geochemistry origin and recharge mechanisms of groundwaters from the garoua sandstone aquifer northen cameroon this paper presents results of the geochemical and isotopic studies on groundwater samples from the garoua sandstone basin in northern cameroon chemical and environmental isotope data are presented and discussed in terms of the origin of dissolved species and of groundwater all of the investigated groundwaters are categorized into two chemical types low mineralized and acidic waters of ca na hco3 type and relatively high mineralized waters of na hco3 type with relatively high ph between 7 40 and 8 22 interpretation of chemical data based upon both thermodynamic calculations and stability diagrams suggests that the chemical evolution of groundwater is primarily controlled by water rock interactions involving 1 acidic weathering of aluminosilicates 2 dissolution of secondary carbonate minerals and 3 cation exchange of na for ca2 however the original composition of groundwater may have been modified by further secondary processes such as mixing of chemically different water masses and anthropogenic no 3 pollution tritium contents in the considered groundwaters are very heterogeneous suggesting differences in the water turnover time or in the recharge conditions or both on the basis of the geographical distribution of 3h contents a hydrogeological relation between river and the groundwater systems has been proposed for the study site interpretation of both 18o and 2h as well as 3h suggests that the recharge of the investigated groundwaters may result from three major mechanisms 1 direct infiltration of local precipitation 2 lateral inflow of river waters 3 probably upward leakage of old groundwaters

surface water and groundwater contaminations and the resultant hydrochemical evolution in the yongxiu area west of poyang lake china major ion and stable hydrogen and oxygen isotopic compositions were employed in this study of surface water and groundwater contaminations and their impacts on intrinsic hydrochemical evolution in the yongxiu area west of poyang lake south china a total of 36 samples were collected from surface water and groundwater in the study area where water pollution risk is high due to the fertilizer use for farmland and the waste drainage from a nearby silicon industry site the results show that the surface water bodies have been badly polluted and are characterized by low ph values minimum 2 85 and high concentrations of chemical compounds such as cl na nh4 n no3 n and tds groundwater has also been polluted with the similar specific contaminates as both surface water and groundwater may have similar contamination sources and groundwater is recharged from the precipitation infiltration and surface water leakage as indicated by oxygen 18 and deuterium compositions due to the thin unsaturated zone in the area the acidification and the intrusion of contamination further lead to hydrogeochemical reactions and changed hydrochemical type of groundwater from ca mg hco3 to ca mg na cl the data evaluation methods and results of this study could be useful to the water sustainable usage management in this area and other environmental vulnerable areas

geochemical and statistical evaluation of groundwater in imphal and thoubal district of manipur india abstract in order to identify the hydrogeochemical process controlling the quality of groundwater an extensive study was carried out in imphal and thoubal district of manipur india the objectives of the studies were to delineate the spatial and temporal variability in groundwater quality and understand its suitability for human uses in the study area groundwater samples from 45 location have been collected during the pre monsoon monsoon and post monsoon seasons and analyzed for the major ions such as ca2 mg2 na k hco 3 cl so 4 2 no 3 po 4 3 f fe and silica the water quality of both districts was good for domestic and agricultural uses except for few samples these saline samples were localized and were due to the inherent lithology of the study area three major hydrochemical facies ca hco3 type mixed ca na hco3 and ca mg cl types in imphal district and ca hco3 mixed ca mg cl and ca cl type in thoubal district were identified the mineral stability diagrams indicated that the groundwater is in equilibrium with kaolinite and ca montmorillonite whereas gibbs plot showed that the chemical composition of ground water in both districts is controlled by the natural weathering processes irrespective of seasons among the chemical weathering processes silicate weathering was dominant the results were supported by wilcox plot and ussl diagrams the study reflected the overall suitability of groundwater for anthropogenic use

polarization tomography for p wave velocity structure in southern california we develop a tomographic inversion method that uses teleseismic p wave polarization data to obtain velocity structure polarization inversion has some intrinsic advantages over travel time inversion it is not influenced by source location and origin time errors it is not sensitive to deep mantle velocity structure and can be used iteratively to improve the tomographic result polarization inversion is more sensitive to near station velocity structure and to velocity gradient and is complementary to travel time inversion in this sense the method is applied to california institute of technology u s geological servey southern california array data the result is generally consistent with previous work and also reveals that the high velocity feature beneath the transverse ranges is bounded between 40 and 200 km depths and possibly has a second small piece at about 300 km depth the slow velocity anomaly under the salt on trough is limited to shallow depths less than about 60 km

appraisal and evolution of hydrochemical processes from proximity basalt and granite areas of deccan volcanic province dvp in india summary this paper deals with a systematic hydrochemical study carried out at proximity basalt and granite areas of deccan volcanic province dvp in india to assess groundwater quality and evaluate the hydrochemical processes a total of 40 groundwater samples were collected equally from these areas and analyzed results showed that the groundwaters rich in alkaline earth in the basalt and alkali rich element in the granite the dominancy of cations was observed as ca 2 mg 2 na k in the basalt and na mg 2 k ca 2 in the granite whereas anions as hco 3 cl so 4 2 and cl hco 3 so 4 2 respectively hydrochemical processes were identified with the helps of ion exchange carbonate weathering and dissolution multiple ionic ratios and silicate weathering which shown the predominance of carbonate dolomite calcite and silicate anorthite weathering in basalt but in granite silicate alkali feldspar weathering was dominated factor analysis also showed that there were multiple processes acting on groundwaters were separated from the main cluster salinity sodium absorption ratio sar soluble sodium percentage ssp residual sodium carbonate rsc kelley s ratio kr and permeability index pi in well samples showed that groundwater in basalt was more suitable for irrigation purposes further a digital elevation model dem was generated using global mapper 8 0 version software which aided to decipher the thickness of basalt trap and vertical transition zone of basaltic trap and granitic basement aquifer at this dvp comprising with the well depths and groundwater chemistry

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

hydrochemical processes governing groundwater quality of sedimentary aquifers in central saudi arabia and its environmental implications the present study deals with the interpretation of the major processes governing the groundwater chemistry in parts of qassim and riyadh province of saudi arabia the study area that is dominated by agricultural activities is represented by a multi layered aquifer system with sedimentary formations ranging from cambrian to the quaternary present as outcrops groundwater samples from 97 agricultural bore wells in the area were collected and analyzed for 16 physio chemical parameters the evaluation of the main hydrochemical processes affecting the groundwater quality was carried out by interpreting the ionic relationships and hydrochemical facies analysis the interpretation pointed toward evaporation gypsum dissolution and ion exchange as main factors controlling the major ion groundwater chemistry the piper plot showed so4 cl type of groundwater with majority of the samples falling in the zone of permanent hardness due to the formation of non carbonate salts principal component analysis that helps to understand the underlying natural and anthropogenic factors controlling the groundwater chemistry in an area was used in the present study based on which four principal components pcs were extracted the first pc as expected was dominated by the major ions and was attributed to natural processes whereas the extracted components mainly heavy metals in pc 2 3 and 4 pointed toward anthropogenic activities playing an active role in affecting the trace element hydrochemistry

