hydrogeochemistry and geochemical simulations to assess water rock interactions in complex carbonate aquifers the case of aguadulce se spain abstract the hydrogeological unit of aguadulce campo de dalias aquifers se spain has a complex geometry this fact together with a continuous rise in water demand due to intensive agriculture and tourism create problems for groundwater quantity and quality in this paper classic geochemical tools managed by means of gis software and geochemical simulations are combined to delineate identify and locate the possible physicochemical processes acting in the aguadulce groundwater two main aquifers can be distinguished the carbonate or lower aquifer of triassic age and the calcodetritic or upper aquifer of plio quaternary age groundwaters from the latter are more saline and assuming all chlorinity originates from seawater intrusion the seawater contribution to their composition would be up to 7 nevertheless the carbonate aquifer appears not to be homogeneous it is compartmentalised into 4 zones where different processes explain the different groundwaters compositions zone 4 samples e margin of the carbonate aquifer resemble those of the plio quaternary aquifer where calcite precipitation dolomite and gypsum dissolution and some cation exchange water rock interaction together with seawater freshwater mixing occur in contrast water rock interaction predominates in zones 1 and 3 of the carbonate aquifer moreover zone 2 samples located between zones 1 and 3 are explained by water rock interaction in addition to mixing with plio quaternary aquifer waters the combination of geochemical simulations with gis and hydrogeochemical analyses has proven to be effective in identifying and locating the different physicochemical processes in the aquifer areas thus improving understanding of hydrogeochemistry in complex aquifers

origin and morphology of limestone caves limestone caves form along ground water paths of greatest discharge and solutional aggressiveness flow routes that acquire increasing discharge accelerate in growth while others languish with negligible growth as discharge increases a maximum rate of wall retreat is approached typically about 0 01 0 1 cm yr determined by chemical kinetics but nearly unaffected by further increase in discharge the time required to reach the maximum rate is nearly independent of kinetics and varies directly with flow distance and temperature and inversely with initial fracture width discharge gradient and pco2 most caves require 104 105 yr to reach traversable size their patterns depend on the mode of ground water recharge sinkhole recharge forms branching caves with tributaries that join downstream as higher order passages maze caves form where 1 steep gradients and great undersaturation allow many alternate paths to enlarge at similar rates or 2 discharge or renewal of undersaturation is uniform along many alternate routes flood water can form angular networks in fractured rock anastomotic mazes along low angle partings or sponge work where intergranular pores are dominant diffuse recharge also forms networks and spongework often aided by mixing of chemically different waters ramiform caves with sequential outward branches are formed mainly by rising thermal or h2s rich water dissolution rates in cooling water increase with discharge co2 content temperature and thermal gradient but only at thermal gradients of more than 0 01 c m can normal ground water co2 form caves without the aid of hypogenic acids or mixing artesian flow has no inherent tendency to form maze caves geologic structure and stratigraphy influence cave orientation and extent but alone they do not determine branch work versus maze character

using geochemical data and modelling to enhance the understanding of groundwater flow in a regional deep aquifer aquitaine basin south west of france abstract in deep aquifers the complex flow pattern originating from the geological structure often leads to difficult predictions of water origin determination of the main flow paths potential mixing of waters all these uncertainties prevent an efficient management of the resource in the context of the aquitaine basin an original modelling approach suggests that geochemical data can be used to identify flow directions where geological and hydrogeological data are too scarce to provide sufficient information in the eocene sands aquifer the major patterns of groundwater geochemistry suggest the presence of two distinct areas within the aquifer in the north and the east waters exhibit sodium bicarbonate or sodium sulphate facies and moderate total dissolved solids related to high sulphate concentrations in the south waters are characterised by calcium bicarbonate facies and low total dissolved solids sulphur isotopic ratios provided key information on the origin of sulphur in solution meteoric gypsum dissolution pyrite oxidation and also on the intensity of the geochemical processes involved in the dissolution of minerals and the concentration evolution a geochemical model was developed to analyse the processes generating the chemical composition of each sampled water at the aquifer scale four main geochemical processes dissolution redox acid base reaction exchange of varying intensity could explain most of the observed spatial variability in groundwater composition among several potential reaction schemes at each point only one allowed to reproduce the independent variables ph and 13c the developed model was used to select the most probable water pathways at the aquifer scale in this context geochemistry clearly demonstrates the role played by subsurface structures on water flow velocities and residence time in their vicinity in addition the concentrations of several ions could only be justified by the aquitard aquifer interactions

stable isotope 2h 18o and 87sr 86sr and hydrochemistry monitoring for groundwater hydrodynamics analysis in a karst aquifer gran sasso central italy this paper deals with chemical and isotope analyses of 21 springs which were monitored 3 times in the course of 2001 the monitoring program was focused on the groundwater of the gran sasso carbonate karst aquifer central italy typical of the mountainous mediterranean area based on the hydrogeological setting of the study area 6 groups of springs with different groundwater circulation patterns were distinguished the hydrogeochemistry of their main components provided additional information about groundwater flowpaths confirming the proposed classification the spatial distribution of their ion concentrations validated the assumptions underlying the hydrogeological conceptual model showing diverging groundwater flowpaths from the core to the boundaries of the aquifer geochemical modelling and saturation index computation elucidated water carbonate rock interaction contribution by alluvial aquifers at the karst aquifer boundaries as well as impacts of human activities the analysis of 18o 16o and 2h h values and their spatial distribution in the aquifer substantiated the hydrogeology based classification of 6 groups of springs making it possible to trace back groundwater recharge areas based on mean isotope elevations the latter were calculated by using two rain monitoring stations 87sr 86sr analyses showed seasonal changes in many springs in winter spring the changes are due to inflow of new recharge water infiltrating into younger rocks and thus increasing 87sr 86sr values in summer autumn when there is no recharge and spring discharge declines changes are due to base flow groundwater circulating in more ancient rocks with a subsequent drop in 87sr 86sr values the results of this study stress the contribution that spatio temporal isotope monitoring can give to the definition of groundwater flowpaths and hydrodynamics in fissured and karst aquifers taking into account their hydrogeological and hydrogeochemical setting

