Search Results (145)

Sediment transport in Hangzhou Bay and the adjacent Changjiang Estuary is extremely complex due to the bathymetry and hydrodynamic conditions in this region. Using the particle tracing method based on the ROMS model, three-dimensional (3D) passive particle transport in Hangzhou Bay and the Changjiang Estuary was simulated. Ocean temperature, salinity, and circulation patterns before and during Severe Tropical Storm Ampil (2018) were reproduced by the model. The circulation in Hangzhou Bay is significantly influenced by the passing of the storm with an enhanced southeastward surface current. The along-front current offshore of the Changjiang Estuary, accompanied by the Changjiang River plume, is weakened by strong mixing under the storm. The transport of passive particles before and during the storm was also simulated based on the current fields of the model. The results show that the passing of the tropical storm enhances mass exchange in Hangzhou Bay by the storm-induced southeast circulation, while particle transport near the Changjiang Estuary decreases as the estuarine plume is weakened by the intense mixing of strong winds of the storm. Full article

Under the dual carbon mission, more and more coal mines will face shutting down in the future and stop treating mine water drainage, which, if it escapes, may cause severe secondary damage to the local groundwater quality. Wudong Coal Mine is a currently active subsurface coal mine in Xinjiang, China, that shows high-salinity characteristics. To forecast and discuss future possible groundwater quality damages and potential solutions, we here introduce a model prediction study on the effects of water pollution by coal mine drainage. The study protocol first involves creating a calibrated 2D groundwater flow model by use of FEFLOW software, then designing several flow and solute transport prediction analyses under changing mine water drainage conditions, different pollution source areas and water treatment pumping wells to discuss future prominent flow and transport behavior, as well as water treatment-affecting factors. It has been shown that mine water drainage plays a critical role in maintaining the mine water solute distribution, as without mine draining, local flow and solute distribution change dramatically, altering the groundwater capture zone, and may change the plume-migrating direction from upstream to downstream. A larger pollution source could produce a higher concentration of pollutants and a larger pollution-coverage area. To reduce pollutant concentrations, mine water treatment pumping wells with higher pumping rates can be applied as a useful remedial measure to effectively prevent the pollutant plume front from reaching the important drinking and irrigation water source of the region, Urumqi River. The results of this study can give important suggestions and decision-making support for authorities focused on water treatment and environmental protection decision-making in the region. Full article

The 2015 Fundão tailings dam collapse in Mariana, Brazil, was a major environmental catastrophe. Assessing its long-term effects on water quality is critical for environmental restoration and policy development. In this study, we reconstructed a 15-year time series of five water quality parameters to assess whether the collapse caused permanent changes. Using public data from the Minas Gerais Water Institute (IGAM), we fitted generalized additive models for location, scale, and shape to model long-term trends in turbidity, total solids, conductivity, pH, and dissolved oxygen. Predictor variables included daily precipitation and smooth functions for time and longitudinal distance along the river. As expected, turbidity and total solids increased sharply after the collapse; however, the mean values returned to pre-collapse levels within four years. Conductivity, which was already elevated pre-collapse, remained high following the passage of the tailings plume. Although we observed a tendency toward pre-collapse values, the long-term conductivity mean did not fully stabilize to previous levels. No clear patterns were observed for pH or dissolved oxygen. This study highlights the acute impact of the dam collapse on five water quality parameters in the Doce River and illustrates the river’s subsequent stabilization process, although other important and chronic impacts are still persistent. Long-term studies such as this provide valuable insights into the dynamics of fluvial systems. Full article

This study employs the MIKE 3 Flow Model, incorporating forcing conditions such as inflow from 18 major rivers along the Bohai coast, wind, precipitation, evaporation, and solar radiation, to develop a hydrodynamic and temperature-salinity model for the Bohai Sea, using a finer mesh for more detailed simulation in Laizhou Bay. The residual current in the surface layer primarily flowed eastward, exhibiting coastal transport characteristics in the southern region, leading to the formation of a large low-salinity region. The bottom salinity distribution closely mirrored that of the surface, with the isohaline shifting shoreward due to the high-salinity Bohai Sea water transported by the residual current. By grouping major runoff sources according to river outlet locations and residual current patterns, the study analyzed the impact of freshwater plumes formed by runoff from different directions on the salinity distribution in Laizhou Bay. The results indicate that the influence of freshwater inputs on both the mean salinity and the area of low-salinity zones in Laizhou Bay, ranked from greatest to least, is as follows: the Yellow River, the southwest, and the southeast. The variation in the area of low-salinity regions is closely related to factors such as runoff volume, residual currents, and the selection of boundaries for the low-salinity regions. Full article

