Search Results (1,626)

Vegetation restoration profoundly impacts soil carbon (C)-nitrogen (N)-phosphorus (P) cycling in arid sandy lands, with vegetation type critically regulating accumulation patterns. However, the magnitudes of soil nutrients and stoichiometry for different vegetation types are still largely unknown. Thus, we conducted a regional-scale study to evaluate the soil nutrients and nutrient stoichiometry under four typical vegetation types in the Mu Us Sandy Land (MUS), including monoculture arbor (MA), monoculture shrub (MS), arbor-shrub mixed (MAS), and monoculture herbaceous (MH), with cropland (Cr) and bare sand (Bs) controls. Our results showed that vegetation type significantly affected SOC and TN content. MS (30–40 years), MA (>40 years), and MH exhibited significant increases of 285.5–305.8% in SOC and 293.6–374.6% in TN in the topsoil, respectively. MS (30–40 years) and MH demonstrated increases of 399.1% and 283.3% in SOC and 250.2% and 162.8% in TN in the subsoil. However, MAS had no significant effect on SOC and TN. MA (>40 years) resulted in a higher TP in the subsoil. Compared to Bs, humic substances significantly increased by 111.1–171.6% under MA (>40 years), MS (>40 years), and MH, exhibiting positive correlations with SOC. Moreover, MAS treatment resulted in a higher C:N, while the MH resulted in a higher C:P and N:P in the topsoil. Despite stable total phosphorus (TP), elevated C:P and N:P ratios under MH indicated emerging P limitation in restoration. Therefore, long-term monoculture shrub, arbor, and herbaceous vegetation effectively enhances soil fertility in arid sandy lands through long-term SOC accumulation and humic substance formation. Full article

In arid and semi-arid regions where soil sandification is widespread, soil drying simultaneously reduces water availability and increases mechanical impedance, yet how rhizosphere carbon inputs regulate this coupling remains unclear. We investigated whether a synthetic root exudate (SRE, glucose) alters the moisture range and time window in which penetrometer resistance (PR) increases during drying across soils with contrasting sand contents. Volumetric water content (θ) and PR were measured concurrently at fixed drying times, from which PR-θ sensitivity metrics and a reference threshold (PR = 2 MPa) were derived. Relative to the control, SRE maintained a higher θ from day 3 onward but also increased PR, shifting the main PR sensitivity window toward wetter conditions and maximum sensitivity was amplified about 3.5-fold at intermediate sand contents. SRE also caused responsive soils to cross the 2 MPa threshold 1.0–1.5 days earlier. Overall, this model system highlights a rhizosphere-driven trade-off: low-molecular-weight carbon inputs can retain moisture while accelerating drying-induced hardening risk toward wetter conditions, with the strongest effects at intermediate sandification levels. These findings provide process-level insight that may inform sustainable soil and water management in arid and semi-arid sandy agroecosystems. Full article

Soil salinity poses a major challenge to agricultural productivity, especially threatening food security in arid and semi-arid areas. Traditional soil reclamation methods, such as leaching, chemical amendments, and drainage engineering, usually need large amounts of water, involve high costs, and can lead to environmental problems. This review compiles existing knowledge on innovative strategies for managing saline soils, focusing on buried interlayer systems that use materials like straw, sand, gravel–sand mixtures, and biochar. These interlayers improve soil hydraulic properties by preventing capillary rise, encouraging salt leaching, and reducing surface salt buildup. Biochar stands out as a particularly useful material because of its stability, large surface area, porosity, and high cation exchange capacity. These features help improve soil structure, increase water retention, and effectively retain sodium. Evidence from lab and field tests shows that buried biochar layers can stop salt from moving upward, aid in desalinating the root zone, and boost crop yields. While straw and sand interlayers show potential in reducing salinity, biochar is noted for its multifunctionality and long-term effectiveness in addressing salinity problems. The success of buried biochar systems depends on several factors, including the properties of the biochar, how much is used, how deep it is buried, and the specific soil and climate conditions. This review highlights how these systems work, compares their performance, and points out research gaps, advocating for their potential as a sustainable, resource-efficient way to manage salinity and improve soil health over the long term. A substantial proportion of the existing evidence is derived from controlled laboratory studies, and the buried biochar layer approach remains an emerging technique that requires further validation under field conditions. Still, significant knowledge gaps persist regarding long-term performance and water-salt dynamics, while site-specific soil variability and scalability challenges may limit the effective implementation of biochar interlayer systems under field conditions. Full article