modeling complex flow in a karst aquifer abstract carbonate aquifers typically have complex groundwater flow patterns that result from depositional heterogeneities and post lithification fracturing and karstification various sources of information may be used to build a conceptual understanding of flow in the system including drilling data well tests geophysical surveys tracer tests and spring gaging these data were assembled to model flow numerically in germany s malm formation at a site where water disappears from the beds of ephemeral stream valleys flows through conduit systems and discharges to springs along surface water features modeling was performed by using a finite difference approach with drain networks representing the conduit component of flow laced throughout the porous medium along paths inferred on the basis of site data this approach represents an improvement over other karst models that attempt to represent a conduit by a single specialized model node at the spring location or by assigning a computationally problematic extremely high permeability to a zone by handling the conduit portion of this mixed flow system with drains a realistic interpretive flow model was created for this intricate aquifer

parsimonious recharge discharge modeling in carbonate fractured aquifers the groundwater flow in the gran sasso aquifer central italy summary in the carbonate fractured aquifer of the gran sasso central italy numerical simulations have been applied to validate a conceptual model of the recharge discharge cycle at regional scale to identify the effective aquifer features that mostly affect the spring discharges simple parsimonious models based on few key parameters whose effective values are well constrained by previous hydrological geological studies are used input data are represented by infiltration calculated considering rainfall snowmelt and runoff in endorheic basins and effective permeability distribution estimated by geological tectonic and hydrogeological settings of the aquifer discharges of tapped springs and tunnel drainages for the 1999 2009 period have been simulated after estimating the recharge area of each monitored spring by the hydrogeological setting and checking them by mean isotope elevation values discharge monitoring has been compared with the simulations obtaining a good agreement both at seasonal and yearly time basis the simulations will also be useful for previewing discharge in drought period and evaluating protection zones of tapped springs in the territory of a national park

conceptual hydrogeological model of flow and transport of dissolved organic carbon in a small jura karst system summary this paper aims at characterizing infiltration and solute transport processes in a karst system during flood events in order to build a conceptual model of hydrogeological functioning the study site is the small karst system of fertans in the french jura soil cover rock matrix and a small spring were monitored to measure hydrological and hydrochemical parameters and particularly a continuous dissolved organic carbon doc signal which is a relevant environmental tracer of fast infiltration we used two combined approaches first from hydrodynamic and hydrochemical data we identified the system structure consistent with a dual porosity scheme and characterized the main processes occurring during flood events second on the basis of this scheme we built a new conceptual hydrogeological model coupled with doc transport to numerically validate the hydrological functioning this modelling approach is based on a rainfall discharge model to simulate spring flow solute transport is modelled using mixing equations including an empirical retardation factor as well as a first order solute decay the model was calibrated and validated on a set of nineteen flood events showing its performances in simulating spring hydrographs and delayed doc signals during flood events with various rainfall intensities we showed that the recharge area of the karst system varied largely with low and high groundwater periods which was attributed to the state of hydraulic connectivity in the unsaturated zone the soil cover appeared to play an important role of mixing and transfer for the recharge water the model simulated the contributions of pre event and event waters during flood events and allowed a better quantification of the available resource it showed in particular that total discharge of some flood events during low water periods is mainly composed of pre event water via piston flow type processes finally this study shows that the mixing model can simulate solute transport correctly taking into account degradation and retardation processes it highlights the need for a quantitative approach on hydrochemical studies of karst systems in order to understand them better

hydrogeology and hydrogeochemistry of gunyuzu semi arid basin eskisehir central anatolia groundwater is often the only water source in semi arid regions of turkey gunyuzu basin located in the sakarya river basin sw of eskisehir exhibits semi arid conditions the study area is composed of paleozoic metamorphic rocks eocene granitic rocks neogene sedimentary rocks and quaternary alluvium in the basin paleozoic marbles are the main reservoir rocks for hot and cold water bordered by impermeable diabases dykes at the sides and by impermeable granites and schists neogene aged limestones conglomerates and alluvium represent the other significant aquifers water samples chosen to exemplify the aquifer characteristics were collected from springs and wells in both the dry and the wet seasons the cation and anion permutation of the samples show that carbonates are the dominant lithology in the formation of chemical composition 18o 11 2 to 8 9 and 2h 79 to 60 isotopic values show that all waters thermal and cold are meteoric in origin the hydrological hydrochemical and isotopic properties of the waters reveal that there exist two main groups of groundwater systems one of these is deep circulating while the other one is shallow tritium values 0 4 tu tritium unit indicate the presence of old static water in these aquifer systems

