Water-rock Interaction Processes Research Articles

Sources and behavior of trace elements in groundwater in the South Eastern Desert, Egypt.

Due to water scarcity, the groundwater will represent an essential source of water in many communities worldwide. This study was carried out to investigate the main hydrogeochemical characteristic of trace elements composition, their sources, and its vulnerability in groundwater to the human population. Fifteen groundwater samples were collected from boreholes and hand dug wells from the South Eastern Desert, Egypt, and analyzed for Al, As, B, Fe, Mn, Cd, Co, Cr, Cu, Hg, Ni, Pb, Rb, Sb, Sr, Th, U, V, and Zn using inductively coupled plasma mass spectrometry. Multivariate analyses were applied to identify the distribution and potential source of trace elements. The groundwater is tapped from the Miocene and the fractured basement rock aquifers. The mean concentrations of trace elements exceed the guideline values of all organizations, except in some wells for Zn, Cu, and Co. Cationic trace elements declined in the order of Mn > Fe > Zn > Al > V > Ni > Rb > Sr > U > Cu > Cr > Co > Cd > Pb > Th > Sb > Hg. Oxyanions As (mean 15.48 mg/L) and B (mean 1.24 mg/L) showed very high concentrations and higher than the average WHO concentrations in water suggesting potential adverse toxicity to all aquatic organisms. Five factor analyses indicated that different geochemical contributions are involved in the chemical characteristics of groundwater in the study area. Water-rock interaction and dissolution processes in bed rocks from different coastal Miocene deposits, meta-volcanics, basic-ultrabasic rocks, granitic and meta-sediments, seawater intrusion, residential wastes, and mining activities, in addition to the pH/Eh conditions, adsorption, and surface complexation during the chemical weathering are the main factors influence the trace elements distribution in groundwater. Results from this study for the six different groundwater aquifers are a unique insight into the sources and mobility of the observed trace elements in the groundwater and can be used in the assessment of contamination for drinking water wells. The association of trace elements from different aquifers might be useful in tracers studies of water-rock interaction. Due to the enrichment of trace elements in nearshore and crystalline groundwater aquifers in the study area and in similar areas worldwide, treatment technologies, and sustainable water management processes should be applied to prevent severe risks to the communities.

Hydrochemical and geological model of the Bañitos-Gollete geothermal system in Valle del Cura, main Andes Cordillera of San Juan, Argentina

The main characteristics of geothermal systems at flat-slab segments are not well understood. This work reports a geological and fluid geochemistry survey at the southern thermal areas of the isolated Valle del Cura, located at the Frontal Andes Cordillera over the Pampean flat-slab. Deep circulation along deep-rooted N-S trend faults and fractures likely heats meteoric water through a locally anomalous geothermal gradient related to scattering Quaternary volcanism. Hot springs discharge up to 60 °C Na-Cl bearing water with high TDS (>5000 mg/L) from meteoric origin, according to the isotopic composition. At the top of an 11 m height travertine fissure ridge, intense gas flux is mainly composed of CO2. Enthalpy model, δD, and B suggest a similar evolution trend for the Bañitos and Gollete thermal waters, clearly separated by the trend evidenced for thermal waters of the northern thermal sites of the Valle del Cura (e.g., Despoblados). Reservoir probably develops below 2–3 km depth hosted by the ignimbrites of the Choiyoi Group. Cation and multicomponent geothermometers estimate a temperature of ~140 °C and quartz + albite + calcite + chlorite ± beidellite-Na ± montmorillonite-K was inferred as the mineral assemblage. Very low tritium contents and δ18O isotopic shift might be because of the water-rock interaction process at low permeability conditions. These findings are consistent with a long residence, fault-controlled deep fluid circulation path. During their rise, the thermal waters likely interacted with cold waters at the base of the Oligocene volcanic deposits, where secondary processes such as calcite and silica precipitation may occur. Further investigations are required to assess the geothermal potential of the study areas, but we hope that this study may represent an incentive for other detailed investigations to evaluate the geothermal systems over flat-slab geothermal plays.

