Search Results (12,076)

Water-level fluctuation (WLF) is a key factor disturbing aquatic ecosystems, particularly aquatic plants (macrophytes in this review). These organisms are exceptionally sensitive to WLF as it profoundly governs their spatial distribution, productivity, species richness, community composition and successional trajectories. In this review, we synthesized recent advances regarding the impacts of WLF on the growth environment, survival strategies, and the integrated morphological, physiological, and reproductive responses of aquatic macrophytes. While existing research has predominantly focused on flooding-related WLF responses and freshwater macrophytes, the ecological consequences of drawdown and the responses of marine macrophytes remain comparatively underexplored. Despite the adverse alterations in sediment dynamics, light availability, hydrostatic pressure, pollutant concentrations, wind and wave exposure, dissolved oxygen levels and nutrient concentration conditions under WLF, aquatic macrophytes can demonstrate remarkable adaptive plasticity. This resilience was mediated through rapid adjustments in survival strategies, coupled with morphological traits, physiological processes and reproductive modifications. While their adaptive capacities were limited, and varied depending on life-forms, species or the WLF amplitudes, fluctuations in water level often precipitated rapid shifts in dominant species or even community succession over short timeframes. Consequently, while moderate WLF might confer ecological benefits, prolonged or extreme WLF posed substantial threats to aquatic vegetation. Synthesizing these findings, we developed a conceptual model diagram integrating the multifaceted responses of aquatic macrophytes to flooding-induced WLF. Future research should prioritize investigating the ecological consequences of drawdown-induced WLF and the responses of marine macrophytes—areas that remain comparatively underexplored. Furthermore, implementing refined water-level-management regimes could help optimize the good functions and services delivered by aquatic ecosystems. Full article

Pressurized seepage alters the water-accessible pore system of clay-mineral-rich slate, but its scale-dependent response remains unclear. Argillaceous calcareous slate from the Lower Cambrian Qiongzhusi Formation (Є₁q) was investigated using paired low-field NMR measurements on two specimen batches before and after 72 h treatments at nominal 0 MPa (low-head seepage), 1, 3, and 5 MPa. Total pore volume, pore-size composition, characteristic radii, and pore-size non-uniformity were evaluated. The total pore-volume increment increased from 0.98% to 1.43% in Batch I and from 0.88% to 1.56% in Batch II between 0 and 5 MPa. The dominant peak remained near 1.2 × 10⁻² μm, whereas its amplitude and large-pore spectral tail increased. The combined nanopore and micropore proportion decreased from 90.16–95.28% before treatment to 83.13–89.69% after treatment. The macropore increment increased from 0.15%/0.16% to 0.52%/0.52% in Batches I/II, while r₅₀, r₆₀, and C_u increased and r₁₀ changed only slightly. Sensitivity analysis over ρ₂ = 5–50 μm/s preserved the larger-pore enhancement. These results indicate pressure-enhanced opening, water accessibility, and local redistribution of pre-existing pores rather than extensive pore-system reconstruction, providing a pore-scale reference for seepage-related deterioration assessment. Full article

This study presents a life cycle assessment (LCA) of drip and flood irrigation systems for wheat production in the semi-arid Central Mashhad Plain, northeastern Iran, following the ISO 14040/14044 framework. The functional unit is defined as 1 ton of wheat grain at the farm gate. Environmental impacts were assessed using the ReCiPe 2016 Midpoint (H) method. Inventory data were sourced from field surveys, the Ecoinvent database, and regional statistics. The results indicate that while drip irrigation reduces water consumption by approximately 35.3% compared with flood irrigation, it is associated with higher environmental burdens in a range of impact categories, notably marine ecotoxicity (+62%), freshwater ecotoxicity (+58%), freshwater eutrophication (+42%), fossil resource scarcity (+41%), human non-carcinogenic toxicity (+38%), and global warming potential (+19%), along with substantial increases in mineral resource scarcity, human carcinogenic toxicity, and terrestrial ecotoxicity. These trade-offs are mainly linked to the material and energy demands of the pressurized irrigation infrastructure (pipes, pumps, and filters). Sensitivity and uncertainty analyses confirm the robustness of the comparative rankings. However, the analysis is limited by the gate-to-gate system boundary and the use of background databases that may not fully reflect region-specific emission factors. These findings highlight the importance of integrated irrigation policies that address both water conservation and the broader environmental implications of irrigation modernization in semi-arid, groundwater-dependent regions. Full article

