Search Results (6,037)

In coastal regions, the interaction between freshwater and seawater creates a dynamic system in which the spatial distribution of salinity critically constrains the use of freshwater for human consumption. Although saline intrusion is a globally widespread phenomenon, its inland extent varies significantly with hydrological conditions, posing a persistent threat to groundwater quality and sustainability. This study aimed to characterize salinity distribution using an integrated karst-watershed approach, thereby enabling the identification of both lateral and vertical salinity gradients. The study area is in the northwestern Yucatan Peninsula. Available hydrogeological data were analyzed to determine aquifer type, soil texture, evidence of saline intrusion, seawater fraction, vadose zone thickness, and field measurements. These included sampling from 42 groundwater sites (open sinkholes and dug wells), which indicated a fringe zone approximately 5 km in size influenced by seawater interaction, in mangrove areas and in three key zones of salinity patterns: west of Mérida (Celestun and Chunchumil), and northern Yucatan (Sierra Papacal, Motul, San Felipe). Vertical Electrical Sounding (VES) and conductivity profiling in two piezometers indicated an apparent seawater influence. The interface was detected at a depth of 28 m in Celestun and 18 m in Chunchumil. These depths may serve as hydrogeological thresholds for freshwater abstraction. Results indicate that saltwater can extend several kilometers inland, a factor to consider when evaluating freshwater availability. This issue is particularly critical within the first 20 km from the coastline, where increasing tourism exerts substantial pressure on groundwater reserves. A coastal-to-inland salinity was identified, and an empirical equation was proposed to estimate the seawater fraction (fsea%) as a function of distance from the shoreline in the Cenote Ring trajectory. Vertically, a four-layer model was identified in this study through VES in the western watershed: an unsaturated zone approximately 2.6 m thick, a confined layer in the coastal Celestun profile about 9 m thick, a freshwater lens floating above a brackish layer between 8 and 25 m, and a saline interface at 37 m depth. The novelty of this study, in analyzing all karstic water surfaces together as a system, including the vadose zone and the aquifer, and considering the interactions with the surface, is highlighted by the strength of this approach. This analysis provides a better understanding and more precise insight into the integrated system than analyzing each component separately. These findings have significant implications for water resource management in karst regions such as Yucatan, underscoring the urgent need for sustainable groundwater management practices to address seawater intrusion. Full article

Hydrochar is a carbon-rich material produced through the hydrothermal carbonization (HTC) of wet biomass such as sewage sludge. Its nitrogen content is a critical quality parameter, influencing its suitability for use as a soil amendment and its potential environmental impacts. This study develops a high-accuracy ensemble machine learning framework to predict the nitrogen content of hydrochar derived from sewage sludge based on feedstock compositions and HTC process conditions. Four ensemble algorithms—Gradient Boosting Regression Trees (GBRTs), AdaBoost, Light Gradient Boosting Machine (LightGBM), and eXtreme Gradient Boosting (XGBoost)—were trained using an 80/20 train–test split and evaluated through standard statistical metrics. GBRT and XGBoost provided the best performance, achieving R² values of 0.993 and 0.989 and RMSE values of 0.169 and 0.213 during training, while maintaining strong predictive capabilities on the test dataset. SHAP analyses identified nitrogen content, ash content, and heating temperature as the most influential predictors of hydrochar nitrogen levels. Predicting nitrogen behaviour during HTC is environmentally relevant, as the improper management of nitrogen-rich hydrochar residues can contribute to nitrogen leaching, eutrophication, and disruption of aquatic biogeochemical cycles. The proposed ensemble-based modelling approach therefore offers a reliable tool for optimizing HTC operations, supporting sustainable sludge valorisation, and reducing environmental risks associated with nitrogen emissions. Full article