This study explores the use of diatomite from West Kazakhstan as a silica-containing raw material for borosilicate glass production. Three glass batches, based on quartz sand, chalk, and diatomite, were synthesized with varying ratios of network-forming and modifying oxides. Partial replacement of quartz sand with diatomite enabled glass melting at 1150 °C, producing a homogeneous melt. Glasses with higher diatomite content showed improved chemical and water resistance; specifically, the sample containing 52% diatomite achieved hydrolytic class III and water resistance class IV (XA = 1.0 cm³·g⁻¹), whereas quartz-based control samples corresponded to classes IV–V. Heat resistance ranged from 120 to 160 °C depending on composition. These findings demonstrate that amorphous SiO₂ and active oxides in diatomite promote a stronger three-dimensional glass network, highlighting the potential of locally sourced diatomite as an alternative SiO₂ source for sustainable, energy-efficient borosilicate glass production. Full article

This study introduces and investigates a novel phase-specific waste utilization strategy for cement-based materials, aiming to concurrently enhance engineering performance and environmental efficiency. Marble dust (MD) was strategically employed as a partial cement replacement in paste systems, while waste glass (WG) served as a natural sand replacement in mortar. Initial findings indicated a reduction in workability for both MD- and WG-incorporated mixtures, with respective declines reaching up to 48.6% and 44.4%. Early-age compressive strength in MD-added mixtures decreased by up to 9.2%, primarily attributed to dilution effects, while WG-containing mixtures exhibited only minor reductions in early strength. Crucially, significant strength recovery was observed at later ages (>28 days). Compressive strengths ultimately increased by up to 3.8% with MD and 5.1% with WG compared to control mixtures, while flexural strengths saw improvements of 6.8% for MD and a notable 13.8% for WG mixtures. Further analysis revealed improved pore refinement at later ages (>28 days). Porosity decreased substantially, by up to 30.1% for MD-containing mixtures and 22.4% for WG-containing mixtures. Similarly, water absorption was reduced by up to 29.5% for MD and 21.8% for WG, attributing these enhancements to MD’s filler and nucleation effects and WG’s pozzolanic reactivity. From an environmental perspective, MD incorporation led to a significant reduction in CO₂ emissions, up to 10.87%. Conversely, WG generally caused minor increases (up to 0.59%), though a 10% replacement level achieved a 1.43% reduction. These results underscore that cement replacement with MD offers superior environmental benefits compared to aggregate replacement. The study highlights the successful balancing of mechanical properties with environmental sustainability through this phase-specific approach, emphasizing the critical influence of transportation distance on the overall carbon footprint. Full article

This study investigates the mechanical behavior of polyurethane (PU)-stabilized calcareous sand with varying PU contents and relative sand densities using unconfined compression and direct shear tests. The results demonstrate that PU stabilization significantly enhances compressive and shear strength and induces a transition from brittle to ductile failure with increasing PU content. Strength and stiffness exhibit nonlinear growth as an interconnected polymer bonding network develops. Relative density controls the timing and efficiency of strength mobilization, with dense specimens strengthening earlier and loose specimens exhibiting accelerated strength development at higher PU contents. SEM and XRD analyses confirm that stabilization is dominated by a bonding–solidification mechanism, without altering the mineralogical composition. Overall, PU stabilization provides an effective approach for achieving rapid strength development and stable mechanical performance in calcareous sand. Full article

With the expansion of electric vehicle (EV) applications into unstructured sandy terrains such as deserts, accurately characterizing tire–sand dynamic interactions is essential for enhancing off-road performance. However, traditional terramechanics models, the discrete element method (DEM), and purely data-driven neural networks all have inherent limitations, failing to balance physical interpretability and computational efficiency. This study proposes a wheel–sand dynamics prediction model that integrates DEM simulation, semi-physical modeling, and deep learning. A DEM tire–sand contact platform is built to acquire longitudinal slip and cornering properties, and a dimensionless semi-physical tire model is derived using frictional constitutive relations and tire theory. A 3-DOF vehicle dynamics model is then established to generate high-fidelity physics-based datasets, and a residual neural network is adopted to avoid performance degradation in deep networks. The model is validated and optimized via real-vehicle sandy terrain tests, with its performance compared against other network structures. The proposed model achieves high prediction accuracy, with engineering-acceptable errors, and outperforms conventional neural networks. The dimensionless framework improves generality, overcoming the weaknesses of traditional and purely data-driven models. This work provides theoretical and statistical support for EV traction control design and tire structure optimization, promoting driving stability and terrain passability in unstructured sandy environments. Full article

