salinization in coastal aquifers of arid zones an example from santo domingo baja california sur mexico groundwater quality in the santo domingo irrigation district area in baja california sur mexico indicates the presence of various salinization processes 1 the geological matter of marine origin comprising the aquifer material suffers diagenetic effects due to its interaction with groundwater of low salinity 2 the effects of intensive agriculture practices produce effluents that infiltrate to the saturated zone and 3 the extraction of groundwater causes modifications in the natural flow system induces lateral flow of seawater from the coast line however groundwater management has been carried out with the belief that the latter is the main source of salinization this has resulted in a policy of installing wells increasingly far from the coast which is not solving the problem irrigation return and seawater that remains in the geological units have been identified as major sources of salinization controls should be imposed when installing wells in contact with clayey units that form the base of the aquifer extracted groundwater consists of a mixture of 1 groundwater of relatively low salinity that circulates in the aquifer and 2 an extreme member with salinity different to seawater contained mainly in formations that have low permeability which limits the aquifer underneath the geochemistry of carbonates and cation exchange reactions both direct and reverse control the concentration of ca mg na and hco3 as well as ph values the concentrations of dissolved trace elements f li ba sr suggest that the extreme saline member is different from the average seawater composition a distinction between the salinization caused by farming practices and that blamed on seawater is defined by the use of no3

hydrogeochemistry of deep formation brines in the central sichuan basin china abstract subsurface brines are abundant in the sichuan basin china five brine bearing aquifers have been identified within rocks of triassic age in the central part of the basin these are of two types brine bearing clastic and brine bearing carbonate aquifers brines in this region have high total dissolved solids and chemical species that are different from those of evaporatively concentrated seawater deep formation brines in clastic aquifers in which evaporites do not exist are characterized by high concentrations of ca sr ba br and i low concentrations of mg and k and lack of so4 and are dominated by the na ca cl type brines in carbonate aquifers which have interbeds of evaporites are characterized by high total dissolved solids low concentrations of ca mg and so4 and lack of ba and are of the na cl type the brines in clastic aquifers originate from connate continental sedimentary waters mixed with marine waters membrane filtration through shales has played an important part in modifying the chemical compositions and increasing the salinity of the brines those in carbonate aquifers are bittern marine sedimentary waters with chemical compositions mainly controlled by precipitation of evaporites

hydrogeological characterization of seawater intrusion in tidally forced coastal fractured bedrock aquifer summary hydrogeological investigation was carried out to characterize seawater intrusion in a tidally forced coastal fractured bedrock aquifer in the west coast of korea peninsular which was also subject to heavy groundwater extraction times series analysis using the data of electrical conductivity ec groundwater level and tidal oscillation showed that intensive groundwater extraction from the wells near the shore caused a severe seawater intrusion the geophysical loggings and hydraulic tests indicated that the tidally forced coastal fractured aquifer in the study area was characterized by the shallow fresh groundwater transition zone and deep high saline water zone the extent of seawater intrusion highly depended on conductive fractures and their hydraulic connectivity in the deep saline water layer progressive seawater intrusion took place mainly by persistent intensive pumping and in part by tidal activity the conductive fractures acted as a pathway for saline water flow from the deep saline water zone to the transition zone when groundwater was extracted the extent of transition zone depended on the change of groundwater level by groundwater pumping or recharge this study indicated that a persistent intensive extraction of groundwater would intensify seawater intrusion in tidally forced coastal fractured aquifer and proper measures would be required to prevent it

geochemistry of formation waters from the lower silurian clinton formation albion sandstone eastern ohio waters of the petroleum bearing clinton formation albion sandstone of eastern ohio are highly concentrated brines with average total dissolved solids tds of 250 000 ppm sodium calcium and chloride account for 97 of the tds distribution of divalent metal chlorides mcl 2 allows inference of an up dip paleoflow direction although present day flow is probably down dip solute distribution may have been emplaced during early basin development it thus provides a snapshot of paleoflow formation structure alone can not explain mcl 2 trends they probably also are controlled by regional variation in salt thickness major constituent data do not indicate that membrane filtration affected the waters high bromide content mean 1860 ppm of the waters indicates that they originated from evaporating seawater they probably are related genetically to the salina evaporite group calculations show that several subsequent diagenetic reactions can account for the observed major ion composition recrystallization of aragonite and dolomitization of calcite probably occurred as the waters moved through the big lime and or the packer shell carbonates cation exchange and chlorite formation probably altered water composition during interaction with shales of the cabot head formation and within the clinton minor constituents of the waters appear to be controlled by reactions with clays

