WorldWideScience

Sample records for carbonate aquifer beneath

  1. Advective heat transport in the upper carbonate aquifer beneath Winnipeg, Manitoba

    Energy Technology Data Exchange (ETDEWEB)

    Ferguson, G.A.G.; Woodbury, A.D. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Civil Engineering

    2003-07-01

    Air conditioning and industrial cooling in Winnipeg, Manitoba requires large volumes of groundwater, with the bulk of this water pumped from the Upper Carbonate Aquifer. Pumping takes place at the erosional surface of several dipping Paleozoic carbonate units beneath the city. To prevent excessive drawdown, wastewater from these processes is reinjected into the aquifer. Heat loading from the surface, combined with this practice, leads to the creation of areas of elevated temperature within the Upper Carbonate Aquifer. An industrial area located in eastern Winnipeg is the site of the largest of these anomalies, where the aquifer's permeability is enhanced by the presence of conduits and discrete fractures. The use of numerical modeling showed that the greatest temperature anomalies occur where there are very high permeabilities, especially in the form of conduits and discrete fractures. Groundwater velocities are increased by these factors, and could result in the creation of plumes of heated water. Plumes of heated water are less likely to occur where the aquifer is thicker and conduits are absent, due to advective heat transport becoming focused between the injection well and the production well in lower permeability situations. These areas also correspond to the areas of decreased transmissivity in several parts of the Upper Carbonate Aquifer, and may not be capable of producing the required volumes of groundwater for thermal applications. Taking into account these permeability features in planning and design of non-consumptive groundwater systems in the Upper Carbonate Aquifer helps to minimize both drawdown and changes in aquifer temperature. 8 refs., 2 figs.

  2. Carbon cycle: storage beneath mangroves

    OpenAIRE

    BOUILLON, S

    2011-01-01

    In the face of continued deforestation, the high carbon stocks in mangrove forests unveiled by Donato et al. provide a strong incentive to consider mangrove ecosystems as priority areas for conservation. Furthermore, these results highlight the need for scientists and funding agencies to address uncertainties regarding the fate of the carbon after land clearance. Only a handful of studies have quantified the loss of sediment carbon after mangrove clear-cutting – but all suggest that these los...

  3. Assessing the impact of modern recharge on a sandstone aquifer beneath a suburb of Doncaster, UK

    OpenAIRE

    Morris, Brian L.; Darling, W. George; Cronin, Aidan A.; Rueedi, Joerg; Whitehead, Emily J.; Gooddy, Daren C.

    2006-01-01

    A major water quality issue in urban areas underlain by a productive aquifer is the impact of modern recharge. Using a variety of sample sources including multi-level boreholes, detectable concentrations of CFCs and SF6 have been found throughout the upper 50 m of the saturated aquifer beneath a suburb of Doncaster, UK, indicating that modern (

  4. Nature and extent of lava-flow aquifers beneath Pahute Mesa, Nevada Test Site

    Energy Technology Data Exchange (ETDEWEB)

    Prothro, L.B.; Drellack, S.L. Jr.

    1997-09-01

    Work is currently underway within the Underground Test Area subproject of the US Department of Energy/Nevada Operations Office Environmental Restoration Program to develop corrective action plans in support of the overall corrective action strategy for the Nevada Test Site as established in the Federal Facility Agreement and Consent Order (FFACO, 1996). A closure plan is currently being developed for Pahute Mesa, which has been identified in the FFACO as consisting of the Western and Central Pahute Mesa Corrective Action Units. Part of this effort requires that hydrogeologic data be compiled for inclusion in a regional model that will be used to predict a contaminant boundary for these Corrective Action Units. Hydrogeologic maps have been prepared for use in the model to define the nature and extent of aquifers and confining units that might influence the flow of contaminated groundwater from underground nuclear tests conducted at Pahute Mesa. Much of the groundwater flow beneath Pahute Mesa occurs within lava-flow aquifers. An understanding of the distribution and hydraulic character of these important hydrogeologic units is necessary to accurately model groundwater flow beneath Pahute Mesa. This report summarizes the results of a study by Bechtel Nevada geologists to better define the hydrogeology of lava-flow aquifers at Pahute Mesa. The purpose of this study was twofold: (1) aid in the development of the hydrostratigraphic framework for Pahute Mesa, and (2) provide information on the distribution and hydraulic character of lava-flow aquifers beneath Pahute Mesa for more accurate computer modeling of the Western and Central Pahute Mesa Corrective Action Units.

  5. Carbon-14 measurements in aquifers with methane

    International Nuclear Information System (INIS)

    A survey of various groundwater systems indicates that methane is a common trace constituent and occasionally a major carbon species in groundwaters. Thermocatalytic methane had delta13Csub(CH4)>-45 per mille and microbially produced or biogenic methane had delta13Csub(CH4)13C values for the inorganic carbon. Thermocatalytic methane had no apparent effect on the inorganic carbon. Because methanogenesis seriously affects the carbon isotope geochemistry of groundwaters, the correction of raw 14C ages of affected groundwaters must consider these effects. Conceptual models are developed which adjust the 14C activity of the groundwater for the effects of methanogenesis and for the dilution of carbon present during infiltration by simple dissolution of rock carbonate. These preliminary models are applied to groundwaters from the Alliston sand aquifer where methanogenesis has affected most samples. In this system, methanogenic bacteria using organic matter present in the aquifer matrix as substrate have added inorganic carbon to the groundwater which has initiated further carbonate rock dissolution. These processes have diluted the inorganic carbon 14C activity. The adjusted groundwater ages can be explained in terms of the complex hydrogeology of this aquifer, but also indicate that these conceptual models must be more rigorously tested to evaluate their appropriateness. (author)

  6. Groundwater salinization mechanism of aquifers beneath Ho Chi Minh City area (Viet Nam)

    International Nuclear Information System (INIS)