frequency dependent scattering observed in p and surface wave arrivals from south india anomalies in polarization angles of teleseismic waves have been used to understand effect of scattered arrivals from subsurface heterogeneities seismological data recorded in southern india show polarization anomalies up to 5 for several stations these anomalies are most pronounced for earthquakes from western and southern azimuths furthermore stations located near the boundary of dharwar craton and southern granulites are more affected by scattered waves considering that many of the nearby stations show similar patterns of polarization anomalies it is likely that the source of scattered energy is located at shallower depths the non stationary nature of seismic arrivals warrants determination of frequency dependent polarization result obtained using multi taper spectral analysis method indicates that data are contaminated at frequencies greater than 2 hz for most of the stations furthermore surface wave records also indicate off azimuth arrivals and quasi love waves indicating heterogeneities or anisotropy in the subsurface these small scale heterogeneities that may be located in crust may be important for studies using converted phases and ground motion prediction studies

an appraisal of groundwater quality in seymour and blaine aquifers in a major agro ecological region in texas usa aquifer based groundwater quality assessment offers critical insight into the major hydrochemical processes and aids in making groundwater resources management decisions the texas rolling plains trp spanning over 22 counties is a major agro ecological region in texas from where highest groundwater nitrate no3 levels in the state have been reported in this study we present a comparative assessment of major hydrochemical facies pertaining to no3 contamination and a host of species such as sulfate so42 chloride cl and total dissolved solids tds in different water use classes in the seymour and blaine aquifers underlying the trp aquifer stratified groundwater quality information from 1990 to 2010 was obtained from the texas water development board and aggregated over decadal scale high groundwater salinization was found in the municipal water use class in the blaine aquifer with about 100 87 and 50 of observations exceeding the secondary maximum contaminant level for tds so42 and cl respectively in the 2000s 2000 2010 the no3 contamination was more alarming in the seymour aquifer with 82 and 61 of observations respectively exceeding the maximum contaminant level mcl in the irrigation and municipal water use classes in the 2000s salinization was more influenced by so42 and cl in the blaine aquifer and by no3 in the seymour aquifer high no3 mcl observations in the seymour aquifer occurred in the ca hco3 and ca mg hco3 facies the domains of fresh water recharge and anthropogenic influences e g agricultural activities waste disposal high so42 cl and tds observations in the blaine aquifer dominated the ca cl na cl and mixed ca mg so4 cl facies indicating evaporite dissolution mixing and solute exchange and lack of fresh recharge

use of receiver functions in wide angle controlled source crustal data sets summary first arrival waveforms remain underutilized in crustal refraction reflection seismology by mostly reducing them to traveltime picks however as in earthquake seismology the waveforms also contain important information about shallow near receiver structures we illustrate the use of three component waveform analysis on the records from the accrete wide angle data set se alaska and british columbia 1994 apply the receiver function rf methodology to the codas of p wave arrivals and draw two important conclusions first the p wave polarization azimuths are found to be controlled by the near receiver structures and virtually unrelated to the source receiver backazimuths from which they deviate by up to 40 this observation might be important for studies of anisotropy and also for earthquake rf studies second after correcting for the polarization azimuths clear p s mode conversions are reliably detected within 80 400 ms following the primary arrivals the conversions are interpreted as originating at the base of the sedimentary cover of the fjord channel in most cases imaging of the basement requires only several records however notable exceptions are also found and interpreted as caused by multipathing localized scattering and onsets of crustal and moho reflections the accrete example shows that rf methodology could be useful for constraining sediment thickness and deriving p and s wave receiver statics in land refraction surveys where collocated reflection profiles are not available in addition rfs from repeatable controlled sources could be useful for testing and calibration of rf techniques

p wave array polarization analysis and effective anisotropy of the brittle crust summary p wave polarization constrains local anisotropy in the vicinity of the receivers using three component and array data from the regional geress array in south eastern germany we measure polarization a and propagation vectors s for p phases of 120 events angular deviations a s between these normalized vectors often approach 10 rendering them easily measurable the effect of anisotropy can be distinguished from remote effects since all remote effects such as source mislocation distant lateral heterogeneity or distant anisotropy affect polarization and propagation vectors simultaneously averaging removes sensitivity to near receiver heterogeneity and local anisotropy is left as the sole cause of the effects in a s this method hence gives local effective anisotropy in the near receiver crust averaging over a depth interval of a wavelength 6 km we resolve strike and dip of the symmetry plane and also two dimensionless numbers and which give constraints on four of the elastic parameters the optimum model variance reduction 44 per cent has symmetry plane orientation of strike 113 and dip 49 to the north which corresponds closely to the consistently observed gneiss foliation direction in the area 120 50 60 comparing and with predictions from different physical models we find that the data are fit by a gneiss model assuming that the anisotropy is dominated by the mica if 3 8 per cent of the mica are well aligned this suggests that anisotropy in the region studied is dominated by the effect of local foliation rather than the regional stress field

hydrogeology and geochemistry of the ogallala aquifer southern high plains the ogallala aquifer which underlies the southern high plains consists of saturated sediments of the ogallala formation neogene that are deposited mainly as a set of humid type alluvial fans derived from the rocky mountains the ogallala aquifer the main source of water for the high plains of texas and new mexico has been severely depleted by extensive pumpage the hydrology and geochemistry of the aquifer are controlled by the surface topography of the underlying formations and by the thickness and permeability of the alluvial fan deposits axes of three major alluvial fans trend from northwest to southeast the fans have increased thickness and permeability compared with interfan areas flow lines follow the orientation of the alluvial fans along these major axes the saturated section is thick and the chemical composition is relatively constant ca hco3 to mixed cation hco3 water depleted in 18o d and tritium external effects on the chemical composition are less pronounced the aquifer is thinner and less permeable in areas between major fan axes and along the caprock escarpment in these areas groundwater can discharge from aquifers in the cretaceous triassic and permian formations into the ogallala formation cross formational movement of water and low permeabilities in the ogallala formation result in varying hydrochemical facies and in isotopic compositions that differ from those of the major depositional areas areas where upward cross formational flow occurs are evident by the presence of permeable contacts between the ogallala and the underlying formations water level head differences and chemical and isotopic similarities secondary factors that locally affect the chemical composition of ogallala formation groundwater include contamination from evaporating saline lakes agricultural chemicals and fertilizers and oil field brines impact of chemicals and brines may increase in the future because much of these contaminants may still be moving through the unsaturated zone toward the water table

the impact of hydrogeological settings on geochemical evolution of groundwater in karstified limestone aquifer basin in northwest sri lanka the geochemical and isotope analysis of groundwaters from the murunkan basin in north western sri lanka was carried out to examine their evolution and recharge sources in order to shed light to enhance the current knowledge of the hydro geochemical processes in a karst geological setting a total of 40 water samples from ground and surface water bodies were collected from the miocene limestone terrain nearby metamorphic and from unconsolidated quaternary terrains for major anions cations and environmental isotopes ratios 18ovsmow and 2hvsmow distinct geochemical differences were noted between waters from limestone terrain and nearby metamorphic terrain indicating the modification of groundwater flow paths bicarbonate chloride rich water is dominated in the limestone terrain in which water flows through a less mineralized aquifer system and is modified by the sea water intrusion groundwater in the metamorphic terrain is modified by dissolving of ca mg rich mineral phases and subsequent ion exchange processes the environmental isotopes of groundwater from both limestone and metamorphic terrains vary from 0 38 to 6 68 and 2 41 to 42 3 for 18ovsmow and 2hvsmow respectively however slightly enriched isotope signatures and low d excess values from limestone terrain indicate an excessive evaporation compared to that of the metamorphic terrain where rapid infiltration occurs through the overlying highly permeable grumusols soil layers

