Water Standards Research Articles

Investigation of particle size distribution and ultrafiltration of digestates from short-fibre residues in paper mills

ABSTRACT Industrial digestates from short-fibre residues, generated in paper recycling mills, are driving interest in resource recovery. This study aims to explore their potential for water recovery. Understanding particle dynamics aids in optimizing dewatering for digestate management. The particle size distribution in this study revealed significant fractions: <0.63 μm (6–20%), 0.63–20 μm (38–52%), and >20 μm (11–16%). Pre-treatment with Na4P2O7 and H2O2 enhances settling and lowers total dissolved solids (TDSs) but results in variation of size distribution. Additionally, this study investigates further water reuse in paper mills, focusing on the quality of ultrafiltration (UF) permeate obtained from the digestate of short fibres. UF permeate analysis reveals deviations from freshwater standards in paper mills. Despite effective TS removal, UF permeate falls short of paper mill water standards due to high TDSs, electrical conductivity, and nutrient concentrations, necessitating further downstream treatment with nanofiltration or reverse osmosis. A substantial reduction of permeate flux from 31 to 5 L/(m2·h) over the time indicated fouling and inefficient membrane wash. The silt density index of the UF membrane at 30 min registered 2.1, suggesting potential fouling. Further investigations on optimizing UF operations to enhance permeate flux and exploring alternative UF membranes are required.

The potential water quality impacts of hard-rock lithium mining: Insights from a legacy pegmatite mine in North Carolina, USA

The global green energy transition has spurred increased lithium exploration and extraction, yet the water quality impacts from lithium mining are understudied. This study investigates the potential water quality impacts from a legacy hard-rock lithium mine through comprehensive geochemical analyses of groundwater, surface waters, ore grade rocks, tailings, and waste rocks from a mine site in North Carolina, USA. The concentrations of regulated contaminants (e.g. As, Pb) in both groundwater and surface water emerging from the mine site were low, below drinking water and ecological standards. Yet Li (up to 46.8 mg/L), Rb (up to 169 μg/L), and Cs (up to 21 μg/L) were elevated relative to local background waters. Leaching experiments of the pegmatite ores, waste rocks, and tailing consistently demonstrate low mobilization of regulated contaminants and high leachability of Li, Rb, and Cs. Leaching experiments also reveal that water-rock interactions of the rocks and solid wastes from the mine site generate alkaline conditions, and that both phosphate and spodumene minerals are primary sources of Li and play a major role in formation of alkaline conditions during early stages of water-rock interactions. Over longer time scales, their direct impact on water quality is decreased. Given the global interest in hard-rock lithium mines, our findings highlight the potential occurrence of Li, Rb, and Cs in water resources adjacent to hard-rock lithium mines.

Off-grid photovoltaic-powered capacitive deionization for groundwater desalination in rural Africa

ABSTRACT In regions lacking centralized water supply and electricity grid connections, capacitive deionization (CDI) offers a promising approach with its modular and energy-efficient characteristics for low-salinity solutions. This research evaluates the feasibility of using a photovoltaic (PV)-powered CDI system as an off-grid, household-based water purification solution for groundwater desalination in rural Uganda. In this work, the CDI system was integrated with a PV system, comprising an ultrafiltration unit for pretreatment, a CDI stack for desalination, and a PV array for power supply. As evidenced by the performance analysis of the CDI stack in a single-pass mode, the system exhibited commendable desalination efficiency with a salt removal efficiency (>60%) and stable energy performance (0.110 ± 0.014 kWh/mol) observed under different influent conductivities (500–3,000 μS/cm). When applied to groundwater desalination, the CDI-based system successfully reduced the conductivity to meet Uganda's potable water standard (1,500 μS/cm), achieving a water recovery of 63%, and an energy consumption of less than 1.5 kWh/m3. Consequently, the CDI-based system effectively couples with the PV system to meet daily water needs solely through solar energy, demonstrating the practical implementation of innovative off-grid water desalination solutions in resource-constrained settings.

