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1.
The study of groundwater hydrogeochemistry of a hard rock aquifer system in Thoothukudi district has resulted in a large geochemical data set. A total of 100 water samples representing various lithologies like Hornblende Biotite Gneiss, Alluvium Marine, alluvium Fluvial, Quartzite, Charnockite, Granite and Sandstone were collected for two different seasons and analyzed for major ions like Ca2+, Mg2+, Na+, K+, HCO3 ?, Cl?, SO4 2?, NO3 ?, PO4 ?, F? and H4SiO4. Statistical analysis of the data has been attempted to unravel the hidden relationship between ions. Correlation analyses and factor analyses were applied to classify the groundwater samples and to identify the geochemical processes controlling groundwater geochemistry. Factor analysis indicates that sea water intrusion followed by leaching of secondary salts, weathering and anthropogenic impacts are the dominant factors controlling hydrogeochemistry of groundwater in the study area. Factor score overlay indicate major active hydrogeochemical regimes are spread throughout the Eastern, Northwestern and Southeastern parts of the study area. The dominant ions controlling the groundwater chemistry irrespective of season are Cl?, Na+, Mg2+, Ca2+, SO4 2?, K+ and NO3 ?. An attempt has also been made to note the seasonal variation of the factor representations in the study area. This study also illustrates the usefulness of statistical analysis to improve the understanding of groundwater systems and estimates of the extent of salinity/salt water intrusion.  相似文献   

2.
The aim of the present study is to identify the geochemical processes responsible for higher fluoride (F–) content in the groundwater of the Yellareddigudem watershed located in Nalgonda district, Andhra Pradesh. The basement rocks in the study area comprise mainly of granites (pink and grey varieties), which contain F-bearing minerals (fluorite, biotite and hornblende). The results of the study area suggest that the groundwater is characterized by Na+: HCO facies. The F– content varies from 0.42 to 7.50 mg/L. In about 68% of the collected groundwater samples, the concentration of F– exceeds the national drinking water quality limit of 1.5 mg/L. The weathering of the granitic rocks causes the release of Na+ and HCO ions, which increase the solubility of ions. Ion exchange between Na+ and Ca2+, and precipitation of CaCO3 reduce the activity of Ca2+. This favours dissolution of CaF2 from the F-bearing minerals present in the host rocks, leading to a higher concentration of F– in the groundwater. The study further suggests that the spatial variation in the F– content appears to be caused by difference in the relative occurrence of F-bearing minerals, the degree of rockweathering and fracturing, the residence time of water in the aquifer materials and the associated geochemical processes. The study emphasizes the need for appropriate management measures to mitigate the effect of higher F groundwater on human health.  相似文献   

3.
The compositional characteristics of many geochemical systems which involve the interaction of natural aqueous solutions with minerals and gases are conveniently described using the following thermodynamic components: Cl?, SO4=, HS?, CO3=, H+, Na+, K+, Ca++, Mg++, Fe++, Zn++, Cu+, Al+++, SiO2 and H2O. A set of mass balance and mass action equations equal in number to the number of components plus the number of saturated minerals (and gases) is defined for a specified temperature, pressure and bulk composition. The mass balance equations include terms for minerals, gases and the molalities of aqueous complexes and dissociated species. This set of non-linear equations can be solved with the aid of a computer using'a Newton-Raphson technique. The calculation takes account of aqueous ion complexing, oxidation-reduction equilibria, activity coefficients, non-unit water activity and solid solutions. The use of H+, SO4=, HS? and H2O as components allows straightforward treatment of processes involving oxidation-reduction, evaporation, boiling and changes of total aqueous H+ due to hydrolysis, mineral reaction or temperature change. One product of this approach is a technique for calculating pH at high temperature from measurement of pH at room temperature.By linking a series of discrete overall heterogeneous equilibrium calculations in which incremental changes of bulk composition, temperature or pressure are made, dynamic geochemical processes can be modeled. Example calculations for two such processes are given. These are the heating of seawater from 25° to 300°C and the isothermal irreversible reaction of rhyolite with an aqueous solution at 250°C.  相似文献   