hydrogeochemical characterization and groundwater quality assessment in the intensive agricultural zone of the upper cheliff plain algeria the alluvial aquifer of upper cheliff northern algeria is known for its intensive agricultural activities which is based especially on groundwater exploitation this aquifer is now facing a dual problem of quantity and quality with a decrease in the groundwater levels and an increase in mineralization twenty monitoring samples were collected and analyzed for major ion during the dry season 2014 in the present study we try to characterize the hydrogeochemical processes and to assess the impact of natural and anthropogenic conditions on groundwater mineralization the analytical results of the dry season 2014 show a groundwater quality slightly alkaline ph 7 and indicate that the majority of samples have a values exceeding the limits of potability fixed by who in 2008 due to the various sources of anthropogenic pollution the piper diagram shows the dominance of groundwater types ca cl the mixed facies cl so4 ca mg and ca hco3 the mineralization process in this aquifer is mainly controlled by the lithology of the aquifer exchange water rock and weathering of calcareous crust dissolution in the unsaturated zone by anthropogenic factors discharges of untreated urban sewage intensive use of fertilizers in agriculture and the use of domestic septic tanks by rural inhabitants and also by geoclimatic conditions semiarid climate suitability of groundwater shows more than 80 of samples have very poor quality for drinking and more than 20 of samples indicate a quality unsuitable for irrigation

prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic considerations abstract the exposed crust consists mainly of plagioclase 35 quartz 20 k feldspar 11 volcanic glass 12 biotite 8 and muscovite 5 quartz is a resistate thus feldspars and glass represent approximately 75 percent of the labile minerals the weathering characteristics of these constituents are summarized in the context of thermodynamic mass balance and kinetic considerations experimentally determined release rate constants were used to predict the proportions of ca na and k released by feldspars of plutonic rocks granites to gabbros to weathering solutions the chemical weathering trends of the weathered residues calculated from the kinetic data conform closely to the initial trends observed in some recent weathering profiles demonstrating the accuracy of the predictions since the weathering of feldspars is controlled by processes that should not change through geological time the relative release rates of ca na and k from the feldspars of granitic rocks can be calculated for future and past episodes of continental weathering experimentally determined release rate constants are not available for a wide range of volcanic glass compositions but the limited data indicate that compositional trends are predictable in weathering profiles developed on volcanic rocks the kinetic data available for rhyolitic glasses accurately predict the initial weathering trends observed in a recent rhyolite weathering profile

seismic evidence of crustal heterogeneity beneath the northwestern deccan volcanic province of india from joint inversion of rayleigh wave dispersion measurements and p receiver functions abstract the northwestern deccan volcanic province nwdvp of india encompassing the saurashtra peninsula and the adjoining gulf of cambay is investigated through joint inversion of surface wave dispersion measurements and teleseismic p receiver functions to estimate the crustal and shallow upper mantle shear wave velocity vs structure the mw 7 7 bhuj earthquake and the post bhuj regional events recorded during the period 2001 2010 at 7 stations along 37 source receiver paths were used along with 35 teleseismic events a joint curve fitting inversion technique is applied to obtain a best fit for the fundamental mode rayleigh wave group velocity dispersion curves for time periods 5 50 s and high quality crustal p wave receiver functions obtained at each station significant crustal heterogeneity is observed within the study region with the average crustal vs ranging from 3 5 km s to 3 8 km s with the paths cutting across the gulf of cambay exhibiting large reduction in shear wave velocities utilizing the average crustal vs 3 66 km s estimated for saurashtra together with the average crustal p wave velocity vp 6 54 km s derived independently through deep seismic sounding studies yields a bulk vp vs ratio of 1 786 or an equivalent crustal poisson s ratio of 0 271 a major contribution to the high poisson s ratio comes from the 12 to 16 km thick lower crustal layers with shear velocities ranging from 3 8 km s to 4 19 km s suggesting widespread magmatic underplating due to emplacement of mafic cumulates in the lower crust the shallow uppermost mantle shear velocities are in the range 4 2 4 5 km s averaging 4 36 km s which is less than that observed for the indian shield indicating the effects of residual thermal anomaly the variation in the crustal vs high poisson s ratios and low upper mantle shear velocities reflect the thermal and compositional effects of the deccan volcanism which are manifested in terms of pervasive presence of mafic dykes volcano plutonic complexes lower crustal mafic cumulates and possible partial melt due to elevated geotherms the significant crustal alterations are possibly a result of weakening of the lithosphere by a mantle thermal source leading to a thin and weak lithosphere which facilitated the deccan volcanism through the rift zones of northwestern india

solute and isotopic geochemistry and ground water flow in the central wasatch range utah ground water flow systems in the rugged central wasatch range utah were investigated by solute and isotopic methods six types of ground water systems were identified on the basis of rock type and structure the systems are broadly grouped into four categories 1 granitic systems 2 non granitic systems a unconsolidated alluvial systems b consolidated sedimentary rock systems and c fault controlled systems 3 thermal systems 4 mine drainage systems these ground water systems have distinctive solute and isotopic chemistries based on an analysis of 3h and 14c data all of the ground waters have a component of post 1952 recharge water and most of the ground waters are composed almost entirely of post 1952 recharge water a few of the ground water systems contain some water which is hundreds to perhaps thousands of years old the 18o and 2h data plot on a local meteoric water line and none of the data exhibit a positive 18o shift the absence of a positive 18o shift suggests maximum aquifer temperatures are approximately 100 c granitic terrains are dominated by fracture controlled local ground water flow systems which respond rapidly to recharge events the granitic ground water systems have estimated maximum circulation depths of about 160 m below land surface all the alluvial most of the consolidated sedimentary bedrock and some of the fault controlled ground water systems are shallow circulating local flow systems with short travel times ground water circulation of most of the local flow systems is within 200 m of land surface and is bedding plane controlled some of the consolidated bedrock and many of the fault controlled ground water systems are of the intermediate type and have circulation depths to 500 m four thermal ground water systems have been identified the thermal systems are heated by the geothermal gradient and have not circulated deeper than 2 2 5 km the thermal systems are of the intermediate and regional type the solute chemistry of most of the non granitic ground waters may be attributed to the dissolution of carbonate minerals and minor amounts of gypsum contributions of external co2 g to some of the thermal systems from either metamorphic or silicate hydrolysis processes is suspected

