Search Results (6,217)

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

Shale gas will be the focus of global oil and gas exploration in the future. As a key mineral component in shale, the characteristics and genesis of feldspar are of great significance for reservoir quality. The feldspar in the Qiongzhusi Formation shale was studied through core observation, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and major and trace elements analysis. The results show that the content of feldspar in the Qiongzhusi Formation shale is relatively high, with an average content of 27.3%, mainly sodium feldspar. The feldspar presents various forms, such as angular clastic particles and strongly altered particles. It exhibits localized dissolution and illitetization. The feldspar in the Qiongzhusi Formation shale is multi-source, mainly provided by the mixture of felsic sedimentary rocks and granites from the upper crust. The main source areas are the Western Sichuan Block, the Motianling Block, and the Hanyang Block. Rapid sedimentation leading to rapid burial is the primary sedimentary control factor for the high initial content of feldspar in the Qiongzhusi Formation shale. During the late burial and diagenetic stages, localized fluid action, comprising the synergy between micro-scale migration and chemical reactions driven by hydrocarbon generation, acts as a key factor influencing the minor variations in feldspar content. Under a stable tectonic background, the fluids in the Qiongzhusi Formation mainly come from organic acids produced by shale hydrocarbon generation, and the influence of formation water fluids is relatively limited, with a low degree of feldspar mineral transformation. Full article

Biochar-based fertilizers (BBFs), including formulations enriched with additives, are sustainable alternatives to conventional fertilizers, promoting waste reuse and controlled nutrient release. This study performed a global meta-analysis to evaluate nutrient dynamics (release and leaching in water and soil) and the agronomic performance of additive-enhanced BBFs compared with unfertilized and/or conventionally fertilized controls. Thirty studies were selected, with 264 experimental pairs extracted from the Web of Science and Scopus databases, and analyzed using a random-effects model. The results indicated that BBFs enriched with natural mineral additives promoted an average increase of 204.3% in nutrient release in water (p < 0.001), whereas in soil biotechnological additives showed the greatest increase, with 109.8% (p < 0.001). Leaching was reduced by up to 74.4% with BBFs enhanced with agricultural residue additives and by 46.9% with industrial additives, indicating greater nutrient retention and greater nutrient-use efficiency. In terms of agronomic performance, additive-enhanced BBFs resulted in average increases of 49.3% in plant height, 232.3% in aboveground biomass, 60.8% in root biomass, and 11.2% in grain yield, compared to unfertilized soil. Overall, the effectiveness of BBFs depends on both the type of additive and the application method, with industrial and mineral additives being the most promising for controlled nutrient release and increased crop productivity. Full article

This study presents a short-term, IoT-enabled sensor-based assessment of treated municipal water and decentralized groundwater in Bragança, northeastern Portugal. Two drinking-water supply contexts were compared: treated surface-water-derived municipal water from the public supply system and groundwater from a decentralized supply system serving part of a higher education campus. Five sampling points were monitored during three campaigns between January and March 2026. At each point, pH, electrical conductivity, temperature, oxidation–reduction potential, and total dissolved solids were recorded at 10 s intervals over approximately 10 min monitoring windows using a multiparameter probe integrated into an IoT-enabled data acquisition workflow. Microbiological analyses were performed on groundwater samples as complementary information. Treated municipal water showed lower mineralization, narrower parameter ranges, and higher oxidation–reduction potential, reflecting source-water characteristics, treatment, and operational control. Groundwater showed higher mineralization, lower oxidation–reduction potential, and greater variability among sampling points and campaigns, consistent with stronger local hydrogeochemical and operational influences. The repeated short-interval readings provided more detailed physicochemical profiles than isolated spot measurements, although the short monitoring windows do not represent continuous long-term high-frequency monitoring. Overall, the results support standardized IoT-enabled sensor-based monitoring as a complementary tool for short-term water-quality assessment and indicate the need for longer seasonal datasets and laboratory confirmation. Full article

