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In their recent paper, Williams et al. (2022) evaluated salinity management in the Murray-Darling Basin (MDB) as 'unsustainable', and a risk to water availability and quality in the Basin. However, this evaluation was weakened first by a failure to analyse the Basin salinity strategies of the last thirty-five years, noting that these have led to Basin salinity target being met since 2010; and second to not providing Basin-specific data to support their evaluation. Contrary to Williams et al. comments, existing evidence indicates that infrastructure intended to improve water use efficiency (e.g. salt leaching, salt disposal basins) will generally reduce stream salinity. The requirement for a leaching efficiency means that there is a lower limit to water use efficiency improvements, but this is unlikely itself to be a major risk. We agree that the changes that have occurred over the last twenty years would warrant a review of salt storage options in the MDB that better matches future needs. [ABSTRACT FROM AUTHOR]

The Shatt Al-Arab estuary is the lifeline of the Basrah city, as it is the source of water for various uses of irrigation, industry, agriculture and human use, in addition to being the navigational passage towards the Arabian Gulf throughout history. Nowadays, the estuary suffers from the deterioration of its water quality due to the increase in salinity values as a result of the intrusion of salinity from the Arabian Gulf due to the lack of freshwater flows from the Tigris and Euphrates rivers. To reduce the risks of water quality deterioration and the lack of natural solutions represented in the provision of freshwater, the idea of building an artificial structure to narrow the channel came to give the ability to resist the impact of the tide and the intrusion of marine salinity. Two hypothetical sites were chosen to build the structure: i.e. in Dweeb and Faw sites, to test the feasibility of this artificial estuary structure. A one-dimensional mathematical model was adopted, which is the Mike 11 software package. The model was run according to a set of scenarios using the critical water discharge values of 10 and 20 m3/s. The results showed through simulation of the model for a period of six months that the structure is useful on improving the water quality by reducing salinity in the river, in addition, there is a delay in the time of arrival of the intrusion of salts. [ABSTRACT FROM AUTHOR]

Mangroves are coastal ecosystems dependent on saline water conditions, although freshwater is seasonally present in most types of mangroves. The riparian mangroves have a greater influence of freshwater than salty water, reducing saline stress and allowing greater productivity and diversity. As they are associated with freshwater channels, their hydrology makes them both a source and a sink for sediments, nutrients, and organic matter. The wetlands adjacent to riparian mangroves are mainly freshwater swamps or marshes. To monitor the composition and abundance of the vegetation and the production of litter and roots in the midterm, 27 monitoring units were monitored (22 in mangroves, five in wetlands) in two periods (2015–2016 and 2018–2019). In them, we evaluated biotic characteristics and root production annually, and monthly the litter production and pore and river water salinity. We detected a gradient of salinity spatially and temporally. The salinity gradually decreased as the distance to the river increased. In the winter of 2018–2019 saline intrusion increased the interstitial and river water values by an average of 10 (interstitial water) and 16‰, (river water). This increase caused a significant decrease in litter and root production and augmented the cover of Laguncularia racemosa (freshwater marsh), mortality of herbaceous species (Acrostichum danaeifolium, Typha domingensis, Phragmites australis), and tree species such as Annona glabra and Acoelorraphe wrightii. [ABSTRACT FROM AUTHOR]

Human activities are not only increasing salinization of rivers, they might also be altering the temporal dynamics of salinity. Here, we assess the effect of human activities on the temporal dynamics of electrical conductivity (EC) in 91 Spanish rivers using daily measures of EC from 2007 to 2011. We expected rivers weakly affected by human activities to have low and constant ECs, whereas rivers strongly affected by human activities should have high and variable ECs throughout the year. We collected information on land use, climate, and geology that could explain the spatiotemporal variation in EC. We identified four groups of rivers with differences in EC trends that covered a gradient of anthropogenic pressure. According to Random Forest analysis, temporal EC patterns were mainly driven by agriculture, but de-icing roads, mining, and wastewater discharges were also important to some extent. Linear regressions showed a moderate relationship between EC variability and precipitation, and a weak relationship to geology. Overall, our results show strong evidence that human activities disrupt the temporal dynamics of EC. This could have strong effects on aquatic biodiversity (e.g., aquatic organisms might not adapt to frequent and unpredictable salinity peaks) and should be incorporated into monitoring and management plans. [ABSTRACT FROM AUTHOR]

Along coasts, biologically diverse terrestrial wetlands and marine ecosystems maintain complex hydrological connections that influence groundwater quality. The coastline of Florida's panhandle is home to globally rare coastal dune lakes that are hydrologically influenced by unique wet prairies within their watersheds. Little is known regarding how changes in ecosystem structure and composition of wet prairies influences groundwater chemistry within these coastal dune lake watersheds. To identify how physical and biological characteristics of terrestrial wetlands influence water chemistry, we analyzed water quality parameters along an upland to wetland gradient of shrub-encroached and fire-maintained wetlands within four of Florida's coastal dune lake watersheds between 2018 and 2021. Shrub-encroached wetlands had significantly higher (p ≤ 0.01) specific conductivity, salinity, acidity, and ion concentrations (Cl−, SO42−, K+, Na+, and Mg2+) than fire-maintained wetlands. Ions in groundwater were similar across the upland to wetland gradient with exception of chloride which was significantly lower (p ≤ 0.01) at upper slope positions where encroaching shrubs were less dense. The sulfate in groundwater was twice that of streams and salinity was most concentrated at the bottom slope positions. As results show that shrub encroachment has a measurable relationship with water chemistry, restoration of herbaceous wetlands through shrub removal may improve water quality and minimize future impacts to Florida's coastal dune lakes. [ABSTRACT FROM AUTHOR]

Florida spring-fed rivers are known for their submerged aquatic vegetation (SAV). which provides habitat for fish and aquatic crustaceans and food for the Florida manatee. Salinization of coastal spring-fed rivers due to climate change and sea level rise have been documented and can cause changes 10 SAV communities. This study investigated patterns and relationships between the SAV community and salinity of the Chassahowitzka River (Citrus County, FL, USA) to extrapolate the long-term effects of river salinization. A distinct dichotomy was seen in the SAV community structure: communities where salt tolerant Chaetomorpha spp. was present and communities where freshwater filamentous algae species were present. Freshwater filamentous algae demonstrated an inverse relationship with salinity. Chaetomorpha spp. replaced the freshwater filamentous algae in regions too salty for freshwater algae to grow. These patterns in the SAV community resulted in three different ecological zones in the Chassahowitzka River: low salinity/freshwater tidal, transition, and brackish zones. While freshwater filamentous algae and Chaetomorpha spp. were characteristic of the freshwater and brackish zones respectively, both species were identified within the transition zone. Utilizing the presence/absence of these macroalgae types could allow for an in-situ approach of characterizing regions of coastal spring-fed rivers that show increased salinization. [ABSTRACT FROM AUTHOR]