    Water supplying for domestic and product activities in Hochiminh City is being taken from two both sources: surface water and groundwater. Environmental isotopes technique is emphasized to determine the salinisation mechanism of groundwater. The objectives studied are groundwater of two aquifers mainly being exploited in Hochiminh City area. Based on the national water monitoring wells existing in the studied area and the hydrogeological setting a network of 70 sampling points for both two aquifers was set up. Water samples were collected two times (in rainy season of 2001 and in the end of dry season of 2002). All collected samples were analyzed for hydrochemical and stable isotopes. 30 of them were analyzed for tritium and 15 of them were done for 14C. Analyzing hydrochemical results of collected samples show that the quality of groundwater varies from fresh to saline, soft to very hard and high iron contents in some regions. The analyses of cations and anions by Piper Trilinear Diagram show that in aquifers where saline groundwater distributed the cations are mainly sodium, calcium, and magnesium type while the anions are mainly chloride and sulfate type but in the part where fresh groundwater the cations are mainly sodium, calcium, and type while the anions are mainly bicarbonate, carbonate and nitrate type. According to TDS values the distribution of fresh and saline groundwater in studied aquifers is mapped and fresh-saline groundwater boundaries in 1990 and 2000 is also demonstrated. The distribution of groundwater samples collected along the GMWL show that groundwater in this area is recharged directly by rainfall and surface water. High tritium contents and 14C relative radioactivity of groundwater in the area also support this process. Delta values of 18O and Chloride contents plot show that it exists two main salinisation mechanism. The first one is the leaching process and the second one is mixing with seawater process and both these mechanisms are

  7. Exploration of a deep carbonate hydrogeothermal aquifer

    Science.gov (United States)

    von Hartmann, H.; Thomas, R.; Schulz, R.

    2009-04-01

    Geothermal energy is an increasing part of the worldwide energy supply. Deep aquifers for hydrogeothermal use must have very high porosities to provide a sufficient flow rate. The exploration of these hydrogeothermal reservoirs have to include all information which helps to predict these areas of high porosity and high permeability: lithology, facies, and structural framework. Therefore exploration techniques known from hydrocarbon exploration are used: 2D and 3D seismic surveys, including log data. A constraint is the amount of exploration costs. By which geophysical means it is possible to build a geological model which predicts the petrophysical parameters with a sufficient high possibility? There are three geological provinces in Germany with hydrogeothermal potential: the North German Basin, the Upper Rhine Graben, and the Southern German Molasse Basin. Within the Southern German Molasse Basin the hydrogeothermal aquifer comprises carbonate rocks of the Upper Jurassic which were lowered to a depth of approximately 3500 m. The interpretation of a 3D seismic survey shows the distribution of carbonate facies, structural framework, and karst formation. All three aspects are related among each other: faults can facilitate karst formation especially where reefs had been formed. Seismic attributes were used to enhance the visualization of these geologic features. The result is an overall understanding of geologic processes which formed areas of high porosity. In this way the advantage of 3D seismic surveys is obvious. Mapping of these areas can be done also within 3D seismic surveys. The appropriate choice of the seismic method depends on the exploration stage and the extent of the reservoirs. Elongated reservoirs which may be formed by carbonate solution along faults may be explored by 2D seismic lines to lower the costs of a geothermal project.

  8. Depleted soil carbon and nitrogen pools beneath impervious surfaces

    International Nuclear Information System (INIS)

    Urban soils and vegetation contain large pools of carbon (C) and nitrogen (N) and may sequester these elements at considerable rates; however, there have been no systematic studies of the composition of soils beneath the impervious surfaces that dominate urban areas. This has made it impossible to reliably estimate the net impact of urbanization on terrestrial C and N pools. In this study, we compared open area and impervious-covered soils in New York City and found that the C and N content of the soil (0–15 cm) under impervious surfaces was 66% and 95% lower, respectively. Analysis of extracellular enzyme activities in the soils suggests that recalcitrant compounds dominate the organic matter pool under impervious surfaces. If the differences between impervious-covered and open area soils represent a loss of C and N from urban ecosystems, the magnitude of these losses could offset sequestration in other parts of the urban landscape. - The soils beneath impervious surfaces are depleted in C and N, which may have implications for the energy and nutrient balance of urban ecosystems.

  9. REACTIVE MULTIPHASE BEHAVIOR OF CO2 IN SALINE AQUIFERS BENEATH THE COLORADO PLATEAU

    Energy Technology Data Exchange (ETDEWEB)

    R.G. Allis; J. Moore; S. White

    2003-01-30

    Gas reservoirs developed within the Colorado Plateau and Southern Rocky Mountains region represent unique natural laboratories for studying the conditions that control long-term storage of CO{sub 2}. Under appropriate conditions, the trapping of CO{sub 2} in mineral phases could equal or exceed the amount of CO{sub 2} sequestered in the pore fluids in deep aquifers. Core samples from the Springerville-St. Johns CO{sub 2} field has allowed investigation of naturally occurring mineral reactions. The presence of travertine deposits over the field provide evidence of the leakage of CO{sub 2} to the atmosphere and justify further study. During reporting period covered here (January 1 to March 30, 2003), the main achievements were: (1) Preparation of three papers to be presented at the Second Annual Conference on Carbon Sequestion (May 5-8, Alexandria, Virginia) and (2) Preparation of two papers for submission to a special volume of Chemical Geology on CO{sub 2} Sequestration.

  10. Piedmont and Blue Ridge carbonate-rock aquifers

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the extent of the Piedmont and Blue Ridge carbonate-rock aquifers in the states of New Jersey, Pennsylvania, and Maryland.

  11. Vulnerability Mapping of an Apulian Deep Carbonate Aquifer Using GIS

    OpenAIRE

    Polemio, M.; CNR-IRPI; Ricchetti, E.; Università di Bari

    1999-01-01

    Computer techniques such as Geographic Information Systems are applied to the evaluation of the vulnerability of a deep carbonate aquifer. The study area, of about 150 km2, is located in the low Murgia Plateau (Apulia) and characterized by Mesozoic limestone and dolomite rocks of several thousand meters thickness. A wide and thick aquifer resides in these carbonate rocks. Its groundwater flows toward the sea mainly under pressure and with maximum piezometric level of about 200 m a.s.l.. Du...

  12. Variation of uranium isotopes in some carbonate aquifers

    International Nuclear Information System (INIS)

    The 234U/238U alpha activity ratio (AR) and uranium concentrations are reported for 83 springs that issue from carbonate aquifers in Florida, Texas, Nevada-California, and Israel. Data for each aquifer fall within more or less mutually exclusive fields. In general, the spring in a humid climate have AR's approaching secular equilibrium, whereas those in more arid climates have AR's differing greatly from equilibrium

  13. Hydraulic conductivities of fractures and matrix in Slovenian carbonate aquifers

    Directory of Open Access Journals (Sweden)

    Timotej Verbovšek

    2008-12-01

    Full Text Available Hydraulic conductivities and specific storage coefficients of fractures and matrix in Slovenian carbonate aquifers were determined by Barker’s method for pumping test analysis, based on fractional flow dimension. Values are presented for limestones and mainly for dolomites, and additionally for separate aquifers, divided by age andlithology in several groups. Data was obtained from hydrogeological reports for 397 water wells, and among these, 79 pumping tests were reinterpreted. Hydraulic conductivities of fractures are higher than the hydraulic conductivities of matrix, and the differences are highly statistically significant. Likewise, differences are significant for specific storage, and the values of these coefficients are higher in the matrix. Values of all coefficients vary in separate aquifers, and the differences can be explained by diagenetic effects, crystal size, degree of fracturing, andcarbonate purity. Comparison of the methods, used in the reports, and the Barker’s method (being more suitable for karstic and fractured aquifers, shows that the latter fits real data better.

