the thermal and mineral springs of aitoloakarnania prefecture function mechanism and origin of groundwater the study area is located in the northwestern part of greece in aitoloakarnania prefecture in this region where no volcanic activity exists thermal springs such as kremasta and kokkino stefani well known for their healing properties occur the objective of this study was the investigation of these springs as well as the study of the chemical composition and origin of water relationships between these springs were also examined the geological setting of the area comprises sedimentary rocks of the pindos gavrovo tripolis and ionian geotectonic zones deformed by orogenic movements followed by neogene extensional tectonism the thermal and mineral springs were classified into three main groups the first group is characterized by ca hco3 water type and low water temperatures it corresponds to the springs that are hosted in the ionian zone and their possible enrichment in so4 is mainly attributed to the evaporites the other two groups consist of alkaline thermal water mainly hosted in the formations of gavrovo tripolis zone in these two groups the very strong reducing conditions that prevail are expressed by high amounts of nh3 and h2s moreover na f li sr and ba display elevated concentrations the second includes mineral waters of ca na hco3 type that are depleted in calcium their residence time is rather long and they originate from deep water circulation through siliceous rocks the third group includes thermal waters of ca mg na hco3 water type of higher water temperatures that reveal characteristics of deep circulation directly associated with the underlain limestones

geochemistry genesis and health implications of fluoriferous groundwaters in the upper regions of ghana the most appropriate and widely used source of drinking water for the populations of the upper regions of ghana is groundwater in general groundwater quality is acceptable except for some parts of the bolgatanga and bongo districts where there are occurrences of elevated levels of natural groundwater fluoride concentrations of groundwater fluoride in excess of the world health organization who maximum guideline value 1 5 mg l in the bongo area have been known since 1978 however the effect of fluoride on people ingesting the water did not receive public and medical attention until october 1993 when health personnel were asked to investigate the cause of stained teeth in school children the investigation established that 62 of the total population of school children in the bongo area had dental fluorosis against this background a study was initiated to understand the geochemistry genesis and distribution of fluoride in relation to the geology of the area groundwater fluoride in the upper regions ranges from 0 11 to 4 60 ppm with the highest concentrations associated with the fluorine enriched bongo coarse grained hornblende granite and syenite suite the source of groundwater fluoride within the bongo granitoids is dissolution of the mineral fluorite and dissolution of and anion exchange with micaceous minerals and their clay products applying the who recommended guideline values for fluoride in drinking water reveals that 49 of wells in the area deliver water below the optimum level of 0 5 mg l f these populations are thus prone to dental caries twenty eight percent of the wells fall within the optimum interval for good dental health 0 5 1 5 mg l f twenty three percent of the wells have concentrations above the recommended maximum guideline limit of 1 5 mg l f this population is susceptible to dental and possibly skeletal fluorosis climatic conditions of the area suggest that the individual water consumption is in the order of 3 to 4 l which is higher than the who estimate of 2 l adult day in addition dietary intake for the upper region population is probably higher than who baseline values 0 2 0 5 mg day this implies that a much higher population is susceptible to developing dental and skeletal fluorosis than originally suspected geochemical symbol plot maps help geochemists understand factors controlling the distribution and uptake of fluoride in the upper regions but they are of minimal value to health officials responsible for planning epidemiological studies and dental health education programs in the region by casting fluoride data into contoured geochemical health risk maps using intake interval guidelines more closely aligned to regional climatic and dietary conditions health officals can better judge the impacts regional and population based of fluoride on segments of the population such as various sex and age groups

the origin of fluoride in groundwater supply to hermosillo city sonora mexico 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

oxygen isotope geochemistry of archean granitoid gneisses and related rocks in the english river subprovince northwestern ontario whole rock 18o values for archean granitoid gneisses from the southern domain of the english river subprovince northwestern ontario increase from an average of 6 5 for 3000 ma old tonalites in the eastern lac seul area to an average of 7 9 for 2750 2800 ma old tonalites trondhjemites and granodiorites that occur in the kenora and eastern lac seul areas still younger granitoid plutons and dykes 2660 2560 ma that intrude the older gneisses also have average 18o 7 9 these values lie towards the low end of the range known for normal granitoid rocks oxygen isotope data for minerals from the granitoid rocks indicate minor isotopic disequilibrium but no evidence exists for large scale depletion in 18o subsequent to granitoid formation rocks rich in 18o are abundant only in the northern domain of the english river subprovince which is dominated by paragneiss and metasedimentary migmatite 18o 9 12 within the kenora area of the southern domain however a remnant supracrustal sequence characterized by a thin metachert iron formation unit 18o 8 10 has been recognized the low whole rock oxygen isotope values indicate that pre existing 18o rich supracrustal rocks were not involved in the genesis of the 3000 ma old gneisses and have made only limited if any contribution to the magmas that formed the younger units this conclusion is supported by the low initial sr isotope ratios of these rocks 0 7009 0 7027 the oxygen and strontium isotope data require that most of the granitoid rocks in the southern domain of the english river subprovince comprise juvenile or near juvenile additions to the continental crust

geochemical characteristics of fluoride in groundwater of gimcheon korea lithogenic and agricultural origins 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 18o 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 d and 18o 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 d and 18o 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

investigation of fluoride contamination and its mobility in groundwater of simlapal block of bankura district west bengal india 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

geochemistry of fluoride rich groundwater in kolar and tumkur districts of karnataka 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

fluorine distribution in waters of nalgonda district andhra pradesh india geochemical and hydrochemical studies were conducted in nalgonda district a p to explore the causes of high fluorine in waters causing a widespread incidence of fluorosis in the local population samples of granitic rocks soils stream sediments and waters were analyzed for f and other salient chemical parameters samples from the area of hyderabad city were analyzed for comparison the f content of waters in areas with endemic fluorosis ranges from 0 4 to 20 mg l the low calcium content of rocks and soils and the presence of high levels of sodium bicarbonate in soils and waters are important factors favoring high levels of f in waters

hydrochemistry of groundwater gw and surface water sw for assessment of fluoride in chinnaeru river basin nalgonda district ap india 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

hydrogeochemical processes and contaminants enrichment with special emphasis on fluoride in groundwater of birbhum district west bengal india 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

hydrogeochemical genesis of groundwaters with abnormal fluoride concentrations from zhongxiang city hubei province central china 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

hydrogeochemical characteristics of groundwater from the two main aquifers in the red river delta vietnam abstract in the red river delta situated in the northern part of vietnam nearly its entire population depends solely on groundwater for daily water consumptions for this reason groundwater quality assessments must be carefully carried out using hydrogeochemical properties to ensure effective groundwater resource planning for the delta s present and future groundwater use in this study the spatial and seasonal changes in the hydrogeochemical characteristics of groundwater in the two main aquifers of the rrd were investigated by analyzing the physicochemical data obtained in 2011 from 31 conjunctive wells in the delta s holocene unconfined aquifer hua and pleistocene confined aquifer pca using the piper diagram and the gibbs diagram results of the data analysis show that the groundwater in both aquifers in the upstream area of the delta is dominated by the ca 2 hco 3 water type while the na cl dominates along the middle stream and downstream areas seasonal changes in the hydrogeochemical facies in both aquifers comparing the results for the dry and the rainy seasons were detected in about one third of the sampling wells which were mainly located at the upstream portion of the delta the hydrogeochemical facies of hua were different from that of pca by about 45 of the sampling wells in both the dry and the rainy seasons which were found mostly in the upstream and middle stream areas