Avaliação geoquímica das águas envasadas de aquíferos cristalinos no sul e sudeste do Brasil

Os mecanismos relacionados à interação rocha-água são importantes processos para o entendimento da qualidade da água subterrânea. A composição química de 38 marcas de água envasada dos aquíferos cristalinos nas regiões Sul e Sudeste do Brasil foram avaliadas para um diagnóstico preliminar dos processos de interação rocha-água atuantes. Os resultados apontam que as diversas amostras de água apresentam graus distintos de interação com a rocha, e que estes podem ser mensurados pela concentração do íon HCO3-. A análise exploratória indica que águas pouco mineralizadas, provavelmente provenientes de recarga recente, são do tipo misto. Por outro lado, águas mais mineralizadas são do tipo bicarbonatado, variando do sódico ao cálcico, ambas com elevada proporção de magnésio. A despeito da ampla variabilidade composicional das rochas que compõe os aquíferos analisados, nota-se que a assembleia mineralógica que mais contribui para a composição da água são os silicatos cálcio-magnesianos, representados predominantemente pela hornblenda. O sódio e parte do cálcio na água são provenientes da hidrólise de plagioclásios, enquanto o potássio é proveniente da dissolução de feldspato potássico.

Assessment of Groundwater Salinity in Aloha Pliocene Aquifer of Marbella (Málaga)

In order to study the origin of the salinity and the salinization mechanisms that operate in the Pliocene Aloha Aquifer, hydrochemical and isotopic environmental techniques have been used, due to their known effectiveness and usefulness in the identification of water-rock interaction processes, location of recharge zones and its origin. Analyzing major ions, trace elements, ionic ratios and isotopic ratios of the elements of the water molecule, stable isotopes (δ18O and δ2H) and δ18O and δ34S of sulphate. Previous hydrochemical studies of the Pliocene Aloha Aquifer indicate high concentrations of Cl- and Na+ as well as HCO3, SO4 and Ca that should be indicated the interaction with waters of highersalinity, but also with rocks (longer residence time in the aquifer). Therefore, as a starting hypothesis, two possible origins of the high salinity are considered: mixture with seawater or connate waters stored in Pliocene formations. Finally, the study confirmed that the salinity of the Aloha Aquifer is of a localcharacteristic and not due to seawater intrusion.

Imaging and integration of hydrogeochemical data for characterization of groundwater quality around Jabalpur, India

Hydrogeochemical surveys were conducted as a part of uranium exploration around the city of Jabalpur and adjacent areas. The present study aimed for integrating geology structures and their quality assessments. Hydrogeochemical images show spatial distribution of physicochemical parameters (pH, electrical conductivity and total hardness (TH)], cations (Rn, Na, K, Ca, Mg, U,) and anions (Cl, CO3, HCO3, SO4, PO4). The varying chemical constituents of groundwater are due to water–rock interaction processes like dissolution, ion exchange, sorption–desorption along the hydraulic gradients and surface slope variation. The groundwater is partially suitable for drinking purposes and public health because the higher concentrations of total dissolved solids (TDS), TH, Ca, Mg, U and Rn, whereas it is suitable for irrigation and livestock. Sodium %, sodium adsorption ratio (SAR), potential salinity, permeability index, Mg ratio and chloro-alkaline index have been determined for irrigation suitability. The corrosivity ratio is calculated to determine the pipes to be used for the water supply lines. The dominant hydrogeochemical facies are HCO3 Ca-Mg type.

Anomalous concentrations of arsenic, fluoride and radon in volcanic-sedimentary aquifers from central Italy: Quality indexes for management of the water resource

659 water samples from springs and wells in the Sabatini and Vicano-Cimino Volcanic Districts (central Italy) were analyzed for arsenic (As), fluoride (F−) and radon (222Rn) concentrations. Waters mostly sourced from a shallow and cold aquifer hosted within volcanic rocks, which represents the main public drinking water supply. Cold waters from perched aquifers within sedimentary formations and thermal waters related to a deep hydrothermal reservoir were also analyzed. The highest concentrations of As and F− were measured in the thermal waters and attributed to their enhanced mobility during water-rock interaction processes at hydrothermal temperatures. Relatively high concentrations of As and F− were also recorded in those springs and wells discharging from the volcanic aquifer, whereas waters hosted in the sedimentary units showed significantly lower contents. About 60% (As) and 25% (F−) of cold waters from the volcanic aquifer exceeded the maximum allowable concentrations for human consumption. Such anomalously high levels of geogenic pollutants were caused by mixing with fluids upwelling through faulted zones from the hydrothermal reservoir. Chemical weathering of volcanic rocks and groundwater flow path were also considered to contribute to the observed concentrations. Cold waters from the volcanic aquifer showed the highest 222Rn concentrations, resulting from the high contents of Rn-generating radionuclides in the volcanic units. Approximately 22% of these waters exceeded the recommended value for human consumption. A specific Quality Index (QI), comprised between 1 (very low) and 4 (very high), was computed for each water on the basis of As, F− and 222Rn concentrations and visualized through a spatial distribution map processed by means of geostatistical techniques. This map and the specific As, F− and 222Rn maps can be regarded as useful tools for water management by local authorities to both improve intervention plans in contaminated sectors and identify new water resources suitable for human consumption.

