Search Results (179)

In the semi-arid Batna Belezma region of northeastern Algeria, groundwater is a vital resource for agriculture and drinking water. However, the climate leads to intense evaporation, which affects its quality. This study aims to identify the key hydrogeochemical processes that control groundwater composition in the Merouana Basin and to evaluate the predictive performance of machine learning (ML) models. A total of 30 groundwater samples were analyzed using multivariate statistical techniques, including Principal Component Analysis (PCA), and were modeled using PHREEQC to assess mineral saturation states. Additionally, ML-based regression models, including K-Nearest Neighbors (KNN), Support Vector Machine (SVM), Random Forest (RF), and Extreme Gradient Boosting (XGB),were employed to predict groundwater chemistry. The results indicate that the dominant ion distribution follows the following trend: Ca²⁺ > Mg²⁺ > Na⁺ and HCO₃⁻ > SO₄²⁻ > Cl⁻. Alkaline earth metals (Ca²⁺ and Mg²⁺) constitute the major fraction of total dissolved cations, reflecting carbonate equilibrium and dolomite dissolution processes. In contrast, Na⁺ represents a smaller proportion of the cationic load; however, its hydro-agronomic significance is substantial due to its influence on sodium adsorption ratio (SAR) and soil permeability. The PHREEQC modeling showed that calcite and dolomite precipitation promote evaporite dissolution, while most samples remain undersaturated with respect to gypsum. The PCA results reveal high positive loadings of Mg²⁺, Cl⁻, SO₄²⁻, HCO₃⁻, and EC, suggesting that ion exchange and seawater mixing are the primary controlling processes, with carbonate weathering playing a secondary role. To enhance predictive assessment, several supervised machine learning models were tested. Among them, the Random Forest model achieved the highest predictive performance (R² = 0.96) with low RMSE and MAE values, confirming its robustness and reliability. The results indicate that silicate weathering and mineral dissolution are the primary mechanisms governing groundwater chemistry. The integration of multivariate statistics and machine learning provides a comprehensive understanding of groundwater evolution and offers a reliable predictive framework for sustainable water resource management in semi-arid environments. Geochemical model performance showed a high global accuracy (GPI = 0.91), confirming a strong agreement between observed and simulated chemical data. However, the HH value (0.81) indicates some discrepancies, particularly for specific ions or extreme conditions. Full article

Located in the north of Yunnan Province, China, the Wuding geothermal area is a typical medium- and low-temperature geothermal system with strong hydrothermal activity and development potential as a clean and renewable energy resource. This study systematically investigates the main controlling factors of the Wuding geothermal field through field investigation, hydrochemical analysis, and stable isotope analysis, and puts forward a genetic model of the geothermal field. The results show that the Wuding geothermal field is a medium- to low-temperature, conduction-dominated geothermal system, and its geothermal water is predominantly of the Ca–HCO₃ (calcium bicarbonate) type. The recharge area lies at an altitude above 2250 m, which is speculated to be within the mountainous area in the southwest of the study area. The underground hot water in the area is immature water. The source water circulates to the deep heat storage zone along faults, rises to the surface through heat convection, and is exposed as hot springs. Upon discharge, the geothermal water mixes with shallow cold water, with cold-water dilution accounting for up to 85% of the total volume. Using the silica thermometer, cation thermometer, and silicon enthalpy model, the maximum temperature of heat storage is estimated to be 91 °C, with the depth of geothermal water circulation reaching 2200 m. The thermal reservoir is composed of dolomites of the Upper Cambrian Erdaoshui Formation (∈3e) and Sinian Dengying Formation (Zbd). Its heat source is heat flow from the upper mantle and the decay of radioactive elements. Continuous heat flow to the thermal reservoir is maintained through the fold fracture zone and faults in the core of the Hongshanwan anticline. The proposed genetic model of the Wuding geothermal field provides a scientific basis for the sustainable redevelopment and utilization of this geothermal resource and is of significance for regional low-carbon energy use and socio-economic sustainable development. Full article

