Search Results (557)

This study presents a hydrogeochemical assessment of oilfield formation waters from the Karazhanbas, Zhetybay, and Uzen oil fields in the Mangystau Region of Kazakhstan, with the aim of elucidating lithium distribution, identifying the geochemical factors controlling its accumulation, and providing a preliminary resource-oriented evaluation. The study investigated pH, total dissolved solids (TDS), ionic–salt composition, lithium (Li) concentration, and the relationships between Li, TDS, major cations, and geochemical ratios, including Ca/Li and Mg/Li. Major ions were determined using standard hydrochemical methods, while Li was analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES). The investigated waters were predominantly classified as chloride–calcium type according to their hydrochemical composition. In terms of TDS, the waters follow the sequence Uzen > Zhetybay > Karazhanbas, whereas Li concentrations follow the sequence Zhetybay > Uzen > Karazhanbas. The highest Li concentrations were detected in Zhetybay waters (1.40–1.85 mg/dm³); in Uzen waters, Li reached 1.51 mg/dm³; and in Karazhanbas waters, it ranged from 0.30 to 0.70 mg/dm³. The highest Mg/Li and (Na⁺ + K⁺)/Li ratios were characteristic of Uzen waters, indicating a more complex salt matrix. Compared with internationally reported lithium-enriched brines, the Mangystau formation waters contain relatively low Li concentrations and cannot currently be considered a commercially viable lithium source. The scientific significance of this study lies in establishing a regional hydrogeochemical baseline for oilfield formation waters and demonstrating that maximum mineralization does not necessarily correspond to the highest Li concentration. Full article

Maintaining effective fluid-loss control in water-based drilling fluids under coupled high-salinity, high-temperature, and high-density conditions remains a critical challenge in deep and ultra-deep drilling operations. In this study, a low-molecular-weight polymer fluid-loss additive (LM-ASQF) was synthesized via redox-initiated copolymerization of acrylamide, dimethyldiallylammonium chloride, and sodium allyl sulfonate. The synthesis route and proposed polymer structure were further illustrated to clarify the incorporation of amide, quaternary ammonium, and sulfonate functional units within the LM-ASQF molecular architecture. The polymer exhibited a controllable number-average molecular weight of 18.2–29.4 kDa with a unimodal distribution. Thermal analysis confirmed that no main-chain-dominated degradation occurred below 220 °C, indicating structural stability under high-temperature conditions. In drilling-fluid systems containing NaCl, CaCl₂, and mixed salts (0–20%), LM-ASQF maintained stable rheological properties, with apparent viscosity ranging from 26.1 to 41.6 mPa·s, while the API fluid loss was controlled within 5.8–11.2 mL. After thermal aging at 220 °C for 16 h, the API fluid loss remained below 13 mL in both freshwater and mixed-salt systems. In high-density systems (1.80–2.40 g/cm³), the drilling fluids preserved continuous rheological structures and showed no abrupt increase in filtration. Mechanistically, fluid-loss control was primarily attributed to synergistic interfacial adsorption of amide groups, hydration stabilization induced by sulfonate functionalities, and particle rearrangement-driven filter-cake densification, rather than viscosity enhancement through long-chain entanglement. This mechanism enables effective filtration control without excessive viscosity increase, thereby maintaining rheological compatibility under complex conditions. These results demonstrate that the low-molecular-weight design strategy provides a reliable approach for achieving stable fluid-loss control in water-based drilling fluids under high salinity, elevated temperature, and high-density conditions. Full article

The interaction between salt solutions and expansive soils is critical for engineering in chemically aggressive environments. However, the effect of iodide salts on pore water distribution in expansive soils remains poorly understood. This study investigated the transverse relaxation time (T₂) characteristics of pore water in expansive soils under varying KI concentrations (0–20%), moisture content (8.7–26.0%), and dry density (1.26–1.79 g/cm³) using nuclear magnetic resonance (NMR). All T₂ curves exhibited a single peak. Increasing moisture content from 8.7% to 26.0% resulted in increases of approximately 63% in T₂ at peak and 408–439% in peak area. Increasing KI concentration decreased both T₂ at peak by up to 33.3% and peak area by up to 44.0% within the tested range, attributed to diffuse double-layer compression and signal loss. Increasing moisture content broadened the T₂ distribution and linearly increased T₂ at peak and peak area, indicating water gradually occupied larger pore spaces as moisture content rose. T₂ at peak was independent of dry density, while the peak area showed a linear relationship with dry density, consistent with mass balance. The observed systematic linear relationships among T₂ at peak, peak area, and the three experimental variables suggest that NMR is a promising tool for the quantitative assessment of salt solution effects on pore water in expansive soils. These findings provide a theoretical basis for evaluating salt-affected expansive soils in coastal and arid regions. Full article

