Water Sources Research Articles

Nanoarchitectonics of Nickel Nitride‐V2CTX Mxene: An Efficient Bifunctional Catalyst for Alkaline Water/Seawater Applications

AbstractSeawater, being the most plentiful natural water source worldwide, is a highly abundant and cost‐efficient medium for producing hydrogen by alkaline water electrolysis. However, the advancement of seawater electrolysis is hindered by notable impediments caused by chloride corrosion at the anode and the simultaneous chlorine evolution process. Only a limited number of non‐noble electrocatalysts demonstrate noteworthy bifunctional catalytic efficacy and long‐term durability. In this regard, Nickel Nitride tailored V2CTX Mxene nanostructures is reported as a bifunctional catalyst for overall water/seawater applications. The optimized sample Ni3N@3000‐V2CTx exhibits low overpotential values of 90 and 300 mV in acidic and alkaline + seawater solutions respectively at 10 mA cm−2 for hydrogen evolution reaction. Similarly, this catalyst shows 70 and 240 mV overpotential values in alkaline water and alkaline + seawater solutions respectively at the same current density for oxygen evolution reaction. Synergetic effects of Multiple Vanadium and Nickel valency along with compelling nitrogen bonds creates elevated density of exposed functional sites for electrocatalytic activity. Furthermore, the notable electrochemical active surface area and mass activity suggest an enhanced and significant presence of abundant active sites. Additionally, the high stability and significantly decreased charge transfer resistance expedited the overall water/seawater‐splitting reaction rate.

Determinants of WASH programmes adoption in flood-prone Tsholotsho District, Zimbabwe

There is an increased frequency of floods in different parts of the world due to Climate Change and many countries in Sub-Saharan Africa face WASH challenges which have worsened during flood and drought incidences. Tsholotsho District has been experiencing an increased frequency of floods over the years and WASH situation has continuously deteriorated. To build the resilience of communities, there are so many programmes that have been introduced toaddress WASH challenges. The paper aimed at assessing the various determinants influencing the adoption of WASH programmes in flood prone Tsholotsho District. A quantitative approach was used to collect data from Household heads in wards 5, 6, 7, and 8 using Questionnaires. A total of 218 Questionnaires were administered in all four wards. A Probit regression analysis and Zero-inflated ordered logit regression analysis were then done using Statistical Package for Social Sciences (SPSS). This study revealed that the coefficient of access to treated water, gender, source of water, level of education, and marital status is positive and statistically significant with the adoption of WASH programmes by the household head in the study area. These factors were also revealed to influence the level of adoption of WASH programmes.Contribution: There is a positive and significant relationship between access to safe water, source of water, level of education, gender, age and marital status and WASH programmes. Therefore, there is a need to consider the determinants of the adoption of WASH programmes to effectively build the resilience of communities.

Pea Pod–Derived Biochar–Zeolitic Imidazolate Framework Composite for the Photocatalytic Degradation of Two Organic Dyes Crystal Violet and Victoria Blue

ABSTRACTThe rapid increase of water pollution globally is a vital environmental concern that requires the immediate attention of researchers to find new innovative ways to remove unwanted environmental pollutants from our water sources. With the advances in the field of sustainable engineering, there is a high demand for the effective utilization of biomass resources for the removal of aqueous environmental contaminants. Biochar is carbon carbon‐enriched substance obtained by biomass pyrolysis; it is inexpensive and has received wide attention in the field of wastewater treatment. Herein, we describe the synthesis of pea pod (PO) biochar‐reinforced zeolitic imidazolate framework (ZIF‐8) nanocomposite (PO@ZIF‐8) through the in situ precipitation of ZIF‐8 onto the biochar surface. The crystal growth, morphology, chemical composition, and optical characteristics of fabricated PO@ZIF‐8 nanocomposite were scrutinized through PXRD, SEM, TEM, UV‐DRS, PL, and XPS analysis. The dodecahedral‐shaped PO@ZIF‐8 particles have an average size between 140 and 160 nm. The biochar‐reinforced ZIF‐8 nanocomposite showed significantly higher photocatalytic activity than the pure ZIF‐8 for the degradation of two commonly found organic dyes crystal violet (CV) and Victoria Blue (VB) in the presence of direct sunlight irradiation. The PO@ZIF‐8 nanocomposite showed the highest degradation efficiency of ~87% and ~80% within 50 min of irradiation time at a catalyst dosage of 20 mg for 30 ppm CV and VB dye solutions at pH 8. First‐order kinetics were obeyed during the photodegradation with 0.041 and 0.030 min−1 as the constant of degradation for the removal of CV and VB. The radical scavenger experiment and the photoluminescence analysis confirm the active participation of ·OH radical in the degradation of both dyes. LC–MS and TOC analysis was also performed to determine the degradation products and for evaluation of the degradation progress. Moreover, the synthesized PO@ZIF‐8 composite also exhibit good stability till the fourth cycle with high degradation efficiency thus making it a good choice of catalyst in the field of environmental decontamination.

