Search Results (27,067)

A prerequisite for the efficient utilization of water and fertilizer in the traditional ridge farming model in the black soil region of Northeast China is the precise elucidation of the small-scale temporal and spatial characteristics of rainfall infiltration and redistribution. However, the existing research findings have yet to fully satisfy this requirement. To investigate soil water infiltration and redistribution at different positions (ridge bed, ridge side, and furrow) before ridge closure in ridge-furrow crops within the black soil regions of Northeast China, indoor simulation experiments and field natural rainfall monitoring were conducted. The indoor test involved rainfall settings of 12, 16, 20, 24, and 30 mm with a rain intensity of 90 mm/h. Field monitoring recorded a natural rainfall intensity of 56 mm/h lasting 22.5 min, with cumulative rainfall reaching 21 mm (randomly measured), to analyze the process of soil water movement post-rainfall. Results indicated that under conventional ridge planting in black soil areas, prior to ridge bed coverage, the infiltration amounts for ridge bed, ridge side, and furrow under 16 mm rainfall conditions equaled the rainfall itself, with ratios close to 1:1:1, showing no significant redistribution of precipitation during infiltration. For rainfall levels of 20 mm, 24 mm, and 30 mm, the ratios of infiltration to rainfall at the ridge bed, ridge side, and furrow positions were 0.92:1.03:1.04, 0.90:1.03:1.06, and 0.89:1.04:1.09, respectively. When rainfall exceeded 20 mm, the infiltration-to-rainfall ratio was approximately 0.9 and 1.04, respectively. Approximately 10% of the rainfall on the ridge platform migrated to the ridge side via splash and runoff, increasing the water volume at the ridge side by about 4%. For rainfall less than 24 mm, the ridge bed, ridge side, and furrow reached a stable state after approximately 50 min of infiltration and redistribution. For rainfall between 24 mm and 30 mm, the ridge platform stabilized within 50 min, whereas the ridge side and furrow required longer stabilization times. These findings elucidate the spatial variation laws of small-scale rainfall infiltration, providing insights for enhancing soil water and fertilizer utilization efficiency. Full article

Flood events have become more frequent as a result of seasonal changes, global warming, and changes in sea level. In terms of basin management, it is necessary to know the hydrodynamics of the basin in order to produce faster solutions in emergency action plans. The Filyos River is one of the two most important floodplains in the western Black Sea basin and has so far only been analyzed to a limited extent using modern hydrological and hydraulic models. In order to analyze the flood dynamics and determine the flood risks in the Filyos River. In this context, flood hydrographs, rainfall depths, peak flows, and excess water volumes were calculated for different return periods (2, 5, 10, 20, 50, and 100 years) using HEC-RAS, HEC-HMS, and Hyfran Plus software. The analyses showed that the rainfall depth and peak flow rate increased significantly as the return period increased. It was also observed that although the volume of precipitation increased, the amount of water converted into surface runoff remained limited due to infiltration and other losses. The results of the study contribute to the identification of high flood-risk areas in the Filyos River basin, the improvement of flood prevention infrastructure, and the development of sustainable water management policies. Analyses using modeling tools such as HEC-RAS and HEC-HMS provide a scientific basis to help local governments and decision makers strengthen flood prevention strategies, update risk maps, and make emergency response plans more effective while making flood scenarios more reliable. Full article

Ammonium nitrate (NH₄NO₃) is a major constituent of fine particulate matter (PM_2.5), playing a critical role in air quality and atmospheric chemistry. However, the dual regulatory role of ammonia (NH₃) in both the formation and volatilization of NH₄NO₃ under ambient atmospheric conditions remains inadequately understood. To address this gap, we conducted high-resolution field measurements at a clean tropical coastal site in China using an integrated system of Aerosol Ion Monitor-Ion Chromatography, a Scanning Mobility Particle Sizer, and online OC/EC analyzers. These observations were complemented by thermodynamic modeling (E-AIM) and source apportionment via a Positive Matrix Factorization (PMF) model. The E-AIM simulations revealed persistent thermodynamic disequilibrium, with particulate NO₃⁻ tending to volatilize even under NH_3gas-rich conditions during the northeast monsoon. This suggests that NH₄NO₃ in PM_2.5 forms rapidly within fresh combustion plumes and/or those modified by non-precipitation clouds and then undergoes substantial evaporation as it disperses through the atmosphere. Under the southeast monsoon conditions, reactions constrained by sea salt aerosols became dominant, promoting the formation of particulate NO₃⁻ while suppressing NH₄NO₃ formation despite ongoing plume influence. In scenarios of regional accumulation, elevated NH₃ concentrations suppressed NH₄NO₃ volatilization, thereby enhancing the stability of particulate NO₃⁻ in PM_2.5. PMF analysis identified five source factors, with NO₃⁻ in PM_2.5 primarily associated with emissions from local power plants and the large-scale regional background, showing marked seasonal variability. These findings highlight the complex and dynamic interplay between the formation and evaporation of NH₄NO₃ in NH_3gas-rich coastal atmospheres. Full article

