Search Results (1,235)

Actual evapotranspiration is a primary pathway for crop water consumption in irrigation districts, including the Shijin irrigation district, where understanding the impacts of irrigation is crucial for managing water resources in this large-scale, water-scarce region. However, existing studies on evapotranspiration driving mechanisms often overlook irrigation activities and lack an analysis of synergistic effects among different environmental factors, with such research remaining particularly limited for this area. This study investigates the synergistic impact mechanisms of multiple drivers on evapotranspiration. Using data from 2003 to 2017, a projection pursuit model was employed to quantitatively assess the contributions of meteorological factors, Leaf Area Index, and irrigation to evapotranspiration evolution. The results indicate a significant structural shift in evapotranspiration, and the reduction in soil evaporation plays an important role in driving the variation of total evapotranspiration. Among the various factors, Leaf Area Index and irrigation exhibited the highest contribution rates to evapotranspiration. Furthermore, irrigation primarily acts in synergy with crop growth to enhance evapotranspiration. This study provides critical scientific insights for evidence-based water resource management and policy optimization in the Shijin irrigation district. Full article

High-fluoride (F⁻) groundwater is a widespread environmental problem that poses significant risks to human health in many regions worldwide. Understanding the origin, circulation, and evolution of fluoride-rich groundwater is therefore essential for effective groundwater management and mitigation strategies. In recent years, stable isotope techniques have helped to address key gaps in understanding the hydrogeochemical processes governing F⁻ enrichment, particularly regarding the source identification and water-rock interaction mechanisms that remain poorly constrained. This study reviews the applications of hydrogen–oxygen, strontium–calcium, and lithium–boron isotopes in research on high-F⁻ groundwater systems. Hydrogen and oxygen isotopes (δ²H and δ¹⁸O) are widely used to identify groundwater recharge sources, mixing processes, and evaporative effects, thereby providing key constraints on the origin of fluoride-rich groundwater. Strontium and calcium isotopes (⁸⁷Sr/⁸⁶Sr and δ^44/40Ca) serve as effective tracers of water-rock interactions and associated hydrogeochemical processes, including mineral weathering and dissolution, cation exchange, and secondary mineral precipitation, which play critical roles in fluoride mobilization and enrichment. In addition, lithium, and boron isotopes (δ⁷Li and δ¹¹B) provide valuable insights into the influence of geothermal fluids and deep hydrothermal processes on fluoride accumulation in groundwater systems. Overall, the integrated application of these stable isotope systems offers a robust framework for elucidating the formation mechanisms and evolutionary pathways of high-F⁻ groundwater. Moving beyond qualitative source identification, future research should prioritize the development of Bayesian isotope mixing models that explicitly quantify uncertainty in fluoride source apportionment and utilize sensitivity analysis to test competing hydrogeochemical mechanisms. Full article

The wet-rail phenomenon can cause low adhesion, which negatively affects railway operation. It is believed to occur when small amounts of water mix with solid particles on wheel and rail surfaces, e.g., wear debris or iron oxides, forming a dense suspension in the wheel–rail contact, leading to sharp adhesion drops. Mini Traction Machine (MTM) tests using water-based suspensions with different particles also show adhesion drops during water evaporation, which can be linked to the wet-rail phenomenon. While the physical mechanisms underlying the adhesion drop are unclear, it is hypothesised that rapid loading raises fluid pressure in the suspension, separating wheel and rail surfaces, reducing force transfer through particle contact, thereby reducing the suspension’s shear strength. For verification, a coupled Discrete Element Method and fluid dynamics model is used to simulate a simplified MTM setting and steps towards full scale wheel–rail contact. During simulation of rapid loading, fluid pressure rises but remains negligible compared to applied contact stresses in all considered cases. Thus, it is unlikely that hydrodynamic pressure build-up within the suspension contributes significantly to the low adhesion observed. Future research should investigate additional mechanisms, such as reduced shear strength of deformed or crushed wet particles under high normal loading conditions. Full article