major ion chemistry of the ganga brahmaputra river system weathering processes and fluxes to the bay of bengal the ganga brahmaputra one of the world s largest river systems is first in terms of sediment transport and fourth in terms of water discharge a detailed and systematic study of the major ion chemistry of these rivers and their tributaries as well as the clay mineral composition of the bed sediments has been conducted the chemistry of the highland rivers upper reaches of the ganga the yamuna the brahmaputra the gandak and the ghaghra are all dominated by carbonate weathering ca mg and hco3 account for about 80 of the cations and anions in the lowland rivers the chambal the betwa and the ken hco3 excess over ca mg and a relatively high contribution of na k to the total cations indicate that silicate weathering and or contributions from alkaline saline soils and groundwaters could be important sources of major ions to these waters the chemistry of the ganga and the yamuna in the lower reaches is by and large dictated by the chemistry of their tributaries and their mixing proportions illite is the dominant clay mineral about 80 in the bedload sediments of the highland rivers kaolinite and chlorite together constitute the remaining 20 of the clays in the chambal betwa and ken smectite accounts for about 80 of the clays this difference in the clay mineral composition of the bed sediments is a reflection of the differences in the geology of their drainage basins the highland rivers weather acidic rocks whereas the others flow initially through basic effusives the ganga brahmaputra river system transports about 130 million tons of dissolved salts to the bay of bengal which is nearly 3 of the global river flux to the oceans the chemical denudation rates for the ganga and the brahmaputra basins are about 72 and 105 tons km yr 1 respectively which are factors of 2 to 3 higher than the global average the high denudation rate particularly in the brahmaputra is attributable to high relief and heavy rainfall

oxygen isotope evidence for the origin of discrete granitoid plutons from the archean western wabigoon belt northwestern ontario abstract the whole rock 18 o values of samples from twelve discrete archean plutons intruding the western wabigoon granite greenstone belt northwestern ontario range from 6 8 to 9 5 most samples with 18 o 8 7 however come from portions of the burditt lake stock or the esox lake area that have been affected by deuteric or metasomatic activity the distribution of 18 o values for the remaining samples is very similar to that known for the large batholithic complexes and gneissic terrains that dominate this portion of northwestern ontario the generally low 18 o values of the discrete granitoid plutons suggest that 18 o rich supracrustal rocks were unimportant in their genesis like the granitoids of the batholithic complexes and gneissic terrains the discrete granitoid plutons represent new additions to the archean sialic crust

hydrochemical and isotopic characterisation of the bathonian and bajocian coastal aquifer of the caen area northern france abstract this paper describes the geochemical evolution of groundwater in the bathonian and bajocian aquifer along its flowpath since this aquifer represents one of the main sources of fresh water supply in the caen area and has been subjected to a holocene marine intrusion its management requires a sound knowledge of 1 the primary conditions and 2 the potential influence of either natural or anthropogenic pressures groundwater vertical sampling validity is discussed with the contribution of high resolution temperature logging the main processes of geochemical evolution along a groundwater flow line and the sea water intrusion characteristics are discussed using ionic concentrations br f and major elements and isotopes water 2 h and 18 o tdic 13 c and a 14 c sulphate 18 o and 34 s as the 13 c content of tdic is used as a tracer of water rock interaction it shows evidence of specific chemical and isotopic evolutions of groundwater within the aquifer both related to water rock interaction and mineral equilibria in groundwater all the above mentioned tracers evolve downflow cation concentrations are modified by exchange with clay minerals allowing a high f concentration in groundwater whereas br and so 2 4 concentrations appear to be redox condition dependant superimposed on these geochemical patterns 18 o and 2 h compositions indicate that aquifer recharge has varied significantly through time the chemical evolution of groundwater is locally affected by a salty water intrusion that is characterised by mixing between flandrian fresh water and sea water which has interacted with peat as evidenced by a high br cl ratio and so 2 4 reduction

fluoride incidence in groundwater in an area of peninsular india groundwater samples were collected from anantapur district andhra pradesh india the district is mainly underlain by peninsular gneisses of archaean age the samples were analysed for fluoride f along with other chemical parameters the results suggest that the main sources of f in groundwater in the district are the country rocks in which fluorine is strongly absorbed in soils consisting of clay minerals a strong positive correlation between f and lithogenic sodium reflects weathering activity this is responsible for the leaching of f which is also caused by the semi arid climate and intensive irrigation in the area an alkaline environment of circulating water in the investigated area mainly facilitates leaching of f from the soils contributing to high f containing groundwater a longer residence time of water in the aquifer zone caused by a high rate of evapotranspiration and a weathered zone of low hydraulic conductivity which promotes the dissolution of fluorine bearing minerals is another factor that further increases the f content in groundwater suggestions are made to improve groundwater quality and thus the health status of the population

hydrochemical characterization of drinking groundwater with special reference to fluoride in an arid area of china and the control of aquifer leakage on its concentrations the objective of the study is to determine the distribution and origin of fluoride in two confined aquifers within the depth of 80 240 m mid deep confined aquifers in shizuishan city an arid area in northwest china based on geological and hydrogeological conditions the distribution patterns of fluoride in the two confined aquifers were studied correlation analysis was used to reveal the mechanisms and reactions influencing the groundwater chemistry the control of aquifer leakage induced by intense groundwater abstraction on fluoride concentrations was also discussed the results show that the concentration of f in some locations of the study area is beyond the limit of the standards for drinking water quality of china correlation analysis shows that the major reactions occurring in the confined aquifers are dissolution of gypsum fluorite and halite and precipitation of calcite and dolomite groundwater leakage from shallow aquifers is also responsible for the elevation of fluoride in mid deep confined aquifers the research is a scientific basis for the rational development and utilization of groundwater in this area and it may be referenced by international scholars for similar research in other parts of the world

characterization and appraisal of facets influencing geochemistry of groundwater in the kulpawn sub basin of the white volta basin ghana groundwater composition in the kulpawn basin is largely controlled by aluminosilicates dissolution and cation exchange resulting in mainly ca mg hco3 and nahco3 water types principal component analysis piper graphical classification and stable isotope 18o and 2h of groundwater and surface water samples were used to delineate geochemical processes and groundwater facies the groundwater is mildly acid to neutral and low in conductivity chemical constituents except hco3 and sio2 have low concentration no cation shows clear majority however the order of relative abundance is na ca2 mg2 k hco3 is the predominant anion and the order of abundance is hco3 no3 so42 cl sio2 concentration is high compared with the major cations dissolution of plagioclase pyroxene and biotite and cation exchange are responsible for groundwater composition isotopic data suggest integrative smooth and rapid recharge from meteoric origin the groundwater quality is generally good for domestic usage however 18 and 47 of boreholes respectively have no3 and f levels outside who recommended limits suggesting potential physiological problems in some localities the groundwater has low sodium absorption ratio and low to moderate salinity hazard but significant magnesium hazard partially limiting its use for irrigation

