首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 187 毫秒
1.
A total of 194 groundwater samples were collected from wells in hard rock aquifers of the Medak district, South India, to assess the distribution of fluoride in groundwater and to determine whether this chemical constituent was likely to be causing adverse health effects on groundwater user in the region. The study revealed that the fluoride concentration in groundwater ranged between 0.2 and 7.4 mg/L with an average concentration of 2.7 mg/L. About 57% of groundwater tested has fluoride concentrations more than the maximum permissible limit of 1.5 mg/L. The highest concentrations of fluoride were measured in groundwater in the north-eastern part of the Medak region especially in the Siddipeta, Chinnakodur, Nanganoor and Dubhaka regions. The areas are underlain by granites which contain fluoride-bearing minerals like apatite and biotite. Due to water–rock interactions, the fluoride has become enriched in groundwater due to the weathering and leaching of fluoride-bearing minerals. The pH and bicarbonate concentrations of the groundwater are varied from 6.6 to 8.8 and 18 to 527 mg/L, respectively. High fluoride concentration in the groundwater of the study area is observed when pH and the bicarbonate concentration are high. Data plotted in Gibbs diagram show that all groundwater samples fall under rock weathering dominance group with a trend towards the evaporation dominance category. An assessment of the chemical composition of groundwater reveals that most of the groundwater samples have compositions of Ca2+–Mg2+–Cl? > Ca2+–Na+–HCO3 ? > Ca2+–HCO3 ? > Na+–HCO3 ?. This suggests that the characteristics of the groundwater flow regime, long residence time and the extent of groundwater interaction with rocks are the major factors that influence the concentration of fluoride. It is advised not to utilize the groundwater for drinking purpose in the areas delineated, and they should depend on alternate safe source.  相似文献   

2.
Presence of fluoride in groundwater is a public health problem in the so-called endemic fluorosis belt of the central Iran, where the groundwater is the major source of drinking water in most urban and rural areas. Therefore, an attempt has been made to determine the hydrogeochemical factors controlling fluoride enrichment in the groundwater resources at this belt. Fluoride concentrations ranged from 0.20 to 1.99 mg/L (1.02 ± 0.47) in groundwater samples. The presence of different F-bearing minerals and also clay minerals in the soils and aquifer materials was confirmed using XRD analysis. To identify probable sources of dissolved F? and investigate groundwater quality, multivariate statistical analyses were carried out. Geochemical modeling indicated that all samples were undersaturated with respect to fluorite, halite, gypsum and anhydrite and mostly oversaturated with respect to calcite and dolomite. Contrary to most high-fluoride regions in the World, the high F? content was dominated by Na–Cl- and Ca–SO4-type groundwater in the study area. Besides, fluoride showed negative relationship with pH and HCO3 ? in groundwater. In order to assess the bioavailability of fluoride in soils, a two-step chemical fractionation method was applied. The results showed that fluoride in soils mostly accompanied with the residual and water-soluble fractions and was poorly associated with soil’s bonding sites. Calculated aqueous migration coefficient demonstrated that fluoride in the studied soils was mobile to easily leachable to the groundwater. Finally, the results demonstrated that combination of water–rock interaction and influence of clay minerals is geochemical mechanism responsible for controlling fluoride enrichment in groundwater.  相似文献   

3.
Hydrochemical studies were conducted in Chinnaeru river basin of Nalgonda district, Andhra Pradesh, India, to explore the causes of high fluorides in groundwater and surface water causing a widespread incidence of fluorosis in local population. The concentration of fluoride in groundwater ranges from 0.4 to 2.9 and 0.6 to 3.6 mg/l, stream water ranges from 0.9 to 3.5 and 1.4 to 3.2 mg/l, tank water ranges from 0.4 to 2.8 and 0.9 to 2.3 mg/l, for pre- and post-monsoon periods, respectively. The modified Piper diagram reflects that the water belongs to Ca2+–Mg2+–HCO3 ? to Na+–HCO3 ? facies. Negative chloroalkali indices in both the seasons prove that ion exchange between Na+ and K+ in aquatic solution took place with Ca2+ and Mg2+ of host rock. The interpretation of plots for different major ions and molar ratios suggest that weathering of silicate rocks and water–rock interaction is responsible for major ion chemistry of groundwater/surface water. High fluoride content in groundwater was attributed to continuous water–rock interaction during the process of percolation with fluorite bearing country rocks under arid, low precipitation, and high evaporation conditions. The low calcium content in rocks and soils, and the presence of high levels of sodium bicarbonate are important factors favouring high levels of fluoride in waters. The basement rocks provide abundant mineral sources of fluoride in the form of amphibole, biotite, fluorite, mica and apatite.  相似文献   

