities in superficial horizons (topsoil) differed from those found in deep horizons (subsoil) in a site-specific manner. However, an overall closer relationship was observed between topsoil as opposed to between subsoil microbial communities. Alpha diversity of soil bacterial communities was higher in topsoil, which also showed more bacterial members interacting and with higher average connectivity compared to subsoils. Finally, abundances of specific taxa could be considered as biological markers in the transition from topsoil to subsoil horizons, like Fibrobacterota, Proteobacteria, Bacteroidota for shallower soils and Chloroflexi, Latescibacterota and Nitrospirota for deeper soils.ConclusionsThe results indicate the importance of the soil drainage conditions for the bacterial community composition, suggesting that information of both structure and their possible ecological relationships, might be useful in clarifying the location of the edge of the topsoil-subsoil transition in mountainous environments.

Potential ore possibility of rocks of the deposit Kalmakyr of Almalyk district (Middle Tien-Shan)

The article presents the mineralogical and geochemical features of the types and grades of ores of the porphyry copper deposit Kalmakyr. The chemical, mass spectrometric results of analyzes of selected samples are given. When describing polished sections, ore minerals and their structural and textural features were established. The polyformation and potential ore content of the rocks of the deep horizons of the Kalmakyr deposit was revealed. It has been determined that the change of copper mineralization with depth to copper-molybdenum is due to the change of diorite by monzonitoids. Gold and silver ores appear to be superimposed, young, and associated with basic-felsic dykes.

Impact of the change in irrigation practices from untreated to treated wastewater on the mobility of potentially toxic elements (PTEs) in soil irrigated for decades

PurposeLong-term agricultural irrigation with untreated wastewater has resulted in metals and metalloids accumulation in soil. Little information is available on the consequences of a change to irrigation with treated water on the mobility of these potentially toxic elements (PTEs).Materials and methodsThe potential mobility of PTEs was assessed using sequential extractions performed on soil irrigated with untreated wastewater for a century in Mexico. The possible effects of change in irrigation practices on PTEs mobility was evaluated through batch experiments, simulating a decrease in pH, an increase in salinity, and in chlorine of the irrigation water. Geochemical modeling allowed predicting the speciation of mobilized PTEs.Results and discussionSoils irrigated with untreated water were mainly enriched with PTEs in surface horizons. Only Cd and As were found in the soluble or exchangeable fractions (< 20%). Cu and Pb were mainly associated with soil organic matter (OM), whereas As and Zn were bound to iron oxides, and Cr with refractory minerals. Batch experiments revealed that acidification resulted in the increased solubility of Cu, Zn, and Cd for surface samples, and As in deep horizons. In contrast, increased salinity only mobilized Zn, Cd, and Cr. Water chlorination mobilized higher amount of Zn, Pb, and Cd compared to the other experiments. As was not mobilized for these two experiments.ConclusionA change in irrigation practices could increase the mobility of PTEs if water treatment is not adapted to the soil type. The mobilization of PTEs, especially As and Cd, could affect both crops and groundwater quality. It is essential to monitor this mobility to avoid future risks to human health.

Anaerobic &lt;i&gt;Thermodesulfovibrio&lt;/i&gt; and Aerobic &lt;i&gt;Meiothermus&lt;/i&gt; Coexist in Deep Thermal Water

Abstract—Research on the microorganisms inhabiting deep aquifers is based on sampling the water released from deep wells and is seldom concerned with the physicochemical processes of the water-rock system. The issue of metabolism of aerobic prokaryotes revealed in deep habitats by molecular techniques remains unclear. Cultivation is required for direct determination of relation of prokaryotes to oxygen. In the present work, aerobic and anaerobic bacteria, which were revealed in thermal radon baths of the Belokurikha resort by molecular techniques, were isolated. Profiling by the 16S rRNA gene revealed predominance of members of the Deionococcus-Thermus group belonging to the genus Meiothermus (17.6% reads) and considered strictly aerobic. Anaerobic sulfate-reducing Thermodesulfovibrio were also present in the sample. The habitat was characterized by reductive, alkaline conditions. Target-oriented cultivation revealed aerobically growing Meiothermus sp. 1165, which was closely related to Meiothermus cerbereus. An alkaliphilic anaerobic sulfate reducer Thermodesulfovibrio sp. 1176 was also isolated. The rate of sulfate reduction measured in the Belokurikha water using \({\text{Na}}_{{\text{2}}}^{{{\text{ 35}}}}{\text{S}}{{{\text{O}}}_{{\text{4}}}}\) yielded the value of 41.4 ± 1.06 µm Sred L–1 day–1, or 1.29 nmol S mL–1 day–1. Analysis of the genome of strain 1176 revealed the presence of various mechanisms responsible for its relative resistance to oxygen and oxidative stress, which included superoxide reductase, rubredoxin, a Fe-Mn family superoxide dismutase, a KatG catalase-peroxidase, and a cytochrome bd ubiquinol oxidase. The low redox potential and intense anaerobic sulfate reduction provide evidence for the generally reduced conditions in the Belokurikha deep horizons. Spatial separation of aerobes and anaerobes in the water-rock system, similar to the one occurring in the terrestrial microbial mats, may be hypothesized, as well as occurring of aerobic processes in microniches.