identification of groundwater contamination zones and its sources by using multivariate statistical approach in thirumanimuthar sub basin tamil nadu india hydrogeochemical studies have been made in the study area by using multivariate statistical analysis which is mainly helpful for interpretation of complex data matrices to better understand the geochemical evolution of the area and it allows identifying the possible factors sources that influence water systems the spatial distribu tion of electrical conductivity reveals that an untreated industrial effluents landfill and anthropogenic activities affecting their groundwater quality in its vicinity and the surrounding area the dominance of ions was in the order of na ca 2 mg 2 k cl hco3 so4 2 no3 and ca 2 mg 2 na k hco3 cl no3 so4 2 during pre monsoon prm and post monsoon pom respectively the statistical results reveals that the groundwater chemistry gets altered by silicate weathering ion exchange leaching anthropogenic input from agricultural return flow and longer distance of migrating groundwater the hydrogeochemical regimes are distributed along the upstream side northwestern western and eastern parts of the study area the study highlights the descriptive capabilities of conventional and multivariate techniques as effective tools in groundwater evaluation

geochemical modelling ionic ratio and gis based mapping of groundwater salinity and assessment of governing processes in northern gujarat india in semi arid arid regions groundwater is the major source of irrigation drinking and industrial requirements water salinity and shortage are major problems of concern north gujarat india is one such area where highly saline groundwater is generally ascribed to rapid increase of population agriculture and industries induced decline in water table by unplanned abstraction of groundwater however no effort has been made to discriminate the natural and anthropogenic influences on groundwater salinity in this brief background the present study attempts to identify the factors and processes controlling the groundwater salinity in the area based on ionic ratios in integration with various graphical methods saturation indices and geographical information system na ca2 1 indicates the deficiency of ca2 possibly due to caco3 precipitation or ion exchange process na cl 1 and text so 4 2 text cl gg 0 05 suggest salinization is mainly due to wastewater infiltration and or due to irrigation water return flow sea water intrusion in coastal parts vertical and lateral mixing of water and anthropogenic inputs are also responsible for salinization of groundwater ussl diagram na sodium adsorption ratio residual sodium carbonate and magnesium hazard indicate unsuitability of groundwater for irrigation purposes to prevent groundwater salinization appropriate measures need to be taken to control further indiscriminate exploitation of groundwater for irrigation

origin of major dissolved ions in groundwater within the lower pra basin using groundwater geochemistry source rock deduction and stable isotopes of 2h and 18o hydrochemical and stable isotopes 18o and 2h analyses of groundwater samples were employed to establish the origin of major dissolved ions in groundwater within the lower pra basin results showed that the major processes responsible for chemical evolution of groundwater include silicate sio4 4 dissolutions ion exchange reactions sea aerosol spray and pyrite fes2 and arsenopyrite feass oxidations the groundwater is strongly acidic to neutral with ph generally range from 3 5 to 7 0 ph units and mean 5 9 0 5 approximately 89 of boreholes had ph values outside the world heath organization who guidelines for drinking water quality 2004 guideline value for drinking water due principally to natural biogeochemical processes and therefore not suitable for potable purposes electrical conductivity ec range from 57 6 to 1 201 s cm with mean 279 3 198 8 s cm total dissolved solids tds range from 32 to 661 mg l with mean 151 7 106 8 mg l with 98 6 of groundwater as fresh tds ca2 mg2 k and hco3 cl so4 2 respectively a plot of 18o against 2h showed that ground and surface waters clustered on or closely along the global meteoric water line suggesting that the waters emanated principally from meteoric source with evaporation playing an insignificant role on the infiltrating water

groundwater quality assessment and its suitability in celtikci plain burdur turkey the celtikci burdur plain is located in the southwest of turkey and is a semi closed basin groundwater is densely used as drinking irrigation and domestic water in the plain hydrogeochemical processes controlling groundwater chemistry and geochemical assessment of groundwater were investigated in the celtikci burdur turkey plain in this study groundwater samples for two seasons were analyzed and major ion chemistry of groundwater was researched to understand the groundwater geochemistry two major hydrochemical facies ca hco3 and ca mg hco3 were determined in the area various graphical plots and multivariate statistical analysis were used for identifying the occurrence of different geochemical processes in the study area weathering is one of the key geochemical processes which controlled the solute concentration in groundwater chemical indexes such as sodium adsorption ratio na residual sodium carbonate magnesium hazard and permeability index were calculated and results show that groundwater is suitable for irrigation purpose except for permeability index values concentrations of mn no3 and total hardness exceed the prescribed limits of who and are the major limiting parameters of groundwater use for potable and domestic purposes

influence of hydrogeochemical processes on temporal changes in groundwater quality in a part of nalgonda district andhra pradesh india geochemical processes that take place in the aquifer have played a major role in spatial and temporal variations of groundwater quality this study was carried out with an objective of identifying the hydrogeochemical processes that controls the groundwater quality in a weathered hard rock aquifer in a part of nalgonda district andhra pradesh india groundwater samples were collected from 45 wells once every 2 months from march 2008 to september 2009 chemical parameters of groundwater such as groundwater level ec and ph were measured insitu the major ion concentrations such as ca2 mg2 na k cl and so42 were analyzed using ion chromatograph co3 and hco3 concentration was determined by acid base titration the abundance of major cation concentration in groundwater is as na ca2 mg2 k while that of anions is hco3 so42 cl co3 ca hco3 na cl ca na hco3 and ca mg cl are the dominant groundwater types in this area relation between temporal variation in groundwater level and saturation index of minerals reveals the evaporation process the ion exchange process controls the concentration of ions such as calcium magnesium and sodium the ionic ratio of ca mg explains the contribution of calcite and dolomite to groundwater in general the geochemical processes and temporal variation of groundwater in this area are influenced by evaporation processes ion exchange and dissolution of minerals

assessment of hydrogeochemistry and contamination of varamin deep aquifer tehran province iran the present study investigates the hydrogeochemistry and contamination of varamin deep aquifer located in the southeast of tehran province iran the study also evaluates groundwater suitability for irrigation uses the hydrogeochemical study was conducted by collecting and analyzing 154 groundwater samples seasonally during 2014 based on evolutionary sequence of chebotarev the aquifer is in the stage of so4 hco3 in the north half of the plain and it has evolved into so4 cl in the south half the unusual increase in tds and cl toward the western boundaries of the aquifer indicates some anomalies these anomalies have originated from discharge of untreated wastewater of tehran city in these areas the studied aquifer contains four dominant groundwater types including na ca so4 55 na ca hco3 22 na cl 13 and ca cl 10 the spatial distributions of na cl and ca cl water types coincide with observed anomalies ionic relationships of so4 2 versus cl and na versus cl confirm that water rock interaction and anthropogenic contribution are main sources of these ions in the groundwater the main processes governing the chemistry of the groundwater are the dissolution of calcite dolomite and gypsum along the flow path and direct ion exchange reverse ion exchange controls the groundwater chemistry in the areas contaminated with untreated wastewater based on na and sar 10 3 and 27 of water samples are unsuitable for irrigation purposes respectively regarding residual sodium carbonate there is no treat for crop yields only 6 of water samples represent magnesium adsorption ratios more than 50 which are harmful and unsuitable for irrigation