Groundwater From Abandoned Mines of the Partizansk Coal Basin, Primorye: Isotope-Geochemical Features of Composition and Regularities of Formation

The underground waters from the abandoned mines of the Partizansk coal basin were subjected to isotope-geochemical study to investigate their compositional features and regularities of their formation. The study has shown that flooding of the mines caused origin in the natural and industrial structures of a succession of water solutions with changeable composition: HCO3-Ca→HCO3-Mg→HCO3-Na→HCO3-SO4-Na→SO4-Na. The sulfur variability here is conditioned by the amount and level of oxidation of pyrite inherent in coals, bacterial component is important as well. The natural and industrial structures under consideration demonstrate zonality of geochemical conditions. Deeper horizons are the place where aerobic systems transit into anaerobic ones, and predominantly deoxidizing environment stimulates generation of biochemical natural gases, such as CH4, H2S, CO2, and H2. It has been established also that transformation of groundwater composition influences the rare-earths behavior; distribution of the dissolved REE depends on the water type and is controlled by the water-rock interaction processes and equilibrium – non-equilibrium state. Mineralization of the waters under study correlates with δ1O and δD parameters, and variation of their values can be used for estimation of the water-rock interaction degree.

Origin of volcanic-hosted Mn-oxide mineralization from San Pietro Island (SW Sardinia, Italy): An integrated geochemical, mineralogical and isotopic study

The Mn-oxide mineralizations from Sardinia (Italy) represent examples of Mn deposits in a continental environment and, as such, their investigation can shed light on the genesis and characteristics of this deposit type, less studied than their more common oceanic counterpart. In this paper, the genetic mechanisms, the physical-chemical conditions and the origin of the mineralizing fluids are discussed for the volcanic-hosted Mn ores of the San Pietro Island (SW Sardinia), through an integrated geochemical, mineralogical and radiogenic isotope approach. New and published data are here examined on the basis of recent trace element discrimination schemes for Mn ores and a model for the genesis is proposed.The mineralogy of the alteration paragenesis (argillic facies) and the type of observed fluid inclusions (very small monophase liquid inclusions) suggest a circulation of mineralizing fluids characterized by weak acidic conditions (pH indicatively around 5) and relatively low temperature (<100–120 °C). Geochemical features such as the contents of transition metals (Mn, Fe, Cu, Co, Ni, Zn), and contents and ratios of rare-earth elements and yttrium (REY), suggest that the San Pietro Island Mn metallogenesis is the result of combined hydrothermal and hydrogenetic mechanisms of formation. The Pb isotope compositions of different Mn veins exhibit a significant spread that suggests the contribution of distinct mineralizing fluids, deriving their isotopic signature from both seawater and water-rock interaction processes.The possible model of formation of the San Pietro Mn mineralization can be viewed as a complex process, in which Mn-bearing fluids originated from remobilization of Mn oxides sequestered in shelf and slope sediments and/or from leaching of the older Cenozoic volcanic rocks that form the basement of the island. Fluid rise was due to hydrothermal convection, possibly related to the general thermal anomaly active in the area from 15 to 12 Ma, during the final stage of the intense Cenozoic volcanic activity of the Sulcis area (San Pietro, Sant'Antioco, Isola del Toro volcanic activity). The fluids were probably dominated by seawater, characterized by relatively low temperatures and acidic conditions, due to the input of H2S of hydrothermal origin. The Mn ore deposition occurred in relatively shallow water and oxidizing environment, following the pH neutralization induced by water-rock interaction processes.