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

marine and human activity influences on the groundwater quality of southern korinthos area greece in this paper the groundwater quality of the southern part of korinthos region north east peloponnese is discussed the geology is characterized by a thick sequence of neogene marls alternating with sandstones overlain by superficial quaternary deposits the latter consist of a mixture of loose materials such as conglomerates marly sandstones sands and clay to silty sands the area is crossed by a fault system parallel to the coastline and the quaternary sediments have formed extended tyrrhenian marine terraces two aquifers have been identified in the area the first is unconfined and occurs within the quaternary sediments whereas the other is a deep confined aquifer occurring within the underlying neogene marl series analysis of hydrochemical evolution over the past 30 years has indicated significant deterioration of quality owing to seawater intrusion and nitrate pollution the various sources of pollution have rendered to a large extent shallow groundwater unsuitable not only for potable water supply but also for irrigation purposes however this is not the case for the deeper confined aquifer statistical analysis was used to explore the evolution of salinization during the years 1968 and 1998 in view of the alarming conditions caused by the documented groundwater quality deterioration the need for integrated water resources management is stressed to maintain the socio economic growth of the region studied copyright 2003 john wiley sons ltd

the origin of high sulfate concentrations and hydrochemistry of the upper miocene pliocene quaternary aquifer complex of jifarah plain nw libya the high uncontrolled groundwater extraction in jifarah plain nw libya causes a modification of natural flow systems inducing seawater intrusion and causing groundwater quality deterioration the principal aim of this study is to identify the hydrogeochemical processes in this coastal aquifer in order to verify the main sources of sulfate concentration increase that occurs in the system in order to achieve this aim water samples were collected from 134 sampling wells in the study area and analyzed for the major cations and anions physical and chemical parameters were measured such as water level electrical conductivity ph and temperature the analytical results obtained in the hydrochemical study were interpreted using piper diagram ion correlations with na cl so4 2 cl and tds in conjunction with calculation of the ionic deviations of the conservative freshwater seawater mixture and saturation indices using the phreeqc 2 16 software the large so4 2 anomaly observed in groundwater near the coast was explained by the presence of seawater intrusion and upconing of deep saline water in these areas this conclusion is based on high chloride concentrations the inverse cation exchange reactions and the lower piezometric level compared to sea level inland in sabratah the high so4 2 values are related to gypsum dissolution from the upper miocene formation in the lower part of the upper aquifer these locally high so4 2 concentrations in the south of the study area show overall increase in the upstream direction which also suggests the dissolution of evaporites from the mountain aquifers in the south high so4 2 concentration is also related to the effect of the scattered sebkha deposits in some areas along the coast

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

analysis of salinization processes in the coastal carbonate aquifer of porto torres nw sardinia italy the porto torres nw sardinia coastal aquifer is hosted in the carbonate rocks of the miocene succession which fills a nnw oriented half graben this aquifer is an important contributor to the fresh water supply of the local area it is increasingly being degraded by salinization processes mainly associated with intense groundwater over exploitation a combined hydrochemical and hydrogeological study has been carried out to identify the origin of the salinity in the groundwater the behavior of the major ions showed that the changes in the chemical composition of the groundwater have been mainly controlled by the encroachment of seawater accompanied by cation exchange reactions since seawater intrusion is a dynamic process an hydrochemical facies evolution diagram hfe d gimenez forcada 2010 approach was taken to establish whether the aquifer was in the seawater intrusion or in the freshening phase the assessment model developed provides regional authorities with a basic tools for sustainable water management in the framework of multi disciplinary research activities aiming to combat and or mitigate desertification and land degradation processes

