Search Results (4,547)

Tight sandstone reservoir effectiveness is governed not by pore volume alone, but by the storage and flow contributions of different pore-throat scales, their structural complexity, and their three-dimensional connectivity. This study investigates tight sandstones of the Benxi Formation deposited in a marine–continental transitional mixed siliciclastic–carbonate setting in the Gaoqiao area, southern Ordos Basin. Petrophysical measurements, red-epoxy-impregnated thin-section petrography, mercury intrusion capillary pressure (MICP), segment-specific fractal analysis of functionally defined pore-throat regimes, X-ray micro-computed tomography (micro-CT), and pore-network modeling (PNM) were integrated. The MICP responses define three pore-throat structure types and two data-derived functional boundaries at 0.708 and 0.141 μm, which separate large-pore-throat-dominated, transitional pore-throat, and fine-throat-limited intervals. Using these nominal boundaries, Type I is strongly dominated by the large-pore-throat interval, which accounts for 88.7% of total mercury intrusion, whereas Type II exhibits a mixed large-to-transitional response, and Type III is characterized by negligible large-pore-throat intrusion and pronounced fine-throat restriction. Perturbing both functional boundaries by ±5% and ±10% does not alter these principal functional distinctions, although samples close to the second boundary exhibit the expected local transitional sensitivity. Among the three segment-specific fractal parameters, the fine-throat fractal dimension, D_B, shows the strongest association with median capillary pressure (r = 0.834, p < 0.001) and remains significantly related to displacement pressure, median pore-throat radius, and permeability, whereas D_T shows no significant linear correlation with the tested petrophysical and MICP parameters. The fractions of the largest connected pore cluster in representative Type I–III samples are 90.26%, 72.56%, and 64.65%, while their PNM permeabilities decrease successively from 64.32 mD to 0.850 and 0.121 mD. Together, these results indicate that, for the investigated samples, reservoir effectiveness reflects the combined influence of pore-throat size configuration, segment-specific structural complexity, and three-dimensional network connectivity. Full article

The sustainable valorization of marine shell waste as functional additives for geopolymer materials represents a promising strategy for developing multifunctional materials for environmental remediation. In this study, metakaolin-based geopolymers were modified with calcium-rich particles obtained by calcination of five marine shell species (Chamelea gallina, Mya arenaria, Mytilus edulis, Pecten maximus, and Rapana venosa) under identical synthesis conditions to evaluate the influence of shell mineralogy on the structural, textural, adsorption, and antibacterial properties of the resulting composites. The materials were comprehensively characterized by Fourier transform infrared spectroscopy in attenuated total reflectance (ATR-FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and nitrogen adsorption–desorption (BET/BJH) analyses. Functional performance was assessed through methylene blue (MB) adsorption experiments, adsorption kinetic modeling, and antibacterial tests against Escherichia coli (E. coli). ATR-FTIR and XRD analyses confirmed the formation of a stable amorphous geopolymer network containing residual crystalline phases together with shell-derived calcium carbonate, predominantly as calcite or aragonite depending on shell origin. The incorporation of shell-derived particles modified the pore architecture of the geopolymers. GP-SJ exhibited the highest BET specific surface area (94.30 m² g⁻¹) and the most developed mesoporous structure. Among the investigated formulations, GP-RP showed the most favorable overall combination of functional properties under the investigated conditions, exhibiting the highest methylene blue removal efficiency (63.97%) and experimental adsorption capacity at 160 min (9.60 mg g⁻¹), together with a comparatively high reduction in recoverable E. coli colonies during preliminary antibacterial screening. The combined structural and functional analyses demonstrate that the environmental performance of shell-modified geopolymers cannot be predicted from a single parameter such as BET surface area or calcium content alone, but results from the synergistic interaction between mineralogical composition, particle dispersion, pore accessibility, and matrix compactness. Under the investigated conditions, these findings provide evidence for proposed structure–property correlations under the investigated conditions and suggests that shell-derived calcium particles act as microstructural regulators of geopolymer matrices, providing a basis for the further development of sustainable multifunctional materials for simultaneous dye removal and bacterial reduction in wastewater treatment. Full article

