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Water-rock interaction and chemistry of groundwaters from the Canadian Shield
Abstract
The chemical and isotopic compositions of groundwaters in the crystalline rocks of the Canadian Shield reflect different degrees of rock-water interactions. The chemistry of the shallow, geochemically immature groundwaters and especially of the major cations is controlled by local rock compositions, whereby dissolution reactions dominate. Conservative constituents, such as chloride and bromide, however, are not entirely a result of such reactions but appear to be readily added from leachable salts during the initial stages of the geochemical evolution of these waters. Their concentration changes little as major cations increase, until concentrations of Total Dissolved Solids (TDS) reach 3000 to 5000 mg 1−1. The isotopic composition of these shallow waters reflects local, present day precipitations.In contrast to the shallow groundwaters, the isotopic and chemical compositions of the deep, saline waters and brines are determined by extensive, low-temperature rock-water interactions. This is documented in major ion chemistries, 18O contents and strontium isotopic compositions. These data indicate that the deep brines have been contained in hydrologically isolated “pockets”. The almost total loss of primary compositions make discussions on the origin of these brines very speculative. However, all brines from across the Canadian Shield have a very similar chemical composition, which probably reflects a common geochemical history. The concentrations of some major and most minor elements in these fluids appear to be governed by reactions with secondary mineral assemblages.
... The lighter H atoms in the soluble minerals containing hydrogen are easily adsorbed by minerals such as clay, while the heavier D atoms exchange with the H atoms in the water, causing the formation water to be continuously enriched with D and to exhibit D drift characteristics. 18 O is enriched in the surrounding rock, and when the groundwater flows through the surrounding rock, it acts on the soluble minerals containing oxygen in the surrounding rock. The heavier 18 O in the minerals undergoes isotope exchange with the lighter 16 O in the groundwater, resulting in the continuous enrichment of 18 O in the formation water and 18 O drift. ...
... 18 O is enriched in the surrounding rock, and when the groundwater flows through the surrounding rock, it acts on the soluble minerals containing oxygen in the surrounding rock. The heavier 18 O in the minerals undergoes isotope exchange with the lighter 16 O in the groundwater, resulting in the continuous enrichment of 18 O in the formation water and 18 O drift. 20,26,31 As the fracturing fluid is gradually discharged, the interaction between the coal seam and the surrounding rock with the fracturing fluid gradually weakens and the interaction between the formation water and the coal seam or the surrounding rock gradually increases. ...
... 18 O is enriched in the surrounding rock, and when the groundwater flows through the surrounding rock, it acts on the soluble minerals containing oxygen in the surrounding rock. The heavier 18 O in the minerals undergoes isotope exchange with the lighter 16 O in the groundwater, resulting in the continuous enrichment of 18 O in the formation water and 18 O drift. 20,26,31 As the fracturing fluid is gradually discharged, the interaction between the coal seam and the surrounding rock with the fracturing fluid gradually weakens and the interaction between the formation water and the coal seam or the surrounding rock gradually increases. ...
The water produced from coalbed methane (CBM) wells contains abundant hydrogeochemical information, which is of great significance for the productivity evaluation of CBM wells. Based on the analysis of the conventional ions, hydrogen and oxygen isotopes, and trace elements in the water produced from three CBM wells in the Laochang Block, eastern Yunnan, the geochemical characteristics of the water produced from three CBM wells and their impacts on productivity are analyzed. The results show that the conventional ions in the water produced from all the three CBM wells in the study area exhibit similar characteristics, with low concentrations of Ca²⁺, Mg²⁺, SO42–, and F–, medium concentrations of K⁺, and high concentrations of Na⁺, Cl–, and HCO3–. As the drainage time increased, the water produced from wells S-2 and S-3 changed from the Na–Cl–HCO3 type to the Na–HCO3 type, while the water produced from well S-1 remained the Na–Cl–HCO3 type. The concentrations of HCO3– and F– are roughly positively correlated with the gas production, with higher gas production at concentrations of approximately 2000 and 2 mg/L, respectively. The gas production from well S-1 is relatively low, and it is speculated that this situation is caused by reservoir damage. The gas production from well S-2 is the lowest among the three wells in the study area, and it is speculated that the cause of this phenomenon is roughly due to breakage of the sandstone at the top of the coal seam or collapse of the wellbore, which communicates with the aquifer. Based on the characteristics of the water production from well S-3 with a good gas production, a quantitative characterization range of trace element changes in the water production from CBM wells is proposed. σY values of around 1500 μg/L and σM values of 0.4–0.5 μg/L are beneficial for the long-term gas production.
... It hosts the oldest crustal rocks in North America, with some rocks dating to over 4.2 Ga (O'Neil & Carlson, 2017). In deep shield environments where water has been sampled, salinities several times greater than seawater are commonly found (Frape et al., 1984). These waters are isolated from the surface, i.e., contain no influx of meteoric waters, on all but the longest time scales-noble gas isotopes indicate that the most isolated of these waters have a subsurface residence time above 1 Ga (Holland et al., 2013). ...
... Canadian Shield brines were first described as Ca-Cl type brines with a distinctive water isotope composition (Fritz and Frape, 1982). An expanded study surveying a wider range of sites found that the Ca/Na ratios in these waters was variable, but in general a Ca-Na-Cl type brine was characteristic of Canadian deep shield waters (Frape et al., 1984). It has long been suspected that the geochemistry of these waters is dependent on long-term rock-water interactions. ...
... Lupin (Nunavut Territory, Canada) data were published in . Sudbury Basin (ON, Canada) and Yellowknife (Northwest Territiries, CA) data were published in (Fritz and Frappe, 1982) and (Frape et al., 1984). Thompson (MB, Canada) data were published in (Fritz and Frappe, 1982), (Frape et al., 1984), and (Telling et al., 2018). ...
Research into the deep biosphere requires an understanding of both the microbial community at a given site and the geochemical and hydrological factors that support that microbial community. To highlight the interplay between geochemistry and microbiology in these deep environments, we characterized the hydrogeologic and geochemical systems of a 2.7 Ga banded iron formation within the Canadian Shield in the Soudan Underground Mine State Park in Minnesota, United States, a site known to host a lithotrophic microbial community. Calcium-sodium-chloride brines, characteristic of deep groundwaters throughout the Canadian Shield, were found in the site with total dissolved constituents (<0.2 micron) as high as 116,000 mg/L (ppm) in one borehole. Comparison of the Soudan waters to those found at other sites in the Canadian Shield or other sites of deep biosphere research indicate that they are notable for their high magnesium concentrations relative to total salinity. Additionally, the most saline Soudan waters have distinct ²H and ¹⁸O water isotope values suggesting long periods of isolation from the surface, which would allow for the evolution of a distinctive subsurface community. The presence of the banded iron formation along with the long-term isolation of the shield waters make Soudan a site of great potential for future research into deep crustal life. Furthermore, our work at Soudan highlights how geochemical data can inform future research into the deep biosphere and highlights a path for future research at the mine.
... H 2 and CH 4 ), and sub-neutral pH (Ward et al., 2004;Onstott et al., 2006;Sherwood Lollar et al., 2006;Frape et al., 2014;Simkus et al., 2016). In these low porosity rock environments, fluids can also reach high salinities at depth, in some cases harboring hypersaline brines (Carpenter, 1978;Vovk, 1981Vovk, , 1982Vovk, , 1987Fritz and Frape, 1982;Frape et al., 1984;Gascoyne et al., 1989;Bottomley et al., 1994;Kloppmann et al., 2002;Kharaka and Hanor, 2003;Onstott et al., 2006;Shouakar-Stash et al., 2007;Li et al., 2016;Magnabosco et al., 2018;Warr et al., 2021). Subsurface continental brines have been studied extensively in terms of the origin of their salinity and their geochemical relationship with in situ microbial processes. ...
... While the fluids at these locations reflect different proposed formation mechanisms, they are all the product of water-rock interaction occurring over long time periods in hydrogeologic isolation. Examples of such processes include: evaporitic dissolution and magmatic HCl interaction (>2.58 Ma, Stargard, Poland) (Kalwasiń ska et al., 2020), silicate hydration (20-50 Ma, Outokumpu, Finland) (Kietäväinen et al., 2013(Kietäväinen et al., , 2014, as well as serpentinization and water radiolysis (>1.00 Ga, Kidd Creek, Canada) (Frape et al., 1984;Warr et al., 2021). Formation of saline deep fluids in the deep boreholes of Germany, Sweden, and Kloof Mine of South Africa's Witwatersrand Basin, have a less certain history, with subsurface geochemical trends suggesting their salinity may have been acquired through some type of water-rock interactions under largely isolated conditions or mixing with higher salinity fluids over time (Gold, 1992;Möller et al., 1997;Onstott et al., 2006;Kieft et al., 2018). ...
... Such high TDS of the Moab brines were similar to values $200 g/L from mines that include Boulby in the UK (Bottrell et al., 1996;Payler et al., 2019) and Kidd Creek on the Canadian Shield . The Ca-Na-Cl composition of the brines is consistent with Ca-Na-Cl dominance observed for other global deep subsurface fracture fluids in crystalline shields (Edmunds et al., 1987;Pearson, 1987;Blomqvist, 1999;Barth, 2000;Frape et al., 1984 (Table 1) are not unusual among deep subsurface brines, with many previously identified deep mine brine systems showing DOC concentrations > 2 mmol/L (Payler et al., 2019;Kalwasiń ska et al., 2020) and some even as high as 2.4-5 mmol/L at Kidd Creek (Sherwood , but the Moab brines were much more depleted in d 13 C DOC/DIC signatures relative to Kidd Creek (À5.1 to À8.9 ‰ d 13 C DOC/À0.5 to À8.8 ‰ d 13 C DIC, Sherwood . The low brine cell counts (Table 1) are close to estimates for other deep brines of the continental subsurface, including the Szczecin Trough brine in Poland ($10 4 cells/ mL, Kalwasiń ska et al., 2020), the Outokumpu deep drill hole ($10 3 cells/mL, Purkamo et al., 2016;Nuppunen-Puputti et al., 2018), the lower end of Kidd Creek brine estimates ($10 3 -$10 5 cells/mL, Lollar et al., 2019). ...
Geochemical and isotopic fluid signatures from a 2.9 – 3.2 km deep, 45 – 55 ℃ temperature, hypersaline brine from Moab Khotsong gold and uranium mine in the Witwatersrand Basin of South Africa were combined with radiolytic and water-rock isotopic exchange models to delineate brine evolution over geologic time, and to explore brine conditions for habitability. The Moab Khotsong brines were hypersaline (Ca-Na-Cl) with 215 – 246 g/L TDS, and Cl⁻ concentrations up to 4 mol/L suggesting their position as a hypersaline end-member significantly more saline than any previously sampled Witwatersrand Basin fluids. The brines revealed low DIC (∼0.266 – ∼1.07 mmol/L) with high (∼8.49 – ∼23.6 mmol/L) DOC pools, and several reduced gaseous species (up to 46% by volume H2) despite microoxic conditions (Eh = 135 – 161 mV). Alpha particle radiolysis of water to H2, H2O2, and O2 along with anhydrous-silicate-to-clay alteration reactions predicted 4 mol/L Cl⁻ brine concentration and deuterium enrichment in the fracture waters over a period >1.00 Ga, consistent with previously reported ⁴⁰Ar noble gas-derived residence times of 1.20 Ga for this system. In addition, radiolytic production of 7 – 26 nmol/(L x yr) H2, 3 – 11 nmol/(L x yr) O2, and 1 – 8 nmol/(L x yr) H2O2 was predicted for 1 – 100 μ g/g ²³⁸U dosage scenarios, supporting radiolysis as a significant source of H2 and oxidant species to deep brines over time that are available to a low biomass system (10² – 10³ cells/mL). The host rock lithology was predominately Archaean quartzite, with minerals exposed on fracture surfaces that included calcite, pyrite, and chlorite. Signatures of δ ¹⁸Ocalcite, δ ¹³Ccalcite, Δ³³Spyrite, δ ³⁴Spyrite and ⁸⁷Sr/⁸⁶Sr obtained from secondary ion mass spectrometry (SIMS) microanalyses suggest several discrete fluid events as the basin cooled from peak greenschist conditions to equilibrium with present-day brine temperatures. The brine physiochemistry, geochemistry, and cellular abundances were significantly different from those of a younger, shallower, low salinity dolomitic fluid in the same mine, and both were different from the mine service water. These results indicate the discovery of one of few long-isolated systems that supports subsurface brine formation via extended water-rock interaction, and an example of a subsurface brine system where abiotic geochemistry may support a low biomass microbial community.
