Littérature scientifique sur le sujet « Groundwater hydrochemical characterization »

Bottled waters have been becoming increasingly popular in Korea over the last two decades due to the high demand for safe drinking water. Hydrochemical characterization of groundwater is essential for understanding quality properties of bottled waters. We investigated hydrochemistry of 60 manufacture factories for bottled waters in relation to geology. The mean EC value is highest in groundwaters of Ogcheon metamorphic rocks (213.6 μS/cm) > Precambrian gneiss (177.8 μS/cm) > Cretaceous granite (160.4 μS/cm) > Jurassic granite (131.3 μS/cm) > Quaternary Jeju Island volcanic rocks (99.2 μS/cm). The groundwater types are commonly classified as Ca-HCO3, Ca-Na-HCO3, or Ca-Mg-HCO3 types depending on bed rocks. Based on correlation matrix, the groundwater chemistry was controlled by water–rock interactions. We established relationships between groundwater compositions and bedrock geology in Korea.

Principal component analysis is applied to 309 groundwater chemical data information from wells in the Serra Geral Aquifer System. Correlations among seven hydrochemical parameters are statistically examined. A four-component model is suggested and explains 81% of total variance. Component 1 represents calcium-magnesium bicarbonated groundwaters with long time of residence. Component 2 represents sulfated and chlorinated calcium and sodium groundwaters; Component 3 represents sodium bicarbonated groundwaters; and Component 4 is characterized by sodium sulfated with high fluoride facies. The components' spatial distribution shows high fluoride concentration along analyzed tectonic fault system and aligned on northeast direction in other areas, suggesting other hydrogeological fault systems. High fluoride concentration increases according to groundwater pumping depth. The Principal Component Analysis reveals features of the groundwater mixture and individualizes water facies. In this scenery, it can be determined hydrogeological blocks associated with tectonic fault system here introduced.

Groundwater is a valuable natural resource and an important source of drinking and domestic water supply. There are two types of groundwater in the Mesta River Basin: HCO3- > Ca2++Mg2+ (1st type waters) and HCO3- < Ca2++Mg2+ < HCO3-+SO42- (2nd type waters). The waters of the first type formed in the silicate rocks, are widespread in the high mountain, mountain and low mountain area. These waters are attached to the region of regional fracturing of the Precambrian metamorphic complex represented by gneisses, granitogneisses, amphibolites and to the fractured environment of the southern Bulgarian granites and granitoids, quartzites, conglomerates and marls of the Paleozoic. The waters of the second type are characteristic of the valleys covered by Pliocene and Quaternary sediments with minimal precipitation. Groundwater from the Mesta River catchment area is mainly hydrocarbonate-calcium-magnesium with high sodium content in the southern part of the catchment area. The content of anions in groundwater is in the sequence: HCO3- > SO42-> Cl-. The cations are arranged in the order: Ca2++Mg2+ > (Na++K+) or Ca2+ > (Na++K+) > Mg2+. Groundwater is very soft to moderately hard, fresh, with TDS content up to 0.5 g/l and chloride content below 10 mg/l.

Georgia is rich in groundwater deposits, which renew over time and are characterized by the best indicators of water quality and a stable regime. Groundwater is one of the main natural productive forces of Georgia, which plays an important role in the economic development and export industry. During 2015–2020, chemical composition of the Nabeghlavi mineral waters has been studied by the means of the modern unified methods. Almost all data from previous chemical analyzes have also been retrieved and systematized/collated. Using mathematical statistical analysis, the maximum, minimum, and mean arithmetic values of the major and specific components of water and the empirical deviation from the arithmetic mean have been calculated. Though comparison of the recent and historic data on chemical composition, based on the results of statistical analysis of the major ions, the natural fluctuation limits of the waters and stability of waters from all exploitation drill holes have been shown. According to the chemical composition and total mineralization there are three groups of waters in fresh and low mineralized category. It is shown that chemical composition of water from all exploitation drill holes meets requirements for the natural mineral water category, both the normative document of Georgia and directive of the European Commission.