tsunamis observed in greece and the surrounding area from antiquity up to the present times abstract a new and improved catalogue of tsunamis observed in greece and the surrounding area from antiquity up to the present time is presented reliable information derived from previous catalogues as well as original historical information which has not been previously taken into account has been used as data source as far as the associated earthquakes are concerned some recent and reliable seismological catalogues have been used as data sources the main cause of the generation of tsunamis is the shallow seismic activity that occurs along the hellenic arc as well as in the internal seismic zone of the aegean area the statistics for tsunamis indicate that the tsunami hazard is low considering the area in question as a whole ten distinct coastal regions in which this hazard can be suggested as medium or high have been defined

effect of land use and urbanization on hydrochemistry and contamination of groundwater from taejon area korea abstract taejon metropolitan city located in the central part of south korea has grown and urbanized rapidly the city depends heavily on groundwater as a water resource because of ubiquitous pollution sources the quality and contamination have become important issues for the urban groundwater supply this study has investigated the chemical characteristics and the contamination of groundwater in relation to land use an attempt was made to distinguish anthrophogenic inputs from the influence of natural chemical weathering on the chemical composition of groundwater at taejon groundwater samples collected at 170 locations in the taejon area show very variable chemical composition of groundwater e g electrical conductance ranges from 65 to 1 290 s cm most groundwater is weakly acidic and the groundwater chemistry is more influenced by land use and urbanization than by aquifer rock type most groundwater from green areas and new town residential districts has low electrical conductance and is of ca hco 3 type whereas the chemical composition of groundwater from the old downtown and industrial district is shifted towards a ca cl no 3 so 4 type with high electrical conductance a number of groundwater samples in the urbanized area are contaminated by high nitrate and chlorine and exhibit high hardness the epco 2 that is the co 2 content of a water sample relative to pure water was computed to obtain more insight into the origin of co 2 and bicarbonate in the groundwater the co 2 concentration of groundwater in the urbanized area shows a rough positive relationship with the concentration of major inorganic components the sources of nitrate chlorine and excess co 2 in the groundwater are likely to be municipal wastes of unlined landfill sites leaky latrines and sewage lines chemical data of commercial mineral water from other jurassic granite areas were compared to the chemical composition of the groundwater in the taejon area factor analysis of the chemical data shows that the hco 3 and no 3 concentrations have the highest factor loadings on factor 1 and factor 2 respectively factors 1 and 2 represent major contributions from natural processes and human activities respectively the results of the factor analysis indicate that the levels of ca 2 mg 2 na cl and so 4 2 derive from both pollution sources and natural weathering reactions

fluoride contamination of groundwater in parts of eastern india and a preliminary experimental study of fluoride adsorption by natural haematite iron ore and synthetic magnetite 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 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

geochemical characteristics and controlling factors of chemical composition of groundwater in a part of guntur district andhra pradesh india a survey on quality of groundwater was carried out for assessing the geochemical characteristics and controlling factors of chemical composition of groundwater in a part of guntur district andhra pradesh india where the area is underlain by peninsular gneissic complex the results of the groundwater chemistry show a variation in ph ec tds ca2 mg2 na k hco3 cl so4 2 no3 and f the chemical composition of groundwater is mainly characterized by na hco3 facies hydrogeochemical type transits from na cl hco3 to na hco3 cl along the flow path graphical and binary diagrams correlation coefficients and saturation indices clearly explain that the chemical composition of groundwater is mainly controlled by geogenic processes rock weathering mineral dissolution ion exchange and evaporation and anthropogenic sources irrigation return flow wastewater agrochemicals and constructional activities the principal component pc analysis transforms the chemical variables into four pcs which account for 87 of the total variance of the groundwater chemistry the pc i has high positive loadings of ph hco3 no3 k mg2 and f attributing to mineral weathering and dissolution and agrochemicals nitrogen phosphate and potash fertilizers the pc ii loadings are highly positive for na tds cl and f representing the rock weathering mineral dissolution ion exchange evaporation irrigation return flow and phosphate fertilizers the pc iii shows high loading of ca2 which is caused by mineral weathering and dissolution and constructional activities the pc iv has high positive loading of mg2 and so4 2 measuring the mineral weathering and dissolution and soil amendments the spatial distribution of pc scores explains that the geogenic processes are the primary contributors and man made activities are the secondary factors responsible for modifications of groundwater chemistry further geochemical modeling of groundwater also clearly confirms the water rock interactions with respect to the phases of calcite dolomite fluorite halite gypsum k feldspar albite and co2 which are the prime factors controlling the chemistry of groundwater while the rate of reaction and intensity are influenced by climate and anthropogenic activities the study helps as baseline information to assess the sources of factors controlling the chemical composition of groundwater and also in enhancing the groundwater quality management

petrological evolution of the crust and mantle in its simplest form crust mantle evolution can be thought of as a study of the processes by which material is lost from the mantle and forms new crust the overall goal is achievement of mass balance between the average composition of material known to have been added to the crust and the estimated average composition of the entire crust attainment of this goal for the earth has been elusive primarily because the materials available for study have generally been involved in several stages of evolution including fractionation within both the crust and mantle and recycling of material from crust to mantle thereby complicating the interpretation of available data although the overall composition of the continental crust generally has been modelled as andesitic taylor and mclennan 1981a the present upper continental crust is granodioritic and requires a more mafic lower crust it has been proposed taylor and mclennan 1981a that originally the archean crust had an andesitic composition throughout its volume and that partial melting in the lower crust developed more felsic melts that rose to enrich the upper crust leaving a more mafic residuum of lower crust this concept has been challenged by weaver and tarney 1981a who argue that the granulites of presumed lower crustal origin do not have the correct compositions for this model if one considers more recent additions to the crust from the mantle over the past several hundred million years it appears that these latest additions are basaltic with very little if any granitic additions in fact barker 1981 in his introduction to a special issue of jgr on granites and rhyolites states to date no one has demonstrated that such magmas may form in the mantle indeed much experimental and geochemical work indicates that such siliceous liquids cannot originate there therefore such magmas must be generated in the crust in island arc environments where the average composition of added material normally is thought to be andesitic a anderson 1982 has shown that the parent melt is basaltic not andesitic in addition kay 1980 has shown that the k content of the newly added material is less than the average k content of the previously existing crust in the oceanic crust the additions from the mantle are basaltic and according to o hara 1982 probably are derived from very mafic picritic melts as parents continental flood basalts which have also added material from mantle to crust also are clearly derived from basaltic parental melts basaltic volcanism study project 1981 thus the evidence for the nature of material subtracted from the mantle and added to the crust for the past several hundred million or perhaps a billion years points to very mafic melts this contrasts significantly with the overall andesitic composition of continental crust it implies furthermore that if the overall archean crustal composition was andesitic as estimated by taylor and mclennan 1981a then additions to the crust have become more mafic with time a concept in direct conflict with most models in which secular trends are from mafic to felsic with time veizer and jansen 1979 and mclennan et al 198o a question which is beginning to appear either explicitly or implicitly is whether crustal volcanic rocks or the crust as a whole really represents the parent melt that formed in the mantle a anderson 1982 o hara 1982 and nisbet and walker 1982