An artificial neural network was developed to augment the accuracy of a physically based computer model in relating heat discharge to visible plume volume of a 12-cell mechanical draft cooling tower. In a previous study, Savannah River National Laboratory developed a 1D model to capture the average power plant discharge levels via analysis of a series of visual images but was unable to accurately predict individual cases, resulting in an overall average error of about $5\%$, but individual comparisons resulted in an $R^2$ of $0.36$. Three optimization algorithms were applied to better fit the entrainment coefficients, and the artificial neural network model was applied to 289 cases of a 12-cell mechanical draft cooling tower power generation facility. Two artificial neural networks configurations consisted of 10 and 47 nodes that used as input readily available plant data, observed cooling tower plume conditions, observed operational conditions, local and regional weather, and the predicted plume volume from the physical model; the individual predictions’ accuracy improved to $R^2>0.95$. This article concludes the sensitivities for the 1D model and additional actions to progress this field of study as well as applications for cooling tower monitoring. This strategy demonstrated an encouraging first step towards using multi-modal artificial neural network machine learning technology for information fusion to estimate power levels from external observations. Full article

River temperature is a critical parameter influencing aquatic ecosystems and water quality. However, it can be changed by natural (e.g., flow and depth conditions) and human factors (e.g., waste and industrial water drainage). Satellite-based monitoring offers a valuable tool for assessing river temperature on a large scale, elucidating the impacts of various factors. This study aims to analyze the spatiotemporal dynamics of surface water temperature (SWT) in the medium-sized Tisza River in response to natural and anthropogenic influences, employing Landsat satellites and in situ water temperature data. The validity of the Landsat-based SWT estimates was assessed across different channel sections with varying sizes. The longitudinal thermal profile of the Tisza was analyzed by mosaicking, monthly, four Landsat 9 images, covering the entire 962 km length of the Tisza in 2023. The impact of climate change was evaluated by analyzing SWT trends at a specific site from 1984 to 2024, utilizing 483 Landsat 4–9 images. The findings indicated elevated accuracy for Landsat-based SWT estimation (R² = 0.94; RMSE = 3.66 °C), particularly for channel sizes covering ≥ 3 pixels. Discharge, microclimatic conditions, and channel morphology significantly influence SWT, demonstrating a general increasing trend downstream with occasional decreases during the summer months. Dams were observed to lower the SWT downstream due to cooler bottom reservoir water discharge, with more pronounced differences during the summer months (1–3 °C). Tributaries predominantly (75%) elevated the SWT in the Tisza River, albeit with varying magnitudes across different months. Over the 40-year study period, an increasing trend in SWT was discerned, with an annual rise rate of 0.0684 °C. While the thermal band of Landsat satellites proved valuable for investigating the Tisza River’s thermal profile at a broad scale, finer spatial resolution bands are necessary for detecting small-scale phenomena such as thermal plumes and localized temperature variations in rivers. Full article

Water colour remote sensing is a valuable tool for assessing bio-optical and biogeochemical parameters across the vast extent of the Amazon River Continuum (ARC). However, accurate retrieval depends on selecting the best atmospheric correction (AC). Four AC processors (Acolite, Polymer, C2RCC, OC-SMART) were evaluated against in situ remote sensing reflectance ($R_{rs}$) measurements. K-means classification identified four optical water types (OWTs) that are affected by the ARC. Two OWTs showed seasonal differences in the Lower Amazon River, influenced by the increase in suspended sediment concentration with river discharge. The other OWTs in the Amazon River Plume are dominated by phytoplankton or by a mixture of optically significant constituents. The Quality Water Index Polynomial method used to assess the quality of in situ and orbital $R_{rs}$ had a high failure rate when the Apparent Visible Wavelength was >580 nm for in situ $R_{rs}$. OC-SMART $R_{rs}$ products showed better spectral quality compared to $R_{rs}$ derived from other AC processors evaluated in this study. These results improve our understanding of remotely sensing very turbid waters, such as those in the Amazon River Continuum. Full article