Influence of decades-long irrigation with secondary treated wastewater on soil microbial diversity, resistome dynamics, and antibiotrophy development

In arid and semi-arid regions, the use of treated wastewater (TWW) for irrigation is gaining ground to alleviate pressure on natural water sources. Despite said treatment, the existing methods fail to eliminate potentially dangerous contaminants. As such, this study assessed the impact of long-term TWW irrigation (5 and 25 years) on soil physicochemical properties and bacterial resistance to heavy metals (Pb, Cu, Cd) and antibiotics (tetracycline and amoxicillin). The results revealed heightened salinity and conductivity and reduced pH in irrigated soils. TWW induces harmful effects by reducing microbial density and size, leading to the disappearance of sensitive populations. Conversely, resilient populations, which mainly utilize antibiotics as a carbon source, have adapted. Metagenomic 16S amplicon sequencing analysis demonstrated a shift, notably reducing Actinobacteria, Bacteroidetes, and Firmicutes while increasing Acidobacteriota and Patescibacteria in treated soils. Operational Taxonomic Units affiliated with either Halomonadacea, or Saccharimonadacea and Vicinamibacteracea, were defined as indicators of the absence or presence of TWW contamination, respectively. We conclude that TWW irrigation significantly increases bacterial resistance to heavy metals, whereas the impact of antibiotics is nuanced, with antibiotrophy leveraging lower concentrations in treated soils.

Irrigation Water Salinity Affects Solute Transport and Its Potential Factors Influencing Salt Distribution in Unsaturated Homogenous Red Soil

As a promising alternative water source to alleviate irrigation water scarcity in red soil regions in southern China, low-quality water could enhance regional water resource utilization and promote sustainable agriculture. However, its soluble salt and ions could affect soil solute distribution and transport, potentially hindering crop growth. Undoubtedly, it is necessary to understand the mechanism of solute transport in red soil under low-quality water irrigation with different water salinity levels. Therefore, a one-dimensional vertical water infiltration experiment and a solute breakthrough experiment were conducted to evaluate the solute transport (soluble salt, Na+, and Cl−) in unsaturated and saturated homogenous red soil at different salinity levels [1 (S1), 2 (S2), 3 (S3), 5 (S5), and 10 (S10) g/L] when irrigated with simulated low-quality water using analytical-grade NaCl. Moreover, the potential factors affecting salt distribution in unsaturated red soil were determined. The findings indicate positive linear relationships between accumulations of three solutes and irrigation water salinity. Generally, the depth of maximum solute concentration increased with the increase in irrigation water salinity. Soluble salt, Na+, and Cl− exhibited early breakthrough and trailing in red soil, but higher irrigation water salinity could reduce PV and retardation. A mobile and immobile water model (MIM) showed that convection was dominant in solute transport in red soil under low-quality water irrigation. D decreased as a power function with increasing irrigation water salinity, while v and R decreased linearly. Furthermore, the red soil can adsorb Cl− resulting from its special charge characteristics under low-quality water irrigation, which may be the main source of salt adsorption. Additionally, v > soil pH > βsalt primarily influenced salt distribution in the 0–40 cm soil profile. This study can provide insights into solute transport in red soil under low-quality water irrigation, facilitating soil fertility and structure, as well as low-quality water irrigation strategy optimization.

