Search Results (3,788)

The Mun River Basin, the largest Mekong tributary in Northeast Thailand, has experienced extensive agricultural expansion and forest decline, raising concerns over increasing soil erosion and sediment transfer. This study provides an integrated assessment of soil loss, sediment yield (SY), and sediment delivery ratio (SDR) across 19 sub-watersheds using the Universal Soil Loss Equation (USLE), field-based SY data, and multivariate statistical analyses in 2024. Basinwide soil loss was estimated at ~35 million t y⁻¹ (mean 4.96 t ha⁻¹ y⁻¹), with more than 80% of the basin classified in the no erosion to very low erosion classes. Despite substantial hillslope erosion, only 402,405 t y⁻¹ of sediment reaches the river network, corresponding to a low SDR of 1.15%, which falls within the range reported for large tropical watersheds with significant reservoir infrastructure. Soil loss is most strongly influenced by slope and forested terrain, while SY responds primarily to rainfall and tree plantations; urban land, croplands, and reservoirs act as sediment sinks. Principal Component Analysis (PCA) resolved multicollinearity and produced six components explaining over 90% of predictor variance. A PCA-based regression model predicted SY per unit area with high accuracy (r = 0.81). The results highlight the dominant roles of hydroclimate and land-use structure in shaping sediment connectivity, supporting targeted soil and watershed-management strategies. Full article

Large outcrops of ophiolites from exposed land surfaces can potentially impact the geochemistry of much greater areas through transport and weathering. Derived soil and sediments contain significant concentrations of heavy metals, including chromium and nickel. In the context of environmental risk analysis, there is a necessity to obtain more information about the distribution of Cr and Ni in serpentine rocks and their derived associated geological matrices, and about how easily Cr could be released and then oxidized in the environment, causing pollution of groundwater. The aim of this study was to evaluate the distribution of Cr and Ni in the geochemical fractions containing Fe and Mn and the role of Fe and Mn oxides (crystalline and non-crystalline) in redox processes leading to the formation of Cr(VI) during serpentine soil weathering. Through the combination of chemical selective sequential extraction (SSE) and X-ray diffraction, solid samples belonging to ophiolitic rocks and their derived soils and sediments in southern Tuscany were investigated. The applied SSE method followed the established extraction scheme commonly used in sequential selective extraction procedures. The extraction was accomplished in seven successive steps, using appropriate reagents to destroy the binding agents between the target metal and the specific soil fraction to release the heavy metals selectively from their structural context. The results indicated significant differences in the availability and mobility of Cr and Ni in soils, with Cr concentrations ranging from 200 to 950 μg/g and Ni from 274 to 665 μg/g in reactive fractions. Cr is tightly bound to well-crystallized Fe-oxides and primary rock-derived phases, whereas Ni is substantially more mobile, being mainly controlled by Mn-oxides and amorphous Fe-oxides. Weakly acidic solutions or systems with high redox potential increase Cr and Ni mobility in the environment due to Fe/Mn hydroxides produced by the weathering of serpentinites. An ORP higher than 1000 mV leads to the formation of Cr(VI) by oxidation of Cr(III), increasing the mobility of Cr in groundwater and the hazard for human health. The analytical activity carried out in this research can be used to identify the potential risk of Cr(VI) release in groundwater from serpentine and derived geomaterials. Full article

