Search Results (376)

Shallow groundwater in saline soils creates a self-reinforcing cycle where waterlogging-induced root hypoxia impairs the ATP-dependent sodium exclusion mechanisms that plants rely on for salt tolerance. We conducted a two-year field experiment to test whether subsurface drainage must precede root-zone aeration for oxygen delivery to be effective. The experimental site was located in Heyang County, Weinan City, on the Guanzhong Plain of Shaanxi Province, north-central China—a major alluvial agricultural region representative of shallow-groundwater-induced salinization. The site had saturated paste electrical conductivity of 6.0 dS m⁻¹ and groundwater depth fluctuating between 0.5 and 1.4 m. A randomized complete block design with 2 × 2 factorial arrangement compared four treatments: control (CK), subsurface drainage only (SD), root-zone aeration only (RA), and both interventions combined (SD + RA). Drainage increased air-filled porosity from 5.8% to 13.5%, crossing the 10.2% threshold (95% CI: 9.1–11.3%) where gas-phase continuity emerges according to segmented regression analysis. Without drainage, aeration achieved only 4.2 mg L⁻¹ dissolved oxygen with high spatial variability (CV 12.5%), while the combined treatment reached 6.8 mg L⁻¹ (CV 6.8%). Root ATP content increased by 89% in SD + RA compared to control, accompanied by 56% lower root Na⁺ and 185% higher K⁺/Na⁺ ratio. These physiological changes correlated with 31% higher grain yield (7580 vs. 5798 kg ha⁻¹). The synergy index of 1.40 (95% CI: 1.28–1.52) indicated that combined effects exceeded the sum of individual treatments by 40%. Methane emissions declined by 62%, and the system achieved a 2.9-year payback period with a benefit–cost ratio of 4.08. These results establish drainage as a physical prerequisite for effective oxygenation, providing a mechanistic explanation for the variable performance of aeration systems reported in previous studies. Full article

Urban underground construction in water-rich sandy strata produces large quantities of high-fluidity pipe-jacking spoil whose high water content, residual conditioning agents and heavy metal contaminants make conventional dewatering and landfilling increasingly unsustainable under carbon peaking and neutrality targets. This study explores a low-carbon route that converts such spoil into CO₂ foamed concrete through a coupled alkali activation–CO₂ foaming process. Ground granulated blast furnace slag and fly ash are used as geopolymer precursors, while a CO₂-based aqueous foam is introduced as both a pore-forming phase and carbon source. Single-factor tests and an L16(4⁴) orthogonal design are conducted to quantify the effects of CO₂ concentration, foam volume fraction, geopolymer dosage and alkali activator content on fluidity, setting time and compressive strength. Scanning electron microscopy (SEM) is employed to examine pore structure, gel morphology, carbonate precipitation and the interfacial transition zone around spoil particles. The results identify an optimum mix window (CO₂ 60–80%, foam 70–80%, geopolymer ≈ 20% and alkali activator ≈ 10% of solids) that delivers a fluidity above 210 mm, 28-day strength exceeding 3.0 MPa and a uniform closed-pore network. A multi-scale mechanism is proposed in which physical foaming, chemical carbonation and spoil particle immobilization act synergistically to form a dense gas–solid–soil composite suitable for in situ backfilling. Full article

