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Studying groundwater renewal time is a valuable tool to deepen the comprehension of sustainable groundwater resources specific to arid regions. Tritium is a radioactive isotope of hydrogen often used as an environmental tracer to study groundwater renewal time. The present work reports groundwater renewal times by the environmental tracer tritium to understand sustainable water resources in arid regions. First, groundwater samples were collected from wells in northeastern arid regions of Saudi Arabia. Then, an electrolysis process was employed to significantly increase the tritium level from twenty-five to thirty times the original concentration. Subsequently, the enriched water was analyzed using a liquid scintillation counter under optimized measurement conditions to determine the tritium concentration precisely. Two internationally recognized tritium laboratories conducted independent assessments to validate the estimated tritium levels. The verified tritium concentration was then used to estimate the groundwater renewal time using the Morgenstern and Pimenta curves. The results suggest that most of the monitored wells in the surveyed areas are more than a century old. Conversely, a few monitoring wells exhibit renewal times of several hundred years and may be considered nonrenewable water sources. These studies help to understand the geochemical characteristics of arid regions to ensure the sustainable management and protection of groundwater resources. [ABSTRACT FROM AUTHOR]

Groundwater is extensively utilized for drinking, irrigation, and industrial activities globally. However, its quality is deteriorating significantly, particularly in coastal regions where saline water infiltration is a major issue. This study investigates the coastal aquifer of Udupi district in Karnataka, India, covering approximately 80 km2, through hydro-geochemical analysis of groundwater samples from 57 spatially distributed locations, pre- and post-monsoon. The major anion and cation parameters analyzed include Cl−, HCO₃−, SO42−, NO₃−, Na+, Ca2+, K+, and Mg2+. The analysis revealed a pH range of 2.9 to 8.3, indicating acidic to slightly alkaline conditions, and total dissolved solids (TDS) concentrations ranging from 110 to 6683 mg/L, predominantly showing saline characteristics toward the coastline. Hydrogeochemical assessment, including Chadha's plot, identified Na-Cl type water in most samples, indicating the influence of salinity. Approximately 21% of pre-monsoon and 67% of post-monsoon samples were deemed unsuitable for irrigation based on permeability index values, with 2 to 3% exhibiting high salinity hazards. The variation in correlation coefficients between pre-monsoon and post-monsoon periods suggests that saline water intrusion, freshwater recharge, and geochemical interactions influence the coastal groundwater system. The molar ratio of Na⁺ to Cl− suggested a reverse cation exchange process, highlighting the complex interactions between saline and freshwater. Overall, 79% of pre-monsoon and 80% of post-monsoon samples were deemed suitable for irrigation, while 21% and 20% were classified as completely unsuitable, respectively. [ABSTRACT FROM AUTHOR]

Leakage at the bottom of an underground structure can compel ground water to form a converging flow, under which soil erosion may occur, thereby threatening the safety of the structure. Previous studies have shown that converging flow may induce backward erosion, and unravelling the mechanism behind this type of erosion was pivotal to mitigating disasters in practical engineering. Existing studies on this topic have been limited to monolayer erodible medium, while the mechanism behind the backward erosion of a multilayer erodible medium under converging flow remains unclear. In this study, both experimental tests and numerical simulations based on the validated computational fluid dynamics and the discrete element coupling method (CFD–DEM) were conducted to investigate the backward erosion of a multilayer sample under converging flow. The results demonstrated that the multilayer sample was eroded layer-by-layer, whereby residual layers could be observed at the bottom of the sample. The eroded regions in different layers were similar in shape but smaller in size for lower layers. In addition, particle exchange occurred among different layers during the erosion process. In general, lower-layer particles could directly ascend to upper layers in the eroded regions, whereas upper-layer particles mainly settled on the periphery of the eroded regions. [ABSTRACT FROM AUTHOR]

The conjunctive use of surface water and groundwater is practiced worldwide as a measure to address water supply uncertainty. This paper focuses on a scenario in which an aquifer is open to multiple users and examines the impact of such an open-access environment on the stabilization function of conjunctive management. We construct a non-cooperative stochastic dynamic game model where multiple users utilize groundwater intake from a common aquifer as a complement to fluctuating surface water. We also propose a simpler baseline applicable to dynamic environments to compute the benefits of the stabilization function when users are unable to adjust groundwater intake to surface water uncertainties. We then apply the model to the real-world case of the water supply environment of the Cao'e River in China. Simulation results show that open access leads to diminishing stabilization values as higher pumping costs due to declining stocks lead to a weakening of users' incentive to utilize groundwater flexibly. Furthermore, the stabilization function itself is destabilized as the number of users increases. This is because greater groundwater intake and a decline in stocks amplify variations in pumping costs caused by different patterns of surface-water fluctuation. [ABSTRACT FROM AUTHOR]

To analyze groundwater contamination with uranium, groundwater samples were collected from the major industrial area of Jalandhar, Punjab, India (as the industrial effluent is found to contain a large number of heavy metals) and analyzed using ICPMS (Inductively Coupled Plasma Mass Spectrometer) for uranium-238. Uranium-238 concentrations in groundwater ranged from 4.96 µg/L and 38.52 µg/L, with an average of 17.0 µg/L. All the values of uranium concentration and uranium activity concentration in the samples were found within the permissible range by the World Health Organization (WHO). The hazard quotient for all the samples is found to be below one, indicating very low or no risk to the population. [ABSTRACT FROM AUTHOR]

This study focuses on the simulation of the natural attenuation of groundwater contaminated by acid-leached uranium at a decommissioned uranium mining site. Although natural attenuation by mixing and dilution, pH buffering, adsorption, and reduction has been well described, little research on the simulation of the natural attenuation of groundwater U6+ and sulfuric acid in sandstone aquifers after mining has been performed. Using PHREEQC Version 3 software and the minteq.v4.dat database, in this paper, the thermodynamic adsorption equilibrium constants and adsorption site parameters were modified based on the experimental results of the mineral composition, chemical reactions, U6+ adsorption, and SO42− reduction reactions. This study provides a basis for establishing detailed environmental background data files, conducting laboratory experiments, and predicting the natural attenuation capability of sandstone aquifers at uranium mining sites and their surrounding areas. [ABSTRACT FROM AUTHOR]

A study to assess the uranium exposure due to ingestion of groundwater in Fatehabad district of Haryana has been carried out. Total 49 drinking water samples were collected from different locations of the district. Two groundwater tests taken near the power plant site exceeded the World Health Organization's recommended threshold limit of 30 μg L−1 (WHO in Guidelines for drinking-water quality, 4th edn, World Health Organization, Geneva, pp 1–564., 2011). The average radiological and chemical toxicity risks are below recommended limit. Because of their high organ sensitivity, babies are found to have the highest annual effective dose among the several life stage groups for which it was estimated. Positive correlations were found between the content of uranium in groundwater samples and EC, TDS, salinity, redox potential, and dissolved oxygen whereas a negative connection with pH has been noted. Organ-specific dosage resulting from uranium ingestion has been investigated using the hair compartment model. [ABSTRACT FROM AUTHOR]

The current study investigates removing tetracycline from water using batch, column, and tank experiments with statistical modelling using ANN for continuous tests. An artificial neural network (ANN) using the Levenberg-Marquardt back-propagation (LMA) training algorithm is constructed to compare the effectiveness of Tetracycline removal from aqueous solution using the sorption technique with prepared adsorbent. Several characterization analyses XRD, FT-IR, and SEM are employed for prepared Brownmillerite (Ca2Fe2O5)–Na alginate beads. The operating conditions of batch tests involved, contact time (0.1–3 h), initial of tetracycline (Co) of (100–250 mg/L), pH (3–12), agitation speed (50–250) rpm and dosage of adsorbent (0.2–1.2 g/50 mL). The outcomes of experiments have demonstrated that the optimum conditions for the batch test to achieve the maximum adsorbent capacity (qmax =7.845 mg/g) are achieved at pH 7, contact time 1.5 h, adsorbent dose 1.2 g/50 mL, agitation speed of 200 rpm, and initial concentration of TC 100 mg/L. Minimum mean square error (MSE) values of 7.09E-04 for 30 hidden neurons and 0.0029 for 59 hidden neurons in the 1D and 2D systems are accomplished, respectively. The artificial neural network model has exhibited excellent performance with correlation coefficients exceeding 0.980 for the operating variables, demonstrating its accuracy and effectiveness in predicting the experimental outcomes. According to sensitivity analysis, the influential parameter in the column test (1D) is the flow rate (mL/min), with a relative importance of 32.769%. However, in the tank test (2D), time (day) is signified as an influential parameter with a relative importance of 31.207%. [ABSTRACT FROM AUTHOR]

