estimating groundwater exchange with lakes 1 the stable isotope mass balance method groundwater inflow and outflow contributions to the hydrologic budget of lakes can be determined using a stable isotope 18o 16o mass balance method the stable isotope method provides a way of integrating the spatial and temporal complexities of the flow field around a lake thereby offering an appealing alternative to the traditional time and labor intensive methods using seepage meters and an extensive piezometer network in this paper the method is applied to a lake in northern wisconsin demonstrating that it can be successfully applied to lakes in the upper midwest where thousands of similar lakes exist inflow and outflow rates calculated for the wisconsin lake using the isotope mass balance method are 29 and 54 cm yr respectively which compare well to estimates derived independently using a three dimensional groundwater flow and solute transport model of 20 and 50 cm yr such a favorable comparison lends confidence to the use of the stable isotope method to estimate groundwater exchange with lakes in addition utilization of stable isotopes in studies of groundwater lake systems lends insight into mixing processes occurring in the unsaturated zone and in the aquifer surrounding the lake and verifies assumed flow paths based on head measurements in piezometers

the tolbachik volcanic massif a review of the petrology volcanology and eruption history prior to the 2012 2013 eruption abstract the primary goal of this paper is to summarize all of the published data on the tolbachik volcanic massif in order to provide a clear framework for the geochronologic petrologic geochemical and to a lesser extent the geophysical and tectonic characteristics of the tolbachik system established prior to the 2012 2013 eruption the tolbachik massif forms the southwestern part of the voluminous klyuchevskoy volcanic group in kamchatka the massif includes two large stratovolcanoes ostry sharp tolbachik and plosky flat tolbachik and a 70 km long zone of the basaltic monogenetic cones that form an arcuate rift like structure running across the plosky tolbachik summit the tolbachik massif gained international attention after the 1975 1976 great tolbachik fissure eruption gtfe which was one of the largest eruptions of the 20th century and one of the six largest basaltic fissure eruptions in historical time by the end of the gtfe 2 2 km 3 of volcanic products of variable basaltic compositions with morb like isotopic characteristics covered an area of 1000 km 2 during the following three decades more than 700 papers on various aspects of this eruption have been published both in national and international journals although the recent 2012 2013 eruption which is the main topic of this volume was not as long as the gtfe in duration or as large in area and volume of the erupted deposits it brought to the surface a unique volcanic material never found before in order to understand the data from new eruptions and make significant progress towards a better understanding of the tolbachik magmatic system it is important to be able to put the new results into the historic context of previous research

oxygen and hydrogen isotopes in the hydrologic cycle changes of the isotopic composition of water within the water cycle provide a recognizable signature relating such water to the different phases of the cycle the isotope fractionations that accompany the evaporation from the ocean and other surface waters and the reverse process of rain formation account for the most notable changes as a result meteoric waters are depleted in the heavy isotopic species of h and o relative to ocean waters whereas waters in evaporative systems such as lakes plants and soilwaters are relatively enriched during the passage through the aquifers the isotope composition of water is essentially a conservative property at ambient temperatures but at elevated temperatures interaction with the rock matrix may perturb the isotope composition these changes of the isotope composition in atmospheric waters surface water soil and groundwaters as well as in the biosphere are applied in the characterization of hydrological system as well as indicators of paleo climatological conditions in proxy materials in climatic archives such as ice lake sediments or organic materials

remote sensing and petrological observations on the 2012 2013 fissure eruption at tolbachik volcano kamchatka implications for reconstruction of the eruption chronology abstract we present a reconstruction of the chronological sequence of events that took place during the first days of the 2012 2013 tolbachik fissure eruption using petrological data and remote sensing methods we were forced to use this approach because bad weather conditions did not allow direct observations during the first two days of the eruption we interpreted infrared images from the scanning radiometer viirs suomi npp and correlated the output with the results of the geochemical study including comparison of the ash deposited at the period from 27 to 29 november with the samples of lava and bombs erupted from the menyailov and naboko vents we argue that the compositional change observed in the eruption products the decrease of sio 2 concentration and k 2 o mgo ratio increase of mgo concentration and mg started approximately 24 h after the eruption began at this time the center of activity moved to the southern part of the fissure where the naboko group of vents was formed therefore this timeframe also characterizes the timing of the naboko vent opening the naboko group of vents remained active until the end of eruption in september 2013

