hydrochemical processes in the lower jordan valley and in the dead sea area abstract changes in the concentrations of major some minor and trace elements occurring in both surface and groundwater of the lower jordan river dead sea drainage basin have been investigated in order to identify the characteristics of the regional aquifers and their recharge areas spider patterns of elements and rare earth distribution patterns pinpoint the characteristic chemical features of groundwater as compared to seawater the high br cl ratios in groundwater are caused either by high br cl ratios in precipitation by leaching of br from bituminous matter or by mixing with brines beyond the epsomite stage the locations of groundwater samples with enhanced b contents coincide with the distribution of gypsum in the beds of the lisan formation which produces water with nearly constant b so 4 2 molar ratios aeolian distribution of the unconsolidated lisan sediments influences the b so 4 ratio in the area of lake tiberias and in the jordan highlands the high gd anomaly in the dead sea water is of geologic origin whereas that in the jordan river and in nahal stream qidron is largely anthropogenic the anthropogenic gd input to the dead sea is insignificant compared to the actual amount in the water of the dead sea hot saline water encountered along the western shores of the dead sea with high gd anomalies indicate that they contain large amounts of ancient dead sea water that mix as hot ascending brines with fresh water the recharge area of groundwater in the lower jordan valley extends largely over limestone and dolomite outcrops of the upper cretaceous judea group weathering of locally underlying lower cretaceous volcanics in the area of pezael beqaot and argaman yield groundwater with 34 s so 4 2 values ranging from 2 to 4 the presence of sulphide bearing bodies in this area is attested to magnetic anomalies detected at depths of several kilometres 34 s so 4 2 indicates very deep groundwater circulation high 34 s so 4 2 15 is typical for marine sulphates from the judea and avedat group limestone the springs located along the northwestern shore of the dead sea discharge water replenished on the eastern judea mountains the increase in the salinity of this water is due to brines flushed from sediments and from adjacent sedimentary rocks which host entrapped brines from the precursors of the dead sea formed during the late stages of lake lisan fresher water flushes out these residual brines as a result of falling sea level salinity increase in groundwater is also affected by the ascent of deep seated hot brines from pre sedom periods along the rift faults calculations of mixing between fresh and highly saline end members show that leaching of anhydrite from sediments precipitation of calcite formation of dolomite albitization of plagioclase and ion exchange with abundant clay minerals control the major element composition of the saline groundwater

oxygen isotopes and sea level from the time that detailed oxygen isotope records derived from foraminifera living in the constant temperature environment of the abyssal ocean became available there has been a discrepancy between the ice volume record that these records imply and that derived from the altitude of dated coral terraces around the world here we re examine the data and conclude that the temperature of the abyssal ocean has been an actively varying component of the climate system

a 7000 year environmental history and soil erosion record inferred from the deep sediments of lake pavin massif central france a 14 m long sedimentary sequence core pav12 was collected in the deepest part of lake pavin a maar lake located in the french massif central the pav12 sedimentary sequence documents the lake s environmental evolution since its formation 7000 years ago the relationships between the catchment s vegetation cover erosion processes and changes in trophic status were shown using a multi proxy characterization of mineral and organic fractions supported by palynological data the record shows a succession of lithological units starting at the base with volcanoclastic material corresponding to the early stage of lake pavin the deposition of organic rich and diatomaceous sedimentary units above volcanoclastic material indicates an evolution toward a pristine lacustrine state the late holocene environmental history of this lake is marked by two tipping points reflecting major environmental disturbances at ca 4000 cal bp and after the deposition of erosive mass wasting deposits mwds at 1350 cal bp ce 600 and 650 cal bp ce 1300 the upper unit of core pav12 which corresponds to the past 700 years indicates that one of these mwds was likely the driving force behind a major limnological change marked by a shift in redox sensitive elements i e current meromictic lacustrine state the palynological diagram indicates a forested catchment where woodland clearances and agro pastoral activities have remained limited except over the last 700 years these findings suggest restricted human impact within the watershed compared to other regional archives the reconstruction of the lake pavin erosion record determined from titanium and red amorphous particle fluxes highlights phases of enhanced erosion at ca 6 5 5 5 4 1 3 8 3 5 2 8 2 6 1 6 1 4 cal kyr bp and during the little ice age lia a comparison between this erosion record palaeoenvironmental archives from western europe and palaeoclimatic data supports an atlantic signal driving precipitation patterns over lake pavin at centennial to millennial timescales the influence of local human activities even on a small scale cannot be completely discounted as their impact on erosional processes may be amplified in a steep catchment such as that found in lake pavin