... Primary fluid inclusions in Dol 1B have high salinities and temperatures above 100 • C (Table 2; Fig. 18). Elevated fluid inclusion salinities around 20 wt-% are typical for basinal or continental basement brines (Frape et al., 1984). ...
Carbonate archives record a brief snapshot of the ambient Earth’s surface conditions at their deposition. However, the geologically reasonable extraction and interpretation of geochemical proxy data from ancient, diagenetically altered rock archives is fraught with problems. Three issues stand out: the dichotomy between petrographic and geochemical alteration; the lack of quantitative age constraints for specific diagenetic phases resulting in a poorly constrained admixture of local, basin-wide and over-regional (far-field) features; and an often insufficient understanding of the temperatures and compositions of diagenetic fluids. Here, the archive of Devonian marine limestones exposed to multiple far-field diagenetic events is used as an example to explore the above-listed issues. Methods applied include petrography, U-Pb dating, micro XRF, fluid inclusion data, clumped isotopes, δ13C and δ18O isotopes, 87Sr/86Sr ratios and quartz trace element data. Devonian limestones studied here were overprinted by two cross-cutting regional fault zones (T ≈ 230 °C) by multiple events between the Variscan Orogeny and the late Paleogene. The following processes are recorded: (i) protolith deposition and partial dolomitisation during rapid burial in the Middle/Late Devonian (T ≈ 180 °C); (ii) deep burial to ca 6.5 km and tectonic/hydrothermal overprint during the Variscan Orogeny in the Carboniferous (T ≈ 90–230 °C); (iii) rapid uplift to 1–2 km burial depth at the end of the Variscan Orogeny and hypogene karstification (T ≈ 50 to 100 °C) initiated by regional geology in the Permian/Triassic; (iv) tectonic/hydrothermal overprint during the opening of the Proto-Atlantic Ocean between the Early Jurassic and the Early Cretaceous (T ≈ 50 to 130 °C); (v) tectonic/hydrothermal overprint including renewed hypogene karstification and hydrothermal calcite cement precipitation (T ≈ 50 to 180 °C) during Alpine Orogeny between the Late Cretaceous and late Paleogene. Despite this complex series of diagenetic events, the protolith limestones largely preserved their respective Middle/Late Devonian dissolved inorganic carbon (DIC) and 87Sr/86Sr signatures. This study documents that geochemical proxy data, placed into their petrographic, paleotemperature, and local to over-regional context, significantly increases the ability to extract quantitative information from ancient carbonate rock archives. Research shown here has wider relevance for carbonate archive research in general.
... The quality of groundwater is determined by multiple factors, including the chemistry of infiltrating water, the geological characteristics of the aquifer, the nature of the casing, recharge and circulation regions, and anthropogenic activities (Frape et al. 1984). Among these factors, the dissolution of aquifer minerals in water is the primary process that controls the chemical composition of groundwater. ...
Groundwater quality assessment is crucial for the sustainable management of water resources in arid regions, where groundwater is the primary source of water supply and increasing demand raises concerns. The study area in Southwest Algeria relies heavily on groundwater as a source of water supply, and the increasing demand for freshwater raises concerns about the quality of groundwater. To assess the hydrochemical characteristics and water quality of groundwater in the Ain Sefra region, multivariate statistical methods, geochemical modeling and water quality indices were employed. The study revealed that the groundwater samples could be classified into four water groups using hierarchical cluster analysis Q mode (HCA), namely Ca-Mg-HCO 3 , Ca-Mg-Cl-SO 4 , Ca-SO 4 and Na-Cl. Factor analysis was used to identify the main factors controlling the study area's hydrochemical processes. The results indicated that water-rock interaction, reverse ion exchange and anthropo-genic pollution were the main hydrochemical processes affecting groundwater chemistry. The water quality index indicated that the groundwater was suitable for human consumption, with only 2.32% of the samples being unsuitable. Additionally, the groundwater was suitable for agricultural use, but salinity control was necessary. The saturation index values showed that the groundwater was supersaturated with aragonite, calcite, dolomite, anhydrite and gypsum, and undersaturated with halite. Ca-smectite, Mg-smectite and kaolinite were identified as the primary processes controlling the chemical composition of groundwater. The application of multivariate statistical methods, geochemical modeling and water quality indices provided a comprehensive understanding of the hydrochemical characteristics and water quality of groundwater in the Ain Sefra region. The findings of the study can serve as a useful basis for future studies on groundwater quality assessment in the region.
... The groundwater quality is influenced by many factors, such as the chemistry of infiltration water, topography, geology of the reservoir rock, and anthropogenic factors [1]. These factors lead to a variation in the chemical composition and hydrogeochemical facies. ...
... The groundwater quality is influenced by many factors, such as the chemistry of infiltration water, topography, geology of the reservoir rock, and anthropogenic factors [1]. These factors lead to a variation in the chemical composition and hydrogeochemical facies. ...
Tel. +213 0 5 55 83 20 05, Tel./Fax: +213 33 86 97 24, Tel. +213 0 5 51 59 37 47, Tel./Fax: +213 33 86 97 24 A B S T R A C T This work aims to evaluate the hydrochemical characteristics of a shallow aquifer located between carbonated formations and salt lake in the Chemora region in northeastern Algeria. Hydrochemical, multivariate statistical, and the thermodynamics techniques were used to investigate the hydrochemical evolution within the aquifer. Twenty-five water samples were collected during May 2013 in this the aquifer wells. The results indicate that this shallow water is characterized by sulfate-dominant facies representing about 64% of cases, followed by the chloride with 24%, and the remaining (12%) is represented by the bicarbonate facies. The sulfate facies is acquired mainly by the alteration of pyrite. The saturation index showed that all carbonate minerals are supersaturated and all evaporate minerals are undersaturated which suggest that their soluble component Na + , Cl − , Ca 2+ , and SO 2À 4 concentrations are not limited by mineral equilibrium. The application of the cluster analysis and the principal components analysis based on major ion contents defined 3 main chemical water types reflecting different hydrochemical processes with salinity increases along the groundwater flow.
... Several researchers have studied the origins of salinity and the processes of groundwater mineralisation acquisition. Indeed, potential sources of salinity in waters are: dissolution of evaporite minerals (Cardenal et al. 1994;Moussa et al. 2011;Khaska et al. 2013), saltwater intrusion from sabkhas (Farid et al. 2013;Demdoum et al. 2015;Dhaoui et al. 2023), intrusion of fossil marine water that is trapped in sediments (Barbecot et al. 1998;Vallejos et al. 2018;Cherchali et al. 2023), current marine intrusion (Custodio and Bruggeman 1987;Bouchaou et al. 2008;Martínez-Pérez et al. 2022), upwelling of deep saline water from the basement (Frape et al. 1984;Aquilina et al. 2002;Hébrard et al. 2006;Walter et al. 2017), agricultural activities (Stigter et al. 1998;Pulido-Bosch et al. 2018) and saline pollution caused by the infiltration of mining brines (Lucas et al. 2010). ...
The regular hydrochemical monitoring of groundwater in the Mila basin over an extended period has provided valuable insights into the origin of dissolved salts and the hydrogeochemical processes controlling water salinization. The data reveals that the shallow Karst aquifer shows an increase in TDS of 162 mg L−1 while the thermal carbonate aquifer that is also used for drinking water supply exhibits an increase of 178 mg L−1. Additionally, significant temperature variations are recorded at the surface in the shallow aquifers and the waters are carbogaseous. Analysis of dissolved major and minor elements has identified several processes influencing the chemical composition namely: dissolution of evaporitic minerals, reduction of sulphates, congruent and incongruent carbonates’ dissolution, dedolomitization and silicates’ weathering. The hydrogeochemical and geothermometric results show a mixing of saline thermal water with recharge water of meteoric origin. Two main geothermal fields have been identified, a partially evolved water reservoir and a water reservoir whose fluid interacts with sulphuric acid (H2S) of magmatic origin. These hot waters that are characterized by a strong hydrothermal alteration do ascend through faults and fractures and contribute to the contamination of shallower aquifers. Understanding the geothermometry and the hydrogeochemistry of waters is crucial for managing and protecting the quality of groundwater resources in the Mila basin, in order to ensure sustainable water supply for the region. A conceptual model for groundwater circulation and mineralization acquisition has been established to further enhance understanding in this regard.
... The SI values of calcite at each water sample point are close to 0, that is, calcite is basically in dissolution equilibrium, and there may be mineral precipitation if it continues to dissolve [50]; the SI values of the remaining minerals (dolomite, gypsum, anhydrous gypsum) are basically less than 0, which are in unsaturated state, indicating that the water samples in the study area have the ability to continue to dissolve the surrounding rocks [48]. Furthermore, the ratio of pit mine water to some surface water is on the 1 :1 line (Fig. 3c), suggesting that other water-rock interactions are involved [51]. ...
... Chloride-type brine commonly occurs below 650 m in crystalline basement rocks and sedimentary formations (89,90). The chloride-type brines in the Canadian Shield may have been formed by extensive, low-temperature water-rock interactions (89), or they may have originated from a residual seawater brine, probably Devonian in age (91). ...
Brine contains cations such as K ⁺ , Ca ²⁺ , Na ⁺ , Mg ²⁺ , Li ⁺ , B ³⁺ , Rb ²⁺ , and Cs ²⁺ , as well as anions such as SO 4 ²⁻ , Cl ⁻ , HCO 3 ⁻ , CO 3 ²⁻ , NO 3 ⁻ , Br ⁻ , and I ⁻ , which are valuable elements. Brines are widely distributed in salt lakes in the world's three enormous plateaus and beyond and are classified into three types: sulfate-, chloride-, and carbonate-type brines. Sulfate-type brine forms in salt lakes, whereas carbonate-type brine results from magmatic and hydrothermal activity. Chloride-type brine forms in deep basins due to the reduction and transformation of buried brine. Li in brine plays a critical role in clean energy transitions, and K in brine is important for potash production. Recently, new techniques for extracting Li from brine have been developed, and the large-scale, comprehensive development pattern of brines has formed the basis for a recycling economic model, which contributes to the efficient use of brines for potash and Li 2 CO 3 development and CO 2 emission reduction. This article reviews the genesis of brines and highlights new utilization techniques, trends, and sustainable development.
... Cl/Br ratios and chlorine stable isotope compositions in fluid inclusions can efficiently discriminate fluid origins (e.g., Frape et al. 1984;Richard et al. 2011), but such data is scarce in F-Ba stratabound and vein deposits from the borders of the FMC. The few data comes from Boiron et al. (2002) in the northwestern part of the FMC, where fluorite fluid inclusion high Cl content, together with Cl/Br ratios lower than the average seawater value, were interpreted as resulting from seawater evaporation during the Late Triassic to Early Jurassic (Boiron et al. 2002). ...