Land subsidence constitutes a critical hazard to coastal megacities globally, amplifying flood risks and damaging infrastructure. Taking Tianjin—a major port city underlain by compressible sediments and affected by groundwater over-exploitation—as a case study, we address two key research gaps: the absence of a quantitative framework coupling groundwater extraction with construction land expansion, and the inadequate separation of seasonal and long-term subsidence drivers. We developed an integrated remote-sensing-based approach: high-resolution subsidence time series (2016–2023) were derived via Small BAseline Subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) using Sentinel-1 Synthetic Aperture Radar (SAR) imagery, validated against leveling measurements (R > 0.885, error < 20 mm). This subsidence dataset was fused with groundwater level records and annual construction land maps. Seasonal-Trend Decomposition using Loess (STL) isolated trend, seasonal, and residual components, which were input into a Random Forest (RF) model to quantify the relative contributions of subsidence drivers. Dynamic Time Warping (DTW) and Cross-Wavelet Transform (CWT) were further employed to characterize temporal patterns and lag effects between subsidence and its drivers. Our results reveal a distinct shifting subsidence pattern: “areal expansion but intensity weakening.” Groundwater control policies mitigated five historical subsidence funnels, reducing areas with severe subsidence from 72.36% to <5%, while the total subsiding area expanded by 1024.74 km², with new zones emerging (e.g., northern Dongli District). The RF model identified the long-term groundwater level trend as the dominant driver (59.5% contribution), followed by residual (23.3%) and seasonal (17.2%) components. Cross-spectral analysis confirmed high coherence between subsidence and long-term groundwater trends; the seasonal component exhibited a dominant resonance period of 12 months and a consistent subsidence response lag of 3–4 months. Construction impacts were conceptualized as a “load accumulation-soil compression-time lag” mechanism, with high-intensity engineering projects inducing significant local subsidence. This study provides a robust quantitative framework for disentangling the complex interactions between subsidence, groundwater, and urban expansion, offering critical insights for evidence-based hazard mitigation and sustainable urban planning in vulnerable coastal environments worldwide. Full article

Conventional descriptive statistical approaches in per- and polyfluoroalkyl substance (PFAS) environmental forensics often fail under small-sample, ecosystem-level complexity, challenging the optimization of sampling, monitoring, and remediation strategies. This study presents an advance from passive description to adaptive decision-support for complex PFAS contamination. By integrating Bayesian optimization (BO) via Gaussian Processes (GP) with a Generalized Linear Mixed Model (GLMM), we developed a signal-extraction framework for both understanding and action from limited data (n = 18). The BO/GP model achieved strong predictive performance (GP leave-one-out R² = 0.807), while the GLMM confirmed significant overdispersion (1.62), indicating a patchy contamination distribution. The integrated analysis suggested a dominant spatiotemporal interaction: a transient, high-intensity perfluorooctane sulfonate (PFOS) plume that peaked at a precise location during early November (the autumn recharge period). Concurrently, the GLMM identified significant intra-sample variance (p = 0.0186), suggesting likely particulate-bound (colloid/sediment) transport, and detected n-ethyl perfluorooctane sulfonamidoacetic acid (NEtFOSAA) as a critical precursor (p < 0.0001), thus providing evidence consistent with the source as historic 3M aqueous film-forming foam. This coupled approach creates a dynamic, iterative decision-support system where signal-based diagnosis informs adaptive optimization, enabling mission-specific actions from targeted remediation to monitoring design. Full article

An ongoing challenge in pelagic oceanography and limnology is to quantify and understand the distribution of suspended particles and particle aggregates with sufficient temporal and spatial fidelity to understand their dynamics. These particles include biotic (mesoplankton, organic fragments, fecal pellets, etc.) and abiotic (dusts, precipitates, sediments and flocks, anthropogenic materials, etc.) matter and their aggregates (i.e., marine snow), which form a large part of the total particulate matter > 200 μm in size in the ocean. The transport of organic material from surface waters to the deep-sea floor is of particular interest, as it is recognized as a key factor controlling the global carbon cycle and hence, a critical process influencing the sequestration of carbon dioxide from the atmosphere. Here we describe the development of an oceanographic instrument, the Pelagic Laser Tomographer (PLT), that uses high-resolution optical technology, coupled with post-processing analysis, to scan the 3D content of the water column to detect and quantify 3D distributions of small particles. Existing optical instruments typically trade sampling volume for spatial resolution or require large, complex platforms. The PLT addresses this gap by combining high-resolution laser-sheet imaging with large effective sampling volumes in a compact, deployable system. The PLT can generate spatial distributions of small particles (~100 µm and larger) across large water volumes (order 100–1000 m³) during a typical deployment, and allow measurements of particle patchiness over spatial scales to less than 1 mm. The instrument’s small size (6 kg), high resolution (~100 µm in each 3000 cm² tomographic image slice), and analysis software provide a tool for pelagic studies that have typically been limited by high cost, data storage, resolution, and mechanical constraints, all usually necessitating bulky instrumentation and infrequent deployment, typically requiring a large research vessel. Full article