carbon isotope exchange rate of dic in karst groundwater abstract the kinetics of isotopic exchange between dissolved inorganic carbon dic of groundwater and calcite of the matrix of karst aquifers of cyrenaica libya can be deduced from 13 c and 14 c data the aquifers are mostly confined and the majority of the wells do not show any occurrence of modern recharge in 1976 1980 in fact the tritium content was below 1 tritium unit tu in most sites assuming that the isotopic exchange takes place through a first order reaction such as 14 c radioactive decay it can be shown that a linear correlation occurs between ln a and ln m e p where a is the 14 c activity m and are the 13 c contents of matrix calcite and dic respectively and e p is the 13 c enrichment in caco 3 precipitation the slope of the correlation provides the half life of the isotopic exchange process for cyrenaica karst groundwater a half life of about 11 000 years is obtained i e about double that of 14 c radioactive decay the isotopic exchange kinetics also depends on the ratio between groundwater volume and the calcite surface exposed to the exchange process thus other aquifers will show different exchange half life values the cretaceous chalk aquifers of the paris basin france and lagerdorf germany give a half life of about 4000 years much shorter than that of cyrenaica which may be due to the high porosity i e to the large surface available for the isotope exchange process the berkshire chalk aquifer uk gives a half life of about 10 000 years much higher half lives above 20 000 years are obtained for two sandy aquifers in flevoland the netherlands and texas usa which could be explained by the low caco 3 content of the aquifer matrix the highest half life value about 40 000 years is obtained in an artesian limestone aquifer in florida usa

isotopic geochemistry of the groundwater system in arid and semiarid areas and its significance a case study in shiyang river basin gansu province northwest china shiyang river basin located in the eastern part of hexi corridor in the middle gansu province nw china is a typical arid to semiarid area within its drainage distance of merely 300 km the groundwater system shows a gradual hydrochemical zonation from the upper reach to the lower reach which is composed of hydrocarbonate sulfate to chloride zones respectively variation in the saturation index si of calcite and dolomite shows that under arid to semiarid conditions the drastic evaporation causes the groundwater quality to deteriorate in the lower reach isotopic compositions of h o and he in the groundwater show that the groundwater recharge sources are mainly from meteoric water 3he 3he 20ne coordinates could clearly distinguish the water sources and mixing among them in the caiqi region there is apparent mixing of the crevice water containing excess 4he with the overlying groundwater which also implies a much lower circulation rate of the groundwater fairly high 3he 4he ratios of the groundwaters collected from the adjacent area of hidden faults along qilian mountains show the eminent input of mantle derived helium indicating that these faults not only cut the crust deeply but are currently active

differentiation of palaeomarine and modern seawater intruded salinities in coastal groundwaters of karaikal and tanjavur india based on inorganic chemistry organic biomarker fingerprints and radiocarbon dating abstract hydrosalinity evolution is examined in the karaikal and tanjavur coastal aquifers situated about 300 km south of madras tamil nadu india ancient and modern sources of solutes in groundwaters have been differentiated using hydro geochemical data environmental radioisotope dates and organic biomarkers results from different techniques show consistently that the pliocene aquifer possesses characteristic palmitoleic and oleic acid biomarkers apparent 14 c ages of more than 20 000 years and high i cl ratio the modern marine estuarine intruded groundwaters in the alluvial aquifer display relatively younger apparent 14 c ages modern to 3000 years enriched potassium ion low i cl ratio and contain vaccenic and hopanoic acid biomarkers and they also tend to display transient changes in chemical characteristics these results have practical importance with regard to identifying and controlling seawater intrusion in coastal areas