Analyzing the hydrochemical characteristics and formation mechanism of metasilicic acid (H₂SiO₃) enrichment in the groundwater of Sanjiang Plain is conducive to guiding the rational development and utilization of mineral water resources in this region. Taking the groundwater in the typical black soil area of the northeastern Sanjiang Plain (from Qindeli Farm to Chuangye Farm) as an example, 104 groups of groundwater samples were collected to analyze enrichment and controlling factors of H₂SiO₃ by comprehensive methods such as hydrochemical analysis, rock geochemistry, water–rock interaction analysis, and ion ratio analysis. The results showed that the groundwater was generally in a reducing environment with low mineralization and weak acidity. The main cations were Ca²⁺ and Mg²⁺, and the main anion was HCO₃⁻. The hydrochemical types were mainly HCO₃–Ca and HCO₃–Ca·Mg, followed by HCO₃·Cl–Ca·Mg mixed type, and the H₂SiO₃ enrichment rate of groundwater reached 80.77%. The enrichment of H₂SiO₃ in the groundwater was related to the local geological structure and specific hydrogeochemical processes, and mainly controlled by the hydrolysis process of silicate rock minerals (such as albite, plagioclase, and olivine). The silicates and aluminosilicates contained in the basalt, diorite, and gneiss distributed in the area provided a rich material basis for the enrichment of H₂SiO₃. Its migration and distribution were simultaneously affected by leaching and cation exchange, while NO₃⁻ and SO₄²⁻ input from anthropogenic sources also participated in the rock weathering, specifically the enrichment process of H₂SiO₃ in the groundwater. From the perspective of mineralization conditions, Qinglongshan Farm and Qindeli Farm are potential areas for developing H₂SiO₃-rich mineral water. However, the main direction for the development and utilization of groundwater in this area should be to explore natural H₂SiO₃-rich groundwater with good comprehensive water quality. Full article

Tight oil reservoirs are widely recognized as a critical successor in global unconventional energy development and are generally characterized by distinct geological features, including fine pore throats, pronounced heterogeneity, and a high concentration of clay minerals (e.g., montmorillonite and mixed-layer illite/smectite). Severe hydration, swelling, and fines migration are readily induced during water injection or conventional water-based fluid operations, thereby resulting in irreversible impairment of reservoir permeability. Despite the excellent injectivity and capacity for viscosity reduction associated with CO₂ flooding, sweep efficiency is severely compromised by viscous fingering and gas channeling, which are induced by the inherent low viscosity of the gas. While CO₂ foam technology is widely acknowledged as a pivotal solution for addressing mobility control challenges, its implementation is hindered by a primary technical bottleneck: the incompatibility between traditional water-based foam systems and strongly water-sensitive reservoirs. A dual challenge comprising water injectivity constraints and gas channeling is presented by strongly water-sensitive tight oil reservoirs. To address these impediments, three emerging low-damage CO₂ foam systems are critically evaluated in this review. First, the synergistic mechanisms of novel quaternary ammonium salts and polymers in inhibiting clay hydration and enhancing foam stability within modified water-based systems are elucidated. Next, the physical isolation strategy of substituting the water phase with a non-aqueous phase (oil/organic solvent) in organic emulsion systems is analyzed, highlighting advantages in wettability alteration and the mitigation of water blocking. Finally, the prospect of waterless operations using CO₂-soluble foam systems—wherein supercritical CO₂ is utilized as a surfactant carrier to generate foam or viscosify fluids via in situ formation water—is discussed. It is revealed by comparative analysis that: (1) Modified water-based systems are identified as the most economically viable option for reservoirs with moderate water sensitivity, wherein cationic stabilizers are utilized to inhibit hydration; (2) Superior wettability alteration and the elimination of aqueous phase damage are provided by organic emulsion systems, rendering them ideal for ultra-sensitive, high-value reservoirs, despite higher solvent costs; (3) CO₂-soluble systems are recognized as the future direction for “waterless” flooding, specifically tailored for ultra-tight formations (<0.1 mD) where injectivity is critical. Current challenges, such as surfactant solubility, high-temperature stability, and cost control, are identified through a comparative analysis of these three systems with respect to structure-activity relationships, rheological properties, damage control capabilities, and economic feasibility. What is more, an outlook is provided on the molecular design of future environmentally sustainable, cost-effective CO₂-philic materials and smart injection strategies. Consequently, theoretical foundations and technical support are established for the efficient exploitation of strongly water-sensitive tight oil reservoirs. By bridging the gap between reservoir damage control and mobility enhancement, this study identifies viable strategies for enhanced oil recovery. Crucially, it supports carbon neutrality and sustainable energy targets via CCUS integration. Full article