Simple Summary: Climate-related salinization of inland waters is observed in many regions of the world as a major environmental problem affecting natural processes in aquatic ecosystems. In order to better predict and control these changes, it is important to study the responses of aquatic fauna to increasing salinity. Macrozoobenthic fauna, which includes mollusks, small crustaceans, and insect larvae, constitutes the main food base for fish and water birds. Due to their relatively short life cycles, large species diversity, and high abundance, macrozoobenthos are the best indicators of changing water salinity. To determine the species richness, distribution, and salinity tolerance of macrozoobenthos, we investigated 17 small rivers with different water salinity in the southern arid region of the East European Plain. The study shows that the species richness gradually decreases with an increase in water salinity in the rivers. In freshwater rivers, the macrozoobenthos fauna includes more than 100 species, whereas, in hypersaline rivers with salinity comparable to seawater, only 10 species were found. A total of 5 of the 156 invertebrate species can be used as indicators of water salinization in rivers of the arid regions of Europe. This study investigated the species composition, distribution, and salinity tolerance of macrozoobenthos in 17 small rivers in the southern arid region of the East European Plain, which are characterized by a small channel gradient, slow-flowing or stagnant water bodies, and a wide range of water salinity, varying between 0.18 and 30 g L−1. In total, 156 taxa were found, among which 66 were Diptera species. The study revealed that the formation of benthic communities in the rivers is influenced by natural factors of the catchment basins, including the flat landscape with sparsely developed relief differentiation, climate aridity, and the widespread occurrence of saline soils and groundwater, largely related to the sedimentation of the ancient Caspian Sea and modern climate changes. These conditions are favorable for the occurrence of lacustrine macrozoobenthic species in freshwater, euryhaline, and halophilic ecological groups. The investigation revealed a decrease in species richness in response to an increase in water salinity. The five identified halophilic species Tanytarsus kharaensis, Glyptotendipes salinus, Cricotopus salinophilus, Chironomus salinarius, and Palpomyia schmidti can be used as indicators of river ecosystem salinization. [ABSTRACT FROM AUTHOR]

• Haihe River is a sluice-controlled coastal plain river showing both salinity and trophic gradients. • TSI posed a greater influence than salinity on the CDOM abundance. • TSI affected the CDOM abundance more than the fluorescence intensity. • Salinity affected the abundance of CDOM but rarely affected FDOM. Due to the combined effect of sluices and sea tide, the sluice-controlled coastal plain river would be characterized by both trophic state and salinity gradients, affecting the spatiotemporal optical properties of dissolved organic matter (DOM). In this study, we investigated the spatiotemporal variation of water quality parameters and optical properties of DOM in the Haihe River, a representative sluice-controlled coastal plain river in Tianjin, China. A significant salinity gradient and four trophic states were observed in the water body of the Haihe River. Two humic- and one protein-like substances were identified from the DOM by the three-dimensional fluorescence spectra combined with the parallel factor (PARAFAC) analysis. Pearson's correlation analysis and redundancy analysis (RDA) showed that the salinity significantly affected the abundance of chromophoric DOM (CDOM) but did not cause significant changes in the fluorescence optical characteristics. In addition, the effect of Trophic state index (TSI) on the CDOM abundance was greater than that on the fluorescence intensity of fluorescent dissolved organic matter (FDOM). In the water body with both salinity and trophic state gradients, TSI posed a greater influence than salinity on the CDOM abundance. Our results fill the research gap in spatiotemporal DOM characteristics and water quality variation in water bodies with both salinity and trophic state gradients. These results are beneficial for clarifying the joint influence of saline intrusion and sluices on the DOM characteristics and water quality in sluice-controlled coastal plain rivers. [Display omitted] [ABSTRACT FROM AUTHOR]

Heterosigma akashiwo is a unicellular microalga which can cause massive mortality in both wild and cultivated fish worldwide, resulting in substantial economic losses. Environmental parameters such as salinity, light, and temperature showed a significant effect on bloom initiation and the toxicity of H. akashiwo. While in previous studies a one-factor-at-a-time (OFAT) approach was utilized, which only changes one variable at a time while keeping others constant, in the current study a more precise and effective design of experiment (DOE) approach, was used to investigate the simultaneous effect of three factors and their interactions. The study employed a central composite design (CCD) to investigate the effect of salinity, light intensity, and temperature on the toxicity, lipid, and protein production of H. akashiwo. A yeast cell assay was developed to assess toxicity, which offers rapid and convenient cytotoxicity measurements using a lower volume of samples compared to conventional methods using the whole organism. The obtained results showed that the optimum condition for toxicity of H. akashiwo was 25 °C, a salinity of 17.5, and a light intensity of 250 μmol photons m−2 s−1. The highest amount of lipid and protein was found at 25 °C, a salinity of 30, and a light intensity of 250 μmol photons m−2 s−1. Consequently, the combination of warm water mixing with lower salinity river input has the potential to enhance H. akashiwo toxicity, which aligns with environmental reports that establish a correlation between warm summers and extensive runoff conditions that indicate the greatest concern for aquaculture facilities. [ABSTRACT FROM AUTHOR]

The large influx of freshwater and mixing of different water masses make simulating salinity challenging for the Bay of Bengal (BoB) region. This study analyses the variability of the simulated sea surface salinity (SSS) using models present in the Coupled Modal Intercomparison Project Phase 6 (CMIP6). We collected data for 37 models from CMIP6 and validated them against the Argo (2005-14) and Aquarius (2011-14) data. Based on the skill scores, we narrowed down our search to one CMIP6 model, viz. CIESM. This model was used to study the freshwater spread (FWS) in BoB during different seasons. We found that the correlation between pH and FWS was appreciable. The CIESM model was then used to project the future trends for 10 years for the tier-1 scenario. The trend analysis of future projections revealed a positive trend in SSP1-2.6, with a decreasing trend in SSP2-4.5 and SSP5-8.5. [ABSTRACT FROM AUTHOR]

Winter road salt use leads to the salinization of freshwater habitats. Freshwater organisms experience negative effects due to increased chloride ions, including algae in periphyton biofilms. This study examines the effects of road salt on algal assemblage composition, lipid production, and enzyme activity. Five streams throughout Erie County, New York, US were sampled monthly from October 2018 to March 2019. Chloride concentrations in all streams averaged 203.6 Cl- mg/L throughout the winter and had a highly significant relationship (rs = 0.82) with developed land use. Algal biodiversity scores decreased with elevated salinity (rs = 0.11). Algae exhibited the greatest total lipids in January (2.92 mg/m2) and the lowest in March (1.03 mg/m2). Similar trends were observed with x3 and x6 compounds. Overall desaturase D6 activity trended with stream Cl- concentrations, mainly along x6 pathways, suggesting an inflammatory stress response. Algal assemblages exhibited evidence of chronic salt exposure through impaired taxonomic composition and patterns of lipid production that followed trends in stream water salinity. These effects suggest road salt applications have negative effects on stream primary producers with consequences for higher trophic levels. [ABSTRACT FROM AUTHOR]

Salt pollution is a threat to freshwater ecosystems. Anthropogenic salt inputs increase lake and stream salinity, and consequently change aquatic ecosystem structure and function. Elevated salt concentrations impact species directly not only through osmoregulatory stress, but also through community‐level feedbacks that change the flow of energy and materials through food webs. Here, we discuss the implications of road salt pollution on freshwater rivers and lakes and how "one size fits all" ecotoxicity thresholds may not adequately protect aquatic organisms. This article is categorized under:Science of Water > Water QualityWater and Life > Nature of Freshwater EcosystemsWater and Life > Stresses and Pressures on Ecosystems [ABSTRACT FROM AUTHOR]

