Hydrothermal Conditions Research Articles

Peculiarities of water exchange of Quercus robur and Acer campestre in an oak-field maple forest

We studied the physiological and biochemical parameters of water exchange of two broadleaf forest species, Quercus robur L. and Acer campestre L., which grow under different levels of water supply. The study was conducted in the lower third of the northern slope and the middle third of the southern exposure slope in the “Viyskovyi” ravine. It was established that the content of total water in the leaves of Q. robur is higher than that of A. campestre under both mesophilic and xerophilic conditions. In A. campestre, the gradual dehydration of leaves during the growing season is more pronounced. The water-holding capacity of the leaves increases in both species, especially in July and August on the southern exposure slope, which is consistent with changes in the content of hydrophilic colloids. This can be considered as an adaptation of plants against rigorous hydrothermal conditions. The leaves of A. campestre retain water better and are characterized by a greater number of hydrophilic colloids compared to the leaves of Q. robur at different levels of water supply. Under xerophilic growth conditions, the suction power of the cellular junctions of leaves is more significant than under mesophilic conditions. At both experimental sites, this indicator is always higher in case of A. campestre, while the difference is greater only under xerophilic conditions. The increase in suction force in leaf cells occurs in parallel with the increase in soil dryness. The leaves of A. campestre have a greater water deficit and suction power, better water-holding capacity due to a greater content of hydrophilic colloids, and a lower intensity of transpiration. The leaves of Q. robur have a lower water deficit and a lower water-holding capacity, which is based on the ability to resist the lack of moisture by the development of a deep root system that allows water to be absorbed from its deep horizons. The obtained data make it possible to clarify the peculiarities of the water regime of tree species during their simultaneous growth in forest phytocoenoses and adaptation to different levels of soil moisture.

Impact of extreme pre-monsoon drought on xylogenesis and intra-annual radial increments of two tree species in a tropical montane evergreen broad-leaved forest, southwest China.

Tropical montane evergreen broad-leaved forests cover the majority of forest areas and have high carbon storage in Xishuangbanna, southwest China. However, stem radial growth dynamics and their correlations with climate factors have never been analyzed in this forest type. By combining bi-weekly microcoring and high-resolution dendrometer measurements, we monitored xylogenesis and stem radius variations of the deciduous species Betula alnoides Buch.-Ham. ex D. Don and the evergreen species Schima wallichii (DC.) Korth. We analyzed the relationships between weekly climate variables prior to sampling and the enlarging zone width or wall-thickening zone width, as well as weekly radial increments and climate factors during two consecutive years (2020 to 2021) showing contrasting hydrothermal conditions in the pre-monsoon season. In the year 2020, which was characterized by a warmer and drier pre-monsoon season, the onset of xylogenesis and radial increments of B. alnoides and S. wallichii were delayed by three months and one month, respectively, compared with the year 2021. In 2020, xylem formation and radial increments were significantly reduced for B. alnoides, but not for S. wallichii. The thickness of enlarging zone and wall-thickening zone in S. wallichii were positively correlated with relative humidity, and minimum and mean air temperature, but were negatively correlated with vapor pressure deficit during 2020 to 2021. The radial increments of both species showed significant positive correlations with precipitation and relative humidity, and negative correlations with vapor pressure deficit and maximum air temperature during two years. Our findings reveal that drier pre-monsoon conditions strongly delay growth initiation and reduce stem radial growth, providing deep insights to understand tree growth and carbon sequestration potential in tropical forests under a predicted increase in frequent drought events.

Forecasting Future Vegetation Dynamics under SSP/RCP Pathways under Spatially Changing Climate and Human Activities Conditions