an assessment of groundwater salinization in haryana state in india using hydrochemical tools in association with gis unplanned abstraction of groundwater due to various land use land cover activities and variations in monsoonal rainfall have greatly affected the availability and quality of groundwater resources in semi arid regions of india in the present study a study of the hydrogeochemical characteristics of groundwater was undertaken in the sonipat district of haryana in india together with the use of stable isotope 18o and d measurements and gis analysis a total of 53 groundwater samples were collected from seven blocks of the district and 14 water quality parameters and stable isotopes 18o and d were analysed to infer hydrogeochemical processes taking place in the area the integration of hydrochemistry with gis is very helpful to understand the factors governing in the area the majority of the samples showed na cl type of hydrochemical facies the trilinear plot for major cations and anions in groundwater indicates dominance of sodium calcium chloride and bicarbonate ions nitrate plumes in the groundwater appear to be migrating in groundwater from the central and south western parts of the area towards the urbanized areas a total of 64 of the samples exceed the maximum permissible limit of 1 5 mg l given by who for fluoride besides natural sources such as silicate and carbonate weathering ion exchange and reverse ion exchange the leaching of surficial salts and untreated industrial wastes along with unregulated abstraction are contributing to poor groundwater quality in the study area an assessment of saturation indices has shown that groundwater in the area is unsaturated with respect to anhydrite halite and gypsum suggesting significant contribution of ca2 mg2 and other ions in the groundwater a scatter plot of 18o versus cl also suggests mixing of saline water with fresh groundwater

identification and evolution of hydrogeochemical processes in the groundwater environment in an area of the palar and cheyyar river basins southern india the palar and cheyyar river basins in tamil nadu state of southern india are characterised by different geological formations and groundwater is the major source for domestic agricultural and other water related activities hydrogeochemical studies were carried out in this area with the objective of identifying the geochemical processes and their relation to groundwater quality groundwater samples were collected once a month from 43 groundwater wells in this area from january 1998 to july 1999 sampling procedures and chemical analysis were carried out as per the standard methods chemical data are used for mathematical calculations and graphical plots to understand the chemical process and its relation to the groundwater quality the chemical composition of groundwater in the central part of the study area mainly depends on the recharge from lakes and the river which is explained by a mixing mechanism in addition weathering of silicate minerals controls the concentration of major ions such as sodium calcium magnesium and potassium in the groundwater of this area further the activity ratios indicate that the groundwater is in equilibrium with kaolinite smectite and montmorrillonite the reverse ion exchange process controls the concentration of calcium magnesium and sodium in hard rock formations and dissolution of carbonate minerals and accessory minerals is the source of ca and mg in addition to cation exchange in the sedimentary formations in general the chemical composition of the groundwater in this area is influenced by rock water interaction dissolution and deposition of carbonate and silicate minerals ion exchange and surface water interactions

hydrogeochemical assessment of the upper cheliff groundwater north west algeria the quality of the upper cheliff groundwater located in north west algeria has in recent years undergone serious deterioration due to uncontrolled discharge of urban wastewaters intensive use of chemical fertilizers in agriculture as well as to overexploitation this study aims at analyzing the flow pattern of the upper cheliff groundwater determining its current hydrochemical status and understanding the mineralization processes involved in its chemical quality two piezometric and sampling campaigns were carried out in 2008 in high water april and low water october periods the major chemical ions ca2 mg2 na k cl hco3 no3 so4 2 were analyzed in all samples the piezometric data were mapped and allowed to analyze the groundwater flow conditions in particular at the boundaries of the aquifer the interpretation of hydrochemical data was made using various methods piper diagram stabler classification base exchanges index bi elements scatter diagrams saturation indices mapping and multivariate principal component analysis the results provide a better understanding of this aquifer hydrogeology and hydrochemistry several hydrochemical types chloride calcium chloride sodium and bicarbonate calcium characterize the groundwater mineralization processes and the origin of salinity are determined by the lithology of the aquifer dissolution base exchanges and by climatic evaporation and anthropogenic factors agricultural and urban wastes the groundwater in the upper cheliff is currently of poor quality this status is worrying as this groundwater is an important natural resource for the socio economic development of this region urgent measures must be taken to preserve this resource

recharge mechanisms and geochemical processes in a semi arid sedimentary basin eastern cape south africa abstract stable isotope 18 o and 2 h and geochemical signatures are used to gain some insight into recharge processes and groundwater salinization mechanisms in a semi arid rangeland catchment the 665 km 2 catchment is underlain by fractured lower beaufort sandstones and mudstones and is intruded by several dolerite dykes chloride and isotopic relationships suggest that chloride ions in ground water are of meteoric origin the hypothesized recharge and salinization mechanism is that large storm events periodically dissolve accumulated surficial meteoric salts and after a period of evaporative enrichment at or near the soil surface leach them into the ground water geochemical variations imply that spatial differences exist in recharge volumes in evaporative enrichment or in the extent of leaching of surficial salts meteoric sodium chloride contributes greater than 90 of the dissolved sodium except at low salinities where cation exchange processes yield additional sodium inputs in exchange for dissolved calcium and magnesium at high salinities this process reverses and sodium is adsorbed releasing calcium and magnesium this process accounts for up to 40 of the dissolved calcium and magnesium contributions from geochemical weathering are relatively uniform in spite of highly variable salinities which implies that residence times are also relatively uniform

assessment of hydrogeochemistry and the quality of groundwater in 24 parganas districts west bengal hydrogeochemistry of an area helps in understanding the geological processes which control the chemistry of water and play an important role in determining the suitability of groundwater for various purposes in the present study an attempt has been made to understand the geological processes controlling the quality of water in a part of north and south 24 parganas districts of west bengal 39 representative groundwater samples were collected from the study area and physico chemical parameters were analyzed for all the samples schoeller and durov diagram were used to understand the hydrochemical nature of water results obtained from water chemistry were used in the interpretation of controlling processes using different conventional graphs and determining the quality of groundwater silicate weathering and ion exchange are the dominant processes controlling the chemistry of groundwater in the study area where calcium and magnesium in the water are replaced by the sodium and potassium in the minerals from the host rock as chloro alkaline indices are negative at most of the places saturation index was calculated to understand the mineralogy of the subsurface the groundwater is oversaturated with iron containing minerals like fe oh 3 goethite and hematite while undersaturated with anhydrite and gypsum the groundwater suitability was determined by calculating water quality index for drinking purpose while sar and residual sodium carbonate indices for the agricultural purpose the groundwater in the study area is not suitable for drinking but can be used for other household use and in irrigation for agriculture