Low-permeability sandstone reservoirs are characterized by fine pore-throat structures and strong heterogeneity, leading to complex multiphase flow behavior; since relative permeability curves are highly sensitive to displacement media, they serve as critical parameters for EOR performance and development optimization, yet the coupling between the pore-throat structure and the displacement fluid type remains poorly quantified. This study investigates low-permeability sandstone cores from the strike-slip fault block of the Laojunmiao Oilfield. Based on a petrophysical analysis and a high-pressure mercury intrusion, the cores are classified into four types (X1: medium pores, high permeability; X2: micropores, low permeability; X3: fine pores, relatively homogeneous; X4: fine pores with locally dominant channels), and unsteady-state relative permeability experiments are conducted under water, polymer, and nitrogen flooding. A comprehensive structural index (SI) is proposed to characterize the pore-throat structure and its correlation with the width of the two-phase flow zone. The results show that the pore-throat structure fundamentally governs the water flooding behavior, with Type X2 cores prone to preferential channeling; polymer flooding improves the mobility ratio most prominently in Type X1 and X3 cores; and nitrogen flooding performs best in Type X2 cores by retarding gas fingering. The two-phase flow zone width correlates linearly with the structural parameters, with polymer flooding showing the greatest sensitivity to structural variation. Full article

Surface energy partitioning regulates heat and water exchange between land and atmosphere and reflects alpine ecosystem responses to meteorological variation. Using radiation and meteorological data from November 2022 to October 2023, we compared adjacent alpine shrubland (Hulu 1) and alpine meadow (Hulu 2) ecosystems in the Qilian Mountains. Surface energy fluxes were estimated with a combined method based on surface energy balance, then evaluated with eddy covariance measurements. Path models examined direct and indirect environmental effects on turbulent fluxes. Standardized sensitivity coefficients based on evaporative fraction (EF) assessed seasonal responses of energy partitioning to environmental variation. Both ecosystems showed similar seasonal patterns, although flux magnitudes differed. Net radiation (R_n) followed a unimodal annual cycle and averaged 107.69 W m⁻² in the meadow and 89.36 W m⁻² in the shrubland. Sensible heat flux (H) peaked in May, with annual means of 60.22 and 51.68 W m m⁻². Latent heat flux (LE) peaked in July and averaged 49.12 and 38.58 W m m⁻². Soil heat flux (G) varied least, averaging −21.64 and −0.89 W m⁻². Path analysis identified R_n as the strongest control on turbulent fluxes. Its effect on H was weaker in the shrubland (0.92) than in the meadow (0.97), whereas its effect on LE was stronger in the shrubland (0.94) than in the meadow (0.71). Wind speed was positively related to H but negatively related to LE, with a stronger effect on H in the shrubland. Vapor pressure deficit (VPD) was negatively related to H but positively related to LE. Soil water content (SWC) had limited direct effects on turbulent fluxes at both sites. Sensitivity analysis showed higher overall EF sensitivity to environmental variation in the meadow during the growing season (0.510 vs. 0.228). Meadow EF was more sensitive to soil temperature (T_s) and SWC, whereas shrubland EF responded more strongly to VPD. Over the whole period, overall EF sensitivity was higher in the shrubland than in the meadow (0.439 vs. 0.353). These findings show that vegetation type and local environmental conditions jointly shape surface energy balance and energy partitioning in alpine ecosystems. Full article