Cereal vinegar sediment (CVS), a byproduct of traditional vinegar fermentation, has been regarded as a health-promoting product. However, its role in genetically induced hyperlipidemia remains unclear. This study systematically evaluated the effects of Dade-CVS (DD-CVS) and Hengshun-CVS (HS-CVS) on apolipoprotein-E-deficient (Apoe^−/−) mice. Both CVS varieties significantly improve certain serological parameters of Apoe^−/− mice, although the overall impact on serum indicators remains limited. Nevertheless, 16S rRNA sequencing revealed that CVS treatment reshaped gut microbial communities to a notable extent. Compared with the Apoe^−/− mice, the DD-CVS treatment significantly increased the relative abundance of Dubosiella while reducing the genus Desulfovibrio, whereas the HS-CVS treatment inhibited the growth of Bifidobacterium and Akkermansia. The pathways predicted in the KO-DD group included vitamin, amino acid, and energy metabolism, while HS-CVS treatment was associated with bile acid biosynthesis and energy pathways. Metabolomic analysis showed that several key metabolites, including N1-acetylspermidine, succinic acid, and 25-hydroxycholesterol, were significantly altered following CVS supplementation. Correlation analysis revealed significant associations between serum indicators and these metabolites. Alistipes, Enterorhabdus, and Romboutsia were also correlated with serum indicators. Overall, these findings indicate that CVS primarily modulated the gut microbiota–metabolite axis and partial lipid modulation in hyperlipidemic mice. The study provides a reference for studies on the beneficial functions of CVS in hyperlipidemia. Full article

Effective management of water quality is critical for Litopenaeus vannamei aquaculture, yet it remains a significant technological hurdle for traditional farmers facing benthic anaerobiosis and toxic metabolite accumulation. This study introduces a novel approach by synergistically integrating calcium peroxide (CaO₂), titanium dioxide (TiO₂), and peracetic acid (PAA) encapsulated within Fe–alginate granules. Unlike conventional methods that treat oxygen depletion and toxicity separately, this composite is designed to simultaneously facilitate in situ oxygenation and advanced oxidation processes (AOPs) directly at the sediment–water interface. The physicochemical properties and radical generation mechanisms of the synthesized composites were characterized using FTIR, XRD, SEM, and ESR. In laboratory simulations of pond conditions, the synergistic efficacy of these composites was evaluated against critical parameters, including dissolved oxygen (DO), ammonia, and sulfide. Experimental results revealed that the application of 5 mg/L CP-T-PAA product to the sediment with an AOP system exhibited superior performance, generating the highest intensity of hydroxyl (•OH) and superoxide (•O₂⁻) radicals. This optimized treatment effectively maintained DO levels above ~2 mg/L at the sediment–water interface for 21 days (3 weeks) and achieved removal efficiencies of 94% for ammonia, 89% for sulfide, and 93% for turbidity. Multi-criteria decision analysis (TOPSIS) validated this formulation as the ideal solution. Consequently, this novel composite presents a sustainable, user-friendly strategy for enhancing environmental stability in traditional shrimp farming. Full article