Understanding how elevation gradients and soil depths influence soil organic carbon stocks (SOCS) and total nitrogen stocks (TNS) is essential for sustainable forest management (SFM) and climate change mitigation. This study investigated the effects of elevation and soil depth on SOCS and TNS in the Mount Kenya East Forest (MKEF). A stratified systematic sampling approach was applied, involving collection of 38 soil samples from two depths (0–20 cm and 20–40 cm) across three elevation zones: Lower Forest (1700–2000 m), Middle Forest (2000–2350 m), and Upper Forest (2350–2650 m). Samples were analysed for bulk density (BD), pH, texture, soil organic carbon (SOC), and total nitrogen (TN), using standard laboratory methods. In topsoil (0–20 cm), SOCS ranged from 109.28 ± 23.41 to 151.27 ± 17.61 Mg C ha⁻¹, while TNS varied from 8.89 ± 1.77 to 12.00 ± 2.46 Mg N ha⁻¹. In subsoil (20–40 cm), SOCS ranged from 72.03 ± 19.90 to 132.23 ± 11.80 Mg C ha⁻¹, with TNS varying between 5.71 ± 1.63 and 10.50 ± 1.90 Mg N ha⁻¹. SOCS and TNS increased significantly with elevation (p < 0.05), exhibiting the following trend: Lower Forest < Middle Forest < Upper Forest. Topsoil consistently stored significantly higher SOCS than subsoil (p < 0.05), emphasizing the critical role of surface soils in carbon sequestration. Regression analysis revealed a significant positive relationship between SOCS and TNS (R² = 0.84, p < 0.001). Both SOCS and TNS were positively correlated with elevation, SOC, TN, and total annual precipitation (TAP), but negatively correlated with BD and mean annual temperature (MAT). These findings provide baseline data for monitoring SOCS and TNS in the MKEF, offering insights into sustainable forest management strategies to improve soil health and enhance climate change mitigation efforts. Full article

Biochar is considered a promising amendment for improving phosphorus (P) availability in agricultural soils; however, its effects on the chemical transformation and long-term immobilization of P in submerged soils across soil depth and over time remain unclear. This study conducted a 98-day column incubation experiment to investigate the effects of rice straw biochar (RSB) on the spatial and temporal dynamics of iron (Fe) and P under soil submergence. Soils with and without biochar addition were mixed with water homogeneously and then added into each PVC column with an additional standing water layer above the soil surface. The results revealed a two-stage shift in soil redox potential (Eh), with more rapid changes observed at deeper depths. RSB addition accelerated the decline in Eh and increased the soil pH. The rise in pH by submergence and biochar addition promoted the release of soluble and exchangeable P from soil to pore water during incubation. Ca-associated P precipitation and re-adsorption resulted in relatively low phosphate concentrations in pore water. RSB addition increased P availability in the early stage by releasing soluble and exchangeable P and promoting phosphate desorption through pH elevation, which increased the negative surface charge of soil constituents, thereby reducing their affinity for phosphate and enhancing its release into the pore water. However, prolonged submergence led to the transformation of soluble and exchangeable P into more stable Ca-P precipitates, limiting long-term P availability. These findings provide new insights into the temporal and spatial dynamics of P in submerged soils and highlight the short-term benefits and long-term limitations of biochar for sustaining P availability in paddy rice systems. Full article