The present study investigates the reactivation of a paleolandslide due to the expansion of a community in an area covered by plastic Pliocene marls in the southwestern part of Cyprus. The landslide, which takes place in an area with gently sloping ground and relatively shallow water table, affects more than 100 residential buildings. In the context of the study, building damages and ground surface ruptures were mapped through field work campaigns. Remote sensing data from InSAR (Interferometric Synthetic Aperture Radar) analysis were evaluated in conjunction with available geological, geotechnical and hydrogeological data. Subsequently, the landslide was backanalyzed using the finite element method to examine possible failure mechanism scenarios and shed light on the influence of potential triggering factors. The results indicate that the paleolandslide has been almost fully reactivated, with the main cause of the reactivation being the rising of the phreatic water table due to long-term discharges of wastewater through the absorption pits of the residential developments. The water table rise was further amplified by rainwater infiltration during rainy years. According to the backanalysis results, the slip surface follows the bedding planes of weak marl horizons with residual friction angle of the order of 10°. [ABSTRACT FROM AUTHOR]

Boundary conditions play a crucial role in groundwater contamination source identification (GCSI), but they may be complex and reliable estimates are difficult to obtain in advance in actual situations. If the estimated values deviate significantly from the actual situation, the GCSI results will be inaccurate. However, very few studies have attempted to identify the boundary conditions in GCSI, and even when they are identified, they are often considered too simple. The boundary mode (Bmode) is assumed to be known, but in reality, it is often unknown and is more complex than initially assumed. Previous practices based on this assumption may not accurately reflect actual situations. Therefore, this study focused on the concentration boundaries, and the boundary conditions were also considered unknown variables, along with contamination source information and model parameters. To alleviate the problem of identifying the boundary conditions under an unknown Bmode, we proposed for the first time to treat the Bmode as an unknown variable. Thus, the source information, model parameters, Bmode, and corresponding parameters in the boundary concentration (BC) function were identified simultaneously. The Differential Evolution Adaptive Metropolis with a Snooker Update and Sampling from a Past Archive (DREAM(ZS)) algorithm and a Kriging surrogate model were used as the primary means of solution. We designed four different synthetic cases to test the effectiveness of the above ideas. When identifying the Bmode, the obtained BC mostly fitted well with the true BC. It was therefore considered feasible for identifying the Bmode. The performance of the DREAM(ZS) algorithm was found to be superior to the traditional DREAM algorithm and was more efficient. [ABSTRACT FROM AUTHOR]

Water pollution is currently a critical global issue. Various research groups have developed active adsorbent materials. This study aims to enhance the adsorption of water pollutants, particularly fluoride, by modifying the electronic structure of red soil through in-situ chemical oxidative polymerization techniques. The synthesized materials were characterized using techniques including powder XRD, FT-IR, UV spectroscopy, and Conductometer, followed by testing their adsorption performance. The XRD analysis revealed that while the crystal structures of embedded red soil remained amorphous, polyaniline (PANI) and PANI/red soil (RS) nanoparticles became polycrystalline. The maximum adsorption capacity (qmax) of fluoride ions by PANI/RS was determined to be 9.35 mg/g. Optimization experiments showed that PANI/RS exhibited maximum adsorption performance for fluoride ions under specific conditions: pH 4.0, a contact time of 50 min, temperature of 35 °C, and an initial concentration of 15 mg/L with 2 mg of adsorbent, achieving a removal efficiency of 99.9%. Both Langmuir and Freundlich isotherm models demonstrated a good fit with the experimental data, with R² values of 0.94 and 0.95, respectively. This suggests that PANI/RS is an effective adsorbent material for removing fluoride ions from wastewater. Overall, PANI/RS outperformed red soil alone, demonstrating potential for practical application in water treatment processes. [ABSTRACT FROM AUTHOR]

The performance of gravity recovery and climate experiment (GRACE) and GRACE-Follow On (GRACE-FO) satellites in estimating groundwater level (GWL) changes on a local scale is a challenging issue. Then, this study aims to investigate the performance of GRACE and GRACE-FO in monitoring GWL changes on a local scale compared to observations at groundwater wells and the results of groundwater modeling. The study utilized hundreds of groundwater observational data points and 180 satellite data from 2002 to 2020 in five Iranian provinces. The data from satellites GRACE and GRACE-FO were modified by subtracting hydrological parameters outputs of the global land data assimilation system (GLDAS) from the satellites' estimations. The significant trends in GWL changes were studied by Sen's slope and Mann–Kendall, which represented a significant declining trend in GWL in all studied provinces. Applying 1–2 month time lags to the observational data improved the correlation coefficients between satellite estimations and the observations at groundwater wells. The best correlation coefficients between observational GWL changes and GRACE estimations in Fars, Khorasan Razavi, Sistan and Baluchistan, East Azerbaijan, and Golestan provinces were calculated as 0.53, 0.42, 0.4, 0.51, and 0.36. Those values for GRACE-FO were calculated as 0.95, 0.67, 0.72, 0.78, and 0.3, respectively, which proved the better performance of GRACE-FO compared to GRACE. Meanwhile, the GWL changes estimated from GRACE-FO were compared to the results of groundwater modeling, which was performed by using MODFLOW via the GMS10.4 interface in Azarshahr aquifer located at East Azarbaijan revealed a satisfactory agreement. [ABSTRACT FROM AUTHOR]

In Southwestern Ghana, groundwater is highly needed for several uses, including drinking, domestic, agricultural, and socioeconomic activities. Groundwater mineralization is usually controlled by natural processes and anthropogenic activities. The mineralization processes and other latent processes can render groundwater unsuitable for human usage. Thus, there is a need for continuous assessment of groundwater. This study aimed to assess the controls of groundwater mineralization in 105 sample stations within the Southwest of Ghana using pollution indexing, hydrochemical, multivariate statistical, and multiple linear regression (MLR) modeling. The tests for physicochemical characteristics followed standard methods. The ionic concentrations of the samples were within acceptable limits, except for nitrate in some locations. The hydrochemical analyses revealed that the water types predominated in the order of Ca–HCO3 > Mg–HCO3 > Ca–Cl > Mg–Cl > Na–HCO3 > Na–Cl. It was also indicated from selected proxies, discriminant diagrams, and multivariate statistical analyses that silicate mineral dissolution and evaporation–crystallization processes are the main controls of the mineralization in the research area. Also, the mineralization processes were noted to be facilitated by the deep and long residence time of groundwater within aquifers. The extent of contamination and suitability of the groundwater for human consumption were evaluated using percentage of pollution index (PPI) and groundwater pollution index (GPI). Their results suggest that 75% of the samples were highly–very highly polluted. The MLR models excellently predicted the relationships between the groundwater quality parameters. They also indicated that the PPI and GPI were mostly influenced by Ca2+, Cl−, HCO3−, F−, and HCO3− concentrations. [ABSTRACT FROM AUTHOR]

Assessing the groundwater quality is important for the efficient exploitation of water resources in semi-arid areas. The study area in northeast Algeria mostly depends on groundwater as its main source of water, and the quality of groundwater is becoming important due to the increasing need for freshwater. The hydrochemical characteristics and water quality of groundwater in the Tebessa-Ain Chabro were assessed using water quality indices, geochemical modeling, and multivariate statistical approaches. The study discovered that the groundwater samples could be classified into four distinct water groups using hierarchical cluster analysis in Q mode (HCA) based on their electrical conductivity. We identified three forms of water: mixed (Ca2+–Mg2+–Cl−), Na+–K+–HCO3−, and Ca2+–Cl−. According to the water quality assessment, only 38% of the samples were deemed suitable for human consumption, while 34% were categorized as poor water, 10% as extremely poor, and 17% as unsafe for drinking. The irrigation water quality index identified four classifications: low, moderate, high, and severe restriction, with corresponding percentages of 31%, 31%, 7%, and 31%. The nitrate pollution index (NPI) showed that 48% of samples fell into the moderate pollution class. Human activity, such as sewage infiltration and waste disposal in open areas, was the cause of this nitrate contamination. The saturation index values showed that groundwater was less saturated in halite and sylvite and more saturated in aragonite, calcite, dolomite, anhydrite, gypsum, and hydroxyapatite. The Tebessa region's groundwater's hydrochemical properties and water quality have been assessed using multivariate statistical techniques, geochemical modeling, and water quality indexes. The study's conclusions can provide a foundation for upcoming research evaluating the region's groundwater quality. [ABSTRACT FROM AUTHOR]

