strontium isotopes and rare earth elements as tracers of groundwater lake water interactions lake naivasha kenya abstract strontium isotope compositions and rare earth element ree concentrations are presented for groundwater and surface water samples collected from the lake naivasha watershed in the east african rift kenya the chief objective of the study is to test the suitability of rees in conjunction with sr isotopes as tools for investigating groundwater lake water interactions in general the ree concentrations and 87 sr 86 sr ratios support the authors earlier investigations where cl mass balance 18 o d and he isotopes were employed to study groundwater lake water interactions in the naivasha watershed the ree data suggest that a significant amount of the groundwater south of lake naivasha i e 50 85 consists of lake water recharge to the aquifer system specifically mixing calculations conducted using ree data of lake naivasha water and groundwaters indicate that between 70 and 85 of groundwater directly south of the lake is likely lake water these values are somewhat higher than the authors previous estimates determined with conservative stable h isotopes d 50 70 for both cases however the data demonstrate that water originating in lake naivasha contributes significantly to the underlying groundwater flow system hence supporting earlier evidence that the lake s freshness reflects rapid loss of water and dissolved solutes to the local groundwater system overall lake and groundwater sr isotope compositions support seepage of lake water into the underlying aquifer along the lake s south shore the 87 sr 86 sr data also provide additional insight into the geochemical evolution of waters of the lake naivasha watershed indicating that the initial source of sr to these waters is likely chemical weathering reactions involving basaltic rocks within the recharge zones of the watershed along the rift valley flanks furthermore with increasing residence time of groundwaters within the aquifer system and flow down and along the rift valley floor sr isotope compositions of groundwaters become more radiogenic reflecting rock water interactions with chemically differentiated and radiogenic peralkaline rhyolite volcanic rocks the importance of the longer aquifer residence times and radiogenic source rocks is especially apparent for geothermal waters of the olkaria geothermal field that have 87 sr 86 sr ratios i e 0 70747 similar to local comendites

comments on carbonatites in a subduction system the pleistocene alvikites from mt vulture southern italy by d orazio et al 2007 abstract d orazio m innocenti f tonarini s doglioni c 2007 carbonatites in a subduction system the pleistocene alvikites from mt vulture southern italy lithos 98 313 334 describe a new finding of alvikite ca carbonatite at vulture they stress its importance as being the first carbonatite to be discovered in a subduction environment they suggest that this rock is different from the other italian carbonatites considered as rocks sharing a carbonatitic affinity which are radiogenic and chemically diluted by addition of sedimentary limestone they note that vulture alvikite is not diluted and is very unradiogenic with respect to other italian carbonatites however they maintain that vulture alvikite carbonate is derived from subducted limestones we present an account of the field relationships relating to the above mentioned rocks setting the geological and petrographic records straight and describing pyroclastic rocks we did not find that these rocks are formed from alvikite dykes or lava but instead recognised them to be a continuous blanket of flaggy welded tuff we found that the rocks consist of physically separated melilitite and carbonatite juvenile lapilli settled into a carbonatite ash matrix form the rock we disagree with the geochemical interpretation of the rock by d orazio m innocenti f tonarini s doglioni c 2007 carbonatites in a subduction system the pleistocene alvikites from mt vulture southern italy lithos 98 313 334 and are particularly concerned by their conclusion of its carbonate origin we remark on the rock s geodynamic assignment in the frame of an extensional tectonic setting also referring to the other italian carbonatite occurrences we reject any ad hoc modified subduction as a direct source of vulture and italian carbonatites

controls on transport and fractionation of the rare earth elements in stream water of a mixed basaltic granitic catchment basin massif central france abstract we present rare earth element ree patterns of small streams from a catchment basin in the massif central france in order to characterize the individual fractionation stages for the dissolved ree from the source to the catchment outlet the upper part of the catchment is located on a basalt plateau followed downstream by deep and narrow valleys within granitic and orthogneissic bedrock basalt normalized 0 45 m filtered stream water has ree patterns slightly depleted in the light ree la sm lree on the basalt plateau close to the source followed by a continuous amplification of this lree depletion downstream at the same time also a negative ce anomaly develops in the adsorbed fraction of 0 45 m particles which has been isolated by leaching with 1 m hcl strontium and neodymium isotope ratios of stream water demonstrate that the dissolved ree are essentially of basaltic origin even in the lower granitic and gneissic part of the catchment mixing with gneiss or granite derived ree thus cannot explain the observed evolution of the ree patterns our data suggest that the ree of the 0 45 m particles in contrast to earlier studies we found no link between ree behavior and organic colloids or organic complexes this scenario is confirmed by a detailed analysis of the ree patterns at 3 stream confluences the results show that the ree do not behave conservatively during mixing at stream confluences but that the lree and ce are preferentially removed similarly to what has been observed at catchment scale our study thus underlines the importance of fe colloids for the transport and fractionation of the ree in stream water

controls on the geochemistry of rare earth elements along a groundwater flow path in the carrizo sand aquifer texas usa groundwater samples were collected along a groundwater flow path in the carrizo sand aquifer in south texas usa field measurements that included ph specific conductivity temperature dissolved oxygen do oxidation reduction potentials eh in mv alkalinity iron speciation and h2s concentrations were also conducted on site the geochemistry i e concentrations shale normalized patterns and speciation of dissolved rare element elements rees in the carrizo groundwaters are described as a function of distance along a flow path eh and other redox indicators i e do fe speciation h2s u and re indicate that redox conditions change along the flow path in the carrizo sand aquifer within the region of the aquifer proximal to the recharge zone groundwaters exhibit both highly oxidizing and localized mildly reducing conditions however from roughly 10 km to the discharge zone groundwaters are reducing and exhibit a progressive decrease in redox conditions dissolved ree geochemical behavior exhibits regular variations along the groundwater flow path in the carrizo sand aquifer the changes in ree concentrations shale normalized patterns and speciation indicate that rees are not conservative tracers with flow down gradient redox conditions ph and solution composite and adsorption modify groundwater ree concentrations fractionation patterns and speciation

assessment of earthquake hazard in the tokyo area japan abstract the probability of occurrence of an inland earthquake originating beneath the tokyo area is evaluated for a 10 year period from 1991 on the basis of an earthquake catalogue containing some 40 earthquakes which caused some damage to edo now tokyo over a period of 400 years the parameters of the weibull and lognormal probability distributions applied to recurrence interval statistics are estimated with these parameters it is concluded that an earthquake directly beneath the capital the magnitude of which is equal to or greater than 6 0 occurs with a probability of 0 40 for the period in question when the magnitude threshold is assumed as 6 4 and 7 0 the probabilities become 0 17 and 0 049 respectively these probability evaluations are extended to those for the seismic intensity at typical sites in the area although no accurate evaluation is possible because the exact focal depths of historical earthquakes are not known on the assumption that these earthquakes occur near the upper surface of the down going philippine sea plate however a typical depth of 30 km or so is suggested should an earthquake having a mean magnitude of 6 4 say and at a mean location of past earthquakes occur the probability of seismic intensity at typical sites in the capital area exceeding 5 on the japan meteorological agency jma scale would amount to 0 17 the possibility of having a highly damaging earthquake of intensity 6 on the jma scale also cannot be ruled out judging from earthquake disasters in the past although the probability does become lower to summarize it may be said that the probability of japan s capital area being hit by a damaging earthquake in the foreseeable future is not particularly low