geochemical assessment of groundwater contamination with special emphasizes on fluoride a case study from midyan basin northwestern saudi arabia water samples for chemical analyses were collected in january 2012 a total of 72 samples of groundwater were collected from 72 boreholes in the midyan basin northwestern saudi arabia samples were collected in polyethylene bottles and preserved and the used analytical techniques were in accordance with the standard methods from american public health association geochemical analyses of the groundwater samples from midyan basin reveal the concentration of fluoride f between 0 98 and 2 1 mg l other parameters e g ph ec tds hco3 so4 no3 cl k na mg and ca have been found in a variable proportion among them the concentration of ec hco3 k na and mg is higher than the permissible limits according to thermodynamical considerations most of the analysed samples are graded under saturated with respect to calcite and fluoride while saturation has been observed in some samples the under saturation could probably be attributed to low concentration of calcite and fluoride in the studied wells fluoride concentration shows weak positive correlation with ec tds na cl and so4 factors controlling the concentration of fluoride f in the studied samples are the area climate water chemistry and the presence of accessory minerals in the rocks through which groundwater is circulating besides the anthropogenic activities in the area

prevalence of fluorosis in the fluoride enriched groundwater in semi arid parts of eastern india geochemistry and health implications abstract fluorosis is becoming a global environmental toxicological problem and is most commonly found in water stressed regions in order to evaluate the geochemical mechanism of fluoride enrichment in groundwater and health implications in the padwakodari environs of eastern part of india a total of twenty two samples were collected and analysed for physico chemical parameters spreading across the study area geologically the area mainly comprises of phyllites granite gneiss mica schist and sandstone high fluoride concentrations found mainly in the granite gneisses which are situated central to northwestern parts of the study area the concentration of fluoride in the groundwater samples ranges from 0 3 to 11 mg l with an average of 2 mg l 64 of the groundwater samples containing fluoride concentration that exceed the who drinking water guidelines value of 1 5 mg l chronic ingestion of high doses has been linked to the development of dental fluorosis and in extreme cases skeletal fluorosis the dominant geochemical facies present in water are na ca mg hco 3 11 samples na mg ca hco 3 5 samples ca na mg hco 3 5 samples and ca mg na hco 3 1 sample sodium and bicarbonate ions being major component in majority of the water types located mostly in the granite gneiss formation has a tendency to increase fluoride concentration in groundwater by dissolving the fluoride from fluoride bearing minerals the oversaturation of half of the samples with respect to calcite and majority of samples undersaturation with respect to fluorite makes it feasible for fluoride to get released in to the groundwater decreasing ca activity downgradient recharge to discharge leads to a dominance of fluorite unsaturated conditions and consequently to mobilization of fluoride in groundwater the results indicate that the fluoride concentration in groundwater is mainly governed by high weathering of fluoride bearing minerals i e apatite and biotite in granite gneiss contains abundant fluoride alkaline hydrogeological environment high temperature low rainfall evapotranspiration and ion exchange

dissolution of fluoride in groundwater a water rock interaction study fluoride rich groundwater is well known in granite aquifers in india and the world although its presence is necessary chances of health risk become high if the fluoride concentration is more than the permissible limit of 1 5 mg l world health organization who in drinking water fluoride mainly occurs in groundwater as a natural constituent results of a laboratory study on water rock interaction at normal temperature pressure and different chemical conditions indicate that the specific conductivity ph ca and hco3 are important chemical parameters for the dissolution of fluoride to groundwater from fluoride rich minerals e g fluorite experimental results indicate that an alkaline medium ph 7 6 to 8 6 high hco3 concentration ranging from 350 450 mg l and moderate specific conductivity ranging from 750 1 750 s cm are favourable for fluoride dissolution no significant correlation existed between fluoride and cahco3

variation of groundwater hydrochemical characteristics in the plain area of the tarim basin xinjiang region china groundwater hydrochemistry could reveal the interaction mechanism between groundwater and the environment which provides a scientific basis for environmental resources management in this study shukaliefu s classification method and piper diagram were adopted to determine the hydrochemical types of groundwater in the tarim basin of xinjiang china the method of one vote veto was applied to evaluate the quality of groundwater phreeqc software was used to calculate the saturation indices of calcite and fluorite in groundwater by comparing groundwater quality data of 2003 and 2011 we characterized the variations in hydrochemical types and water quality types salinization of groundwater and fluoride geochemistry of the plain area of the tarim basin results show that the primary anion in phreatic water in the plain area of the tarim basin changed from hco3 to so4 2 or cl on the contrary the primary anion in confined water changed from so4 2 or cl to hco3 in 2003 63 1 of the sampling points in the study area exceeded the class iii water quality standard of china in 2011 the proportion increased to 82 5 in addition severe groundwater salinization was found at 19 7 of the sampling points some of the deep groundwater samples were salinized as well in the aksu area at the north west part of the tarim basin f concentration exceeding the standard limit 1 mg l was found to be 55 0 of the groundwater samples tested based on these findings it is concluded that the phreatic water in the study area was severely influenced by the industrial wastewater and domestic sewage related to human activities while the confined water was less affected the general quality of groundwater was in an aggravation trend and the groundwater salinization was in a severe condition in this area the ca2 na ionic exchange the unsaturated fluorite and oversaturated calcite in the aquifer of the aksu area are proposed to cause f enrichment in groundwater of this area

on elevated fluoride and boron concentrations in groundwaters associated with the lake saint martin impact structure manitoba abstract hydrogeological investigations conducted by the geological survey of canada in the lake saint martin region of manitoba have confirmed earlier reports of naturally elevated f and b concentrations in local groundwaters fluoride and b concentrations are highly correlated r 2 0 905 and reach 15 1 mg l and 8 5 mg l respectively virtually all groundwaters with f concentrations greater than the drinking water limit of 1 5 mg l are from wells within the lake saint martin impact structure a 208 ma complex crater 23 km in diameter underlying a large part of the study area the high f groundwaters can be classified into two groups according to their anionic and isotopic compositions group i samples consist of na mixed anion groundwaters with cl greater than 100 mg l and highly depleted 18 o compositions indicative of recharge under much cooler climatic conditions than at present samples belonging to this group exhibit a striking relationship to crater morphology and are found in an arcuate belt within the southern rim of the impact structure group ii high f samples consist of na hco 3 so 4 groundwaters with little cl and less depleted 18 o compositions samples belonging to this group are associated with groundwaters recharged locally on a low ridge within the impact structure this paper traces the probable source of high f groundwaters to phosphatic pellets in shales of the winnipeg formation a regional basal clastic unit which sub crops at shallow depth beneath the crater rim as a result of more than 200 m of structural uplift associated with the impact event this extensive aquifer is known elsewhere in southern manitoba for its naturally softened groundwaters and locally elevated f concentrations group i groundwaters are interpreted as discharge from the winnipeg formation where it abuts against crater fill deposits group ii high f groundwaters are interpreted as modern recharge from within the impact structure displacing group i groundwaters thus elevated f and b concentrations observed in groundwaters of the lake saint martin area represent the geochemical signature of upwelling from a deep regional aquifer the previously unsuspected discharge zone occurs within an isolated sub crop of the aquifer formed as a result of structural uplift caused by the impact event