Against the backdrop of global warming and the “warming and moistening” trend in northwestern China, arid inland river basins are highly sensitive to climate change, with their vegetation dynamics strongly controlled by upstream snowmelt water supply. The Keriya River Basin, situated on the northern slope of the Kunlun Mountains and the southern edge of the Taklamakan Desert, exhibits pronounced vertical zonation in vegetation cover and relies heavily on upstream snowmelt water supply for its water resources. To date, there has been a lack of systematic research into the spatiotemporal evolution patterns of long-term NDVI time series in this basin, its multiscale climate responses, and, in particular, future vegetation projections based on CMIP6 multi-scenario analyses and machine learning methods. To address this, this study utilised MODIS NDVI remote sensing data, historical data from the CMIP6 BCC-CSM2-MR model, and monthly temperature, precipitation, and snow cover data for three SSP scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5) and systematically analysed the spatiotemporal differentiation characteristics of NDVI in the Keriya River Basin and its multiscale coupling relationships with climatic factors. A multi-model selection and forecasting framework was developed, integrating feature engineering with the XGBoost machine learning algorithm. The study innovatively introduced a physically constrained scenario scaling factor based on historical correlations and future climate mean values, thereby addressing the bias where machine learning models’ predicted NDVI means converged across different SSP scenarios. This enabled the monthly estimation of NDVI under various emission pathways from 2015 to 2100. The results indicate: (1) During the historical period (2001–2024), the basin’s annual average NDVI showed an overall slight increase; the annual pattern was unimodal, peaking in July and reaching its trough in January–February; NDVI was highest in summer and lowest in winter. (2) NDVI initially increases and then decreases with altitude; the highest NDVI values are observed in the 3000–4000 m altitude band; in the mid-altitude band, NDVI rose significantly after 2010 and peaked in 2017; the low-altitude band exhibits the greatest interannual stability. (3) During the historical period, both temperature and precipitation in the catchment exhibited high levels of fluctuation, with annual mean temperatures ranging from 1.90 to 3.92 °C and annual precipitation ranging from 434.5 to 621.0 mm. NDVI showed a strong positive correlation with temperature (R = 0.86), a relatively strong negative correlation with snow cover (R = −0.71), and virtually no correlation with precipitation, indicating that upstream snowmelt is heat-driven and water-dependent. (4) Under the future SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios, temperature increases are projected to be 0.83 °C, 2.68 °C, and 5.35 °C, respectively, whilst snow cover is projected to decrease by 2.0%, 14.3%, and 34.0%, respectively; The multi-year mean NDVI values predicted using the XGBoost model (validation R² = 0.9097) are 0.0726, 0.0683, and 0.0690, respectively, all characterised by strong seasonal fluctuations. Given that these future projections are based on a single CMIP6 model and a statistical forecasting framework, they are subject to a degree of uncertainty; however, the low-emission scenario (SSP1-2.6) still indicates a trend that is relatively more conducive to maintaining vegetation stability in this region and may provide preliminary scientific guidance for water resource management along the southern margin of the Tarim Basin. Full article

Understanding the interactions among mountain snow resources, river discharge, and irrigated agriculture is essential for sustainable water management in transboundary river basins of Central Asia. This study evaluated the relationships among high-elevation snow conditions, hydroclimatic factors, summer river discharge, and agricultural vegetation dynamics in the transboundary Chu River Basin during 2001–2025 using MODIS snow-cover, snow-persistence, and NDVI products together with meteorological and hydrological observations. The results showed that snow cover was widespread during winter but declined substantially during spring, while the Mann–Kendall analysis indicated that no statistically significant trend predominated across most of the high-elevation snow zone, although significant decreases in snow persistence occurred across 12.83% of the analyzed area. For summer cropland NDVI, 61.15% of the analyzed area showed no significant trend, while significant decreases and increases occurred across 26.24% and 12.62%, respectively. Spring temperature exhibited a significant negative correlation with snow persistence (r = −0.64, p < 0.001), indicating the sensitivity of mountain snow resources to warming conditions. Summer river discharge was strongly correlated with summer precipitation (r = 0.77, p < 0.0001), vegetated cropland area (r = 0.76, p < 0.0001), and mean summer NDVI (r = 0.69, p < 0.001). In addition, snow persistence showed a significant positive relationship with summer river discharge (r = 0.63, p < 0.001), vegetated cropland area (r = 0.52, p = 0.008), and mean summer NDVI (r = 0.42, p = 0.036), suggesting a linkage between high-elevation snow conditions, seasonal water availability, and downstream agricultural vegetation. Canonical correlation analysis further revealed a strong multivariate association between hydroclimatic and hydroagricultural variables (Rc = 0.900, Rc² = 0.810). Overall, the findings indicate significant statistical linkages among climate conditions, snow resources, river discharge, and irrigated agriculture, providing a scientific basis for water-resource management and climate-change adaptation in transboundary mountain-fed basins. Full article