4.
Fluoride in drinking water has both beneficial and detrimental effects on public health, and a narrow range between .6 and 1.5 mg/L is optimal for consumption. However, natural groundwater sources exceed these guidelines affecting the entire population. This study aims to assess the distribution and controlling factors of fluoride concentration in the Tamiraparani River basin, South India. A total of 124 groundwater samples were analyzed for their fluoride content and other hydrogeochemical parameters. The fluoride concentration in the study area varied from .01 to 1.67 mg/L, and the highest concentrations were measured in the northern and central parts of the study area, which is underlain by charnockites and hornblende biotite gneiss. The sampling indicated (as per the Bureau of Indian Standards) that 53.9% of the area has fluoride concentrations below levels that are protective of teeth from dental caries (<.6 mg/L). .1% of the area is considered to be at risk of dental fluorosis, and the remaining 46% of the area is considered to have fluoride levels at desirable to permissible limit in groundwater. The groundwater in the study area belongs to Ca–Mg–Cl–SO4 and Ca–Mg–HCO3 types. A positive correlation between fluoride and TDS, Na+, K+ and HCO3 ? indicates its geogenic origin, and positive loading between pH and fluoride shows that alkaline environment enhances the dissolution of fluoride-bearing minerals into the groundwater. An empirical Bayesian kriging model was applied to interpolate the fluoride concentration in the study area. This geostatistical model is found to be better than other kriging methods, and it yielded an average standard error of .332 and root-mean-square standardized value of .986.  相似文献   

5.
The occurrence of dental/skeletal fluorosis among the people in the study area provided the motivation to assess the distribution, severity and impact of fluoride contamination in groundwater of Bankura district at Simlapal block, West Bengal, India. To meet the desired objective, groundwater samples were collected from different locations of Laxmisagar, Machatora and Kusumkanali regions of Simlapal block at different depths of tube wells in both pre- and post-monsoon seasons. Geochemical results reveal that the groundwaters are mostly moderate- to hard-water type. Of total groundwater samples, 37% are situated mainly in relatively higher elevated region containing fluoride above 1.5 mg/L, indicating that host aquifers are severely affected by fluoride contamination. Machatora region is highly affected by fluoride contamination with maximum elevated concentration of 12.2 mg/L. Several symptoms of fluorosis among the different age-groups of people in Laxmisagar and Machatora areas are indicating consumption of fluoridated water for prolonged period. The groundwater samples were mainly Na–Ca–HCO3 type and rock dominance indicating the dissolution of minerals taking place. Ion exchange between OH? ion and F? ion present in fluoride-bearing mineral is the most dominant mechanism of fluoride leaching. High concentration of Na+ and HCO3 ? increases the alkalinity of the water, providing a favorable condition for fluoride to leach into groundwater from its host rocks and minerals.  相似文献   