Tourism is a major driver of economic growth in tropical island destinations but also places increasing pressure on fragile marine ecosystems. This study examined tourists’ environmental awareness, perceptions, and conservation-related behaviors on Cozumel Island, part of the Mesoamerican Reef System and home to multiple protected areas, including the Arrecifes de Cozumel National Park. Between June and September 2022, surveys were conducted with 144 tourists at major tourism hubs across the island. Although 86% of respondents identified themselves as environmentally conscious, awareness of local environmental impacts associated with tourism remained limited, and only 6% reported engaging in environmentally conscious actions during their visit. Awareness of the protected status and regulations of the Arrecifes de Cozumel National Park was also low (39%), and only 19% reported purchasing the required conservation bracelet or park pass. Short-stay cruise visitors represented 65% of respondents, potentially limiting opportunities for deeper environmental engagement and conservation education. These findings highlight the need for stronger pre-trip environmental communication, visible on-site interpretation, and targeted outreach strategies to support sustainable tourism and coral reef conservation in the Mexican Caribbean. Full article

Mesophotic kelp habitats may contribute to marine carbon cycling, yet their productivity and long-term carbon retention remain poorly constrained. We assessed a depth-constrained analytical support domain for the endemic and endangered Brazilian kelp Laminaria abyssalis across 45–70 m on the southwestern Atlantic shelf using a published species distribution model, high-resolution bathymetry, biomass observations, and literature-based productivity scenarios. Accounting for within-cell bathymetric variation yielded 12,514.60 km² of depth-constrained analytical support within non-NA SDM coverage. The biomass dataset contained 23 observations aggregated into 19 raster cells. Leave-one-out validation showed that inverse distance weighting did not outperform a non-spatial mean (RMSE = 75.25 vs. 74.02 kg km⁻²; r = −0.389, p = 0.100); therefore, no regional biomass or biomass-derived productivity surface was produced. Using the only depth-overlapping Laminaria productivity analog (22.32 g C m⁻² yr⁻¹), the full-occupancy area-integrated NPP scenario was 279,326 t C yr⁻¹, with an empirical transferability envelope of 4242–1,074,367 t C yr⁻¹. At a long-term retention fraction of 0.11, the retained-carbon equivalent ranged from 467 to 118,180 t C yr⁻¹. These values are assumption-dependent screening estimates, not measurements of export, burial, sequestration, or carbon-credit potential. Field measurements of occupancy, local productivity, transport, burial, and permanence are required before carbon-accounting claims can be supported. Full article

The long-term accumulation of polyethylene terephthalate (PET) in marine environments may drive the evolution of microbial degradation capabilities, positioning the ocean as a valuable reservoir for discovering novel PET-degrading microorganisms. In this study, we isolated 305 marine-derived microorganisms with potential PET-degrading capability from samples collected from mangrove areas of Zhanjiang and the intertidal zones of Daya Bay, Shenzhen, China, using PET powder as a major carbon source. Subsequent evaluation of degradation performance via scanning electron microscopy and Fourier-transform infrared spectroscopy analysis identified 14 isolates capable of degrading PET film. These 14 strains belonged to 14 distinct species, none of which, to the best of our knowledge, has been previously documented as PET degraders. Among them, Microbacterium aurum SCSIO 85700 exhibited the most potent PET-degrading activity, achieving a weight loss of 2.1 mg (2.1%) and a 6.5% increase in relative crystallinity over 30 days. Genome analysis revealed the genetic basis underlying PET degradation and associated metabolic pathways in strain SCSIO 85700. Notably, genome mining and structural modeling identified two candidate polyester hydrolases, MA2267 and MA2443, possessing conserved His–Asp–Ser catalytic triads and exposed substrate-binding clefts resembling those of characterized PET-degrading enzymes, suggesting their potential involvement in PET depolymerization. Collectively, this study expands the recognized diversity of marine PET-degrading microorganisms and provides microbial resources for sustainable PET bioremediation. Full article

