Search Results (2,531)

To investigate the effects of long-term elevated atmospheric CO₂ (eCO₂) on the distribution and stability of soil aggregates and microbial characteristics in wetland soils and to reveal the mechanisms by which eCO₂ influences soil organic carbon (SOC) sequestration, a multi-temporal-scale eCO₂ control experiment was conducted in the Sanjiang Plain wetland with treatments at ambient CO₂ concentration (AC), 550 ppm, and 700 ppm CO₂. Soil aggregate fractionation, phospholipid fatty acid (PLFA) analysis, and redundancy analysis (RDA) were used to analyze changes in aggregate size distribution, stability indices (MWD, GMD), microbial biomass, and community structure. The results showed that eCO₂ significantly affected aggregate size distribution. Both short- and long-term exposure to low-concentration eCO₂ reduced the proportion of large aggregates. Over time, the proportion of silt and clay particles increased, while microaggregates decreased. Although CO₂ concentration did not directly affect MWD and GMD, long-term eCO₂ significantly reduced soil aggregate stability. Microbial biomass and diversity were not sensitive to CO₂ concentration but decreased significantly with prolonged exposure. In contrast, microbial community structure was significantly affected by both CO₂ level and exposure duration. RDA indicated that, under short-term eCO₂, aggregate fractions were positively correlated with microbial biomass, whereas, under medium- and long-term treatments, they were positively correlated with soil physicochemical properties. Macroaggregates were positively correlated with aggregate stability, while microaggregates and silt–clay fractions were negatively correlated—a relationship that strengthened with longer eCO₂ exposure. Thus, long-term eCO₂ altered soil aggregate structure and microbial communities, ultimately influencing SOC stability. These findings provide data and theoretical support for predicting soil carbon stability and ecosystem functioning in wetlands under climate change. Full article

The continuous-cropping obstacles of Pogostemon cablin (patchouli) is severely constrained by autotoxic phenolic acids accumulated in the rhizosphere soil. Biochar adsorption and chemical oxidation are common remediation strategies; they often fail to simultaneously and efficiently remove phenolic allelochemicals while improving the soil micro-ecological environment. To address this issue, this study developed a novel biochar–urea peroxide composite particle (BC-UP). Batch degradation experiments and electron paramagnetic resonance (EPR) analysis confirmed the synergistic adsorption-oxidation function of BC-UP. A pot experiment demonstrated that application of BC-UP (5.0 g/kg) significantly alleviated phenolic acid stress. Specifically, BC-UP application significantly enhanced shoot biomass by 28.8% and root surface area by 49.3% compared to the phenolic acid-stressed treatment and concurrently reduced the total phenolic acid content in the rhizosphere soil by 37.3%. This growth promotion was accompanied by the enhanced accumulation of key bioactive compounds (volatile oils, pogostone, and patchouli alcohol). BC-UP amendment also improved key soil physicochemical properties (e.g., pH, and organic matter) and enhanced the activities of critical enzymes. Furthermore, BC-UP reshaped the microbial community, notably reducing the fungi-to-bacteria OTU ratio by 49.7% and enriching the relative abundance of Firmicutes and Nitrospirota but suppressing the Ascomycota phylum abundance. Redundancy analysis identified soil sucrase and catalase activity, total phenolic acid content, and Ascomycota abundance as key factors influencing patchouli biomass. In conclusion, BC-UP effectively mitigates phenolic acid stress through combined adsorption and radical oxidation, subsequently improving soil properties and restructuring the rhizosphere microbiome, offering a promising soil remediation strategy for patchouli and other medicinal crops. Full article

Substrate composition plays a vital role in the soilless cultivation of Helleborus; high-quality substrates can create optimal growth conditions and enhance plant quality. However, knowledge regarding suitable substrates for Helleborus remains limited. The aim of the study was to test the effects of different substrates on growth of potted Helleborus × hybridus seedlings. In total, 12 treatments were formulated by mixing organic components (moss peat, cocopeat, domestic peat) with inorganic particles (perlite, kanuma soil, vermiculite) at a 1:1 ratio, using moss peat moss as the control. The results indicated that substrates of moss peat + vermiculite (1:1) and cocopeat + vermiculite (1:1) significantly promoted plant height, shoot number, leaf number, and root development. The treatment with domestic peat + perlite + kanuma soil + vermiculite (3:1:1:1) yielded the highest soluble protein content, whereas the CK group showed the highest soluble sugar content. A comprehensive evaluation by Principal Component Analysis (PCA) identified moss peat + vermiculite (1:1) as the optimal substrate, followed by coir + vermiculite (1:1). Considering economic costs and environmental protection factors, the cocopeat + vermiculite (1:1) mixture demonstrated superior potential. Collectively, our study clarifies the effects of different substrate compositions and provides new insights for achieving cleaner and more efficient soilless cultivation of Helleborus. Full article