Water-based drill cuttings generated during onshore natural gas development are complex solid wastes that may pose environmental risks if improperly managed. This study evaluates the feasibility of reutilizing water-based drill cuttings as pavement base materials after stabilization using a novel composite stabilizer composed of cement, stabilizer liquid agent, and water-reducing powder (CLP stabilizer). Mix proportion optimization was conducted through compaction and 7-day unconfined compressive strength tests, followed by evaluation of road performance, including strength, compressive rebound modulus, water stability, and temperature shrinkage, with stabilized powder stabilized soil as a control. Microstructural characteristics were analyzed using X-ray diffraction and scanning electron microscopy, and environmental safety was assessed through heavy metal leaching tests and background soil investigation. The results show that the optimal mixture ratio of curing agent (5% cement + 2% liquid stabilizer + 8% superplasticizer powder) satisfies the strength requirement for pre-drilling road bases, exhibiting superior performance compared to the control group. When the stabilizer dosage reaches 9%, the 7-day unconfined compressive strength achieves a maximum of 3.38 MPa, representing a 51% increase over the control group. At a stabilizer dosage of 12%, the splitting tensile strength reaches a peak value of 0.901 MPa, showing a 60.3% improvement. These results indicate enhanced deformation resistance, water stability, and reduced temperature shrinkage rates. Microstructural analysis indicates that the formation of calcium silicate hydrate (C-S-H) gel and ettringite (AFt phase) leads to a denser structure and enhanced durability. Heavy metal concentrations comply with relevant standards, demonstrating controllable environmental risks and supporting sustainable pavement base application. Full article

The analysis of water and emission efficiency in cropping systems is vital for sustainable agriculture in Mediterranean regions, which face increasing water shortages. This study offers a site-specific assessment of the Water Footprint (WFP) and Carbon Footprint (CFP) of organic cotton grown under Mediterranean conditions, integrating environmental indicator measurements with economic valuation of greenhouse gas (GHG) emissions via the EU Emissions Trading System (ETS) and the Social Cost of Carbon (SCC). Experiments were carried out at three sites with different soil types, testing two cultivars (Armonia and ST-318) under three irrigation scenarios: severe water deficit (I30), moderate water deficit (I70), and full irrigation (I100). The results reveal significant site-specific variability, with average WFP_lint values ranging from about 1.440 m³ per ton at the most productive site to over 4.100 m³ per ton at the least productive site. Similarly, CFP_lint is lower under high-yield conditions, emphasizing the strong influence of yield on mass-based indicators. At the Carboj and Primosole sites, shifting from (I30) to I100 results in roughly a 50% reduction in emissions, while at Buonfornello, increased irrigation does not consistently produce benefits. The cultivar response is key: Armonia shows greater resilience to water stress, while ST-318 performs best with full irrigation. Overall, the findings highlight that the sustainability of the Mediterranean cotton system depends on factors such as yield performance, site-specific conditions, and cultivar choice. Full article

Halophyte plants constitute vital resources for the advancement of sustainable agricultural practices in soils affected by salinity; however, the precise germination requirements for these species are still inadequately investigated. In this study, we examined how Salicornia europaea aggr., a succulent edible halophyte species, germinates under different genetic, environmental, and hormonal conditions such as gibberellic acid (GA₃), testing the effects of genotype, light exposure, and salinity stress on seed and early seedling development. Two genotypes (GR-1-BBKK-24.6196 and GR-1-BBKK-25.6212) were examined across a range of GA₃ (0, 250, 500 ppm), light intensity (40 and 80 μmol m⁻² s⁻¹), and salt concentrations (0 and 1% NaCl). At the seedling stage, four NaCl concentrations were used (0, 50, 100, 200 mM NaCl). Our data showed that S. europaea seeds do not exhibit dormancy—GA₃ treatment had no effect on germination success. Dark conditions and salt exposure both hindered germination, whereas the highest light intensity (80 μmol m⁻² s⁻¹) improved it considerably. Salt stress progressively slowed seedling growth. Seedling development was enhanced by 200 mM NaCl demonstrating inconsistency of the effect of salinity between the seed and seedling stages. Overall, our work demonstrates that the germination in S. europaea varies substantially between genotypes, with sufficient light and low salt being particularly important for maximizing seed germination, while 200 mM NaCl seems to promote seedling growth. Full article