selective recharge and isotopic composition of shallow groundwater within temperate epigenic carbonate aquifers summary this paper considers the variation of 18o and 2h vsmow in precipitation and shallow groundwater from carbonate aquifers that lend insight into the source and timing of recharge within temperate epigenic karst the shallow groundwater collected during 2010 and 2011 at stream cave sc and natural bridge caverns nbc represent one input to and the primary output from the redmond creek karst aquifer in the cumberland plateau of southeast kentucky respectively these data are compared with the isotopic composition of concurrent samples of precipitation from the same watershed that covers some 1900 ha values of 18o and 2h at sc and nbc are statistically similar and cluster at the midpoint of the local meteoric water line these values remain surprisingly constant despite seasonal changes in temperature regimens and discharge samples in 2012 from regional springs that include redmond creek are more depleted in the heavier isotope and similarly stable despite coming from aquifers of a range of sizes and physical characteristics applying a priestly taylor model for daily values of potential evapotranspiration only 43 of the 1 10 m of precipitation in the 2010 2011 dataset remains as potential recharge primarily during cooler months with lower solar insolation weighting 18o and 2h values of precipitation by potential recharge creates a better match with the isotopic composition of shallow groundwater than by weighting by precipitation amount the isotopic composition and deuterium excess of precipitation samples are directly and inversely proportional to temperature respectively deuterium excess in this study and displays intra and inter annual variation that ranges from a minimum of 11 1 to a maximum of 29 5 that demonstrate the higher than average deuterium excess in greater appalachia and the shifting latitude of moisture sources including a significant winter component of re evaporated continental moisture

numerical simulation and a geochemical model of supergene carbonate hosted non sulphide zinc deposits abstract the proposed metallogenetic model presented in this paper is based on observations from the iranian non sulphide zinc deposits mehdi abad iran kuh and kuh e surmeh the emplacement of non sulphide ore can be generally subdivided into an oxidation stage followed by a post oxidation stage the formation of carbonate hosted non sulphide zinc deposits is primarily controlled by three factors climate protore composition and geology lithology and structure of the wall rocks the climate controls the oxidation and metal transport predominantly through the amount of meteoric water and the availability of oxygen which indirectly is controlled through the thickness of the soil cover and biogenic oxygen consumption favourable conditions for oxidation are an arid climate with minimal biogenic activity within the soil as a consequence oxygen can reach the sulphides easily resulting in higher metal concentrations of the supergene aqueous solutions dry climates are associated with a low water table preventing descending zn bearing fluids from contact with the aquifer and thus from dilution dispersion and removal of metals commonly non sulphide zinc deposits consist of two types of ore red zinc ore rich in zn 20 fe 7 pb as and white zinc ore typically with very high zinc grades up to 40 but low concentrations of iron 4 2 ions during the oxidation stage leads to the precipitation of highly insoluble anglesite which results in low pb 2 concentration within the fluid most of the zinc up to 80 at ph 6 or 97 at ph 5 leaves the oxidation zone and precipitates as zinc carbonates in adjacent parts of the carbonate host rock the neutralisation processes of the sulphuric acid with the carbonates of the host rock during the oxidation stage lead to the formation of co 2 g consequently the co 2 partial pressure p co2 g increases drastically and forms a co 2 g halo around the active oxidation zone thus most of the zinc precipitates as smithsonite which is stable and occurs exclusively in a high p co2 g environment the p co2 g decreases during the post oxidation stage and reaches the level of atmospheric p co2 g under these conditions hydrozincite becomes stable and starts to replace smithsonite most of the stage i smithsonite becomes corroded and is altered to stage ii hydrozincite the post oxidation stage is also associated with the successive formation of local zinc hydro silicates depending on the availability of sio 2 within the solution generally arid climates provide the best conditions for the preservation of non sulphide deposits the limited availability of meteoric water and deep to very deep water tables protect the non sulphide ore from subsequent dissolution

strontium isotope characterization and major ion geochemistry of karst water flow shentou northern china summary karst water is the most important source of water supply for shanxi province northern china the shentou springs are representative of the 19 major karst springs at shanxi the total area of the shentou karst water system is 5316 km 2 the middle ordovician limestone being its major karst aquifer in this study data about the strontium isotope geochemistry and major ion hydrochemistry were analyzed to understand the flow patterns and hydrogeochemical processes of karst water at shentou the contour map of tds value of karst water and that of sr concentration are similar showing the general tendency of increase from the northern western and southern boundary to the discharge area the average values of 87 sr 86 sr ratios of karst water decrease from recharge 0 7107 to discharge area 0 7102 evolving towards those of limestone hostrocks comparison of 87 sr 86 sr ratios with sr content suggests that isotopic compositions of some karst water samples from the recharge and flow through area should be the result of interaction between aquifer limestone matrix and strontium poor recharge waters of meteoric origin however for samples from the discharge area that are plotted above the mixing line mixing with groundwater in the quaternary aquifers with high 87 sr 86 sr ratios may be another factor controlling sr isotope chemistry two major groundwater flow paths were discerned from hydrogeological and geochemical data along both flow paths the 87 sr 86 sr ratios of karst water show a general tendency of decrease geochemical modeling of the major ion geochemistry of karst water using phreeqc also indicates that the chemistry of springs should be affected by the incorporation of groundwater in quaternary aquifer the effect of the mixing action on the spring hydrochemistry in flow path 1 is more remarkable than that in flow path 2 according to different mixing ratios in both paths 30 in flow path 1 and 5 in flow path 2

dissolved organic carbon of infiltration within the autogenic karst hydrosystem this work aims at using the dissolved organic carbon doc as a tracer of infiltration in karstic aquifers with only diffuse recharge regular measurements of doc have been carried out in three karstic systems located in south eastern france during an hydrogeological cycle considering that the doc is mainly located in the soil it might be used as a tracer of the infiltration the behavior of the tracer considerably varies between the high and low flow periods the low concentrations of doc occur when the flow is mainly due to a long residence time of the water in the saturated zone whereas the concentration of doc increases with the contribution of recent waters during the flood period so the doc can be used as a tracer of the infiltration a comparison between the magnesium and the doc allows to demonstrate the ability of using the doc as a tracer of the water residence time