The Amapá margin, part of the Brazilian Equatorial Margin (BEM), is a key region that plays a strategic role in the global climate balance between the North and South Atlantic Ocean as it is strictly tied to equatorial heat conveyance and the fresh/salt water equilibrium with the Amazon River. We performed a new scientific expedition on the Amapá continental shelf (ACS, northern part of the Amazon continental platform) collecting sediment and using instrumental observation at an unstudied site. We show here the preliminary outcomes following the applied methodologies for investigation. Geophysical, geological, and biological surveys were carried out within the ACS to (1) perform bathymetric and sonographic mapping, high-resolution sub-surface geophysical characterization of the deep environment of the margin of the continental platform, (2) characterize the habitats and benthic communities through underwater images and biological sampling, (3) collect benthic organisms for ecological and taxonomic studies, (4) define the mineralogical and (5) elemental components of sediments from the study region, and (6) identify their provenance. The geophysical data collection included the use of bathymetry, a sub-bottom profiler, side scan sonar, bathythermograph acquisition, moving vessel profiler, and a thermosalinograph. The geological data were obtained through mineralogical, elemental, and grain size analysis. The biological investigation involved epifauna/infauna characterization, microbial analysis, and eDNA analysis. The preliminary results of the geophysical mapping, shallow seismic, and ultrasonographic surveys endorsed the identification of a hard substrate in a mesophotic environment. The preliminary geological data allowed the identification of amphibole, feldspar, biotite, as well as other minerals (e.g., calcite, quartz, goethite, ilmenite) present in the substrata of the Amapá continental shelf. Silicon, iron, calcium, and aluminum composes ~85% of sediments from the ACS. Sand and clay are the main fraction from these sediments. Within the sediments, Polychaeta (Annelida) dominated, followed by Crustacea (Arthropoda), and Ophiuroidea (Echinodermata). Through TowCam videos, 35 taxons with diverse epifauna were recorded, including polychaetes, hydroids, algae, gastropods, anemones, cephalopods, crustaceans, fishes, and sea stars. Full article

The exploration of alternative energy sources has gained significant traction in recent years, driven by the urgent need to mitigate greenhouse gas emissions and transition towards sustainable energy. Among these alternatives, ${\mathrm{C}\mathrm{O}}_2$ plume geothermal and hydrothermal systems have emerged as promising options due to their potential for providing clean, renewable energy. This study presents a probabilistic investigation into the sensitivity of ${\mathrm{C}\mathrm{O}}_2$ plume geothermal and hydrothermal systems under various reservoir conditions in the Williston Basin, North Dakota. In addition to elucidating the impact of reservoir conditions on system performance, the study utilizes probabilistic methods to assess energy output of ${\mathrm{C}\mathrm{O}}_2$ plume geothermal and hydrothermal systems. Insights derived from this probabilistic investigation offer valuable guidance for the working fluid selection, systems design and optimization in the Williston Basin and beyond. Results from the sensitivity analysis reveal the profound influence of reservoir conditions on the behavior and efficiency of ${\mathrm{C}\mathrm{O}}_2$ plume geothermal and hydrothermal systems. Our case study on Red River Formation and Deadwood Formations shows a potential of 34% increase and 32% decrease in heat extraction based on varying reservoir conditions. Our investigations in the Beaver Lodge field within the Red River Formation yielded arithmetic mean values for ${\mathrm{C}\mathrm{O}}_2$ best case resources, hydrothermal resources and the ${\mathrm{C}\mathrm{O}}_2$ worst case as 6.36 $\times {10}^{18}$ J, 4.75 $\times {10}^{18}$ J and 3.24 $\times {10}^{18}$ J, respectively. Overall, this research contributes to advancing the knowledge and understanding of ${\mathrm{C}\mathrm{O}}_2$ plume geothermal and hydrothermal systems as viable pathways towards sustainable energy production and carbon sequestration. By highlighting the sensitivity of these systems to reservoir conditions, the study provides valuable insights that can inform decision-making processes and future research endeavours aimed at fostering the transition to a low-carbon energy landscape. Full article

During the summer, substantial freshwater discharge from the Changjiang River into the East China Sea (ECS) results in extensive low-salinity water (LSW) plumes that significantly affect regions along the southern Korean Peninsula and near Jeju Island. Previous research developed an empirical equation to estimate sea surface salinity (SSS) in the ECS during the summer season using remote-sensing reflectance (R_rs) data from bands 3–6 (490, 555, 660, and 680 nm) of the Geostationary Ocean Color Imager (GOCI). With the conclusion of the GOCI mission in March 2021, this study aims to ensure the continuity of SSS estimation in the ECS by transitioning to its successor, the GOCI-II. This transition was facilitated through two approaches: applying the existing GOCI-based equation and introducing a new machine learning method using a random forest model. Our analysis demonstrated a high correlation between SSS estimates derived from the GOCI and GOCI-II when applying the equation developed for the GOCI to both satellites, as indicated by a robust R² value of 0.984 and a low RMSD of 0.8465 psu. This study successfully addressed the challenge of maintaining continuous SSS estimation in the ECS post-GOCI mission and evaluated the accuracy and limitations of the GOCI-II-derived SSS, proposing future strategies to enhance its effectiveness. Full article