Understanding the nonlinear relationship between human activity intensity (HAI) and ecosystem resilience (ER) is crucial for sustainability, yet underdeveloped areas are often overlooked. This study examines the Xuzhou Urban Agglomeration (XZUA) from 2012 to 2022, creating a framework to assess both ER and HAI. Both frameworks utilize multi-source datasets, such as remote sensing, statistical yearbooks, and geospatial data. The ER framework uniquely combines dynamic and static indicators, while the HAI framework differentiates explicit and implicit human activity dimensions. We used spatial analysis, the Optimal Parameter Geodetector (OPGD), and Multi-Scale Geographically Weighted Regression (MGWR) to examine the nonlinear spatiotemporal interaction between HAI and ER. Results show the following: (1) ER exhibited a “shock-recovery” pattern with a net decline of 3.202%, while HAI followed a nonlinear “rise-fall” trend with a net decrease of 0.800%. (2) Spatial mismatches between HAI and ER intensified over time. (3) The negative correlation in high-HAI regions remained stable, whereas neighboring low-HAI areas deteriorated, indicating a spillover effect. (4) OPGD identified the change in HAI (Sen’s slope) as the primary driver of ER change (q = 0.512), with the strongest interaction observed between HAI Sen’s slope and precipitation (q = 0.802). (5) Compared to HAI intensity (mean), its temporal variation had a more spatially stable influence on ER. These findings offer insights for ecological management and sustainable planning in underdeveloped regions, highlighting the need for targeted HAI and ER interventions. Full article

This study explores the influence of two different synthesis methods on the sintering behavior of three novel high-entropy oxides possibly suitable for thermal barrier applications: (Ce_0.2Zr_0.2Yb_0.2Er_0.2Nd_0.2)O_2-d, (Ce_0.2Zr_0.2Yb_0.2Er_0.2La_0.2)O_2-d, and (Ce_0.2Nd_0.2Yb_0.2Er_0.2La_0.2)₂O_3+d. Rare-Earth-based High-Entropy Oxides (RE-HEOs), recently known for their exceptional thermal stability and compositional flexibility, have gained increasing attention as potential candidates for many advanced technological applications. Thus, our current work focuses on the specific effects of synthesis techniques, namely co-precipitation and hydrothermal treatment, on the entropy-driven stabilization, microstructure, electrochemical properties, and sintering behavior of three novel RE-HEOs. The obtained results reveal significant differences in terms of densification yield and of the obtaining of the designed entropy-stabilized single phase depending on the adopted synthesis route, underscoring the critical role of synthesis in optimizing RE-HEOs for near-future technological applications. Full article

Cohesive soil in the reservoir area is vulnerable to natural disasters because of its poor erosion resistance and low strength. Therefore, it needs to be reinforced. Microbially induced calcium carbonate precipitation (MICP) is a sustaibable soil reinforcement technique with low energy consumption and no pollution. Different combinations of Bacillus subtilis bacterial solution (BS) concentrations and cementing solution (CS) concentrations were set to perform MICP solidification treatment. The characterization of cohesive soil before MICP was carried out by means of Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), and Laser Particle Size Analyzer (LPSA). The results showed that the unreinforced soil showed an amorphous state with low strength and the particle size distribution was dominated by powder particles. However, with the addition of BS concentrations and CS concentrations, SEM results showed that spherical and rhombohedral minerals filled the pores of the cohesive soil, which increased the content of precipitations and enhanced the cementitious characteristics. When the concentrations of CS or BS were fixed, CaCO₃ content, deviatoric stress, shear strength, cohesive force, and internal friction angle all showed a trend of first increasing and then decreasing with the increase in CS or BS concentration. The optimal combination of CS and BS concentration was 1.5 mol/L and OD₆₀₀ = 1.8. Thermochemical analyses showed an improved thermal stability of the reinforcing cohesive soil, with the lowest mass loss (32%) and the highest pyrolysis temperature (812 °C) of the samples at the optimal combination of BS and CS concentration. This study is expected to improve the understanding of the MICP reinforcement process and contribute to the optimal design of future biologically mediated soil amendments, promoting bioremediation. Full article

