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1.
Abdelrahman M. Abdelgawad Kunio Watanabe Shinji Takeuchi Takashi Mizuno 《Engineering Geology》2009,108(1-2):76-85
The aim of this paper was to explore new factors that might be reasons for the occurrence of fluoride-rich groundwater in the area around a construction site. During the construction of two deep shafts of the Mizunami Underground Research Laboratory (MIU) in Mizunami city, central Japan, a large quantity of groundwater with high fluoride concentration was charged into the shafts. Chemical investigation carried out during the excavation revealed that fluoride concentrations in the area around the MIU site greatly exceeded those prescribed by Japanese standards. Therefore, the origin of fluoride ion was experimentally investigated. Samples were collected from the core of a deep borehole drilled in the study area. The weathering - and alteration levels of the collected granites varied greatly. Granitic powders were used to measure fluoride content in the granitic rock mass. The fluoride content ranged between 200 and 1300 mg/kg. The powders were reacted with purified water for 80 days. The results of water–rock interaction showed granitic rock to be one of the main sources of fluoride-rich groundwater in Mizunami area. Fluoride concentrations in these solutions that were shaken for 80 days varied between 2 and 7 mg/l. This change may have occurred as a result of the spatial distribution of fluoride ions in the granite mass as evidenced by mineralogical analysis of fluoride content in several specimens. X-ray powder diffraction analysis of the rock before- and after the water–rock interaction tests manifested that the presence of fluorite mineral was relatively small compared to other minerals. The degree of weathering and alteration might be an additional factor causing dissolution of fluoride-rich minerals. However, it was difficult to interpret the change in fluorite composition by X-ray diffraction analysis. 相似文献
2.
Geochemical characteristics of fluoride in groundwater of Gimcheon, Korea: lithogenic and agricultural origins 总被引:1,自引:1,他引:0
The occurrence of fluoride in groundwaters can be influenced by many factors. In Korea, the fluoride-rich groundwaters are
normally associated with rock types, especially granite and gneiss. In Gimcheon, high-fluoride groundwaters (up to a maximum
of 2.15 mg/L) were observed with bimodal distribution of concentrations. The groundwater in this area showed relatively high
concentrations of anthropogenic chemicals such as nitrate, chloride, and sulfate. Statistical analysis showed that fluoride
is positively correlated with pH, alkalinity, sodium, and lithium, indicating that the interaction with granite is the main
cause enriching its concentration. In Gimcheon, δ18O data of groundwater showed a negative correlation with nitrate and can be used as an indicator of groundwater age. The four
samples of fluoride-rich groundwater were plotted in the light δD and δ18O region, showing that they were the result of long water–rock reaction. However, other groundwater with a low-fluoride concentration
was evenly distributed throughout all δD and δ18O ranges and did not show a statistically significant correlation with nitrate, indicating possible mixing with another source
of fluoride. Considering the influence from the surface on the geochemical characteristics of groundwater in this area, anthropogenic
sources including phosphate fertilizer containing fluoride and pesticides may also have partly contributed to the concentrations
of fluoride in the low-fluoride groundwater. The scattered distribution of fluoride-rich groundwater and the significant correlation
with lithium suggest that pegmatite is the main rock type increasing fluoride concentration in this area. 相似文献
3.
Geochemistry of fluoride rich groundwater in Kolar and Tumkur Districts of Karnataka 总被引:2,自引:2,他引:0
Groundwater is a significant water resource in India for domestic, irrigation, and industrial needs. By far the most serious
natural groundwater-quality problem in India, in terms of public health, derives from high fluoride, arsenic, and iron concentrations.
Hydrogeochemical investigation of fluoride contaminated groundwater samples from Kolar and Tumkur Districts in Karnataka are
undertaken to understand the quality and potability of groundwater from the study area, the level of fluoride contamination,
the origin and geochemical mechanisms driving the fluoride enrichment. Majority of the groundwater samples did not meet the
potable water criteria as they contained excess (>1.5 mg/L) fluoride, dissolved salts (>500 mg/L) and total hardness (75–924 mg/L).