isotope evidence for quantifying river evaporation and recharge processes in the lower reaches of the yellow river evaporation and recharge are important hydrological processes in the water cycle however accurately quantifying these two processes of river remains to be difficult due to their spatial heterogeneity and the limitations of traditional methods in this study a more reliable method of stable isotopes of 18o and 2h based on the rayleigh distillation equation and mass conservation was used to estimate the evaporation and recharge of the rivers in the lower reaches of the yellow river north china plain comprehensive sampling campaigns including 30 surface water samples from 10 rivers 33 groundwater samples from domestic and observation wells and two yellow river water samples were conducted the results showed that the evaporation proportion of the rivers based on 18o and 2h both averaged 14 4 the evaporation proportions in each river did not completely follow a linear increasing trend along the flow path this phenomenon could be mainly explained by the different proportions of recharge from groundwater and yellow river water with closer to the yellow river evaporation of the rivers decreased while the recharge by the yellow river increased regression equations based on 18o 2h and their average revealed that the evaporation proportion respectively increased by 1 02 0 79 and 0 90 with the increase in the distance to the yellow river per 10 km on the contrary the recharge proportion decreased by 7 68 5 51 and 6 59 respectively in addition using 18o rather than 2h was more reliable in studying the spatial influence of the yellow river on evaporation and recharge sensitivity analysis showed that the evaporation model was most sensitive to isotopic composition rather than to air temperature or relative humidity the results of this study provide insights into the determination of river hydrological processes and the management of water resources

reprint of seismic monitoring of the plosky tolbachik eruption in 2012 2013 kamchatka peninsula russia abstract the active basaltic volcano plosky tolbachik pl tolbachik is located in the southern part of the klyuchevskoy volcano group on the kamchatka peninsula the previous 1975 1976 great tolbachik fissure eruption 1975 1976 gtfe occurred in the southern sector of pl tolbachik it was preceded by powerful earthquakes with local magnitudes between 2 5 and 4 9 and it was successfully predicted with a short term forecast the kamchatka branch of geophysical survey kbgs of the russian academy of science ras began to publish the results of daily seismic monitoring of active kamchatka volcanoes on the internet in 2000 unlike the 1975 1976 gtfe precursor 1 seismicity before the 2012 2013 tolbachik fissure eruption 2012 2013 tfe was relatively weak and earthquake magnitudes did not exceed 2 5 2 precursory earthquake hypocenters at 0 5 km depth were concentrated mainly under the southeastern part of the volcano 3 the frequency of events gradually increased in september 2012 and rose sharply on the eve of the eruption 4 according to seismic data the explosive effusive 2012 2013 tfe began at 05 h 15 min utc on november 27 2012 the outbreak occurred between the summit of the pl tolbachik and the northern breakthrough of the 1975 1976 gtfe 5 because of bad weather early interpretations of the onset time and the character of the eruption were made using seismological data only and were confirmed later by other monitoring methods the eruption finished in early september 2013 this article presents the data obtained through real time seismic monitoring and the results of retrospective analysis with additional comments on the future monitoring of volcanic activity

precipitation origin and evaporation of lakes in semi arid patagonia argentina inferred from stable isotopes δ18o δ2h stable isotope approaches are often used for estimating water balances of lakes such studies require regional background information about hydrogen and oxygen isotope variability of lakes and their potential inflows here a stable isotope database 2h and 18o is presented for estimating evaporation to inflow ratios e i of lakes in semi arid southern patagonia water samples of 23 lakes and ponds located in the patagonian steppe at about 52 s were sampled during three subsequent austral summers two deep crater lakes laguna azul and laguna potrok aike were studied in more detail during a two years monitoring furthermore precipitation groundwater and atmospheric water vapor were sampled for isotope analyses presented data imply that the isotopic composition of rainfall in southeastern patagonia is predominantly determined by precipitation amount and moisture source area for the investigated area the first meteoric water and evaporation lines in 2h vs 18o space are presented the database was further used to estimate the water balances of the two crater lakes laguna azul and laguna potrok aike which are in the focus of recent paleoclimatic investigations according to that approach about 50 and 60 respectively of the water entering laguna azul and laguna potrok aike via surface and subsurface inflow evaporates these results testify a considerable flow of lake waters into the groundwater

