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Metagenomic analysis typically includes read-based taxonomic profiling, assembly, and binning of metagenome-assembled genomes (MAGs). Here we integrate these steps in Read Annotation Tool (RAT), which uses robust taxonomic signals from MAGs and contigs to enhance read annotation. RAT reconstructs taxonomic profiles with high precision and sensitivity, outperforming other state-of-the-art tools. In high-diversity groundwater samples, RAT annotates a large fraction of the metagenomic reads, calling novel taxa at the appropriate, sometimes high taxonomic ranks. Thus, RAT integrative profiling provides an accurate and comprehensive view of the microbiome from shotgun metagenomics data. The package of Contig Annotation Tool (CAT), Bin Annotation Tool (BAT), and RAT is available at https://github.com/MGXlab/CAT%5fpack (from CAT pack v6.0). The CAT pack now also supports Genome Taxonomy Database (GTDB) annotations. Metagenomic taxonomic profiling usually relies either on reads or assembled contigs/MAGs. Here, authors present RAT, a tool that integrates taxonomic signals from reads, contigs, and MAGs into one profile with high precision and sensitivity. RAT provides a comprehensive view of the microbiome. [ABSTRACT FROM AUTHOR]

The study aims to understand the hydrochemical characteristics and groundwater suitability for agricultural and drinking purposes. For this purpose, 21 groundwater samples were collected, and major physicochemical parameters such as pH, EC, TDS, temp, salinity, Ca2+, Mg2+, Na+, K+, HCO3−, Cl−, and SO42− were analyzed, followed by the standard analytical procedures. Different groundwater quality graphical representations were constructed by using Aqua Chem software. The results indicate groundwater samples were alkaline with fresh to moderate saline in nature, sixty-eight percent of the samples were suitable for drinking in accordance with WHO, and thirty-two percent of the samples were unsuitable due to the excess amount of different ionic concentrations derived from natural and various anthropogenic sources. Irrigation water quality parameters such as SAR, EC, PI, Na %, RSBC, MR, and KR were used to understand the irrigation suitability. The US salinity diagram exemplifies that most groundwater samples fall in the C3S1 category with high salinity hazard and low alkali hazard. The Wilcox plot reveals that 80% of the samples were found under very good to permissible limits, and few samples fall with doubtful to unsuitable quality due to the excess amount of alkali and salinity. Permeability index values show that groundwater is suitable for irrigation. Three major hydrochemical facies were identified with the dominance order of mixed CaMgCl, NaCl, and CaCl. Gibb's plot suggests that evaporation and rock-water interaction are the dominant natural mechanisms controlling the groundwater chemistry in the present study area. [ABSTRACT FROM AUTHOR]

This study focused on analyzing the contamination status of groundwater around an oil depot in Fuxin by considering physicochemical indexes, potentially toxic elements (PTEs), and organic substances with reference to relevant standards. The hazard analysis using the Nemero contamination index and potential ecological hazard index method, aimed at determining the levels of PTEs and organic contaminants in the groundwater, revealed a mild ecological risk in the study area. A redundancy analysis-geographic information system employed to uncover the sources of PTEs in groundwater samples revealed two main components: the first comprised Cd, Zn, Mn, and Pb, which were mainly of anthropogenic origin (oil reservoir leakage), and the second component includes Cr, Hg and As, which may originate from anthropogenic and geological sources. Evaluation of the carcinogenic and noncarcinogenic risks associated with PTEs indicated high levels of the former in the study area. Finally, the correlation between organic pollutants and environmental factors and the natural attenuation trend was explored. This exploration aimed to provide a reference for groundwater contamination investigation, formulation for contamination prevention and control strategies in relevant demolition areas, and theoretical guidance and technical support for subsequent analysis and monitoring of field data. Highlights: Organic pollutants in the study area are below the standard values; Groundwater around the study area falls under mild ecological hazard; Clarify contamination risk around the oil depot and potential toxic element sources; Determine the effect of natural attenuation on decreasing pollutant concentration. [ABSTRACT FROM AUTHOR]

The present study was conducted to evaluate the concentration of arsenic in groundwater in Bhakkar district, Western Punjab Province, Pakistan. To analyze hydrochemical characteristics, 68 groundwater samples from various water schemes in four tehsils were taken. While most of the samples’ concentrations of major cations and anions were within the WHO’s maximum allowed range, almost 44% had higher arsenic levels than what was considered acceptable for drinking water. Gibbs diagrams were used to show how groundwater chemistry is affected by the dominance of rocks and evaporation crystallization. An investigation of the Indus River’s lateral distribution and upstream to downstream locations’ arsenic concentrations showed variability. According to the Health Risk Assessment (HRA), samples from Bhakkar tehsil (73.3%), Darya Khan tehsil (60%), and Kalur Kot tehsil (13.3%) all surpassed the hazard quotient level of “1,” whereas all samples from Mankera tehsil were within acceptable bounds. The hazard quotient numbers displayed a range of 0.038–5.127, with an average of 1.149 – suggesting that a considerable portion of people consuming water laden with high levels of arsenic may suffer from non-cancerous health complications. Moreover, the carcinogenic risk values were as high as 2.31 × 10−3, implying a heightened danger of cancer over the long term due to arsenic-contaminated water. It was determined that Bhakkar tehsil had the highest quantity of arsenic among the tehsils in the Bhakkar district, making the groundwater unfit for drinking. [ABSTRACT FROM AUTHOR]

Fluoride and nitrate enriched groundwater are potential threats to the safety of the groundwater supply that may cause significant effects on human health and public safety, especially in aggregated population areas and economic hubs. This study focuses on the high F– and NO3– concentration groundwater in Tongzhou District, Beijing, North China. A total of 36 groundwater samples were collected to analyze the hydrochemical characteristics, elucidate genetic mechanisms and evaluate the potential human health risks. The results of the analysis indicate: Firstly, most of the groundwater samples are characterized by Mg‐HCO3 and Na‐HCO3 with the pH ranging from 7.19 to 8.28 and TDS with a large variation across the range 471–2337 mg/L. The NO3– concentration in 38.89% groundwater samples and the F– concentration in 66.67% groundwater samples exceed the permissible limited value. Secondly, F– in groundwater originates predominantly from water‐rock interactions and the fluorite dissolution, which is also regulated by cation exchange, competitive adsorption of HCO3– and an alkaline environment. Thirdly, the effect of sewage disposal and agricultural activities have a significant effect on high NO3– concentration, while the high F– concentration is less influenced by anthropogenic activity. The alkaline environment favors nitrification, thus being conducive to the production of NO3–. Finally, the health risk assessment is evaluated for different population groups. The results indicate that high NO3– and F– concentration in groundwater would have the largest threat to children's health. The findings of this study could contribute to the provision of a scientific basis for groundwater supply policy formulation relating to public health in Tongzhou District. [ABSTRACT FROM AUTHOR]

Heilongdong Spring Basin (HSB) is an ecologically and economically important area in northern China, with widespread and intensive anthropogenic activities (industrialization, mining, agriculture). To understand the hydrogeochemical characteristics and water quality status of groundwater in various aquifers, 33 groundwater samples were collected and analyzed by Piper diagram, Gibbs diagram, Entropy-Weighted Quality Index (EWQI) and Hierarchical cluster analysis (HCA) in the area. The results indicated that the groundwater was mainly derived from meteoric water, and rock weathering was the dominant source of ions in the area. The majority of the karst groundwater samples (KGWs) fell in the category of HCO3-Ca·Mg and HCO3·SO4-Ca·Mg, the hydrochemical faces of pore groundwater (PGWs) and fissure groundwater (FGWs) samples were mainly SO4·HCO3-Ca type with a few of the HCO3·SO4-Ca·type. According to the EWQI, all the KGWs were within the EWQI of below 100 and were suitable for drinking, while the central and eastern parts of regions have elevated EWQI values, especially 3 samples of KGWs were within the EWQI value in the range of 83–95, closing to the "poor" bracket. In addition, 66.7% of FGWs and all the PGWs were unsuitable for drinking. The HCA results showed that local groundwater quality was mainly controlled by geogenic processes and anthropogenic factors. Especially, the shallow groundwater was more affected by anthropogenic activities. Moreover, it was worth noticing that a few karst groundwater samples were close to shallow groundwater samples, which might be related to coal mining and agricultural activities. The present results provide a scientific basis for the protection and utilization of groundwater in different aquifers. [ABSTRACT FROM AUTHOR]