4.
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5.
The detailed hydro-chemical study of meltwater draining from Khangri glacier Arunachal Pradesh has been carried out to evaluate the major ion chemistry and weathering processes in the drainage basin. The investigative results shows that the meltwater is almost neutral to slightly acidic in nature with Mg–HCO3-dominated hydro-chemical facies. In glacial meltwater, Ca+?2 is the most dominated cation followed by Mg+2, Na+, and K+, while HCO3? is the most dominant anion followed by SO42?, NO3?, and Cl?. The dominant cations such as Ca+2 and Mg+2 show a good relation with the minerals abundance of the rocks. Calcite (CaCO3) and biotite [K(Mg,Fe)3AlSi3O10(F,OH)2] are the most abundant minerals in the deformed carbonate-rich metasedimentary rocks near to the snout with some K feldspar (KAlSi3O8) and quartz (SiO2). This suggests Ca+2 have definitely entered into the water due to the dissolution of calcite and Ca feldspar (CaAl2Si2O8), while one of the source of Mg+2 is biotite. Na feldspar (NaAlSi3O8) has contributed towards the availability of sodium ion, while potassium ion is derived from the chemical weathering of K feldspar and biotite. The chemical weathering is the foremost mechanism controlling the hydro-chemistry of the Khangri glacier because of the least anthropogenic interferences. The mineralogy of surrounding rocks is studied to understand better, the rock–water interaction processes, and their contribution towards ionic concentration of meltwater. The meltwater discharge and individual ion flux of the catchment area have also been calculated, to determine the ionic denudation rate for the ablation season. The high elemental ratio of (Ca?+?Mg)/(Na?+?K) (7.91?±?0.39 mg/l) and low elemental ratio of (Na?+?K)/total cations (0.11?±?0.004) indicate that the chemical composition of meltwater is mainly controlled by carbonate weathering and moderately by silicate weathering. The scatter plot result between (Ca?+?Mg) and total cations confirms that carbonate weathering is a major source of dissolved ions in Khangri glacier meltwater. In addition, the statistical analysis was also used to determine the correlation between physical parameters of glacier meltwater which controlled the solute dynamics.  相似文献   

6.
Detailed hydrogeochemical investigation has provided new information concerning the major factors and mechanisms controlling the groundwater chemistry of Chougafiya basin. The hydrogeochemical characteristics of groundwaters comprise three main types: Cl–SO4–Ca, Cl–SO4–Na and Cl–Na. Hydrochemical characteristics based on the bivariate diagrams of major (Cl?, SO4 2?, NO3 ?, HCO3 ?, Na+, Mg2+, K+ and Ca2+) and some trace (Br? and Sr2+) ions, mineral saturation indices and hierarchical cluster analysis indicate different origins of groundwater mineralization. The water–rock interaction (dissolution of evaporitic minerals), followed by cation exchange reactions with clay minerals, constitute the main processes that control groundwater salinization. However, the chemical composition of brackish groundwater in the central and southern parts of the study area is influenced by a mixing process with Sabkhas salt groundwater. The mixing proportions inferred from chloride mass balance prove that the contribution of Sabkhas groundwater to Quaternary aquifer ranges between 2.7 and 9.1 %. These intrusion rates reflect the progress of the saltwater–freshwater interface, which is mainly controlled by the piezometric level variation and the distance to the Sabkhas.  相似文献   

7.
Hydogrochemical investigation of groundwater resources of Paragraph district has been carried out to assess the solute acquisition processes and water quality for domestic and irrigation uses. Fifty-five groundwater samples were collected and analyzed for pH, electrical conductivity, total dissolved solids, hardness, major anions (F?, Cl?, NO3, HCO3 ?, SO4 2?) and cations (Ca2+, Mg2+, Na+, K+). Study results reveal that groundwater of the area is alkaline in nature and HCO3 ?, Cl?, Mg2+, Na+ and Ca2+ are the major contributing ions to the dissolved solids. The hydrogeochemical data suggest that weathering of rock forming minerals along with secondary contributions from agricultural and anthropogenic sources are mainly controlling the groundwater composition of Pratapgarh district. Alkaline earth metals (Ca2++Mg2+) exceed alkalis (Na++K+) and weak acid (HCO3 ?) dominate over strong acids (Cl?+SO4 2?) in majority of the groundwater samples. Ca-Mg-HCO3 and Ca-Mg-Cl-HCO3 are the dominant hydrogeochemical facies in the groundwater of the area. The computed saturation indices demonstrate oversaturated condition with respect to dolomite and calcite and undersaturated with gypsum and fluorite. A comparison of groundwater quality parameters in relation to specified limits for drinking water shows that concentrations of TDS, F?, NO3 ? and total hardness exceed the desirable limits in many water samples. Quality assessment for irrigation uses reveal that the groundwater is good for irrigation. However, values of salinity, sodium adsorption ratio (SAR), residual sodium carbonate (RSC), %Na and Kelley index are exceeding the prescribed limit at some sites, demanding adequate drainage and water management plan for the area.  相似文献   

