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1.
Present study is an effort to distinguish between the contributions of natural weathering and anthropogenic inputs towards high salinity and nutrient concentrations in the groundwater of National Capital Territory (NCT) Delhi, India. Apart from the source identification, the aquifer of entire territory has been characterized and mapped on the basis of salinity in space and water suitability with its depth. Major element chemistry, conventional graphical plots and specific ionic ratio of Na+/Cl−, SO4 2−/Cl−, Mg2+/Ca2+ and Ca2+/(HCO3 − + SO4 2−) are conjointly used to distinguish different salinization sources. Results suggest that leaching from the various unlined landfill sites and drains is the prime cause of NO3 − contamination while study area is highly affected with inland salinity which is geogenic in origin. The seasonal water level fluctuation and rising water level increases nutrients concentration in groundwater. Mixing with old saline sub-surface groundwater and dissolution of surface salts in the salt affected soil areas were identified as the principle processes controlling groundwater salinity through comparison of ionic ratio. Only minor increase of salinity is the result of evaporation effect and pollution inflows. The entire territory has characterized into four groups as fresh, freshening, near freshening and saline with respect to salinity in groundwater. The salinity mapping suggests that in general, for drinking needs, groundwater in the fresh, freshening and near freshening zone is suitable up to a depth of 45, 20 and 12 m, respectively, while the saline zones are unsuitable for any domestic use. In the consideration of increasing demand of drinking water in the area; present study is vital and recommends further isotopic investigations and highlights the need of immediate management action for landfill sites and unlined drains.  相似文献   

2.
In this study, 92 groundwater samples were collected from the Attica region (Greece). Moreover, geographical information system database, geochemistry of groundwater samples and statistics were applied. These were used for studying the chemical parameters (NO3 −, Mg2+, Ca2+, Cl−, and Na+) and conductivity spatial distribution and for assessing their environmental impact. The ranges of chemical parameters of the water samples (in mg L−1) are: NO3 − 1–306, Mg2+ 2–293, Ca2+ 3–453, Cl− 5–1,988, and Na+ 4–475. The elevated concentrations of sodium, Mg2+, Cl− are attributed to natural contamination (seawater intrusion). On the other hand, NO3 − elevated concentrations are attributed to anthropogenic contamination (nitrate fertilizers). The results of the GIS analysis showed that elevated values of Na+, Mg2+, Cl− are related to shrubby and sparsely vegetated areas, while elevated values of NO3 − are connected with urban and agricultural areas.  相似文献   

3.
A water quality investigation was carried out in the Deoria district, Ganga plain, to assess the suitability of surface and groundwaters for domestic, agricultural, and industrial purposes. As much as 50 representative samples from river and groundwater were collected from various stations to monitor the water chemistry of various ions, comprising Ca2+, Mg2+, Na+, K+, HCO3 −, SO4 2−, NO3 −, Cl−, F−, and trace metals, such as Fe, Cu, Mn, Zn, Cd, and Pb. The results showed that electrical conductance (EC), total dissolved solids (TDS), HCO3 −, Mg2+, Na+, and total hardness (TH) are above the maximum desirable limit, and apart from Fe and Mn all other trace metals are within the maximum permissible limit for drinking water. The calculated values for sodium absorption ratio (SAR), salinity, residual sodium carbonate (RSC), and permeability index (PI) indicate well to permissible use of water for irrigation. High values of Na%, RSC, and Mg-hazard (MH) at some stations restrict its use for agricultural purpose. Anthropogenic activities affect the spatial variation of water quality. Economic and social developments of the study area is closely associated with the characteristics of the hydrological network.  相似文献   

