Search Results (2,360)

Microplastic (MP) analysis in various environmental media currently faces significant challenges due to the complex and transportable nature of these materials. This study employed Fourier-transform infrared spectroscopy (FTIR) to investigate the presence of MPs in caddisfly larval cases, which incorporate vegetative fragments, sediment grains, and MP particles as building materials. The analysis of MPs in 2049 caddisfly larval cases revealed a total of 7553 items, resulting in an average of 3.7 items/case. The lowest recorded rate was 0.8 items/case, while the highest reached 18.2 items/case. Fiber MPs comprised 39.2% of the total, followed by fragment MPs at 30.8% and spherical MPs at 30%. Among the colors analyzed, blue MPs were the most prevalent, accounting for 36.6%, with white/transparent MPs at 22.1% and red MPs at 14.1%. MPs smaller than 100 µm were the most common, accounting for 37%, followed by MPs in the 100–250 µm range at 23.9%, larger than 500 µm at 22.3%, and those between 250 and 500 µm at 15.8%. Cellulose acetate was discovered to be the most abundant MP among different polymer types, followed by cellulose acetate butyrate, polyethylene terephthalate, poly(vinyl propionate), poly(ethylene glycol), poly(acrylonitrile-co-butadiene), cellulose propionate, hydroxyethyl cellulose, polyvinyl alcohol, glycerol triacetate, polystyrene, and poly(propylene glycol) methacrylate. These findings show the existence of MP in biotic components of these ecosystems, which has implications for aquatic biota health and freshwater quality, particularly in places influenced by human activity. Full article

Landslide-induced surges and subsequent dam breaching constitute severe cascading hazards in mountainous gorges. Conventional steady-flow sediment theories fail to describe these extreme, unsteady processes, and existing research focuses on wave propagation rather than surge-driven erosion mechanisms. Using the Baige landslide dam as a prototype, this study combines 1:100 physical model tests with CFD-DEM simulations to investigate how landslide fall height, water depth, and sediment gradation govern surge propagation, dam scour, and sediment transport. The results show the surge amplitude reaches 38.21 cm under high-fall, deep-water conditions and decays nonlinearly. Fine-grained beds exhibit suspended-load transport (max concentration 15.2%), whereas coarse-grained beds develop scour pits via bedload transport, with deposition volume increasing ~230%. Sediment transport follows a three-stage spatial pattern: intense erosion near the dam (max depth 2.9 cm), grain-size-sorted deposition in the middle reach (max height 4.6 cm), and fine-sediment accumulation downstream. The numerical results agree well with experiments. The constructed “water depth–gradation–energy” risk assessment matrix supports refined prediction and mitigation of landslide dam-break cascading hazards. Full article

Siltation in semi-enclosed basins is commonly ascribed to the combined action of horizontal entrainment, tidal filling/emptying, and density flow, yet the interplay among these processes complicates a mechanistic understanding of siltation in artificially modified macrotidal bays. In this study, Dyer’s decomposition method for suspended sediment flux (SSF) and end-member analysis (EMA) were applied, combined with in situ hydrodynamic, suspended sediment concentration (SSC), and surface sediment grain-size measurements. Using Wuyuan Bay (Xiamen, China) as a case study, we examined its sediment dynamics and siltation patterns from a tidal-cycle perspective. Results show that the contribution of density flow is negligible. A recirculating gyre, formed during flood and suppressed during ebb, creates flood–ebb velocity asymmetry and net landward sediment transport, producing a central siltation body (CSB) that accounts for 45% of the total deposition. Near the entrance, Eulerian residual transport (gyre advection) dominates, with a notable contribution from tidal pumping. Further landward, tidal pumping weakens and gyre-induced Eulerian transport prevails. Grain-size analysis and EMA decomposition reveal uniform sedimentary dynamic conditions in this zone, with flood-phase deposition averaging 83% of the total siltation. Full article