A hydrogeochemical appraisal of groundwater in the Banas river basin area in North West India was carried out to determine its quality and appropriateness for domestic uses. In addition, the objective of the study is to enumerate the effects of geological and human factors on groundwater chemistry in the research area. A total of 38 groundwater samples were gathered and analyzed for the determination of pH, EC, TDS, TH, main cations, and anions. The findings revealed that groundwater is alkaline, fresh to brackish, and very hard in nature; moreover, in the majority of groundwater samples, the physicochemical parameters like EC, TH, Ca2+, Mg2+, HCO3−, and Cl− were found to be exceeded to their threshold levels as prescribed for drinking purposes. According to the groundwater quality index, 73.68 and 26.32% of the groundwater samples are classified as good and poor types of groundwater, respectively. According to Piper and Chadha's diagrams, the bulk of groundwater samples are mixed type (Ca. Mg-Cl), followed by Na-Cl and Ca.Mg-HCO3 types, which indicated a shift from pure recharge water to saline water via mixed type water. Alkaline earths outperformed alkalis, and strong acid anions outperformed weak acid anions in the groundwater of the basin. Furthermore, Na+, and Cl− and HCO3− were found to be dominated among the cations and anions, respectively, in water samples, and Gibbs diagrams evidenced that hydrochemistry of water is primarily regulated by rock-water interaction and evaporation processes, while graphical and inter-ionic plots, molar ionic ratios, correlation analysis study, chloro-alkaline indices (CAI), and saturation indices (SI) revealed that the chemical constitution of groundwater is regulating by rock weathering, mineral dissolution, ion exchange, and evaporation, as well as anthropogenic activities. [ABSTRACT FROM AUTHOR]

The effect of the simultaneous presence of fluoride (0.15–1.2 mg L−1), bicarbonates (83.6–596 mg L−1), and synthesized goethite (0.3 mg L−1) at typical concentrations often found in groundwater samples was evaluated on the degradation of 2,4‐dichlorophenoxyacetic acid (2,4‐D) at pH 6.9 under simulated sunlight irradiation (300 W m−2) and H2O2 concentrations of 10 mg L−1. The 2,4‐D removal was strongly enhanced by the presence of fluoride. F− could modify the surface of iron (hydr)oxide, leading to the formation of surface Fe–F bonds benefiting the formation of free •OH, producing upward band bending, reducing the electron‐hole recombination, and enhancing the electron transfer to H2O2. On the other hand, bicarbonate may react with •OH generating CO3−• species that could participate in pollutant oxidation, while solar light‐induced H2O2 photolysis also played an important role in removing 2,4‐D. These findings suggest that tuning of iron (hydr)oxides by fluoride could take place in real groundwater, generating photocatalysts with a high activity that could participate, by adding H2O2, in the enhancement of sunlight photoinduced natural abiotic processes for pollutant abatement. [ABSTRACT FROM AUTHOR]

Groundwater contamination has increased in several Indian states in recent years. Very few studies were reported from Himalayan region. Thus, this study is being conducted in the district Kullu of Himachal Pradesh to analyse groundwater quality assessment in selected samples. The study aimed to analyse groundwater pH, TDS, arsenic levels and analyse water quality parameters based on depth and altitude. A total of 106 groundwater samples were taken from the Kullu district at an elevation range of 747-2368 meter. Depth of borewell's was 40-300 feet, covering all seven blocks and examined for pH, TDS, and arsenic levels. Arsenic level were analysed through Field Test Kits of Merck using standard protocol. Statistical analysis was done using GraphPad Prism 5. The mean pH was 7.841±0.3268, mean TDS was 302.9±127.7 mg/L and mean arsenic level was 5.104±6.005 μg/L, which were within permissible limits. Maximum TDS was 710 mg/L, found from tehsil Bhuntar. 9.433% of samples had TDS levels above prescribed limits of 500 mg/L. Maximum arsenic level was 50 μg/L found in Anni. 4.716% samples were above prescribed limits of 10 μg/L for arsenic levels. The highest depth measured was 300 feet, with an average depth level of 132.6±61.70 feet. High arsenic levels were found below 100 feet of depth and altitude were above 1300 m above mean sea level. In conclusion, since Himalayan groundwater is considered safe, it is degrading at an alarming rate since 4.71% samples was analysed above permissible limit of arsenic, which may be due to geogenic causes and may lead to serious health consequences in future. As a result, groundwater must be monitored on a frequent basis and large scale analysis will be needed. [ABSTRACT FROM AUTHOR]

Porous sandstone geothermal water is an important geothermal resource, which is a low-carbon and clean resource, but lacks systematic research on a regional scale. The northern part of Jinan City is rich in geothermal resources, specifically porous sandstone thermal reservoirs. However, there is still incomplete research on the mechanism of geothermal genesis and the hydrochemical characteristics of geothermal water in porous sandstone. This study aims to address this gap by collecting 21 groundwater samples from northern Jinan and comparing their conventional ion and isotope characteristics to investigate the hydrochemical characteristics during the formation of geothermal water and uncover the genesis mechanism of porous sandstone geothermal water. The results indicate that the geothermal water is classified as Na-Cl type and Na-SO4-Cl type. The hydrochemical characteristics of geothermal water are primarily influenced by water–rock interaction and groundwater mixing. The water source primarily comes from the atmospheric precipitation in the Taiyi mountains, with an altitude of 910.75–1542.2 m.s.a.l.. The estimated temperature of the thermal reservoir ranges from 51 to 78 °C, and the depth of geothermal water circulation is estimated to be between 1316 and 2216 m. Based on the characteristics of the geothermal field, including the "cap rock, water source, heat source, reservoir, and channel," a conceptual model of the porous sandstone geothermal water flow system is proposed. This model offers novel insights into the genesis mechanism of geothermal water under similar geological conditions. [ABSTRACT FROM AUTHOR]

Hydrogeological, hydrochemical and isotopic traits of the groundwater in the Quaternary aquifer system in an urban-periurban locality within and encircling the Kolkata-Howrah twin city in the south Bengal Basin have been synthesised to explain the present- and paleo-hydrological processes, surface and groundwater interaction and mixing dynamics of contamination of groundwater. Rock-weathering, evaporation, ion-exchange and active mineral dissolution are the key processes commanding the groundwater chemistry. Freshwater flushing from the recharge zones had thinned the entrapped sea water which has generated the present-day brackish water by a non-uniform fusion. The best-fit line of the plots of δD and δ18O of groundwater samples displays a slope lower than that of local meteoric water line (LMWL) and global meteoric water line (GMWL) which hints that isotopic constitution of the groundwater of the present area is primarily formed by evaporation before or in the recharging process. A wide range of δ18O values in groundwater suggests that these waters are not blended enough to remove dissimilarities in isotope configuration of recharge water. This also suggests that many groundwaters are a result of mixing of present-day recharge and an older integrant recharged under previously cooler climatic conditions. The groundwater samples are more depleted of oxygen at the shallower level. The depleted samples cluster around the Tolly's nala (canal) where upper aquitard is missing or < 10-m thick. The tritium values range between 0.70 and 15.02 which indicate the occurrence of 'sub-modern', 'a mix of modern and sub-modern water' and 'modern water'. It indicates mingling of isotope-depleted water from the Hugli River by means of Tolly's canal with relatively less-depleted groundwater of Kolkata's late Pleistocene aquifer. The tritium values and Cl/Br ratio of groundwater samples adjoining Tolly's canal and elsewhere refer the direct infiltration of 'modern wastewater and freshwater' which mixes with the 'sub-modern water' in the aquifer system. [ABSTRACT FROM AUTHOR]