  14. What lies beneath: Rural landholder interpretation of the risks of aquifer exploitation in Australia

    Science.gov (United States)

    Mendham, Emily; Curtis, Allan

    2014-04-01

    Risks associated with the management of groundwater in farming landscapes are at the forefront of public discourse in Australia and North America. There has been very little social research examining rural landholder attitudes to groundwater use and management. This is an important gap given the critical role social acceptability plays in resource access decisions, the important role groundwater plays in sustaining livelihoods, and the vital role it plays in maintaining groundwater dependent ecosystems. This paper attempts to address that gap by exploring how rural landholders interpret risks associated with groundwater use for irrigated agriculture. We do that by using a case study from south eastern Australia where farmers' livelihoods are increasingly dependent on groundwater. We draw upon spatially referenced survey data to investigate the general extent and nature of concern about risk associated with pumping groundwater. We also explore the factors influencing risk interpretation, including occupational identity and proximity to the aquifer. Survey results suggest that while there is concern about pumping groundwater for irrigated agriculture in the Wimmera region, there is also considerable confidence that negative outcomes can be avoided. The dimension of risk of most concern to respondents was the possibility that the benefits of pumping groundwater would not be shared equitably. Those reporting lower concern about the risks of groundwater pumping were more likely to own properties located above the aquifer, to exhibit a strong business orientation including prioritising economic values compared to environmental values, and to express attitudes indicating they thought private property rights should be protected. A substantial proportion of survey respondents indicated they were 'Unsure' on all the risk items in the survey. It seems the future social acceptability of groundwater exploitation in the Wimmera region will depend on the extent that those 'Unsure

  15. REACTIVE MULTIPHASE BEHAVIOR OF CO2 IN SALINE AQUIFERS BENEATH THE COLORADO PLATEAU

    Energy Technology Data Exchange (ETDEWEB)

    R.G. Allis; J. Moore; S. White

    2003-06-30

    The six coal-fired power plants located in the Colorado Plateau and southern Rocky Mountain region of the U.S. produce 100 million tons of CO{sub 2} per year. Thick sequences of collocated sedimentary rocks represent potential sites for sequestration of the CO{sub 2}. Field and laboratory investigations of naturally occurring CO{sub 2}-reservoirs are being conducted to determine the characteristics of potential seal and reservoir units and the extent of the interactions that occur between the host rocks and the CO{sub 2} charged fluids. The results are being incorporated into a series of two-dimensional numerical models that represent the major chemical and physical processes induced by injection. During reporting period covered here (March 30 to June 30, 2003), the main achievements were: Presentation of three papers at the Second Annual Conference on Carbon Sequestration (May 5-8, Alexandria, Virginia); Presentation of a poster at the American Association of Petroleum Geologists meeting; Co-PI organized and chaired a special session on Geologic Carbon Dioxide Sequestration at the American Association of Petroleum Geologists annual convention in Salt Lake City (May 12-15).

  16. Geochemical detection of carbon dioxide in dilute aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, S; Hao, Y; Aines, R

    2009-03-27

    Carbon storage in deep saline reservoirs has the potential to lower the amount of CO{sub 2} emitted to the atmosphere and to mitigate global warming. Leakage back to the atmosphere through abandoned wells and along faults would reduce the efficiency of carbon storage, possibly leading to health and ecological hazards at the ground surface, and possibly impacting water quality of near-surface dilute aquifers. We use static equilibrium and reactive transport simulations to test the hypothesis that perturbations in water chemistry associated with a CO{sub 2} gas leak into dilute groundwater are important measures for the potential release of CO{sub 2} to the atmosphere. Simulation parameters are constrained by groundwater chemistry, flow, and lithology from the High Plains aquifer. The High Plains aquifer is used to represent a typical sedimentary aquifer overlying a deep CO{sub 2} storage reservoir. Specifically, we address the relationships between CO{sub 2} flux, groundwater flow, detection time and distance. The CO{sub 2} flux ranges from 10{sup 3} to 2 x 10{sup 6} t/yr (0.63 to 1250 t/m{sup 2}/yr) to assess chemical perturbations resulting from relatively small leaks that may compromise long-term storage, water quality, and surface ecology, and larger leaks characteristic of short-term well failure.

  17. Reactive Multiphase behavior of CO2 in Saline Aquifers beneath the Colorado Plateau

    International Nuclear Information System (INIS)

    Gas reservoirs developed within the Colorado Plateau and Southern Rocky Mountains region are natural laboratories for studying the factors that promote long-term storage of CO2. They also provide sites for storing additional CO2 if it can be separated from the flue gases of coal-fired power plants in this part of the U.S.A. These natural reservoirs are developed primarily in sandstones and dolomites; shales, mudstones and anhydrite form seals. In many fields, stacked reservoirs are present, indicating that the gas has migrated up through the section. There are also geologically young travertine deposits at the surface, and CO2-charged groundwater and springs in the vicinity of known CO2 occurrences. These near-surface geological and hydrological features also provide examples of the environmental effects of leakage of CO2 from reservoirs, and justify further study. During reporting period covered here (the second quarter of Year 2 of the project, i.e. January 1-March 31, 2002), the main achievements were: (1) Field trips to the central Utah and eastern Arizona travertine areas to collect data and water samples to support study of surface CO2-rich fluid leakage in these two areas. (2) Partial completion of a manuscript on natural analogues CO2 leakage from subsurface reservoirs. The remaining section on the chemistry of the fluids is in progress. (3) Improvements to CHEMTOUGH code to incorporate kinetic effects on reaction progress. (4) Submission of two abstracts (based on the above work) to the topical session at the upcoming GSA meeting in Denver titled ''Experimental, Field, and Modeling Studies of Geological Carbon Sequestration''. (5) Submission of paper to upcoming GGHT-6 conference in Kyoto. Co-PI S. White will attend this conference, and will also be involved in three other papers

  18. Groundwater characteristics and problems in carbonate rock aquifers

    International Nuclear Information System (INIS)