The rapid development of the oil and gas industry has led to increasingly severe challenges for buried pipelines when crossing complex geological environments. Especially in fault zones induced by seismic action, the pipe–soil interaction mechanism and the rapid judgment of pipeline mechanical response urgently require in-depth research. This study conducted pipe–soil interaction tests on pipeline uplift under seismic-frequency loading, and for the first time, proposed a modified soil-spring method suitable for typical soft clay under seismic wave frequencies of 1–5 Hz. Through numerical simulation, the axial strain response of pipelines under normal fault movement was systematically analyzed. Considering comprehensively various variables such as fault dip angle, seismic wave frequency, internal pipeline pressure and wall thickness variation, this study extracted the maximum and minimum strain characteristics of the pipe top and pipe bottom, established a diversified intelligent prediction system for fault geological hazards, constructed the optimal machine learning model matching the type of normal fault geological hazards, and realized full-process intelligent modeling from model selection to parameter optimization. The research results can provide technical support for the seismic design and safety status prediction of pipelines under normal faulting conditions. Full article

Dynamic phase transition of natural gas hydrates confined within complex pore–throat structures is a key factor impacting the safe and efficient development of hydrate-bearing deposits. In this work, hydrate-bearing samples with varying saturation were first reconstructed with the proposed ice-seeding method using actual marine soil in hydrate-bearing sediments from the South China Sea. Dynamic evolution characteristics of hydrate formation in evolving porous media under different temperature and pressure conditions were analyzed in detail. Combined with high-resolution CT scanning, image processing, pore network extraction, and statistical analysis, the typical microscopic pore–throat structures of hydrate-bearing sediments were revealed, and the presence of nanopores was identified. Furthermore, highly controllable heterogeneous pore–throat structures were constructed for microfluidic chips by integrating stochastic modeling, equivalent modeling, and machine learning approaches. On this basis, a novel microfluidic testing method was developed for investigating the dynamic formation, dissociation, and phase transition characteristics of natural gas hydrates in complex pore structures by controlling the temperature. This study provides reliable data support and theoretical guidance for the productivity prediction of marine hydrate-bearing deposits. Full article

Replacing conventional chemical binders with natural polymers in geotechnically treated soil allows for the creation of more sustainable materials with both valuable ecological and mechanical properties. Xanthan gum and sodium alginate are natural polymers with excellent binding properties and water retention, which can help reduce carbon emissions. However, there is a lack of research on how to achieve optimal performance through the rational formulation of different biopolymers. This study investigates the use of these two natural biopolymers as binders (xanthan gum and sodium alginate) in slope-protection habitats treated with soil optimised using response surface methodology (RSM) within Design-Expert analysis software. The effects of xanthan gum concentration, sodium alginate concentration, and time, as well as their interactions on the properties of treated soil, ryegrass growth, and soil greenhouse gas emissions were evaluated, resulting in an optimized substrate formulation that balances good geotechnical properties with low environmental impact. Pot cultivation trials indicated that cohesion (c) and internal friction angle (φ) increased linearly with rising xanthan gum and sodium alginate concentrations, while the number of ryegrass plants (N_p) and root area ratio (RAR) decreased linearly with increasing binder concentration. Both CO₂ and CH₄ fluxes increased with rising binder concentrations. An analysis of variance (ANOVA) revealed that xanthan gum concentration had a stronger promoting effect on c and φ and a stronger inhibiting effect on N_p and RAR than sodium alginate. In contrast, sodium alginate concentration exhibited a stronger inhibitory effect on CO₂ and CH₄ fluxes. Through comprehensive optimization of geotechnical properties, vegetation growth, and greenhouse gas emissions, the optimal formulation was determined to be 0.885% for xanthan gum and 0.791% for alginate. The optimized composition resulted in increases of 38.6% and 19.1% for c and φ, respectively, while N_p and RAR increased by 7.7% and 15.0%, respectively. CO₂ and CH₄ fluxes decreased by 61.6% and 65.2%, respectively. This study contributes to advancing the sustainability of geotechnical treatments to favour vegetation regrowth. However, these materials will need to be further tested under field conditions to verify their effectiveness and duration. Full article