We provide new constraints for the fluid flow system at the origin of two F-Ba deposits located at the unconformity between the south of the Paris Basin and the northern edge of the French Massif Central. We used microthermometry and bulk crushleach analyses to determine isotope ratios of mineralizing fluids (δ18O, δD, δ37Cl), together with cation and anion composition of fluid inclusions hosted by fluorite. Chlorinity and Cl/Br molar ratios (212–521) indicate the involvement of a brine, whose origin likely corresponds to Triassic evaporated seawater compatible with supratidal dolomitic facies preserved nearby. Microthermometry reveals high Ca/Na ratios, suggesting that the brine composition evolved from hydrothermal alteration of the Variscan basement and partial dissolution and replacement of the host sedimentary rocks. δ37Cl values are lower than the expected value of evaporated seawater, suggesting Cl isotope fractionation by ion filtration in clay-rich horizons. Fluorite crystallized at minimum temperatures of 70 to 110 °C, 10–40 °C warmer than the host Triassic sedimentary rocks. Ascending brines were expelled during the Early Cretaceous and experienced a drop in pressure and temperature, together with possible mixing with the SO4-rich pore water of the sedimentary rocks, causing precipitation of silica, followed by fluorite and barite, forming a stratabound deposit similar to those found in many areas in Western Europe
... The groundwater quality is influenced by many factors, such as the chemistry of infiltration water, the geological nature of the reservoir rock, the decomposition of organic matter and anthropogenic factors (Frape et al., 1984). The dissolution of minerals from the surrounding rock in the water is the dominant factor controlling the chemical composition of these waters. ...
The intensive exploitation of groundwater resources in the region of Agmerouel-Roknia has greatly influenced the hydrochemical functioning of the superficial aquifer. This has resulted in a general decline of the piezometric level of the groundwater, a mineralization of water and calcium facies near Western limestone and sodium chloride in the East of the plain in liaison with the lithology. To highlight the hydrochemical processes of groundwater, a study by Major ions were analyzed for twenty two groundwater samples collected from this aquifer during the month of March 2013. Multivariate statistical techniques factor analysis and cluster analysis were applied to the data on groundwater quality, with the objective of defining the main controls on the hydrochemistry at the plain. These statistical techniques have shown the presence of two salinity groups increasing important according to the geology. The initial facies on the Western limits as well as infiltration areas is bicarbonate. In the East of the plain water becomes charged with Na and Cl in connection with the dissolution of salt formations. The presence of nitrates is related to agricultural activity. The major ion chemistry (Mg, Ca, HCO3 and SO4) in the three stations derived from the anthropogenic sources and the water-rock interaction.
... Groundwater quality depends on the geochemistry and the properties of the aquifer. It is controlled by several factors such as topography, aquifer's rock lithology, residence time and human activities (Frape et al. 1984;Lashmanan et al. 2003). These factors lead to changes in the chemical composition of water chemistry between recharge and discharge areas (RefatNasher and Humayan Ahmed 2021). ...
The present study aims to investigate the hydrogeochemical characteristics of the Terminal Complex (TC) groundwater in the Biskra region (north-east Algeria) to understand the hydrogeochemical processes that control their chemical composition using multivariate statistical techniques, bivariate and thermodynamic plots. A total of forty-five (45) water samples were collected from wells exploiting the TC aquifer and analyzed for electrical conductivity, pH, temperature, and major ions (April 2019). The results obtained indicate that the quality of the water does not meet WHO standards for drinking water, with contents of major elements exceeding the standard for most of the wells, except for the wells in the northern part, which are of good quality. Four types of hydrochemical facies were identified, revealing the diversity of processes that control water chemistry in the study area: (i) a sulfate sodium facies (47%), (ii) a sulfate calcium facies (37%), (iii) a bicarbonate magnesium facies (9%) and (iv) a sulfate magnesium facies (7%). Facies (i), (ii) and (iv), highlighted in the southern and south-western parts, are linked to the dissolution of salts and gypsum from evaporite formations. Facies (iii), identified in the northern part, reflects the dissolution of carbonate formations located in the aquifer recharge limits (recharge zone). The application of principal component analysis indicates that Na+, Cl−, Ca2+, Mg2+, SO42− and TDS represent the axis of mineralization. The dissolution of halite, gypsum, and anhydrite-bearing rocks is the primary mechanism for conducting groundwater salinization. These processes are confirmed by the PHREEQC model which reveal that calcite and dolomite precipitation favors the dissolution of evaporites where almost all water samples are undersaturated with respect to gypsum, anhydrite and halite (evaporite minerals). In addition, bivariate plots of the different ions show that cation exchange reactions leading to the adsorption of Ca2+ on clay minerals and simultaneous release of Na+ ions and silicate weathering are also processes that influence the groundwater chemistry of the Terminal Complex aquifer.
... However, few samples with lower TDS from subgroups G1A and G2A fall toward the zone of rainwater chemistry. This is in coherence with their major water types discussed in the previous sections, low salinity of such water type indicates recently infiltrated waters from recharge areas with limited mixing (Frape et al., 1984;Gascoyne and Kamineni, 1994). Subgroup G1B shows exclusively dominance of geology. ...
Middle Ganga Basin (MGB) is lifeline for millions of inhabitants relying heavily on the groundwater. This has resulted in depletion of water quality and quantity at a very rapid scale. The present study has emphasized on hydrogeochemical evolution of groundwater in the Middle Ganga Basin, covering an area of 99,058 sq. km. Around 400 water samples were evaluated to determine the geochemical evolution of the shallow groundwater in MGB. The weighted average water quality index (WAWQI) shows 20.2% of the groundwater are unsuitable for drinking purposes. The Ca–HCO3 water facies dominates in northern region in the interfluves of Ghaghara and West Rapti rivers whereas more evolved water types such as Mg–HCO3, Na–HCO3 are found in the interfluves area of Ghaghara, Ganga, Yamuna, and Gomati Rivers. The occurrence of more mineralized water with increasing residence time in the flow direction suggests geogenic control and evolution follow the Chebotarev sequence. The saline water type is observed in and around the settlement reflecting the in-situ enrichment due to stagnation and anthropogenic activities. Hierarchical cluster analysis classified the regional groundwater data into three distinct major groups G1, G2, and G3. Factor 1 is attributed to anthropogenic inputs and associated with subgroup G2B and group G3. Factor 2 is attributable to the geogenic factors and is associated with subgroups G1A, G1B, and G2A. The various bivariate plots confirm the dominance of silicate weathering over carbonate weathering in the study area. Geochemical mass balance modeling suggests calcite and dolomite are in saturation to oversaturation conditions, restricting their further dissolution and primary silicate minerals controlling the groundwater chemistry. Our work reveals hydrogeochemical evolution on a regional scale in the shallow groundwater which will help to develop sustainable groundwater management strategies.
... Na-Cl type (IV): This type is commonly found in seawater and hot spring water. Therefore, in this study, groundwater classified as Na-HCO3 type may have been in deep stagnation for a long time, and groundwater classified as Na-Cl type may be mixed with seawater or hot spring water [14]. The relationship between the equivalent concentration ratios of Na + and Clsuggests possibility that groundwater at most of study sites may be affected by sodium leaching from volcanic rocks and by mixing seawater and fossil seawater [4] [15]. ...
Djibouti is one of the most arid areas in the world and rivers are not formed regularly in this region. So, groundwater has been used as the main water resource for humans and livestock. Therefore, necessary to understand the state of groundwater in terms of utilizing of sustainable water resources in this country. In this study, we measured ion contents (Li + , Na + , NH4 + , K + , Mg 2+ , Ca 2+ , F-, Cl-, NO2-, Br-, SO4 2-, NO3-, PO4 3-, HCO3-) in groundwater using ion chromatography, and analyzed characteristics groundwater quality using by multivariate analysis based upon groundwater quality with stable isotope ratio of hydrogen and oxygen and tritium concentrations, with reference to their locations and examined the distribution analysis using GIS data of watershed maps. As a result of groundwater quality measurements, the most of groundwater samples in this study mixed with seawater or hot spring water and fossil seawater. And the concentration of NO3-in groundwater was over 50 mgL-1 at 4 sites. In addition, as a result of the hierarchical cluster analysis, groundwater in this study showed different chemical characteristics even in the same watershed. As results of this study, although some important data of groundwater quality in Djibouti has been obtained, it is considered necessary to study in groundwater dating and water stable isotope ratios more wide area in order to understand its complex groundwater distribution and water quality characteristics.
... The evolution continuum of groundwater to a brackish end-member follows two possible paths in the study region. First, groundwater tends to evolve through Water/Rock interactions to a CaCl 2 end-member, as found within the PSB formation described elsewhere in Canada (Frape et al., 1984). Second, groundwater from confined aquifers mixes with Pleistocene Laflamme Seawater trapped in the regional aquitards (Water/Clay groundwater), causing recharge groundwater RGW to evolve to a NaCl water type which is equivalent to SW. ...
... Thus, the Cl and SO₄²-facies of the studied waters are probably due to the gypsum lens dissolution located in the Miocene marl formations and/or to the leaching of agricultural lands following the water infiltration into the aquifer. It is known that the groundwater quality is influenced by many factors, such as chemistry, the reservoir rocks geology [17] and anthropogenic factors [18]. ...
... Based on this, the WQI was calculated using Weighted Arithmetic Index Method [30][31][32] for each of the 89 villages in the area. Several groundwater characteristics, especially its chemical characteristics, have been chronicled around the world [33][34][35][36][37]. By preparing the Water Quality Index (WQI) or Groundwater Quality Index (GWQI based on the collected groundwater samples and data) [38], the overall water quality of the region has been assessed. ...
Groundwater constitutes a significant component of freshwater resources in India being vital for its economy and domestic water security. The quantity, quality and accessibility of water resources forms the basis of balanced socio-economic development and its optimum utilization cannot be sustained unless its quality is assessed. The current study tries to access the quality and suitability
of groundwater for drinking purposes in western drier parts of India in the state of Rajasthan. Based on collected data, selected hydro-geochemical parameters, the quality of water has been determined and Water Quality Index (WQI) have been prepared using GIS applications. Applying the Inverse Distance Weighting method, WQI values for 89 villages in the area have been computed, which ranged between 71.23 and 447.39. While 68% of the region had “poor water quality”, only 32% is
sustained as ‘good water’ for consumption. The fluoride content ranging between 1.66 and 8.60 mg/L
and TDS > 1000 mg/L with average pH levels > 7 (8–9 pH) were found to be very high amongst all the
12 water quality parameters taken for the study. The northeastern region with a WQI value of >250
had the worst water quality. Furthermore, the existing water quality is also examined for influencing
two water borne diseases, i.e., gastroenteritis and fluorosis in the region. The study thus establishes
that the majority of groundwater in the region is beyond the permissible safer consumption limits,
and a large population of the region, which is directly dependent on groundwater sources, is prone
to water borne health hazards. A significantly high correlation was observed between Specific
Water Quality Parameters in the region and prevalence of gastroenteritis (and fluorosis diseases with R2 = 0.530 and R2 = 0.813, respectively).
... Precipitates at the modern-day BIC margin record the presence of waters from 31 to 18 ka ago that are compositionally consistent with high-salinity groundwaters found at depths of tens to hundreds of meters in crystalline basement rocks of the Canadian shield (42,44,51). The presence of these high-density shield brines at the base of the LIS requires a powerful physical mechanism to transport them to the subglacial surface. ...
During the last glacial period, the Laurentide Ice Sheet (LIS) underwent episodes of rapid iceberg discharge, recorded in ocean sediments as "Heinrich events" (HEs). Two competing models attempt to describe the stimulus for HEs via either internal ice sheet oscillations or external ocean-climate system forcing. We present a terrestrial record of HEs from the northeastern LIS that strongly supports ocean-climate forcing. Subglacial carbonate precipitates from Baffin Island record episodes of subglacial melting coincident with the three most recent HEs, resulting from acceleration of nearby marine-terminating ice streams. Synchronized ice stream acceleration over Baffin Island and Hudson Strait is inconsistent with internal ice sheet oscillations alone and indicates a shared ocean-climate stimulus to coordinate these different glaciological systems. Isotopic compositions of these precipitates record widespread subglacial groundwater connectivity beneath the LIS. Extensive basal melting and flushing of these aquifers during the last HE may have been a harbinger for terminal deglaciation.