the value of iodide as a parameter in the chemical characterisation of groundwaters abstract brackish and saline groundwaters can severely constrain the use of fresh groundwaters their chemical characterisation is important in understanding the hydraulic conditions controlling their presence in an aquifer major ions are frequently of limited value but minor ions can be used iodide in groundwater is particularly significant in many environments due to the presence of soluble iodine in aquifer matrix materials iodide is found in groundwaters in parts of the english chalk aquifer in concentrations higher than are present in modern seawater its presence is considered as a indication of groundwater residence and is of use in the characterisation of fresh as well as saline waters under certain circumstances modern seawater intrusion into aquifers along english estuaries produces groundwaters which are easily identified due to iodide enrichment from estuarine muds in other environments iodide concentrations are of value in distinguishing between groundwaters in limestones and shaly gypsiferous rocks as shown by a study in qatar while in an alluvial aquifer study in peru iodide has been used to identify groundwaters entering the aquifer from adjacent granodiorites

groundwater geochemistry and calcite cementation of the aquia aquifer in southern maryland the aquia aquifer in southern maryland exhibits three regions that are characterized by distinctly different water composition region i is about 26 mi 42 km wide and is parallel to the outcrop area water in region i has relatively high calcium 30 mg l magnesium 10 mg l and bicarbonate 150 mg l concentrations and relatively low sodium 2 mg l concentrations region ii parallel to and downgradient from region i is about 24 mi 38 km wide water in region ii is characterized by constant bicarbonate increasing sodium decreasing calcium and decreasing magnesium concentrations region iii is downgradient from region ii and is characterized by low calcium 2 mg l low magnesium 1 mg l high bicarbonate 300 mg l and high sodium 100 mg l concentrations the major lithologic constituents of the aquia aquifer are quartz sand 55 glauconite 30 and carbonate shell material 8 heavy minerals clay minerals and finely disseminated lignite make up about 2 of the aquifer material calcite cementation is commonly observed in and near the outcrop area of the aquia stoichiometric chemical models were constructed based on this lithology to describe the water chemistry of each region these models are region i ca1 x mgx co3 s co2 g h2o 1 1 x ca aq 2 xmg aq 2 2hco3 aq region ii 1 x ca aq 2 xmg aq 2 na2 glauconite ad ca 1 x mgx glauconite ad 2na aq and region iii ca 1 x mgx co3 s co2 g h2o 1 na2 glauconite ad 2na aq 2hco3 aq ca 1 x mgx glauconite ad the applicability of these models was verified by comparing predicted and observed molar ratios of dissolved species using linear regression techniques in all cases close matches were found between predicted and measured curves mass balance calculations using the verified chemical models predict a spatial distribution of calcite cementation that closely matches the observed distribution in the aquia aquifer this suggests that the observed calcite cementation is postdepositional in origin and has resulted from reaction of groundwater with aquifer material

sulfur isotopic study of sulfate in the aquifer of costa de hermosillo sonora mexico in relation to upward intrusion of saline groundwater irrigation pumping and land cultivation abstract groundwater from the costa de hermosillo aquifer has been used extensively for irrigation over the past 60 a in the sonora region of northwestern mexico resulting in salinization of fresh groundwater resources salinization of groundwater is most pronounced on the western coastal side of the aquifer with an aerial extent of 26 7 km2 where maximum values are reported for conductivity 31 ms cm and cl concentrations 16 271 mg l salinization is likely to increase if groundwater pumping continues at levels comparable to the present time upward incursion of marine water into the aquifer is inferred from 2h 7 2 and 18o 1 6 compositions of groundwater samples with the highest conductivity compared to modern seawater in the gulf of california ratios of so4 cl and cl br are small 0 01 and 33 respectively and the s isotopic composition of so 4 2 is high 32 7 in the most saline portions of the costa de hermosillo this saline groundwater is inferred to result from an earlier phase of dissimilatory bacterial so 4 2 reduction coupled to decomposition of organic matter in marine blue clays deposited during the miocene pliocene transgression the isotopic composition of present day surface discharge from agricultural fields is substantially enriched in 32s due to widespread application of nh4 2so4 fertilizers and potential mobilization of s from mineral resources surface water discharging from irrigated fields has 34s values ranging from 2 1 to 3 3 which are distinctly different from groundwater and surface water in adjacent non agricultural areas with 34s values ranging from 5 2 to 13 5 prolonged irrigation pumping that promotes the incursion of air to the subsurface could enhance the weathering of s bearing minerals such as magmatic sulfides producing 32s enriched so 4 2