    The lithology and tectonic structure of carbonate rocks are directly linked to the evolution of aquifers. Solubility is based on the dissolving ability of water, especially the carbon dioxide content, as well as on the dissolving readiness of carbonate rocks. Combined application of environmental and artificial tracers provides evidence on two main fields of hydrogeology: calculation of subsurface water storage and localization of recharge areas. Artificial tracing experiments usually show rapid flow characteristics in fractures and solution channels. In contrast, environmental isotopes and dissolved solids generally process the total aquifer. Hence, a comparison between natural and artificial tracing can be used to develop a model for aquifer dynamics. Concerning the localization of recharge areas, the effect of altitude on stable hydrogen and oxygen isotopes, the chemical constraints on rock-water interactions and artificial tracing should be applied in a synoptic way. Case studies are described from an Alpine karst massif and a coastal karst area in the Mediterranean region. (author). 3 refs, 6 figs, 1 tab

  19. Geochemical detection of carbon dioxide in dilute aquifers

    Directory of Open Access Journals (Sweden)

    Aines Roger

    2009-03-01

    Full Text Available Abstract Background Carbon storage in deep saline reservoirs has the potential to lower the amount of CO2 emitted to the atmosphere and to mitigate global warming. Leakage back to the atmosphere through abandoned wells and along faults would reduce the efficiency of carbon storage, possibly leading to health and ecological hazards at the ground surface, and possibly impacting water quality of near-surface dilute aquifers. We use static equilibrium and reactive transport simulations to test the hypothesis that perturbations in water chemistry associated with a CO2 gas leak into dilute groundwater are important measures for the potential release of CO2 to the atmosphere. Simulation parameters are constrained by groundwater chemistry, flow, and lithology from the High Plains aquifer. The High Plains aquifer is used to represent a typical sedimentary aquifer overlying a deep CO2 storage reservoir. Specifically, we address the relationships between CO2 flux, groundwater flow, detection time and distance. The CO2 flux ranges from 103 to 2 × 106 t/yr (0.63 to 1250 t/m2/yr to assess chemical perturbations resulting from relatively small leaks that may compromise long-term storage, water quality, and surface ecology, and larger leaks characteristic of short-term well failure. Results For the scenarios we studied, our simulations show pH and carbonate chemistry are good indicators for leakage of stored CO2 into an overlying aquifer because elevated CO2 yields a more acid pH than the ambient groundwater. CO2 leakage into a dilute groundwater creates a slightly acid plume that can be detected at some distance from the leak source due to groundwater flow and CO2 buoyancy. pH breakthrough curves demonstrate that CO2 leaks can be easily detected for CO2 flux ≥ 104 t/yr within a 15-month time period at a monitoring well screened within a permeable layer 500 m downstream from the vertical gas trace. At lower flux rates, the CO2 dissolves in the aqueous phase

  20. Experimental simulation of magma–carbonate interaction beneath Mt. Vesuvius, Italy

    OpenAIRE

    Jolis, E. M.; Department of Earth Sciences, Uppsala University, Uppsala, Sweden; Freda, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Troll, V. R.; DEPARTMENT OF EARTH SCIENCES, UPPSALA UNIVERSITY, VILLAVAGEN 16, 75236 UPPSALA, SWEDEN; Deegan, F. M.; Department of Geosciences, Swedish Museum of Natural History; Blythe, L. S.; Department of Earth Sciences, CEMPEG, Uppsala University,; McLeod, C. L.; DEPARTMENT OF EARTH SCIENCES, THE UNIVERSITY OF DURHAM, DURHAM DH1 3LE, UK; Davidson, J. P.; DEPARTMENT OF EARTH SCIENCES, THE UNIVERSITY OF DURHAM, DURHAM DH1 3LE, UK

    2013-01-01

    We simulated the process of magma–carbonate interaction beneath Mt. Vesuvius in short duration piston-cylinder experiments under controlled magmatic conditions (from 0 to 300 s at 0.5 GPa and 1,200 C), using a Vesuvius shoshonite composition and upper crustal limestone and dolostone as starting materials. Backscattered electron images and chemical analysis (major and trace elements and Sr isotopes) of sequential experimental products allow us to identify the textural and chemical ...

  1. Fluid Dynamics of Carbon Dioxide Disposal into Saline Aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Julio Enrique

    2003-12-18

    Injection of carbon dioxide (CO{sub 2}) into saline aquifers has been proposed as a means to reduce greenhouse gas emissions (geological carbon sequestration). Large-scale injection of CO{sub 2} will induce a variety of coupled physical and chemical processes, including multiphase fluid flow, fluid pressurization and changes in effective stress, solute transport, and chemical reactions between fluids and formation minerals. This work addresses some of these issues with special emphasis given to the physics of fluid flow in brine formations. An investigation of the thermophysical properties of pure carbon dioxide, water and aqueous solutions of CO{sub 2} and NaCl has been conducted. As a result, accurate representations and models for predicting the overall thermophysical behavior of the system CO{sub 2}-H{sub 2}O-NaCl are proposed and incorporated into the numerical simulator TOUGH2/ECO{sub 2}. The basic problem of CO{sub 2} injection into a radially symmetric brine aquifer is used to validate the results of TOUGH2/ECO2. The numerical simulator has been applied to more complex flow problem including the CO{sub 2} injection project at the Sleipner Vest Field in the Norwegian sector of the North Sea and the evaluation of fluid flow dynamics effects of CO{sub 2} injection into aquifers. Numerical simulation results show that the transport at Sleipner is dominated by buoyancy effects and that shale layers control vertical migration of CO{sub 2}. These results are in good qualitative agreement with time lapse surveys performed at the site. High-resolution numerical simulation experiments have been conducted to study the onset of instabilities (viscous fingering) during injection of CO{sub 2} into saline aquifers. The injection process can be classified as immiscible displacement of an aqueous phase by a less dense and less viscous gas phase. Under disposal conditions (supercritical CO{sub 2}) the viscosity of carbon dioxide can be less than the viscosity of the aqueous

  2. Aquifers

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — This map layer contains the shallowest principal aquifers of the conterminous United States, Hawaii, Puerto Rico, and the U.S. Virgin Islands, portrayed as...

  3. Studies and projections of hydraulic conductivity of Devonian Plavinu and Daugava carbonate aquifers in Latvia

    Science.gov (United States)

    Perkone, E.; Delina, A.; Saks, T.; Raga, B.; Jātnieks, J.; Klints, I.; Popovs, K.; Babre, A.; Bikše, J.; Kalvāns, A.; Retike, I.; Ukass, J.