Hydrogeochemical facies of the groundwater samples suggest that rock weathering and evaporation–crystallization control the
groundwater composition in the study area with 50–67% of samples belonging to the Ca–HCO3 type and the remaining falling into the mixed Ca–Na–HCO3 or Ca–Mg–Cl type. The saturation index values indicated that the groundwater in the study area is oversaturated with respect
to calcite and under-saturated with respect to fluorite. The deficiency of calcium ion concentration in the groundwater from
calcite precipitation favors fluorite dissolution leading to excess fluoride concentration. 相似文献
4.
L. Valenzuela-Vásquez J. Ramírez-Hernández J. Reyes-López A. Sol-Uribe O. Lázaro-Mancilla 《Environmental Geology》2006,51(1):17-27
Anomalous high fluoride concentration up to 7.59 mg/dm3 is found in groundwater from “La Victoria” area. This water is used to supply drinking water to Hermosillo City, Sonora. Geochemistry of groundwater, relationship between physicochemical parameters, hydrogeology and geologic setting were correlated to define the origin and the geochemical mechanisms of groundwater fluorine enrichment. High fluoride concentration is associated with high bicarbonates, pH and temperature, and it decreases toward the west and south of the area. Fluoride is in negative correlation to calcium concentration. Sodium sulphate facies of regional deep water flow are related to high fluoride concentration. High electric resistivity rocks associated with granites from the Sierra Bachoco basement might be the deep source of fluoride. Outcropping of Sierra Bachoco in the west causes upward regional flow. Groundwater of longer residence time can be pumped there. The anomalous area is restricted to “La Victoria” because calcareous paleozoic rocks outcrop to the south. 相似文献
5.
Enrichment of fluoride in groundwater under the impact of saline water intrusion at the salt lake area of Yuncheng basin,northern China 总被引:2,自引:0,他引:2
Long-term intake of high-fluoride groundwater causes endemic fluorosis. This study, for the first time, discovered that the
salt lake water intrusion into neighboring shallow aquifers might result in elevation of fluoride content of the groundwater.
Two cross-sections along the groundwater flow paths were selected to study the geochemical processes controlling fluoride
concentration in Yuncheng basin, northern China. There are two major reasons for the observed elevation of fluoride content:
one is the direct contribution of the saline water; the other is the undersaturation of the groundwater with respect to fluorite
due to salt water intrusion, which appears to be more important reason. The processes of the fluorine activity reduction and
the change of Na/Ca ratio in groundwater induced by the intrusion of saline water favor further dissolution of fluorine-bearing
mineral, and it was modeled using PHREEQC. With the increase in Na concentration (by adding NaCl or Na2SO4 as Na source, calcium content kept invariable), the increase of NaF concentration was rapid at first and then became slower;
and the concentrations of HF, HF2−, CaF+, and MgF+ were continuously decreasing. The geochemical conditions in the study area are advantageous to the complexation of F− with Na+ and the decline of saturation index of CaF2, regardless of the water type (Cl–Na or SO4–Na type water). 相似文献
6.
Hydrochemical baseline condition of groundwater at the Mizunami underground research laboratory (MIU) 总被引:2,自引:0,他引:2
Hydrochemical conditions up to depths of 1000 m below ground level around the Mizunami Underground Research Laboratory were investigated to construct a “baseline condition model” describing the undisturbed hydrochemical environment prior to excavation of the underground facilities at Mizunami, Gifu, Japan. Groundwater chemistry in this area was classified into a Na–Ca–HCO3 type of groundwater in the upper part of sedimentary rock sequence and a Na–(Ca)–Cl type of groundwater in the deeper part of the sedimentary rock sequence and basement granite. The residence time of the groundwaters was estimated from their 14C contents to be approximately 9.3 ka in the middle part of the sedimentary rock and older than 50 ka in the deep part of the granite. The evolution processes of these groundwaters were inferred to be water–rock interactions such as weathering of plagioclase, dissolution of marine sulphate/sulphide minerals and carbonate minerals in the Na–Ca–HCO3 type of groundwater, and mixing between “low-salinity water” in the shallow part and “higher-salinity water” in the deeper part of the granite in the Na–(Ca)–Cl type of groundwater. The source of salinity in the deeper part of the granite was possibly a palaeo-hydrothermal water or a fossil seawater that recharged in the Miocene, subsequently being modified by long-term water–rock interaction. The Cl-depth trend in granitic groundwater changes at a depth of −400 m below sea level. The hydrogeological properties controlling the groundwater flow and/or mixing processes such as advection and diffusion were inferred to be different at this depth in the granite. This hydrochemical conceptual model is indispensable not only when constructing the numerical model for evaluating the hydrochemical disturbance during construction and operation of the MIU facility, but also when confirming a hydrogeological model. 相似文献
7.