Volcanic aquifers have become valuable resources for providing water to approximately 2.5 million people in the Yogyakarta-Sleman Groundwater Basin, Indonesia. Nevertheless, hydrogeochemical characteristics at the basin scale remain poorly understood due to the complexity of multilayered aquifer systems. This study collected sixty-six groundwater samples during the rainy and dry seasons for physicochemical analysis and geochemical modeling to reveal the hydrogeochemical characteristics and evolution in the Yogyakarta-Sleman Groundwater Basin. The results showed that groundwater in the unconfined and confined aquifers exhibited different hydrogeochemical signatures. The Ca–Mg–HCO3 facies dominated groundwater from the unconfined aquifer. The groundwater facies evolved into a mixed Ca–Mg–Cl type along the flow direction towards the discharge zone. Meanwhile, groundwater from the confined aquifer showed mixed Ca–Na–HCO3, Na–HCO3, and Na–Cl–SO4 facies. The presence of Mg in the confined aquifer was replaced by Na, which was absorbed in the aquifer medium, thus showing the ion exchange process. The main geochemical processes can be inferred from the Gibbs diagram, where most groundwater samples show an intensive water–rock interaction process mainly influenced by the weathering of silicate minerals. Additionally, only groundwater samples from the confined aquifer were saturated with certain minerals (aragonite, calcite, and dolomite), confirming that the groundwater followed the regional flow system until it had sufficient time to reach equilibrium and saturation conditions. This study successfully explained the hydrogeochemical characteristics and evolution of a multilayer volcanic aquifer system that can serve as a basis for groundwater basin conservation. [ABSTRACT FROM AUTHOR]

Assessing groundwater geochemical formation processes and pollution circumstances is significant for sustainable watershed management. In the present study, 58 shallow groundwater samples were taken from the Dongwen River Basin (DRB) to comprehensively assess the hydrochemical sources, groundwater quality status, and potential risks of NO3– to human health. Based on the Box and Whisker plot, the cation's concentration followed the order of Ca2+ > Mg2+ > Na+ > K+, while anions' mean levels were HCO3− > SO42− > NO3− > Cl−. The NO3− level in groundwater samples fluctuated between 4.2 and 301.3 mg/L, with 67.2% of samples beyond the World Health Organization (WHO) criteria (50 mg/L) for drinking. The Piper diagram indicated the hydrochemical type of groundwater and surface water were characterized as Ca·Mg-HCO3 type. Combining ionic ratio analysis with principal component analysis (PCA) results, agricultural activities contributed a significant effect on groundwater NO3−, with soil nitrogen input and manure/sewage inputs also potential sources. However, geogenic processes (e.g., carbonates and evaporite dissolution/precipitation) controlled other ion compositions in the study area. The groundwater samples with higher NO3− values were mainly found in river valley regions with intense anthropogenic activities. The entropy weight water quality index (EWQI) model identified that the groundwater quality rank ranged from excellent (70.7%) and good (25.9%) to medium (3.4%). However, the hazard quotient (HQ) used in the human health risk assessment (HHRA) model showed that above 91.38% of groundwater samples have a NO3− non-carcinogenic health risk for infants, 84.48% for children, 82.76% for females, and 72.41% for males. The findings of this study could provide a scientific basis for the rational development and usage of groundwater resources as well as for the preservation of the inhabitants' health in DRB. [ABSTRACT FROM AUTHOR]

The qualitative and quantitative assessment of groundwater is one of the important aspects for determining the suitability of potable water. Therefore, the present study has been performed to evaluate the groundwater quality for Achhnera block in the city of Taj, Agra, India, where groundwater is an important water resource. The groundwater samples, 50 in number were collected and analyzed for major ions along with some important trace element. This study has further investigated for the applicability of groundwater quality index (GWQI), and the principal component analysis (PCA) to mark out the major geochemical solutes responsible for origin and release of geochemical solutes into the groundwater. The results confirm that, majority of the collected groundwater samples were alkaline in nature. The variation of concentration of anions in collected groundwater samples were varied in the sequence as, HCO3− > Cl− > SO42− > F− while in contrast the sequence of cations in the groundwater as Na > Ca > Mg > K. The Piper diagram demonstrated the major hydro chemical facies which were found in groundwater (sodium bicarbonate or calcium chloride type). The plot of Schoellar diagram reconfirmed that the major cations were Na+ and Ca2+ ions, while in contrast; major anions were bicarbonates and chloride. The results showed water quality index mostly ranged between 105 and 185, hence, the study area fell in the category of unsuitable for drinking purpose category. The PCA showed pH, Na+, Ca2+, HCO3− and fluoride with strong loading, which pointed out geogenic source of fluoride contamination. Therefore, it was inferred that the groundwater of the contaminated areas must be treated and made potable before consumption. The outcomes of the present study will be helpful for the regulatory boards and policymaker for defining the actual impact and remediation goal. [ABSTRACT FROM AUTHOR]

Studies of the effects of volcanic activity on the Hawaiian Islands are extremely relevant due to the past and current co‐eruptions at both Mauna Loa and Kīlauea. The Big Island of Hawaiʻi is one of the most seismically monitored volcanic systems in the world, and recent investigations of the Big Island suggest a widespread subsurface connectivity between volcanoes. Volcanic activity has the potential to add mineral contaminants into groundwater ecosystems, thus affecting water quality, and making inhabitants of volcanic islands particularly vulnerable due to dependence on groundwater aquifers. As part of an interdisciplinary study on groundwater aquifers in Kona, Hawaiʻi, over 40 groundwater wells were sampled quarterly from August 2017 through March 2019, before and after the destructive eruption of the Kīlauea East Rift Zone in May 2018. Sample sites occurred at great distance (~80 km) from Kīlauea, allowing us to pose questions of how volcanic groundwater aquifers might be influenced by volcanic subsurface activity. Approximately 400 water samples were analyzed and temporally split by pre‐eruption and post‐eruption for biogeochemical analysis. While most geochemical constituents did not differ across quarterly sampling, microbial communities varied temporally (pre‐ and post‐eruption). When a salinity threshold amongst samples was set, the greatest microbial community differences were observed in the freshest groundwater samples. Differential analysis indicated bacterial families with sulfur (S) metabolisms (sulfate reducers, sulfide oxidation, and disproportionation of S‐intermediates) were enriched post‐eruption. The diversity in S‐cyclers without a corresponding change in sulfate geochemistry suggests cryptic cycling may occur in groundwater aquifers as a result of distant volcanic subsurface activity. Microbial communities, including taxa that cycle S, may be superior tracers to changes in groundwater quality, especially from direct inputs of subsurface volcanic activity. [ABSTRACT FROM AUTHOR]

This study determines the prevailing concentrations of 222Rn in twenty groundwater samples and primordial radionuclides in twelve soil samples collected from the surrounding area of the Rooppur Nuclear Power Plant (RNPP) in Bangladesh. The mean concentration of 222Rn, 226Ra, 232Th and 40K in the studied samples was found to be 4.42 ± 2 Bq/L (Water), 25.2 ± 5.3, 23.9 ± 6.3 and 317.1 ± 31.4 Bq kg−1 (Soil) respectively. Associated health hazards were estimated and compared with the respective safety limits recommended by international organizations. The present results may serve as the base values of naturally occurring radioactive materials in the vicinity of the RNPP in Bangladesh. [ABSTRACT FROM AUTHOR]

Globally, it has been reported that groundwater contains elevated levels of Fe and Mn. However, the risk of prolonged exposure to groundwater with elevated Fe and Mn was often ignored due to their much lower carcinogenic risk. To assess the human health risk of elevated Fe and Mn intake in groundwater, 1863 groundwater samples from the Yangtze catchment, a densely populated and economically prosperous area of China, were collected in this study. The spatial distributions of Fe and Mn in groundwater were investigated by the geographic information system (GIS) and their health risk assessment was done. The results indicated that 38.6% and 50.3% of the groundwater samples were defined as "elevated/high" levels for Fe and Mn, respectively, exceeding 0.3 and 0.1 mg/L (World Health Organization guidelines). Moreover, in the groundwater of Yangtze Catchment, the order of Fe and Mn contents is followed by upper< middle< lower. Based on the calculated hazard index (HI), HIadult and HIchild were in a range of 0‐4.91 and 0‐11.07, respectively. There was an area of 3,483 and 35,523 km2 with a non‐carcinogenic risk from Fe and Mn, correspondingly. The numbers of affected adults and children were about 3,018,066 and 2,775,007, respectively. It means that 0.20% and 2.00% of the study area or 0.64% and 0.59% of the total population will suffer health risks from Fe and Mn intake in groundwater, respectively. Therefore, a significant basis for groundwater safety in the Yangtze catchment and similar areas was provided in this study. [ABSTRACT FROM AUTHOR]