Rice (Oryza sativa L.) straw-return can improve soil carbon (C) sequestration, but its adoption in intensive rice systems is limited by short fallow periods (< 30 days), which likely lead to incomplete straw decomposition and increase methane emissions under continuous flooding (CF). Brittle rice straw, characterized by lower recalcitrant fiber content and rapid decomposition, may overcome this constraint; however, its environmental performance under alternate wetting and drying (AWD) remains unclear, such as broader C allocation. This 150-day microcosm study evaluated the interaction of straw type (brittle vs. non-brittle) and water management (CF vs. AWD) on greenhouse gas (GHG) emissions, dissolved C production, soil C storage, and aggregate formation in two contrasting paddy soils (sandy loam vs. silty clay loam). Compared with non-brittle straw, brittle straw returns reduced net GHG emissions by approximately 28.4% under CF and 39.6% under AWD. The combination of brittle straw with AWD produced the lowest net GHG emissions (0.61 kg CO_2-eq m⁻²), indicating that intermittent oxygen input effectively mitigated the early decomposition-related emission risk. Brittle straw also increased the concentrations of dissolved inorganic C by 14.2% and nitrate by 64.3% under AWD, suggesting enhanced mineralization and potential inorganic C stabilization. Regardless of straw type, straw return improved soil C stocks by 27.3% in sandy loam and 29.6% in silty clay loam, while also promoting macroaggregate formation. Overall, this study demonstrated that coupling brittle rice straw with AWD can reduce GHG emissions while maintaining soil C benefits, offering a promising residue management strategy for intensive rice cultivation. Full article

A study was conducted on the construction of sulfonated poly(aryl ether ketone) nanomicelles and their dispersion–displacement synergistic behavior in deep oil recovery. Unlike conventional surfactant systems, inorganic nanoparticle-based EOR materials, and polymeric nanofluids that mainly rely on interfacial tension reduction, wettability alteration, or viscosity regulation, this study constructs self-assembled sulfonated poly(aryl ether ketone) nanomicelles that integrate a rigid aromatic backbone, ionizable sulfonic acid groups, nanoscale dispersion, and interfacial regulation within one polymeric architecture. Sulfonated poly(aryl ether ketone) nanomicelles were prepared by combining polymer sulfonation with solvent-induced self-assembly, and their structural features, dispersion stability, interfacial behavior, porous-media transport, and displacement performance were systematically evaluated. Spectroscopic characterization confirmed the successful introduction of sulfonic acid groups into the polymer backbone. The resulting nanomicelles exhibited an average hydrodynamic diameter of 117.8 nm, a polydispersity index of 0.186, and a zeta potential of −38.6 mV in deionized water, while a value of −27.4 mV was still maintained at a salinity of 150,000 mg/L, indicating good electrostatic stability under highly mineralized conditions. Further evaluation showed that the 0.30 wt% system retained a transmittance of 97.4% after 15 d of static standing, and its particle size remained at 151.7 nm even under 120 °C and 150,000 mg/L, demonstrating favorable thermal–salinity tolerance. At the same concentration, the oil–water interfacial tension decreased to 6.9 mN/m at 1800 s, while the contact angle of oil-aged quartz was reduced from 118.4° to 58.7°, indicating effective regulation of both the oil–water interface and the solid surface wettability. During microscopic displacement, the residual oil area fraction decreased from 32.8% after water flooding to 14.6%, and cluster-like oil, corner oil, and film-like oil were reduced from 14.6%, 9.8%, and 8.4% to 5.9%, 4.2%, and 4.5%, respectively. In core flooding, the incremental oil recovery reached 13.2%, the final water cut decreased to 81.2%, and the injection pressure increased only from 0.42 MPa to 0.68 MPa. These results indicate that sulfonated poly(aryl ether ketone) nanomicelles promote deep residual-oil mobilization through the combined effects of stable dispersion, interfacial regulation, and effective transport, with 0.30 wt% identified as the preferred concentration range. The main scientific contribution of this work is to establish a structure–dispersion–interface–transport–displacement relationship for SPAEK nanomicelles under deep-reservoir conditions, providing a polymeric nanomicelle-based strategy distinct from conventional surfactant, sulfonated polymer, and nanoparticle flooding systems. Full article

The lamprophyre dikes and multi-generational pyrite and arsenopyrite developed in the Jinshan gold deposit in the West Qinling metallogenic belt provide critical evidence for understanding the role of mantle-derived magmatism in gold mineralization processes. In this study, we conducted zircon U-Pb dating of lamprophyre to constrain the timing of magmatic activity and the mineralization age, and performed EMPA and LA-ICP-MS analyses on sulfides from the main metallogenic stage (Py II–III, Apy II–III) and lamprophyre-hosted pyrite (Py L) to constrain the formation conditions and metal sources of the Jinshan deposit. The results show that the mantle-derived magmatism represented by lamprophyre yields an age of 206 ± 2 Ma, which provides a lower-limit constraint on the timing of gold mineralization, corresponding to the subduction-to-extension transition period in the region. Stage II mineralization occurred at 270–320 °C with logƒS₂ of −9 to −5, dominantly as Au-HS complexes, indicating medium-temperature hydrothermal conditions with low sulfur fugacity, consistent with microscopic mineral assemblages and thermodynamic simulations. Systematic δ³⁴S variations reveal: stage II values (9.24–5‰) indicate granitic/Devonian sedimentary sources; Py L values (2.19–3.6‰) reflect mantle contributions; stage III signatures (−2.3–1.93‰) record late meteoric water mixing. Complementary δ⁵⁶Fe data show that Py II (0.2–0.3‰) and Py L (0.58–0.68‰) preserve magmatic fingerprints, while negative values of Py III (−2.29 to −0.71‰) document increasing sedimentary Fe incorporation. Combined with geochronology, S-Fe isotopes, and physicochemical constraints, we propose that the Jinshan gold deposit formed in a tectonic setting transitioning from compression to extension during the Late Indosinian (ca. 237–201 Ma). Mineralization was initiated by the partial melting of the metasomatized mantle, where hydrous magmas efficiently extracted Au and volatiles. These components ascended through transcrustal faults, with Au partitioning into exsolved fluids that precipitated gold through immiscibility and boiling in secondary structures. Full article