Abandoned, lost, or otherwise discarded fishing gear (ALDFG) is a persistent form of marine pollution requiring survey approaches capable of resolving individual items across large spatial extents. While uncrewed aerial vehicles (UAVs) can capture imagery at resolutions sufficient to resolve individual debris items, their use remains largely constrained to visual line-of-sight (VLOS) operations, limiting large-scale coastal monitoring. This case study develops and field-tests an operational framework for low-altitude beyond visual line-of-sight (BVLOS) UAV surveys, in which DEM-based communication viewshed modelling incorporating first Fresnel zone clearance is used to plan BVLOS missions. A lightweight fixed-wing UAV flown at 60 m AGL completed 20 missions across 210 km of remote northern Australian coastline. Communication viewshed modelling reliably guided mission planning with 90.5% of waypoints placed within predicted high-clearance zones maintaining moderate-to-strong command-and-control (C2) link quality in flight. Manual screening confirmed that the resulting imagery was of sufficient quality, with 291 derelict fishing nets detected. In a simulated VLOS operational scenario, 76.3% of these detections fell beyond VLOS range, and equivalent coverage would require an estimated 8.8-fold increase in mission count. These findings demonstrate that fixed-wing UAVs operating under low-altitude BVLOS conditions can support large-scale image acquisition in remote coastal areas, particularly when enabled by communication-aware mission planning. Full article

The marine and continental transitional facies coal of the Longtan Formation in western Guizhou Province is a key area for coalbed methane (CBM) exploration and development in Southwest China and has numerous resources; however, the exploration and development effects have been average. The development status of the Longtan Formation is such that it presents prominent compatibility issues, challenging production layer combinations, and limited production capacity. On the basis of the “three-step method” of the multicoal seam coproduction combination method and considering the influence of effective gas content and coal seam modification on productivity, a new CBM production seam combination optimization method is developed in which acoustic logging is used to elucidate the coal structure of a coal seam. The combination optimization of production layers in 9 typical wells in the study area was carried out, and the influencing factors and geological insights were discussed. The following conclusions were drawn: Under the multiple influences of the in situ stress mechanism, temperature, and formation pressure, the effective gas content of the coal seam first increases and then decreases, with the highest value occurring at approximately 600 m, and the gas saturation continues to increase. The in situ permeability and transformation permeability first decreased, then increased, and then decreased, and the turning depths were 400 m and 600 m. The productivity potential of the combined mining combination tended to increase with increasing depth. At depths up to 1000 m, a 100 m interval is the optimal combined span, 550–750 m is the enrichment high-permeability window, and it is also the best depth for coal seam joint mining. At a depth of 1000 m, the permeability and effective gas content of the coal seam decreased, whereas the gas saturation and desorption pressure increased, which increased the development potential and research value of the CBM reservoir. Full article

The presence of plastic marine litter (ML) and its associated negative environmental impacts have been documented in all existing parts of the marine and coastal environment, including protected areas (PAs). The aim of this study is to identify gaps in existing research related to the lack of standardization of methods and scarcity of detailed information on the characteristics of ML found. This systematic review provides current information on the methods and results of studies focused on the problem of ML and microplastic (MP) pollution on the coastlines of PAs. This study was conducted in accordance with the PRISMA 2020 statement. It is based on 28 peer-reviewed publications from four online databases and search platforms: ScienceDirect, PubMed, MDPI and Google Scholar, published between 2021 and 2025. The presence of ML was detected in all 28 studies (100%), confirming the relevance of the problem along the coastlines of PAs, even those far from industrial centers. The reported densities, however, ranged from a few fragments of litter to several thousand items. Plastic was the most common material of ML among all the peer-reviewed publications analyzed. Most of the studies showed that polyethylene (PE) fragments were the dominant type of microplastic (MP) found in coastal environments of PAs. However, despite the growing research on this topic, the problems of lack of detailed information and standardization of methods remain unresolved. This review emphasizes the importance of applying unified methods and conducting long-term monitoring experiments in future research. Full article

With the growing interest in Maritime Autonomous Surface Ships (MASS), numerous risk-assessment models have been proposed for route planning and hazard avoidance during navigation. Existing models, however, generally share two limitations. First, many assess risk from information such as vessel traffic and therefore do not adequately reflect the marine weather and sea state itself. Second, they often consider only one or two factors, such as wave height or wind, and even when several factors are merged into a single value, it is difficult to trace back why the result is dangerous. To overcome these limitations, this study proposes a Meteo-Hydrological Fusion Index (MHFI) that combines five environmental factors—wave height, swell period, current, wind, and visibility—into a single risk value. Each factor is first mapped to a 0–4 risk score, and the three highest scores at a given location are then combined by a weighted sum. This summarizes composite risk in a single value while preserving the ranking of the factors that produced it, so the result remains traceable. Applying the index to the coastal waters of Mokpo, we confirmed that the dominant factor behind a given risk grade varies with time and location, and that a rapid, area-wide rise in risk over a short period can be captured by a single indicator. We further show how risk varies along the main fairway and how the index can be overlaid on a display panel. These results indicate that the MHFI could serve as a decision-support layer in an S-100-based digital navigation environment. Full article