This experimental study investigates the performance and sustainability of a modified double-slope solar still (MDSSS) integrated with a combined water channel to enhance evaporation rates. The integration of the water channel ensures uniform water flow and enhanced heat distribution across the basin surface, thereby improving thermal performance. Experiments were conducted using three types of feed water, groundwater, saline water, and domestic wastewater, to assess the system’s versatility and effectiveness in various water desalination applications. Under identical meteorological conditions, thermal parameters, distillate yield, energy efficiency, and sustainability were analyzed. The results revealed that incorporating the water channel significantly increased evaporation and condensation rates compared to the conventional double-slope solar still (DSSS) configuration. Also, the performance of an MDSSS was evaluated under various water qualities, including physical, chemical, and biological parameters. The experiment begins at half the optimal water depth for water quality, with the remaining half passing through an open-channel attachment into the solar still basin. The modified system effectively reduced pollutants, achieving a 98.18% reduction in chemical oxygen demand in groundwater, complete salt removal from saline water, and a 96.67% reduction in sewage water. Full article

The increasing global demand for freshwater, together with the high energy consumption and environmental footprint of conventional desalination technologies, has stimulated growing interest in interfacial solar steam generation (ISSG). ISSG is a solar-driven water purification strategy that localizes heat at the air–water evaporation interface, thereby promoting surface evaporation without heating the entire bulk water body. The development of efficient, durable, and multifunctional ISSG systems depends strongly on substrate materials that can regulate water transport, heat localization, vapor release, and mechanical stability. This review focuses on cellulose-based substrates for ISSG and examines how their molecular structure, fibrillar assembly, and macroscopic porous architecture influence evaporation behavior and device function. The reviewed cellulose platforms are classified into three major groups: bottom–up assembled nanocellulose substrates, including cellulose nanocrystals, cellulose nanofibers, and bacterial cellulose; natural hierarchical substrates, including wood, cotton fabrics, and agricultural residues; and commercial planar substrates, including cellulose paper and membranes. Beyond evaporation performance, this review discusses multifunctional design strategies for salt regulation, antifouling and antibacterial operation, water–electricity cogeneration, and photocatalytic pollutant degradation, with emphasis on their mechanisms and functional trade-offs. Finally, we identify critical bottlenecks limiting practical deployment and propose a roadmap for future intelligent, adaptive, and multi-energy-coupled cellulose-based ISSG systems. These systems offer a promising platform for distributed and resource-efficient water treatment, but their practical and environmental benefits depend on fabrication energy, material safety, device lifetime, and end-of-life management. Full article

Wood- and lignocellulosic-residue-derived constituents have attracted increasing attention in cementitious materials because they may support clinker reduction, waste valorization, moisture regulation, crack control, and longer service life. This review synthesizes evidence on wood ash, wood-derived biochar, and wood or lignocellulosic fibers in low-clinker and low-carbon-oriented cementitious systems, with emphasis on severe cold service involving freeze–thaw cycling, salt freezing, and chloride ingress. This review clarifies the evidence boundaries among direct wood-derived materials and related biomass or lignocellulosic analogues, because wood ash, non-wood biomass ashes, such as bamboo ash and bagasse ash, wood fiber, and non-wood plant fibers cannot be treated as equivalent materials. Wood ash is best regarded as a controlled partial binder replacement or filler whose performance depends on combustion temperature, oxide composition, alkali content, residual carbon, fineness, and water demand. Biochar is more appropriately treated as a low-dosage functional additive, commonly in the range of approximately 1–3 wt.% of binder, where it may assist internal curing, nucleation, moisture redistribution, and pore regulation; excessive dosage can increase porosity and reduce mechanical or transport performance. Wood and lignocellulosic fibers mainly contribute to crack control, toughness, and post-cracking behavior, but their effectiveness is limited by water absorption, swelling, lignin- and extractive-related hydration interference, and long-term interfacial degradation in alkaline matrices. Across these material classes, engineering performance is governed by the interfacial transition zone, pore-size distribution, moisture state, air–void compatibility, and exposure-specific durability response. The main contribution of this review is to propose a boundary-conscious framework for material classification, quantitative comparison, mixture-design screening, and severe-cold durability qualification. Future application requires source-specific characterization, water-demand control, treated fibers, low-dosage biochar optimization, and service-informed testing that couples freeze–thaw cycling, chloride transport, saturation state, and microstructural verification. Full article

