groundwater composition hydrochemical evolution and mass transfer in a regional detrital aquifer baza basin southern spain abstract the physical chemical characteristics of the groundwater in the baza caniles detrital aquifer system indicate that a wide diversity of hydrochemical conditions exists in this semiarid region defining geochemical zones with distinct groundwater types the least mineralized water is found closest to the main recharge zones and the salinity of the water increases significantly with depth towards the center of the basin geochemical reaction models have been constructed using water chemistry data along flow paths that characterize the different sectors of the aquifer system namely quaternary aquifer unconfined sector and shallow and deep confined sectors of the mio pliocene aquifer geochemical mass balance calculations indicate that the dominant groundwater reaction throughout the detrital system is dedolomitisation dolomite dissolution and calcite precipitation driven by gypsum dissolution this process is highly developed in the central part of the basin due to the abundance of evaporites apart from this process there are others which influence the geochemical zoning of the system in the quaternary aquifer which behaves as a system open to gases and which receives inputs of co 2 gas derived from the intensive farming in the area the interaction of the co 2 with the carbonate matrix of the aquifer produces an increase in the alkalinity of the water in the shallow confined sector of the mio pliocene aquifer the process of dedolomitisation evolves in a system closed to co 2 gas ca 2 na cation exchange and halite dissolution processes are locally important which gives rise to a relatively saline water finally in the deep confined sector a strongly reducing environment exists in which the presence of h 2 s and nh 4 in the highly mineralized groundwater can be detected in this geochemical zone the groundwater system is considered to be closed to co 2 gas proceeding from external sources but open to co 2 from oxidation of organic matter the geochemical modeling indicates that the chemical characteristics of this saline water are mainly due to so 4 dissolution dedolomitisation and so 4 reduction coupled with microbial degradation of lignite

water salinization in arid regions observations from the negev desert israel abstract the processes affecting salinization of precipitation surface water vadose water and groundwater were studied in the negev desert israel observations spanning 18 years included the collection of rainfall at three rain sampling stations flood water at six flood stations vadose water from four coreholes penetrating chalk formations and groundwater from 16 monitoring wells tapping the chalk aquitard dissolved carbonate dust and evaporation of the falling raindrops result in ca hco 3 2 facies and increased ion concentration of the rainwater with respect to inland more humid regions the exposure of flood water to evaporation during flood events is minimal the observed ca hco 3 2 facies and salt enrichment by a factor of three to five in the flood water with respect to precipitation results primarily from interactions of the flood water with the chalk and limestone bedrock including ion exchange on na and k bearing minerals and the dissolution of calcite gypsum and halite the presence of these salts at and near land surface results from the complete evaporation of rainwater in land surface depression storage areas following most rain events except for a small portion moving through the low permeability chalk matrix most of the vadose water moves through preferential pathways and is typically not exposed to evaporation this dual movement of water accounts for the nacl facies of vadose water and the variable rates of isotopic depletion and salt dilution observed in the underlying heterogeneous groundwater in the saturated zone although the variable mixing with low salinity isotopically depleted water percolating from the fractures accounts for the depleted isotopic composition of the groundwater its relatively low solute content cannot modify the groundwater nacl facies consequently only groundwater salinity in the chalk is reduced by the preferentially flowing water but the ca hco 3 2 facies prevailing in the rainwater and flood water disappears and the nacl imprint from the vadose zone prevails

the modified generalized moveout approximation a new parameter selection non hyperbolic generalised moveout approximation is a powerful tool to approximate the travel time function by using information obtained from two rays the standard approach for parameter selection is using three parameters defined from zero offset ray and two parameters obtained from a reference ray these parameters include the travel time and travel time derivatives of different order the original parameter selection implies more fit at zero offset compared with offset from a reference ray we propose an alternative approach for parameter selection within the frame of generalised moveout approximation by transferring more fit from the zero offset to a reference ray by changing in parameter selection the modified approximation is tested against the original one in few analytical model examples including the multi layered model