... Thus, the Cl and SO₄²-facies of the studied waters are probably due to the gypsum lens dissolution located in the Miocene marl formations and/or to the leaching of agricultural lands following the water infiltration into the aquifer. It is known that the groundwater quality is influenced by many factors, such as chemistry, the reservoir rocks geology [17] and anthropogenic factors [18]. ...
The quality of the Souss-Massa Daraa (S-MD) aquifer is influenced by natural and anthropogenic contaminations. Indeed, geological formations are the main sources of mineralization in the aquifer, which compromises the potential irrigation, and threatens the sustainability of agricultural activities. In this context, hydrochemical and statistical studies were carried out on the major and secondary elements of water, based on different physico-chemical parameters, such as T °C, pH, EC (electric conductivity), NO3 - (nitrate), Cl- (chloride), HCO3 - (bicarbonate), SO4 2- (sulfate), Ca2+ (calcium ions), Mg2+ (magnesium ions), K+ (potassium ion), Na+ (sodium), Na%, Mg% and SAR (sodium adsorption ratio). The sampling was carried out in 2018, over two seasons (winter and summer), by analyzing 26 wells distributed over the studied plain. According to the water classification based on EC, it was found that 80% of the samples show very high mineralization, and 96.66% are very hard and unfit for human consumption. Also, Cl- values of most of the samples were within limits inappropriate for irrigation, but some estimated parameters, such as Na% and SAR, were within appropriate levels. In addition, according to the piper diagram, the waters are characterized by a geochemical facies of 86.66% NaCl (sodium chloride), 13.33% CaSO4 (sulphated calcium) and Mg. Thus, the principal component analysis (PCA) shows that the region waters mineralization is of natural origin.
... Opal solubility is both temperature and pH dependent 85 , with lower pH favoring precipitation. The silicon concentrations of subglacial waters 86 and mature brines that emanate from ice sheets 87 are typically tens of ppm,-values similar to other surface waters 88 -and Si concentration does not scale with total dissolved solids 89 . At these relatively low Si concentrations, saturation of amorphous silica cannot be achieved without a mechanism to concentrate Si in solution. ...
Ice cores and offshore sedimentary records demonstrate enhanced ice loss along Antarctic coastal margins during millennial-scale warm intervals within the last glacial termination. However, the distal location and short temporal coverage of these records leads to uncertainty in both the spatial footprint of ice loss, and whether millennial-scale ice response occurs outside of glacial terminations. Here we present a >100kyr archive of periodic transitions in subglacial precipitate mineralogy that are synchronous with Late Pleistocene millennial-scale climate cycles. Geochemical and geochronologic data provide evidence for opal formation during cold periods via cryoconcentration of subglacial brine, and calcite formation during warm periods through the addition of subglacial meltwater originating from the ice sheet interior. These freeze-flush cycles represent cyclic changes in subglacial hydrologic-connectivity driven by ice sheet velocity fluctuations. Our findings imply that oscillating Southern Ocean temperatures drive a dynamic response in the Antarctic ice sheet on millennial timescales, regardless of the background climate state.
... Over the last few decades, salinisation of groundwater has been the subject of extensive research [AOUIDANE, BELHAMRA 2017;GIBBS 1970;PAZAND et al. 2012]. This problem can be attributed to natural and/or anthropogenic factors, such as the interaction of water with rocks [FRAPE et al. 1984;GHESQUIÈRE et al. 2015], the intrusion of coastal saltwater or Sabkha water generated by excessive groundwater pumping [CAPACCIONIA et al. 2005], fossil seawater, which is a primary source of Cretaceous seawater [FARID et al. 2013;TIJANI 2004]. Finally, the anthropogenic intervention compounded local natural processes by saline water intrusion, due to overexploitation of groundwater, inadequate sewage disposal, intensive agricultural and industrial activities [ZEWDU et al. 2017]. ...
The aquifer system of the Remila plain (Khenchela, Algeria), covering 250 km 2 , is one of the semiarid regions where groundwater is heavily exploited for urban supply and irrigation. An integrated hydrochemical and statistical analysis was performed on 70 water samples to identify the main processes and the origin of salinisation of our waters. Chemical analyses indicate salinity values (TDS) ranging from 568 to 1586 mg·dm-3 with an average of 869 mg·dm-3 , with sulphate being the dominant ions, especially in the north and northeastern parts of the region. The identified chemical facies are SO 4-Cl-Ca in the northeastern part, SO 4-Cl-Ca-Mg present in most waters, and HCO 3-Ca-Mg in the southeastern part. We applied the statistical approach to group the waters into three categories using Principal Component Analysis (PCA) and Hierarchical Clustering Analysis (HCA); 1) saline waters (23%) (TDS > 1000 mg·dm-3 and SO 4 2-dominance), 2) moderately saline waters (51%) with HCO 3-dominance, 3) moderately saline waters (26%) with a mixed facies. The binary ion diagrams used suggest that the main hydrochemical processes are: evaporites dissolution and/or precipitation, accompanied by an exchange and/or reverse exchange of ions. Additionally, another process was detected in the northeastern part of the area; the saline intrusion of Sabkha waters, favoured by intensive aquifer exploitation.
... As a result, tectonically undisturbed continental crustal sections may host several stratified fluid reservoirs, which are not constrained to any lithological boundary as they all reside in the same crystalline aquifer (Bons et al., 2014;Burisch et al., 2018). In some regions, this stratification can still be recognized today in groundwater samples from deep boreholes (Bucher and Stober, 2016;Frape et al., 1984). Following these arguments, metal-rich basement brines may be assumed to have been present in the upper and middle crust across large parts of Central and Western Europe from ∼250 Ma onwards -an assumption that is supported by fluid inclusion studies from the Schwarzwald region (Walter et al., 2016). ...
Mesozoic hydrothermal systems host the majority of Europe's fluorspar and barite resources as well as significant amounts of metals such as Ag, Co, Zn, Pb, Ni and Cu. Their genetic link to extensional tectonics in conjunction with the opening of the North Atlantic has long been suspected, but their spatial and temporal relation to the tectonic evolution of Europe has remained enigmatic. A thorough evaluation of available geochronological data for fluorite-barite-Pb-Zn, native-metal-arsenide-carbonate and MVT-type mineralization in Continental Europe and North Africa reveals a distinct, as yet unrecognized, time-space relationship between the distribution of hydrothermal mineral systems and the tectonic evolution of the Tethys-Atlantic-Caribbean rift system. The observed time-space relationship and ore-forming mechanisms are evaluated to constrain the underlying driving force for hydrothermal mineralization in the context of the geodynamic evolution of the European lithosphere. Based on this assessment we propose the first continental-scale model for the genesis of Mesozoic hydrothermal ore deposits associated to the breakup of the supercontinent Pangea.
... Based on this, the WQI was calculated using Weighted Arithmetic Index Method [30][31][32] for each of the 89 villages in the area. Several groundwater characteristics, especially its chemical characteristics, have been chronicled around the world [33][34][35][36][37]. By preparing the Water Quality Index (WQI) or Groundwater Quality Index (GWQI based on the collected groundwater samples and data) [38], the overall water quality of the region has been assessed. ...
Groundwater constitutes a significant component of freshwater resources in India being vital for its economy and domestic water security. The quantity, quality and accessibility of water resources forms the basis of balanced socio-economic development and its optimum utilization cannot be sustained unless its quality is assessed. The current study tries to access the quality and suitability of groundwater for drinking purposes in western drier parts of India in the state of Rajasthan. Based on collected data, selected hydro-geochemical parameters, the quality of water has been determined and Water Quality Index (WQI) have been prepared using GIS applications. Applying the Inverse Distance Weighting method, WQI values for 89 villages in the area have been computed, which ranged between 71.23 and 447.39. While 68% of the region had “poor water quality”, only 32% is sustained as ‘good water’ for consumption. The fluoride content ranging between 1.66 and 8.60 mg/L and TDS > 1000 mg/L with average pH levels > 7 (8–9 pH) were found to be very high amongst all the 12 water quality parameters taken for the study. The northeastern region with a WQI value of >250 had the worst water quality. Furthermore, the existing water quality is also examined for influencing two water borne diseases, i.e., gastroenteritis and fluorosis in the region. The study thus establishes that the majority of groundwater in the region is beyond the permissible safer consumption limits, and a large population of the region, which is directly dependent on groundwater sources, is prone to water borne health hazards. A significantly high correlation was observed between Specific Water Quality Parameters in the region and prevalence of gastroenteritis (and fluorosis diseases with R2 = 0.530 and R2 = 0.813, respectively).
Earth's deep continental subsurface is a prime setting to study the limits of life's relationship with environmental conditions and habitability. In Precambrian crystalline rocks worldwide, deep ancient groundwaters in fracture networks are typically oligotrophic, highly saline, and locally inhabited by low‐biomass communities in which chemolithotrophic microorganisms may dominate. Periodic opening of new fractures can lead to penetration of surface water and/or migration of fracture fluids, both of which may trigger changes in subsurface microbial composition and activity. These hydrogeological processes and their impacts on subsurface communities may play a significant role in global cycles of key elements in the crust. However, to date, considerable uncertainty remains on how subsurface microbial communities may respond to these changes in hydrogeochemical conditions. To address this uncertainty, the biogeochemistry of Thompson mine (Manitoba, Canada) was investigated. Compositional and isotopic analyses of fracture waters collected here at ~1 km below land surface revealed different extents of mixing between subsurface brine and (paleo)meteoric waters. To investigate the effects this mixing may have had on microbial communities, the Most Probable Number technique was applied to test community response for a total of 13 different metabolisms. The results showed that all fracture waters were dominated by viable heterotrophic microorganisms which can utilize organic materials associated with aerobic/facultative anaerobic processes, sulfate reduction, or fermentation. Where mixing between subsurface brines and (paleo)meteoric waters occurs, the communities demonstrate higher cell densities and increased viable functional potentials, compared to the most saline sample. This study therefore highlights the connection between hydrogeologic heterogeneity and the heterogeneity of subsurface ecosystems in the crystalline rocks, and suggests that hydrogeology can have a considerable impact on the scope and scale of subsurface microbial communities on Earth and potentially beyond.
Description
STP 1033 provides a unique perspective on stabilization and solidification research as performed by the hazardous and radioactive waste communities. These papers are grouped into 4 sections: Processes; Regulatory Aspects and Testing Methods; Laboratory Evaluation; and Large Scale Evaluation or Demonstration.
Clear anomalous electrical conductivity horizons and high salinity (Cl, Na, Ca) of groundwater were identified in several exploration boreholes at a mine development site in Western Finland. As these could not be explained thoroughly with geological variations, further studies on the origin of the anomalies were suggested.
The results indicate long residence times (up to 10,000 years BP), but no strong water-rock interaction. Despite being below the highest Litorina Sea shoreline, a typical Litorina SO4 layer is missing. Groundwater of the study site is a mixture of modern meteoric water, pre-Litorina groundwater, and the glacial melt water.
Fluoride (F−) pollution in potable groundwater (GW) is a serious environmental concern in Pakistan with substantial human health hazard reports. The research on F− pollution in GW resources in Sindh Province is still incomplete. To explore the realistic conditions, the present research aimed to investigate the GW quality of community tube wells concerning F− contamination in Tharparkar, Sindh, Pakistan. A total of 53 samples were collected and examined for F−, along with other physicochemical parameters. The F− values observed varied from 0.2–4.2 mg/L, with a mean value of 1.63 mg/L. Among the 53 samples, 46% had F− levels that were higher than the World Health Organization’s (WHO) recommended limit (1.5 mg/L). The water type of the studied region was Ca-HCO3 type, which can be attributed to fresh recharged water. The interaction of rock–water contact controls the hydrochemistry of GW. The GW resources of the research zone were highly saturated with fluorite minerals. Human health risk calculation outcomes exposed that 21 samples showed high HQ values for children and 7 samples showed high values for adults in the research zone. Children are at high risk in the study area from drinking F−-contaminated GW. WQI results showed that 31 samples were not suitable for drinking.