Deciphering the driving factors and probabilistic health risks of potentially toxic elements in arid surface water: Insights from the Tarim River Basin

Potentially toxic elements (PTEs) in surface water in arid areas pose a serious threat to environmental safety and human health within a basin. It is important to determine the factors controlling PTEs and to assess the likelihood that they will pose a risk to human health in order to support the development of environmental protection and risk management strategies. In this study, a structural equation model and Bayesian method were combined to discuss the distribution and probabilistic health risks of PTEs in surface water in arid area, and the Tarim River Basin was taken as a case study. The results show that the average concentrations of As, Co, Cu, and Ni in the surface water in the Tarim River Basin ranged from 0.04 to 2.92 μg/L, which do not exceed the international standard values. However, the maximum value of As (19.20 μg/L) exceeded both the recommended drinking water standards and the Chinese irrigation water standards. Spatially, the high As concentrations were distributed in the upper reaches of the Kashgar River, and the high Co, Cu and Ni concentrations were distributed in reservoirs and lakes on the main stream of the Tarim River. The concentrations of the PTEs in the surface water in the basin were not only affected by random anthropogenic factors such as traffic discharge, agricultural activities and mining industry, but were also directly and indirectly influenced by climatic factors. The results of the probabilistic health risk assessment showed that the 95th percentile the total hazard index for infants exceeded the allowable value of 1, and the total carcinogenic risk of PTEs exposure in four age groups was at the notable level. In this study, we conducted a comprehensive analysis of the controlling factors and health risks associated with PTEs in surface water in the Tarim River Basin, and the findings are expected to provide a scientific basis for regional water environment management and safety control.

Groundwater quality in Sargodha City, Pakistan: comprehensive research of geochemical modeling, groundwater quality assessment, and risk evaluation

Groundwater, an indispensable global resource, faces escalating contamination threats, jeopardizing human health and environmental sustainability. This study offers detailed insights into the quality of the groundwater, its drinking suitability, and associated human health risks in Sargodha City, Pakistan. Employing hydrogeochemical analysis, inverse geochemical modeling, groundwater quality index, and human health risk evaluation, this research highlights widespread exceedances of WHO drinking water standards, particularly in TDS, EC, TH, Na+, Ca2+, Mg2+, SO42−, Cl−, HCO3−, NO3-N, and As levels, signifying that a significant portion of the groundwater is unfit for consumption. Hydrochemical facies analysis reveals a dominance of the Na-Cl type. Water–rock interactions, cation exchange, and anthropogenic influences are the primary factors shaping groundwater hydrochemistry in the region. Saturation indices and inverse geochemical modeling demonstrated intricate geochemical processes involving both mineral precipitation and dissolution. Notably, the GWQI reveals a diverse spectrum of water quality, with 50% of the samples exhibiting excellent to good quality, 29% falling into the poor to extremely poor category, and 21% deemed unfit for drinking. Health risk assessment reveals alarming carcinogenic risks from As, affecting children (70.8%) and adults (83.35%), while 8.3% of the samples indicate non-carcinogenic risks. Conversely, NO3-N presents acceptable non-carcinogenic risks across all samples. The total hazard index spans between 0.14 and 1.90 for adults and 0.16 to 2.23 for children, underscoring the heightened vulnerability of children. This study advances the understanding of groundwater contamination dynamics in urbanized regions, offering insights to safeguard public health and ensure sustainable water management in areas with similar hydrogeochemical conditions.