The complex relationships within desert ecosystems and their environmental conditions are reflected in patterns of plant water use. Thus, understanding the sources of water used by plants in these areas is crucial for effective resource management. In this study, we investigated the water use pattern of Haloxylon ammodendron in Semnan province, in the central plateau of Iran, using the stable isotope analysis. We employed a simple, homemade cryogenic vacuum distillation (CVD) system to directly extract water from soil samples and different plant components for subsequent analysis by mass spectrometer. The contribution of each possible water source to the plant xylem water was estimated using the IsoSource mixing model. The pattern of δ 18O values in the xylem water of H. ammodendron indicated its reliance on groundwater as a primary water resource during the wet season. Additionally, the correlation of sand particles with both δ2H and δ18O was found to be 0.32. Moreover, the δ 18O values of H. ammodendron xylem water were mainly similar to those of groundwater, suggesting the species' dominant use of groundwater. The findings of this study provide valuable insights for strategically planting H. ammodendron to mitigate impacts on groundwater resources and ensure long-term sustainability in arid and semi-arid regions. [ABSTRACT FROM AUTHOR]

Chemical and isotopic indicators were used to recognize the origin of hydrothermal groundwater, to assess the mineralization processes and groundwater quality, to identify the source of solutes and the likely mixing with cold, and elucidate the fluid geothermometry in the Jérid field of Southern Tunisia. The results show that the geothermal groundwater is neutral to slightly alkaline. They are characterized by SO4-Cl-Na-Ca water type. The dissolution of evaporates and pyrite-bearing rocks is the dominant mineralization process. The groundwater quality index indicates that the majority of samples are very hard and belong to poor to unsuitable for drinking classes. Applications and calculations of hydrogeochemical parameters, including SAR, %Na, PI, Kr, and MAR, showed that the majority of samples are unsuitable for agricultural practices. The human health risk was assessed based on hazard quotient and total hazard index through ingestion and dermal contact with iron-rich groundwater. The consumption of CI groundwaters does not present non-carcinogenic risk to adults and children. The δ18 O and δ2H signatures indicate that the geothermal groundwater was recharged by ocean precipitation during cold and wet paleoclimatic periods. The slight enrichment of oxygen-18 and deuterium contents suggests a limited mixing effect between geothermal water and cold groundwater within the same aquifer. This mixing effect is confirmed by the Na–K-Mg and the chloride-enthalpy diagrams. The K-Mg and SiO2 geothermometers provided fairly reliable reservoir temperature values, ranging between 69.6 and 99 °C. Calculated geothermal potential values, varying between 469 and 16987 kWth, which allow several applications such as domestic and agricultural heating. [ABSTRACT FROM AUTHOR]

Groundwater depletion and water scarcity are pressing issues in water-limited regions worldwide, including Pakistan, where it ranks as the third-largest user of groundwater. Lahore, Pakistan, grapples with severe groundwater depletion due to factors like population growth and increased agricultural land use. This study aims to address the lack of comprehensive groundwater availability data in Lahore's semi-arid region by employing GIS techniques and remote sensing data. Various parameters, including Land Use and Land Cover (LULC), Rainfall, Drainage Density (DD), Water Depth, Soil Type, Slope, Population Density, Road Density, Normalized Difference Vegetation Index (NDVI), Normalized Difference Built-Up Index (NDBI), Moisture Stress Index (MSI), Water Vegetation Water Index (WVWI), and Land Surface Temperature (LST), are considered. Thematic layers of these parameters are assigned different weights based on previous literature, reclassified, and superimposed in weighted overlay tool to develop a groundwater potential zones index map for Lahore. The groundwater recharge potential zones are categorized into five classes: Extremely Bad, Bad, Mediocre, Good, and Extremely Good. The groundwater potential zone index (GWPZI) map of Lahore reveals that the majority falls within the Bad to Mediocre recharge potential zones, covering 33% and 28% of the total land area in Lahore, respectively. Additionally, 14% of the total area falls under the category of Extremely Bad recharge potential zones, while Good to Extremely Good areas cover 19% and 6%, respectively. By providing policymakers and water supply authorities with valuable insights, this study underscores the significance of GIS techniques in groundwater management. Implementing the findings can aid in addressing Lahore's groundwater challenges and formulating sustainable water management strategies for the city's future. [ABSTRACT FROM AUTHOR]

Good quality water for human consumption, irrigation, and industrial use is very important. Today, around the world, water is contaminated by natural processes and human activities. This study aimed to evaluate the suitability of groundwater for drinking and irrigation, identify the source of fluoride and nitrate contamination, and assess the human health risks around the Cauvery River basin in southern India. A total of 30 groundwater samples were collected and analyzed for hydrochemical parameters, including EC, TDS, pH, Ca, Mg, Na, K, HCO3, Cl, SO4, NO3, and F−. The majority of groundwater samples in the study area are used for drinking and irrigation. The pH of groundwater in the study area was observed to be dominantly alkaline. The levels of TDS, Ca, Na, K, F, and TH exceeded the permissible limits recommended by BIS and WHO. Fluoride and nitrate levels in groundwater exceeded the permissible limits for drinking purposes in 43% and 50% of the samples, respectively. The excessive concentration of fluoride and nitrate in groundwater could pose serious human health problems. Fluoride and nitrate concentrations in groundwater vary between 0.1 and 2 mg/l and 12 and 95 mg/l, respectively. Based on the computation of the drinking water quality index, about 73% of groundwater samples were classified as excellent to good. Health risk was assessed for infants, children, and adults using non-carcinogenic risk indices such as hazard quotients (HQ), hazard indexes (HI), total hazard indices (THI), and carcinogenic risk indices (CR). Infants, children, and adults have different total hazards indexes ranging from 1.508 to 5.733, 1.579 to 6.003, and 0.011 to 0.046, respectively. Health risk assessment results indicated that the hazard index and hazard quotient were above the recommended limit of > 1 in most of the samples for infants and children. Non-carcinogenic risk and carcinogenic risks were more likely to affect infants and children rather than adults through ingestion of contaminated water. [ABSTRACT FROM AUTHOR]

This study explores the utility of silica concentration in deciphering geological controls and hydrogeochemical processes affecting groundwater quality in Mount Cameroon’s volcanic terrain. Fifty water samples from wells, boreholes, springs, and rivers were analysed for hydrochemical properties (EC, pH, temperature, TDS) and major ion concentrations (Ca2+ > Mg2+ > K +> Na+ and HCO3− > Cl −> NO3− > SO42−). The groundwater exhibits low mineralization, with a dominance of Ca2+, Mg2+, HCO3−, and SiO2, reflecting minimal water–rock interaction and short residence times. Spatial variations in hydrochemistry suggest diverse water–rock interactions and potential mixing processes (76% of samples in rock dominance zone). Silica concentrations (5.8–58.7 mg/L) and estimated chalcedony temperatures (> 60 ℃ at five sites) indicated depths exceeding 1000 m. This research highlights silica’s effectiveness in tracking water–rock interactions across diverse geological settings, regardless of flow depth or interaction time variations. Mineral saturation indices pointed towards supersaturation with silicate minerals (quartz) but undersaturation with carbonates, sulphates, and halides. These findings contribute to a better understanding of groundwater evolution in Mount Cameroon, valuable insights into the hydrogeochemical processes shaping groundwater quality, aiding sustainable water resource management practices that can benefit local communities by ensuring a reliable source of freshwater. However, opportunities exist to improve future studies and water resource management. For a more comprehensive understanding, future analyses should include a broader range of geochemical tracers, such as nitrate (NO3−) and phosphate (PO43−), to assess potential agricultural or anthropogenic contamination. The study also found elevated levels of chloride and sodium, suggesting potential anthropogenic influences on groundwater quality, such as agricultural practices and waste disposal.Article Highlights: Mt. Cameroon’s volcanic rocks store rainwater, forming vast underground reserves that feed springs and rivers. This study assessed water quality in a volcanic aquifer region. This study’s findings can guide sustainable water management practices in the region. [ABSTRACT FROM AUTHOR]

Long-term variations of ecological and hydrological parameters governing the natural reproduction of sturgeon are analyzed. It was found that long-term variations of hydrological characteristics are taking place against the background of cyclic development of phases with different water abundance and transformation of the annual redistribution of runoff. The contribution of long-term runoff regulation by the Iriklinskoe Reservoir to water regime variations in the Ural River is considered for its middle reaches. A conclusion is made regarding the need to restore the sturgeon herd in the Northern Caspian Sea. Recommendations are made regarding the priority measures for preserving the potential of sturgeon spawning grounds in the middle reaches of the Ural River. [ABSTRACT FROM AUTHOR]