    2012-04-01

    Carbonate aquifers show a very wide range of hydrogeological characteristics. Carbonate rock hydrogeology display two extremes: on one hand hydrogeological properties of the carbonates are governed by the pathways of the preferential groundwater flow typical in karstic regions, on the other - some carbonate aquifers behave almost like a homogeneous, isotropic, porous medium. Most lie between these extremes, but these case variations complicates the study of carbonate aquifer properties. In this study the results of the hydraulic conductivity in carbonate aquifers measurements, hydraulic conductivity correlation between sediments lithology and the aquifer surface depth and fractures research is presented. Upper Devonian Frasnian stage Pļaviņu and Daugava carbonate aquifers in the Latvian part of the Baltic basin is considered. The aim of this research is to elaborate characteristic hydraulic conductivity values for each aquifer based on existing data of the pumping test results and other aquifer properties. Pļaviņu and Daugava carbonate aquifers mainly consist of jointed dolomite with intermediate layers of dolomitic marlstone, limestone, clays and gypsum. These aquifers are prevalent in most of the study area, except Northern and South - Eastern parts of the territory. In geological structure Daugava aquifer lies above Pļaviņu aquifer. Daugava aquifer depth changes from 10 - 20 and even less meters in Eastern part to 250 - 300 m in South - West part of study area, but thickness varies from few meters to 30 m. Pļaviņu aquifer surface depth varies from 20 - 30 m, but in uplands surface depth reaches more than 120 m, in Eastern part to more than 300 m in South - West part of study area. Aquifer average thickness varies from 20 - 40 m, but in areas with buried valleys thickness can be less than 10 meters. Outcrops of these sediments are occurring in banks of largest rivers and in some areas aquifers are karstified. In studies of the carbonate aquifers it is

  4. Internal corrosion of carbon steel piping in hot aquifers service

    Directory of Open Access Journals (Sweden)

    Simičić Miloš V.

    2011-01-01

    Full Text Available Internal corrosion of carbon steel pipelines is a major problem encountered in water service. In terms of prediction of the remaining lifetime for water pipelines based on the corrosion allowance, the three main approaches are corrosion modelling, corrosion inhibitor availability, and corrosion monitoring. In this study we used two theoretical corrosion models, CASSANDRA and NORSOK M-506 of quite different origin in order to predict uniform corrosivity of hot aquifers in eight different pipelines. Because of the varying calculation criteria for the different models, these can give very different corrosion rate predictions for the same data input. This is especially true under conditions where the formation of protective films may occur, such as at elevated temperatures. The evaluation of models was conducted by comparison using weight-loss coupons and three corrosion inhibitors were obtained from commercial suppliers. The tests were performed during the 60-day period. Even though inhibitors’ efficiencies of 98% had been achieved in laboratory testing, inhibitors’ availabilities of 85% have been used due to logistics problems and other issues. The results, given in mmpy, i.e. millimeter per year, are very consistent with NORSOK M-506 prediction. This is presumably because the model considers the effect of the formation of a passive iron carbonate film at temperatures above 80 °C and significant reduction in corrosion rate. Corrosion inhibitor A showed a better performance than inhibitors B and C in all cases but the target corrosion rates of less than 0.1 mmpy were achieved for all inhibitors. The chemical type of corrosion inhibitor A is based on quaternary amines mixed with methanol, isopropyl alcohol, xylene and ethylbenzene. Based on the obtained results the carbon steel lifetime of 30 years, provided proper inhibitors are present and 3mm corrosion allowance, can be achieved for hot aquifers service with presented water compositions.

  5. Radiocarbon, 13C and tritium in water samples from basaltic aquifers and carbonate aquifers on the island of Oahu, Hawaii

    International Nuclear Information System (INIS)

    Principal fresh water aquifers on the subtropical island of Oahu consist of basaltic rocks that are devoid of fossil carbonate minerals. In southern Oahu fresh water occurs as semi-independent basal lenses which float on salt water and are bounded by sedimentary formations along the coast and in valley bottoms. The latter formations contain carbonate aquifers. Fresh water also occurs in dike compartments located in the central parts of the mountains. The radiocarbon content of groundwater recharge on Oahu is between 96 and 100% modern. The 13C concentration associated with fresh groundwater is between -17 and -19 δ per mille PDB and remains constant while such waters reside in, or travel through, basaltic rock aquifers. Radiocarbon and tritium data on basal waters withdrawn by major pumping stations show these waters to have ages between a few decades and several hundred years. Differences in these ages relate systematically to individual pumping rates of the stations, well depths and local lens thickness. (author)

  6. Chemical and carbon isotopic composition of dissolved organic carbon in a regional confined methanogenic aquifer

    Science.gov (United States)

    Aravena, R.; Wassenaar, L.I.; Spiker, E. C.

    2004-01-01

    This study demonstrates the advantage of a combined use of chemical and isotopic tools to understand the dissolved organic carbon (DOC) cycle in a regional confined methanogenic aquifer. DOC concentration and carbon isotopic data demonstrate that the soil zone is a primary carbon source of groundwater DOC in areas close to recharge zones. An in-situ DOC source linked to organic rich sediments present in the aquifer matrix is controlling the DOC pool in the central part of the groundwater flow system. DOC fractions, 13C-NMR on fulvic acids and 14C data on DOC and CH4 support the hypothesis that the in-situ DOC source is a terrestrial organic matter and discard the Ordovician bedrock as a source of DOC. ?? 2004 Taylor and Francis Ltd.

  7. Microbial Response to Carbon Dioxide Injection in a Shallow Aquifer

    Science.gov (United States)

    Rook, A.; Faehndrich, D.; O'Mullan, G.; Mailloux, B.; Matter, J.; Stute, M.; Goldberg, D.

