holocene climate optimum and last glacial maximum in the mediterranean the marine oxygen isotope record reconstructions with comprehensive estimates of confidence intervals are presented of changes in the w e stable oxygen isotope gradient in mediterranean surface waters between the holocene climate optimum and the present and between the last glacial maximum and the present rigorous statistical assessment is made of the significances of the mean geographic trends observed in these reconstructions firstly it is concluded that any reconstruction should strictly be based on values obtained by analyses of one single foraminiferal species throughout the basin as different species are found to respond with isotopic variations of different amplitudes to climatic hydrographic change this difference is tentatively related to differences between the habitats and seasons of growth of the various species secondly a significant increase of roughly a factor 3 is found in the mediterranean w e oxygen isotope gradient during the last glacial maximum relative to the present this difference is almost entirely due to increased glacial values in the levantine sea which are considered to be a result of a combination of increased evaporation rates and or somewhat cooler than anticipated surface water conditions thirdly an eastward increase of roughly half the present day magnitude is found for the w e oxygen isotope gradient during the holocene climate optimum values in the levantine sea appear to have undergone up to 0 3 more depletion than those elsewhere in the eastern mediterranean however no significant trends are found between the eastern and western parts of the levantine sea nor between values near the nile delta and those from elsewhere in the levantine sea the holocene climate optimum s eastward increase in the mediterranean oxygen isotope gradient although weaker than the present suggests that the mediterranean continued to function as a concentration basin albeit in a less vigorous way than today finally simple mixing arguments are used to argue that inferred oxygen isotope ratios of surface waters may not be used as an indication of conservative property e g salinity distribution on geological timescales but instead show amplitudes of response to climatic hydrographic changes that likely are 2 times larger than the corresponding amplitudes of response for truly conservative properties

a multidisciplinary approach for sustainable management of a complex coastal plain the case of sibari plain southern italy abstract coastal plain environments constantly adapt to change as a result of natural processes and increasing anthropogenic pressure as in the case of the low relief sibari coastal plain calabria southern italy in order to reconstruct the hydrostratigraphic framework and explain the spatial distribution of groundwater salinization of the sibari coastal plain an integrated hydrogeological and geochemical approach was applied to support an accurate conceptualisation and modelling of the whole plain groundwater system litho hydro stratigraphic relationships were constructed from lithologic logs obtained from exploratory boreholes whereas the groundwater flow system has been studied using conventional hydrogeological field investigations hydrochemistry and isotope hydrology three distinct hydrological units hu3 shallow aquifer hu2 aquitard and hu1 lower aquifer were identified showing distinct geometrical hydrochemical and isotopic signatures with the aim of explain the origin of na cl ca cl and na hco 3 waters were considered the role of ion exchange processes the results demonstrate that values of na mg 2 cl and so 4 can be attributed to seawater intrusion where k is probably the major pollutant of the shallow aquifer the adopted multidisciplinary approach provides an effective tool for accurately determination of groundwater processes and can be useful for a sustainable management of water resources in coastal plain the physically based model of the pail groundwater system was able to explain the observed groundwater salinity variations and to support a detailed long lasting numerical simulation of variations in the quantity and quality of groundwater resources

origin of groundwater salinity and hydrogeochemical processes in the confined quaternary aquifer of the pearl river delta china summary the pearl river delta prd located in the coastal area of south china contains a large confined quaternary aquifer this aquifer has been identified to have high concentrations of total dissolved solids ranging from 1 g l in the inland area to 26 8 g l near the southeast shoreline this work aims to investigate the origin of groundwater salinity and the major hydrogeochemical processes controlling the groundwater evolution in the confined basal aquifer of the prd a total of 40 boreholes were drilled in the prd during 2007 2009 and groundwater samples were collected for major ion ca 2 mg 2 na k nh 4 cl so 2 4 and hco 3 and isotope d 18 o d 2 h 3 h d 13 c and 14 c analyses these analyses demonstrate that groundwater in the confined basal aquifer is recharged by local rainwater and seawater and seawater is the major salinity source for groundwater the contribution of seawater varies from less than 1 in the inland areas to 74 near the shoreline so 2 4 reduction and methanogenesis occur in this reducing confined aquifer the results of ion exchange show that mg 2 exchanges mainly with the nh 4 ion which is derived from the mineralization of sedimentary organic matter ion exchange between na

inorganic isotopic and organic composition of high chloride water from wells in a coastal southern california aquifer abstract chloride concentrations were as high as 230 mg l in water from the surface discharge of long screened production wells in pleasant valley calif about 100 km nw of los angeles wells with the higher cl concentrations were near faults that bound the valley depending on well construction high cl water from different sources may enter a well at different depths for example cl concentration in the upper part of some wells completed in overlying aquifers influenced by irrigation return were as high as 220 mg l and cl concentrations in water sampled within wells at depths greater than 450 m were as high as 500 mg l these high cl waters mix within the well during pumping and produce the water sampled at the surface discharge changes in the major ion minor ion trace element and 34s and 13c isotopic composition of water in wells with depth were consistent with changes resulting from so4 reduction precipitation of calcite and cation exchange the chemical and isotopic composition of high cl water from deep wells trends towards the composition of oil field production water from the study area chloride concentrations in oil field production water present at depths 150 m beneath freshwater aquifers were 2200 mg l and cl concentrations in underlying marine rock were as high as 4400 mg l high cl concentrations in water from deeper parts of wells were associated with dissolved organic c composed primarily of hydrophobic neutral compounds believed to be similar to those associated with petroleum in underlying deposits these compounds would not be apparent using traditional sampling techniques and would not be detected using analytical methods intended to measure contamination

geochemical and boron strontium and oxygen isotopic constraints on the origin of the salinity in groundwater from the mediterranean coast of israel in order to identify the origin of the salinity and formation of saline plumes in the central part of the mediterranean coastal aquifer of israel we determined the elemental and boron strontium and oxygen isotopic compositions of fresh and brackish groundwater cl up to 1500 mg l we distinguish between two key anthropogenic sources 1 sewage effluents used for irrigation with high na cl so4 cl and b c1 ratios and low br cl ratios relative to seawater ratios low 11b values 0 10 and high 18o values 4 and 2 imported water from the sea of galilee that is artificially recharged to the aquifer with high br cl 3 10 3 and 18o values 1 and a low 87sr 86sr ratio of 0 70753 the brackish groundwater from the saline plumes have relatively low na cl ratios 0 5 0 8 and high ca mg mg cl and ca so4 hco3 1 ratios relative to seawater ratios marine so4 cl and br cl ratios 11b values of 24 8 49 9 18o of 2 95 to 4 73 and 87sr 86sr ratios of 0 708275 0 708532 the composition of most of the investigated groundwater from the saline plumes differs from those of the anthropogenic sources imported water fresh uncontaminated groundwater 87sr 86sr of 0 70866 11b of 20 30 and saline water from the adjacent eocene aquitard only in areas of artificial recharge does local groundwater have high br cl and 18o values that are typical to the sea of galilee the linear relationships between chloride and most of the ions including b and sr the relatively high 11b 30 and low 18 o 4 values and the chemical signature of the saline plumes e g marine br cl and so4 cl ratios suggest that 1 mixing processes control the chemical composition of the brackish water within the aquifer and 2 the saline postulated end member has a chemical composition that resembles modified seawater with a marine and higher 11b values and a 87sr 86sr ratio of 0 7083 we propose that most of the salinization phenomena and the formation of saline plumes in the inner parts of the coastal aquifer are derived from upconing of underlying natural saline water bodies and enhanced by overexploitation and draw down of the overlying fresh groundwater

continuous co 2 escape from the hypersaline dead sea caused by aragonite precipitation abstract chemical precipitation of caco 3 occurs in diverse marine and lacustrine environments in the hypersaline ca chloride lakes that have been occupying the dead sea basin since the late pleistocene caco 3 precipitated mostly as aragonite the aragonite sediments precipitated mainly during periods of high lake level stands as a result of mixing of bicarbonate rich freshwater runoff with dead sea brine that is ca rich and have high mg ca ratio during periods of arid conditions with limited freshwater inflow water level declined salinity increased and gypsum and halite became the dominant evaporitic minerals to precipitate the present study investigates the carbon cycle of the dead sea under the current limited water and bicarbonate supply to the brine representing periods of extremely arid conditions the decrease of inflows to the dead sea in recent years stems mainly from diversion of freshwater from the drainage basin and results in dramatic water level decline and massive halite precipitation during 2013 2014 bi monthly depth profiles of total alkalinity dissolved inorganic carbon dic and its isotopic composition 13 c were conducted in the dead sea from surface down to the bottom of the lake 290 m mass balance calculations conducted for the period 1993 2013 show that while inventories of conservative ions such as mg 2 remained constant the net dic inventory of the lake decreased by 10 dic supply to the lake during this period however amounted to 10 of lake s inventory indicating that during 20 years the lake lost 20 of its 1993s inventory compilation of historical data with our data shows that during the past two decades the lake s low dic 1 mmol kg 1 and very high pco 2 1800 ppm v remained relatively constant suggesting that a quasi steady state situation prevails in spite of the surprisingly stable dic and co 2 concentrations during this 20 year period 13 c dic increased significantly from 1 4 to 2 7 an isotopic mass balance calculation together with the high pco 2 of the brine show that during that period the lake lost about 3 7 10 10 moles of dic of which 60 by co 2 degassing and 40 by aragonite precipitation the deviation from the common 1 1 co 2 caco 3 ratio in most aqueous systems is facilitated by the dominance of the borate alkalinity of the dead sea nucleation and crystal growth experiments suggest that throughout this time the dead sea remained supersaturated with respect to aragonite a situation facilitated by combination of slow nucleation rates and absence of growth surfaces the very high pco 2 of the dead sea is maintained by the low co 2 piston velocity of the brine calculated to be only 4 5 m yr 1 more than an order of magnitude slower than seawater value

