Search Results (11,835)

Soil stabilizers using conventional cement and lime binders incur high environmental costs owing to CO₂ emissions associated with their excavation, production, and processing. This has motivated research on low-carbon, waste-derived alternatives. The review shows that: biochar increases unconfined compressive strength (UCS) by 15–40% with a 2–5% dosage through pore filling and particle binding; nanocellulose promotes soil cohesion by 25–60% through fibrous network development and tensile bridging; recycled PET powder at 5–10% increases shear strength by 20–35% promoting mechanical interlocking, increasing stiffness, crack resistance and durability. Biochar provides direct carbon sequestration with a carbon transfer capacity of up to 2.5 tons CO₂-eq/ton. Recycled PET introduces waste valorization, with the potential to divert millions of tons of annual PET waste, while nanocellulose provides indirect carbon savings by avoiding emissions from cement and lime replacement. This review’s objectives are as follows: providing a comprehensive comparison of biochar, nanocellulose, and PET powder as promising non-cement composite stabilizers; identifying optimal dosage ranges and stabilization mechanisms for each material across different soil types; and outlining knowledge gaps and future research directions in sustainable geotechnical practices. The review assessed the individual and synergistic effects of the additives on critical geotechnical properties, including unconfined compressive strength (UCS), California bearing ratio (CBR), resilient resistance, swelling resistance, and the durability of the treated soil. Findings provide actionable guidance for practitioners seeking to reduce construction carbon footprints while maintaining geotechnical performance standards. Research gaps were identified, and future directions for integrating high-performance, low-carbon soil composites into sustainable construction solutions are proposed. Full article

The construction sector is experiencing increasing demand for deep underground structures in urban environments, where excavations frequently intersect fractured aquifers. Such conditions pose significant risks to structural stability and long-term durability due to groundwater inflow and elevated hydrostatic pressures. This study investigates the influence of deep underground construction on fractured aquifer systems using the Abu Dhabi Plaza development in Kazakhstan as a case study. An integrated methodological approach combining hydrogeological monitoring, hydrochemical analysis, and engineering–geological testing was applied. Groundwater levels were monitored using observation wells, while triaxial and uniaxial compression tests were conducted to evaluate the mechanical properties of rock and soil materials. Hydraulic gradients, flow velocities, and hydrostatic pressures were estimated using Darcy’s law and the Boussinesq equation, supported by GIS-based spatial analysis. Groundwater mineralisation is consistently represented in this study by total dissolved solids (TDS), expressed in g/L. The results indicate that groundwater in the Quaternary aquifer is fresh to slightly mineralised, with TDS ranging from 0.47 to 1.50 g/L, whereas groundwater in the fractured Ordovician aquifer exhibits a more stable hydrochemical regime with TDS values of 0.72–0.73 g/L. Statistical analysis identifies two primary controls on groundwater chemistry: (i) natural geochemical processes associated with water–rock interaction and (ii) technogenic influences related to urban activities. Hydrodynamic calculations indicate a hydraulic gradient of approximately 0.136, a filtration velocity of about 0.35 m/day, well discharge reaching 0.11 L/s, and hydrostatic pressure ranging from 1.45 to 2.81 atm. Groundwater drawdown caused by excavation dewatering reached 29–30 m. The findings demonstrate that groundwater inflow is primarily controlled by fracture-controlled permeability and structural heterogeneity within the aquifer system. These results highlight the importance of integrated hydrogeological and hydrochemical assessment, in which TDS serves as the principal quantitative indicator of groundwater mineralisation, for the effective management of groundwater-related risks during deep underground construction. Full article

This study addresses the urgent need for sustainable alternatives to single-use plastics by developing biodegradable composites from peach and apple processing waste employing hot compression molding. Utilizing a definitive screening design, the impact of the process variables, including recipe composition, grinding size, pressure, temperature, and holding time, on the physical (including water resistance) and mechanical properties of the composites was systematically evaluated. Physicochemical and thermal analyses of the dried by-products indicated that processing temperatures below 150 °C prevent the degradation of lignocellulosic constituents. The results demonstrated that increasing both the molding pressure and holding time decreased the composite thickness, while enhancing the stiffness and flexural strength, with modulus of elasticity values exceeding 1000 MPa under optimal conditions. Higher molding temperatures reduced water absorption and diffusivity, particularly in lignin-rich composites, by promoting lignin softening and particle consolidation, resulting in denser structures with limited moisture transport. Biodegradability was assessed through soil burial tests over 200 days, revealing a weight loss ranging from 54.2% to 90.7% among samples, with apple-based composites exhibiting greater degradation compared to peach-based ones. Overall, the study highlights the development of a “green composite” formulation inspired by biomimetic principles, exploiting the natural self-bonding capacity of lignocellulosic biomass, where two different-in-composition biowastes are combined to produce a plastic-free composite material with possible applications in the foodservice industry. Full article

