Search Results (82)

The water level of Lake Neuchâtel (Switzerland) was lowered 150 years ago, initiating soil formation and colonization by riparian forests of the previously submerged areas. Although the soils of the whole area are young and have probably quite similar parent material (lacustrine sediments and moraine), the present soils show a large diversity of horizon structures and contents. The aim of this study is to describe the respective processes of accumulation, integration, and stabilization of organic matter and assess the soil variables influenced by these processes in the various types of riparian forests with different moisture levels. The investigation employed a semi-quantitative, holistic approach that combined field observations, laboratory analyses, and micromorphological examination of soil thin sections. The results indicate that the accumulation and stabilization of organic matter are primarily governed by physicochemical factors associated with the parent material, particularly soil texture and calcium cation saturation. Soil moisture and groundwater elevation were found to mainly influence biological activity and vegetation types. Additionally, the incorporation of organic matter is affected by both soil texture and bioturbation processes. Overall, this study underscores the complexity of the mechanisms regulating organic matter dynamics in young soils. Full article

Effective monitoring of fish passage through river barriers is essential for evaluating fishway performance and supporting adaptive river management. Traditional methods are often invasive, labor-intensive, or too costly to enable widespread implementation across most fishways. Infrared (IR) beam-break counters offer a promising alternative, but their adoption has been limited by high costs and a lack of flexibility. We developed and tested a novel, low-cost infrared beam-break counter—FishTracker—based on open-source Raspberry Pi and Arduino platforms. The system detects fish passages by analyzing interruptions in an IR curtain and reconstructing fish silhouettes to estimate movement, direction, speed, and morphometrics under a wide range of turbidity conditions. It also offers remote access capabilities for easy management. Field validation involved controlled tests with dummy fish, experiments with small-bodied live specimens (bleak) under varying turbidity conditions, and verification against synchronized video of free-swimming fish (koi carp). This first version of FishTracker achieved detection rates of 95–100% under controlled conditions and approximately 70% in semi-natural conditions, comparable to commercial counters. Most errors were due to surface distortion caused by partial submersion during the experimental setup, which could be avoided by fully submerging the device. Body length estimation based on passage speed and beam-interruption duration proved consistent, aligning with published allometric models for carps. FishTracker offers a promising and affordable solution for non-invasive fish monitoring in multispecies contexts. Its design, based primarily on open technology, allows for flexible adaptation and broad deployment, particularly in locations where commercial technologies are economically unfeasible. Full article

Sediments are key players in the optimum functioning of ecosystems; however, they also represent the largest known repository of harmful contaminants. The vast variety of these sediment-associated contaminants may exert harmful effects on marine communities and can impair ecosystem functioning. Whole-cell biosensors are a rapid and biologically relevant tool for assessing environmental toxicity. Therefore, in this study, we developed a bioassay-based toxicity measurement system using genetically modified bacteria to create a whole-cell optical biosensor. Briefly, reporter bacteria were integrated and immobilized using a calcium alginate matrix on fiber-optic tips connected to a photon counter placed inside a light-proof, portable case. The calcium alginate matrix acts as a semi-permeable membrane that protects the reporter-encapsulated optical fiber tips and allows the inward passage of toxicant(s) to induce a dose-dependent response in the bioreporter. The samples were tested by directly submerging the fiber tip with immobilized bacteria into vials containing either water or suspended sediment samples, and the subsequent bioluminescent responses were acquired. In addition to bioavailable sediment toxicity assessments, conventional chemical methods, such as liquid chromatography–mass spectroscopy (LC-MS) and inductively coupled plasma optical emission spectroscopy (ICP-OES), were used for comprehensive evaluation. The results demonstrated the efficacy of the biosensor in detecting various toxicity levels corresponding to identified contaminants, highlighting its potential integration into environmental monitoring frameworks for enhanced sediment and water quality assessments. Despite its utility, this study notes the system’s operational challenges in field conditions, recommending future enhancements for improved portability and usability in remote locations. Full article