gypsum precipitation dissolution as an explanation of the decrease of sulphate concentration during seawater intrusion the precipitation of gypsum during the intrusion of seawater in a coastal aquifer is shown to be a possible cause of the decrease of the sulphate concentration with respect to the conservative freshwater seawater mixing observed in many field studies results of previously published laboratory column experiments and the application of a multicomponent reactive transport model show that gypsum precipitates during the first stages of seawater intrusion causing a decrease in sulphate concentration as the resultant front advances the water becomes undersaturated with respect to gypsum when the content of seawater 50 at that point water samples exhibit a deficit of sulphate of several mmol l in the range of the field values reported in papers on intrusion in coastal aquifers thus in addition to bacterial sulphate reduction by organic matter gypsum precipitation is a possible explanation for the non conservative behaviour of sulphate during seawater intrusion

sulfur isotope constraint on the provenance of salinity in a confined aquifer system of the southwestern nobi plain central japan abstract a combination of 34 s values and chemical compositions of brackish groundwater were used to examine the provenance of salinity in a confined aquifer system in the southwestern nobi plain central japan a tongue of brackish confined groundwater cl 1000 mg l which extends from the shoreline of ise bay inland has somewhat lower so 4 cl ratios and higher 34 s values 79 than those of the present seawater although the cation compositions of the brackish groundwater are consistent with values calculated for a mixture of fresh recharge water and seawater the anion compositions cannot be adequately interpreted as derived from such a mixing process alone using a rayleigh distillation model we found that the groundwater chemistry could be explained by sulfate reduction in combination with the mixing of two types of seawaters the present seawater and so 4 free seawater with the fresh recharge water the so 4 free seawater may consist mainly of fossil seawater that was trapped in an aquiclude for thousands of years model calculations based on cl and so 4 2 contents and 34 s values showed that the present and fossil seawaters compose at most 10 7 and 9 4 respectively of the brackish groundwater volume and the reduced so 4 2 content is up to 353 mg l in the confined aquifer the model s discrimination of the two seawaters is also in agreement with the spatial distribution patterns of groundwater composition from the west to the east in succession the main influence on the groundwater chemistry is fresh recharge water the present seawater and the fossil seawater moreover the area of intrusion of present seawater predicted by the model agrees well with the area of seawater intrusion determined from water quality data obtained a decade ago indicating that the model calculations can be reasonably used to discriminate quantitatively between present and fossil seawaters

the circulation of the dead sea brine in the regional aquifer abstract ca chloride brines have circulated between the lakes and the adjacent aquifers throughout the history of the dead sea lacustrine hydrology system the ein qedem eq hydrothermal saline springs system discharging at the western shores of the modern dead sea is the modern manifestation of this essential and continuous process the eq springs comprise the most significant source of ca chloride brine that currently discharges into the lake the chemical composition of eq brine has remained virtually uniform during the past ca 40 yr indicating that the brine represents a large groundwater reservoir the eq brine evolved from ancient ca chloride brine that occupied the tectonic depression of the dead sea basin during the quaternary during this period the composition of lake s brine was affected by mixing with freshwater and formation of primary minerals based on chronological and geochemical data we argue that the eq brine comprises the epilimnetic solution of last glacial lake lisan that penetrated and circulated through the adjacent judea group aquifer 14c and 81kr dating indicates recharge ages spanning the time interval of 40 20 ka coinciding with the period when the lake reached its highest stand of 200 30 m below msl at 31 17 4 ka and maintained a stable layered stratified configuration for a period of several ten thousand years the presented evidence suggests that the circulation of the ca chloride brine involves penetration into the aquifer during high stands eq brine recharge and its discharge back into the lake during the modern low stands 400 to 430 m below msl accordingly the mechanism of brine circulation between the lake and the marginal aquifers is related to the long term hydro climate history of the dead sea basin and its vicinity

misleading reconstruction of seawater intrusion via integral depth sampling summary saltwater intrusion in coastal aquifers is an urgent issue for the actual and future groundwater supply and a detailed characterization of groundwater quality with depth is a fundamental prerequisite to correctly distinguish salinization processes in this study interpolated cl maps of the po river delta coastal aquifer italy gained with integrated depth sampling ids and multi level sampling mls techniques are compared the data set used to build up the ids and mls interpolated cl maps come from numerous monitoring campaigns on surface and ground waters covering the time frame from 2010 to 2014 the ids interpolated cl map recalls the phenomenon of actual seawater intrusion with cl concentration never exceeding that of seawater and the absence of hypersaline groundwater all over the study area on the contrary in the mls interpolated cl maps the lower portion of the unconfined aquifer presents hypersaline groundwater making it necessary to consider salinization processes other than actual seawater intrusion like upward flux from a saline aquitard results demonstrate the obligation of using mls in reconstructing a reliable representation of the distribution of salinity especially in areas where the density contrast between fresh and saline groundwater is large implications of the reported field case are not limited to the local situation but have a wider significance since the ids technique is often employed in saltwater intrusion monitoring even in recent works with detrimental effect on the sustainable water resource management of coastal aquifers

saline intrusion and refreshening in a multilayer coastal aquifer in the catania plain sicily southern italy dynamics of degradation processes according to the hydrochemical characteristics of groundwaters the catania plain is a large alluvial depression which represents one of the most important hydrogeological units in eastern sicily a detailed hydrochemical and hydrogeological investigation focussed on its north eastern corner has provided new insights into the past and present relationship between freshwater and seawater in shallow and deep aquifers according to hydrochemical data over the last centuries the area has been affected by local variations of the sea level giving rise to sequential processes of re equilibration of the exchangeable complex involving freshwater and seawater in both surficial and deep aquifers these ongoing processes consist in the refreshening of both deep aquifers 500 m from the shoreline and to a lesser extent due to lower freshwater influx shallow aquifers in the former case there is a shift of the groundwater compositions towards the na hco3 type and a significant drop in the salt contents while in the latter case the salt contents do not drop significantly at a distance 500 m from the shoreline the exchangeable complex of deep aquifers is presently subject to salinization according to the temporal variabilities in the hydrochemical data over the period 1995 96 the apparent dualism can be attributed to a general worsening of the current freshwater seawater relationship in deep aquifers this new tendency appears to be related to a sharp increase in water consumption by the local industrial plant which has reversed the natural refreshening tendency giving rise to a new saline intrusion that is particularly severe close to the shoreline

investigation of seawater intrusion using stable and radioisotopes at coastal area south of beirut the capital of lebanon in this study field measurements were made and environmental isotopes and radiological properties were determined in six selected wells located in the coastal area south of beirut the capital of lebanon it is one of the many district areas in lebanon threatened by the penetration of seawater into aquifers two sampling campaigns were carried out to determine possible seasonal variations high electrical conductivity was observed ranging from 1080 to 7900 s cm the total dissolved solids values ranged from 530 to 5600 mg l this is attributed to a seawater intrusion confirmed by high chlorine concentrations that ranged from 400 to 3500 mg l isotope data for 18o 2h showed enrichment that is relatively small at the end of wet season due to recharge by local precipitation and infiltration carbon 14 ages and 234u 238u ratios confirmed the presence of young water no radiological hazard was observed as all values lay below the guidance levels of the who

sediment transport mechanisms revealed by quantitative analyses of seafloor morphology new evidence from multibeam bathymetry of the israel exclusive economic zone abstract this study synthesizes 15 years 2001 2016 of detailed multibeam hydrographic mapping covering the entire 26 500 km2 of the israeli exclusive economic zone eez multibeam data were collected on board three research vessels across the continental shelf slope and the deep levant basin between water depths of about 15 m to 2100 m single channel 3 5 khz seismic reflection chirp profiles were collected simultaneously with the multibeam surveys in selected parts of the area the new data enabled the first comprehensive quantitative seafloor morphological analysis of the slope and deep basin using gis techniques on the high resolution multibeam data we analyze the spatial distribution and quantitatively describe the seafloor morphologies in detail high resolution chirp seismic profiles demonstrate the underlying shallow structure results indicate that the seabed comprises five main morphologies folds faults sediment waves deepwater channels and sediment fan lobes quantitative morphological analysis and seismic data interpretation were used to derive field relations between these morphologies which along with previously collected multi channel seismic reflection data suggest that a concentric fold geometry formed around the nile outlet during the late pliocene to early pleistocene as part of a general thin skin radial salt tectonic deformation above the messinian mobile unit this radial motion was accompanied by displacement along nne trending strike slip faults in the basin and an extensional component across e w trending strike slip faults along the levant margin while some of these displacements continue to deform the modern seabed across area a others are covered by a wedge of quaternary deposits mainly in the northeastern part of the basin area b areas a and b also differ in grain size distribution as indicated by backscatter analysis of the multibeam data these observations divide the israeli eez into two distinct areas area a nile derived siliciclastic sediments transported directly into the deep basin via confined forming meandering channels and overbank deposits and unconfined flows forming fans and lobes the wedge consisting of area b was fed by erosion products of the nile outlet that were transported northwards along the continental shelf by seafloor currents of the levant jet system and glided down the northern levant continental slope as turbidity currents this supply built at least seven sequences of quaternary sediment waves that form upslope migrating cyclic steps the complete data coverage and quantitative morphological analysis presented here introduce new spatial and temporal constraints that call for a reexamination of previous seabed sampling locations not accounting for detailed bathymetry and to augment future seabed sampling efforts understanding the sediment supply paths across the basin and the geomorphological footprint of salt tectonics processes

salt precipitation and dissolution in the late quaternary dead sea evidence from chemical and δ 37 cl composition of pore fluids and halites abstract the chemical composition and 37 cl of pore fluids from the icdp core drilled in the deepest floor of the terminal and hypersaline dead sea and halites from the adjacent mount sedom salt diapir are used to establish the dynamics of halite precipitation and dissolution during the last interglacial and glacial periods between 132 and 116 thousand years ago ka halites precipitated in the lake resulting in the expulsion of na and cl from the residual solution over 50 of the cl reservoir was removed resulting in a decrease in the na cl ratio from 0 57 to 0 19 this process was accompanied by a decrease in 37 cl values in the precipitating halites and the associated residual cl in the lake the observed decrease fits a rayleigh distillation curve with a fractionation factor of nacl dead sea solution 0 32 0 12 determined in the present study this behavior implies negligible contribution of external sources of cl to the lake during the main peak of the last interglacial mis5e subsequently during the last glacial ca 117 to 17 ka dissolution of halite took place the na and cl inventory were replenished accompanied by an increase in na cl from 0 21 to 0 55 and in the 37 cl values from 0 46 to 0 12 while the lake underwent significant dilution during that time the decrease in salinity was somewhat suppressed by the dissolution of the halite which was mostly derived from mount sedom salt diapir