Deep shale gas reservoirs in the southern Sichuan Basin (Weiyuan area) exhibit strong heterogeneity and complex pore-fracture networks. Traditional reservoir evaluation methods struggle to accurately capture their microscale pore characteristics and fracability, thereby restricting efficient development and precise sweet spot prediction. Therefore, integrating digital core technology with geological analysis is essential to systematically quantify key reservoir parameters, including microscale pore structure, mineral composition, and brittleness characteristics. To clarify the controlling factors of high-quality deep shale gas reservoirs in the Weiyuan area and assess their exploration and development potential, we performed digital core analysis at micron to nanometer scales. Three-dimensional digital core models of representative deep shale gas wells were constructed. Integrating mineral composition, geochemical characteristics, and pore space features, we discuss the geological conditions for deep shale gas accumulation and the fracability of horizontal wells, and we delineate favorable shale reservoir zones. The results show that digital core technology enables quantitative and visual characterization of each sublayer of the Longmaxi Formation shale reservoir, including mineral types, laminae types, pore-throat structures, and organic matter distribution. From the Long 11-1 sublayer to the Long 11-4 sublayer, the pore-throat radius, total pore volume, total throat volume, connected pore-throat percentage, and coordination number all gradually decrease. In the eastern Weiyuan area, the siliceous components in deep shale gas reservoirs at the base of the Longmaxi Formation are primarily of both biogenic and terrigenous origin. Due to local variations in the sedimentary environment, terrigenous input contributes significantly to the total siliceous content in this region. Although the Long 11-1 sublayer of the Longmaxi Formation is lithologically classified as mud shale, its particle size and mineral composition more closely resemble those of clayey siltstone or argillaceous sandstone, suggesting considerable potential for reservoir space development. Typical wells in the eastern Weiyuan area exhibit distinct lithological characteristics, including coarser grain sizes, stronger hydrodynamic conditions during deposition, and abundant terrigenous clastic supply. The rigid framework formed by silt- to sand-sized particles effectively mitigates compaction, thereby facilitating the preservation of intergranular pores and microfractures. High organic matter abundance, appropriate thermal maturity, and a considerable thickness of high-quality shale ensured sufficient hydrocarbon supply. The main types of natural fractures are intergranular and grain-edge fractures formed by differences in sedimentary grain size, and bedding-parallel fractures generated by hydrocarbon generation overpressure. Based on reservoir mineral composition, pore characteristics, areal porosity, and pore size distribution identified via digital core analysis, the bottom 0–3 m of the Long 11-1 sublayer is determined to be the optimal target interval. By delineating the microscopic characteristics of the shale reservoir and predicting rock mechanical parameters, a fracability evaluation index was established from digital core simulations. This guides the selection of target layers in deep shale gas reservoirs and optimizes hydraulic fracturing design. Full article

Benthic foraminifera are valuable bioindicators in modern and paleo-environmental studies due to their sensitivity to ecological changes. While sediment grain size is a fundamental factor structuring benthic habitats, its direct impact on benthic foraminifera remains poorly understood, as field studies are often complicated by covarying environmental parameters. To address this knowledge gap, we conducted a 14-week controlled laboratory culture experiment to investigate the biological response of a common benthic foraminifera Quinqueloculina seminula to different sediment grain sizes. Specimens were cultured in three distinct sediment grain size treatments (50, 150 and 250 μm), representing a gradient from fine to coarse sand. Our results demonstrate a clear and significant positive relationship between sediment grain size and the test size of Q. seminula. Furthermore, the species exhibited significant morphological plasticity, with the ratio of length/width increasing from 1.61 in fine sediment to 1.71 in coarse sediment. Individuals of Q. seminula in coarse sediment developed more elongate tests, while those in fine sediment maintained a more rounded morphology. This study provides the first experimental evidence that sediment grain size can drive significant changes in the size and morphology of Q. seminula. The observed phenotypic plasticity likely represents an adaptation to optimize locomotion and energetic allocation in different sedimentary environments. These findings confirmed the importance of sediment granulometry as a key control on foraminiferal biology and have important implications for the use of morphological data in paleoenvironmental reconstructions and modern biomonitoring. Full article