aridity events during the last 4000 years in western mediterranean marshes almenara and benicasim marshes e spain abstract facies and geochemical analysis applied to marsh deposits are useful proxies for the reconstruction of aridity for the last millennia the comparison of facies and geochemical records among cores from the almenara and benicasim marshes allows to identify changes in water level si al al ca and salinity of the feeding waters mg al na al s al these changes in turn represent fluctuations in the position of the saline fresh groundwater boundary which can be related to variations in sea level and rainfall for the last 4000 years three events recording higher salinity conditions ca 3 4 ka bp ca 3 ka bp and ca 1 8 ka bp are noticeable in the record comparison to other studies around the western mediterranean basin allows us to correlate these events to arid episodes and to identify their forcing mechanisms these aridity events are correlative to small falls in solar activity and surface sea temperature sst during positive north atlantic oscillation nao periods despite the small magnitude of these changes the sensitivity of the system amplified the result providing a conspicuous signal

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

geochemistry of sediments from the mangalore cochin shelf and upper slope off southwest india geological and environmental factors controlling dispersal of elements abstract the geochemical investigations on 136 surficial sediment samples of the mangalore cochin shelf and upper slope were undertaken to understand the distribution sources and processes by which various major and trace elements are incorporated into the sediments texturally the inner shelf 120 m water depth are dominantly composed of clayey sediments whereas the outer shelf 50 120 m water depth is carpeted by relict 10 000 yr in age sands the results show that sediment texture largely controls the distribution of elements the sandy relict sediments of the outer shelf 59 samples and of the upper slope restricted coverage have high contents of sio 2 caco 3 and sr amongst which sio 2 is present as terrigenous quartz sand while caco 3 and sr being well correlated with skeletal components are biogenous extremely good positive correlation between sr and caco 3 r 0 77 suggests presence of sr in the lattices of aragonite which is the main carbonate mineral the clay rich sediments of the inner shelf 52 samples and upper slope 25 samples are both very rich in organic carbon content and low in sio 2 content and very high in al 2 o 3 tio 2 fe 2 o 3 mgo na 2 o k 2 o p 2 o 5 mn cu ni zn and li contents as compared to the sandy sediments of the outer shelf except for organic carbon p 2 o 5 and tio 2 strong positive correlations of these components with al 2 o 3 r 0 41 0 90 suggest their association mainly with clay minerals within the clay minerals these are present in the crystal lattice either as essential constituent or incorporated by cation exchange or adsorbed onto clay platelets organic carbon p 2 o 5 and tio 2 also show positive correlation with al 2 o 3 mainly due to their physical association with fine grained clayey sediments phosphate in these sediments is mainly present in association with organic matter and to some extent it also occurs either as ferric phosphate or as authigenic apatite in general the geochemistry of these sediments clearly reflects their mineralogy formation of fe and mn hydroxides in the nearshore regions is responsible for scavenging of ni cu and zn and effectively incorporating them into the inner shelf sediments these trace elements also show significant correlation with organic carbon r 0 51 0 56 suggesting that a part of their content is biogenous