origin of groundwater salinity and hydrogeochemical processes in a confined coastal aquifer case of the rhone delta southern france the rhone delta south of france camargue 750 km2 is a coastal saline wetland located along the mediterranean sea the confined aquifer of this delta shows high values of electrical conductivity rising from the north 4 ms cm to the shoreline 58 ms cm this work aims to identify the origin of groundwater salinity and the geochemical processes occurring in this coastal confined aquifer according to the degree of salinity a natural tracing approach is considered using monthly sampling in 8 piezometers for chemical and isotopic analyses 18o 2h 13ctdic ionic and isotopic ratios demonstrate that strong salinities are due to a simple mixing between mediterranean seawater and freshwater seawater contribution reaches up to 98 at 8 km from the shoreline seawater intrusion induces a particular groundwater chemistry which varies with the degree of seawater contribution 1 in the less saline part of the aquifer seawater contribution 20 the intrusion induces so4 reduction which is confirmed by highly depleted 13ctdic values up to 19 the 13ctdic also reveals that methanogenesis processes may occur in the most reductive part of the aquifer due to so4 reduction the intrusion induces a shift in carbonate equilibrium leading to supersaturation with respect to dolomite and or magnesian calcite thus carbonate precipitation may occur in the area strongly influenced by seawater

isotopic and geochemical characterization of salinization in the shallow aquifers of a reclaimed subsiding zone the southern venice lagoon coastland summary the coastal plain bordering the southern venice lagoon is a reclaimed lowland characterized by high subsidence rate and ground level and water table depth below sea level in this agricultural region where the surface hydrologic network is entirely artificially controlled by irrigation drainage canals salinization problems have long been encountered in soils and groundwaters here we use isotopic and geochemical tracers to improve our understanding of the origin of salinization and mineralization of the semi confined aquifer 0 40 m and the freshwater inputs to this hydrological system water samples have been collected at different seasons in the coastal adriatic sea lagoon rivers and irrigation canals as well as in the semi confined aquifer at depths between 12 and 35 m 14 boreholes and in the first confined aquifer three boreholes drilled between 40 and 80 m depth stable isotopes 18 o and d and conductivity profiles show that direct saline intrusion from the sea or the lagoon is observed only in a restricted coastal strip while brackish groundwaters are found over the entire topographic and piezometric depression in the centre of the study area fresh groundwaters are found only in the most western zone the sharp isotopic contrast between the western and central regions suggests disconnected hydrological circulations between these two parts of the shallow aquifer the border between these two regions also corresponds to the limits of the most strongly subsiding zone our results can be interpreted in terms of a four end member mixing scheme involving 1 marine water from the lagoon or the open sea 2 alpine and pre alpine regional recharge waters carried either by the main rivers adige bacchiglione and brenta irrigation waters or by the regional groundwater circulation 3 local precipitation and 4 evaporated waters infiltrated from the surface infiltration from the surface is also revealed by the stratification of the electrical conductivity profiles showing that the brackish groundwaters are overlain by a shallow layer of less saline water all over the central depression in the first confined aquifer the groundwaters have isotopic compositions similar to the deep groundwaters of the venetian confined aquifers 40 400 m depth the isotopic data and the br cl ratio show that the origin of the salinization of the phreatic aquifer can be ascribed to seawater intrusion alone with no indication of the involvement of deep brines identified at 450 m depth in the process the chemical composition of the saline and brackish groundwaters is characterized by an excess of sodium and a deficit of calcium compared to conservative mixing between fresh groundwaters and seawater this suggests that the phreatic aquifer is progressively freshening as a consequence of the beneficial influence of the extensive irrigation drainage network including raised canals acting as a hydraulic barrier along the coast this freshening tendency may have been lasting since the reclamation in the mid twentieth century and has probably been accelerated by the ban on groundwater abstraction since the 1970s

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

morphological and structural relations in the galilee extensional domain northern israel the lower galilee and the yizre el valley northern israel are an extensional domain that has been developing since the miocene prior and contemporaneously to the development of the dead sea fault dsf it is a fan shaped region bounded in the east by the n s trending main trace of the dsf in the north by the bet kerem fault system and in the south by the nw se trending carmel fault the study area is characterized by high relief topography that follows fault bounded blocks and flexures at a wavelength of tens of km a synthesis of the morphologic structural relations across the entire galilee region suggests the following characteristics 1 blocks within the lower galilee tilt toward both the southern and northern boundaries forming two asymmetrical half graben structures opposite facing and oblique to one another 2 the lower galilee s neighboring blocks which are the upper galilee in the north and the carmel block in the southwest are topographically and structurally uplifted and tilted away from the lower galilee 3 the southern half graben along the carmel fault is topographically and structurally lower than the northern one combining structural and geological data with topographic analysis enables us to distinguish several stages of structural and morphological development in the region using a semi quantitative evolutionary model we explain the morpho structural evolution of the region our results indicate that the galilee developed as a set of two isostatically supported opposite facing half grabens under varying stress fields the southern one had started developing as early as the early miocene prior to the formation of the dsf the northern and younger one has been developing since the middle pliocene as part of the extension process in the galilee elevation differences between the two half grabens and their bounding blocks are explained by differences in isostatic subsidence due to sedimentary loading and uplift of the northern half graben due to differential influences of the regional folding d 2003 elsevier b v all rights reserved

high resolution insar constraints on flood related subsidence and evaporite dissolution along the dead sea shores interplay between hydrology and rheology abstract sinkhole generation and land subsidence are commonly attributed to dissolution of subsurface layers by under saturated groundwater and formation of cavities along the dead sea ds shorelines this process also involves seasonal flash floods that are drained into the subsurface by existing and newly formed sinkholes we quantify the contribution of flash floods to salt dissolution and land subsidence using high resolution interferometric synthetic aperture radar insar subsidence rates during a 3 year period 2012 2015 were calculated from 57 cosmo skymed x band interferograms bracketing major flood events and intra flood periods in 21 sinkhole sites the sites are located within channels and alluvial fans along the western shores of the dead sea israel the observed subsidence reaches maximum rates of 2 5 mm day accumulating in specific sites to 500 mm year in most of the sinkhole sites a gradual increase in the annual subsidence rate is observed during the 3 year study period three different modes of response to floods were observed 1 sites where floodwater is not directly channeled into sinkholes do not respond to floods 2 sites adjacent to active channels with sinkholes are unaffected by specific floods but their subsidence rates increase gradually from early winter to mid summer and decay gradually until the following winter and 3 sites in active channels with sinkholes are characterized by an abrupt increase in subsidence rates immediately after each flood by a factor of up to 20 and by a subsequent quasi exponential subsidence decay over periods of several months in these latter sites subsidence rates after each flood are temporally correlated with alternating groundwater levels in adjacent boreholes the rapid rise in groundwater head following floods increases the hydraulic gradient of the under saturated groundwater and hence also the groundwater discharge and the dissolution rate of the subsurface salt layer a subsequent quasi exponential water level drop results in similar deceleration in dissolution and subsidence rates with a similar characteristic decay time of about 150 days the observed subsidence decay pattern may also be explained by viscoelastic relaxation of the overburden in response to instantaneously formed dissolution cavities utilizing a kelvin viscoelastic model we show that the contribution of this process is most probably

origin of groundwater salinity and hydrochemical processes in an unconfined aquifer case of yang dai river basin in qinhuangdao china groundwater salinization has become a growing concern in yang dai river basin of qinhuangdao china where groundwater is commonly exploited for domestic industrial and agricultural uses in this study hydrochemical and physical parameters of groundwater were analyzed to identify the origin of groundwater salinity and the geochemical processes occurring in the unconfined aquifer groundwater types are ca mg hco3 so4 in the hills ca mg hco3 so4 in the piedmont plain and na cl in the coastal alluvial plain respectively electrical conductivity values varied between 322 and 3990 s cm chloride concentration attained to 942 mg l and the proportion of seawater intrusion in the coastal alluvial plain was 5 39 calculated by seawater fraction formal displaying the severe seawater intrusion cation exchange reactions and water rock interactions related to the dilution of halite gypsum dolomite and calcite occurred by ionic relationships during seawater intrusion high nitrate concentrations ranged from 35 6 to 686 5 mg l distributed in the hills and the south coastal alluvial plain where they are seriously polluted by the industrial wastewater agricultural fertilizers and domestic sewage seawater intrusion and nitrate contamination have common effects on the hydrochemical process in the south coastal alluvial plain therefore the origin of groundwater salinization was attributed not only to seawater intrusion but also to anthropogenic pollution in the study area this research provides useful information for groundwater salinization and water planning strategies in a coastal area

the cave of the letters sediments indication of an early phase of the dead sea depression abstract the highest aquatic sediments along the shoulders of the dead sea depression have been found in the cave of the letters nahal hever israel the cave has acted as a sediment trap preserving autogenic dolomite and detritic deposits the dolomitic sediment may correlate with late miocene dolomites within the rift valley the morphostratigraphic setting of the sediment implies deposition within an early topographic low that existed in the dead sea region since 10 to 7 ma

geochemical processes and solute transport at the seawater freshwater interface of a sandy aquifer geochemical processes occurring at a seawater freshwater interface were studied in a shallow coastal siliclastic aquifer containing minor amounts of calcite data were collected from 106 piezometers in a 120 m transect from the coastline and landward in the first 40 m from the coastline a wedge of saltwater is intruding below the freshwater aquifer the aquifer is strongly reduced with mineralization of organic matter by methanogenesis in the freshwater aquifer and sulfate reduction dominating in the most seaward part of the saline aquifer the spatial separation of cations in the aquifer indicated a slow freshening process where ca2 from freshwater displaced the marine cations na and mg2 from the exchanger complex the resulting loss of ca2 from solution decreases the saturation state for calcite and possibly causes calcite dissolution a storm flooding event was recorded where pulses of dense seawater sank through the fresh aquifer as a result the terminal electron accepting process switched from methanogenesis to sulfate reduction the pulses of sinking seawater also triggered cation exchange reactions where ca2 was expelled from the exchanger by seawater na and mg2 the released ca2 is being flushed from the aquifer by groundwater flow and this export of ca2 will in the long term cause decalcification of the sediment the water composition in the aquifer is in a transient state as the result of various processes that operate on different timescales oxidation of organic matter occurs continuously but at a rate decreasing on a geological time scale the freshening of the aquifer operates on the timescale of a few years the episodic flooding and sinking of seawater through the aquifer proceeds in the course of days to weeks but occurs irregularly with years in between