4.
Displacement studies on leaching of potassium (K+) were conducted under unsaturated steady state flow conditions in nine undisturbed soil columns (15.5 cm in diameter and 25 cm long). Pulses of K+ applied to columns of undisturbed soil were leached with distilled water or calcium chloride (CaCl2) at a rate of 18 mm h−1. The movement of K+ in gypsum treated soil leached with distilled water was at a similar rate to that of the untreated soil leached with 15 mM CaCl2. The Ca2+ concentrations in the leachates were about 15 mM, the expected values for the dissolution of the gypsum. When applied K+ was displaced with the distilled water, K+ was retained in the top 10–12.5 cm depth of soil. In the undisturbed soil cores there is possibility of preferential flow and lack of K+ sorption. The application of gypsum and CaCl2 in the reclamation of sodic soils would be expected to leach K+ from soils. It can also be concluded that the use of sources of water for irrigation which have a high Ca2+ concentration can also lead to leaching of K+ from soil. Average effluent concentration of K+ during leaching period was 30.2 and 28.6 mg l−1 for the gypsum and CaCl2 treated soils, respectively. These concentrations are greater than the recommended guideline of the World Health Organisation (12 mg K+ l−1).  相似文献   

5.
Understanding and deciphering processes proceeding near the surface are among the urgent tasks of contemporary mineralogy and geochemistry, which are especially important for resolving ecological challenges and developing principles of rational environmental management. The paper presents systematized data published on thermodynamics of minerals (arsenates, sulfates, selenites, and selenates), which are formed in the weathering zone of sulfide ores, and determines approaches to quantitative physicochemical modeling of their formation conditions. Diagrams of phase and chemical equilibria (Eh-pH, diagrams of solubility) of the subsystems of the model system Fe-Cu-Zn-Pb-Co-Ni-As-Se-S-H2O (Fe2+, Fe3+, Cu2+, Zn2+, Pb2+, Ni2+, Co2+, H+//SeO32−, SeO42−, AsO43−, SO42−, OH−-H2O) are used as a thermodynamic basis for modeling mineral-forming processes in the weathering zone of ore deposits. Seventy-two arsenates, about 70 sulfates, and 7 selenites and selenates have been identified in the framework of this system. The available published values of standard thermodynamic functions of the formation of minerals and chemical compounds are given, as well as the Pitzer equation parameters to describe the sulfate systems, which are substantially specific due to the high solubility of their components.  相似文献   

6.
Hydrochemical investigations were carried out in Damagh area, Hamadan, western Iran, to assess chemical composition of groundwater. Forty representative groundwater samples were collected from different wells to monitor the water chemistry of various ions. Chemical analysis of the groundwater showed that the mean concentration of the cations is in the order Na+ > Ca2+ > Mg2+ > K+, while that for anions was HCO3− > Cl− > SO42 − > NO3−. All of the investigated groundwaters present two different chemical facies (Ca–HCO3 and Na–HCO3) which is in relation with their interaction with the geological formations of the basin, cation exchange between groundwater and clay minerals and anthropogenic activities. The principal component analysis (PCA) performed on groundwater identified three principal components controlling their variability in groundwater. Electrical conductivity, Mg2+, Na+, SO42−, and Cl− content were associated in the same component (PC1) (salinity), determined principally by anthropogenic activities. The pH, CO32 −, HCO3−, and Ca2+ (PC2) content were related to the geogenic factor. Finally, the NO3−, Cl− and K+ (PC3) were controlled by anthropogenic activity as a consequence of inorganic fertilizers.  相似文献   