Semi-submerged curtain breakwaters are increasingly favored to protect marinas and other microtidal basins, yet they are still almost exclusively designed with deterministic wave transmission equations. This study introduces a fully probabilistic design framework that translates uncertainty in wave climate and water level design parameters into explicit confidence limits for transmitted wave height. Using Latin Hypercube Sampling, input uncertainty is propagated through a modified Wiegel transmission model, yielding empirical distributions of the transmission coefficients K_t and H_t. Our method uses the associated safety factor required to satisfy a 95% non-exceedance criterion, SF₉₅. Regression analysis reveals the existence of a strong inverse linear relationship (R = −0.9) between deterministic K_t and the probabilistic safety factor, indicating that designs trimmed to low nominal transmission (e.g., K_t ≤ 0.35) must be uprated by up to 55% once parameter uncertainty is acknowledged, whereas concepts with greater transmission require far smaller margins. Sobol indices show that uncertainty in H_m0 and T_p each contribute ≈40% of the variance in H_t for a tide signal standard deviation of σ_η = 0.16 m, while tides only become equally important when σ_η > 0.30 m. Model-based uncertainty is negligible, standing at under 8%. The resulting lookup equations allow designers to convert any deterministic K_t target into a site-specific probabilistic limit with a single step, thereby embedding reliability into routine breakwater sizing and reducing the risk of underdesigned marina and port structures. Full article

This article describes the reasons for and trends in the overgrowth of soft-water lakes in Belarus. Due to their unique water properties (low mineralization, pH, and nitrogen and phosphorus concentrations) and high water transparency, soft-water lakes are home to protected plant species like Lobelia dortmanna L., Isöetes lacustris L., and Littorella uniflora L. The purpose of this study was to analyze changes in aquatic vegetation distribution in seven soft-water Belarusian lakes and identify the causes of these changes. The initial data for this research were the results of field observations, the archive materials of the research laboratory of lake research conducted by the Belarusian State University for the period from 1971 to 2016, including morphometric and hydrochemical parameters, the characteristics of catchments and water exchange, and the results of studying the species composition and distribution of aquatic vegetation. The authors’ field studies were carried out in 2022–2024. We used expeditionary, hydrochemical, cartographic, and comparative research methods. The most significant changes in overgrowth were observed in Lakes Svityaz and Beloe (Luninets District). These lakes have high recreational loads. Significant negative trends were also noted in Lakes Bolshoe Ostrovito and Bredno. Over 35 years, the depth of distribution of submerged macrophytes in Lake Svityaz has decreased from 7 to 2 m, and the abundance and projective cover of semi-submerged macrophytes have increased. In Lake Beloe, I. lacustris, which forms a tier of submerged plants, has almost completely disappeared, and a previously absent strip of air-aquatic plants has formed. The total area of overgrowth in the lake has decreased from 35% of the water area to 3.2%. In Lake Bolshoe Ostrovito, Fontinalis sp., previously common at depths of up to 5 m, has practically disappeared. In Lake Bredno, the water moss Drepanocladus has spread to a depth of 4 m. In Lake Glubokoe, a new area of I. lacustris growth was discovered around an island at depths of up to 4 m. In Lake Cherbomyslo, the decrease in the species’ depth and area of distribution is associated with a weakening of the inflow of bog waters due to their backwater. The main causes of these changes are largely due to anthropogenic factors (water pollution by biogenic compounds) and, to a lesser extent, hydrological changes (decrease in the moisture content of lake catchments). Full article