Vegetation dynamics result from the interaction between human activities and climate change. Numerous studies have investigated the contributions of human activities and climate change to vegetation cover dynamics using statistical methods. However, these studies have not focused much on the spatially non-stationary effects of human activities on vegetation cover changes and future trends. Taking the Three Gorges Reservoir (TGR) area as the case study area, it was divided into 32 combinations by considering the spatially varying effects of five factors related to human activity and climate change, including gross domestic product (GDP), population, land use change, precipitation, and temperature. Regression in terms of pixels was then performed for each combination at the pixel scale. The result showed that from 2001 to 2020, the annual average normalized digital vegetation index (NDVI) in the TGR area exhibited an upward trend (slope = 0.0051, p < 0.01), with the mean NDVI increasing from 0.53 to 0.64. Compared with the regression with climate variables, the proposed model improved the R2 value from 0.2567 to 0.6484, with the p-value in the t-test reduced from 0.2579 to 0.0056. It indicated that changes in vegetation were dominated by human activities and climate change in 48.77% and 3.19% of the TGR area, respectively, and 43.70% of the vegetation coverage was dominated by both human activities and climate change. This study also predicted the future NDVI according to the shared socioeconomic pathways (SSPs) and representative concentration pathway (RCP) scenarios provided by the Intergovernmental Panel on Climate Change. It suggests that, assuming future regional policies are the same as the historical policies in the TGR, the SSP5–8.5 scenario would have the highest and fastest growth in average NDVI, with the average NDVI increasing from 0.68 to 0.89, because of the large increase in the GDP, lower population in this scenario, and adequate hydrothermal conditions.

CO2 Fixation to Prebiotic Intermediates over Heterogeneous Catalysts.

ConspectusThe study of the origin of life requires a multifaceted approach to understanding where and how life arose on Earth. One of the most compelling hypotheses is the chemosynthetic origin of life at hydrothermal vents, as this condition has been considered viable for early forms of life. The continuous production of H2 and heat by serpentinization generates reductive conditions at hydrothermal vents, in which CO2 can be used to build large biomolecules. Although this involves surface catalysis and an autocatalytic process, in which solid minerals act as catalysts in the conversion of CO2 to metabolically important organic molecules, the systematic investigation of heterogeneous catalysis to comprehend prebiotic chemistry at hydrothermal vents has not been undertaken.In this Account, we discuss geochemical CO2 fixation to metabolic intermediates by synthetic minerals at hydrothermal vents from the perspective of heterogeneous catalysis. Ni and Fe are the most abundant transition metals at hydrothermal vents and occur in the active site of the enzymes carbon monoxide dehydrogenases/acetyl coenzyme A synthases (CODH/ACS). Synthetic free-standing NiFe alloy nanoparticles can convert CO2 to acetyl coenzyme A pathway intermediates such as formate, acetate, and pyruvate. The same alloy can further convert pyruvate to citramalate, which is essential in the biological citramalate pathway. Thermal treatment of Ni3Fe nanoparticles under NH3, which can occur in hydrothermal vents, results in Ni3FeN/Ni3Fe heterostructures. This catalyst has been demonstrated to produce prebiotic formamide and acetamide from CO2 and H2O using Ni3FeN/Ni3Fe as both substrate and catalyst. In the process of serpentinization, Co can be reduced in the vicinity of olivine, a Mg-Fe silicate mineral. This produces CoFe and CoFe2 with serpentine in nature, representing SiO2-supported CoFe alloys. In mimicking these natural minerals, synthetic SiO2-supported CoFe alloys demonstrate the same liquid products as NiFe alloys, namely, formate, acetate, and pyruvate under mild hydrothermal vent conditions. In contrast to the NiFe system, hydrocarbons up to C6 were detected in the gas phase, which is also present in hydrothermal vents. The addition of alkali and alkaline-earth metals to the catalysts results in enhanced formate concentration, playing a promotional role in CO2 reduction. Finally, Co was loaded onto ordered mesoporous SiO2 after modification with cations to simulate the minerals found in hydrothermal vents. These catalysts were then investigated under diminished H2O concentration, revealing the conversion of CO2 to CO, CH4, methanol, and acetate. Notably, the selectivity to metabolically relevant methanol was enhanced in the presence of cations that could generate and stabilize the methoxy intermediate. Calculation using the machine learning approach revealed the possibility of predicting the selectivity of CO2 fixation when modifying mesoporous SiO2 supports with heterocations. Our research demonstrates that minerals at hydrothermal vents can convert CO2 into metabolites under a variety of prebiotic conditions, potentially paving the way for modern biological CO2 fixation processes.