7.
About 24 samples from hand-dug wells and boreholes were used to characterize concentrations of the main inorganic ions in a laterite environment under semi-arid climatic conditions in Tikaré, northern Burkina Faso. It was found that the most represented groundwater anion in groundwater was HCO3 − with average levels of 49.1 mg/L in the dry season and 33.5 mg/L in the rainy season. The most represented cation was Ca2+ with mean concentrations of 13.7 and 9.5 mg/L, respectively. The main processes, which influence the concentrations of these ions, are evaporation (dry season), local enrichment of recharge water in some elements, ion exchange and fixation by clay minerals (in case of K+). The best correlations were found between Ca2+ and Mg2+ (r = 0.95), Cl− and Na+ (r = 0.95), HCO3 − and Mg2+ (r = 0.89), HCO3 − and Ca2+ (r = 0.89), and between HCO3 − and Na+ (r = 0.80). In general, the quality of the groundwater from the different wells sampled for this study was good enough to serve as drinking water. However, there were situations where the quality of water was polluted because of anthropogenic contaminants (mainly NO3 −, K+, Cl−) from septic tanks and manure pits located in the vicinity of some sampled wells. In addition, application of fertilizers also represents a potential anthropogenic contamination source with regard to SO4 2−, Ca2+, K+, Na+, and Mg2+. Considering the high concentrations of SO4 2−, Mg2+, Na+ and Ca2+ found in one borehole, the deeper, fractured aquifers were also likely to be enriched in these elements. In contrast, the shallow aquifers are likely to be contaminated with Cl−, NO3 − and K+. Cl− and K+ seem to be locally present in recharge water as shown by their relative higher mean concentrations in the rainy season samples.  相似文献   

8.
Pollution of groundwater by seawater intrusion poses a threat to sustainable agriculture in the coastal areas of Korea. Therefore, seawater intrusion monitoring stations were installed in eastern, western, and southern coastal areas and have been operated since 1998. In this study, groundwater chemistry data obtained from the seawater intrusion monitoring stations during the period from 2007 to 2009 were analyzed and evaluated. Groundwater was classified into fresh (<1,500 μS/cm), brackish (1,500–3,000 μS/cm), and saline (>3,000 μS/cm) according to EC levels. Among groundwater samples (n = 233), 56, 7, and 37% were classified as the fresh, brackish, and saline, respectively. The major dissolved components of the brackish and saline groundwaters were enriched compared with those of the fresh groundwater. The enrichment of Na+ and Cl− was especially noticeable due to seawater intrusion. Thus, the brackish and saline groundwaters were classified as Ca–Cl and Na–Cl types, while the fresh groundwater was classified as Na–HCO3 and Ca–HCO3 types. The groundwater included in the Na–Cl types indicated the effects of seawater mixing. Ca2+, Mg2+, Na+, K+, SO4 2−, and Br− showed good correlations with Cl− of over r = 0.624. Of these components, the strong correlations of Mg2+, SO4 2−, and Br− with Cl− (r ≥ 0.823) indicated a distinct mixing between fresh groundwater and seawater. The Ca/Cl and HCO3/Cl ratios of the groundwaters gradually decreased and approached those of seawater. The Mg/Cl, Na/Cl, K/Cl, SO4/Cl, and Br/Cl ratios of the groundwaters gradually decreased, and were similar to or lower than those of seawater, indicating that Mg2+, Na+, K+, SO4 2−, and Br−, as well as Cl− in the saline groundwater can be enriched by seawater mixing, while Ca2+ and HCO3 − are mainly released by weathering processes. The influence of seawater intrusion was evaluated using threshold values of Cl− and Br−, which were estimated as 80.5 and 0.54 mg/L, respectively. According to these criteria, 41–50% of the groundwaters were affected by seawater mixing.  相似文献   

9.
This study was carried out to analyze groundwater quality in selected villages of Nalbari district, Assam, India, where groundwater is the main source of drinking water. 40 groundwater samples collected from hand pumps and analyzed for pH, EC, TDS, Ca2+, Mg2+, Na+, K+, HCO3 −, SO4 2−, Cl− and F−. Chemical analysis of the groundwater showed that mean concentration of cations in (mg/L) is in the order Ca2+ > Mg2+ > Na+ > K+ while for anions it is HCO3 − > Cl− > SO4 2− > F−. Fluoride concentration was recorded in the range of 0.02–1.56 mg/L. As per the desirable and maximum permissible limits for fluoride in drinking water recommended by WHO and by Bureau of Indian Standards (BIS), which is 1.5 mg/L, the groundwater of about 97% of the samples were found to be suitable for drinking purpose. The suitability of the groundwater for irrigation purpose was investigated by some determining factors such as sodium adsorption ratio, soluble sodium percentage, Kelly’s ratio and electrical conductivity. The value of the sodium absorption ratio and electrical conductivity of the groundwater samples were plotted in the US Salinity laboratory diagram for irrigation water. Most of the groundwater samples fall in the field of C2S1 and C3S1 indicating medium to high salinity and low sodium water, which can be used for irrigation on almost all types of soil with little doubt of exchangeable sodium. The hydrochemical facies shows that the groundwater is Ca-HCO3 type.  相似文献   