the levels of fluorine in the sediments of the aquifer and their significance for fluorosis in coastal region of laizhou bay china the levels of fluorine in sediment cores obtained from changyi county pz core and laizhou county ts core are used to discuss the fluorine sources in groundwater and its enrichment dynamics the sediments in the aquifer are mainly constituted of granite gravels the levels of fluorine in the pz and ts cores range from 130 to 468 mg kg 139 528 mg kg with average values of 324 348 mg kg respectively which show relatively lower levels than the national average of fluorine in the soil or sediment thus the fluorosis in this area should not be attributed to the levels of fluorine in sediments the average fluorine concentrations in the aquifer from top to bottom are 154 139 200 222 mg kg for the ts core and 154 130 266 272 mg kg for the pz core respectively which are the lowest of the cores and extremely lower levels than the fresh granites such a fact indicates that a vast amount of fluorine has been leached into the groundwater moreover the fluorine leachability is estimated to be approximately 70 although the previous documents showed fluorine contents of the granite surrounding laizhou bay were almost equal to or even lower than the average levels of fluorine in fresh granites meanwhile a simulation experiment also reveals that fluorine release from rocks increases with the addition of seawater and brine water therefore the seawater intrusion may potentially enhance the fluorine leachability and should be an important dynamic of fluorine enrichment

spatial variation in arsenic and fluoride concentrations of shallow groundwater from the town of shahai in the hetao basin inner mongolia abstract twenty nine wells were selected for groundwater sampling in the town of shahai in the hetao basin inner mongolia four multilevel samplers were installed for monitoring groundwater chemistry at depths of 2 5 20 m results show that groundwater as exhibits a large spatial variation ranging between 0 96 and 720 g l with 71 of samples exceeding the who drinking water guideline value 10 g l fluoride concentrations range between 0 30 and 2 57 mg l there is no significant correlation between as and f concentrations greater as concentrations were found with increasing well depth however f concentrations do not show a consistent trend with depth groundwater with relatively low eh has high as concentrations indicating that the reducing environment is the major factor controlling as mobilization low as concentrations 2 into the aquifers and lead to reducing conditions that favor as release sediment composition is an additional factor in determining dissolved as concentrations in aquifers composed of yellowish brown fine sands at depths around 10 m groundwater generally has low as concentrations which is attributed to the high as adsorption capacity of the yellow brown fe oxyhydroxide coatings fluoride concentration is positively correlated with ph and negatively correlated with ca 2 concentration all groundwater samples are over saturated with respect to calcite and under saturated with respect to fluorite dissolution and precipitation of ca minerals such as fluorite and calcite and f adsorption desorption are likely controlling the concentration of f in groundwater

environmental hydrogeochemistry and genesis of fluoride in groundwaters of dindigul district tamilnadu india fluoride f is an indispensable element for the human s skeletal and dental health at prescribed levels and becomes lethal at higher levels spatial temporal variability of f and its geochemical control association with other dissolved ions in groundwater in the dindigul district of tamilnadu india were conducted to describe the geochemical dynamics of f in response to seasonal variability high concentrations of fluoride 1 5 mg l 1 were observed in the northern region of the district high levels of f were observed in non monsoon periods and low levels in monsoon because of dilution by precipitation bicarbonate was well correlated with f which explains that both ions were derived from the weathering while f has a very weak correlation with silica this implies that the silicate weathering does not supply f to the groundwater system the f pollution in dindigul groundwaters is mainly driven by two factors 1 the geogenic weathering inputs the geology of this area mainly comprises fluoride bearing minerals e g hornblende biotite gneiss and charnockite 2 the anthropogenic inputs agri fertilizers and tannery waste further f in the study area is mainly attributed to geogenic sources during pre and postmonsoons and anthropogenic sources in monsoon periods

hydrochemical characteristics of groundwater and surface water for domestic and irrigation purposes in vea catchment northern ghana 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

assessment of groundwater quality for irrigation and drinking purposes and identification of hydrogeochemical mechanisms evolution in northeastern tunisia oligocene and mio plio quaternary siliciclastic deposits constitute the most important deep aquifers of the kairouanai sahel region considering the over exploitation and contamination of the surface groundwater recourse to use deep groundwater was crucial these aquifers revealed three major hydrochemical facies hco3 mg hco3 na and so4 mg water types rock water interaction showed the main mechanisms are rock weathering and evaporation different parameters such as water quality index wqi sodium absorption ratio sar percentage of sodium residual sodium carbonate rsc magnesium hazard mh and permeability index pi were used to evaluate groundwater suitability for drinking and irrigation purposes results highlighted that groundwater is unsafe for irrigation based on pi mh rsc and salinity diagram according to the wqi values 10 25 of the water samples had good water quality 69 23 were considered as poor water 12 82 were very poor water and 7 69 were considered unsuitable for drinking purpose

hydrogeochemical processes of fluoride enrichment in chimakurthy pluton prakasam district andhra pradesh india thirty six groundwater samples were collected from chimakurthy area prakasam district andhra pradesh on hydrogeochemical evaluation it was found to be contaminated based on fluoride concentration the samples were segregated into group a group b and group c fluoride concentration varies from 0 23 to 9 84 mg l with the mean value of 2 01 mg l 44 of the tested samples had f 1 50 mg l apart from f the water was contaminated with no3 and cl implying both geogenic and anthropogenic pollution of the aquifer ionic dominance pattern was unique in samples with low moderate to high f concentrations na and hco3 were progressively increasing along with f from group a to c whereas ca2 and mg2 were depleting groundwater facies were unique among different group samples especially in end members with low and high f concentration suggesting that f dissolution was strongly influenced by the chemical nature of solution na cl molar ratio was 1 whereas na k tz and ca2 mg2 tz ratios were 1 in all samples indicating that na was released from silicate weathering process it also confirms that f was contributed from lithogenic sources of aquifer material mean molecular ratios of 1 for ca2 mg2 in group b samples and 1 1 2 in groups a and c support that the ca2 and mg2 were added into aquatic medium by calcite and dolomite dissolution contradictory distribution of f in north low and south high indicates that availability of f minerals in aquifer matrix influenced the rate of f absorption in accompanying water variation in f concentration in groundwater of the core area south supports the hypothesis of aquatic chemistry acting as catalyst in f dissolution into formation waters even though the aquifer was enriched with f minerals very high f in groundwater in the contact zone of country rock and plutonic intrusive indicates that f mineralization occurred under geothermal conditions the fracture network in disturbed and fragile contact zone has facilitated development of potential aquifers and enhancement in f concentration