6.
In this laboratory pilot-scale study, a hybrid treatment system has been developed to remove chlorinated solvent trichloroethylene and fine particles from chlorinated solvent trichloroethylene-contaminated groundwater before it is applied for further recovery. The two-stage system contained fiber-ball filtration followed by nanofiltration membrane processes. The measured chlorinated solvent trichloroethylene and suspended solids of the tested groundwater were 850 μg/L and 1,052 mg/L, respectively. Up to 97.3 % of chlorinated solvent trichloroethylene and 99.9 % of SS could be removed by the hybrid system with an operational pressure of 4.1 kg/cm2. The chlorinated solvent trichloroethylene removal mechanism in the fiber-ball filtration process could be due to adsorption. Approximately 98.2 and 78.6 % of chlorinated solvent trichloroethylene rejection was observed when nanofiltration membrane was used for chlorinated solvent trichloroethylene removal with the recover rate of 80 % and initial chlorinated solvent trichloroethylene concentration of 1 and 10 mg/L. Higher chlorinated solvent trichloroethylene rejection can be obtained when lower chlorinated solvent trichloroethylene concentration (1 mg/L) was applied. High chlorinated solvent trichloroethylene concentration (10 mg/L) would increase the pore size of nanofiltration, which causes the decrease in chlorinated solvent trichloroethylene rejection rate. Approximately 46.6 % of flux drop was observed when nanofiltration membrane was used along compared to the system using FF as the first treatment stage. This indicates that the application of fiber-ball filtration could maintain a higher flux of groundwater treatment. The developed fiber-ball filtration and nanofiltration hybrid membrane system is able to reduce the chlorinated solvent trichloroethylene and solid concentrations to meet the water reuse and groundwater remediation standards.  相似文献   

7.
Fluoride contamination in groundwater resources of Alleppey,southern India   总被引：1，自引：0，他引：1  
Alleppey is one of the thickly populated coastal towns of the Kerala state in southern India.Groundwater is the main source of drinking water for the 240,991 people living in this region.The groundwater is being extracted from a multi-layer aquifer system of unconsolidated to semi-consolidated sedimentary formations,which range in age from Recent to Tertiary.The public water distribution system uses dug and tube wells.Though there were reports on fluoride contamination,this study reports for the first time excess fluoride and excess salinity in the drinking water of the region.The quality parameters,like Electrical Conductivity(EC) ranges from 266 to 3900 μs/cm,the fluoride content ranges from 0.68 to2.88 mg/L,and the chloride ranges between the 5.7 to 1253 mg/L.The main water types are Na-HC03,NaCO_3 and Na-Cl.The aqueous concentrations of F~- and CO_3~(2-) show positive correlation whereas F~- and Ca~(2+) show negative correlation.The source of fluoride in the groundwater could be from dissolution of fluorapatite,which is a common mineral in the Tertiary sediments of the area.Long residence time,sediment-groundwater interaction and facies changes(Ca-HCO_3 to Na-HCO_3) during groundwater flow regime are the major factors responsible for the high fluoride content in the groundwater of the area.High strontium content and high EC in some of the wells indicate saline water intrusion that could be due to the excess pumping from the deeper aquifers of the area.The water quality index computation has revealed that 62%of groundwater belongs to poor quality and is not suitable for domestic purposes as per BIS and WHO standards.Since the groundwater is the only source of drinking water in the area,proper treatment strategies and regulating the groundwater extraction are required as the quality deterioration poses serious threat to human health.  相似文献   

8.
Hydrochemical and environmental isotope methods were used to characterize the groundwater quality in ten wells belonging to the Euphrates alluvial aquifer in Syria, with the aim to assess the origin and dynamic of groundwater salinization in this system. The Euphrates River (ER) water along its entire course in Syria is rather fresh (TDS < 0.5 g/L), and thus, it is suitable for drinking and irrigation purposes. Groundwater salinity progressively increases from north to south, changing from almost freshwater (TDS < 0.6 g/L), with a Ca–Mg and HCO3 type near the Syrian–Turkish border to brackish water (1 < TDS < 3 g/L), with a Ca–Mg or Na–Ca–Mg and SO4–HCO3 type in the vicinity of Al-Raqqa, and hence it can safely be used for irrigation. Downstream Deir-Ezzor the groundwater quality becomes fairly saline to very saline (3 < TDS < 29 g/L), with a Na–Cl type, and therefore it has an absolute hazard (SAR > 5) for irrigation uses. This pattern of chemical evolution, which is also clearly reflected in the variations of groundwater ionic ratios, completely agrees with the thermodynamic simulation results obtained by an experimental evaporation essay of a water sample taken from the ER near Deir-Ezzor. Stable isotopes permit the distinction between three main evaporation processes: under high, intermediate and low humidity conditions. Radioisotopes (3H and 14C) indicate the recent age and renewability of groundwater in this aquifer and confirm that its origin is entirely belonged to the ER water, either by direct bilateral interconnection or by vertical infiltration of the irrigation water totally taken from the ER. Relationships between major ions and δ18O values of the groundwater allow to differentiate between two main enrichment processes: either evaporation only or evaporation plus dissolution, that can explain altogether the development of groundwater salinity in such a dry area.  相似文献   