hydrodynamic and isotopic investigations for evaluating the mechanisms and amount of groundwater seepage through a rockslide dam this study addresses the influence of landslide dams on surface water drainage and groundwater flow in the study area of scanno lake and sagittario river central italy a limestone rockslide avalanche formed a lake which has an outlet that is occasionally active showing infiltration into the rockslide dam several springs are present at the lake s base and are partly fed by seepage through the rockslide debris piezometric surveys discharge measurements pumping tests and chemical analyses are tools used to build a conceptual model of the groundwater flow and to evaluate the flow through the rockslide debris seasonal water isotopic signatures validate the assumed model showing a mixing of infiltration recharge and groundwater seepage throughout the rockslide debris various recharge areas have been found for springs pointing out those directly fed by the rockslide debris aquifer hypotheses about seasonal groundwater mixing between the regional carbonate aquifer and the rockslide debris aquifer are supported by isotope results seasonal changes in groundwater table level due to recharge and surface losses from seasonal outlet have been correlated with isotopic groundwater composition from the rockslide debris aquifer and the downstream springs this relationship highlights the role of the rockslide dam body on the hydrodynamics of the studied area relationships between surface waters and groundwater in the area have been completely understood on the basis of water isotopic fingerprinting finally obtaining a complete evaluation of groundwater renewable resources and its regimen copyright 2010 john wiley sons ltd

using non conservative tracers to characterise karstification processes in the merinos colorado carrasco carbonate aquifer system southern spain the systematic sampling of the chemical composition of the groundwater from five karst springs including an overflow spring and one outflowing borehole have permitted to determine distinctive chemical changes in the waters that reflect the geochemical processes occurring in a carbonate aquifer system from southern spain the analysis of the dissolution parameters revealed that geochemical evolution of the karst waters basically depends on the availability of the minerals forming aquifer rocks and the residence time within the aquifers in the three proposed scenarios in the aquifers which include the preferential flow routines the more important geochemical processes taking place during the groundwater flow from the recharge to the discharge zones are co2 dissolution and exsolution outgassing calcite net dissolution calcite and dolomite sequential dissolution gypsum anhydrite and halite dissolution de dolomitization and calcite precipitation a detailed analysis of the hydrochemical data set saturation indices of the minerals and partial pressure of co2 in the waters joined to the application of geochemical modelling methods allowed the elaboration of a hydrogeochemical model of the studied aquifers the developed approach contributes to a better understanding of the karstification processes and the hydrogeological functioning of carbonate aquifers the latter being a crucial aspect for the suitable management of the water resources

interaction between shallow and deep aquifers in the tivoli plain central italy enhanced by groundwater extraction a multi isotope approach and geochemical modeling abstract in the tivoli plain rome central italy the interaction between shallow and deep groundwater flow systems enhanced by groundwater extraction has been investigated using isotopic and chemical tracers a conceptual model of the groundwater flowpaths has been developed and verified by geochemical modeling a combined hydrogeochemical and isotopic investigation using ion relationships such as dic cl ca ca mg so 4 so 4 hco 3 and environmental isotopes 18 o 2 h 87 sr 86 sr 34 s and 13 c was carried out in order to determine the sources of recharge of the aquifer the origin of solutes and the mixing processes in groundwater of tivoli plain multivariate statistical methods such as principal component analysis and cluster analyses have confirmed the existence of different geochemical facies and the role of mixing in the chemical composition of the groundwater results indicate that the hydrochemistry of groundwater is characterized by mixing between end members coming directly from carbonate recharge areas and to groundwater circulating in a deeply buried meso cenozoic carbonate sequence the travertine aquifer is fed by both flow systems but a local contribution by direct input in the plain has also been recognized the stable isotope data 18 o 2 h 13 c and 34 s supports the flow system conceptual model inferred from the geochemical data and represents key data to quantify the geochemical mixing in the different groundwaters of the plain the results of numerical modeling phreeqc are consistent with the flowpaths derived from the hydrogeochemical conceptual model the inverse models performed generated the main geochemical processes occurring in the groundwater flow system which also included mixing geochemical and isotope modeling demonstrate an increasing influence of groundwater from the deeply buried aquifer in the travertine aquifer enhanced by lowering of the travertine aquifer water table due to quarry pumping

hydrochemistry and isotopic studies of carbonatite groundwater systems the alkaline carbonatite complex of barreiro southeastern brazil in brazil alkaline intrusions are source rocks for several commodities bauxite phosphate niobium and barite to mention a few including mineral water the present study aims to understand by means of chemical and stable isotope analyses the residence time circulation and hydrochemical facies of the groundwater systems from the alkaline carbonatitic complex of barreiro state of minas gerais brazil this mesozoic alkaline complex is located in the brazilian tropical region characterized by weathered soils and fractured rocks which play an important role in the groundwater dynamics to assess this influence groundwater samples from 12 points and water samples from 3 artificial lakes were collected for the determination of chemical element and natural isotope 18o deuterium and 13c concentrations and 14c and tritium dating two main groundwater categories were revealed a a local acidic and sub modern groundwater system developed in thick poorly mineralized weathered soil from the inner part of accb and b a basic hypothermal ca 40 ky old fractured aquifer developed in mineralized fenitized quartzites the younger and shallower groundwater circulation is controlled by the present intrusion relief and is prone to environmental impacts the older hypothermal groundwater system indicates existing geothermal residual heat provided by the mesozoic alkaline intrusion

