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The Oued El Hatiba basin, located at the eastern boundary of the Aures massif, constitutes the main massif of the pre-Saharan Atlas in eastern Algeria. Geologically, the basin features a succession of marls at the base, overlain by Cretaceous limestones, covered by Plio-Quaternary sediments composed of alluvium and sand. The Babar Dam is situated in this basin, draining an area of 567 km2 along the Larab wadi. It is intended for irrigation of surrounding lands and the supply of potable water to neighboring communities. The analysis of major element concentrations from various sampled water points reveals that the waters exhibit dominant facies: chloride-calcium (48.88%), sulfate-calcium (24.44%), bicarbonate-calcium (15.55%), magnesium bicarbonate (08.88%), and magnesium chloride (02.22%). These chemical facies are determined by the aridity of the climate, water-rock interaction, dissolution, and mineral precipitation, mediated by cationic exchanges throughout the water flow towards its outlet. Calculation of mineral saturation indices in the water indicates that only carbonate minerals tend to precipitate, notably as calcite and dolomite, while evaporitic minerals (gypsum and halite) tend towards dissolution. A principal component analysis (PCA) was conducted on a data table consisting of eight (08) variables and 50 individuals. The analysis was extended to two factors, explaining 75.38% of the variance.

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, HCO 3−  > Cl −  > SO4 2−  > 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 Ca 2+ 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 + , Ca 2+ , HCO 3− 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.

Quantitative information regarding the endmember composition of the gas and oil that flowed from the Macondo well during the Deepwater Horizon oil spill is essential for determining the oil flow rate, total oil volume released, and trajectories and fates of hydrocarbon components in the marine environment. Using isobaric gas-tight samplers, we collected discrete samples directly above the Macondo well on June 21, 2010, and analyzed the gas and oil. We found that the fluids flowing from the Macondo well had a gas-to-oil ratio of 1,600 standard cubic feet per petroleum barrel. Based on the measured endmember gas-to-oil ratio and the Federally estimated net liquid oil release of 4.1 million barrels, the total amount of C ₁-C ₅ hydrocarbons released to the water column was 1.7 10 ¹¹ g. The endmember gas and oil compositions then enabled us to study the fractionation of petroleum hydrocarbons in discrete water samples collected in June 2010 within a southwest trending hydrocarbon-enriched plume of neutrally buoyant water at a water depth of 1,100 m. The most abundant petroleum hydrocarbons larger than C ₁-C ₅ were benzene, toluene, ethylbenzene, and total xylenes at concentrations up to 78 μg L ⁻¹. Comparison of the endmember gas and oil composition with the composition of water column samples showed that the plume was preferentially enriched with water-soluble components, indicating that aqueous dissolution played a major role in plume formation, whereas the fates of relatively insoluble petroleum components were initially controlled by other processes.

Nowadays, the presence of microplastics in drinking water is of concern worldwide due to potential impacts on human health. This paper has examined the presence of microplastics along the Llobregat river basin (Catalonia, Spain) and studied their behaviour and elimination along the drinking water treatment plant (DWTP). Due to different water composition, different sampling and sample preparation protocols were used to determine microplastics from river water and in the DWTP. Identification of microplastics of size range from 20 μm to 5 mm was performed by fourier-transform infrared spectroscopy (FTIR). Microplastics were detected in 5 out of 7 points along the Llobregat basin, with concentrations ranging between non-detected and 3.60 microplastics/L. In the intake of the DWTP, the mean concentration was 0.96 ± 0.46 microplastics/L ( n =5), with a predominance of polyester (PES) and polypropylene (PP) and at the outlet the mean concentration was of 0.06 ± 0.04 microplastics/L with an overall removal efficiency of 93 ± 5%. Sand filtration was identified as the key stage in microplastic removal (78 ± 9%). Furthermore, the results showed that ultrafiltration/reverse osmosis (advanced treatment) is more effective for microplastic removal than ozonation/carbon filtration stage (upgraded conventional treatment). In addition, a preliminary migration test of the different materials used in the DWTP has been performed to identify potential sources of microplastics in each treatment step.

The current research aimed to determine the origin of ions and the type of flow system in groundwater flowing out through two types of atmospheric and hydrothermal springs by hydrochemical and hydrodynamic approaches in a volcanic aquifer. Findings revealed that the major ion types in atmospheric waters are calcic and magnesium bicarbonate, whereas hydrothermal springs predominantly indicated chloride–sodic composition, showing an evolving pattern resulting from hydrothermal and atmospheric waters mixing. Investigating the ionic ratios and the saturation index to determine the origin of ions suggests that the presence of ions in the waters can be attributed to the weathering of silicates and plagioclase-bearing minerals in the volcanic units, and in some cases, ionic exchange also plays a role. The recession curve analysis revealed a predominant conduit flow with α = 0.144 in the system feeding the representative hydrothermal spring. Two micro-regimes with α1 = 0 = 0.46 and α2 = 2.68 were detected on the hydrograph of the atmospheric representative spring, indicating the development of systems with two types of flow regimes. Estimating the Qmax/Qmin ratio for selected hydrothermal and atmospheric springs as 2.3 and 36.8, respectively, and calculating the electrical conductivity coefficient as 11% and 18% respectively, confirmed the recession curve analysis result.