groundwater salinization in the azores archipelago portugal groundwater salinization in coastal regions causes severe constraints to water supply and economic losses to society worldwide in the azores archipelago groundwater abstraction in wells drilled in coastal aquifers is very important for water supply and quality problems have been reported therefore a groundwater chemistry dataset from wells was compiled to study groundwater salinization in these aquifers waters are mainly of the na cl type presenting a slightly acidic to slightly alkaline character with a ph between 5 63 and 8 50 median 7 40 electrical conductivity measurements range from 127 to 9 670 s cm median 862 suggesting highly variable mineralization with higher values observed on santa maria sao miguel pico graciosa and sao jorge islands the major ion composition reflects the contribution of seawater to the groundwater compositional evolution which is essentially explained by seawater intrusion into wells in many samples exchange reactions of na k for ca2 mg2 are associated with salinization the seawater fraction in groundwater composition reaches a maximum of 22 5 these results are extremely challenging to water managers in the azores because failure to comply with national water quality regulations and with european union groundwater directive requirements often occurs

upper mantle structure of shear waves velocities and stratification of anisotropy in the afar hotspot region abstract the afar area is one of the biggest continental hotspots active since about 30 ma it may be the surface expression of a mantle plume related to the african superswell central africa is also characterized by extensive intraplate volcanism around the same time 30 ma volcanic activity re started in several regions of the african plate and hotspots such as darfur tibesti hoggar and mount cameroon characterized by a significant though modest volcanic production the interactions of mantle upwelling with asthenosphere lithosphere and crust remain unclear and seismic anisotropy might help in investigating these complex interactions we used data from the global seismological permanent fdsn networks geoscope iris mednet geo fon etc from the temporary passcal experiments in tanzania and saudi arabia and a french deployment of 5 portable broadband stations surrounding the afar hotspot a classical two step tomographic inversion from surface waves performed in the horn of africa with selected rayleigh wave and love wave seismograms leads to a 3d model of both s v velocities and azimuthal anisotropy as well as radial s h s v anisotropy with a lateral resolution of 500 km the region is characterized by low shear wave velocities beneath the afar hotspot the red sea the gulf of aden and east of the tanzania craton to 400 km depth high velocities are present in the eastern arabia and the tanzania craton the results of this study enable us to rule out a possible feeding of the central africa hotspots from the afar plume above 150 200 km the azimuthal anisotropy displays a complex pattern near the afar hotspot radial anisotropy although poorly resolved laterally exhibits s h slower than s v waves down to about 150 km depth and a reverse pattern below both azimuthal and radial anisotropies show a stratification of anisotropy at depth corresponding to different physical processes these results suggest that the afar hotspot has a different and deeper origin than the other african hotspots darfur tibesti hoggar these latter hotspots can be traced down to 200 km from s wave velocity but have no visible effect on radial and azimuthal anisotropy

mount sedom salt diapir source for sulfate replenishment and gypsum supersaturation in the last glacial dead sea lake lisan abstract during the late quaternary several hypersaline lakes occupied the tectonic depression of the dead sea basin depositing sequences of primary evaporitic mineral phases aragonite caco3 gypsum caso4 2h2o and halite nacl aragonite and gypsum were the dominant primary mineral phases during the glacial periods and their formation required significant import of bicarbonate hco3 and sulfate so42 ions to the lake while bicarbonate was likely derived from dissolution of calcite in the watershed the sources of sulfate remained elusive here we investigate and quantify the long term sulfate reservoir changes in the deep waters hypolimnion of lake lisan the last glacial dead sea using concentrations and stable isotopes of sulfur in pore fluids from the cores that were drilled at the lake floor 2010 11 by icdp international continental drilling program from ca 117ka pore fluid sulfate concentrations increased and the brine attained supersaturation with respect to gypsum peaking during the last glacial maximum lgm ca 20ka stable isotopes of pore fluid sulfate 34s and 18o are similar to the values found in bulk sulfate minerals from the nearby mount sedom salt diapir we suggest that relatively diluted and cool paleo epilimnion water facilitated dissolution of halite and anhydrite caso4 of the mt sedom salt diapir resulting in a localized increase in solution density subsequently this solution sank and mixed with saline hypolimnion water simultaneously replenishing chloride sodium and sulfate reservoirs while diluting it with respect to other solutes the mixing of the calcium rich gypsum saturated hypolimnion and the sulfate rich sinking brine from above resulted in gypsum supersaturation

deciphering the interaction between quaternary and continental sabkhas aquifers in central tunisia using hydrochemical and isotopic tools climate aridity and intensive exploitation due to uncontrolled pumping for irrigation have caused a drastic decrease in the piezometric level of the shallow aquifer of chougafiya plain central tunisia and have seriously degraded groundwater quality according to the hydrochemical data cl so42 no3 hco3 br na mg2 k ca2 sr2 and the stable isotopes 18o and 2h content groundwater salinization in the investigated aquifer is caused by four main processes 1 evaporite dissolution 2 cation exchange reactions 3 evaporation processes and 4 mixing with sabkhas salt water causing salinity to increase in the central and southern parts of the basin the radiogenic 3h isotope data provided insight into the presence of significant contemporaneous recharge waters in the western part of the shallow aquifer the movement of the tritiated water may have occurred according to the general flow path nw se when tritium was used in conjunction with the stable isotopes and chloride the mixing process could be clearly identified especially in the central part of the study area

relationship between senonian and deep aquifers in southern tunisia abstract steady increase in the salinity of water resources and the decline in the groundwater level are the most widespread processes that degrade water quality and endanger future water exploitation in southern tunisia hydrological geochemical and environmental isotope data were evaluated to characterize the recharge conditions of the senonian aquifer and the flow pattern of groundwater mixing the results show that groundwaters can be classified into two major water facies ca so4 to mixed and na cl the main hydrogeochemical processes that typically control the groundwater mineralization are dissolution of evaporites halite gypsum and anhydrite evaporation cation exchange and mixing process related to the up flow leakage of deep groundwaters the stable isotope signatures reveal that the main part of groundwater is significantly affected by evaporation process wide range 4 5 to 8 4 and spatial heterogeneity of 18o in groundwater indicate that the aquifer is characterized by a slow process of natural groundwater in its lateral extent the 14c activity varies between 43 and 0 33 pmc the 13c contents of the total dissolved inorganic c tdic range between 10 8 and 3 6 the calculated 13c contents of the co2 in equilibrium with the tdic varying between 15 1 to 11 4 indicate two origins of c in solution the carbonate matrix 13c 2 and the soil co2 13c from 26 and 22 for the cultivated areas mean residence times have been determined after correction of the initial activities for dead c from the rock matrix the mean residence times confirm a modern recharge of the groundwater from dahar upland and indicate the presence of palaeowaters in the northern and southern parts of the basin detailed investigations on identifying the potential recharge zones flow paths of mixing and recharge conditions will be useful to protect the groundwater resources from depletion and salinization

sediment budget of the rhone delta shoreface since the middle of the 19th century this study analyses long term 1841 1872 1895 1974 changes in the grand rhone prodeltaic lobe to 1 quantify the accumulation 2 determine the evolution of relict prodeltaic lobes and 3 establish long term relationships between river sediment discharge the shoreface and the continental shelf our results show a reduction of the sedimentation of the prodeltaic lobe at the main river mouth since 150 yr by a factor of 3 7 12 63 to 3 41 10 6 m 3 yr 1 at the minor mouth of the river erosion dominates and speeds up during the same period 0 53 to 1 34 10 6 m 3 yr 1 these changes are found to directly result from the river sediment input decrease related to the natural decreasing of the frequency of major floods end of the little ice age the reforestation in the catchment area the dam construction and the dredging activities since the 1950s our results indicate that while there is large sediment accumulation in the area around a growing prodeltaic lobe there is also a reduced contribution of the river sediments to the non adjacent beaches of the mouth following a shift in the river channel and mouth the relict prodeltaic lobes petit rhone st ferreol bras de fer and pegoulier are reworked by waves and their sediments contribute partially to the growth of the spits espiguette beauduc and gracieuse this suggests that there is a time shift between the input of river sediment to the sea and the build up of a beach the chronic erosion of the coastline is likely to continue in the future since 1 a river shift is not possible because the river channels are controlled by dykes and human intervention 2 the decrease of river sediment input and 3 the relict prodeltaic lobes constitute sedimentary reservoirs that are gradually being used up 2006 published by elsevier b v

holocene stratigraphy of the dead sea correlation of high resolution seismic reflection profiles to sediment cores the northern basin of the dead sea is occupied by a 300 m deep lake a series of cores in the deep water part of the lake provide information about the top 365 cm of the sediments the cores were correlated with high resolution 3 5 khz seismic profiles from this area and provide lithologic and age constraints for the high resolution seismic reflection data visual comparison of the two data sets shows that strong surface and shallow subsurface reflectors a and b correlate to the massive salt at the seafloor surface and the indurated salt at the base of the cores respectively calculations of an average seismic velocity based on the interval between these reflectors and the corresponding sedimentary thickness yield an average 3500 m s velocity this agrees closely with velocities determined from direct measurements of compressional velocities for sediment samples ultrasonic wave velocity measurements of salt samples from the cores and dry rock salt cores from the southern basin of the dead sea indicate that wave velocities are independent of the burial depth at shallow depths however velocities show strong dependence on porosity at low hydrostatic pressure a reduction in porosity as well as closure of microcracks in the crystals cause an increase in the velocities this increase disappears at higher stress levels synthetic seismograms of the upper 3 ms and the entire 25 ms penetrated by the seismic profiles reinforce the lithologic and seismic stratigraphic correlation and confirm that prominent reflectors in the basin represent the top boundary of halite layers which are separated by laminated sequences of evaporites and elastics the salt in the upper salt sequence is deposited at a very fast rate of more than 20 mm yr however at shallow depths considerable compaction takes place variations in appearance and velocities of the upper salt sequence and middle salt sequence indicate that the porous granular and fine grained precipitates of the surface salts are diagenetically altered to a coarse and compact crystalline aggregate by re solution and crystallization with burial the sedimentary sequences recovered in the cores suggest that significant lake level fluctuations took place in the past in response to climatic changes the detailed correlation of the cores and seismic profiles makes it possible to extrapolate climatic data from earlier periods beneath the maximum core penetration by analyzing the seismic stratigraphic sequences of the seismic reflection data