An Assessment of Groundwater Contamination Risk with Radon Based on Clustering and Structural Models

There is currently some controversy in the scientific community regarding the efficiency of the water–rock interaction process in the contamination of radon in groundwater. In this study, some difficulties were found in the sampling phase. Many of the water collection points are used for human consumption. As such, some municipalities did not want to collaborate. When this natural contaminant is undetectable to the human sense and may cause pulmonary neoplasms in the long term, it is difficult to obtain collaboration from the municipalities concerned. To overcome this controversy, it is important to understand that geogenic, climatic, hydrological, and topographic features may contribute to the effective transfer of radon from rocks to groundwater. In brief, this new approach combines the radon transfer from the geological substrate to the groundwater circulation through hierarchic agglomerative clustering (HAC) and partial least squares-path modeling (PLS-PM) methods. The results show that some lithologies with higher radon production may not always contribute to noticeable groundwater contamination. In this group, the high-fracturing density confirms the recharge efficiency, and the physical-chemical properties of the hydraulic environment (electric conductivity) plays the main role of radon unavailability in the water intended for human consumption. Besides, the hydraulic turnover time of the springs can be considered an excellent radiological indicator in groundwater. In the absence of an anomalous radioactive source near the surface, it means that the high-turnover time of the springs leads to a low-radon concentration in the water. Besides linking high-risk areas with a short period required to free local flow discharges, this study exposes the virtues of a new perspective of a groundwater contamination risk modeling.

Water and dissolved gas geochemistry at Coatepeque, Ilopango and Chanmico volcanic lakes (El Salvador, Central America)

Coatepeque (on the E slope of Santa Ana Volcano), Ilopango (inside Ilopango Caldera) and Chanmico (associated with San Salvador Volcano) are volcanic lakes in El Salvador, showing a thermocline at a relatively shallow depth (from 30 to 40 m, from 20 to 40 m and from 5 to 15 m depth, respectively) and anoxic conditions below 33, 24 and 4 m depth, respectively. The Na+–Cl− composition of the Coatepeque and Ilopango lakes, displaying TDS values up to 1226 and 1216 mg/L, respectively, is likely due to hydrothermal fluids that feed these two lakes, as also confirmed by Cl−/Br− molar ratios ≤ 650, high As, B, Li and Si contents and Cl−/SO42− ratio > 1. The Mg2+–HCO3− water composition of Lake Chanmico, whose TDS values were between 566 and 856 mg/L, suggests water-rock interaction processes with mafic/ultramafic rocks variably affected by serpentinization processes, which produced high Mg2+, Si and B concentrations. Waters at depth were characterized by the presence of CO2 from an extra-lacustrine source, as suggested by δ13C-CO2 values significantly less negative than those typically related to biogenic processes, albeit this gas was found in smaller quantities when compared to those recorded in other meromictic lakes hosted in quiescent volcanic systems (e.g. Lake Kivu in DRC, Monticchio, Albano and Averno lakes in Italy, Hule and Rio Cuarto lakes in Costa Rica, Lake Pavin in France). The occurrence of CH4, whose concentrations in Lake Chanmico were up to two orders of magnitude higher than those recorded in Coatepeque and Ilopango lakes, suggests bacterial methanogenesis.

The Role of Water-Rock Interaction Processes in Soil Formation: Geochemical, Mineralogical, Geomorphological, and Engineering-Geological Aspects

The Role of Water-Rock Interaction Processes in Soil Formation: Geochemical, Mineralogical, Geomorphological, and Engineering-Geological Aspects

Multivariate analysis of trace elements leaching from coal and host rock

Trace elements in coal mine water have pollution potential to environmental water bodies. By process of water-rock interaction in coal seam and coal host rock, trace elements may immigrate from solid matrix to water, including oxidation, dissolution, ion-exchange, adsorption-desorption, etc. Water parameters and occurrence of trace elements in the solid matrix are keys to leaching behavior. In site observation and leaching experiments were designed and implemented so as to model these processes, analyze leaching behavior and mechanisms. The data composes a matrix by two dimensions, samples and trace elements, which were used to analyze trace element occurrence in coal, host rock and leaching behavior in the coal/rock leaching water, by method of multivariate analysis. Analytical results showed major occurrence of trace elements in the coal and host rock and key controlling mechanism of trace elements during water-rock interaction: in coal host rock seam, Se/Cd/Hg/As occurred in sulfide minerals, Be and V occurred in carbonate minerals, Cr and Pb occurred in clay minerals, respectively. Se, As and Hg immigrated through dissolution of sulfide minerals, Cr immigrated through transformation of clay minerals. In coal seam, Se/Cr/Pb occurred in clay minerals, As and Hg occurred in sulfide minerals. Se, Pb and Cr immigrated through transformation of clay minerals, As and Hg immigrated through dissolution of sulfide minerals, respectively.