Soil water availability, salinity dynamics, and nitrate transport are key factors controlling agricultural sustainability in arid environments characterized by limited water resources and high evaporative demand. This study evaluated the combined effects of soil texture, nitrate–nitrogen application, and sawdust mulching on soil water retention, evaporation losses, salinity redistribution, and nitrate movement in loamy sand and sandy clay loam soils under controlled greenhouse conditions. Results showed that soil texture was the dominant control on hydrochemical behavior, with sandy clay loam exhibiting higher water retention and lower drainage than loamy sand. Sawdust mulching significantly improved soil water conservation by reducing evaporation and stabilizing moisture distribution, while the 4 cm mulch treatment achieved the highest overall CSI performance. Evaporation strongly governed salinity accumulation in surface layers, whereas mulching reduced salt build-up and promoted a more uniform salinity profile. Nitrate transport closely followed water fluxes, resulting in higher leaching in loamy sand and greater retention in sandy clay loam. Increasing nitrogen application enhanced nitrate mobility and leaching in both soils. A Composite Sustainability Index (CSI) was developed to integrate soil water conservation, evaporation reduction, salinity control, and nitrate retention into a unified metric. Sensitivity analysis demonstrated that treatment rankings were largely unaffected by alternative weighting schemes, confirming the robustness of the CSI framework. The CSI identified mulch application, particularly the 4 cm mulch treatment, as the most effective management option based on overall sustainability performance. The CSI framework provides an integrated decision-support tool for evaluating coupled water–salt–nitrate interactions and improving water use efficiency and salinity management in arid agricultural systems. This study offers a novel integrated CSI-based framework for simultaneously quantifying hydrological and hydrochemical soil responses under mulch management in arid environments. Full article

The growing share of intermittent renewable electricity has increased the need for long-duration storage in industrial energy systems. Meanwhile, many industrial processes still release recoverable low-grade waste heat. Introducing this heat into pumped thermal energy storage (PTES) can improve thermal integration, but industrial waste heat is often unsteady, and its temperature and mass flow fluctuations may disturb the charging process. This study investigates an air-based reverse Brayton PTES system assisted by an industrial hot-water waste heat stream of approximately 100 °C. A dynamic model was developed in Simulink/Simscape. The shaft speed is fixed at 3000 rpm, and a PID controller regulates the molten-salt flow rate to maintain the thermal storage temperature. The results show that increasing the waste heat temperature from 95 °C to 105 °C mainly changes the charging-side heat distribution. The waste heat utilization power increases from 36.0 MW to 37.9 MW, while the regenerator power decreases from 126.8 MW to 122.0 MW. The thermal storage power increases slightly from 117.0 MW to 119.0 MW, with the mechanical input fixed at 81.0 MW. The influence of waste heat temperature is concentrated near the low-temperature heat exchanger, regenerator, and turbine outlet. Under dynamic disturbances, faster temperature ramps increase short-term deviations, but the PID-based molten-salt flow regulation keeps the storage temperature close to 550 °C, indicating that the proposed control strategy can suppress moderate thermal disturbances during charging. When waste heat temperature and mass flow rate vary together, same-direction changes strengthen the disturbance, whereas opposite-direction changes partly offset it. These results clarify the disturbance propagation mechanism of fluctuating industrial waste heat in the PTES charging loop and provide a basis for the dynamic design and temperature-control strategy of waste-heat-assisted PTES systems. Full article