snowmelt contribution to the sustainability of the irrigated mendoza s oasis argentina an isotope study mendoza is the province that has the largest irrigated area in argentina where water resources depend mainly on snowmelt and glacier melting in the closed andes mountain in this region the blanco river basin is one of the most important covering about 300 km2 flowing from the highest peaks to potrerillos dam 1300 masl the objective of this work was to make a preliminary characterization of stable isotopes in surface and groundwater ice and snowmelt to contribute to a better understanding of the hydrologic cycle in the region using a los gatos dlt 100 analyzer hydrochemical analyses were performed on 157 samples the isotopic composition of rain water is more enriched than streamwater clearly indicating that the stream recharge sources are at higher altitude the discharge regime of the streams indicates that snowmelt is the main water origin and considering the theoretical evolution of isotopes in meltwater the composition of streams corresponds to the first meltwater without fractionation then it is more depleted than the original snow the ice isotopic composition is more enriched than streamwater indicating that snowmelt is the main recharge source the hydrochemical results indicate the importance of geology in determining streamwater composition which is integrated with isotopic data to achieve a better comprehension of the hydrological system

constraints on unrest in the tolbachik volcanic zone in kamchatka prior the 2012 13 flank fissure eruption of plosky tolbachik volcano from local seismicity and gps data abstract a new fissure eruption began on 27 november 2012 on the southern slope of plosky tolbachik volcano which is located in central kamchatka russia and is part of the klyuchevskoy volcano group we analyzed the displacement of the earth surface and the seismicity during several months before the eruption onset according to seismic and gps data the eruption was preceded by about 4 5 months july november 2012 of synchronous crustal deformation and seismicity the seismic anomaly comprises low energy level seismicity mainly m 1 2 2 3 under plosky tolbachik volcano at a depth of less than 5 km in the 2 3 weeks immediately preceding the eruption the rate of seismicity and the amount of radiated seismic energy exceeded the long term average values 2000 2011 by more than 40 times the deformation anomaly was recorded by displacement of the gps points at distances from 20 to 60 km to the north of tolbachik the principal axis of the compressive strain was approximately directed towards the tolbachik eruption site the permanent gps network detected radial compression and tangential stretching the compressive strain reached about 10 7 prior to eruption onset the comparable duration of seismic and deformation anomalies 4 5 months before the eruption is consistent with a common origin connected to magma rising from depth and is interpreted as indicating that they were medium term precursors to the eruption data recorded during this unrest episode of the tolbachik volcanic zone will contribute to understanding of the reawakening of volcanic activity in this region and others worldwide with similar characteristics

calculation of lava effusion rates from landsat tm data we present a thermal model to calculate the total thermal flux for lava flowing in tubes on the surface or under shallow water once defined we use the total thermal flux to estimate effusion rates for active flows at kilauea hawaii on two dates input parameters were derived from landsat thematic mapper tm field and laboratory measurements using these parameters we obtain effusion rates of 1 76 0 57 and 0 78 0 27 m3 s 1 on 23 july and 11 october 1991 respectively these rates are corroborated by field measurements of 1 36 0 14 and 0 89 0 09 m3 s 1 for the same dates kauahikaua et al 1996 using weather satellite avhrr data of lower spatial resolution we obtain similar effusion rates for an additional 26 dates between the two tm derived measurements we assume that although total effusion rates at the source declined over the period the shut down of the ocean entry meant that effusion rates for the surface flows alone remained stable such synergetic use of remotely sensed data provides measurements that can a contribute to monitoring flow field evolution and b provide reliable numerical data for input into rheological and thermal models we look forward to being able to produce estimates for effusion rates using data from high spatial resolution sensors in the earth observing system eos era such as landsat 7 the hyperspectral imager the advanced spaceborne thermal emission spectrometer and the advanced land imager

