Search Results (184)

This study investigates ground deformations in the southeastern Po Plain (northern Italy), focusing on the Bologna area—a densely populated region affected by natural and anthropogenic subsidence. Ground deformations in the area result from geological processes (e.g., sediment compaction and tectonic activity) and human activities (e.g., ground water production and underground gas storage—UGS). We apply a multidisciplinary approach integrating subsurface geology, ground water production, advanced differential interferometry synthetic aperture radar—DInSAR, gas storage data, and land use information to characterize and analyze the spatial and temporal variations in vertical ground deformations. Seasonal and trend decomposition using loess (STL) and cluster analysis techniques are applied to historical DInSAR vertical time series, targeting three representatives areas close to the city of Bologna. The main contribution of the study is the attempt to correlate the lateral extension of ground water bodies with seasonal ground deformations and water production data; the results are validated via knowledge of the geological characteristics of the uppermost part of the Po Plain area. Distinct seasonal patterns are identified and correlated with ground water production withdrawal and UGS operations. The results highlight the influence of superficial aquifer characteristics—particularly the geometry, lateral extent, and hydraulic properties of sedimentary bodies—on the ground movements behavior. This case study outlines an effective multidisciplinary approach for subsidence characterization providing critical insights for risk assessment and mitigation strategies, relevant for the future development of CO₂ and hydrogen storage in depleted reservoirs and saline aquifers. Full article

Dense aggregations of species in the family Pinnidae give soft substrata a specific characterization. They may influence the biological and physical properties of the surrounding sediments. Bottom-trawl samplings performed in the Sea of Marmara revealed populations of a large pinnid species, particularly at depths of 40–45 m in soft substrata. Both morphological and DNA analyses confirmed the species’ taxonomic identity as Atrina fragilis. This species had a population density ranging from 31 to 469 ind.km⁻², and the shell lengths ranged from 21.3 to 31 cm. A total of 47 macrozoobenthic species belonging to eight taxonomic groups were found on the shells of ten live and nine dead A. fragilis individuals. Polychaeta accounted for 53% of the total number of species and 75% of the total number of individuals. Among these species, Protula tubularia and Serpula concharum comprised almost 30% of all epifaunal populations. Community parameters changed according to the shell length and width. Different faunal assemblages were encountered on the shells. Given the ecological significance of A. fragilis as both a habitat-forming and sensitive benthic species, conservation measures should prioritize the protection of known habitats and the regulation of activities that lead to seabed disturbance. Full article

The growing mismatch between ecosystem service (ES) supply and demand underscores the importance of thoroughly understanding their spatiotemporal patterns and key drivers to promote ecological civilization and sustainable development at the regional level in China. This study investigates six key ES indicators across mainland China—habitat quality (HQ), carbon sequestration (CS), water yield (WY), sediment delivery ratio (SDR), food production (FP), and nutrient delivery ratio (NDR)—by integrating a suite of analytical approaches. These include a spatiotemporal analysis of trade-offs and synergies in supply, demand, and their ratios; self-organizing maps (SOM) for bundle identification; and interpretable machine learning models. While prior research studies have typically examined ES at a single spatial scale, focusing on supply-side bundles or associated drivers, they have often overlooked demand dynamics and cross-scale interactions. In contrast, this study integrates SOM and SHAP-based machine learning into a dual-scale framework (grid and city levels), enabling more precise identification of scale-dependent drivers and a deeper understanding of the complex interrelationships between ES supply, demand, and their spatial mismatches. The results reveal pronounced spatiotemporal heterogeneity in ES supply and demand at both grid and city scales. Overall, the supply services display a spatial pattern of higher values in the east and south, and lower values in the west and north. High-value areas for multiple demand services are concentrated in the densely populated eastern regions. The grid scale better captures spatial clustering, enhancing the detection of trade-offs and synergies. For instance, the correlation between HQ and NDR supply increased from 0.62 (grid scale) to 0.92 (city scale), while the correlation between HQ and SDR demand decreased from −0.03 to −0.58, indicating that upscaling may highlight broader synergistic or conflicting trends missed at finer resolutions. In the spatiotemporal interaction network of supply–demand ratios, CS, WY, FP, and NDR persistently show low values (below −0.5) in western and northern regions, indicating ongoing mismatches and uneven development. Driver analysis demonstrates scale-dependent effects: at the grid scale, HQ and FP are predominantly influenced by socioeconomic factors, SDR and WY by ecological variables, and CS and NDR by climatic conditions. At the city level, socioeconomic drivers dominate most services. Based on these findings, nine distinct supply–demand bundles were identified at both scales. The largest bundle at the grid scale (B3) occupies 29.1% of the study area, while the largest city-scale bundle (B8) covers 26.5%. This study deepens the understanding of trade-offs, synergies, and driving mechanisms of ecosystem services across multiple spatial scales; reveals scale-sensitive patterns of spatial mismatch; and provides scientific support for tiered ecological compensation, integrated regional planning, and sustainable development strategies. Full article