Typical saline lacustrine mixed sedimentary strata are developed in the Middle Permian Lucaogou Formation (P₂l) in the Jimsar Sag, with frequent interbedding of mudstone, dolomitic mudstone, and argillaceous dolomite. The widespread development of dolomite is a key factor controlling the quality of shale oil reservoirs. To reveal the formation mechanism of dolomite in mixed sedimentary rocks and its constraint on lithological assemblages, this study focuses on comparing the differences in mineralogy, geochemistry, and sedimentary environment of the three types of lithologies based on systematic tests such as thin-section observation, X-ray diffraction, major and trace element analysis, organic petrology, and biomarker analysis. The results indicate that dolomite formation in the study area is not controlled by a single factor, but instead results from the combined control of hydrothermal activity, microbial metabolism, and paleoclimatic fluctuations. Hydrothermal activity provided a source of Mg²⁺, and together with evaporation driven by an arid climate, elevated the Mg/Ca ratio of the lake water, establishing the hydrochemical basis favorable for dolomite development. Metabolic activities of lower aquatic organisms, such as bacteria and algae, promoted the formation of a sustained alkaline environment, creating favorable conditions for dolomite precipitation. Against a background of a relatively arid climate, the alternation of extreme arid and extreme precipitation events caused frequent fluctuations in lake water saturation, potentially providing ideal dynamic conditions for rapid and abundant dolomite formation. This combined control governed dolomite development and produced the interbedded lithological succession in the P₂l mixed sedimentary strata. This study integrates the dominant controlling factors and synergistic mechanisms of dolomite development in mixed sedimentary strata of continental saline lacustrine basins, which helps predict the occurrence and distribution of high-quality reservoir lithologies within such strata and has important implications for the optimization of “sweet spots” in shale oil exploration. Full article

Maize production in the black soil region of Northeast China is highly vulnerable to drought and flood stress, yet stage-specific mechanisms under rain-fed conditions remain unclear. Daily meteorological records from 1951 to 2024 were used to calculate the Crop Water Surplus Deficit Index (CWSDI) for four maize phenological stages, and 2025 in situ soil moisture and temperature observations were used to derive root-zone soil water storage (SWS), soil water depletion rate (SWDR), and the soil temperature–moisture coupling index (STMI). The growing season showed a persistent water deficit (mean CWSDI = −39.19%). Drought risk was greatest during sowing–jointing (S1; CWSDI = −64.73%; drought frequency = 73.0%) and milk–maturity (S4; CWSDI = −49.84%; drought frequency = 58.1%), whereas jointing–tasseling (S2) had the highest flood frequency (13.5%). Soil hydrothermal indicators showed that S1 drought was evaporation-driven, S2 involved potential hot-wet compound stress, tasseling–milk (S3) had rapid root-zone water depletion, and S4 drought was driven by insufficient late-season precipitation. These findings show that maize water stress is a sequence of stage-specific mechanisms rather than a uniform seasonal phenomenon. We therefore propose a regulation strategy combining soil moisture conservation, rainwater harvesting, precision supplemental irrigation, and field drainage to improve maize resilience. Full article

Recently, self-powered MoS₂/GaAs photodetectors have attracted intensive attention. However, thermal processing following metal–electrode deposition tends to damage the lattice structure of MoS₂, leading to degraded device performance and poor consistency. In this work, Au/MoS₂/GaAs photodetectors are fabricated using two different methods of transferring Au (Tr-Au) and thermal evaporation Au (TE-Au), and their photoelectric performances are compared. It is found that, compared to TE-Au devices, the Tr-Au devices exhibit higher responsivity (45.29 A/W) and detectivity (3.11 × 10¹³ Jones). The underlying mechanisms are attributed to a significant reduction in defect traps in MoS₂ and a smooth MoS₂/GaAs heterojunction interface, which collectively increase photocurrent and suppress dark current. Therefore, the room-temperature Au transfer method shows great promise for the fabrication of high-performance optoelectronic devices. Full article