Background and Objectives: Extracellular vesicles (EVs) derived from mesenchymal stem cells have gained much attention as potential therapeutic agents in many diseases, including hearing disorders such as sensorineural hearing loss (SNHL). EVs inherit similar therapeutic effects, including the stimulation of tissue regeneration from the parental cells. The aim of our study was to isolate EVs produced by MSCs and use them to treat inner ear cells in culture to evaluate their protective potential against the damaging effect of an ototoxic drug. Materials and Methods: We isolated MSC-derived EVs by precipitation and characterized them by number, size, and morphology using nanoparticle tracking analysis and TEM, evaluated the protein concentration by BCA assay and the presence of EV markers CD9, CD63, and CD81 by the Dot Blot immunoblotting method. HEI-OC1 inner ear cell line was treated with EVs either alone or followed by Cisplatin. We assessed the uptake of EVs in HEI-OC1 cells by fluorescence microscopy after PKH26 labeling, ROS production by the DCFDA (dichlorfluorescein diacetate) assay, cellular viability by Alamar Blue assay, and apoptosis with the Annexin V/Propidium Iodide method. Results: The isolated EVs had mean dimensions of 184.4 nms and the concentration of the EV suspension was 180 × 10⁶ particles/mL. TEM analysis showed intact vesicular structures with lipid-bilayer membranes having similar sizes with those measured by NTA. The PKH26-labeled EVs were observed in the HEI-OC1 cells after 24 h incubation, the amount increasing with the concentration. EVs reduced ROS production and increased the number of viable cells both alone and as pretreatment before Cisplatin, dose-dependently. Cells in early apoptosis were inhibited by EVs, while those in late apoptosis were enhanced, both with and without Cisplatin. Conclusions: EVs secreted by MSC protected HEI-OC1 cells against Cisplatin toxicity, reduced ROS production, and stimulated cell viability and the elimination of damaged cells by apoptosis, protecting the HEI-OC1 cells against Cisplatin-induced damage. Full article

The design of efficient and stable visible-light-driven photocatalysts is paramount for sustainable hydrogen (H₂) evolution and the degradation of organophosphorus pesticides, exemplified by dichlorvos (DDVP). In this work, we synthesized a co-catalyst-free nanocomposite photocatalyst composed of Al₆Si₂O₁₃ (ASO) and Cd_8.05Zn_1.95S₁₀ (ZCS). By constructing a Type-I heterojunction, the optimized ASO/ZCS-1 nanocomposite (ASO loading ratio: 30%) enhanced visible-light-driven H₂ evolution activity (5.1 mmol g⁻¹ h⁻¹), nearly doubling that of pristine ZCS (2.7 mmol g⁻¹ h⁻¹). Stability assessments revealed catalytic durability for ASO/ZCS-1 over five successive cycles, whereas the activity of pure ZCS precipitously declined to 59.7% of its initial level. Additionally, ASO, ZCS, and ASO/ZCS-2 (ASO loading ratio: 50%) demonstrated notable photocatalytic efficiency toward DDVP degradation without any co-catalyst, reducing DDVP concentration to 56.2% (ASO), 18.9% (ASO/ZCS-2), and 38.4% (ZCS), with corresponding degradation stability of 93.8%, 95.1%, and 93.8%, respectively. These results underscore the superior photocatalytic activity and stability of ASO, ZCS, and ASO/ZCS in the remediation of organophosphorus pesticides, with the Type-I heterojunction structure of ASO/ZCS enhancing both degradation activity and stability. Comprehensive characterizations by X-ray photoelectron spectroscopy (XPS), ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS), and differential charge density analyses verified the Type-I heterojunction charge-transfer mechanism, effectively suppressing charge recombination and thus improving photocatalytic performance. Consequently, ASO/ZCS nanocomposites exhibit significant promise for broad applications in sustainable H₂ production, pollutant degradation, and ensuring food and agricultural product safety. Full article

Climate change, marked by decreasing rainfall and increasing extreme events, represents a major challenge for water resources, particularly in semi-arid regions. To estimate aquifer recharge, it is essential to assess the fraction of precipitation contributing to groundwater recharge and to implement a water balance model. However, the limited number of rainfall stations has led researchers to rely on satellite and reanalysis rainfall products. The accuracy of these datasets is essential for reliable hydrological modeling. In this study, we evaluated five rainfall products—CHIRPS, ERA5_Ag, CFSR, GPM, and PERSIANN-CDR—by comparing them to ground measurements from gauging stations in the central Haouz region of Marrakech. The evaluation was conducted at three temporal scales: daily, monthly, and annual. Statistical metrics, including RMSE, MAE, NSE, Bias, and Pearson correlation, as well as classification metrics (accuracy, F1 score, recall, precision, and Cohen’s Kappa), and wavelet analysis, were applied to assess the accuracy of the products. The results identified ERA5_Ag and GPM as the most accurate products in capturing rainfall events. Nevertheless, ERA5_Ag showed a high bias. After applying the quantile mapping method to correct the bias, the product exhibited greater accuracy. The corrected datasets from these two products will be used to estimate recharge over the last 30 years, contributing to the development of a hydrogeological model for groundwater dynamics. Full article