As critical infrastructure for carbon capture, utilization, and storage (CCUS) and large-scale energy storage, subsurface salt caverns are seriously challenged by fluid-induced sediment mobilization during the supplementary debrining. Conventional bulk resin consolidation often causes severe viscous fingering, uneven consolidation, and pore clogging under hypersaline conditions. Here, we develop a foam-templated hybrid polymer gel co-stabilized by silica nanoparticles, polyvinyl alcohol, and the zwitterionic surfactant. The key novelty is the use of foam as a transient transport template that redistributes the resin phase and promotes selective cementation at grain-contact points instead of indiscriminate pore filling. This nano-reinforced gel system remained stable under hypersaline conditions (24% NaCl), and temperatures ranging from 20–80 °C. Micro-CT analysis showed that this selective templating preserved an interconnected pore network with a porosity above 45% and a CT-derived permeability of approximately 1.18 D, while reducing binder consumption by 55.6% relative to bulk resin injection. Crucially, a 1:200 geometrically scaled, velocity-matched pilot model demonstrated that this gel strategy limited sediment entrainment below 0.5% and reduced fluid discharge by 45.9%. These results establish a material-efficient consolidation strategy that combines sediment stabilization with permeability preservation, providing a promising solution for safer supplementary debrining in salt-cavern CCUS and energy-storage operations. Full article

Recent advances in numerical modelling, remote sensing, and artificial intelligence are bringing a transformation in our ability to assess sediment transport. Nevertheless, climate change is fundamentally altering sediment production, transport, and deposition through intensifying hydrological extremes, sea-level rise, changing storm regimes, cryosphere degradation, and increasing human modification of sediment pathways. These interacting drivers challenge conventional sediment transport assessment, which has largely evolved within separate fluvial, estuarine, coastal, and marine disciplines and often lacks an integrated perspective capable of representing source-to-sink sediment connectivity under non-stationary environmental conditions. Although significant advances have been made in process-based numerical modelling, Earth observation, and artificial intelligence (AI), these approaches are commonly reviewed independently, limiting their collective application to regional climate-responsive sediment assessment. This review examines state-of-the-art process-based numerical models, observational tools, and machine-learning approaches for sediment transport from source-to-sink. A transparent benchmarking scheme is used to compare leading modelling systems (e.g., AdH, SRH-2D, FLO-2D, HEC-RAS, TELEMAC, Delft3D, EFDC, SCHISM, XBeach, ROMS), highlighting differences in dimensionality, sediment-process representation, computational demands, and climate-scenario readiness. Remote sensing (optical, SAR, LiDAR, UAV) and AI/ML/DL methods (e.g., random forests) are reviewed as complementary tools that enhance model parametrization, improve validation, and address uncertainty in data-limited regions. A reproducible bibliometric synthesis based on Dimensions.ai records (2000–2026) reveals accelerating growth in sediment-transport research, with strong recent expansion in coastal, estuarine, and data-driven modelling applications. Major challenges include cohesive sediment physics, cross-environment coupling, limited long-term validation datasets, and the need for scalable workflows compatible with climate-model forcing. In this manuscript, we analyse and propose a future roadmap for near-term integration of satellite–field data streams, medium-term development of hybrid physics–AI models, and long-term coupling of sediment modules within Earth-system and regional climate frameworks. Collectively, this review provides a foundation for next-generation, climate-responsive sediment transport assessment supporting sustainable river basin and coastal management. Full article

Bottom currents and their associated sedimentary structures are key agents in shaping deep-sea morphodynamics, among which the genesis of seafloor undulations is still debated, restricting engineering risk assessment and resource development safety. Based on high-resolution multibeam bathymetry, sub-bottom profiles, and near-bottom current observations, this study analyzes morphological characteristics, internal reflection structures, and near-bottom current dynamic processes of seafloor undulations in the Shenhu canyon area. The results indicate that undulations occur at canyon heads, canyon interfluve, and east side of canyon. The undulations are generally characterized by vertical aggradation, with some sediment waves exhibiting directional crestline migration accompanied by wave merging, indicating the existence of persistent sediment transport processes. Within the canyon, the flow is concentrated and exhibits significant vertical deflection, reflecting the pronounced flow-guiding effect of the confined topography on near-bottom currents, which consequently controls the lateral migration of crestlines on both sides of the canyon and the shaping of seafloor undulations at canyon heads by internal tides. In contrast, in the relatively open canyon interfluve, flow directions are more dispersed, predominantly characterized by weaker currents. These findings contribute to the understanding of deep-water sedimentary dynamic processes and provide a reference for interpreting the genesis of similar deep-water seafloor undulations. Full article