radionuclides as natural tracers for the characterization of fluids in regional discharge areas buda thermal karst hungary summary the buda thermal karst budapest hungary developed in the regional discharge zone of a carbonate rock aquifer system high radioactivity of the spring waters has already been reported in 1912 but there has been no detailed study and no consistent explanation for its origin in this area mixing of cold and hot karst waters was hitherto assigned to be responsible for cave formation however the dissimilarity of the discharging waters within budapest in the north rozsadomb in the south gellert hill may suggest also different cave forming processes the application of radionuclides as natural tracers represents a novel approach to investigate these questions for this study we used uranium radium and radon to identify mixing of fluids in the buda thermal karst system and to infer the temperature and chemical composition of the end members chloride as a conservative component allowed the mixing ratios for the sampled waters to be calculated their fluid compositions were modeled and through the comparison of modeled and measured values the end members were validated as the result of this study it was possible to characterize the mixing end members for the rozsadomb area whereas for the gellert hill discharge zone mixing components could not be identified with the aid of radionuclides therefore it is suggested that different processes are responsible for cave formation in these areas in the rozsadomb area structurally controlled mixing is the dominant cave forming process whereas in the gellert hill area due to the lack of mixing members other processes have to be found which are responsible for the formation of the caves such as retrograde calcite solubility and or geogenic acids such as h 2 s the application of radionuclides thus further supported the differences between the two study areas this study identified moreover the source of elevated radon content of the waters in the gellert hill area in form of iron hydroxide precipitates that accumulate in the spring caves these precipitates are highly efficient in adsorbing radium which generates radon by alpha decay and hence act as local radon source for the waters in this study we showed that uranium radium and radon naturally occurring in groundwater can be used to characterize fluids of different flow systems in regional discharge areas owing to the contrasting geochemical behaviors of these elements

tracing regional flow paths to major springs in trans pecos texas using geochemical data and geochemical models abstract san solomon giffin and phantom lake springs located in trans pecos texas have a high tds na cl so 4 baseflow component derived from a regional flow system and a low tds mixed cation mixed anion stormflow component derived from local precipitation events the hypothesis that the regional flow system maintaining baseflow spring discharge originates in the salt basin and flows through the apache mountains towards the springs is tested with historical geochemical data from wells and springs data from over 1400 wells in the study area over a 50 year period were analyzed and used to delineate 11 hydrochemical facies based on the predominant ions geochemical data from samples along the hypothesized regional flow path indicate a trend of increasing dissolved solids and cl hco 3 ratios and decreasing na cl ratios these are consistent with evolution of groundwater in an unconfined regional system dominated by carbonates and evaporites in the bicarbonate facies the waters represent recent recharge modified by mineral dissolution and cation exchange in the sulfate zones the hydrochemical facies are controlled by gypsum anhydrite and halite dissolution cation exchange and mixing with na cl waters in the chloride zones the hydrochemical facies are controlled by halite dissolution and irrigation return flow spring discharge chemistry is most similar to chloride zone waters na cl and ca so 4 ratios suggest that baseflow is derived from the chloride zone waters upgradient along the hypothesized flow path phreeqc modeled groundwater evolution along the hypothesized flow path and spring discharge under stormflow and baseflow conditions results indicate that 1 hydrochemistry along the regional flow path is controlled by dissolution of halite gypsum dolomite and co 2 and by precipitation of calcite 2 baseflow spring discharge is derived primarily from this regional flow system and 3 spring discharge after major storm events can constitute as much as 72 local recharge that is further modified by dissolution of calcite gypsum and co 2 data analysis and model results suggest that cave formation in this system is occurs during major storm events

dual flow in karst aquifers toward a steady discharge spring presciano central italy influences on a subsurface groundwater dependent ecosystem and on changes related to post earthquake hydrodynamics the presciano spring system central italy is fed by a fractured carbonate regional aquifer and shows peculiar hydrogeological physicochemical hydrogeochemical and biological features that led to hypothesis about local superimposition of a dual groundwater flow system the components of this system are fast flow and baseflow groundwater paths hydrogeochemical and isotopic 18o and d for h2o and 34 text s text so 4 and 18 text o text so 4 data were used to test this conceptual model differences in physico chemistry and ion concentrations were recorded for two main spring sectors attributable to different groundwater flowpaths environmental isotope analyses allowed distinguishing different recharge areas for the two groups more depleted values 10 4 18o and 71 d indicated the existence of a flowpath influenced by a higher elevation recharge area whereas enriched isotope signals 9 9 18o and 66 d supported a regional recharge area of local water infiltration the existence of a dual flow system is also reflected in the relationship between so42 concentration and so42 isotope data the isotopic pattern of so42 reflects the seasonal contributions by the two flow paths to the springs after snowmelt the isotopic sulphate value in the spring outlet is very similar to the spring sector fed by the fast flow component while after the spring exhaustion period its isotopic composition is very similar to the base flow spring sectors fed by the fracture network the influence of the different flowpaths has also been highlighted by changes in water isotope composition after the 2009 l aquila earthquake in this area the strong homogeneous response of the spring system can be attributed to a cleaning of the fracture system which affected the aquifer at regional scale additional investigations adopting the geoelectrical tomography technique highlighted the possibility of the existence of a buried karst channel or at least high permeability shear zone at the contact between the carbonate aquifer and the fluvio lacustrine quaternary deposits where the spring system is located biological indicators such as groundwater copepods also showed a response to the dual flowpath regime the results of this study have great relevance for a better management of the presciano spring habitat which is increasingly threatened by anthropogenic disturbance

hydrologic and geologic factors controlling surface and groundwater chemistry in indian wells owens valley area southeastern california usa the indian wells owens valley area is located in the semi arid basin and range province which is characterized by alternating mountains and alluvial basins surface water resources are limited in this arid region and water demand is mainly met by groundwater pumpage in a classic basin and range groundwater system water flows from recharge areas in the mountains to discharge areas in adjacent valleys discharge areas are generally occupied by playas where large amounts of salt deposition occur due to evaporating groundwater hydrochemical data from a total of 1368 spring surface and well water samples collected over an 80 year period were used to evaluate water quality and to determine processes that control water chemistry q mode hierarchical cluster analysis hca was employed for partitioning the water samples into hydrochemical facies also known as water groups or water types five major water groups resulted from the hca analysis the samples from the area were classified as recharge area waters ca na hco3 water and na ca hco3 water transition zone waters na hco3 cl water and discharge area waters na cl water and more concentrated na cl water spatial plots of the major statistical groups show that the samples that belong to the same group are located in close proximity to one another suggesting the same processes and or flowpaths inverse geochemical models of the statistical groups were developed using phreeqc to elucidate the chemical reactions controlling water chemistry the inverse geochemical modeling demonstrated that relatively few phases are required to derive water chemistry in the area in a broad sense the reactions responsible for the hydrochemical evolution in the area fall into four categories 1 silicate weathering reactions 2 dissolution of salts 3 precipitation of calcite amorphous silica and clay minerals and 4 ion exchange