Determination of seven phenoxy carboxylic acid herbicides in water using dispersive solid phase extraction coupled with ultra-high performance liquid chromatography-tandem mass spectrometry based on metal-organic framework composite aerogel

Phenoxy carboxylic acid herbicides (PCAs) are difficult to degrade and, thus, pose significant threats to the environment and human health. The limit for 2,4-dichlorophenoxyacetic acid is 30 μg/L in China's standards for drinking water quality, 70 μg/L in the United States' drinking water standards, and 30 μg/L in the World Health Organization's guidelines for drinking water quality. Therefore, the development of an effective detection method for trace PCAs in water is a crucial endeavor. Metal-organic frameworks (MOFs) are novel porous materials that possess advantages such as a large specific surface area, adjustable pore size, and abundant active sites. They exhibit excellent adsorption capability for various compounds. However, the applications of MOFs as adsorbents are limited. For example, the process of isolating powdered MOFs from aqueous solutions is laborious, and microporous MOFs exhibit limited surface affinity, which decreases their mass transfer efficiency in the liquid phase. MOF crystals can be embedded in a substrate to overcome these limitations. Aerogels are obtained by drying hydrogels, which are hydrophilic polymers with a three-dimensional crosslinked network structure. Spongy aerogel materials exhibit unique structural properties such as high porosity, large pore volume, ultralow density, and easy tailorability. When MOFs are combined with an aerogel, their efficient and selective adsorption properties are preserved. In addition, MOF aerogels exhibit a hierarchical porous structure, which enhances the affinity and mass transfer efficiency of the MOF for target molecules. At present, MOF aerogels are primarily prepared by freeze-drying or using supercritical carbon dioxide. These drying processes require significant amounts of energy and time. Hence, the development of greener and more efficient methods to prepare skeleton aerogels is urgently needed. In this study, we prepared an environment-friendly aerogel at ambient temperature and pressure without the use of specialized drying equipment. This ambient-dried MOF composite aerogel was then used for the dispersive solid phase extraction (DSPE) of seven PCAs from environmental water, followed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The key parameters affecting the efficiency of DSPE, including the extraction conditions, ratio of MIL-101(Fe)-NH2 to sodium alginate, pH of the aqueous samples, extraction time, ionic strength (salinity), and elution conditions, such as the elution solvent ratio, elution time, and elution volume, were investigated to obtain optimal extraction efficiency. The adsorbent could adsorb the target contaminants within 12 min, and the analytes could be completely desorbed within 30 s by elution with 4 mL of 1.5% (v/v) formic acid in methanol solution. The water samples could be analyzed without pH adjustment. The main adsorption mechanisms were electrostatic interactions and π-π conjugation. Thus, a new method based on MOF aerogels coupled with UHPLC-MS/MS was developed for the determination of the seven PCA residues in water. The calibration curves for the seven PCAs showed good linearity (r2≥0.9986), with limits of detection (LODs) and quantification (LOQs) ranging from 0.30 to 1.52 ng/L and from 1.00 to 5.00 ng/L, respectively. Good intra- and inter-day precision values of 6.5%-17.1% and 7.4%-19.4%, respectively, were achieved under low (8 ng/L), medium (80 ng/L), and high (800 ng/L) spiking levels. The developed method was applied to the detection of PCAs in surface water, seawater, and waste leachate, and the detected mass concentrations ranged from 0.6 to 19.3 ng/L. Spiked recovery experiments were conducted at mass concentrations of 8, 80, and 800 ng/L, and the recoveries ranged from 61.7% to 120.3%. The proposed method demonstrates good sensitivity, precision, and accuracy, and has potential applications in the detection of trace PCAs in environmental water.

The evaluation of bottled water quality compliance association formal and informal retailers in Gauteng municipality. South Africa

The quality of bottled water (BW) can vary based on factors such as handling, processing, transportation, hygiene practices, and the retail shop from which it is purchased. This study aimed to compare the microbiological quality of BW (Heterotrophic plate count (HPC), E.coli, and total coliforms (TC)) purchased from both formal and informal retail shops. The study used a convenience sampling approach and categorized the shops into formal and informal. A total of 117 samples were obtained, with 16 from informal shops and 101 from formal shops. The data was analysed using SPSS version 29, and the water quality compliance was assessed based on SANS 241, 1657, and World Health Organization standards for drinking water. The findings indicated a significant link between compliance with bottled water (BW) standards and the specific shop from which the BW was purchased (p 0.001). These results highlight shop compliance's crucial role in influencing BW's microbiological quality, especially in relation to total coliforms (TC) and E.coli presence. Bottled water obtained from informal shops did not meet the standards, whereas BW from formal shops adhered to the standards for TC and E.coli.