Guar gum (GG), a typical biopolymer, has found widespread use in packaging applications due to its biodegradability, non-toxicity, and low price. However, the further application of GG is significantly limited by its poor flexibility and water resistance. In this study, GG/natural rubber (NR) films were prepared by thermo-compressing hand-kneaded pastes made from GG powder and fresh NR latex. Various NR contents—5, 10, 20, and 40 wt%—were investigated. Water-resistant properties were determined by moisture absorption, water dissolution, surface wettability, and water vapor permeability. Fourier transform infrared spectroscopy indicated interactions between the dispersed NR phases and the GG matrix. Scanning electron microscopy revealed distinct phase separation between the GG and NR phases in the films. All GG/NR films exhibited excellent interfacial adhesion between GG and NR phases. Tensile results indicated that an increase in the amount of NR in the GG-based films led to a decrease in both maximum tensile strength and Young’s modulus, while elongation at break increased. GG/40% NR films exhibited an elongation at break of 17.5%, which is a substantial increase of 415% compared to pure GG films. The addition of NR showed improved water-resistant properties of GG-based films; however, the rate of biodegradation during soil burial decreased as the NR ratios increased. These thermo-compressed GG/NR blends hold promise as sustainable alternatives to single-use plastic packaging applications. Full article

Urban soils along transportation routes are subjected to intense anthropogenic pressure, altering their physicochemical properties and promoting the accumulation of potentially toxic metals (PTM). This study aimed to assess soil contamination levels and evaluate the bioindicative potential of Acer negundo L. growing in urban green areas exposed to varying traffic intensities. Topsoil and leaf samples were collected from eight sites representing different levels of anthropogenic disturbance. Soil granulometric composition, pH, organic carbon content, selected nutrients, and concentrations of PTM (Cu, Pb, Zn, Ni, Co, Mn, Cd, Hg, Fe) were determined, and contamination was evaluated using pollution indices (Igeo, EF, CF, Er). The soils ranged from moderately acidic to slightly alkaline (pH_KCl 5.85–7.66). Elevated concentrations of Zn (1078 ± 3.07 mg kg⁻¹), Pb (401.4 ± 2.51 mg kg⁻¹), Mn (1816 ± 3.3 mg kg⁻¹), and Cd (10.8 ± 2.06 mg kg⁻¹) were recorded at most sites, frequently exceeding permissible limits for urban green areas (Zn: 500; Pb: 200; Mn: 240 and Cd: 2 mg kg⁻¹). Correlation analyses revealed that zinc and cadmium are the two predominantly traffic-related origins. Pollution indices indicated moderate to very high enrichment, particularly for Cu and, locally, for Cd and Zn, while cadmium posed the highest potential ecological risk. The differences in the order of element abundance between the soil and plant tissues indicated a selective enrichment in plant leaves, with a preference for Fe, Zn, Mn, Cu and Pb. A strong positive correlation between soil and leaf cadmium concentrations indicates its high bioavailability and efficient transfer to plant tissues. These results demonstrate that Acer negundo is a valuable bioindicator of urban soil contamination, particularly for cadmium and zinc, and highlight the significant impact of road traffic on urban soil quality. Full article

In earthquake engineering and hydraulic engineering, the dynamic mechanical behavior of cohesive soils is crucial to ensure structural stability. However, most existing dynamic constitutive models fail to adequately account for the influence of strain history, which is essential for accurately predicting soil behavior under seismic loading. This study conducted a series of cyclic single-shear tests on both in situ and disturbed Changsha cohesive soils. Hysteresis curves were obtained under varying shear strain amplitudes to investigate the degradation patterns of the dynamic shear modulus and the evolution of the damping ratio. Furthermore, multi-cycle loading tests under constant strain amplitude were carried out to clarify the correlation between damping ratio, dynamic shear modulus, and the number of loading cycles. A simplified practical dynamic model, applicable to general cohesive soils, is proposed. This model incorporates the effect of strain history and provides a valuable reference for analyzing the dynamic response of soils subjected to earthquake actions. Full article