Sediment transport in alluvial channels is strongly controlled by the grain-size distribution of bed and suspended materials. This, in turn, influences river morphology by modifying the cross-sectional area and course of the channel. Statistical parameters such as mean, standard deviation, skewness, and kurtosis provide quantitative indicators of the energy conditions that control sediment transport and deposition. This study examines the depositional characteristics of sediments in the Ganga River in Varanasi City, India, employing a novel combination of linear discriminant function (LDF) and sediment transport index (STI). The LDF results reveal distinct depositional environments: Y₁ and Y₂ values indicate deposition in a low-energy fluvial environment similar to beaches, Y₃ values suggest shallow marine settings, and Y₄ values point to mixed deltaic and turbid current depositional environments. Additionally, CM diagrams show rolling and suspension as the dominant sediment transport mechanisms. Shear stress analysis combined with STI highlights significant depositional features, with minimal erosion observed throughout the study area. The study provides an operational framework for mapping erosion-deposition patterns on alluvial point bars that are transferable to other sand-bed rivers worldwide where detailed hydraulic data are limited but detailed grain-size and DEM information are available. Full article

The homogeneity of methane hydrates in marine sediments plays a significant role in determining the efficiency of gas production during exploitation processes. Revealing their distribution mechanisms is crucial for optimizing the development of gas hydrates. This work systematically investigates the evolution patterns of effective thermal conductivity (ETC) during the formation and dissociation of methane hydrate in marine sediments, focusing on their major mineral components, such as quartz sand, illite, and montmorillonite. The results reveal the influence of thermal conductivity (TC) characteristics in porous media on hydrate phase transition behavior and spatial distribution. Key findings demonstrate that the TC characteristics of porous media are one of the dominant factors controlling hydrate formation rates. High-conductivity porous media significantly accelerate hydrate formation through efficient heat transfer. The swelling characteristics of montmorillonite and its coupling effects with salt ions impair heat transfer pathways, thereby inhibiting hydrate formation. Further analysis reveals that the spatial heterogeneity in reservoir TC is the primary intrinsic mechanism responsible for the macroscopic heterogeneous distribution of hydrates. Additionally, the hydrate dissociation process disrupts solid-state thermal bridging and generates gaseous thermal barriers, causing irreversible attenuation of reservoir TC. This phenomenon exacerbates the non-uniformity of the front during dissociation and increases the risk of secondary formation during exploitation. From a novel perspective of reservoir TC heterogeneity, this study establishes mechanistic links between the thermophysical properties of porous media and the spatial distribution patterns of hydrates. This provides significant theoretical guidance for resource exploration and the safe, efficient exploitation of marine gas hydrate reservoirs. Full article

The ancient city of Gela (built in the 7th century BCE) is located in the southern sector of the Sicily Island (Southern Italy) on a Pleistocene marine terrace near the mouth of the Gela River. Gela was one of the most important Greek colonies in the Mediterranean Sea, strategically positioned at the crossroads of the major maritime trade routes and with a rich production of cereals thanks to the fertile Gela River alluvial plain. To reconstruct the coastal and environmental configuration during the Greek period and to improve the understanding of the location of the harbour basin, a multidisciplinary approach was applied to a sector of the Gela River alluvial–coastal plain. This area, located very close to the ancient city, is known as Conca (Italian for “Basin”) and was identified through the analysis of historical and modern maps as well as aerial photographs. The multidisciplinary approach includes geomorphology (derived from maps and aerial photos), stratigraphy (boreholes and archeological trench), paleoecology (ostracoda, foraminifera and fossil contents of selected layers), geochronology (¹⁴C dating of selected organic materials) and archeology (historical sources and maps, pottery fragments extracted from boreholes and trench layers). The main results show that this area was occupied by lower shoreface environments in the time intervals between 4.4 and 2.8 ka, which progressively transitioned to upper shoreface environments until the Greek age. During the Roman period, these environments were significantly reduced due to repeated alluvial sedimentation of the Gela River transforming the area into fluvial–marshy environments. A time interval of aeolian sand deposition was recorded in the upper part of the coastal stratigraphical succession, which can be related to climatic conditions with high aridity. Available data show that marine environments persisted in the Conca sector during the Greek age, allowing hypothesizing the presence of an ancient harbour in this area. The depth of the Greek age marine environments is estimated to be between 4.5 and 7 m below the current ground level. Further investigation, mainly based on geophysical and stratigraphical methods, will be planned aimed at identifying the presence of buried archeological targets. Full article

