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Using fine-scale measurements in the northwestern Sea of Japan, we estimated the vertical mixing parameters in the sea water column extended from the lower part of the thermocline downward to the near-bottom layer above the continental slope. The vertical scales of the turbulent patches were determined together with the turbulent dissipation rate and diapycnal diffusivity based on the conductivity, temperature, and depth data obtained by an Aqualog moored profiler from April through October 2015. The Thorpe-scale method was used to estimate the vertical mixing parameters as well as the vertical heat and salt fluxes. The enhanced vertical mixing, as well as enhanced downward heat flux and upward salt flux, occurred below the mixed layer despite strong density stratification. By comparing the turbulent dissipation rate and diapycnal diffusivity estimates derived via the Thorpe-scale method and the estimates of the same parameters obtained earlier by applying the finescale parameterization method to the same dataset in addition to the collocates of the current velocity measurements, the comparative accuracy evaluation of both methods was carried out. Finally, by compiling the vertical mixing data obtained by the Thorpe-scale method and the finescale parameterization approach, the generalized depth profile for the diapycnal diffusivity is presented for the depth range from 70 to 350 m. [ABSTRACT FROM AUTHOR]

The influence of water temperature on the size–age structure and size of the population of mollusks Hydrobia acuta and their invasion with parthenites of the microphallid trematode Gynaecotyla adunca in Kazachya Bay (Black Sea) has been studied. It was revealed that temperature changes explain about 60% of the variance in the invasion extensity, and about 30% of the variance in the abundance of mollusks. The established correlation dependencies can be used for an approximate assessment of the influence of water temperature on the indicators of the population size of mollusks and their infestation with parthenites of trematodes in the Black Sea water area. [ABSTRACT FROM AUTHOR]

Clay minerals were studied in Pleistocene sediments from Hole 1038А (114.50 m deep) and Hole 1038Н (192.80 m deep) drilled near a hydrothermal vent with a temperature of 217°C on Central Hill, 275 m east of Hole 1038B. In sediments from Hole 1038A, at a depth of 8.52 m, <0.001-mm fraction consists completely of chlorite. In the rest of the sediment section in Hole 1038A, clay minerals consist of chlorite (from ~64 to ~98%) and illite. In sediments from Hole 1038H, clay minerals also consist of chlorite and illite. They were formed under conditions related to the intrusion of a basaltic melt as laccolith into the Escanaba Trough and the heating under its influence of a solution, during the interaction of which with sediments at a high-temperature stage biotite was formed. During the subsequent slow cooling of the laccolith and fluid, the newly formed biotite was replaced completely by chlorite. Illite was precipitated from a hydrothermal solution. At a depth of 183 m, in sediments from Hole 1038H, clay minerals consist of biotite, chlorite, and dioctahedral smectite, just as in sediments from Hole 1038B during their formation under conditions of rapid cooling of the laccolith flank and penetration of sea water into the sediments. The paper shows similarities and dissimilarities in the formation of clay minerals in Pleistocene sediments of the Central Hill, located above the slowly cooling part of the laccolith (Holes 1038A and 1038H) and in sediments located above the rapidly cooling laccolith flank (Hole 1038B). [ABSTRACT FROM AUTHOR]

Per- and polyfluoroalkyl substances (PFASs), which have their origins in both industrial processes and consumer products, can be detected at all treatment stages in wastewater treatment plants (WWTPs). Quantifying the emissions of PFAS from WWTPs into the marine environment is crucial because of their potential impacts on receiving aquatic ecosystems. In this study, the levels of five PFAS were measured in both influent and effluent sewage water samples obtained from a municipal WWTP, the discharges of which flow into False Bay, on the Indian Ocean coast of Cape Town, South Africa. Additionally, seawater, sediment, and biota samples from eight sites along the False Bay coast were also analysed. Results showed high prevalence of PFAS in the different environmental matrices. Perfluorononanoic acid was most dominant in all these matrices with maximum concentration in wastewater, 10.50 ng/L; seawater, 18.76 ng/L; marine sediment, 239.65 ng/g dry weight (dw); invertebrates, 0.72–2.45 µg/g dw; seaweed, 0.36–2.01 µg/g dw. The study used the chemical fingerprint of five PFASs detected in WWTP effluents to track their dispersion across a large, previously pristine marine environment and examined how each chemical accumulated in different marine organisms. The study also demonstrates that primary and secondary wastewater treatment processes cannot fully remove such compounds. There is thus a need to improve effluent quality before its release into the environment and promote continuous monitoring focusing on the sources of PFAS, including their potential transformation products, their environmental fate and ecological risks, particularly in areas receiving effluents from WWTP. [ABSTRACT FROM AUTHOR]

The use of reverse osmosis (RO) for desalination holds great promise for addressing water scarcity issues in many parts of the world. However, membrane fouling is a significant impediment in this regard, as it reduces the quality and quantity of water produced, increases energy consumption, requires cleaning, and shortens membrane life. The use of granular activated carbon (GAC) adsorption in conjunction with ultrafiltration (UF) as a pre-treatment ensures that high-quality seawater enters the desalination process free of contaminants that could harm the plant. This method increases the efficiency and longevity of the equipment, lowers maintenance costs, and produces high-quality desalinated water for a variety of applications. In this study, GAC was made from commercially available charcoal and used to remove organic compounds, heavy metals, and microbiological contaminants from seawater. A preliminary study was conducted to determine GAC's effectiveness in removing methylene blue (MB). The removal efficiency was found to be 78 and 99% at initial MB concentrations of 50 and 10 mg/L, respectively. The isotherm modeling confirms that the adsorption process follows the Langmuir model. In addition, the kinetic study demonstrated that MB adsorption on GAC follows the pseudo-second-order model. GAC filtration removed more than 99% of COD and significantly reduced metal concentrations such as Zn, Cu, and Cd. Bacteriological analysis of seawater treated with GAC revealed a significant reduction in total and fecal coliforms, as well as fecal streptococci, indicating the efficacy of the GAC/adsorption filtration system. [ABSTRACT FROM AUTHOR]

Settleability is vital important for the stability of effluent quality from the widely used activated sludge (AS) process in wastewater treatment plants. In this study, filamentous algae and seawater condition were used to build a microalgae-bacteria (MB) consortia system with the objective of improving the settleability of AS. Filamentous algae were found to flourish more in aeration seawater reactor (R2) than non-aeration (R1). During 90 days, large contents of N, P were firstly released from the biomass, but were absorbed by the algae to relatively low concentrations (N 1.1 mg/L, P 1.4–2.3 mg/L). Meanwhile, the settleability of the two types of MB consortia both significantly increased, but was superiorly enhanced in aeration condition to a low 5-min sludge volume (SV5) (11.5%, 55 d). Filamentous algae Leptolyngbya, as the most dominant part (9.8%) of microbial community in R2, could tightly bind the bacteria cells and extracellular polymeric substances (EPS) to form larger particles, which greatly accelerated the sedimentation. This study is of interest for the potential use of sludge settleability promotion in wastewater treatment plants, which has promising prospects for preventing the sludge bulking or biomass loss in AS systems. Highlights: A modified MB consortia was studied to enhance the settleability of AS. Filamentous algae flourished in seawater MB consortia with aeration. Settleability was remarkably enhanced by the algae in seawater condition. N and P were released from AS but was mostly absorbed by algae. Filamentous Leptolyngbya was dominant algae in the MB consortia. [ABSTRACT FROM AUTHOR]