Genetic structure and connectivity information can be used to identify biological corridors and prioritize the conservation of areas that help maintain ecosystem integrity. Some marine fish, especially those of commercial interest, have been proposed as suitable indicators to identify potential marine biological corridors due to their high mobility among habitats and socioeconomic importance. In this study, we assessed the genetic structure of lane snapper populations in the Honduran Caribbean to evaluate connectivity and identify potential environmental barriers. Furthermore, we evaluated the genetic characteristics of the lane snapper on a larger spatial scale, including populations across the rest of its distribution range in the western Atlantic, using mtDNA and nuDNA markers. Our results demonstrate a significant genetic diversity of lane snappers in the Honduran Caribbean. Furthermore, despite their high dispersal potential, we observed genetic structuring in lane snapper populations on a larger spatial scale, resulting in the formation of two distinct groups throughout their distribution range: group 1 from Florida, the Gulf of Mexico, Honduras, and Colombia and group 2 from Puerto Rico and Brazil. This genetic differentiation can be attributed to oceanographic barriers such as river plumes and marine currents. These findings have the potential to significantly impact marine conservation and management efforts in the region, both at local and regional scales. It is anticipated that they will not only inform but also elicit a response, driving further action towards effective conservation measures. At a local scale, we recommend that conservation efforts focus on protecting critical habitats. At a regional scale, lane snappers should be included in the management plans of existing marine protected areas necessary to ensure the long-term sustainability of the species and the marine ecosystems in which it resides. Full article

Measurements of temperature, salinity, and currents in the Amazon River plume over a section in the open ocean of the western tropical North Atlantic (38°48′ W) are considered. The measurements were carried out using an AML Base X CTD probe in the upper layer and a flow-through system that measures salinity, turbidity, and chlorophyll-a content in seawater while a vessel is on the way. The measurements were supplemented by velocity profiling using shipborne SADCP. Additionally, archived oceanographic data from the World Ocean Database (WOD18), data on satellite altimetry measurements (AVISO), and satellite salinity data from Aquarius and SMOS were used. It is shown that the width of the Amazon River plume is about 170–400 km and the depth of desalination is from 50 to 100 m. Surface salinity decreases compared to the background (36.1) by 0.25 in February and by more than 3.0 in September during the period of maximum development of the plume, which was determined from satellite measurements of surface salinity. Lagrangian modeling of the back-in-time advection of passive markers simulating freshwater particles was carried out. It was shown that the source of freshwater in the measurement area is discharge from the Amazon River. Amazon River freshwater covered a distance of 3300 km in 60–80 days. The estimate of freshwater transport in the plume was 0.02 Sv, which is one order of magnitude smaller than the mean river discharge. Full article

The grooved carpet-shell clam is one of the most economically relevant shellfish species living in the Mediterranean and nearby Atlantic coasts. Previous studies using different types of genetic markers showed a remarkable genetic divergence of the eastern Mediterranean, western Mediterranean, and Atlantic populations, but important details remained unclear. Here, data from six nuclear introns scored for restriction fragment size polymorphisms in eight populations that have not been studied before have been pooled for the analysis with data scattered through three previous studies, totaling 32 samples from 29 locations. The results show lower levels of heterozygosity, higher mean number of alleles, and alleles with restricted distribution in the Mediterranean populations, suggesting the existence of a large, isolated population in the eastern Mediterranean at the middle Pleistocene. The data also confirm the similarity of populations from Tunisia to Western Mediterranean populations. Finally, a genetic mosaic is apparent in the Atlantic coasts of the Iberian Peninsula, with a divergence of Rias Baixas populations from more northern populations and Central Portugal populations. The effects of oceanic fronts, seasonal upwellings, river plumes, and/or fishery management operations could explain this and other features of the Atlantic populations. Full article