    2007-12-01

    Extensive research is underway to investigate the geophysical and geochemical dynamics of subsurface carbon sequestration, but there has been only theoretical consideration of the microbial response. Microbial dynamics are capable of altering the range and rates of geochemical reactions in the subsurface. The goal of this field experiment is to link geochemical changes due to CO2 injection to alterations in the microbial community and to provide an initial characterization of the microbial response. A seven week push-pull experiment was conducted at the Lamont-Doherty Earth Observatory Test Well. 200L of groundwater was extracted, bubbled with carbon dioxide, augmented with a bromide tracer, and injected to 230m depth below ground surface. The hydraulically isolated injection zone marked the contact area between dolerite sill and sedimentary rock. Samples were taken on a weekly basis. Geochemically, a drop in pH from 9.4 to 4.5 at injection was coupled with a release of Fe2+ from the formation. As neutralization and mixing caused pH to return toward background levels, Fe2+ concentrations decreased. The aquifer remained anoxic throughout the experiment. DNA was successfully extracted and the gene encoding 16S ribosomal RNA was amplified from all samples with the exception of the injection fluid. Sequencing from clone libraries and tRFLP analyses were used to characterize microbial dynamics during the seven week study. Whereas the number of microbial groups detected remained relatively constant over the course of the experiment, changes were observed in both the dominant microbes phylogenetic identity and relative abundance. Methane concentrations increased from background levels (below 50 nM) to 4.2 nM after injection, but initial attempts to amplify archaeal and methanogen-specific genes were unsuccessful, bringing into question the presence of a significant methanogenic population. These results confirm that there is a microbial response to carbon dioxide

  8. Review and model-based analysis of factors influencing soil carbon sequestration beneath switchgrass (Panicum virgatum)

    Energy Technology Data Exchange (ETDEWEB)

    Garten Jr, Charles T [ORNL

    2012-01-01

    Abstract. A simple, multi-compartment model was developed to predict soil carbon sequestration beneath switchgrass (Panicum virgatum) plantations in the southeastern United States. Soil carbon sequestration is an important component of sustainable switchgrass production for bioenergy because soil organic matter promotes water retention, nutrient supply, and soil properties that minimize erosion. A literature review was included for the purpose of model parameterization and five model-based experiments were conducted to predict how changes in environment (temperature) or crop management (cultivar, fertilization, and harvest efficiency) might affect soil carbon storage and nitrogen losses. Predictions of soil carbon sequestration were most sensitive to changes in annual biomass production, the ratio of belowground to aboveground biomass production, and temperature. Predictions of ecosystem nitrogen loss were most sensitive to changes in annual biomass production, the soil C/N ratio, and nitrogen remobilization efficiency (i.e., nitrogen cycling within the plant). Model-based experiments indicated that 1) soil carbon sequestration can be highly site specific depending on initial soil carbon stocks, temperature, and the amount of annual nitrogen fertilization, 2) response curves describing switchgrass yield as a function of annual nitrogen fertilization were important to model predictions, 3) plant improvements leading to greater belowground partitioning of biomass could increase soil carbon sequestration, 4) improvements in harvest efficiency have no indicated effects on soil carbon and nitrogen, but improve cumulative biomass yield, and 5) plant improvements that reduce organic matter decomposition rates could also increase soil carbon sequestration, even though the latter may not be consistent with desired improvements in plant tissue chemistry to maximize yields of cellulosic ethanol.

  9. Modeling the Impact of Carbon Dioxide Leakage into an Unconfined, Oxidizing Carbonate Aquifer

    Energy Technology Data Exchange (ETDEWEB)

    Bacon, Diana H.; Qafoku, Nikolla; Dai, Zhenxue; Keating, Elizabeth; Brown, Christopher F.

    2016-01-01

    Multiphase, reactive transport modeling was used to identify the mechanisms controlling trace metal release under elevated CO2 conditions from a well-characterized carbonate aquifer. Modeling was conducted for two experimental scenarios: batch experiments to simulate sudden, fast, and short-lived release of CO2 as would occur in the case of well failure during injection, and column experiments to simulate more gradual leaks such as those occurring along undetected faults, fractures, or well linings. Observed and predicted trace metal concentrations are compared to groundwater concentrations from this aquifer to determine the potential for leaking CO2 to adversely impact drinking water quality. Finally, a three-dimensional multiphase flow and reactive-transport simulation of CO2 leakage from an abandoned wellbore into a generalized model of the shallow, unconfined portion of the aquifer is used to determine potential impacts on groundwater quality. As a measure of adverse impacts on groundwater quality, both the EPA’s MCL limits and the maximum trace metal concentration observed in the aquifer were used as threshold values.

  10. Factors Affecting Water Quality in Selected Carbonate Aquifers in the United States,1993-2005

    Science.gov (United States)

    Lindsey, Bruce D.; Berndt, Marian P.; Katz, Brian G.; Ardis, Ann F.; Skach, Kenneth A.

    2009-01-01

    Carbonate aquifers are an important source of water in the United States; however, these aquifers can be particularly susceptible to contamination from the land surface. The U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program collected samples from wells and springs in 12 carbonate aquifers across the country during 1993-2005; water-quality results for 1,042 samples were available to assess the factors affecting ground-water quality. These aquifers represent a wide range of climate, land-use types, degrees of confinement, and other characteristics that were compared and evaluated to assess the effect of those factors on water quality. Differences and similarities among the aquifers were also identified. Samples were analyzed for major ions, radon, nutrients, 47 pesticides, and 54 volatile organic compounds (VOCs). Geochemical analysis helped to identify dominant processes that may contribute to the differences in aquifer susceptibility to anthropogenic contamination. Differences in concentrations of dissolved oxygen and dissolved organic carbon and in ground-water age were directly related to the occurrence of anthropogenic contaminants. Other geochemical indicators, such as mineral saturation indexes and calcium-magnesium molar ratio, were used to infer residence time, an indirect indicator of potential for anthropogenic contamination. Radon exceeded the U.S. Environmental Protection Agency proposed Maximum Contaminant Level (MCL) of 300 picocuries per liter in 423 of 735 wells sampled, of which 309 were drinking-water wells. In general, land use, oxidation-reduction (redox) status, and degree of aquifer confinement were the most important factors affecting the occurrence of anthropogenic contaminants. Although none of these factors individually accounts for all the variation in water quality among the aquifers, a combination of these characteristics accounts for the majority of the variation. Unconfined carbonate aquifers that had high

  11. Density and stability of soil organic carbon beneath impervious surfaces in urban areas.

    Science.gov (United States)

    Wei, Zongqiang; Wu, Shaohua; Yan, Xiao; Zhou, Shenglu

    2014-01-01

    Installation of impervious surfaces in urban areas has attracted increasing attention due to its potential hazard to urban ecosystems. Urban soils are suggested to have robust carbon (C) sequestration capacity; however, the C stocks and dynamics in the soils covered by impervious surfaces that dominate urban areas are still not well characterized. We compared soil organic C (SOC) densities and their stabilities under impervious surface, determined by a 28-d incubation experiment, with those in open areas in Yixing City, China. The SOC density (0-20 cm) under impervious surfaces was, on average, 68% lower than that in open areas. Furthermore, there was a significantly (Pdensities of SOC and total nitrogen (N) in the open soils, whereas the correlation was not apparent for the impervious-covered soils, suggesting that the artificial soil sealing in urban areas decoupled the cycle of C and N. Cumulative CO2-C evolved during the 28-d incubation was lower from the impervious-covered soils than from the open soils, and agreed well with a first-order decay model (Ct = C1+C0(1-e-kt)). The model results indicated that the SOC underlying capped surfaces had weaker decomposability and lower turnover rate. Our results confirm the unique character of urban SOC, especially that beneath impervious surface, and suggest that scientific and management views on regional SOC assessment may need to consider the role of urban carbon stocks. PMID:25299685