Synthesis of Acetylene‐Functionalized Schiff base for Selective Detection of Al(III) and Exploring Its Antibacterial Properties via In Silico and In Vivo Approach

AbstractThe identification of perilous metal ions and the treatment of diseases induced by microorganisms are critical areas requiring attention. We report herein the design and development of an acetylene‐functionalized Schiff base compound 4, using a low‐cost and straightforward approach. This compound 4 exhibits dual functions in the detection of harmful metal ions, particularly Al(III), as well as in the prevention of disorders caused by bacteria, specifically Staphylococcus aureus (S. aureus) and Bacillus subtilis (B. subtilis). It was well characterized through the utilization of diverse spectroscopic techniques, such as NMR (1H and 13C), FT‐IR, and mass spectrometry. Furthermore, the complete structure clarification of the Schiff base compound 4 was revealed through the utilization of X‐ray crystallography. The limit of detection (LOD) for Al(III) is 35.5 × 10−8 M, surpassing the WHO drinking water standard of 26.7 µM, underscoring the high sensitivity of compound 4. The antibacterial activity of compound 4 has also been effectively evaluated on Gram‐positive (S. aureus and B. subtilis) bacteria. Furthermore, compound 4 was docked to S. aureus and B. subtilis proteins, which represents outstanding outcomes with binding energies of −7.31 kcal/mol and −7.87 kcal/mol, respectively. The antibacterial activity of the compound 4 in both in vitro and docking studies suggests that it possesses the potential to serve as an antibacterial agent in the future.

ANALISIS KETERSEDIAAN DAN KEBUTUHAN AIR BAKU DISTRIK BONGGO KABUPATEN SARMI

The development of an area will cause the demand for water to continue to increase along with thepopulation growth rate. The fulfillment of food needs and the activities of the population are always closely relatedto the need for water. The demands are unavoidable but must be predicted and planned for optimal utilization.The tendency that often occurs is the imbalance between water availability and water demand. To achieve abalance between water demand and availability in the future, efforts are needed to assess the components of rawwater availability and demand as clean water sources. The source of clean water for the people of Bonggo District, Sarmi Regency, comes from borehole pumps,shallow wells (pumps), and rainwater. The analysis results on the need for domestic and non-domestic clean waterin the Bonggo District in 2023 show a total requirement of 210.38 liters/day or 0.0024 m3/second. The need forclean water is expected to increase by 2043, with the total requirement for domestic and non-domestic clean waterreaching 285,820 liters/day or 0.0033 m3/second. The availability and need for clean water sourced from rawwater that can be utilized as clean water comes from pump bore wells as a suitable raw water source. In terms ofquantity, it is available 24 hours a day and throughout the year. The investigation results of the pump bore wellraw water source meet the clean water quality requirements according to Government Regulation No. 82 of 2001,Level II. This is supported by groundwater, obtained through the analysis of geological conditions, land cover,morphology, and river flow, which have a high to very high groundwater potential score, located in the northernpart of Bonggo District. Economically, in terms of quantity, rainwater can be used as clean water due to its sufficientavailability, with high rainfall (104,775 mm/year) and year-round service (continuity), and in terms of quality, theresults of rainwater quality tests meet the clean water standards according to quality standards.