Dhaka is the capital city of Bangladesh. A lot of people migrate every day. For their survival, the housing
sector is flourishing day by day. The demand impacts the supplies. A number of people are doing housing
business to support the situation. Still, on the contrary, they are grabbing a lot of green fields or water bodies
from private properties evacuating the owners. One of the ill examples is considered as Pallabi Eastern Housing
2nd Phase Project. The study is to find the socio-economic status of the land owners and local inhabitants who
are evicted from their land for the project. According to the primary observation and information collected
from different sources, approximately 350 families are relocated. Of the 45 relocated people placed under
survey from the questionnaire survey by snowball sampling, it was found that most people were displaced from
their original location through the involuntary procedure. The income level, housing condition, and utility
facilities are worse off than before the resettlement. They are unaware of taking action against the developer
for the deprivation in the land price. The study discovered different aspects that clarified how land developers
exploited the local people. The four different actors, namely land developers, local musclemen, local officials,
and local people, were identified who actively played various roles in this relocation procedure. A few scopes
are identified to rehabilitate the victims to recover from their present situation. Government should adequately
care about the reallocated people to compensate at the current rate considering the long period of suffering.
There is scope for more intensive study on the topic.
This study presents a comprehensive analysis of the physicochemical parameters in Lake Goverdhan Sagar, aiming to provide valuable insights into its current environmental status. Water samples were collected from various predetermined sampling sites across the lake during Jan 2023 to April 2023 different sampling stations and depths. A set of physicochemical parameters including temperature, pH, dissolved oxygen (DO), electrical conductivity (EC), turbidity, total dissolved solids (TDS), and major ion concentrations (such as chloride, sulfate, calcium, and magnesium) were analyzed using standard methods and instruments. The average Temperature of water was 28.57 °C, Colour and Odour disagreeable, and pH of lake was found with mean value of 8.7. During the study the mean value of BOD 3.96 ppm and COD 45.88 ppm was observed. The mean value of dissolved Oxygen (DO) 5.48 was found and satisfactory for the survival and growth of aquatic organisms. Similarly the mean value of nitrogen was determined as 7.24 ppm, which is under permissible limit. The hardness is mainly due to calcium and magnesium ions. During the study, mean value of total hardness, Calcium hardness and Magnesium hardness was observed as 30.82 ppm, 7.40 ppm and 23.43 ppm respectively, which are under permissible limits. Finding of lake water which recorded mean value of total alkalinity 253.58 ppm. During the study mean value of chloride content observed as 165.20 ppm which is below the permissible limit and Fluoride content 0.58 ppm was found as a mean value. According to study the high value of pH, EC and TDS characteristics of Goverdhan Sagar Lake shows its nutrient rich and alkaline nature. The water quality indicated that the water of lake is suitable for the fishery and gardening purpose. However, water of the lake was not found suitable for potable and domestic uses as the high value of bacterial load, bio-chemical oxygen demand and Chemical oxygen demand showed its high pollution status
The freshwater on the surface of the world Just 2.5% is usable. In this sense, lakes are one of the most significant water resources. They have traditionally been utilized as a source of drinking water and make up around 0.3% of all surface water bodies. As a result, rising anthropogenic activity near lakes have caused their state to continuously worsen. In general, numerous physico-chemical and biological characteristics chosen from the Designated Best List are used to assess the quality of lake water (or water from other surface sources). Usage of the lake's water body for a variety of applications. As a result, the Water Quality Index (WQI) is a crucial instrument for identifying the lake water quality. Natural lakes are often small, enclosed pools of water without a sufficient flow to self-cleanse the water, which causes a buildup of different contaminants. In these situations, many indices, such the Heavy Metal Index (for heavy metals), eutrophication potential (due to nutrients), and other related indices system, are used to assess the quality of these contaminants. Determining existing properties aids in decision-making. of potential trends for these pollutants and, consequently, the lake water quality in the future. For the purpose of predicting future changes in lake water quality, a variety of modelling techniques are used, including watershed models, ground water models, and lake models. In order to provide an understanding of the various tools and techniques used for comprehensive water quality monitoring and management, the current study provides an overview and critically evaluates the literature on all aspects of water quality.
In the present study, the chemical characteristics of groundwater with respect to drinking and Irrigation water quality in
upper Thirumanimuthar sub-basin, Cauvery River, have been studied. 51 groundwater samples were collected and analysed for
pH, conductance, total dissolved solids, total hardness, calcium, magnesium, carbonate, bicarbonate, total alkalinity, chloride,
sodium, potassium, sulphate etc. The values analyzed were evaluated in detail and compared with WHO water quality standards.
It is observed that, for most of the groundwater quality parameters, the values are not potable for drinking and irrigational
use. To understand the spatial distribution of unsuitable zones, ArcGIS was employed. Attributes were linked and spatial interpolation
mapping was done. Inverse distance weighted interpolation technique was followed for raster and vector mapping. Finally the
overlay analyses were also carried out to locate the worst quality zone.
KeywordsSAR-Sodium percentage-GIS-Spatial distribution map-Overlay analysis-Cauvery River-Tamil Nadu
The dissolution of sodium-containing minerals in high-temperature geothermal systems can cause Na+ to exceed 400 mg/L with high salinity. But the Na+ of low-salinity geothermal water is mostly less than 100 mg/L in medium-low temperature geothermal systems. However, geothermal water with Na+ up to 325.4 mg/L and TDS less than 650 mg/L was found in the Huangshadong geothermal field, which is a typical medium-low temperature hydrothermal system in South China. The water chemistry results indicate that thermal groundwater is uniformly HCO3 -Na type with high sodium content (average 240.06 mg/L). All the thermal groundwater and shallow groundwater have the same meteoric origin based on δD and δ18 O. According to water chemical geothermometers and multicomponent mineral equilibrium (MME) method, the reservoir temperature is estimated to be 100-130°C at a maximum depth of 2.43 km. The estimation of the Cl- mixed indicator suggests that geothermal water has mixed with 51%-72% of shallow groundwater, resulting in the reduction of Na+ content in real geothermal water (Na+ up to 685.2 mg/L). The simulated results of water-rock interactions indicate that mineral dissolution and ion exchange have minor contributions to Na+ enrichment in geothermal water. Hydrochemical simulations and Gibbs diagrams suggest an additional source of high sodium: granite fluid inclusions are fractured into geothermal water at high temperatures. Granite fluid inclusions may only account for 3%-5% of geothermal water, but they provide the main source of Na+ in geothermal water.
In isolated fracture networks in the Precambrian Shield, long-term water and rock interactions produce saline anoxic fluids that host extant microbial communities deep within the continental subsurface. Light and oxygen (O2) are absent in these environments. Thus, chemotrophic organisms inhabiting these systems rely on anaerobic reactions for energy. Viable electron donors include short-chain alkanes, such as methane (CH4) and C2+ alkanes, while alternative electron acceptors include sulfate (SO2−4), nitrate (NO−3), and ferric iron (Fe³⁺). Here, we constrain the potential sources of energy for microorganisms in Neoarchean bedrock on the 27th level west drift of the Soudan Underground Mine State Park, MN, USA (713.5 meters below the surface). The Gibbs Free Energy (ΔG) of 11 reactions are modeled and expressed as available chemical potential energy per mass fluid (J/kgfluid). Metabolic reactions involving CH4 oxidation by SO2−4 would yield the highest potential energy of reactions modeled in this study (−111 J/kgfluid). The free energy for methanogenesis via the breakdown of dimethylamine (DMA; ∑(CH3)2NH(aq)) is exergonic but with near-zero available energy per mass fluid, suggesting that DMA may be cycled quickly to produce biological CH4 at Soudan. We examine all the possible pathways by which CH4 and other short-chain alkanes may be formed. Conventional δ13CCH4 values and C1/C2+ abundance ratios support a mixed biological and non-biological origin of CH4. Doubly substituted ‘clumped’ CH4 isotope ¹³CH3D values are consistent with formation temperatures of 84-89 °C that exceed current environmental conditions of 11.5-12.1 °C. These estimated formation temperatures are too low for CH4 to be formed solely through thermogenic degradation of organic matter. Further, low or undetectable H2 rules out active abiogenesis of CH4 from CO2 reduction. It is more likely that the bulk CH4 pool reflects a mixture of microbial CH4 with Δ13CH3D values equilibrated at 11.5-12.1 °C and thermogenic CH4 formed at temperatures >100 °C. Understanding the origin and cycling of these electron donors contributes to a fundamental understanding of how microbial activity may promote, maintain, or suppress the habitability of these isolated systems over long timescales.
Wells up to 3000 m deep at the foot of the active volcanoes Koryaksky and Avachinsky within the Avachinsky Depression revealed a basin of saline waters (up to 22 g/l), methane-rich gas (CH4 up to 75 vol% in dry gas) with a temperature up to about 70 °C in the western part of the explored area (Ketkino Field) and colder ones - to the east, closer to the Pacific coast. This article presents data on the chemical composition including trace elements, and isotopic compositions of these waters that include δD and δ¹⁸O of waters, ⁸⁷Sr/⁸⁶Sr of the dissolved Sr, ³He/⁴He, δ¹³C of CH4 and CO2 in gases, and δ³⁴S of the dissolved H2S and SO4. The composition of the waters is sodium chloride, with very low contents of sulfate and magnesium in waters of the western section of the basin, high calcium (up to 960 ppm), and unusually high concentrations of strontium (up to 54 ppm). The N2/Ar ratio is generally 2–3 times higher than in the air, i.e. non-atmospheric nitrogen is present. A distinctive geochemical feature of the basin is the significant difference between δ¹³C–CH4 and ⁸⁷Sr/⁸⁶Sr in the thermal Ketkino fluids comparing to colder fluids of other parts of the basin, despite the practically identical composition of waters and gases. Possible scenarios of water-rock interaction responsible for the chemical composition of waters are discussed.
Karstic aquifers are one of the most important freshwater resources, and in some areas, they are the only available water resources. These resources have significant challenges, including reduced quality and increased pollution. Izeh city in the southwest of Iran intensively depends on karstic water resources due to lack of access to surface water streams. Accordingly, five water wells were drilled to supply part of the city's and surrounding villages' drinking water in the Kamarderaz anticline plunge. During the drilling in the Atabaki area, two wells encountered H2S gas penetration and increased Ec during drilling, making the wells cumbering. The chemical parameters of water resources were measured to investigate the causes of qualitative changes in 4 states during two seasons in spring and summer over 2017-2018. Na /Cl, Br /Cl, I /Cl ion ratios, and Total Organic Carbon Index (TOC) was used to differentiate salinity sources, water sources mixing with brine, and the infiltration of hydrocarbons into water. In this study, statistical analysis, including PCA and AHC, was used to more accurately investigate the factors affecting the qualitative changes in the region. According to the statistical analysis in the area, two factors of carbonate mineral dissolution, evaporation and brine infiltration, have simultaneously affected the water quality, especially in the western part of the plunge anticline. TOC analysis and Na /Cl, Br /Cl, and I /Cl ratios illustrated the mixing of water and oil brines and infiltration of hydrocarbons.