Groundwater is an important natural resources of drinking water in mining area in Xin’an spring basin, northern China. To foster the sustainable development and utilization of groundwater, a total of 332 groundwater samples, including 147 pore groundwater, 95 fissure groundwater and 90 karst groundwater, were collected and hydrochemical parameters were applied to assess the groundwater quality and human health risks caused by oral ingestion. The results showed that the major chemical components of groundwater in Xin’an spring basin were HCO3−, SO42−, NO3−, Cl−, Ca2+, Mg2+, Na+, total hardness (TH), and total dissolved solids (TDS). The contents of TDS, TH, SO42−, NO3−, F−, Fe, Mn, Pb, and As in groundwater were exceed the standard of groundwater quality (SGQ) limits. The main hydrochemical types of groundwater were HCO3-Ca·Mg and SO4·Cl–Ca·Mg. The factors controlling the groundwater chemistry mainly were mineral weathering, evaporation, cation exchange, and anthropogenic input. The results of water quality assessment showed that the karst and fissure groundwater in study area was mainly excellent-good quality water, while pore groundwater was mainly good-medium quality water. The poor and extremely poor quality water was mainly distributed in Changzhi basin, and the greater contribution made by Pb, Mn, NO3−, Fe, SO42−, TH and TDS. The range of hazard index (HI) values of groundwater was 0.28 to 27.79, and the HI values mainly contributed by NO3−, F−, As, ingestion rate (IR) and exposure duration (ED). The cumulative carcinogenic risk (CCR) values ranged from 1.5 × 10–7 to 2.78 × 10–3, and the greater contribution made by Cr, As, Cd, IR and ED. The results of health risk assessment suggested that some parts of the study region may pose a significant non-carcinogenic risk and a high probability in developing cancer to local residents, and infants were at greatest risk to health, followed by children and adults, while teenagers were at least at risk. This study will provide a deeper insight into the water quality situation and geochemical evolution of groundwater in Xin’an spring area, and will assist decision-makers to formulate management strategies of drinking water safety for the study area.

Nitrate pollution of groundwater has become a global concern as it can affect drinking water quality and human health. In this paper, an extensive hydrochemical investigation was performed to assess the spatial distribution, source identification, and health risk of groundwater nitrate pollution in the Subei Lake basin. The prevalent pollutant, nitrate (NO 3 − ), was identified based on descriptive statistical method and box plots, and most of the other parameters of groundwater samples met water standards and can be used for drinking purpose. The results showed that nearly 23.53% of groundwater samples displays the NO 3 − concentrations higher than the limit of 50 mg/L recommended by the World Health Organization, and the highest nitrate content (199 mg/L) is mainly distributed around the Mukai Lake. Piper triangle diagram demonstrated that the dominated anions of hydrochemical types exhibit a gradual evolving trend from HCO 3 − to SO 4 2− and Cl − with increasing nitrate concentration. The correspondence analysis suggested that agricultural activities are identified as the most possible source of nitrate contamination, while the higher content of other parameters in individual groundwater samples may be controlled by natural factors. The impacts of pollutant NO 3 − on human health were quantified using human health risk assessment method, and results showed that the order of non-carcinogenic health risk values through drinking water intake is Infants>Children>Adult males>Adult females, and 65%, 53%, 41%, and 35% of samples exceed the acceptable risk level (hazard quotient=1), respectively. The main findings obtained from this study can provide valuable insight on drinking water safety and groundwater pollution prevention.