geochemical behaviors of rare earth elements in groundwater along a flow path in the north china plain abstract rare earth element ree geochemistry is a useful tool in delineating hydrogeochemical processes and tracing solute transport which can be used to reveal groundwater chemical evolution in the complexed groundwater systems of the north china plain ncp groundwaters and sediments were collected approximately along a flow path in shallow and deep aquifers of the ncp to investigate ree geochemistry as a function of distance from the recharge zone groundwater ree concentrations are relatively low with ranges from 81 2 to 163 6 ng l in shallow groundwaters and from 65 2 to 133 7 ng l in deep groundwaters speciation calculation suggests that dissolved rees mainly occur as dicarbonato ln co3 2 and carbonato lnco3 complexes although along the flow path groundwater ree concentrations do not vary substantially relatively lower hrees are observed in central plain zone ii compared to recharge area zone i and discharge plain zone iii shale normalized ree patterns are characterized by different degrees of enrichment in the hrees as indicated by the variation in average er nd nasc value the similar ree compositions and shale normalized ree patterns of shallow and deep groundwaters demonstrate that interactions of groundwaters between shallow and deep aquifers possibly occur which is likely due to the long term groundwater over exploration cerium anomalies ce ce cenasc lanasc prnasc 0 5 generally increase from zone i through zone ii to zone iii with trends from 0 79 to 3 58 and from 1 22 to 2 43 in shallow groundwaters and deep groundwaters respectively this is consistent with the variations in oxidation reduction potential and redox sensitive components i e dissolved fe mn no3 and as concentrations along the flow path positive ce anomaly and redox indicators suggest that redox conditions progressively evolve from oxic to moderate anaerobic in the direction of groundwater flow in the recharge zone zone i groundwater low positive ce anomalies are likely due to partially oxidative scavenging of ce iii to ce iv and hree enrichment would result from preferential scavenging of the lrees relative to the hrees during fe mn oxides oxyhydroxides precipitations which is well supported by the low concentrations of dissolved fe and mn in the down gradient zone ii and zone iii reductive dissolution of fe mn oxides oxyhydroxides increases positive ce anomalies along the flow path the positive correlations between er nd nasc values and dissolved fe mn concentrations suggest that reductive dissolution of fe mn oxides oxyhydroxides as well as readsorption are the geochemical controls on groundwater ree fractionation patterns groundwaters mostly have positive eu anomalies eu eu eunasc smnasc gdnasc 0 5 which would be the result of chemical weathering of feldspars e g plagioclase detected in aquifer sediments by xrd technique

probabilistic assessment of tsunami recurrence in the indian ocean the indian ocean is one of the most tsunamigenic regions of the world and recently experienced a mega tsunami in the sumatra region on 26 december 2004 m w 9 2 earthquake with tsunami intensity i soloviev imamura intensity scale equal to 4 5 causing heavy destruction of lives and property in the indian ocean rim countries in this study probabilities of occurrences of large tsunamis with tsunami intensities i 2 0 and i 3 0 average wave heights h 2 83 m and h 5 66 m respectively during a specified time interval were calculated using three stochastic models namely weibull gamma and lognormal tsunami recurrence was calculated for the whole indian ocean and the special case of the andaman sumatra java asj region excluding the 1945 makran event from the main data set for this purpose a reliable homogeneous and complete tsunami catalogue with i 2 0 during the period 1797 2006 was used the tsunami hazard parameters were estimated using the method of maximum likelihood the logarithm of likelihood function ln l was estimated and used to test the suitability of models in the examined region the weibull model was observed to be the most suitable model to estimate tsunami recurrence in the region the sample mean intervals of occurrences of tsunamis with intensity i 2 0 and i 3 0 were calculated for the observed data as well as for the weibull gamma and lognormal models the estimated cumulative and conditional probabilities in the whole indian ocean region show recurrence periods of about 27 30 years 2033 2036 and 35 36 years 2039 2040 for tsunami intensities i 2 0 and i 3 0 respectively while it is about 31 35 years 2037 2041 and 41 42 years 2045 2046 for a tsunami of intensity i 2 0 and i 3 0 respectively in the asj region a high probability 0 9 of occurrence of large tsunamis with i 2 0 in the next 30 40 years in the indian ocean region was revealed

behaviour of rare earth elements and yttrium in ferromanganese concretions gibbsite spots and the surrounding terra rossa over dolomite during chemical weathering abstract the behaviour of rare earth elements rees and yttrium y during chemical weathering processes has been investigated on a 4 05 m thick terra rossa profile over dolomite on the yunnan guizhou plateau china in this profile ferromanganese concretions and gibbsite spots coexist in the terra rossa solum analyses of rees y zr f s and toc as well as mineralogical studies were conducted on a suite of ferromanganese concretions gibbsite spots terra rossas dolomites and insoluble residues from the underlying dolomite these analyses helped us to understand the mobilization redistribution and fractionation of rees and y during chemical weathering the rees and y are mobilized and redistributed during the terra rossa formation rees except for ce are removed from the upper and middle profiles transferred downwards and then precipitated in the base profile resulting in remarkable enrichment in the terra rossa near the weathering front the significant increase of ph near the weathering front was responsible for ree excluding ce and y enrichment in the base profile y is quite mobile during extreme chemical weathering and most of it was carried away from the profile because of very efficient oxidative fractionation of ce a significant positive ce anomaly in terra rossa was found in the middle of the profile whereas the terra rossa near the weathering front exhibited notably negative ce anomalies moreover the presence of cerianite and its content in the ferromanganese concretions can explain the markedly positive ce anomaly and the variation of ce ce values with depth in profile these ce anomalies are characteristic of the geochemical environment especially the redox condition studies of ree distribution in the ferromanganese concretions gibbsite spots and surrounding terra rossa revealed that significant ree fractionation occurred rees and y were preferentially concentrated in the ferromanganese concretions rather than in the gibbsite spots the water rock interaction resulted in m type tetrad effects in some of the ferromanganese concretions gibbsite spots and terra rossa samples in addition the tetrad effect in terrestrial weathering processes likely played an important role in the fractionation of rees and y such as y ho sm nd and the eu anomaly change

submarine groundwater discharge is an important net source of light and middle rees to coastal waters of the indian river lagoon florida usa abstract porewater i e groundwater samples were collected from multi level piezometers across the freshwater saltwater seepage face within the indian river lagoon subterranean estuary along florida s usa atlantic coast for analysis of the rare earth elements ree surface water samples for ree analysis were also collected from the water column of the indian river lagoon as well as two local rivers eau gallie river crane creek that flow into the lagoon within the study area concentrations of rees in porewaters from the subterranean estuary are 10 100 times higher than typical seawater values e g nd ranges from 217 to 2409 pmol kg 1 with submarine groundwater discharge sgd at the freshwater saltwater seepage face exhibiting the highest ree concentrations the elevated ree concentrations for sgd at the seepage face are too high to be the result of simple binary mixing between a seawater end member and local terrestrial sgd instead the high ree concentrations indicate that geochemical reactions occurring within the subterranean estuary contribute substantially to the ree cycle a simple mass balance model is used to investigate the cycling of rees in the indian river lagoon and its underlying subterranean estuary mass balance modeling reveals that the indian river lagoon is approximately at steady state with respect to the ree fluxes into and out of the lagoon however the subterranean estuary is not at steady state with respect to the ree fluxes specifically the model suggests that the sgd nd flux for example exported from the subterranean estuary to the overlying lagoon waters exceeds the combined input to the subterranean estuary from terrestrial sgd and recirculating marine sgd by on average 100 mmol day 1 the mass balance model also reveals that the subterranean estuary is a net source of light rees lree and middle rees mree to the overlying lagoon waters but acts as a sink for the heavy rees hree geochemical modeling and statistical analysis further suggests that this fractionation occurs in part due to the coupling between ree cycling and iron redox cycling within the indian river lagoon subterranean estuary the net sgd flux of nd to the indian river lagoon is 7 fold larger than the local effective river flux to these coastal waters this previously unrecognized source of nd to the coastal ocean could conceivably be important to the global oceanic nd budget and help to resolve the oceanic nd paradox by accounting for a substantial fraction of the hypothesized missing nd flux to the ocean

rare earth elements as geochemical tracers of regional groundwater mixing abstract the rare earth elements ree were analyzed in a groundwater system from south central nevada i e ash meadows national wildlife refuge the spring mountains pahranagat national wildlife refuge and the nevada test site in order to investigate their potential use as tracers of regional groundwater flow previous investigations using conservative tracers e g deuterium and uranium isotopes identified recharge in local mountains as the primary source 60 70 of total discharge for the springs in the regional discharge zone i e ash meadows with the remaining contribution being interbasin flow from the northeast initial mixing calculations for these groundwaters using shale normalized ree patterns agreed well with the previous studies however because the rees are not expected to behave conservatively in natural waters the effect of both solution complexation which acts to enhance the stability of the rees in solution as well as surface complexation responsible for the particle reactive behavior of the rees were examined in subsequent mixing calculations in order to assess the roles of solution and surface complexation relative partitioning coefficients were estimated for each ree in each groundwater by evaluating the ratio of the ionic strength corrected co 3 1 ree co 3 2 ree and co 3 2 f to the first hydrolysis binding constants for the rees the relative partitioning coefficients were then used to calculate ree patterns expected to develop and persist in solution as a consequence of solution and surface complexation the calculated ree values closely resembled the actual measured ree concentrations suggesting that the rees are in fact controlled by solution and surface complexation in these groundwaters the calculated ree concentrations were subsequently used to determine mixing ratios the results of which coincided with the initial calculations as well as the previous studies the results of this study suggest that solution complexation of the rees is sufficient to overcome to a certain degree the affinity of the rees to be adsorbed onto surface sites in the aquifers such that distinctive ree signatures develop and persist in solution in groundwaters from different aquifers the ability of solution complexation to overcome surface complexation is likely related to the formation of the negatively charged dicarbonato complex i e ln co 3 2 where ln is any ree which accounts for significant fractions of each ree in these groundwaters