In agriculture, the use of per- and polyfluoroalkyl substances (PFASs) as active substances in pesticides has increased over recent decades due to their chemical stability, their ability to alter cell membrane permeability, and their capacity to bind to target proteins. However, their intentional application to agricultural soils has led to progressive environmental accumulation. Their high persistence, mobility, and bioaccumulation potential, combined with documented toxicological effects, raise concerns for aquatic organisms and ecosystems. Monitoring surface and groundwater is essential to assess PFAS contamination. Data from the Italian monitoring plan show widespread contamination, despite the existing European regulatory framework designed to safeguard ecosystems and public health. The contamination is likely underestimated because monitoring programs currently target only a limited number of substances and PFAS metabolites and co-formulants are not included. Approximately 46 PFASs have been identified as active ingredients in pesticides, 29 of which are still authorized within the European Union, posing challenges for drinking water production and ecosystem protection. Existing regulatory regimes also differ in their evaluation procedures, which may lead to inconsistent conclusions regarding PFAS applications. Within the framework of the European “One Substance One Assessment” (OSOA) approach aimed at to ensuring the protection of human health and natural resources, this paper examines the properties of PFASs used as active substances in pesticides, their regulatory status, and their monitoring in Italy, highlighting the regulatory inconsistencies that result in the differential treatment of these substances compared with PFASs used in other sectors. Full article

Sugarcane is an important economic crop in southern China. Affected by typhoons, it is prone to lodging, which not only increases the difficulty and loss rate of mechanical harvesting but also reduces the sugar content. The mechanical properties of the sugarcane root–soil system are crucial to its lodging resistance. However, accurate discrete element parameters are still lacking for DEM-based research on the mechanical properties of this system. Therefore, this study adopts a method combining the angle of repose test, shear force test, and discrete element simulation of single roots to calibrate DEM parameters. Using the angle of repose and maximum shear force of a single root as response values, Plackett–Burman, steepest ascent, and Box–Behnken tests are sequentially carried out with Design-Expert 13 software to calibrate the contact and bonding parameters of individual sugarcane roots. The relative errors between the physical and simulation test results for the angle of repose and shear force are 1.29% and 0.66%, respectively. This study provides a reference for the establishment of discrete element simulation models for sugarcane roots and for the subsequent development of sugarcane root–soil composite models. Full article

This study collected 155 sets of test data for granite residual soils from the Fujian–Guangdong region and applied the chi-square test to analyze the distributions of eight common physical and mechanical parameters. Drained triaxial tests were then simulated using the Unified Hardening (UH) model, and a Sobol global sensitivity analysis of model parameters was conducted based on the distributions of soil properties. The results show that natural density and cohesion approximately follow Weibull distributions; void ratio, liquid limit and plastic limit follow lognormal distributions; water content and internal friction angle follow normal distributions; and plasticity index follows a Gumbel distribution. The Sobol analysis indicates that the critical state deviatoric stress mainly depends on the critical state stress ratio (M), the critical state volumetric strain is jointly controlled by M and the slope of the normal compression line (λ). The overall evolution of deviatoric stress mainly depends on M, and the overall evolution of volumetric strain mainly depends on λ, whereas Poisson’s ratio (ν) has little influence on the soil stress–strain response. These findings provide references for parameter selection and numerical simulation of granite residual soils in the Fujian–Guangdong region. Full article

In this study, compression, rebound, and triaxial tests were conducted to investigate the strength and deformation behavior of lignin-fiber-reinforced sandy soil under various conditions, with a focus on the influence of fiber content (FC) on its mechanical properties. Based on the experimental results, a modified Duncan–Chang model suitable for lignin-fiber-reinforced sandy soil was established. The results indicate that the addition of lignin fibers increases the compressive deformation of sandy soil. Under saturated conditions, the fibers suppress compressive deformation while enhancing rebound deformation, with the minimum compressive deformation observed at an FC of 0.5%. Quantitative analysis shows that as FC increases, the effect of dry and saturated states on compression and rebound indicators gradually diminishes. When the FC reaches 5%, these indicators are no longer significantly affected by moisture conditions. The inclusion of fibers also improves the shear strength of sandy soil. With increasing FC and confining pressure, the stress–strain curves gradually transition to a strain-hardening type. At an FC of 5% and under confining pressures of 100 kPa and 200 kPa, the stress–strain curves exhibit a more pronounced hardening trend compared to those at other fiber contents; under a confining pressure of 300 kPa, the curve exhibits a strain-hardening type. As FC increases, the specimens initially show dilatancy followed by contraction. The curves calculated using the modified Duncan–Chang model are in good agreement with the experimental data, validating the model’s feasibility in capturing softening-type stress–strain behavior. Full article