The cosmetics industry continually seeks innovations that deliver ever-higher performance while meeting growing sustainability requirements. Although numerous plant-derived surfactants have recently emerged, achieving performance levels comparable to synthetic benchmarks remains challenging. In this study, we aimed to design a natural polyglycerol-10 ester (PG-10 ester) capable of stabilizing demanding systems such as high-internal-phase nano-emulsions (nano-HIPE) and mineral oil-in-water sunscreens. We investigated the key parameters governing surfactant efficiency: fatty acid composition from C12 to C22 or their blends, the presence of partial glycerides, and reaction parameters. Various polyglycerol esters were synthesized and characterized through chromatographic analysis and HLB determination, and then incorporated into formulations to assess their performance. This work made it possible to identify four parameters as essential for achieving high surfactant efficiency: (i) grafting multiple fatty acids onto a single polyglycerol backbone, (ii) combining short/medium-chain (<C16) and long-chain (≥C16) fatty acids, (iii) including partial glycerides within the surfactant, and (iv) allowing the reaction medium to reach full equilibrium. Achieving full equilibrium results in synthesis medium clarity, which allows the HLB value to rise from 6 to 7 to 11–12 and ensures complex emulsion stability. This rational design approach led to a natural PG-10 ester whose performance equals that of conventional synthetic benchmarks, providing a significant advancement toward sustainable high-performance surfactant technologies. Full article

Serpentine group minerals, including lizardite, antigorite, and chrysotile, are common gangue minerals in nickel sulfide ores, and exhibit complex and often unexpected wettability that adversely affects flotation efficiency. However, how these serpentine polymorphs differ in surface hydrophobicity is still not well known, making it difficult to explain their distinct flotation behaviors. In this work, molecular dynamics (MD) simulations and experimental contact angle measurements are used to investigate the wettability of the three main serpentine polymorphs. MD simulation results reveal that the contact angles of the lizardite Si–(00$\overline{1}$) surface and Mg–(001) are 78.6° and 71.1°, respectively. Chrysotile exposes the Mg–(001) surface, with a contact angle of 74.9°. The water droplet on the antigorite surface is spread along the SiOH region. Even the Mg–OH-terminated octahedral surfaces of the three serpentine polymorphs can exhibit hydrophobicity, depending on hydroxyl orientation and oxygen bonding configuration. Contact angle measurements show that antigorite (001) is moderately hydrophobic at about 40°, while (020) is highly hydrophilic at about 10°. The combination of Derjaguin–Landau–Verwey–Overbeek (DLVO) theory and hydrophobic interactions between antigorite and air bubbles produces a net attractive force, enabling particle–bubble adhesion. This work provides new insights for controlling serpentine behavior during flotation of copper–nickel ores hosted in ultramafic rocks. Full article

During flotation, the hydration behavior of collector head groups plays an important role in determining collector hydrophilicity and interfacial adsorption behavior. However, although computation-assisted flotation studies have extensively investigated collector–mineral interactions, systematic comparisons of the intrinsic hydration characteristics of different collector head groups under unified computational conditions remain limited. In this work, density functional theory (DFT) calculations using the B3LYP functional with Grimme dispersion correction were conducted to investigate the hydration interactions between water molecules and representative head groups of five sulfide mineral collectors, including xanthate (X), dithiocarbamate (DTC), dithiophosphate (DTP), dithiophosphinate (3418A), and thiocarbamate (Z-200), and five oxide mineral collectors, including oleate (OA), oxidized paraffin soap (OPS–C₁₂), dodecyl sulfonate (DS), styrene phosphonic acid (SPA), and salicylhydroxamic acid (BHA). The results show that oxide mineral collectors exhibit significantly stronger hydration interactions than sulfide mineral collectors. Sulfide collectors mainly form weak S···H–O hydrogen bonds with relatively long H-bond distances (2.27–2.61 Å), whereas oxide collectors predominantly form stronger O···H–O hydrogen bonds with shorter distances (1.66–2.24 Å). The total hydration binding energies of sulfide collectors range from −150 to −290 kJ/mol, while those of oxide collectors range from −244 to −491 kJ/mol. Among the studied collectors, SPA exhibits the strongest hydration tendency due to its highly charged phosphonate group, whereas Z-200 shows the weakest hydration interaction. The results indicate that hydration behavior is strongly influenced by head group type, charge state, and hydrogen-bond characteristics. Full article