evaluation of groundwater quality in the cihanbeyli basin konya central anatolia turkey the cihanbeyli basin is located in the northern part of konya in the central anatolian region turkey and is characterized by semi arid climatic conditions and scarcity in water resources the suitability of groundwater quality for drinking and agricultural purposes in the cihanbeyli basin was assessed by measuring physicochemical parameters including major cation and anion compositions ph total dissolved solid electrical conductivity and total hardness for this purpose 54 samples were collected from different sources viz deep wells shallow wells and springs results from hydrochemical analyses reveal that groundwater is mostly affected by salty and gypsiferous lithologies evaporite minerals such as gypsum anhydrite and chloride salts make high contributions from the recharge areas west northwest and southwest parts toward the discharge area central and eastern parts high values of total dissolved solids in groundwater are associated with high concentrations of all major ions a comparison of groundwater quality in relation to drinking water standards showed that most of the water samples are not suitable for drinking based on sodium absorption ratio values and percent sodium salinity appears to be responsible for the poor groundwater quality rendering most of the samples unsuitable for irrigation usage it is concluded that evaporation and mineral dissolution are the main processes that determine major ion compositions

high spatial resolution in vertical slice ocean acoustic tomography most studies of ocean acoustic tomography have assumed that little horizontal information is available from the many acoustic multipath travel times observed in a single vertical plane slice between source and receiver moorings there is in fact significant small scale information present in such data sets we examine single vertical slice tomography in spectral terms and show that the acoustic measurements resemble a high pass filter which is more sensitive to small scales shorter than 100 km than to longer scales with the exception of the mean which is well measured the sensitivity extends to scales smaller than 10 km in theory although the level of the ocean energy spectrum is so low at these scales that even small data errors limit the measurement we use analytical calculations supplemented by numerical simulations with realistic data sets to show that accurate reconstructions of the high wave number features are possible out to the limits of the parameterization 9 2 km wavelength when the power spectrum of the ocean features is white or red the total measurement error is 1 ms and multiple receivers are used the ultimate limit of spatial resolution may be smaller still depending on array configuration measurement errors and the shape of the power spectrum

3d velocity independent elliptically anisotropic moveout correction azimuthal anisotropy or lateral velocity variations cause azimuthal variations in moveout velocity which can degrade seismic images if handled improperly in cases in which apparent azimuthally anisotropic moveout is present a single picked velocity is inadequate to flatten an event on a 3d cmp gather conventional velocity analysis techniques require a significant amount of time and effort especially in areas where apparent anisotropy is observed we propose a velocity independent imaging approach to perform an elliptically anisotropic moveout correction in three dimensions the velocity independent approach relies on volumetric local traveltime slopes rather than aggregate velocities and therefore provides an azimuthally flexible description of traveltime geometries throughout the gather we derive theoretical expressions for extracting the moveout slowness matrix and the angle between the symmetry and acquisition axes as volumetric local attributes a practical inversion scheme to extract the same p

remote sensing of western boundary currents using acoustic tomography the utility of continuous long range acoustic transmissions between fixed sources and receivers to measure the deflection and speed of a western boundary current front along the transmission paths is discussed in a theoretical context a signal processing technique which utilizes both the amplitude and the phase of the acoustic arrivals is used to estimate the change in acoustic travel time with more accuracy than is possible by using only the amplitudes of the arrivals when the transmission path crosses the front only once and when the rotations of the front are confined to orientations that are within about 60 deg of the normal direction to the transmission path the deflection of the front can be measured with an accuracy of about 2 km over periods of a few days and its propagation speed can be measured with an accuracy of about 8 cm s errors are imposed by the changes in acoustic travel time that arise from the influence of the random fluctuations of internal waves the errors of the tomographic