9.
The present study focuses on the hydrogeochemical composition of groundwater in Chhatarpur area with special focus on nitrate and fluoride contamination, considering the fact that groundwater is the only major source of drinking water here. Carbonate and silicate mineral weathering followed by ground water–surface water interactions, ion exchange and anthropogenic activities are mainly responsible for high concentrations of cations and anions in the groundwater in the region. The average concentration of nitrate and fluoride found in 27 samples is 1.08 and 61.4 mg/L, respectively. Nitrate enrichment mainly occurs in areas occupied with intense fertilizer practice in agricultural fields. Since the area is not dominated by industrialization, the possibility of anthropogenic input of fluoride is almost negligible, thus the enrichment of fluoride in groundwater is only possible due to rock–water interaction. The highly alkaline conditions, which favor the fluorite dissolution, are the main process responsible for high concentration of fluoride.  相似文献   

10.
Elevated fluoride (F) concentration in groundwater is posing a public health risk in the Manas River Basin (MRB), Northwest China. Based on the characterization of regional groundwater flow, 90 groundwater samples from aquifers were analyzed, along with top-soil leachate and pore-water samples from aquitards. Stable oxygen (δ18O) and hydrogen isotopes, radiocarbon and hydrochemical analyses of the groundwater and pore-water samples were conducted to trace groundwater hydrological and hydrochemical processes and thereby understand the distribution and migration mechanism of F. The groundwater is recharged by meteoric precipitation through vapor condensation processes in the Tianshan Mountains. The F concentration in groundwater samples from this basin ranged from 0.11 to 48.15 mg/L (mean 2.56 mg/L). In 37 of the 90 groundwater samples, the F concentrations were above the safe level for drinking water. The F concentrations progressively increased with the residence time and well depths in the northwest of the alluvial-fluvial plain, where groundwater is overexploited for agricultural and domestic use. Positive correlations between F and sodium (Na)/calcium (Ca) indicate that the enrichment and migration of F are influenced by cation exchange processes under high-Na and alkaline pH conditions. The relationships between δ18O and F and chloride (Cl) concentrations were nonlinear due to leaching and mixing processes. This shows that vertical leaching by irrigation return flow and mixing with pore water are the dominant processes driving the migration of F in the groundwater flow system of MRB, in addition to geochemical processes.  相似文献   

11.
  相似文献   

12.
Exposure to arsenic and fluoride through contaminated drinking water can cause serious health effects. In this study, the sources and occurrence of arsenic and fluoride contaminants in groundwater are analyzed in Dawukou area, northwest China, where inhabitants rely on groundwater as the source of drinking water. The triangular fuzzy numbers approach is adopted to assess health risk. The fuzzy risk assessment model incorporates the uncertainties that are caused by data gaps and variability in the degree of exposure to contaminants. The results showed that arsenic and fluoride in groundwater were mainly controlled by the dissolution–precipitation of Ca-arsenate and fluorite under weakly alkaline conditions. The arsenic and fluoride concentrations were higher in the shallow groundwater. The most probable risk values for arsenic and fluoride were 4.57 × 10?4 and 0.4 in the shallow groundwater, and 1.58 × 10?4 and 0.3 in the deep groundwater. Although the risks of fluoride were almost within the acceptable limit (<1.0), the risk values of arsenic were all beyond the acceptable levels of 10?6 for drinking water. Further, the local administration should pay more attention to the potential health risk through dietary intake and to the safety of deep water by ensuring it is not contaminated under prolonged pumping conditions. The fuzzy risk model treats the uncertainties associated with a quantitative approach and provides valuable information for decision makers when uncertainties are explicitly acknowledged, particularly for the variability in contaminants. This study can provide a new insight for solving data uncertainties in risk management.  相似文献   