High-efficiency phosphorus recovery from hypophosphite and phosphite-containing wastewater via a new electrodialysis enrichment and hydrothermal oxidation coupling process

Hypophosphite is an ideal reducing agent used in industries such as electroplating. However, the presence of high concentrations of hypophosphite and phosphite in industrial wastewater necessitates the consumption of large amounts of strong oxidants to oxidize hypophosphite to phosphate for subsequent removal by precipitation. This study introduces an innovative application of green hydrothermal process for the oxidation treatment of inorganic materials, combined with the ion enrichment advantages of electrodialysis. This novel coupling process achieves efficient enrichment and rapid oxidation of high-concentration hypophosphite and phosphite with minimal chemical consumption and more economical operating costs, yielding high-quality phosphate resources. Under electrodialysis conditions with a particle electrode dosage of 3 %, a voltage of 20 V, and a residence time of 10 h, the total phosphorus in the middle chamber was reduced from 2801.17 mg/L to 119.05 mg/L, achieving an anodic enrichment rate of 95.75 %. Under hydrothermal conditions of 400 °C for 15 min, with an H2O2 doping ratio of 7 % and a Ca(OH)2 doping ratio of 35 g/L, the peak oxidation rates of H2PO2− and HPO32− reached 99.38 %, and 99.39 % of phosphorus was transferred from the liquid phase to the solid phase in recyclable forms such as Ca5(PO4)3OH, Ca3(PO4)2, and FePO4. H2O2 enhances the hydrothermal oxidation process by increasing the concentration of free radicals. Ca(OH)2 acted as a catalyst to enhance •OH generation during the hydrothermal reaction, provided Ca2+ required for phosphorus recycling, and increased the pH to obtain crystalline products with a high Ca/P molar ratio. Compared to conventional advanced oxidation processes, the electrodialysis and hydrothermal coupling process offers a clean alternative for treating high-concentration hypophosphite and phosphite in plating wastewaters, achieving a cost saving of 22.99 %.

Uranium partitioning between apatite and hydrothermal fluids at 150–250 °C

This experimental study is focused on the immobilization of dissolved uranium (U) via its entrapment by apatite at hydrothermal conditions. Experiments on apatite crystallization were conducted in 0.5 M sodium chloride (NaCl) solutions at temperatures of 150, 200, and 250 °C. Uranium was introduced into the system as a solid compound (UO3), which controlled the concentration of dissolved U in the hydrothermal fluids. The results showed that U contents in apatite exceed U concentrations in co-existing fluid by 2–3 orders of magnitude. Apparent Nernst partition coefficients (DU) and exchange coefficient (KU/Ca) were evaluated. Experimentally determined DU values were consistent with DU predicted by the Lattice Strain Model at 200 and 250 °C. The obtained KU/Ca values shows dependence on temperature. The results lay the foundation for further assessment of uranium immobilization in apatite and other minerals at repository conditions.

Kinetic Study and Catalytic Activity of Cr3+ Catalyst Supported on Calcium Silicate Hydrates for VOC Oxidation.

Volatile organic compounds (VOCs) are pollutants that pose significant health and environmental risks, necessitating effective mitigation strategies. Catalytic oxidation emerges as a viable method for converting VOCs into non-toxic end products. This study focuses on synthesizing a catalyst based on calcium silicate hydrates with chromium ions in the CaO-SiO2-Cr(NO3)3-H2O system under hydrothermal conditions and evaluating its thermal stability and catalytic performance. A catalyst with varying concentrations of chromium ions (10, 25, 50, 100 mg/g Cr3+) was synthesized in unstirred suspensions under saturated steam pressure at a temperature of 220 °C. Isothermal curing durations were 8 h, 16 h, and 48 h. Results of X-ray diffraction and atomic absorption spectroscopy showed that hydrothermal synthesis is effective for incorporating up to 100 mg/g Cr3+ into calcium silicate hydrates. The catalyst with Cr3+ ions (50 mg/g) remained stable up to 550 °C, beyond which chromatite was formed. Catalytic oxidation experiments with propanol and propyl acetate revealed that the Cr3+ catalyst supported on calcium silicate hydrates enhances oxygen exchange during the heterogeneous oxidation process. Kinetic calculations indicated that the synthesized catalyst is active, with an activation energy lower than 65 kJ/mol. This study highlights the potential of Cr3+-intercalated calcium silicate hydrates as efficient catalysts for VOC oxidation.