Dissolved organic matter (DOM) is widespread in uranium (U) hosting aquifer, a key substance affecting CO2 + O2 in situ leaching (ISL) of U by consuming injected O2. However, molecular composition and molecular transformation of DOM are poorly understood in this aquifer during the U mining. To address this issue, Fourier transform ion cyclotron resonance mass spectrometry was applied to investigate DOM molecules in groundwater samples and rock samples collected from a U mining aquifer. The high proportion of labile tyrosine‐like component and BIX value in monitoring wells (BM) indicated the biological origin of DOM. CHOS and aliphatic were the major components of water‐soluble organic matter (WSOM) in U‐bearing rocks, but CHO and highly unsaturated structures with high oxygen (HUSHO) were the main components of DOM in BM. The ISL led to the release of WSOM and the oxidation of DOM, which accounted for 24.5%–57.4% and 39.1%–65.7% of expected DOM, respectively. Potential molecular transformations (PMTs) results showed that the intragroup transformations dominated, and remarkable transformations from CHON and CHONS to CHO occurred during ISL. The positive net PMTs of condensed aromatic structure (CAS), aromatic structures (AS), and aliphatic suggested that they were transformed from HUSLO and HUSHO. A gradual decrease in (DBE−O)/Cwa and a gradual increase in NOSCwa indicated that the saturated degree and oxidation state of DOM increased during mining. This work successfully identified molecular characteristics of DOM in U hosting aquifer, and proposed a paradigm of DOM transformation pathways during ISL. Plain Language Summary: Dissolved organic matter (DOM) was a key substance widely distributed in Uranium (U) hosting aquifer, however, the characteristics and its potential molecular transformation during neutral in situ leaching (ISL) remained unclear. Here, 13 groundwater samples and 5 rock samples were collected from the Qianjiadian U deposit, a sandstone‐type U deposit by neutral ISL in China. Groundwater chemistry, 3D fluorescence spectroscopy, FT‐ICR MS, and carbon isotope approaches were employed to investigate the characteristics of DOM, identify and quantify the processes affecting the composition of DOM during ISL. Spectral and molecular characteristics of DOM revealed the biological origin of DOM and the biological activity in U‐hosting aquifers. CHOS and aliphatic were the major components of water‐soluble organic matter (WSOM) in U‐bearing rocks. The release of WSOM (24.5%–57.4%) and oxidative degradation of DOM (39.1%–65.7%) together controlled the composition of DOM during ISL. The gradual decrease of (DBE−O)/Cwa and gradual increase of NOSCwa indicated that the saturated degree and oxidation state of DOM increased as mining. This work improves our understanding of molecular characteristics of DOM in U hosting aquifer and molecular transformation pathways of DOM during ISL. [ABSTRACT FROM AUTHOR]

Karst areas are widespread in China and can be divided into southern karst and northern karst based on the geographical boundary of Qinling Mountains and Huaihe River. In northern karst regions, karst springs are the predominant landform. Previous studies on karst springs have predominantly focused on macroscopic perspectives, such as water chemistry characteristics, with less attention given to the microscopic characteristics of springs. Therefore, this study focused on the Jinan Baotu Spring area, representative of a typical northern karst region, and investigated the natural nanoparticles present in different aquifers at various depths from a microscopic point of view. Through the observation of nanoparticle tracking analyzer (NTA), numerous nanoparticles were identified in the groundwater samples. The particle size range of the particles contained in groundwater is mainly concentrated in the range of 150–500 nm, and the particle concentration is mainly concentrated in the range of 1.5–5.0 × 105 Particles/L. The microstructure, chemical composition, and element distribution of these nanoparticles were analyzed using TEM-EDS techniques. The results unveiled the presence of Ti-bearing nanoparticles in various groundwater layers, including both crystalline and amorphous states, as well as nanoparticles exhibiting the coexistence of crystal and amorphous structures. By comparing the measured lattice spacing with PDF cards, the crystalline Ti-bearing nanoparticles were identified as rutile, brookite, anatase, ilmenite, pseudorutile, and ulvospinel. Furthermore, the main components of the amorphous Ti-bearing nanoparticles predominantly consisted of Ti or a mixture of Ti and Fe. EDS analysis further indicated that the Ti-bearing nanoparticles carried additional metal elements, such as Zn, Ca, Mn, Mo, Cr, and Ni, suggesting their potential role as carriers of metal elements during groundwater transportation. This discovery provided new insights into the migration of metal elements in groundwater and underscores the capacity of nanoparticles to enhance the mobility of inorganic substances within the water environment. Notably, brookite was detected in three different areas, including the direct discharge area, indirect recharge area, and discharge area, which may indicate that some special natural nanoparticles could serve as natural mineral tracer particles in the process of groundwater migration. [ABSTRACT FROM AUTHOR]

A total of 18 samples of shallow groundwater around the Hancheng mining area in the Guanzhong Basin were collected from 1–4 May 2018. According to the analysis of hydrochemical data, the Gibbs semi-logarithmic diagram and Piper diagram were used to research the hydrogeochemical behavior of shallow groundwater around the Hancheng mining area in the Guanzhong Basin. The results of the groundwater hydrochemical analyses shown on the Gibbs and Piper plots are as follows: The chemical composition analysis showed that the main cation components were Mg2+, Ca2+, Na+, and K+, the anion components were HCO3−, Cl−, and SO42−. A measure of 89% of the groundwater samples in this area were freshwater, the HCO3− were mainly dolomite, calcite, and gypsum dissolved precipitation resulted. Na+ and Cl− came from the dissolution of halite. Most of the groundwater was of the SO4·Cl-Ca·Mg type, accounting for 61.1%. The main ion chemistry of the shallow groundwater in this area is controlled by rock weathering, and pyrite oxidation is a significant factor affecting the SO42− concentration. These research results will help analyze the formation mechanism of chemical components and provide some basic data for the evolution of mine water in this area in the future. [ABSTRACT FROM AUTHOR]

The Amu Darya River and the surrounding groundwater aquifers are important resources for drinking water and agricultural use in Karakalpakstan, western Uzbekistan. However, access to these water resources has been limited because of the region's arid cli- mate. Considerable concerns for water quality are the contents of minerals and uranium. In Karakalpakstan, soil salinization has been caused by years of inappropriate and excessive irrigation with highly mineralized water. High uranium concentrations in drinking water can increase the risk of health issues such as kidney disorders. In this study, the concentrations of uranium were measured by ICP-MS to evaluate the quality of groundwater and the Amu Darya River. The uranium concentration of the river water was more than two-fold greater than in 2004. The uranium concentrations exceeded the WHO guidance value at some groundwater sampling locations. A correlation analysis between the mineral and uranium contents in groundwater showed a strong correlation when the uranium concentration was less than 100 µg/L. Conversely, there was no obvious correlation at uranium concentrations greater than 100 µg/L. While low uranium levels can accumulate naturally with salts, extremely high uranium levels are likely the result of intensive human-caused pollution. [ABSTRACT FROM AUTHOR]

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In arid regions characterized by large variations in groundwater salinity, the data derived from irrigation and domestic water supply wells may exhibit bias, reflecting an overall lower salinity than the true aquifer distribution. This bias stems from the decommissioning, non-use, or disrepair of wells that are frequently sources of higher salinity readings, rendering them unavailable for sampling. Baseflow-fed streams, agricultural drains, seeps, springs issuing into agricultural drains, and randomly located test hole samples tend to manifest higher averages and ranges of salinity when compared to supply wells. Agricultural drain flows, springs, and test holes, if sampled following recommended guidelines, are less susceptible to such bias. This study presents a case of groundwater bias identified through an initial water well sampling program in El Paso (Texas, USA). Subsequent rounds of sampling, incorporating drain samples, spring samples, and test hole samples, revealed a more comprehensive understanding of the salinity dynamics. The dataset not only highlights the existence of bias but also provides evidence for a combined geological and agricultural origin of salinity. Additionally, it demonstrates that drain sampling in an earlier study did not accurately depict a primary salinity source due to incomplete analysis of the data. Recommendations are outlined to mitigate bias, emphasizing the importance of sample control from baseflow-fed drains, springs, water wells, and test hole samples. The study also infers the upwelling of saline groundwater from deeper formations in the study area, contributing to a more comprehensive understanding of groundwater salinity dynamics. [ABSTRACT FROM AUTHOR]