the groundwater recharge regime of some slightly metamorphosed neoproterozoic sedimentary rocks an application of natural environmental tracers isotope data of precipitation and groundwater in parts of the voltaian basin in northern ghana were used to explain the groundwater recharge regime in the area groundwater recharge is an important parameter in the development of a decision support system for the management and efficient utilization of groundwater resources in the area it is therefore important to establish the processes and sources of groundwater recharge 18o and 2h data for local precipitation suggest enrichment relative to the global meteoric water line gmwl and indicate that precipitation takes place at a relative humidity less than 100 the groundwater data plot on an evaporation line with a slope of 5 suggesting a high degree of evaporative enrichment of the precipitation in the process of vertical infiltration and percolation through the unsaturated zone into the saturated zone this finding is consistent with the observation of high evapotranspiration rates in the area and ties in with the fact that significant clay fraction in the unsaturated zone limits vertical percolation and thus exposes the percolating rainwater to the effects of high temperatures and low humidities resulting in high evapotranspiration rates groundwater recharge estimates from the chloride mass balance cmb method suggest recharge in the range of 1 8 32 of the annual average precipitation in the form of rainfall the highest rates are associated with areas where open wells encourage significant amount of groundwater recharge from precipitation in the area in the northern parts of the study area groundwater recharge is lower than 12 the recharge so computed through the application of the cmb methodology takes on a spatial distribution akin to the converse of the spatial pattern of both 18o and 2h in the area as such the locations of the highest recharge are associated with the most depleted values of the two isotopes this observation is consistent with the assertion that low vertical hydraulic conductivities slow down vertical percolation of precipitation down to the groundwater water the percolating precipitation water thus gets enriched in the heavier isotopes through high evapotranspiration rates at the same time the amount of water that finally reaches the water table is considerably reduced copyright 2013 john wiley sons ltd

characteristics and chronology of fracture fluid infiltration in the archean eye dashwa lakes pluton superior province evidence from h c o isotopes and fluid inclusions the archean eye dashwa lakes pluton 2672 24 ma has domains of mineralogically fresh isotropic granite domains that have undergone bulk hydrothermal alteration and at least eleven sets of sequential fracture arrays each with distinctive mineral assemblages fresh granite is characterized by whole rock 18o 8 1 to 8 6 and primary magmatic quartz feldspar 1 3 quartz biotite 5 2 to 5 4 and quartz magnetite 9 8 fractionations magmatic fluids had a calculated isotopic composition of 18o 7 9 0 5 and d 80 5 these isotropic volumes of the granite have not experienced significant incursion of external thermal waters pegmatites quartz molybdenite veins and phlogopite muscovite coated fractures are sporadically distributed in the granite and were precipitated from high temperature magmatic fluids where 18o 8 0 to 10 3 and d 80 5

fluoride hydrogeochemistry in alluvial aquifer an implication to chemical weathering and ion exchange phenomena fluoride f concentration in some parts of the quaternary alluvial aquifer of birbhum district west bengal india varies from 0 31 to 13 61 mg l with an average of 3 13 mg l high f groundwater mostly belongs to na hco3 type isotopic signature suggests that most of the groundwater having fast recharge component either from flowing canals or rainfall contains relatively less f 2 mg l and relatively depleted 18o content 18o 5 to 4 on the other hand some of the groundwaters having relatively depleted 18o 4 to 3 do exhibit f in the range of 4 13 mg l average ratio of na na k 0 69 and cl cl hco3 0 25 with average tds 267 5 mg l represents that the weathering of aquifer sediments or sediment water interaction primarily controls the major ion chemistry particularly f concentration of groundwater in this region this idea is further strengthened by the relationship between na k and total cations tz and na cl molar ratio moreover groundwater is under saturated with respect to amorphous silica average sisio2 a 0 64 while all water samples are either saturated or super saturated with respect to quartz average siquartz 0 66 mineral stability diagrams for the nao h2o al2o3 sio2 and k2o h2o al2o3 sio2 systems suggest that most stable silicate mineral phase in the aquifers is kaolinite suggesting that semi arid nature of the study area and intermediated flow condition may give rise to kaolinite sample falling in kaolinite stability field indicates that the hydrolysis of some alumino silicate minerals such as albite and biotite is responsible for the formation of hco3 na and k which are dominant in the groundwaters this ultimately leads to higher rate of ion exchange of f from biotite and muscovite rich aquifer matrix to groundwater of the study area

assessing the impact of natural and anthropogenic activities on groundwater quality in coastal alluvial aquifers of the lower liaohe river plain ne china abstract the lower liaohe river plain lrp is an economically and ecologically important area situated on an alluvial plain where anthropogenic activities are very intensive field investigations were conducted in the lrp and 15 water quality parameters surveyed at 216 wells during september and october of 2009 and 2010 these showed significant variation in the hydrochemistry of groundwater throughout the plain a piper plot was used to identify the major geochemical processes occurring in the entire plain principal components analysis pca was used to identify various underlying natural and anthropogenic processes that created these distinct water types the stuyfzand classification was used to subdivide and interpret the complex groundwater hydrochemistry of the liaohe river delta five principal components pcs were extracted in terms of pca which can be invoked to explain 82 of the total variance in water quality parameters the pca results can be categorized by five major factors 1 holocene transgression and mixing 2 surface water infiltration 3 multi factor processes 4 rainfall and agricultural fertilizer contamination and 5 geogenic f enrichment this study demonstrates that the great variation of groundwater hydrochemistry in the lrp should be attributed to both natural and anthropogenic processes

hydrochemical borehole logs characterizing fluoride contamination in a crystalline aquifer maheshwaram india summary hydrochemical borehole loggings with a submersible idronaut ocean seven 302 multiparameter probe equipped of f and no 3 ion selective electrodes in combination with ec ph and dissolved oxygen were applied for characterizing fluoride f contamination in a crystalline hard rock aquifer of a small indian agricultural watershed where groundwater is intensively abstracted for rice irrigation a high accuracy of f concentrations determined in situ shown by comparing with laboratory analyses was obtained through using conductivity logs for ionic strength consideration large variations in chemical composition and particularly of f concentration were observed inside boreholes though restricted to the weathered fractured layer down to 30 35 m depth this conforms to the hydrogeological model of a crystalline aquifer where most groundwater flow occurs in the shallow part of the fractured zone the general trend of increasing f content with depth results from f accumulation through water rock interaction but the shape of the f profile depends on the connectivity of the fracture network close to the borehole the concentrations seen within the water table fluctuation zone locally suggest f input from fertilizers in groundwater in addition to the earlier demonstrated role of evaporation from irrigation return flow it is also likely that locally the deepening of boreholes has contributed to increasing the population s vulnerability by tapping f enriched groundwater at depth