Diclofenac (DCF), a widely consumed non-steroidal anti-inflammatory drug, presents significant environmental challenges due to its persistence and toxicity in aquatic ecosystems. This study investigates the pH-dependent ozonation of DCF in aqueous media, focusing on degradation kinetics, transformation pathways, and effects on key water quality indicators. Ozonation experiments were conducted across a broad pH range (2.0–13.0), using a multi-scale analytical approach combining UV/Vis spectroscopy, colorimetry, turbidity, and aromaticity measurements. The results show that pH strongly influences DCF degradation efficiency: acidic conditions favor selective reactions with molecular ozone, while an alkaline pH enhances non-selective oxidation via hydroxyl radicals. Spectroscopic analyses revealed the progressive breakdown of aromatic structures, the transient formation of quinonoid and phenolic intermediates, and eventual mineralization to inorganic by-products such as nitrate. Low-pH conditions also induced turbidity due to precipitation of neutral DCF species. These findings underline the importance of pH control in optimizing ozonation performance and minimizing toxic by-products. Furthermore, this study proposes ozonation as a viable pre-treatment step within Nature-Based Solutions (NBSs), potentially improving the performance of downstream biological systems such as constructed wetlands. The results contribute to the development of integrated and sustainable water treatment strategies for pharmaceutical contaminant removal and water reuse. Full article

The possible incorporation of Al and Zn issuing from galvanic anodes in the calcareous deposit forming on carbon steel surfaces subjected to cathodic protection was studied via three methodological approaches. The calcareous deposits were analyzed by X-ray diffraction for phase composition and X-ray fluorescence spectroscopy for chemical composition. First, a calcareous deposit formed on the steel pile of a seaport installation, sampled far (2 m) from the closest galvanic anode, was found to incorporate a small amount of the pollutants present in the seawater (Zn, Ti, Cu). An in situ experiment performed at another seaport focused on the calcareous deposit formed on steel surfaces close to the anode. In this case, a small amount of Zn directly issuing from the anode was incorporated in the deposit. This amount remained low as it corresponded to Zn(II) species adsorbed on the surface of aragonite crystals. Finally, laboratory experiments were performed with Zn(II) and/or Al(III) chlorides (10⁻³ mol L⁻¹ each) added to seawater. With both Zn(II) and Al(III), a Zn(II)-Al(III) hydroxychloride precipitated in the bulk seawater. With only Al(III), and under a higher cathodic current density, Al(III) could be incorporated in a deposit mainly composed of brucite, but only in small amount. Full article

Various forms of alumina have attracted considerable attention for their ability to remove anionic dyes from wastewater, attributed to their high specific surface area, and environmental safety. In this study, a series of modified alumina materials were synthesized for the first time using the reverse precipitation method with dual aluminum sources and without template agent to explore their applicability in various scenarios, including adsorption processes and regeneration cycles. The results revealed that non-modified alumina exhibited superior adsorption properties, while silicon-modified alumina demonstrated exceptional thermal stability during high temperature calcination. For silicon-modified alumina, the replacement of some Al–OH groups with silicon resulted in the formation of a protective silicon layer on the alumina surface, which delayed the sintering process. The pseudo-second-order kinetic model and Langmuir model were utilized to fit the experimental data. Furthermore, the adsorption and regeneration properties of silicon-modified alumina were investigated, revealing a maximum equilibrium adsorption capacity of 822.6 mg/g for Congo Red using non-modified alumina. Notably, the non-modified alumina demonstrated a 40.6% increase in its adsorption capacity compared to its initial capacity after six regeneration cycles at 1000 °C. Full article

Brine purification is an important process unit in chlor-alkali industrial plants for the production of sodium hydroxide, chlorine, and hydrogen. The membrane cell process requires ultrapure brine, which is obtained through mechanical filtration, chemical precipitation and fine polishing, and ion exchange using polymer resins. Temperature variations can lead to the degradation of the exchange properties of these resins, primarily causing a decrease in their exchange capacity, which negatively impacts the efficiency of the brine purification. After multiple ion exchange regeneration cycles, significant quantities of spent resins may be generated. These must be managed in accordance with resource efficiency and hazardous waste management to ensure the sustainability of the industrial process. In this paper, a comparative study is conducted to characterize the long-term stability of a new commercial chelating resin used in the industrial electrolysis process. The spectroscopic methods of physicochemical characterization included: scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR). The thermal behavior of the polymer resins was evaluated using the following thermogravimetric methods: thermogravimetry (TG), derivative thermogravimetry (DTG), and differential thermal analysis (DTA), while the moisture behavior was studied using dynamic vapor sorption (DVS) analysis. To assess the energy potential, the polymer resins were analyzed to determine their calorific value and overall energy content. Full article