8.
The hydrogeochemistry of groundwater in rural parts of Birbhum district, West Bengal, India, has been studied to understand the contaminants and prime processes involved in their enrichment with a focus on F? concentration. The lithological units consist of Quaternary alluviums with underlying Rajmahal basaltic rocks of Middle Jurassic age. Groundwater occurs in the alluviums, weathered residuum and fracture zone of Rajmahal rocks. Studies show elevated concentration of Cl?, SiO2, Fe and F?; excess Cl? is attributed to anthropogenic inputs, SiO2 is ascribed to high degree of weathering of silica rich host rocks, and high Fe is due to the interaction of water with Fe-rich sediments under reducing condition. The F? concentration is found high (>1.20 mg/L) mainly in water from Rajmahal rocks revealing a lithological control on F? enrichment. The weathering of silicates and ion exchange are the leading controlling processes for major ions in groundwater. The F? enrichment is due to the dissolution of F?-bearing minerals and perhaps also through anion exchange (OH? for F?) on clay minerals at high alkaline conditions; precipitation of CaCO3 favours CaF2 dissolution leading to elevated F? concentration. CaHCO3, the dominant water type, contains low F? while NaHCO3 and NaCl types exhibit high F? concentrations. Among the three spatial associations, Cluster-1 and Cluster-2 are CaHCO3 type; Cluster-3 shows NaHCO3 and NaCl waters with low Ca2+ and Mg2+ and high Na+ contents. Cluster-1 and Cluster-2 waters are, in general, drinkable barring the elevated Fe content, while Cluster-3 water is unsafe for drinking due to the high F? concentration.  相似文献   

9.
The reservoir temperature and conceptual model of the Pasinler geothermal area, which is one of the most important geothermal areas in Eastern Anatolia, are determined by considering its hydrogeochemical and isotope properties. The geothermal waters have a temperature of 51 °C in the geothermal wells and are of Na–Cl–HCO3 type. The isotope contents of geothermal waters indicate that they are of meteoric origin and that they recharge on higher elevations than cold waters. The geothermal waters are of immature water class and their reservoir temperatures are calculated as 122–155 °C, and their cold water mixture rate is calculated as 32%. According to the δ13CVPDB values, the carbon in the geothermal waters originated from the dissolved carbon in the groundwaters and mantle-based CO2 gases. According to the δ34SCDT values, the sources of sulfur in the geothermal waters are volcanic sulfur, oil and coal, and limestones. The sources of the major ions (Na+, Ca2+, Mg2+, Cl?, and HCO3 ?) in the geothermal waters are ion exchange and plagioclase and silicate weathering. It is determined that the volcanic rocks in the area have effects on the water chemistry and elements like Zn, Rb, Sr, and Ba originated from the rhyolite, rhyolitic tuff, and basalts. The rare earth element (REE) content of the geothermal waters is low, and according to the normalized REE diagrams, the light REE are getting depleted and heavy REE are getting enriched. The positive Eu and negative Ce anomalies of waters indicate oxygen-rich environments.  相似文献   