stable oxygen and hydrogen isotopes as indicators of lake water recharge and evaporation in the lakes of the yinchuan plain the yinchuan plain has more than 2000 years of history of irrigation by diverting water from the yellow river currently the amount of water diverted from the yellow river is about 21 7 times the water formed on the plain as a result of precipitation and inflow of groundwater under the intensive influence of irrigation the plain changed from a desert into a rich and populous area earning its name as south china beyond the great wall with lakes scattered across the yinchuan plain just as stars in the sky in this research 17 representative lakes were sampled to analyze and study 2h and 18o content the results showed that lakes on the plain have undergone obvious non equilibrium evaporation recharges of the lakes can be divided into three types recharge from the yellow river from groundwater and from both of these the craig gordon non equilibrium evaporation model for isotope fractionation was used to estimate the evaporation proportion of each lake the results showed that evaporation from lakes on yinchuan plain is generally extensive under the dry climatic conditions most lakes have an evaporation proportion of over 25 with the largest originating from shahu lake and gaomiaohu lake in the northern part of the plain at 42 5 and 42 8 respectively the evaporation proportions calculated on the basis of 18o and 2h are very close to each other this shows that the method used in this paper is feasible for estimating the evaporation proportions of lakes in areas with a heavy anthropogenic influence copyright 2013 john wiley sons ltd

some observations regarding the thermal flux from earth s erupting volcanoes for the period of 2000 to 2014 we present satellite measurements of the thermal flux observed from 95 active volcanoes based on observations made daily over the past 15 years by nasa s terra and aqua moderate resolution imaging spectroradiometer sensors excursions from an apparent baseline level of thermal emission are attributable to episodic lava flow forming eruptions highest average intensity was associated with the july 2001 eruption of etna italy which radiated an average of 2 5 109 w over 23 days however recent fissure eruptions in the afar rift have attained higher average intensities of 2 4 4 4 109 w albeit for days not weeks the largest magnitude eruption was the ongoing eruption of bardarbunga iceland which radiated 2 6 1016 j k lauea hawai i has radiated the most energy since 2000 although the lava lake at nyiragongo democratic republic of congo comes a close second time series analysis reveals evidence for periodicity in radiant flux at some volcanoes but not at others

publisher s noteoverview of the precursors and dynamics of the 2012 13 basaltic fissure eruption of tolbachik volcano kamchatka russia

shifts in mid to late holocene anion composition in elk lake grant county minnesota comparison of diatom and ostracode inferences abstract the fossil diatom record from elk lake grant county minnesota was used to reconstruct salinity and brine type between 2640 and 4645 14 c yr bp this lake was selected for a brine type reconstruction because a previous study using fossil ostracode assemblages indicated a shift in anion composition during the mid holocene smith et al 1997 salinity was reconstructed using a transfer function developed for the northern great plains ngp of north america the reconstruction revealed that salinity was higher 1 5 6 2 g l 1 between 4000 and 4645 14 c yr bp and dropped to 0 35 1 2 g l 1 after 4000 14 c yr bp the anion composition of the system was investigated by passively plotting fossil diatom assemblages onto a canonical correspondence analysis cca biplot of the ngp modern samples to determine where core assemblages fell with respect to brine type the biplot suggests that elk lake was mainly a bicarbonate system but temporarily shifted to sulfate domination at 4080 14 c yr bp both the salinity and brine type reconstructions essentially agree with results from smith et al 1997 but the diatom record provides less definitive information on anion proportions as compared to anion concentrations because shifts in the relative abundances of anion associated diatom taxa generally tracked the ostracode inferred changes in brine type we conclude that fossil diatom assemblages can reveal information on shifts in brine type over time and provide insight into brine evolution and groundwater behavior in a lake system

isotopic characteristics of precipitation surface and ground waters in the yinchuan plain northwest china the isotopic characteristics of hydrogen and oxygen of various water bodies in the yinchuan plain were investigated a total of 131 water samples were collected and another 99 water samples collected by other scholars and the international atomic energy agency were referred to in the study the stable isotopic compositions of precipitation and lake waters are influenced by dry climate and strong evaporation of the area and the slope of local meteoric water line and lake water line are smaller than that of global meteoric water line the isotopic compositions of the yellow river water are significantly lower than the weighted averages of local atmospheric precipitation and are controlled by the runoff of upstream areas the isotopes of phreatic water suggest that the single phreatic water is predominantly recharged by the bedrock fissure water of helan mountain while the phreatic water in multilayer structure area is recharged by multiple sources the confined waters in the area may be recharged under cooler climate conditions than the present which makes the heavy isotopes depleted the 3h contents of various water bodies are in the following order the yellow river water multilayer phreatic water single phreatic water lake water drainage ditch water upper confined water lower confined water this is in accordance with the recharge discharge and circulation conditions of the specific water bodies the isotope compositions of waters in the yinchuan plain are mainly affected by external water recharge rather than local precipitation this study is meaningful and helpful in understanding the groundwater flow systems and water cycle in the area