the root of the urals evidence from wide angle reflection seismics abstract the existence of a crustal root beneath the urals which would deflect the position of the moho by some 20 km is still largely controversial a french russian project carried out a wide angle reflection seismic experiment across the middle urals to image the moho topography along a 175 km profile running approximately east west north of ekaterinburg new data show a 6 km moho deflection beneath the central part of the orogen the moho reflectivity is variable along the section with very sharp reflections beneath the russian platform 45 km depth and fainter attenuated signals in the root zone 51 km depth even if this crustal root is not as thick as indicated by some previous speculations it makes the urals the only palaeozoic orogen in the world to show such a peculiarity a major ultramafic overload in the upper crust would partly balance the crustal root in accordance with isostatic equilibrium we finally postulate that sharp wide angle reflections from the moho can be considered indicative of a layered lower crust this would apply to the russian platform which maybe gained this structuring during the ordovician extensional regime

rare earth element concentrations and speciation in organic rich blackwaters of the great dismal swamp virginia usa concentrations of rare earth elements ree major inorganic solutes and dissolved organic carbon doc were measured in waters from the great dismal swamp in southeastern virginia including lake drummond ph 4 3 and its principal surface inflows and outflow concentrations of ree are high in the lake average nd 8 nmol kg and the acidic doc rich inflow and out flow waters i e nd 12 5 nmol kg in jericho washington ditch and 8 nmol kg in feeder ditch respectively the slightly acidic ph 6 6 4 inflow waters from west of the suffolk scarp that comprise the chief source of surface water flow into lake drummond exhibit lower ree concentrations nd 3 4 7 nmol kg great dismal swamp waters are all enriched in the middle rees compared to the light and heavy rees lree and hree when normalized to upper continental crustal ucc values rare earths are positively correlated to doc concentrations in great dismal swamp waters and inversely correlated with ph speciation calculations using a modified version of the well established humic ion binding model v predict that organic matter complexes are the predominant form of dissolved rees in great dismal swamp waters despite significant competition from aqueous fe and al for organic matter binding sites adsorptive cathodic stripping voltammetry acsv was employed using a previously developed competitive ligand equilibration approach that involved adding the o cresolphthalexon ocp ligand to directly investigate ree complexation with natural organic ligands in great dismal swamp waters although preliminary the results of the acs voltammetric titrations are consistent with dominance of organic matter complexes of rees in great dismal swamp waters the results of the speciation modeling and the voltammetric titrations all point towards control of dissolved rees in great dismal swamp waters by complexation of these heavy metals with natural organic matter

the geochemistry of rare earth elements in groundwater from the carnmenellis area southwest england shallow groundwater samples from the carnmenellis area of southwest england collected from wells boreholes springs adits and stream baseflow represent recently recharged waters of low salinity their major ion concentrations closely reflect the lithology of their host rocks which comprise the carnmenellis granite and devonian metasediments and metabasite of greenschist grade groundwaters from the granite are predominantly na cl or na ca cl type whilst those from the metasediment are na ca mg cl hco3 waters with a larger range of compositions the major ion compositions are predominantly a function of water rock interaction processes and the larger range of metasediment water compositions probably reflects the greater lithological variation the ph of groundwater samples circulating through granite is typically lower than that of groundwater in the metasediments the range being 4 3 to 7 2 median 5 7 and 4 7 to 8 0 median 6 6 respectively rare earth element ree concentrations of 0 45 m filtered groundwater samples have been determined by inductively coupled plasma mass spectrometry icp ms a large range of concentrations exists and many are below detection limits but levels reach up to 229 g 1 1 6 m total rees the rees are strongly controlled by ph with higher levels in groundwaters of ph 6 chondrite normalised profiles are light rare earth element lree enriched compared to heavy rare earths hrees with a common slight negative eu anomaly both features reflecting the compositions of their host rocks ree profiles therefore appear to be controlled by water rock interactions involving predominantly ree enriched minerals in the granite the rees are probably derived mainly from the accessory minerals monazite and apatite as well as the high ree framework minerals biotite and muscovite the source of rees in groundwater from the metasediments is more uncertain but probably includes clay minerals chlorite and carbonate ree compositions normalised to shale have flatter profiles although many are slightly convex with higher normalised sm eu and gd values a few metasediment derived waters with high total ree concentrations have lree enriched shale normalised patterns it is suggested that the bulk of the rees in these few samples is colloidal rather than totally dissolved groundwaters from the metasediments have a notable depletion in ce which is distinct from waters in the granite this depletion is problematic in that it is difficult to see how redox processes could be the dominant control since groundwaters from the metasediments are unlikely to be more oxidising than those from the granite likewise variations in ph fail to totally explain the distinctions in ce concentration and la ce ratios between the two water types it is therefore suggested that the ce contents are largely source related rather than process related the observed ree compositions of granite and metasedimentderived groundwaters from the carnmenellis area are so distinctive that the rees in general and ce in particular might be useful as future tracers in studies of water rock interaction and groundwater provenance

binding and transport of rare earth elements by organic and iron rich nanocolloids in alaskan rivers as revealed by field flow fractionation and icp ms abstract water samples were collected from six small rivers in the yukon river basin in central alaska to examine the role of nanocolloids 0 5 40 nm in the dynamics and transport of rare earth elements rees in northern high latitude watersheds influenced by permafrost total dissolved 40 nm colloids in a river sampled at higher altitude the

geochemical controls on arsenic and rare earth elements approximately along a groundwater flow path in the shallow aquifer of the hetao basin inner mongolia article i nfo groundwaters and sediments were sampled approximately along a groundwater flow path in the shallow aquifer of the hetao basin inner mongolia along a flow path with a length of about 9 km groundwater evolves from ca hco3 so4 through mg ca hco3 cl to na cl hco3 from the recharge zone to the discharge

isotopic ratio and concentration of sulfur in the undersaturated alkaline magmas of vulture volcano italy both the 34 value and the total s content of products from vulture volcano italy are mainly controlled by the separation of s gases predominantly so2 from high fo2magmas containing s predominantly as so2 4 the addition of evaporites to such magmas appears to be a relatively uncommon and limited phenomenon the total s content of the most primitive product of vulture volcano 5600 mg kg is very high the high 34s value of 4 indicates an origin through the partial melting of a mantle containing high s enriched in 34s of unknown origin

global risk from extreme geophysical events threat identification and assessment in an increasingly interconnected world any single geophysical hazard is capable of having consequences far beyond the range of immediate physical effects most recently this was demonstrated by the 2004 asian tsunami which took the lives of citizens from 57 different nations and by hurricane katrina in august 2005 which raised fuel prices worldwide and contributed to a record uk trade deficit in the month following the devastation of new orleans on an altogether wider scale global geophysical events gges are natural phenomena capable of having wholesale deleterious consequences for the world s environment economy and society these may arise i due to a global physical effect such as an episode of severe planetary cooling in response to a volcanic super eruption or large comet or asteroid impact or ii as a result of subsidiary ramifications for the global economy and social fabric of a cataclysmic regional event such as an atlantic or pacific wide mega tsunami or a more spatially confined event at a strategically sensitive location for example the awaited major tokyo earthquake while very infrequent the wide ranging and potentially ruinous consequences of a gge for the well being of the international community make it essential that they are seriously considered within any comprehensive assessment of natural threats