Hydrogeochemistry data were utilized to understand origin, distribution, and geochemical evolution of the high-fluoride groundwater
in Taiyuan basin, China. In the study area, the spatial distribution of the high-fluoride groundwater are strictly controlled
by the host rock and geomorphic conditions. Three types of groundwater with the F− concentration of <1.5 mg/L, 1.5–2 mg/L and >2 mg/L are located in the areas bordering the limestone zones, in the areas bordering
the sandstone of Permian and Carboniferous, and in the depressions of the central parts of the basin, respectively. The high-fluoride
groundwater mostly have the high values of TDS, and its values of pH range from 7.2 to 8.8. The most common water types of
the high-fluoride groundwater are Na·Ca–HCO3 and Na·Mg–HCO3. The geochemical mode reveals that the dissolution of the fluorine-containing minerals and the evaporation effect of the
shallow groundwater control the evolution of high F− concentration in Taiyuan basin. 相似文献
8.
D. C. Kantharaja T. K. Lakkundi M. Basavanna S. Manjappa 《Environmental Earth Sciences》2012,65(1):67-76
Hydrogeochemical investigations with emphasis on groundwater fluoride concentrations were carried out in the Shivani watershed
area, Karnataka, South India. This drought-prone watershed is characterised by poor groundwater potential and is composed
of different lithounits like gneisses, migmatites, tonalites, mafics–ultramafics, conglomerates and quartzites. Analysis of
spatial variation of groundwater fluoride concentration through the use of GIS technology software platforms like ArcView
3.2a and MapInfo Professional 8.5 has enabled the identification of low-fluoride and high-fluoride areas within the watershed.
Geochemical data indicates that 38% of groundwater samples have excessive fluoride concentration which poses a health risk
to the population of the area. Correlation studies indicate that higher groundwater alkalinity activates leaching of fluoride
resulting in elevated concentrations of fluoride. No other significant geochemical interrelationship could be identified between
fluoride and rest of the physico-chemical parameters owing to the lack of any significant correlation coefficients. This holds
good in the case of both low-fluoride (<1.5 mg/L) and high-fluoride (>1.5 mg/L) groundwaters of the watershed. However, differential
or non-uniform type (positive or negative) of coefficient of correlation is observed between fluoride at different levels
and other physico-chemical parameters. Among the different lithounits of the study area, gneisses house comparatively more
number of high-fluoride groundwaters. Fluoride-bearing minerals biotite, hornblende and apatite are the probable natural sources
of groundwater fluoride. 相似文献
9.
Association of hydrogeological factors in temporal variations of fluoride concentration in a crystalline aquifer in India 总被引:6,自引:0,他引:6
The major part of groundwater in India is found in granitic aquifers. Fluoride in groundwater from a crystalline aquifer in a semi-arid region of granitic rocks in India, known as Maheshwaram watershed, was analyzed for spatial and temporal variability during 1999–2002 to assess the effect of hydrogeological factors on fluoride concentration. Samples were collected from 32 representative wells in the area for the pre- and post-monsoon seasons and analyzed for F content. The CHESS computer program was used to calculate ionic activities of aqueous species and the mineral saturation index (SI) for calcite and fluorite. The GARDENIA computer program was used to calculate the recharge values in the study area. The influences of dissolution kinetics of fluoride minerals and recharge from rainfall on fluoride concentration were of interest and results clearly indicate that fluoride content in groundwater depends on the interaction period of groundwater with host rock. Results could also be utilized for designing remedial measures particularly with dilution method in an optimal way. 相似文献
10.