application of multiple isotopic and geochemical tracers for investigation of recharge salinization and residence time of water in the souss massa aquifer southwest of morocco summary groundwater and surface water in souss massa basin in the west southern part of morocco is characterized by a large variation in salinity up to levels of 37 g l 1 the high salinity coupled with groundwater level decline pose serious problems for current irrigation and domestic water supplies as well as future exploitation a combined hydrogeologic and isotopic investigation using several chemical and isotopic tracers such as br cl 18 o 2 h 3 h 87 sr 86 sr 11 b and 14 c was carried out in order to determine the sources of water recharge to the aquifer the origin of salinity and the residence time of water stable isotope 3 h and 14 c data indicate that the high atlas mountains in the northern margin of the souss massa basin with high rainfall and low 18 o and 2 h values 6 to 8 and 36 to 50 is currently constitute the major source of recharge to the souss massa shallow aquifer particularly along the eastern part of the basin localized stable isotope enrichments offset meteoric isotopic signature and are associated with high nitrate concentrations which infer water recycling via water agricultural return flows the 3 h and 14 c data suggest that the residence time of water in the western part of the basin is in the order of several thousands of years hence old water is mined particularly in the coastal areas the multiple isotope analyses and chemical tracing of groundwater from the basin reveal that seawater intrusion is just one of multiple salinity sources that affect the quality of groundwater in the souss massa aquifer we differentiate between modern seawater intrusion salinization by remnants of seawater entrapped in the middle souss plains recharge of nitrate rich agricultural return flow and dissolution of evaporate rocks gypsum and halite minerals along the outcrops of the high atlas mountains the data generated in this study provide the framework for a comprehensive management plan in which water exploitation should shift toward the eastern part of the basin where current recharge occurs with young and high quality groundwater in contrast we argued that the heavily exploited aquifer along the coastal areas is more vulnerable given the relatively longer residence time of the water and salinization processes in this part of the aquifer

data dependent non double couple components of shallow earthquake source mechanisms effects of waveform inversion instability seismic moment tensors are routinely determined for global earthquakes using waveform inversions and the resulting double couple and non double couple characteristics are extensively used in tectonic analyses for shallow events several moment tensor components are intrinsically poorly resolved especially for surface wave inversions which can lead to artificial non double couple components or can obscure actual non double couple components in the source representations the relatively greater instability of surface wave inversions can cause differences between inversions based on only body waves and joint inversions of body and surface waves the harvard cmt catalog exhibits systematic variations in non double couple components with seismic moment which can be attributed to use of only body waves in inversions for small events and combined body and surface waves for large events systematic behavior of non double couple components with regional strain environment is significantly less dependent on seismic moment when solutions influenced by less stable surface waves are omitted

hydrogeochemical and isotopic evidence of groundwater salinization in a coastal aquifer a case study in jeju volcanic island korea abstract in order to identify the origin of saline groundwater in the eastern part of jeju volcanic island korea a hydrogeochemical and isotopic study has been carried out for 18 observation wells located in east and southeast coastal regions the total dissolved solid contents of groundwaters are highly variable 77 21 782 mg l oxygen hydrogen sulfur and strontium isotopic data clearly show that the saline water results from mixing of groundwater with seawater strontium isotopic compositions and br cl and i cl ratios strongly suggest that the source of salinity is modern seawater intrusion hydrogeochemical characteristics based on bivariate diagrams of major and minor ions show that changes in the chemical composition of groundwater are mainly controlled by the salinization process followed by cation exchange reactions the highly permeable aquifers at the east coastal region are characterized by low hydraulic gradient and discharge rate and high hydraulic conductivity as compared with other regions these properties enhance the salinization of groundwater observed in the study area based on the cl br and 18 o data seawater was determined to have intruded inland some 2 5 km from the coastline considering the poor correlation of sampling depth and cl concentrations observed the position of seawater freshwater interface is not uniformly distributed in the study area due to heterogeneities of the basaltic aquifers