Species invasions are a global problem of increasing concern, especially in highly connected aquatic environments. Despite this, salinity conditions can pose physiological barriers to their spread, and understanding them is important for management. In Scandinavia's largest cargo port, the invasive round goby (Neogobius melanostomus) is established across a steep salinity gradient. We used 12,937 SNPs to identify the genetic origin and diversity of three sites along the salinity gradient and round goby from western, central and northern Baltic Sea, as well as north European rivers. Fish from two sites from the extreme ends of the gradient were also acclimated to freshwater and seawater, and tested for respiratory and osmoregulatory physiology. Fish from the high‐salinity environment in the outer port showed higher genetic diversity, and closer relatedness to the other regions, compared to fish from lower salinity upstream the river. Fish from the high‐salinity site also had higher maximum metabolic rate, fewer blood cells and lower blood Ca2+. Despite these genotypic and phenotypic differences, salinity acclimation affected fish from both sites in the same way: seawater increased the blood osmolality and Na+ levels, and freshwater increased the levels of the stress hormone cortisol. Our results show genotypic and phenotypic differences over short spatial scales across this steep salinity gradient. These patterns of the physiologically robust round goby are likely driven by multiple introductions into the high‐salinity site, and a process of sorting, likely based on behaviour or selection, along the gradient. This euryhaline fish risks spreading from this area, and seascape genomics and phenotypic characterization can inform management strategies even within an area as small as a coastal harbour inlet. [ABSTRACT FROM AUTHOR]

Freshwater salinization of rivers is occurring across the globe because of nonpoint source loading of salts from anthropogenic activities such as agriculture, urbanization, and resource extraction that accelerate weathering and release salts. Multidecadal trends in river salinity are well characterized, yet our understanding of annual regimes of salinity in rivers draining diverse central and western U.S. landscapes and their associated catchment attributes is limited. We classified annual salinity regimes in 242 stream locations through dynamic time warping and fuzzy c‐medoids clustering of salinity time series. We found two dominant regimes in salinity characterized by an annual summer–fall peak or spring decline. Using random forest regression, we found that precipitation amount, stream slope, and soil salinity were the most important predictors of salinity regime classification. Advancing our understanding of salinity regimes in rivers will improve our ability to predict and mitigate the effects of salinization in freshwater ecosystems through management interventions. [ABSTRACT FROM AUTHOR]

All landscapes, including estuarine islands, normally try to restore their geomorphic isostasy in all anthropogenic interventions on land dynamics. Munroe Island has been experiencing drastic environmental degradation, such as land subsidence, severe tidal/monsoon flooding, subsidence of build-ups and a drastic decay in agricultural productivity. This paper examines the role of anthropo-geomorphic interventions causing for the land degradation in Munroe Island through a multidisciplinary approach. Multidated, multiresolution satellite products and published maps, spanning a period of about six decades from 1960 to 2021, were used to understand the different geomorphic and geographical processes in the study area. Evaluation of the temporal bathymetric datasets, salinity measurements of the river and estuary, borehole data logs of the area and electrical resistivity surveys of the island were analyzed to find out the causative factors for the disturbances in the land neutrality, along with the tidal hydrodynamic changes in the region. The study shows about 14% of the total land area was vanished during the study period, and more than 25% of the area is under stress, leading to further land degradation. More than 500 households are forced to vacate their residence due to land subsidence/flooding. Lack of required freshwater and sediment supply from the Kallada river after the construction of the Thenmala reservoir in the Kallada river as well as the uncontrolled sand mining prevailed are the key factors for the environmental degradation of Munroe Island. The paper describes the role and colinkages of human-induced hydrogeomorphic interventions on a geomorphic system, in charge of the environmental degradation and land subsidence crisis of an estuarine island ecosystem and discusses the concerns related to the management strategies of such region. [ABSTRACT FROM AUTHOR]

The energy crisis is one of the most emergency problems that humanity is facing now. To alleviate energy crisis, some new energy sources different from traditional fossil energy are developed in the past decades, for example, nuclear energy, wind energy, solar energy, et al. Among these new energy sources, an important energy existing in the ocean and river named as salinity gradient energy benefits from the features of green, safe, low cost and huge amount, and comes into the researcher's sight. In this article, we review the recent progress in harvesting salinity gradient energy with reverse electrodialysis (RED) membrane. First, the mechanism of RED was introduced, including the basic structure and working principle of RED, the ion selectivity, and the ion rectification effect. The materials which are suitable for RED were discussed in detail, such as 1D nanofluidic nanochannels, 2D materials, and composite materials. Among these materials, 2D materials are thought to be one kind of powerful material for RED because of the feasibility of producing ion-selective membranes. Besides, we dwell on the influences of solution conditions on the RED performance, like the salt gradient and species, pH value, and so on. Finally, we discussed what the RED membranes need in theory and experiment to satisfy the practical application. And the large-scale production and the anti-fouling for the long-term running of RED membranes are two key issues needed to be solved through the analysis of this paper. [ABSTRACT FROM AUTHOR]

This study is to establish a new approach to estimate river salinity of semi‐arid agricultural watershed and identify drivers by using hydrologic modeling and machine learning. We augmented the limitations of the Soil and Water Assessment Tool (SWAT) to model salinity by coupling with eXtreme Gradient Boosting (XGBoost), a decision‐tree‐based ensemble machine learning algorithm. Streamflow, precipitation, elevation, main reach length, and dominant soil texture of the top two layers were used along with NO3, NO2, and total phosphorus (TP) output from a calibrated SWAT model are used as predictors to Total Dissolved Solids (TDS) in the XGBoost algorithm. Then, the SWAT model simulations of streamflow, NO3+NO2, and TP from 2000 to 2015 are used as inputs of the XGBoost model to predict monthly water TDS distribution along the river. The predicted river water TDS showed a higher concentration as going downstream from El Paso (inlet) through the Hudspeth canal to Fort Quitman (outlet). Finally, this study carried out cause analysis focusing on soil physical characteristics. The soil salinity level is directly affected by the soil permeability and irrigation water. As a result, the highest TDS is shown in sites with silt loam, whereas the lowest TDS was shown in sites with very cobbly soil. Silt soils can hold more water and are slower to drain than soils of a sand type. These analyses can be used to better understand the mitigation of water salinity. [ABSTRACT FROM AUTHOR]

The interfaces between small river plumes and ambient seawater have extremely sharp horizontal and vertical salinity gradients, often accompanied by velocity shear. It results in formation of instabilities at the lateral borders of small plumes. In this study, we use high-resolution aerial remote sensing supported by in situ measurements to study these instabilities. We describe their spatial and temporal characteristics and then reconstruct their relation to density gradient and velocity shear. We report that Rayleigh–Taylor instabilities, with spatial scales ~5–50 m, are common features of the sharp plume-sea interfaces and their sizes are proportional to the Atwood number determined by the cross-shore density gradient. Kelvin–Helmholtz instabilities have a smaller size (~3–7 m) and are formed at the plume border in case of velocity shear >20–30 cm/s. Both instabilities induce mass transport across the plume-sea interfaces, which modifies salinity structure of the plume borders and induces lateral mixing of small river plumes. In addition, aerial observations revealed wind-driven Stokes transport across the sharp plume-sea interface, which occurs in the shallow (~2–3 cm) surface layer. This process limitedly affects salinity structure and mixing at the plume border, however, it could be an important issue for the spread of river-borne floating particles in the ocean. [ABSTRACT FROM AUTHOR]

An inland waterway is to be constructed in an existing channel in West Java, Indonesia. The change of salinity in a river due to capital dredging was investigated using a finite element modelling system. The location of the research was the Cikarang Bekasi Laut (CBL) channel, Bekasi Regency, West Java, Indonesia. This study aimed to simulate salinity propagation in the CBL channel before and after capital dredging. Salinity modelling was carried out using Surface-water Modelling System (SMS) software. Field surveys of the topography, bathymetry, current velocity, and water level were conducted to develop the model. The model's results were validated with the current velocity and water level measured in the field. The field and model results agreed well with each other. The current and salinity results showed that the trends were correlated with river discharges. After capital dredging, the salinity in the CBL channel increased. Mitigation was carried out by constructing a check dam, which could reduce the average salinity in the upstream region by up to 0.05 ppt during the wet season and up to 0.12 ppt during the dry season. [ABSTRACT FROM AUTHOR]