Records of changing ice mass in offshore sediments and ice cores suggest that the West Antarctic ice sheet experienced millennial-scale ice loss during the last termination. However, the distal location and short temporal coverage of these records leads to uncertainty in both the spatial footprint of ice response, and whether this response persists outside of glacial terminations. Here we present a >100kyr archive of episodic Antarctic ice sheet basal melt events recorded by mineralogic variation in subglacial precipitates. 234U-230Th dates for two precipitates are used to build a time series of 32 opal-calcite transitions that correspond to Late Pleistocene millennial-scale climate cycles, with precipitation of opal during cold periods and calcite during warm periods. Geochemical data indicate that opal precipitation occurs via cryoconcentration of silica in brines beneath the ice sheet margin, while calcite precipitation is triggered by the addition of subglacial meltwater originating from the ice sheet interior. These freeze-flush cycles represent changes in subglacial hydrologic-connectivity driven by ice sheet velocity fluctuations, which likely occur in response to Southern Ocean thermal forcing acting on grounding lines within the Ross Embayment. Our results suggest that oscillating temperatures in the Southern Ocean affect the mass of the Antarctic ice sheet by regulating the delivery of heat to buttressing ice shelves and grounding lines on millennial timescales, regardless of the background climate state.
Understanding the controls on the behaviour of metalloids (Se, As) and metals (Cu, Zn, Pb) in natural aqueous systems is vital to interpreting hydrogeochemical data in environmental and mineral exploration applications. Geochemical, isotopic, and redox measurements of a suite of groundwaters sampled from around the ABM zone from the Kudz Ze Kayah (KZK) volcanogenic massive sulfide (VMS) deposit in the Yukon, Canada are presented and contrasted with other case studies from a variety of mineral deposit types. This deposit has atypically (high) As (up to 4.3 wt.%, average 2457 ppm) and Se (up to 2620 ppm, average 157 ppm) contents in the sulfide mineralization. As a relatively undisturbed deposit (unmined), it is an ideal site to study the mobility and solubility of trace metals in groundwaters. Herein we present field measurements (pH, dissolved oxygen, specific conductance, oxidation-reduction potential, and temperature), major ion, trace element, anion (Cl, Br, SO 4 , and PO 4 ), and stable isotope (δ ² H, δ ¹³ C DIC , δ ¹⁸ O, δ ¹⁸ O SO4 , δ ³⁴ S) data.
Waters are dominantly low-salinity HCO 3 to HCO 3 -SO 4 -type waters with variable sulfate (4.83 to 601 mg/L), Ca (23 – 235 mg/L) Mg (3.1 – 96.8 mg/L), Na (0.30 – 66.9 mg/L) and K (0.55 to 6.25 mg/L) concentrations. These waters also have variable trace element concentrations that include As (0.01 to 148 µg/L), Se (<0.02 to 1.01 µg/L), Fe (0.01 to 3.84 mg/L), Zn (<0.2 to 1070 µg/L), Pb (<0.01 to 8.4 µg/L), Cu (0.03 and 24.5 µg/L) and Sb (0.01 to 54.4 µg/L). Some waters also have elevated concentrations (compared to most meteoric waters) of Nb (up to 0.3 µg/L), Y (up to 1.42 µg/L), Zr (up to 18 µg/L), and the REE (sum REE up to 2.04 µg/L). The δ ¹⁸ O (-22.8 to -20.9 ‰) and δ ² H (-174 to -158 ‰), together with the δ ¹³ C DIC (-10.6 to +1.9 ‰), δ ³⁴ S (+10 to +12 ‰) and δ ¹⁸ O SO4 (15.5 to -4.75 ‰) all suggest that local meteoric water has interacted with massive sulfide mineralization at the ABM zone. Our results demonstrate the requirement for the use of multiple techniques in hydrogeochemical studies, with dissolved concentrations of major and trace elements coupled with a suite of stable isotopes that help define a larger geochemical footprint for the KZK deposit. Water-mineral interaction between groundwater aquifers and VMS deposits like the ABM zone are distinctly different from dispersion halos described from other deposit types (i.e., Cu porphyry, unconformity U).
Thematic collection: This article is part of the Hydrochemistry related to exploration and environmental issues collection available at: https://www.lyellcollection.org/cc/hydrochemistry-related-to-exploration-and-environmental-issues
The isotope ⁹⁴Nb (t1/2 = 2.04 ∙ 10⁴ a) is produced during the operation of nuclear reactors due to the neutron activation of ⁹³Nb present in reactor vessels. Related waste streams will be disposed of in cement-based repositories for low and intermediate level wastes (L/ILW).
The retention of niobium by cement was investigated using a combination of ⁹⁵Nb and natural ⁹³Nb. Sorption experiments assessed also the impact of iso-saccharinic acid (ISA) and chloride on Nb retention, both expected in specific L/ILW.
Sorption experiments revealed a strong uptake of Nb by cement. Isotopic exchange with ⁹³Nb in HCP partly explains ⁹⁵Nb uptake, although sorption on C-S-H is tentatively proposed as main retention process. Sorption of Nb is weakly affected by chloride, but decreases importantly at [ISA] ≥ 10⁻³ M reflecting the formation of (Ca-)Nb(V)-ISA complexes. This work provides key inputs to assess ⁹⁴Nb retention in the Safety Case context of nuclear waste repositories.
ABSTRACT The deep biosphere hosts uniquely adapted microorganisms overcoming geochemical extremes at significant depths within the crust of the Earth. Attention is required to understand the near subsurface and its continuity with surface systems, where numerous novel microbial members with unique physiological modifications remain to be identified. This surface-subsurface relationship raises key questions about networking of surface hydrology, geochemistry affecting near-subsurface microbial composition, and resiliency of subsurface ecosystems. Here, we apply molecular and geochemical approaches to determine temporal microbial composition and environmental conditions of filtered borehole fluid from the Edgar Experimental Mine (∼150 m below the surface) in Idaho Springs, CO. Samples were collected over a 4-year collection period from expandable packers deployed to accumulate fluid in previously drilled boreholes located centimeters to meters apart, revealing temporal evolution of borehole microbiology. Meteoric groundwater feeding boreholes demonstrated variable recharge rates likely due to a complex and undefined fracture system within the host rock. 16S rRNA gene analysis determined that unique microbial communities occupy the four boreholes examined. Two boreholes yielded sequences revealing the presence of Desulfosporosinus, Candidatus Nitrotoga, and Chelatococcus associated with endemic subsurface communities. Two other boreholes presented sequences related to nonsubsurface-originating microbiota. High concentration of sulfate along with detected sulfur reducing and oxidizing microorganisms suggests that sulfur related metabolic strategies are prominent within these near-subsurface boreholes. Overall, results indicate that microbial community composition in the near-subsurface is highly dynamic at very fine spatial scales (
In addition to high concentrations of CH4 and H2, abundant dissolved N2 is found in subsurface fracture fluids in Precambrian cratons around the world. These fracture fluids have hydrogeological isolation times on order of thousands to millions and even billions of years. Assessing the sources and sinks of N2 and related (bio)geochemical processes that drive the nitrogen cycle in these long isolated systems can shed insights into the nitrogen cycles on early Earth with implications for other planets and moons. In this study, we collected dissolved gas samples from deep subsurface fracture fluids at seven sites (Kidd Creek, LaRonde, Nickel Rim, Fraser, Copper Cliff South, Thompson, and Birchtree) in the Canadian Shield. Multiple gas components (e.g., H2, O2 and Ar) were integrated with δ¹⁵NN2 values to characterize the N2 signatures. Results show that the dissolved N2 in deep subsurface fracture fluids from the Canadian Shield sites are more ¹⁵N-enriched than those from the Fennoscandian Shield and the Witwatersrand Basin in the Kaapvaal Craton. The nitrogen isotopic signatures of the Canadian Shield samples coupled with their hydrogeological framework indicate the N2 was sourced from fixed ammonium in silicate minerals in host rocks and was generated by metamorphic devolatilization. Modeling of nitrogen devolatilization from host rocks supports this interpretation, but also suggests that a second process, likely abiotic N2 reduction, is required to account for the observed ¹⁵N enrichment in the N2 samples from the Canadian Shield. A 10-year monitoring study for one of the boreholes, at 2.4 km of the Kidd Creek Observatory, shows a steady decrease in δ¹⁵NN2 values with time, which coincides with the temporal isotopic evolution of some other gas components in this borehole. Although it cannot be confirmed at this time, this isotopic shift in N2 may be potentially attributed to microbial processes (e.g., anaerobic oxidation of ammonium). Nevertheless, the large ¹⁵N enrichments for the majority of the samples in this study suggest that the nitrogen cycle in the deep saline fracture fluids in the Canadian Shield is dominated by abiotic processes. This is in contrast to the nitrogen cycles in the subsurface fracture fluids in the Fennoscandian Shield and the Witwatersrand Basin, which have been shown to be strongly affected by extant microbial ecosystems discovered in those fracture waters.
Extraterrestrial materials consist of samples from the moon, Mars, Vesta and a variety of smaller bodies such as asteroidsAsteroids and comets. These planetary samples have been used to deduce the evolution of our solar system. A major difference between extraterrestrial and terrestrial materials is the existence of primordial isotopic heterogeneities in the early solar systemSolar system. These heterogeneities are not observed on Earth, because they have become obliterated during high-temperature processes over geologic time. Nevertheless, isotopes have been used as a genetic link between meteorites and the Earth (i.e. Clayton in Treatise on geochemistry, Elsevier, Amsterdam, 2004).
Copper–silver skarn occurrences in the McKenzie Gulch (MG) area are spatially associated with Middle Devonian (386.3 ± 2.3 Ma; UPb zircon) intermediate to felsic dyke swarms. Mineralization occurs as veins and stockwork veinlets, disseminations, patches, and locally as replacement of calc-silicate skarns in argillaceous limestone. Fluid inclusion data from the MG deposit suggest that hydrothermal systems associated with skarn formation evolved from an early magmatic-dominated stage to a late formation water and/or meteoric water-dominated stage. An early prograde endoskarn and exoskarn formed from high temperature (444–865 °C) and high salinity (36–40 wt% CaCl2 + NaCl) fluids, whereas retrograde skarn formed from low temperature (97–257 °C) and low salinity (1–15 wt% NaCl equiv.) fluids. The salinity gap between prograde and retrograde fluids (~ 4-fold dilution) may be due to throttling in the magmatic-hydrothermal system resulting in a pressure regime that alternated between dominantly lithostatic and hydrostatic. The δ³⁴S values of sulfides from the skarn deposit range from +4.6 to +9.1‰. These values are lower than the corresponding δ³⁴S values from the adjacent gold-bearing quartz-calcite-sulfide veins whose values range from +7.9 to +10.0‰. These high positive values suggest that magmatic hydrothermal fluids interacted with and incorporated significant amount of sulfides from sedimentary rocks, which typically have higher δ³⁴S values in the region.
Hydrothermal titanites from retrograde skarn ores were successfully dated by laser ablation-inductively coupled plasma-mass spectrometry (LA–ICP–MS) in an effort to constrain the timing of mineralization. These analyses yield weighted mean ²⁰⁶Pb/²³⁸U age of 387.2 ± 3.6 Ma, in agreement with ²⁰⁶Pb/²³⁸U age of 386.3 ± 2.3 Ma of zircon from associated porphyry dykes. The felsic porphyry dykes spatially associated with CuAg skarn at MG, coupled with fluid inclusion data, provide evidence for magmatic activity coincident with the mineralizing events. In addition, Pb isotope compositions of galena and other sulfides (chalcopyrite, pyrite and pyrrhotite) are compatible with a model linking the skarns with Early to Middle Devonian magmatic activity at depth that eventually interacted with and incorporated significant volumes of sedimentary host rocks. Consequently, the MG CuAg skarn mineralization occurred contemporaneously with the intrusion of porphyry dyke swarms.