hydrochemical and isotopic characterisation of groundwaters to define aquifer type and connectivity in a subtropical coastal setting fraser coast queensland physico chemical parameters major ion chemistry and isotope composition of surface and groundwaters were determined in forested coastal catchments and adjacent coastal plains results showed obvious characterisation related to physical and hydrological setting and highly variable spatial differences reflecting the complexities of these areas all these coastal waters are dominated by na cl and fall on a common dilution line hydrochemical grouping is largely due to anionic differences cl so4 and hco3 although na and mg ratios also vary six major hydrochemical facies were determined for groundwaters compositional differences are largely related to aquifer material and level of confinement for coastal groundwaters important are tidal effects and proximity to the shoreline differentiation for surface waters is mainly by drainage morphology flow regime plus proximity to the coast connectivity between water bodies is reflected by minor base flow to catchment streams including with flood plain wetlands but mostly occurs in low lying zones where there is mixing of fresh and saline water within surface water and subterranean estuaries or by seawater intrusion enhanced by overuse oxygen and hydrogen isotopic data for confined and semi confined groundwaters along the coast indicates local recharge fresh surface waters in the elevated catchments are shown to be sourced further inland plus have experienced evaporation

hydrogeochemical analysis of salinization processes in the coastal aquifer of oropesa castellon spain the coastal aquifer of oropesa is affected by salinization processes undoubtedly associated with intense groundwater exploitation for agriculture supply the aquifer corresponds geologically to a tectonic depression with plioquaternary fill hydrogeologically this aquifer is detrital with intergranular porosity which receives substantial recharge from adjacent mesozoic aquifers contact with the sea in addition to the presence of cultivated soil requiring extreme exploitation of groundwater frequently give rise to processes of seawater intrusion the present research is an attempt to understand the saltwater intrusion in this aquifer using hydrochemical analyses of the behavior of certain minor ions that could help in the characterization process in the case of the oropesa sector groundwater salinization does not appear to be attributable solely to the intrusion of seawater but there are also anomalies related largely to the geology of the sector and its surroundings the type of recharge the hydrodynamic conditions in the specific area etc

geochemical and isotopic evidence of shallow groundwater salinization in a reclaimed coastal zone the yellow river delta china this paper aims to improve the current knowledge of groundwater salinization processes of a young coastal aquifer in the yellow river delta yrd and to assess the impact of both the transfer of irrigation water from the yellow river and seawater intrusion using a combination of hydrochemical isotopic measurements the major ion cl ratios generally closely follow the mixing line between freshwater end member the yellow river and saline water end members salt groundwater or seawater indicating the importance of mixing under natural and anthropogenic influences the examination of stable isotope in groundwater ranging from 9 0 to 3 5 for 18o and from 73 to 29 for d respectively and chloride concentrations 2 to 629 meq l confirms that the saline end member is associated with saltwater rather than present seawater and most groundwater samples are plotted on mixing lines between the yellow river and saltwater the similar range in stable isotopes 18o and d and cl compositions between saltwater and confined aquifer supports the hypothesis that upward seepage of confined saline water intruded the shallow aquifer moreover the deviations in some cases from mixing line imply water rock interaction is also important in dominant control on groundwater chemistry such as cation exchange so4 2 reduction and nacl solution the brackish water was characterized by slight excess of na and deficit of ca2 compared to non reactive mixing line this indicates that the coastal aquifer is generally freshening with respect to extensive irrigation network as well as the transfer from the yellow river for ecological recharge into wetland

discussion about the validity of sharp interface models to deal with seawater intrusion in coastal aquifers analytical models have been exhaustively used to study simple seawater intrusion problems and the sustainable management of groundwater resources in coastal aquifers because of its simplicity easy implementation and low computational cost most of these models are based on the sharp interface approximation and the ghyben herzberg relation and their governing equations are expressed in terms of a single potential theory to calculate critical pumping rates in a coastal pumping scenario the ghyben herzberg approach neglects mixing of fresh water and seawater and implicitly assumes that salt water remains static therefore the results of the analytical solutions may be inaccurate and unacceptable for some real complex case studies this paper provides insight into the validity of sharp interface models to deal with seawater intrusion in coastal aquifers i e when they can be applied to obtain accurate enough results for that purpose this work compares sharp interface solutions based on the ghyben herzberg approach with numerical three dimensional variable density flow simulations for a set of heterogeneous groundwater flow and mass transport parameters and different scenarios of spatially distributed recharge values and spatial wells placement the numerical experiment has been carried out in a 3d unconfined synthetic aquifer using the finite difference numerical code seawat for solving the coupled partial differential equations of flow and density dependent transport this paper finds under which situations the sharp interface solution gives good predictions in terms of seawater penetration transition zone width and critical pumping rates additionally the simulation runs indicate to which parameters and scenarios the results are more sensitive copyright 2013 john wiley sons ltd