Located 30 km south–southeast of Kabul in Logar province, Aynak is the largest and best-known copper orebody in Afghanistan. The deposit is hosted by the Loy Khwar Formation, a Neoproterozoic–Cambrian metasedimentary sequence of dolomite marble, carbonaceous quartz schist and quartz–biotite–dolomite schist. The primary ore minerals are chalcopyrite and bornite, with less abundant pyrite and minor cobaltite, chalcocite, pyrrhotite, sphalerite and molybdenite. Sulphides occur as bedded laminae and disseminations, in metamorphic segregations, and in syn- to post-metamorphic cross-cutting veins. Building on the mineralogical, lithogeochemical and sulphur isotope framework established by Waizy et al. (2020), ICP-MS analyses of sulphide-rich separates from Central and Western Aynak (n = 31) were undertaken to characterise trace-element distributions, evaluate possible metal sources, and further constrain the genetic model of the deposit. Co and As enrichment in chalcopyrite-dominant samples is consistent with cobaltite, whereas Co enrichment in the absence of arsenic suggests the possible presence of carrollite. Fluid inclusion analyses of secondary quartz-hosted inclusions indicate interaction between the Aynak deposits and saline aqueous fluids (32 to 47 equivalent wt% NaCl) at minimum P-T conditions of ~100–200 MPa and 300 °C. It is uncertain whether these fluid parameters relate to primary copper transport and deposition, or to remobilisation during metamorphism. Nevertheless, comparison with analogous sediment-hosted copper deposits suggests that highly saline basinal brines played an important role in the formation and evolution of the deposit. Occurrences of scapolite provide additional evidence for a model of brine-related mineralisation. Together with previously published mineralogical, lithogeochemical and sulphur isotope evidence, these findings support a sedimentary–diagenetic origin for the Aynak copper deposit that is broadly comparable with sediment-hosted stratiform copper systems of the Central African Copperbelt. Full article

Changes in river channel morphology under the influence of natural and anthropogenic factors pose a serious threat to the stability of aquatic ecosystems and water resource use, especially in regions with limited hydrological information. This study presents, for the first time, a three-dimensional numerical investigation of channel processes in the Talas River (Kazakhstan), employing the Volume of Fluid (VOF) method for free-surface flow simulation and a non-Newtonian model for sediment transport and riverbed morphodynamics. To verify the developed mathematical model, experimental data on the flow in the L-shaped channel and Earthfill dam break were used, which provided high reliability of the calculated results. The calculations showed a significant increase in the channel area in the studied section of the Talas River (from 41,334.92 m² to 56,890.17 m²) for the period from 2019 to 2024, mainly due to the intensification of the dynamics of currents and the formation of additional vortex zones with a diameter of 50 to 200 m. It was found that in places of local flow acceleration, water velocity increased up to 4.5 m/s, leading to bank erosion and channel widening, whereas after redistribution of channel flows, the maximum velocity decreased to 2.8 m/s, ensuring stabilisation of morphological changes. The results of the study underline the need for an integrated approach to river morphodynamics management using numerical modelling to predict channel changes, minimise flood risks and optimise the use of water resources. The presented computational approach can be adapted to analyse hydrodynamic processes in other poorly studied river systems, which significantly expands its scientific and practical value. Full article

Submarine groundwater discharge (SGD) is an important pathway of dissolved matter transport to coastal ecosystems, yet its identification in methane seep environments remains challenging because chemical signals are modified by sedimentary biogeochemical processes. This study evaluated hydrochemical tracers of SGD in methane seep sites, bacterial mat areas, and background sediments along the southern coast of Crimea (Black Sea). The studied settings exhibited distinct water chemical characteristics. Chloride concentrations decreased from 10.6 to 11.2 g L⁻¹ in background waters, to 8.7–9.3 g L⁻¹ in bacterial mat pore waters and to 7.7 g L⁻¹ in sediment–water interface waters, indicating the presence of a low-salinity water component. Dissolved silica increased by approximately one order of magnitude relative to background values at methane-associated sites. Methane concentrations ranged from 0.025 to 1058 μM, with the highest values occurring in bacterial mat areas. These zones were further characterized by sulfate depletion (down to 0.9 g L⁻¹), elevated normalized alkalinity, ammonium concentrations reaching 8000 μg L⁻¹, high sulfide contents, and low dissolved Fe concentrations consistent with iron sulfide precipitation. The results demonstrate that no single hydrochemical parameter is sufficient to identify SGD in methane-affected coastal sediments. Instead, the combined use of conservative tracers (Cl⁻ and DSi) and reactive constituents (SO₄²⁻, alkalinity, NH₄⁺, HS⁻, TDFe, and Mn²⁺) provides a robust hydrochemical framework for recognizing groundwater influence and evaluating associated biogeochemical transformations. Full article