In M'bahiakro, nitrate contamination of drinking well water is becoming a cause for concern and continues despite the efforts made in the town. To help monitor these waters, this study aims to predict nitrate concentrations in the M'bahiakro water table based on physico-chemical parameters measured in situ. To this end, a gradient error back-propagation (BPNN) artificial neural network (ANN) was developed to simulate nitrate concentrations using temperature (T), electrical conductivity (EC), dissolved oxygen (O2), redox potential (Eh) and well water depth as input data. The resulting dataset was divided into two parts to form the artificial neural network, where 70% of the dataset was used for training, and the remaining 30% was also divided into two equal parts: one for testing and the other for model validation. The models were configured using a constructive approach, which consists of testing each input variable individually in a reference network and combining the variables until the best intelligent model is obtained according to the chosen performance criteria. The intelligent models obtained were evaluated on the basis of the coefficient of determination (R2) closest to 1 and the lowest mean square error (MSE). The results obtained showed that the BPNN models developed using four input variables in the dry and rainy seasons provided the best results. The MSE and R2 values were around 0.01 mg/L and 95%, respectively. They are obviously more accurate since the mean square errors are low with coefficients of determination close to unity. The BPNN models thus obtained were able to reproduce satisfactorily the nitrate concentrations obtained experimentally in 19 wells in the town of M'bahiakro. However, it is essential to continue this study in order to define the time interval during which the BPNN models obtained can remain valid in terms of performance in the M'bahiakro area. [ABSTRACT FROM AUTHOR]

An effort has been made to develop statistical and ANN models for estimation of sodium concentration in pre-monsoon and post-monsoon seasons using routinely monitored water quality parameters of ground water wells in Jaipur district, Rajasthan (India). The Best Subset procedure based on R2 (coefficient of determination) and F (Fishers test) values was used in model dissemination. It was found that electrical conductivity, hardness, chloride, and sulphate could be used as surrogate parameters for the prediction of sodium. The model values of Na when compared with actual values (validation) showed a reasonably good matching. Further it was noticed that there was not a single model which could be used to predict the Na levels. It is primarily attributed to the fact that sodium concentration not only varies from site to site but also varies from season to season. Secondly, Principal component analysis was used to predict the dominating water quality constituents and it was revealed that four principal components are accounted for the total chemical variability in the ground water quality for pre-monsoon season and three principal components for post-monsoon season, respectively. The common factors conductivity, fluoride, nitrate, alkalinity, and phosphate have perceptible influence on the quality of groundwater of Jaipur district, Rajasthan. Finally, Back Propagation, three layered ANN models for both pre-monsoon and post-monsoon season was developed for estimation of sodium using the steepest descent optimization technique. ANN models were developed considering a fixed number of iterations as 1000 and the developed models were verified on the data not considered in calibration. The input variables considered for different model structures were identified through correlation analysis. Based on the statistical performance evaluation criteria such as root mean square error (RMSE), correlation coefficient (CC), and coefficient of efficiency (CE), the results indicated satisfactory performance of ANN based model. [ABSTRACT FROM AUTHOR]

Solid waste management is a burning issue that requires special attention and consideration in developing countries. In most cities and towns, it has become a public health concern due to uncontrolled dumping that has caused degradation of the natural environment. Therefore, the present study assessed the impact of dump yards on the surrounding environment by conducting physicochemical and biological analysis of groundwater and leachate samples and comparing it with control sites located at Silchar town of Assam, India. The result demonstrated that a large number of organic materials and inorganic salt leached to the surrounding environment by the decomposition of waste at open dumping site which significantly pollutes the groundwater sources of nearby areas. The sample site S5 recorded the highest value of WQI (100.78). Contamination of Total Coliform and E. Coli bacteria were recorded in the range of 96–2116 CFU/100 ml and 0–2466 CFU/100 ml respectively in sample sites. However, in control sites, coliform bacteria were found in the range of 8–43 CFU/100 ml and E. coli bacteria was found to be absent in all the control sites. The mean concentrations of Pb (8.94 mg L−1), Mn (19.12 mg L−1) and Ni (6.38 mg L−1) in the dump yards were found above the maximum permissible limit of EPA US, 1986; however, the concentrations of Cu (4.05 mg L−1) and Cd (0.45 mg L−1) were within the permissible limit. Hence, there is a need for proper scientific planning and management of waste disposal for the protection of our surrounding environment. [ABSTRACT FROM AUTHOR]

Nitrate contamination in drinking water is now gaining global attention because of its potential effect on human health. In this study, nitrate concentrations and their potential sources in groundwater and surface water were investigated using hydrochemical and isotopic methods. The physical parameters were measured in-situ using multi parameter meters; major ions, stable isotopes (δ2H and δ18O of H2O) and δ15N and δ18O of NO3− were measured using the Ion Chromatography, laser spectrometry and titanium (III) reduction method respectively. The results indicate that the dominant water type is Ca-Mg-HCO3, followed by the Ca–Mg–Cl hydrogeochemical facies. The plot of NO3−/Cl− against Cl− revealed that the dominant sources of NO3− in the groundwater are manure/sewage with few traces from soil inputs. Meanwhile the plot of δ2H-H2O against δ18O-H2O showed that rainfall is the main source of groundwater recharge with few groundwater samples showing evidence of recharge from an enriched source (Black Volta River). The plot of δ18O – NO3− against δ15N – NO3− suggests that a significant percentage of nitrate is from manure and sewage, followed by the soil zone, hence leading to nitrification and denitrification being important biological processes affecting NO3− concentrations in groundwater in the study area. The stable isotope mixing model suggests manure contributed a mean proportional contribution of about 74% of NO3− to groundwater in the study area, while soil nitrogen contributed 10%. The Nitrate Pollution Index (NPI) suggests that about 80.2% of water samples were pollution free, while anthropogenic activities resulted in about 8.3% of the pollution index. Since most samples with lower nitrate pollution indices were observed around recharged areas and increased toward the discharge points, our study suggests the possibility that recharge areas of the water was free or lowest in nitrate contamination. [ABSTRACT FROM AUTHOR]

Freshwater scarcity poses challenges to aquaculture worldwide, including countries like Egypt. In this study, we investigate the feasibility of integrating underground saline water (USW) with varying salinities into a Biofloc (BFT) system for desert mariculture of Florida red tilapia (FRT) and its impacts on water quality, fish performance and health. Four BFT treatments (C/N ratio = 15) were examined in triplicate using four salinity levels 0 ppt, 12 ppt, 24 ppt and 36 ppt, expressed as S0, S12, S24 and S36, respectively. For 75 days, a total of 12 fiberglass tanks (each 250 L−1 water) were used to store FRT fry (average weight of 1.73 ± 0.01 g/fish). The fish were fed an experimental diet (protein/fat = 30/5) and an additional carbon source of rice bran. The results revealed that group S12 showed better growth indicators, higher survival rate, lower FCR, and lower ammonia levels, while group S0 exhibited lower growth indicators (final weight, weight gain, and specific growth rate) than all groups. The serum kidney, liver, and antioxidant indices performed better in the S12 group. At 12 ppt, the immune-related parameter (IgM) increased by 22.5%, while the stress parameter (cortisol) decreased by 40.8% compared to the S0 group. The liver and intestinal histopathological results revealed that the S12 and S24 groups performed better. Pathogenic bacterial load counts favored the S24 group, which had the lowest number among the groups studied. The recommended salinity for FRT cultivation in USW and BFT is 19.94-20 ppt, determined by polynomial regression of FW and FCR. [ABSTRACT FROM AUTHOR]

Determining groundwater quality status and hydro-geochemistry of an aquifer is crucial to ensure cleaner and safer water for human consumption. Groundwater sustainability issues are getting attraction due to global warming and complexities in land utilization. These concerns increased the challenge of gaining an appropriate comprehension of anthropogenic activities and natural processes, as well as how they influence the quality of surface water and groundwater systems. In the present investigation, 48 groundwater samples were collected and analyzed from the Panchkula district of Haryana, located in the Upper Ghaggar River Basin, to explore the sources and driving factors responsible for hydro-geochemistry of the aquifers falling under the natural and anthropogenically intervened areas. Groundwater sampling was carried out in the premonsoon (PRM) as well as postmonsoon (POM) seasons to examine the spatio-seasonal variations in its quality. The results of the study revealed that reverse ion exchange processes are mainly controlling the aquifer geochemistry in areas occupied by natural vegetation, while the nitrate and chloride content of groundwater was the result of anthropogenic activities. The mechanisms governing groundwater quality and the related hydro-geochemical processes were assessed using binary plots of different cations and anions, along with the Gibbs plot and chloro-alkaline indices (CAI). Saturation indices (SI) indicated that groundwater was over-saturated with respect to dolomite, calcite, and aragonite, while 68.75% and 50% of samples indicated under-saturation with respect to anhydride and gypsum, respectively. Principal component analysis (PCA) and Pearson's correlation coefficients were also considered to affirm the processes taking place to control the aquifer chemistry. Groundwater in the majority of the area was found suitable for drinking purposes except in the locations where high nitrate concentrations were recorded, thus suggesting the use of water treatment facilities for such areas. [ABSTRACT FROM AUTHOR]