This study evaluates a SiO₂ nanoparticle (SiO₂NPs)/Paraloid B-72 nanocomposite as a restorative and antifungal treatment for deteriorated sandstone at the Ptolemaic Temple of Isis, located within a densely populated residential area. The temple stones exhibit structural damage, soiling, and severe microbiological deterioration. Fungal isolates from the sandstone were cultured on PDA medium and identified by ITS region DNA sequencing as Alternaria alternata, Penicillium chrysogenum, and Aspergillus niger. The SiO₂NPs and their Paraloid B-72 nanocomposites were synthesized and characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD). Stone samples, examined before and after treatment via SEM-EDX, TEM, and XRD, were used to assess both conservation performance and compatibility. Laboratory antifungal tests showed that SiO₂NPs at 300 ppm exhibited the greatest inhibition of mycelial growth, reaching 91.59% for P. chrysogenum, 90.77% for A. niger, and 85.2% for A. alternata. Mechanical testing demonstrated that treatment with the SiO₂NPs/Paraloid B-72 nanocomposite enhanced stone strength, increasing compressive strength from 26.5 MPa to 27.4 MPa. SEM images confirmed excellent, homogeneous dispersion of the nanocomposite on stone grains, forming a coherent coating without pore occlusion. Overall, the SiO₂NPs/Paraloid B-72 formulation improved sandstone surface properties while substantially improving short-term mechanical performance and antifungal efficacy, indicating promise for enhancing restoration procedures when combined with established conservation protocols for sandstone architectural heritage. Full article

Clarifying the responses of microbial communities in distinct microhabitats like roots, the soil, and litter layers to secondary succession is critical for predicting the effects of global climate change on ecosystem functions. We investigated the microbial activities, compositions, and networks in these microhabitats of Fagus lucida forests ranging from 40 to 200 years. The results showed that soil physicochemical properties decreased with forest succession, except for NH₄⁺-N and available phosphorus, which decreased at the early stage. All vector angles of extracellular enzyme stoichiometry that were greater than 45° indicated that phosphorus was the key limiting element for microorganisms. The microbial community shifted from r- to K-strategists with forest succession, displaying the replacement of most bacterial phyla by Proteobacteria and Acidobacteriota, and an increase in the Acidobacteriota: Proteobacteria ratio, especially in the soil and litter layers. Soil properties, particularly NH₄⁺-N and pH, significantly affected the bacterial diversity and structure. Moreover, the bacterial network complexity increased with succession, particularly in the litter layer, and the topological properties of bacterial networks showed a stronger influence on microbial activities compared with those of fungal networks. The richness of keystone taxa in the litter layer was higher than in the soil layer and roots. However, the fungal community dominated by symbiotrophs showed lower sensitivity to soil nutrient changes and greater resilience to forest succession, displaying stable diversity and decreased network complexity, particularly in the roots. Ectomycorrhizal fungi (e.g., Russula) dominated the fungal guilds, and their abundance increased with forest succession, accompanied by a decrease in pathogenic fungi. Plant roots with significantly higher phosphatase activities played a stronger role than soils in structuring the litter microbial community, as reflected by similar carbon- and nitrogen-acquiring enzyme activities, microbial compositions, a greater share of taxa, and closer community distance. Our results revealed the increasingly important role of plant roots with forest succession in structuring the microbial community and nutrient cycling in the soil and litter layers. Full article

This study focused on alfalfa (Medicago sativa cv. Xinmu No. 4) as the experimental material, and a two-year field plot controlled experiment was conducted to compare the effects of different co-application ratios of organic and chemical fertilizers on alfalfa yield, soil nutrient status, and soil biological characteristics. The six fertilization treatments were as follows: CM0 (100% cattle manure), CM1 (75% cattle manure + 25% chemical fertilizer), CM2 (50% cattle manure + 50% chemical fertilizer), CM3 (25% cattle manure + 75% chemical fertilizer), CM4 (100% chemical fertilizer), and CK (no fertilizer application). The results showed that alfalfa hay yield was highest under the CM3 treatment in both 2024 and 2025, representing increases of 38.03% and 40.85%, respectively, compared with the control (CK). Relative to the other treatments, CM3 significantly increased soil total nitrogen, alkali-hydrolyzable nitrogen, available phosphorus, readily available potassium, and organic matter contents. In addition, CM3 markedly enhanced the activities of soil nitrate reductase (NR), nitrite reductase (NiR), and the root enzymes glutamate synthase (GOGAT) and glutamine synthase (GS). The combined application of organic and chemical fertilizers significantly reshaped the soil bacterial community structure associated with alfalfa. Under the CM3 treatment, Chao1, Shannon, and ACE indices of soil bacterial diversity increased, whereas the Simpson index decreased. Moreover, the CM3 treatment was associated with higher relative abundances of several key bacterial phyla and genera. The 25% cattle manure plus 75% chemical fertilizer (CM3) treatment exhibited the strongest overall effects, significantly increasing total alfalfa hay yield, enhancing soil macronutrient availability and key enzyme activities, improving soil microbial α-diversity, and optimizing soil bacterial community structure. This treatment consistently outperformed the no-fertilizer control (CK) and all other organic–inorganic fertilizer combinations. Collectively, these findings provide robust scientific evidence supporting strategies to increase forage productivity, mitigate environmental impacts, and promote the sustainable development of the grassland industry. Full article