The reconstruction of detrital flux, paleoclimate, paleosalinity, paleo-primary productivity, paleohydrodynamic conditions, and paleo-water depth enhances understanding of sedimentary processes and their drivers during deep-time greenhouse-icehouse transitions, such as the Eocene–Oligocene transition. This study uses detailed geochemical analyses of major oxides and trace elements in sediment samples collected from the Beni Suef Formation (Bartonian–Priabonian) and the Maadi Formation (Priabonian) in the southern Tethys shelf (Egypt, northeastern Desert). Detrital proxies, including Si/Al, Ti/Al, and Zr/Al, indicate an enhanced influx of terrigenous sediments in the middle portion of the Qurn Member of the Beni Suef Formation, as further supported by noticeable facies variations, particularly the transition from shale to coarser silt- and sand-sized fractions. Paleoclimate indicators (Sr/Ba, Rb/Sr, K₂O/Al₂O₃, and Sr/Cu) point to a climatic shift from humid to arid conditions, consistent with the regional Late Eocene aridification across the Tethyan realm. Paleosalinity proxies (Sr/Ba, Ca/Al, and Mg/Al×100) suggest episodic intensification of open-marine influence and a reduction in freshwater input, with an upsection increase in Sr/Ba ratios, reflecting phases of enhanced marine water settings or decreased terrestrial runoff. Primary productivity was evaluated using multiple geochemical proxies, including P, Ni/Al, Cu/Al, P/Al, P/Ti, and Babio ratios. These collectively indicate generally low primary productivity interrupted by intervals of enhanced paleoproductivity or increased organic matter export to the sediments. This interpretation is further supported by the low total organic carbon (TOC) values. These results highlight the sensitivity of the southern Tethys shelf to Middle–Late Eocene climatic variability and the key role of prevailing paleoenvironmental conditions in controlling sediment supply, water chemistry, and biological productivity. Full article

Tamusu, the only identified super-large sandstone-hosted uranium deposit in the Bayingobi Basin, provides an important natural laboratory for evaluating ore-controlling factors and genetic models of sandstone-type uranium mineralization. Based on core descriptions from more than 200 boreholes, log facies analysis and geochemical environmental proxies, this study constrains the sedimentary–mineralization architecture and key controlling factors of the deposit. Uranium orebodies are mainly hosted in the upper member of the Lower Cretaceous Bayingobi Formation (Sq2) within a gravity flow-dominated fan-delta–lacustrine system. Braided distributary channel sands on the fan-delta plain and subaqueous distributary channel sands on the delta front constitute the principal uranium reservoirs, controlling both the migration pathways and storage space for U-bearing fluids. Mineralization is jointly governed by fan-delta architecture, interlayer oxidation zonation and reducing agents. The interlayer oxidation zone displays a north-thick–south-thin geometry, and uranium orebodies are concentrated at redox transition positions, with grades of 0.01–0.33 wt%. The metallogenic evolution can be summarized in three stages: syndepositional uranium pre-enrichment, interlayer oxidation mineralization, and a late hydrothermal/diagenetic overprint that mainly modified reservoir properties, favored ore preservation, and did not contribute to the primary uranium budget. Accordingly, a genetic model of “fan-delta architecture + interlayer oxidation control + late overprint and preservation” is proposed to guide exploration in the Bayingobi Basin and analogous sandstone-type uranium systems. Full article

Sustainable materials are increasingly being incorporated into high-strength concrete (HSC) to reduce environmental impact while maintaining structural performance. This study experimentally investigates the combined use of steel scale waste (SSW) as a replacement for natural fine aggregates and graphite nano/micro platelets (GNMPs) as a nano-modifying additive in HSC. Natural sand was replaced with SSW at levels of 0%, 50%, and 100%, while GNMPs were incorporated at dosages of 0%, 0.1%, 0.3%, and 0.5% by weight of cement. The results indicate that partial replacement of sand with SSW significantly improves concrete density and mechanical performance due to enhanced particle packing and the high specific gravity of steel scale particles. At the nanoscale, GNMPs contribute to pore refinement, improved nucleation of hydration products, and crack-bridging within the cement matrix, thereby strengthening the interfacial transition zone and delaying crack propagation. The combined effect of these mechanisms produces a synergistic enhancement in concrete performance. The optimum mixture containing 50% SSW and 0.3% GNMPs achieved a compressive strength of 68.2 MPa and splitting tensile strength of 7.6 MPa, representing improvements of approximately 54% and 52%, respectively, compared with the control mix. Durability-related properties such as water absorption and sorptivity were also significantly improved due to matrix densification and pore structure refinement. Although the incorporation of SSW and GNMPs reduced workability, all mixtures remained within a practical range for casting. The developed concrete is particularly suitable for structural applications requiring high strength and durability, such as high-rise building components, bridge elements, and precast structural members. The findings demonstrate that the combined use of industrial steel waste and nano-reinforcement offers a promising pathway toward sustainable and high-performance concrete. Full article