Argillaceous siltstone forms water-sensitive weak layers in red-bed slopes, but its multiscale deterioration under wet–dry cycling remains incompletely understood. Specimens subjected to 0, 1, 3, 5, 7, and 9 cycles were examined through uniaxial compression, energy analysis, digital image correlation (DIC), and microstructural and mineralogical characterization. The mean unconfined compressive strength (UCS) decreased by 36.0% after the first cycle and then remained broadly stable, with modest fluctuations, from 1 to 5 cycles. At five cycles, the elastic modulus remained substantially below the natural-state value, and although total strain energy approached the natural-state level, elastic strain energy remained lower and the dissipated energy ratio more than doubled, indicating continued irreversible damage. The characteristic calcite diffraction peak was no longer detected in the X-ray diffraction (XRD) patterns, while microstructural observations showed redistributed fines within pores together with a temporary decrease in face porosity. With further cycling, the UCS declined again and was 59.0% below its initial level after nine cycles. Meanwhile, strain fields and failure patterns evolved from localized deformation and splitting to distributed cracking and surface spalling, while particle detachment reopened pores and increased face porosity to 14.37%. These observations are consistent with a dissolution–filling–detachment mechanism and suggest that the intermediate UCS stabilization reflected temporary maintenance of load-bearing capacity rather than recovery of the original rock skeleton. Full article

Sensitivity is a critical performance parameter of sensors used in industrial process measurement systems. Conventional sensors are typically calibrated for a predefined operating range, resulting in reduced measurement sensitivity and accuracy when users require measurements within alternate subranges of the sensor’s operating band. To address this limitation, this paper proposes an intelligent autoranging technique that dynamically enhances sensor sensitivity across user-defined measurement ranges without the need for manual recalibration. The proposed approach integrates an adaptive calibration framework based on artificial neural network (ANN) algorithms to automatically adjust the sensor response for different operating intervals. The methodology is implemented and experimentally validated using a capacitance level sensor (CLS) incorporating a 60 cm helical electrode structure for liquid-level measurement. The experiments were conducted using water as the test liquid under controlled laboratory conditions. The sensor capacitance, varying from 0.929 nF to 421 μF over a liquid-level range of 0 to 60 cm with a resolution of 0.1 cm, is converted into a measurable voltage signal ranging from 0.010939 V to 2.953 V through a dedicated signal conversion and conditioning circuit. The experimental results demonstrate that the proposed ANN-based autoranging strategy significantly improves sensor performance by increasing the full-scale sensitivity from 4.9 V/m to 58 V/m across different user-selected measurement ranges. The developed technique offers a flexible and intelligent solution for enhancing sensor sensitivity and adaptability in process industry applications, enabling accurate measurements over varying operating ranges without additional calibration procedures. Full article

Urban drainage resilience assessments emphasize hydraulic performance or pollutant discharges at outfalls, with limited attention paid to street-level contamination following sewer surcharge and overflow. This study developed an event-based framework to quantify surface pollution exposure resilience. An integrated 1D pipe network–2D surface hydraulic-water quality model was implemented in InfoWorks ICM for Xiamen Island, China. Spatial analysis revealed a mismatch between inundation extent and pollutant concentration distributions, demonstrating that severe flooding does not necessarily coincide with high pollution exposure and hydraulic indicators alone cannot adequately represent pollution exposure risk. Therefore, an event-based performance function integrating overflow nodes, pollution exposure area, and exposure intensity under different designed storms was proposed. Results showed that hydraulic failure occurred rapidly after rainfall onset, whereas pollutant accumulation and spatial expansion exhibited delayed responses, reflecting different controlling mechanisms of drainage failure and pollution exposure. Sensitivity analysis indicated that hydraulic failure dominated resilience sensitivity to rainfall intensity, with node-focused weighting causing the largest decline (0.733 to 0.662), whereas pollution exposure determined the magnitude of overall resilience loss, which was consistently lowest under exposure area-focused weighting. These findings highlight the necessity of integrating hydraulic and pollution perspectives to understand urban drainage behavior and provide a scientific basis for targeted resilience-oriented management and urban renewal. Full article