isotope hydrology and geochemical modeling new insights into the recharge processes and water rock interactions of a fissured carbonate aquifer gran sasso central italy the goal of this paper was to characterize the recharge process and water rock interactions in a regional homogeneous fractured carbonate aquifer in the mediterranean environment gran sasso central italy through isotope data 2h 18o and 13c dic collected between 2006 and 2010 samples were collected from the springs of the gran sasso aquifer and from the underground nuclear physics laboratories located within the aquifer additionally the hydrochemical data and the reference hydrogeological frameworks of previous studies have been used as a starting point for the geochemical modeling the gran sasso aquifer which is bounded by terrigenous and clastic units acting as aquitards accommodates a uniquely broad regional groundwater which feeds springs mainly at its border with high steady discharge in total these springs discharge of more than 18 m3 s at a local scale for the aquifer core and at a regional scale for the overall aquifer 2h 18o and 13c dic isotope data the geochemical inverse modeling through phreeqc and the 13c dic fractionation modeling through netpath 2 0 show the following 1 clear processes of evaporation and related isotope enrichment may be ruled out 2 groundwater flow is active and extends to the overall aquifer without clear signs of layering and partitioning 3 groundwater flowpaths radiate from the core toward the periphery 4 in l aquila plain gran sasso groundwater mixes with shallow quaternary water at a ratio of one half 5 the main geochemical processes are the dissolution of calcite and dolomite and in some cases ion exchange occurs mg2 and so42 release ca2 adsorption 6 in the less mineralized recharge groundwater the 13c dic value is influenced by the 13c dic value of rainfall while in more evolved groundwater the final 13c dic value is reached by fractionation during the flowpaths indicating a lengthy interaction with limestone

oxygen and hydrogen isotopes for the characteristics of groundwater recharge a case study from the chih pen creek basin taiwan assessing the seasonal variation of groundwater recharge is important for effective management of groundwater resources stable isotopes of oxygen and hydrogen were used to estimate the sources of groundwater and seasonal contributions of precipitation to groundwater recharge in chih pen creek basin of eastern taiwan based on the isotopes of precipitation n 177 two different local meteoric water regression lines lmwl can be obtained for the different seasons d 8 0618o 10 08 for wet season precipitation may through october and d 8 65 18o 17 09 for dry season precipitation november through april the slope and intercept of regression line for wet season precipitation are virtually identical to the global meteoric water line gmwl of craig 1961 in contrast to during dry season precipitation due to evaporation effect the intercept of 17 09 is much higher than of the gmwl of 10 the results show the stable isotopes compositions of precipitation decrease with increasing rainfall amount and air temperature due to the amount effect of precipitation is pronounced the amount effect is clearly but do not show the temperature effect from january to december 2007 using a mass balance equation a comparison of deuterium excess or d values of precipitation and groundwater indicates the groundwater consist of 76 wet season precipitation and 24 dry season precipitation representing a distinct seasonal variation of groundwater recharge in study area about 79 of the groundwater is recharged from the river water of the mountain watershed and 21 is from the rain that falls on the basin

calc silicate alteration in the hemlo gold deposit ontario mineral assemblages p t x constraints and significance a late calc silicate alteration characterizes the archean hemlo gold deposit in ontario canada calc silicate minerals including epidote clinozoisite tremolite actinolite titanite prehnite pumpellyite allanite grossular garnet antimonian vesuvianite and armenite occur as mono or bi mineralic veins or aggregates but are volumetrically minor in the main orebody golden giant mine aggregates of various combinations of tremolite actinolite clinopyroxene phlogopite talc chlorite calcite dolomite microcline tourmaline and quartz are abundant in the diffuse westward extension c zone of the williams mine and north zone of the golden sceptre resources ltd property mineral equilibria calcite dolomite geothermometry and fluid inclusion study indicate that the late calc silicate alteration occurred at about 200 degrees to 400 degrees c and 1 to 2 kbars in an aqueous fluid of moderate to high salinity x sub co 2 in the hydrothermal fluid increased from 0 02 in the main orebody to 0 1 in the diffuse westward extension compositions of phlogopite yield log f hf f sub h 2 o from 4 97 to 6 08 for the coexisting hydrothermal fluid at 350 degrees c the calc silicate alteration most likely occurred at about 2637 to 2644 ma at least 30 m y later than the peak metamorphism of the region homogenization temperatures of fluid inclusions in both quartz and carbonates range from 200 degrees to 400 degrees c and exhibit a good almost linear correlation with salinity 5 2 37 wt nacl equiv which is consistent with mixing of a hot saline magmatic fluid with a cool dilute fluid within a dilatant regional planar structure the hemlo shear zone a direct association of native gold grains with calc silicate minerals is observed in all parts of the hemlo deposit the late calc silicate alteration must have been responsible for at least some of the economic mineralization in the hemlo deposit