hydrochemical and statistical studies of the groundwater salinization in mediterranean arid zones case of the jerba coastal aquifer in southeast tunisia coastal aquifers are considered as major sources for freshwater supply worldwide especially in arid zones the weak rainfall as well as the intensive extraction of groundwater from coastal aquifers reduce freshwater budget and create local water aquifer depression causing both seawater intrusion and a threat to groundwater this phenomenon was observed in the jerba island which is located in southeast tunisia jerba s unconfined aquifer shows high values of groundwater salinity reaching locally 17 g l and a strong contrast between some zones of the aquifer high pumping rates and weak recharge disturb the natural equilibrium between fresh and saline water causing water salinization in most areas of the island this study aims at establishing the salinity map of the aquifer and identifying the origin of groundwater salinization the salinity map shows that zones characterized by low groundwater salinity are located in the center of the study area high groundwater salinities are observed near the coast and in some parts having low topographic and piezometric levels groundwater geochemical characterization and br cl and na cl ratios suggest that the origin of abnormal salinity is seawater intrusion considering groundwater salinity values and br concentrations a seawater intrusion map is established it shows that many areas of the unconfined aquifer are contaminated by mixed groundwater and seawater the statistical analysis demonstrates that high mineralization of the groundwater is due to gypsum and carbonate dissolution coupled with the mixed groundwater and seawater in many areas

digital topography and bathymetry of the area of the dead sea depression abstract the dead sea depression occupies the central part of that segment of the syrian african rift extending from the mountains of southern lebanon to the arava valley north of the gulf of aqaba on the red sea the lowest continental feature in the world it encloses the dead sea whose surface now lies at about 409 m this shrunken sea consists of a shallow southern basin occupied by evaporation pans and a northern basin 50 km in length by 13 17 km in width with a flat floor some 731 m below msl the depression is asymmetric with the mountains to the east being up to 500 m higher the closed depression has two outlets one at 60 5 m altitude into the mediterranean via the jezreel valley near afula and a second into the red sea at about 200 m altitude in the arava valley a digital terrain model dtm based upon the local 1 50 000 scale topographic maps and modern bathymetric surveys gives elevations to decimeter resolution on a grid with 25 m spacing when visualized as shaded relief or in coloured hypsometric format the dtm graphically shows the overall morphology and its many features these include the local tectonics from the major boundary faults to the associated subsidiary faults and lineaments and their possible relationships with the incised canyons offshore also clearly visible are the volcanic cones on the golan heights the coast paralleling kurkar ridges and the halokinetic disruptions to the deep offshore topography the dtm was used to compute a hypsometric curve for the closed depression from 731 m to 60 m the maximum area and volume of a lake extending to the afula spillway would be 5985 km 2 and 1602 km 3 respectively inflection points were observed at 715 m where the dead sea s flat bottom meets its steep flanks at 385 m where the northern basin meets the flat floor of the southern basin and surrounding plain at 228 with the step up to the basin of the sea of galilee and at mediterranean sea level

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

earthquake induced barium anomalies in the lisan formation dead sea rift valley israel prominent barium concentration anomalies that appear within earthquake brecciated layers seismites in the late pleistocene lacustrine lisan formation in the dead sea basin dsb are described and discussed here for the first time chemical analyses of samples from vertical profiles through the seismites display asymmetric ba concentration peaks the peaks start a few centimeters above the seismite s base and gradually rise to maxima reaching some 1000 ppm ba before falling off to background values around 100 ppm or abutting against the upper boundary of the breccia layer high resolution sem and electron microprobe analyses disclose that the ba in the anomalies resides within prismatic crystallites mostly 2 m in length composed of a ba sr so4 mineral designated bm henceforth these are lacking altogether in the normal non seismic underlying and overlying sediments the crystallites are much smaller than the adjacent supporting matrix grains of the gradually bedded seismite and show no size sorting relationship with the latter the peaks of the anomalies reflect higher population density rather than larger crystal sizes of the bm crystallites therein mass balance calculations show that the mass of ba2 dissolved in the lake above a unit area of the seismites was mostly several times larger than that found in the seismite the concentration of ba2 in dsb ca chloride brines is mostly lesser than that in the dsb lake ruling out the former as a source of ba to the anomalies we propose that during earthquakes the uppermost bottom sediment layers in the dsb lake were shaken and re suspended into the overlying brine the larger faster settling fragments and grains remained almost intact or were rapidly removed unaffected from the slurry however the finer grains remained in suspension for longer periods allowing nucleation and growth of bm crystallites on their surfaces from the surrounding brine before reaching the bottom the lag of ba trapping behind the breccia accumulation and the asymmetrical peak shapes of the anomalies are accounted for by decreasing dilution of the ba rich finer particles by ba poor coarse grains during seismite accumulation as reflected by the graded bedding of the seismite layers the supply rate of ba2 to the lake by freshwater and brines was more than sufficient to account for the buildup of ba in recurring seismites separated by seismically quiescent intervals as short as 100 yr

hydrochemical effects of saltwater intrusion in a limestone and dolomitic limestone aquifer in lebanon this study demonstrates groundwater quality differences between a limestone and a dolomitic limestone sub oxic coastal aquifer in the eastern mediterranean lebanon with and without ongoing moderate salinization since the last decades for this purpose 8 major and 50 trace elements tes were analyzed in 80 water and 65 rock samples and interpreted with a quad fold approach utilizing 1 nonparametric statistical tests 2 concentration deviations from ideal conservative freshwater seawater mixing lines 3 a new parameter called mixing enrichment factor to assess the mobility of chemical constituents under salinizing conditions and 4 1 d dual porosity flow path modeling with phreeqc dissolution precipitation of caxmgysrzco3 and cation exchange were the main disclosed hydrogeochemical processes besides minor signs of organic matter oxidation in the dolomitic limestone aquifer less carbonate dissolved as compared to the limestone aquifer partly because of lower pco2 in addition to seawater inflow triggering mg calcite precipitation by cation exchange saltwater intrusion led to mobilization of as ba cu ni rb sr and u in both aquifers sometimes likely by cation exchange e g ba and sr some of these tes notably cu and ni recorded higher concentrations in the dolomitic limestone regardless of salinization other elements like al be ce cr nb pb v y and zr revealed no or a low mobilization tendency the concentration of all tes in groundwater remained below drinking water limits notwithstanding moderate salinization this classifies carbonate rocks as a weak geogenic source of tes whereas encroaching seawater appears to be a more important source

bromine and iodine in peru margin sediments and pore fluids implications for fluid origins at the peruvian convergent margin two distinct pore fluid regimes are recognized from differences in their cl concentrations the slope pore fluids are characterized by low cl concentrations but elevated br and i concentrations due to biogenic production the shelf pore fluids exhibit elevated cl and br concentrations due to diffusive mixing with an evaporitic brine in the slope pore fluids the br i and nh4 concentrations are elevated following bacterial decomposition of organic matter but the i concentrations are in excess of those expected based on mass balance calculations using nh4 and br concentrations the slope sediment organic matter which is enriched in iodine from oxidationreduction processes at the oxygenated sediment water interface is responsible for this enrichment the increases in dissolved i and the i enrichments relative to nh4 and br correlate well with sedimentation rates because of differential trapping following regeneration the pore fluid i br ratios suggest that membrane ion fiitration is not a major cause of the decreases in cl concentrations other possible sources for low cl water including meteoric water clathrate dissociation and or mineral dehydration reactions imply that the diluting component of the slope low cl fluids has flowed at least 1 km through the sediment the low bottom water oxygenation in the shelf is responsible for the low if any enrichment of iodine in the shelf sediments fluctuations in bottom water oxygen concentrations in the past however may be responsible for the observed variations in the sediment ibr ratios comparison of na cl and br cl molar ratios in the pore fluids shows that the shelf high cl fluid formed from mixing with a brine that formed from seawater concentrated by twelve to nineteen times and probably was modified by halite dissolution this dense brine located below the sediment sections drilled appears to have flowed a distance 500 km through the sediment

modelling precipitation streamflow processes in karst basin the case of the jordan river sources israel summary a system approach daily precipitation streamflow model was developed for both the base and the surface flow components of large scale karst basins long term streamflow data were separated to baseflow and surface flow using the recursive digital filter method which provides time series for model calibration the hydrological model for karst environment hymke includes attributes to large scale preferential flow that recharge the groundwater and solve the problem of uncorrelated baseflow and surface flow in a karst environment hymke was applied simultaneously to the three major tributaries of the upper catchment of the jordan river which originate in the karstic region of the hermon mountain northern israel it was verified by comparing the calculated surface flow and baseflow with the daily time series of the baseflow separation procedure and demonstrated good agreement of both the surface r2 0 6 and baseflow r2 0 77 components of each stream

a 45 kyr laminae record from the dead sea implications for basin erosion and floods recurrence abstract recording and analyzing how climate change impacts flood recurrence basin erosion and sedimentation can improve our understanding of these systems the aragonite detritus laminae couplets comprising the lacustrine formations that were deposited in the dead sea are considered as faithful monitors of the freshwater supply to the lakes we count a total of 5600 laminae couplets deposited in the last 45 kyr mis3 mis1 at the dead sea center which encompass the upper 142 m of the icdp core 5017 1 the present study shows that aragonite and detritus laminae are thinner and occur at high frequency during mis 3 2 while they are much thicker and less frequent during mis 1 by analyzing multiple climate connected factors we propose that significant lake level drops enhanced dust input and low vegetative cover in the drainage basin during the last deglaciation 22 11 6 ka have considerably increased erodible materials in the dead sea watershed we find a decoupling existed between the significant lake level drop lake size reduction and lamina thickness change during the last deglaciation we argue that during the last glacial and the holocene the variation of lamina thickness at the multiple millennium scale was not controlled directly by the lake level size change we interpret this decoupling implying the transport capacity of flash floods is low and might be saturated by the oversupply of erodible materials and indicating a transport limited regime during the time period we suggest the observed thickness and frequency distribution of aragonite detritus laminae points to the high frequency of small magnitude floods during the last glacial in contrast to low frequency but large magnitude floods during the holocene