behavior of rare earth elements in groundwater during flow and mixing in fractured rock aquifers an example from the dandenong ranges southeast australia a previously defined flow system is used to investigate ree behavior at different stages along groundwater flow paths in fractured basalt and sedimentary aquifers results from this study indicate that ree concentrations and patterns predominantly reflect different types and rates of reactions taking place to those controlling major ion chemistry in areas where recharge is through sediments ree concentrations are high nd 8 62 31 61 ng l and localised processes such as source heterogeneity control ree patterns and concentrations increased concentrations of rees in these groundwaters where ph 6 1 is a result of early stage ree mobilisation in the flow system in contrast where groundwater recharges through basalt ree concentrations are low nd 2 40 4 75 ng l and ree concentrations are relatively constant along groundwater flow paths indicating steady state conditions groundwater from both the sediment and basalt aquifer systems flows into the local discharge area in contrast to tds contents and major ion ratios groundwater from the discharge area has ree concentrations nd 1 84 4 18 ng l and patterns that reflect a larger component of flow from the basalt aquifer lower ree concentrations of groundwater from the regional sedimentary aquifer may result from progressive ree sorption or co precipitation as indicated by an increase in y ho cl cn ratios and hree enrichment for groundwater with ph not vert similar 7 1 due to greater abundances of hree vs lree dicarbonato complexes

a probabilistic estimate of the most perceptible earthquake magnitudes in the nw himalaya and adjoining regions nw himalaya and its neighboring region 25 40 n and 65 85 e is one of the most seismically hazardous regions in the indian subcontinent a region that has historically experienced large to great damaging earthquakes in the present study the most perceptible earthquake magnitudes mp are estimated for intensity i vii horizontal peak ground acceleration a 300 cm s2 and horizontal peak ground velocity v 10 cm s in 28 seismogenic zones using the two earthquake recurrence models of kijko and sellevoll bulletin of the seismological society of america 82 1 120 134 1992 and gumbel s third asymptotic distribution of extremes giii both methods deal with maximum magnitudes the earthquake perceptibility is calculated by combining earthquake recurrence models with ground motion attenuation relations at a particular level of intensity acceleration and velocity the estimated results reveal that the values of mp for velocity v 10 cm s show higher estimates than corresponding values for intensity i vii and acceleration a 300 cm s2 it is also observed that differences in perceptible magnitudes calculated by the kijko sellevoll method and giii statistics show significantly high values up to 0 7 0 6 and 1 7 for intensity acceleration and velocity respectively revealing the importance of earthquake recurrence model selection the estimated most perceptible earthquake magnitudes mp in the present study vary from mw 5 1 to 7 7 in the entire zone of the study area results of perceptible magnitudes are also represented in the form of spatial maps in 28 seismogenic zones for the aforementioned threshold levels of intensity acceleration and velocity estimated from two recurrence models the spatial maps show that the quetta of pakistan the hindukush pamir himalaya the caucasus mountain belt and the himalayan frontal thrust belt kashmir kangra uttarkashi chamoli regions exhibit higher values of the most perceptible earthquake magnitudes mw 6 0 these spatially distributed values indicate good agreement with high seismic hazard zones in previously published hazard maps based on seismicity maximum expected earthquake magnitudes during specific time intervals and maximum expected acceleration these maps have useful implications in preparing earthquake selection criteria for the anti seismic design of non critical structures in the study region

modeling earthquake recurrence in the himalayan seismic belt using time dependent stochastic models implications for future seismic hazards interest in and pertinent studies related to the seismic hazard in the himalayan region have increased significantly since the instrumental era and each damaging earthquake encourages its reestimation in the work presented herein the non poissonian probabilities of exceedance of magnitudes in a specified time in the future were investigated for different elapsed times based on the recurrence time intervals of past earthquakes in the himalaya using the weibull log normal gamma and inverse gaussian stochastic models the whole himalayan arc is divided into four seismogenic source zones viz the northwestern himalayas zone 1 the central seismic gap region zone 2 the eastern nepal and sikkim zone 3 and the eastern himalayas zone 4 by considering approximately 380 years of seismological data the suitability of each stochastic model for each zone was estimated using the kolmogorov smirnov k s test to describe the different physical processes responsible for earthquake occurrence the results show that the gamma inverse gaussian log normal and inverse gaussian models were most suitable for zones 1 4 respectively for m 6 0 the cumulative probability of recurrence intervals reaches up to 90 in 30 years for zones 1 and 2 49 years for zone 3 and 41 years for zone 4 the estimated conditional probability reaches 90 in 30 years in zone 1 35 years in zone 2 and 50 years in zones 3 and 4 the most suitable models for m 7 0 were found to be the log normal for zones 1 2 and 3 and gamma for zone 4 the cumulative probability for m 7 0 reaches 90 in 85 years in zone 1 86 years in zone 2 93 years in zone 3 and 148 years in zone 4 the estimated conditional probabilities reach 90 in 80 years in zone 1 90 years in both zone 2 and 3 and 150 years in zone 4 it is strongly recommended that model suitability be evaluated in complex regions such as the himalaya before proceeding with seismic hazard assessments the heterogeneous and complex tectonics of the himalayas differentiated plate motions different stress release patterns spatially and temporally and locking unlocking of faults thrusts are some of the reasons responsible for the different probabilistic models describing the earthquake occurrence phenomena in these four zones

controls on the geochemistry of rare earth elements in sediments and groundwaters of the aquia aquifer maryland usa abstract groundwater samples were collected along two flow paths from the aquia aquifer in maryland usa to investigate the rare earth element ree geochemistry of the flow system as a function of evolving groundwater composition neodymium nd concentrations of aquia aquifer groundwater range from 56 6 to 71 4 pmol kg 1 along the eastern shore flow path i e eastern shore of the chesapeake bay and from 41 5 to 77 9 pmol kg 1 on the western shore flow paths and consequently fall within the range reported for other circumneutral to alkaline ph groundwaters shale normalized ree patterns of eastern and western shore aquia groundwaters are similar i e relatively flat and do not vary substantially along either flow path for example yb nd nasc for aquia aquifer groundwaters exhibit a limited range between 0 7 and 1 1 aquia aquifer sediments were analyzed for rees following a sequential extraction procedure neodymium concentrations for the bulk aquifer sediment range from 26 to 70 mol kg 1 3 7 to 10 1 ppm or a factor of 2 5 to 7 lower than the nd content of the upper continental crust the sequential extractions reveal that the majority of the rees in the aquifer sediments occur associated with the abundant carbonate shell fragments that are ubiquitous within the aquia aquifer sediments furthermore the sequential extraction data indicate that the light rees lree are more readily exchangeable i e outer sphere surface complexed on aquifer mineral surfaces than the heavy rees hree and the hrees and middle rees mree exhibit a greater association with fe mn oxides oxyhydroxides within the sediments analysis of the abundant glauconite pellets within aquia aquifer sediments indicates an overall enrichment in the hrees relative to the lrees for this mineral compared to shale our data suggest that the chief source of rees to aquia aquifer groundwater is dissolution of carbonate biominerals shell fragments that occurs in the recharge zone and before groundwaters become saturated with respect to calcite and aragonite additionally weakly sorbed rees outer sphere surface complexed contribute lrees and mrees to aquia aquifer groundwater as ph increases above 8 leading to the relatively flat shale normalized ree patterns that characterize aquia aquifer groundwaters once released to the solution ree form strong aqueous complexes with carbonate ions lnco 3 and ln co 3 2 with the dicarbonato complexes i e ln co 3 2 predominating the ree are subsequently transported with flowing groundwater in the aquia aquifer as the negatively charged dicarbonato complexes exhibit a low affinity to sorb to negatively charged mineral surfaces in the aquifer sediments

estimates of long term probabilities for future great earthquakes in the aleutians we compute probabilities for future great earthquakes in the aleutian arc probability distributions are fitted to recurrence periods of great aleutian evens m sub w or 7 8 since 1788 given a probability distribution and data of the last grat earthquake in each arc segment time dependent conditional probabilities are determined for future periods of interest we obtain for the next two decades high probabilities 99 to 30 for great earthquakes in the shumagin yakataga unalaska and kommandorski seismic gaps these probabilities are higher than for any other assessed region of the u s believed to be capable of great earthquakes low probabilities 17 to 9 are found for segments that ruptured most recently in 1965 1964 and 1957 recurrence periods for great earthquakes measure on average about 80 years but vary substantially whether recurrence periods for great aleutian earthquakes follow a normal log normal or any other probability distribution is not resolved because in most arc segments the known seismic record embraces at best one or two recurrences the resulting uncertainty affects the magnitude of estimated probabilities especially in seismic gaps that have not ruptured for a long time in some instances a normal distribution yields a three times higher probability than the correspondingmore log normal distribution less