Marine fisheries play a vital role in ensuring food supply and sustaining livelihoods in coastal regions of China. However, the expansion of aquaculture has led to increasing carbon emissions and mounting pressure on resources and the environment, making the improvement of ecological efficiency a critical issue for the sustainable development of the industry. From the perspective of carbon emissions as undesirable output, this paper employs the DEA-SBM model and the GML index to measure the ecological efficiency of marine fisheries across nine coastal provinces in China from 2006 to 2023. Furthermore, using fixed-effects models, mediation-effect models, and grouped regression models, this study empirically examines the impacts of fishermen’s income and environmental regulations on the ecological efficiency of marine fisheries and their transmission mechanisms. The results indicate that ecological efficiency exhibits fluctuating trends across provinces, with significant inter-provincial disparities. Fishermen’s income has a significant positive effect on ecological efficiency, while environmental regulations show a significant negative effect. Digitalization level significantly promotes ecological efficiency, whereas fishery disaster losses significantly inhibit it. Technological adoption intention plays a partial mediating role in the pathways through which both fishermen’s income and environmental regulations affect ecological efficiency. Significant regional heterogeneity is observed, with the eastern coastal region exhibiting the strongest effects of various factors and the northern coastal region showing the weakest. Accordingly, this paper proposes differentiated enhancement pathways for ecological efficiency from four dimensions, including technological innovation-driven development, industrial structure optimization, environmental policy regulation, and regional coordinated governance, with the aim of providing theoretical foundations and policy references for the low-carbon transformation and sustainable development of marine fisheries in China’s coastal areas. Full article

Accidental releases of radionuclides from nuclear-powered vessels or ships carrying nuclear weapons may expose marine organisms to radioactive contaminants. The consequences of such events can differ markedly between resident fish populations and migratory species that move through affected areas. While these contrasting responses have been evaluated by the authors for coastal nuclear accidents, comparable assessments for open-sea scenarios remain limited. We simulated radionuclide releases from vessels in the North Atlantic to evaluate exposure pathways and potential ecological effects on both resident and migratory fish, since several naval bases operating nuclear-powered vessels are located along the eastern North American coastline. Physical transport of radionuclides was modeled using a Lagrangian framework that incorporates advection by ocean currents, three-dimensional turbulent diffusion, radioactive decay, and dynamic sediment–water exchanges. This transport model was coupled to a four-compartment food-web bioaccumulation model representing phytoplankton, zooplankton, non-piscivorous fish, and piscivorous fish. The approach allows evaluation of contaminant uptake in resident fish populations and along the migration routes of highly mobile species. Bluefin tuna (Thunnus thynnus), a key ecological and commercially valuable species, was selected as the migratory case study. Migration paths reconstructed from electronic tagging data were integrated to estimate radionuclide exposure along individual trajectories. This combined modeling framework provides new insight into how open-sea nuclear releases may differentially affect resident fish communities and wide-ranging migratory species in the North Atlantic, with relevance for fish ecology, population risk assessment, and fisheries management. Full article

In recent years, plastic litter in marine ecosystems has emerged as a global concern. Consequently, efforts to control, mitigate, and remove micro- and macroplastics from marine systems have intensified. In order to thoroughly analyze this topic, the present work provides a comprehensive overview of various strategies aimed at reducing plastic waste pollution spread in marine areas. Based on this, worldwide regulations limiting single-use plastic (SUP) products and microplastics in health care products were discussed. Further attention was also paid to bioplastic production as a potential alternative to non-degradable ones, with particular attention to their different degradability rates in various environmental compartments. Finally, strategies for the reduction in plastic pollution were specifically analyzed through a review of plastic litter collection/removal systems from beaches and the marine environment as well as different waterways. According to the above-mentioned aspects, this work highlights the significance of marine plastic litter pollution and provides support for the identification and selection of effective strategies for the mitigation of the impact of such litter on the environment. Full article