To clarify the hydrocarbon-generation potential of deep source rocks in the Qingyang Gas Field, this study focuses on the Shanxi and Taiyuan Formation source rocks at burial depths of 4000–5000 m. Integrated organic geochemical analyses were conducted to investigate organic matter abundance, kerogen type, thermal maturity, hydrocarbon-generation conditions, and their significance for natural gas accumulation. The TOC values of the 12 valid mudstone samples range from 0.07% to 2.53%, with an average of 0.77%, indicating generally poor to fair organic matter abundance. Rock-Eval results show that S2 values range from 0.0681 to 6.2797 mg/g, with an average of 1.5946 mg/g, whereas S1 + S2 values range from 0.0948 to 6.9066 mg/g, with an average of 1.8582 mg/g, indicating generally limited Rock-Eval hydrocarbon-generating capacity, with local improvement. The kerogen assemblage is heterogeneous and is generally dominated by Type III humic kerogen, with subordinate Type II components and minor Type I components in some samples, indicating mixed organic-matter input but an overall gas-prone character. Tmax values range from 420 to 482 °C; however, because Tmax may be unreliable in samples with very low S2 values, thermal maturity was evaluated mainly using vitrinite reflectance and natural gas geochemical evidence. R_o values range from 2.03% to 2.22%, with an average of 2.11%, indicating that the source rocks have reached a high- to overmature stage. The natural gas is methane-rich, with an average methane content of 91.73% and an average heavy hydrocarbon content of only 0.16%, indicating a typical dry-gas composition. The carbon isotope values of methane and ethane are both negative, with δ¹³C₁ values ranging from −35.59‰ to −20.65‰ and δ¹³C₂ values ranging from −37.82‰ to −28.44‰, consistent with high-maturity coal-derived gas generated from humic organic matter. The formation water is mainly medium- to high-salinity CaCl₂ type, indicating a relatively closed hydrologic environment favorable for natural gas preservation. Clay mineral assemblages dominated by kaolinite and illite provide supplementary evidence for depositional conditions, burial diagenesis, and fluid–rock interaction. Overall, although the Rock-Eval hydrocarbon-generating capacity of the Shanxi and Taiyuan Formation source rocks is generally limited, the Type III-dominated mixed kerogen, high- to overmature R_o values, methane-rich dry-gas composition, and carbon isotope characteristics collectively indicate that these source rocks experienced effective natural gas generation during geological evolution and are genetically related to the present deep natural gas accumulation. This study provides fundamental geochemical constraints for further integrated exploration and evaluation of the deep coal-measure gas system in the Qingyang Gas Field. Full article

Calcium carbide slag is a highly alkaline solid waste generated during acetylene production, but its long-term accumulation causes land occupation and persistent environmental risks such as soil alkalinization and water pollution. To support circular economy and carbon emission reduction goals, in this study, we develop an integrated physical decontamination–mineralization process combining calcination, magnetic separation, sedimentation, and CO₂ mineralization. After calcination, magnetic separation, and 8 h of gravity sedimentation, the removal efficiency of Si reaches about 67% (residual Si content reduces to 0.43%), while those of Fe and Al are 75.4% and 74.2%, respectively. The purified calcium-rich slurry is then used for CO₂ mineralization. Under a solid-to-liquid ratio of 10% and a CO₂ flow rate of 0.4 L/min, CO₂ is fixed as carbonate solids, yielding calcite-type CaCO₃ with 97.88% ± 0.35% purity. This process is centered on physical separation and uses no acids, alkalis, or ammonium salts, avoiding secondary pollution while achieving waste valorization and permanent CO₂ sequestration. In this study, we provide a scalable, low-impact pathway for alkaline solid waste valorization and carbon emission reduction, contributing to sustainable consumption and production (SDG 12) and climate action (SDG 13). Full article