Estuaries are dynamic environments which are driven by various natural processes like river discharge, tides, waves, influx of saline water and sediments, etc. These ecosystems are the most sensitive to sea level rise and fluctuations in river discharge associated with climate change. A direct response of sea level rise and river discharge can be observed in the water level of estuaries. However, existing models have not considered these parameters for forecasting water level. This paper focuses on developing a water level forecast model for the Chikugo River estuary in Japan using Nonlinear Autoregressive with Exogenous inputs (NARX Model). NARX neural network was used to do the one-step-ahead prediction of water level considering the various parameters that can very well be influenced by climate change: previous water level, river discharge, and salinity. Accordingly, three models were developed: (i) Model I considering previous water level; (ii) Model II additionally considering river discharge; and (iii) Model III additionally considering salinity. All the models showed appreciable performance in forecasting the water level. Model III had the best correlation with the water level with a cross-correlation value of 0.6030, while the river discharge had only a cross-correlation of 0.1113 indicating that the Chikugo River estuary is tide-dominated. The model was trained using different combinations of available data - previous water level, river discharge, and salinity. Cross-correlation results showed a better correlation between water level and salinity than various other combinations trained. Therefore, tidal intrusion influences the water level in the estuary, thereby depicting that sea level rise can affect the water level, and its influence can be well predicted by the developed model. The water level significantly affects the flora and fauna and the predictability of future estuarine floods can help in taking necessary mitigation strategies. • Water Level of Chikugo estuary forecasted using NARX model. • Analyzed the influence of previous water level, discharge and salinity. • Water level has more cross-correlation with salinity than discharge. • Forecasted the water level for various river discharge and salinity. • Model capable to analyse the influence of climate change on water level. [ABSTRACT FROM AUTHOR]

The need to feed an increasing population while limiting the environmental impact of agriculture is currently one of the greatest challenges relating to the food chain. One of the key factors involved in doing this is irrigation, which has a downstream impact that can be minimised if nutrient and water management are efficiently undertaken. The objective of this study was to determine which irrigation management improvements can be done at field scale in modern irrigated areas to reduce its irrigation return flow impact. The study was conducted in the Noguera Ribagorçana River basin, in NE Spain, where almost 6000 ha of land were brought into irrigation from 2000 to 2009. We based our study on a water quality dataset, measured in four different sites along a 29 km2 stretch of the river over a period of 20 years. Our results show an increase in nitrate (from 1.7 mg·L−1 to 10.5 mg·L−1) and salt concentrations (electrical conductivity from 297 to 675 µS·m−1) in the downstream course of the river compared to the most upstream monitoring site. That was exclusively associated with the irrigation return flows from the newly irrigated area. The highest nitrate and salt concentrations are found during the non-irrigation season which corresponds to the local rainy season. To reduce this impact, better irrigation management is required. Autumn leaching could be lowered by reducing irrigation volume applied during the final weeks of crop cycles in order to allow the soil to retain the volume of water received from rainfall. To deal with this issue, we propose a methodology based on soil moisture to determine the end of the irrigation season. In this way, the impact on ecosystems located further downstream would be reduced while crop yields and productivity in the area could be maintained. • Irrigation returns flows caused an increase in nitrate (1.7 mg·L−1 to 10.5 mg·L−1) and salinity in the river. • Irrigation in the studied area did not increase phosphorus concentration in the river. • Water quality in the river worsens during the non-irrigation months. • Reducing irrigation depths at the end of the season would lower the impact in the river. • A methodology based on soil moisture is proposed to reduce irrigation. [ABSTRACT FROM AUTHOR]

Premise: Gene flow in riparian ecosystems is influenced by landscape features such as orography, climate, and salinity. The downstream increase in genetic diversity (DIGD) hypothesis states that the unidirectionality of the watercourse causes an accumulation of genetic diversity toward downstream populations, while upstream populations are more structured and less diverse, especially in water‐dispersed organisms. Methods: We used chloroplast and nuclear microsatellites to characterize genetic diversity, structure, and gene flow patterns among populations of Salix humboldtiana across an elevation and salinity gradient on three rivers (Actopan, Antigua, and Blanco) in Mexico. We used optimization of resistance surface methods to determine whether genetic distances between populations are correlated with landscape features. Results: Positive FIS values evidenced biparental inbreeding in some populations, particularly at higher elevations where lower niche availability constrains colonization and persistence. Four genetic groups were distinguished, corresponding to populations on the Actopan and Antigua rivers and upstream and downstream on the Blanco, but with high admixture between populations on the Actopan and Antigua rivers. Higher gene flow rates were found among proximate populations on the same river than among different rivers. Genetic diversity increased toward the river mouths, in support of the DIGD hypothesis, probably due to greater niche availability and larger population size. Differences among rivers in precipitation patterns and salinity, as well as geographic distance, were significant predictors of gene flow. Conclusions: Our results depict that the DIGD and gene flow patterns in S. humboldtiana result from the complex interaction among physiography, climate, river salinity, and life‐history traits of the species. [ABSTRACT FROM AUTHOR]

Coastal rivers and estuaries provide habitat and migratory corridors for freshwater estuarine-opportunists. We evaluated movement patterns of 61 blue catfish (Ictalurus furcatus) in the tidal York and Rappahannock rivers in Virginia, USA with acoustic telemetry from July 2015 to June 2016. To evaluate river-specific movements, we utilized a multistate Cormack–Jolly–Seber (CJS) model within a Bayesian framework to estimate probabilities of detection and transition (movement) among established salinity zones (i.e., tidal-fresh (0‰–0.5‰), oligohaline (>0.5‰–5‰), mesohaline (>5‰–18‰)). We considered flow as an environmental covariate. Despite high site fidelity in tidal-fresh zones, some individuals displayed movements into oligohaline and mesohaline habitats indicative of partial migration. Once downstream movement occurred, the probability of staying in the new salinity zone was higher than the probability of movements to other salinity zones. In the Rappahannock River only, movement upstream from mesohaline habitats was associated with below average flow. As flow increased, the probability of remaining in oligohaline and mesohaline zones increased. Our study shows blue catfish can move into downstream areas of tidal rivers with elevated salinities and that increased freshwater flow may allow them to remain in these habitats for extended durations. [ABSTRACT FROM AUTHOR]

The quality of water intended for irrigation is mainly determined by the content and type of salts present in it. The purpose of this research is to evaluate Yamanigüey River's water quality for agricultural irrigation in 12 samples taken throughout the basin in preliminarily way. Performance of physicochemical parameters was evaluated and water quality was determined based on the values of sodium adsorption ratio, electrical conductivity, irrigation coefficient, potential salinity and effective salinity. It is concluded that waters on Yamanigüey River have a good to excellent quality and, according to Riverside standards, its water is suitable to use in agricultural irrigation, except in very low permeability soils for salinity and sodium sensitive crops. [ABSTRACT FROM AUTHOR]