Characteristics of interactions between black shale and water

Some geological engineering problems are caused by weathering of black shale within dispersed sulfide minerals (mainly pyrite), in which some weathering products such as acid water and expansive sulfates play an important role. These effects are essentially manifested through oxidation of sulfide minerals. Complex chemical reactions occur simultaneously and influence mutually in water-rock interaction process. Chemical weathering of black shale is a factor leading to engineering problems such as landslides and acid corrosion. The objectives of present study are to understand the process of water-rock interactions between black shale and water. The semi-immersion simulation experiment is mainly used to explore the chemical weathering characteristics of black shale under natural conditions.

Rare earth element contents in high pCO2 groundwaters of Sakhalin Island (the Far East of Russia)

The geochemistry of rare earth elements in cold, high pCO2 mineral waters was studied through the sampling of springs and boreholes of Sakhalin Island (the Russian Far East). The main common features of studied waters are the Na-Cl-HCO3 hydrochemical type, high TDS (6–20 g/L), alkaline pH (6.2–7.4), and reducing environment (-195 to +62 mV). The North American Shale Composite-normalized patterns of groundwaters exhibited a heavy REEs enrichment with high positive Eu anomalies. Both, positive and negative Ce anomalies were detected in CO2-rich mineral waters. The distinct positive Eu/Eu* in waters indicates water-rock interaction processes and positive Ce/Ce* corresponds to reducing conditions. The various processes responsible for negative Ce anomaly in reducing environment are described.

Hydrogeochemistry and distribution of potentially toxic elements in a metallogenic province – The Iberian Pyrite Belt, Portugal

Contamination by acid drainage is an environmental problem in mineralized regions, especially in the surroundings of sulphide mines. The water rock interaction process involves the oxidative dissolution of sulphides, naturally or by mining activity, that generates acidity which, in turn, produces sulfate, and water pollution by sulphide-hosted metals. The particular geology of the Iberian Pyrite Belt (IPB) in the southwestern Iberian Peninsula creates the ideal conditions for such water contamination. Different water types were sampled at 28 locations across the entire IBP metallogenetic province. Anions, metals, and arsenic were analysed to assess the influence of acid drainage. The results demonstrate the sulfate nature of waters in the vicinity of mines. Other types of water in the IPB region are mainly mixed chloride and bicarbonate (river and groundwater) and mixed and sodium-bicarbonate (lakes) types. Water quality assessment indicated strong contamination of surface waters that are directly influenced by mine wastes. There is the additional concern that some lakes and groundwaters exhibit concentrations of potentially toxic elements (e.g. Al, As) that are above the regulatory limits established by the European Commission Water Framework Directive.

Heavy Metal Concentrations in the Groundwater of the Barcellona-Milazzo Plain (Italy): Contributions from Geogenic and Anthropogenic Sources.

We collected and analysed 58 samples of groundwater from wells in the Barcellona-Milazzo Plain, one of the most important coastal aquifers of Sicily (Italy), to determine major, minor, and trace element concentrations. In this area, geogenic and anthropogenic sources of heavy metals and other pollutants co-act, making the individuation of the main pollution sources difficult. Our work was aimed at the application of geostatistical criteria for discriminating between these pollution sources. We used probability plots for separating anomalous values from background concentrations, which were plotted on maps and related to possible sources of pollutants. Our results indicate that hydrothermal fluid circulation and the water–rock interaction of country rocks that host mineralized ore deposits generate a significant flux of heavy metals to groundwater, as well as anthropogenic sources like intense agriculture and industrial activities. In particular, NO3, F, and Ni exceed the Maximum Admitted Concentrations (MACs) established by the WHO and Italian legislation for drinking-water. The spatial distributions of geogenic and anthropogenic sources were so deeply interlocked that their separation was not easy, also employing geostatistical tools. This complex scenario makes the implementation of human health risk mitigation actions difficult, since the flow of pollutants is in many cases controlled by simple water–rock interaction processes.