Accurate numerical prediction of particle–tool interaction requires validation methods that closely reflect the complexity of real operating conditions. This study introduces a comprehensive methodology for validating the motion of particulate material modeled using the Discrete Element Method (DEM) under field-like conditions, with experimental measurements conducted directly during agricultural processing. The proposed framework integrates image analysis with manual extraction of experimental particle trajectories, providing an efficient, flexible, and cost-effective validation approach. A multilayer perceptron artificial neural network (ANN) trained on 94,939 calibration samples was employed to transform pixel coordinates from two synchronized cameras into 3D spatial positions. To the best of the authors’ knowledge, this represents the first application of an ANN-based trajectory reconstruction method under laboratory soil-channel conditions that replicate field-representative geometry and operating velocities. Experiments were conducted in a laboratory soil channel using a full-scale agricultural chisel operating at 1.0 and 1.5 m·s⁻¹, corresponding to realistic tillage velocities. The ANN achieved excellent accuracy (R² = 0.9994, 0.9993, and 0.9988 for the X-, Y-, and Z-axes; average deviation 2.7 mm), and the subsequent comparison with DEM simulations resulted in an average nRMSE error of 4.7% for 1 m·s⁻¹ and 9.41% for 1.5 m·s⁻¹. The results confirm that the proposed methodology enables precise reconstruction of particle trajectories and provides a robust framework for the validation and calibration of DEM models under conditions closely approximating real field environments. Full article

Particle size distribution (PSD), also referred to as grain-size distribution (GSD), is a fundamental characteristic of granular materials, influencing packing density, porosity, permeability, and mechanical behavior across soils, sediments, and industrial powders. Accurate and reproducible representation of PSD is essential for computational modeling, digital twin development (i.e., virtual replicas of physical systems), and machine learning applications in geosciences and engineering. Despite the widespread use of classical distributions (log-normal, Weibull, Gamma), there remains a lack of systematic frameworks for generating synthetic datasets with controlled statistical properties and reproducibility. This paper introduces a unified computational framework for generating virtual PSDs/GSDs with predefined statistical characteristics and a specified number of grain-size fractions. The approach integrates parametric modeling with two histogram-based allocation strategies: the equal-width method, maintaining uniform bin spacing, and the equal-probability method, distributing grains according to quantiles of the target distribution. Both methods ensure statistical representativeness, reproducibility, and scalability across material classes. The framework is demonstrated on representative cases of soils (Weibull), sedimentary and industrial materials (Gamma), and food powders (log-normal), showing its generality and adaptability. The generated datasets can support sensitivity analyses, experimental validation, and integration with discrete element modeling, computational fluid dynamics, or geostatistical simulations. Full article

The rapid growth in manufacturing and use of electrical and electronic equipment has led to unprecedented volumes of poorly managed e-waste, posing serious ecological risks. Although data on individual chemical substances in e-waste are available, evidence of ecotoxicity from actual e-waste materials remains scattered. This review consolidates organism-level ecotoxicity data on real e-waste samples (mixed fractions, fragments, leachates) and samples collected near e-waste facilities (soil, sediments, dust, water) across aquatic and terrestrial environments. It critically examines how methodological approaches influence reported outcomes and outlines research priorities. In aquatic environments, toxic responses vary with increased amounts of toxicants (dissolved metals, particles from dismantling operations) that mobilise to surface waters, while hydrophobic organic compounds cause sublethal behavioural and genotoxic effects. The few studies on terrestrial environments show impaired invertebrate growth and reproduction, along with changes in soil and “plastisphere” microbiota. However, tested concentrations, material complexity, and incomplete reporting of exposure chemistry, among other factors, limit the environmental relevance and comparability of the data. Uniformised procedures, combined with thorough chemical characterisation, environmentally realistic conditions, and cross-system bioassays (including different exposure routes and cumulative assessments), may provide mechanistic insights into e-waste toxicity, supporting evidence-based risk management strategies while contributing towards the development and validation of robust new approach methodologies (NAMs). Full article

