Search Results (78)

Accurate quantification of ecological losses in estuarine environments is often hindered by the mismatch between coarse-resolution biological surveys and fine-scale physical disturbances from engineering activities. While numerical models can simulate high-resolution environmental shifts, the inherent sparsity of ecological monitoring points limits the precision of spatial impact assessments. This study develops an integrated spatial-downscaling framework to transform sparse monitoring data into a high-resolution spatial continuum. A three-tiered modeling approach was used: first, the estuarine domain was partitioned into five eco-hydrodynamic zones using an entropy-weighted Support Vector Machine (SVM); second, localized chained Generalized Additive Models (GAMs) were established within each zone using MIKE-simulated hydrodynamic and water-quality data as proxy drivers; and third, these localized response functions were propagated across the study area to quantify multi-trophic biomass and economic losses. The framework revealed substantial spatial non-stationarity. Dredging operations locally altered the estuarine hydrodynamic regime. In northern channels, decreases in flow velocity were statistically associated with phytoplankton biomass to decline by 5.0% to 23.42%. Conversely, southern velocity increases enhanced water exchange and plankton growth. Using silt curtains as a mitigation strategy reduced the loss of phytoplankton by 11.4% and zooplankton by 9.6%. As a result, the total economic loss decreased from 26.54 million CNY to 25.34 million CNY, equivalent to a 4.5% reduction in economic loss. These results indicate that the proposed downscaling method can generate spatially explicit biological estimates. By offering a systematic pathway for impact evaluation and compensation in data-limited coastal regions, this framework supports more ecologically sustainable dredging operations. Nevertheless, the framework remains dependent on the representativeness of sparse monitoring stations, and future applications should integrate cross-estuary validation to improve transferability and uncertainty control. Full article

Introduction: The sea lamprey (Petromyzon marinus) is an anadromous jawless fish that migrates between marine and freshwater environments, spawning once in rivers before dying. It is distributed along both coasts of the North Atlantic. In Asturias (northern Spain), P. marinus is classified as Vulnerable, and a conservation plan is currently under development. In the present study, Critical Conservation Areas (CCAs) are defined as river reaches requiring urgent protection due to their high ecological value for the species. Objective: This study aimed to identify key reproductive and larval habitats (spawning grounds and silt–sand banks) to support the designation of CCAs for the conservation of the sea lamprey in Asturias. Methodology: Fieldwork was conducted in the main salmonid rivers of Asturias (Deva, Nalón, Narcea, Navia, Eo, and Sella basins). During spring 2025 and 2026, habitats were characterized and spawning sites identified using transects. In autumn 2025, larvae were sampled by electrofishing within defined areas (10–30 m²), measured and weighed, and densities were extrapolated using an inverse distance weighting (IDW) model. Basin use and critical areas were assessed based on species distribution and habitat quality. Results: A total of 1886 larvae were recorded across 27 river sections, of which 1366 were measured. Sea lamprey was present in 74.1% of sections, whereas brook lamprey (Lampetra planeri) was detected only in the Deva basin. Mean larval size was 9.5 ± 3.7 cm and 2.3 ± 2.19 g, with marked spatial variability. The highest larval densities occurred in the Eo (21.5 ind/m²) and Narcea rivers (15.1 ind/m²). Additionally, 94 spawning records were identified, and 65% of the 83 assessed sections were classified as good or very good habitat. Conclusions: A total of 31 CCAs (~300 km) were proposed, including 97 km classified as “of interest”, 21 km as “important”, and 180 km as “highly important”. Habitat use was greatest in sinuous middle river reaches with riffles, pools, and fine sediment deposits. Transversal barriers, dredging, and channel simplification were identified as the main drivers of habitat loss. These findings provide a robust scientific basis for conservation planning and management of the species in Asturias. Full article