Climate change is projected to substantially alter the Southern Ocean's physical and chemical properties, thereby impacting its marine ecosystems and species, particularly those in Antarctic and sub-Antarctic regions. This study focuses on Neobuccinum eatoni, a polar marine 'true whelk' endemic to these regions, utilizing 166 spatially independent occurrence data records to model potential distribution shifts under future climate scenarios. Employing Species Distribution Models (SDMs) on spatially cross-validated occurrences, we achieved high predictive accuracy, identifying "sea water salinity range" at mean bottom depth as the most significant predictor of habitat preferences. Additionally, dissolved iron (minimum), ocean temperature (range), and pH (long-term maximum) emerged as critical factors influencing the species' modeled distribution. By 2050, future projections under the SSP2-4.5 scenario predict an eastward expansion, particularly in the Antarctic Peninsula, the Scotia Arc and the Weddell Sea, with an expansion in the latter region also predicted under the SSP5-8.5 scenario. However, in both scenarios, a reduction in habitat suitability is expected in certain sectors around the Antarctic continent and the Kerguelen Archipelago. By 2100, under the moderate emissions scenario (SSP2-4.5), the species is projected to move to deeper areas and lower latitudes, with notable expansions in the Weddell Sea and in the Southern Ocean surrounding the Kerguelen Archipelago. However, under the SSP5-8.5 scenario, expansion is projected in the Weddell Sea and reductions in Antarctic and subantarctic regions. This study highlights the critical influence of changing salinity on N. eatoni's distribution, predicting a significant habitat reduction under high CO2 emissions scenarios (SSP5-8.5). The findings underscore the urgent need for focused research on the vulnerability of endemic marine invertebrates to develop effective conservation strategies in the face of rapid climatic changes. [ABSTRACT FROM AUTHOR]

Undersea mining encounters challenges due to the presence of seawater. An influx of seawater into stop in undersea can result in enormous disaster. Predicting strata settlement is a crucial measure to ensure the safety of undersea mining. This study proposed an intelligent model based on deep forest (DF) to evaluate the strata settlement during undersea mining. Initially, the strata displacement was monitored in the Xishan mining area of Sanshandao gold mine, China. Comprehensive datasets encompassing roof displacement and twelve influencing factors were compiled from 120 observations. Then, these datasets were statistically analyzed and used to train the DF model. The developed DF model achieved a training R2 of 0.971 and a testing R2 of 0.936. Compared with other machine learning models, the DF model has superior performance in the prediction of strata settlement. Moreover, a graphical user interface was designed to facilitate the application of the DF model. Finally, to validate model feasibility, displacement monitoring was conducted in the Xinli mining area of Sanshandao gold mine. Additional datasets were collected to validate the capability of the DF model. The results suggested that the DF model can be used to predict strata subsidence in undersea mining effectively. [ABSTRACT FROM AUTHOR]

We conducted a study to investigate the potential effects of nutrients released from a fish farm, which fell within the typical range found in oligotrophic offshore waters of the Aegean Sea, on phytoplankton growth. We designed an in situ bioassay experiment at a fish farm and incubated natural phytoplankton assemblages inside dialysis membrane bags for six days. Changes in phytoplankton growth in samples of ambient seawater collected throughout the experiment served as controls and were considered indicative of the net population change rates. Half of the bags were filled with seawater filtered through a 150-µm mesh, while the other half contained unfiltered seawater. The growth rates, estimated based on chlorophyll a concentrations and phytoplankton cell numbers inside the filtered and unfiltered bags, showed no significant differences. While no detectable net phytoplankton growth occurred in the ambient seawater, there was an exponential increase in chlorophyll a content and cell numbers within the bags. Moreover, the species richness within the bags gradually declined throughout the experiment. The findings of the study confirm that continuous nutrient releases from fish farms can promote high population growth rates in oligotrophic environments, provided that phytoplankton losses due to grazing, advection, and sinking are minimized or eliminated. [ABSTRACT FROM AUTHOR]

The pearlspot, Etroplus suratensis is a climate resilient cichlid fish that exhibits unusual adaptation to salinity. The fish is able to complete full life cycle in diverse salinity habitats ranging from fresh water to marine environments. High-quality primary and phased genome assemblies were generated for pearlspot fish using PacBio HiFi and Arima HiC sequencing technologies, for the first time. The primary assembly is highly contiguous with contig N50 length of 36 Mb. The final assembly is of 1.247 Gb with N50 length of 51.57 Mb and 98% of the genome length anchored to 24 chromosomes. The genome was assessed to be 99.9% complete based on BUSCO evaluation and was predicted to contain 52.96% repeat elements. We have predicted 27,192 protein encoding genes, of which 21,580 were functionally annotated. The genome offers an invaluable resource to understand adaptation of pearlspot fish to diverse salinity habitats. [ABSTRACT FROM AUTHOR]

The iron (Fe)-oxide deposits of the Lahn-Dill-type are composed of haematite-quartz and rare siderite-haematite ores. These ores formed as marine chemical sediments on top of volcaniclastic rocks near the Middle to Late Devonian boundary (∼ 380 Ma). As such, their trace element fractionation patterns provide key information on venting style, ocean chemistry, particle-solution interaction, and depositional environment at the time of ore formation. This study combines WDXRF and ICP-MS/OES whole-rock geochemistry with complementary in-situ LA-ICP-MS analysis, and TEM element mapping of ore samples from the Fortuna Mine (Rhenish Massif, Germany). In-situ measurments were conducted on quartz-haematite, haematite, and siderite-haematite microdomains. Bulk major element contents of the ores indicate (volcani)clastic contamination and post-depositional hydrothermal alteration. Microdomain trace element distributions reveal four different trace element signatures, which are related to: (1) syngenetic apatite formation due to sorption of P and REY from seawater; (2) Fe-(oxyhydr)oxide-specific trace element scavenging and fractionation within the seawater column; (3) diagenetic Fe(III) reduction and trace element mobilisation in pore water; and (4) simultaneous deposition of (volcani)clastic material and Fe-(oxyhydr)oxides. These results show that Lahn-Dill-type iron ore formation resulted from mixing of a low-temperature vent fluid with ambient seawater at high seawater to vent fluid ratios. This likely was related to an environment in which diffuse venting dominated over focused venting, and in which quick Fe-particle precipitation led to formation of haematite-quartz ores. Local diagenetic Fe(III) reduction resulted in post-depositional siderite-haematite ore formation during which trace elements were partially remobilised in pore water. [ABSTRACT FROM AUTHOR]

In recent years, solar evaporation desalination has been recognized as one of the most promising sustainable technologies and an efficient way to generate clean water and seawater desalination. In this paper, we introduce a three-dimensional (3D) photothermal evaporator with ZnFe2O4: Activated carbon (AC) ferrite photothermal nanocomposite including glutaraldehyde (GA) and polyvinyl alcohol (PVA). Then, physical, optical absorption, and structural properties and removal of water salinity and pollutants of ZnFe2O4/PVA:GA:AC nanocomposite were studied by X-ray diffraction analysis (XRD), Field emission scanning electron microscopy (FESEM), UV–Vis spectrophotometer, Fourier-transform infrared spectroscopy (FTIR), inductively coupled plasma (ICP) and Total dissolved solids (TDS) analysis. Under one sun irradiation, the ZnFe2O4/PVA:GA:AC nanocomposite hydrogel can reach a record high evaporation rate of 1.80 Kgm−2h−1. In addition, the hydrogel micropores and nanopores channels have a higher freshwater collection rate of 1 mlh−1 with very low hardness and ion conductance from 6648 to 138 ppm and 8651 µS to 293 µS, respectively for casspian sea water. Also, ICP spectroscopy result indicated that the reduction of the concentrations of k+, Na+, Mg2+ Hg2+ ions after distillation for casspian sea to 0.44 ppm, 3.49 ppm 1.14 ppm and 0 ppm, which was far below the salinity level of drinkable desalinated water defined by the World Health Organization. These results demonstrate the potential of ZnFe2O4/PVA:GA:AC nanocomposite hydrogel evaporator for practical application of water purification and high surface evaporator. [ABSTRACT FROM AUTHOR]