Biological two-stage treatment technology for mitigating mining-related heavy metal pollution in Georgian rivers

ObjectivesThe study aimed to investigate heavy metal contamination (copper, arsenic, manganese) in Georgian rivers affected by mining and develop a two-stage water purification technology using Spirulina (Arthrospira platensis) and trehalose lipid (TRL). This technology offers a sustainable and efficient solution to mitigate environmental and health hazards from mining-related pollution, improving river ecosystems and public health.Data DescriptionThis study examines the current state of the Kvirila, Lukhuni, Kazretula, and Mashavera rivers in terms of heavy metal pollution. Data were collected from field application of a two-stage purification process. Initial assessments showed heavy metal concentrations exceeding local regulatory limits (საქართველოს საკანონმდებლო მაცნე. გარემოსდაცვითი ტექნიკური რეგლამენტების დამტკიცების თაობაზე. Environmental Technical Regulations Approval. www.matsne.gov.ge/en/document/view/2196792?publication=0&scroll=0. Accessed 22 Aug 2024.). The purification process involved a 72-h incubation in a primary tank, followed by membrane filtration and the addition of biomass with trehalose lipid (TRL) in a secondary tank. Post-treatment data revealed significant reductions in manganese and copper concentrations, bringing them below permissible thresholds. These data highlight the effectiveness of the two-stage purification technology in removing heavy metal contaminants from water sources impacted by industrial pollution. The findings demonstrate the potential of this technology to improve sustainable water management practices and provide scalable solutions for communities facing similar water quality challenges.

Prevalence of Resistance Genes Among Multidrug-Resistant Gram-Negative Bacteria Isolated from Waters of Rivers Swat and Kabul, Pakistan.

The waters of rivers Swat and Kabul are the main water source for domestic and irrigation purposes in the northwestern part of Pakistan. However, this water has been contaminated due to human activities. This study aimed to analyze the water of these rivers for occurrence of antibiotic resistance genes among Gram-negative bacteria. Samples were collected from 10 different locations of these rivers. The samples were processed for the isolation of Gram-negative bacteria. Isolated bacteria were checked against 12 different antibiotics for susceptibility. The isolates were also analyzed for the presence of seven antibiotic resistance genes. A total of 50 bacterial isolates were recovered that belonged to five different bacterial genera, that is, Escherichia coli, Klebsiella oxytoca, Pseudomonas aeruginosa, Raoultella terrigena (Klebsiella terrigena), and Pseudomonas fluorescens. Antibiotic resistance pattern was cefixime 72%, cephalothin 72%, ampicillin 68%, nalidixic acid 68%, kanamycin 54%, streptomycin 42%, sulfamethoxazole-trimethoprim 28%, chloramphenicol 28%, meropenem 8%, gentamicin 8%, amikacin 2%, and tobramycin 2%. The prevalence of bla-TEM gene was 72% (n = 36), aadA gene 34% (n = 17), sul gene 32% (n = 16), bla-CTXM gene 12% (n = 6), int gene 66% (n = 33), and int1 gene 6% (n = 3). This information highlights the need for controlling and monitoring the release of domestic wastes to rivers.

Montane grassland recovery: lessons from 25 years of the Working for Water program on the northern Drakensberg Escarpment, South Africa

Despite their strategic importance as biodiversity hotspots and water sources, montane ecosystems are among the most neglected conservation areas. In particular, the monitoring and management of invasive alien plants in this critical biome is limited. This study presents an analysis of long‐term invasive alien plant removal within montane grassland ecosystems, drawing on insights from 25 years of the Working for Water (WfW) program on the northern Drakensberg Escarpment. We assessed the response of vegetation communities to invasive alien plant removal in this region. Using data from the WfW program on clearance activities, expenditure, and re‐visit times, we compared plant species richness, diversity, and composition in sites managed under the WfW program to adjacent patches of pristine vegetation. Results showed minimal variation in species richness between cleared sites and unmanaged sites. However, these vegetation communities remain distinctly dissimilar across sites. These findings suggest the need for active restoration of montane vegetation communities if they are to return to their natural condition and further highlight the need to conserve the remaining habitats for critically endangered species, even in their depauperate state.