This paper presents findings on groundwater physiochemical composition and radioactivity levels in households in Bac Lieu province, Vietnam. Through discriminant analysis, it was observed that groundwater quality exhibits spatial variations corresponding to saline intrusion zones. The paired-samples T-tests revealed significantly different ratios of Ra-224, Ra-226, and Ra-228 isotopes between Na–Cl and Ca–Na–HCO3 water types. All three water types had a ratio of Ra-226/Ra-228 of approximately one, indicating the presence of groundwater aquifers beneath the crust and fluvial marine sediment. Furthermore, strong associations between sulfate and calcium suggest that CO2 enrichment in groundwater aquifers indicates anoxic aquatic environments. Twenty-five of the thirty-three evaluated samples exceeded the national technical regulations for domestic water quality with parameters such as chloride, sulfate, sodium, gross alpha, or total dissolved solids. Fifteen samples exceeded gross alpha's allowable contamination threshold of 0.1 Bq/L. The combination of Ra-226 and Ra-228 did not surpass the U.S. Environmental Protection Agency's recommended limit of 0.185 Bq/L. However, nineteen samples exhibited annual committed effective doses of radium isotopes for infants that exceeded the WHO recommendation of 0.1 mSv/year. [ABSTRACT FROM AUTHOR]

Excessive intake of iodine will do harm to human health. In recent years, high iodine groundwater has become a global concern after high arsenic and high fluorine groundwater. A deep understanding of the environmental factors affecting iodine accumulation in groundwater and the mechanism of migration and transformation is the scientific prerequisite for effective prevention and control of iodine pollution in groundwater. The paper comprehensively investigated the relevant literature on iodine pollution of groundwater and summarized the present spatial distribution and hydrochemical characteristics of iodine-enriched groundwater. Environmental factors and hydrogeological conditions affecting iodine enrichment in aquifers are systematically summarized. An in-depth analysis of the hydrologic geochemistry, physical chemistry, biogeochemistry and human impacts of iodine transport and transformation in the surface environment was conducted, the results and conclusions in the field of high iodine groundwater research are summarized comprehensively and systematically. Stable isotope can be used as a powerful tool to track the sources of hydrochemical components, biogeochemistry processes, recharge sources and flow paths of groundwater in hydrogeological systems, to provide effective research methods and means for the study of high iodine groundwater system, and deepen the understanding of the formation mechanism of high iodine groundwater, the application of isotopic technique in high iodine groundwater is also systematically summarized, which enriches the method and theory of high iodine groundwater research. This paper provides more scientific basis for the prevention and control of groundwater iodine pollution and the management of groundwater resources in water-scarce areas. [ABSTRACT FROM AUTHOR]

There has been a significant rise in cancer-related mortality in the Ladakh region during the past 10 years. The most common type of case is gastrointestinal cancer, which has been linked in theory by medical research to lifestyle factors, high altitude conditions, and the prevalence of Helicobacter pylori bacteria brought on by poor hygiene. Nevertheless, the precise cause of the rise in cancer cases is still unknown. Concurrently, there has been a significant change in Ladakh's water use practices due to development, improved basic utilities, and related vocational shifts. The local population has become increasingly reliant on groundwater since it provides a year-round, continuous water supply for home and agricultural uses. In this study, we assessed heavy metal contamination in groundwaters and associated human health risks. The results indicate that 46–96% of the groundwater samples have heavy metal pollution with a health hazard index > 1, which means using these groundwaters for drinking, food preparation, and agriculture is likely to result in carcinogenic and non-carcinogenic health hazards. The main heavy metal contaminants found in the groundwater of the Leh district include Cr, As, Hg, and U. According to the health risk assessment, 46–76% of the groundwater samples contain unsafe levels of Cr and As. Prolonged exposure to these levels is likely to cause gastrointestinal cancer in the local population. Acute to chronic exposure to U and Hg concentrations present in some groundwater samples is likely to result in various non-carcinogenic health risks. [ABSTRACT FROM AUTHOR]

The soil-water characteristic curve (SWCC) is an important basis for describing hydraulic properties, which is closely related to environmental problems such as the migration of toxic substances from groundwater and soil. The SWCC models vary considerably with respect to the void ratio or bulk density. However, the void ratio and bulk density of the same soil change at different depths or positions within a flat space. Accurate simulation or calculation requires a precise SWCC, but measuring every SWCC under each density or void ratio condition is difficult. In this study, two particle packing models, the Kwan model and the modified linear packing density model (MLPDM), were introduced into the van Genuchten (VG) model to predict the SWCC for soil at the minimum void ratio (the maximum dry density). Then, the prediction method of the SWCCs for the same soil with different densities or void ratios was given. A series of laboratory tests using quartz sand mixtures were conducted to verify the accuracy of two extended models (the K-VG model and the M-VG model). For the K-VG model, the average RMSE was 0.020. For the M-VG model, the average RMSE was 0.017. In general, the SWCCs predicted by the two extended models were consistent with the measured values. [ABSTRACT FROM AUTHOR]

Seawater intrusion seriously threatens the quality of coastal groundwater, affecting nearly 40% of the world's population in coastal areas. A study was conducted in the Kamini watershed situated in the Udupi district of Karnataka to assess the groundwater quality and extent of seawater intrusion. During the pre-monsoon period, 57 groundwater and 3 surface water samples were analyzed to understand the impact of seawater on the groundwater and surface water. The analysis revealed that the groundwater in the study area is slightly alkaline. The weighted overlay analysis map indicated that 11% of the study area is unsuitable for drinking water due to the influence of seawater. The Piper plot analysis revealed that the groundwater is predominantly CaMgCl facies. The hydrogeochemical facies evolution diagram (HFED) showed that 62% of the groundwater is affected by seawater. The HFED and Piper plots also indicate that the surface water is also affected by seawater. These results are also supported by various molar ratios such as Cl− vs. Cl⁻/HCO3⁻, Cl⁻ vs. Na⁺/Cl⁻, Cl− vs. SO42−/Cl−, and Cl⁻/HCO3− vs. Mg2+/Ca2+, suggesting that the majority of the water sample has been affected by seawater. The saturation indices indicated that mineral dissolution has significantly contributed to groundwater salinization. The correlation between sulfate concentration and calcite and dolomite dissolution suggested the influence of seawater intrusion in the coastal aquifer. The process of reverse ion exchange mainly influences the groundwater chemistry according to chloroalkali indices. The total hazard index (THI) values of nitrate and fluoride exceeded limits, posing health risks to adults and children. Studies suggest that with time and space, seawater intrusion is increasing in some pockets of the study area, especially along the west coast. [ABSTRACT FROM AUTHOR]

The power output of reverse electrodialysis (RED), an important renewable energy technology, can be improved using high-salinity feed solutions. Herein, a RED stack of ultrathin ion exchange membranes was operated continuously for 10 days using reverse osmosis brine (~0.9 M NaClequivalent) and underground water (~0.01 M NaClequivalent). The net power and net energy efficiency were initially 1.8 W m−2cell pair and 40.8%, respectively, and then decreased gradually, as did the generated current and stack resistance. This deterioration was caused not by conventional membrane fouling but by trapped water inside the polymer matrix of the anion exchange membrane, especially near the cathode. The high salinity gradient and ultrathin membranes caused a flux imbalance between co-ion transport and osmotic water permeation. Further, bulk mass transfer was enhanced inside the RED stack to maintain electroneutrality. Therefore, combinations of membranes with high water permeability and permselectivity may be required to achieve stable RED operation. [ABSTRACT FROM AUTHOR]