hydrochemical and isotopic investigation of groundwater of al batin alluvial fan aquifer southern iraq major ions and important trace elements in addition to 18o and 2h were analysed for 43 groundwater samples sampled from the al batin alluvial fan aquifer south iraq the most dominant ions with respect to molarity were na cl so4 2 ca2 mg2 no3 hco3 with total dissolved solids tds averaging 7855 mg l high concentrations were found for the trace elements u mo v b sr and cr this study suggests a hydraulic connection exists near the fan apex between the uppermost part of the al batin aquifer and the underlying dammam aquifer by means of the abu jir fault system except for the effects of extensive irrigation fertilizer use and poorly maintained sewers the groundwater chemistry is mainly controlled by geological processes such as dissolution of evaporites and the enrichment of dissolved ions as a result of the high evaporation and low recharge rate furthermore it is shown that the kuwaiti fuel oil burning during gulf war in 1991 contributed to the enrichment of v and mo in the studied aquifer the spatial distribution of most ions appears to generally increase from the south west towards the north east in the direction of groundwater flow the stable isotopes show heavier values in groundwater with a gradually increasing trend in the direction of groundwater flow due to the decreasing depth to groundwater and thus increasing of evaporation from both groundwater or irrigation return water additionally the stable isotope signature suggests that rainfall from sources in the arabian gulf and the arabian sea is the major source of recharge for the al batin aquifer except for two samples of groundwater all samples were not suitable for potable use according to the who standards most of the groundwater is suitable for some agricultural purpose and for livestock water supply apart from the high salinity boron represents the most critical element in the groundwater with respect to agricultural purposes

water chemistry and isotope study of streams and springs in northern chile abstract the relationship between the stable isotopic and chemical composition of rain spring and stream water was studied in the high andes of northern chile the isotopic pattern of the springs is mainly a reflection of the altitude of their recharge areas however processes that occur during snow melting seem to play a major role in the high altitude springs the streams show patterns similar to the springs in the higher part of the basins but their isotopic composition is modified along the river course due mainly to evaporation the difference in chemical composition between the springs at high and intermediate elevations reflects the duration of water rock interaction the best parameter to trace this length of travelling time is the na k ratio which increases as a result of removal of k into alteration minerals k silicates the na cl ratio increases with salinity in springs and decreases in stream water this reflects the different sources of salt whereas the main source of salts in spring water is the dissolution of silicate and sulfide minerals halite accumulations close to the surface is the main salt source in the streams during floods the stream water chemical characteristics change na cl increases with decreased salinity and na k decreases

chemical characteristics of groundwater in parts of mountainous region alvand hamadan iran eighty seven groundwater samples have been collected from a mountainous region alvand iran for hydrochemical investigations to understand the sources of dissolved ions and assess the chemical quality of the groundwater most water quality parameters are within world health organization acceptable limits set for drinking water the least mineralized water is found closest to the main recharge zones and the salinity of water increased towards the north of the basin the most prevalent water type is ca hco3 followed by water types ca no3 ca cl ca so4 and mg hco3 the ca no3 water type is associated with high nitrate pollution agricultural and industrial activities were associated with elevated level of no3 mineral dissolution weathering of evaporites dominates the major element hydrochemistry of the area chemical properties of groundwater in alvand region are controlled both by natural geochemical processes and anthropogenic activities

mapping of moveout attributes using local slopes decomposing seismic data in local slopes is the basic idea behind velocity independent imaging using accurate moveout approximations enables computing moveout attributes such as normal moveout velocity and nonhyperbolic parameters as functions of zero offset travel time mapping of moveout attributes is performed from the pre stack seismic data domain into the time migrated image domain the different moveout attributes have different accuracy for a given moveout approximation that depends on the corresponding order of travel time derivative the most accurate attribute is the zero offset travel time and the nonhyperbolic parameter has the worst accuracy regardless of the moveout approximation typically the mapping of moveout attributes is performed using a point to point procedure whereas the generalized moveout approximation requires two point to point mappings testing the attribute mapping on the different models shows that the accuracy of mapped attributes is model dependent whereas the generalized moveout approximation gives practically exact results