Track of methylparaben in the bulk phase and on the extracellular matrix of dual-species biofilms: Biodegradation and bioaccumulation

Methylparaben (MP) is a preservative considered an environmental contaminant of emerging concern due to its persistence in water sources, including drinking water (DW). This study assesses the interaction between MP and dual-species biofilms of Acinetobacter calcoaceticus and Stenotrophomonas maltophilia. These biofilms were grown under realism-based conditions in a multiple-cylinder biofilm reactor on polypropylene (PPL) surfaces, for 7 days, and then exposed to MP at 0.5 mg/L for three consecutive days. S. maltophilia predominantly succeeds within these biofilms compared to A. calcoaceticus. Exposure to MP resulted in a 4-fold increase in the number of culturable cells and a 1.4-fold rise in polysaccharide content, suggesting that bacterial cells may utilize MP as a carbon source to enhance biofilm fitness. MP was found to adsorb to PPL with biofilms following a pseudo-second-order kinetic model. Circa 37 % of MP adsorbed to PPL after 3 days of exposure. Besides that, MP was biodegraded by biofilms following an apparent first-order kinetic model. Part (25 %) of the MP was biodegraded whereas only 0.02 % bioaccumulated on the biofilm matrix. Biodegradation was related to esterase and lipase activity. The results provide new insights into the interaction between MP with biofilms and materials used in DW industries.

Early Hominin Paleoenvironments and Habitat Heterogeneity

Environmental changes are often cited as the main driver of hominin evolutionary events, including major adaptive events such as bipedalism. Thus, researchers are particularly interested in the paleoenvironment of early hominins. The previous prevailing idea that hominins originated in expanding savannas is contradicted by the association of the earliest hominins with more closed and mesic (i.e., moderately wet) habitats. The Pliocene homi-nins that followed lived in a variety of habitats characterized by high levels of heterogeneity and permanent sources of water. This article reviews what we know of Mio-Pliocene hominin paleoenvironments, discusses the nature of the observed habitat heterogeneity associated with early hominins and implications for hominin paleoecology, and considers the challenges we face in showing a causative relationship between environmental change and major evolutionary events.

Evaluation of some anions in groundwater in Riyadh, Saudi Arabia, and human health risk assessment of nitrate and fluoride.

Groundwater is a vital source of water for human and agricultural use in many parts of the world. The purpose of this research was to establish the quality of groundwater in Riyadh, Saudi Arabia, as well as the human health concerns associated with it. We collected and examined groundwater samples for pH, EC, TDS, CaCO3, fluoride (F-), chloride (Cl-), sulfate (SO42-), and nitrate (NO3-). The ion chromatography conductometric detection method was constructed to determine fluoride, chloride, sulfate, and nitrate in groundwater. The suggested method worked well for the anions that were being studied; it had a high coefficient of determination (r2 > 0.998) and average recoveries for all analytes that were between 97.5% and 99.0%, with a range of error of 0.77 to 2.37%. Fluoride concentrations were detected between 0.001 and 0.14mg/L, which are within the acceptable limit by several organizations. Chloride was measured in the range of 17.1 to 966.5mg/L, with some samples above the limits. The influence on sulfate ranged from 2.0 to 1136.0mg/L, with several samples exceeding the limits. In contrast, with nitrate levels ranging from 1.4 to 5.0mg/L, the majority of the samples fall within the acceptable range. The overall intake of fluoride, chloride, sulfate, and nitrate is 0.00605, 138.911, 65.515, and 1.19, respectively, which is lower than the recommended daily consumption except for chloride. The groundwater sample contains fluoride and nitrate with HQ values less than one: 0.000064-0.0641 and 0.033654-0.120192. Humans in Riyadh, Saudi Arabia, do not pose a health risk when digesting or absorbing groundwater fluoride or nitrate.

Flower-Shaped MnFe2O4@MoS2 Nanocomposite Activated H2O2 for Efficient Degradation of Tetracycline: Performance Evaluation, Mechanism and Degradation Pathway