Understanding the spatiotemporal evolution and driving mechanisms of soil salinization in the Yellow River Delta is a key research focus in the comprehensive utilization of saline–alkali land. Taking Zhanhua District as the study area, this study extracted soil salinization information using four remote sensing salinity index models (SDI1, SDI2, SDI3, SDI4). Model accuracy was evaluated, and the optimal model (SDI1, with an overall accuracy of 86.21%) was selected to analyze the spatiotemporal dynamics of soil salinization from 1993 to 2023. The XGBoost-SHAP framework was then applied to identify and interpret the driving factors of salinization. Furthermore, future soil salinization trends under climate change were projected based on four scenarios from the Sixth Coupled Model Intercomparison Project (CMIP6), including SSP1-2.6 (low forcing), SSP2-4.5 (medium forcing), SSP3-7.0 (medium-to-high-forcing), and SSP5-8.5 (high forcing). The results show the following: (1) Spatially, soil salinization in Zhanhua District exhibits a pattern of being “lighter in the south and heavier in the north.” Over the past 30 years, salinization has undergone a phased evolution characterized by a transition from “severe in the north and mild in the south” to “overall expansion” and finally to “improvement in the north and optimization in the south,” while the proportional structure of salinization severity levels has remained relatively stable. (2) Among the driving factors, evaporation is the dominant contributor (SHAP value = 0.3357), followed by precipitation (0.1732) and population density (0.1518). Soil moisture, land use, and temperature exert moderate influences, while nighttime light intensity, slope, and elevation contribute relatively less. Overall, soil salinization is jointly controlled by climatic factors and human–nature interactions. (3) Among the future climate scenarios, the SSP1-2.6 low-emission scenario exhibits the most pronounced mitigation trend, with a further reduction in salinization intensity projected by 2100. This study provides a scientific basis and data support for formulating soil salinization control and saline–alkali land management strategies in Zhanhua District and the Yellow River Delta. Full article

The thermal management-induced drag of conventional ram-air cooling systems for low-temperature fuel-cell propulsion can account for roughly 20% to 25% of total drag in fuel-cell aircraft concepts, while its mass and power impact at the overall aircraft level are far less significant. This drag penalty can severely reduce efficiency, especially when additional parallel power sources for takeoff such as gas turbine engines are undesirable. To address this, we propose augmenting low- and medium-temperature fuel-cell cooling with an auxiliary water-evaporation system. This mechanism is used only when needed, primarily during takeoff in hot ambient conditions, while the ram-air system can be downsized to meet cruise requirements. Water evaporation can achieve coefficients of performance of 50 to 100, while reducing the required mass flow by two orders of magnitude. It provides a heat-rejection energy density of approximately 670 $\mathrm{Wh}$/$\mathrm{k}\mathrm{g}$, far exceeding that of state-of-the-art high-power-density batteries. Furthermore, the resulting vapor can be vented overboard, and the system is expected to outperform batteries in reliability, durability, and environmental impact. The paper introduces several architectures for integrating water-evaporation cooling into aircraft systems and discusses their respective advantages, limitations, and implications for overall aircraft performance. Initial results indicate that enabling evaporative cooling can significantly reduce the required ram-air channel size and drag, offering a promising pathway to more efficient fuel-cell-powered aircraft. In the EU project TheMa4HERA, aircraft-level design trades and scaled experimental validation for aviation applications of water evaporation are planned in 2026. Full article

Understanding how the development of large-scale coal mining bases affects river hydrochemistry is a key scientific issue in the field of water environment research. In this study, the Qingyang–Binzhou section of the Jinghe River Basin was selected as the study area, and a total of 29 water samples were collected in April 2025 from the upper to lower reaches of the coal mining base. Hydrochemical analysis, ion ratio methods, and the positive matrix factorization (PMF) model were comprehensively applied to systematically characterize the hydrochemical features and identify the pollution sources in the river under the influence of large-scale coal mining activities. The results showed that the mean concentrations of Na⁺, SO₄²⁻, Cl⁻, and total dissolved solids (TDS) in the mainstream were as high as 414 mg/L, 728 mg/L, 226 mg/L, and 1636 mg/L, respectively, reflecting a significant impact of coal mining activities on river hydrochemistry. Four spatial variation patterns were observed along the river: the first pattern was characterized by “stable in the upper reaches, sharp increase in the middle reaches, and fluctuating increase in the lower reaches,” represented by Na⁺ and SO₄²⁻; the second pattern showed “stable in the upper reaches, slight decrease in the middle reaches, and fluctuating decrease in the lower reaches,” represented by pH; the third pattern exhibited “fluctuating in the upper reaches, sharp decrease in the middle reaches, and extremely low levels in the lower reaches,” represented by NO₃⁻; and the fourth pattern was dominated by irregular variations controlled by nitrogen transformation processes, represented by NH₄⁺ and NO₂⁻. Gibbs plots and ion ratio diagrams indicated that the hydrochemistry of sites unaffected by coal mine drainage was primarily controlled by rock weathering, whereas contaminated samples shifted toward the evaporation-concentration zone and extended beyond its typical range, reflecting an “anthropogenic salinization effect” induced by the input of mine water superimposed on the arid to semi-arid climatic background. The PMF model identified three main pollution sources: coal mining and mine water discharge (48.3%), domestic sewage (30.2%), and carbonate weathering (21.5%). This study reveals the significant modification mechanism of river hydrochemistry by large-scale coal mining base development, providing a scientific basis for targeted water pollution control in the Jinghe River Basin and for water environment management in similar mining areas. Full article