The present study assesses the pollution load of groundwater with reference to the trace and rare earth elements (REEs) and the potential health risk by its consumption for the residents of three distinct geological areas underlain by rocks of Quaternary (area 1), Cretaceous (area 2), and Precambrian, areas 3A and 3B in southeastern (SEN) and northcentral (NCN) Nigeria respectively. For this, 75 groundwater samples were collected and analyzed for physical parameters including hydrogen ion concentration (pH), electrical conductivity (EC), and total dissolved solids (TDS), trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn), and REEs. The pH varied from acidic to alkaline, with EC (6–1270 μS/cm) and TDS (8–922 mg/l) below guideline values. Concentration of Al (16.78–3716 μg/l), Ba (7.83–730.8 μg/l), Fe (33.72–1192.5 μg/l), and Mn (3.58–1192.0 μg/l) in some locations were higher than their respective guideline values. REEs (0.05–26.42 μg/l) PAAS normalized values showed negative Ce and positive Eu patterns with minor variations to positive Ce and flat patterns. Geochemical analysis of the groundwater samples showed that areas 1, 2, and 3A were severely contaminated with Al, while area 3B was contaminated with Fe. Multivariate analysis indicated that elements in groundwater were contaminated mainly through natural (Al, As, Ba, Fe, Mn, Ni, REE) as well as anthropogenic (As, Cd, Cu, Cr, Pb, V, and Zn) sources, degree of contamination (Cd), trace element pollution index (TEPI), and trace element evaluation index (TEEI) for the different areas for most groundwater samples were below critical values, indicating low pollution. However, rare earth element evaluation index (REEEI) showed various level of pollution in the different areas, in the order 3A > 1 > 2 > 3B. For the majority of groundwater samples across the different areas, non-carcinogenic health risk was not observed as the hazard quotient (HQ) values were less than unity, except for Al. The hazard index (HI) values were higher than unity for all areas and age groups (1.60–754.61) due to Al, indicating unacceptable non-carcinogenic health risk. The total carcinogenic risk (CRTOTAL) values were ranged 1.10E-04 to 6.21E-03 for all areas and age groups, suggesting that the CRTOTAL values were at unacceptable level of 1.00E-04 for sum of all PHEs. The order was Cd > Ni > As > Cr > Pb. In all cases, higher values of HI and CR were obtained for children compared to adults and infants in the entire study area, which means that children are more susceptible to health impairment. [ABSTRACT FROM AUTHOR]

This study determined the antibiotic-resistant gene (ARG) contents of 34 groundwater samples in Henan Province collected from September to October 2022, then assessed the roles of both water quality parameters and intI1 in ARG propagation in groundwater. The results show that there existed universal ARG pollution in groundwater, and sulfonamides-, β-lactem-, and tetracycline-resistance genes were the most prevalent gene types during the time. Sul1 contributed the majority proportion of the total resistance genes (TARGs). The prevalence of ESBLs gene blaTEM and the occurrence of Carbapenems resistant gene blaOXA-1 suggests the pollution of high-risk ARGs in groundwater demands more attention. IntI1 is prevalent and had a significantly positive correlation with almost 50% ARGs, indicating its contribution to ARG propagation in groundwater. Well types contribute little to ARG propagation in rural groundwater of Henan, which means the protective facilities established by the local government for public wells can effectively prevent contamination from exogenous ARGs. However, the economic level has no impact on the abundance of ARGs in rural groundwater, which suggests the local government should pay greater attention to investment in controlling ARG pollution in Henan rural areas. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the REEs' presence in the rocks and groundwaters of three different aquifers in eastern Crete. The first develops in carbonate rocks, and is a typical unconfined karst aquifer. The second, develops in Miocene conglomerates and sandstones, and is confined by marly formations, while the third in the Pliocene conglomerates overlying the Phyllites Formation. They are all formed by minerals such as calcite, dolomite, aragonite, anhydride, halite and sylvite, display neutral to slightly alkaline pH and positive to slightly positive redox values. The karst aquifer is of Ca-Mg-HCO3 water type, while near the coast Na+ and Cl− are also involved due to seawater intrusion. In the other two aquifers, complex hydrochemical types prevail such as, Ca-Mg-Na-HCO3-Cl for the second or Na-Ca-Mg-Cl-HCO3 for the third one. ΣREEs concentrations range between 64 and 1,671 ppm for rocks, 45 and 120 ppt for 0.45 μm filtered, and 219 and 1,087 ppt for unfiltered groundwater. The differences between filtered and unfiltered samples were attributed to the greater tendency of REEs to be adsorbed on surfaces such as Fe-Mn oxides and hydroxides, some organic substances or particles, colloids, clay minerals, and microorganisms, which were removed during filtration. Furthermore, an evident negative Ce anomaly in the filtered samples was attributed to the Ce oxidation and removal from the dissolved phase. The Japanese and European shales normalised REE diagrams of all groundwater samples show great similarities attributed to the presence of common major minerals such as calcite, dolomite and gypsum. The positive Eu anomalies were attributed to the dissolution of these common minerals from the aquifers' bedrock. Finally, the increased concentrations in the unfiltered samples of the porous aquifers were associated with ion exchange processes, while the lower values in certain brackish samples were attributed to colloidal precipitation processes due to the increased salinity. [ABSTRACT FROM AUTHOR]

To elucidate the hydrochemical characteristics, controlling factors, sources and mechanisms of strontium ion enrichment in groundwater in the northwest plain of Shandong Province, China, 88 groundwater samples were collected, including 51 shallow pore groundwater samples, 29 deep pore groundwater samples and 8 karst groundwater samples. The hydrochemical characteristics of the different types of groundwater were quite different. The karst groundwater samples were all fresh water with a single hydrochemical type, either HCO3-Ca or HCO3-Ca·Mg. The deep pore groundwater samples were mainly brackish water, and the shallow pore groundwater samples were brackish water–salt water, which has complex hydrochemical types. The hydrochemical characteristics of all the types of groundwater were controlled by mineral dissolution and active positive cation exchange. In shallow pore groundwater, deep pore groundwater and karst groundwater, the dissolution of silicate, evaporite and carbonate minerals dominated the hydrogeochemical process. The strontium in groundwater was derived from the dissolution of minerals with strontium isomorphism. The average contents of strontium in shallow, deep and karst groundwater were 1.59 mg/L, 0.58 mg/L and 0.50 mg/L, respectively. The strontium in shallow pore groundwater was mainly derived from the enrichment of groundwater runoff, and its sources are abundant, with silicic rock being the main source. The deep pore groundwater mainly derived from the evaporative minerals containing strontium, and the karst water mainly derived from carbonate rock dissolution with similar characteristics. [ABSTRACT FROM AUTHOR]

This work aimed to investigate the impact of hydrogen peroxide (HP) punctual dosage on paracetamol (PCT) degradation, through Fenton and photo-Fenton processes under near-neutral pH conditions, using ferrioxalate and artificial sunlight. The assays were performed using a D-optimal experimental design, to statistically evaluate the influence of radiation (ON or OFF), HP concentration (94.5–756 mg L−1), and HP dosage (YES or NO), on PCT conversion. The optimal conditions determined from the study were: HP = 378 mg L−1, DOS = YES, and RAD = ON, achieving a predicted PCT conversion of 99.68% in 180 min. This result obtained from the model was very close to the experimental one (98.80%). It was verified that HP dosage positively influenced the iron catalytic cycle since higher Fe2+ concentrations were reached at shorter reaction times, accelerating not only PCT conversion but also its by-products hydroquinone and 1,4-benzoquinone, leading to better performances of Fenton and photo-Fenton reactions. Under optimal conditions and employing real water matrices (an artificial matrix with inorganic anions, a real groundwater sample, and a synthetic industrial wastewater), HP dosage demonstrated the ability to mitigate the negative effects caused by the content of different ions and other organic compounds and significantly improve HP consumption in challenging wastewater conditions. [ABSTRACT FROM AUTHOR]