The pressure infiltration of fresh and salty bentonite slurries against a medium-fine sand has been investigated in a laboratory setup. In the tests, two series of salty bentonite slurries were used: non-pre-hydrated salty slurry, for exploring what will happen if directly salty water is used to make bentonite slurry, and pre-hydrated salty slurry, for identifying the consequence of pre-hydrated fresh bentonite slurry mixing with the salty water in the soil pores. The salty water employed was a mixture of different percentages of freshwater and seawater. Experimental results show that the test with non-pre-hydrated salty slurry exhibited a significantly faster and shorter (time) mud spurt, or even no mud spurt at all, compared to the test with fresh or pre-hydrated salty slurry. The influence of salty water on the pre-hydrated fresh bentonite is less than on the non-pre-hydrated slurry and depends on the seawater content in the salty water. Compared with the test with fresh bentonite slurry, a slower and shorter (time) mud spurt could be seen in the test with the pre-hydrated salty slurry when the seawater content was not more than 20%. As seawater content exceeded 20%, a faster mud spurt showed up; however, the timespan of the mud spurt may be shorter or longer, mainly depending on the viscosity and sedimentation behavior of the bentonite. A model to estimate the slurry infiltration distance during mud spurt is introduced, which agrees well with the experimental results using the measured input parameters. After the mud spurt, a filter cake would form in each test. The permeability of the filter cake increased with the increase in seawater content. Directly mixing salty water remarkably increased the permeability of the filter cake, while the pre-hydration of bentonite could reduce this increase. For instance, with the salty water containing 10% seawater, the permeabilities of the filter cakes formed by fresh bentonite slurry, non-pre-hydrated salty slurry, and pre-hydrated salty slurry with the 50 g/L bentonite concentration were 1.69 × 10−9 m/s, 2.26 × 10−8 m/s, and 3.23 × 10−9 m/s, respectively. [ABSTRACT FROM AUTHOR]

Rapid development of electronic and grid storage technologies based on lithium-ion batteries are leading to tight supply of lithium resources in the future. Extracting lithium from seawater can completely solve the problem of lithium resource shortage. An electro-deposition method based on a lithium superionic conductive solid-state electrolyte, Li1.5Al0.5Ge1.5(PO4)3 (LAGP), has been reported to obtain metallic lithium from seawater. However, expensive LAGP increases the cost of lithium extraction, while Li1.3Al0.3Ti1.7(PO4)3 (LATP) with relatively lower prices cannot meet the stable requirements. Herein, a low-cost, stable glass–ceramics, Li1.5Al0.3Ti1.7Si0.2P2.8O12 (LATSP), has been prepared for lithium extraction from seawater. The LATSP glass–ceramics show good selectivity towards Li+ and exhibit a high ionic conductivity of 3.98 × 10−4 S cm−1 at 22 °C. After soaking in simulated seawater, LATSP showed much better stability than LATP, comparable to LAGP. The resultant LATSP glass–ceramics was successfully employed in a seawater lithium extraction device, with a high lithium extraction Coulombic efficiency of 94.0%. Moreover, the LATSP exhibits an ionic conductivity of 2.80 × 10−4 S cm−1 and maintains a complete structure after 45 h of lithium extraction. This work presents an effective and practical Li-ion conducting membrane for lithium extraction from seawater. [ABSTRACT FROM AUTHOR]

Microplastics have recently emerged as a significant environmental concern due to their direct impacts on marine ecosystems. Vietnam, with its 3260-km coastline, faces an elevated risk of microplastic pollution due to various coastal anthropogenic activities. This study explored microplastic distribution in coastal surface seawater in the Southern Vietnam regions of Tien Giang, Can Gio, and Vung Tau. A total of 45 samples were collected in April, 2019, and the results showed that microplastics present at all sampling sites, with the abundance varying from 0.074 ± 0.109 pieces/m3 in Can Gio to 0.56 ± 0.35 pieces/m3 in Tien Giang. Estuarial sites showed higher abundances for all regions. Most microplastics were under 2.8 mm, fragmented, and primarily white or transparent. Polypropylene, polyethylene, and ethylene–vinyl acetate were the dominant polymers. This research indicates the urgency of further investigations to comprehensively understand the influence of wind patterns and other environmental factors on microplastic distribution. [ABSTRACT FROM AUTHOR]

As one of the world's mega-biodiverse regions, the Indian subcontinent harbors exceptional biological riches spanning diverse taxa and ecosystems. However, rapid economic growth and associated anthropogenic pressures pose ever-increasing threats to native biota through habitat loss, overexploitation, invasive species, climate change, and pollution. This paper analyzes India's changing biodiversity landscape, evaluates the efficacy of conservation policies, and charts strategic priorities for the future. Spatiotemporal trends for 3563 species across terrestrial, fresh water and marine realms were assessed using IUCN Red List data. We find that birds and mammals show modest improvements recently owing to legal protections and habitat recovery initiatives. However, other less-charismatic taxa exhibit alarming population declines nationwide. Our policy analysis highlights critical gaps in implementation frameworks involving multi-sector coordination, capacity building, benefit sharing, and participatory decision-making. To arrest biodiversity erosion and achieve stated policy targets by 2030, we propose an integrated, evidence-driven strategy prioritizing invasives control, agro-ecological transitions, pollution abatement, ecological connectivity via green-gray infrastructure, and community-based adaptation. Mindful of inherent socio-ecological complexities, our recommendations provide a framework for targeted conservation investments attuned to India's development aspirations. [ABSTRACT FROM AUTHOR]

Dimethylsulfide (DMS) is a climatically active volatile sulfur compound found in Earth's oceans and atmosphere that plays an important role in cloud formation. DMS originates from its precursor dimethylsulfoniopropionate (DMSP), which is produced by several classes of phytoplankton. Concentrations of DMS and DMSP in Antarctic sea ice, snow and underlying seawater are not well documented and there is currently no dataset available to find the existing data. The purpose of this project was to compile historical measurements into a publicly available dataset. A total of 220 samples collected since 1992 were compiled using the Antarctic Sea ice Processes and Climate program template, in accordance with the existing datasets for chlorophyll-a, macronutrients, and dissolved iron. Analyses performed on the completed DMS dataset showed that the spatial and temporal coverages are limited; there are barely any measurements in autumn and winter, nor in the Amundsen or Ross seas. These findings provide a basis for future sampling efforts in the Antarctic region. [ABSTRACT FROM AUTHOR]

Marine plastic pollution poses a growing environmental threat, with microplastics accumulating in the global oceans. This study profiles the seasonal dynamics and taxonomic composition of the plastisphere, the microplastic ecosystem, in the Eastern Mediterranean Sea. Using long-read 16 S and 18 S metabarcoding, we analyzed offshore microplastic and whole seawater samples across each season over a two-year period. The analysis revealed a higher richness of prokaryotic communities on microplastics compared to seawater, which was predominantly composed of Proteobacteria and Bacteroidota and exhibited notable seasonal variability. Benthic eukaryotes were enriched on microplastics compared to the surrounding seawater. Diatoms (Bacillariophyceae), in particular, showed significant enrichment within the microplastic eukaryotic community with primarily pennate diatoms of Amphora, Navicula, and Nitzschia genera, whereas the seawater included mostly centric diatoms. Seasonal fluctuations were less pronounced in the microplastic communities than in seawater, highlighting the relative stability of this new human-made ecosystem. These findings underscore the unique ecological niche of microplastic-associated communities in marine environments. [ABSTRACT FROM AUTHOR]