We present a 30-year analysis of water quality trends in Grand Teton National Park, based on 715 sampling events we collected at 33 locations across 29 lakes from 1995 to 2025. Our dataset includes Secchi depth, chlorophyll-a, and total phosphorus, collected seasonally from both in-lake and inlet sites. We classified lake trophic states using the Carlson Trophic State Index (CTSI) and the Vollenweider (VW) and Larsen–Mercier (LM) models. Most lakes remain mesotrophic (CTSI 38–54), with larger lakes such as Jackson and Phelps showing lower total phosphorus, while smaller lakes like Christian Pond and Cygnet Pond exhibit higher chlorophyll-a. High-elevation lakes generally have reduced nutrient concentrations. Seasonal effects are pronounced, with late summer and fall samples—especially at Swan Lake and Two Ocean Lake—showing increased chlorophyll-a. Trend analysis using the Mann–Kendall test identified statistically significant decreases in chlorophyll-a for six lakes and in total phosphorus for fifteen lakes; no lakes showed significant increases in any parameter. Four lakes—Christian Pond, Swan Lake, Two Ocean Lake, and Oxbow Bend—demonstrated consistent improvements across all measured indicators. The magnitude of these declines was modest, suggesting gradual oligotrophication rather than widespread eutrophication. Our comparison of trophic state models highlights that VW and LM often assign higher trophic classifications than CTSI. This study provides a robust baseline for understanding the resilience of high-elevation lakes in Grand Teton National Park. Our unique dataset, collected from remote and often barely accessible sites, is publicly available to support future research and management. Continued monitoring is essential to detect potential impacts of climate change and human activity, ensuring the preservation of these sensitive aquatic ecosystems. Full article

The socioecological system (SES) of the Qilian Mountains community—mountains, water, forests, fields, lakes, grasslands, and sands—faces considerable challenges from climate change and anthropogenic pressures. Here, we aimed to examine the coupled coordination relationships within the Qilian Mountains community. Using a comprehensive evaluation index system for the socioeconomic components of the life community, we analyzed the spatiotemporal evolution of the coupled coordination degree (CCD) from 2000 to 2023, identified key hindering factors, and forecasted future trends based on a grey prediction model. The overall CCD achieved a historic leap from near-disharmony to sound coordination. The findings reveal the following: (1) The overall CCD achieved a historic leap from near-disharmony to sound coordination from 0.340 to 0.523, indicating a transition into a synergistic development phase, though with persistent spatial disparities. (2) System coordination is primarily constrained by water, farmland, and grassland subsystems, with water supply–demand imbalance being the foremost regional obstacle. In the Hexi Oasis area, this manifests as a sharp contradiction between farmland expansion and agricultural water demand. In the Qinghai region, it is deeply intertwined with topography, water yield modulus, and the distribution of forested and aquatic areas. (3) GM(1,1) projections suggest a continued upward trajectory for CCD, yet also underscore the complexity and long-term nature of coordinated development. This study established a framework for socioecological system research in arid and vulnerable regions, with the conclusions providing a reference for optimizing national ecological security barrier construction and regional high-quality coordinated development. Full article

Soil erosion threatens agricultural sustainability and water quality in Mediterranean watersheds, necessitating effective Nature-Based Solutions (NBSs) for mitigation. This study applied the InVEST Sediment Delivery Ratio (SDR) model to assess erosion patterns and evaluate NBS effectiveness in the Carapelle watershed (506 km²). The SDR model was calibrated and validated using measured sediment yield data from 2007 and 2008. Model validation achieved a 4.3% deviation from observed data after parameter optimization. Four NBS scenarios were evaluated: contour farming (CF), no-tillage (NT), cover crops (CCs), and combined practices (Comb). Baseline soil loss varied from 2.43 t ha⁻¹ yr⁻¹ (2007) to 3.88 t ha⁻¹ yr⁻¹ (2008), with sediment export ranging from 0.86 to 1.30 t ha⁻¹ yr⁻¹. NT demonstrated the highest individual effectiveness, reducing sediment export by 72.2% on average. The Comb approach (NT + CCs) achieved a superior performance with a 75.9% sediment export reduction and a 70.5% soil loss reduction. Spatial analysis revealed that high-retention zones were concentrated in forest and shrubland, while agricultural zones showed the greatest potential for NBS implementation. NBSs significantly enhance sediment retention services in Mediterranean agricultural watersheds. The InVEST SDR model proves to be effective for watershed-scale assessment. The results provide actionable guidance for sustainable land management and soil conservation policy in erosion-prone Mediterranean environments. Full article