Against the backdrop of global water scarcity, utilizing sediment-laden river water for agricultural irrigation is a critical strategy for ensuring food security. However, the associated water and nitrogen transport processes are influenced by the coupled effects of multiple factors, and the governing mechanisms are not yet fully understood. To investigate the coupled effects of muddy water sediment concentration (ρ), physical clay content (d_0.01), applied nitrogen concentration (N), and pressure head (H) on infiltration characteristics during film hole irrigation, this study conducted an indoor soil-box experiment using an orthogonal design to analyze soil water and nitrogen transport dynamics. Results indicated that sediment properties were the dominant factors governing infiltration, with their relative influence on cumulative infiltration following the order ρ > d_0.01 > H > N. ρ and d_0.01 strongly inhibited infiltration; for instance, an increase in ρ from 3% to 9% reduced the initial infiltration rate by as much as 49.3%. Conversely, H and N exhibited a slight promoting effect. High muddy water sediment concentration and physical clay content significantly restricted water and nitrogen transport, causing substantial amounts of ammonium nitrogen (NH₄⁺-N) to be retained within the surface soil layer adjacent to the irrigation hole. Paradoxically, the same factors that reduced infiltration (ρ and d_0.01) led to a significant increase in the average change in volumetric water content (Δθ) within the wetted soil volume. Based on these findings, multivariate power function models were developed to predict key parameters. The models demonstrated high predictive accuracy, with coefficients of determination (R²) of 0.9715 for cumulative infiltration, 0.94 for wetting front migration, and 0.9758 for Δθ, and validation errors were within acceptable limits. In conclusion, the film hole irrigation process is predominantly governed by physical clogging from sediment particles, a mechanism that decisively controls the spatial distribution of water and nitrogen. Furthermore, the slight enhancement of infiltration by nitrogen fertilizer suggests a potential physicochemical mechanism, possibly involving ion-induced flocculation of clay particles. The models developed in this study provide a quantitative basis for precision fertigation management in China’s Yellow River irrigation district and other regions with similar conditions. Full article

To address the issue of restricted grout diffusion caused by seepage effects during grouting in sandy soil layers, this study proposes an optimised grouting method for water-based polyurethane-cement composite grout (WPU-CS) under vacuum-pressure synergy. By establishing a porous medium flow model based on the mass conservation equation and linear filtration law, the influence mechanism of cement particle seepage effects was quantitatively characterised. An orthogonal test (L₉(3⁴)) optimised the grout composition, determining the optimal parameter combination as the following: water-to-cement ratio 1.5:1, polyurethane-to-cement ratio 5~10%, magnesium aluminium silicate content 1%, and hydroxypropyl methylcellulose content 0.15%. Vacuum permeation grouting tests demonstrated that compared to pure cement slurry, WPU-CS reduced filter cake thickness by 80%, significantly suppressing the leaching effect (the volume fraction $\delta$ of cement particles exhibited exponential decay with increasing distance $r$ from the grouting end, and the slurry front velocity gradually decreased). Concurrently, the porosity $\varphi$ in the grouted zone showed a gradient distribution (with more pronounced porosity reduction near the grouting end). When vacuum pressure increased from −10 kPa to −30 kPa, slurry diffusion distance rose from 11 cm to 18 cm (63.6% increase). When grouting pressure increased from 20 kPa to 60 kPa, diffusion distance increased from 8 cm to 20 cm (150% increase). The study confirms that synergistic control using WPU-CS with moderate grouting pressure and high vacuum effectively balances seepage suppression and soil stability, providing an innovative solution for efficient sandy soil reinforcement. Full article