This study investigated rubber additives and relevant transformation products (RARTPs) in surface waters of Kaifeng, a city linking the Yellow River and Huaihe River basins. Seven of fifteen target analytes were detected in >10% of samples. The hydrolysis product 4-hydroxydiphenylamine (4OH) showed the highest detection frequency (70%), followed by 1,2-Dihydro-2,2,4-trimethylquinoline (TMQ, 57%) and N-(1,3-Dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD, 27%). TMQ had the highest average concentration (6.16 ± 4.17 ng·L⁻¹). Urban rivers (14.20 ± 4.72 ng·L⁻¹) were contamination hotspots, driven by management practices (e.g., dredging of urban lakes). Although detected at lower levels (0.09 ± 0.21 ng·L⁻¹), 6PPD-quinone (6PPD-Q) was associated with elevated risk (risk quotient, RQ ≥ 1) at 19% of sites. The chronic daily intake assessment showed that drinking water ingestion contributed 66.7% of total exposure in daily use, whereas dermal absorption dominated during swimming. Children, especially girls, were the most vulnerable subgroup. Although estimated chronic daily intakes (CDIs) from surface water accounted for only a negligible proportion of the daily urinary excretion of p-phenylenediamine antioxidants (PPDs) reported in a Chinese population, the ecological risk of 6PPD-Q warrants continued attention. These findings highlight the need for improved management of water bodies receiving urban runoff and aquaculture inputs, and further health risk assessment of RARTPs. Full article

This paper develops foamed mixture lightweight soil (FMLS) using dredged soil for ecological floating landscapes applications, focusing on key performance indices including dry density, compressive strength, splitting tensile strength, water absorption, and fluidity. Orthogonal experiments determined the optimal mix ratio, while CaO expansion agent, MgO expansion agent, polypropylene fiber (PPF), and basalt fiber (BF) were employed to modify material properties. The microstructural mechanisms of FMLS before and after modification were characterized by scanning electron microscopy (SEM). The results show that FMLS achieves optimal comprehensive performance at a cement-to-sand ratio of 0.4, foam content of 10%, and water-to-sand ratio of 0.35, with all parameters conforming to technical specifications. The optimal dosage for both CaO and MgO expansion agents is 5%, PPF is 0.3% and BF is 0.5%, respectively. MgO expansion agent and PPF demonstrate superior suitability for floating landscapes due to enhanced pore-filling efficiency and crack-bridging effects by SEM. Finally, correlation analysis further indicates that the water–binder ratio critically governs the strength characteristics of FMLS. This paper not only provides a new direction to promote the effective use of dredged soil resources, but also provides new ideas for carrier materials for ecological floating landscapes. Full article

Large inland waterway infrastructure projects are increasingly exposed to supply disruptions, logistics uncertainty, carbon-control pressure, and dredged-material management challenges. Although resilient supplier selection, closed-loop supply chains, and ESG-oriented optimization have been widely studied, existing models rarely integrate resilient sourcing, hub configuration, forward material supply, reverse dredged-material resourceization, and social externality penalties within a unified maritime infrastructure decision framework. To fill this gap, this study proposes an ESG-endogenous closed-loop supply-chain optimization model for construction of an inland waterway navigation hub. The model jointly optimizes resilient supplier selection, transshipment/resourceization hub activation, equipment deployment, forward material flows, and reverse dredged-material flows. Three objectives are considered: minimizing economic cost, minimizing carbon emissions, and maximizing net social benefit. In particular, a social benefit and ecological-debt penalty function is introduced to quantify the transition from beneficial reuse to disposal-related negative externalities. NSGA-II is adopted as a multi-objective solver, with parameter calibration, convergence analysis, and benchmark comparison used to evaluate computational performance. The Pinglu Canal project is used as a case study. The results produce 14 Pareto-optimal solutions and show that the lowest-cost and lowest-emission configurations may still generate negative social benefits. A low-cost ESG transition region around 197.3–197.8 million CNY is identified, where limited additional investment can activate resourceization pathways and shift the system from ecological debt to near-saturated social benefit. These findings suggest that sustainable infrastructure planning should move beyond isolated cost or carbon minimization and instead identify balanced supplier–hub–equipment–flow configurations that jointly support resilience, circularity, and ESG performance. Full article