isotopic evidence for palaeowaters in the british isles before the 20th century groundwater circulation in the aquifers of the british isles had largely adjusted to the temperate maritime climate and sea levels established over the past 10 ka since the end of the pleistocene however in the last 100 a this natural regime has been disturbed by abstraction of water for public supply and industrial use and palaeowaters from earlier recharge episodes are now becoming a factor to be considered in water balance estimates this paper presents a synthesis of the existing palaeowater distribution in the british isles based on isotopic evidence 18o 2h and and14c as such it has relevance to palaeoclimatic studies in addition to the water resource implications the triassic basins of england and northern ireland contain saline waters beyond the range14c dating 40 ka stable isotopic ratios show enrichment in some basins and depletion in others without an overall pattern that would explain all the observed compositions the results for the wessex basin suggest recharge in pre quaternary times but for the other basins some flushing by pleistocene or holocene meteoric waters is indicated isolated occurrences of apparently long residence waters are found elsewhere throughout the british isles for example from carboniferous and lower palaeozoic strata in such cases environmental isotopes are more useful as constraints on hydrogeological models than as indicators of palaeoconditions major water supply aquifers are restricted almost entirely to england the two sandstone formations triassic sherwood sandstone and cretaceous lower greensand have a greater range of stable isotopic values between phreatic and confined conditions than the two carbonate formations jurassic lincolnshire limestone and cretaceous chalk this indicates that the sandstone aquifers are better archives of information on palaeoconditions than the carbonate aquifers they show that atmospheric circulation patterns over britain have probably remained the same since the late pleistocene however 14c data from all four of the major aquifers emphasise the hiatus in recharge during periglacial conditions which occurred between the late pleistocene and early holocene

behaviour of boron and strontium isotopes in groundwater aquifer interactions in the cornia plain tuscany italy abstract the cornia plain alluvial aquifer in tuscany is exploited intensely to meet the demand for domestic irrigation and industrial water supplies the b concentration of groundwater however is often above the european limit of 1 mg l 1 with the result that exploitation of these water resources requires careful management boron and sr isotopes have been used as part of a study on the origin and distribution of b dissolved in groundwater and indirectly as a contribution to the development of appropriate water management strategies the geochemistry of the cornia plain groundwater changes from a hco3 facies in the inland areas to a cl facies along the coastal belt where seawater intrusion takes place the b concentration of groundwater increases towards the coastal areas while the 11b 10b ratio decreases this indicates that there is an increasing interaction between dissolved b and the sediments forming the aquifer matrix whose b content is in the order of 100 mg kg 1 adsorption desorption exchanges take place between water and the sediment fine fraction rich in clay minerals with a net release of b from the matrix into the groundwater and a consequent 11b shift from positive to negative values the aquifer matrix sediments therefore seem to be the major source of b dissolved in the groundwater the groundwater matrix interactions triggered by the ionic strength increase caused by seawater intrusion can also be detected in the ca na ion exchanges dissolved sr follows a trend similar to that of ca while the 87sr 86sr ratio is equal to that of the exchangeable sr of the aquifer matrix and therefore does not change significantly these results have helped to define a new strategy for groundwater exploitation with the final objective of reducing b concentration in the water extracted from the aquifer

radiocarbon application in dating complex hot and cold co2 rich mineral water systems a review of case studies ascribed to the northern portugal abstract the use of radioactive isotopes plays a very important role in dating groundwater providing an apparent age of the systems in the framework of the aquifers conceptual modelling making available important features about the water fluxes such as recharge horizontal flow rates and discharge in this paper special emphasis has been put on isotopic constraints in the use of 13 c and 14 c content as a dating tool in some hot 76 c and cold 17 c co 2 rich mineral waters discharging in the vilarelho da raia pedras salgadas region n portugal the radiocarbon content determined in these co 2 rich mineral waters 14 c activity from 4 3 up to 9 9 pmc is incompatible with the systematic presence of 3 h from 1 7 to 7 9 tu the 13 c values of the studied co 2 rich mineral waters indicate that the total c in the recharge waters is being masked by larger quantities of co 2 14 c free introduced from deep seated upper mantle sources this paper demonstrates that a good knowledge of mineral water systems is essential to allow hydrologists to make sound conclusions on the use of c isotopic data in each particular situation