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

some factors affecting tds and ph values in groundwater of the beihai coastal area in southern guangxi china groundwater of low total dissolved solids tds of 10 mg l and low ph ranging commonly from 4 0 to 7 0 occurs in the unconsolidated unconfined and confined aquifers in the coastal plain near beihai guangxi china minerals in the unconsolidated sediment of quaternary are predominated by quartz more than 50 with small amount of clay minerals such as kaolinite illite and chlorite sio2 accounts for most more than 70 of the chemical compositions of the sediments the sediments contain low concentrations of soluble constituents below 300 g g and are predominated by so4 abundant recharge from low tds precipitation and a long time s dissolution of the unconsolidated sediments containing small amount of soluble compositions lead to low tds of the groundwater in the area

submarine groundwater discharge into the coast revealed by water chemistry of man made undersea liquefied petroleum gas cavern summary the occurrence of submarine groundwater discharge sgd as well as its supply of many nutrients and metals to coastal seawaters is now generally known however previous studies have focused on the chemical and radiological analysis of groundwater surface seawater shallow marine sediments and their pore waters as well as the measurement of upward flow through the marine sediments as end members of the discharge process in this study chemical and isotopic analysis results of marine subsurface waters are reported these were obtained from deep boreholes of an undersea liquefied petroleum gas lpg storage cavern located about 8 km off the western coast of korea the cavern is about 130 150 m below the sea bottom which is covered by a 4 8 19 5 m silty clay stratum an isotopic composition 2h and 18o of the marine subsurface waters falls on a mixing line between terrestrial groundwater and seawater vertical ec profiling at the cavern boreholes revealed the existence of a fresh water zone an increase in the contents of ferrous iron and manganese and a decrease in levels of nitrate bicarbonate and cavern seepage were recorded in august 2006 indicating a decreased submarine groundwater flux originating from land mainly caused by an elevated cavern gas pressure it is suggested in this study that the main source of fresh waters in the man made undersea cavern is the submarine groundwater discharge mainly originating from the land

hydrogeochemistry and quality of groundwater of coastal unconfined aquifer in amol ghaemshahr plain mazandaran province northern iran groundwater of the unconfined aquifer 1 100 sq km of a two tier coastal aquifer located in the amol ghaemshahr plain mazandaran province northern iran is classified into fresh and brackish water types fresh groundwater fgw samples n 36 are characterized by ca2 na mg2 k and hco3 cl so4 2 no3 spearman s rank correlation coefficient matrices factor analysis data values of the c ratio av 0 89 and cai and values of the molar ratios of ca2 hco3 ca2 so4 2 mg2 hco3 and mg2 so4 2 indicate that the ionic load in the fgw is derived essentially from carbonic acid aided weathering of carbonates and aluminosilicates saline sea water trapped in the aquifer sediments now admixed with the groundwater and ion exchange reactions values of the cai and na cl molar ratio suggest that the part of the ca2 mg2 content in 23 fgw samples is derived from clay minerals of the aquifer matrix and part of the na content in 20 12 and 3 fgw samples is derived respectively from alkali feldspar weathering clay minerals of the aquifer matrix and rain water and or halite brackish groundwater bgw samples n 4 contain cl as the dominant anion and their average total ionic concentration 38 65 meq l is 1 79 times higher than that of the fgw samples 21 50 meq l bgw pockets were generated by non conservative mixing of fgw with the upconed saline water from the underlying saline groundwater zone of the semi confined aquifer along bore wells involved in excessive extraction of groundwater from the unconfined aquifer groundwater belongs essentially to high salinity low sodium irrigation water class