Deep-water gravity flow deposits constitute a critical frontier in global hydrocarbon exploration, and characterizing flows controlled by complex topography remains a significant challenge. Focusing on the Cretaceous Pointe Indienne Formation in the Lower Congo Basin, West Africa, this study systematically investigates the depositional characteristics, flow types, vertical sedimentary sequences, and depositional models of lacustrine gravity flows, based on newly acquired drill core data, analytical test results, and three-dimensional seismic interpretation from the study area. Three major gravity flow types are identified in this study: sandy debris flows, muddy debris flows and turbidity currents. Meanwhile, we highlight the critical roles of slide–slump deposits and contour currents in deep-water depositional evolution, which further clarifies the sedimentary characteristics, vertical facies association patterns and spatial distribution of the Pointe Indienne Formation. Based on these results, we construct a stepped-slope depositional model for lacustrine rift basins. This “stepped-slope-controlled gravity flow” model describes the evolution of sediment transport from high-density, block-based processes (slides/debris flows) to low-density turbulent processes (turbidity currents). Beyond explaining the geological features of sub-salt gravity flow deposits in the Lower Congo Basin, this model improves the accuracy of predicting deep-water gravity flow sand body distribution in lacustrine basins with analogous structural and topographic settings, providing robust geological and theoretical support for hydrocarbon exploration in similar regions. Full article

During continuous casting, the flow behavior of liquid steel in the tundish directly affects the temperature distribution of liquid steel, inclusion removal, and billet quality. In tundish-related research, water model experiments remain an intuitive method for investigating the flow process in the tundish. However, water model experiments are often conducted in different seasons, and variations in experimental temperature can change fluid properties such as density and viscosity, thereby affecting flow characteristics and the comparability of experimental results. In this study, a 1:3.57 transparent bare single-strand tundish model made of acrylic was used, and the differences in tracer transport processes at 7 °C and 20 °C, as well as the influence of different tracer dosages on the experimental results, were systematically investigated through flow visualization and stimulus-response experiments. The results showed that, under the 7 °C condition, the upward transport tendency of the pure ink tracer was weakened, the overall flow remained closer to the tundish bottom, the transport speed decreased, and the time required to reach the outlet was significantly prolonged. For the saturated KCl solution tracer, a lower temperature enhanced its transport along the bottom toward the outlet and suppressed its diffusion toward the liquid surface. The RTD results showed that, after the temperature was increased, the curves shifted to the left as a whole, and both the peak time and the mean residence time were shortened. The outflow percentage of tracer results showed that the difference for the 10 mL saturated KCl solution between the 7 °C and 20 °C conditions was the most significant. At 7 °C, the total outflow percentage of the 10 mL salt solution tracer at 1500 s was 76.86%, which was 22.97% lower than that at 20 °C. As the tracer dosage increased, the differences in the transport process, RTD curves, and outflow percentage curves under different temperature conditions gradually decreased, indicating that the effect of dosage on the experimental results gradually became stronger than that of temperature. These results indicate that the combined effects of experimental temperature and tracer dosage cannot be neglected in tundish water model experiments. Full article

Aquaculture ponds and salt pans represent the dominant forms of coastal production spaces along the Jiangsu coast, China; however, their long-term co-evolution and mutual transitions remain poorly understood. To bridge this gap, this study developed a 40-year (1985–2025) spatiotemporal dataset of these land covers leveraging Landsat imagery via the Google Earth Engine (GEE) platform. We established an integrated classification workflow encompassing single-scene water mask extraction, annual Modified Normalized Difference Water Index (MNDWI)-based water frequency statistics, Otsu automatic thresholding, connected-component labeling, and the masking of natural water bodies. The resulting dataset demonstrated high reliability, achieving overall accuracies (OA) ranging from 92.32% to 94.15% and an average Kappa coefficient of 0.89. Based on multi-metric analyses of area dynamics, annual change rates, and transition patterns, we identified three distinct co-evolutionary stages: simultaneous expansion (1985–1995), internal reorganization (1995–2015), and overall contraction (2015–2025). Notably, transitions between the two production spaces were highly asymmetric over the 40-year period; the area converted from salt pans to aquaculture ponds was approximately 15.23 times greater than the reverse conversion. Furthermore, their distribution exhibited strong spatial heterogeneity at the county level, underscoring the critical role of localized coastal planning in balancing economic production and wetland conservation. Ultimately, this work provides foundational data and methodological insights for long-term coastal ecological monitoring and sustainable production space management. Full article