A composite based on θ-Al₂O₃ microspheres coated with graphene oxide (GO) and reduced graphene oxide (RGO) was prepared and evaluated as a sorbent for the removal of synthetic dyes from aqueous solutions. GO was synthesized by a modified Hummers’ method and deposited onto alumina microspheres via ultrasound-assisted treatment under various conditions, followed by supercritical reduction to obtain the Al₂O₃_RGO composite. The structure, morphology, and composition of the materials were characterized by Raman spectroscopy, SEM, TGA/DSC, FTIR, and XRD, revealing the formation of mono- and few-layer GO/RGO coatings on the substrate surface. Adsorption tests for cationic methylene blue (MB) dye and anionic methyl orange (MO) dye demonstrated that the alumina substrate was inactive, whereas GO- and RGO-coated microspheres exhibited high adsorption efficiency for MB and partial uptake of MO from water solutions. In mixed-dye solutions, both Al₂O₃_GO and Al₂O₃_RGO composites showed selectivity toward MB, and the RGO-based composite demonstrated enhanced MB adsorption at low concentrations. The results highlight GO/RGO-coated θ-Al₂O₃ microspheres as convenient and selective composite sorbents for water purification processes. Full article

Olive mill wastewater (OMW) contains high organic loads and phytotoxic polyphenols. In Tunisia, OMW is often stored in unlined evaporation ponds. This practice creates a risk of soil and groundwater contamination. This study evaluates the environmental impact of a long-term OMW evaporation pond in the Ben Aoun area, Sidi Bouzid region. The investigation combines wastewater, soil and groundwater sampling with laboratory physicochemical analyses. Three OMW samples (E1 surface, E2 mixed, E3 recent spill) were collected. Three shallow boreholes (0–5 m) were sampled at 20 cm intervals. In addition, three nearby pumping wells were sampled. All samples were analyzed for pH, electrical conductivity (EC), chemical oxygen demand (COD), total and volatile solids, major cations/anions, total nitrogen, total phosphorus and total polyphenols. Results obtained using the Folin–Ciocalteu method are expressed as mg Eq AG L⁻¹ for liquids and mg Eq AG gMS⁻¹ for soils. OMW samples showed high COD (E1 = 48, E2 = 70, E3 = 80 g/L) and polyphenols (E1 = 5, E2 = 9.7, E3 = 14 g/L). Soil profiles inside the pond exhibited increased EC with peak of 15.48 mS cm⁻¹ at 0.4 m depth. Near-surface layers showed low pH and increased organic matter and polyphenols to depths of ~5 m. Groundwater samples collected near the pond contained measurable polyphenols (up to 41 mg/L in the closest well), indicating subsurface migration. Evidence indicates lateral migration of about 20 m and vertical infiltration to a depth of approximately 5 m beneath the pond. The findings demonstrate that unlined OMW evaporation ponds act as a persistent source of organic and phenolic contamination. This poses a potential risk to shallow groundwater. Full article