Egypt’s largest coastal lagoon, Manzala Lagoon, has undergone severe degradation due to sediment infilling, aquatic vegetation proliferation, and untreated wastewater. It has shrunk from 805 km² in 1985 to 525 km² by 2017, with poor water quality and heavy metal accumulation. The 2017–2022 restoration project deepened the lagoon to 3–4 m, restoring 750 km² of open water and temporarily improving water quality. However, the reuse of dredged sediments to construct 13 elongated sand barriers and man-made islands inadvertently created semi-isolated sub-basins, disrupting east–west circulation, fostering localized stagnation, and coinciding with vegetation resurgence and seasonal algal blooms. This study employs coupled CMS-Flow and CMS-Wave modeling to evaluate hydrodynamic conditions and test innovative restoration strategies. Four scenarios were analyzed: pre-purification (2017), post-intervention project (2025), and two proposed interventions aimed at restoring connectivity, either through complete barrier removal or selective channel excavation, to enhance east–west water circulation and reduce stagnation. This study demonstrates that targeted, data-driven interventions can rapidly restore water circulation, revive ecological function, and optimize management strategies, providing a conceptually transferable framework for hydrodynamic assessment and sustainable management of coastal lagoons subject to similar anthropogenic pressures. Full article

The Yangtze River Economic Belt supports over 400 million people and contributes nearly half of China’s GDP, yet decades of industrialization, urbanization, and agricultural intensification have resulted in severe contamination and pressing environmental challenges. This systematic review synthesizes three decades of peer-reviewed and governmental data to examine the spatiotemporal distribution, sources, and ecological and human health risks of major pollutants, including heavy metals, microplastics, persistent organic pollutants, and excess nutrients. While point-source emission of heavy metals such as cadmium, lead, and mercury have decreased by 35–42% since 2013 following policy interventions like the 10-Point Water Plan and the Yangtze River Protection Law, legacy contaminants in sediments and diffuse agricultural inputs continue to pose significant risks. Cadmium levels in rice still exceed food safety standards, arsenic in groundwater surpasses health guidelines, and microplastic flux into the East China Sea has reached 8.3 × 10¹² particles per year. Nutrient surpluses also drive extensive algal blooms, causing substantial economic losses. This review evaluates remediation strategies such as dredging, phytoremediation, wetland restoration, and AI-enhanced monitoring, which show removal efficiencies of 60–90% at reduced costs. However, critical gaps remain in understanding chronic mixture toxicity, the long-term fate of emerging contaminants, and pollutant–climate interactions. We propose an integrated basin-wide roadmap combining zero-liquid-discharge mandates, green infrastructure, and adaptive, performance-based governance to secure the Yangtze’s ecological and economic sustainability. This framework offers a transferable model for large-scale watershed management worldwide. Full article

Shellfish aquaculture can alter sediment conditions and affect benthic ecosystem functioning, so dredging is widely applied as a management strategy to mitigate sediment deterioration. However, its ecological effectiveness remains uncertain. This study evaluated ecological quality under the disturbance of dredging in shellfish farming areas of Gamak Bay, South Korea, using multiple macrobenthic indices. Macrobenthic samples and environmental data were collected before (May 2025) and after dredging (August 2025). Five macrobenthic indices, including the AZTI Marine Biotic Index (AMBI), BENTIX, Benthic Polychaete/Amphipod ratio (BPA), Benthic Pollution Index (BPI), and Multivariate AMBI (M-AMBI), along with a composite index, were used to assess ecological quality. Temporal changes within groups were tested using Wilcoxon signed-rank tests, and differences between dredged and control stations were examined using Mann–Whitney U tests. Multivariate analyses were used to explore environmental gradients and community responses. Results showed clear seasonal variation in environmental conditions and macrobenthic community structure. Most indices indicated a decline in ecological quality after dredging, with higher AMBI values and lower BENTIX, BPI, and M-AMBI values at dredged stations. However, these changes were not statistically significant (p > 0.05), suggesting limited short-term effects of dredging. The proportion of stations with acceptable ecological status decreased slightly from May to August. Seasonal factors, particularly temperature and salinity, played a dominant role in structuring benthic communities. Overall, the findings indicate that the short-term dredging effects were weaker than seasonal environmental variability. A multi-index approach is recommended for robust ecological assessment, and long-term monitoring is necessary to fully evaluate the effectiveness of dredging in shellfish aquaculture systems. Full article