The limited utilization of H2O2 restricts the practical application of heterogeneous Fenton oxidation technology. In this study, the flower-shaped MnFe2O4@MoS2 nanocomposite was prepared by two-step hydrothermal treatment, constructing MnFe2O4@MoS2/H2O2 system for the degradation of tetracycline (TC). Under optimized conditions, MnFe2O4@MoS2/H2O2 system fully degraded 20 mg·L−1 of TC within 60 min, and the corresponding utilization of H2O2 was also as high as 95.7%. Meanwhile, this system not only exhibited excellent cycling stability for the degradation of TC but also had good anti-interference ability against actual water sources, inorganic cations and anions and natural organic compounds. The efficient activation of H2O2 in MnFe2O4@MoS2/H2O2 system mainly relied on the redox cycling of Fe(II)/Fe(III) and Mn(II)/Mn(III) mediated by MoS2; meanwhile, the oxygen vacancies caused by redox cycling also accelerated activation of H2O2, resulting in the production of a large number of active species (·OH, ·O2− and 1O2) for rapid degradation of pollutants. The vulnerable atomic sites of TC were confirmed through theoretical calculation, and four degradation pathways of TC in MnFe2O4@MoS2/H2O2 system were proposed. Finally, the toxicity analysis confirmed that the toxicity of degradation intermediates was developing towards low toxicity. This study provided new insights into the wide application of heterogeneous Fenton systems in wastewater treatment.

Sustainable Acid Mine Drainage Water Reclamation Using Silica-pectin Multichannel Tubular Membrane: A Comparison of Ultrafiltration Vs Pervaporation

The practice of coal mining has been demonstrated to exert a detrimental impact on the surrounding environment, particularly through the formation of acid mine drainage (AMD) ponds, which have the potential to pollute water sources. The reclamation of AMD is necessary to treat wastewater to ensure its safety for discharge into the environment and subsequent use as clean water. This study aims to treat AMD by comparing ultrafiltration (UF) and pervaporation (PV) processes utilizing silica-pectin multichannel membranes. The membranes were fabricated by coating silica-pectin sol on an inner surface of multichannel tubular support. The UF process was conducted under various pressures (1-3 bar), while the PV process was tested at various feed temperatures. Both permeate were collected and analyzed using several parameters (pH, Mn, and conductivity). The results showed that the UF process is more effective in collecting permeate flux over 136.6 L.h-1.m-2 at 3 bar pressure. Meanwhile, PV performs high permeate quality with Mn and conductivity rejection of 99.9 and 96.5%, respectively. Both UF and PV processes exhibit slightly increasing permeate pH with a range of 4.5-5.6. It concluded that multichannel silica-pectin membranes successfully reclamation AMD to enhance water quality. In addition, the UF process is more affordable for recycling AMD with high permeate flux, pretty good Mn, and conductivity rejection of over 95%.

Extended-spectrum beta-laktamase (ESBL) enzyme producing bacteria isolated from rectal swabs of around animals in dairy farms

This study aims to identify bacterial contamination of Klebsiella pneumoniae and Escherichia coli producing Extended Spectrum Beta Lactamase (ESBL) isolated from rectal swabs of local animals on a dairy farm in Deyeng Village, Kediri, East Java. Interviews and observations were conducted with farmers to obtain the required risk factor data (cleanliness of drinking and eating places, drinking water sources, and administration of antibiotics to livestock). The number of samples tested in this study was 34 samples, including 12 chicken samples, 8 goat samples, 5 duck samples, 4 rabbit samples, 3 cat samples and 2 goose samples. Samples were isolated on MCA media + cefotaxime 1 mg/l and isolated again on MCA media without the addition of antibiotics to multiply pure bacterial colonies. The tests carried out to determine the presence of ESBL-producing bacteria are biochemical tests, namely the IMViC test (Indole, Methyl red, Voges-Proskauer, Citrate Utilization), TSIA (Triple Sugar Iron Agar) test, gram staining, and the Double Disk Standard Method test using β-lactam disc antibiotics, namely cefotaxime 30μg, ceftazidime 30μg, and amoxycilline-clavulanate acid 30μg. The results of this research were that 6 samples or 17.6% of ESBL-producing bacteria were identified from poultry groups (chickens, ducks and geese) from dairy farms in Deyeng Village, Kediri Regency, East Java.

A Systematic Review on Fluoride Contamination in Water Resources of Iran from 2016 to 2023: Spatial Distribution and Probabilistic Risk Assessment (Monte Carlo Simulation).