Pharmaceutically active compounds (PACs) are ubiquitous contaminants that can pollute the environment. This study critically analyzes the sorption of PACs to soil materials based on 137 published papers encompassing 106 PACs and 212 soil materials. The batch technique is commonly employed for sorption studies of PACs to soil, but the experimental setups vary in terms of the type and number of PACs, mixing time, solid to liquid (S/L) ratio, solution type, range of initial concentration, and bio-inhibition method. Sorption competition among PACs or between PACs and dissolved organic matter occurs for certain cases. Linear or close to linear behavior was reported for sorption of many PACs to soil, but sorption of some PACs deviates from linearity. The reaction of PACs to soil is fast at the initial stages but slows down as it approaches equilibrium. PACs characteristics, soil properties, and solution attributes intricately influence the sorption process. Zwitterionic PACs exhibit the highest sorption affinity, whereas neutral PACs display increased sensitivity to soil hydrophobicity. The average sorption coefficient (K) ranges from 0.0915 mL/g for anionic sulfonamides to 84725.5 mL/g for zwitterionic norfloxacin. An increase in the molar volume corresponds to heightened sorption for cationic PACs and reduced sorption for anionic PACs. Increasing solubility, soil organic carbon, cation exchange capacity, S/L ratio, and soil surface area while decreasing pH, ionic strength, and temperature result in an increase in K. The values of K determined by the batch technique are higher than their column-determined counterparts, possibly due to variations in the employed residence times between the two systems. Several models have been developed to estimate K of PACs, but they are limited in their applicability to specific PACs and soil types. Future research related to sorption of PACs to soils has been suggested. [ABSTRACT FROM AUTHOR]

Equilibrium passive sampling continues to find increasing use for performing in situ assessments and monitoring of hydrophobic organic compounds (HOCs). Although this method has been successfully used in several field studies including open surface waters and sediments, comparatively, their use in groundwater has been very limited. In this study, low-density polyethylene (LDPE) passive samplers were deployed for 80 days in three groundwater wells contaminated with polycyclic aromatic hydrocarbons (PAHs). Prior to deployment, LDPE was loaded with performance reference compounds (PRCs) consisting of deuterated PAHs and their release used to ascertain system equilibrium. Within the 80-day deployment period, LDPE-groundwater equilibrium was confirmed for PAHs with molecular weights (MWs) in the range of 178 to 228 (i.e. anthracene, chrysene). Measured freely dissolved concentrations (Cw) were between one to three orders of magnitude lower than the total filtered concentrations (Ctotal) in the studied wells. The sum of PAHs (ΣPAHs) measured based on Cw and Ctotal were 2.05, 0.07 and 29.2 μg L−1 and 197, 59.7 and 1010 μg L−1, at wells 1, 2 and 3, respectively. A separate dataset, comprising long-term (2010 to 2022) concentrations of PAHs in total (i.e., unfiltered) groundwater, is also presented to provide insight into PAH contamination levels at the assessed groundwater wells based on conventional measurement. Estimated in situ LDPE daily clearance volumes (2.34 to 27.56 Ld−1) for the target analytes were far less than the daily turnover of ground water (144 to 348 Ld−1) encountered in the wells eliminating the possibility of depletive sampling of the groundwater by the passive samplers. These results represent the first published study on the practical application of equilibrium passive sampling using LDPE for monitoring and quantitatively assessing PAHs in groundwater. Also, this work demonstrates that LDPEs are a useful tool for measuring the Cw of PAHs in groundwater, a critical contaminant in many ecological and human health risk assessments. [ABSTRACT FROM AUTHOR]

The identification of groundwater contamination sources (IGCSs) is an important requirement for the remediation and treatment of groundwater contamination. The data assimilation methods such as ensemble Kalman filter (EnKF) and ensemble smoother (ES) have been applied to IGCSs in recent years and obtained good identification results. The unscented kalman filter (UKF) is also a data assimilation method with the potential to simultaneously identify hydraulic conductivity and GCSs. However, when UKF is applied to identify hydraulic conductivity and GCSs, it is necessary to use the observed data at different times separately, which increases the complexity of the update process and this may result in low identification accuracy. ES is a variant of EnKF that updates the system parameters with all observed data in all time periods, which makes ES faster and easier to implement than EnKF. Therefore, inspired by the ES, an unscented kalman smoother (UKS) based on UKF was proposed for simultaneously identifying the hydraulic conductivity and GCSs in this study. The UKS can use the data observed in all time periods simultaneously, while it is also simpler to operate and the calculation speed is faster. Present studies have shown that ES can solve IGCS problems. Thus, ES was also applied to identify the hydraulic conductivity and GCSs in this study, and its identification performance was compared with UKS. In contrast to previous applications of ES to IGCSs, both UKS and ES were set up with stop iteration conditions instead of only performing one update process, and thus both methods applied multiple update processes. The results showed that compared with ES, the identification results obtained by UKS were characterized by greater stability, higher accuracy, and the iterative process required less iteration process and computational time. [ABSTRACT FROM AUTHOR]

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

The distribution of rare alkalis (Li, Rb, and Cs) is analyzed in spatially linked water objects of the Baikal geosystem: water of Baikal and its tributaries, underground water from boreholes and thermal springs, and the Angara River (the sole outlet), which are located in the Baikal rift zone. The rare alkali content differs significantly in some water objects, but the average and median contents are similar in the surface and deep water of Lake Baikal and the Angara River. The water of Barguzin thermal springs of the eastern shore of Lake Baikal contains the maximum amount of rare alkalis, but this affects the Baikal water insignificantly due to its natural self-cleaning and deep renewal of water during geodynamic movements. The similar rare alkali contents of Barguzin and some thermal springs of Kamchatka emphasize their indicator role in the genesis of water objects. [ABSTRACT FROM AUTHOR]

Evaluating groundwater inflow is greatly significant for ensuring the safety and economy during foundation pit dewatering with suspended waterproof curtains. However, there are limited applicable methods to predict the groundwater inflow of circle foundation pit with waterproof curtains in deep unconfined aquifers. In this study, based on Darcy's law and the continuity of water flow, the impact of suspended waterproof curtains on groundwater seepage was initially analyzed during circle foundation pit dewatering in deep unconfined aquifers. Furthermore, an analytical solution was proposed for groundwater inflow of circle foundation pit with suspended waterproof curtains in the unconfined aquifers. The effect of suspended waterproof curtains on seepage area, seepage direction, and seepage path were respectively considered by introducing the buried depth of waterproof curtain, the anisotropy coefficient, and the seepage path reduction coefficient. Finally, based on the self-conducted indoor seepage experiment and other cases (an indoor seepage experiment and two actual engineering projects), this proposed method was applied to conduct a comparative analysis with the existing methods. Results indicated that the proposed method can more reasonably evaluate the groundwater inflow of circle foundation pit with waterproof curtains in the unconfined aquifer, which can provide a better guidance for the groundwater inflow control in the practical dewatering projects. [ABSTRACT FROM AUTHOR]

Iodine is one of the essential trace elements in the human body, and excessive or insufficient intake will affect human health. To ensure the safety of drinking water resources, the spatial distribution of iodine content and migration enrichment factors in shallow underground salty water in Tianjin coastal area were studied. The results show that the iodine (as I−) content of shallow groundwater ranges from not detected (ND) to 1320 μg/L, and high iodine groundwater (100–300 μg/L) and super-high iodine groundwater (> 300 μg/L) account for 37.5% of the groundwater samples, distributed in the east, west, central and south of the study area; iodine-deficient groundwater (< 25 μg/L) accounts for 10% of the groundwater samples, and iodine-suitable groundwater (25–100 μg/L) accounts for 15% of the groundwater samples. From north to south and from northwest to southeast, the shallow groundwater in the study area changed from freshwater and brackish water to saline and salt water; the I− concentrations in freshwater, brackish water, and saltwater were significantly different, and the I− concentrations tended to increase with the increase of TDS concentration; the main hydrochemical types in this direction changed as HCO3-Ca·Na → Cl·SO4-Na·Mg → HCO3·Cl-Na·Ca → Cl·HCO3-Na → Cl-Na type shift; high iodine and super-high iodine groundwater chemistry types are mainly Cl-Na type, Cl·HCO3-Na type and HCO3-Ca·Na type. The main source of iodine in groundwater is inferred to be marine sediments. Sedimentary iodine is released during dissolution of marine sediments. I− concentrations increase along with the groundwater flow. In the eastern area, the poor permeability of the aquifer due to the main lithology of mucky clay slows down the groundwater flow, and strong evaporation and concentration on account of the shallow groundwater depth contributes significantly to iodine enrichment. [ABSTRACT FROM AUTHOR]