chemical and isotopic δ18o δ2h δ13c 222rn multi tracing for groundwater conceptual model of carbonate aquifer gran sasso infn underground laboratory central italy summary a hydrochemical and isotope study was conducted on the drainage waters of an underground laboratory located inside the gran sasso massif central italy the study was expected to improve the conceptual model of groundwater circulation at the base of an over 1000 thick unsaturated zone in the gran sasso partitioned karst aquifer this lithostratigraphically and tectonically complex aquifer is typical of africa europe thrust and fold collision belt in the mediterranean area in this case investigations on water rock interactions during recharge in complex aquifers overlaid by a thick unsaturated zone have been made thanks to the strategic location of the gran sasso underground laboratories located in the core of a huge carbonate aquifer knowledge of the local basic hydrogeological setting was the starting point for a detailed hydrogeochemical and isotopic study which was carried out at the aquifer scale and at the fine scale in the underground laboratories the water rock interaction processes were investigated both spatially and in temporal sequences analysing recharge waters and groundwater in the underground laboratories by multitracing techniques including major ions and 18o 2h and 13c stable isotopes use of 222rn provides information on transit time in the aquifer processes proved to be typical of carbonate rocks with clear influence of vertical movement of water on chemical physical parameters through the unsaturated zone conversely in the saturated zone these processes proved to be dominantly affected by local geological structural conditions a conceptual model with dual flow velocity is proposed directly related to the local geological structural setting 222rn decay enables to calculate an effective velocity of around 10 m day for the fracture network through the sequence of less permeable dolomites and underlying limestone lag time between recharge and chemical changes in the saturated zone testifies to an effective velocity of about 35 m day for fast flow through recent and active extensional faults

geostatistical and geochemical analysis of surface water leakage into groundwater on a regional scale a case study in the liulin karst system northwestern china abstract the liulin karst system is typical of hydrogeological systems in northern china with a group of springs as the dominant way of regional groundwater discharge surface water leakage into groundwater has been observed in six sections of the rivers in the study area to extract hydrogeological information from hydrochemical data 29 water samples were collected from the system on a trilinear diagram most of the groundwater samples are clustered around the surface waters indicating the effect of leakage on their chemistry r mode factor analysis was made on seven variables na ca mg so 4 cl hco 3 and no 3 of the samples and three principal factors were obtained the f 1 factor is composed of ca mg and so 4 the f 2 of hco 3 and no 3 and the f 3 of na and cl these factors are then used as regionalized variables in ordinary kriging for unbiased estimates of the spatial variations of their scores considering regional hydrogeological conditions the hydrogeological implications of the spatial distribution of the factor scores as related to the effects of the surface leakage are discussed to evaluate the geochemical processes the geochemical modeling code netpath was employed the modeling results show that mixing commonly occurs in the system and dolomite dissolution is more important than calcite dissolution dedolomitization calcite precipitation and dolomite dissolution driven by anhydrite dissolution is locally important in the western flank of the system where the surface water leakage has the least effect

linear model describing three components of flow in karst aquifers using 18o data the stable isotope of oxygen 18o is used as a naturally occurring ground water tracer time series data for 18o are analyzed to model the distinct responses and relative proportions of the conduit intermediate and diffuse flow components in karst aquifers this analysis also describes mathematically the dynamics of the transient fluid interchange between conduits and diffusive networks conduit and intermediate flow are described by linear systems methods whereas diffuse flow is described by mass balance methods an automated optimization process estimates parameters of lognormal pearson type iii and gamma distributions which are used as transfer functions in linear systems analysis diffuse flow and mixing parameters also are estimated by these optimization methods results indicate the relative proximity of a well to a main conduit flowpath and can help to predict the movement and residence times of potential contaminants the three component linear model is applied to five wells which respond to changes in the isotopic composition of point recharge water from a sinking stream in the madison aquifer in the black hills of south dakota flow velocities as much as 540 m d and system memories of as much as 71 years are estimated by this method also the mean median and standard deviation of traveltimes time to peak response and the relative fraction of flow for each of the three components are determined for these wells this analysis infers that flow may branch apart and rejoin as a result of an anastomotic or channeled karst network

a micromorphological index of soil development for the quaternary geology research abstract profile development indices of harden harden j w 1982 a quantitative index of soil development from field examples from a chronosequence in central california geoderma 285 1 98 and ferrari and magaldi ferrari g magaldi d 1983 significato ed applicazioni della paleopedologia nella stratigrafia del quaternario boll mus civ st nat verona 10 315 340 have shown their utility for comparative dating of some paleosols during geomorphological and geological surveys in italy and other countries pedostratigraphic methods have been commonly applied to soil profiles formed in continental formations unfortunately buried and relict paleosols are very scarce or badly preserved in some areas of italy due to past and recent tectonic activity and to strong human impact dating back to prehistoric times in order to use relict paleosols for correct chronostratigraphic interpretation of relict paleosols and in order to correlate them with old landscape forms for the reconstruction of quaternary sequences a new micromorphological index misodi for assessing soil development and degree of weathering was devised the index was tested in the extensional tectonic basin of l aquila scoppito abruzzi central italy where some chronostratigraphic information is available results demonstrate that there is a good relationship between presumed relative age of paleosols and degree of weathering and pedogenesis in b and b c horizons as assessed by this index the index has the potential to be adapted for application to other paleosol types in other countries