The level of salt tolerance of rice varies with the developmental stage. The information on the tolerance of rice at each stage is valuable for breeding and planning in cultural management to obtain the optimal growth and yield in salt-affected areas. The objectives of this study were to compare the salt tolerance and physiological- and yield-related responses at three growth stages of the salt-sensitive Thai jasmine rice, KDML105, with its genetically improved variety RD73 (a registered commercial variety) and TSKC1-144 (a breeding line), both containing Pokkali-derived salt-tolerant QTL. The young hydroponically grown seedlings of TSKC1-144 treated with 150 mM NaCl were highly tolerant, while KDML105 was highly sensitive and RD73 was moderately tolerant. At the vegetative stage, KDML105 exhibited more growth and leaf physiological damage, showing the highest percentage reductions in the net photosynthesis rate (Pn), leaf relative water content (RWC), and shoot and total plant dry weight, but the highest increase in leaf electrolyte leakage (EL) and the highest leaf Na⁺/K⁺ ratio. During the reproductive phase, salt stress did not significantly induce physiological damage to the flag leaves, except for Pn, which was significantly reduced, particularly for KDML105. Both RD73 and TSKC1-144 exhibited lower biomass reductions and higher yields and yield components than KDML105. Compared with TSKC1-144, RD73 produced a lower grain number panicle⁻¹, grain weight panicle⁻¹, and lower 100-grain weight but 34% more panicles; therefore, it yielded a higher grain weight plant⁻¹ (27.57 cf. 20.93 g). The most prominent trait that conferred a greater salt tolerance to RD73 and TSKC1-144 compared with KDML105 was the more efficient Na⁺ exclusion. Taking their tolerance at all growth stages into consideration, RD73 and TSKC1-144 are deemed suitable for growing under rain-fed conditions where the intensity of the soil salinity fluctuates throughout the growing season. Full article

Hydrological modeling across heterogeneous watersheds remains a key challenge for water resource assessment in regions with strong hydroclimatic gradients. This study presents and evaluates the Chilean Hydrological Model for Climate Change (MHiDROC3) that integrates hydrometeorological and geospatial inputs, data imputation, sensitivity analysis, parameter calibration, distributed hydrological simulation, water-demand representation, and climate scenario analysis within a single workflow. MHiDROC3 was applied to five contrasting watersheds in south-central Chile over the 1980–2021 historical period. Across calibration, validation, and full-period simulations, KGE ranged from 0.51 to 0.77, while natural-streamflow simulations for the complete period showed KGE values of 0.52–0.74 and NSE values of 0.15 to 0.64, indicating variable model performance among basins. Mean simulated streamflow differed from observations by −32.2% to 17.7% across watersheds. Future simulations for 2022–2100 projected lower streamflow under SSP5–8.5 relative to SSP1–2.6, particularly during fall (−33.1% to −57.5%) and winter (−16.0% to −35.9%). By combining distributed process representation, demand effects, and climate-scenario testing in a Chilean framework, MHiDROC3 provides a practical basis for basin-specific water resource assessment, while its variable performance indicates that local evaluation remains necessary before operational application. Full article

The presence of antimicrobial-resistant bacteria in fresh produce constitutes a significant public health concern, particularly in rural areas where untreated water is commonly used for irrigation. Certain Enterobacter species have been reported as causal agents of onion bulb rot, with Enterobacter cloacae experimentally demonstrated to cause bulb rot in onions. However, there is poor documentation of its effects in the Vhembe District, South Africa. This study investigated the detection and identification of enteric bacteria in onions, soil, and irrigation water, as well as the characterisation of the identified isolates. Thirty-six samples were analysed, comprising 13 onion samples, 4 irrigation water samples, and 9 soil specimens collected from three farms using selective and differential agar. Identification and enumeration in water and onion samples were performed with the Colilert Quanti-Tray. Physicochemical analysis of irrigation water indicated that Farm 3 had the highest electrical conductivity (EC) and total dissolved solids (TDS), as well as the lowest pH, while Farm 2 exhibited the greatest diversity of pathogenic Escherichia coli pathotypes, including enteroinvasive E. coli (EIEC), which was absent in Farm 3. Culture-based methods yielded 72 presumptive bacterial isolates, which were characterized using the VITEK 2 system. Identified species included Pseudomonas aeruginosa, Klebsiella pneumoniae, Klebsiella oxytoca, Citrobacter amalonaticus, Raoultella ornithinolytica, and members of the Enterobacter cloacae complex. Phylogenetic analysis revealed that most Enterobacter isolates closely matched reference strains of Enterobacter ludwigii. Antimicrobial susceptibility testing against 19 antibiotics demonstrated varied resistance patterns among the isolates. The Enterobacter cloacae complex exhibited the highest resistance (10/19 antibiotics), followed by Klebsiella pneumoniae (9/19) and Citrobacter amalonaticus (7/19). All isolates were resistant to colistin but remained susceptible to ciprofloxacin, with most also sensitive to gentamicin and amikacin. Future research should include additional farms and investigate antibiotic resistance at the genetic level to elucidate its origins. Full article