The present study explores the suitability of groundwater for drinking purpose and evaluates non-carcinogenic health risks for children, women, and men. For this purpose, 47 groundwater samples were collected and analyzed for physicochemical parameters, including nitrate concentration. The results revealed that nitrate concentration varied from 15 to 85 mg/L and that 48.93% of the groundwater samples exceeded the Bureau of Indian Standards' limits of 45 mg/L. The spatial map of the pollution index of groundwater specifies that most of the study area lies in moderate to high pollution zones. Principal component analysis was also applied, and five principal components achieving eigenvalues more than 1 with a cumulative variance of 77.36% were found to be sufficient. The findings of non-carcinogenic risk rates range from 0.628 to 3.559 (average of 2.069) for children, 0.427 to 2.421 (average of 1.408) for women, and 0.362 to 2.049 (average of 1.191) for men, and approximately 80% of the population in the study region is exposed to high health risks. The health risk assessment specified that children in the study area are more susceptible than women and men. The findings of this study suggest that groundwater quality in the region has deteriorated, emphasizing the need for treatment before drinking. [ABSTRACT FROM AUTHOR]

A holistic understanding of groundwater hydrogeochemical characteristics and water quality is an essential task for managing and protecting groundwater resources. However, it is a challenge for the complex hydrogeological conditions of the Tibetan Plateau coal base, where many factors can cause regional hydrochemical changes. In this study, the groundwater hydrochemical processes in the Jiangcang basin of Qilian coal base are analyzed by the combination of self-organizing map (SOM) and K-means clustering. Traditional hydrogeochemical methods such as Durov diagram and Gibbs diagram are used to further demonstrate the feasibility of the SOM clustering method systematically. Further, the entropy-weighted theory is used to describe groundwater quality and assess the suitability of groundwater for drinking purposes. The results show that the groundwater samples (Cluster I and III) are mainly distributed around the mine area and coal transport channel, with high Na+ and high SO42− type. Their groundwater hydrochemical formation mechanisms are influenced by human factors, the main ion sources are related to coal production. The groundwater samples (Cluster II) are distributed in river valley talik and bedrock mountains far away from the mine area, mainly HCO3− type water. The rock weathering is the dominant mechanism controlling the groundwater chemistry of Cluster II. Among the 42 groundwater samples, 80.9% of the above-medium groundwater samples were suitable as drinking water. The results of this study demonstrate that the SOM can be used as a data-driven approach to understanding the hydrochemical processes in alpine regions, which can facilitate better water resource management and ecological environmental protection of Tibetan Plateau coal base. [ABSTRACT FROM AUTHOR]

Water inrush accidents in coal mining seriously restrict production activities and accurately identifying the source of inrush water can effectively ensure mining safety. Based on groundwater, chemical composition of main aquifer in Pingdingshan coal mine area established a dynamic weight identification model of mixed inrush water source based on variable weight synthesis theory. The results indicate: through Piper trilinear diagram analysis, the pore groundwater sample Q11 of Quaternary system and the groundwater sample P6 of Permian sandstone system with abnormal content of Na+ + K+ were removed; and determine the state variable weight parameter α of the main aquifer (Quaternary α1 = − 0.2997, Permian α2 = − 0.3766, Carboniferous α3 = − 0.3085, Cambrian α4 = − 0.2469); construct the variable weight matrix of the water sample, combined with the principle of membership degree, the dynamic weight discriminative model of water source is established. The discrimination results show that the accuracy of the model reaches 100%. Significantly higher than the Piper–EWM water source identification model based on constant weight (76.9% accuracy). This model considers the configuration level of various variables in the water sample, weakens the influence of content extreme value on weight, the weight of the same index will change dynamically between different water samples, get rid of the constraint of fixed weight, reflect the weight of each index in the discrimination process more scientifically, greatly improve the identification accuracy, and provide a strong guarantee for the safety of coal mining activities. [ABSTRACT FROM AUTHOR]

Groundwater carries radioactive elements like 226Ra, 222Rn, and 210Po during its flow beneath and above the land. When this water is used for drinking, cooking and other household purposes, the radioactive substances in the water may enter the human body and cause adverse health effects. This study was conducted to determine the distribution of 226Ra, 222Rn, and 210Po in the groundwater samples of Chamarajanagar District, Karnataka, India. The activity of 222Rn in 66 places was studied using the smart radon monitor. The activity of 226Ra, and 210Po was studied at 12 places using emanometry technique and radiochemical analysis, respectively. The activity of 222Rn in groundwater samples varied from 0.94 ± 0.13 to 26.90 ± 3.53 Bq L−1 with an average of 4.44 ± 0.56 Bq L−1. The activity of 226Ra, and 210Po varied from 2.18 ± 0.31 to 96.42 ± 16.55 mBq L−1 with an average of 31.38 ± 9.93 mBq L−1 and 0.72 ± 0.24 to 6.33 ± 0.88 mBq L−1 with an average of 2.86 ± 0.52 mBq L−1, respectively. A good correlation between 226Ra, 222Rn, and 210Po was observed, indicating that they might be of the same origin. The average ingestion dose due to 226Ra, 222Rn, and 210Po were 6.41, 11.58, and 2.51 µSv y−1 respectively, which is less than the recommended effective dose of 100 µSv y−1 associated with the intake of radionuclide from drinking water by WHO. [ABSTRACT FROM AUTHOR]

While extant research has predominantly focused on elucidating the mechanisms of fluorine (F−) enrichment in groundwater within the North China Plain, the occurrence and formation mechanisms of high-F− groundwater in Xiong'an New Area remain unexplored. Consequently, 365 groundwater samples (172 from shallow groundwater, 193 from deep groundwater) were collected from Xiong'an New Area. Hydrochemical analysis, geochemical modeling, and statistical analysis were used to explore the occurrence and formation mechanisms of high-F− groundwater. The results reveal that the highest F− concentrations in shallow and deep groundwater were up to 3.22 mg/L and 1.79 mg/L, respectively. High-F− groundwater was primarily located at the eastern part of the study area. The distribution area of high-F− shallow groundwater was much greater than that of deep groundwater. F-bearing minerals dissolution and ion exchange were the principal formation mechanisms of high-F− groundwater in both shallow and deep aquifers. Moreover, competitive adsorption, evaporation, and the impacts of Ca2+ and Mg2+ dissolution equilibrium on F-bearing dissolution were crucial to the formation of high-F− groundwater in shallow aquifers. Desorption in an alkaline environment, evaporites dissolution and salt effects were vital to the formation of high-F− groundwater in deep aquifers. These findings can contribute to the support of local groundwater security and management. [ABSTRACT FROM AUTHOR]

The Nestos River delta is one of the most important and sensitive basins in Greece and Europe due to its ecosystem functions, combining intensive agricultural production with low-enthalpy geothermal energy and important ecotopes. High water quality is of paramount importance to the sustainability of the system. Systematic and continuous assessment of water quality needs to be carried out in a way that is easy and quick for decision makers and non-expert societal partners to comprehend. In this way, decisions may be made more rapidly, and involved water users may be sensitized to rational water use. To this end, this paper presents the assessment of groundwater quality in the Nestos River's western delta with the use of Poseidon (PoS), a versatile, index-based method. Groundwater samples collected from 24 and 22 wells tapping the unconfined and the confined aquifers, respectively, in four time periods (May and October 2019 and 2020) were analyzed. Using the PoS index, groundwater samples were classified according to their quality status, highlighting the parameters driving quality degradation issues, thus assisting water managers in obtaining an overview of quality status and evolution through datasets that were often large. PoS index is applied in the study area for the first time and provides a groundwater quality assessment through a unique score representative of the overall water quality status regardless of processes (anthropogenic or natural) or any kind of pressures. [ABSTRACT FROM AUTHOR]

The purpose of this study is to clarify the vertical prokaryotic distribution in groundwater in a terrestrial subsurface sedimentary environment with a geological complex. Six groundwater samples were collected from a coastal 1200-m-deep borehole in which digging strata deposited between 2.3 and 1.5 Ma in Horonobe, Hokkaido, Japan. The studied succession was divided into three vertical zones that were geochemically differentiated according to their chloride contents and water-stable isotopes. The upper zone (UZ; shallower than 500 m) primarily contained fresh water supplied by penetrating meteoric water, the connate water zone (CWZ; deeper than 790 m) contained paleo-seawater, and the diffusion zone (DZ; 500–790 m depth) located between UZ and CWZ. Fluctuations in the prokaryotic density and constituents were observed across these three zones. The prokaryotic density decreased from UZ toward DZ, and the density of DZ was two orders of magnitude lower than that of UZ and CWZ. High prokaryotic activity was observed in CWZ below DZ. The upward expansion of prokaryotic distribution from CWZ, where high prokaryotic potential expressed by biomass can be maintained almost equivalent to that in the marine environment, probably occurred on a geological timescale from 80 ka to 1.3 Ma, as shown by the groundwater age of DZ. The DZ is a zone where the geochemistry has changed drastically owing to the mixing of penetrating meteoric water and the diffusion of deep paleo-seawater, preserving a unique subsurface environment. This chemically mixed zone might be considered as a buffering zone for prokaryotes to prevent the expansion of prokaryotic density and activity provided by diffusion and their in situ growth from both above and below the zones, which is expected to be maintained over a geological timescale. This zone is considered important for using subsurface space in the deep subsurface environment of the island arc. [ABSTRACT FROM AUTHOR]