Previous studies have investigated the characteristics and influencing factors of plume bulge in the Pearl River Estuary (PRE) using observations and numerical simulations. However, the understanding of how river discharge affects plume bulge is not consistent, and the response mechanism of plume bulge to changes in river discharge has not been revealed in detail. In this study, a three-dimensional hydrodynamic Finite-Volume Coastal Ocean Model (FVCOM) is constructed, and five experiments were set to characterize the horizontal and vertical distribution of the plume bulge outside the PRE under different river discharge conditions during spring tide. The physical mechanisms of plume bulge generation and its response mechanisms to river discharge were discussed through standardized analysis and momentum diagnostic analysis. The results indicate that the plume bulge is sensitive to changes in river discharge. When the river discharge is relatively low (e.g., less than 11,720 m³/s observed in the dry season), the bulge cannot be formed. Conversely, when the river discharge is relatively high (e.g., exceeding 23,440 m³/s observed in flood season), the bulge is more significant. The plume bulge is formed by the anticyclonic flow resulting from the action of the Coriolis force on the strongly mixed river plume. The bulge remains stable under the combined effects of barotropic force, baroclinic gradient force, and Coriolis force. The reduction of river discharge weakens the mixing of freshwater and seawater, resulting in the reduction of both the volume and momentum of the river plume, and the balance between advective diffusion and Coriolis forces are altered, resulting in the plume, which is originally flushed out from the Lantau Channel, not being able to maintain the anticyclonic structure and instead floating out along the coast of the western side of the PRE, with the disappearance of the plume bulge. Due to the significant influence of plume bulges on the physical and biogeochemical interactions between estuaries and terrestrial environments, studying the physical mechanisms behind the formation of plume bulges is crucial. Full article

Monthly climatology data for salinity fronts in the South Atlantic have been created from satellite SMOS sea surface salinity (SSS) measurements taken from 2011–2019, processed at the Barcelona Expert Center of Remote Sensing (BEC), and provided as high-resolution (1/20°) daily SSS data. The SSS fronts have been identified with narrow zones of enhanced horizontal gradient magnitude (GM) of SSS, computed using the Belkin–O’Reilly algorithm (BOA). The SSS gradient fields generated by the BOA have been log-transformed to facilitate feature recognition. The log-transformation of SSS gradients markedly improved the visual contrast of gradient maps, which in turn allowed new features to be revealed and previously known features to be documented with a monthly temporal resolution and a mesoscale (~100 km) spatial resolution. Monthly climatologies were generated and analyzed for large-scale open-ocean SSS fronts and for low-salinity regions maintained by the Rio de la Plata discharge, Magellan Strait outflow, Congo River discharge, and Benguela Upwelling. A 2000 km-long triangular area between Africa and Brazil was found to be filled with regular quasi-meridional mesoscale striations that form a giant ripple field with a 100 km wave length. South of the Tropical Front, within the subtropical high-salinity pool, a trans-ocean quasi-zonal narrow linear belt of meridional SSS maximum (Smax) was documented. The meridional Smax belt shifts north–south seasonally while retaining its well-defined linear morphology, which is suggestive of a yet unidentified mechanism that maintains this feature. The Subtropical Frontal Zone (STFZ) consists of two tenuously connected fronts, western and eastern. The Brazil Current Front (BCF) extends SE between 40 and 45°S to join the subantarctic front (SAF). The STFZ trends NW–SE across the South Atlantic, seemingly merging with the SAF/BCF south of Africa to form a single front between 40 and 45°S. In the SW Atlantic, the Rio de la Plata plume migrates seasonally, expanding northward in winter (June–July) from 39°S into the South Brazilian Bight, up to Cabo Frio (23°S) and beyond. The inner Plata front moves in and out seasonally. Farther south, the Magellan Strait outflow expands northward in winter (June–July) from 53°S up to 39–40°S to nearly join the Plata outflow. In the SE Atlantic, the Congo River plume spreads radially from the river mouth, with the spreading direction varying seasonally. The plume is often bordered from the south by a quasi-zonal front along 6°S. The diluted Congo River water spreads southward seasonally down to the Angola–Benguela Front at 16°S. The Benguela Upwelling is delineated by a meridional front, which extends north alongshore up to 20°S, where the low-salinity Benguela Upwelling water forms a salinity front, which is separate from the thermal Angola–Benguela Front at 16°S. The high-salinity tropical water (“Angola water”) forms a wedge between the low-salinity waters of the Congo River outflow and Benguela Upwelling. This high-salinity wedge is bordered by salinity fronts that migrate north–south seasonally. Full article