Lithium (Li) is a critical metal element in geothermal systems, yet its enrichment mechanism in coastal geothermal waters remains poorly understood. This study focuses on the Xiamen coastal geothermal system, located in the South China granitic reservoir at the front of the Pacific subduction zone. Self-organizing map (SOM) classification, hydrogeochemical analysis, hydrogen–oxygen isotopic constraints, and a three end-member mass balance model were applied to identify the sources and enrichment mechanisms of Li. The geothermal waters are classified into two types: inland low-TDS (Cluster-1) and coastal high-TDS (Cluster-2). Isotopic data indicate a mixture of meteoric water and seawater as the recharge source. The model shows that seawater and groundwater mixing accounts for 2–45% of Li concentration, with over 55% derived from the rock end-member. The leaching of 0.002–0.187 kg of granite per liter of geothermal water explains the observed Li levels. Elevated temperature and low pH enhance Li⁺ release from silicate minerals, and reverse cation exchange further amplifies this process. A strong positive correlation between the CAI-II index and Li⁺ concentration reveals a synergistic effect of ion exchange in high-salinity environments. Overall, the results provide a quantitative framework for understanding Li enrichment and evaluating resource potential in coastal geothermal systems. Full article

A novel and facile route for intercalating alkali-metal ions and ammonium ions into the layered mixed-ion compound tungsten oxychloride (WO₂Cl₂) has been developed using the iodide–triiodide redox couple as a mild redox-active reagent. Unlike traditional intercalation techniques employing highly reducing and air-sensitive reagents such as n-butyllithium, alkali triethylborohydride, and naphthalenide, the I⁻/I₃⁻ redox system operates at a moderate potential (0.536 V vs. SHE), enabling safer handling under ambient conditions without stringent inert-atmosphere requirements. This redox pair promotes the reduction of W⁶⁺ to W⁵⁺, thereby facilitating cation insertion into the van der Waal (vdW) gaps of WO₂Cl₂. This method uniquely enables ammonium ion intercalation into WO₂Cl₂, a first for this system. Intercalation was confirmed by X-ray diffraction, scanning electron microscopy (SEM/EDS), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), with measured lattice expansion correlating well with Shannon ionic radii and coordinating environments. Electrical transport measurements reveal a transition from insulating WO₂Cl₂ to a semiconducting phase for K_0.5WO₂Cl₂, exhibiting a resistance drop of over four orders of magnitude. This work demonstrates the I⁻/I₃⁻ couple as a general, safe, and versatile method for layered mixed-anion materials, broadening the chemical toolkit for low-temperature, solution-based tuning of structures and properties. Full article

Polyelectrolyte-based complexes have attracted attention, as the interaction of the oppositely charged components results in nanoparticle formation through an easy but highly efficient method, avoiding the use of strong solvents, extreme temperatures, and toxic chemicals. Sodium oleate (NaOL) is a widely used surfactant in the pharmaceutical industry due to its availability, eco-friendliness, and low cost. In the present study, the neutral-cationic block copolymer poly(oligo(ethylene glycol) methyl ether methacrylate)–b–quaternized poly(2-(dimethylamino) ethyl methacrylate) (POEGMA-b-Q(PDMAEMA)) is mixed with the anionic surfactant sodium oleate for the formation of nanoscale polyelectrolyte complexes through electrostatic interactions. Different weight ratios of copolymer to surfactant are studied. Then, the co-solvent protocol was implemented, and curcumin is successfully loaded in the formed particles for drug delivery applications. The size and morphology of the macromolecular complexes are examined via Dynamic Light Scattering (DLS) and Cryogenic Transmission Electron Microscopy (cryo-TEM). The methods that we have used have indicated that the polymer–surfactant complexes form spherical complexes, worm-like and vesicle-like structures. When curcumin was introduced, encapsulation was effectively achieved into micelles, giving rise to vesicle-like shapes. The success of curcumin encapsulation is confirmed by Ultraviolet–Visible absorption (UV–Vis) and fluorescence (FS) spectroscopy. POEGMA-b-Q(PDMAEMA)–sodium oleate polyelectrolyte complexes revealed promising attributes as efficient drug carrier systems for pharmaceutical formulations. Full article