Abstract. The understanding of runoff generation mechanisms is crucial for the sustainable management of river basins such as the allocation of water resources or the prediction of floods and droughts. However, identifying the mechanisms of runoff generation has been a challenging task, even more so in arid and semi-arid areas where high rainfall and streamflow variability, high evaporation rates, and deep groundwater reservoirs increase the complexity of hydrological process dynamics. Isotope and hydrochemical tracers have proven to be useful in identifying runoff components and their characteristics. Moreover, although widely used in humid-temperate regions, isotope hydrograph separations have not been studied in detail in arid and semi-arid areas. Thus the purpose of this study is to determine if isotope hydrograph separations are suitable for the quantification and characterization of runoff components in a semi-arid catchment considering the hydrological complexities of these regions. Through a hydrochemical characterization of the surface water and groundwater sources of the catchment and two and three component hydrograph separations, runoff components of the Kaap Catchment in South Africa were quantified using both, isotope and hydrochemical tracers. No major disadvantages while using isotope tracers over hydrochemical tracers were found. Hydrograph separation results showed that runoff in the Kaap catchment is mainly generated by groundwater sources. Two-component hydrograph separations revealed groundwater contributions between 64 and 98% of total runoff. By means of three-component hydrograph separations, runoff components were further separated into direct runoff, shallow and deep groundwater components. Direct runoff, defined as the direct precipitation on the stream channel and overland flow, contributed up to 41% of total runoff during wet catchment conditions. Shallow groundwater defined as the soil water and near-surface water component, contributed up to 45% of total runoff, and deep groundwater contributed up to 84% of total runoff. A strong correlation for the four studied events was found between the antecedent precipitation conditions and direct runoff. These findings suggest that direct runoff is enhanced by wetter conditions in the catchment which trigger saturation excess overland flow as observed in the hydrograph separations.

Water resources are scarce in arid or semiarid areas; groundwater is an important water source to maintain residents’ lives and the social economy; and identifying the hydrogeochemical characteristics of groundwater and its seasonal changes is a prerequisite for sustainable use and protection of groundwater. This study takes the Hongjiannao Basin as an example, and the Piper diagram, the Gibbs diagram, the Gaillardet diagram, the Chlor-alkali index, the saturation index, and the ion ratio were used to analyze the hydrogeochemical characteristics of groundwater. Meanwhile, based on self-organizing maps (SOM), quantification error (QE), topological error (TE), and the K-means algorithm, groundwater chemical data analysis was carried out to explore its seasonal variability. The results show that (1) the formation of groundwater chemistry in the study area was controlled by water–rock interactions and cation exchange, and the hydrochemical facies were HCO3-Ca type, HCO3-Na type, and Cl-Na type. (2) Groundwater chemical composition was mainly controlled by silicate weathering and carbonate dissolution, and the dissolution of halite, gypsum, and fluorite dominated the contribution of ions, while most dolomite and calcite were in a precipitated state or were reactive minerals. (3) All groundwater samples in wet and dry seasons were divided into five clusters, and the hydrochemical facies of clusters 1, 2, and 3 were HCO3-Ca type; cluster 4 was HCO3-Na type; and cluster 5 was Cl-Na type. (4) Thirty samples changed in the same clusters, and the groundwater chemistry characteristics of nine samples showed obvious seasonal variability, while the seasonal changes of groundwater hydrogeochemical characteristics were not significant.