a four component mixing model for water in a karst terrain in south central indiana usa using solute concentration and stable isotopes as tracers the study area lies in a highly karstified carbonate terrain in south central indiana sinkholes conduits and caves form large secondary pathways for the subsurface flow as a result the discharge from a main emergence point for the subsurface flow system the orangeville rise quickly responds to the storm events and shows wide variations in flow rate water chemistry and stable isotopic compositions these responses are attributed to the mixing of water in secondary pathways in the study area recharge occurs through the thick mantled karst plain and the sinkhole plains and the role of soil layer and epikarst in the recharge process is of great importance rain dic 2 hco3 mg l 13cdic 7 soil water dic 544 hco3 mg l 13cdic 14 7 epikarstic water dic 224 hco3 mg l 13cdic 13 6 and phreatic diffuse flow water dic 299 hco3 mg l 13cdic 11 8 generally showed unique and constant dissolved inorganic carbon dic and 13cdic values over time using dic and 13cdic as tracers a four component mixing model was established for the karstic flow system by constructing the discharge hydrograph separation curves the mixing ratio of each component rain 10 6 soil 3 1 epikarstic 52 3 and phreatic 34 0 water was determined for the orangeville rise discharge over the testing period of 104 h after the storm event of 10 4 90 vadose water occupied 55 4 of spring discharge and this demonstrates the importance of the unsaturated zone especially the epikarst in the karstic flow systems

cl br ratios and environmental isotopes as indicators of recharge variability and groundwater flow an example from the southeast murray basin australia abstract systematic variations in cl br ratios together with r 36 cl values 14 c activities and 18 o values reflect differences in groundwater recharge and define groundwater flow paths in the riverine province of the southeast murray basin in groundwater from the shallowest shepparton formation homogenisation of cl br and 18 o values and a decline in 14 c activities with depth imply that vertical flow dominates the 14 c activities define variations in pre land clearing recharge in the palaeovalleys of present day rivers deep leads which contain sandier sediments higher recharge 0 5 to 1 4 mm year produced relatively fresh groundwater tds 36 cl values in groundwater from the goulburn subcatchment zones of groundwater with variable cl br ratios in the deeper calivil renmark aquifer also allow the detection of rapid leakage from the surface that has the potential to compromise groundwater resources

fractured rock hydromechanics from borehole testing to solute transport and co2 storage the paper was prepared with partial support of the us department of energy under contract no de ac02 05ch11231 with the lawrence berkeley national laboratory

isotopic composition of precipitation in italy a first overall map abstract composite monthly samples of atmospheric precipitation were collected over different periods of time ranging from one to seven years at 77 different locations throughout italy these samples were measured for their oxygen and hydrogen isotopic composition to obtain basic information for hydrological and meteorological studies in this area on the basis of the results obtained a first map of the isotopic composition of precipitations in italy has been drawn up the main features of this map are the following 1 no isotopic latitudinal gradient has been found along the tyrrhenian coast from sicily to the italian french border despite the considerable range of latitude 2 a minor latitudinal gradient is found in the southeasternmost section of the country apulia partially favored by the local morphology 3 a marked shadow effect of the apennines is apparent along the southern section of the po valley and along the central section of the adriatic coast 4 the contribution of water vapor from the northernmost section of the adriatic sea affects the eastern and central sections of the po plain 5 the shadow effect of the alps is considerably smaller than expected 6 the isotopic vertical gradients calculated in nine different areas and based on groups of two to five different stations vary but are essentially close to about 0 2 100 m 7 when mean monthly temperature values were available their relationship with the isotopic composition of precipitation was found to be on average very poor 8 the relationship between mean 18o and mean d calculated for the collection locations shows shifts of both the slope and the deuterium excess when compared to the global meteoric water line these shifts are different for northern central and southern italy 9 in a few cases anomalously low monthly values suggest the existence of pronounced amount effects

stable isotopic information for hydrological investigation in hailuogou watershed on the eastern slope of mount gongga china hydrological systems have been seriously affected by changes of glaciations and snow covers in mount gongga sichuan china but the relevance of ice snow melt for alpine river basin hydrology is so far not well known to better understand hydrological features of the hailuogou river changes of 18o and 2h were investigated by analyzing 117 water samples collected from may 2008 to november 2009 our results show that the stream water contains a relatively intermediate magnitude of isotopic variations with 18o ranging from 18 09 to 13 08 and 2h from 126 5 to 88 8 the average values are both higher than those of ice snow meltwater but lower than those of meteoric water these data also show a gradually increasing trend from upstream to downstream and these changes might document the fingerprint of ice snow melt in the headwater region and indicate the increasing recharge of heavy isotope enriched waters with flow distance the similarity in slopes of 2h and 18o relationship for meteoric waters and stream waters suggests that the isotopic signature of precipitation is well preserved in stream flow and during the rainfall and stream flow the evaporation is only minor based on 18o model the results suggested that the fraction of ice snow meltwater input over the total stream flow ranged from 84 50 to 86 52 in the headwater region but the fraction of ice snow meltwater input from upper basin downward was significantly decreased the study demonstrates that ice snow meltwater is a substantially important water source in alpine regions on the edge of tibetan plateau

long term trend and fluctuations of karst spring discharge in a mediterranean area central southern italy karst springs in central southern italy are largely exploited for the human consumption since the roman times and currently feed some tens of millions inhabitants with tap water of high quality unlike other karst springs they are characterized by a steady rate during the year with modest seasonal variability however the effects of climate changes are being strongly perceived in central and southern italy as in the rest of the mediterranean basin and groundwater is obviously also affected in this paper we analyze the discharge time series of some important karst springs in the region evaluating the trends and fluctuations in relation to rainfall regime on a yearly time scale the aim is to evaluate the response of these large karst aquifers in the mediterranean area to the recharge input variation the role of the north atlantic oscillation has also been considered trends and fluctuations have been highlighted by n years moving average and transforming the time series by the rescaled adjusted partial sum the results show that a drop in the discharge has occurred since 1987 with reductions ranging from 15 up to 30 although this negative trend is now possibly attenuating or even reversing as a final remark the spring discharge of the large karst aquifers in central southern italy can be assumed as a robust indicator for climate changes as it integrates the effects of precipitation and temperature variation in time and space