Salinity is a classic problem in water quality management since it is directly associated with low water quality indices. Debate continues about selecting the best model for water quality forecasting, it remains a major challenge and causes much uncertainty. Accordingly, identifying the optimal modelling that can capture the salinity behaviour is becoming a common trend in recent water quality research. This study applies novel combined techniques, including data pre- processing and artificial neural network (ANN) optimised with constriction coeffi- cient-based particle swarm optimisation and chaotic gravitational search algorithm (CPSOCGSA) to forecast monthly salinity data. Historical monthly total dissolved solids (TDS) and electrical conductivity (EC) data of the Euphrates River at Al- Musayyab, Babylon, and climatic factors from 2010 to 2019 were used to build and validate the methodology. Additionally, for more validation, the CPSOCGSA-ANN was compared with the slime mould algorithm (SMA-ANN), particle swarm optimisation (PSO-ANN) and multi-verse optimiser (MVO-ANN). The results reveal that the pre-processing data approaches improved data quality and selected the best predictors’ scenario. The CPSOCGSA-ANN algorithm is the best based on several statistical criteria. The proposed methodology accurately simulated the TDS and EC time series based on R² = 0.99 and 0.97, respectively, and SI = 0.003 for both parameters. [ABSTRACT FROM AUTHOR]

The implementation of air gap membrane distillation systems is limited by a lack of overall performance predictions which rely on few available pilot-scale studies. This study evaluates the productivity, energy consumption, and selectivity of a pilot-scale air gap membrane distillation system by combining experiments and modeling activities. The effect of operating conditions, i.e., applied vacuum, feed flow rate, and feed stream salinity, was investigated to identify regulating factors and quantify dependencies. Response surface methodology was applied to model the phenomena and provide statistical analysis. Increasing flow rates produced a near linear increase of productivity within the investigated range. Operating at higher applied vacuum also translated into enhanced productivity, though the distillate flux increased by a maximum of 10 % when vacuum increased from −100 mbar to −500 mbar. Flow rate and vacuum also governed the observed salt flux by a similar magnitude because salt flux resulted mainly from liquid pore flow phenomena. The trans-membrane pressure regulated the membrane rejection: increasing the pressure difference led to a lower rejection. Moreover, high feed stream salinity lowered both the productivity and the distillate quality. The productivity gains were typically achieved at the expense of an increase in specific thermal energy consumption; however, an interesting relation was observed with feed stream salinity, with a minimum of specific thermal energy consumption of roughly 300 kWh th ⋅ m − 3 identified in the treatment of a stream with a salinity of 150 g / L. [Display omitted] • Productivity, selectivity, and energy consumption were investigated in AGMD. • Feed flow rate and applied vacuum solidly correlate with distillate flux and STEC. • The distillate quality is regulated by the relative rate of vapor and liquid flow. • The total pressure difference across the membrane governs the system rejection. [ABSTRACT FROM AUTHOR]

Saltwater intrusion is a natural mixture process between watershed freshwater and seawater that frequently occurs in estuaries. Station-based monitoring of saltwater intrusion is time-consuming and labor-intensive. To enable quick monitoring of saltwater intrusion, this study developed new remote sensing algorithms for water surface salinity measurement using four decision tree-based machine learning models. These models were built based on simultaneously collected in-situ salinity data from a waterway in the Pearl River Delta and Unmanned Aerial Vehicle (UAV) hyperspectral images. A 10-fold cross-validation was applied to assess the performance of the models, with XGBoost outperforming the other three models (R 2 =0.93, RMSE = 0.88 psu). Then the developed model was employed for Sentinel-2 multispectral satellite images to invert the estuarine salinity distribution at a larger spatial scale. Results displayed the high performance of the machine learning models proposed in this study for mapping the salinity distribution in river channels, making it an efficient and practical technique for monitoring saltwater intrusion in river channels at a regional scale. [Display omitted] • We developed a ML method to predict estuary salinity from UAV data. • Model's versatility extends to large-scale monitoring with satellite images. • Feature importance enhances predictor selection, boosting model practicality. • Validation underscores high accuracy of the method in estuary salinity mapping. [ABSTRACT FROM AUTHOR]

For the first time, an assessment of the taxonomic and quantitative structure of the phytobenthos of seven saline rivers in the basin of the hypersaline Lake Elton (Volgograd region) is presented. The main types of algal communities developing on substrates were revealed: diatom phytobenthos, communities of diatoms with cyanoprokaryotes, cyanobacterial films and mats, and epiphyton. The phytobenthos consists of local, mosaic-distributed communities with a small similarity in their species composition. The structure of algal communities is determined by Bacillariophyta (with the predominance of species of g. Navicula) and Cyanoprokaryota (of the gg. Phormidium, Leptolyngbya, and Geitlerinema). The abundance and biomass values vary widely, reaching their highest values (109 834–417 472 million cells/m2 and 523.6–567.6 g/m2) in cyanobacterial communities of mesohaline rivers at a water salinity reaching 16–19 g/L. Mineralization as a factor influencing the structure of communities most rigidly acts in the mouth sections of rivers, by controlling the composition of the dominant species. For critical salinity values (>70 g/L), characteristic structural transformations of communities by the type of replacement of planktonic and benthic Bacillariophyta and Cyanoprokaryota by planktonic Chlorophyta (of the g. Dunaliella) and picoplankton were revealed. [ABSTRACT FROM AUTHOR]

For the first time, an assessment of the taxonomic and quantitative structure of the phytobenthos of seven saline rivers in the basin of the hypersaline Lake Elton (Volgograd region) is presented. The main types of algal communities developing on substrates were revealed: diatom phytobenthos, communities of diatoms with cyanoprokaryotes, cyanobacterial films and mats, and epiphyton. The phytobenthos consists of local, mosaic-distributed communities with a small similarity in their species composition. The structure of algal communities is determined by Bacillariophyta (with the predominance of species of g. Navicula) and Cyanoprokaryota (of the gg. Phormidium, Leptolyngbya, and Geitlerinema). The abundance and biomass values vary widely, reaching their highest values (109 834–417 472 million cells/m2 and 523.6–567.6 g/m2) in cyanobacterial communities of mesohaline rivers at a water salinity reaching 16–19 g/L. Mineralization as a factor influencing the structure of communities most rigidly acts in the mouth sections of rivers, by controlling the composition of the dominant species. For critical salinity values (>70 g/L), characteristic structural transformations of communities by the type of replacement of planktonic and benthic Bacillariophyta and Cyanoprokaryota by planktonic Chlorophyta (of the g. Dunaliella) and picoplankton were revealed. [ABSTRACT FROM AUTHOR]

Salinization of streams, rivers and other water sources threaten the civilizations, ecologies enduring constituent species that results in rendering the precious water unusable for human chores. Increase in salinity across the flow in streams and wet-lands have been mostly to raise a concern towards salt tolerance to various limits. Hence, it becomes important to monitor the acidity/alkalinity causing water parameters that can be referred to as salinity. The prime measure scale of salinity is the quality of potential-of-hydrogen (pH) present in river waters at two sample locations. Two locations that have been identified by CPCB as per the highly reported pollutants' level found, have been analysed through artificial-intelligence (AI) conjucted with Multivariate Adaptive Regression Spline (MARS). The hybrid of wavelet neuro-fuzzy inferences with that of MARS (WNF-MARS) predicted with more accuracy. Simulation of performance measures: root meant square error (RMSE); mean absolute error (MAE); goodness-of-fit (R2) together with their execution time for the three prototypes provided remarkable results. RMSE outcomes diminish on the whole on applying the training and validating data division in Wavelet conjucted MARS and WNF-MARS as compared to studying the data through MARS. Goodness-of-fit statistic analysed the concentration levels of salinity in the river at the identified sites. Thus, it is observed from this study that the pH levels provide future estimation of inapt quality of water at the source, so that it prohibits the further-decay of water consumed in the ecosystem. Thus, these predictors would be helpful towards formulation of strategies for protection of vegetation and other required purposes. [ABSTRACT FROM AUTHOR]