In agriculture, soil amendments like compost, manure, superabsorbent polymers (SAP) and biochar (BC) are already in use to mitigate the effects of water shortage and to obtain a higher yield and survivability. The present study focuses on the impact of BC and SAP under moderate and reduced soil water content (SWC) on the physiological and biochemical response of Chenopodium quinoa Willd. (cv. UDEC-5), a naturally drought-resistant and strategic crop in arid regions, with the aim of further improving its resilience and biomass production. Plants were grown in the presence or absence (control) of SAP (1% or 0.1% g/100 g SAP) or BC (3% g/100 g BC) by taking into account the smallest possible amount of irrigation necessary for optimal growth of the control. Sixty-five days after sowing, the reduced watering approaches started. The irrigation amount was reduced slowly until plants without any amendment showed a significant reduction in CO₂/H₂O gas exchange and further significant changes in 23 morphological, physiological and biochemical symptoms of water shortage. Each amendment already caused individual plant response in wet conditions: The soil amendments of SAP (1% and 0.1%) and BC had no significant effect on biomass production but caused changes in PS I (portion of oxidized and open centers in PS I), the C/N ratio and N content. The addition of SAP (0.1% and 1%) led to a decrease in gH⁺, ECStmAu ^× gH⁺, R_D, R_L, the C_i/C_atm ratio and ETR/A_gross ratio and to an increase in water use efficiency (WUE), especially in the 0.1% SAP treatment. In moderate conditions, 0.1% SAP and 3% BC caused a significant increase in both the LOP and C/N ratio. In the moderate treatments, the application of 0.1% SAP promoted an increased A_net, while 3% BC promoted a significant reduction in malondialdehyde (MDA). The results of the present quinoa experiment indicate the drought avoidance mechanism of the control under low SWC. The reduced transpiration led to increased WUE due to the efficient use of the substomatal CO₂ reservoir under low C_s and low E. It could also be confirmed that quinoa plants balanced low soil water potential by the accumulation of compatible solutes to lower the LWP and LOP. Drought led, especially in leaves in the 1% SAP treatment, to significant reductions in CO₂/H₂O gas exchange (A_net, R_D), decreases in Y (II) and ETR in PS II, and an increase in the ETR/A ratio and over-reduced centers in PS I, pointing to an increased appearance of reactive oxygen species (ROS) in the chloroplasts. The latter change was indicated by higher levels of lipid peroxidation (MDA). It could be shown that the response of the test species Chenopodium quinoa to the addition of BC and SAP proved to be highly adaptable. The plant reacted in a very coordinated and specific way to both the danger of oversupply of SAP soil amendments under water shortage conditions and an effective adaptation to a limited water supply with 3% BC and 0.1% SAP by increasing WUE and proline content. However, BC also had a mitigating effect on the level of reactive oxygen species (ROS). It can be assumed that this effect is based on a more plant-compatible, less one-sided ion composition of BC. The results presented indicate that SAP and BC can have an impact on the water and nutrient accessibility for plants. Therefore, optimal biomass production and plant response can only be reached if plant soil interactions and competition between SAP, BC and the plant roots are taken into account when planning for climate-resilient, water-saving agriculture. Full article

Human-driven soil erosion is a signal of the widely debated “Anthropocene”. There is widespread controversy regarding the time consistency and time transgression of human-driven soil erosion in the Late Holocene. In this study, three well-dated cores, B10, B14 and W20 from west to east, spanning the past 4–6 ka from the Pearl River Estuary (PRE) shelf, southern China, were selected for elemental tests. Principal component analysis divides the elements into four components. The first principal component (PC1) includes TFe₂O₃, Al₂O₃, V, Cs, Rb, Ga, TiO₂, K₂O, Ta, Nb, MnO, Th, LOI, and Cl, being the proxy for fine-grained terrigenous input and watershed soil erosion. The PC1 variations in B10 and B14 reveal that erosion enhanced at ~2.2 ka BP, and less erosion occurred at ~1.5 ka BP but has intensified since ~1.2 ka BP, which is consistent with the simulated cropland area of the Pearl River Basin and lake records in the upper West River, southwestern China. However, the records from the W20 reveal a continuous increase in terrestrial input since 2.2 ka BP, which is consistent with the soil erosion changes recorded by the South China coast lakes at its provenance region. Hence, differences in the initial age of the signals of human activities were revealed in the PRE shelf system. Our study not only reveals the time transgression of the “Anthropocene” boundary but also updates the sediment source-to-sink model of the PRE shelf system. Full article