Groundwater resources in Jordan are under severe stress due to rapidly increasing water demand and over-abstraction that far exceeds natural replenishment. In addition, water quality is threatened by pollution from the misuse of fertilizers and pesticides, leakage from septic tanks, and illegal waste disposal. This study focuses on the Aqeb, Corridor, and Special Economic Zone wellfields, where hydrological and hydrochemical investigations were carried out. A total of 36 groundwater samples were collected and analyzed for hydrochemical composition, stable isotopes of oxygen (δ¹⁸O) and hydrogen (δ²H), and trace elements. In addition, two exploration 2D seismic profiles crossing the study area were interpreted, providing critical insights into the activity of the subsurface Fuluk Fault zone and its relationship with the wellfields. The hydrochemical results reveal elevated total dissolved solids and nitrate concentrations, accompanied by more depleted δ¹⁸O and δ²H values in wells located in the central part of the study area. Three distinct hydrochemical groups were identified within the same aquifer, indicating heterogeneity in groundwater chemistry that reflects variations in recharge conditions, flow paths, and geochemical processes. The first group (high Na/Cl with low salinity) likely represents recently recharged waters with limited rock–water interaction. The second group (intermediate Na/Cl and moderate salinity) may be influenced by evaporation, irrigation return flow, or cation exchange. The third group (low Na/Cl with high salinity) suggests the dissolution of sulfate minerals or mixing with deeper mineralized groundwater, possibly facilitated by structural features such as the Fuluk Fault. Seismic interpretation indicates several active near-surface fault systems that are likely to serve as preferential pathways for salinity and nitrate enrichment, linked to intensive agricultural activities and wastewater leakage from nearby septic tanks. The findings emphasize the combined influence of geochemical processes, excessive groundwater abstraction, and structural features in controlling water quality in the region. Full article

This study examines the effect of cationic bio-based adhesion promoters (APs) derived from rapeseed oil (RO) on the performance of bitumen and asphalt mixtures. Several synthesized APs with varying polyamine content were evaluated and compared with commercial additives (Wetfix^® BE, Nouryon, Netherlands and Carbazole AK-M, SPETSKONTRAKT, Kyiv, Ukraine). Modification of bitumen with bio-based APs improved adhesion to glass and crushed stone while keeping penetration, softening point, and ductility within standard limits. Among the tested formulations, AP20 demonstrated the most balanced performance, achieving high adhesion values even at low dosages (0.2–0.4 wt. %). Asphalt concrete mixes prepared with AP20 exhibited enhanced water resistance and higher indirect tensile strength ratio (ITSR), indicating improved durability under moisture exposure. These findings highlight the potential of rapeseed oil-based adhesion promoters as effective and sustainable alternatives to conventional anti-stripping agents in road construction. Full article

Hybrid halide perovskites are promising materials for optoelectronics and space applications due to their excellent light absorption, high efficiency, and light weight. However, their stability under radiation exposure remains a key challenge, especially in space environments, where high-energy particles can cause significant damage. Here, we present the effects of primary and secondary radiation on perovskite materials, using Monte-Carlo simulations with the GEANT4 toolkit. The interactions of protons, electrons, neutrons, and γ-rays with APbI3 (A = Ma, FA, Cs) perovskites under space-relevant conditions typical for low Earth orbit (LEO) were studied. The results show that different perovskite compositions respond uniquely to radiation: CsPbI₃ generates higher-energy secondary positrons, neutrons, and protons, while MAPbI₃ produces more secondary electrons under proton irradiation. Mixed-cation perovskites exhibit narrower energy distributions for secondary γ-rays, indicating material-dependent differences in radiation tolerance. These findings suggest the potential role of secondary particle generation in perovskite degradation, based on our simulations, and they emphasize the need for comprehensive modeling to improve the radiation resistance of perovskite-based technologies for space applications. Future studies should consider contributions from encapsulating materials in device structures. Full article