Seawater direct electrolysis (SDE) using renewable energy provides a sustainable pathway to harness abundant oceanic hydrogen resources. However, the side-reaction of the chlorine electro-oxidation reaction (ClOR) severely decreased direct electrolysis efficiency of seawater and gradually corrodes the anode. In this study, a redox-mediated strategy is introduced to suppress the ClOR, and a decoupled seawater direct electrolysis (DSDE) system incorporating a separate O2 evolution reactor is established. Ferricyanide/ferrocyanide ([Fe(CN)6]3−/4−) serves as an electron-mediator between the cell and the reactor, thereby enabling a more dynamically favorable half-reaction to supplant the traditional oxygen evolution reaction (OER). This alteration involves a straightforward, single-electron-transfer anodic reaction without gas precipitation and effectively eliminates the generation of chlorine-containing byproducts. By operating at low voltages (~1.37 V at 10 mA cm−2 and ~1.57 V at 100 mA cm−2) and maintaining stability even in a Cl−-saturated seawater electrolyte, this system has the potential of undergoing decoupled seawater electrolysis with zero chlorine emissions. Further improvements in the high-performance redox-mediators and catalysts can provide enhanced cost-effectiveness and sustainability of the DSDE system. Seawater direct electrolysis using renewable energy provides an appealing pathway to harness abundant oceanic hydrogen resources. Here, authors report a redox-mediated decoupled seawater direct electrolysis strategy to suppress the chlorine electro-oxidation side reaction. [ABSTRACT FROM AUTHOR]

Freshwater purification from wasted water and seawater is crucial in addressing the global problem of water scarcity. Porous fiber felt with a micro/nanostructure emerges as an efficient approach for water purification; however, its production usually relies on chemical postprocessing to create micro/nano structures on the fiber surface, which might pollute the environment. This study proposed an ecofriendly method to produce micro/nanostructured copper fiber felt without chemical treatment. First, a new transverse-feeding vibration cutting is proposed to fabricate micro/nanostructured fibers with controllable structure characteristics. Through the sintering of the structured fibers without postprocessing, the fiber felt can be produced in an ecofriendly way and exhibit special wettability and excellent photothermal properties. Felt-based freshwater purification, including oil–water separation and solar-driven seawater desalination, can be realized effectively. Results show an oil–water separation efficiency of > 90% and a high evaporation rate of water of > 1.08 kg m−2 h−1 at 73 mW cm−2 are achieved, demonstrating the application prospect of the produced fiber felt. Highlights: A transverse-feeding vibration cutting process is proposed to fabricate micro/nanostructured copper fibers. Micro/nanostructured based felts can achieve special wettability and corresponding wettability transition. Micro/nanostructured fibers can enhance the felts' photothermal conversion ability and reduce heat transfer loss. [ABSTRACT FROM AUTHOR]

Two novel Gram-stain-negative, aerobic, and non-motile strains, designated FZY0004T and YYF002T, were isolated from an agar-degrading co-culture, which was obtained from seawater of the intertidal zone of Yancheng City, the Yellow Sea of China. Strain FZY0004T optimally grew at 28 °C, pH 7.0, and 2–6% NaCl, while strain YYF002T optimally grew at 28 °C, pH 7.5, and 2–4% NaCl. Strain FZY0004T possessed Q-9 as the major respiratory quinone, and its major fatty acids (> 10%) were summed feature 8 (C18:1ω7c), C16:0, and summed feature 3 (C16:1ω7c/C16:1ω6c). The polar lipids identified in strain FZY0004T were phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and several unidentified phospholipids (PL) and lipids (L). On the other hand, strain YYF002T had MK-6 as the predominant respiratory quinone and its major fatty acids consisted of iso-C15:0, iso-C15:1 G, and iso-C15:0 3-OH. The polar lipids identified in strain YYF002T were aminolipid (AL), PE, and several unidentified lipids. Strain FZY0004T shared 99.5% 16S rRNA gene sequence similarity and 90.1% average nucleotide identity (ANI) with T. povalilytica Zumi 95T, and strain YYF002T shared 99.2% 16S rRNA gene sequence similarity and 88.2% ANI with W. poriferorum JCM 12885T. The genomic DNA G + C contents of strains FZY0004T and YYF002T were 54.5% and 33.5%, respectively. The phylogenetic, phenotypic, and physiological characteristics permitted the distinction of the two strains from their neighbors, and we thus propose the names Thalassospira aquimaris sp. nov. (type strain FZY0004T = JCM 35895T = MCCC 1K08380T) and Winogradskyella marincola sp. nov. (type strain YYF002T = JCM 35950T = MCCC 1K08382T). [ABSTRACT FROM AUTHOR]

The Kingdom of Saudi Arabia is facing challenges related to water scarcity, however, the Cambrian-Ordovician Saq Aquifer System, in Al Qassim Province, provides vital water resources. This article assesses the petrophysical properties and hydrochemical characteristics of the aquifer system utilizing downhole cam recording and geostatistical analysis. The evaluation aims to assign the hydrogeological attributes, groundwater potential, and associated risks using an open-petrophysical aquifer system approach. The petrophysical evaluation appraises the prevailing lithology, zonation, hydrogeological properties, and salinity patterns. Sandstones with low shale content and dispersed distribution possess effective porosity that is fully saturated with groundwater containing calcium and bicarbonate ions. The majority of groundwater samples exhibit simple dissolution or lack prevailing ionic concentrations, indicating an ancient marine water genesis and a fossilized water type. The resistivity-depth profiles reveals three potential water-bearing aquifers including a disconnected compartment of an unconfined aquifer, a continuous compartment of a confined aquifer, and a continuous compartment of an unconfined aquifer. Petrophysical and hydrochemical parameters have been analyzed using geostatistical methods to assess their spatial variability and reduce potential sampling errors. Three distinct risk segments (RSs) with varying levels of risk characterize the aquifer system. RS-A represents a potential aquifer with low risk, RS-B poses moderate risks, and RS-C carries high risks. A fairway map of the aquifer system assigns geologic-hydro related factors that influence aquifer assessment and risk mapping. Segment-A is deemed an attractive long-term investment opportunity with low risk, while Segment-B offers a good investment opportunity with moderate risk. Segment-C provides a fair investment opportunity but entails high risks related to petrophysical qualities, hydrochemical characterizations, and irrigation utilities. The extraction and utilization of groundwater present promising investment opportunities, while employing a petrophysical approach can effectively evaluate and manage groundwater resources for sustainable utilization. [ABSTRACT FROM AUTHOR]

Abstract—Variations in the position of the dome of Weddell Sea Deep Water was studied based on the EN4 data on temperature and salinity for monthly mean conditions in February and August in 1993–2012 depending on the wind friction stress calculated according to the JRA55-do data. The dome itself is considered in the region 60°–67° S and 10°–25° W. The range of potential temperatures in the layer of Weddell Sea Deep Water is 0.02-0.20°C. Observed mean data of the dome of isotherms and isopycnals in February from 1993 to 2012 is formed as a sequence of the intensification of the thermohaline circulation in general and the wind circulation of water in the Weddell Sea. Isotherms experience periodic rise and descent under the influence of seasonal variability of the cyclonic nature and the intensity of the wind field. The outflow of deep water from the Weddell Sea mainly occurs through the Orkney Passage over a transverse ridge of about 3600 m deep. Depending on the rise or descent of the isotherms around this passage, warmer or colder Antarctic Bottom Waters enter the Scotia Sea. [ABSTRACT FROM AUTHOR]

For the first time, the isotopic composition and concentration of dissolved inorganic carbon in waters of the western Bering Sea (Koryak shelf and Chukotka continental slope, and Commander Islands, depth range 10–4100 m) have been analyzed. The [DIC] values vary from 1900 μmol/kg in the summer waters of the Koryak shelf to 2510 μmol/kg in the deep waters in the area of the Commander Islands. The δ13С values of DIC in productive summer waters exceed +1‰ and reach +3.08‰ in Koryak shelf surface waters. The depth of the carbon isotope minimum (–0.7‰) is ≈500 m. The model calculations were made taking into account the physical processes (isotopic exchange with atmospheric CO2 and conservative mixing). The calculations show that the δ13С(DIC) and [DIC] values in the main water column are governed by oxidation of organic matter. The predominance of primary production occurs only in the surface (<20 m) waters of the Bering Sea. The DIC concentrations increase to depths of ≈1000 m and remain approximately constant (2430 ± 30 μmol/kg), exceeding [DIC] levels in deep Pacific waters. A "physical carbon pump" model is proposed, in which the main role in the accumulation and redistribution of DIC within the water column is attributed to winter waters of the Bering Sea. [ABSTRACT FROM AUTHOR]