  12. Carbon sequestration in soil beneath long-term Miscanthus plantations as determined by 13C abundance

    International Nuclear Information System (INIS)

    Miscanthus is a perennial rhizomatous warm-season grass with C4-photosynthesis. It shows considerable production potentials (10-20 t dry matter ha-1) under NW European growth conditions and plantations of Miscanthus are established to provide biomass for energy. The plant senesces in the autumn in response to adverse climatic conditions, but harvest is normally postponed until spring when the biomass is more suitable for combustion. Total pre-harvest and harvest losses may account for as much as two-thirds of autumn standing biomass and these losses provide a significant carbon input to the soil. In this study, we examine soil organic carbon (SOC) storage and turnovers beneath 9 and 16 year old Miscanthus plantations established at Hornum, Denmark (56 deg. 50'N, 09 deg. 26'E). The soil is a loamy sand (Typic Haplumbrept, coarse loamy, mixed, mesic) with a C3 vegetation history. Soil was sampled at 0-20, 20-50 and 50-100 cm depth in the Miscanthus plantations and in two reference sites under C3-plants. The 0-20 cm samples were divided into fine soil (13C/12C ratio. Rhizomes/stubbles accounted for 10.9-12.6 t DM ha-1 and coarse roots for 3.2-3.7 t DM ha-1 at 0-20 cm depth. No rhizomes and coarse roots were observed in the deeper soil layers. Concentrations of SOC were higher at all soil depths under the 16 year old Miscanthus whereas 9 years of Miscanthus and reference sites showed similar SOC concentrations. δ13C in 0-20 cm reference soil averaged -27.6 per mille while soil beneath 9 and 16 year Miscanthus showed -25.6 per mille and -22.8 per mille, respectively. Difference in δ13C between reference and Miscanthus soils was smaller at greater soil depths. SOC inventories at 0-100 cm ranged from 91-92 t C ha-1 in reference and 9 year Miscanthus to 106 t C ha-1 under 16 years of Miscanthus growing. The main part of the SOC was at 0-20 and 20-50 cm soil with 30-40 t C ha-1 in each layer. Although changes in the overall SOC storage were less significant, 13% and 31

  13. Uranium isotopes in carbonate aquifers of arid region setting

    DEFF Research Database (Denmark)

    Alshamsi, Dalal M.; Murad, Ahmed A.; Aldahan, Ala;

    2013-01-01

    429–5,293 ng L-1 (average: 2,508 ng L-1) respectively. These uranium concentrations are below the higher permissible WHO limit for drinking water and also comparable to averages found in groundwater from similar aquifers in Florida and Tunisia. Negative correlation between rainfall and uranium...

  14. Study of a Dolomitic Aquifer with Carbon-14 and Tritium

    International Nuclear Information System (INIS)

    The Dolomite Series which outcrops over an extensive area of the Transvaal is frequently subdivided into separate groundwater compartments by vertical diabase dykes to form well-defined aquifers which usually overflow in strong springs at the lowest point on the surface. The hydrology of one such compartment has been analysed to provide figures for the aquifer characteristics which can be compared with the results of the isotope data. The recharge rate of the aquifer is found to be 17.7 mm/yr and the storage capacity is about 57 times the annual recharge. Expressions for the age distribution in an idealized model of the aquifer and the age of the water discharging from the spring are derived and used to determine the recharge and capacity from the 14C and tritium data. The initial 14C content of the groundwater varies from 80 to 90% with the result that this isotope is relatively unsuitable for quantitative deductions of recharge etc. Both 14C and tritium show a linear increase in age with depth in accordance with the theory. From the tritium results a recharge rate of 11.5 mm/yr, and a storage capacity of 106 times the annual recharge is deduced. Practically the same results are obtained from the tritium content of the spring water if the initial tritium content of the recharge, extrapolated from the age-depth curve (7 TU), is used and the relationship between average age and apparent age of the discharge employed. (author)

  15. Study of a dolomitic aquifer with carbon-14 and tritium

    International Nuclear Information System (INIS)

    The Dolomite Series which outcrops over an extensive area of the Transvaal is frequently subdivided into separate groundwater compartments by vertical diabase dykes to form well-defined aquifers which usually overflow in strong springs at the lowest point on the surface. The hydrology of one such compartment has been analysed to provide figures for the aquifer characteristics which can be compared with the results of the isotope data. The recharge rate of the aquifer is found to be 17.7 mm/yr and the storage capacity is about 57 times the annual recharge. Expressions for the age distribution in an idealized model of the aquifer and the age of the water discharging from the spring are derived and used to determine the recharge and capacity from the 14C and tritium data. The initial 14C content of the groundwater varies from 80 to 90% with the result that this isotope is relatively unsuitable for quantitative deductions of recharge etc. Both 14C and tritium show a linear increase in age with depth in accordance with the theory. From the tritium results a recharge rate of 11.5 mm/yr, and a storage capacity of 106 times the annual recharge is deduced. Practically the same results are obtained from the tritium content of the spring water if the initial tritium content of the recharge, extrapolated from the age-depth curve (7 TU), is used and the relationship between average age and apparent age of the discharge employed. (author)

  16. Hydrochemical and isotopic evolution in a deep carbonate aquifer in northern Andalusia, Spain

    International Nuclear Information System (INIS)

    The Loma de Ubeda aquifer is formed by Jurassic carbonates with a mean thickness of about 80 m. The carbonate sequence is covered in the southern part of the study area by a thick sequence of Miocene sediments, and groundwater becomes confined. Groundwater samples in the phreatic zone contain tritium activities similar to present-day precipitation, as well as high nitrate contents, indicating the relevance of recent recharge. Further down-gradient, in the confined part of the aquifer, tritium contents become null. δ18O values in most groundwater samples are similar to those of present-day recharge. The uncorrected 14C-DIC 'ages' increase from recent up to 20-25 ka in the deepest part of the aquifer. Carbon-13 values in the confined part become progressively depleted (up to -21 per mille,) indicating the presence of a source of organic carbon in the aquifer. The δ34S values in dissolved sulphate and the high concentrations of H2S reflect the importance of sulphate reduction. Geochemical models suggest that the residence time of groundwater in the deepest part is up to 10,000 years younger than the uncorrected 14C-DIC ages. (author)

  17. Distribution of potentially bioavailable natural organic carbon in aquifer sediments at a chloroethene-contaminated site

    Science.gov (United States)

    Thomas, L.K.; Widdowson, M.A.; Chapelle, F.H.; Novak, J.T.; Boncal, J.E.; Lebrón, C. A.