a review of ocean acoustic tomography 1987 1990 the techniques and instruments used in acoustic tomography of the oceans are surveyed and results are summarized sections are devoted to theoretical studies and numerical simulations mesoscale mapping vertical slice tomography flow imaging and nonlinear bias series of tomographic experiments analyses to identify global changes and outstanding problems the forward and inverse problems and ocean physics typical data are presented in tables and graphs and a comprehensive bibliography is provided 72 refs

geochemical and isotopic characterization of groundwater from shallow and deep limestone aquifers system of aleppo basin north syria stable isotopes 18o 2h and 13c and radioactivity 3h 14c have been used in conjunction with chemical data to evaluate the processes generating the chemical composition reconstruct the origin of the water and groundwater residence time the aleppo basin is comprised of two main limestone aquifers the first one is unconfined of paleogene age and the second is confined of upper cretaceous age the chemical data indicate that the dissolution of minerals and evaporation are the main processes controlling groundwater mineralization the groundwater from the two aquifers is characterized by distinctive stable isotope signatures this difference in water isotopes is interpreted in terms of difference origin and recharge period fresh and brackish shallow groundwater were mostly recharged during the holocene period the presence of 3h in several groundwater samples of this aquifer gives evidence that groundwater recharge is going on brackish water of the deep confined aquifer has depleted stable isotope composition and very low 14c activity that indicates recharge during the late pleistocene cold period

geochemistry characterization of groundwater in an agricultural area of razan hamadan iran this study was conducted to evaluate factors regulating groundwater quality in an area with agriculture as main use thirty groundwater samples have been collected from razan area hamadan iran for hydrochemical investigations to understand the sources of dissolved ions and assess the chemical quality of the groundwater the chemical compositions of the groundwater are dominated by na ca2 hco3 cl and so42 which have been derived largely from natural chemical weathering of carbonate gypsum and anthropogenic activities of fertilizer s source the production of so42 has multiple origins mainly from dissolution of sulphate minerals oxidation of sulphide minerals and anthropogenic sources the major anthropogenic components in the groundwater include na cl so42 and no3 with cl and no3 being the main contributors to groundwater pollution in razan area

basin scale tomography a new tool for studying weather and climate we present the first experimental results demonstrating the use of acoustic tomography to observe the large scale 500 km temperature fluctuations in ocean basins use of the tomographic technique as presented here will eventually lead to a better understanding of weather climate ocean circulation and the distributions of marine organisms from june to september 1987 tomographic signals were transmitted between four sources and nine receivers over a 3000 by 4000 km region the basin scale in the northeast pacific this paper discusses five issues related to transmissions across one 3000 km section first basin scale tomography is feasible because multipaths are stable in the presence of ocean fluctuations and the multipaths can be understood with ray theory and its extensions second the tomography problem can be initiated from climatological estimates it is unnecessary to initiate with conventional measurements during the experiment a prohibitively expensive proposition third a description of the tomographic reconstruction procedure kalman filtering is presented the filter imposes temporal and spatial constraints on the solution for the thermal field fourth the sensitivity of the estimated thermal field is examined with respect to variations of the constraints thermal maps are not very sensitive to variations of the constraints fifth tomography is used to observe significant changes from month to month in the large scale thermal field in the ocean including the seasonal thermocline where week to week resolution can be obtained in contrast available point measurements appear to be insufficient for observing monthly changes in the large scale thermal field in the ocean these acoustic measures of weather and climate in the ocean cannot be verified with other data e g satellites point measurements and thus provide an orthogonal perspective by which weather and climate may be observed and understood