contrasting fault fluids along high angle faults a case study from southern apennines italy abstract this work focuses on two fault controlled deposits the atella and rapolla travertines which are associated with high angle extensional faults of the bradano trough southern apennines italy the atella travertine is along a nw se striking deep seated extensional fault already described in literature which crosscuts both apulian carbonates and the overlying foredeep basin infill the rapolla travertine is on top of a ne sw striking shallow seated fault here described for the first time which is interpreted as a tear fault associated with a shallow thrust displacing only the foredeep basin infill the results of structural sedimentological mineralogical and c and o isotope analyses are here reported and discussed to assess the provenance of mineralizing fluids and to evaluate the control exerted by the aforementioned extensional faults on deep mantle derived and shallow meteoric fluids sedimentological analysis is consistent with five lithofacies in the studied travertines which likely formed in a typical lacustrine depositional environment mineralogical analysis show that travertines mainly consist of calcite and minor quartz feldspar and clay minerals indicative of a terrigenous supply during travertine precipitation the isotope signature of the two studied travertines shows different provenance for the mineralizing fluids at the atella site the 13cpdb values range between 5 2 and 5 7 and the 18opdb values between 9 0 and 7 3 which are consistent with a mantle derived co2 component in the fluid in contrast at the rapolla site the 13cpdb values vary from 2 7 to 1 5 and the 18opdb values from 6 8 to 5 4 suggesting a mixed co2 source with both biogenic derived and mantle derived fluids the results of structural analyses conducted along the footwall damage zone of the fault exposed at the rapolla site show that the whole damage zone in which fractures and joints likely channeled the mixed fluids acted as a distributed conduit for both fault parallel and cross fault fluid migration

geochemistry and secular trends in the middle late permian karst bauxite deposits northwestern iran abstract this study focuses on the middle late permian bauxite deposits found within karstic depressions and sinkholes of carbonates of the ruteh and nessen formations northwestern iran data concerning five karst bauxite deposits each related to a different stratigraphic position within the bedrock were selected to address the chemical distribution and inter elemental relationships especially for critical elements factors that control bauxite formation and the parental affinity the analyzed samples mainly clayey bauxite and bauxitic clay are characterized by large compositional fluctuations involving both major and trace elements the major element composition is dominated by sio2 tio2 al2o3 and fe2o3 among the critical elements compositional fluctuations induce the occurrence of outliers for co nb ta lree and hree similar to other trace elements such as ba sr cr u and zr elemental mobility indicates that most of elements are generally depleted among the critical elements co is enriched only in several samples of the older deposits and ree are enriched in some samples of the younger deposits factor analysis suggests that due to the observed al ga covariance fairly acidic conditions were never attained during bauxitization and that detrital resistant minerals concentrated during a bauxitization stage promoting al ti accumulation furthermore the u co variance with low soluble elements nb ta and th suggests that u was mostly conservative during the formation of deposits cobalt co varies with cr and these elements accumulated during later bauxitization stages when the massive leaching of silica occurred the cia ciw and pia paleo weathering proxies indicate an upward weathering increase which suggests a trend toward more extreme weathering conditions in a wetter and warmer climate according to the permian global warming this is consistent with an upward increasing ba sr ratio and the inspection of the a cn k plot where the younger deposits fall close to the a k edge involving a clayey precursor requires a rainfall increase interestingly the upward trend toward a warmer and wetter climate was also coupled with paleo redox conditions promoting cerium oxidation as depicted by the ce ce values finally the eu anomaly and the sm nd ratio indicate that the studied bauxite deposits were mainly derived from a mafic protolith that formed in the middle late permian as a consequence of the volcanism that affected the entire iranian platform a cluster of karst bauxites however has eu eu values lower than the average standard deviation range of the mafic rocks suggesting a possible contribution of a more differentiated and less mafic protolith similarly the u th ratio at large supports the hypothesis of a mafic protolith for the middle late permian bauxite deposits although some samples show the u th values well above the average standard deviation range of the mafic rocks likely indicating that processes promoting the accumulation of resistant minerals with high u th ratios cannot be excluded this means that in this case the u th ratio does not necessarily reflect the protolith of karst bauxites and that more in general this proxy needs to be carefully interpreted when used to assess the parental affinity of residual rocks

rapid development of negative ce anomalies in surface waters and contrasting ree patterns in groundwaters associated with zn pb massive sulphide deposits ground and surface waters collected from two undisturbed zn pb massive sulphide deposits the halfmile lake and restigouche deposits and active mines in the bathurst mining camp bmc nb canada were analysed for the rare earth elements ree ree contents are highly variable in waters of the bmc with higher contents typical of waters with higher fe and lower ph there are significant differences between ground and surface waters and between groundwaters from different deposits the ree contents of surface waters are broadly similar within and between deposit areas although there are spatial variations reflecting differences in ph and redox conditions surface waters are characterised by strong negative ce anomalies ce ce nasc as low as 0 08 produced by oxidation of ce3 to ce4 and preferential removal of ce4 from solution upon leaving the shallow groundwater environment groundwaters and seeps typically lack significant ce anomalies reflecting generally more reducing conditions in the subsurface environment and indicating that ce oxidation is a rapid process in the surface waters deeper groundwaters at the halfmile lake deposit are characterised by ree patterns that are similar to the host lithologies whereas most groundwaters at the restigouche deposit have lree depleted patterns compared to nasc halfmile lake deposit groundwaters have generally lower ph values whereas restigouche deposit groundwaters show greater heavy ree complexation by carbonate ions shallow waters at the halfmile lake and stratmat main zone deposits have unusual patterns which reflect either the adsorption of light ree onto colloids and fracture zone minerals and or precipitation of ree phosphate minerals middle ree enrichment is typical for ground and surface waters and is highest for neutral ph waters the labile portion of stream sediments are generally more middle ree enriched than total sediment and surface waters indicating that the ree are removed from solution by adsorption to fe and mn oxyhydroxides in the order middle ree light ree heavy ree

petrogenesis of monte vulture volcano italy inferences from mineral chemistry major and trace element data the paper presents major and trace element data and mineral compositions for a series of foiditic tephritic to phonolitic rocks coming from monte vulture southern italy and investigates their origin evolution and relationship with the other centres of the roman province

mantle co2 degassing at mt vulture volcano italy relationship between co2 outgassing of volcanoes and the time of their last eruption abstract mantle volatiles are mainly lost from the earth to the atmosphere through subaerial and submarine volcanism recent studies have shown that degassing of mantle volatiles also occurs from inactive volcanic areas and in tectonically active areas a new challenge in earth science is to quantify the mantle derived flux of volatiles e g co2 which is important for understanding such diverse issues as the evolution of the atmosphere the relationships between magma degassing and volcanic activity gas pressure and seismogenic processes and the hazards posed by volcanic lakes here we present a detailed study of mantle derived co2 budget from mt vulture volcano in the apennines italy whose latest eruption occurred 141 11 kyr ago the relationship between 13cco2 and total dissolved carbon at mt vulture volcano indicates that the emitted co2 is a mixture of a biogenic end member with an average 13cco2 of about 17 and a mantle derived co2 end member with 13cco2 values from 3 to 2 these values of mantle derived 13cco2 are in the range of those for gas emitted from active volcanoes in the mediterranean we calculated the contribution of individual components co2 in groundwater in lakes and from main pools to the total co2 budget in the area we used new measurements of water flow combined with literature data to calculate the co2 flux associated with groundwater and measured the gas flux from the main pools on the volcanic edifice finally we calculated the co2 flow in the lakes based on the gradient concentration and eddy diffusivity the total mantle derived co2 budget in the area is 4 85 10 8 mol yr 1 which is more than double previous estimates this is higher than those observed in younger volcanic systems elsewhere thereby supporting the existence of actively degassing mantle melts below mt vulture volcano a structural map highlights the tectonic control on co2 flow across the mt vulture volcanic edifice indeed the tectonic discontinuities that controlled the magma upwelling during the most recent volcanic activity are still the main active degassing structures the new estimate of co2 budget in the mt vulture area together with literature data on co2 budget from historically active and inactive italian volcanoes suggests a power law functional relationship between the age of the most recent volcanic eruption and both total discharged co2 r 2 0 73 and volcano size normalized co2 flux r 2 0 66 this relation is also valid by using data from worldwide volcanoes highlighting that deep degassing can occur over very long time too in turn the highlighted relation provides also an important tool to better evaluate the state of activity of a volcano whose last activity occurred far in time finally our study highlights that in the southern apennines an active degassing of mantle derived volatiles i e he co2 occurs indiscriminately from west to east this is in contrast to the central northern apennine which is characterized by a crustal radiogenic volatile contribution which increases eastward coupled to a decrease in deep co2 flux this difference between the two regions is probably due to lithospheric tears which control the upwelling of mantle melts their degassing and the transport of volatiles through the crust