Because of significant variations and existence of high fluoride (F-) in some waters, Iran has been considered for various fluoride studies in recent decades. Nevertheless, there is a no updated review on fluoride levels especially including F- risk assessment. Thus, this systematic review is mainly aimed to evaluate the spatial distribution of F- content in water sources of Iran using geographic information system (GIS) and conduct the health risk assessment. Besides, the Monte-Carlo Simulation technique with 10,000 iterations was applied for determination of the non-carcinogenic effects of F- in different exposed groups (infant, children, teenagers, and adults). The results indicated that the maximum and minimum concentrations of F- content were related to Jazmourian (Roudbar plain) (4.8mg/L) and Sahneh (0.1mg/L) provinces, respectively, and F- content of more than ≅ 19% of the samples exceeds the Iranian standard value (1.5mg/L). The results showed that the HQ of F- in all groups were higher than 1 with the order of children > infants > teenager > adults in which children were the vulnerable group to F- consumption in study area. Therefore, it is necessary to monitor and continuously measure water supplies for fluoride content and control measures, including removal steps, be taken for human risk reduction.

Influence of Longitudinal Fragmentation on Length–Weight Relationships of Fishes in the Someșul Cald River, Romania

Romania has a rich hydrographic network, which permitted the construction of over 80 large dams on its water courses, estimating a number between 545 and 674 hydropower plants that were either built or were in a different construction stage on the rivers of Romania in 2021. These hydropower plants were often built outside specific legislation regarding ecological impacts, especially before 1990. Longitudinal fragmentation of rivers causes severe ecological impacts on biodiversity, food chains, and nutrient cycles. Someșul Cald River is the main tributary of Someșul Mic River, the most important water source for the northwestern region of Transylvania. On its course, several dams and reservoirs were built from 1968 to 1980 for electricity production and population freshwater supply. The present study aimed to analyze the length–weight relationships (LWRs) and condition factors occurring in the longitudinally fragmented Someșul Cald River. The LWRs, relative condition factor Kn, and Fulton condition factor K were determined based on total length and wet body weight. Comparisons of LWRs, Kn, and K across river sections constrained by dams showed that some fish species exhibited similar growth patterns and physiological conditions, while others differed significantly. Freshwater fish physiology is altered by longitudinal fragmentation, both natural and artificial. Barriers such as dams influence the energy gradient, limiting feed availability and, consequently, the life history of fish species. Long-term management plans regarding conservation should take into consideration existing fish species population dynamics, along with their physiological and somatic status.

An Assessment of Water Quality and Pollution Sources in a Source Region of Northwest China

China prioritizes ensuring drinking water safety, particularly in the water-scarce northwest region. This study, utilizing water quality data from 52 village and town water sources since August 2022, assesses water quality, with a specific focus on key indicators related to organic pollution sources. This study provides a scientific foundation for enhancing water quality in these sources. Employing category factor analysis for classification and grading, principal component analysis for qualitative analysis of key evaluation indicators, and the absolute principal component linear regression equation for quantitative calculation of pollution sources, this study reveals that all 52 water sources meet quality standards. Principal component analysis categorizes pollution sources as diverse types of organic compounds in surface water. Source analysis calculations highlight decay-type organic substances as major contributors to increased water color and permanganate index, with pollution contribution rates of 54.78% and 31.31%, respectively. Fecal-type organic substances dominate the increase in dissolved total solids and total coliforms, with pollution contribution rates of 56.65% and 40.16%, respectively. Additionally, high-molecular-weight organic substances exhibit lower concentrations in the water. This article presents a systematic water quality assessment methodology, which is used for the first time to qualitatively assess the types of water sources and to quantitatively trace specific sources of organic pollution in source water in northwest China. This systematic study’s results, involving initial assessment followed by traceability, recommend the adoption of a simple contact filtration and disinfection process to enhance water quality in the region.

Mitigation of Fluoride Contamination in Drinking Water Supply Sources by Adsorption Using Bone Char: Effects of Mineral and Organic Matrix