Abandoned, lost, or discarded fishing gear (ALDFG) poses significant environmental threats, namely contributing to microplastic (MP) pollution. However, the release of MPs from ALDFG remains poorly studied, despite its crucial role in understanding plastic pollution in marine ecosystems. This study is, to the best of our knowledge, the first to assess the environmental impact of ALDFG as a source of MPs, using an integrated approach combining laboratory experiments, in situ field trials, and environmental surveys. Laboratory tests showed that in the presence of light and sediment, braided polyethylene net released 1 fibre after incubation, demonstrating that the studied plastic fishing nets had the potential to release MPs. In situ experiments in a semi-enclosed marine environment did not show a clear influence of submerged fishing nets on water MPs, due to the high MP contamination in the selected location (5322 ± 4936 MP m⁻³). Nonetheless, at ALDFG hotspots off northwest Portugal, an increased presence of MPs in water samples compared to locations without ALDFG suggested potential MP release. These findings demonstrate the potential of ALDFG to act as a source of MPs and showcase the need for further studies, in order to comprehensively investigate the degradation of different plastic fishing nets in the field. Reducing ALDFG pollution is critical to mitigating its environmental impact and preserving marine ecosystems. Full article

Floodplain agriculture is a practice that involves cultivating arable soils along riverbanks and reservoirs, which become submerged during the rainy season. This study aimed to analyze the socioeconomic aspects of floodplain farmers in the municipalities of Amarante, Floriano, and Uruçuí along the banks of the Parnaíba River in northeastern Brazil. We conducted semi-structured interviews using the rapport technique. Data were analyzed using generalized linear models with four distributions (gamma, inverse Gaussian, exponential, and Gaussian), with the aim of identifying patterns and relationships between socioeconomic variables and production system profiles. The average age of respondents was 49 years across the three communities, with a predominance of male farmers. Regarding the length of residence, communities in Uruçuí had lived in the area the longest. In terms of monthly income, 80% of farmers earned up to one minimum wage. Land size analysis indicated that properties in Amarante had the highest average land area in hectares. We conclude that agriculture in the region studied is dominated by manual planting, low adoption of technologies, and scarce use of soil conservation techniques, suggesting more sustainable agricultural practices, the development of management plans, and rural extension practices. Full article

The effects of wave and current on floating offshore wind turbines (FOWTs) are usually treated separately without considering their inherent interaction. In this study, the coupling effect of wave and current on the dynamic responses of a semi-submerged FOWT carrying a 5-MW NREL turbine is investigated. A numerical model considering the wave–current interaction is introduced, which accounts for the frequency shifts and surface profile changes for waves traveling over currents. The dynamic structural model of the semi-submerged FOWT is established in ANSYS AQWA, where the aero-servo-structural loadings on tower and turbine were obtained from the FAST platform by using the FAST-to-AQWA coding program. Irregular waves with 1- and 50-year return periods, in conjunction with a uniform current, were adopted to evaluate the coupling interaction effects. Waves traveling on positive and on opposite currents are examined in different cases with waves and currents propagating along the surge or sway direction. Waves consistently propagate along positive surge or sway direction. Waves interacting with positive or opposite currents have dramatically different modifications on the wave spectrum. Differences of up to 22% are recorded by comparing both the main motions and mooring tension when the interaction of waves and currents is considered or not. The coupling interaction between waves and currents has a limited influence on the tower base shear forces and bending moments. It was found that a straightforward superposition approach to evaluate the effect of the waves and the currents may underestimate the dynamic motions and mooring tension of FOWTs. Full article

The mechanical and hydrodynamic characteristics of single-piece nets are key to the design and optimization of offshore aquaculture net cages. A numerical approach for offshore submerged aquaculture net materials based on the Morison equations and finite element is proposed, simulating the hydrodynamic characteristics of single-piece nets under varying parameters such as wire diameter, mesh size, and flow velocity, and simulating the impact of marine organism attachment on nets by modifying the drag coefficient. The simulation results of nets made from materials such as Copper–Zinc Alloy (Cu-Zn), Zinc–Aluminum Alloy (Zn-Al), Semi-Rigid Polyethylene Terephthalate (PET), and Ultra-High Molecular Weight Polyethylene (UHMWPE) are compared, which provides a theoretical basis for optimizing design parameters and selecting materials for nets based on force conditions and hydrodynamic characteristics. The simulation results indicate that the current force on the net is positively correlated with flow velocity; the maximum displacement of the net is also positively correlated with the flow rate. Compared to other materials, the Cu-Zn net is subjected to the greatest water flow force, while the UHMWPE net experiences the greatest displacement; the larger the diameter of the netting twine, the greater the current force on the net; the mesh size is inversely related to the current force on the net. With increasing drag coefficient, both the maximum displacement of the net and the current force experiences increase, and UHMWPE material nets are more sensitive to increases in the drag coefficient, which indicates a greater impact from the attachment of marine organisms. The density and elastic modulus of the netting material affect the rate of increase in force on the net. The research results can provide a basis for further research on material selection and design of deep-sea aquaculture nets. Full article