Hydrogeochemical Insights into the Sustainable Prospects of Groundwater Resources in an Alpine Irrigation Area on Tibetan Plateau

The Tibetan Plateau is the “Asia Water Tower” and is pivotal for Asia and the whole world. Groundwater is essential for sustainable development in its alpine regions, yet its chemical quality increasingly limits its usability. The present research examines the hydrochemical characteristics and origins of phreatic groundwater in alpine irrigation areas. The study probes the chemical signatures, quality, and regulatory mechanisms of phreatic groundwater in a representative alpine irrigation area of the Tibetan Plateau. The findings indicate that the phreatic groundwater maintains a slightly alkaline and fresh status, with pH values ranging from 7.07 to 8.06 and Total Dissolved Solids (TDS) between 300.25 and 638.38 mg/L. The hydrochemical composition of phreatic groundwater is mainly HCO3-Ca type, with a minority of HCO3-Na·Ca types, closely mirroring the profile of river water. Nitrogen contaminants, including NO3−, NO2−, and NH4+, exhibit considerable concentration fluctuations within the phreatic aquifer. Approximately 9.09% of the sampled groundwaters exceed the NO2− threshold of 0.02 mg/L, and 28.57% surpass the NH4+ limit of 0.2 mg/L for potable water standards. All sampled groundwaters are below the permissible limit of NO3− (50 mg/L). Phreatic groundwater exhibits relatively good potability, as assessed by the entropy-weighted water quality index (EWQI), with 95.24% of groundwaters having an EWQI value below 100. However, the potential health risks associated with elevated NO3− levels, rather than NO2− and NH4+, merit attention when such water is consumed by minors at certain sporadic sampling locations. Phreatic groundwater does not present sodium hazards or soil permeability damage, yet salinity hazards require attention. The hydrochemical makeup of phreatic groundwater is primarily dictated by rock–water interactions, such as silicate weathering and cation exchange reactions, with occasional influences from the dissolution of evaporites and carbonates, as well as reverse cation-exchange processes. While agricultural activities have not caused a notable rise in salinity, they are the main contributors to nitrogen pollution in the study area’s phreatic groundwater. Agricultural-derived nitrogen pollutants require vigilant monitoring to avert extensive deterioration of groundwater quality and to ensure the sustainable management of groundwater resources in alpine areas.

Main spatial-temporal regularities of the state of the chemical composition of groundwater of the oligocene aquifer in the Shaim oil and gas bearing area

The constantly growing need for fresh water in the Shaim oil and gas region necessitates the exploration of new areas and the development of measures to improve the operation of water intakes. To predict the quality of groundwater, which is an operational parameter of the aquifer aquifer, it is needed up-to-date information on the chemical composition of ground-water. The aim of this study to identify main spatial-temporal regularities of the state of the chemical composition of groundwater of the oligocene aquifer in the Shaim oil and gas bearing area, compared to average values from adjacent areas. Research methods include the systematization of laboratory data on water samples, analysis of groundwater chemistry, and mapping of the main spatial-temporal patterns in component concentration changes. The average values of chemical composition indicators in the studied area are similar to those of neighbouring areas, with some indicators exceeding drinking water standards. Similarities are observed in the variability of the chemical composition, spatial patterns of changes in most chemical indicators, and the presence of areas with extreme values. Current data on the chemical composition of the oligocene aquifer ground-water, including key characteristics and spatial-temporal trends presented in distribution maps, can be used in designing groundwater intakes and forecasting long-term groundwater quality.

Sequential novel use of Moringa oleifera Lam., biochar, and sand to remove turbidity, E. coli, and heavy metals from drinking water

This research investigates the individual and combined use of Moringa oleifera (MO) Lam., biochar, and sand to remove turbidity, pathogens, and heavy metals from drinking water. Contaminated water was synthetically prepared using kaolin, standard nickel/lead solutions, and Escherichia coli (E. coli). The optimal dose of MO seed protein, extracted in 1 M NaCl solution, was determined using a jar test flocculator. MO treatment reduced water turbidity from 200 to 4 NTU and achieved a 1–2 log reduction in E. coli from an initial count of 1×105 CFU/ml. Nevertheless, no significant reduction in nickel and lead concentrations was noted. Subsequently, the MO-treated water was passed through a biochar column supported on a sand bed, revealing clear water with 1 NTU turbidity and no trace of E. coli counts being detected. The sequential process of using biochar and sand reduced nickel and lead by 97.5 % and 99.3 %, respectively. The physicochemical properties of the treated water met WHO and UK standards for safe drinking water. All experiments were performed in duplicates (n=2; P < 0.05). The scalability and economic feasibility of the project, the mechanism of removal of contaminants by MO and biochar, and the study's limitations are also discussed.