Thermal energy storage using latent heat storage materials represents a promising solution for stabilizing low-temperature energy systems; however, its effectiveness is limited by the low thermal conductivity of phase change materials (PCM), particularly salt hydrates such as sodium acetate trihydrate (SAT). The objective of this work is to analyze to what extent vertical gradation of a metallic gyroid structure can enhance heat transfer and temperature homogeneity in the PCM during charging. Time-dependent numerical simulations of conjugate heat transfer were performed for three gyroid variants differing in the orientation of pore gradation, modeling heat transfer between the flowing water, the aluminum gyroid structure, and the solid phase of SAT until the PCM reached a temperature of 58 °C. The results showed that the orientation of the gradation significantly affects both the heating dynamics and the quality of the temperature field. The variant with enlarged pores in the region of contact with the fluid and gradually decreasing pores toward the PCM achieved the shortest time to complete heating, the lowest temperature amplitude, and the highest degree of temperature homogeneity. This variant also exhibited the highest energetic efficiency, expressed as the ratio of transferred heat to pressure drop. The study demonstrates that deliberately designed gyroid gradation can substantially improve the performance of PCM composites without increasing the amount of material and represents a promising pathway for the development of advanced thermal storage systems. Full article

Earthquakes are among the most catastrophic natural disasters, primarily due to their immediate potential to cause loss of human life. However, their impact extends beyond the initial seismic event, particularly in karst systems, where groundwater resources are highly sensitive to geodynamic disturbances. The abundance of karst springs within these terrains makes them critical water sources for many communities, yet earthquakes can significantly disrupt their discharge patterns and degrade water quality. This study examines the vulnerability of karst springs to seismic activity, focusing on two case studies that illustrate distinct earthquake-induced hydrogeological effects. The first case investigates the temporary failure of the Opačac Spring near Imotski, Croatia, following the Mw 3.7 earthquake on 7 September 2018. This spring experienced a complete cessation of discharge for four days, as recorded by continuous hydrograph monitoring, before recovering due to the release of accumulated groundwater behind a temporarily blocked conduit. The second case explores the impact of seismic activity on water quality, focusing on the sensitive freshwater lens of the karstic Island of Vis in response to the Mw 6.1 earthquake on 22 April 2022, near Stolac, Bosnia and Herzegovina. Despite the epicenter being over 150 km away, water quality monitoring revealed notable changes, emphasizing the influence of seismic disturbances on fragile groundwater systems in carbonate island environments. Using a multidisciplinary approach, integrating seismic data analysis with hydrological and hydrogeological observations, this study investigates the mechanisms through which earthquakes alter karst water systems. A proposed vulnerability assessment framework is introduced, aiming to correlate earthquake intensity, proximity, and hydrogeological response to better predict karst spring failure and water quality degradation. This model provides valuable insights for disaster preparedness, water resource management, and risk mitigation strategies in karst terrains, highlighting the necessity of incorporating karst hydrogeology into regional earthquake response planning. Full article

Ensuring access to safe drinking water is a fundamental public health priority, yet the growing diversity of contaminants demands more human-relevant toxicity assessment frameworks. Conventional models based on immortalized cell lines or sentinel species, while informative, lack the tissue complexity and inter-individual variability required to capture realistic human responses. Organoids, three-dimensional epithelial structures derived from adult or pluripotent stem cells, retain the genomic, histological, and functional characteristics of their original tissue, enabling assessment of contaminant-induced toxicity, short-term peak exposures, and inter-donor variability within a single system. This study examined whether current international drinking water guidelines remain protective or if recent organoid-based findings reveal toxicity at differing concentrations. Comparative synthesis indicates that per- and polyfluoroalkyl substances (PFAS) often display organoid toxicity at concentrations above current thresholds, suggesting conservative guidelines, whereas most metals are properly regulated. However, some metals exhibit toxicity at concentrations that include levels below guideline values, highlighting the need for further investigation. Emerging contaminants, including pesticides, nanoparticles, microplastics, and endocrine disruptors, induce adverse effects at environmentally relevant concentrations, despite limited or absent regulatory limits. Integrating organoid-based toxicology with high-frequency monitoring and dynamic exposure modeling could refine water quality guidelines and support adaptive regulatory frameworks that better reflect real-world exposure patterns and human diversity. Full article