active faulting in the dead sea rift abstract manifestations of late quaternary and holocene faulting were studied in a 500 km long segment of the dead sea transform rift most prominent are left slip faults whose characteristic physiographic features are recognizable along most of the studied segment where these faults bend or are stepped to the left rhomb shaped grabens or pull aparts are produced forming depressions in the reverse situation compressional features such as pressure ridges domes and folds form positive topographic features such structures are combined on a variety of scales ranging from a few hundred meters long to tens of kilometers normal faults sub parallel to the left slip faults produce a trough like valley along much of the dead sea transform but are most prominent along the margins of the large rhomb grabens e g the dead sea trough they apparently record a small component of transverse extension generally their motion is slow young slip did not occur along some segments during the last few 10 4 y elsewhere throws of 10 20 m at least occurred in this period the dead sea transform is seismically active the instrumental and historic records indicate a seismic slip rate of 0 15 0 35 cm y during the last 1000 1500 y while estimates of the average pliocene pleistocene rate are 0 7 1 0 cm y either much creep takes place or the slip rate varies over periods of a few 10 3 y

processes affecting groundwater chemistry in a zone of saline intrusion into an urban sandstone aquifer abstract samples have been collected from inflows into railway tunnels in the triassic sandstone aquifer beneath liverpool and the mersey estuary england u k these provide a profile through a saline freshwater mixing zone analyses were made of major anions and cations 34s and 18o in so4 13c in dissolved inorganic c and 87sr 86sr the data demonstrate that the presence of a low permeability fault exerts a strong control on the local groundwater chemistry on the estuary side of the fault groundwater chemistry is dominated by mixing of intruding estuary water which is modified by so4 reduction and calcite dissolution with fresh groundwater the environment of so4 reduction in the tidal estuary is one of repeated reduction and re oxidation of s in an open system and has resulted in virtually no change in s isotopic composition but an enrichment in residual so4 18o of 1 5 groundwater chemistry on the landward side of the fault is primarily the result of recharge in an urban environment there is also evidence that saline water has been present in this region of the aquifer in the past and that this has now been flushed by fresh groundwaters this saline water was either transported along the landward side of the fault from nearer the estuary or more probably transmitted across the fault both mechanisms would have been driven by large landward head gradients caused by heavy industrial abstraction earlier this century this has produced a zone of groundwaters depleted in ca and radiogenic sr and enriched in na as a result of ion exchange between the fresh groundwaters and the aquifer previously occupied by more saline water sulphur isotopic composition however shows no variation since so4 does not undergo significant ion exchange a tracer test from a borehole to the tunnels showed multiple breakthroughs to some locations indicating a number of different flow paths through the aquifer the maximum flow velocity recorded in this test was 140 m d suggesting flow along fractures

occurrence and mobilization of radium in fresh to saline coastal groundwater inferred from geochemical and isotopic tracers sr s o h ra rn abstract salinization in groundwater systems can induce water rock interaction including the release of naturally occurring trace elements of health significance such as radium ra with possible implications for the usability of water resources in addition to the increase of dissolved solids tds concentrations in general radium mobility is limited by chemical removal mechanisms including adsorption onto clays and or mn and fe oxides exchange processes and coprecipitation with secondary barite in order to examine the effect of aquifer salinity gradients on the distribution of naturally occurring ra in fresh to saline groundwater and the relationship to water rock interaction and ra removal mechanisms two contrasting systems were investigated the shallow unconfined coastal aquifer in agadir southwestern morocco and the confined cretaceous cape fear and pliocene yorktown aquifers of the atlantic coastal plain north carolina usa geochemical and isotopic indicators of salinity sources e g cation ratios 18o 2h br cl 34 s so 4 2 18 o so 4 2 were used to identify the relative contributions of seawater and other saline waters and subsequent geochemical modification by water rock interaction radium activities 224ra 226ra 228ra radon 222 alkaline earth metal mg ca sr ba concentrations and ratios and 87sr 86sr ratios were analyzed to identify water rock interaction processes affecting alkaline earth metals including ra the morocco coastal aquifer is generally oxic exhibits a range of salinity and water types cl 163 2120 mg l median 932 mg l and exhibits ca na ratios above the seawater value typical of monovalent divalent cation exchange base exchange reactions in coastal aquifers in contrast the atlantic coastal plain aquifers are anoxic sulfate reducing cover a wider salinity range cl 5 9890 mg l median 800 mg l representing a transition between na hco 3 and na cl waters and exhibit ca na ratios below that of modern seawater typical of reverse base exchange reactions possible salinity sources in the morocco coastal aquifer include seawater intrusion mesozoic evaporites other natural saline waters and or wastewater whereas the atlantic coastal plain is primarily affected by old seawater present in the aquifer system radium activities are generally low and vary significantly within each aquifer for example 226ra ranges from 1 8 27 7 mbq l in the morocco coastal aquifer median 8 1 mbq l and 1 9 214 mbq l in the atlantic coastal plain median 18 9 mbq l the highest ra activities were observed in the most saline wells sampled in the atlantic coastal plain at total dissolved solids tds concentrations above an apparent threshold of 5000 mg l radium activities increase in a generally linear fashion with salinity in the atlantic coastal plain broadly comparable to previous studies indicating a threshold range of 3000 10 000 mg l at lower tds concentrations water rock interaction processes that vary with local aquifer conditions appear to control ra distribution rather than merely salinity in the morocco coastal aquifer adsorption of ra and coprecipitation with secondary barite are apparently favorable to control ra levels in groundwater radium removal in the anoxic atlantic coastal plain aquifers appears to be associated with adsorption and or exchange processes with the additional possibility of barite precipitation in the cape fear aquifer indicated by barite saturation overall the locally variable factors that can control ra sources and mobility in fresh to brackish groundwater at near neutral ph include variation in solid phase radioactivity redox state affecting adsorption sites availability of competing divalent cations and barite saturation

hydrogeochemical characteristics in coastal groundwater mixing zone abstract this study presents the hydrogeochemical analysis in coastal groundwater mixing zone of a sandy aquifer ting kok hong kong groundwater samples collected along a sampling transection that covers the salinity transition zone were analyzed for spatial and temporal distribution of major ions cl so 4 2 na k mg 2 and ca 2 and ancillary parameters such as salinity ph temperature and total alkalinity the seawater freshwater interface sfi based on different ions ionic delta of major ions phreeqc based saturation index si of minerals are used to systematically investigate geochemical processes such as cation exchange precipitation dissolution of minerals and sulfate reduction under the effect of seasonal hydrologic variation compared to cl based sfi the landward movements of cation based sfi and seaward movement of so 4 2 based sfi indicate that the coastal aquifer serves as the source of cations and sink of so 4 2 for groundwater the sfi is sensitive to seasonal hydrologic variation due to the variation of land sea hydraulic gradient the cation exchange and precipitation dissolution of minerals are dynamic and complex in coastal groundwater mixing zone the simultaneous enrichment of all cations is found in the aquifer due to external input of a specific cation the sulfate reduction is responsible for so 4 2 depletion and also the enrichment of total alkalinity in coastal groundwater mixing zone because gypsum precipitation does not occur according to mineral si analysis the cation exchange is very sensitive to the seasonal hydrologic variation while the sulfate reduction is not obviously influenced

combining boron isotopes and carbamazepine to trace sewage in salinized groundwater a case study in cap bon tunisia abstract the korba aquifer on the east coast of cape bon has been overexploited since the 1960s with a resultant reversal of the hydraulic gradient and a degradation of the quality due to seawater intrusion in 2008 the authorities introduced integrated water resources planning based on a managed aquifer recharge with treated wastewater water quality monitoring was implemented in order to determine the different system components and trace the effectiveness of the artificial recharge groundwater samples taken from recharge control piezometers and surrounding farm wells were analyzed for their chemical contents for their b isotopes a proven tracer of groundwater salinization and domestic sewage and their carbamazepine content an anti epileptic known to pass through wastewater treatment and so recognized as a pertinent tracer of wastewater contamination the system equilibrium was permanently disturbed by the different temporal dynamics of continuous processes such as cation exchange and by threshold processes linked to oxidation reduction conditions the b isotopic compositions significantly shifted back and forth due to mixing with end members of various origin under the variable contribution of meteoric recharge the plio quaternary groundwater 11b of 35 40 6 a mean b concentration of 30 mol l no carbamazepine n 7 was subject to seawater intrusion that induced a high 11b level 11b of 41 5 48 0 a mean b concentration of 36 mol l and n 8 fresh groundwater 11b of 19 89 b concentration of 2 8 mol l no carbamazepine was detected close to the recharge site and may represent the deep miocene pole which feeds the upper plio quaternary aquifer the managed recharge water 11b of 10 67 13 8 n 3 was brackish and of poor quality with a carbamazepine content showing a large short term variability with an average daily level of 328 61 ng l a few piezometers in the vicinity of the recharge site gradually acquired a b isotopic composition close to the wastewater signature and showed an increasing carbamazepine content from 20 to 910 ng l the combination of b isotopic signatures with b and carbamazepine contents is a useful tool to assess sources and mixing of treated wastewaters in groundwaters effluent quality needs to be greatly improved before injection to prevent further degradation of groundwater quality