The present study is a part of hard rock aquifer of Telangana, South India, where the groundwater is withdrawn heavily for drinking, irrigation, and small-scale industrial purposes. Geochemical characteristics explain the chemical processes, which control the groundwater chemistry and consequently the groundwater quality, while the chemical quality of groundwater is adversely affected by anthropogenic activities, which damage the water environment. The focus of the present study was, thus, to know the origin of geochemical characteristics and also to evaluate the quality of groundwater for various purposes for taking the suitable remedial measures to provide safe water to the local community. Geochemical relations (GR) and hierarchical cluster analysis (HCA) were used to assess the geochemical characteristics. Entropy weighted groundwater quality index (EWGQI), United States Soil Salinity Laboratory Staff (USSLS)’s diagram, and groundwater quality criteria for water supply pipes (GQCW) were used to evaluate the groundwater quality for drinking, irrigation, and industrial purposes, respectively. The study found that the water-rock interactions associated with ion exchange and evaporation were the prime geochemical factors controlling the geochemical characteristics and the anthropogenic activities as the secondary factor. These observations were further supported by HCA. According to the EWGQI, 34.97% of the spatial area was found to have the poor and very poor groundwater quality zones for drinking purpose, because of the dominance of TDS, Na + , Cl − , SO 4 2 − , NO 3 − , and F − contents in the groundwater system. Based on the USSLS’s diagram, 79.55% of the present study area was observed to be poor and very poor water quality type for irrigation utilization due to salinity hazard. The GQCW demonstrated that the 7.91% and 8.82% of the areas were not suitable for industrial purpose due to influence of incrustation based on HCO 3 − and SO 4 2 − , respectively, and 1.85%, 12.32%, and 1.25 of the areas are unfit due to influence of corrosion based on pH, TDS, and Cl − , respectively. Therefore, boiling, activated carbon filter, rainwater harvesting, suitable coatings on metal surfaces of water supply pipes, etc. are the important suggested effective strategic measures to provide safe water for drinking, irrigation, and industrial purposes.

Assessment of pollutants and groundwater quality has attracted much attention worldwide as it is directly linked to human health. In view of this, groundwater samples were collected from a part of Guntur district, Andhra Pradesh, India, to assess groundwater pollution levels and groundwater quality, using Water Pollution Index (WPI) and Water Quality Index (WQI), respectively. Groundwater chemical composition results indicated that groundwater quality was characterized by alkaline and very hard categories with Na+ > Mg2+ > Ca2+ > K+: HCO3- > Cl - > SO42- > NO3- > F - facies. TDS, TH, Ca2+, Mg2+, Na+, K+, HCO3-, Cl -, NO3-, and F - were above the recommended threshold limits in 100%, 100%, 35%, 100%, 100%, 100%, 100%, 95%, 85%, and 75% of groundwater samples, respectively, for drinking purposes. The geochemical diagram showed base exchange water type (Na+–HCO3-) in 50% of groundwater samples resulting from weathering and dissolution of plagioclase feldspars under the influence of soil CO2 and ion exchange process. The remaining groundwater samples showed saline water type (Na+–Cl -) due to the influence of evaporation, sewage sludge, septic tank leaks, irrigation-return flows, agrochemicals, etc. Ionic relationships of Ca2+/Na+vs HCO3-/Na+, Ca2+/Na+vs Mg2+/Na+, higher Na+ than Ca2+, and occurrence of CaCO3 concretions further supported geogenic processes that alter groundwater chemistry. The positive linear trend of TDS vs Cl - + NO3-/HCO3- and the relationship of TDS with TH showed anthropogenic input as the main factor, causing groundwater contamination. The WPI indicated two categories of water quality: moderately polluted water (WPI: 0.75–1.00) and highly polluted water (WPI: > 1.00) in 60% and 40% of groundwater samples, which were 81.49% and 18.51% of the study area, respectively. Hierarchical cluster analysis identified three clusters: Cluster I (pH, F -, Ca2+, K+, NO3-, Na+, and SO42−), Cluster II (TH, Mg2+, Cl -, and HCO3-), and Cluster III (TDS) support WPI. Following WQI, 75% and 25% of groundwater samples fell under poor groundwater quality type (WQI: 100–200) and very poor groundwater quality type (> 200), respectively, especially due to the increased concentrations of Mg2+, Na+, K+, HCO32−, Cl -, NO3-, and F - ions, thereby increasing salinity (TDS) and hardness (TH) in groundwater. Spatially, they covered 85.84% and 14.06% of the study area. The quality of this groundwater is not suitable for drinking purposes. Therefore, the present study suggests preventive measures (safe drinking water supply, desalinization, defluoridation, denitrification, calcium food, and rainwater harvesting) to protect human health.

Groundwater quality research is extremely important for supporting the safety of the water supply and human health in arid and semi-arid areas of China. This review article was constructed to report the latest research progress of groundwater quality in western China where groundwater quality is undergoing fast deterioration because of fast economic development and extensive anthropogenic activities. The opportunities brought by increasing public awareness of groundwater quality protection were also highlighted and discussed. To guide and promote further development of groundwater quality research in China, especially in western China, ten key groundwater quality research fields were proposed. The review shows that the intensification of human activities and the associated impacts on groundwater quality in China, especially in western China, has made groundwater quality research increasingly important, and has caught the attention of local, national, and international agencies and scholars. China has achieved some progress in groundwater quality research in terms of national and regional laws, regulations, and financial supports. The future of groundwater quality research in China, especially in western China, is promising reflected by the opportunities highlighted. The key research fields proposed in this article may also inform groundwater quality protection and management at the national and international level.