Evaluating the aquatic ecological and environmental consequences of dredging projects with precision is essential for reconciling engineering objectives with the long-term health of aquatic ecosystems. This study establishes an evaluation system for the aquatic ecological and environmental impacts of dredging engineering based on the Pressure–State–Response (PSR) analytical framework, and constructs a comprehensive assessment system through Velocity Pausing Particle Swarm Optimization–Projection Pursuit (VPPSO-PP) coupled with fuzzy pattern recognition. Taking the Pinglu Canal project as a case study, the objective weights of indicators are obtained via the VPPSO-PP method, and the impact levels are determined by combining the fuzzy pattern recognition model. Case studies show that the quality of discharged residual water is the most critical factor affecting the aquatic ecological environment, ranking highest with a weight of 0.0839, followed by the proportion of aquatic ecological restoration investment at 0.0685. Among the five typical dredging sections of the Pinglu Canal, the Shaping River section and the Offshore Estuary Section were rated as having a “mild impact.” In contrast, the Main Stream of Qinjiang River section, the Watershed section, and the Qinzhou urban section were rated as having a “moderate impact.” These evaluation results are consistent with the actual engineering conditions. The model developed in this study enables a quantitative and objective assessment of the aquatic ecological impacts of dredging projects. It provides a scientific basis and a practical tool for ecological management and decision-making in dredging operations. Full article

Harbour sedimentation represents a major challenge to the environmental sustainability and operational efficiency of coastal infrastructure, as frequent dredging activities increase maintenance costs, ecological disturbance, and carbon emissions. Conventional physical and numerical sediment transport models, while widely applied, are computationally intensive and often unsuitable for early-stage, sustainability-oriented design optimisation. To address these limitations, this study proposes a hybrid artificial intelligence-based optimisation framework integrating Artificial Neural Networks (ANNs), Genetic Algorithms (GAs), and Particle Swarm Optimisation (PSO) for sustainable breakwater and harbour layout design. Hydrodynamic simulations using the Coastal Modelling System (CMS) were conducted to generate a comprehensive dataset describing sediment transport behaviour under varying geometric and structural configurations. An ANN surrogate model was trained to capture nonlinear relationships between breakwater parameters and accumulated sedimentation volume, while GA-based global optimisation and PSO-based validation and local refinement were employed to identify optimal design solutions. Comparative assessment demonstrated consistent convergence of ANN–GA and ANN–PSO solutions within the same design region, with a maximum deviation of 8.46% between design variables and a sedimentation difference of 2.4%. The hybrid ANN–GA–PSO framework achieved the lowest predicted sedimentation volume, representing an improvement of approximately 2.3% relative to the ANN–GA baseline. The proposed framework supports Integrated Coastal Structures Management (ICSM) by enabling proactive, design-stage reduction in long-term sediment accumulation and dredging requirements, offering a scalable pathway toward sustainable and digital-twin-enabled harbour planning. Full article