This study elucidated the spatial distribution characteristics of surface snow chemistry and stable isotope composition and their influencing factors in Antarctica’s coastal region. We analyzed data from eight surface snow chemical ion transects and five surface snow stable isotope transects to examine the distributions of sea-salt ions (Na⁺, Cl⁻, Mg²⁺, K⁺), non-sea-salt ions (NO₃⁻, methanesulfonic acid (MSA), non-sea-salt sulfate (nssSO₄²⁻), non-sea-salt Ca²⁺ (nssCa²⁺)), and the stable isotope δ¹⁸O. Concentrations of chemical ions were found to exhibit distinct source signatures. Principal component analysis indicated that the ranking of ion sources in Antarctica’s coastal areas is as follows: sea-salt aerosol transport, followed by marine biological activities and crustal dust and then atmospheric chemical reactions. Data from all transects exhibited a general pattern of diminishing δ¹⁸O with increasing distance from the coast but with marked regional differences in the δ¹⁸O–distance slope (−6.84 to −1.98‰/100 km), δ¹⁸O–altitude slope (−0.97 to −0.20‰/100 m), and δ¹⁸O–temperature slope (0.61 to 1.14‰/°C). The moisture source regions and transport pathways, local orographic uplift, and local temperature field jointly affect the differentiation of δ¹⁸O in coastal areas. The findings suggest that snow chemistry and isotopic composition in Antarctica’s coastal zones are controlled by marine source transport, biogeochemical cycling, and polar topographic and climatic processes. Full article

The preservation of submerged cultural heritage depends on the ability to locate, document, and monitor sites before they are degraded or lost. Although the North American Great Lakes contain thousands of exceptionally well-preserved shipwrecks, their large geographic extent and diverse operating environments present significant challenges for efficient archeological survey. This study presents a multi-platform autonomous survey framework developed and implemented during 2021–2022 field campaigns in Lake Michigan and Lake Ontario. The framework integrates autonomous underwater vehicles (AUVs), autonomous surface vehicles (ASVs), crewed vessels, side-scan sonar, multibeam bathymetry, magnetometry, optical imaging, and field-based data review within a hierarchical workflow comprising wide-area assessment (WAA) reconnaissance, high-resolution geophysical (HRG) mapping, adaptive mission refinement, and visual confirmation. The surveys produced 19.72 km² of geophysical coverage, including side-scan sonar mosaics, bathymetric surfaces, magnetic anomaly maps, and optical imagery that supported archeological interpretation. A case study from Lake Ontario demonstrates the framework’s effectiveness through the confirmation of a previously undocumented wooden shipwreck using complementary acoustic, magnetic, and visual datasets. Beyond the individual discoveries, the results demonstrate how integrated autonomous systems improve survey efficiency, support adaptive decision-making, and provide scalable methods for digital documentation, baseline site characterization, long-term monitoring, and preservation of submerged cultural heritage in freshwater and marine environments. Full article

Jacket foundations, with their excellent adaptability and economic efficiency, have been increasingly widely applied in medium-deep water areas. However, the scouring and erosion effects in the marine environment, coupled with complex wind-wave loads, have severely restricted the long-term safe service of jacket foundations. In this study, a structure-pile-soil coupled dynamic response model considering the effects of scour depth and changes in wind and wave directions for the jacket-type offshore wind turbine is developed by integrating the wind and wave load generation capability of OpenFAST and the nonlinear pile-soil interaction analysis function of OpenSees. By quantitatively analyzing key response parameters such as tower top displacement, nacelle acceleration, and internal forces of the foundation tower and pile shaft, this study reveals the significant influence of soil stiffness degradation induced by scour on structural dynamic characteristics, and verifies the effective suppression mechanism of the feathering shutdown strategy on structural responses under extreme loads. The research results indicate that scour has a negligible impact on the fundamental frequency of the jacket-type offshore wind turbine structure, while it significantly reduces the high-order frequencies and leads to a substantial increase in pile shaft internal forces; the effect of wind-wave angle intensifies the spatially coupled vibration response of the structure. The study provides important theoretical and technical support for the anti-scour design, multi-directional load assessment, and formulation of safety control strategies for jacket foundations in complex deep-sea environments. Full article