Ten (10) groundwater samples collected from boreholes in Itu and Uyo localities of Akwa Ibom State were evaluated for physicochemical, bacteriological and hydrogeochemical assessment using standard analytical techniques. Results showed average pH of 4.49, temperature of 29.14 oC, EC of 45.30 μs/cm; TDS of 21.60 mg/l, Hardness of 4.30 mg/l, K of 2.49 mg/l. Mg was found to be 0.74 mg/l, Ca is 13.14 mg/l, SO4 has values of 3.9 mg/l, HCO3 concentration was also found to be 1.35 mg/l, Cl observed to be 4.07 mg/l. furthermore, NO3 concentration was also observed to be 17.71 mg/l, Mn2+ had 0.049 mg/l concentration, BOD5 is 5.82 mg/l, P2O5 was found to be 12.00 mg/l, Cr is 0.025 mg/l, NH3 is 0.142 mg/l, Zn is 0.138 mg/l, Cy is 0.006 mg/l, Fe is 0.159 mg/l, Pb is 0.002 mg/l, Ni is 0.19 mg/l, Cu2+ is 0.034 mg/l, Turbidity is 0.40 mg/l, Salinity is 0.002 ppt, and Alkalinity is 2.40 mg/l.. Comparing these values with WHO (2011a) standards, it was discovered that some parameters, including Ni, Cr, Fe, Mn and NO3-, had concentrations that were above the permissible limits in some locations while a few other locations showed concentrations which were within the permissible limits. Bacteriological investigations of faecal coliform count (FCC), total coliform count (TCC) and total heterotrophic count (THC) revealed an excessive presence of coliform. Hydrogeochemical assessment revealed no evidence of saline intrusion and the groundwater is of terrestrial origin. Based on different ionic concentrations, the Piper trilinear diagram revealed two fundamental types of water; the calcium sulphate and calcium bicarbonate waters. The groundwater was classified as acceptable for agricultural purposes based on the magnesium ratio and sodium adsorption ratio, which also indicate that the groundwater is excellent, soft and suitable. [ABSTRACT FROM AUTHOR]

Groundwater is extensively used for irrigation in the Doaba region of Punjab, where it supports the cultivation of various crops, including potatoes. This region relies heavily on chemical fertilizers and pesticides for growing different crops, which pose a dual threat by potentially degrading groundwater quality and depleting its reserves. To address these concerns, a survey-based investigation was conducted to evaluate the quality of irrigation water and assess potato tuber yields. It was observed that farmers are drawing groundwater from borewells with an average depth of 254.0 feet, and the water is delivered from a depth of 145.67 feet. The analytical results showed that all the groundwater samples tested were suitable for irrigation. Additionally, a significant positive correlation was found between potato tuber yield and the nitrate content of the groundwater. Consequently, it is essential to factor in the nitrate contribution from groundwater when making recommendations for nitrogen usage in the region. [ABSTRACT FROM AUTHOR]

The self-potential (SP) method investigated leachate distribution near Rawa Kucing. Rawa Kucing is the main landfill in Tangerang that burned almost the entire area. A total of 78 SP data points were scattered throughout the study area. The SP values range from -20 to 16 millivolts, dominated by negative values attributed to electrokinetic processes. The results suggest that a highly conductive zone in the study area may have been caused by high contamination from leachate. The possible direction of leachate flow is towards the Cisadane stream, located west of the landfill. On the other hand, a quantitative interpretation of SP was conducted for two profiles, AA' and BB'. The result shows that the vertical spreading of leachate was found at a depth of h 6,59 and 3,53 meters and H 8,10 and 4,34 meters for AA' and BB', respectively, with an angle of 28,810. Additionally, groundwater samples were collected from four sites near the landfill to assess groundwater quality using physical and chemical analysis. Based on the Indonesian Ministry of Health Regulation, most parameters indicated low contamination. Statistical analysis revealed that the groundwater near the landfill was worthy of consumption. Based on the results, rainfall during the study significantly reduced the concentrations of contaminants in leachate due to dilution. [ABSTRACT FROM AUTHOR]

Hydrochemical study of groundwater has carried out for the Al-Khassa Sub-Basin during the October 2020 and May 2021 seasons for estimating the impacts of seasonal variation and human activity on water quality and using the isotope to determine the main source of recharge. It was found that Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), and Dissolved Oxygen (DO) were out of the standard indicating that the groundwater environment was reduced and difficult to recover from pollution. Physical and chemical properties that were high (Total Dissolved Solid (TDS), Total Suspended Solid (TSS), Electrical conductivity (EC), Total Hydrocarbon (THC)). Partial pollution by nitrate and phosphorous due to the use of fertilizers for these elements. The contamination by manganese, molybdenum and boron was present in allsamples of the two seasons, and partly for lead and mercury due to fertilizers, agricultural activities, the presence of animal and poultry,ranchesbesides the poor sewage system in the basin based on a septic tank. Washing polluted agricultural soil by rain lead to polluting groundwater. From the environmental isotope analysis (δ²H and δ18O), the isotopic compositions of precipitation were used to construct a local meteoric water line for the study area. The isotopic compositions of groundwater samples were situated to the left of the Global meteoric water line (GMWL), suggesting input of local rainfall that derives from weather front originating from the Mediterranean Sea. Comparing the isotope composition of groundwater and precipitation showed that the infiltrated precipitation that was the main source of recharge to the aquifer system in the study area. [ABSTRACT FROM AUTHOR]

Radon ( 222Rn) is naturally readily water-soluble, posing a cancer risk to the exposed community. Human exposure in the community may occur via 222Rn intake in drinking water. Groundwater is used for drinking and other domestic purposes in the region. Higher concentrations of 222Rn in groundwater have been reported near Kotli district, Azad Jammu, and Kashmir. This investigation aimed to measure 222Rn concentrations in groundwater and evaluate the associated risk assessment for children and adults in the Kotli district. 222Rn concentrations were measured in randomly collected groundwater samples of Kotli (n = 25) and Sehnsa (n = 15) towns in the Kotli district using the portable Radon Detector (RAD7, Durridge Company, United States of America). Among the studied areas, the Sehnsa showed a higher average 222Rn concentration (7.6 ± 0.2 Bq/L) in groundwater compared to Kotli (6.0 ± 1.9 Bq/L). The average concentrations of 222Rn were found within the recommended limit (11.1 Bq/L) of the United States Environmental Protection Agency (USEPA), except for 10% of sampling sites. 222Rn concentrations were used for the calculation of total effective dose for ingestion and inhalation pathways (EwTotal) values for infants (24.5 ± 7.5 and 30.7 ± 0.9 μSv/a), children (18.1 ± 5.5 and 23.5 ± 0.7 μSv/a), and adults (18.1 ± 5.5 and 22.7 ± 0.3 μSv/a) in the Kotli and Sehnsa, respectively. This study noted that EwTotal and estimated lifetime cancer risk (ELCR) values were found within the World Health Organization (WHO) and European Commission (EU) acceptable limits (<100 μ Sv/a and 0.1 × 10-3 ). [ABSTRACT FROM AUTHOR]