The rapid expansion of coastal dredging projects has resulted in the accumulation of large volumes of dredged sediments, creating significant environmental and land-use challenges. Conventional disposal methods, such as landfilling and marine dumping, not only waste valuable resources but also pose risks, including heavy metal contamination and excessive salinity. In this study, dredged sediment from the former sedimentation area of Huanghua Port was systematically examined for its potential reuse as greening soil through a three-stage approach: desalination, amendment with additives, and composting. Water-washing experiments were conducted to optimize desalination parameters, with a focus on the effects of solid-to-liquid ratios and washing solution concentrations on electrical conductivity reduction. Biochar, fly ash, and wood vinegar were then applied as amendments to evaluate their impacts on soil properties, including pH, organic matter, electrical conductivity, and cation exchange capacity. In addition, co-composting experiments with dredged sediment and crop straw were designed to investigate composting dynamics and changes in physicochemical characteristics under different mixing ratios. The results showed that two washes with a 0.3% NaCl solution effectively reduced electrical conductivity to acceptable levels. Subsequent amendment and composting treatments markedly enhanced soil fertility and ecological suitability. In particular, the combination of 1000-fold diluted wood vinegar and straw-to-sediment composting at a 1:3 weight ratio enabled the amended sediment to meet the Chinese standards for Planting Soil Green. Overall, this study establishes a scientific basis and practical strategy for the sustainable recycling of dredged sediments, supporting their application in urban greening and ecological restoration. Full article

Soil nitrogen (N) and phosphorus (P) loss in watersheds is a critical source of water pollution. This study explores the spatial distribution, release potential, and environmental impacts of soil N and P in the downstream Daliao River basin by integrating field investigations and simulation experiments. Results showed that total nitrogen content in soils ranged from 256.09 to 3362.75 mg/kg, while that in sediments ranged from 114.85 to 1640.54 mg/kg. Total phosphorus content in soils varied from 250.18 to 1142.69 mg/kg, whereas in sediments it ranged from 327.23 to 586.24 mg/kg. The ammonia nitrogen release potentials of soils collected from rice paddies, corn farmlands, roadsides, and reed wetlands were 0.75, 0.86, 0.70, and 8.65 mg/L, respectively, with corresponding total phosphorus release potentials of 0.61, 1.01, 0.31, and 1.52 mg/L. For sediments, ammonia nitrogen and total phosphorus release potentials ranged from 0.96 to 1.21 mg/L and 0.44 to 0.52 mg/L, respectively. Temperature, pH, and dissolved oxygen were important factors influencing nitrogen and phosphorus release from soils and sediments. The export of nitrogen and phosphorus from soil reached 50.50 t/a and 21.63 t/a, respectively. During the soil erosion process in the Daliao River Basin, phosphorus exhibited a high release potential and served as the primary pollutant, whereas the release mechanism of ammonia nitrogen was more complex, showing seasonal variability. Soils in the downstream Daliao River basin have large specific surface areas and may pose a high pollution risk after discharge into water bodies due to prolonged adsorption of pollutants. It is recommended to propose promoting soil testing-based fertilization, constructing ecological engineering projects, developing sponge cities, and conducting environmental dredging to reduce N and P release from agricultural lands, construction areas, natural wastelands, and sediments. Full article

Coastal reclamation reshapes both soils and vegetation, yet their coupled trajectories remain poorly understood. Here we investigated soil–vegetation co-evolution across a 15-year chronosequence on Hengsha Island in the Yangtze River estuary. The reclaimed soils were formed primarily from dredged estuarine silt and clay slurry deposited during hydraulic filling. Four representative sites were studied, spanning 3 (Y3), 7 (Y7), 10 (Y10), and 15 (Y15) years since reclamation. Soil physicochemical properties (pH, electrical conductivity, salinity, nitrogen, phosphorus, potassium) were measured, while vegetation cover was quantified using NDVI and fractional vegetation cover (FVC) derived from satellite data. Soil conditions improved markedly with reclamation age: pH, conductivity, and salinity declined, whereas nitrogen, phosphorus, and potassium accumulated significantly (p < 0.001). Vegetation shifted from salt-tolerant pioneers (e.g., Suaeda salsa, Phragmites australis) to mixed communities and cultivated rice fields (Oryza sativa), reflecting progressive improvements in soil quality. Vegetation cover increased in parallel, with NDVI rising from 0.12 ± 0.05 (Y3) to 0.35 ± 0.09 (Y15), reflecting a shift from salt-tolerant pioneers to structurally complex communities. Mantel tests revealed strong positive associations of NDVI with organic matter, nitrogen, and phosphorus, and negative associations with pH, conductivity, and salinity. Structural equation modeling identified organic matter and nitrogen enrichment, along with declining pH and dissolved salts, as dominant drivers of vegetation recovery. These results highlight a co-evolutionary process in which soil improvement and vegetation succession reinforce one another, offering insights for ecological restoration and sustainable management in coastal reclamation landscapes. Full article