Landslide-generated surge waves are significant natural hazards, posing severe risks to engineering safety. Despite extensive research on the dynamics of landslide-generated waves, studies analyzing controlling factors and their mechanisms remain limited, leaving key influencing processes inadequately understood. This study utilizes computational fluid dynamics (CFD) to perform a numerical simulation of a semi-submerged landslide in a hydropower station reservoir area. The research systematically investigated the effects of key variables, including slide volume, velocity, centroid height, and water depth, on the behavior of semi-submerged landslide-generated surge waves. Results demonstrate a positive correlation of slide volume, velocity, and centroid height with the initial wave height and run-up on the opposing shoreline. However, the impact of water depth reveals a more complex pattern, exhibiting distinct surge characteristics in the near-field and far-field zones. Via correlation and sensitivity analyses, this study elucidated the relationships between these factors and surge dynamics, identifying the primary factors influencing the size of the semi-submerged landslide-generated surge. The findings provide critical insights for predicting and mitigating surge disasters, offering both theoretical foundations and practical application value for landslide disaster prevention and management. Full article

Poyang Lake is the largest freshwater lake in China, which boasts unique hydrological conditions and rich biodiversity. In this study, metagenomics technology was used to sequence the microbial genome of soil samples S1 (sedimentary), S2 (semi-submerged), and S3 (arid) with different water content from the Poyang Lake wetland; the results indicate that the three samples have different physicochemical characteristics and their microbial community structure and functional gene distribution are also different, resulting in separate ecological functions. The abundance of typical ANME archaea Candidatus Menthanoperedens and the high abundance of mcrA in S1 mutually demonstrate prominent roles in the methane anaerobic oxidation pathway during the methane cycle. In S2, the advantageous bacterial genus Nitrospira with ammonia oxidation function is validated by a large number of nitrification functional genes (amoA, hao, nxrA), manifesting in that it plays a monumental role in nitrification in the nitrogen cycle. In S3, the dominant bacterial genus Nocardioides confirms a multitude of antibiotic resistance genes, indicating their crucial role in resistance and their emphatic research value for microbial resistance issues. The results above have preliminarily proved the role of soil microbial communities as indicators predicting wetland ecological functions, which will help to better develop plans for restoring ecological balance and addressing climate change. Full article

Tomato cultivation is relatively dense, and the main stem is easily submerged in a background environment with small color difference. The semi-enclosed planting space and fast growth cycle are both limitations that cannot be ignored in detection technology. The accuracy and real-time performance of plant height detection are of great practical significance. To this end, we are committed to improving YOLOv5 and proposing a lightweight real-time detection method for plant height by combining visual features of tomato main stems. Here, we improved the backbone, neck, head, and activation functions of YOLOv5, using CSP dark net53-s as the backbone structure and introducing a focus structure to reduce the number of GE modules. We replaced all CSP2_X structures in neck and head with GE modules, embedded interactive multi-head attention, and replaced YOLOv5’s framework function and attention activation function. We defined visual features such as the color of the main stem of tomato plants in the preprocessed image; input improved YOLOv5; and completed plant height detection through effective feature map fusion, main stem framing, and scale conversion. The experimental results show that the linear deviation between the plant height detection value and the actual value of the proposed method is always less than 3 cm, and the detection FPS can reach up to 67 frames per second, with superior timeliness, which can effectively achieve lightweight real-time detection. Full article