The Kara Sea has been systematically studied since the beginning of the 20th century. Large amounts of data have been accumulated as a result of both national and international expeditions. Many publications have been devoted to Kara Sea regional zoning as per the geomorphological, biological, oceanographic aspects of its nature. This paper presents the results of statistical analysis of combined hydrophysical and hydrochemical data. On its basis, seven regions of the Kara Sea were identified, and for each region, the main characteristics are presented and the factors governing them are highlighted. The results can be used to reconstruct the seasonal variability of hydrophysical and hydrochemical parameters, as well as to analyze their interannual variability in different regions of the sea in order to study climatic change response. [ABSTRACT FROM AUTHOR]

The Earth exhibits an equatorial flattening specified by the ellipticity and the east longitude (or orientation) of the equatorial major axis, which is uniquely determined by the degree 2 and order 2 gravitational coefficients, C22 and S22. The 31-year SLR (satellite laser ranging) and 22-year GRACE/GRACE-FO (gravity recovery and climate experiment) data are analyzed to study the climate-related secular and 5.7 years to decadal variations in C22 and S22, in turn, the drift and decadal variation in the Earth's equatorial ellipticity and orientation of the principal axis of the least moment of inertia. The effects of the surface floating mass changes (including atmosphere, ocean and surface water redistribution and the melting of the mountain and polar glaciers) and the interior fluid convective (Earth's core flows) were evaluated. Results reveal that the equatorial ellipticity of the Earth is linearly increasing along with a remarkable decadal variation and the Earth's equator is flattening by ~ 0.16 mm/yr. [ABSTRACT FROM AUTHOR]

Wireless power transfer (WPT) system in seawater exhibits distinct transmission characteristics from those in air due to the unique properties of seawater medium and the complexity of the seawater environment. In this paper, transmission characteristics of a 2-transmitter (2TX) and 1-receiver (1RX) WPT system in the frequency band of 350 ~ 550 kHz in seawater are investigated. When the transfer distance is at midrange, the maximum load voltage point of the system is shifted from 460 to 430 kHz compared to that in air, and the maximum transfer efficiency is 7 times of that in air, which is very different from the traditional view that the transfer efficiency in water is always worse than in air. The system maintains a stable output voltage when the receiving coil is at different offsets. To grasp the influence mechanism of seawater on wireless power transfer, two new parameters, complex self-inductance and complex mutual inductance, are introduced into the circuit model to explain the shift of the optimal frequency and the increase of transfer efficiency, and the model is verified through experiments. [ABSTRACT FROM AUTHOR]

Holopelagic Sargassum spp. (sargassum) are the founding species of diverse communities in the Sargasso Sea. Since 2011, a new area of concentration of these algae was formed in the equatorial North Atlantic and Caribbean Sea. We analyzed elemental composition, and the small mobile fauna associated with sargassum collected at 41 stations, during two expeditions in the Caribbean Sea in 2018 and 2019, that covered open-sea stations in two marine ecoregions, and coastal stations (< 20 km from the shore) in one of them. Metal(loid) concentrations generally followed the order As > Zn > Cu > Cd > Se > Pb > Hg, and contents of As (195.5 ± 13.7 µg g−1), Cd (0.59 ± 0.02 µg g−1), and Hg (0.22 ± 0.09 µg g−1) were highest in S. fluitans III in the South-Western-Caribbean ecoregion. Mean [Ctot] per ecoregion varied between 26.1 and 30.1 mg g−1, and variation was mainly accounted for by higher [Cinorg] (likely produced by calcifying epibionts) in the South-Western Caribbean (10.12) compared to the Western Caribbean (8.92 and 7.19); this tendency that was also found for [Ntot] (between 1.06 and 1.27), and these contents were positively correlated with seawater chlorophyll concentrations. Sixty-six taxa of mobile fauna were identified, with the phylum Arthropoda being most abundant and diverse. The faunal community composition was similar in both open-sea regions, but differed in the coastal stations, which was mostly explained by differential relative abundance of Latreutes fucorum, Carpias minutus, Litiopa melanostoma, and some fish species. The Caribbean open-sea rafts harbor a diverse fauna comparable to that found in the Sargasso Sea, and likely provide similar ecosystem services, and thus merit similar protective efforts as those directed towards sargassum in the Sargasso Sea. [ABSTRACT FROM AUTHOR]

Marine Heat Waves (MHWs) occurrence has been increasing in the Mediterranean Sea. The effects of field simulated MHWs of different intensity (medium and high temperature) on the transcriptome expression of the endemic seagrass Posidonia oceanica were evaluated considering different origins of the plant. The aim of the study was reached through a common garden transplant experiment in the North-west of Sardinia (Italy), where two P. oceanica meadows characterized by different thermal regimes (cold and warm) were chosen. MHWs were simulated in front of a power plant, that creates a natural laboratory by releasing warm water in the sea. Differential gene expression and GO enrichment analyses highlighted differences in the transcriptomic profiles of plants from cold and warm environments suggesting that the MHWs induced different levels of stress due to different tolerance to the heat event. Plants from both origins activated processes to achieve protein homeostasis, but only cold plants activated an antioxidant defense and altered sugar metabolism, both indicators of heat stress. Within plants of the same origin, a different response to MHW intensity was also detected: while warm plants showed the most complex response at high temperature rather than at medium temperature, cold plants seemed to better cope with the medium temperature intensity rather than with high temperature. [ABSTRACT FROM AUTHOR]

The mechanism(s) of sodium, chloride and pH regulation in teleost fishes has been the subject of intense interest for researchers over the past 100 years. The primary organ responsible for ionoregulatory homeostasis is the gill, and more specifically, gill ionocytes. Building on the theoretical and experimental research of the past, recent advances in molecular and cellular techniques in the past two decades have allowed for substantial advances in our understanding of mechanisms involved. With an increased diversity of teleost species and environmental conditions being investigated, it has become apparent that there are multiple strategies and mechanisms employed to achieve ion and acid-base homeostasis. This review will cover the historical developments in our understanding of the teleost fish gill, highlight some of the recent advances and conflicting information in our understanding of ionocyte function, and serve to identify areas that require further investigation to improve our understanding of complex cellular and molecular machineries involved in iono- and acid-base regulation. [ABSTRACT FROM AUTHOR]

The results of high-precision direct determination of CO2 in the surface waters of the Black Sea are presented. These measurements made possible to obtain high precision characteristics of the content and intra-annual variations in pCO2 for the first time. The average annual value of pCO2 is 436 µatm, which is higher than the average annual value in the near-sea surface layer of the atmosphere (420 µatm). The seasonal variability has revealed decrease of pCO2 in seawater from late spring to fall. The minimum values of pCO2 are detected in January–February; the maximum ones, in July. The seasonal variations in the CO2 content in the near-sea atmosphere reveal an inverse relationship, with maximum values in February and minimum values in July. This indicates different mechanisms of the evolution of CO2 in the air and seawater. The content of CO2 in the atmosphere is determined by external sources and depends on the burning intensity of organic carbon. Variations in pCO2 in water is significantly affected by abiotic factors, such as the influence of temperature change on CO2 solubility and the state of the carbon system. In the summer–fall season, pCO2 is determined by a combination of abiotic and biotic factors, including variations in temperature and intensity of biological processes of organic matter transformation. Both the intensity and effect of these factors vary throughout the year, but the abiotic factor remains primay during the entire year. [ABSTRACT FROM AUTHOR]