Beach sands may harbor human pathogens and antibiotic resistance genes, prompting the proposal of low-dose quicklime (CaO; 1–3% w/w) as a remediation strategy to improve microbiological quality in highly contaminated areas. After application, CaO is converted into calcium carbonate (CaCO₃), yet the ecological effects of this residual compound on benthic fauna remain poorly understood. This study evaluated the short-term impact of CaCO₃-enriched sediment (3% w/w) on the Manila clam, Ruditapes philippinarum, under controlled mesocosm conditions. Adult clams were exposed for one week, and survival, burrowing behavior, feeding- and metabolism-related parameters (clearance, ingestion, absorption efficiency and rate, ammonia excretion), and oxidative stress (malondialdehyde, MDA) were assessed using a hierarchical design, with a tank as the experimental unit. No significant differences were detected between control and CaCO₃-enriched treatments for any measured endpoint. Survival remained high, functional responses showed overlapping ranges, and MDA levels did not differ significantly between groups. Although limited to short-term exposure and a single concentration, these findings suggest that residual CaCO₃ derived from quicklime application did not induce detectable adverse effects in adult R. philippinarum under the tested conditions. Further long-term and multi-species studies are needed to confirm ecological safety. Full article

Wind erosion is a multidimensional, dynamic process driven by natural and anthropogenic factors, but existing statistical methods struggle to capture its complex nonlinear relationships, resulting in incomplete quantification of drivers and their spatial variability. To address this, we integrate the Revised Wind Erosion Equation (RWEQ)model with explainable artificial intelligence to disentangle the spatiotemporal positive and negative effects of dominant drivers and their synergistic interactions in Inner Mongolia. Results show that, from 2000–2022, wind erosion has been decreasing on average by 1.1 t·ha⁻¹·yr⁻¹, mainly in the western deserts and locally in Hulunbuir sandy land. Severe erosion is mostly due to nature (78.7%) rather than anthropogenic (21.3%). Normalized difference vegetation index (NDVI), clay content (CL), windy days (WD), precipitation (PRE), temperature (TEM), and sand content (SA) were found to be the most important drivers of wind erosion. Critical threshold conditions for severe wind erosion are NDVI < 0.14, CL < 12%, GD > 26, PRE < 73.15 mm, and SA > 66%. When there is a certain combination of variables, wind erosion risk is greatly increased, which mainly happens in the western part of Alxa, Bayannur, and the area near the desert edge. Wind erosion control should shift toward region-specific precision management, including engineering protection, optimized grazing management, and vegetation restoration. Full article

In arid and semi-arid agroecosystems, soil water availability is a critical regulator of coupled carbon–water (C–W) cycling, vegetation dynamics, and ecosystem resilience under environmental change. This research investigated the temporal evolution and spatial patterns of soil moisture across sand dune slopes within the Mu Us Sandy Land. Data were collected via a combination of continuous high-frequency in situ monitoring spanning 20 months and manual sampling campaigns. We analyzed moisture levels at various depths and slope positions (windward vs. leeward) to understand their distribution and reaction to precipitation. Statistical analysis of all rainfall events that triggered measurable soil moisture responses showed that precipitation was the primary determinant of soil moisture fluctuations. Specifically, shallow soil (10 cm) reacts rapidly to rainfall events > 4.6 mm, whereas intermediate layers (20–50 cm) require > 8.6 mm. Conversely, deep soil moisture (>100 cm) remains stable, responding only to substantial storm events (>50 mm). Topography exerts a strong control over spatial variance; notably, slope toes consistently exhibit higher moisture than upper sections, particularly during wet seasons, indicating strong topographic control on moisture redistribution and possibly reflecting lateral subsurface transfer. Additionally, a nonlinear correlation was observed between mean moisture content and its variability, peaking under intermediate moisture conditions. The results provide a mechanistic basis for understanding agroecosystem responses to climate variability and offer valuable insights for adaptive land management, vegetation restoration, and hydrological modeling in water-limited regions. Full article