Kinetics study on the temperature-dependent reduction of aqueous U(VI) by natural pyrite

Previous studies have indicated that acid-washed pyrite is inert toward aqueous U(VI) under most pH conditions at ambient temperature, even though insoluble UO2 is the thermodynamically predicted product for the reduction of U(VI) by pyrite. Considering the exothermic nature of nuclear waste, the interaction between uranyl nitrate/acetate and natural pyrite was studied at temperatures ranging from 25 °C to 85 °C and at pH values between ∼4.0 and ∼9.5, to simulate the scenarios encountered in a high-level radioactive waste repository. The results revealed that the reactivity of pyrite toward aqueous U(VI) significantly increased with rising temperature, and the reaction could be described by a pseudo-first-order kinetic equation. Activation energies were calculated to be 79.4 ± 10.6 and 45.7 ± 3.8 kJ⋅mol−1 for the reduction of uranyl nitrate, and 78.2 ± 5.2 and 42.2 ± 5.8 kJ⋅mol−1 for the reduction of uranyl acetate, at pH values of ∼4.5 and ∼5.0, respectively. These values indicate that the reaction is controlled by the surface chemical processes. In addition, the complete reduction of aqueous U(VI) to UO2 product was first observed for the reactions at pH ∼4.0 to ∼5.5 when the temperature was ≥75 °C. Conversely, non-stoichiometric UO2+x(s) (0 < x ≤ 0.67) was found at lower temperatures within the same pH range, and also at 85 °C with a reaction pH of ∼9.5. Moreover, the ratio of reduced U(IV/V) on pyrite surfaces increased gradually over time, indicating that reaction time played a significant role in the reduction products. The findings are essential not only for the safety assessment of the high-level radioactive waste repository, but also for understanding the metallogenic mechanism of U(IV)-bearing ore deposits under the relevant anaerobic and hydrothermal conditions.

Chemical stitching of a reduced and fluorine decorated graphene oxide quilt

This work demonstrated the possibility of obtaining continuous thin transparent films of reduced graphene oxide of large size. The process of chemical interaction of individual graphene oxide microsheets is implemented in a planar version on a silicon substrate with an oxide layer during preheating and subsequent reduction under hydrothermal conditions. Based on the results of thermal analysis, in situ X-ray diffraction, and results of XPS, a model of the chemical interaction of functional groups of graphene oxide during its primary thermal and subsequent hydrothermal treatment is proposed. The thin films obtained in this work were transferred to a measuring structure and their conductive properties were measured in planar and vertical geometries.

ТРАНСФОРМАЦИЯ ПЛОДОРОДИЯ ПОЧВ ЗАЛЕЖЕЙ ЛЕСОСТЕПНОЙ ЗОНЫ ПРИ РАЗЛИЧНОМ НАПРАВЛЕНИИ ИХ ИСПОЛЬЗОВАНИЯ

The purpose of research is to provide a comprehensive comparative assessment of the fertility of gray fallow soils in the forest-steppe zone of the Krasnoyarsk Region, overgrown with forest, used for hayma-king and re-developed into arable land. The studies were conducted in 2007–2020 in the Krasnoyarsk and Achinsk-Bogotol forest-steppe on gray soils of fallow lands no longer used for agricultural purposes. Stu-dies were carried out to assess the indicators of the potential and effective fertility of gray soils of fallow lands of the Krasnoyarsk and Achinsk-Bogotol forest-steppe with their various post-agrogenic use. It has been established that forests regenerated on fallow lands do not lead to degradation of soil fertility, especially in terms of the content of humus and agronomically valuable aggregates. The emerging forest litter and tree litter accelerate the accumulation of organic matter, a source of humus. There is weak spatial va¬riation in most indicators of effective and potential fertility in soils under regenerating forest compared to pure fallow lands. With the re-involvement of fallow land into arable land, nitrification somewhat increases, spatial variation in soil properties decreases, and the content of humus and absorbed bases decreases. The structural composition of the soils of all study objects is characterized as excellent (ACF 88–77 %) with an insignificant value of the coefficient of variation of fractions (4–7 %). When reclaiming fallow lands into arable land, the proportion of the blocky fraction is significantly reduced. The spatial variability of the structural composition of soils in fallow lands and hayfields is higher than on arable land, which is asso¬ciated with the “clumpiness” of the ground cover and root system of plants on uncultivated soils. In terms of fertility, post-agrogenic gray soils used for haymaking occupy an intermediate position between clean fallow lands and those overgrown with forest. The productivity of the phytomass of fallow lands, arable land and hayfields in the Krasnoyarsk and Achinsk-Bogotol forest-steppe is more closely correlated with the indicators of the potential fertility of post-agrogenic gray soils. In most cases, the values of the correlation coefficients are closer between phytomass reserves and indicators of effective fertility in the Achinsk-Bogotol forest-steppe, which is associated with more favorable hydrothermal conditions in this research area and optimal water-physical properties.