This study focused on fluoride (F−) contamination of water sources in Bahimi village, Cameroon. After the first investigation, results revealed that all water samples collected had elevated concentrations of fluoride ions (2.3 ± 0.1) mg/L to (4.5 ± 0.2) mg/L above the WHO guidelines (less than 1.5 mg/L). To mitigate the F− levels, the use of bone char (BC) as an adsorbent material was proposed and its performance was tested. BC was prepared from bovine bones at different calcination temperatures (350 °C, 450 °C, 550 °C and 650 °C) and residence times (1 h and 2 h). The prepared materials were characterized in detail by SEM/EDS, BET, FTIR, and XRD. The BET findings indicated that the surface area of BC samples decreased with increasing calcination temperature and residence time. At a lower heating temperature and holding time (350 °C, 1 h), the prepared BC exhibited a higher specific surface area (112.3 ± 0.3) m2/g and adsorption capacity for F− in the sampled water. Also, the batch adsorption experiments showed that the optimized adsorbent dose of 8 g/L facilitates the reduction in the F− level of the sampled water below the acceptable limit level (1.5 mg/L) within 5 min of treatment. The presence of Ca2+ and Mg2+ in natural water has a positive effect on the removal of F− in BC resulting in a high adsorption performance range of (72.5 ± 1.4)% to (80.3 ± 0.6)%. It was found that the adsorption of Ca2+ on the BC surface occurs via cation exchange with Na+. However, an increase in dissolved organic carbon (DOC) in the treated water limited the application of BC. Overall, the study presented a cost-effective adsorbent for the removal of this recalcitrant ion in the water source.

The Israeli Water Policy and Its Challenges During Times of Emergency

In a time of growing climate crisis, and despite the global warming trend, Israeli citizens routinely enjoy a regular constant supply of clean fresh water thanks to local desalination plants. Establishment of the desalination plants has become a model of water management for many countries in an era of growing climate crisis. At the same time, Israel’s water sector is faced with challenges and threats related to earthquakes, various states of warfare, and security confrontations. In such times of emergency, Israel’s water sector is particularly vulnerable to disruptions of the water infrastructure and its adequate operation by both contamination of the water sources and damage to the desalination plants. This study examines the challenges of the Israeli water sector that require it to contend with these emergency situations in an era of reliance on desalination plants. The research findings lead to the conclusion that public policy on managing the water sector, manifested in the development and establishment of water desalination plants, has resolved Israel’s water crisis, put an end to its dependency on the amount of precipitation and on natural water sources, and allowed for an increase in water production to match the rise in consumption. Nonetheless, as successful as this public policy may be, it does not consider the possibility of extreme scenarios and does not develop the entire range of steps necessary to confront them, and thus it undermines the ability of the Israeli water sector to provide its citizens with water in times of emergency.

Response time of fast flowing hydrologic pathways controls sediment hysteresis in a low-gradient watershed, as evidenced from tracer results and machine learning models

Hydrologic controls on the timing of sediment transport and sediment hysteresis patterns remain an open area of investigation in hydrology, especially for low-gradient watersheds with substantial instream sediment deposition. Sediment hysteresis, which describes the mismatch between hydrograph peak and sedigraph peak, aids with elucidation of the mechanisms of sediment transport in watersheds. Most frequently, the controls of hysteresis are attributed to the proximity of sediment sources to monitoring locations in a watershed. However, this assumption, while widely applied, is infrequently verified. We investigated the controls of sediment hysteresis in a low gradient system located in the Bluegrass Region of central Kentucky, USA. Turbidity and conductivity sensors installed at the basin outlet provided data to quantify sediment hysteresis and separate hydrologic flow pathways (i.e., by describing the source of water delivered to the watershed’s outlet) using a tracer-based approach. Predictive hydrologic parameters, including hydrologic pathways, event magnitude, and antecedent conditions, were estimated and grouped based on hydrologic similitude. Thereafter, we identified parameters required to predict sediment hysteresis using a tailored ensemble feature selection approach coupled with three machine learning algorithms—Random Forest, K-Nearest Neighbors, and Gradient Boosted Trees. Results from the analysis of 68 storm events occurring over a two-year period showed that clockwise events accounted for 85 % of the total sediment yield despite comprising only 53 % of the events. The hysteresis index (HI) can be predicted (r = 0.8, RMSE = 0.12) using three, out of the thirty-nine hydrologic parameters considered. The most important predictors of HI reflect the volume of event rainfall and the relative proportions of new water (i.e., water derived from precipitation during the storm event) and old water (i.e., water previously stored in the watershed) comprising the hydrograph. Further analyses reveal that new water timing—which changes with the rainfall volume—and sediment timing are closely linked, suggesting that variations in the hysteresis patterns are controlled by changes in the response time of fast flowing water pathways. This implies that hydrologic pathways, as opposed to sediment proximity to the watershed outlet, control sediment hysteresis in this watershed. These results have important implications for better understanding the mechanisms controlling sediment transport at the watershed scale.