tectonic analysis of the dead sea rift region since the late cretaceous based on mesostructures we have measured the orientations of small faults slickensides tectonic stylolites vein with secondary mineralization small folds and dikes in israel and sinai these structures are indicators of paleo stress or strain and provide the pattern of tectonic deformation data were collected at 130 stations most with tens of separate measurements most stations showed consistent deformation stations were located on exposures ranging from precambrian crystalline rocks to pleistocene sediments we have defined two tectonic stress fields each relatively uniform in both time and space one stress field with dominating maximum horizontal compression trending w to wnw in the late cretaceous to eocene rocks in the folds and plateaus west of the dead sea rift the second field with dominating horizontal extension trending e to ene in all rocks inside the rift and proximal thereto the first stress field is called the syrian arc stress and the second is called the dead sea stress a change in style of tectonic deformation which corresponds to the two stress fields is manifested also in the major structures in israel the late cretaceous to neogene deformation is characterized by long wavelength folds and monoclines whereas the neogene to recent deformation is characterized by normal and strike slip faults and volcanic activity

rising of the lowest place on earth due to dead sea water level drop evidence from sar interferometry and gps 1 the dead sea water level has been dropping at an exceedingly increasing rate since 1960 and between 1993 and 2001 the interval of the insar data examined in this study it has dropped at an average rate of 0 88 m per year such a water level change could potentially give rise to a resolvable lithospheric rebound and regional uplift with spatial extent and amplitude that are controlled by the effective mechanical properties of the crust and upper mantle combined we measure that deformation for the years 1993 to 2001 using 149 short baseline interferograms made of 31 ers 1 and ers 2 synthetic aperture radar sar images and continuous gps data from the survey of israel recorded between 1997 and 2011 the uplift rate at the dead sea is small up to 4 mm year and the basin topography is almost a mirror of the displacement introducing a strong trade off between uplift and stratified atmosphere noise to overcome this complication we impose a linearity constraint on the satellite to ground line of sight los phase changes based on the steady uplift observed by a continuous gps station in the area of interest and simultaneously solve for the los change rate digital elevation model dem errors and the elevation phase correlation while the los rate and dem errors are solved for each pixel independently the elevation phase correlation is solved for each sar acquisition independently using this approach we separated the stratified atmospheric delay from the ground displacement we observed a regional uplift around the dead sea northern basin with maximum uplift close to the shorelines and diminishing to zero by the mediterranean coast we modeled the effect of water load changes using a homogeneous elastic half space and found a good agreement between modeled and observed ground displacements using elastic properties that are compatible with seismic and gravity data down to a depth of 15 km below the dead sea basin suggesting that the response of the crust to the sea level drop is controlled mainly by the elastic properties of the upper crust immediately below the dead sea basin

an assessment of the seawater effect by geochemical and isotopic data on the brackish karst groundwater from the karaburun peninsula izmir turkey the study area is located in the center of the karaburun peninsula turkey where several karstic springs discharge near the coast 0 2 m above the sea level the most important discharge points are the ildiri and gerence springs groundwater obtained from ildiri springs and several drill wells provide water to the region during the summer periods the electrical conductivity values are between 1900 and 3900 s cm springs are slightly salty and are not used directly as drinking water salinity was observed in the spring waters under natural flow conditions the salinity values of the drillings and springs were measured in dry and wet seasons spring waters have conductivity values between 3000 and 4000 s cm preliminary surveys reveal that seawater contribution to ildiri springs is 6 5 maximum gerence spring waters discharge to the surface from a region very close to the sea the dominant cation is na and the dominant anion is cl conductivity values were between 7000 and 13 000 s cm gerence spring waters discharge to the sea with seawater contributions ratios between 8 5 and 20 3 depending on the seasonal changes while some spring waters discharge 0 5 1 0 m above sea level the rest of them discharge directly into the sea salinization of gerence spring water is higher than the other springs

multivariate statistical analysis and hydrogeochemical modelling of seawater freshwater mixing along selected flow paths case of korba coastal aquifer tunisia abstract groundwater sampling and piezometric measurements were carried out along two flow paths corresponding to two transects in korba coastal plain northeast of tunisia the study aims to identify hydrochemical processes occurring when seawater and freshwater mix those processes can be used as indicators of seawater intrusion progression and freshwater flushing into seawater accompanying submarine groundwater discharge sgd seawater fractions in the groundwater were calculated using the chloride concentration hierarchical cluster analysis hca was applied to isolate wells potentially affected by seawater in addition phreeqc was used to simulate the theoretical mixing between two end members seawater and a fresh brackish groundwater sample geochemical conventional diagrams showed that the groundwater chemistry is explained by a mixing process between two end members results also revealed the presence of other geochemical processes correlated to the hydrodynamic flow paths direct cation exchange was linked to seawater intrusion and reverse cation exchange was associated to the freshwater flushing into seawater the presence of these processes indicated that seawater intrusion was in progress an excess of ca that could not be explained by only cation exchange processes was observed in both transects dedolomitization combined to gypsum leaching is the possible explanation of the groundwater ca enrichment finally redox processes were also found to contribute to the groundwater composition along flow paths

coupled hydrogeochemical modelling using kirmat to assess water rock interaction in a saline aquifer in central eastern tunisia abstract to quantify water rock interactions and forecast their spatiotemporal evolution in the shallow aquifer of sidi el hani located in central eastern tunisia the numerical code kirmat was used based on available geological mineralogical thermodynamic kinetic and hydrodynamic data the model was built and calibrated on two transects of the aquifer oriented along the flow lines of groundwater the numerical results show that the interactions between water and rock are responsible for groundwater salinity which is strongly dominated by chlorides sodium and sulphates the variations of dissolved species in space and time are the result of halite dissolution anhydrite and gypsum dissolution and precipitation calcite dissolution and dolomite precipitation the precipitation of dolomite can locally induce a reduction in permeability and further enhance an increase in leaching because the residence time between rock and water will be amplified three numerical sensitivity studies have been conducted to evaluate the influence of water rock interactions on groundwater salinization the study highlights the finding that the modelled fate of dissolved species in the unconfined aquifer is rather sensitive to the darcy velocity but not very sensitive to the initial volume fractions of minerals in the two transects and the composition of groundwater injected at the upstream boundary

hydrodynamic analysis of a mediterranean aquifer system with the use of hydrochemical and isotopical analysis as supporting tools the management of groundwater resources in coastal environments within the mediterranean basin has become of paramount importance especially in the light of global changes a typical example of such a hydrosystem is the lavrio basin in greece this research site involves two aquifer types granular and karstic formations that are hydraulically interconnected furthermore the proximity to the sea and the abstractions for irrigation and drinking water supply have led to the phenomenon of seawater intrusion the present study aims at analyzing the hydraulic hydrological and hydrogeological conditions of the area by means of hydrochemical and isotopical data interpretation as supporting tools which will inform and support the development of an integrated conceptual hydrogeological model of the area field investigations were conducted in order to collect piezometric and chemical data and use them to retrieve the quantitative and qualitative status of the local aquifer units new interpretation of an older dataset gave an insight into how the karstic aquifer behaves in terms of hydraulics the results have also demonstrated that there is a hydraulic connection between the different aquifers and the mediterranean sea while natural recharge was quantified for both aquifer types

geochemical evolution and timescale of seawater intrusion into the coastal aquifer of israel this study is an attempt to quantify the geochemical processes and the timescale of seawater intrusion into a coastal aquifer from changes in the major ionic composition of the water and the natural distribution of the cosmogenic isotopes 14c and 3h for that purpose we sampled saline and brackish groundwaters from the israeli coastal aquifer a multilayer sampler mls was used to obtain very high resolution 10 cm profiles across the fresh saline water interface fsi the chemical and stable isotope data revealed three distinct water types end members that are located in different zones on the route to the coastal aquifer 1 slightly modified mediterranean seawater sws 2 slightly diluted with up to 20 fresh groundwater saline groundwater sds and 3 fresh groundwater fgw the sws samples generally show an excess of total alkalinity and total dissolved inorganic carbon dic and a depletion of 13cdic and 14cdic with respect to normal seawater indicating that anaerobic oxidation of organic matter is the first diagenetic reaction that affects seawater during its penetration into the bottom sediments sds waters appear when sws is slightly diluted gain ca2 and sr2 and is depleted in k suggesting that the main processes that transform sws into sds are slight dilution with fresh groundwater and cation exchange at the fresh saline water interface sds generally shows conservative mixing with fgw inspection of chemical data from coastal aquifers around the world indicates that intensive ion exchange in slightly diluted saline groundwater is a globally important phenomenon of seawater intrusion most of our saline groundwater samples contain substantial amounts of 3h suggesting that penetration of mediterranean seawater and its inland travel to a distance of 50 100 m onshore occurred 15 30 yr ago this is supported by the 14cdic mass balance that explains the relatively low 14cdic activities in the sds as influenced by diagenesis and not by simple radioactive decay

high resolution stratigraphy and evolution of the rhone delta plain during postglacial time from subsurface drilling data bank this study is based upon a large set of core drilling data lithology and well logs of the rhone delta plain extracted from the french geological survey brgm databank the main goals are to set up a sequence stratigraphy model of the postglacial sedimentary bodies of the rhone delta plain and to evaluate the relative importance and influence of the main controlling factors and processes subsidence eustasy sediment yield climate anthropic influence that led to their formation first a detailed study 60 drill holes with tenth meters spacing was performed on a restricted area saint ferreol lobe 1 5 km2 correlation between well logs data and lithological data allows to identify the main sediment lithofacies and key surfaces and to set up a detailed stratigraphic framework postglacial deposits are subdivided into a lower member of coastal plain and backbarrier deposits and an upper member of marine deposits coastal barrier environments following the analysis of 160 wells distributed on the whole delta plain depicts the large scale architecture of postglacial deposits in the upper delta plain fluviatile coastal plain and palustral deposits prevail in the lower delta plain the deposits are made of a lower part of coastal plain deposits organized into four units t1 t4 stacked in a retrograding pattern this lower member is truncated by an erosional surface progressively deepening seaward above an upper member of marine deposits thickening seaward and coarsening upward is organized into five units p1 p5 arranged in a prograding pattern the core drilling data have been correlated with high resolution seismic data on the adjacent shelf and are interpreted in sequence stratigraphy terms the retrogradational units t1 t4 with coastal plain deposits are correlative of shelf units and constitute together trangressive parasequences deposited during phases of slowing down of postglacial sea level rise the upper marine units p1 p5 arranged in a prograding pattern represent parasequences of the highstand systems tract which have prograded since the period of reduced rate of sea level rise at the end of the holocene during this period the evolution of the sedimentary rhone system was controlled by major changes of the hydrologic regime periods of increased sediment discharge aggradation of the floodplain and progradation of the coastline are correlated with the development of the deltaic lobes of the rhone d ulmet unit p3 and of the rhone du bras de fer unit p4 unit p5 correlates with adjacent prograding shelf unit that developed seaward of the present rhone river mouth comparison of sea level history between the eastern part of the rhone delta plain and the rocky coast to the east of marseille suggests that tecto subsident movements account for part of the changes in relative sea level moreover the truncation of transgressive and progradation surfaces the unevenness of the mfs the dilatation of sedimentary record and deformations of key surfaces are also in favor of differential subsidence