Influence of biochemical composition of above-ground biomass of oilseed radish on the expediency of its green manure application

Over a ten-year period, the volumes of formed ground biomass of oil radish and its biochemical composition were estimated for spring and summer plantings in terms of its green manure application. The formed leaf and stem mass of the oil radish variety Zhuravka was studied using official AOAC international analysis methods, liquid chromatography, methods of field evaluation of yield and weight and equivalent indicators. The effectiveness of green manure application was assessed by the method of multicriteria-decision support. Oil radish was confirmed to have a high adaptive potential at the maximum level of determination of bioproductivity, with an optimal moisture and temperature supply of up to 40%. The long-term average productive and biochemical portfolio of oil radish was identified as follows: 21.19 t/ha of leaf-stem ground mass with 62.3% soil cover 70 days after sowing, 2.8% nitrogen, 22.8% fibre, 0.6% phosphorus, 3.8% potassium, 16.6 μmol/g glucosinolates at the C/N ratio of 14.7, 83% plant-mass quality, and 48.1 mol/ha biofumigation potential based on glucosinolate aucumulation. The study confirmed the high potential of oilseed-radish adaptability to the regimes of unstable moisture of territories, finding interannual variation of the total bioproductivity and biochemical parameters of leaf-mass quality with the value of the variation coefficient ranging 23.6–31.2%, depending on the sowing date. The effectiveness of oilseed radish was also revealed by comparison with the similar interannual variation of hydrothermal conditions of vegetation (the amount of precipitation 48.2%, average daily temperature 27.5%, moisture coefficient 68.1%, and aridity index 58.9%). Oilseed radish was found to be agrobiologically and agrotechnologically feasibile to be used in the system of both spring and summer (intermediate) green manure technologies in grey loess soils under conditions of unstable moisture, as indicated by its bioproductivity and biochemical quality of leaf mass, as well as the results of the components of the multicriteria assessment of the plant as green manure, the value of normalised weight coefficients ranging 0.62–0.99

Profound loss of microbial necromass carbon in permafrost thaw-subsidence in the central Tibetan Plateau

Climate warming is causing rapid permafrost degradation, including thaw-induced subsidence, potentially resulting in heightened carbon release. Nevertheless, our understanding of the levels and variations of carbon components in permafrost, particularly during the degradation process, remains limited. The uncertainties arising from this process lead to inaccurate assessments of the climate effects during permafrost degradation. With vast expanses of permafrost in the Tibetan Plateau, there is limited research available on SOC components, particularly in the central Tibetan Plateau. Given remarkable variations in hydrothermal conditions across different areas of the Tibetan Plateau, the existing limited studies make it challenging to assess the overall SOC components in the permafrost across the Tibetan Plateau and simulate their future changes. In this study, we examined the properties of soil organic carbon (SOC) and microbial necromass carbon (MicrobialNC) in a representative permafrost thaw-subsidence area at the southern edge of continuous permafrost in the central Tibetan Plateau. The results indicate that prior to the thaw-subsidence, the permafrost had a SOC content of 72.68 ± 18.53 mg g−1, with MicrobialNC accounting for 49.6%. The thaw-subsidence of permafrost led to a 56.4% reduction in SOC, with MicrobialNC accounting for 70.0% of the lost SOC. MicrobialNC constitutes the primary component of permafrost SOC, and it is the main component that is lost during thaw-subsidence formation. Changes in MicrobialNC are primarily correlated with factors pH, plant input, and microbial properties. The present study holds crucial implications for both the ecological and biogeochemical processes associated with carbon release from permafrost, and it furnishes essential data necessary for modeling the global response of permafrost to climate warming. Based on this study and previous research, permafrost thawing in the Tibetan Plateau causes substantial loss of SOC. However, there's remarkable heterogeneity in SOC component changes across different regions, warranting further in-depth investigation.