13.
This study has been carried out in the granitic aquifer of Maheshwaram watershed, Telengana, India. In this study, groundwater sample data of 8 years were analyzed for the fluoride content with other chemical quality parameters. The correlation and factor analysis were employed to understand the mechanisms for fluoride (F) enrichment as well as the hydrochemistry of the area. These analyses addressed that the observed groundwater quality was due to water-rock interaction in the aquifer and fluoride is coming from the dissolution of fluorite and other silicate minerals like biotite and hornblende by the groundwater. Land use/land cover (LULC) study from 2002 to 2008 revealed there were significant positive changes in build-up land and negative changes in vegetation cover after 2003. The main agriculture (paddy) has been reduced to 0.97 km2 in 2008 from 2.39 km2 in 2003. The studied watershed has been characterized on the basis of F concentration into safe, transition, and unsafe groups following the WHO and BIS guidelines. The temporal variation of the three groups showed that 57.6% area of the watershed was in unsafe zone in 2000–2003, but 69.2% of the area became safe in 2006–2009. It has been found that F concentration reduced in 12.59% of the area (became safe from unsafe) accompanied by the reduction of paddy field area. After validation with present (2016) fluoride concentrations, it was found that 16.28% are vulnerable in near future. The results of this study showed that (a) the safe and unsafe zones of fluoride concentrations vary with time with the changes in other parameters associated with it like crop pattern and (b) vulnerable zone can be identified based on the susceptibility to change of safe and unsafe zones. Such studies are useful for planning and management purposes.  相似文献   

14.
Tertiary fractured permeable confined aquifer, which covered about 70 % of the studying area, played an important role in alleviating drinking water shortages. However, about 58 and 79 % of the groundwater samples exceeded the desirable limits for fluoride (1.5 mg/L) and TDS (1,000 mg/L). Two multivariate statistical methods, hierarchical cluster analysis (HCA) and principal components analysis (PCA), were applied to a subgroup of the dataset in terms of their usefulness for groundwater classification, as well as to identify the key processes controlling groundwater geochemistry. In the PCA, two principal factors have been extracted, which could explain 73 % of the total data variability. Among them, factor 1 revealed the source of groundwater salinity and factor 2 explained the elevated fluoride. Two major groups were classified by HCA and Group 1 was near the groundwater recharge zone and Group 2 was mainly distributed over the groundwater discharge zone. Inverse modeling (NETPATH) results indicated that the hydrochemical evolution was primarily controlled by (1) the dissolution of mirabilite, gypsum and halite for the source of groundwater salinity; (2) the release of the adsorbed fluoride through desorption or through competition with HCO3 ? under alkalinity condition for the elevated fluoride in the groundwater.  相似文献   

15.
The groundwater of the deep Ye?ilköy aquifer is the only water resource for agricultural and domestic consumption at the Karpaz Peninsula of Cyprus, which stretches approximately 100 km from the northeast of capital Nicosia to the northern tip of Cyprus. During the last decade, over-pumping and following dry periods have depleted the groundwater resources and the water surface elevation of the aquifer has dropped. The aim of this study is to understand the behavior of the Ye?ilköy aquifer in the last decade for the proper management of groundwater resources. This has been achieved based on well survey and field survey studies, monitoring programs followed by pumping tests, and safe yield analysis. Most of the research effort has been focused on field and well survey studies to quantify agricultural water consumption and abstraction rates from the aquifer. A long-term groundwater level monitoring program, short-term continuous groundwater monitoring and pumping tests provided information for the regression analyses while deriving a sixth order polynomial relationship between the period parameter and the head parameter. The equation was helpful to predict the short-term behavior of the water level when the present hydrogeological conditions prevail. The pumping test results satisfied the hydraulic properties of calcarenite formation yielding T = 1,782 m2/day and S = 0.0012. The results of safe yield analysis show that the annual deficit of the aquifer is 0.496 million cubic meters (MCM), which is equivalent to a 0.6 m drop in groundwater levels per year. Finally, the resultant annual safe yield of the aquifer is estimated as 0.84 MCM.  相似文献   