Phragmites australis is the dominant species in the Yellow River Delta and plays an important role in wetland ecosystems. In order to evaluate the relationship between phenotypic variation and environmental factors, explore how functional traits respond to changes in electrical conductivity and soil water content, and reveal the ecological strategies of P. australis, we investigated the ecological responses of P. australis to soil properties based on 96 plots along the coastal–inland regions in the Yellow River Delta of China. Within the range of soil water content (SWC, 9.39%–36.92%) and electrical conductivity (EC, 0.14–13.29 ms/cm), the results showed that (a) the effects of salinity were more important than the soil water content for the characterization of the morphological traits and that plant functional traits including leaf traits and stem traits responded more strongly to soil salinity than soil water content; (b) compared with morphological traits such as average height and internode number, physiological traits such as SPAD value, as well as morphological traits closely related to physiological traits such as specific leaf area and leaf thickness, showed stronger stability in response to soil water and salinity; and (c) under the condition of high electrical conductivity, P. australis improved its water acquisition ability by increasing indicators such as leaf water content and leaf thickness. In addition, with the increase in plant tolerance to stress, more resources were used to resist external stress, and the survival strategy was inclined toward the stress tolerator (S) strategy. Under low EC conditions, P. australis increased specific leaf area and leaf area for its growth in order to obtain resources rapidly, while its survival strategy gradually moved toward the competitor (C) strategy. [ABSTRACT FROM AUTHOR]

On the basis of theoretic-probability analogies, a quantitative characteristic of diversity of the river delta, the variance, is proposed. The series of computer experiments with a hydrological model demonstrate that an increase in the variance of the delta structure reduces the intraannual amplitude of fluctuations in salinity of the closing reservoir. The simulations for the Don River and Taganrog Bay (the Sea of Azov) used as the closing reservoir show that modern climatic change and anthropogenic factors reduce the proper functioning of the River Don arms. Therefore, there is a prospect of decrease in the variance of river runoff and, hence, destabilization and increase in the variability of salinity in the closing reservoir. [ABSTRACT FROM AUTHOR]

Salinity is related to the quantity of salt in rivers, and that salt can take several different forms. Salinity is determined by water evaporation to dryness, and form residual measuring. The total salt content in water can in influence the taste of water. Drinking water at levels of salinity greater than around 1.0 g/L is drastically and rapidly unpalatable. In this research, two models, the internal wave hydrodynamic model and the salinity dispersion model, are proposed. The internal waves hydrodynamic model provides salinity internal wave and salinity flow velocity. The salinity dispersion model provides the salinity level. A modified salinity control model is also used in a river with a barrage dam. The suggested model provides salinity control releasing fresh water from a barrage dam where the salinity level is not higher than the standard and does not waste too much fresh water. An explicit finite difference method which is unconditionally stable is used for approximating the degree of salinity from the proposed model under many conditions. [ABSTRACT FROM AUTHOR]

Zero liquid discharge (ZLD) has shown to be a promising technology to recycle water with good quality. The ZLD objective is to purify the water from all the liquid waste. The ZLD approach is concentrated on reducing wastewater for possible reuse. In conventional ZLD systems, thermal processes are fundamental. The biggest challenge to implement thermal ZLD systems widely is its intensive energy consumption. As a solution, thermal ZLD systems are integrated with membrane-based reverse osmosis (RO) technology to reduce both capital and operational costs. This study, therefore, focuses on the optimizing a RO/thermal ZLD system based on one of the most important parameters of design—the salinity of the reject brine of evaporator. To give more practical aspect to the results, solution is based realistic design data of a petrochemical complex as the producer of ammonia (2050 ton day−1) and urea (3250 ton day−1). Results show that increasing the salinity of brine stream in evaporator reduces the total required heating surface area of the ZLD plant as well as its required power. This decrease is evident at lower amounts of Xb, but the rate is lowered with increasing of this parameter. So, further increase in Xb does not have much effect on reducing the total heating surface area and power consumption. It means that there is an optimum amount of Xb which can be selected for different applications. [ABSTRACT FROM AUTHOR]

To investigate the effects of river waters on estuarine seagrass, the tropical seagrass Halophila ovalis was collected at Brunei Bay, Borneo, and was cultured under laboratory conditions for 18 days. Three treatments were set up in the experiment: natural seawater with a salinity 30 (S30), estuarine river water with a salinity 10 (S10), and the intermediate water that was composed of the seawater and river water with a salinity 20 (S20). New leaf production, the average length of new leaves, rhizome elongation, and photosynthetic rate of H. ovalis were significantly higher in S20 than S10. Chlorophyll a (chl a) and carotenoid content in H. ovalis were significantly lower in S10 than S20 and S30. Though the tropical river waters could potentially cause both positive and negative effects on seagrass, the present results suggested that low salinity would be the most influential factor to hinder the growth and metabolism of H. ovalis, and the salinity threshold was observed between 10 and 20. These results suggested that H. ovalis may be able to extend its present distribution to the upper estuary at this study site in the future. [ABSTRACT FROM AUTHOR]

This study starts from a two‐layer 1D Estuary Box Model (EBM), the so called Centro Euro‐Mediterraneo sui Cambiamenti Climatici (CMCC) EBM (Verri et al., 2020, https://doi.org/10.1016/j.ocemod.2020.101587), devised to offer a proper representation of the net river release in a coupled modeling framework with hydrology models and ocean models reaching the mesoscale. Two key advances are proposed in the present study: (I) the estuary length and (II) the horizontal eddy diffusivity coefficient are no longer considered as static parameters to calibrate but two non‐dimensional equations have been introduced in order to make them time‐variable. The Goro branch of the Po river delta is considered as case study of "salt‐wedge estuary" flowing into a microtidal sea. Regarding the estuary length, a non‐dimensional equation has been tested and validated. This equation provides a time dependent estuary box volume which is more realistic choice. This time‐variable estuary length represents the length of the salt wedge intrusion. Regarding the horizontal eddy diffusivity, the static eddy coefficient adopted in the previous version of the model is a coarse assumption. Thus a non‐dimensional equation for this coefficient has been tested and validated. It makes the eddy diffusivity dependent on the velocity shear, the salinity gradient and the estuary geometry. The proposed dynamic formula is found to enhance the model capability to reproduce the salinity at the estuary mouth. Overall the high statistical performance in terms of RMSE and correlation coefficient, the short CPU time and the minimal calibration encourage to use the CMCC EBM in coupled mode with both mesoscale‐resolving ocean and hydrology models to produce operational forecasts and climate scenarios. Plain Language Summary: The Centro Euro‐Mediterraneo sui Cambiamenti Climatici Estuary Box Model is placed in the framework of developing a conceptual and numerical modeling approach to simulate the effects of river release on the coastal to open sea circulation and dynamics. The few kilometers resolution of mesoscale ocean models cannot explicitly resolve the estuary dynamics; thus, the idea of an "estuary box model" that gives reasonable values of water volume flux and salinity at the river mouth, which in turn affects the ocean dynamics. A further development of the model equations is offered in this article and is demonstrated to enhance the model capability to reproduce the salinity at the estuary mouth; moreover, the length of the salt wedge intrusion is considered a model unknown. The research is not only interesting from an academic point of view but also for its practical application: (i) introducing an information on river release into ocean models, from regional to global scale, can improve their performance and produce more realistic operational forecasts or climate scenarios; (ii) introducing an estimate of the length of the salt wedge contributes to address the pressing issue of salt water intrusion and salinization processes in coastal areas. Key Points: An Estuary Box Model is devised to represent the salt‐wedge intrusion length and the net river release at the estuary mouthTwo key advancements, that is non‐dimensional equations for time‐variable estuary length and eddy diffusivity, enhance the model performanceThe proposed model is suitable for coupling with mesoscale ocean and hydrology models to produce operational forecasts and climate scenarios [ABSTRACT FROM AUTHOR]