The influence of hydrothermal conditions on the strawberries flower buds formation in the Middle Urals

The influence of hydrothermal conditions on the strawberries flower buds formation in the Middle Urals

CORN FOR GRAIN IN CONTINUOUS GROWING UNDER DIFFERENT FERTILIZER SYSTEMS AND WEATHER CONDITIONS

On the experimental field of the Poltava State Agricultural Experimental Station named after M. I. Vavilov of the The Institute of Pig Breeding and Agro-Industrial Production of the National Academy of Agrarian Sciences of Ukraine, during 1984-2023, on typical chernozem in conditions of unstable moisture of the Left-Bank Forest-Steppe, were conducted researches to study the continuous growing of corn for grain and its productivity. Precipitation is the leading factor in providing corn with available moisture in this region. Different hydrothermal conditions, especially the amount of moisture during the agricultural year and the vegetation, led to sharp fluctuations in grain yield over the years, which occurred in a wide range. The analysis of the average values ​​of corn productivity for each 10 consecutive years of conducting these studies made it possible to establish that during the first decade of observations, the dynamics of this indicator in subsequent periods took place in the paradigm of its growth, albeit at a different level. Maize grain yield and its correlation with different weather conditions and fertilization systems, regardless of the replacement of maize hybrids, ranged from direct to inverse and from low to high. Long-term application of different doses and ratios of organic and mineral fertilizers contributed to changes in both quantitative and qualitative indicators of humus in the soil. It was determined that the content of total carbon in the fertilized areas was higher by 3,0 and 3,3 relative percent compared to the unfertilized ones. Special attention was paid to the ratio between humic and fulvic acids, which directly depends on the fertilization system. The different effect of this agrotechnical measure on the amount of humus accumulation in the soil is shown. Thus, in areas without fertilizers (control), its accumulation occurs at the level of an average indicator and a weak effect of organic acids on the mineral part of the soil, while under the organo-mineral fertilization system, this process takes place intensively, and the mineral part remains almost unchanged.

FEATURES OF FORMING WATER AVAILABILITY FOR WINTER WHEAT IN THE SOUTH OF UKRAINE

The article examines the importance of considering several factors affecting the soil water regime in the context of developing models for forecasting productive soil moisture reserves. It was established that the main factors, such as the type of soil, its density, and mechanical composition, remain constant in different soil and climatic regions of Ukraine. The second group of factors, such as air temperature, precipitation, and soil moisture, are subject to changes throughout the growing season and even over short periods. Therefore, the dynamics of soil moisture as a function of the main variables, such as average air temperature and precipitation, was considered using calculations. Initial moisture reserves are used in the calculations for more accurate forecasting of moisture reserves at the end of a specified period. Hydrothermal conditions considered as predictors in the regression equation are also used. The reliability of the conducted research is confirmed by the analysis of independent input and output information from the Kherson weather station in the period from 2018 to 2021 regarding the actual reserves of productive moisture in the soil at a depth of 0 - 20,0 - 50 and 0 - 100 cm. The average error between actual and calculated data did not exceed +13,5%. It confirms the reliability and precision of the conducted research making it the basis for further analyses and conclusions. The conclusions noted the need for accurately determining soil moisture to effectively manage agrometeorological conditions and optimize crop yield. The authors believe that the research work presented in this article can significantly contribute to developing modern approaches to water availability in agriculture and agrometeorology. That will contribute to the gradual and improved development of soil moisture forecasting methodology, which is key to ensuring sustainable and productive development in agriculture.