Research on the observation of nutrient release rates from slow-release and regular fertilizers combined with the percolation rate in the soil is scarce. This work aims to observe potassium and phosphate release behavior from slow-release and regular fertilizer, followed by the percolation of that nutrient in the soil. The characteristics of the soil were analyzed using X-ray Diffraction (XRD), X-ray Fluorescence (XRF), and Scanning Electron Microscope (SEM). The concentration of potassium and phosphate in soil is analyzed using Atomic Absorption Spectroscopy (AAS) and Ultraviolet–Visible Spectroscopy (UV–Vis), respectively. The release rate of nutrients from slow-release fertilizer is 6 to 8 times slower than regular fertilizer. Meanwhile, the rate of nutrients released from slow-release and regular fertilizer followed by soil percolation matches the quadratic equation. Potassium adsorption on the soil surface is significantly higher than that of potassium. The negativity of soil polarity contributed to the high level of potassium adsorption on soil particle surfaces. The low phosphate adsorption capability of magnetite and the negativity of soil polarity contributed to the soil's low phosphate adsorption. [ABSTRACT FROM AUTHOR]

Trace element (TEs) contamination in groundwater is a key factor for health risk assessment and one of the environmental challenges linked with Ghana's sustainable development. This study aims to investigate TE concentrations in groundwater used for drinking and domestic purposes and their potential health risk in the Kumasi Metropolis using multivariate statistics. In the study, 23 groundwater samples were analyzed for 32 TEs using Perkin Elmer Nexion 2000 Inductively Coupled Plasma Mass Spectrometer (ICP-MS). Levels of TEs recorded in the study were in order of Na > Si > Ca > K > Mg > S > Ba > Cu > Zn > Al > Sr > Li > Mn > P > Fe > B > Pb > Ni > Co > Bi > Se > Sb > Cr > As > Ti > Be > V > U > C d > T l > Mo > Hg. The study revealed that the concentration of trace and toxic elements like Al, Cu, and Pb exceeded their corresponding WHO permissible standards. Hazard index (HI) values and total likely cancer risk (TLCR) values for non-carcinogenic and carcinogenic health risks indicate that 91.3% of the total sampling sites presented health concerns to adults and children. The mean TLCR values associated with exposure to carcinogenic metals via ingestion of groundwater samples were estimated to be 2.09 × 10−4 and 4.44 × 10−4 for adults and children respectively. Exposure through the ingestion pathway was found to be more risky compared to dermal contacts. Children are particularly vulnerable to these health hazards. Pearson correlation (PC) matrix, principal component analysis (PCA), and hierarchical cluster analysis (HCA) suggested that sources of TEs in the groundwater are attributed to both anthropogenic and geogenic factors. [ABSTRACT FROM AUTHOR]

Investigations have revealed the presence of microplastics in both soil and groundwater, but the migration characteristics from soil to groundwater remain incompletely understood. In this study, two sampling sections consisting of soil-groundwater-river water were established near Lianxi Bridge and Xilin Bridge along the Jiuxi River in Xiamen. A total of 22 soil samples, 36 groundwater samples, and 18 river water samples were collected. Microplastics were detected in all samples with an abundance range of 392–836 n/kg in soil (mean, 655 ± 177 n/kg), 0.58–2.48 n/L groundwater (mean, 1.23 ± 0.42 n/L), and 0.38–1.80 n/L in river water (mean, 0.86 ± 0.41 n/L). Flakes predominantly constituted the shape of microplastics found in soil, while fibers dominated those present in water. Black, yellow, and red were the dominant color types. Polyamide (PA) and polyethylene (PE) were the main components of microplastics within soils, whereas polyethylene terephthalate (PET), polypropylene (PP), and PA prevailed within water. Microplastic particle sizes ranged from 39 to 2498 μm in soils, mainly from 29 to 3394 μm in water. The upstream section displayed higher abundances of microplastic compared to the downstream, revealing the soil particles having an intercepting effect on microplastics. The distribution and migration of microplastics in soil and groundwater are affected by many factors, including natural and anthropogenic factors, such as soil depth, soil properties, pore structure, hydrodynamics, hydraulic connections between groundwater and surface water, the extensive utilization and disposal of plastics, irrational exploitation of groundwater, and morphology and types of microplastics. These research findings contribute to a better understanding of the pathways, migration capacity, and influencing factors associated with microplastic entry into groundwater, thereby providing valuable technical support for the development of strategies aimed at controlling microplastic pollution. [ABSTRACT FROM AUTHOR]

The present study focused on the distribution of uranium in groundwater samples collected from various sources in the Chikkaballapur district and its associated risk in humans. Seventy-five groundwater samples were collected during pre-monsoon and post-monsoon seasons and were analysed for uranium concentration along with different water quality parameters. The uranium concentration ranged from 0.23 to 285.23 µg/L in the pre-monsoon season and from 0.02 to 107.87 µg/L in the post-monsoon season. More than 90% of samples, except a few, were under the safe limits of 60 µg/L as directed by the Department of Atomic Energy (DAE) of India's Atomic Energy Regulatory Board (AERB). The study analysed physicochemical parameters like pH, total dissolved solids (TDS), nitrate, total hardness, phosphate, sulphate and fluoride in collected water samples. Out of all samples, few samples noted higher values of TDS, nitrate and fluoride. Their correlation along with uranium is detailed in the study. Owing to its slightly elevated content, an evaluation of the radiological and chemical hazards associated with uranium consumption was analysed. When the risk resulting from chemical toxicity was evaluated, relatively few samples had a hazard quotient (HQ) score higher than 1, which suggested that the people were vulnerable to chemical danger. This study also evaluates the dangers of elevated uranium levels in groundwater samples to the general public's health. It also acknowledges the importance of routinely evaluating and treating the drinking water sources in the region. [ABSTRACT FROM AUTHOR]

Jakarta is the center of Indonesia's economy and development. However, the city of Jakarta suffers from many problems related to groundwater, and good groundwater governance is needed to realize groundwater sustainability. Groundwater management can be initiated by undertaking conceptual and numerical groundwater modeling. This paper reviews several previous studies related to groundwater modeling of the Jakarta groundwater basin that have provided information about the groundwater system and groundwater quantity. However, improvements are required for any further studies. The critical challenges to providing a complete picture of the groundwater conditions in the Jakarta groundwater basin are the availability of reliable data and improved groundwater flow models. [ABSTRACT FROM AUTHOR]

Groundwater is the most reliable source of freshwater for household, industrial, and agricultural usage. However, anthropogenic interventions in the water cycle have disrupted sustainable groundwater management. This research aims to comprehend the future of groundwater recharge predominantly due to rainfall under changing climate. In this study, predictors of groundwater recharge such as precipitation, land use land cover (LULC), soil type, land slope, temperature, potential evapotranspiration, and aridity index (ArIn) were used for the Punjab region of India over the duration of 34 years, from 1986 to 2019. To simulate future conditions, various climate change scenarios from the CMIP6 report have been incorporated. Different Artificial Intelligence and Deep Learning models, ranging from the straightforward Linear Regression model to the intricate Extreme Gradient Booting (XGBoost), used these parameters as input. Statistical analysis of the models showed that XGBoost is most effective in predicting the groundwater recharge phenomena. Correlation studies revealed precipitation to be the primary contributor to recharge, followed by the ArIn, while soil type and slope are found to have the strongest inverse correlation. The models' resilience and performance were investigated by conducting a k-fold cross-validation analysis. The pattern of groundwater recharge is forecasted for the years 2020 to 2035 across Punjab with different climate change scenarios. The study demonstrates how the Punjab area is mirroring its current status around Shared Socioeconomic Pathway (SSP) 370. Groundwater level estimates confirmed its strong correlation with and dependence on groundwater recharge. The analysis is strengthened by comparing the AI-predicted groundwater recharge with the Central Ground Water Board (CGWB) Punjab's annual estimate. Key points: • Data-driven deep learning models can model groundwater recharge with high accuracy without extensive aquifer parameter data requirement. • Pronounced effect of climate change on groundwater recharge in the future pertaining to the different climate change scenarios (SSPs). • Forecasted groundwater recharge and level data shows significant match with the CGWB, Govt. of India's estimates and observed data. [ABSTRACT FROM AUTHOR]

The study comprised characterisation of Groundwater of Himalayan State Uttarakhand India at 46 locations and its suitability assessment for drinking and irrigation purpose. Samples from each of 13 districts datasets are obtained from web site of Uttarakhand Pollution Control Board and data analysis is performed for physicochemical as well as heavy metals for the year 2022 and 2023 (pre-monsoon and post-monsoon in each year) was compiled and the average of each parameter from each location is analysed. The average of each parameter was compared mainly with the Indian Standards. From the analysis of the data, it is revealed that none of the sample exceeded the permissible limit and hence groundwater is fit for drinking purpose. Out of the eight heavy metals analysed, As, Hg, Cr and Cd were not detectable at all samples and Cu was found only in 63% samples and was observed above the acceptable limits. Pb is detected only at three locations which are mainly the industrial locations, and was found to be above the prescribed limits. Zn and Fe are found in all samples. Zn is always found below the acceptable limit though Fe is always detected above the prescribed limits. Ionic analysis revealed that the water is suitable for irrigation purpose. In all the samples, the amount of ions detected was in the following order: CO3 > HCO3 > Ca > Mg > SO4 > Cl > Na > K. In the water from each of the sample location, alkaline earth metals exceed over alkalis and are mainly calcium and bicarbonate type. Physicochemical parameters are found to have a negative correlation with metals in most of the cases. However, metals show positive correlation with each other. [ABSTRACT FROM AUTHOR]