16.
The groundwater abstracted at a well field near the Yamuna River in Central Delhi, India, has elevated ammonium (NH4 +) concentrations up to 35 mg/L and arsenic (As) concentrations up to 0.146 mg/L, constituting a problem with the provision of safe drinking and irrigation water. Infiltrating sewage-contaminated river water is the primary source of the NH4 + contamination in the aquifer, leading to reducing conditions which probably trigger the release of geogenic As. These conclusions are based on the evaluation of six 8–27-m deep drillings, and 13 surface-water and 69 groundwater samples collected during seven field campaigns (2012–2013). Results indicate that losing stream conditions prevail and the river water infiltrates into the shallow floodplain aquifer (up to 16 m thickness), which consists of a 1–2-m thick layer of calcareous nodules (locally known as kankar) overlain by medium sand. Because of its higher hydraulic conductivity (3.7 × 10?3 m/s, as opposed to 3.5 × 10?4 m/s in the sand), the kankar layer serves as the main pathway for the infiltrating water. However, the NH4 + plume front advances more rapidly in the sand layer because of its significantly lower cation exchange capacity. Elevated As concentrations were only observed within the NH4 + plume indicating a causal connection with the infiltrating reducing river water.  相似文献   

17.
Hydrogeologic framework of the Maku area basalts, northwestern Iran   总被引：1，自引：0，他引：1  
The Maku area in northwestern Iran is characterized by young lava flows which erupted from Mount Ararat in Turkey. These fractured volcanic rocks overlie alluvium associated with pre-existing rivers and form a good basalt-alluvium aquifer over an area of 650 km2. Groundwater discharge occurs from 12 large springs, ranging from 20 to 4,000 L s?1, and from some extraction wells. Permian and Oligo-Miocene age limestones along the northern boundary of the Bazargan and Poldasht Plains basalts are intensively karstified and groundwater from these high lands easily enters the basalt-alluvium aquifers. The transmissivity of the basalt-alluvium aquifer ranges from 24 to 870 m2 d?1, indicating heterogeneity. Groundwater of the aquifer is a sodium-bicarbonate and mixed cation-bicarbonate type and the concentration of fluoride is higher than the universal maximum admissible concentrations for drinking. In order to determine the chemical composition and identify the source of the high fluoride concentrations in the groundwater of the basaltic area, water samples from the springs, wells and rivers were analyzed. The results indicate that the high fluoride water enters the study area from the Sari Su River.  相似文献   

18.
The Cuatrociénegas area is useful for the investigation of the effect of groundwater extraction in the Chihuahuan freshwater xeric ecoregion. It has been investigated at this time using a selection of geochemical indicators (major, minor and trace elements) and δ34S data, to characterize the origin of groundwater, the main geochemical processes and the mineral/groundwater interactions controlling the baseline geochemistry. The area is composed of limestones of Mesozoic age, with a composite thickness of about 500 m, overlaid by basin fill (poorly consolidated young sediments). Substantial water extraction and modification of natural discharges from the area along the last century have produced a detrimental impact on ecosystem structure and function. Water–rock interactions, mixing and evaporative processes dominate the baseline groundwater quality. Natural recharge is HCO3–Ca type in equilibrium with calcite, low salinity (TDS?<?500 mg/L), Cl? lower than 11 mg/L and average Li+ concentration of 0.005 mg/L. Along the groundwater flow systems, δ34S evidence and mass transfer calculations indicate that Cretaceous gypsum dissolution and dedolomitization reactions adjust water composition to the SO4–Ca type. The increase of water–rock interaction is reflected by Cl? values increase (average 68 mg/L), TDS up to about 1500 mg/L and an average Li+ concentration of 0.063 mg/L. Calculations with chemical geothermometers indicate that temperature at depth could be at maximum of 15–20 °C higher than field-measured temperature for pozas. After groundwater is discharged to the surface, chemical evolution continues; water evaporation, CO2 degassing and precipitation of minerals such as gypsum, calcite and kaolinite represent the final processes and reactions controlling water chemical composition.  相似文献   