Global and regional water cycle includes precipitation, water vapor divergence, and change of column water vapor in the atmosphere, and land surface evapotranspiration, terrestrial water storage change, and river discharge, which is linked to ocean salinity near the river mouth. The water cycle is a crucial component of the Earth system, and numerous studies have addressed its individual components (e.g., precipitation). Here we assess, for the first time, if remote sensing and reanalysis datasets can accurately and self-consistently portray the Amazon water cycle. This is further assisted with satellite ocean salinity measurements near the mouth of the Amazon River. The widely used practice of taking the mean of an ensemble of datasets to represent water cycle components (e.g., precipitation) can produce large biases in water cycle closure. Closure is achieved with only a small subset of data combinations (e.g., ERA5 precipitation and evapotranspiration plus GRACE satellite terrestrial water storage), which rules out the lower precipitation and higher evapotranspiration estimates, providing valuable constraints on assessments of precipitation, evapotranspiration, and their ratio. The common approach of using the Óbidos stream gauge (located hundreds of kilometers from the river mouth) multiplied by a constant (1.25) to represent the entire Amazon discharge is found to misrepresent the seasonal cycle, and this can affect the apparent influence of Amazon discharge on tropical Atlantic salinity. [ABSTRACT FROM AUTHOR]

The salinity distribution in the estuarine channel network of a partially mixed estuary was investigated by quantifying salt intrusion length and stratification with response to tidal circulation, seasonal variation, topography, and river discharge. The studied Karnafuli River estuary responds to a power-law relationship between discharges and salt intrusion lengths with exponent −0.64. In the river network, two salinity sinks were identified, that is, a river confluence and a channel bend. At the estuary, the surface salinity level during the dry period increased by 1.2–1.9 times that of the wet period due to residual salinity. On the other hand, the surface salinity level during the wet period decreased due to high river discharge. Again, a high salinity pulse was observed during flood tide and lower concentration was found in surface salinity during ebb tide. The spring–neap transition also causes salinity variation, reaching the lowest concentration at the end of the neap tide-wet period. Applying a subgrid scale Horizontal Large Eddy Simulation model in Delft3D, the spatial distribution of salinity showed that during flood tide the centrifugal force acted stronger than the opposing barotropic pressure gradient, and the centrifugal force moves the low-density water toward the river bend, which resists salinity intrusion. High salinity stratification was observed with high freshwater discharge and low stratification was found at a shallow water depth of the estuary. The surface salinity responds faster than the channel bottom salinity flux with changing forcing conditions (tide and discharge), while the bottom salinity circulation follows an unsteady process. [ABSTRACT FROM AUTHOR]

The present study aims to estimate effective diahaline turbulent salinity fluxes and diffusivities in numerical model simulations of estuarine scenarios. The underlying method is based on a quantification of salinity mixing per salinity class, which is shown to be twice the turbulent salinity transport across the respective isohaline. Using this relation, the recently derived universal law of estuarine mixing, predicting that average mixing per salinity class is twice the respective salinity times the river run‐off, can be directly derived. The turbulent salinity transport is accurately decomposed into physical (due to the turbulence closure) and numerical (due to truncation errors of the salinity advection scheme) contributions. The effective diahaline diffusivity representative for a salinity class and an estuarine region results as the ratio of the diahaline turbulent salinity transport and the respective (negative) salinity gradient, both integrated over the isohaline area in that region and averaged over a specified period. With this approach, the physical (or numerical) diffusivities are calculated as half of the product of physical (or numerical) mixing and the isohaline volume, divided by the square of the isohaline area. The method for accurately calculating physical and numerical diahaline diffusivities is tested and demonstrated for a three‐dimensional idealized exponential estuary. As a major product of this study, maps of the spatial distribution of the effective diahaline diffusivities are shown for the model estuary. Plain Language Summary: Eddy diffusivity determines how intensively concentrations in a fluid are spreading due to turbulent motion. Here, we analyze the diffusivity that spreads salt concentration (i.e., salinity) across a surface of constant salinity (the isohalines), also called effective diahaline diffusivity. A new method is presented that calculates effective diahaline diffusivities based on the specific volume between two specified isohalines, on the salinity mixing within this volume as well as on the surface area of the isohalines. We define mixing as the rate of destruction of salinity variance per unit volume due to turbulent mixing processes. The method applies to computer models of ocean dynamics on scales ranging from coastal to global. In such models, the mixing is determined by statistical mathematical equations of turbulent processes, which is the so‐called physical mixing. In models, additional (numerical) mixing occurs due to numerical inaccuracies of algorithms that move around water masses passively with the currents, a process called advection. Using our method, the total effective diffusivity determined for each isohaline surface can be accurately separated into contributions from physical mixing and numerical mixing. We demonstrate the functioning of the new method for an idealized model simulation of an estuary. Key Points: Mixing and volume per salinity class determine effective diahaline diffusivityEffective diahaline diffusivity is split into physical and numerical contributionsIn an idealized estuary, largest effective diffusivities are found in the brackish waters of the navigational channel [ABSTRACT FROM AUTHOR]

The La Niña of 2007/2008 was particularly strong, so was the southward flow of the cold, nutrient-rich Changjiang (Yangtze River) Diluted Water (CDW) when the winter monsoon started to blow in the fall. Here we use shipboard data in 2008 in two transects, one in the southwestern East China Sea and one in the southern Taiwan Strait, to show that as late as April in 2008 the CDW was still clearly identifiable when the winter monsoon had weakened. Waters as cold as 16 °C with a salinity lower than 30 still occupied the southwestern East China Sea. Waters of 17 °C and S < 32 could also be found off the coast of China in the central Taiwan Strait. The concentration of NO3 + NO2 was higher than 18 μmol L−1 at both places, which was as much as 40 times higher than the northward moving South China Sea (SCS) water to the east. As a result, the Changjiang River plume may be a significant source of nutrients, particularly N, to the oligotrophic, N-poor SCS, especially in the La Niña years. Indeed, colder and more turbid CDW was more intense and went farther south in 2008 compared with the normal springs of 2006, 2007 and 2009. [ABSTRACT FROM AUTHOR]

• Uplifted landforms support diapir growth. • Impact of diapirism on drainage network diversion and truncation. • Episodic salt flow enhanced by erosional unloading. • Long term rates of diapiric uplift. This work analyses the Quaternary landforms, geomorphic changes and stratigraphic evidences of evaporite dissolution and halokinesis in the Estella salt diapir (Basque-Cantabrian Basin). The mapping of Quaternary deposits demonstrates that karstic subsidence and diapirism happen at the same time. The diapir geometry is characterised by a prominent 4.5 km-long fault scarp attributed to the uplift of the diapir and a fluvial gypsum escarpment along the northern and eastern diapir edges. The dissolution of the gypsiferous caprock is responsible for the development of a large number of collapse sinkholes, the local thickening of terrace deposits and a network of endokarstic conduits connected to saline springs that cause a notable increase in the salinity of the Ega river across the diapir (70% electrical conductivity increase). The 40 m vertical displacement of T4 terrace and P5 pediment deposits, the anomalous longitudinal profile of the old terraces, the deflection of infilled-valleys at the base of the fault scarp, the occurrence of wind gaps and the continuous lateral migration of the Ega river away from the diapir support salt upwelling since 644 ± 81 ka ago at a long-term, average uplift rate of 0.05–0.07 mm/yr. The 12 m offset of T8 terrace, the steepening of the Ega river floodplain and the tilting of the upper level and the antigravitative erosion genesis of the Longinos cave point to a faster diapir rising rate of 0.23–0.57 mm/yr in the last 36 ± 15 ka coinciding with a period of increasing river incision. The lack of tectonic activity in the region suggests that diapirism is enhanced by erosional unloading related to fluvial entrenchment. The thickening of pediment P5 supports the north-northeast flow of salt towards the river valley. [ABSTRACT FROM AUTHOR]