Soil salinization poses a major environmental threat to global agriculture, affecting approximately 20% of cultivated land and 50% of irrigated land worldwide. Developing salt–alkali tolerant plant varieties represents a sustainable strategy for utilizing these marginal lands. Phosphatidylinositol-specific phospholipase C (PI-PLC) is a key enzyme in the phosphoinositide signaling system and has been implicated in plant stress responses; however, its function under salt–alkali stress remains poorly understood. In this study, the function of AtPLC1 in salt–alkali tolerance was investigated, and only the atplc1 mutant exhibited a pronounced stress-sensitive phenotype, with AtPLC1 being predominantly expressed in roots and leaves, with peak expression at 6 h of treatment. Compared with wild-type, atplc1 mutants displayed significantly reduced seedling survival, retarded root growth, decreased biomass, water content, chlorophyll, and soluble sugar contents, yet accumulated higher levels of Na⁺, malondialdehyde, H₂O₂, and superoxide anions under salt–alkali stress. Notably, atplc1 mutants showed increased stomatal conductance and decreased leaf surface temperature, as detected by thermal imaging, indicating impaired water regulation. Collectively, our findings demonstrate that AtPLC1 positively regulates salt–alkali tolerance and provides a candidate gene for molecular breeding of stress-resistant crops. Full article

The durability deterioration of concrete under the coupled action of freeze–thaw cycles and corrosive media is a critical technical challenge for engineering structures in cold regions and salt corrosive environments. This paper systematically reviews the research progress on the mechanical properties of concrete subjected to coupled freeze–thaw and corrosion effects. Starting from the mechanisms of freeze–thaw damage and corrosion damage, it analyzes the material degradation laws under individual factors and the synergistic failure mechanism of the coupled freeze–thaw–corrosion condition. The coupling effect is revealed: freeze–thaw-induced microcracks accelerate the penetration of corrosive media, while the expansion of corrosion products in turn aggravates freeze–thaw damage. Building on this, from the perspective of factors influencing concrete failure, this paper systematically summarizes the key factors governing concrete damage under single-factor and coupled-factor conditions as well as their nonlinear response characteristics. The review indicates that the damage degree under the coupled action is far greater than the simple superposition of damage caused by individual factors and presents complex patterns, including the concentration threshold effect, the time-sequence effect, and sensitivity to a low water–cement ratio. Existing reviews predominantly focus on qualitative descriptions of single-factor deterioration mechanisms, while systematic comparative analyses of threshold behaviors under multi-factor coupling and quantitative consolidation of mechanical degradation metrics remain limited. Furthermore, targeted durability design guidance tailored to cold saline environments is rarely summarized in the prior literature, which motivates the present comprehensive review. Although existing studies are relatively well-established for single damage mechanisms, further efforts are still needed to deepen the understanding of multi-factor interaction thresholds and dynamic evolution processes. The findings of this review can provide theoretical support and engineering reference for the durability design and service life prediction of concrete structures in cold regions and salt corrosive environments. The summarized threshold laws and quantitative mechanical degradation data can provide targeted parameter guidance for the durability design of hydraulic structures, bridge substructures, and port engineering in northwest saline soil, northern severe cold, and eastern coastal salt fog areas. Full article