Abstract. The understanding of runoff generation mechanisms is crucial for the sustainable management of river basins such as the allocation of water resources or the prediction of floods and droughts. However, identifying the mechanisms of runoff generation has been a challenging task, even more so in arid and semi-arid areas where high rainfall and streamflow variability, high evaporation rates, and deep groundwater reservoirs may increase the complexity of hydrological process dynamics. Isotope and hydrochemical tracers have proven to be useful in identifying runoff components and their characteristics. Moreover, although widely used in humid temperate regions, isotope hydrograph separations have not been studied in detail in arid and semi-arid areas. Thus the purpose of this study is to determine whether isotope hydrograph separations are suitable for the quantification and characterization of runoff components in a semi-arid catchment considering the hydrological complexities of these regions. Through a hydrochemical characterization of the surface water and groundwater sources of the catchment and two- and three-component hydrograph separations, runoff components of the Kaap catchment in South Africa were quantified using both isotope and hydrochemical tracers. No major disadvantages while using isotope tracers over hydrochemical tracers were found. Hydrograph separation results showed that runoff in the Kaap catchment is mainly generated by groundwater sources. Two-component hydrograph separations revealed groundwater contributions of between 64 and 98 % of total runoff. By means of three-component hydrograph separations, runoff components were further separated into direct runoff, shallow and deep groundwater components. Direct runoff, defined as the direct precipitation on the stream channel and overland flow, contributed up to 41 % of total runoff during wet catchment conditions. Shallow groundwater defined as the soil water and near-surface water component (and potentially surface runoff) contributed up to 45 % of total runoff, and deep groundwater contributed up to 84 % of total runoff. A strong correlation for the four studied events was found between the antecedent precipitation conditions and direct runoff. These findings suggest that direct runoff is enhanced by wetter conditions in the catchment that trigger saturation excess overland flow as observed in the hydrograph separations.

This study deals with hydrochemical assessment of groundwater within the lithological framework underlain Zamfara State, Northwestern Nigeria with the aim of ascertaining its suitability for human consumption. Groundwater samples were collected from boreholes tapping the aquifer of the area and analyzed for various physico-chemical parameters, such as total dissolve solids, electrical conductivity (Ec), pH, temperature, Na+, K+, Ca2+, Mg2+, HCO3, Cl-, SO4, NO3, PO4, and trace elements (Mn, Cu, Zn, Fe, Pb and Cr). The results obtained were subjected to multivariate statistical analysis, water quality index method, and hydrochemical variation plots for proper characterization. As far as suitability is concerned most of the studied physic-chemical parameters trace elements (iron, lead and chromium ions) revealed average concentrations lower than the permissible limit set for domestic water use by World Health Organization. However, the compiled overall water quality index for the studied groundwater shows ‘very poor water quality’. Due to the fact that WQI rating reflect the composite influence of different water quality parameters. The result of the multivariate statistical analysis, as applied to the chemical data set of the studied groundwater provides an insight into the underlying controlling hydrochemical processes in the area. Four factors including factor-1 (total hardness, chloride, nitrate, manganese, bicarbonate and alkalinity), factor-2 (TDS, conductivity, total hardness, magnesium and calcium), factor-3 (Temperature, sodium, potassium, copper, zinc, iron and chromium), factor-4 (calcium, magnesium and nitrate) represents the signatures from dissolution of bedrock through which the groundwater passes, ionic mixing, leaching from the lateritic overburden, agricultural activities (fertilizer application) and effluent from waste dumpsites in the study area. The distribution of major ions in the groundwater shows relative abundance of cations: Na++K+ > Ca2+ > Mg2+; while the relative abundance of the anions is: Cl- > HCO3- > SO42-. Groundwater in the aquifer of the study area are majorly of evolved type with mixing of ionic concentrations. Alkali’s are more in abundant to that of alkaline earth, while Cl and HCO3 dominate SO4 and NO3 concentration. The water samples are basically ‘Alkali waters’ with ‘Earth Alkaline’ components that are predominantly HCO3- and Cl-.The relative abundance of the three (3) dominant water types are as thus: Na-HCO3-Cl > Ca-Mg-HCO3-Cl > Na-Ca-Cl. Simple mineral dissolution or mixing processes is mainly responsible for the variation in the hydrochemistry of the groundwater of the study area.