estimation of sea surface wave spectra using acoustic tomography ocean acoustic tomography signals that interact with the ocean surface suffer travel time perturbations which have information on the frequency direction spectrum of that surface in this paper a technique for tomographically estimating spatially varying frequency direction spectra is introduced to demonstrate this technique synthetic signal spectra data were generated using an empirical model for a fetch limited sea the synthetic data were then inverted using linear inverse techniques to produce an estimate of the original sea surface spectra inverse solutions for both noise free and noisy experiments are presented and discussed

hydrogeochemical assessment of groundwater in isfahan province iran groundwater quality in five catchment areas in isfahan province of iran is assessed by measuring physicochemical parameters including major cation and anion compositions ph total dissolved solid electrical conductivity and total hardness for this purpose 567 piezometric well samples were collected in october 2007 the abundance of major ions in four of the catchment areas including gavkhuni ardestan salt lake and central iran desert basins is similar and follows cl so42 na hco3 ca2 mg2 k co32 trend while in the fifth basin karoon the trend changes into hco3 ca2 cl so42 mg2 na k co32 in general four water facies are determined and it is shown that alkali elements and strong acids are dominating over alkaline earth and weak acids statistical analysis including mann whitney u test indicate that physicochemical parameters in three of the five investigated basins gavkhuni ardestan and central iran desert cid are similar while karoon and salt lake basins display different characteristics the result indicate that groundwater west of the province is suitable for irrigation while in the central and eastern parts of the province the groundwater loses its quality for this purpose it is concluded that mineral dissolution and evapotranspiration are the main processes that determine major ion compositions

theory of acoustic measurement of internal wave strength as a function of depth horizontal position and time high frequency 1 cpd variations in travel time of acoustic transmissions over ocean mesoscale distances are known to be dominated by the effects of internal wave displacements of the sound speed stratification flatte et al 1979 flatte 1983a variations in the difference in travel time between transmissions in opposite directions along the same path reciprocal transmissions are dominated by internal wave currents munk et al 1981 we investigate the usefulness of a two mooring acoustic system for determining the statistical variances of internal wave displacements and currents as a function of depth geographical position and time we find that statistical fluctuations in the internal wave field itself prevent recovery of range dependent information between the two moorings however range averaged information can be obtained about mean energy level and about vertical energy migration we find that uncertainties in the buoyancy and sound speed profiles do not significantly affect the usefulness of the method

the principal components statistical method as a complementary approach to geochemical methods in water quality factor identification application to the coastal plain aquifer of israel abstract in general schoeller and piper diagrams as well as other classical techniques facilitate the description of the various geochemical groups of water and help to explain quality changes in an aquifer we propose the use mainly of principal components analysis for identification of relevant groups of water and the factors that bring about a change in their quality the major advantage of this method is its suitability for simultaneous analysis of a great number of variables and observations it is here being applied for the investigation of the dan metropolitan region of israel s coastal plain the variables involved include major ions as well as the physical factors of depth of the well intake filter below sea level distance from the sea and aquifer recharge the primary purpose of this work is to demonstrate the use and reliability of principal components analysis pca as a method complementary to classical approaches for hydrogeochemical research subsidiary purposes involve determination of the major water groups characterizing the coastal plain aquifer identification of some of the principal variables that influence changes in water quality in the aquifer and description of some of the geochemical phenomena contributing to change in aquifer water quality the following results were achieved for the test area 1 1 two major groups of water were identified a low salinity calcium bicarbonate water occurring in the phreatic portion of the coastal plain aquifer and a more saline sodium chloride water characterizing the neighboring cenomanian aquifer and the confined portions of the coastal plain aquifer 2 2 the major water input sources such as rain injection water waste water irrigation etc may vary in their influence upon resulting water quality this water quality is affected by such physical factors as distance from the sea depth of well intake filters below sea level proximity to streams and the lithology of the saturated and unsaturated zones 3 3 the evolutionary alteration in content of specific ions with time can be clearly visualized on the same graph by means of pca the universal applicability of such a statistical approach to other hydrological settings is noted