The paper presents the results of a study on the structure and electrical properties of graphite-like amorphous carbon films deposited by electron-beam evaporation with vacuum heat treatment. The current–voltage characteristics of the films were analyzed in weak and strong electric fields in the temperature range from 25 to 155 °C. For the contact of carbon films with nickel, the Schottky barrier height was calculated based on the obtained current–voltage characteristics. It was found that in the temperature range of 25–45 °C, the mechanism of direct tunneling of charge carriers through the narrow Schottky barrier dominates (φ_b = 0.055 eV). In the range of 55–75 °C, a transition to the thermally assisted tunneling mechanism is observed (φ_b = 0.076 eV). At temperatures above 85 °C, charge carrier transport through the Schottky barrier occurs via thermionic emission (φ_b = 0.3 eV). The analysis of the current–voltage characteristics of graphite-like carbon films allowed us to establish the main mechanisms of hopping conductivity via localized states. It is shown that in the temperature range of 298–348 K, conductivity is determined by states near the Fermi level. The temperature interval of 348–428 K corresponds to conductivity through the band tail of localized states near the conduction band. It is shown that the increase in conductivity in strong electric fields is due to the Poole–Frenkel effect. Full article

Understanding the coupled dynamics of groundwater flow and salinity transport is essential for the sustainable management of aquifer systems, particularly in irrigated and semi-arid regions where evaporation, recharge variability, and groundwater abstraction strongly influence hydrogeological regimes. In multilayer porous media, groundwater-level fluctuations and salt migration processes are closely interconnected, since hydraulic gradients control solute transport while salinity variations may affect flow behaviour through density-related mechanisms. In this study, a nonlinear mathematical model is developed to describe groundwater-level evolution and salt transport within a two-layer porous medium consisting of a phreatic layer and an underlying confined aquifer. The model accounts for filtration processes, interlayer hydraulic exchange, density-dependent effects, and external forcing factors including surface recharge, evaporation, and pumping. For numerical implementation, the governing equations are discretized using a finite-difference scheme with central spatial approximations and an implicit Crank–Nicolson-type temporal formulation. A hybrid second-order time approximation is introduced for the main-layer equation to improve numerical smoothness and stability. The resulting tridiagonal algebraic systems are solved using the Thomas algorithm within an iterative quasi-linearization framework, ensuring both computational efficiency and numerical robustness. Simulation results reveal a clear difference in the dynamical behaviour of the two layers. The phreatic aquifer exhibits rapid and high-amplitude responses to external forcing, whereas the confined aquifer demonstrates slower and smoother hydraulic and geochemical adjustments. Sensitivity analysis further identifies the filtration coefficient, transmissivity, porosity, density-related parameters, surface flux, and pumping intensity as the dominant factors governing groundwater dynamics and salinity redistribution. The proposed modelling framework provides a reliable tool for analysing coupled groundwater–salinity processes and offers a scientifically grounded basis for groundwater monitoring, salinization risk assessment, and sustainable aquifer management. Full article

Drought events have become more frequent worldwide under ongoing climate change. However, how precipitation deficits evolve into runoff deficits across contrasting dry and humid climate regions, and which factors control this transition, remains insufficiently understood. This study takes five climate zones in China (arid, semi-arid, semi-humid, humid–semi-humid, and humid) from 1970 to 2020 as examples to explore the propagation process of drought and its key driving factors. We used the Standardized Precipitation Index (SPI), Standardized Runoff Index (SRI), maximum correlation coefficient method, Kendall’s test, and multiple linear regression to identify the drought propagation time (DPT), its dynamic changes, and its main influencing factors. The results indicate that DPT exhibits significant seasonal and regional variations: on a national scale, its peak occurs in winter (7.35 months) and its trough in summer (2.54 months); specifically, propagation times in humid regions are relatively short and stable, whereas those in semi-arid, semi-humid, and humid–semi-humid regions are relatively long and highly variable. Temperature (20.69% in spring; 16.67% in summer) and potential evaporation dominate in spring, autumn, and winter, while summer precipitation (9.38%) also has a significant impact. The El Niño–Southern Oscillation (ENSO) has the most significant impact on humid regions, increasing the model R² from 34.6–37.2% to 43.7–45.0%. These results improve the understanding of drought propagation mechanisms across climatic regions, highlight the significant influence of ENSO on seasonal and regional variations in DPT, and provide a basis for regional drought early warning and water-resource management. Full article