Pumping stations serve as critical hydraulic infrastructure for water conveyance and irrigation. Sediment deposition in forebays can deteriorate intake flow conditions, increase hydraulic losses, reduce pumping efficiency, and consequently impair the long-term operational performance of pumping systems. To accurately predict sediment deposition in complex three-dimensional flow fields, we developed a dynamics-driven boundary-responsive numerical model that integrates sediment particle dynamics with real-time bed evolution. This model adopts the near-bed vertical velocity of sediment particles as the deposition discrimination criterion and dynamically updates bed topography via a mass-conservation-based boundary response strategy. The proposed method was validated against open-channel experimental data. The simulated flow structures, deposition patterns, and temporal variations in deposition thickness agreed well with the measurements, with average deviations below 4%. Compared with conventional static-boundary numerical methods, the proposed model reproduces the coupled evolution of sediment transport, flow redistribution, and bed deformation with higher fidelity. The developed framework provides an effective numerical tool for sediment deposition prediction and offers practical support for hydraulic structure optimization, maintenance scheduling, and energy-efficient operation of pumping stations with sediment-laden flow. Full article

River avulsion, the sudden relocation of a river channel to a new course from the parent channel, is a geomorphic process with direct implications for floodplain evolution, ecosystem dynamics, and infrastructure vulnerability. This review article discusses how sandbar migration acts as a precursor to avulsion by altering hydraulic geometry, redirecting flow paths, modifying sediment transport patterns, and affecting the development of incipient channels. The morphodynamic evolution of sandbars, influenced by sediment supply, flow regime, vegetation, and anthropogenic influences, such as dams and sand mining, plays a central role in creating avulsion. Different methods, such as field measurements, remote sensing imagery (including multispectral, SAR, LiDAR and UAV), physics-based numerical models, machine learning, and deep learning techniques, which are used to evaluate river sandbar and river avulsion, are also thoroughly evaluated for efficacy and fit for purpose. Future research should focus on combining different data sources and creating a model that understands vegetation–sediment–flow feedbacks, sediment sorting process, anthropogenic impacts and extreme climate change impacts on channel evolution. Full article

The discharge of metal-rich mining effluents and waste into marine environments represents a significant environmental challenge, with impacts extending from coastal to deep-sea ecosystems. This study presents a scoping review conducted in accordance with PRISMA-ScR guidelines to identify, classify, and synthesise evidence on the effects of large-scale mining waste disposal in coastal and marine settings. Searches of Web of Science, Scopus, and relevant grey literature sources yielded 147 eligible publications from an initial dataset of 563 records. The evidence reviewed enabled the identification of 81 distinct impacts systematically grouped into nine primary categories spanning physical, geotechnical, hydrodynamic, geochemical, biological, ecological, and socio-economic dimensions. Marine tailings deposits behave as dynamic systems that facilitate the transport of contaminants beyond disposal sites through processes such as plume dispersion, sediment resuspension, turbidity currents, and porewater exchange. Geochemical reactions and geotechnical failures can increase environmental vulnerability, a risk further exacerbated by ocean warming, acidification, and changing circulation patterns. Beyond highlighting the need for precautionary, integrated, and adaptive management approaches, this review provides the first comprehensive global inventory of impact categories and assessment factors associated with marine mining waste disposal, establishing a reference framework to guide future research, environmental management, regulatory evaluations, and industry decision-making. Full article

This study aims to spatially analyze the potential soil loss rates of the Özkonak Watershed, located within Nevşehir Province, using the Revised Universal Soil Loss Equation (RUSLE) integrated with Geographic Information Systems (GIS) and Remote Sensing (RS) technologies. In the 149.9 km² watershed, the main parameters triggering erosion—rainfall erosivity (R), soil erodibility (K), slope length and steepness (LS), land cover and management (C), and support practices (P)—were modeled in a GIS environment. According to the spatial analysis results, 85.8% of the watershed area falls within the “very low” and “low” erosion susceptibility classes. Nevertheless, erosion increases markedly in the northern areas with high slope gradients and in areas where agricultural activities are concentrated. The mean soil loss across the watershed was calculated as 2.75 t ha⁻¹ yr⁻¹. The eroded and transported material was determined to constitute a threat to the dam. The findings indicate that conservation plans, including afforestation in the upper watershed, adjustment of land use to natural land capability, and construction of check dams, should be implemented to ensure sustainable management of the watershed. From a soil and sediment remediation perspective, the identification of erosion-source areas and sediment-transport pathways provides a scientific basis for source-control measures aimed at reducing sediment delivery and associated water-quality deterioration in the Bayramhacılı Dam reservoir. Full article