The Dashty-Hewler basin is a groundwater basin located in Erbil in northern Iraq. It comprises three distinct sub-basins (Kapran, Central, and Bashtapa) covering a total basin area of 2,660 km² . It is bounded by the greater Zab river to the north and the little Zab to the south. The groundwater in this catchment has never been investigated using modern environmental isotope evidence. Since the groundwater in this basin serves as both drinking water and a source of irrigation, its management is crucial. Recently, due to the increase in population, excessive pumping has taken place, which has led to a decline in the water table. Accordingly, it is necessary to address the issues of where the groundwater will recharge and what the source of the recharge will be. For this purpose, 27 groundwater samples from different wells and two river water samples were analyzed for stable isotopes (δ18O and δ² H). The distribution of δ18O and δ² H over the study area was utilized by inverse distance weighted (IDW) interpolation within ESRI ArcGIS (10.8). The results indicated that the relationship between δ18O and δ² H in the groundwater samples (δ² H = 6.59 δ18O þ7.48‰) showed relative shifts of both the slope and the deuterium excess when compared to the Iraq meteoric water line (δ² H = 7.66 δ18O þ 14.19‰). The deviation of data points from the meteoric line can be attributed to high evaporation both during the rainy season and through run-off on the ground surface before infiltration. Most of the groundwater samples had a deuterium excess above 10‰ between 12.14 and 22.72‰, suggesting the precipitation present in the groundwater comes from the Mediterranean sector. Based on local isotopic gradients (δ18O, 0.22/100 m), in combination with topographic and geologic criteria, the recharge areas were identified as being between 400 m and 1,100 m above sea level. [ABSTRACT FROM AUTHOR]

This study aimed to assess the quality of groundwater for drinking and irrigation in the Pandameru River basin, Andhra Pradesh, India. Groundwater samples were collected from 46 locations within the research region during the pre-monsoon season. These samples were analyzed for various parameters such as pH, EC, TDS, Ca2+, Mg2+, Na+, K+, HCO3−, Cl−, SO42−, and NO3−. The results were compared with WHO guidelines, indicating slightly alkaline groundwater. Analysis using the WQI and GIS-based interpolation provided an overall evaluation of water quality. WQI values range from 78.49 to 115.92 mg/L, indicating that 77% of the samples are safe for drinking, while 23% were unfit. Groundwater samples are found in the field of rock dominance, based on the Gibbs plot. The majority of the samples fell into the C3S1 category, which denotes water with high salinity and low sodium which is moderately suitable for irrigation purposes, according to the USSL diagram. Regarding cultivation, 78% were good, 20% doubtful, and 2% unsuitable based on the Wilcox classification. Except for a few locations, most samples were suitable for irrigation. However, some samples exceeded allowable contaminant levels due to human activity, requiring treatment before consumption. [ABSTRACT FROM AUTHOR]

The coastal aquifer of Gwadar city is exceptionally vulnerable to saltwater intrusion due to sea level rise and the combined effects of both anthropogenic and natural factors. Due to this reason, the current research aids in understanding the extent of saltwater intrusion and the role played by the associated factors. Thirty-five groundwater samples were collected from the bores and wells, and the water level at each sampling location was measured. The physicochemical parameters (TDS, EC) and pH of the groundwater were recorded in situ. Analytical findings indicate that the groundwater in the study area is typically brackish to saline. The salinity (EC) values of the groundwater are highly variable, rising from 760 to 18,350 μS/cm with an average of 6884 μS/cm, whereas the average pH was 7.1 and varied from 6.6 to 7.5. The salinity values nearest and farthest from the shores were 760 μS/cm and 11,650 μS/cm, and the average salinity during low (1.38) and high tide (1.46 m) were 3566 and 14,462 μS/cm, respectively. The average salinity of the groundwater samples with a relatively low elevation was 11,770 μS/cm. The recorded values of EC and TDS show the impact of salinization in the coastal aquifer of Municipal Committee Gwadar (MCG) because of saltwater intrusion. [ABSTRACT FROM AUTHOR]

The study examines the groundwater around Prague Castle as an example of an extreme urban environment that has been influenced by human activity since the Neolithic period. The longterm human activity, including several stillfunctioning drainage adits, resulted in a number of aggradation and degradation processes that have significantly impacted the groundwater regime. Furthermore, building development, particularly largescale concrete structures, has had a notable effect on groundwater chemistry. This paper presents results of available archival chemical analyses from the area of interest (Fig. 1), along with our own groundwater chemical analyses. The results of recovery test in the anthropogenic alluvium well underneath the courtyard III of Prague Castle (Weiss et al. 2024) indicate that the transmissivity of saturated alluvium is low (8-10 m²/day). However, it is reasonable to assume a higher transmissivity for the entire area. The clayey anthropogenic alluvium near the surface likely has a much lower permeability than the underlying fractured zone of the Letná Formation made of shales (Late Ordovician). Field reconnaissance in the drainage adits indicates that groundwater flows directly from the historic alluvium (presence of bones and other organic remains) into the Ordovician strata. The existence of a clay aquitard, as mentioned by some authors (e.g. Kos 1965), between the historical alluvium and the underlying Ordovician is thus unlikely. The analysed water samples from selected objects can be classified into three distinct groups based on their pH levels: slightly acidic (precipitation water, and the well in the St. George's Convent -- V4), neutral (majority of samples), and alkaline (the environment underneath the courtyard III of Prague Castle). Slightly acidic pH level only applies to samples from precipitation or probable seepage (V4). The concentration of Clin the majority of the analysed groundwater samples is higher than the natural background level of around 8-10 mg/l, which indicates an anthropogenic source. The major source of these ions in the area is likely the use of NaCl to salt roads and sidewalks during the winter months, which has been a common practice for decades. The overall analysis of the studied samples identified two main hydrochemical types of water: Type A and Type B. Type A is represented by moderately alkaline water that is rich in sulphate and calcium/magnesium. Type B, on the other hand, is represented by strongly alkaline water rich in hydrogencarbonate and calcium, found mainly under the courtyard III of Prague Castle, which stands on a concrete structure. Type A is the predominant type and is typical of water originating in the pyritebearing shales of the Letná Formation. The high sulphate content of these waters may cause "sulphate attack" of concrete, leading to its decomposition and thus affecting the durability of building structures. This study provides valuable insights into groundwater chemistry in urban environments that can be applied to other similar sites. [ABSTRACT FROM AUTHOR]

A simple and novel ultrasonically modified dual-cloud point extraction (Um-DCPE) method has been developed to preconcentrate a toxic heavy metal, lead (Pb2+), in aquifer water of different depths in the region of Thar coalfield, Pakistan, prior to analysed by flame atomic absorption spectrometry (FAAS). The Pb2+ in water samples have been complex with 8-hydroxyquinoline followed by the entrapping in the hydrophobic non-ionic surfactant (Triton X-114). The second step of Um-DCPE involved the addition of 0.5 to 2.0 mol L−1 of HCl/HNO3 (2 mL) and subjected to shaking and centrifugation, separate upper aqueous layers, and subjected for analysis. To check the performance of the proposed method a certified reference material (CRM) of water and spiked standard in a real sample were applied successively. Both LOD and LOQ achieved by the proposed method for Pb2+ were 0.023 and 1.70 μg L−1, respectively. The optimised Um-DCPE method was applied effectively to selected aquifer water samples. The results obtained from the proposed method indicated that the aquifer water samples of different depths have 2 to 3 folds higher Pb2+ values than recommended values of the world health organisation. [ABSTRACT FROM AUTHOR]

Understanding the residence time, flow velocities, and storage volumes in fractured rock aquifers is essential for assessing the sustainable use of groundwater in island aquifer systems. Environmental tracers such as tritium (3H) and sulfur hexafluoride (SF6) that enter the aquifer systems through natural hydrological processes are effectively used to quantify the "apparent age" of young groundwater (<60 years) to calculate these aquifer characteristics. The island of Tobago is predominantly a fractured rock aquifer system that contains groundwater sub-basins that produce 100–1000% more than their calculated recharge. In this study, we analyzed ten samples from groundwater wells throughout the island for environmental tracers to establish the "apparent age" of the groundwater. We then estimated the active flux and storage volume of the aquifer. The 3H results of ten wells throughout the island range between 0.02 and 0.60 TU. The groundwater samples to the south of the island possess more pre-modern groundwater ages (older ages) than samples in the north of the island. These tritium values reveal age ranges between 18 and 60–plus years. This finding suggests that fractures create flow paths oriented towards the southern parts of the basin that enable the transport of groundwater across significant topographic boundaries and watershed divides. Additionally, the data may support that southern wells are connected to isolated old sources of groundwater. SF6 values range between 0.91 and 7.97 (part per trillion volume) with an interpreted age range between 18 and 39 years. Both tracers support the original hypothesis that longer residence time waters are located south of the island except for three SF6 samples which are believed to be affected by "excess air". [ABSTRACT FROM AUTHOR]