Recycling wastewater from washing concrete trucks in concrete production addresses both economic and sustainability needs. In the present article, wastewater from washing concrete trucks was added to cement pastes made with two different types of cement for comparison. OPC type CEM I 42.5 was compared to pozzolanic cement type CEM IV/B (P-W) 32.5 in terms of hydration behavior and compressive strength development. The hydration of ordinary Portland cement (CEM I 42.5) was accelerated, while the hydration of pozzolanic cement (CEM IV 32.5) showed a relatively lower total normalized heat. Cement pastes were produced from both cement types, and compressive strength, thermal analysis, and setting time tests were performed for their characterization. The early-age kinetics and compressive strength development of CEM I 42.5 pastes indicate that hydration with wastewater leads to a slight increase in compressive strength. Test concrete prepared with pozzolanic cement (CEM IV 32.5) exhibited increased capillary voids, which contributed to less favorable mechanical and durability performance. Compared to the reference concrete, compressive strength was reduced by 7% at 28 days. Wastewater utilization increased the initial absorption rate by approximately 20%, but the calculated chloride content at the exposed concrete surface decreased after the addition of wastewater compared to the control mix. The carbonation depth of concrete with wastewater increased by 1–2 mm, with an uneven penetration zone, but the compressive strength after carbonation increased. Overall, the type of cement used appears to significantly influence the performance of concrete prepared with wastewater. For wastewater collected from sedimentation tanks, replacing fresh water at a 100% rate and using it with pozzolanic cement to produce concrete, it seems that the mechanical properties and durability are only slightly affected. Full article

Beach nourishment has become a globally adopted “soft” engineering measure to mitigate coastal erosion and sustain beach functions. This study conducts a systematic comparative analysis of beach nourishment practices between China and the United States, focusing on extensive project data and historical records. The research examines differences in historical development trajectories, spatial distribution patterns, restoration philosophies, funding mechanisms, and key technologies. The results reveal that the U.S., with over a century of experience, exhibits large-scale, high-frequency nourishment projects supported by diversified funding and long-term maintenance strategies. In contrast, China, despite a later start (circa 1992), has achieved rapid progress in both project scale and technical innovation, though its approach remains more government-led and structurally oriented. This study also identifies converging trends in resource concentration between the two countries, as measured by a proposed “beach nourishment primacy” index. Based on these findings, the work offers strategic recommendations for the coastal management of China, including the establishment of a national nourishment database, adoption of Regional Sediment Management, and greater integration of ecological engineering principles. This comparative analysis provides valuable insights for coastal nations seeking to optimize beach nourishment strategies in the face of growing climatic and anthropogenic pressures; to further advance these efforts, future research could explore the integration of interdisciplinary approaches and intelligent technologies, aiming to deepen our understanding of coastal system complexity and support the development of dynamic adaptive management. Full article

The valorization of dredged sediments represents a major environmental and logistical challenge, particularly in the context of forthcoming regulations restricting their marine disposal. This study investigates the potential of untreated dredged sediments as sustainable raw materials for geopolymer binder development, with the dual objective of sustainable sediment management and reduction in cement-related environmental impact. Dredged sediments from the Grand Port Maritime de Bordeaux (GPMB) were activated with sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃), both alone and in combination, with supplementary aluminosilicate and calcium-rich co-products, to assess their reactivity and effect on binder performance. A multi-scale experimental approach combining mechanical testing, calorimetry, porosity analysis, Scanning Electron Microscopy and Energy-Dispersive Spectroscopy (SEM–EDS), X-ray diffraction (XRD), Thermogravimetric Analysis (TGA), and solid-state Nuclear Magnetic Resonance (NMR) was employed to challenge the commonly assumed inert behavior of sediments within geopolymer matrices, to elucidate gel formation mechanisms, and to optimize binder formulation. The results show that untreated sediments actively participate in alkali activation, reaching compressive strengths of up to 5.16 MPa at 90 days without thermal pre-treatment. Calcium-poor systems exhibited progressive long-term strength development associated with the formation of homogeneous aluminosilicate gels and refined microporosity, whereas calcium-rich systems showed higher early age strength but more limited long-term performance, linked to heterogeneous gel coexistence and increased total porosity. These findings provide direct evidence of the intrinsic reactivity of untreated dredged sediments and highlight the critical role of gel chemistry and calcium content in controlling long-term performance. The proposed approach offers a viable pathway for low-impact, on-site sediment valorization in civil engineering applications. Full article