The Safe Drinking Water Act at 50: Another Identity Crisis

Key TakeawaysThe Safe Drinking Water Act (SDWA) of 1974 (amended in 1986, 1996, and 2018) shows the tension between purity and safety, cost and benefits, and balancing risks, down to today's policy debates.Following the 1996 amendments, regulatory successes include arsenic, radionuclides, filter backwash recycling, total coliform, disinfectants and disinfection byproducts, and enhanced surface water treatment.With recent drinking water standards, such as the 2024 per‐ and polyfluoroalkyl substances rule, based on very low detection levels, the SDWA continues to generate intense public dialogue.

Construction of PTFE/PI-PI/PANI-PA composite nanofibrous membrane for efficient photothermal membrane distillation and VOCs interception

Water-soluble volatile organic compounds (VOCs) are one of the difficult substances in seawater and industrial wastewater treatment. Photothermal membrane distillation (PMD) technology has great advantages in solving the problems of low energy conversion efficiency and serious pollution of traditional membrane distillation (MD) technology, but it still faces the challenge that VOCs cannot be effectively removed.To solve this problem, we prepared photothermal Polytetrafluoroethylene/Polyimide-Polyimide/Polyaniline-Polyamide (PTFE/PI-PI/PANI-PA) composite membranes with VOCs interception. The composite membrane was fabricated by applying the previously studied PTFE/PI-PI/PANI/PANI membrane by interfacially polymerising an ultrathin PA layer with controllable pore sizes. Among them, the PTFE/PI-PI/PANI base membrane in the composite membrane not only provides strong support and durability as a backbone structure, but the PANI photothermal layer also provides photothermal conversion for effective PMD operation. In addition, the ultra-thin PA layer acts as a molecular sieve separator to effectively intercept VOCs in the feed solution. When the feed solution was 35 g⋅L−1 NaCl, the average permeate flux of the #M-PA-0.1 membrane was 1.44 ± 0.02 L⋅m−2⋅h−1 with a salt interception rate of 99.99 % or more after 80 h of PMD testing. Meanwhile, when 50 mg⋅L−1 of VOCs was added to the feed solution, the VOCs retention rate >99.35 %, and the concentration of VOCs on the permeate side was much lower than the corresponding concentration in the drinking water standards recommended by the World Health Organisation (WHO) and the US Environmental Protection Agency (EPA). This study effectively combines the molecular sieve effect with the solar-powered evaporation process, which provides a research basis for the preparation of high-performance PMD membranes that can effectively remove volatile organic compounds.

Green synthesis of nanoscale zero-valent iron impregnated walnut shell biochar as efficient adsorbent for metal(loid)s purification: Performance and mechanism insight

The escalation of metal(loid) contamination in global water poses severe risks to ecological environment safety. Meeting the ‘pollution control with waste’ strategy, we utilized eco-friendly waste tea leaf extract and walnut shell to first fabricate a greenly synthesized nanoscale zero-valent iron impregnated walnut shell biochar (G-nZVI/WSB) for the simultaneous sequestration of cadmium (Cd), lead (Pb), and arsenic (As) from aqueous systems. Since the interactions among these metal(loid)s during adsorption on G-nZVI/WSB and their corresponding mechanisms remain unclear, we conducted a series of batch experiments coupled with characterization techniques. The optimal pyrolysis temperature and Fe/C ratio for G-nZVI/WSB were determined to be 650 °C and 20 %, respectively. Under optimal conditions (contact time = 24 h, pH = 6), G-nZVI/WSB exhibited theoretical maximum adsorption capacities for Cd(II), Pb(II), and As(III) of 52.96, 135.1, and 8.414 mg g−1, respectively, which were significantly higher than those of WSB carrier. In single and combined systems, the monolayer and chemical adsorption of metal(loid)s were predominant, with their competitive affinity for active sites following the order of Pb(II) > Cd(II) > As(III). Characterization analyses using FTIR, SEM, XRD, and XPS confirmed the specific adsorption mechanisms of G-nZVI/WSB for these metal(loid)s, including cation-π interactions, coprecipitation, oxidation, and coordinated complexation. Notably, G-nZVI/WSB exhibited excellent adsorption stability over five cycles of adsorption-desorption, which achieved the efficient purification of multi-contaminated actual wastewaters to meet the standards for wastewater discharge or drinking water. These findings demonstrate the significant potential of G-nZVI/WSB as an eco-friendly and promising nanocomposite for treating metal(loid)-contaminated wastewater.