source and short distance propagation of the july 9 1956 southern aegean tsunami abstract properties of the tsunamigenic source as well as the attenuation of the tsunami intensities of the large tsunami of july 9 1956 in the southern aegean are investigated this tsunami was generated by a shallow earthquake with a surface wave magnitude of 7 5 which was caused by a normal fault fault plane solution isoseismal lines and bathymetric information indicate that the tsunamigenic source had an elliptical shape with the large axis equal to 110 km and oriented in an ene wsw direction this is also the strike of the normal fault which produced the earthquake and it is probable that the southern block was downthrown linear relations between a the tsunami intensity and the epicentral distance for distances up to 330 km b the observed tsunami height and the epicentral distance and c the tsunami height and intensity have been determined this information concerning the source parameters of tsunamis and the attenuation of the tsunami intensity and tsunami height with distance are of great importance for determining the tsunami hazard in this area

volcanic ash leachates a review and recommendations for sampling methods tephra in plumes can scavenge and thereby rapidly deposit volatiles including sulphur halogen and metal species these may then be leached e g by rainfall potentially releasing heavy loadings to soils and water bodies several eruptions have resulted in contamination of pasture sometimes with serious impacts on livestock water quality has also been an issue in some areas affected by tephra fall this work synthesises the literature on volcanic ash leachates and considers the controls on volatile adsorption general trends emerge for basaltic intermediate and silicic tephra as well as for variable particle size and transport distance the applications of ash leachate data to plume gas geochemistry calculation of volatile budgets and environmental impact assessment are evaluated comparisons for different eruptions are hampered by disparities in leachate analysis techniques a standardised methodology is therefore proposed to facilitate future health impact assessment and volcanological interpretation of results from different sites

fluoride hydrogeochemistry and bioavailability in groundwater and soil of an endemic fluorosis belt central iran 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

factors controlling fluoride contents of groundwater in north central and northwestern sri lanka chemical characterization has been made of groundwater bodies at 294 locations in four village districts in north central and northwestern sri lanka with special focus on fluorine contamination high fluoride contents in groundwater are becoming a major problem in the dry zone of sri lanka and dental fluorosis and renal failures are widespread field measurements of temperature ph and electrical conductivity were made during sampling chemical analyses of the water samples were later made using atomic absorption spectroscopy spectrophotometry and titration fluoride concentrations in the study area vary from 0 01 to 4 34 mg l and depend on ph and the concentrations of na ca and hco3 basement rocks including hornblende biotite gneiss biotite gneiss and granitic gneiss seem to have contributed to the anomalous concentrations of fluoride in the groundwater longer residence time in aquifers within fractured crystalline bedrocks may enhance fluoride levels in the groundwater in these areas in addition elevated fluoride concentrations in shallow groundwater in intensive agricultural areas appear to be related to the leaching of fluoride from soils due to successive irrigation

geochemical control on spatial variability of fluoride concentrations in groundwater from rural areas of gujrat in punjab pakistan spatial variability and geochemical factors controlling fluoride f concentrations were evaluated in five villages of subdistrict gujrat in pakistan groundwater samples n 70 were collected along the river chenab and examined for f concentrations the average f concentrations in groundwater of village chhani nikoani 1 8 mg l and dhool khurd 2 2 mg l were crossing the world health organization who permissible limit of 1 5 mg l while village kalra khasa ghazi chak and kula chor were below the who guidelines about 64 of the samples contain fluoride concentrations that exceed the 1 5 mg l drinking water standard set by who spatially f concentrations in groundwater increased as moving away from the river chenab because more residence time for water rock interaction was available high f concentrations were associated with high electric conductivity ec total dissolved solids tds ph and na values the overall groundwater quality is controlled by silicate mineral weathering and less by evaporation fluoride originates from anion exchange oh for f on clays and weathered micas under high ph conditions high fluoride levels are associated with nacl and nahco3 type water produced by calcite precipitation and or base ion exchange the groundwater with higher fluoride concentrations is accompanied by lower ca 2 levels this study enhances our understanding on geochemical behavior of f and highlights the importance of spatial variability on f release in aquifers of punjab in pakistan as well as in other countries of asia region

controls on the genesis of some high fluoride groundwaters in india india has an increasing incidence of fluorosis dental and skeletal with some 62 million people at risk high fluoride groundwaters are present especially in the hard rock areas south of the ganges valley and in the arid north western part of the country the phenomenon is related to groundwater with residual alkalinity ca2 hco3 fluoride concentrations are governed by adsorption equilibria and by fluorite solubility evapotranspiration leads to a precipitation of calcite a lowering of ca activity and increase in na ca ratios and this allows an increase in f levels in southern india mg seems to be controlled by dolomite while sepiolite and palygorskite are mg sinks in rajasthan but may then release f under alkaline conditions the latter two minerals are probably also important sources and sinks for f in the hydroxy positions the increase in the extent of sodic soils as a result of irrigation is a contributing factor to the increasing incidence of fluorosis remedial measures including addition of gypsum and rainwater harvesting are needed even in areas where the sodicity does not cause structural problems in the soil

sources distributions of fluoride in waters and its influencing factors from an endemic fluorosis region in central guizhou china the use of high fluoride content coal caused the severe coal burning endemic fluorosis in zhijin county guizhou province china the long term mine exploitation in this region is as an important source of acid mine drainage amd and leads to the release of potential fluoride f into the surrounding waters aiming to investigate the source hydrogeochemical characteristics and influencing factors of fluoride in waters of this area a hydrogeological and geochemical research has been conducted in this study samples of various types of waters were collected and analyzed for major cations major anions and tfe al selected coal and gangue samples were analyzed for fluoride contents the f concentration in amd or amd affected waters ranged from 0 27 to 4 94 mg l and f was mainly enriched in na so4 and mg so4 waters but a relatively low f concentration was found in the ca so4 water the f concentration in the ca hco3 water without being affected by amd ranged from 0 01 to 0 20 mg l the elevated f contents were found in the amd which is mainly influenced by the local coal mining activities and it is resulted from the dissolution of fluoride bearing minerals in coal bearing clastic rocks as well as the low ph values high al and fe concentrations high total dissolved solids and high al f ratio of the amd in addition the dissolution precipitation of carbonate rocks and special hydrogeological conditions determined the f concentration in surface water meanwhile the climate is also an influencing factor that cannot be ignored to affect the f concentrations of surface water and groundwater