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

seasonal disparity in the co occurrence of arsenic and fluoride in the aquifers of the brahmaputra flood plains northeast india arsenic as and fluoride f in groundwater are increasing global water quality and public health concerns the present study provides a deeper understanding of the impact of seasonal change on the co occurrence of as and f as both contaminants vary with climatic patterns groundwater samples were collected in pre and post monsoon seasons n 40 in each season from the brahmaputra flood plains bfp in northeast india to study the effect of season on as and f levels weathering is a key hydrogeochemical process in the bfp and both silicate and carbonate weathering are enhanced in the post monsoon season the increase in carbonate weathering is linked to an elevation in ph during the post monsoon season a piper diagram revealed that bicarbonate type water with na k ca2 and mg2 cations is common in both seasons correlation between cl and no3 r 0 74 p 0 01 in the post monsoon indicates mobilization of anthropogenic deposits during the rainy season as was within the 10 g l 1 who limit for drinking water and f was under the 1 5 mg l 1 limit a negative correlation between oxidation reduction potential and groundwater as in both seasons r 0 26 and 0 49 respectively for pre monsoon and post monsoon p 0 05 indicates enhanced as levels due to prevailing reducing conditions reductive hydrolysis of fe hydr oxides appears to be the predominant process of as release consistent with a positive correlation between as and fe in both seasons r 0 75 and 0 73 for pre and post monsoon seasons respectively at p 0 01 principal component analysis and hierarchical cluster analysis revealed grouping of fe and as in both seasons f and sulfate were also clustered during the pre monsoon season which could be due to their similar interactions with fe hydr oxides higher as levels in the post monsoon appears driven by the influx of water into the aquifer which drives out oxygen and creates a more reducing condition suitable for reductive dissolution of fe hydr oxides an increase in ph promotes desorption of as oxyanions aso4 3 arsenate and aso3 3 arsenite from fe hydr oxide surfaces fluoride appears mainly released from f bearing minerals but fe hydr oxides can be a secondary source of f as suggested by the positive correlation between as and f in the pre monsoon season

identification of hydrogeochemical processes and pollution sources of groundwater resources in the marand plain northwest of iran the main aims of the present study are to identify the major factors affecting hydrogeochemistry of groundwater resources in the marand plain nw iran and to evaluate the potential sources of major and trace elements using multivariate statistical analysis such as hierarchical clustering analysis hca and factor analysis fa to achieve these goals groundwater samples were collected in three sampling periods in september 2013 may 2014 and september 2014 and analyzed with regard to ions e g ca2 mg2 na and k hco3 so4 2 cl f and no3 and trace metals e g cr pb cd mn fe al and as the piper diagrams show that the majority of samples belong to na cl water type and are followed by ca hco3 and mixed ca na hco3 cross plots show that weathering and dissolution of different rocks and minerals ion exchange reverse ion exchange and anthropogenic activities especially agricultural activities influence the hydrogeochemistry of the study area the results of the fa demonstrate that 6 factors with 81 7 of total variance are effective in the overall hydrogeochemistry which are attributed to geogenic and anthropogenic impacts the hca categorizes the samples into two clusters samples of cluster c1 which appear to have higher values of some trace metals like pb and as are spatially located at the eastern and central parts of the plain while samples of cluster c2 which express the salinization of the groundwater are situated mainly westward with few local exceptions

characterization and evaluation of processes governing the groundwater quality in parts of the sabarmati basin gujarat using hydrochemistry integrated with gis intense agricultural and industrial activities in any area are likely to make groundwater vulnerable with respect to its quality in one such area which is a part of sabarmati river basin of gujarat factors influencing the groundwater hydrochemistry in pre and post monsoon season were evaluated groundwater samples were collected from 5 km 5 km grids on the basis of spectral signature of vegetation and soil observed on satellite image integration of conventional graphical plots piper plot saturation index values estimated using phreeqc and gis was helpful not only to create the database for analysis of spatial variation in respective water quality parameters but also to decipher the hydrogeochemical process occurring in such a large area ussl diagram and sodium were used to characterise the suitability of groundwater for irrigation it was observed that leaching of wastes disposed from anthropogenic activities and agrichemicals is the major factor influencing the groundwater quality in addition to the natural processes such as weathering dissolution and ion exchange sea water relics are also impacting the groundwater quality control of indiscriminate and unplanned exploitation of groundwater application of fertilizers and disposal of industrial wastes in the affected areas can possibly ensure groundwater protection from further pollution and depletion copyright 2011 john wiley sons ltd

assessment of geochemical processes in the unconfined and confined aquifers in the eastern ganges basin a geochemical approach groundwater quality is gaining more importance in groundwater management due to rapid growth in population agriculture and industrial sectors worldwide the goal of the present study is to evaluate the groundwater chemistry and to identify the geochemical processes governing the water chemistry in the shallow unconfined and deeper confined aquifers in the eastern ganges basin using geochemical methods groundwater samples were analysed for major ions and metals fe mn zn cu pb and as shallow wells are found to have high ph ec tds ca mg cl and so4 and low hco3 cl ratio compared to the deep wells however the average concentration of na hco3 no3 po4 f and mn is not significantly varied with depth which indicates that the variation in the water chemistry between unconfined and confined aquifers is not only due to the natural processes but also indicates that surface contamination sources could have affected the water chemistry in the unconfined aquifer in the unconfined aquifer processes like wastewater infiltration denitrification reverse ion exchange and mineral weathering govern the water chemistry the water chemistry in the confined aquifer is regulated by weathering of silicate and carbonate minerals and regional flow

identifying source and evaluation of hydrogeochemical processes in the hard rock aquifer system geostatistical analysis and geochemical modeling techniques in order to quantify spatio temporal changes in the hydrogeochemistry of swarnamukhi river basin andhra pradesh india a total of 239 groundwater samples have been collected for pre and post monsoon seasons of 2014 and 2015 the geology of the study area is comprised of granite granitic gneisses shales quartzites laterites and recent alluvium along the river course based on the study of geochemical processes of different seasons it is found that the occurrence of na and hco3 in 2014 shifted toward ca and hco3 in 2015 due to cation exchange process fe shows the higher concentration value than safe limit due to dissolution of ferruginous minerals and domestic sewage discharges bivariate plots of various ions and ratios depict the predominance of silicate weathering over carbonate and evaporite dissolution apart from anthropogenic activities in the enrichment of groundwater constituents high nitrate concentration was observed in the urbanized regions of the basin followed by intense agricultural areas geochemical modeling was carried out using mineral saturation index and thermodynamic stability plots to deduce major weathered products most of the groundwater samples in the study area are saturated with carbonate minerals but are undersaturated with silicate minerals thermodynamic stability plots suggest the formation of kaolinite secondary mineral and presence of aluminosilicate minerals fuzzy calculation is applied to determine the water quality index which categorizes a majority of the samples as excellent to good category for human use factor analysis points toward the mixed source identification of ionic constituents saline water mixing index model calculation suggests the effect of salinization in coastal areas due to heavy withdrawal of the fresh groundwater resources for various uses whereas in the mainland it is due to agricultural runoff and domestic waste water

geochemical influences on the quality of groundwater in eastern part of semnan province iran to identify the principal geochemical processes controlling groundwater quality in eastern part of semnan province a total of 257 groundwater samples from wells and springs were collected since groundwater is the only source of water for various purposes preservation of the quality of available groundwater resources in this region is of great importance the order of abundance of anions was cl so4 2 hco3 no3 f and for them the average values were 509 41 404 24 120 48 14 51 0 59 mg l respectively on the other hand for cations na and ca2 with average values of 442 10 and 135 09 mg l were the most abundant parameters geochemical characteristics based on bivariate diagrams indicated that na release from silicate weathering is an important process whereas the dissolution of dolomite and the effect of silicate materials on the aquifer were other determinative processes influencing the quality of groundwater in the area in order to predict the overall quality of groundwater with respect to a calculated water quality index wqi support vector machine svm and artificial neural network ann were utilized the correlation coefficients between the predicted and observed wqi for the training and test data set related to svm were 0 97 and 0 96 respectively on the contrary the results of anns with early stopping showed roughly the same performance resulting in correlation coefficients of 0 98 and 0 96 for the training and test data set respectively as a whole the wqi for 8 of the sampling stations was 50 and for 17 the calculated index was 60 which are important concerns