ACCUMULATION OF SYMBIOTIC NITROGEN BY PERENNIAL LEGUMINOUS CROPS IN THE SOUTHERN STEPPE OF UKRAINE

The use of perennial leguminous crops is an energetically and economically beneficial and ecologically safe measure for improving the nitrogen balance of soils, which implementation requires specification and additional research of certain soil and climatic conditions and farming systems. The work aimed at studying the accumulation of biologically bound nitrogen by alfalfa and Hungarian sainfoin in single-species crops, as well as in wheatgrass-alfalfa and wheatgrass-sainfoin grass mixtures on the dark-chestnut soil of southern Ukraine. Laboratory, field, and statistical research methods were applied. The obtained results showed that the accumulation of nitrogen in the biomass of leguminous perennial grasses in single-species crops of blue hybrid alfalfa, Hungarian sainfoin, and intermediate wheatgrass and their grass mixtures depended on the hydrothermal conditions of the growing season, changes in species botanical composition by the years of grass stand used. During the first and second years of use, the nitrogen content in the biomass of alfalfa was 3,54-3,75%, sainfoin – 3,49-3,65%, and was significantly higher than in single-species crops of intermediate wheatgrass – 2,62-2,77% to dry matter. The removal of total nitrogen by intermediate wheatgrass during this period did not exceed 90 kg/ha; by alfalfa and sainfoin, it was 125-134 kg/ha, including symbiotic nitrogen removed by the alfalfa crop – 35-39 kg/ha and Hungarian sainfoin – 37-44 kg /ha. In the fractional composition of nitrogen in the soil of the experimental field after three years of using alfalfa when inoculating seeds with the complex microbial preparation Ecovital, the nitrogen content was the highest compared to other types of crop rotation, including total nitrogen – 1006,3-1428,8, mineral nitrogen – 24,9-46,3; alkaline hydrolyzed nitrogen – 113,8-186,0 mg/kg of soil. The obtained results allow us to conclude that the creation of highly productive symbiotic systems when using the latest biological preparations will contribute to improving soil nitrogen balance, eliminate the catastrophic decrease in fertility and soil degradation, improve the fodder base for animal production, and reduce the ecological burden on agricultural lands.

Synthesis of customized zeolite X with outstanding CO2 selectivity over CH4 and N2 using facile activated spent fluid catalytic cracking catalysts

Efficient separation of CO2 from natural gas mixtures (CO2/CH4) and flue gas (CO2/N2) is pivotal for effective carbon capture and sequestration. Utilizing adsorbents derived from solid waste provides additional benefit for the carbon capture industry. This study introduces a convenient activation method at 200 °C for SFCC. Utilizing the activated SFCC as raw material under mild hydrothermal conditions, highly crystalline zeolite X (referred to as SFCC-X-200) of commercial quality with exceptional CO2 separation ability from CH4 and N2 is obtained. The static water adsorption rate of SFCC-X-200 meets the requirements of the national standard for commercial zeolite X (GB6287-86). Moreover, the ideal adsorbed solution theory (IAST) selectivity of SFCC-X-200 for CO2 from CO2/N2 (15/85, v/v) and CO2/CH4 (50/50, v/v) mixtures is significantly higher, at 797 and 199, respectively, compared to commercial X zeolite. SFCC-X-200 demonstrates tremendous potential for separating CO2/N2 and CO2/CH4 mixtures due to its outstanding adsorption capacity and selectivity, rapid attainment of adsorption equilibrium, complete desorption at ambient temperature, and extremely low cost.

Experimental Study on the Preparation of High-Purity Iron Oxide Red by Acid Leaching Iron from Coal Gangue.

Aiming at the problems of the large storage, complex composition, low comprehensive utilization rate, and high environmental impact of coal gangue, this paper carried out experimental research on the preparation of iron oxide red from high-iron gangue by calcination activation, acid leaching, extraction, and the hydrothermal synthesis of coal gangue. The experimental results show that when the calcination temperature of coal gangue is 500 °C, the calcination time is 1.5 h, the optimal concentration of iron removal is 6 mol/L, the acid leaching temperature is 80 °C, the acid leaching time is 1 h, and the liquid--solid mass ratio is 4:1; the iron dissolution rate can reach 87.64%. A solvent extraction method (TBP-SK-hydrochloric acid system) was used to extract the leachate, and a solution with iron content up to 99.21% was obtained. By controlling the optimum hydrothermal conditions (pH = 9, temperature 170 °C, reaction time 5 h), high-purity iron oxide red product can be prepared; the yield is 80.07%. The red iron oxide was characterized by XRD, SEM-EDS, particle-size analysis, and ICP-OES. The results show that the red iron oxide peak has a cubic microstructure, an average particle size of 167.16 μm, and a purity of 99.16%. The quality of the prepared iron oxide red product meets the requirement of 98.5% of the "YHT4 Iron oxide Standard for ferrite". It can be used as a raw material to produce high-performance soft magnetic ferrite. In summary, this experimental study on the preparation of iron oxide red from coal gangue is of great significance for the comprehensive utilization of coal gangue to realize the sustainable development of the environment and economy.