Yvonne S. Anku Bruce Banoeng-Yakubo Daniel K. Asiedu Sandow M. Yidana 《Environmental Geology》2009,58(5):989-997
Hydrochemical data are presented for groundwater samples, collected from fractured aquifers in parts of northern Ghana. The
data was collected to assess the groundwater suitability for domestic and agricultural use. Results of the study reveal that
the pH of the groundwater in the area is slightly acidic to slightly alkaline. The electrical conductivity values, total dissolved
solids (TDS) values and calcium, magnesium and sodium concentrations in the groundwater are generally below the limit set
by the WHO for potable water supply. On the basis of activity diagrams, groundwater from the fractured aquifers appears to
be stable within the montmorillonite field, suggesting weathering of silicate minerals. An inverse distance weighting interpolator
with a power of 2 was applied to the data points to produce prediction maps for nitrate and fluoride. The distribution maps
show the presence of high nitrate concentrations (50–194 mg/l) in some of the boreholes in the western part of the study area
indicating anthropogenic impact on the groundwater. Elevated fluoride level (1.5–4 mg/l), higher than the WHO allowable fluoride
concentration of 1.5, is recorded in the groundwater underlying the northeastern part of the study area, more specifically
Bongo and its surrounding communities of the Upper East region. Results of this study suggest that groundwater from the fractured
aquifers in the area exhibit low sodicity–low salinity (S1–C1), low sodicity–medium salinity (S1–C2) characteristics [United
States Salinity Laboratory (USSL) classification scheme]. All data points from this study plot within the ‘Excellent to good’
category on a Wilcox diagram. Groundwater in this area thus appears to provide irrigation water of excellent quality. The
hydrochemical results indicate that, although nitrate and fluoride concentrations in some boreholes are high, the groundwater
in the study area, based on the parameters analyzed, is chemically potable and suitable for domestic and agricultural purposes. 相似文献
11.
Geochemical investigation of groundwater in a Granitic Island: a case study from Kinmen Island,Taiwan 总被引:1,自引:0,他引:1
Tai-Sheng Liou Hsueh-Yu Lu Cheng-Kuo Lin Wayne Lin Yu-Te Chang Jeng-Ming Chien Wen-Fu Chen 《Environmental Geology》2009,58(7):1575-1585
Kinmen Island is principally composed of low permeable granitoid and covered by a very thin sedimentary layer. Both surface
and groundwater resources are limited and water demand is increasing with time. The groundwater in the granitoid has been
surveyed as an alternative water source for daily use. Two to five highly fractured zones in the granitoid aquifer for each
site were first determined by geochemical well logging. Accordingly, ten samples were collected from three sites. Using environmental
isotopes and geochemical modeling, geochemical processes occurring due to water–rock interaction in the granitoid aquifer
can be quantitatively interpreted. The stable isotopes of oxygen and hydrogen in groundwaters cluster along Taiwan’s local
meteoric waterline, indicating evaporation does not have considerable effect on groundwaters. Given such a high evaporation
rate for Kinmen Island, this result implies that infiltration rate of groundwater is high enough to reduce retention time
through a well-developed fracture zone. NetpathXL is employed for inverse geochemical modeling. Results determine gypsum as
being the major source of sulfate for deep groundwaters. The contribution from pyrite is minor. In addition, the weathering
of albite to kaolinite is the dominant water–rock interaction characterizing geochemical compositions of deep groundwater
in Kinmen Island. 相似文献
12.