This study investigates the hydrography and geochemical signature in Ilha Grande Bay (RJ, Brazil), focusing on the seasonal intrusion of South Atlantic Central Water (SACW) and its interaction with lead sources. CTD (Conductivity, Temperature, and Depth) data revealed the presence of SACW during the summer campaigns (Mangaratiba/2011 and Frade/2012), characterized by temperatures below 20 °C and salinity between 34.6 and 36. The intrusion is driven by northeasterly winds that favor coastal upwelling, establishing a classic thermohaline stratification. The winter campaigns did not detect SACW, confirming its seasonal nature. Isotopic analysis of Pb in sediments identified six Pb²⁰⁶/Pb²⁰⁷ intervals, indicating multiple sources, including natural contributions, industrial waste, and urban effluents. The Pb²⁰⁶/Pb²⁰⁷ ranges were defined based on cluster analysis and frequency histograms, which are common methods in isotopic provenance studies. An overlap between the most radiogenic isotopic signatures and the presence of SACW suggests that this water mass acts as a vector for transporting trace elements from the deep oceanic region to the coast. This study provides the first evidence that the South Atlantic Central Water (SACW) acts as a seasonal vector, importing a distinct radiogenic Pb isotopic signature onto the continental shelf of Ilha Grande Bay. By synoptically coupling physical water-mass analysis (CTD) with Pb isotopic tracers, we introduce a novel approach that successfully discriminates oceanic from anthropogenic Pb sources, offering a new framework for understanding contaminant transport in coastal areas influenced by boundary currents. It is concluded that the coastal dynamics in Ilha Grande Bay are governed by the seasonal interaction of coastal, continental, and oceanic waters, and that the integration of physical and geochemical data is crucial for understanding mixing processes and contaminant transport in this complex environment. Full article

Integrated multi-trophic aquaculture (IMTA) has emerged as an ecological intensification strategy capable of enhancing nutrient utilization and improving environmental stability in mariculture systems, yet the microbial mechanisms driving nutrient transformations remain insufficiently understood. This study investigated how culture mode (IMTA vs. monoculture) shape water quality, sediment microbial communities, and nutrient cycling processes in a shrimp–sea urchin system by combining water-quality monitoring, nutrient analysis, 16S rRNA high-throughput sequencing, and redundancy analysis. IMTA significantly increased turbidity, chlorophyll-a, phosphate, ammonium, and nitrite compared with monoculture, while physico-chemical parameters remained stable. Sediment microbiota in IMTA exhibited substantially higher alpha diversity and showed a clear compositional separation from monoculture communities. At the genus level, IMTA sediments were enriched in Vibrio, Motilimonas, and Ruegeria, distinguishing them from monoculture systems. At the phylum level, IMTA was characterized by increased abundances of Proteobacteria and Bacteroidota, accompanied by a marked decline in Spirochaetota. Functional predictions indicated that microbial communities were predominantly characterized by pathways related to amino acid and carbohydrate metabolism, as well as nutrient remineralization. RDA and correlation analyses further identified turbidity, chlorophyll-a, phosphate, ammonium, and nitrite as the principal drivers of microbial divergence. Overall, the findings demonstrate that IMTA reshapes sediment microbial communities toward more efficient nutrient-processing assemblages, thereby promoting active nitrogen and phosphorus transformations and improving biogeochemical functioning relative to monoculture. These results provide mechanistic insight into how IMTA supports nutrient recycling and environmental sustainability in modern mariculture systems. Full article