Increasing water scarcity in arid regions has prompted the mining industry to develop strategies to maximize water recovery and reuse, especially in tailings treatment processes. In this context, the present investigation evaluated the effects of sodium polyacrylate (NaPA) on the compressibility and viscoelasticity of clayey tailings in the presence of hard water containing calcium and magnesium. To this end, clayey slurries were analyzed using rheological tests (rheograms and oscillatory viscoelasticity), zeta potential measurements, and compressibility tests using batch centrifugation. The yield stress was determined using the Herschel–Bulkley model, while the compressive yield stress (Py(Φ)) was calculated as a key indicator to characterize the degree of sediment consolidation. The results showed that NaPA, due to its anionic nature and high degree of ionization at pH 8, induces effective particle dispersion by increasing electrostatic repulsion and decreasing the interaction force between particles, which reduces both rheological parameters and compressive yield stress. For the 70/30 quartz/kaolin mixture, the yield stress decreased from 70.54 to 61.64 Pa in CaCl₂ and from 57.51 to 52.95 Pa in MgCl₂ in the presence of NaPA. It was also observed that suspensions in the presence of magnesium ions presented greater compressibility than those with calcium, attributable to the greater hydration radius of magnesium (10.8 Å), which favors less dense and more easily deformable network structures. Furthermore, a higher proportion of kaolin in the mixture resulted in higher yield stresses, a product of the clay’s laminar structure, colloidal size, and high surface area, both in the absence and presence of NaPA. Overall, the results show that incorporating NaPA significantly improves the compressibility and rheology of clayey tailings in hard water, offering a promising alternative for optimizing water recovery and improving tailings management efficiency in the context of water restrictions. Full article

Water is scarce in semi-arid regions due to environmental limitations; this situation is aggravated by changes in land use and land cover (LULC). In this respect, the basic ecological functions of Permanent Preservation Areas (PPAs) help to maintain water resources. The aim of this study was to evaluate the relationship between the LULC and water quality in PPAs in a semi-arid watershed, from 2009 to 2016. The following limnological data were analyzed: chlorophyll-a, transparency, total nitrogen and total phosphorus. The changes in LULC were obtained by classifying images from Landsat 5, 7 and 8 into three types: Open Dry Tropical Forest (ODTF), Dense Dry Tropical Forest (DDTF) and Exposed Soil (ES). Spearman correlation and principal component analysis were applied to evaluate the relationships between the parameters. There was a significant positive correlation between DDTF and the best limnological conditions. However, ES showed a significant negative relationship with transparency and a positive relationship with chlorophyll-a, indicating a greater input of sediments and nutrients into the water. The PCA corroborated the results of the correlation. It is therefore essential to prioritize the preservation and restoration of the vegetation in these sensitive areas to ensure the sustainability of water resources. Future studies should assess the impact of specific human activities, such as agriculture, deforestation and livestock farming, on water quality in the PPAs. Full article

The Yangzhuang Formation of the Mesoproterozoic Jixian System exhibits a well-developed carbonate sedimentary sequence. However, the carbonate cycles within the Yangzhuang Formation and their co-evolution with paleoclimate and paleoceanographic environment changes remain insufficiently studied. This study conducts a systematic investigation of the rhythmic layers of the Yangzhuang Formation within the Yanshan Basin, North China, through major and trace element analysis, rare earth element analysis, inorganic carbon isotope analysis, granulometric analysis, and time series analysis. The results show that the low content of terrigenous clastics (11.2%~32.6%), slow sedimentation rate (2.2–2.5 cm/ka), Mg/Ca molar ratio close to 1 (1.05–1.53), and small fluctuation of δ¹³C_carb (−0.37‰~−0.05‰) in Member 3 of the Yangzhuang Formation constitutes the processes of co-evolution, along with a mid-phase fluctuation. It indicates the stable evolution of the sedimentary environment and slow ocean expansion speed. However, there is a fluctuating characteristic affected by the breakup of the Colombian supercontinent. The chemical and granulometric analysis of the red and gray layers shows that the terrigenous materials are mainly derived from the eolian sediments, with differences in the wind carrying materials. The time series analysis of the dense samples displays the coupling between the rhythm of the red and gray layers, the inorganic carbon isotope cycle, and the 15 ka precessional cycle in the Mesoproterozoic. We conclude that the rhythm of layers is mainly affected by the monsoon change driven by low-latitude solar radiation at that time, and the age of the Yangzhuang Formation is limited to 1550~1520 ± 2 Ma. The study of the Mesoproterozoic sequence using geochemical data from carbonate deposits reveals the underlying mechanism of global co-evolution during this period, providing a basis for understanding the evolution of the Mesoproterozoic Earth system. Full article