The compressive strength of composite materials is critical for designers. This study investigates how seawater immersion influences the mechanical properties and compressive behaviour of solid and open-hole glass/epoxy laminates used in aircraft structures. The specimens were divided into three groups: first not immersed, second immersed in seawater for 30 days, and last sun-dried 12 hours after immersion. Immersion in seawater lowered the compressive strength of solid and open-hole specimens by 40 % and 33 %, respectively. The sun-drying process after seawater immersion increased the compressive strength of solid and open-hole specimens by 5 % and 17 %. After drying, the residual strength of solid and open-hole GFRP was 65 % and 84 %, respectively. In solid GFRP composites, the seawater immersion and drying process is irreversible; besides, in open-hole composites it can be reversible. The compressive examination was numerically duplicated using a finite element method (FEM) model of the composite material. [ABSTRACT FROM AUTHOR]

In tropical islands, calcareous sand with poor engineering properties usually needs to be treated before it can be used as building materials. Considering the scarcity of freshwater in these areas, this study proposes seawater-based enzyme induced carbonate precipitation (EICP) technology to enhance the properties of calcareous sand. It is to induce calcium carbonate crystals to bond calcareous sand particles together using the seawater-based crude soybean enzyme and cementation solution (i.e., urea and calcium chloride). In this study, the crude soybean urease extraction test was firstly carried out using seawater and it was also investigated what components of seawater had a greater effect on the soybean urease extraction. Afterwards, the solution test was conducted to explore the ability of the extracted urease in inducing calcium carbonate through analyzing the variation of concentration of calcium ions and pH of the solution. Finally, the biocementation effect of EICP treated calcareous sand using the seawater extracted urease solution was evaluated by the unconfined compressive strength (quc) and microscopic analysis. Test results show that the turbidity of the seawater-extracted soybean urease solution can be reduced by 66.7% compared to that of deionised water extracted urease, with only a slight reduction in urease activity. Among all the components of seawater, NaCl, MgCl2, CaCl2, NaHCO3 and KBr can significantly reduce the turbidity of soybean urease solution. The lower turbidity can effectively avoid bioclogging and contribute to the homogeneity of the EICP-treated calcareous sands, and thus improve the biomineralization efficiency and strength enhancement. Seawater-based EICP treatment will be a great promising technology in freshwater-scarce tropical islands, because it can directly use seawater for biomineralization treatment of calcareous sand, and meanwhile effectively avoid local clogging of biocementation. [ABSTRACT FROM AUTHOR]

This work successfully prepared a graphene/carboxymethyl cellulose/poly(amidoxime) aerogel named GCPA for uranium capture. Excitingly, GCPA exhibits superb mechanical properties (320 kPa). Additionally, the adsorption rate of GCPA remained above 90% even after 6 adsorption–desorption cycles. The results of the adsorption mechanism analysis show that GCPA adsorbed uranium mainly through electrostatic attraction, intraparticle diffusion, and coordination. It is worth mentioning that GCPA maintains good adsorption capacity for uranium in weakly alkaline environments. And GCPA has exceptional selectivity for uranium even in the presence of competing ions. Results show that GCPA is expected to be utilized in uranium extraction from natural seawater. [ABSTRACT FROM AUTHOR]

As an important underlying visual processing task, underwater image enhancement techniques have received a lot of attention from researchers due to their importance in marine engineering and lake ecosystem optimization. However, various underwater image enhancement algorithms have been proposed to be evaluated mainly with marine water body datasets, and it is not clear whether these algorithms can be performed on datasets collected from inland lakes in the freshwaters. To bridge this gap, for the first time, we construct an underwater image dataset for highland and freshwater-circumstances (HFUI) using 1000 real images to complement the underwater image datasets. In addition, we propose an unsupervised underwater image enhancement algorithm (HUFI-Net) specifically for this dataset to correct the sharpness and color of the images. This algorithm, as well as current advanced underwater image enhancement algorithms, was investigated qualitatively and quantitatively using this dataset to evaluate the effectiveness and limitations of various algorithms and to provide novel ideas for future underwater image enhancement research. We also further validate the generalization and effectiveness of the algorithm on the underwater image datasets of the UIEB and the RUIE. [ABSTRACT FROM AUTHOR]

We analysed the migratory behaviour of adult Northern Gannets (Morus bassanus) breeding at Helgoland in the North Sea, based on data obtained from geolocation devices in the non-breeding season 2016–2017. Birds moved east and south-west to a broad range of wintering sites, ranging from the western Baltic Sea to North-West Africa. Three out of 12 birds spent the winter in Africa, while 9 birds wintered in Europe, with the primary wintering sites in the North Sea. All but one tagged bird spent some time in the Baltic Sea or in the transitional waters between the North Sea and Baltic Sea. We also analysed data from online databases (dofbasen.dk, ornitho.de) and the German Seabirds at Sea database to explore the extent to which Northern Gannets used the western Baltic Sea, as well as the Kattegat and Skagerrak, during the winter months. Records of Northern Gannets in Danish waters have increased substantially over the last 18 winters, with particular increases in the Baltic Sea. There was also a notable increase in sightings of Northern Gannets in German Baltic Sea waters, but this occurred later than in the more northerly Danish waters. Both analyses demonstrated that Northern Gannets explored the western part of the Baltic Sea, as well as the Kattegat and Skagerrak, increasingly intensively. This recent increase in sightings is in accord with the establishment and exponential increase in the nearest breeding colony of Northern Gannets at Helgoland. [ABSTRACT FROM AUTHOR]

A reduced-order model (ROM) of the global oceans is developed by projecting the hydrostatic Boussinesq equations of motion onto a proper orthogonal decomposition (POD) basis. Three-dimensional POD modes are calculated from the ocean fields of an ensemble climate reanalysis dataset. The coefficients in the POD ROM are calculated using a regression approach. The performance of various POD ROM configurations are assessed. Each configuration is derived from an alternate sea-water equation of state, linking the density and temperature fields. POD ROM variants incorporating an equation of state in which density is a quadratic function of temperature, are able to reproduce the statistics of the large-scale structures at a fraction of the computational cost required to numerically simulate this flow. Due to the speed and efficiency of calculation, such reduced-order models of the global geophysical system will enable researchers and policy makers to assess the physical risk for a broader range of potential future climate scenarios. [ABSTRACT FROM AUTHOR]

Estuaries are nutrient-rich environments characterized by a gradient in salinity due to the mixing of freshwater and seawater. These bodies of water play vital functions in nature and provide a wide variety of essential ecosystem services. In general, many natural and/or man-made activities have strongly stressed the Egyptian Nile estuarine habitats, as has the water shortage that was expected after the construction of the Grand Ethiopian Renaissance Dam. In recent decades, the Nile Delta has been considered to be one of the most important productive oil-producing petroleum regions due to onshore and offshore gas discoveries alongside gasoline and base oil generation. Up-to-date systematic reviews of the Egyptian estuarine habitats (Rosetta and Damietta) are missing, and the review reported here was undertaken to fill this gap. In this review, we consider the physical, chemical, geological, pollution, and biological parameters of Egyptian Nile estuaries. In this context, our aim is to contribute to a broader understanding of the Egyptian estuarine habitat; moreover, we provide potential warning signals that may aid in estuarine environmental protection. We found that most of the previous studies had focused on the two branches of the Nile or on the marine waters adjacent to these branches, and that only a few studies focused on the estuarine habitats themselves. In most of these previous studies, the salinity gradient of water was reported to be a significant factor in the distribution of the different measured parameters while, in contrast, more recent investigations confirm the importance of potential effluent sources in affecting the distribution of these parameters. We highly recommend that the data reported here be updated in future studies on different environmental aspects. [ABSTRACT FROM AUTHOR]