The Archean Yellowknife Supergroup (Slave Structural Province. Canada) is composed of a thick sequence of supracrustal rocks, which differs from most Archean greenstone belts in that it contains a large proportion ( ~ 80%) of sedimentary rocks. Felsic volcanics of the Banting Formation are characterized by HREE depletion without Eu-anomalies, indicating an origin by small degrees of partial melting of a mafic source, with minor garnet in the residua. Granitic rocks include synkinematic granites [HREE-depleted; low ()I], post-kinematic granites [negative Eu-anomalies, high ()I] and granitic gneisses with REE patterns similar to the post-kinematic granites. Sedimentary rocks (turbidites) of the Burwash and Walsh Formations have similar chemical compositions and were derived from 20% mafic-intermediate volcanics, 55% felsic volcanics and 25% granitic rocks. Jackson Lake Formation lithic wackes can be divided into two groups with Group A derived from 50% mafic-intermediate volcanics and 50% felsic volcanics and Group B, characterized by HREE depletion, derived almost exclusively from felsic volcanics.REE patterns of Yellowknife sedimentary rocks are similar to other Archean sedimentary REE patterns, although they have higher . These patterns differ significantly from typical post-Archean sedimentary REE patterns, supporting the idea that Archean exposed crust had a different composition than the present day exposed crust.
Les études microthermométriques de 400 inclusions secondaires provenant des zones B et D du gisement Henderson montrent la coexistence de deux fluides, une solution aqueuse chlorurée, fortement chargée en sels (NaCl et CaCl2) et un fluide riche en méthane. Les analyses des ions en solutions effectuées sur 16 échantillons indiquent que Na+ et Ca+2 représentent la presque totalité des cations présents dans la solution. La température de formation déduite des observations sur la saturation en NaCl des solutions est de l'ordre de 240° ± 10°C. Utilisant l'isochore du méthane pour tracer celui de la saumure, la pression correspondante est voisine de 800 bars. Enfin les implications génétiques sont discutées.
La composition des inclusions fluides de filons et lentilles de quartz dans deux séries de roches métamorphiques rétromorphosées suggère un équilibre entre les fluides et les assemblages de minéraux rétromorphiques.
Les métagraywackes et amphibolites riches en calcium contiennent des saumures à CaCl2 et NaCl tandis que les métapélites pauvres en calcium contiennent des saumures riches en NaCl. La présence dans ces saumures d'autres constituants dissous comme KCl est possible mais n'a pas été confirmée.
Les réactions rétromorphiques suivantes suggèrent un mécanisme pour la concentration de Na+, K+ et Ca2+ dans les fluides, pour produire des filons et des lentilles de quartz et pour créer des conditions oxydantes durant la rétromorphose :
3 microcline + H2O = muscovite + 6 quartz + 2K+ + O-2 ;
3 albite + H2O + K+ = muscovite + 6 quartz + 3Na+ + O-2 ;
3 anorthite + 1 1/2H2O + K+ = épidote + muscovite + Ca+2 + 1/2O-2 ;
2 biotite + 4H2O = chlorite + 3 quartz + 2K+ + (Mg, Fe)+2 + O-2.
In the Thompson belt, ultramafic amphibolites occur within the metavolcanic-metasedimentary sequence, in mignatitic gneisses and in association with serpentinized peridotites. The amphibolites, in concordant lenses or sheets, commonly exhibit layering defined by the relative proportions of amphibole, olivine, orthopyroxene and spinel. CIPW norms, calculated on whole-rock analyses, indicate mainly picritic compositions. The association of metapicrites with metabasaltic rocks suggests an extrusive or hypabyssal origin, locally confirmed by pillows. Although no obvious spinifex textures have been found in these rocks, quench textures are preserved in some of the less deformed magnesian metabasalts; the others are completely amphibolitized. All the metapicrites in the Thompson belt are komatiitic, as shown by plots of Al2O3 versus FeO/(FeO + MgO). Variations in the FeO/ (FeO + MgO) ratio in individual units may reflect differentiation during solidification. Similarly, all the metavolcanic rocks are also komatiitic and chemically form a continuous trend with the metapicrites. This suggests derivation from the same magma source. Metapicrites associated with serpentinized peridotites are interpreted as differentiates of peridotite magma. The metapicritic portion is generally located at the margin of a given serpentinite body, and chemically continuous with it. These relationships clearly point to a common magma source. The metapicrites therefore comprise both ultramafic flows and hypabyssal intrusions genetically related to the serpentinites. Their complex metamorphic character indicates that they (and the serpentinites) are either early Hudsonian or pre-Hudsonian in age.
The content of total dissolved solids and δD and δO18 values are given for 95 oil-field brines from the Illinois, Michigan, and Alberta basins and the Gulf Coast. The variation in deuterium content among basins is found to be much greater than that within each basin. Oxygen isotopic composition, on the other hand, shows a large range in each basin, strongly correlated with salinity. The relationships between isotopic and chemical compositions of the brines lead to the following conclusions: (a) the water is predominantly of local meteoric origin; (b) the deuterium content has not been greatly altered by exchange or fractionation processes; (c) extensive oxygen exchange has taken place between water and reservoir rocks. Several samples contain water which appears to have originated as precipitation during Pleistocene glacial periods.
The results of geochemical and isotopic analyses of groundwater samples from five mines and several shallow wells in the Sudbury basin are discussed. Two distinctive water types are recognized: fresh to brackish waters were found from surface to approx 800 m in depth, but below 914 m very saline or briny waters occur at most of the localities sampled. The geochemistry of the shallow waters shows gradual increases in concentration for most elements. Isotopic data indicate that the major component of these waters is <30 yr of age and represents local meteoric waters. The saline waters have dissolved loads often >200 g/litre, and are dominated by Ca and chloride. The chemistry and isotopic contents of the Sudbury brines are very distinct from highly saline waters or brines of sedimentary or geothermal origin. The brines appear to represent very old, stagnant groundwaters which may have undergone prolonged chemical and isotopic alteration since their original emplacement. A variety of possible origins for the deep Sudbury waters can be postulated, but most models for brine formation are unsatisfactory to explain the origin and genesis of these deep Canadian Shield brines. -P.Br.
Twenty-four groundwater samples from seven operating mines at Sudbury, Yellow-knife and Thompson (Ontario, North West Territories and Manitoba, resp.), all from depths greater than 1 km and ranging in total dissolved solids (TDS) from 1900 to 250,000 mg l−1, were measured for their values. Each geographic location gives a limited range in values and each location is distinct from the others. This is interpreted as the result of extensive water-rock interaction on a local scale. For most of the time, these brines were isolated and only recently have been exposed to surface water as a result of the mining operations. The extent of the isolation is shown by the contrasting isotopic values of two “pockets” of water (0.711 vs. 0.716) located on opposite sides of the same fault system on the North Range at Sudbury. The exchange at all sites probably has continued until the present, as indicated by the close agreement between water and present-day whole-rock values. If so, it suggests that there is no single age for such brines, but it may be possible to date stages in the water's evolution by determining the age of secondary minerals that equilibrated with the water.
A brine may be defined as a solution containing more than 100,000 mg/l dissolved solids. Brines in sedimentary basins are genetically related to evaporites in one of three ways:dissolution of evaporite minerals generally halite;expulsion of interstitial fluids from evaporites; andalteration of hydrous evaporite minerals such as carnallite.
Most Na-Ca-Cl brines originate as interstitial fluids in halite-rich rocks. These fluids initially are rich in magnesium, sulfate, and potassium but evolve to a Na-Ca-Cl brine during migration to their present host rock. The principal reactions involved in present host rock. The principal reactions involved in the chemical evolution of these brines are dolomitization, sulfate reduction, albitization of plagioclase, and the formation of authigenic potassium aluminosilicates.
Introduction
Occurrences of brines in sedimentary basins containing intervals of bedded halite are known in a number of areas around the world. In many of these locations, certain stratigraphic intervals are important producers of hydrocarbons and, in some cases, contain producers of hydrocarbons and, in some cases, contain major base-metal deposits. The purpose of this investigation has been to develop a model for predicting the chemical composition of brines produced by the evaporation of sea water and a model for quantitatively predicting the changes in the composition of these brines predicting the changes in the composition of these brines as they migrate into sedimentary rocks and react with a variety of common minerals. If the brines and their associated hydrocarbons in oilfield reservoirs have migrated to their present position along the same path, the ability to determine the point of origin and the migration path of a brine from its chemical characteristics could be a valuable tool in petroleum exploration.
CLASSIFICATION AND ORIGIN OF BRINES
Carpenter has recommended the adoption of the water classification system shown in Table 1. This system has the advantages that it is geometric in progression, easy to remember, and coincides with lay progression, easy to remember, and coincides with lay terminology for saline water. The term brine, as defined in Table 1, has definite genetic implications. Natural aqueous solutions containing more than 100,000 mg/1 appear to originate either as a result of the crystallization of siliceous magma or as a result of some process involving evaporites (Table 2). Fluid inclusion studies of brines associated with porphyry copper deposits indicate that brines porphyry copper deposits indicate that brines produced by magmatic processes are Na-K-Cl brines. produced by magmatic processes are Na-K-Cl brines. The association of evaporites and brines in sedimentary basins has been recognized for a long time. Brines produced by the dissolution of highly soluble minerals such as halite have distinct compositions which can be used to determine the mineral or minerals which have been dissolved. Brines produced by the dissolution of halite consist almost entirely of sodium and chloride and have very low concentrations of bromide and calcium. The incongruent alteration of hydrous evaporite minerals has been described by Braitsch. These brines are usually very high in calcium and/or magnesium and relatively low in sodium. Their occurrence is generally restricted to the immediate vicinity of evaporite deposits containing potash salts. Sodium-calcium-chloride brines appear potash salts. Sodium-calcium-chloride brines appear to originate as interstitial fluids in evaporites and are then subsequently expelled as a result of the compaction which occurs in response to loading by younger sediments. Landes states that evaporite mineral accumulations usually have initial porosities in excess of 50 percent which is in considerable contrast to the percent which is in considerable contrast to the negligible porosities of ancient evaporites.
The modification of subsurface brine composition can occur through a variety of mechanisms. Mangles-dorf et al. have reviewed the effects of gravitational settling of ions, ion movement in a thermal gradient, and thermocell diffusion. They concluded that these mechanisms cannot account for the enrichment of dissolved salts found in brines but may modify compositions produced by other processes. Manheim and Horn have carefully evaluated the difficulties of producing brines by shale membrane filtration. They producing brines by shale membrane filtration. They concluded that the pressure requirements for appreciable salt-filtration remain unsatisfied by known geologic environments. They also noted that a second requirement of a filtration system capable of producing brines is that "enormous volumes of fluids must be pushed through poorly permeable (membrane-active) pushed through poorly permeable (membrane-active) strata in preference to permeable channels under virtually leak-free conditions."
The conventional procedure for analysis of 18O in aqueous solutions yield δ18O values on an activity scale rather than a value for the isotope concentration. Conversion between the two scales in natural chloridic solutions containing magnesium, calcium and potassium is given by the equation (δ0 − δm)/(1000 + δm) × 103 = 1.11 MMg + 0.47 MCa − 0.16 MK, where δ0 is the δ value on a concentration scale, δm the measured activity delta and M the molality. This linear equation holds up to molalities of 6 in pure and mixed salt solutions. The correction is of significance for a variety of geochemical processes, among them the use of the isotope content of different brines as an indicator of the salinization mechanisms of water sources.
Data for total and water-soluble chlorine in 96 granitic rocks from intrusions in Scotland, N Wales and SW England show that in general a third to two-thirds of the Cl is soluble. The soluble Cl content of the rocks increases with increasing total Cl content, being highest in the granites of SW England, but the ratio of soluble to total Cl decreases with increasing Cl content. A greater proportion of Cl is in a lattice-bound state in granites which have above average Cl contents. About 70% of the Cl in kaolinised granites is in a water-soluble state. This Cl is possibly absorbed in the kaolinite. Over 80% of the Cl in six xenoliths analysed was in an insoluble state and hence probably lattice-bound.