10.
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11.
Rock water interactions play an important role in the flow of groundwater. Groundwater samples were collected from deep production wells with depths ranging from 120 to 230 m. Complete chemical analysis of 40 groundwater samples was collected from the fractured limestone aquifer including major cations (Na+, K+, Ca2+, Mg2+) and major anions (Cl?, SO4 2?, HCO3 ?, CO3 2?). A geochemical modeling (NETPATH Software) was applied for environmental simulate net geochemical mass-balance reactions between initial and final waters along a hydrologic flow path. This program simulates selected evolutionary waters for every possible combination of the plausible phases that account for the composition of a selected set of chemical constraints in the system. The groundwater of the Eocene aquifer mainly belongs to fairly fresh water with salinity contents ranging from 228 to 3595 ppm. The measured groundwater levels range between 8 and 25 m near the river Nile to the limestone plateau (eastwards). Consequently, groundwater flows from east to westward toward the river Nile. Groundwater aquifer in the study area is mainly composed of fractured limestone; the saturated states of the PCO2, calcite, aragonite, dolomite, siderite, gypsum, anhydrite, hematite, and goethite in addition to H2 gas were estimated. The undersaturated state of carbon dioxide reflects closed conditions and very low probability of recent recharge, and it reveals also the high tendency of water to precipitates carbonate species. Undersaturation by carbonate minerals is only restricted to some pockets distributed on the different places of the aquifer in the study area. The majority of groundwater samples of Eocene aquifer in the study area indicated that groundwater is not suitable for irrigation with treatment and requires good drainage.  相似文献   

12.
Groundwater is the most important source of water supply in Iran and understanding the geochemical evolution of groundwater is important for sustainable development of the water resources in Tabas area. A total of 29 samples of groundwater in Tabas area have been analyzed for ions and major elements. Groundwater of the study area is characterized by the dominance of Na–Cl water type. Groundwater was generally acidic to high alkaline with pH ranging from 5.42 to 10.75. The TDS as a function of mineralization characteristics of the groundwater ranged from 479 to 10,957 mg/l, with a mean value of 2,759 mg/l. The Ca2+, Mg2+, SO4 2? and HCO3 ? were mainly derived from the dissolution of calcite, dolomite and gypsum. The Cu, Pb and Zn ions are not mobile in recent pH–Eh, but these conditions controlled dissolved Se, V and Mo in groundwater. The As is released in groundwater as a result of the weathering of sulfide minerals like arsenopyrite.  相似文献   

13.
A study was carried out in the Madurai district of Tamil Nadu, India to identify the hydrogeochemical processes using factor analysis as a predictive tool. It also focuses on characterizing the samples of these factors with respect to standard geochemical plots. In order to obtain a synoptic view of the statistics and the geochemical processes, a total of 53 groundwater samples are collected representing the entire district. The major ions were analyzed; the order of ion dominance are Ca2+?>?Na+?>?Mg2+?>?K+?=?Cl??>?HCO? 3?>?H4SiO? 4?>?NO? 3?>?SO2? 4?>?P3? 4. The samples are classified according to three factors. Factor 1 shows strong positive loadings of Cl?, Ca2+, Mg2+, and NO? 3 with 36.98 % of the total variance (TV); factor 2 accounts for 13.72 % of TV with high loadings of Na+, K+, and HCO? 3; and factor 3 shows strong positive loadings of PO3? 4 and SO2? 4 with TV of 13.1 %. In the Piper plot, few samples fall in the mix region as evidenced by the mixing proportion of two samples using AQUACHEM software. The results suggest that different hydrogeochemical processes, like weathering, ion exchange processes, and anthropogenic activities (like sewage infiltration and agriculture), has predominant impact in the study area. Thus, the study highlights the factor analysis technique as a predictive and effective tool for groundwater evolution.  相似文献   

14.
河北汤泉地热流体水文地球化学特征及其成因   总被引：7，自引：5，他引：2       下载免费PDF全文
提要：汤泉位于河北省遵化市西北部,为山前丘陵地貌,地热资源丰富。本文通过对该地区地热流体研究发现：Na+、Ca2+、K+、Mg2+与SO2-4、HCO-3、Cl-、NO-3是该地区地下热水的主要成分,水化学类型主要为SO2-4-Na+型,属于未污染的天然弱碱性水;流体中F-含量平均为9.36 mg/l,远高于国家地下水质量标准ⅴ级;可溶性SiO2的含量可作为地热温标;地热流体总矿化度平均为782.33 mg/l,属于淡水;为中等腐蚀型水,不结碳酸钙垢,无CaSO4?2H2O垢和SiO2垢生成的可能;地热流体属于含岩盐地层溶滤的陆相沉积水;根据氢氧稳定同位素可知,河北汤泉地热流体主要来源于大气降水。  相似文献   