Enhancing low-level tritium detection in environmental waters: assessing the Hidex ULLA liquid scintillation counter

Tritium (³H) is a vital tracer in isotope hydrology and environmental studies, necessitating accurate and precise low-level detection methods. This study evaluated the performance of the new Hidex ULLA Liquid Scintillation Counter for ultra-low-level tritium assays in environmental water samples. The optimization of instrumental parameters enabled accurate and reproducible 3H measurements. Test samples (10–132 TU) were analyzed in triplicate, including 3H-free water and NIST traceable standards. The results demonstrated excellent accuracy and reproducibility, as evidenced by Zeta scores and linearity across these tritium concentrations. The system's stability over extended measurement time periods ensured reliable performance for routine ultra-low level 3H analysis. The optimization of key parameters such as coincidence time and region of interest (ROI) achieved the highest figure of merit (FoM) by using a 25 ns coincidence time and the DigPb open mode for optimal spectral fittings. Detection limits (DL) based on ISO11929 recommendations were significantly improved but highlighted the need for sample enrichment for most low-level environmental applications, with LSC counting times preferably exceeding 1000 min. Overall, the Hidex ULLA Liquid Scintillation Counter proved to be a robust and reliable instrument suitable for ultra-low-level tritium detection in environmental water samples.

Nitrate source analysis of underground drinking water sources in Zhangjiakou main urban area and its health risk assessment

&lt;p style="line-height:200%;text-align:justify;text-justify:inter-ideograph;"&gt;&lt;span lang="EN-US"&gt;In order to investigate the main pollution factors of underground drinking water sources in semi-arid agricultural areas in China, and to reveal the threatening influence of pollutants on the normal water security of local society. Single-factor evaluation index, principal component analysis, basic data statistics are used to clarify the main pollution indicators of underground drinking water sources in Zhangjiakou main city and discuss the main influencing factors of the change of their pollution concentration, and evaluate the degree of health threat of its pollution to the drinking water of local residents. The results show that: the water sources of Taobeiying and Gushi are deeply affected by human activities, and nitrate, as the only exceeding substance under drinking water standards, is the most important indicator of groundwater pollution; and the nitrate con-centration of groundwater is higher in the pasture and nearby agricultural activities; nitrate contamination levels in groundwater are within the health acceptability range for the vast majority of the population, with only newborns in the Taobeiying drinking water source being exposed to a non-carcinogenic risk of nitrate. The results of the study will help to maintain a stable groundwater environment.&lt;/span&gt;&lt;/p&gt;

Ecological perspectives of endemic fish species under cascade hydropower development