Continuous discharges from diverse industrial activities have severely degraded the water quality of the Lerma River, turning it into a major environmental, social, and public health concern. Conventional wastewater treatment processes are often insufficient for eliminating persistent and refractory organic pollutants; therefore, the implementation of advanced oxidation processes (AOPs) is increasingly required to restore water quality. In this context, the present study systematically evaluated the individual and combined effects of ozonation and electrochemical oxidation using boron-doped diamond (BDD) electrodes for the treatment of contaminated river water. Ozonation alone achieved an 89% reduction in turbidity and a 19% decrease in total organic carbon (TOC), while electrochemical oxidation reduced turbidity by 82% and TOC by 57%. Remarkably, the simultaneous application of both treatments resulted in a 98% reduction in turbidity and an 80% decrease in TOC, clearly demonstrating a strong synergistic effect. Regarding true color at 436 nm, associated with yellow chromophore compounds, removal efficiencies of 98.9%, 94.7%, and 67.3% were obtained for the combined process, electrochemical oxidation, and ozonation, respectively. Phytotoxicity tests with Lactuca sativa seeds showed no statistically significant difference in toxicity in water treated with the O₃–EO System compared to raw water. These results highlight, for the first time under real river water conditions, the superior performance of the integrated O₃–EO system as an effective strategy for the intensified degradation and partial mineralization of persistent organic contaminants, thereby underscoring its strong potential for advanced remediation of heavily polluted surface waters. Full article

The soil of Siraitia grosvenorii (LHG) farmland often suffers from acidification, compaction, and declining organic matter content. As biochar helps improve soil quality and enhance soil carbon sequestration capacity, an increasing number of studies are utilizing biochar for soil quality improvement. To address the soil degradation problem in LHG farmland and achieve the goals of soil organic carbon (SOC) sequestration and nutrient increase, we conducted a 100-day indoor constant-temperature incubation experiment by adding different proportions of LHG vine biochar. We analyzed the changes in SOC mineralization, different carbon fractions, and soil nutrient content in LHG farmland. The main results showed that, compared with the control group, the cumulative mineralization (CumulMine) of SOC increased by 3% to 51%, and organic carbon content increased by 52.43% to 193.87%. As the LHG vine biochar application rate increased, the metabolic entropy (qCO₂) rose, whereas the microbial entropy (qMBC) showed an opposite trend. Similarly, compared with the control group, the addition of 1.0%, 2.0%, and 4.0% LC increased water-soluble organic carbon by 45.87 mg·kg⁻¹, 67.00 mg·kg⁻¹, and 81.73 mg·kg⁻¹, respectively, and soil nutrients also increased, but microbial biomass carbon (MBC) and readily oxidizable organic carbon (ROC) contents decreased. The main conclusions indicate that adding LHG vine biochar increases SOC content, which is associated with reduced microbial activity. Biochar-derived DOC may serve as a substrate for microbial respiration, thereby contributing to increased CO₂ release and accelerated nutrient release. The application of LHG vine biochar enhanced the carbon sequestration capacity of LHG farmland soil while improving soil nutrient content, with the 4% application rate treatment performing the best. Full article

Iron-exchanged bentonites derived from a natural montmorillonite-rich clay (Taganskoe deposit, Kazakhstan) were prepared through a simple aqueous ion-exchange route using Fe(II) or Fe(III) inorganic salt precursors, yielding final Fe contents of ca. 5–7 wt.%, while preserving the smectite layered framework. A mild thermal treatment under air was applied to tune iron coordination without triggering major structural collapse. The resulting materials were characterized by ED-XRF, PXRD, FE-SEM/EDX, DLS/ζ-potential and DR UV–Vis–NIR spectroscopy, revealing predominantly exchanged Fe species with a limited fraction of surface iron-oxide clusters, whose contribution increases after activation. Structure–reactivity relationships were probed under mild conditions in liquid-phase ethyl acetate using dimethyl methylphosphonate (DMMP) and 2-chloroethyl ethyl sulfide (2-CEES) as organophosphorus and organosulfur hazardous chemicals and chemical warfare agent simulants, respectively. Fe(III)-bentonite enabled very fast DMMP removal (ca. 93% within 0.5 h) with a remarkable improved performance with respect to Fe(II)-bentonite and the pristine mineral clay. For 2-CEES, the presence of H₂O₂ markedly enhanced oxidation on Fe-containing clays, reaching quantitative abatement within 24 h (up to >90%), with strong retention of oxidized sulfur products by the clay matrix. These results highlight Fe-exchanged natural bentonites as robust, cheap and multifunctional adsorption/catalytic solids for decontamination and water-treatment applications. Full article