Illitization of montmorillonite in ammonium solutions under hydrothermal conditions

In diagenetic solutions, ammonium may be incorporated into smectites as an exchangeable cation and become fixed within the interlayer space of illites and other white micas. To study the potential impact of NH4+ on the smectite-to-illite transformation reaction, a series of hydrothermal experiments were carried out at 100, 150 and 200 °C, spanning reaction duration from 15 to 90 days, and two NH4+ concentrations (0.1 and 0.2 M). The solids resulting from these alteration experiments were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and transmission and analytical electron microscopy (TEM and AEM). The XRD analysis revealed that, under the specified experimental conditions, smectite incorporates NH4+ in the structure, leading to the formation of non-swelling layers, resulting in partial transformation to illite layers and producing packets of disordered illite/smectite (I/S). In addition, a minor XRD peak at ∼10 Å suggests the formation of discrete illite crystals. The FTIR spectra demonstrated the uptake of NH4+, with deformation bands observed at 1400 and 1430 cm−1, corresponding to exchangeable NH4+ in smectite and fixed NH4+ in high-charge layers, respectively. TEM analysis revealed that smectite particles exhibited wavy stacks comprising a few layers with abundant defects and lateral discontinuities. The interlayer spacing in these particles ranged from 12 to 15 Å and became thinner and more plate-like with increasing temperature and time. Moreover, they contained inclusions of 10–10.3 Å layers, either as discrete layers or in packets of several layers, indicating the formation of disordered mixed-layer illite-smectite. Lateral transitions from 12 to 15 Å to 10 Å layers were frequently observed and interpreted as reaction fronts due to local rearrangement. At 150 and 200 °C, isolated packets of 10 Å layers were identified as discrete illite crystals that precipitated directly from solution. Analysis of the chemical composition of individual particles revealed an increase in octahedral charge (MgVI for AlVI substitution) in smectite particles, followed by increase in tetrahedral charge in I/S particles. Interlayer NH4+ played a stabilizing role in the high-charge layers and favored the smectite-to-illite conversion process.

Frictional Properties of Feldspar‐Chlorite Gouges and Implications for Fault Reactivation in Hydrothermal Systems

AbstractAs a particularly common mineral in granites, the presence of feldspar and feldspar‐chlorite gouges at hydrothermal conditions has important implications in fault strength and reactivation. We present laboratory observations of frictional strength and stability of feldspar (K‐feldspar and albite) and feldspar‐chlorite gouges under conditions representative of deep geothermal reservoirs to evaluate the impact on fault stability. Velocity‐stepping experiments are performed at a confining stress of 95 MPa, pore pressures of 35–90 MPa, and temperatures of 120–400°C representative of in situ conditions for such reservoirs. Our experiment results indicate that the feldspar gouge exhibits strong friction (μ ∼ 0.71) at all experimental temperatures (∼120–400°C) but when T &gt; 120°C, the frictional response transitions from velocity‐strengthening to slightly velocity‐weakening. At constant confining pressure and temperature, increasing the pore pressure increases the friction coefficient (∼0.70–0.85) and the gouge remains slightly velocity weakening. The presence of alteration‐sourced chlorite leads to a transition from velocity weakening to velocity strengthening in the mixed gouge at experimental temperatures and pore pressures. As a ubiquitous mineral in reservoir rocks, feldspar is shown to potentially contribute to unstable sliding over ranges in temperature and pressure typical in deep hydrothermal reservoirs. These findings emphasize that feldspar minerals may increase the potential for injection‐induced seismicity on pre‐existing faults if devoid of chloritization.