Polyurethane (PU) mixtures are a promising high-strength, rapid-curing alternative to conventional asphalt, but their widespread application is hindered by slow curing rates and sensitivity to ambient moisture. To address these limitations, this study systematically evaluated the efficacy of three additives—lignin-based fiber, Glauber’s salt, and green vitriol—in regulating the curing behavior and performance of PU mixtures. Marshall stability, volumetric properties, and moisture resistance were measured under both outdoor and controlled laboratory curing conditions. Lignin fiber uniformly accelerates early-stage curing by enhancing moisture distribution via capillary action. Glauber’s salt releases crystalline water, drastically boosting early-age strength (by 162.4% after 2 days) but at the cost of an increased air void content (up to 8.1%) and reduced long-term water stability (residual stability <80%). Green vitriol acts through Fe²⁺ catalysis and crystalline water release, with its effectiveness being highly temperature- and delay-time-dependent. Combining fiber with Glauber’s salt yields the highest early strength but the shortest construction window (<1 h) and the most severe volumetric deterioration beyond the optimal delay time. All mixtures achieved high ultimate strength after sufficient curing (7 days), but the improvement varied significantly with additive type—ranging from 52.2% (fiber alone) to 162.4% (Glauber’s salt alone). Moreover, even under ideal curing, incomplete –NCO conversion persisted, indicating intrinsic cross-linking limitations. The residual stability of all mixtures fell below the 80% specification for conventional asphalt, suggesting that this metric alone is insufficient for assessing the moisture resistance of high-strength PU mixtures. This study demonstrates that while additives significantly enhance early-age performance, their application requires carefully optimized dosage, delay time, and temperature control to balance early strength gains with long-term volumetric integrity and durability. The findings provide revised evaluation metrics and practical guidelines for implementing PU mixtures in rapid pavement construction and repair. Full article

In recent years, the distribution of potassium salt resources in the Central Asia–Tarim Basin salt lake chain has shown an asymmetric pattern, and exploration efforts in the northwestern Tarim Basin have not seen significant progress. This study focuses on the central Bachu Uplift within the Central Asia–Tarim Basin salt lake chain. The characteristics of subsurface brines and indicators of potash formation are investigated. By examining various potassium exploration indices, such as the potassium–chlorine coefficient and magnesium–chlorine coefficient, along with comprehensive analysis of hydrogen–oxygen, sulfur, and strontium isotopes, this research serves to evaluate the potential for potash formation in the central Bachu Uplift. Analysis shows a brine salinity of 12.69–88.46 g/L and a potassium concentration of 0.07–0.65 g/L. The hydrochemical coefficients indicate a high nNa/nCl value, with low K × 10³/Cl values. All brine samples plot within the halite phase field of the 25 °C Na⁺,K⁺,Mg²⁺//C1⁻-H₂O Quaternary metastable phase diagram, clustering towards the Na-rich end. This indicates that the brine likely originated from halite dissolution. In the Na⁺,K⁺,Mg²⁺//C1⁻,SO₄²⁻-H₂O Quinary metastable phase diagram, the majority of samples project within the mirabilite phase field, trending toward the sylvite field. This suggests that the shallow subsurface brine may still be in the early to middle stages of sylvite deposition. Hydrogen and oxygen isotopes indicate that the brine samples were influenced by water–rock interaction and strong evaporative concentration; strontium isotopes reveal their marine–continental transitional characteristics; and sulfur isotopes suggest that the sulfur in the samples was derived from the weathering of Meso-Cenozoic gypsum in the western Tarim Basin. This integrated evidence implies that the brines in the central Bachu Uplift contain a deep-seated potassium anomaly, with fault zones likely conveying information about deep potash resources. This provides preliminary evidence for potassium exploration in the area and holds significant indicative value for identifying key prospective targets. Full article