A strong geochemical gradient was observed in the thick overburden aquifer of the Asa drainage basin. Different types of
groundwater occur at different (downslope) locations and groundwater table depths. The following sequence was noticed with
increasing distance downslope or with increasing groundwater table depth:
1. Ca–Mg–HCO3 water at about 390-m groundwater table elevations or upslope locations.
2. Ca–Mg–HCO3–Cl water at middle-slope locations or groundwater table elevations of about 350 m above sea level;
3. Ca–Mg–SO4–Cl water at downslope locations or groundwater table elevations of about 300 m above sea level.
In this basin, changes in the type of water are expected at about every 40–50 m depth from the surface. Statistical analysis
via the determination of the correlation coefficient (r) and regression analysis shows that about 80–99% of the variation in groundwater chemistry is accounted for by the topography,
using the model presented in this paper. The rate of change in the sequence will depend on the permeability of the aquifer,
which determines the rate of groundwater flow and the residence time, and the nature of recharge.
Received: 4 February 1997 · Accepted: 22 July 1997 相似文献
13.
The groundwaters from Zhongxiang City, Hubei Province of central China, have high fluoride concentration up to 3.67 mg/L,
and cases of dental fluorosis have been found in this region. To delineate the nature and extent of high fluoride groundwaters
and to assess the major geochemical factors controlling the fluoride enrichment in groundwater, 14 groundwater samples and
5 Quaternary sediment samples were collected and their chemistry were determined in this study. Some water samples from fissured
hard rock aquifers and Quaternary aquifers have high fluoride concentrations, whereas all karst water samples contain fluoride
less than 1.5 mg/L due to their high Ca/Na ratios. For the high fluoride groundwaters in the fissured hard rocks, high HCO3
− concentration and alkaline condition favor dissolution of fluorite and anion exchange between OH− in groundwater and exchangeable F− in some fluoride-bearing minerals. For fluoride enrichment in groundwaters of Quaternary aquifers, high contents of fluoride
in the aquifer sediments and evapotranspiration are important controls. 相似文献
14.
Temporal variations of fluoride concentration in Isparta public water system and health impact assessment (SW-Turkey) 总被引:1,自引:0,他引:1
Water–rock interaction is one of the prime factors affecting the fluoride contents of surface and groundwater. If fluoride
concentration of drinking water has been neglected, excess fluoride can cause serious dental and medical problems on human
health, which is well known at Golcuk-Isparta region. In the research area, Egirdir lake, Golcuk lake and surrounding springs
have been utilized as drinking water sources. Golcuk lake water and surrounding groundwaters have high fluoride content (1.4–4.6 mg/l),
which is above the WHO standards. Fluoride is predominantly supplied by dissolution of fluoride within the fluormicas of volcanics
during the circulation of water. Fluoride concentrations of waters have shown variations for dry and rainy seasons depending
on the degree of interaction between groundwater and volcanic rocks. It tends to decrease in rainy seasons and increase in
dry seasons for all years. In this study, temporal variations and spatial distribution of fluoride concentration in public
water system of Isparta were investigated to get benefit using GIS techniques from1990 to 2003 years. Extremely fluoride concentrations
were measured in the public water system in 1990 at almost every district of the city. In 2003, fluoride content of the public
water system decreased in some district of city due to drinking water has started obtaining from Egirdir lake in 1995. The
fluoride contents of Isparta drinking water ought to be modified with suitable mixture of lake waters and groundwater point
of view to health impact. 相似文献
15.
The supraregional GIS-supported stochastical model, WEKU, for the determination of groundwater residence times in the upper
aquifers of large groundwater provinces is presented. Using a two-dimensional analytical model of groundwater flow, groundwater
residence times are determined within two extreme cases. In the first case, maximal groundwater residence times are calculated,
representing the part of groundwater, that is drained by the main surface water of a groundwater catchment area. In the second
case, minimal groundwater residence times for drainage into the nearest surface water are determined. Using explicit distribution
functions of the input parameters, mean values as well as potential ranges of variations of the groundwater residence times
are derived. The WEKU model has been used for the determination of groundwater residence times throughout Germany. The model
results – mean values and deviations of the groundwater velocity and the maximal and minimal groundwater residence times in
the upper aquifers – are presented by general maps and discussed in detail. It is shown that the groundwater residence times
in the upper aquifer vary regionally, differentiated between less than 1 year and more than 2000 years. Using this information,
the time scales can be specified, until measures to remediate polluted groundwater resources may lead to a substantial groundwater
quality improvement in the different groundwater provinces of Germany. With respect to its supraregional scale of application,
the WEKU model may serve as a useful tool for the supraregional groundwater management on a state, federal or international
level.