This study quantifies morphological features of global braided river deltas using Google Earth imagery, analyzing eight systems (e.g., Yukon–Kuskokwim, Poyang Lake, Lena River deltas). Methods include listwise deletion for missing data (retaining 87% of Poyang Lake delta samples) and sensitivity analysis (threshold changes ≤2.4%). Nonparametric tests (Kruskal–Wallis, H = 12.73, p = 0.005) show significant differences in bifurcation angles across deltas, with the wave-dominated Po River (59.2°) having an 18% higher 80% threshold the than tide-dominated Poyang Lake (50.1°, p = 0.003). Key quantitative results include the following: 1.65% of bifurcation angles cluster at 30–60°, differing from fan deltas (p < 0.01); wavelength–amplitude relationships are nonlinear (R² = 0.537–0.913), with positive slopes indicating a high sediment supply (e.g., Yukon–Kuskokwim) and negative slope channel avulsion (e.g., Poyang Lake); bifurcation spacing correlates with the sediment supply—54% of Poyang Lake spacings < 2000 m (dense networks) vs. 80% of Lena River spacings < 15,000 m (stable channels). The resulting dataset enables global, remote-sensing-based comparisons, providing thresholds for sedimentary modeling and reservoir prediction. Moderate missing data (≤13%) minimally affect results, though high-missingness cases need further analysis. This study replaces empirical rules with statistical validation, showing that morphometric differences reflect depositional dynamics, which are critical for reservoir heterogeneity assessments. Full article

This study assesses the risks of glacial lake outburst floods (GLOFs) from moraine sediment dams around Gurudongmar Lake in the Northern Sikkim Himalayas at an elevation of 17,800 feet. It focuses on three moraine sediment dams, analysing the implications of slope failure on the upstream side and the downstream stability under steady seepage conditions, as well as the risks posed by permafrost thawing. Using a comprehensive methodology that includes geotechnical evaluations, remote sensing, and digital elevation models (DEMs), the research employs finite element analysis via PLAXIS2D for the stability assessment. The main findings indicate a stratification of sediment types: the upper layers are loose silty sand, while the lower layers are dense silty sand, with significant variations in shear strength, permeability, and other geotechnical properties. Observations of solifluctions suggest that current permafrost conditions enhance the dams’ stability and reduce seepage. However, temperature trends show a warming climate, with the average days below 0 °C decreasing from 314 (2004–2013) to 305 (2014–2023), indicating potential permafrost thawing. This thawing could increase seepage and destabilise the dams, raising the risk of GLOFs. Numerical simulations reveal that scenarios involving water level rises of 5 and 10 m could lead to significant deformation and reduced safety factors on both the upstream lateral dams and downstream front dams. The study emphasises the urgent need for ongoing monitoring and risk assessment to address the potential hazards associated with GLOFs. Full article

The present study focuses on the sources and spatial distribution of potentially toxic elements (PTEs) and organic pollutants in water, canal bed sediment, and soil in the Versiliana urban park, an inclusive green area near the coast in the densely populated Versilia Plain of Tuscany. Surface water and bed sediments from canals crossing the urban park were collected at 10 stations during four different surveys to account for hydrological seasonality. Groundwater was collected in a survey through 10 piezometers. Eleven shallow soil samples were also collected, with the aim of evaluating the potential release of pollutants. Groundwater ranged from Ca-HCO₃, to NaCl, CaCl₂, and Na-HCO₃ water types, indicating conservative mixing and cation exchange processes during seawater intrusion. Most waters from canals belonged to the Ca-HCO₃ hydrofacies; a salinization shift, due to hydraulic connection with saline groundwater and soil sea salt dissolution, is observed. The concentration of most PTEs in groundwater and canal water is below Italian regulatory thresholds, with the only exception being As, which exceeds the legal limit in some samples. In most sediments, Ni, Cr, Zn, and As exceed the threshold effect concentration, and in some cases, the probable effect concentration. Geogenic PTE sources are attributed to metalliferous mineralization that characterizes the upstream Versilia River basin catchment. However, local PTE inputs from vehicular emissions and local industrial activities have been highlighted. Arsenic in sediments originated from geogenic sources and from arsenical pesticides, as indicated by the analysis of organic compounds, highlighting the legacy of the use of organic pesticides that have settled in bed sediments, in particular malathion and metalaxyl. The arsenic risk-based screening level in soil is lower compared with the regulatory threshold and with the measured concentration. Full article