10.
2 study area was assessed with respect to its heavy-metal load on the basis of the current guideline values. The heavy-metal loads of the soils in the study area have ranges of <0.2–200 mg kg−1 for Cd, <10–30,000 mg kg−1 for Pb, 7–10,000 mg kg−1 for Cu and 50–55,000 mg kg−1 for Zn. Mobility of the heavy metals was determined by extraction at different pH values. The acid neutralisation capacity (ANCx) at these pH values was also determined to estimate the probability that the pH can drop to pH=x. The ANC values in the study area ranged from 6 to 3000 mmol H+ kg−1, from −33 to 800 mmol H+ kg−1 and from −74 to 160 mmol H+ kg−1 for ANC3.5, ANC5.0 and ANC6.2, respectively. Together with pedological data, the extraction experiments permit differentiation between soil units that have been placed in the same environmental hazard class on the basis of total heavy-metal loads. Received: 10 August 1998 · Accepted: 14 August 1999  相似文献   

11.
Samples were collected from two snowpits in Baishui glacier no. 1, Mt Yulong, China, in May 2006. Snowpit chemistry was studied, using ion tracer techniques, HYSPLIT model, factor analysis, correlation and trend analysis. It indicated that total cation concentration is higher in 4,900-m snowpit than in 4,750-m snowpit, whereas total anion concentration is higher in 4,750-m snowpit. Cations, especially Ca2+, dominate ionic concentrations in Baishui glacier no. 1. According to correlation analysis and factor analysis, ions can be categorized as follows: Cl− and NO3 − as Group 1, SO4 2− as Group 2, Mg2+ and Ca2+ as Group 3, Na+ as Group 4, K+ as Group 5. Contribution made by terrestrial dust to ionic concentration accounts for 52.27, 100, 99.36, 98.91, 96.16 and 99.97% of Cl−, NO3 −, SO4 2−, K+, Mg2+ and Ca2+, respectively, in 4,900-m snowpit, and for 64.00, 100, 99.57, 98.63, 96.25 and 99.97% in 4,750-m snowpit. Local dust is the principal source of snowpit chemical components. Pollutants brought from industrial areas of South Asia, Southeast Asia and South China by monsoonal circulation also makes some contribution to anion concentrations, but pollution associated with human activities makes a very slight contribution in study area. The chemical characteristics of two snowpits are different owing to the difference of deposition mechanism and local environment in different altitudes.  相似文献   