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

hydrogeochemical processes affecting groundwater in an irrigated land in central tunisia detailed hydrogeochemical investigation has provided new information concerning the major factors and mechanisms controlling the groundwater chemistry of chougafiya basin the hydrogeochemical characteristics of groundwaters comprise three main types cl so4 ca cl so4 na and cl na hydrochemical characteristics based on the bivariate diagrams of major cl so42 no3 hco3 na mg2 k and ca2 and some trace br and sr2 ions mineral saturation indices and hierarchical cluster analysis indicate different origins of groundwater mineralization the water rock interaction dissolution of evaporitic minerals followed by cation exchange reactions with clay minerals constitute the main processes that control groundwater salinization however the chemical composition of brackish groundwater in the central and southern parts of the study area is influenced by a mixing process with sabkhas salt groundwater the mixing proportions inferred from chloride mass balance prove that the contribution of sabkhas groundwater to quaternary aquifer ranges between 2 7 and 9 1 these intrusion rates reflect the progress of the saltwater freshwater interface which is mainly controlled by the piezometric level variation and the distance to the sabkhas

possible connection between large volcanic eruptions and level rise episodes in the dead sea basin abstract the june 1991 pinatubo volcanic eruption perturbed the atmosphere triggering short term worldwide changes in surface and lower troposphere temperatures precipitation and runoff the following winter was anomalously wet in the levant with a 2 m increase in the dead sea level that created a distinct morphological terrace along the lake s shore given the global radiative and chemical effects of volcanogenic aerosols on climatic systems we tested the hypothesis that the 1991 92 winter shore terrace is a modern analogue to the linkage between past volcanic eruptions and a sequence of shore terraces on the cliffs around the dead sea basin dsb sixteen shore terraces detected using airborne laser scanning data were interpreted as indicating short term level rises due to episodes of enhanced precipitation and runoff during the dramatic drop in lake lisan s palaeo dead sea level at the end of the last glacial maximum the terraces were compared with a dated time series of volcanogenic sulfate from the gisp2 ice core and similar numbers of sulfate concentration peaks and shore terraces were found furthermore a significant correlation was found between so 4 concentration peaks and the heights of the terraces this correlation may indicate a link between the explosivity of past eruptions the magnitude of stratospheric injection and their impact on the northern hemisphere water balance the record of such short term climato hydrological effects is made possible by the dramatic desiccation of lake lisan detailed records of such events albeit rare because of their vulnerability and short longevity provide an important demonstration of global climatic teleconnections

geochemical and palaeohydrological controls on the composition of shallow groundwater in the netherlands with the exception of the south of the country the netherlands has a strong bipartite hydrogeology the holocene part with a coastal dune belt and confining top layer of clay and peat further inland and the pleistocene where thick phreatic aquifers dominate this research aimed to ascertain the geochemical and palaeohydrological controls on the composition of shallow groundwater in 27 regions close to 6000 groundwater analyses were grouped and interpreted in terms of 1 salinity 2 redox status 3 acid base and carbonate status and 4 natural nutrients nh4 and po4 the a priori classification into geographical regions and geological formations revealed many statistically significant differences in medians even for geologically or geographically related data groups the compound specific interpretation indicates that there are geogenically controlled systematic differences in groundwater composition at the regional scale the imprint of the geological sediments on the groundwater composition decreases in the order marine estuarine via limnological fluvial to aeolian the imprints with respect to ph and carbonate status natural nutrients and redox status are not necessarily interrelated the vertical stratification in groundwater composition turns out to be often limited at the regional scale due to mutual occurrence of infiltrating and exfiltrating groundwater in regions and either the presence of a highly reactive holocene confining top layer or temporal changes in contamination in the holocene part the salinity is controlled by the palaeoenvironmental conditions during the holocene and by the recharge origin the average cl concentration decreases from estuarine via lagoonal to the former zuider sea which was a bay the most reduced states and also the highest nutrient concentrations and highest co2 pressure are related to the presence of holocene marine sediments in the confining top layer degradation of marine derived organic matter as a nutrient source is likely more intense in the holocene deposits than that of peat and sedimentary remnants of terrestrial plants a broad range in ph carbonate status and redox status is encountered in the pleistocene part here the palaeohydrological evolution in terms of carbonate leaching together with the geological controls on the calcareous nature of the shallow sedimentary deposits cause regional differences in ph calcite saturation and silicate weathering one region with late pleistocene limnological deposits has deviating groundwater characteristics and appears more similar to the holocene part of the netherlands furthermore reactive fe is not abundant in all pleistocene fluvial sediments nor is it maximally mobilised as not all anoxic groundwater in these sediments is siderite saturated this leads to considerable intra and inter region variability 2013 elsevier ltd

ionic and isotopic ratios for identification of salinity sources and missing data in the gaza aquifer abstract groundwater is the only source of fresh water in the gaza strip however it is severely polluted and requires immediate effort to improve its quality and increase its usable quantity intensive exploitation of groundwater in the gaza strip over the past 40 years has disturbed the natural equilibrium between fresh and saline water and has resulted in increased salinity in most areas salinization in the coastal aquifer may be caused by a single process or a combination of different processes including seawater intrusion upconing of brines from the deeper parts of the aquifer flow of saline water from the adjacent eocene aquifer return flow from irrigation water and leakage of wastewater each of these sources is characterized by a distinguishable chemistry and well known isotopic ratios in this paper na cl so4 cl br cl ca hco3 so4 and mg ca ionic ratios were used to distinguish different salinization sources 11b and 87sr 86sr isotopic composition were also included in the model to study their importance in this monitoring task the task of monitoring and the associated decision making process are characterized by a high degree of uncertainty with respect to input data and accuracy of models for this reason probabilistic expert systems and more specifically bayesian belief networks bbns are used to identify salinization origins the bbn model incorporates the theoretical background of salinity sources area specific monitoring data that are characteristically incomplete in their coverage expert judgment and common sense reasoning to produce a geographic distribution for the most probable sources of salinization the model is also designed to show areas where additional data on chemical and isotopic parameters are needed

temporal variation in the geometry of a strike slip fault zone examples from the dead sea transform abstract the location of the active fault strands along the dead sea transform fault zone dst changed through time in the western margins of dead sea basin the early activity began a few kilometers west of the preset shores and moved toward the center of the basin in four stages similar centerward migration of faulting is apparent in the hula valley north of the sea of galilee as well as in the negev and the sinai peninsula in the arava valley seismic surveys reveal a series of buried inactive basins whereas the current active strand is on their eastern margins in the central arava the centerward migration of activity was followed by outward migration with pleistocene faulting along nne trending faults nearly 50 km west of the center largely the faulting along the dst which began in the early middle miocene over a wide zone of up to 50 km became localized by the end of the miocene the subsidence of fault controlled basins which were active in the early stage stopped at the end of the miocene later during the plio pleistocene new faults were formed in the negev west of the main transform they indicate that another cycle has begun with the widening of the fault zone it is suggested that the localization of faulting goes on as long as there is no change in the stress field the stresses change because the geometry of the plates must change as they move and consequently the localization stage ends the fault zone is rearranged becomes wide and a new localization stage begins as slip accumulates it is hypothesized that alternating periods of widening and narrowing correlate to changes of the plate boundaries manifest in different euler poles

groundwater salinization processes in shallow coastal aquifer of djeffara plain of medenine southeastern tunisia urban and industrial development and the expansion of irrigated agriculture have led to a drastic increase in the exploitation of groundwater resources the over exploitation of coastal aquifers has caused a seawater intrusion and has seriously degraded groundwater quality the shallow coastal aquifer of the djeffara plain southeastern tunisia constitutes an example of water resource suffering an intensive and uncontrolled pumping for irrigation intensive exploitation of the aquifer and climate aridity caused a decrease in piezometric level and an increase in salinity according to the hydrochemical data cl so4 2 no3 hco3 br ca2 mg2 na k and the stable isotope composition oxygen 18 and deuterium content groundwater salinization in the investigated system is caused by three main processes i salts dissolution especially in the central part of jerba and around medenine plain ii evaporation process and iii seawater intrusion which caused the increase in salinity in the peninsula of el jorf in jerba and in the north of ben gardane

constraints on evaporation and dilution of terminal hypersaline lakes under negative water balance the dead sea israel abstract the response of hypersaline terminal lakes to negative water balance was investigated by studying brines evaporating to extreme salinities in sinkholes along the western coast of the dead sea and during on site evaporation experiments of the dead sea brine density and temperature were determined in the field and all samples were analyzed for their major and a few minor solutes the activity of h 2 o a h2o in the brines was calculated and the degree of evaporation de was established using sr 2 as a conservative solute the relations between density and water activity were obtained by polynomial regression and the relation between the lake s volume and level was established using hall s 1996 hypsographic model for the dead sea basin relating the results to the modern long term relative humidity rh over the basin shows that a the lowermost attainable level of a terminal lake undergoing evaporation with no inflow is dictated by the median rh this level represents equilibrium between the brine s a h2o and rh b small saline water bodies with high surface to volume ratios a v such as the hypersaline brines in the sinkholes are very sensitive to short term changes in rh in these the brines a h2o closely follows the seasonal changes c the level decline of the dead sea due to evaporation under present climatic conditions and assuming no inflow to the lake may continue down to 516 537 m below mean sea level bmsl corresponding to a water activity range of 0 46 0 39 in its brine in equilibrium with the overlying relative air humidity this suggests that the lake level cannot drop more than 100 m from its present level and d the maximum rh values that existed over the precursor lake of the dead sea lake lisan during geologically reconstructed minima levels can be similarly calculated