This review provides a comprehensive analysis of the petrophysical controls influencing greensand reservoirs, with an emphasis on the role of glauconite and associated clay minerals in determining porosity, permeability, and water saturation. Greensands contain iron-rich clay minerals that exert paramagnetic and conductive effects, challenging conventional well-log interpretations and often leading to biased estimates of reservoir parameters. Several challenges for petrophysical property measurements are faced in the laboratory due to clay-induced pore-throat obstruction and microporosity, which underscores the importance of tailored interpretation workflows and data integration. In this paper we highlight the necessity of integrated approaches such as combining core analysis, spectral gamma-ray, and nuclear magnetic resonance (NMR) logging with conventional well logs to calibrate petrophysical models using shale–sand water saturation models, such as Waxman–Smits and Simandoux, to better characterise economical pay zones. Finally, future research directions are indicated, which include refining the calibration of saturation and permeability models, advancing rock-typing methodologies, and understanding mineralogical influences on reservoir quality to optimise hydrocarbon recovery from greensand reservoirs. Full article

Responses of size-fractionated phytoplankton to environmental variables—particularly temperature, euphotic depth, and ammonium—were investigated in Gwangyang Bay to identify the phytoplankton groups responsible for estuarine blooms. Carbon-normalized biomass clearly showed the dominance of nanoplankton during summer and microplankton during winter. A combination of microscopy and flow cytometry analyses revealed that cryptophytes dominated the summer bloom, whereas diatoms dominated the winter bloom. Polynomial regression models indicated that diatom-dominated microplankton biomass declined sharply with increasing temperature and ammonium, while cryptophyte-dominated nanoplankton and cyanobacteria-dominated picoplankton biomass increased with rising temperature and decreased with increasing euphotic depth. These results highlight the substantial role of small phytoplankton (nanoplankton and picoplankton) in the bay ecosystem, where concerns over declining water quality and reduced nitrate availability are ongoing. Full article

Rapid and accurate moisture detection is critical for alfalfa quality control, yet conventional methods are slow, and non-destructive techniques are challenged by different product forms. This study leveraged Short-Wave Infrared Hyperspectral Imaging (SWIR-HSI) to acquire spatially representative spectra, aiming to develop and validate robust, form-specific moisture prediction models for compressed and powdered alfalfa. For compressed alfalfa, a full-spectrum Support Vector Regression (SVR) model demonstrated stable and good performance (mean Prediction Coefficient of Determination ${\mathrm{R}}_{\mathrm{P}}^2$ = 0.880, Ratio of Performance to Deviation RPD = 2.93). In contrast, powdered alfalfa achieved superior accuracy (mean ${\mathrm{R}}_{\mathrm{P}}^2$ = 0.953, RPD = 5.29) using an optimized pipeline of Savitzky–Golay’s first derivative, Successive Projections Algorithm (SPA) for feature selection, and an SVR model. A key finding is that the optimal model for powdered alfalfa frequently converged to an ultra-sparse, single-band solution near water absorption shoulders (~970/1450 nm), highlighting significant potential for developing low-cost, filter-based agricultural sensors. While this minimalist model showed excellent average accuracy, rigorous repeated evaluations also revealed non-negligible performance variability across different data splits—a crucial consideration for practical deployment. Our findings underscore that tailoring models to specific product forms and explicitly quantifying their robustness is essential for reliable NIR sensing in agriculture and provides concrete wavelength targets for sensor development. Full article

Water resources are increasingly scarce, with groundwater overexploitation causing major declines in quantity and quality. Effective water accounting is essential for sustainable management, which requires measuring irrigation water use despite limited metering. Traditional modeling approaches suffer from errors when there are narrow spatial coverages. Digital agriculture and remote sensing offer alternatives by enabling large-scale, cost-effective, and near-real-time monitoring. However, issues of accuracy, methodological consistency, and integration with governance frameworks still restrict operational use. This review followed the PRISMA protocol, screening 1485 documents and selecting 79 studies on remote sensing for irrigation water accounting. A structured labeling process classified papers into Technological Readiness, Management Impact, Implementation Barriers, Policy Integration, and Innovation/Gaps. Findings show a strong focus on management benefits and technological innovation, while institutional and policy aspects remain limited. Although many studies addressed multiple themes, governance integration and real-world barriers were often overlooked. Research is concentrated in digitally advanced regions, with limited attention to water-scarce areas in the Global South. The review concludes that although remote sensing improves efficiency and data availability, adoption is challenged by institutional, regulatory, and methodological gaps. Interdisciplinary work, stronger validation, and stakeholder engagement are essential for transitioning these tools into operational components of integrated water management. Full article