the effect of carbonates and gypsum precipitation in the root zone on the chemical composition of groundwater dissolution of a solid phase in the unsaturated zone is usually assumed to be the main factor transforming the composition of atmospheric water to that of groundwater however the opposite mechanism namely a precipitation of insoluble and slightly soluble salts from rain water penetrating the root zone may predominate especially in arid regions field study of pore fluids in the unsaturated zone was carried out in the southern ukraine where the climate is temperate continental pore fluid samples were taken from soils and loessial loams at different depths in boreholes of about 1 m diameter with insulated walls the bore holes were drilled to groundwater levels situated in loess loams at depths of 10 24 m the sampling was performed using vacuum lysimeters in the upper 0 5 2 5 m well washed layer the infiltrating water composition changed from a hco3 so4 ca type water to a so4 na type the latter corresponding to groundwater composition the root zone acts as a geochemical barrier which retains the calcium predominating in rain and irrigation water owing to calcite and gypsum precipitation this precipitation is accompanied by hco3 and so4 removal from the pore fluids and by an increase in the total dissolved solids tds as a result of evapotranspiration the observed profiles of calcium concentration in pore fluids the manifestations of alkalization and the calcite accumulation are explained by the precipitating action of the root zone similar patterns were found in loess covered arid regions of southern israel the negev on the basis of reported data on the composition of rain water saturated soil extracts and the phreatic groundwater in sediments of the avedat group a simple steady state model of the transformation of rainwater composition to groundwater composition was developed and applied it is based on the exclusion of ca mg carbonates and gypsum from rain water annual precipitation rates 6 13 g m 2 year 1 and the composition of precipitated salts calculated for the negev are in agreement with data reported in the literature it is shown that carbonate and gypsum precipitation in the root zone may explain the change of the hco3 ca type of rain water to the so4 na or cl na type of groundwater which is fed by it under different climatic conditions

oriented surface passive seismic location using local slopes abstracta common acquisition scenario in microseismic monitoring is the deployment of large areal receiver arrays at or near the surface this recording geometry has the advantage of providing coverage of the source s focal hemisphere as well as characterization of the arrival time moveout curve however the accuracy of many location techniques applied to these data sets depends on the accuracy of the depth velocity model provided prior to location we have developed a simple oriented time domain location technique so that full knowledge of the velocity model is not required a priori the applicability of the technique is limited to horizontally layered models and also to models with dipping interfaces of small angles however this restriction is acceptable in many unconventional reservoirs implementation of the technique includes three steps 1 smoothing of the observed time arrivals by fitting a hyperbolic moveout curve with a broad set of constraints 2 updating and restricting the constraints u

hydrogeochemistry of continental brackish waters in the southern coastal plain israel abstract the southern coastal plain in israel incorportates a transitional fringe of the desert in which three different chemical types of groundwater are found 1 near surface waters from springs along the besor river course 2 shallow to moderate depth waters from the slightly westward dipping pleistocene coastal aquifer this aquifer which consists of sandstone layers of the kurkar group is recharged in the coastal plain and 3 deep waters of the westward dipping upper cretaceous judea group carbonates which are recharged in the mountains in the east a thick aquiclude of upper cretaceous tertiary rocks separates the judea group aquifer from the overlying coastal aquifer in the southern coastal plain isotopically light oxygen and depleted deuterium characterize the judea group waters as expected from high altitude recharge the isotopic composition of the coastal plain waters is variable but for the most part enriched in 18o and d within the southern coastal plain aquifer a southern subgroup comprises waters more depleted in heavy isotopes than those of either the northern or eastern subgroups the besor waters are isotopically similar to the judea group waters reflecting their origin in the mountain region and flow through the surficial river gravels and sands it is suggested that leakage of the besor waters into the underlying southern coastal plain aquifer results in mixing of the two water types the most prominent chemical feature characterizing the groundwater of the southern coastal plain is na cl 1 this na cl ratio can be maintained only by a continuous input from a non marine source of na the most plausible source of this na is the dissolution of feldspar derived from the windblown loess deposits which cover the area and or leaching of trona minerals found in the unsaturated zone combined with base exchange processes