This study evaluated the effectiveness of Planet satellite imagery in mapping seagrass coverage in Santa Rosa Sound, Florida. We compared very-high-resolution aerial imagery (0.3 m) collected in September 2022 with high-resolution Planet imagery (~3 m) captured during the same period. Using supervised classification techniques, we accurately identified expansive, continuous seagrass meadows in the satellite images, successfully classifying 95.5% of the 11.18 km² of seagrass area delineated manually from the aerial imagery. Our analysis utilized an occurrence frequency (OF) product, which was generated by processing ten clear-sky images collected between 8 and 25 September 2022 to determine the frequency with which each pixel was classified as seagrass. Seagrass patches encompassing at least nine pixels (~200 m²) were almost always detected by our classification algorithm. Using an OF threshold equal to or greater than >60% provided a high level of confidence in seagrass presence while effectively reducing the impact of small misclassifications, often of individual pixels, that appeared sporadically in individual images. The image-to-image uncertainty in seagrass retrieval from the satellite images was 0.1 km² or 2.3%, reflecting the robustness of our classification method and allowing confidence in the accuracy of the seagrass area estimate. The satellite-retrieved leaf area index (LAI) was consistent with previous in situ measurements, leading to the estimate that 2700 tons of carbon per year are produced by the Santa Rosa Sound seagrass ecosystem, equivalent to a drawdown of approximately 10,070 tons of CO₂. This satellite-based approach offers a cost-effective, semi-automated, and scalable method of assessing the distribution and abundance of submerged aquatic vegetation that provides numerous ecosystem services. Full article

Simulating the free decay motion and wave radiation from a heaving semi-submerged sphere poses significant computational challenges due to its three-dimensional complexity. By leveraging axisymmetry, we reduce the problem to a two-dimensional simulation, significantly decreasing computational demands while maintaining accuracy. In this paper, we exploit axisymmetry to perform a large ensemble of Computational Fluid Dynamics (CFDs) simulations, aiming to evaluate and maximize both accuracy and efficiency, using the Reynolds Averaged Navier–Stokes (RANS) solver interFOAM, in the opensource finite volume CFD software OpenFOAM. Validated against highly accurate experimental data, extensive parametric studies are conducted, previously limited by computational constraints, which facilitate the refinement of simulation setups. More than 50 iterations of the same heaving sphere simulation are performed, informing efficient trade-offs between computational cost and accuracy across various simulation parameters and mesh configurations. Ultimately, by employing axisymmetry, this research contributes to the development of more accurate and efficient numerical modeling in ocean engineering. Full article

The production of polyhydroxyalkanoates using submerged cultures of Cupriavidus necator DSM 428 was evaluated using low-cost substrates from agroindustry: (i) dextrose from cassava starch and (ii) a mixture of sugarcane vinasse from the bioethanol industry and dextrose from cassava starch. The effects of vinasse composition (2.5, 5.0, 7.5, 25, 50, and 75% v/v) and the use of raw and activated carbon-pre-treated vinasse were assessed. The results indicate that cultivations using only cassava starch dextrose reached 4.33 g/L of biomass as the dry cell weight and a poly(3-hydroxybutyrate) (PHB) production of 47.1%. Raw vinasse proportions of 25, 50, and 75% in the culture medium resulted in total inhibition. Vinasse treated at the same ratios led to biomass production in the range 1.7–4.44 g/L. The higher PHB production scenario was obtained in a medium containing dextrose and treated vinasse (7.5%), yielding 5.9 g/L of biomass and 51% of PHB accumulation. The produced PHB was characterized by XRD and FTIR for an analysis of crystalline structure and chemical functional groups, respectively. EDS was employed for a semi-quantitative analysis of the chemical composition, and SEM was used to analyze the morphology of the microgranules. The results of DSC and TGA analyses demonstrated the thermal stability of the obtained PHB. Full article