investigation of the hydrogeochemical processes in an alluvial channel aquifer located in a typical karoo basin of southern africa an investigation was conducted to assess the hydrogeochemical processes of an alluvial channel aquifer located in a typical karoo basin of southern africa the investigation was aimed at identifying and describing the groundwater chemistry evolution and its contribution to the overall groundwater quality x ray fluorescent spectrometry xrf and x ray diffractometry xrd analyses were performed on geological samples to identify and quantify the major element oxides and minerals the study utilises the conventional piper diagram bivariate plots and phreeqc hydrogeochemical model to analyse groundwater chemistry data obtained during the wet february and may and dry seasons august and december of 2011 the xrf and xrd results show that the channel deposits are dominated by sio2 element oxides and quartz minerals thus elevated concentrations of silicon si4 were found in the groundwater dolomite and calcite minerals were also detected in the unconsolidated aquifer sediments the detailed study of the alluvial aquifer system has shown that dissolution of dolomite and calcite minerals and ion exchange are the dominant hydrogeochemical processes influencing the groundwater quality the groundwater evolves from ca2 mg2 hco3 recharge water that goes through ion exchange with na in the clay silt sediment to give a na hco3 water type the groundwater is supersaturated with respect to quartz dolomite and calcite minerals the study shows the potential usefulness of simple bivariate plots as a complimentary tool to the conventional methods for analyzing groundwater hydrogeochemical processes

the origin of a large 3 km maar volcano by coalescence of multiple shallow craters lake purrumbete maar southeastern australia lake purrumbete maar is located in the intraplate monogenetic newer volcanics province in southeastern australia the extremely large crater of 3000 m in diameter formed on an intersection of two fault lines and comprises at least three coalesced vents the evolution of these vents is controlled by the interaction of the tectonic setting and the properties of both hard and soft rock aquifers lithics in the maar deposits originate from country rock formations less than 300 m deep indicating that the large size of the crater cannot only be the result of the downwards migration of the explosion foci in a single vent vertical crater walls and primary inward dipping beds evidence that the original size of the crater has been largely preserved detailed mapping of the facies distributions the direction of transport of base surges and pyroclastic flows and the distribution of ballistic block fields form the basis for the reconstruction of the complex eruption history which is characterised by alternations of the eruption style between relatively dry and wet phreatomagmatic conditions and migration of the vent location along tectonic structures three temporally separated eruption phases are recognised each starting at the same crater located directly at the intersection of two local fault lines activity then moved quickly to different locations a significant volcanic hiatus between two of the three phases shows that the magmatic system was reactivated the enlargement of especially the main crater by both lateral and vertical growth led to the interception of the individual craters and the formation of the large circular crater lake purrumbete maar is an excellent example of how complicated the evolution of large seemingly simple circular maar volcanoes can be and raises the question if these systems are actually monogenetic

sodium calcium ion exchange in the weathering of shales implications for global weathering budgets unpolluted rivers and streams that drain marine shales show an excess of sodium compared to chloride and a deficiency of calcium and magnesium compared to sulfate and alkalinity this is due in part to cation exchange of sodium for divalent cations on clay minerals consideration of the global weathering budget suggests that up to 34 of the sodium in the total dissolved stream load may be due to cation exchange rather than sodium production via silicate dissolution weathering reactions these results suggest that the weathering budgets for sodium and calcium are in need of revision because of the inclusion of cation exchange processes in the weathering cycle this implies that silicate dissolution is less important in determining the composition of global river water than was previously thought

assessment of the hydrogeochemical characteristics of groundwater in two aquifer systems in cumra plain central anatolia located in a semi arid climate cumra konya plain is one of the most important agricultural regions in turkey groundwater is the major source for agricultural domestic and other water related activities due to the insufficiency of surface water as groundwater is the only major source of water in this area it is important to know the effects of geological formations and anthropogenic activities on groundwater chemistry this study was carried out with the objective of identifying the hydrogeochemical characteristics and processes controlling the groundwater chemistry in cumra plain central anatolia turkey the study area is comprised of two main aquifers which are the semi confined aquifer of the neogene age and the unconfined aquifer of the quaternary age to identify the hydrogeochemical characteristics of groundwater in two aquifer systems and to understand the major factors and mechanisms controlling the groundwater chemistry graphical plots mineral saturations and multivariate statistical analysis of chemical constituents in the groundwater were used study results show that groundwater is generally neutral to slightly alkaline in nature with a ph ranging from 6 67 to 8 10 and the dominance of ions is in the order of ca2 mg2 na k for the neogene aquifer and hco3 so4 2 cl no3 mg2 ca2 na k and so4 2 hco3 cl no3 for the quaternary aquifer while the chemical composition of groundwater in the neogene aquifer is mainly controlled by water rock interaction including dissolution of carbonates and gypsum calcite precipitation and de dolomitization the main geochemical processes in the quaternary aquifer are reverse ion exchange evaporation dissolution of carbonates gypsum and soil salts calcite precipitation and silicate weathering the mechanism controlling groundwater chemistry in the neogene aquifer is actually regulated by the geogenic processes water rock interaction rather than by anthropogenic activities however the mechanism controlling groundwater chemistry in the quaternary aquifer is regulated by both geogenic processes and anthropogenic activities in addition anthropogenic nitrogen pollution in the study area is currently not serious but evaporation and leaching of soil salts due to anthropogenic activities increase the concentrations of ions in the quaternary aquifer

hydrogeochemical controls on shallow alluvial groundwater under agricultural land case study in central portugal a hydrogeochemical study employing graphical multivariate statistical and modeling tools was conducted in an area of alluvial deposits in the mondego river basin to determine the factors and processes controlling the shallow groundwater chemistry groundwater was collected from 29 observation wells in six sampling campaigns between march 2001 and september 2002 samples were analyzed for basic physicochemical parameters major ions and some minor ions hierarchical cluster analysis was applied to the data set including both the spatial and temporal monitoring data and resulted in the definition of eight distinct water types with the aid of hydrochemical and physicochemical scatter plots it was possible to identify the main processes controlling the groundwater chemistry 1 evapotranspiration and recharge 2 calcium and magnesium carbonate and co2 dissolution 3 nitrate leaching from agriculture 4 oxidation and reduction and 5 cation exchange these processes are frequently common to more than one water type but unique in combination and or extent in space and or time geochemical modeling of the water types using phreeqc allowed the validation and to a certain extent quantification of the processes that affect the shallow groundwater evolution these tools can provide an essential support for the assessment of groundwater vulnerability to contamination and for the elaboration of groundwater resource management strategies