15.
The Vea catchment, mainly underlain by crystalline basement rocks, is located in Northern Ghana. Hydrogeochemical studies were carried out in this area with the objective of identifying the geochemical processes influencing water quality and suitability of surface and groundwater for agricultural and domestic uses. Sixty-one groundwater and four surface water samples were collected from boreholes, dams and rivers and analysed for Ca2+, Mg2+, Na+, K+, HCO3 ?, Cl?, and SO4 2?, Fetot, PO4 3?, Mntot, NH4 +, NO3 ?, NO2 ?. In addition, pH, total dissolved solids, electrical conductivity, total hardness, turbidity, colour, salinity and dissolved oxygen were analysed. Chloro-alkaline indices 1 and 2, and characterization of weathering processes suggest that the chemistry of groundwater is dominated by the interaction between water and rocks. Cation exchange and silicate weathering are the dominant processes controlling the chemical composition of the groundwater in the area studied. Mineral saturation indices indicate the presence of at least three groups of groundwater in the Vea catchment with respect to residence time. The meteoric genesis index suggests that 86% of the water samples belong to the shallow meteoric water percolation type. The findings further suggest that the groundwater and surface water in the basin studied are mainly Ca–Mg–HCO3 water type, regardless of the geology. Compared to the water quality guidelines of WHO, the study results on sodium absorption ratio, sodium percentage, magnesium hazard, permeability index and residual sodium carbonate indicate that groundwater and surface water in the Vea catchment are generally suitable for drinking and irrigation purposes.  相似文献   

16.
One hundred forty-eight groundwater samples were collected from the lower part of Wadi Siham catchment area for hydrogeochemical investigations to understand the hydrogeochemical processes affecting groundwater chemistry and their relation with groundwater quality. Groundwater in the study area is abstracted from different aquifers. The study area is characterized by arid climate and extremely high relative humidity. The results indicate that groundwater in the study area is fresh to brackish in nature. The abundance of the major ions is as follows: Na+1?>?Ca+2?>?Mg+2?≥?K+1 and Cl?1?>?HCO 3 ?1 ?>?SO 4 ?2 ?>?NO 3 ?1 . Various graphical and ionic ration plots, statistical analyses, and saturation indices calculations have been carried out using chemical data to deduce a hydrochemical evaluation of the study area. The prevailing hydrogeochemical processes operating in the study area are dissolution, mixing, evaporation, ion exchange, and weathering of silicate minerals in the eastern part (recharge areas). The reverse ion exchange and seawater intrusion control the groundwater chemistry along the Red Sea coast areas and few parts of the study area. Deterioration in groundwater quality from anthropogenic activities has resulted from saltwater intrusion along the coastal areas due to groundwater overpumping and extensive use of fertilizers and infiltration of sewage water. Salinity and nitrate contamination are the two major problems in the area, which is alarming considering the use of this water for drinking.  相似文献   

17.
A study of the hydrochemical evaluation of waters in the I??kl? Lake and surrounding area was carried out with the objective of identifying the geochemical processes and their relation with water quality in the region. The multivariate statistical techniques were used in the hydrochemical evaluation of waters. Statistical analysis of water quality parameters was made to seeing the interrelationship between different variables in order to explain the water quality and pollution status of study area. For this purpose, water samples were taken from lake, river, stream, and springs which are represented by investigated area and water qualities were evaluated. Generally, Ca2+, Mg2+, and Cl?, HCO3 ? ions are dominant within surface water and water sources. Arsenic concentration increase is determined in I??kl? spring and Kufi stream water samples. Also, aluminum concentration is high level in the Kufi stream water samples. This increase was related to igneous rocks as geogenic origin. Also, geogenic contamination was identified in R-mode factor and cluster analyses. There is high correlation between electrical conductivity and major ions of waters.  相似文献   