Electrical energy can be extracted from the mixing of two water streams with different salinity through the reverse electrodialysis (RED) technique. Ion exchange membranes (IEMs) are vital components for capturing the energy in the RED systems. Therefore, the design and fabrication of IEMs are essential to the enhancement of power production by the RED system. In this work, the novel cation exchange membranes (CEM) were prepared by sulfonated poly (2,6-dimethyl-1,4-phenylene oxide) as a polymer and MXene nanosheets as filler for the first time. The effect of polymer concentration and MXene loading on the electrochemical properties, membrane structure, and gross power output in the RED system was investigated in detail. An increase in MXene additive (0 to 2 %) significantly increased the permselectivity from 77.40 % to 91.25 %, and reduced the area resistance from 4.7 to 1.3 Ω.cm2 of fabricated CEMs (sPPO: 22 wt%). The results also showed that CEM was prepared by a solution containing 22 wt% of sPPO (1 wt% of MXene additive), and 19 wt% of sPPO (2 wt% of MXene additive) exhibited relatively desirable electrochemical properties for power generation. These membranes presented the highest gross power density (1.45 and 1.37 W.m−2, respectively) in RED experiments, which were significantly higher than the commercially available CMX membrane (1.01 W.m−2). • Novel CEMs were prepared and optimized with different loading of functionalized MXene and polymer concentration for use in the RED system. • The electrochemical and physical properties of fabricated CEMs and their relationship are discussed. • Fabricated CEMs showed high permselectivity (>90 %), conductivity, and low area resistance. • An increase in power density observed with optimal MXene loading. [ABSTRACT FROM AUTHOR]

Martdianto, R.; Muin, M.; Kusuma, S.B.; Muslim, A.B., and Alam, H.N., 2023. BOD-salinity simulation in the Sunter River Tanjung Priok port with a non-orthogonal model application. In: Lee, J.L.; Lee, H.; Min, B.I.; Chang, J.-I.; Cho, G.T.; Yoon, J.-S., and Lee, J. (eds.), Multidisciplinary Approaches to Coastal and Marine Management. Journal of Coastal Research, Special Issue No. 116, pp. 76-80. Charlotte (North Carolina), ISSN 0749-0208. Tanjung Priok port is the biggest port in Indonesia, located in the Capital City of Jakarta, equipped with two sides of a breakwater that protects the port from the direct impact of the sea. The Sunter river flow to Tanjung Priok port delivers high domestic waste as an influence of urban activities. The high content of BOD values along the Sunter river to Tanjung Priok increases the source of water pollution that needs to control correctly. Tanjung Priok also has pollution sources consisting of solid domestic waste, domestic liquid waste, and oil sludge. The Sunter river streamflow in the Jakarta drainage system is divided by Kanal Banjir Timur (KBT), changing flow rate, and water quality pattern. The study area is the Sunter river's main channel, which has a 17 km length and includes Duren Sawit, Pulo Gadung, Kelapa Gading, Plumpang, Rawa Badak, and Tanjung Priok. To describe the complexity of a river's geometric flow to an estuary along the Sunter river to Tanjung Priok, the concept of a curvilinear Non-Orthogonal model is used, which is careful in composing the river morphology shape, river-channel branching, dimension, and elevation of the river to the estuary. Efforts to improve water quality along the Sunter river by increasing saltwater's effect by carrying out a Density-Induced Current (DIC) and dredging configuration. Dredging at the mouths of rivers by considering the influence of DIC involves water currents, river flow, wind stress, and tides. The study presents several simulation scenarios using MuQual3D to assess water quality problems in the Sunter river by increasing salinity through river dredging. [ABSTRACT FROM AUTHOR]

Salinity in a river is a measure of the content of salts in water. Salinity intrusion problem pose hazards for a river as well as affecting human health and agriculture. There are two methods to measure the salinity in a river. First, the sampling water method by monitoring stations has been using to collect the actual data. Second, a mathematical model is introduced to predict the salinity in a river. In this research, a mathematical model of salinity measurement in a river with releasing fresh water from a diversion dam effect is proposed. There are two finite difference techniques are introduced to approximate the model solution. The traditional forward time centered space techniques are also introduced. A new fourth order finite difference method is employed to accurately approximate the salinity in a river. A part of the Chaopraya river which is closed to the estuary is experimented. The actual problem is focused in this research. The experiment suggested can be used in many practical measurements of the salinity. The proposed method will predict the salinity level in a period on the future. The computational salinity measurement gives precisely results when the actual salinity and numerical salinity are compared. The proposed numerical simulation can be applied to a salinity forecasting. [ABSTRACT FROM AUTHOR]

Capacitive deionization (CDI) is an emerging desalination technology for effective removal of ionic species from aqueous solutions. Compared to conventional CDI, which is based on carbon electrodes and struggles with high salinity streams due to a limited salt removal capacity by ion electrosorption and excessive co‐ion expulsion, the emerging Faradaic electrodes provide unique opportunities to upgrade the CDI performance, i.e., achieving much higher salt removal capacities and energy‐efficient desalination for high salinity streams, due to the Faradaic reaction for ion capture. This article presents a comprehensive overview on the current developments of Faradaic electrode materials for CDI. Here, the fundamentals of Faradaic electrode‐based CDI are first introduced in detail, including novel CDI cell architectures, key CDI performance metrics, ion capture mechanisms, and the design principles of Faradaic electrode materials. Three main categories of Faradaic electrode materials are summarized and discussed regarding their crystal structure, physicochemical characteristics, and desalination performance. In particular, the ion capture mechanisms in Faradaic electrode materials are highlighted to obtain a better understanding of the CDI process. Moreover, novel tailored applications, including selective ion removal and contaminant removal, are specifically introduced. Finally, the remaining challenges and research directions are also outlined to provide guidelines for future research. [ABSTRACT FROM AUTHOR]

Multieffect distillation with thermal vapour compression (MED–TVC) is one of the most attractive thermal desalination technologies for the production of freshwater. Several mathematical models were presented in the open literature to analyse the steady‐state performance of such process. However, these models have several limitations and assumptions. Therefore, there remains the challenge of having a reliable model to accurately predict the performance of the MED process. Thus, this research attempts to resolve this challenge by rectifying the shortcomings of the models found in the literature and create a new one. The robustness of the developed model is evaluated against the actual data of Umm Al‐Nar commercial plant situated in UAE. In seawater desalinisation, a large amount of high‐salinity stream (brine) is rejected back into the sea. This paper investigates the influence of the rejected (exit) brine temperature on the system performance parameters of MED–TVC process. Specifically, these parameters are considered as total heat consumption, gain output ratio, freshwater production, heat transfer area and performance ratio. Also, the particular parameters of TVC section of the entrainment ratio, compression ratio and expansion ratio are also addressed. Moreover, a critical evaluation of the influence of the rejected brine temperature on the seawater is also embedded. [ABSTRACT FROM AUTHOR]