The article presents the results of experimental studies of the sorption and desorption of rare-earth metal (REM) cations by the Co-bearing ferromanganese crusts of the Govorov Guyot. It has been established that the REM cations are sorbed on the CFC ore minerals (Fe-vernadite, vernadite, Mn-feroxyhite, and goethite. The crusts are characterized by high exchange capacity (1.78–3.57 mg-equiv/g, which increases in the following series: (Dy < Gd < Lu < Sm < Nd < Y, La < Eu) Ce. The REM cation sorption proceeds by the irreversible ion-exchange equivalent mechanism. The exchange complex of ore minerals consists of Na+, K+, Ca2+, and Mg2+ cations, which contribute 97‒98% to their total capacity. The crusts are characterized by the group sorption of REM cations from multicomponent water solutions of metal salts. The selectivity of manganese and ferruginous minerals of crusts to REM cations is significantly higher than to the main cations of ocean water. Experimental data on the desorption of sorbed REM cations with the NaCl solution suggest their irreversible sorption by ore minerals and strengthening of the chemical bond of sorbed REM cations with the main structural elements of these minerals over time. An important property of ore minerals, primarily manganese minerals, is their chemical and structural stability in aqueous electrolyte solutions, suggesting the repeated use of FMC as sorbents of REM cations. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) and nanoplastics (NaPs) in coastal regions, particularly in sediments, have gained increasing attention. However, in Türkiye, research on sediment pollution by MPs and NaPs is still limited. To fill this knowledge gap, the distribution, composition, and ecological impact of MPs and NaPs were investigated for the first time in the literature over a one-year period at three sampling stations on the south coast of Istanbul. The average total particle concentration was 1364.17 ± 600.51 particles.kg−1 dw sediment. Most of the MPs detected in the sediments were in the form of fibers with a size of 100–250 µm and were black and transparent. The study found that NaPs accounted for only 17%, 13.8% and 11.8% of the particles collected at stations S1, S2 and S3, respectively. According to the FTIR results, polyethylene and polyethylene terephthalate were the most abundant compared to polypropylene, polyamide and other polymers. The hazard index was classified as level V with a value of 17,261. This classification emphasizes the urgent need for further comprehensive studies on the risk assessment of MPs and NaPs. Scanning electron microscopy results showed microorganisms on the particle surface, indicating the MP-associated passing-through mechanism. Moreover, energy dispersive spectroscopy detected several unexpected elements such as Nb, Sr, Mo, Bi, Ta and Rn on MP and NaP surfaces. The results indicate that MP and NaP pollution in Istanbul’s coastal sediments may pose a major risk to the environment through the leaching of inherent/adsorbed elements and therefore requires future investigation. [ABSTRACT FROM AUTHOR]

The global spread of multidrug-resistant Escherichia coli threatens human, animal, and environmental health. Despite the recognition of water bodies as potential reservoirs, research on antimicrobial resistance (AMR) and antibiotic residues in the Baltic Sea is limited. In this study, we examined the presence of ESBL-producing E. coli in surface water in northeastern Germany. We then conducted phenotypic and genotypic analyses of the strains, which encompassed AMR and heavy metal/metalloid tolerance, biofilm formation, and detailed plasmid examination. In addition, we used solid-phase extraction with ultra-high performance liquid chromatography and mass spectrometry to quantify antibiotic residues. Our analysis identified 30 ESBL-producing E. coli isolates, some of which were associated with clinically relevant high-risk clonal lineages. We detected antibiotic residues in the environmental samples, but the antibiotic concentrations were significantly lower compared to wastewater samples. These results suggest that the Baltic Sea surface water could serve as a reservoir for ESBL-producing E. coli and clinically relevant antibiotics. [ABSTRACT FROM AUTHOR]

Antarctic Bottom Water (AABW), which supplies the lower limb of the thermohaline circulation, originates from dense shelf water (DSW) forming in Antarctic polynyas. Here, combining a long mooring record of DSW measurements with numerical simulations and satellite data, we show that significant correlation exists between interannual variability of DSW production in the Ross Sea polynyas, where DSW contributes between 20–40% of the global AABW production, and the Southern Annular Mode (SAM). The correlation is largest when the Amundsen Sea Low (ASL) is weakened and shifted east of the Ross Sea. During positive SAM phases, enhanced offshore winds and lower air temperatures over the western Ross Sea increase sea ice production and promote DSW formation, with the opposite response during negative SAM phases. These processes ultimately modulate AABW thickness in the open ocean. A projected positive shift of the SAM and eastward displacement of the ASL thus has implications for the future of DSW and AABW formation. This study shows that the formation of bottom water and the related sea ice processes in the Ross Sea are significantly affected by major climate patterns in the southern hemisphere's extratropical regions. [ABSTRACT FROM AUTHOR]

In the Casablanca-Mohammedia corridor (Morocco), flooding episodes have happened frequently over the past 20 years, damaging coastal settlements through overtopping and overflowing processes. In this context, a realistic assessment of the flood risk on this coastline is required. For this, the marine water level variations were computed by combining the involved variables (astronomical tide, storm surge, wave run-up, and sea level rise) during energetic events. They were compared with the seafront altitude to delineate the maximum spatial extent of flooded areas for the current and future (2100) time horizons. These variables were obtained through numerical and empirical modeling using topobathymetry, tide gauge, wind, and reanalysis data for wave and atmospheric pressure. Statistical methods were used to determine trends and distributions, including linear regression and the GEV model. Our approach was validated by comparing the estimated results of the total water level with the observations made in situ during previous events. Results show that flooding occurs mainly at high tides. The run-up is the largest contributor to total water level during energetic events (45–60% in structure defense areas against ~ 35% in natural areas). Currently, the floodable area for all of Casablanca-Mohammedia's coastline (109 km2) is estimated to be ~ 23.5 km2, of which ~ 13.9 km2 is urban. This area would grow by 10.87% and 20.9% by 2100, respectively. The most vulnerable zones are Mohammedia, Ain Sbâa, and Merzeg quarters, as well as Tamaris beaches. The touristic quarters of Ain Diab and the promenades on either side of the Hassan II Mosque are also vulnerable and can be dangerous for pedestrians. This study is crowned by the proposal of numerous necessary protection and adaptation measures, considering the specificities of the sections characterizing this coastline. [ABSTRACT FROM AUTHOR]

Fault fracture zones are rock formations commonly encountered in submarine tunnels, and the diffusion mechanism of slurry in fault fracture zones has a crucial impact on submarine tunnel reinforcement. Based on the seepage equation of Bingham fluid, the tortuosity parameter, fractal theory, and variable viscosity equation are introduced to establish a spherical permeation grouting model of Bingham fluid considering the slurry diffusion path and viscosity time variability. The viscosity variation law with time of sulfur aluminate cement slurry under different seawater admixture conditions was tested, and the time-varying equation of viscosity of sulfur aluminate cement slurry was obtained by fitting. A set of fault fracture zone permeation grouting test system was developed, and a fault fracture zone grouting simulation test was carried out. The study shows that the diffusion distance calculated without considering the influence of slurry diffusion path and seawater is 1.63–1.91 times of the test value, which obviously overestimates the diffusion distance; the diffusion distance calculated with considering the influence of diffusion path and seawater is 1.06–1.35 times of the test value, which is in good agreement with the test value. The research results can provide some theoretical support for the design of grouting in seawater environment. [ABSTRACT FROM AUTHOR]