Source identification of mine water inrush: a discussion on the application of hydrochemical method

This paper presents an investigation on source identification of mine water inrush using a geochemical technique. The hydrogeochemistry characteristics can reflect water–rock interaction processes; therefore, the results of hydrochemical analysis could indicate the groundwater occurrence. Although hydrochemical analysis has been reviewed in previous studies, the selection of the evaluation index and the choice of units have seldom been studied. Statistical methods, hierarchical cluster analysis (HCA) and principal component analysis (PCA), were used for analysis by SPSS 21.0. Piper, Durov, and Stiff diagrams were used to identify the four types of water sources. Four types of water samples were used to perform this research, and the major purpose of the present research is to examine the results obtained under different conditions. The results show that the situations arising from the selection of different identification indices, units, and identification methods can lead to great differences. The results are as follows: The selection of trace ions for identification indices can largely affect the discriminant results. In this study, identification results with fewer indicators are poor than results with more indicators as a whole. The unit milliequivalents per liter (mEq/L) is not useful for better identification results according to this study. The data is appropriate for PCA (the Kaiser–Meyer–Olkin measure of sampling adequacy is > 0.5, and the significance value for Bartlett’s test is < 0.01), but its application to reduce dimensions cannot work under all conditions.

Contamination risk assessment of the Transboundary Zeravshan River using chemical and isotopic studies

The results of chemical and isotope analyses of water of the Zeravshan River are presented. Results show that the low salinity of the river water in the upstream reach is formed mainly by water dissolution of minerals in natural rocks, i.e. the existence of a water-rock interaction process. The detection of heavy cations in the composition of the river water is due to their transport long distances in the form of microparticles by wind and accumulation in snow cover and glaciers. During the melting of snow and glaciers, and during rain events, pollutants are carried by streams, small rivers, and finally by Zeravshan River that distributes the pollutants over long distances.

Hydrochemistry of groundwaters from alluvial and fractured igneous aquifers at the western region of Lake Hazar (Elazığ, Turkey)

The study area is located at Eastern Anatolian Fault Zone and at the western shore of Lake Hazar (Elazig, Turkey). This study aims to identify the hydrochemical features of groundwaters from fractured igneous aquifers and to correlate them with the alluvial aquifer’s groundwaters. The water samples were collected in April and September during the rainy and dry periods, respectively. As a result of active tectonism in this region, hard rocks have gained secondary porosity and permeability. According to major ion composition, the fractured igneous and alluvial aquifer groundwaters can be grouped into the Ca-Mg-HCO3 type, whereas the groundwaters emerging very close to the thrust fault locations can be classified as the Mg-Ca-HCO3 type. The water-rock interaction process represents the primary factor controlling the hydrochemistry of the investigated groundwaters. Generally, the alluvial aquifer’s groundwaters are characterized by low pH values. Clay minerals in the alluvial material may act as H+ buffers and cause decreased pH values. According to the isotopic tracers of 18O, 2H, and 3H, the spring water discharging at higher altitudes from the fractured igneous aquifer reflects rapid circulation and recharging from recent precipitation compared to alluvial aquifer groundwater. The groundwaters’ major ions fall well within the permissible limits for drinking water in Turkey. In contrast, the NO3− and NH4+ concentrations from groundwaters, especially those recharging from fractured igneous aquifers, are very close to or in excess of the limit values. The high concentrations of NO3− and NH4+ in groundwaters presumably result from landfills and the use of agricultural fertilizers in the study area. The surface waters (Lake Hazar and man-made wetland (MMW)) also are investigated within the scope of the hydrochemistry studies. Higher TDS, Cl−, and Na+ concentrations in the MMW reflect salinity that could result from lake water intrusion and evaporation processes.

Using the multivariate statistical analysis for understanding of chemical composition of saline lakes in south part of Western Siberia, Russia

Major ion and trace elements chemistry of fifty-eight water samples of southern part of Western Siberia (Russia) were analysed with a suite of statistical techniques (using R programming language), in an effort to explain the key processes affecting chemical composition of saline lakes. The database included data about well, river, and lake waters and groundwater. According to performed cluster analysis of chemical data, all lakes in the area can be divided in to 5 main groups and their chemical composition very similar to rivers and deep groundwater. Shallow groundwaters are more enriched in Ca2+ and Mg2+. Principal component analysis (PCA) identified four main principal components, with the first principal component (PC1) accounting for 44.3% and representing the process of salinization, and PC2 and PC3 (17.9 and 8.6% of total variance) controlled by water-rock interaction process of carbonates/sulphates precipitation and aluminosilicates formation.