Fractures in the Eye–Dashwa pluton near Atikokan, Ontario can be subdivided on the basis of their filling materials. These materials include aplite, epidote, chlorite, and gypsum–carbonate–clay, listed in order of decreasing age established from crosscutting relations. Textures indicate that infilling occurred during fracture growth. Continuous cooling of the pluton during fracturing is inferred from the expected crystallization temperatures of fillings. Fracturing began before the pluton was completely solidified (650–600 °C) and continued to temperatures below 100 °C. Many fractures appear to have been sealed by the filling materials after initiation but were subsequently sheared and filled by lower temperature materials. Apparently the majority of fractures formed during or immediately after pluton solidification and new fractures became smaller and more restricted in location as cooling progressed. Fractures and filling materials are seen as important features in assessing the possibility of movement of radionuclides in aqueous solutions away from a nuclear fuel waste repository.
Distilled water was passed at a low rate down a temperature gradient through cylinders of Barre and Westerly Granite. Temperatures ranged from 80–100°C at the outer edges of the cylinders to 250–300°C in central, drilled holes which housed the heating coils. The measured permeabilities of the granite cylinders decreased by as much as two orders of magnitude in experiments of 1–3 weeks' duration. The amount of permeability decrease varied directly with temperature and inversely with the rate of fluid flow. The compositions of the fluids discharged from the granites were functions of temperature and flow rate as well as mineral composition, with dissolved silica concentrations showing trends different from those of the other analyzed species. Fluids from experiments run at higher temperatures but at much lower initial rates of fluid flow had higher concentrations of most ions but substantially lower dissolved silica contents. In contrast, an increase in temperature at similar rates of fluid flow resulted in higher silica concentrations. In the experiments, the distilled water acquired enough dissolved materials at high temperatures to become supersaturated with respect to several minerals at the low-temperature edges of the cylinders. Some of this material, particularly silica, was deposited along grain boundaries and microfractures, causing the observed permeability decreases. The very low rates of fluid flow in some high-temperature experiments significantly increased the rates of SiO2 precipitation and reduced dissolved silica concentrations relative to other species in the discharged fluids.
Stable isotopes of hydrogen and oxygen, together with chemical analyses, were determined for 20 surface waters, 8 shallow potable formation waters, and 79 formation waters from oil fields and gas fields. The observed isotope ratios can be explained by mixing of surface water and diagenetically modified sea water, accompanied by a process which enriches the heavy oxygen isotope. Mass balances for deuterium and total dissolved solids in the western Canada sedimentary basin demonstrate that the present distribution of deuterium in formation waters of the basin can be derived through mixing of the diagenetically modified sea water with not more than 2.9 times as much fresh water at the same latitude, and that the movement of fresh water through the basin has redistributed the dissolved solids of the modified sea water into the observed salinity variations. Statistical analysis of the isotope data indicates that although exchange of deuterium between water and hydrogen sulphide takes place within the basin, the effect is minimized because of an insignificant mass of hydrogen sulphide compared to the mass of formation water. Conversely, exchange of oxygen isotopes between water and carbonate minerals causes a major oxygen-18 enrichment of formation waters, depending on the relative masses of water and carbonate. Qualitative evidence confirms the isotopic fractionation of deuterium on passage of water through micropores in shales.
The chemical and isotopic compositions of saline groundwaters and brines in the Canadian Shield are described. The occurrence of such waters is very widespread, not related to any specific rock type or mineralization and, generally, can be expected at depths below 1 km. The most saline brines have salinities exceeding 200 g l−1. Dissolved solids and their chemistries tend to suggest that, in the past, saline waters penetrated the Canadian Shield. The original chemistry of these solutions was subsequently modified through strong rock-water interactions, and it appears that their final chemical compositions are independent of the original chemistries.Stable-isotope analyses indicate that these waters are not simple evaporated seawater, sedimentary-basin brines, hydrothermal solutions, or residual ore-forming fluids, although any of these could be a precursor of the brines. Secondary isotope-exchange reactions, and the hydration of primary silicates, accompanied by the formation of clay minerals, could have modified not only the primary isotopic composition but may have also profoundly influenced the chemistries of these brines. To be effective these processes would have had to occur in closed systems.
Kinetic dissolution experiments on serpentine, forsterite and enstatite over a wide pH range at 25°C show that there is an initial rapid exchange of surface magnesium ions with hydrogen ions followed by a longer period of hydrogen exchange and extraction of internal magnesium and silicon, with the amount extracted proportional to . The parabolic exchange kinetics are consistent with either of two rate controlling mechanisms: nonsteady state diffusion of ions within the mineral and quasi-steady state diffusion of ions through a leached shell surrounding the mineral. Diffusion coefficients for magnesium are greater than for silicon for each of the minerals, leading to incongruent dissolution over moderate time periods. The diffusion coefficients decrease in the order forsterite > serpentine > enstatite. Eventually the parabolic exchange rates decrease to the rate of dissolution of all material at the aqueous interface. Hence, over very long periods the amount of silicon and magnesium dissolved is proportional to t and dissolution is congruent. In highly acid solutions dissolution rates are fast and this terminal condition is reached much sooner.
Saline groundwaters (up to 19,100 mg 1−1 total mineralisation) issue in tin mines in the Carnmenellis Granite in Cornwall (U.K.) at depths up to 800 m. Their stable-isotope composition rules out seawater as a contributor to salinity. Circulation experiments carried out during Hot Dry Rock (HDR) reservoir development in the same granite also produce return fluids with enhanced salinities. Acid hydrolysis of plagioclase and biotite are proposed as the main sources of salinity in the groundwater. Experimental studies carried out on biotites from a borehole used for HDR evaluation demonstrate the reactivity of the biotite and confirm the hypotheses of the field studies.Mg, Li, K and silica levels in reacted solutions reflect the stoichiometric composition of the biotite. Chloride, Na and Ca in solution, on the other hand, are enriched between 1 and 3 orders of magnitude over that of biotite, reflecting the strongly incongruent nature of the reaction. Quartz and chalcedony saturation of the groundwaters encourages silica (or silicate) deposition rather than dissolution of rock-forming quartz; this argues against fluid inclusions as the source of salinity and suggests that new inclusions might be formed. The proposed model for the genesis of saline water therefore links together, or explains, several processes — groundwater movement, convective heat transport, the chemistry of the water, water-rock interaction, secondary mineral (including kaolinite) formation and fluid inclusion formation and stability.
Six Deep Sea Drilling Project (DSDP) Sites (252, 285, 315, 317, 336, 386) were examined for the chemical composition of the dissolved salts in interstitial waters, the oxygen isotopic composition of the interstitial waters, and the major ion composition of the bulk solid sediments. An examination of the concentration-depth profiles of dissolved calcium, magnesium, potassium, and H218O in conjunction with oxygen isotope mass balance calculations confirms the hypothesis that in DSDP pelagic drill sites concentration gradients in Ca. Mg. K, and H218O are largely due to alteration reactions occurring in the basalts of Layer 2 and to alteration reactions involving volcanic matter dispersed in the sediment column. Oxygen isotope mass balance calculations require substantial alteration of Layer 2 (up to 25% of the upper 1000 m). but only minor exchange of Ca, Mg, and K occurs with the overlying ocean. This implies that alteration reactions in Layer 2 are almost isochemical.
A standard, based on the set of ocean water samples used by Epstein and Mayeda to obtain a reference standard for oxygen-18 data, but defined relative to the National Bureau of Standards isotopic reference water sample, is proposed for reporting both deuterium and oxygen-18 variations in natural waters relative to the same water. The range of absolute concentrations of both isotopes in meteoric-waters is discussed.
A new mineral, calcium chloride hexahydrate, was discovered in the Don Juan Pond in Victoria Land, Antarctica. The optical properties, chemical analysis, and powder patterns obtained by x-ray diffraction agree with those of artificial calcium chloride hexahydrate. The name Antarcticite is proposed for the new mineral.
Origin of saline groundwaters in the Cammenellis granite: natural process and reaction during hot rock reservoir cir-culation
- Edmunds W M L F Kay R
- Mccartney R
EDMUNDS W. M., KAY R. L. F. and MCCARTNEY R. (1983) Origin of saline groundwaters in the Cammenellis granite: natural process and reaction during hot rock reservoir cir-culation. Proc. Int. Symposium on Water Rock Interaction.
On the effects of the lithological composition of rocks on the chemical composition of ground waters under the conditions ofthe Cola Peninsula
- Neyhdanova I K Sve~hnikov
- G B P Svetin Y
NEYHDANOVA I. K., SVE~HNIKOV G. B. and SVETIN Y. P. (1976) On the effects of the lithological composition of rocks on the chemical composition of ground waters under the conditions ofthe Cola Peninsula. Proc. Int. Symposium on Water-Rock Interaction, Czechoslovakia, 1974, Geo-logical Survey Prague, pp. 92-95.
Origin of saline formation waters Geochemistry of Oil Field Waters Standard for reporting concentrations of deuterium and oxygen-18 in natural waters
- Clayton R N Friedman
- I Graf
- D L Mayeda
- T K Meents
- W F F Shimp N
CLAYTON R. N., FRIEDMAN I., GRAF D. L., MAYEDA T. K., MEENTS W. F. and SHIMP N. F. (1966) Origin of saline formation waters. J. Geophys. Res. 71, 3869-3882. COLLINS A. G. (1975) Geochemistry of Oil Field Waters. Elsevier. 485 pp. CRAIG H. (1961) Standard for reporting concentrations of deuterium and oxygen-18 in natural waters. Science 133, 1833-1834.
Chemical analyses of Canadian rocks, minerals and ores Strontium isotopic composition of some Precambrian Shield brines
- Maxwell J A R Dawson K
- M E Mcnutt
- R H Frape
MAXWELL J. A., DAWSON K. R. and TOMLIN~ON M. E. (1965) Chemical analyses of Canadian rocks, minerals and ores. Geol. Surv. Can. Bull. 100, 500 p. MCNUTT R. H., FRAPE S. K. and FRITZ P. (1984). Strontium isotopic composition of some Precambrian Shield brines. Isotope Geoscience (in press).
Metamorphism of natural water Acta Dissolution kinetics of magnesium silicates. Geochim. Cos-8, 198-212. mochim
- Cheb~tarev I I W Luce R
- Parks W Bartlett R
CHEB~TAREV I. I. (1955) Metamorphism of natural water LUCE R. W., BARTLETT R. W. and PARKS G. A. (1972) in the crust of weathering-3. Geochim. Cosmochim. Acta Dissolution kinetics of magnesium silicates. Geochim. Cos-8, 198-212. mochim. Acta 36, 35-50.
Influence of geology on the chemical compositions of groundwaters-Analysis of Na, K, Ca, Mg, and Sr utilizing a chemical leaching method
- Tamari Y Tsuji H
- Kusaka Y
TAMARI Y., TSUJI H. and KUSAKA Y. (1983) Influence of geology on the chemical compositions of groundwaters-Analysis of Na, K, Ca, Mg, and Sr utilizing a chemical leaching method. Proc. Int. Symposium on Water-Rock Interaction. Misasa, Japan, pp. 472-474.
Chemical analyses of Canadian rocks, minerals and ores
- Maxwell
Conceptual framework for the chemical processes in the Stripa ground waters
- Nordstrom
Nickel-copper mineralization in the Lynn Lake gabbro
- Pinsent
A survey of low temperature water-mineral relations
- Garrels
Influence of geology on the chemical compositions of groundwaters— Analysis of Na, K, Ca, Mg, and Sr utilizing a chemical leaching method
- Tamari
Saline Brines in Crystalline Basement Rocks
- Vovk
Genesis of some ground waters from igneous rocks
- Garrels
On the effects of the lithological composition of rocks on the chemical composition of ground waters under the conditions of the Cola Peninsula
- Neyhdanova
Metamorphism of natural waters in the crust of weathering—3
- Chebotarev
Geochemistry and isotope hydrology of groundwaters in the Stripa granite. Swedish-American Cooperative Program on Radioactive Waste Storage in Mine Caverns in Crystalline Rock
- Fritz