magma migration at the onset of the 2012 13 tolbachik eruption revealed by seismic amplitude ratio analysis abstract in contrast of the 1975 76 tolbachik eruption the 2012 13 tolbachik eruption was not preceded by any striking change in seismic activity by processing the klyuchevskoy volcano group seismic data with the seismic amplitude ratio analysis sara method we gain insights into the dynamics of magma movement prior to this important eruption a clear seismic migration within the seismic swarm started 20 hours before the reported eruption onset 05 15 utc 26 november 2012 this migration proceeded in different phases and ended when eruptive tremor corresponding to lava flows was recorded at 11 00 utc 27 november 2012 in order to get a first order approximation of the magma location we compare the calculated seismic intensity ratios with the theoretical ones as expected the observations suggest that the seismicity migrated toward the eruption location however we explain the pre eruptive observed ratios by a vertical migration under the northern slope of plosky tolbachik volcano followed by a lateral migration toward the eruptive vents another migration is also captured by this technique and coincides with a seismic swarm that started 16 20 km to the south of plosky tolbachik at 20 31 utc on november 28 and lasted for more than 2 days this seismic swarm is very similar to the seismicity preceding the 1975 76 tolbachik eruption and can be considered as a possible aborted eruption

aster watches the world s volcanoes a new paradigm for volcanological observations from orbit onboard nasa terra spacecraft is one of the most sophisticated earth observing instruments ever flown the advanced spaceborne thermal emission and reflection radiometer aster created as part of a joint project between the japanese ministry of economy trade and industry and nasa this instrument consists of three independent bore sighted telescopes with 14 channels in the visible near infrared and thermal infrared regions capable of being pointed up to 22 5 off nadir in addition there is an additional backward looking visible channel telescope for stereo photogrammetric observations the spatial resolutions are 15 m pixel in the visible 30 m pixel in the near ir and 90 m pixel at thermal wavelengths and the swath width is 60 km aster instrument offers unprecedented opportunities for observing volcanoes and their activity from low earth orbit it is the purpose of this short paper to introduce aster to the volcanological community highlight its capabilities advantages and limitations and to show some examples of aster data and related analyses we will also explain how users can readily access aster data

morphometric and morphological development of holocene cinder cones a field and remote sensing study in the tolbachik volcanic field kamchatka article i nfo the evolution of landscape over time is a central aspect of geological paleogeographical and geomorphological studies volcanic features like cinder cones offer the opportunity to monitor the processes and development of the landscape cinder cones are perhaps the simplest and most common volcanic landforms in the world morphological and morphometric study of cinder cones has proven an efficient tool for determining their relative dates and the erosional processes affecting them the extensive kamchatka volcanic province russian far east with its large tolbachik cinder cone field is an excellent case study for spatial and temporal classification and calibration of changes in morphometric values with time we show how the morphological and morphometric values of the monogenetic cinder cones measured in the field and by digital elevation models can be used to validate their age and erosional processes field data were gps measurements of cinder cones formed at the tolbachik 1975 1976 eruption and of holocene cinder cones erosion processes on the cinder cones and lava flows were identified and evaluated for every studied cinder cone morphometric parameters were assessed on the basis of remotely sensed data and digital elevation model morphometric measurements were taken of cone height and slope and average axis diameter and the height width ratio was obtained the comparison of morphometric parameters calculated from aster dem and topographic map clearly supports the concept of relative morphometric dating as the most recent cinder cones are always associated with the highest slopes and h w ratio the measured morphometric values of the recent tolbachik cinder cones are valuable benchmark data for determining erosion rates such as the measured values for the paricutin cone in mexico after the 1943 eruption the variability of the morphometric values of the recent cinder cones is due to their lithological coarse composition a comparison with the older cinder cones in the area shows that the climatic conditions of the kamchatka peninsula and the slow development of vegetation cover determine a high rate of erosion and rapid change in the morphometric values as compared to published values for other volcanic fields