In the long-term operation of canals in loess areas, instability and landslides frequently occur due to the effect of wetting–drying cycles, which severely restricts the long-term safe operation of engineering projects. To reveal the evolution law of loess strength under wetting–drying cycles and establish a strength prediction model, this study conducted wetting–drying cycle tests and direct shear tests, analyzing the effects of different cycle times, dry densities, and initial water contents on the shear strength and its parameters. A combined model of improved adaptive genetic algorithm and backpropagation neural network (IAGA-BP) was adopted for shear strength prediction. An adaptive crossover and mutation operator based on the Sigmoid function, which combines the fitness value with the population iteration number, was proposed. By optimizing the parent selection strategy and the uniform crossover genetic method, the population diversity was effectively maintained, and premature convergence was avoided. The test results show that with the increase in the wetting–drying cycle times, both the shear strength and strength parameters of loess exhibit a trend of gradual attenuation and eventually tend to be stable. The increase in the dry density and initial water content can reduce the degradation amplitude of soil cohesion after five wetting–drying cycles. The model verification results indicate that all evaluation indicators of the IAGA-BP neural network model (MAPE = 3.75%, MAE = 0.95 kPa, MSE = 9 × 10⁻⁴, R² = 0.975) are significantly superior to those of the traditional BP and GA-BP models, with the comprehensive prediction performance improved by 62% and 46%, respectively. This model not only effectively overcomes the defect that traditional models are prone to fall into local extremum but also shows significant advantages in prediction accuracy and convergence speed. This study can provide a theoretical reference for the calculation of loess strength degradation and the prediction of long-term stability under the environment of wetting–drying alternation. Full article

Unsymmetrical dimethylhydrazine (UDMH) serves as a high-performance liquid rocket propellant extensively utilized in the global aerospace industry, and its environmental release and leakage (particularly into soil systems) pose severe risks to ecological integrity and human health. As one of the few studies to quantitatively correlate soil physicochemical properties with UDMH degradation kinetics and pathway partitioning using controlled incubation experiments, this work aims to reveal the environmental hazards of UDMH in soil and provide a theoretical basis for subsequent remediation. The temporal degradation dynamics of UDMH in three comparative soil matrices (yellow-brown soil, red soil and black soil) were explored, correlations between soil physicochemical characteristics and UDMH degradation behavior were clarified, and UDMH degradation pathways were quantified. Headspace solid–phase microextraction (HS–SPME) was adopted as the pretreatment method, and gas chromatography–mass spectrometry (GC–MS) was used to identify UDMH and its transformation products (TPs) in soil incubation. From the GC–MS chromatogram, UDMH and its TPs—formaldehyde dimethylhydrazone (FDMH), acetaldehyde dimethylhydrazone (ADMH) and 1,1,4,4-tetramethyltetrazene (TMT)—were identified in the three soil matrices. UDMH underwent rapid degradation within the first 7 days of incubation, with degradation rates reaching 66.03%, 67.51% and 73.13% in yellow-brown soil (YS), red soil (RS) and black soil (BS), respectively. Degradation was most rapid in BS, followed by YS and RS. UDMH degraded completely and was undetectable within 30 days of soil incubation in the present study. Correlation analysis of soil physicochemical properties and UDMH degradation behavior revealed a significant influence of these edaphic properties on UDMH degradation dynamics across the tested soil matrices. The analysis of UDMH degradation pathways, including volatilization, photodegradation, microbiological degradation, and others (oxidation and self-degradation, etc.) demonstrated that other pathways (including catalytic transformation, induced transformation or unidentified biotic–abiotic coupled processes) acted as the dominant pathway governing its degradation (accounting for 68.75%). This study provides important insights and theoretical basis for unraveling the environmental fate of UDMH and remediating UDMH-contaminated soils. Full article