The concept of synergistic water resources, water environment, water ecology remediation, and restoration (3WRR) is essential for addressing the interlinked challenges of water scarcity, pollution, and ecological degradation. An intelligent platform of remediation and restoration project optimization was developed, integrating multi-source data fusion, a coupled air–land–water model, and dynamic decision optimization to support 3WRR in river basins. Applied to the Jinshan Lake Basin (JLB) in China’s Greater Bay Area, the platform assessed 894 scenarios encompassing diverse remediation and restoration plans, including point/non-point source reduction, sediment dredging, recycled water reuse, ecological water replenishment, and sluice gate control, accounting for inter-annual meteorological variability. The results reveal that source control alone (95% reduction in point and non-point loads) leads to limited improvement, achieving less than 2% compliance with Class IV water quality standards in tributaries. Integrated engineering–ecological interventions, combining sediment dredging with high-flow replenishment from the Xizhijiang River (26.1 m³/s), increases compliance days of Class IV water quality standards by 10–51 days. Concerning the lake plans, including sluice regulation and large-volume water exchange, the lake area met the Class IV standard for COD, NH₃-N, and TP by over 90%. The platform’s multi-objective optimization framework highlights that coordinated, multi-scale interventions substantially outperform isolated strategies in both effectiveness and sustainability. These findings provide a replicable and data-driven paradigm for 3WRR implementation in complex river–lake systems. The platform’s application and promotion in other watersheds worldwide will serve to enable the low-cost and high-efficiency management of watershed water environments. Full article

Human activities have led to severe aquatic pollution and significant concerns about the ecological health of the Lianjiang River Basin (LRB). These concerns resulted in the implementation of comprehensive policies and treatments to improve the sediment and water quality. Herein, we explore the concentrations, sources, and degree of metal contamination in filtered water (FW), suspended solids (SSs), and surficial channel sediments (SCSs) in streams of the LRB. Calculated enrichment factors, an ecological risk index, and a principal component analysis were employed to understand the degree of elemental contamination, ecological risks, and their potential sources. Elements (e.g., Hg, Cd, Sn, Sb, Cu, and Mo) were mainly detected in FW, SSs, and SCSs in the Bergang, Hucheng, Xiashan, and Zhonggang rivers, and the mainstream of the LR. Four potential anthropogenic sources were identified, including electronic waste recycling (e.g., Cu, Sb, Pb, and Ni), mixed pollution (e.g., Se, Zn, Mn, and Mo), metal processing (e.g., Hg, Cr, Sn, and Cd), and battery manufacturing and recycling (e.g., Co, Ni, and Mn). Overall, Sn, Sb, Hg, Cu, and Cd were enriched by 37.5–79.2% and 34.8–91.3% at the SS and SCS sites, respectively. Mercury, Cd, Sn, Sb, Cu, and Mo posed the most risk both in the SSs and SCSs. Overall, the SS and SCS samples from the LRB remain severely contaminated with metals after recent environmental remediation. The implementation of pollution source control, sewage interception, and dredging operations should be further enhanced. Full article