suitability assessment of deep groundwater for drinking and irrigation use in the djeffara aquifers northern gabes south eastern tunisia the multilayered djeffara aquifer system south eastern tunisia has been intensively used as a primary source to meet the growing needs of the various sectors drinking agricultural and industrial purposes the analysis of groundwater chemical characteristics provides much important information useful in water resources management detailed knowledge of the geochemical evolution of groundwater and assessing the water quality status for special use are the main objective of any water monitoring study an attempt has been made for the first time in this region to characterize aquifer behavior and appreciate the quality and or the suitability of groundwater for drinking and irrigation purposes in order to attend this objective a total of 54 groundwater samples were collected and analyzed during january 2008 for the major cations sodium calcium magnesium and potassium anions chloride sulfate bicarbonate trace elements boron strontium and fluoride and physicochemical parameters temperature ph total dissolved salts and electrical conductivity the evolution of chemical composition of groundwater from recharge areas to discharge areas is characterized by increasing sodium chloride and sulfate contents as a result of leaching of evaporite rock in this study three distinct chemical trends in groundwater were identified the major reactions responsible for the chemical evolution of groundwater in the investigated area fall into three categories 1 calcite precipitation 2 gypsum and halite dissolution and 3 ion exchange based on the physicochemical analyses irrigation quality parameters such as sodium absorption ratio sar percentage of sodium residual sodium carbonate residual sodium bicarbonate and permeability index pi were calculated in addition groundwater quality maps were elabortaed using the geographic information system to delineate spatial variation in physico chemical characteristics of the groundwater samples the integration of various dataset indicates that the groundwater of the djeffara aquifers of the northern gabes is generally very hard brackish and high to very high saline and alkaline in nature the water suitability for drinking and irrigation purposes was evaluated by comparing the values of different water quality parameters with world health organization who guideline values for drinking water piper trilinear diagram was constructed to identify groundwater groups where the relative major anionic and cationic concentrations are expressed in percentage of the milliequivalent per liter meq l and it was demonstrated that the majority of the samples belongs to so4 cl ca na cl so4 na ca and na cl hydrochemical facies as a whole all the analyzed waters from this groundwater have revealed that this water is unsuitable for drinking purposes when comparing to the drinking water standards salinity high electric conductivity sodium adsorption ratio and sodium percentages indicate that most of the groundwater samples are inappropriate for irrigation the sar vary from medium s2 to very high s4 sodicity therefore the water of the djeffara aquifers of the northern gabes is dominantly of the c4 s2 class representing 61 23 of the total wells followed by c4 s3 and c4 s4 classes at 27 27 and 11 5 of the wells respectively based on the us salinity classification most of the groundwater is unsuitable for irrigation due to its high salt content unless certain measures for salinity control are undertaken

use of isotopic tracers to characterize the interaction of water components and nitrate contamination in the arid rasafeh area syria chemical and isotopic data in atmospheric precipitation surface water and groundwater in arid rasafeh area northeast syria are used to clarify the status of groundwater quality the interaction of water components groundwater dating and vulnerability to anthropogenic contamination interpretation of chemical data with thermodynamic calculation reveals that the dissolution of evaporate mineral is the main factor of high salinity the 18o and 2h relationships indicate that the groundwater is fed by mixing water from euphrates river and precipitation and the isotope balance equation were used to estimate the contribution of the euphrates river to the aquifers recharge high tritium content together with high 14c activity in the majority of groundwater samples indicate shorter residence times and consequently potentially greater recharge the presence of high nitrate concentration associated with high tritium concentration in both shallow and deep aquifer units indicates the presence of high permeability so that groundwater is highly susceptible to anthropogenic contamination nitrate seems to derive exclusively from the application of n fertilizers the high nitrate values are characteristic of the areas with intensive agricultural activity indicating the importance of irrigated return flow on the groundwater