12.
Fluid chemistry and processes at the Porgera gold deposit, Papua New Guinea   总被引：4，自引：0，他引：4  
The Porgera gold deposit in Papua New Guinea is a world-class example of an alkalic-type epithermal gold system (stage II), which overprints a precursor stage of magmatic-hydrothermal gold mineralization (stage I). Gas and ion chromatographic analyses of fluid inclusions contained in vein minerals from both mineralization stages have been carried out in order to constrain the compositions of the fluids involved in, and the processes attending, ore deposition. These data indicate the presence of three end-member liquids, the most dilute of which was present throughout the mineralization history and is interpreted to represent evolved groundwater of meteoric origin. Its composition is estimated to have been approximately 500 mM Na+, 10 mM K+, 5 mM Li+, 250 mM Cl−, 0.15 mM Br−, and 0.01 mM I−, plus significant concentrations of dissolved gases. More saline liquids were also present during the two main stages of ore formation, and although their compositions differ, both are interpreted to have been derived at least in part from magmatic fluids, and to have been the media by which gold was introduced into the system. Stage I minerals contain fluid inclusions which decrease in salinity towards this dilute end-member composition through the vein paragenesis, reflecting progressive dilution at depth of the magmatic fluid source by groundwaters. Ore deposition is thought to have been caused largely by simple cooling and/or wallrock reactions, although limited in situ fluid mixing may also have occurred. The most saline fluids, present in early quartz and pyrite, contain at least 810 mM Na+, 530 mM Ca2+, 130 mM K+, 12 mM Li+, 87 mM SO4 2−, 960 mM Cl−, 1.1 mM Br−, and 0.05 mM I−, plus significant but variable concentrations of dissolved gases. Fluid inclusions from stage II hydraulic breccia veins reveal the presence of two distinct liquids with contrasting salinities, which were present at different times during vein formation. A higher salinity liquid appears to have predominated during mineralization, whereas lower salinity groundwaters filled the structures during intervening periods. The ore-forming fluid may have been forcibly injected into the veins from depth during fracturing and depressurization events, displacing the resident groundwaters in the process. The original composition of this fluid is estimated to have been at least 1770 mM Na+, 59 mM K+, 180 mM Li+, 210 mM SO4 2−, 680 mM Cl−, 1.4 mM Br−, and 0.09 mM I−, plus 1.5 mol% CO2, 0.19 mol% CH4, and 0.04 mol% N2. Gas chromatographic analyses of fluid inclusions from stage II samples show a decrease in total gas content between early unmineralized veins and post-mineralization vuggy quartz (suitable samples could not be obtained from the ore stage itself). Post-mineralization samples plot along an experimental gas-saturation curve in the CO2-CH4-H2O-NaCl system, obtained at conditions similar to those attending stage II ore deposition at Porgera (200–300 bar, ˜165 °C). These results are interpreted to indicate a period of depressurization-induced phase separation during hydraulic fracturing, which resulted in rich ore deposition. Volatile gases such as CH4 and N2, in addition to CO2 in solution, are shown to have a significant negative effect on total gas solubility. This effect may be of critical importance in lowering the temperature and increasing the depth (pressure) at which phase separation can occur in epithermal systems. Received: 28 November 1995 / Accepted: 17 July 1996  相似文献   

13.
Geochemical processes that take place in the aquifer have played a major role in spatial and temporal variations of groundwater quality. This study was carried out with an objective of identifying the hydrogeochemical processes that controls the groundwater quality in a weathered hard rock aquifer in a part of Nalgonda district, Andhra Pradesh, India. Groundwater samples were collected from 45 wells once every 2 months from March 2008 to September 2009. Chemical parameters of groundwater such as groundwater level, EC and pH were measured insitu. The major ion concentrations such as Ca2+, Mg2+, Na+, K+, Cl−, and SO4 2− were analyzed using ion chromatograph. CO3 − and HCO3 − concentration was determined by acid–base titration. The abundance of major cation concentration in groundwater is as Na+ > Ca2+ > Mg2+ > K+ while that of anions is HCO3 − > SO4 2− > Cl− > CO3 −. Ca–HCO3, Na–Cl, Ca–Na–HCO3 and Ca–Mg–Cl are the dominant groundwater types in this area. Relation between temporal variation in groundwater level and saturation index of minerals reveals the evaporation process. The ion-exchange process controls the concentration of ions such as calcium, magnesium and sodium. The ionic ratio of Ca/Mg explains the contribution of calcite and dolomite to groundwater. In general, the geochemical processes and temporal variation of groundwater in this area are influenced by evaporation processes, ion exchange and dissolution of minerals.  相似文献   