This study presents a novel unresolved SPH-DEM coupling framework to investigate the complex interactions between rising gas bubbles and sinking solid particles in multiphase systems. Traditional numerical methods often struggle with large deformations, multiphase interfaces, and computational efficiency when simulating dense particle-laden flows. To address these challenges, the proposed model leverages SPH’s Lagrangian nature to resolve fluid motion and bubble dynamics, while the DEM captures particle–particle and particle–bubble interactions. An unresolved coupling strategy is introduced to bridge the scales between fluid and particle phases, enabling efficient simulations of large-scale systems with discrete bubbles/particles. The model is validated against benchmark cases, including single bubbles rising and single particle’s sedimentation. Simulation studies reveal the effects of particle/bubble number and initial distance on phase interaction patterns and clustering behaviors. Results further illustrate the model’s capability to capture complex phenomena such as particle entrainment by bubble wakes and hindered settling in dense suspensions. The framework offers a robust and efficient tool for optimizing industrial processes like mineral flotation, where bubble–particle dynamics play a critical role. Full article

To create an orthodontic bracket material combining the favourable properties of ceramic and polymer while minimising their limitations, graded porous ceramic scaffolds were created using unidirectional gelation-freeze casting, following which the pores were infiltrated with polymer. Two processing parameters were investigated: (1) sedimentation times of 0, 8, and 24 h, with ceramic solid loading of 20 vol.% and 2.5 wt.% gelatine concentration, and (2) ceramic solid loadings of 15, 20, and 25 vol.% with a fixed 2.5 wt.% gelatine concentration and an 8 h sedimentation time. The graded ceramic structures demonstrated porosity gradients ranging from 9.86 to 63.84 vol.%, except those with 25 vol.% ceramic solid loading at 8 h sedimentation. The Al₂O₃-UDMA/TEGDMA composites had compressive strengths of 60.25 to 120.92 MPa, modulus of elasticity of 19.84 to 35.29 GPa, and fracture toughness of 0.78 to 1.78 MPa·m^1/2. The values observed were between those of dense ceramic and pure polymer. Statistical analysis was conducted using Excel^® 2019 (Microsoft^®, Washington, DC, USA). Means, standard deviations, and 95% confidence intervals (CI) were calculated at a significance level of α = 0.05, alongside polynomial regression to evaluate relationships between variables. Composites with 20 vol.% ceramic solid loading at 8 h sedimentation displayed promising potential for further clinical validation. Full article

This Study delves on changes in the extent of mangroves over a 42 years span in the Douala-Edea NP, Cameroon. Mangroves are valuable ecosystems that provide significant biological, environmental, ecological, and cultural functions. To inform the development of management plans for the ecosystem’s sustainability, it is crucial to evaluate how their land cover, levels of degradation, and phases of restitution have changed. GIS and remote sensing techniques were used to classify and analyze Landsat images from 1980 to 2022 categorized into nine classes: bare ground, Nypa palms, settlements, coastal sedimentation, river sedimentation, regeneration, matured mangroves, dense forest, and water body. Using the Markovian chain approach, the changes noted during the period were utilized to forecast future trends up to 2052. Findings demonstrated that the mature mangrove area decreased throughout the study. The surface area covered by mature mangroves was 80,628.78 hectares in 1980, which decreased by 7.31%, 1.51%, 3.70%, and by 17% for the overall period of 42 years. Additionally, a gain of 6.84% from 1980 to 2022 was observed, probably from artificial mangrove regeneration. Settlements, invasive Nypa palms, bare ground (resulting from over-exploitation), and the sedimentation of rivers and coast primarily replaced mangroves. The prediction derived indicated the continuous decline in mangroves if not fully protected by law. The gazettement to National Park and recent promulgation of two laws are steps in providing the needed protection. These results provide vital information to direct future mangrove conservation actions in the recently gazetted Douala-Edea National Terrestrial and Marine Park and other mangrove blocks along the Gulf of Guinea. Full article