tracing stream leakage towards an alluvial aquifer in a mountain basin using environmental isotopes abstract stream aquifer relationships in mountain basins are of great relevance because they control the water balance and with it the amount of resources whether surface water or ground water available for ecological and human demands in this paper this relationship is studied using environmental isotopes 18 o and d to identify the occurrence of stream recharge in the arbucies river basin ne spain isotopic data from 51 natural springs define the local altitudinal gradient this function is weighted by the proportional area above each point given by the hypsometric curve in order to estimate the isotopic stream water content as the contribution of runoff from incremental elevations stream water isotopes from two surveys are compared with hypsometrically averaged isotopic values to check for the appropriateness of this approach results show that it is more suitable when subsurface flows from surface formations such as alluvial deposits are the main contributors to stream discharge than when it derives from a single rainfall event the characterization of stream isotope values is used as a key factor in identifying stream leakage to an unconfined alluvial aquifer in the lower reach of the arbucies river

hydrogeochemical and isotopic constraints on the origins of dryland salinity murray basin victoria australia abstract combined hydrogeological and hydrogeochemical data allow flow systems and the origins of solutes in the honeysuckle creek area of the southeastern murray basin which is an area affected by dryland salinity to be constrained recharge occurs both on the uplands that are composed of fractured violet town volcanic rocks and the riverine plain that comprises sediments of the shepparton and coonambidgal formations groundwater from the violet town volcanics has low salinity 20 mmol l groundwater has intermediate cl br ratios 600 1000 which indicate that the high salinities do not simply result from halite dissolution rather mixing of groundwater homogenises cl br ratios and evaporation as a consequence of a shallow water table is the dominant process that increases salinity oxygen and h isotopes also indicate that mixing and evaporation have occurred these results indicate that land use over the whole region not just the uplands needs to be considered in any salinity management plans additionally future development of salinity is controlled by depth to the water table on the plains and the efficiency of recharge rather than by salt stores halite or brines in the unsaturated zone

flow paths and mixing properties of groundwater using hydrogeochemistry and environmental tracers in the southwestern area of jeju volcanic island summary groundwater from springs test boreholes and domestic wells was investigated to assess the flow system of basaltic aquifers at base flow conditions in the southwestern part of jeju island south korea this study utilized hydrogeochemical parameters and environmental tracers of 18 o 2 h 3 h and chlorofluorocarbons cfcs which showed that well connected flow paths exist between coastal springs regardless of flow rates in contrast test boreholes near the coastal springs exhibited various flow paths nitrate concentrations were much higher than baseline values in mountainous groundwater while those decreased in coastal areas was seemingly contributed from nitrate contamination sources and seawater sources were minimal due to low permeability layers near sea level the water stable isotopes indicated little evaporation and were comparable to the local meteoric water line during the rainy season which was confirmed by deuterium excess values demonstrating that effective infiltration primarily occurs during the rainy season from the effects of altitude on 18 o the mean recharge altitudes for both mountainous and coastal springs were estimated as 300 400 m which implies longer flow paths for the coastal springs the relationship of cfc 12 cfc 113 and that of cfc 12 3 h concordantly indicated that the groundwater consists mainly of binary mixtures composed of 15 25 year old young water and old water with ages greater than 60 years lower nitrate levels in the coastal springs were well represented by the mixing models recharge altitudes for coastal springs increased up to 700 m assuming that old water corresponds to high altitude recharge using the binary mixing model integration of hydrochemical and environmental tracer characteristics revealed that pahoehoe lava flows and hydrovolcanic tuffs play key roles in controlling the groundwater occurrence and quality