Groundwater is the primary source of livestock watering across the arid pasturelands of western Kazakhstan, yet no systematic field hydrochemical assessment has been published for this region in over 40 years. This study presents the first systematic field-based hydrochemical characterisation of groundwater sources used for pasture livestock watering in the West Kazakhstan Region and Aktobe Region, filling a critical data gap that has persisted since the Soviet era. Specifically, it characterises the hydrochemistry, water quality, and infrastructure condition of groundwater sources, and evaluates the groundwater resource potential against current and projected livestock water demand. A total of 139 groundwater samples were collected along 11,182 km of field routes during May–July 2025, and analysed for 25 physicochemical parameters; hydrochemical classification was performed using AquaChem 11, and spatial analysis was conducted in ArcGIS 10.8. The groundwater chemistry distribution is bimodal: fresh bicarbonate-calcium-magnesium waters (TDS < 3.0 g/L) constitute approximately 80% of samples, while highly mineralised chloride-sulphate-sodium waters (TDS up to 9.91 g/L) occur in salt-dome-influenced discharge zones. Nitrate concentrations exceeded 50 mg/L in 23–36% of samples, with maxima of 635 mg/L, reflecting intensive anthropogenic contamination near livestock facilities. Predictive exploitable fresh groundwater resources exceed current livestock demand by a factor of 162. The principal constraint on pasture water supply is not resource scarcity but the non-operational status of 51–75% of inspected watering infrastructure, a legacy of post-Soviet institutional collapse that requires urgent rehabilitation. Full article

Saline water irrigation has emerged as a promising approach to mitigate agricultural water shortages; however, its improper use may induce secondary soil salinization. In this study, saline-alkali soil collected from Hami, Xinjiang, was used to conduct a series of indoor one-dimensional vertical soil column experiments. The aim was to systematically investigate the effects of sodium humate and desulfurization gypsum on soil infiltration behavior and the distribution patterns of key cations and anions under different levels of irrigation water salinity. The results showed that sodium humate application markedly improved soil infiltration capacity, while the duration of infiltration decreased with increasing salinity. Under salinity levels of 12 and 16 g/L, the 4 g/kg sodium humate treatment exhibited the most rapid advancement of the wetting front. In contrast, desulfurization gypsum reduced infiltration rates, with the lowest infiltration observed under the 12.5 g/kg treatment at 16 g/L salinity. Under different treatments, the adjusted coefficients of determination (adjusted R²) for the Philip, Kostiakov, and Horton models ranged from 0.8450 to 0.9841, 0.9901 to 0.9989, and 0.9748 to 0.9942, respectively, while the global performance indicator (GPI) ranged from 1.619 × 10⁻³ to 5.103 × 10⁻¹, 4.998 × 10⁻⁹ to 2.166 × 10⁻⁵, and 1.505 × 10⁻⁶ to 2.438 × 10⁻⁴, respectively. These results indicate that the Kostiakov model outperformed the other models in terms of fitting accuracy and overall performance for describing the soil infiltration process. In addition, sodium humate generally increased the sorptivity parameter S in the Philip model and the empirical coefficient K in the Kostiakov model, whereas desulfurization gypsum showed the opposite trend. In terms of salt regulation, sodium humate demonstrated optimal desalination performance at application rates of 6–8 g/kg under low salinity and 4–6 g/kg under high salinity conditions. Conversely, excessive gypsum application tended to exacerbate salt accumulation, although a moderate dosage (5 g/kg) effectively limited the downward migration and accumulation of Na⁺ and Cl⁻. These two ions were identified as the dominant contributors to soil salinization, showing strong positive correlations with soil salt content (SSC), sodium adsorption ratio (SAR), and exchangeable sodium percentage (ESP). In contrast, Ca²⁺, Mg²⁺, and HCO₃⁻ played beneficial roles in alleviating sodicity through ion exchange and buffering mechanisms. Overall, sodium humate enhanced infiltration and facilitated salt leaching in the upper soil layers under saline irrigation conditions. Although desulfurization gypsum reduced infiltration and increased overall salt content, it contributed to mitigating Na⁺ accumulation in deeper soil profiles. These findings highlight the critical importance of selecting appropriate soil amendments and optimizing their application rates to improve saline water use efficiency and promote sustainable management of saline-alkali soils. Full article