Monitoring soil contamination from petroleum products is vital for protecting human health and the environment. In forestry, hydraulic oil spills frequently result from leaks in equipment such as harvesters. This study evaluates a custom-built, inexpensive electronic nose, equipped with a Figaro TGS gas sensor array, for discriminating between pristine and contaminated soil samples. Two oil types and three pollution intensities were analyzed. The constructed electronic nose applied two sensor operation modes: (i) response to change of sensor operation condition from clean air to target odors and (ii) response to sensor heater temperature modulation. Classification was performed using Random Forest and Support Vector Machine (SVM) algorithms, and Linear Discriminant Analysis (LDA) was used to explore multidimensional data patterns. The sensor heater temperature modulation mode provided superior classification performance. Measurements at room temperature achieved an accuracy of 97%, clearly outperforming measurements on samples heated to 60 °C (75%). While the system successfully identified biodegradable oil contamination, standard mineral oil was more challenging to detect. Among the sensors tested, TGS 2602 was the most effective. These findings indicate that portable electronic noses can provide a statistically robust and cost-effective tool for assessing the severity of soil pollution. Full article

Climate change induced by greenhouse gas emissions is currently one of the most important challenges of the world. Against this backdrop, we deeply explore the temporal variation characteristics of vegetable production in Guangdong Province, a major province of China from the carbon footprint perspective. The aim is to promote the reduction of greenhouse gas emissions from agricultural production and carbon sequestration, as well as sustainable agricultural development. We primarily adopted the carbon emission coefficient provided by Intergovernmental Panel on Climate Change and utilized data from the China Rural Statistical Yearbook and the Guangdong Rural Statistical Yearbook from 1990 to 2022 to analyze the changing characteristics of the carbon footprint of vegetable production in Guangdong Province. In addition, we used the grey prediction model GM (1, 1) to estimate the parameters and test the residual. Then, the carbon emission of vegetable production in Guangdong province was predicted from 2023 to 2060. The research results show that agricultural input is the largest source of carbon emissions, accounting for 51.99–66.55%, followed by farmland soil utilization (33.45–48.01%). Within agricultural input, fertilizers, pesticides, and mulching films are the main sources of carbon emissions. Based on the data from 2011 to 2022, it is predicted that the net carbon emissions of vegetable production in Guangdong Province will continue to decline after 2022. Based on the above findings, it is suggested to promote the sustainable development of the vegetable industry by increasing policy support for the R&D and promotion of green and low-carbon technologies and green vegetable production, reducing agricultural input, and promoting the formation of the low-carbon production concept. Full article

Detecting trace metals in soil across geologically diverse terrains remains challenging due to complex mineral–metal interactions and the limited spatial coverage of traditional geochemical tests. This study develops a scalable VIS–NIR–SWIR spectroscopy and machine learning (ML) framework to predict and map soil concentrations of Cr, As, Cu, and Cd in the Aligudarz District, located within the geotectonically complex Sanandaj–Sirjan Zone of western Iran. Laboratory reflectance spectra (~350–2500 nm) obtained from 110 soil samples were pre-processed using derivative filtering, scatter-correction techniques, and genetic algorithm (GA)-based wavelength optimisation to enhance diagnostic absorption features linked to Fe-oxides, clay minerals, and carbonates. Multiple ML-based approaches, including artificial neural networks (ANNs), support vector regression (SVR), and partial least squares regression (PLSR), as well as stepwise multiple linear regression (SMLR), were compared using nested, spatial, and external validation. Nonlinear models, particularly ANNs, exhibited the highest predictive accuracy, with strong generalisation confirmed via an independent test set. GA-selected wavelengths and derivative-enhanced spectra revealed mineralogical controls on metal retention, confirming that spectral predictions reflect underlying geological processes. Ordinary kriging of spectral-ML residuals generated spatially consistent metal-distribution maps that aligned well with local and regional geological features. The integrated framework demonstrates high predictive accuracy and operational scalability, providing a reproducible, field-ready method for rapid geochemical assessment. The findings highlight the potential of VIS–NIR–SWIR spectroscopy, combined with advanced modelling and geostatistics, to support environmental monitoring, mineral exploration, and risk assessment in geologically complex terrains. Full article