Wang Y, Wang Q, Zhang W, Wang N, Cong N, Kattel G, Qi Y, Yao W. 2024. Ecological perspectives of endemic fish species under cascade hydropower development. Lake Reserv Manag. XXX–XXX. The upstream Lancang River basin (in Tibet) offers rich hydropower resources together with some of the most delicate freshwater fish species diversity in the world. However, a large dam construction scheme throughout the basin has threatened the fish species diversity and ecology. Our study focuses on the extent to which hydropower construction in the basin influences the river’s ecological status, including the aquatic environment, fish migration, and fish spawning sites. We surveyed the water quality, fish distribution, and fish spawning sites and estimated the fish spawning capacity in the basin. Our results indicate that the water quality prior to dam construction would meet China’s water standards. However, water quality would decline significantly following dam construction, exacerbating the rate of loss of 7 of the protected endemic fish species, as well as threatening the habitat of several other fish species. Our analysis shows a loss trend of fish populations and spawning capacity after damming the river. Cascade dams constructed in the upstream Lancang River basin would obstruct natural migration of fish and inundate their spawning sites, causing reproductive failure and population decline. Based on our analysis, and eco-hydraulic engineering principles, we recommend several ecological protection measures and management options in the upstream Lancang River basin, including the construction of artificial fish ladders, the implementation of ecological regulation, and a fish strategy that will reduce the negative effect of cascade dam constructions.

Assessment of the Bacteriological Quality of Drilling Water in the 8th District of the City of N'Djamena (Chad)

Study is to evaluate the bacteriological quality of borehole water consumed by residents of the 8th district of the city of N'Djamena. Twenty (20) samples were taken and sent to the National Water Laboratory for the research of microbiological parameters. Four microbiological parameters were evaluated: Total coliforms, Escherichia coli, Fecal enterococcus and Salmonella spp. The technique used for this analysis is spreading and membrane filtration. The average values obtained in the samples are 0.338 10 4 CFU/100 ml for total coliforms, 0.319 10 3 CFU/100 ml for Escherichia coli, 33.33 CFU/100 ml for fecal Enterococcus and 1.385 10 4 CFU/100 ml Salmonella spp . The results of these analyses, considering the tolerance threshold set by the drinking water standards in Chad, showed that these averages largely exceed the recommended standards for drinking water. These waters must be treated and the environments of water points improved for consumption without impact.

Hydro-geochemistry and age-dependent health risk assessment of nitrate, nitrite, and fluoride in health facilities water: a multivariate analysis.

Groundwater from alluvial fan plains is the prevailing water source, especially for arid/semiarid regions, but its contamination poses substantial risks to water supply and public health. The recent study aims to assess the hydro-geochemistry, distribution, and potential health risks of NO3-, NO2-, and F- concentrations in the groundwater of previously unexplored health facilities in District Vehari, Punjab, Pakistan. In total, 75 groundwater samples were evaluated for NO3-, NO2-, and F- levels as well as pH, EC, TDS, CO32-, HCO3-, Cl-, Na+, Fe, K+, Ca2+, Mg2+, taste, odor, color, and turbidity. The Durav graph shows that the water type is Na-HCO3-Ca, with Na and HCO3 dominant, weak acids > strong acids, and alkaline ions > alkalis. Results revealed that drinking water samples (21.73% and 20%) taken from Tehsil Mailsi, and the Basic Health Unit (BHU) exceeded the WHO standard (1.5mg/L) for F- concentration, respectively. Moreover, the mean chronic daily intake (CDI) of F- was 0.044, 0.018, and 0.02mg/kg/day in children, men, and women, respectively. Similarly, the average CDI of NO3- was 0.113, 0.046, and 0.050 in children, men, and women, respectively, and the respective values of NO2- were 0.004, 0.001, and 0.001. The NO2- shows a significant range of hazard quotient (HQ) (0.0-1.172) in children. The range of HQ for F- was 0.0-3.114, 0.0-1.290, and 0.0-1.389 in children, men, and women, respectively. Additionally, the health risks analysis revealed an HQ > 1.0 for children in groundwater, indicating a potential carcinogenic risk from the F-. Pearson correlation and PCA analysis found a significant positive correlation (0.8) between NO3- and NO2- and a negative correlation (0.3) between F- and HCO3-. These findings highlight the need for groundwater treatment in healthcare facilities prior to water consumption. Enforcing international and national drinking water standards in healthcare units is vital to strengthening services and providing equitable access to safe drinking water. Legislative and efficient water management measures must be taken for the protection of public health.