The Aksu River Basin oasis, a typical arid ecological environment, faces considerable ecological and public health risks from fluoride accumulation in soil and groundwater. However, systematic investigations integrating soil–groundwater co-enrichment mechanisms with multi-pathway health risk assessments under environmentally relevant conditions remain scarce. We examined spatial fluoride distribution in the soil–groundwater system, associated health risks, and key driving mechanisms. Based on 2009 soil and 264 groundwater samples, we applied radial basis function (RBF) interpolation, Getis-Ord G_i* hotspot analysis, the geo-accumulation index (I_geo), the ecological risk index (ER), and the U.S. EPA health risk assessment model to evaluate pollution levels, ecological risks, and health impacts on adults and children. Spearman’s correlation analysis revealed relationships with 12 environmental factors, including topography, climate, soil properties, and vegetation. Key results are as follows: (1) High-fluoride soils (>700 mg·kg⁻¹) clustered in the eastern basin, while groundwater fluoride increased along a west–east gradient, with RBF interpolation yielding the highest accuracy; (2) soil fluoride was generally “unpolluted–moderate risk” (mean I_geo = −0.14, ER = 1.40), whereas groundwater posed the primary health risk, with a mean hazard quotient of 1.83 for children via drinking water, indicating non-carcinogenic risk; (3) soil enrichment was driven by evaporation–concentration–alkaline activation, while groundwater enrichment followed a convergence–concentration–evaporation mechanism, being negatively correlated with elevation. Groundwater fluoride presents a clear health risk, particularly to children, arising from high geological background levels and intense evaporation. Managing fluoride pollution and safeguarding drinking water quality in arid oasis regions is consequential. These findings provide a scientific basis for sustainable groundwater management and public health protection in arid oases. Full article

To enhance the mechanical properties and surface quality of PET composite aluminum foil fabricated by vacuum evaporation, an L₉ (3⁴) orthogonal experiment was performed to explore the influences of cooling roll temperature, evaporation boat voltage, tension roll force, and bias current on tensile strength, elongation, and surface morphology. Evaporation boat voltage had the most significant effect on tensile strength, whereas bias current mainly controlled elongation. The optimal parameters were identified as −30 °C, 10.5 V, 55 N, and 35 mA. Under these conditions, sample CAF-10 reached a tensile strength of 262.8 MPa and an elongation of 58.28% with a defect-free surface. A strong negative correlation between tensile strength and elongation was observed. Better interfacial bonding increased strength but reduced elongation, presenting an obvious trade-off. Overly high temperature or tension led to material defects and degraded the composite strength. These results validate the feasibility of orthogonal optimization and offer technical support for the industrial manufacturing of high-performance PET composite aluminum foil. Full article

Reverse osmosis (RO) membranes are widely applied in reuse facilities, but the management of RO concentrate remains a major sustainability challenge. Conventional brine disposal methods, such as deep well injection or evaporation ponds, are costly, energy intensive, and often ineffective at addressing the accumulation of contaminants of emerging concern (CEC) and per- and polyfluoroalkyl substances (PFAS). Bioelectrochemical systems, such as microbial fuel cells (MFCs), offer a promising pathway for sustainable brine organic load management by simultaneously reducing organic load and recovering energy. In this study, a pilot-scale MFC system (Aquacycl BETT^®, Escondido, CA, USA, unit, 12 modular reactors) was evaluated for treatment of RO concentrate produced by a combined ultrafiltration and closed-circuit reverse osmosis pilot train at the San Jacinto Valley Regional Water Reclamation Facility (San Jacinto, CA, USA). Operating with a 4-h hydraulic retention time, the MFC achieved an average chemical oxygen demand (COD) removal of 40% and biochemical oxygen demand (BOD₅) removal of 52%. Coulombic efficiency ranged from 2.8% to 15.5%, with an average energy recovery value of about 8.1 Wh per kg of COD removed. PFOS concentrations decreased by 36% across the MFC, and PFAS were not detected in the harvested anode biomass. The mechanism of PFOS attenuation (e.g., adsorption vs. transformation) was not directly evaluated. These findings highlight the potential of MFCs as a bioelectrochemical solution for sustainable water reuse RO brine management. Full article