14.
Two kinds of mylonite series rocks, felsic and mafic, have been recognized in the NW-striking shear zone of the Jiapigou gold belt. During ductile deformation, a large amount of fluid interacted intensively with the mylonite series rocks: plagioclases were sericitized and theAn values declined rapidly, finally all of them were transformed to albites; dark minerals were gradually replaced by chlorites (mostly ripidolite). Meanwhile, large-scale and extensive carbonation also took place, and the carbonatization minerals varied from calcite to dolomite and ankerite with the development of deformation. The δ13C values of the carbonates are −3.0‰ – −5.6‰ suggesting a deep source of carbon. The ductile deformation is nearly an iso-volume one (f v≈1). With the enhancement of shear deformation, SiO2 in the two mylonite series rocks was depleted, while volatile components suchs as CO2 and H2O, and some ore-forming elements such as Au and S were obviously enriched. But it is noted that the enrichment of Au in both the mylonite series rocks did not reach the paygrade of gold. The released SiO2 from water-rock interactions occurred in the form of colloids and absorbed gold in the fluid. When brittle structures were formed locally in the ductile shear zone, the ore-forming fluids migrated to the structures along microfractures, and preciptated auriferous quartz because of reduction of pressure and temperature. Fluid inclusion study shows that the temperature and pressure of the ore-forming fluids are 245–292°C and 95.4–131.7 MPa respectively; the salinity is 12.88–16.33wt% NaCl; the fluid-phase is rich in Ca2+, K+, Na+, Mg2+, F− and Cl−, while the gaseous phases are rich in CO2 and CH4. The δD and δ18O, values of the ore-forming fluid are −84.48‰ – −91.73‰ and −0.247‰ – +2.715‰ respectively, suggesting that the fluid is composed predominantly of meteoric water. This project is financially supported by the National Natural Science Foundation of China (No. 9488010).  相似文献   

15.
Hydrogeochemical investigations are carried out in the different blocks of Burdwan district, West Bengal, India in order to assess its suitability for drinking as well as irrigation water purpose. Altogether 49 representative groundwater samples are collected from bore wells and the water chemistry of various ions viz. Ca2+, Mg2+, Na+, K+, CO32−, HCO3−, Cl−, SO42− and NO3− are carried out. The chemical relationships in Piper and Gibbs diagram suggest that the groundwater mainly belongs to alkali type and Cl− group and are controlled by rock dominance. A comparison of groundwater quality in relation to drinking water quality standards proves that most of the water samples are suitable for drinking water purpose whereas groundwater in some areas of the district has high salinity and high sodium adsorption ratio (SAR), indicating unsuitability for irrigation water and needs adequate drainage.  相似文献   

16.
Deposition, leaching and chemical transformation are processes that affect roofing tile and roof runoff water. Leaching experiments, with artificial rainwater in the laboratory, showed the presence of Na+, K+, Mg2+, Ca2+, Cl−, NO3 −, SO4 2−, with a ratio of Ca2+ and SO4 2− suggesting gypsum dissolution. X-ray fluorescence (XRF) of the exposed roof tile showed depletion such as Mg, Al, Si, P, Ti and K at the surface of the tile and an enrichment of Fe and Mn which hinted at a process akin to laterite formation. However, calcium appeared to be enriched at the surface as gypsum (confirmed by X-ray diffraction) and to a lesser extent calcite, which is characteristic of deposits on building surfaces in cities.  相似文献   

17.
This study was conducted to evaluate factors regulating groundwater quality in an area with agriculture as main use. Thirty groundwater samples have been collected from Razan area (Hamadan, Iran) for hydrochemical investigations to understand the sources of dissolved ions and assess the chemical quality of the groundwater. The chemical compositions of the groundwater are dominated by Na+, Ca2+, HCO3 −, Cl− and SO4 2−, which have been derived largely from natural chemical weathering of carbonate, gypsum and anthropogenic activities of fertilizer’s source. The production of SO4 2− has multiple origins, mainly from dissolution of sulphate minerals, oxidation of sulphide minerals and anthropogenic sources. The major anthropogenic components in the groundwater include Na+, Cl−, SO4 2− and NO3 −, with Cl− and NO3 − being the main contributors to groundwater pollution in Razan area.  相似文献   