radiogenic helium degassing and rock fracturing a case study of the southern apennines active tectonic region gas from mud volcanoes dry mofettes springs and wells were sampled in a region of active tectonics and high seismicity in the southern apennines italy where there is a long history of disastrous earthquakes with the latest ms 6 9 occurring in 1980 the fluids consist of a mixture of mantle derived and crust derived volatiles with a low atmosphere derived contribution as identified by the he isotope signature and he ne ratio measurements one year of monthly monitoring of the he concentrations and he isotopes revealed no seasonal modifications or variations induced by low seismicity there are extraordinary high outputs of 4he produced in the crust in the area up to 2 5 1028 atoms yr 1 these outputs cannot be solely due to the whole rock production rate and a long lasting diffusion degassing through the crust of the produced 4he this study explored the relation between the volume of fractured rock and the related release of he the results support that crustal degassing can be controlled by tectonic events resulting in earthquakes the high seismicity in this sector of the apennines provides the conditions necessary for a massive release of he that has accumulated in the rock over a long time period we identified that the assessed high crustal 4he output can be attributed to an intense fracturing of a calculable volume of rock which gives new constraints on the volume of rock involved in high magnitude earthquakes in the region

active degassing of mantle derived fluid a geochemical study along the vulture line southern apennines italy abstract we report the results of a geochemical study of gas emissions along a ne sw transect in southern italy in order to test the hypothesis that the region around monte vulture is affected by degassing of mantle derived fluids through a lithospheric discontinuity we also investigated lavas from the monte vulture volcano displaying 3 he 4 he up to 6 0 ra and sr isotopes that are consistent with an origin in mantle that has had minimal pollution from subducted adriatic slab similar 3 he 4 he in fluids from around mt vulture indicate that the deep volcanic system is still degassing mantle derived he occurs in fluids along the length of the vulture line reinforcing the hypothesis that it is a deep tectonic discontinuity along which mantle fluids and or melts advect to the surface the co 2 3 he ratios are highly variable 2 7 10 8 2 15 10 11 in response to processes such as gas dissolution into aquifers addition of crustal gases and degassing fractionation

water rock interaction in an acidic mine discharge as indicated by rare earth element patterns abstract the rare earth element ree composition of an acidic spring discharging at ph 2 7 was studied in relation to the ree composition of selected extracts of the coal bearing strata hydrologically above the discharge the low ph of the discharge and the access to the strata through which it flows provides an excellent opportunity to study the use of rees as tracers of water rock interaction extraction techniques were used to mimic the process of acidic groundwater generation in coal bearing strata samples were treated to remove exchangeable ions and then treated sequentially with solutions buffered at ph 5 5 3 6 and 1 6 in order to mimic the natural buffering systems of groundwaters finally samples were oxidised with hydrogen peroxide in an attempt to remove the pyrite the results show that the composition of the spring is controlled by pyrite oxidation and buffering by fe oxy hydroxides the latter with compositions inherited from carbonates from within the sequence the similarity of ree patterns of the carbonate and the silicate extracts tends to obscure information concerning the relative roles of carbonate or silicate phases the source strata of the spring has evolved over time and shows that different coal seams have a unique contribution this distinct contribution appears more related to the mixture of sedimentary components i e carbonates silicates etc in the coal seam and the combination of shale and sandstone layers surrounding coal seams than the composition of the components themselves the similarity between ree compositions of the sequential extracts suggests that relationships discovered for this spring will be applicable elsewhere in the basin however this very property will hamper the use of such lithophilic elements in cases where characterisation of the source area is not possible

rare earth element geochemistry of groundwaters from a thick till and clay rich aquitard sequence saskatchewan canada rare earth elements ree were determined in groundwater samples collected from a thick till and clay rich aquitard sequence located in southern saskatchewan canada the groundwaters are na mg so4 type waters that range from highly concentrated brines e g i up to 2 moles kg near the ground surface to relatively dilute waters i 0 04 moles kg at depth the majority of these groundwaters have ph values between 7 and 8 although the deepest samples are more alkaline 9 ph 9 6 groundwater ree concentrations are relatively constant in the overlying till but increase by up to a factor of 50 in the underlying clay bedrock shallow groundwaters have heavy ree hree enriched shale normalized patterns whereas the ree patterns of the deep groundwaters are relatively flat solution complexation modelling indicates that variations in ree patterns reflect differences in solution complexation across the ree suite in the shallow groundwaters strongly adsorbed positively charged carbonate complexes lnco3 sulfate complexes lnso4 and free metal ion species ln3 dominate the speciation of light rees lree whereas hrees occur chiefly as more stable negatively charged dicarbonato complexes i e ln co3 2 for the deepest groundwaters however all of the rees are predicted to occur in solution as dicarbonato complexes the large hree enrichments of the shallow groundwaters reflect the greater affinity of the positively charged lree solution species to adsorb to clay minerals or coatings on clay minerals in the aquitard sequence compared to the more stable negatively charged hree dicarbonato complexes on the other hand the flat ree patterns of the deep groundwaters reflect the dominance of the negatively charged dicarbonato complex for all rees the solution complexation model along with the strong positive correlation between rees and co32 f 0 79 r 0 95 and to a lesser extent ph 0 57 r 0 72 indicates that carbonate ion concentrations and thus ph exert important controls on aqueous ree concentrations in these groundwaters

rare earth element fractionation and concentration variations along a groundwater flow path within a shallow basin fill aquifer southern nevada usa abstract rare earth element ree concentrations were measured in 5 well water samples and 3 springs located along a groundwater flow path in a shallow tuffaceous alluvial aquifer from southern nevada usa the ree concentrations in these groundwaters decrease in the direction of groundwater flow a previous investigation demonstrated that ree solid liquid phase partitioning coefficients i e kd s for groundwaters from tuffaceous alluvial aquifers in southern nevada are relatively high mean kd 102 6 our groundwater ree data in conjunction with these kd s support strong sorption of aqueous rees to aquifer surface sites as the primary removal mechanism of rees from these groundwaters in addition relatively high aqueous ree concentrations occur at distinct locations along the groundwater flow path the elevated ree concentrations are explained by addition of deeper groundwaters influx of geothermal waters from a hot spring system differences in solution complexation and or mixtures of regional and local recharge sources solution complexation modelling of rees in the groundwaters indicate that carbonate complexes account for more than 99 of each rees in solution moreover groundwater yb nd ratios a measure of ree fractionation are associated with alkalinity hco3 co32 r 0 71 the data and speciation model results indicate that ree fractionation i e the observed heavy ree hree enrichments compared to rock sources is controlled by formation of progressively stronger carbonate complexes in solution with increasing atomic number which inhibits hree sorption compared to light rees lree and a greater affinity for the lrees to sorb to surface sites in the local tuffaceous alluvial aquifers compared to the hrees

recurrence time and frequency slip statistics of slip events on the creeping section of the san andreas fault in central california summary an important question in seismic hazard assessments is the frequency size and recurrence interval statistics at a point on a fault does a point on a fault obey the same statistics as earthquakes in a region do this is a difficult question to answer because the number of repetitive earthquakes on a particular fault that have been observed is small in order to overcome this difficulty we consider slip events on the creeping section of the san andreas fault in central california sequences of up to 100 events are obtained from creepmeter records we compare the statistical distribution of recurrence times with the brownian passage time lognormal and weibull distributions and using goodness of fit tests find that the weibull is the preferred distribution we also consider the frequency amplitude distribution of slip events we find that the data clearly do not obey a gutenberg richter distribution instead there is a uniform distribution of event sizes for a large fraction of events

rare earth elements as reactive tracers of biogeochemical weathering in forested rhyolitic terrain article rareearthelements rees were evaluatedaspotentialtracers of biogeochemicalweathering atpedon hillslope and catchment scales in the jemez river basin critical zone observatory jrb czo valles caldera national pre serve nm usa we investigated time series of ree patterns in precipitation soil pore water groundwater and stream water and related these data to ree composition of soil rock and atmospheric dust ree signatures in stream waters are dynamic reflecting processes that occur along hydrologic flowpaths during transport to the stream including organic matter complexation primary and secondary mineral weathering water soil bedrock interaction and atmospheric deposition strong compositional similarities for the ree between soil waters and stream waters during the initial snowmelt are consistent with shallow subsurface flows to streams most bio