18.
Groundwater survey has been carried out in the area of Gummanampadu sub-basin located in Guntur District, Andhra Pradesh, India for assessing the factors that are responsible for changing of groundwater chemistry and consequent deterioration of groundwater quality, where the groundwater is a prime source for drinking and irrigation due to non-availability of surface water in time. The area is underlain by the Archaean Gneissic Complex, over which the Proterozoic Cumbhum rocks occur. The results of the plotting of Ca2+ + Mg2+ versus HCO3 ? + CO3 2?, Ca2+ + Mg2+ versus total cations, Na+ + K+ versus total cations, Cl? + SO4 2? versus Na+ + K+, Na+ versus Cl?, Na+ versus HCO3 ? + CO3 2?, Na+ versus Ca2+ and Na+: Cl? versus EC indicate that the rock–water interaction under alkaline condition is the main mechanism in activating mineral dissociation and dissolution, causing the release of Ca2+, Mg2+, Na+, K+, HCO3 ?, CO3 2?, SO4 2? and F? ions into the groundwater. The ionic relations also suggest that the higher concentrations of Na+ and Cl? ions are the results of ion exchange and evaporation. The influences of anthropogenic sources are the other cause for increasing of Mg2+, Na+, Cl?, SO4 2? and NO3 ? ions. Further, the excess alkaline condition in water accelerates more effective dissolution of F?-bearing minerals. Moreover, the chemical data plotted in the Piper’s, Gibbs’s and Langelier–Ludwig’s diagrams, computed for the chloro-alkaline and saturation indices, and analyzed in the principal component analysis, support the above hypothesis. The groundwater quality is, thus, characterized by Na+ > Ca2+ > Mg2+ > K+: HCO3 ? + CO3 2? > Cl? > SO4 2? > NO3 ? > F? facies. On the other hand, majority of groundwater samples are not suitable for drinking with reference to the concentrations of TDS, TH, Mg2+ and F?, while those are not good for irrigation with respect to USSL’s and Wilcox’s diagrams, residual sodium carbonate, and magnesium hazard, but they are safe for irrigation with respect to permeability index. Thus, the study recommends suitable management measures to improve health conditions as well as to increase agricultural output.  相似文献   

19.
Geothermal water is plentiful in Changbai Mountain region, northeastern China, due to the volcanic activities and widespread faults. For the exploration of geothermal resources, this study uses quartz and cation geothermometer to estimate the temperatures of the geothermal reservoir and uses the tubular models to evaluate the thermal gradient. The hydrogeochemical characteristics of the geothermal resources were also evaluated by hydrogeochemical analysis. The results showed that the geothermal reservoir temperatures of the four major thermal springs in Changbai Mountain region range from 72 to 169 °C. The average geothermal reservoir temperatures of Jinjiang hot springs, Changbai hot springs I, Xianrenqiao hot springs, and Changbai hot springs II are 129.25, 169, 89, and 73.67 °C, respectively. The geothermal gradient values of the four major thermal springs have different characteristics. The geothermal gradient values of Jinjiang hot springs and Changbai hot springs I are 4.6 and 3.1 °C/100 m, respectively. The geothermal gradient values of Xianrenqiao thermal springs and Changbai thermal springs II are both lower than 1.5 °C/100 m, with the values of 1.1 and 1.4 °C/100 m. And the geothermal gradients are influenced by Changbai Mountain Tianchi volcano. In addition, the water chemical analyses showed that the geothermal water types are HCO3-Na with higher concentrations of Na+, Cl?, SO4 2?, TDS, and HCO3 ? than the non-thermal waters, which suggested a deep and long water cycle of the thermal water, and therefore a sufficient water-rock interaction.  相似文献   

20.
The primary scientific goal of studying salt lakes is to better understand the formation of small continental-type hydrogeochemical systems. Many scientists have attributed the metamorphism of the chemical composition of salt lakes to the evaporative concentration of water. However, the formation of soda water is inconsistent with this hypothesis. Thus, analyzing intrabasinal biochemical processes and water—rocks interactions during the evaporative concentration of water allows us to understand the major mechanisms of the formation and evolution of water compositions. Therefore, the aim of this paper is to identify the key processes involved in the formation of the chemical composition of the water in Lake Doroninskoye. An analysis of the distribution of major components shows that Na+, HCO3 ?, CO3 2?, and Cl? are dominant in this water. High concentrations of these elements are the result of evaporative water concentration. Calcium, magnesium, and potassium are not accumulated because the water is saturated in minerals containing these elements. The main barrier to the growth of the sulfate content of water is sulfate reduction. This process also contributes to the additional reproduction of carbon dioxide, which reacts with the products of the hydrolysis of aluminosilicates OH? to form HCO3 ? and CO3 2?, thus further contributing to the natural processes of soda formation.  相似文献   

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