Received: 15 August 1995 · Accepted: 15 October 1995 相似文献
16.
《Applied Geochemistry》1999,14(7):917-925
The origin of salinity within the Äspö groundwater system is investigated by combining interpretations of conservative dissolved ions and of stable isotope ratios in water. The interpretation concludes that the groundwater salinity results from a mixing between Baltic Sea water intrusion and a deep seated saline groundwater of marine origin. This conclusion supports the geochemical model developed for the Äspö site. The residence time of the deep salinity is assessed by comparing the 36Cl content of dissolved salt at different depths and the secular equilibrium value of the host rock. The 36Cl of deepest levels corresponding to the highest salinity, is in equilibrium with rock, suggesting a penetration of the deep salinity into the host rock more than 1.5 Ma ago. 相似文献
17.
Geochemical processes controlling fluoride-bearing groundwater in the granitic aquifer of a semi-arid region 总被引:1,自引:0,他引:1
N. Subba Rao A. Dinakar P. Surya Rao P. N. Rao Pandith Madhnure K. M. Prasad G. Sudarshan 《Journal of the Geological Society of India》2016,88(3):350-356
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
18.
The hydrogeochemical characterization of Morsott-El Aouinet aquifer, Northeastern Algeria 总被引:1,自引:0,他引:1
A study of the hydrogeochemical processes in the Morsott-El Aouinet aquifer was carried out with the objective of identifying
the geochemical processes and their relation with groundwater quality as well as to get an insight into the hydrochemical
evaluation of groundwater. The high salinity coupled with groundwater level decline pose serious problems for current irrigation
and domestic water supplies as well as future exploitation. A combined hydrogeologic and isotopic investigation have been
carried out using chemical and isotopic data to deduce a hydrochemical evaluation of the aquifer system based on the ionic
constituents, water types, hydrochemical facies and factors controlling groundwater quality. The ionic speciation and mineral
dissolution/precipitation was calculated by WATEQF package software. The increase in salinity is related to the dissolution
and/or precipitation processes during the water–rock interaction and to the cationic exchange reactions between groundwater
and clay minerals. The isotopic analysis of some groundwater samples shows a similarity with the meteoric waters reflect their
short residence time and a lowest evaporation phenomenon of infiltrated groundwater. 相似文献
19.
Groundwater samples were collected from 25 sampling sites of the Oropos–Kalamos basin aiming to describe the groundwater quality
in relation to geology, lithology and anthropogenic activities of the study area. Chromium speciation analysis, factor analysis,
GIS database and geochemical data proved successful tools for the identification of natural and anthropogenic factors controlling
the geochemical data variability and for the identification of the redox couple controlling Cr speciation. A Durov diagram
is used to classify groundwater quality into five types: Ca–HCO3, Mg–HCO3, Na–Cl, Mg–Cl and Ca–Cl. The groundwater quality of Oropos–Kalamos is influenced by various natural and anthropogenic factors.
Evaluation of water quality for drinking and irrigation purposes is discussed. 相似文献
20.
Said Ettazarini 《Environmental Geology》2005,49(2):293-299
Possible water–rock interaction processes, in the Moroccan basin of Oum Er-Rabia, were discussed by a geochemical study of groundwater from the Turonian limestone aquifer, the most important water resource in the region. Different types of water according to the classification of Piper were defined. Waters have shown an evolution from dominant CHO3–Ca–Mg type through mixed to SO4–Cl–Ca–Mg type. The use of geochemical diagrams and chemical speciation modeling method has shown that water–rock interaction is mainly controlled by carbonate and anhydrite dissolution, ion exchange and reverse ion exchange processes. Water–rock equilibrium conditions are favorable for the precipitation of calcite, dolomite, kaolinite and magnesian smectite. 相似文献