Turbidite sandstones of the Chang 6 member and delta-front sandstones of the Chang 8 member in the Yuele Block, southwestern Yishan Slope, Ordos Basin, serve as the primary tight oil reservoirs. In this study, a total of 243 continuous core samples from multiple wells were collected for integrated analyses, including cast thin-section observation, scanning electron microscopy (SEM), X-ray diffraction (XRD) of clay minerals, routine core physical property measurements and mercury intrusion porosimetry (MIP), to systematically compare sedimentary–diagenetic disparities between semi-deep lacustrine turbidites (Chang 6) and delta-front sandstones (Chang 8). Measured data indicate that the two intervals have similar average porosities of 9.27% and 9.88%, while their respective geometric mean permeabilities differ markedly, with values of only 0.142 × 10⁻³ μm² for Chang 6 and 0.260 × 10⁻³ μm² for Chang 8. Micro-pore-throat size and connectivity dominate reservoir fluid flow capacity, and total porosity alone cannot objectively evaluate reservoir quality. Delta-front sandstones of the Chang 8 member are supplied by a proximal magmatic-rich provenance from the southwest, and widespread grain-coating chlorite forms during early diagenesis, effectively mitigating compaction damage and inhibiting quartz overgrowth, leading to well-preserved primary pores. As mixed-provenance deposits lacking protective chlorite rims, Chang 6 turbidites experience more intensive compaction, and abundant fibrous illite and carbonate cements precipitate in the subsequent diagenetic stage to fill and separate pore throats, forming an isolated micropore network. Quantitative comparison with baseline parameters of the Longdong region reveals that the Yuele Block is located closer to the southwestern sediment source, resulting in higher contents of magmatic lithics and chlorite in Chang 8 as well as elevated illite concentrations in Chang 6 relative to regional averages, which verifies that source-to-sink transport distance regulates reservoir quality by driving the differentiation of clay mineral assemblages. A complete quantitative coupling sequence of “provenance supply–authigenic clay mineral-pore evolution” is defined herein, and two distinct sedimentary–diagenetic evolutionary routes are classified: high-quality delta-front reservoirs protected by grain-coating chlorite, and low-quality turbidite reservoirs blocked by illite–carbonate cements. This research refines the diagenetic differentiation rules for continental tight sandstones with diverse sedimentary origins in the Ordos Basin and provides quantitative mineralogical criteria for identifying tight oil sweet spots in proximal provenance blocks. Full article

The Magdalena River Estuary hosts the access channel to the Port of Barranquilla, where recurrent dredging is required to maintain navigable depths of up to approximately 12 m. Chronic siltation in this channel is closely linked to the dynamics of the Turbidity Maximum Zone (TMZ), which remain poorly understood in tropical, microtidal systems with extreme sediment loads. This study investigates the spatiotemporal variability of the TMZ in the Magdalena River Estuary (MRE), Colombia, using a previously calibrated and validated MOHID 3D numerical model coupled with sediment transport. Sixteen scenarios covering river discharges from 2000 to 5500 m³ s⁻¹ under neap and spring tidal conditions were analyzed. Results show that the TMZ core position follows a nonlinear inverse relationship with discharge (R² = 0.976), migrating from km 13–15 under extreme low-flow conditions (Q = 2000 m³ s⁻¹) to the estuary mouth for discharges above 5000 m³ s⁻¹. Within the simulated discharge range of 2000–5500 m³ s⁻¹ and under the modeled neap and spring tidal conditions, the position where ε = 0.005 tracks the TMZ core location (R² = 0.96, RMSE ≈ 1 km), suggesting that this threshold can be used as a first-order spatial indicator of maximum sedimentation under the conditions evaluated in this study. Contrary to macrotidal estuaries, the MRE exhibits higher suspended-sediment concentrations during neap tides than during spring tides, with SSC up to 77 percent greater for Q = 2000 m³ s⁻¹. This reversal is driven by the suppression of turbulent mixing (R_i > 20) during neap conditions, which preserves the salt-wedge structure and enhances stratification-controlled sediment trapping. These results provide two process-based criteria for predicting turbidity-maximum behavior in the MRE: the ε = 0.005 stratification isoline and the discharge–TMZ polynomial. More broadly, the methodological framework may support the development of site-specific predictors for other highly stratified, microtidal estuaries subject to strong discharge variability. Full article