This study presents an environmentally friendly alternative to conventional energy-intensive methods for soil improvement by investigating an enzyme-induced active magnesium oxide carbonation (EIMC) technique for the stabilization of gravelly soil. The solidification efficacy and strengthening mechanism of EIMC-treated soil were systematically investigated through a combination of mechanical property tests and microstructural analyses. Results indicate that key mechanical properties—including compressive strength, shear strength, and elastic modulus—were directly proportional to the magnesium oxide (MgO) content. Notably, an 8% MgO content resulted in a 113-fold increase in unconfined compressive strength (UCS) compared to the untreated soil. The strength development stabilized after a five-day curing period. While higher MgO content yielded greater absolute strength, the efficiency of strength gain per unit of MgO peaked at a 4% dosage. Consequently, considering both performance and efficiency, an MgO content of 4% and a curing period of 5 days are recommended as the optimal parameters. The EIMC treatment substantially improved the soil’s mechanical properties, inducing a transition in the failure mode from plastic to brittle, with this brittleness becoming more pronounced at higher MgO concentrations. Furthermore, the treatment enhanced the soil’s water stability. Microstructural analysis revealed that the formation of hydrated magnesium carbonates filled voids, cemented particles, and created a dense structural matrix. This densification of the internal structure underpinned the observed mechanical improvements. These findings validate EIMC as a feasible and effective eco-friendly technique for gravelly soil stabilization. Full article

Land subsidence is the geological hazard caused by natural or human factors, resulting in a regional decrease in ground elevation due to the compression of the surface soil of the earth’s crust, which has brought huge losses to the national economy. The physical model tests were conducted to study the land subsidence induced by triple pumping including Pumping I, Pumping II and Pumping III. A total of 41 LVDTs were installed to monitor the settlement of the ground, and pictures of the front of the model were taken to obtain the section settlement via the particle image velocimetry (PIV) software. On Path 1, the subsidence is −1.40 mm, −1.50 mm, −1.86 mm, and −2.36 mm after Pumping I; it is −3.15 mm, −3.56 mm, −3.45 mm, and −4.57 mm after Pumping II; and it is −1.29 mm, −0.68 mm, −0.86 mm and −1.65 mm after Pumping III. The closer the soil is to the pumping well, the more severe the settlement after pumping. In the confined aquifer, the pore pressure in the soil experiences a process of initial decrease followed by an increase, which is the manifestation of the drawdown cone on pore pressure. In the layered settlement of the soil, compression in the upper and lower clay layers is significant, accounting for the majority of surface subsidence, while the confined aquifer experiences almost no compression. The results can offer a reference for the prevention and control of land subsidence in soft soil areas. Full article

This study investigates the effectiveness of magnesium oxide (MgO) and coal gangue in improving expansive soil roadbeds through wet–dry cycle tests, unconfined compressive strength tests, and direct shear tests. The results demonstrate that coal gangue effectively suppresses non-load-induced swelling rates in expansive soil. At 15% coal gangue content, the unconfined compressive strength peaked at 0.6 MPa. Further incorporation of MgO at 2%, 4%, 6%, 8%, and 10% concentrations showed that 10% MgO significantly enhanced strength to 3.1 MPa, surpassing both the untreated soil (0.07 MPa) and coal gangue-only treatment (0.6 MPa). While wet–dry cycle tests revealed a gradual decrease in strength with repeated cycles, increasing MgO content mitigated this decline, resulting in coal gangue–MgO-stabilized soil with excellent water stability. Scanning electron microscopy revealed MgO-hydrated cementitious materials encapsulating expansive soil particles and connecting coal gangue particles, though fine cracks were observed near coal gangue surfaces. Full article

The agrifood sector produces considerable waste, offering opportunities for sustainable innovation. In the coffee industry, spent coffee grounds (SCG) can be valorized to generate eco-friendly nanomaterials such as nano zerovalent iron (nZVI), widely applied in soil and water remediation. In this study, green nZVIs were synthesized using SCG hydromethanolic extracts and FeCl₃, subsequently characterized, and assessed for cytotoxicity. High-performance liquid chromatography with diode-array detection (HPLC-DAD) was employed to identify hydroxycinnamic acids, caffeine, and trigonelline in the SCG extracts. Preliminary remediation assays were conducted with seven contaminants, with venlafaxine selected for detailed pH and kinetic studies. Characterization of nZVIs included SEM and EDS analyses, which revealed spherical nZVI particles (72–83 nm) composed of carbon (47%), oxygen (34%), and iron (16%). Dynamic light scattering (DLS) measurements indicated the presence of smaller particles (15–23 nm). Thermogravimetric analysis (TG) confirmed a residual mass of about 20% at 1400 °C. Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed phenolic compound incorporation, while X-ray diffraction (XRD) revealed an amorphous structure. The particles exhibited magnetic behavior and showed no cytotoxicity toward MRC-5 and U87 cell lines. Among the tested contaminants, venlafaxine displayed the highest removal efficiency in remediation tests. Compared with chemically synthesized nZVI, the green version exhibited enhanced stability, attributed to the presence of surface-bounded organic matter. Overall, this sustainable and cost-effective approach to produce nZVI from SCG provides an innovative method for waste valorization and environmental remediation. Full article