As solid waste generated from shield tunnel construction, shield muck is characterized by its massive volume, high water content, and poor engineering properties. Large-scale stockpiling not only occupies precious land resources but also poses potential environmental risks. This has become one of the key bottlenecks hindering the green, low-carbon, and sustainable development of rail transit construction. Efficient dewatering is a key prerequisite for its subsequent disposal or reutilization. Lime, cement, phosphogypsum, nano-SiO₂, and ground granulated blast furnace slag were employed in this research as composite conditioning agents to dewater shield tunnel muck. A range of water content, pH, and total organic carbon analyses tests were conducted to explore the roles of lime, cement, phosphogypsum, nano-SiO₂, and ground granulated blast furnace slag on the dewatering effect of shield tunnel muck. Furthermore, microstructures and elemental distribution of typical mixes were analyzed by scanning electron microscopy and energy-dispersive X-ray spectroscopy tests. Results indicate that a composite agent consisting of 3.5% lime, 4% cement, 1% phosphogypsum, 0.2% nano-SiO₂, and 4% ground granulated blast furnace slag exhibits optimal performance, reducing water content from 50% to 29.8% within 24 h. Phosphogypsum significantly decreased pH and reduced TOC to below 1 g/kg after 15 days, effectively mitigating the environmental hazards associated with muck disposal. The formation of cementitious products, including calcium aluminate hydrate, calcium aluminosilicate hydrate gels, and calcium silicate hydrate, effectively bonds soil particles. Additionally, ettringite crystals produced by the reaction between phosphogypsum and calcium aluminate phases filled interparticle voids. These processes were identified as the primary mechanisms for water reduction. Although nano-SiO₂ exerted a limited direct influence on water content, it acted as a pozzolanic catalyst that accelerated hydration reactions of lime and cement, rapidly reducing muck fluidity. The synergistic effect of the composite dewatering agent components establishes a multi-mechanism dewatering system characterized by “hydration gel + AFt filling + nano-catalysis.” The dewatering system developed in this study achieves both high efficiency and environmental friendliness for shield tunnel muck. This provides technical support for subsequent resource utilization, such as subgrade filling, while promoting the recycling of industrial solid wastes like phosphogypsum and blast furnace slag, ultimately contributing to green, low-carbon, and sustainable development. Full article

The excessive use of chemical fertilizers is a primary driver of soil degradation in agricultural systems. Planting green manure during fallow periods offers a sustainable alternative for soil conservation. The present study investigated the effects of different green manure cropping systems (Ryegrass (TR), Chinese milk vetch (TM), and Spinach (TS)) on soil physicochemical properties, biological activity, and microbial communities, compared to a control (CT). Results demonstrated that green manure treatments significantly enhanced soil fertility by increasing the content of soil organic matter (SOM), available nitrogen (AN), available phosphorus (AP), and available potassium (AK). Notably, the TR treatment increased SOM, AN, and AP by 23.0%, 60.0%, and 44.6% (p < 0.05), respectively. Concurrently, key soil enzyme activities (urease, dehydrogenase, catalase) were significantly boosted (p < 0.05), with TR showing the most pronounced effect. Earthworm indicators (such as earthworm biomass and abundance) were significantly higher in the Ryegrass plots (p < 0.05). Microbial analysis revealed that TM enhanced bacterial diversity, whereas TR increased fungal richness (p < 0.05). Beneficial bacterial phyla, particularly Proteobacteria, exhibited a marked increase under the TM and TR treatments, while the fungal community underwent a favorable shift. Consequently, a significant elevation was observed in the overall Soil Quality Index (SQI) across all green manure treatments. Notably, the TR treatment resulted in a substantial 150% increase. In summary, ryegrass emerged as the most effective treatment in enhancing soil fertility, biological activity, and microbial diversity, underscoring its considerable potential as a green manure for sustainable soil management during fallow periods in paddy fields. Full article