velocity independent τ p moveout in a horizontally layered vti medium local slopes of seismic events carry complete information about the structure of the subsurface this information is sufficient for accomplishing all time domain imaging tasks without the need to estimate or know the seismic velocity model a velocity independent p imaging approach has been developed to perform moveout correction in horizontally layered vertical transverse isotropy vti media the effective and interval anisotropic parameters are transformed into data attributes through the use of slopes and become directly mappable to the zero slope traveltime the p transform is the natural domain for anisotropy parameter estimation in layered media because the phase velocity is given explicitly in terms of p therefore the p transform permits reflection traveltime modeling and inversion that are simpler than traditional methods which are based on taylor series expansions of traveltime in the t x domain synthetic and field data tests demonstrate the practical effectiveness of the p

geochemical and isotopic characterization of groundwater from the paleogene limestone aquifer of the upper jezireh syria this research aims to evaluate the groundwater resources of paleogene aquifer in the upper jazireh area syria in terms of chemical water type recharge zones and water ages the results show that the main recharge zones for the paleogene aquifer range between 650 and 900 m a s l which coincide with the outcrop of the karstified limestone in the mardin uplift the chemical and isotopic behaviors of groundwater together with radiometric 14c reflect the existence of three different groundwater groups 1 the fresh and cold water percolating in short and shallow flow paths for which the main replenishment processes are recent 2 the brackish and thermal water containing certain amounts of h2s gas that percolate in longer and deeper flow paths for which the main replenishment processes occurred during the palaeoclimatic humid conditions of pleistocene time placed at 10 18 ka bp 3 the brackish and admixed thermal groundwater with intermediate 14c age which seems to be formed as a result of mixing between the previous two groups

ocean acoustic tomography travel time biases the travel times of acoustic rays traced through a climatological sound speed profile are compared with travel times computed through the same profile containing an eddy field the exact travel time difference is compared with its constituent terms one of which is linearly related to the deviation of the sound speed referenced to the climatological profile and the others which are nonlinearly related to the deviation at ranges that are much greater than the eddy scale and for eddy fields whose range averaged temperature anomaly is small the numerical results are 1 the values of the nonlinear terms are insensitive to changes in the positions of the eddies and 2 the nonlinear terms are approximately proportional to the range between the source and receiver and to the square of the eddy anomaly at a 1084 km range in the east atlantic at 24 n 36 n the nonlinear terms can account for 17 90 of the exact travel time change where the temperature anomalies associated with the eddies are typicall

the use of na cl ratios to trace solute sources in a semiarid zone rainwater interaction with soils is a major source of dissolved salts in groundwater the transition zone between the humid and the arid area is characterized by a specific combination of reactions which do not exist elsewhere this combination of caco3 dissolution and base exchange reactions affects the na cl ratio which is the quantitatively most important parameter used for tracing salinity sources of groundwater the increase in the na cl ratio in the coastal plain aquifer of israel from north to south is related to local recharge of na rich water after interaction with soils of loessial origin

velocity independent estimation of kinematic attributes in vertical transverse isotropy media using local slopes and predictive painting abstractagood seismic velocity model is required for many routine seismic imaging techniques velocity model building from seismic data is often labor intensive and time consuming the process becomes more complicated by taking nonhyperbolic traveltime estimations into account an alternative to the conventional time domain imaging algorithms is to use techniques based on the local event slopes which contain sufficient information about the traveltime moveout for velocity estimation and characterization of the subsurface geologic structures given the local slopes there is no need for a prior knowledge of a velocity model that is why the term velocity independent is commonly used for such techniques we improved upon and simplified the previous versions of velocity independent nonhyperbolic approximations for horizontally layered vertical transverse isotropy vti media by removing one order of differentiation with respect to offset from the imaging kinematic attributes these kinematic attributes ar