Climate-driven changes in freshwater inputs have been shown to affect the structure and function of coastal ecosystems. We evaluated changes in the influence of river runoff on coastal systems of Northwestern Patagonia (NWP) over recent decades (1993–2021) by combined analysis of long-term streamflow time series, hydrological simulation, satellite-derived and reanalysis data on sea surface conditions (temperature, turbidity, and salinity). Significant decreases in minimum streamflow across a zone spanning six major river basins were evident at weekly, monthly, and seasonal scales. These changes have been most pronounced in mixed-regime northern basins (e.g., Puelo River) but appear to be progressing southward to rivers characterised by a nival regime. In the adjacent two-layer inner sea, reduced freshwater input corresponds with a shallower halocline and increased surface temperatures across northern Patagonia. Our results underscore the rapidly evolving influence of rivers on adjacent estuarine and coastal waters in NWP. We highlight the need for cross-ecosystem observation, forecasting, mitigation and adaptation strategies in a changing climate, together with corresponding adaptive basin management of systems that supply runoff to the coastal marine waters. [ABSTRACT FROM AUTHOR]

Perhaps the most dynamic component of the Arctic sea ice cover is the marginal ice zone (MIZ), the transitional region between dense pack ice to the north and open ocean to the south. It widens by a factor of four while seasonally migrating more than 1600 km poleward in the Bering–Chukchi Sea sector, impacting climate dynamics, ecological processes, and human accessibility to the Arctic. Here we showcase a transformative mathematical modeling approach to understanding changes in MIZ location and width, focusing on their seasonal cycles as observed by satellites. We view the MIZ as a liquid-solid phase transition region, or mushy zone, on the scale of the Arctic Ocean. Invoking the physics of phase changes, the MIZ is modeled as a dynamic, multiscale composite material layer; this model captures 96% of the annual cycle of MIZ location and 78% of the annual cycle of MIZ width. Temperature in the upper ocean is described by a nonlinear heat equation with effective parameters obtained using homogenization theory for a random medium of ice floes in a sea water host. Observations and simulations together indicate that MIZ location closely tracks the below-ice 273 K isotherm while the width of the MIZ follows vertical heat flux convergence, but with a three-week lag. [ABSTRACT FROM AUTHOR]

Sex-related differences in the expression of genes encoding prolactin (Prl1) in the brain and its receptors (PrlRa and PrlRb) in the brain, kidneys, gills, and intestine of the three-spined stickleback (Gasterosteus aculeatus L.) were studied in the context of freshwater adaptation. Males and females of the marine morph were adapted to freshwater for 72 h, and Prl1, PrlRa and PrlRb expression levels were assessed using RT-qPCR. In seawater, no sex differences in Prl1 expression in the brain were detected, but they appeared after freshwater adaptation due to significantly increased Prl1 expression in females. In seawater, PrlRa expression in the brain of females was significantly lower compared to males, but increased significantly after freshwater adaptation, becoming comparable in both sexes. PrlRb expression in the brain increased significantly in females following freshwater adaptation. In the kidneys, PrlRa expression was indistinguishable between females and males in either seawater or freshwater, but significantly decreased after freshwater adaptation in both sexes. PrlRb expression in the kidneys was sex-independent in seawater, but freshwater adaptation led to its significant increase in females and a decrease in males. In the gills, PrlRa and PrlRb expression was independent of both sex and salinity. In the intestine, PrlRa expression did not depend on either sex or salinity, whereas PrlRb gene expression also showed no sex differences, while decreasing in both sexes after transitioning to freshwater. It is concluded that the dependence of the prolactin osmoregulatory function on the sex of sticklebacks is manifested in sex differences in prolactin gene expression in the brain, as well as in the sensitization of the brain and osmoregulatory organs to this hormone during freshwater adaptation. [ABSTRACT FROM AUTHOR]

This research investigates the origins of high-salinity water in the southern Bay of Bengal (SBHSW) in summer (June to August) and its interannual variabilities associated with El Niño-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). The two distinctive sources of the SBHSW, including the eastern Arabian Sea (AS) origin and the western equatorial Indian Ocean (EIO) origin mentioned in the previous studies are identified. The eastern AS origin has much higher salinity (35.5 PSU vs. 35.2 PSU), shallower isopycnal layers (1023.0–1023.5 kg m-3 vs. 1024.0–1024.5 kg m-3), and intrudes into the Bay of Bengal (BOB) approximately one month later compared to the western EIO origin, while accounting for 53% of the total salinity variability compared to 47% contribution from the western EIO origin. The interannual variabilities of SBHSW are closely linked with ENSO and IOD events, with contributions of approximately 47% and 41%, respectively. During El Niño decaying years, high-salinity water export from the western EIO origin into the southern bay (< 7°N) is enhanced due to the anomalous strong spring Equatorial Undercurrent (EUC) associated with El Niño; while in the north of 7°N, the SBHSW was freshened both by the increased rainfall and by the downwelling associate with the anomalous anticyclonic wind. Similar processes operate but in an opposite direction during La Niña decaying years. In contrast, IOD exerts its influence on the SBHSW primarily through modulating the strength of SMC. Positive (negative) IOD caused the anomalous freshening (salty) SBHSW by weakening (enhancing) SMC and consequently advecting less (more) saline water into the BOB. [ABSTRACT FROM AUTHOR]

There are no reports of production and characterization of polysaccharides in the genera Chlorella and Spirulina cultivated in seawater (SW) and brackish groundwater (BGW). Furthermore, there are few studies on the cultivation of these microalgae in seawater for this purpose. Therefore, the aim of the study was to evaluate the production and composition of polysaccharides in Spirulina sp. LEB 18 and Chlorella fusca LEB 111 grown in seawater and brackish groundwater, with and without nutrient supplementation. In this study, 100% SW and 100% BGW were used as nutrient sources and supplemented with different concentrations of nitrogen, phosphorus, iron, and EDTA sources that make up the Zarrouk/BG-11 culture media. Cultivating Chlorella fusca LEB 111 in SW, without the addition of nutrients, resulted in an approximately 23% increase in starch production (g/g). The cultivation of Spirulina sp. LEB 18 in SW and BGW, without the addition of nutrients, showed an increase in glycogen concentrations (50.5 and 40.75 g/100 gbiomass, respectively) and highest levels of exopolysaccharides (0.34 and 0.50 g/100 gbiomass, respectively) compared to the control. Moreover, exopolysaccharides compositional analysis has shown an increase in glucose content with salinity, and a decrease in xylose and glucuronic acid. This cultivation strategy demonstrates the viability of utilizing SW and BGW as alternatives to freshwater culture medium for microalgae that have high nutritional requirements, with the potential to produce exopolysaccharides. [ABSTRACT FROM AUTHOR]

Deep biospheric anaerobic microbial sulfate reduction and oxidative sulfur cycling have been studied in long sediment cores mainly acquired as part of IODP explorations. The most remarkable observation in many of these studies is the existence of an active sulfur cycle in the deep subsurface sediments that have very low organic carbon content and are presumably refractory. Here, we investigate the interstitial sulfate concentrations and sulfur isotope ratios in a 290 m-long sediment core collected from the eastern Arabian Sea at a water depth of 2663 m. Continuous decrease in porewater-sulfate concentrations with depth (up to 75 mbsf) coupled with enrichment in δ34SSO4 values suggests organoclastic sulfate reduction (OSR) processes attributed to the activity of sulfate-reducing bacteria (SRB) and retention of labile organic substrates amenable to the SRBs. Below a depth of 75 mbsf, the absence of further reduction in sulfate concentration indicates insufficient labile substrate to drive sulfate-reduction activity. An increase in sulfate concentrations at the deeper subsurface (below 128.5 mbsf) coupled with decreasing δ34SSO4 values may be attributed to the oxidation of Fe-sulfide to sulfate. The increase in porewater alkalinity in the lower part of the core has been linked to the silicate degradation process by CO2 produced via the dissolution of CaCO3. Compilation of previous studies from this core, along with our investigation, intrigues future research on organic matter reactivity and microbiological activity in deeper subsurface under oligotrophic depositional regimes. [ABSTRACT FROM AUTHOR]