The excessive use of chemical fertilizers results in environmental issues, including loss of soil fertility, eutrophication, increased soil acidity, alterations in soil characteristics, and disrupted plant–microbe symbiosis. Here, we synthesize recent studies available from up to 2025, focusing on engineered biochar and its application in addressing issues of soil nutrient imbalance, soil pollution from inorganic and organic pollutants, soil acidification, salinity, and greenhouse gas emissions from fields. Application of engineered biochar enhanced the removal of Cr (VI), Cd²⁺, Ni²⁺, Zn²⁺, Hg²⁺, and Eu³⁺ by 85%, 73%, 57.2%, 12.7%, 99.3%, and 99.2%, respectively, while Cu²⁺ and V⁵⁺ removal increased by 4 and 39.9 times. Adsorption capacities for Sb⁵⁺, Tl⁺, and F⁻ were 237.53, 1123, and 83.05 mg g⁻¹, respectively, and the optimal proportion of polycyclic aromatic hydrocarbon (PAH) removal was 57%. Herbicides such as imazapyr were reduced by 23% and 78%. Low-temperature pyrolyzed biochar showed high cation exchange capacity (CEC) resulting from improved surface functional groups. Although biochar application led to a yield increase of 43.3%, the biochar–compost mix enhanced it by 155%. The analysis demonstrates the need for future studies on the cost-effectiveness of biochar post-processing, large-scale biochar aging studies, re-application impact, and studies on biochar–compost or biochar–fertilizer mix productivity. Full article

Lead halide perovskites, including single-cation (MAPbI₃, FAPbI₃, CsPbI₃) and mixed-cation (Cs_0.12FA_0.88PbI₃, Cs_0.1MA_0.15FA_0.75PbI₃) compositions, are promising for both space photovoltaics and γ-ray detection due to their tunable optoelectronic properties. However, their response to high-energy radiation remains critical for reliable operation. We performed Monte-Carlo simulations using GEANT4 to investigate photon interactions (0.1–90 MeV) with perovskites of varying composition and thickness (1 cm to 1 μm). Results indicate that heavy atoms (Pb, I) dominate photoelectric absorption and scattering, broadly similar absorbed energies and event rates across compositions. Cs-containing perovskites exhibit slightly higher absorption and ionization, whereas FA- and MA-rich compositions show reduced photoelectric and Rayleigh scattering. Layer thickness strongly influences the radiation response: ultrathin films display fewer interactions with higher per-event energy, while millimeter-scale layers achieve efficient absorption and enable pair-production events at MeV energies. The sequence of dominant processes follows the expected energy dependence: photoelectric effect at low energies, Compton and Rayleigh scattering at intermediate energies, and pair production at high energies. These findings demonstrate that perovskite γ-interaction is primarily governed by heavy-atom content, with A-site cations fine-tuning the process balance, and that device performance for detection or photovoltaics depends critically on layer thickness. Full article

To elucidate the hydrochemical characteristics and evolution mechanisms of shallow groundwater in the alluvial–coastal transitional zone of the Tangshan Plain, 76 groundwater samples were collected in July 2022. An integrated approach combining Piper and Gibbs diagrams, ionic ratio analysis, multivariate statistical methods (including Pearson correlation, hierarchical cluster analysis, and principal component analysis), and PHREEQC inverse modeling was employed to identify hydrochemical facies, dominant controlling factors, and geochemical reaction pathways. Results show that groundwater in the upstream alluvial plain is predominantly of the HCO₃–Ca type with low mineralization, primarily controlled by carbonate weathering, water–rock interaction, and natural recharge. In contrast, groundwater in the downstream coastal plain is characterized by high-mineralized Cl–Na type water, mainly influenced by seawater intrusion, evaporation concentration, and dissolution of evaporite minerals. The spatial distribution of groundwater follows a pattern of “freshwater in the north and inland, saline water in the south and coastal,” reflecting the transitional nature from freshwater to saline water. Ionic ratio analysis reveals a concurrent increase in Na⁺, Cl⁻, and SO₄²⁻ in the coastal zone, indicating coupled processes of saline water mixing and cation exchange. Statistical analysis identifies mineralization processes, carbonate weathering, redox conditions, and anthropogenic inputs as the main controlling factors. PHREEQC simulations demonstrate that groundwater in the alluvial zone evolves along the flow path through CO₂ degassing, dolomite precipitation, and sulfate mineral dissolution, whereas in the coastal zone, continuous dissolution of halite and gypsum leads to the formation of high-mineralized Na–Cl water. This study establishes a geochemical evolution framework from recharge to discharge zones in a typical alluvial–coastal transitional setting, providing theoretical guidance for salinization boundary identification and groundwater management. Full article