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

a hydrogeological and hydrochemical explanation of the groundwater composition under irrigated land in a mediterranean environment algarve portugal in the campina de faro in the south of portugal agricultural practices have a large impact on groundwater composition these practices involve pumping of water for irrigation from combinations of large diameter shallow wells noras and small diameter deep boreholes furos excess irrigation water returns to the aquifer and mixes with water from the regional groundwater flow system this irrigation return flow is concentrated by strong evapotranspiration and by flushing of fertilisers the concentration increase induces cation exchange whereby ca on the soil exchanger is replaced by na the mixing in the aquifer allows application of a mixing cell model which may then be used to calculate transmissivities from the cl mass balance the calculations are complicated by the time variant behaviour of cl and the method is adjusted to calculate the change of chloride in time results from the calculations appear to be in good agreement with hydrochemical observations

source of groundwater salinity in coastline aquifers based on environmental isotopes portugal natural vs human interference a review and reinterpretation environmental stable 18o 2h 13c and radioactive 3h and 14c isotopes together with geochemical data were used to identify the origin of salinization in different environments three case studies from sedimentary basins of continental portugal are presented i two at the meso cenozoic portuguese southern border algarve basin and ii one at the lower tagus lower sado basin central portugal with a new data interpretation groundwater salinization occurs in all three cases and may reach values of several grams of total dissolved solids per liter above accepted limits for drinking water the source of this high mineralization could be a seawater intrusion ancient or modern b dissolution from diapiric structures intruding on the aquifer systems c brine dissolution at depth and d evaporation of irrigation water the results obtained have provided an effective label for seawater and freshwater to enable seawater intrusion to be traced as well as the identification of other processes that might be responsible for groundwater salinization such as salt minerals dissolution and ion exchange

seawater intrusion and associated processes in a small coastal complex aquifer castell de ferro spain an attempt to identify the hydrogeochemical processes that accompany current or past intrusion of seawater in the castell de ferro coastal aquifer se spain was made using ionic deltas ionic ratios and saturation indices alluvial and coastal quaternary sediments and triassic marbles constitute this complex aquifer cation exchange dolomitization and calcite dissolution were identified as operating in the aquifer the cation exchange processes in the detrital materials are different from those in the marbles in addition it was determined that while the processes of marine intrusion associated with periods of low groundwater levels still persist in the detrital aquifer in the carbonate sector the flushing process characteristic of wetter conditions has begun

salinization of groundwater in arid and semi arid zones an example from tajarak western iran study of the groundwater samples from tajarak area western iran was carried out in order to assess their chemical compositions and suitability for agricultural purposes all of the groundwaters are grouped into two categories relatively low mineralized of ca hco3 and na hco3 types and high mineralized waters of na so4 and na cl types the chemical evolution of groundwater is primarily controlled by water rock interactions mainly weathering of aluminosilicates dissolution of carbonate minerals and cation exchange reactions calculated values of pco2 for the groundwater samples range from 2 34 10 4 to 1 07 10 1 with a mean value of 1 41 10 2 atm which is above the pco2 of the earth s atmosphere 10 3 5 the groundwater is oversaturated with respect to calcite aragonite and dolomite and undersaturated with respect to gypsum anhydrite and halite according to the ec and sar the most dominant classes c3 s1 c4 s1 and c4 s2 were found with respect to adjusted sar adj sar the sodium na content in 90 of water samples in group a is regarded as low and can be used for irrigation in almost all soils with little danger of the development of harmful levels of exchangeable na while in 40 and 37 of water samples in group b the intensity of problem is moderate and high respectively such water when used for irrigation will lead to cation exchange and na is adsorbed on clay minerals while calcium ca2 and magnesium mg2 are released to the liquid phase the salinity hazard is regarded as medium to high and special management for salinity control is required thus the water quality for irrigation is low providing the necessary drainage to avoid the build up of toxic salt concentrations