natural zeolites enhance groundwater quality evidences from deccan basalts in india the zeolite minerals characterized with hydrated aluminosilicates negative ionic charge and 3d framework structure are well known for purifying the groundwater occurring in basaltic aquifer systems however the filtering mechanism at in situ field conditions is a complex process which is rarely studied and hence it needs to be demonstrated this paper explores the mechanism of hydrochemical processes and evolution of natural zeolites associated with basaltic rock to enhance groundwater quality we present the hydrochemical findings and evolution processes derived from 46 groundwater samples nt 46 belong to zeolitic nz 25 and non zeolitic nnz 21 zones of a micro watershed 4 4 km2 beset over basaltic terrain deccan volcanic province dvp india the groundwater samples collected for one hydrological cycle pre and post monsoons are examined for major ion chemistry to determine the aqueous solution mechanism and ion exchange process occurred in zeolitic and non zeolitic zones further the hydrochemical parameters are appraised by means of dominancy of ions rock water interactions silicate weathering chloro alkaline indices cation exchange bivariate plots and the mechanism controlling groundwater chemistry the results show that 1 the purifying efficiency of zeolites for total ionic strength is observed as 63 85 and 68 58 during pre and post monsoons respectively 2 the significant reduction 36 51 in total hardness attributed to the positive trend of chloro alkaline indices depicting the ion exchange phenomenon between na and k alkalies and ca2 and mg2 alkali earth elements in the zeolitic zone 3 gibbs plot shows the rock water interaction as the predominant mechanism controlling groundwater chemistry in the zeolitic zone and 4 the groundwater quality parameters from zeolitic zone are found within the permissible limit of who drinking water standards

use of hydrochemistry and isotopes for improving the knowledge of groundwater flow in a semiconfined aquifer system of the eastern slavonia croatia abstract knowledge of groundwater flow and accordingly groundwater residence time is immensely important for the sustainable management of groundwater resources this requires a good conceptual model of the aquifer system in this paper a conceptual model based on the interpretations of hydrogeological and hydrochemical data as well as measurements of environmental tracers 18 o 2 h 3 h was formulated for a semiconfined aquifer system in eastern slavonia in croatia the aquifer system is composed of quaternary gravel and sand and silty clayey interlayers and is covered with low permeability deposits measurements of water levels and environmental tracers in the study area clarified the groundwater flow evolution from the recharge area to the discharge area the content of stable isotopes confirmed that the groundwater originates from precipitation the tritium content and geochemical processes such as cation exchange silicate weathering suggested a relatively long residence time of groundwater in the part of the aquifer system that is further from the sava river the same is confirmed by the results of calculated particle tracking pathlines

factors influencing the major ion chemistry in the tihama coastal plain of southern saudi arabia evidences from hydrochemical facies analyses and ionic relationships coastal aquifers across the globe have been a subject of extensive research mainly because of problems related to saline water intrusion as a consequence of global climate changes and overabstraction of groundwater the present work deals with the assessment of factors which affects the groundwater chemistry in parts of the tihama coastal plains in the jazan province of southern saudi arabia hydrochemical parameters ph ec tds major ions no3 and sio2 were obtained from 263 wells and were interpreted hydrochemical facies analyses revealed two main types of groundwater facies i e the mixed groundwater facies predominantly confined to the eastern and central part of the study area away from the coast and groundwater facies dominated by so4 cl no3 ions found mostly in the coastal zones in the western part of the study area the average tds value of the mixed groundwater facies is 945 7 mg l whereas the average tds value is 3149 7 mg l for the so4 cl no3 anionic species greater influence of rainfall recharge can be observed in the mixed water species while saline water mixing or rock water interaction can be seen in the so4 cl no3 type of anionic species however ionic ratios point more toward rock water interaction rather than saline water mixing in the groundwater facies dominated by so4 cl no3 ions this interpretation is also supported by the presence of sabkhas salt flats in the coastal zones where its interaction with the groundwater has resulted in high cl and so4 concentration cl br ratios which have often been used to detect saline water intrusion in coastal zones also do not support saline water intrusion in the study area ionic ratios point toward dissolution and base ion exchange as the main factors influencing the groundwater chemistry silicate weathering and silica dissolution are also found in the area saturation indices point toward gypsum and halite dissolution the average no3 concentration is 157 80 mg l and is mostly attributed to the agricultural practices in the region the presence of shallow unconfined aquifers facilitate the easy percolation of irrigation return flows enriched in no3 concentration from the application of inorganic fertilizers on the agricultural farms

seasonal variation of the solute and suspended sediment load in gangotri glacier meltwater central himalaya india abstract a systematic study on the seasonal variation of major cations and anions was carried out to understand the source of dissolved ions as well as the geochemical weathering processes controlling the meltwater chemistry of gangotri glacier calcium and magnesium are the major cations while sulphate is the dominant anion followed by bicarbonate the high ratios of ca mg na k ca na mg na hco3 na and low ratio of na k tz for pre monsoon monsoon and post monsoon seasons indicate the dominance of carbonate weathering which is a major source of the dissolved ions in the meltwater of gangotri glacier followed by silicate weathering high equivalent ratios of na cl and k cl as compared to sea water indicate relatively lesser contribution from atmospheric input to the chemical composition of meltwater correlation matrix and factor analysis were used to identify various factors controlling the major ion chemistry marked seasonal and diurnal variations were observed in the dissolved ions and suspended sediment concentration daily mean suspended sediment concentration for pre monsoon monsoon and post monsoon was observed as 1719 3281 and 445 mgl 1 respectively highest suspended sediment load was observed in monsoon season followed by pre monsoon and post monsoon seasons the cation denudation rates of gangotri glacier meltwater were calculated to be 42 2 46 5 and 15 9 t km 2 y 1 for pre monsoon june only monsoon and post monsoon respectively these values are higher than that of other himalayan glaciers whereas physical weathering rate of the gangotri glacier catchment was observed to be 7056 15 344 and 588 t km 2 y 1 for pre monsoon june only monsoon and post monsoon respectively much higher than the indian and world averages of river

seismic determination of elastic anisotropy and mantle flow when deformed many rocks develop anisotropic elastic properties on many seismic records a long period 100 to 250 seconds quasi love wave with elliptical polarization arrives slightly after the love wave but before the rayleigh wave mantle anisotropy is sufficient to explain these observations qualitatively as long as the fast axis of symmetry is approximately horizontal quasi love observations for several propagation paths near pacific ocean subduction zones are consistent with either flow variations in the mantle within or beneath subducting plates or variations in the direction of fossil spreading in older parts of the pacific plate

multivariate statistical analysis for identifying water quality and hydrogeochemical evolution of shallow groundwater in quaternary deposits in the lower kelantan river basin malaysian peninsula a long term hydrogeochemical data set is used in this study to evaluate the water quality and hydrogeochemical evolution of shallow groundwater in a quaternary deposit a multivariate statistical method hierarchical cluster analysis hca is applied to overcome the problem of a large number of data points in the integration interpretation and representation of the results hca is applied to a subgroup of the hydrogeochemical data set to evaluate their usefulness to classify the groundwater bodies this subgroup consists of 27 groundwater wells and 15 variables ph total dissolved solids electrical conductivity ec na ca2 mg2 k hco3 cl so42 fe mn nh4 no3 and sio2 only 12 chemical variables were used for the analysis four clusters have been identified c1 c4 with two main prevalent facies na hco3 and ca hco3 the hydrogeochemical evolution of shallow groundwater is governed by the processes of precipitation weathering dissolution and ion exchange