A groundwater chemistry sampling campaign was run over two sampling seasons in 2018. Groundwater samples were taken across the region of southern Mozambique, between the towns of Namaacha, Catuane, Ponta do Ouro and Marracuene. Major anions and cations were analyzed by two labs at Stellenbosch University, and stable isotopes of oxygen and hydrogen, and radiogenic isotopes of strontium were analyzed at the Department of Geological Sciences at the University of Cape Town. The aim of this study was to characterize the isotopic and hydrochemical composition of groundwater in the southern Mozambique study area, using major ions and stable isotopes. Samples were categorized into different zones based on the underlying geology in which the borehole was sited. Overall, the dominant anions and cations are: Cl>HCO3>SO4 and Na> Ca=Mg>K. 68% of samples plotted in the Na-Cl water type, whilst 30% plotted in the Na-HCO3 water type of the Piper and Chadha diagrams. Salinization is the mechanism controlling the Na-Cl water types, whilst recharge is mechanism controlling the Na-HCO3 water types. Saturation indices of calcite, dolomite, halite, and gypsum. Saturation indices were calculated using the thermodynamic software PHREEQC. All samples were undersaturated with respect to gypsum and halite, suggesting that the conditions were thermodynamically favored for their dissolution. Samples that were from boreholes that plotted in the limestone layers and >40m depth in basalts, and quaternary sediments were oversaturated with respect to calcite and dolomite, indicating that the conditions were thermodynamically favored for their precipitation out of solution. Samples that plotted in the rhyolite, shallow basalts and quaternary sediments were undersaturated with respect to calcite and dolomite, suggesting dissolution into solution. Sixty-two percent of sample had an NA/Cl ration greater than one, indicating silicate weathering as a major process affecting the chemical character of the water. Samples in the basalts however had Na/Cl ratios less than one, and δ 2H and δ 18O values out of the range of seawater, suggesting ion exchange as a process affecting the chemistry of groundwater in these areas. Since there is no established Local Meteoric Water Line (LMWL) in the area, LMWL from Pretoria and Durban were used as proxies, and the Global Meteoric Water Line (GMWL) was also plotted. Samples in the rhyolites, basalts and quaternary sediments has high d-excess values, and showed a strong evaporation trend. The mechanisms for groundwater salinization in these areas is strongly influenced by evapoconcentaion effects. Geographical features such as seasonal variation, latitude, elevation and distance from coast do not appear to be a major factor affecting the isotopic composition of the groundwaters. The strontium isotopes and elemental strontium concentrations indicate that groundwater mixing likely occurred in each zone, however no end-members were established.