diatom based transfer functions for inferring past hydrochemical characteristics of african lakes abstract a new dataset of 282 modern diatom samples and associated environmental information has been created by merging existing regional datasets from north and east africa and niger the relationships between diatom species distributions and hydrochemistry are examined using canonical correspondence analysis cca and partial cca variables reflecting water conductivity ph and cation and anion composition account for significant and independent components of the total variation in the diatom data predictive models transfer functions are developed using the method of weighted averaging for conductivity r 2 0 87 ph r 2 0 77 and ratios between alkali and alkaline earth metals r 2 0 81 and carbonate bicarbonate and sulphate chloride ions r 2 0 82 prediction errors are estimated using the computer intensive method of jackknifing these transfer functions enlarge the potential domain for reconstruction of past hydrochemistry from fossil diatoms preserved in lake sediments

ground water processes controlling a prairie lake s response to middle holocene drought lake response to climate forcing is commonly regarded as being controlled by within lake processes we present a case from the northern great plains in which holocene drought response recorded in lake sediments was determined by changes in chemical characteristics of source ground water middle holocene ostracode assemblages were dominated by halophylic limnocythere staplini indicating increased lake water salinity yet the oxygen isotope values in this period decreased by 2 to 3 contrary to expectations of evaporative dominance we infer from these proxy records and ground water flow model results that the paleoclimatic record in the lake was mediated by changes in ground water catchment area and by reduction in evapotranspiration accompanying desiccation of peripheral lake basins

hydrogeochemical characteristics and formation of the hot springs occurring in the plunging ends of an anticline in chongqing eastern sichuan basin china hot springs occurring in two plunging ends of a very long and narrow anticline is unique this study focuses on the hydrogeochemical characteristics and formation of the anticline controlled thermal groundwater which may provide a perspective for geothermal resources potential the low to middle temperature thermal groundwater of the taozidang anticline in the sichuan basin china was examined to estimate the temperature of the deep reservoir and identify the main hydrogeochemical processes affecting the composition of hot water during circulation and evolution the occurrences of thermal groundwater of these springs strongly controlled by anticline are in the two plunging ends of the anticline and differ from that of the more common deep fault circulation controlled by faults or by faults and anticlines incongruent dissolution of the gypsum or anhydrite of the lower triassic jialingjiang and middle triassic leikoupo groups is affected by the anticline structures and results in hot water of so4 ca type meteoric water infiltrates through the karst channels and fissures at the outcropping area of carbonates to feed the groundwater part of the groundwater flows to depth and circulate along the two flanks of the anticline after heated it issues in the form of hot springs or wells in the plunging ends of the anticline another part of the groundwater undergoing a shallow circulation forms the normal temperature spring near the hot springs this study of the anticline controlled thermal groundwater is important for exploitation and utilization of geothermal energy tourism and provides a perspective for the anticline controlled geothermal resources potential

early holocene limnological and climatic variability in the northern great plains information on the timing and direction of climatic and environmental change on a millennial scale exists for many regions of north america whereas little is known about decadal to centennial scale variability here we present a high resolution analysis of diatom inferred salinity from a site in the northern great plains to reconstruct multidecadal and centennial scale climatic patterns during the early holocene the diatominferred salinity indicates a transition from fresh to highly saline conditions between c 13 400 and 7700 cal yr bp which suggests a major shift in climate from wet to dry conditions the overall trend toward increasing salinity is interrupted by several freshwater intervals between c 9800 and 7950 cal yr bp which may be the result of an increase in the frequency of monsoonal flow from the gulf of mexico the early holocene is considered to be a time of rapid change in climate and vegetation within the holocene although rates of change in the moon lake diatom assemblages were hi