This study investigates the radon concentration in groundwater in Kupwara, the northernmost district of the Kashmir valley. It further assesses the annual effective dose experienced by the district’s diverse population—infants, children, and adults—attributable to both inhalation of airborne radon released from drinking water and direct ingestion. In addition to this, the calculation of gamma dose rate is also carried out at each of the sampling site of radon. A portable radon-thoron monitor and a portable gamma radiation detector were respectively employed to estimate the activity concentration of radon in water samples and to measure the gamma dose rate. The radon concentration was found to exhibit variability from a minimum of 2.9 BqL−1 to a maximum of 197.2 BqL−1, with a mean of 26.3 BqL−1 and a standard deviation of 23.3 BqL−1. From a total of 85 samples, 10.6% of the samples had radon activity concentrations exceeding the permissible limits of 40 BqL−1 set by the United Nations Scientific Committee on Effects of Atomic Radiations as reported by UNSCEAR (Sources and effects of ionizing radiation, 2008) and only 1.2% of the samples have radon activity concentration exceeding the permissible limits of 100 BqL−1 set by the World Health Organization as reported by WHO (WHO guidelines for drinking-water quality, World Health Organization, Geneva, 2008). The mean of the annual effective dose due to inhalation for all age groups as well as the annual ingestion dose for infants and children, surpasses the World Health Organization’s limit of 100 μSv y−1 as reported by WHO (WHO guidelines for drinking-water quality, World Health Organization, Geneva, 2008). The observed gamma radiation dose rate in the vicinity of groundwater radon sites ranged from a minimum of 138 nSv h−1 to a maximum of 250 nSv h−1. The data indicated no significant correlation between the dose rate of gamma radiation and the radon levels in the groundwater. Radon concentration of potable water in the study area presents a non-negligible exposure pathway for residents. Therefore, the judicious application of established radon mitigation techniques is pivotal to minimize public health vulnerabilities. [ABSTRACT FROM AUTHOR]

Pollution of farmland by heavy metals threatens food security and human health. In addition, heavy metals in soil could infiltrate into groundwater to influence the water quality and safety of drinking water. However, the relationship between heavy metal pollution in soil and groundwater is still not clear. In this study, we investigated the soil and groundwater in the Guanzhong Plain region, which is a significant grain production base in China, and determined the spatial distributions, ecological risk, sources, and migration fates of heavy metals (As, Cd, Cr, Cu, Ni, Pb, and Zn). The results showed that the mean values (0–20 cm) in the soil were 19.57 mg kg−1 for As, 0.71 mg kg−1 for Cd, 69.65 mg kg−1 for Cr, 21.97 mg kg−1 for Cu, 28.67 mg kg−1 for Ni, 17.54 mg kg−1 for Pb, and 73.77 mg kg−1 for Zn, and the corresponding mean values in groundwater were 1.2, 0.04, 4.69, 0.15, 0.07, 0.3, and 3.6 μg L−1, respectively. The mean values for As, Cd, Cr, Pb, and Zn in soil exceeded the background values, and the mean values for As, Cd and Pb exceeded those in groundwater. Positive matrix factorization models identified five sources (fertilizers and organic fertilizers, natural sources, pesticides and herbicides, industrial activities, and sedimentation caused by transportation) for heavy metal pollution in soil and four sources (industry activity, atmospheric sedimentation caused by transportation, natural sources, and agriculture) for heavy metal pollution in groundwater. The soil particle composition and soil organic carbon content were important factors that affected the vertical distribution of heavy metals in the soil. The migration modes (convection and diffusion) were not found for all heavy metals. These results help to understand the relationships between heavy metals in soil and groundwater in farmland ecosystems regionally. [ABSTRACT FROM AUTHOR]

This research examines whether the groundwater in the Sivakasi Region of South India is suitable for consumption, and assesses the possible health hazards for various age demographics including infants, children, teenagers, and adults. A total of 77 groundwater samples were gathered, covering a total area of 580 km2 and analyzed for major and minor ions. The hydrogen ion concentration (pH) of the samples indicates neutral to marginally alkaline. The total dissolved solids (TDS) fluctuate from 255 to 2701 mg/l and electrical conductivity varies from 364 to 3540 µS/cm. A wide range of fluoride concentration was detected (0.1 to 3.2 mg/l) with nearly 38% groundwater samples surpassing the proposed limit (1.5 mg/l) suggested by the World Health Organization in 2017. Gibbs plot analysis suggested that most of the samples were influenced by geogenic factors, primarily rock weathering in this region. Correlation analysis showed that most of the samples were impacted by both natural and human sources. The pollution index of groundwater (PIG) fluctuated from 0.67 to 2.60 with approximately 30% and 53% of samples falling into insignificant and low pollution categories, respectively. Furthermore, 10% and 5% of total samples were characterized as moderate and high pollution levels, and 2% as very high pollution category. Spatial analysis using GIS revealed that 440.63 km2 were within safe fluoride levels according to the WHO standards, while 139.32 km2 were identified as risk zone. The principal component analysis (PCA1) showed strong positive loadings on EC (0.994), TDS (0.905), Mg2+ (0.910), Cl− (0.903) and HCO3− (0.923) indicating rock water interaction. PCA2 accounts the high positive factor loading on HCO3− (0.864) indicating ion exchange and mineral leaching. The PCA1 and PCA2 indicated that variables such as mineral leaching and rock water interaction are the major mechanisms contributing to the chemical signatures in groundwater, which may support for the elevated fluoride levels in certain areas. Risk assessments, including Hazard Quotient results showed that 71%, 61% 38%, and 34% of groundwater samples exceeded the permissible THI limit (THI > 1) for infants, children, teenagers, and adults, respectively. The study recommends implementing measures such as denitrification, defluorination, rainwater harvesting, and improved sanitation infrastructure to enhance the health conditions in the study region. Additionally, it suggests introducing educational programs in rural areas to create awareness about the health dangers due to consumption of water with high fluoride levels. [ABSTRACT FROM AUTHOR]

Groundwater near a sulfuric acid plant in Xingyang, Henan, China was sampled from seven distinct sites to explore the prevalence of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs). Results showed that genes aadA, blaCTX-M, tetA, qnrA, and sul1 were detected with 100% frequency followed by aac(6')-Ib (85.71%), ermB (85.71%), and tetX (71.42%). Most abundant ARGs were sul1 in LSA2 (1.15 × 1011 copies/mL), tetA in LSA6 (4.95 × 1010 copies/mL), aadA in LSA2 (4.56 × 109 copies/mL), blaCTX-M in LSA4 (1.19 × 109 copies/mL), and ermB in LSA5 (1.07 × 109 copies/mL). Moreover, in LSA2, intl1 as a marker of class 1 integron emerged as the most abundant gene as part of MGE (2.25 × 1011 copies/mL), trailed by ISCR1 (1.57 × 109 copies/mL). Environmental factors explained 81.34% of ARG variations, with a strong positive correlation between the intl2 and blaCTX-M genes, as well as the ISCR1 gene and qnrA, tetA, intl2, and blaCTX-M. Furthermore, the intI1 gene had a strong positive connection with the aadA, tetA, and sul1 genes. Moreover, the aac(6')-Ib gene was associated with As, Pb, Mg, Ca, and HCO3-. The intl2 gene was also shown to be strongly associated with Cd. Notably, network analysis highlighted blaCTX-M as the most frequently appearing gene across networks of at least five genera. Particularly, Lactobacillus, Plesiomonas, and Ligilactobacillus demonstrated correlations with aadA, qnrA, blaCTX-M, intI2, and ISCR1. Based on 16S rRNA sequencing, the dominant phyla were Proteobacteria, Firmicutes, Bacteroidota, Acidobacteriota, and Actinobacteriota, with dominant genera including Pseudomonas, Ligilactobacillus, Azoarcus, Vogesella, Streptococcus, Plesiomonas, and Ferritrophicum. These findings enhance our understanding of ARG distribution in groundwater, signaling substantial contamination by ARGs and potential risks to public health. [ABSTRACT FROM AUTHOR]