The present study concerns the analysis of the hydrogeology and the hydrogeochemistry of the As, Fe, Mn rich groundwater of the alluvial multi-layer aquifer in the lower Po Plain (northern Italy), referring specifically to the territory of Cremona. The main aim is to understand the origins (natural or anthropic) and mechanisms of the high groundwater As, Fe and Mn concentrations. The specific study area is located near the confluence between Adda and Po rivers. It covers a 50 km2 wide area around the urban territory of Cremona. The considered aquifer depths are around 200-250 m. The applied methodology involves the (a) collection of historical data related to water quality, water levels and well logs; (b) storage of collected data in specific databases and geographical information systems; (c) design and execution of two field surveys of water levels and water quality, realized in July 2010 and July 2012; (d) construction of a 3D model of aquifer hydrogeological properties (deposits texture, hydraulic conductivity and effective porosity), built by means of ordinary kriging interpolation of numerical values derived from the coding of well logs; (e) analysis of the hydrodynamic properties of the system; (f) analysis of water quality data (both field and historical data) considering the hydrogeological and hydrodynamic properties of the aquifer system; (g) implementation of a 1D reactive transport model in order to better understand the hydrogeochemical mechanisms in the system; (h) elaboration of a general hydrogeochemical conceptual model concerning possible origins and chemical mechanisms for the high groundwater As, Fe, Mn and NH4 concentrations, considering also possible anthropogenic influences; (i) development of management tools, as natural background levels derivation, supporting groundwater resources protection by public authorities. The 3D aquifer modelling underlines the presence of an alternation of sandy layers (K = 10-3-10-5 m/s) and silty-clayey layers (K = 10-7-10-8 m/s) with significant peat deposits and leads to the identification of 5 aquifer units. In relation to the hydrodynamic properties analysis, these 5 units are classified as (1) phreatic (F), from 0 to 25 m b.s., (2) semi-confined (S) from 30 to 50 m b.s., (3) confined 1 (C1) from 65 to 85 m b.s., (4) confined 2 (C2) from 100 to 150 m b.s. and (5) confined 3 (C3) from 160 to 250 m b.s.. The aquifer F can locally have semi-confined characteristic due to the presence of superficial silty-clayey deposits, while in the other zones it remains phreatic. The analysis of field and historical data of water quality underlines the general presence of reduced hydrochemical facies, characterized by high concentration of As, Fe, Mn and NH4, with the exception of the zones with phreatic conditions in aquifer F, where oxidized facies are identified. In particular, the survey of July 2010 points out high As concentrations (ranging from 1 to 180 μg/L), especially in the 30-100 m depth range, corresponding to aquifers S and C1. High concentrations of Fe and Mn are also found, they range from 100 to 6000 μg/L and from 10 to 1200 μg/L, respectively. The higher concentrations are found in superficial aquifers: in aquifer F for Mn and in aquifers F and S for Fe. NH4 is also found with high concentrations (1-5 mg/L, up to 18.9 mg/L) from aquifer S to C3. The measurements of July 2010 can represent the natural background of As, Fe, Mn and NH4 because no direct sources or indirect anthropogenic influences are found. The survey of July 2012 generally confirms the hydrochemical characterization based on July 2010 data. In the analysis of the hydrochemical historical data, a separation between the data referred to the natural background and to anthropogenic influences is done. Pollutions by hydrocarbons and organic matter in general can be considered as indirect human influences on As, Fe, Mn and NH4 concentrations, as reported by previous studies. The analysis of historical chemical data referred to the natural background generally confirms the hydrochemical characterization emerged from the data of July 2010 survey. The analysis of historical data also points out a probable anthropogenic influence on As, Fe, Mn and NH4 concentrations in two sites located in the study area: an oil refinery, affected by hydrocarbons pollution, and a municipal solid waste landfill, with probable organic leachate spills. In order to understand the origin and the mechanisms of the high As, Fe, Mn and NH4 concentrations, a hydrogeochemical conceptual model is implemented. The conceptual model considers the process of natural organic matter degradation (i.e. peat) as primary control factor on high As, Fe, Mn and NH4 concentrations. Degradation of peat is associated with the consecutive reduction of O2, NO3-, Mn(IV), Fe(III), SO42-, CO2. The reductive dissolution of Mn and Fe oxides (contained in the aquifer sediments) leads to high concentrations of dissolved Fe and Mn, but also to high concentrations of dissolved As, which is generally sorbed on Mn and Fe oxides. Dissolved As concentration can be also lowered by different processes (co-precipitation of As in iron sulfides, precipitation of arsenic sulfides, sorption of As on the remaining Fe-oxides and Mn-oxides, etc.). NH4 is released from the degradation of organic nitrogen of peat. Therefore, a natural origin of As, Fe, Mn and NH4 can be assumed. In order to understand if the hydrogeochemical conceptual model, based on literature, could be reliable on the present case study, a 1D reactive transport model, using PHREEQC code, is implemented. The modelled concentrations result in good agreement with the measured concentrations (July 2010). This result could support the validity of the conceptual model. In addiction, isotope and microbiological analysis, executed in the survey of July 2012, confirms the natural origin of NH4 and the occurring of Fe-oxide and sulfate reduction in the studied system. In conclusion, the present work can contribute to understand origins and mechanisms of high groundwater As, Fe, Mn and NH4 concentrations in the lower Po Plain, supporting the management and protection of groundwater resources by public authorities.