the hydrochemical identification of groundwater flowing to the bet she an harod multiaquifer system lower jordan valley by rare earth elements yttrium stable isotopes h o and tritium abstract the bet she an and harod valleys in israel are regional recipients and mixing zones for groundwater draining from a multiple aquifer system which includes carbonate and basalt aquifers and deep seated pressurized brines the aquifers drain through two types of outlets distinct and mixed the latter type is mainly conditioned by the occurrence of fault blocks related to the jordan rift system which act as connecting media between the aquifers and facilitate interaquifer flow conjoint application of rare earth element distribution and water isotopes enables detection of the local areas replenishment by rainfall infiltration and in connection with the position of wells or springs the identification of groundwater flow paths once stationary equilibria are established changes of rey composition between rey in groundwater and their surface adsorption are negligible in areas with little soil coverage and vegetation even recharge over young tertiary and diagenetic cretaceous limestones is distinguishable by their rey distribution patterns groundwater recharged over tertiary limestones show higher rey abundance and more significant ce anomalies than those derived from the cretaceous limestones weathering of alkali olivine basalts leads to rey patterns in groundwater depleted in the middle ree the improved knowledge of the hydrological systems is thought to be useful for regional hydrogeological modeling and for designing rational water management schemes

stable isotope ratios in meteoric recharge and groundwater at mt vulture volcano southern italy summary a rain gauge network consisting of five sites located at different altitudes ranging from 320 to 1285 m a s l was installed at mt vulture volcano southern italy rain water samples were collected monthly over a two year period and their isotopic composition 18o and d was analyzed during the same period circulating groundwater was sampled from 24 springs and wells distributed throughout the study area monthly isotopic composition values were used to determine the local meteoric water line lmwl its slope is slightly lower than the relationship defined by longinelli and selmo longinelli a selmo e 2003 isotopic composition of precipitation in italy a first overall map j hydrol 270 75 88 for southern italy the groundwater samples analyzed were distributed essentially along the lmwl the weighted local meteoric water line wlmwl defined through the mean values weighted by the rainfall amount however may define in a short range the meteoric end member in the local hydrological cycle more precisely since most of the groundwater sampling locations do not show seasonal variations in their stable isotope values the flow system appears to be relatively homogeneous the mean altitude of the recharge by rainfall infiltration was estimated on the basis of the local vertical isotopic gradient 18o a few springs which show anomalous isotopic values reveal more regional circulation systems associated with tectonic structures responsible for the ascent of deeper water

rare earth elements ree in deep groundwater from granite and fracture filling calcite in the tono area central japan prediction of ree fractionation in paleo to present day groundwater rare earth elements rees combined with yttrium yree in deep groundwater from granite and fracture filling calcite are being studied at the mizunami underground research laboratory miu tono area central japan the groundwater was sampled from cored boreholes drilled from the miu galleries at 200 300 400 and 500 m depths the fracture filling calcite was collected from the same boreholes and dissolved in 1 m nh4 acetate buffer solution ph 4 8 major chemical composition of groundwater changed with depth and the concentrations of some major elements na k ca2 mg2 cl br and b increased with depth while alkalinity so42 and f decreased isotopic compositions of 18o and d indicated that the groundwater originated from meteoric water yree patterns of groundwater also changed with depth with heavy ree hree enrichment in shallow groundwater 200 to 400 m and light ree lree enrichment in deep groundwater 500 m the predominant yree species are yreeco3 and yree co3 2 laco3 65 70 la co3 2 8 27 luco3 20 38 and lu co3 2 53 77 the lree enrichment in the shallow groundwater resulted in preferential scavenging of positively charged yreeco3 by negatively charged bedrock surfaces in slightly alkaline groundwater ph 7 4 8 6 because of the construction and operation of the underground facility the shallow groundwater has been influenced by infiltration of surface water undersaturated in calcite in contrast the deep groundwater was barely affected by the mixing of surface water indicating that the yree originated from yree fractionation by bedrock granite irrespective of depth a negative ce anomaly preserved in the groundwater is probably indicative of paleo oxic conditions during paleo recharge the negative ce anomaly in the groundwater was possibly fractionated from sedimentary calcite with positive ce anomalies during the paleo recharge the yree patterns of the fracture filling calcite were enriched in lree the isotopic variations of 18o and 13c in the fracture filling calcite indicated that it originated from a mixture of sea water and fresh water at a temperature 100 c the yree patterns of paleo groundwater from which the fracture calcite precipitated were calculated using yree abundances in the fracture calcite and distribution coefficient reported in previous laboratory experiments the paleo groundwater was found to be enriched in lree and hree depending on the aqueous yree species our results suggest that changes in the paleo to present day yree fractionation range roughly from that of present day shallow to deep groundwater

magma evolution at mount vulture southern italy the vulture complex is made up of foiditic tephritic phonolitic trachytic and phonolitic products new rock analyses have been performed in order to ascertain whether the various rock types derive from a unique parental magma and if so to define its nature the data presented support that the vulture suite originated from a foiditic melt which had differentiated at low pressures the main process determining the foidite tephrite phonolitic trachyte evolution seems to be the crystal fractionation of mainly clinopyroxenes and opaques with the contribution of plagioclases and hauyne too in the tephrite trachyte evolution additionary role must have been played by a mixing of melts at different evolution stages occurred in a shallow seated magma chamber

the distribution of rare earth elements in groundwaters assessing the role of source rock composition redox changes and colloidal particles rare earth element ree dissolved organic carbon doc and trace element al mn fe sr ba u and th concentrations were measured in fourteen well water samples 0 22 m and one spring located along two transects set up in a catchment from western europe kervidy coet dan catchment france previous hydrological and hydrochemical no3 so42 investigations demonstrated that three chemically and spatially distinct groundwater types are present in this catchment which is fully confirmed by the ree and doc results these include i a shallow organic rich groundwater 4 4 doc 34 6 mg l from the wetland areas close to the river network this first groundwater type characterized by the development of temporary reducing conditions records high and variable ree contents 2 ree 16 ppb and displays slight or no negative ce anomaly ce ce 0 8 1 05 ii a shallow organic poor doc 3 mg l no3 rich groundwater type 86 8 no3 155 mg l located in the weathered schists below the hillslope domains this second type corresponds to recently recharged oxidized water and displays also high and variable ree concentrations 2 ppb ree 15 ppb but distinguish from the former by the occurrence of very strong negative ce anomalies ce ce 0 05 0 10 finally iii a deep organic poor doc 1 mg l nitrate poor no3 close to 0 2 mg l detection limit groundwater this third type corresponds to reduced water flowing into the deep fresh schists and yields low to very low ree contents ree 0 15 ppb as well as slight negative ce anomaly ce ce 0 8 to 0 9 temporal ree concentration variations were assessed using samples regularly collected over a six month period results show that the spatially distributed ce anomaly and ree pattern signatures are preserved throughout the studied period by contrast ree concentrations are quite variable through time especially in the wetland waters where the ree concentrations are seen to vary in phase with both redox changes and doc fe u and th content variations three ree rich water samples one doc rich and two doc poor were also filtered through membranes of decreasing pore size 100 000 d 30 000 d 5 000 d the results show that between about 40 to 65 of the ree present in the shallow doc poor groundwater samples are controlled by the colloidal fraction which is likely to consist in these inorganic waters of a mixture of mineral phases in the wetland groundwaters the fraction of ree controlled by microparticles is higher than 65 which confirms the predominant role of organic colloids as major ree carriers in wetland waters using the above data set in conjunction with analyses of soil samples we show that the deep ce anomalies found in the upper non organic part of the aquifer are probably not source rock inherited features most likely these anomalies arise from the oxidative precipitation of ce the very low ree content displayed by waters flooding the deep fresh schists is interpreted as due to the combined effects of i ph variation ii secondary sulfate mineral precipitation and iii the trapping of colloids borne ree by the aquifer rock pores data from wetland groundwaters show that the ree fe u and th budgets of these waters are mainly controlled by seasonal changes in redox conditions and organic matter content however unlike organic poor waters it appears difficult to relate the ce behaviour in these organic rich waters solely to redox conditions it is likely that the complexation of ce by organic colloids in the organic rich waters may mask redox changes by inhibiting the development of negative ce anomalies