18.
The hydrolysis of the Pd2+ ion in HClO4 solutions was examined at 25–70°C, and the thermodynamic constants of equilibrium K (1)0 and K (2)0were determined for the reactions Pd2+ + H2O = PdOH+ + H+ and Pd2+ + 2H2O = Pd(OH)20 + 2H+, respectively. The values of log K (1)0 = −1.66 ± 0.5 (25°C) and −0.65 ± 0.25 (50°C) and log K (2)0 = −4.34 ± 0.3 (25°C) and −3.80 ± 0.3 (50°C) were derived using the solubility technique at 0.95 confidence level. The values of log K (1)0 = −1.9 ± 0.6 (25°C), −1.0 ± 0.4 (50°C), and −0.5 ± 0.3 (70°C) were obtained by spectrophotometric techniques. The palladium ion is significantly hydrolyzed at elevated temperatures (50–70°C) even in strongly acidic solutions (pH 1–1.5), and its hydrolysis is enhanced with increasing temperature.  相似文献   

19.
A long mining history and unscientific exploitation of Jharia coalfield caused many environmental problems including water resource depletion and contamination. A geochemical study of mine water in the Jharia coalfield has been undertaken to assess its quality and suitability for domestic, industrial and irrigation uses. For this purpose, 92 mine water samples collected from different mining areas of Jharia coalfield were analysed for pH, electrical conductivity (EC), major cations (Ca2+, Mg2+, Na+, K+), anions (F−, Cl−, HCO3 −, SO4 2−, NO3 −), dissolved silica (H4SiO4) and trace metals. The pH of the analysed mine water samples varied from 6.2 to 8.6, indicating mildly acidic to alkaline nature. Concentration of TDS varied from 437 to 1,593 mg L−1 and spatial differences in TDS values reflect the variation in lithology, surface activities and hydrological regime prevailing in the region. SO4 2− and HCO3 − are dominant in the anion and Mg2+ and Ca2+ in the cation chemistry of mine water. High concentrations of SO4 2− in the mine water of the area are attributed to the oxidative weathering of pyrites. Ca–Mg–SO4 and Ca–Mg–HCO3 are the dominant hydrochemical facies. The drinking water quality assessment indicates that number of mine water samples have high TDS, total hardness and SO4 2− concentrations and needs treatment before its utilization. Concentrations of some trace metals (Fe, Mn, Ni, Pb) were also found to be above the desirable levels recommended for drinking water. The mine water is good to permissible quality and suitable for irrigation in most cases. However, higher salinity, residual sodium carbonate and Mg-ratio restrict its suitability for irrigation at some sites.  相似文献   

20.
Water wells were sampled near North Madison, Ohio, following a gas well blow out that injected large amounts of CH4 into near-surface groundwater Chemical analyses showed elevated levels of Fe+2, Mn+2, Ca+2, sulfide, alkalinity, and pH, and low levels of dissolved oxygen, SO4 −2, and NO3 − in CH4-affected wells compared to unaffected wells. Sulfate reduction is quantitatively the most important vehicle for CH4 oxidation Equilibrium thermodynamic computer models were used to simulate groundwaters from the North Madison area Model results showed that CH4 is oxidized to HCO3 −, SO4 −2 is reduced, iron and manganese oxides are reduced and dissolved, and pH increases These simulations are in excellent agreement with trends observed in the field data A laboratory experiment was designed to simulate CH4 − perturbed groundwater in the methane-perturbed system, sulfide increased significantly, providing direct evidence for methane oxidation by sulfate reduction Although suitable anaerobic methane-oxidizing bacteria have not been isolated from groundwater aquifers, the combination of field data, laboratory experiment, and computer simulation form a convincing argument that CH4 perturbation of aquifers can and does affect groundwater chemistry  相似文献   

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