monitoring of the volcanic rock compositions during the 2012 2013 fissure eruption at tolbachik volcano kamchatka abstract here we present the results from monitoring of the composition of rocks produced during the 2012 2013 fissure eruption at tolbachik volcano fte major and trace element concentrations in 75 samples are reported products of this eruption are represented by high alumina basaltic trachyandesites with higher alkalis and titanium contents than in all previously studied rocks of the tolbachik monogenetic volcanic field rocks erupted during the first three days 27 30 november from the northern also called menyailov group of vents are the most silica and alkali rich sio2 concentrations up to 55 35 wt and k2o up to 2 67 wt from december onwards when the eruptive activity switched from the menyailov vents to the southern naboko group of vents silica content dropped by 2 wt concentrations of mgo feo tio2 and mg increased and k2o and na2o concentrations and k2o mgo ratio decreased for the rest of the eruption the compositions of rocks remained constant and homogeneous no systematic compositional differences between lava bombs and scoria samples are evident trace element distributions in the rocks of the menyailov and naboko vent lavas are relatively uniform menyailov lavas have slightly higher th nb hf y and hree concentrations than the naboko vent lavas at more or less constant element ratios we explain the initial change in geochemistry by tapping of a slightly cooler and fractionated 3 mt and 8 cpx upper part of the magma storage zone before the main storage area began to feed the eruption thermodynamic constraints show that apparent liquidus temperatures varied from 1142 c to 1151 c and thermodynamic modeling shows that variations in compositions are consistent with a high degree of low pressure 100 300 mpa nominally anhydrous fractionation of a parent melt compositionally similar to the 1975 northern breakthrough high mg basalt geochemistry petrological observations and modeling are in agreement with the newly erupted material being derived from remnant high al magma from the 1975 76 southern breakthrough eruption with only slight amounts of cooling less than 1 c per year during the intervening 36 years

geochemical isotopic and hydrological mass balance approaches to constrain the lake water groundwater interaction in dal lake kashmir valley it is important to have qualitative as well as quantitative understanding of the hydraulic exchange between lake and groundwater for effective water resource management dal a famous urban fresh water lake plays a fundamental role in social cultural and economic dynamics of the kashmir valley in this paper geochemical isotopic and hydrological mass balance approaches are used to constrain the lake water groundwater interaction of dal lake and to identify the sources of lake water water samples of precipitation n 27 lake water n 18 and groundwater n 32 were collected across the lake and its catchment for the analysis of 18o and 2h a total of 444 lake water samples and 440 groundwater samples springs tube wells and dug wells were collected for the analysis of ca2 mg2 hco3 so4 2 cl no3 na and k water table and lake water level were monitored at 40 observation locations in the catchment water table map including ph and ec values corroborate and verify the gaining nature of the dal lake stable isotopes of lake water in boddal and gagribal basins showed more deviation from the global meteoric water line than hazratbal and nigeen basins indicating the evaporation of lake water the isotopic and geochemical mass balance suggested that groundwater contributes a significant proportion 23 40 to dal lake the estimated average groundwater contribution to dal lake ranged from 31 2 103 to 674 103 m3 day 1 with an average of 276 103 m3 day 1 the study will be useful to delineate the possible sources of nutrients and pollutants entering the lake and for the management of lake water resources for sustainable development

isotopic signatures of precipitation surface water and groundwater interactions poyang lake basin china poyang lake whose hydrological characteristics are impacted by the operation of the three gorges dam is the largest freshwater lake in china however water cycle mechanisms in the poyang lake basin remain poorly understood in this study stable isotopes d and 18o of water samples taken in april july and november 2013 and hydrological data are used to investigate the interactions between precipitation river water lake water and shallow groundwater in the poyang lake region the isotopic results show seasonal variations in precipitation surface water and groundwater which provides a set of tools to identify waters that have different histories the similar isotopic compositions of river water and groundwater suggest a close hydrological connection hydrological data present a positive correlation between river run off and precipitation however isotopic results show that rivers in the poyang lake basin in different seasons are primarily recharged by subsurface run off with different proportion between base flow and near surface quick flow rather than by surface run off directly formed by concurrent rainfall due to the geological characteristics of stratum in the poyang lake basin it is easier for precipitation to infiltrate into soil and recharge groundwater than to form direct surface flow that feeds rivers the groundwater system is like a huge reservoir which can effectively impound rainfall water playing an important role in restraining floodwater during the flood season and in ensuring river run off supply during the dry season