rare earth elements in waters from the albitite bearing granodiorites of central sardinia italy with the aim of contributing to the knowledge of the geochemical behaviour and mobility of the rare earth element ree in the natural water systems the ground and surface waters of the ottana orani area central sardinia italy were sampled the study area consists of albititic bodies included in hercynian granodiorites the waters have ph in the range of 6 0 8 6 total dissolved solid tds of between 0 1 and 0 6 g l and major cation composition dominated by ca and na whereas predominant anions are cl and or hco3 the ph and the major element composition of the waters are the factors affecting the concentration of ree in solution the concentrations of ree y in the samples filtered at 0 4 m vary between 140 and 1600 ng l with la of between 14 and 314 ng l and yb of between 6 and 12 ng l a negative ce anomaly especially marked at high ph is observed in the groundwaters the surface waters show lower ree concentrations which are independent of ph and negligible ce anomaly speciation calculations carried out with the eq3nr computer program showed that the complexes with the co32 ligand are the dominant ree species at ph in the range of 6 7 8 6 the ree3 ions dominate the speciation at ph 6 7 and only in the light ree lree the relative concentrations of ree in water roughly reflect those in the aquifer host rocks however when concentrations of ree in water are normalised relative to the parent rocks a preferential fractionation of heavy ree hree into the water phase can be observed suggesting the greater mobility and stability of hree in aqueous solution

the development of middle rare earth element enrichments in freshwaters weathering of phosphate minerals abstract many phosphatic minerals of biogenic authigenic and diagenetic origin are distinguished by rare earth element ree compositions which have a well developed middle rare earth element mree enrichment defined by a gradual increase in the shale normalized ratios of ree toward the middle of the ree series la to lu also the ree composition of dissolved matter in the waters of the amazon fly and sepik rivers as well as other river lake and ground waters have well developed mree enrichments the development of mree enrichments was studied through a series of leaching experiments using river bank sediments from the amazon fly sepik and mississippi rivers a well characterized phosphate mineral rich shale with a pronounced mree enrichment in its bulk composition was also leached in order to better assess the relationship between the weathering of phosphate minerals and the formation of mree enriched solutions the two leaching solutions per sediment consisted of filtered lake water at ph 5 and the same water adjusted to ph 2 leaching experiments with the four river sediments result in extensive fractionation whereby the ree compositions of the solutions develop mree enrichments from starting sediments that show no mree enrichments the ph 2 leachates have much higher concentrations of the ree and more fully developed mree enrichments than do the ph 5 leachates the mree enrichments at ph 2 usually form within an hour of starting the experiments the phosphatic shale results show that there is preferential release of large amounts of mree at ph 5 as well as at ph 2 demonstrating the weather ability of the phosphatic minerals at phs of natural freshwaters the sepik river ph 5 experiment also shows significant mree enrichment under near neutral conditions the development and retention of the mree enrichments in the leaching solutions is accompanied by an increase in dissolved phosphate concentrations although the magnitudes of the mree enrichment do not directly correlate with the percent of phosphate released the experimental data suggest that the preferential dissolution of phosphatic minerals during weathering can result in extensive ree fractionation between bulk river sediment and water leading to freshwaters with mree enrichments

rare earth elements distribution and geochemical behaviour in the volcanic groundwaters of mount vulture southern italy abstract the mount vulture basin which mainly consists of pyroclastic and subordinate lava flow layers is one of the most important aquifers for drinking water and irrigation supply in southern italy in this study we investigated the geochemical behaviour of the rare earth elements rees in the groundwater of this aquatic system assessing fractionation patterns and performing speciation calculations to elucidate the geochemical processes affecting the rees distribution the groundwater collected was separated into two subsets corresponding to recharge and discharge water overall the groundwater exhibited ree concentrations well below 1000 ng l and the average content measured in the discharge water is approximately three times higher than that of the recharge water in the recharge water the shale normalised patterns are characterised by a more negative average ce anomaly a more positive average eu anomaly and a larger average la yb paas the observed relationship between ce anomalies and dissolved oxygen do supports the idea that ce oxidative scavenging has a role in determining the size and shape of the ce anomaly further the less negative average size of the ce anomaly in the discharge zone also suggests ce desorption due to changes in redox conditions as for the eu anomalies the largest eu are associated with the recharge zone characterised by higher average eh and do values the volcanics in the mt vulture lithologies have post archean average shale paas normalised patterns showing positive eu anomalies due to feldspars occurrence this indicates that the eu of groundwater in the recharge zone is mostly produced by the dissolution of feldspars in the discharge zone most samples are in equilibrium with smectite and eu2 adsorption onto the clay phase surface or its inclusion in the mineral structure as exchangeable cations likely lead to the smaller average size of eu the possible occurrence of secondary minerals preferentially scavenging light rees may also explain the difference in the la yb paas index observed between the recharge and discharge zones speciation calculations indicate that dissolved rees consist mainly of carbonato complexes lnco3 whereas the percentage of dicarbonato complexes ln co3 2 increases in samples with circa neutral ph at acidic ph the ln3 species are numerous and in samples with large amounts of dissolved sulphate derived by feldspathoids dissolution from the discharge zone the percentage of lnso4 species is not negligible

geochemical behavior of rare earth elements during the evolution of co2 rich groundwater a study from the kangwon district south korea abstract a hydrochemical study of co 2 rich groundwaters in the kangwon district south korea was conducted to elucidate the behavior of rare earth elements ree as a result of mixing of co 2 rich waters the ree fractionation during the formation of carbonate precipitates was also investigated the co 2 rich waters can be classified into three chemical types na hco 3 ca na hco 3 and ca hco 3 with characteristic isotope compositions chemical and isotope data indicate that the na hco 3 waters were influenced by a deep co 2 supply at depth while other waters were formed by mixing between na hco 3 water and less saline shallow groundwater concentrations of total dissolved ree ree in co 2 rich waters varied according to the water types and were highest in the na hco 3 waters up to 3456 ng l their ree concentrations showed excellent correlations with parameters such as tds ph alkalinity 18 o and tritium indicating progressive mixing with shallow groundwater the distribution of dissolved ree concentration showed different patterns dependent upon water type the na hco 3 waters displayed an s shape pattern with strong heavy ree hree enrichment in contrast the ca na hco 3 water was characterized by a slight hree enrichment while the ca hco 3 water exhibited a relatively flat scattered low ree lree enrichment pattern the ree patterns of the precipitates formed from the original waters and of the residual waters after removal of the precipitates were similar to those of the original co 2 rich waters indicating that no ree fractionation occurred between precipitates and residual waters

how mineralogy and slope aspect affect ree release and fractionation during shale weathering in the susquehanna shale hills critical zone observatory abstract to understand the factors that control rare earth elements ree release and fractionation during shale weathering we investigate the ree contents in solid bedrock regolith stream sediments and natural waters stream and pore waters from a first order catchment developed entirely on gray shales in central pennsylvania usa up to 65 of the ree relative to parent bedrock is depleted from the weathering profiles in the acidic and organic rich soils due to chemical leaching in addition newly formed fine particles were also lost along with the down slope movement of soil waters weathering profiles on the south facing slope show less depletion of ree than those on the north facing slope 33 vs 45 on average we hypothesize that the different degrees of ree depletion on the two transects reflect a history of different chemical weathering rates and possible different surface erosion rates controlled by contrasting slope aspect induced microclimate conditions in addition weathering profiles natural waters and sequential extractions all show a preferential removal of middle ree up to 22 more relative to light ree and heavy ree during shale weathering due to preferential release of mree from rhabdophane furthermore the long term phosphate mineral dissolution rates e g rhabdophane were estimated at 10 15 to 10 14 mol m 2 s 1 under field conditions based on ree depletion profiles strong positive ce anomalies average ce ce n value 1 79 observed in the regolith stream sediments and regolith extractions point to the fractionation and preferential precipitation of ce as compared to other ree due to the generally oxidizing conditions during release transport and redistribution of ree in the surface and subsurface environments positive eu anomalies average eu eu n value 1 30 observed in the natural waters of the catchment are attributed to weathering of plagioclases in the shale bedrock this study highlights the use of ree as natural tracers for low temperature geochemical processes