Organic matter (OM)-hosted pores play a crucial role in unconventional shale reservoirs, with their development influenced by OM type and thermal maturity across terrestrial, transitional, and marine deposits. In this study, a comparative analysis of porosity and pore structures is presented using organic petrographical, petrophysical, and mineralogical methods on organic-rich samples from diverse depositional environments. A pore evolution model for these sediments in different settings is proposed. Results show that kerogen particles in terrestrial shales at low and moderate thermal maturity (Dameigou Formation and Qingshankou Formation) are mostly nonporous. Transitional shales (Longtan Formation) contain vitrinite and inertinite, with only some inertinite exhibiting visible primary pores. In marine shales at higher maturity (late oil window; Dalong Formation), the interparticle pore space is occupied by solid bitumen, and secondary porosity is present at higher maturity, approaching the thermal gas generation stage. In over-mature marine shales (Wujiaping and Daye Formations), secondary pores are densely distributed within pyrobitumen. A negative correlation between organic carbon content and pore volume is observed in low-maturity lacustrine and transitional shales due to poorly developed kerogen-bound pores and interparticle pore occlusion by solid bitumen. However, over-mature marine shales exhibit a strong positive correlation due to extensive secondary porosity in pyrobitumen. Thus, pore evolution within OM is controlled by kerogen type and maturity. In oil-prone marine and lacustrine shales, secondary porosity in solid bitumen and pyrobitumen increases with thermal maturity. In contrast, terrestrial kerogen rarely forms solid bitumen and mainly develops micropores rather than mesopores at high maturity. Full article

Physical soil crust (PSC) is a dense structural layer formed on the surface of bare or very low-cover land due to raindrop splashes or runoff. The formation of crust changes the properties of the soil and strongly affects water infiltration and runoff and sediment production processes on slopes. The irrational use of soil and water resources and frequent human production activity under the influence of urbanization increase the possibility of inducing erosion. Studying the formation and structural characteristics of PSC to predict terrestrial hydrological processes and improve models for predicting erosion is very important. Many studies of PSC have been carried out in China and abroad, but they are mainly unilateral discussions of the basic properties and characteristics of crust and its effects on runoff and sediment yield on slopes. Studies systematically analyzing and synthesizing the progress of crust research, however, are lacking. By reading the literature and analyzing the developmental history of PSC, we provide a comprehensive review of the following: (1) the meaning, main types, and classification of PSC, (2) the mechanism of formation and the characteristics and dynamic development of crust, (3) the factors affecting the formation of crust, including natural and anthropogenic factors and comprehensive effects, and (4) the development and formation of crust in the soil environment, i.e., hydrological processes and erosion. We also summarize the potential directions for future research on PSC: (1) studying the dynamics of soil structure during the development of crust, (2) developing an objective and standardized quantitative method for studying crust formation, (3) using models of erosion influenced by crust development, (4) improving the scale of the degree of crust development and structural characteristics, and (5) rationalizing the management of crust to optimize land structure and increase crop yield. Full article

Urbanization and the expansion of impervious surfaces have increased stormwater runoff volumes, altered runoff timing, and degraded water quality and aquatic ecosystems. Runoff from urban areas carries pollutants such as nitrogen, phosphorus, sediments, and heavy metals, which can adversely impact the physical characteristics of receiving waterbodies. Stormwater management programs aim to mitigate these effects using Best Management Practices (BMPs) to retain and treat stormwater on-site. However, in densely developed areas, space constraints and high costs often make traditional BMPs impractical. This study assessed the effectiveness of expanded shale, an engineered material, as a filtration medium in bioswales, a type of linear BMP commonly used in transportation infrastructure. Thirty scenarios were tested in a 16 ft (4.9 m) long plexiglass flume using expanded shale mixed with sandy clay soil. Due to the limited scope of this study, it focused on assessing the effectiveness of expanded shale in removing suspended sediments and reducing turbidity. Results showed that expanded shale achieved removal efficiencies ranging from 20% to 82% for total suspended solids (TSS) and −4% to 61% for turbidity under different conditions. It outperformed conventional filtration materials such as sand and gravel, requiring less channel length. Remarkably, even in a small-scale laboratory setting, expanded shale met the suspended sediment removal standard of 80%, demonstrating its potential as a highly effective filtration material alternative for urban stormwater management. Full article