seismic studies in the north celtic sea basin implications for basin development modelling of seismic refraction data from the north celtic sea basin offshore ireland demonstrates the presence of a nnw trending basement flexure mesozoic sediments are 4 km thick on the west and 6 km thick on the east of the feature which is interpreted as a transfer fault zone lying along a major reactivated basement fracture bulk extension is greater in the lower lithosphere than in the upper crust with the interface being a rheologically regulated mid crustal detachment surface the basin developed in response to the interplay between periodic disengagement along the detachment and selective strain transfer into the upper crust

hydrochemical and physical processes influencing salinization and freshening in mediterranean low lying coastal environments abstract ground and surface water chemistry and stable isotope data from the coastal zone near ravenna italy have been examined to determine the geochemical conditions and processes that occur and their implications for fresh water availability in the various brackish saline coastal environments fresh water in shallow coastal aquifers is often not enough to provide drinking water but it may sustain agriculture and natural environments such as pine forests dunes and lagoons the hydrochemistry and stable o and h isotopes of the ground and surface water near ravenna were investigated in relation to these particular environments rivers drainage channels lagoons coastal dunes paleo dunes agricultural fields and gravel pit lakes emphasis was put on the spatial distribution of ground water bodies with similar hydrochemistry most water samples are of the brackish to saline nacl type nacl concentration 300 20 000 mg l with a negative base exchange index bex that is indicative of cation exchange reactions caused by water rock interactions during the infiltration of saline water in a fresh water aquifer calcium dominated fresh water is found only in the rivers in the irrigation and drainage channels and in a few ground water samples the analysis of stable isotopes and so 4 2 cl and 18o cl ratios shows that the major chemical and physical processes determining the salinity in the area are evaporation mixing with saline water cation exchange oxidation of organic matter migration and seepage of hyper saline water the migration and upward seepage of hyper saline water driven by the hydraulic gradients induced by the drainage system causes the aquifer to become more saline over time the areas where natural recharge occurs have always been small and this in combination with the mediterranean climate results in very little natural recharge therefore unless drastic changes to the hydraulic infrastructure are made the coastal aquifer near ravenna will become more saline and will threaten the ecology of current natural areas as well as the farmland

water rock interaction in tertiary sandstones san joaquin basin california u s a diagenetic controls on water composition three water types are recognized among petroleum associated waters of the southern san joaquin basin 1 meteoric water 2 diagenetically modified connate water and 3 mixed meteoric modified connate water the diagenetically modified connate marine water can be further subdivided into three types 1 fully mg depleted mg 1 mole of the sum of na k ca and mg 2 partially mg depleted and 3 ca enriched enrichment in ca which is the sharpest chemical divide found for the diagenetically modified connate water is the result of feldspar albitization the ca enriched waters are also rich in total dissolved al up to 6 mg l 1 and exhibit lighter 18o values than other diagenetically modified connate waters the total dissolved al abundance in these waters may be due to the presence of organic complexing agents simple and aromatic organic acids and phenolics the lighter 18o values are probably due to both albitization and the lack of substantial clay diagenesis illitization of smectite

salinization properties of a shallow groundwater in a coastal reclaimed area yeonggwang korea the need for more agricultural or residential land has encouraged reclamation at the coastal areas of korea since 1200 ad approximately the groundwaters of these reclaimed areas could be expected to reveal hydrogeochemical properties different from those of areas directly affected by seawater intrusion the purpose of this study therefore was to examine the salinization of shallow groundwater in a coastal reclaimed area and to identify the effect of land reclamation on groundwater quality major cations and anions iodide total organic carbon d 18o and 13c were measured to assist the hydrogeochemical analysis chloride d and 18o data clearly show that the na cl type water results from mixing of groundwater with seawater in particular the d and 18o of ca mg cl no3 type groundwaters are close to the meteoric water line but na cl type waters enriched in chloride are 18o enriched with respect to the meteoric water line meanwhile carbon isotopic data and i cl ratios strongly suggest that there are various sources of salinity the 13c values of na cl type groundwaters are generally similar to those of ca mg cl no3 type waters which are depleted in 13c with respect to seawater i cl ratios of na cl type groundwater are 10 100 times higher than that of seawater because the reclamation has incorporated a large amount of organic matter it provides optimum conditions for the occurrence of redox processes in the groundwater system therefore the salinization of groundwater in the study area seems to be controlled not only by saltwater intrusion but also by other effects such as those caused by residual salts and organic matter in the reclaimed sediments