19.
Incidence of high fluoride (F?) in groundwater (>1.5 mg/L) in two tribal belts of eastern India, one around Chukru in the Palamau district of Jharkhand and the other around Karlakot in the Nuapada district of Odisha, has been studied. The maximum concentration of F? in groundwater from dug wells and tube wells is 10.30 mg/L in Chukru and 4.62 mg/L in Karlakot. The groundwaters are mildly alkaline with pH ranges of 7.52–8.22 and 7.33–8.20 in Chukru and Karlakot, respectively. The F? concentration is positively correlated with pH, electrical conductivity and SO4 2? in both areas. The high F? in groundwater resulted mainly from dissolution of biotite and fluorapatite in quartzofeldspathic gneiss. The ionic dominance pattern (in meq/L) is mostly in the order Ca2+ > Na+ > Mg2+ > K+ among cations and HCO3 ? > SO4 2? > < Cl? > F? among anions in the Karlakot groundwater. Preliminary adsorption experiments were conducted on natural haematite iron ore and synthetic magnetite to evaluate their potential for F? removal from water. Effects of different parameters such as contact time, pH, adsorbent dose and initial F? concentration on the adsorption capacity of these materials were investigated. Strong dependence of F? removal on pH was observed for both the adsorbents. With natural haematite iron ore, the maximum F? removal of 66 % occurred at an initial pH of 3.2 for a solution with F? concentration of 3 mg/L, adsorbent dose of 7 g/L and overnight contact time. The haematite iron ore was observed to increase the pH of the F? solution. Adsorption equilibrium was not achieved with this adsorbent even after a contact time of 45.2 h. In the case of synthetic magnetite, 84 % F? removal was achieved after 2 min of contact time for a solution with F? concentration of 6 mg/L, adsorbent dose of 10 g/L and initial pH of 7. The results indicate high potential of both natural haematite iron ore and synthetic magnetite as adsorbents of F? in water.  相似文献   

20.
The physicochemical properties and major ion chemistry of the groundwater sources from alluvial aquifers along the stretch (60 km) of Jhelum River in Kashmir Himalaya were determined in order to identify hydro-geochemical processes and their suitability for drinking purposes. The data depicted that calcium and bicarbonates were dominating among the cations and anions. The results indicate the trend of cation dominance as Ca2+ > Na+ > Mg2+ > K+, whereas anion dominance was in the order of HCO3 ? > Cl? > SO4 2?. Ratio of calcium to magnesium indicated the dissolution of Ca2+ from CaCO3, which results in an increased levels of Ca2+ in the groundwater. Interpretation of Piper Trilinear plot understands the various geochemical processes affecting the groundwater quality and shows groundwater was dominated by Ca–HCO3 type. The pH was recorded in the slightly alkalinity range 7.2–7.8 and was showing positive correlation with HCO3 ?. The chloro-alkaline indices revealed 86% of the sources exchange by a type of base-exchange reactions, rest by cation–anion exchange. Gibbs diagram revealed groundwater sources fall in the category of rock dominance. The concentration of the nitrogen compounds was in the progression of NO3–N > NH4–N > NO2–N, and the PO4 ? fluctuated from 0.12 to 0.22 mg/L. Moreover, corrosivity ratio indicated that water from the majority of sources (71%) is safe to supply using pipes without any corrosive effects, while 29% of sources are corrosive in nature and need non-corrosive pipes for transporting and lifting of groundwater. The results revealed, groundwater samples were within permissible limits as prescribed by International and National standards, for drinking purposes. The State government and NGO’s can show their interest in utilizing such water resources to overcome the shortage of drinking water in a sustainable way for the daily consumption of the people living in the vicinity of Jhelum River.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号