In studies of potential climate change (CC) impacts on freshwater ecosystems, water temperature is a primary abiotic factor. Still, it is insufficient to describe the specific habitat conditions that have changed for the biological elements of water quality affecting fish. In this study, special attention is focused on the fish bioindicator species, Barbus balcanicus. For two future scenarios of CC impact (RCP4.5 (2020–2050) and RCP8.5 (2070–2100)), in a Sutla River water body case study, fish life stage models are developed based on the fundamental abiotic factors (water flow, depth, velocity, temperature, and dissolved oxygen) to describe the ecological requirements of the selected fish bioindicator species. Two future CC impact scenarios and their results—water flow, dissolved oxygen, and nutrients, prepared by SWAT—have been analysed. To determine the most important abiotic factors, for water temperature, depth, and velocity, models have been developed by the machine learning tool Weka. The modelled biological elements of water quality were combined with previously calculated dissolved oxygen, flow, and E-flow values during dry periods and the spawning period. For both selected CC scenarios, the results indicate that in approximately 60–70% of the life stages of the bioindicator species Barbus balcanicus, the conditions are acceptable. Full article

Introduction: Chest drainage is central to thoracic surgery, pleural medicine, and emergency care, yet practice remains heterogeneous in tube caliber, access, suction, device selection, and removal thresholds. This narrative review aims to synthesize evidence and translate it into guidance. Materials and Methods: We performed a narrative review with PRISMA-modeled transparency. Using backward citation from recent comprehensive overviews, we included randomized trials, meta-analyses, guidelines/consensus statements, and high-quality observational studies. We extracted data on indications, technique, tube size, analog versus digital drainage, suction versus water-seal drainage, removal criteria, and key pleural conditions. Due to heterogeneity in device generations, suction targets, and outcomes, we synthesized the findings qualitatively according to converged evidence. Results: After lung resection, single-drain strategies, early use of water-seal, and standardized removal at ≤300–500 mL/day reduce pain and length of stay without increasing the need for reintervention; digital systems support objective removal using sustained low-flow thresholds (approximately 20–40 mL/min). Small-bore (≤14 Fr) Seldinger catheters perform comparably to larger tubes for secondary and primary pneumothorax and enable ambulatory pathways. In trauma, small-bore approaches can match large-bore drainage in stable patients when paired with surveillance and early escalation of care. For pleural infection, image-guided drainage, combined with fibrinolytics or surgery, is key. Indwelling pleural catheters provide relief comparable to talc in dyspnea associated with malignant effusions in patients with non-expandable lungs. Complications are mitigated by ultrasound guidance and avoiding abrupt high suction after chronic collapse; however, these strategies must be balanced against risks of malposition, occlusion or retained collections, prolonged air leaks, and device complexity, which demand protocolized escalation and team training. Conclusions: Practice coalesces around three pillars—right tube, right system, proper criteria. Adopt standardized pathways, device-agnostic thresholds, and volume or airflow criteria. Trials should harmonize “seal” definitions and validate telemetry-informed removal strategies. Full article

The textile industry releases effluents containing toxic contaminants such as azo dyes, which severely affect water quality and aquatic ecosystems. This study optimized the Fe⁰/H₂O₂/UV photo-Fenton process through Response Surface Methodology (RSM) using a Box–Behnken design applied to real textile wastewater. The process relies on in situ hydroxyl radicals (•OH) generation, which degrades refractory organic compounds. Under optimal conditions (pH 3.5, 0.5 g Fe⁰, and 0.55 mL H₂O₂), the system achieved complete color removal, 91% aromatic structures degradation, and an 80% COD reduction within 3 h. Statistical validation indicated an excellent model fit (R² = 1.0; Q² = 1.0), with strong correlation between experimental and predicted results. Spectroscopic analyses (UV–Vis and FTIR) further confirmed the cleavage of chromophoric and aromatic structures, indicating efficient pollutant degradation. Overall, the findings indicate that the Fe⁰/H₂O₂/UV system is an effective and sustainable technology for treating textile wastewater, offering strong potential for industrial-scale application. Full article