Desertification erodes arable land and human habitats. Vegetation restoration represents a critical process for improving the quality of sandy land by enhancing soil structure and nutrient cycling. This study aims to investigation how vegetation restoration affects soil physicochemical properties and soil quality. Five vegetated land types were selected (Pinus sylvestris var. mongholica Litv., PS; Amygdalus pedunculata Pall., AP; Salix psammophila, SP; Amorpha fruticosa L., AF; Artemisia desertorum Spreng., AD). Bare sandy land (BS) served as the control. The physicochemical properties of 270 soil samples from three vertical depth intervals (0–10, 10–20, and 20–30 cm) were analyzed. The findings demonstrated that vegetation restoration markedly improved the proportion of finer soil particles (clay and silt) and organic carbon, while the variations in total phosphorus, ammonia nitrogen, and nitrate nitrogen were not significant. To better understand the variations in soil quality in different vegetated lands, a soil quality index (SQI) was developed that considers multiple soil physical and chemical indicator selections and scoring methods. The SQI based on the minimum dataset and linear scoring method better differentiated the soil quality for sandy lands and showed higher values for SP among all five vegetated lands and BS. Improvements in soil quality were closely related to vegetation properties (density and coverage) and litter characteristics (thickness, water content, and total phosphorus content). Restoration strategies for sandy lands should focus more strongly on species selection, taking into account interspecific variations in litter production, physicochemical properties, canopy architecture, and planting density to more effectively improve soil quality. Full article

Suction embedded plate anchors (SEPLAs) are widely used in offshore engineering, but their keying process is often accompanied by embedment loss, which reduces the holding capacity. To minimize embedment loss, inwardly rotating keying flaps have been introduced, though their kinematics and effects on embedment loss remain insufficiently understood. In this study, transparent soil model tests, combined with particle image velocimetry (PIV), were conducted to directly visualize the keying behavior of SEPLAs with inwardly rotating keying flaps. Five anchor configurations were tested, including a reference model without flaps and four models with flap lengths ranging from 0.2 to 0.5 times the anchor breadth. The results show that inwardly rotating keying flaps significantly reduce embedment loss, with the configuration featuring a flap length of 0.4 times the anchor breadth exhibiting the optimal performance. The findings provide valuable insight into the influence of flap length on SEPLA keying behavior and embedment loss, offering practical guidance for optimizing flap design. Full article

The rise in greenhouse gases underscores the urgency of carbon dioxide removal (CDR) as a complement to emission reductions. Enhanced rock weathering (ERW) holds promise by coupling geochemical carbon sequestration with agronomic benefits, although integrative experimental evidence remains limited. This study evaluated two amendments (recycled concrete in wheat, C₃, and basalt in maize, C₄) under ambient and elevated CO₂ conditions (~1000 ppm). Conducted in a greenhouse over 21 weeks using loam soils, the experiment evaluated four treatments comprising three different particle-size ranges (<2 mm, 2–6 mm, and 6–15 mm) and a control. Plant growth (height, total and partitioned biomass), grain quality (N and protein), and soil properties (pH, electrical conductivity, and carbonates) were measured. Elevated CO₂ enhanced biomass, particularly vegetative biomass in wheat (+42.6%) and root biomass in maize (+55%), without significantly increasing yield. In wheat, particle size was decisive: intermediate fractions (2–6 mm) yielded the best results. In maize, basalt effects were less consistent. Concrete amendments increased soil pH and carbonate content, especially with coarse particles and elevated CO₂, whereas basalt-induced responses were slower and more variable. These findings confirm the potential of ERW as a dual climate–agronomic strategy while highlighting the need for long-term, field-scale validation. Full article