genesis and geochemistry of high fluoride bearing groundwater from a semi arid terrain of nw india occurrence of fluoride in natural water resources and the associated health hazards have been reported from many parts of india during the last decade with the objective of organizing a systematic scientific programme to understand the geochemical behaviour of fluoride in natural water resources in relation to the local hydrogeological climatic conditions and agricultural use a typical semi arid terrain in the northwestern part of india was chosen for detailed study the present work is an attempt to study the fluoride contamination in groundwater in parts of jaipur district rajasthan state and to assess the origin and genesis of fluoride in groundwater the area falling under the semi arid tract of central rajasthan is geologically occupied by alluvial formations and precambrian rocks gneisses and schists where groundwater occurs under unconfined to semi confined conditions a total of 66 groundwater samples was collected during the pre monsoon period and analysed which gave a concentration of fluoride in water in the range of 0 35 to 9 3 mg l with 62 of the samples in excess of permissible limit of 1 5 mg l as compared to alluvial formations fluoride enrichment in groundwater is higher in hard rock areas the samples collected from the granite gneissic terrain show higher values when compared to those in the schist the groundwater of the shallow aquifers soil clay complex weathered zone has a higher concentration of fluoride than the deep fractured hard rock aquifer does the possible sources of fluoride are chemical weathering and leaching of fluorine bearing minerals present in hard rocks and alluvial formations under the alkaline environment in arid to semi arid conditions high ph as well as alkalinity and low levels of ca mg and total hardness suggest favourable chemical conditions for the fluoride dissolution process a higher rate of evapotranspiration intensive and long term irrigation and heavy use of fertilizers are the supplementary factors that further increase the fluoride content in the groundwater a groundwater management programme is suggested

hydrochemical characteristics of aquifers near sutherland in the western karoo south africa the western karoo depends entirely on groundwater for domestic and agricultural use an understanding of the chemical evolution of the groundwater provides insight into the interaction of water with the environment and contributes to better resource management descriptive statistics correlation matrices and factor analysis together with stable isotope data were used to gain an understanding of the hydrochemical processes of the groundwaters in the fractured rocks around sutherland in the western karoo the main processes influencing the groundwater chemistry are salinisation mineral precipitation and dissolution cation exchange and human activity the stable isotope data indicate that the infiltration of evaporated water is partly responsible for the occurrence of saline subsurface waters the ionic oxygen and hydrogen stable isotope composition of the groundwaters suggests that the effects of localised topography are one of the overriding factors controlling the groundwater chemistry in higher lying areas ca hco3 2 type waters are prevalent while in topographical flat areas nacl type waters dominate in areas where water collects close to or at the surface saline soils are formed from these areas salts are leached to the subsurface during significant recharge periods these findings are important in that they contribute to the identification of suitable locations for developing groundwater resources that could yield a relatively better quality water q 2001 elsevier science b v all rights reserved

fluoride dynamics in the granitic aquifer of the wailapally watershed nalgonda district india high concentrations of fluoride up to 7 6 mg l are a recognized feature of the wailapally granitic aquifer of nalgonda district andhra pradesh india the basement rocks provide abundant sources of f in the form of amphibole biotite fluorite and apatite the whole rock concentrations of f in the aquifer are in the range 240 990 mg kg calcretes from the shallow weathered horizons also contain comparably high concentrations of f 635 950 mg kg the concentrations of water soluble f in the granitic rocks and the calcretes are usually low 1 of the total or less but broadly correlate with the concentrations observed in groundwaters in the local vicinity the water soluble fraction of fluoride is relatively high in weathered calcretes compared to fresh calcretes groundwater major ion composition shows a well defined trend with flow downgradient in the wailapally aquifer from na ca hco3 dominated waters in the recharge area at the upper part of the catchment through to na mg hco3 and ultimately to na hco3 and na hco3 cl types in the discharge area in the lowest part the evolution occurs over a reach spanning some 17 km groundwater chemistry evolves by silicate weathering reactions although groundwaters rapidly reach equilibrium with carbonate minerals favouring precipitation of calcite and ultimately dolomite in the lower parts of the watershed this precipitation is also aided by evapotranspiration decreasing ca activity downgradient leads to a dominance of fluorite undersaturated conditions and consequently to mobilisation of f despite the clear downgradient evolution of major ion chemistry concentrations of f remain relatively uniform in the fluorite undersaturated groundwaters most being in the range 3 0 7 6 mg l the rather narrow range is attributed to a mechanism of co precipitation with and or adsorption to calcrete in the lower sections of the aquifer the model may find application in other high f groundwaters from granitic aquifers of semi arid regions

oxygen isotope mapping of the archean sturgeon lake caldera complex and vms related hydrothermal system northwestern ontario canada the hydrothermal and magmatic evolution of the sturgeon lake caldera complex is graphically documented by a regional scale 525 km2 analysis of oxygen isotopes spatial variations in whole rock oxygen isotope compositions provide a thermal map of the cumulative effects of multiple stages of hydrothermal metasomatism before during and after volcanogenic massive sulfide vms mineralization there is a progressive upward increase in 18o from less than 2 to greater than 15 through a 5 km thick section above the biedelman bay subvolcanic intrusive complex this isotopic trend makes it clear that at least the earlier phases of this intrusive complex were coeval with the overlying vms hosting cauldron succession and provided thermal energy to drive a convective hydrothermal circulation system the sharp contrast in 18o values between late stage phases of the biedelman bay intrusion and immediate hanging wall strata indicates that the main phase of vms related hydrothermal activity took place before late stage resurgence in the cauldron related magmatic activity mineralogical and isotopic evidence indicates the presence of both syn and postmineralization hydrothermal activity defined by the presence of widespread semiconformable and more restricted discordant alteration zones that affect the pre and syncauldron strata the semiconformable alteration zones formed during early stages of hydrothermal circulation and are defined by widespread silicification and carbonatization in association with relatively high 18o values the discordant alteration assemblages containing al silicate minerals with chloritoid and or fe rich carbonate or chlorite centered on synvolcanic faults represent restricted zones of both seawater inflow and hydrothermal fluid upflow a rapid increase in 18o values 7 9 over a short distance 200 m suggests marked cooling of hydrothermal fluid from 350 c to less than 130 c either just before or during discharge onto the seafloor late emplacement of diorite sills and a dacite dome disrupted the isotopic imprint of cauldron stage hydrothermal activity the abrupt lowering of 18o values at the transition from explosive to passive volcanism andesite flows and dacite domes indicates postcauldron emergence subsequently thrust faulting disrupted the older synvolcanic hydrothermal isotopic patterns

fluoride occurrence and mobilization in geo environment of semi arid granite watershed in southern peninsular india plausible forms of fluoride f responsible for the persistence of fluoride toxicity in ground water of a granitic terrain of semi arid region which is the main source of drinking water have been studied the study area in anantapur district of andhra pradesh india is one of the chronic regions with excess fluoride in groundwater and the region is under transformation into aridity due to poor rainfall and over exploitation of groundwater geochemical analysis of soil groundwater and rock samples of the study area revealed the presence of other toxic elements also in addition to fluoride which need to be addressed in drinking water sector in near future soil fluoride leaching experiments demonstrated the probable mode of mobilization of f into the groundwater through natural recharge process during monsoon analysis of saturation indices indicates that the fluorite solubility alone is not attributable to the high fluoride content in groundwater the groundwater flow controls fluoride mobilization in the study area as it is evidenced through fluoride concentration and electrical conductivity increase from catchment to downstream region creation of lesser fluoride groundwater sources through rainwater harvesting and artificial recharge of groundwater in catchment areas is suggested as a long term sustainable safe drinking water strategy