the hydrogeochemical characterization of morsott el aouinet aquifer northeastern algeria a study of the hydrogeochemical processes in the morsott el aouinet aquifer was carried out with the objective of identifying the geochemical processes and their relation with groundwater quality as well as to get an insight into the hydrochemical evaluation of groundwater the high salinity coupled with groundwater level decline pose serious problems for current irrigation and domestic water supplies as well as future exploitation a combined hydrogeologic and isotopic investigation have been carried out using chemical and isotopic data to deduce a hydrochemical evaluation of the aquifer system based on the ionic constituents water types hydrochemical facies and factors controlling groundwater quality the ionic speciation and mineral dissolution precipitation was calculated by wateqf package software the increase in salinity is related to the dissolution and or precipitation processes during the water rock interaction and to the cationic exchange reactions between groundwater and clay minerals the isotopic analysis of some groundwater samples shows a similarity with the meteoric waters reflect their short residence time and a lowest evaporation phenomenon of infiltrated groundwater

degradation of groundwater quality in coastal aquifer of sabratah area nw libya overextraction of groundwater is widely occurring along the coast where good quality groundwater is at risk due to urbanization tourist development and intensive agriculture the sabratah area at the northern central part of jifarah plain northwest libya is a typical area where the contamination of the aquifer in the form of saltwater intrusion gypsum anhydrite dissolution and high nitrate concentrations is very developed fifty groundwater samples were collected from the study area and analysed for certain parameters that indicate salinization and pollution of the aquifer the results demonstrate high values of the parameters electrical conductivity sodium potassium magnesium chloride and sulphate which can be attributed to seawater intrusion the intensive extraction of groundwater from the aquifer reduces freshwater outflow to the sea creates drawdown cones and lowering of the water table to as much as 30 m below mean sea level irrigation with nitrogen fertilizers and domestic sewage and movement of contaminants in areas of high hydraulic gradients within the drawdown cones probably are responsible for the high nitrate concentration towards the south of the region seawater intrusion and deep salt water upconing result in general high so4 2 concentrations in groundwater near the shoreline where localized so4 2 anomalies are also due to the dissolution of sebkha deposits for few wells in the nearby sebkhas upstream the increase in so4 2 concentrations in the south is ascribed to the dissolution of gypsum at depth in the upper aquifer

using the cl br ratio as a tracer to identify the origin of salinity in aquifers in spain and portugal summary a study on the applicability of the cl br molar ratio for identifying the origin of groundwater salinity is presented according to the experience gained in spain and portugal cl br ratios in atmospheric bulk deposition have helped to distinguish groundwater in which cl derives only from atmospheric sources from groundwater in which cl is contributed by endogenous lithological or anthropogenic sources considering the seawater cl br ratio of 655 4 cl br ratios may be increased up to 1500 in groundwater by the addition of wastewater loaded with nacl or leaching of solid waste and decreased to 300 by the use of br based pesticides or leaching farm animal or septic waste leaching and dissolution of natural and industrial nacl and of gypsum rich formations containing some nacl may yield cl br ratios between one thousand and several thousand although leaching of potassium halides near salt mines produces cl br ratios below the seawater ratio when cl content in groundwater is not affected by extreme evaporation up to halite saturation at 6 2 mol l 1 of nacl and if there are no other cl sources recharge by rainfall can be estimated by relating cl in atmospheric bulk deposition to derived groundwater the cl br ratio appears to be a good tracer for discriminating non atmospheric cl contributions to groundwater provided chemical analyses are accurate since its variability is not wide data have been collected from different areas of spain and portugal and are explained and illustrated by two cases described in detail the donana aquifer in southwest spain and the canary islands both showing the mixing paths