    2012-01-01

    The distribution of natural organic carbon was investigated at a chloroethene-contaminated site where complete reductive dechlorination of tetrachloroethene (PCE) to vinyl chloride and ethene was observed. In this study, operationally defined potentially bioavailable organic carbon (PBOC) was measured in surficial aquifer sediment samples collected at varying depths and locations in the vicinity of a dense nonaqueous phase liquid (DNAPL) source and aqueous phase plume. The relationship between chloroethene concentrations and PBOC levels was examined by comparing differences in extractable organic carbon in aquifer sediments with minimal chloroethene exposure relative to samples collected in the source zone. Using performance-monitoring data, direct correlations with PBOC were also developed with chloroethene concentrations in groundwater. Results show a logarithm-normal distribution for PBOC in aquifer sediments with a mean concentration of 187  mg/kg. PBOC levels in sediments obtained from the underlying confining unit were generally greater when compared to sediments collected in the sandy surficial aquifer. Results demonstrated a statistically significant inverse correlation (p=0.007) between PBOC levels in aquifer sediments and chloroethene concentrations for selected monitoring wells in which chloroethene exposure was the highest. Results from laboratory exposure assays also demonstrated that sediment samples exhibited a reduction in PBOC levels of 35% and 73%, respectively, after a 72-h exposure period to PCE (20,000  μg/L). These results support the notion that PBOC depletion in sediments may be expected in chloroethene-contaminated aquifers, which has potential implications for the long-term sustainability of monitored natural attenuation.

  18. Uranium isotopes in carbonate aquifers of arid region setting

    International Nuclear Information System (INIS)

    Groundwater in arid and semiarid regions is vital resource for many uses and therefore information about concentrations of uranium isotopes among other chemical parameters are necessary. In the study presented here, distribution of 238U and 235U in groundwater of four selected locations in the southern Arabian peninsula, namely at two locations within the United Arab Emirates (UAE) and two locations in Oman are discussed. The analyses of the uranium isotopes were performed using ICP-MS and the results indicated a range of concentrations for 235U and 238U at 3-39 ng L-1 (average: 18 ng L-1) and 429-5,293 ng L-1 (average: 2,508 ng L-1) respectively. These uranium concentrations are below the higher permissible WHO limit for drinking water and also comparable to averages found in groundwater from similar aquifers in Florida and Tunisia. Negative correlation between rainfall and uranium concentrations suggests that in lithologically comparable aquifers, climate may influence the concentration of uranium in subtropical to arid regions. (author)

  19. Interlaboratory study of a method for determining nonvolatile organic carbon in aquifer materials

    Science.gov (United States)

    Caughey, M.E.; Barcelona, M.J.; Powell, R.M.; Cahill, R.A.; Gron, C.; Lawrenz, D.; Meschi, P.L.

    1995-01-01

    The organic carbon fraction in aquifer materials exerts a major influence on the subsurface mobilities of organic and organic-associated contaminants. The spatial distribution of total organic carbon (TOC) in aquifer materials must be determined before the transport of hydrophobic organic pollutants in aquifers can be modeled accurately. Previous interlaboratory studies showed that it is difficult to measure TOC concentrations 1%. We have tested a new analytical method designed to improve the accuracy and precision of nonvolatile TOC quantitation in geologic materials that also contain carbonate minerals. Four authentic aquifer materials and one NIST standard reference material were selected as test materials for a blind collaborative study. Nonvolatile TOC in these materials ranged from 0.05 to 1.4%, while TIC ranged from 0.46 to 12.6%. Sample replicates were digested with sulfurous acid, dried at 40??C, and then combusted at 950??C using LECO or UIC instruments. For the three test materials that contained >2% TIC, incomplete acidification resulted in a systematic positive bias of TOC values reported by five of the six laboratories that used the test method. Participants did not have enough time to become proficient with the new method before they analyzed the test materials. A seventh laboratory successfully used an alternative method that analyzed separate liquid and solid fractions of the acidified sample residues. ?? 1995 Springer-Verlag.

  20. Geochemistry of dissolved inorganic carbon in a Coastal Plain aquifer. 2. Modeling carbon sources, sinks, and δ13C evolution

    Science.gov (United States)

    McMahon, Peter B.; Chapelle, Francis H.

    1991-01-01

    Stable isotope data for dissolved inorganic carbon (DIC), carbonate shell material and cements, and microbial CO2 were combined with organic and inorganic chemical data from aquifer and confining-bed pore waters to construct geochemical reaction models along a flowpath in the Black Creek aquifer of South Carolina. Carbon-isotope fractionation between DIC and precipitating cements was treated as a Rayleigh distillation process. Organic matter oxidation was coupled to microbial fermentation and sulfate reduction. All reaction models reproduced the observed chemical and isotopic compositions of final waters. However, model 1, in which all sources of carbon and electron-acceptors were assumed to be internal to the aquifer, was invalidated owing to the large ratio of fermentation CO2 to respiration CO2 predicted by the model (5–49) compared with measured ratios (two or less). In model 2, this ratio was reduced by assuming that confining beds adjacent to the aquifer act as sources of dissolved organic carbon and sulfate. This assumption was based on measured high concentrations of dissolved organic acids and sulfate in confining-bed pore waters (60–100 μM and 100–380 μM, respectively) relative to aquifer pore waters (from less than 30 μM and 2–80 μM, respectively). Sodium was chosen as the companion ion to organic-acid and sulfate transport from confining beds because it is the predominant cation in confining-bed pore waters. As a result, excessive amounts of Na-for-Ca ion exchange and calcite precipitation (three to four times more cement than observed in the aquifer) were required by model 2 to achieve mass and isotope balance of final water. For this reason, model 2 was invalidated. Agreement between model-predicted and measured amounts of carbonate cement and ratios of fermentation CO2 to respiration CO2 were obtained in a reaction model that assumed confining beds act as sources of DIC, as well as organic acids and sulfate. This assumption was

  1. Inorganic carbon cycle in soil-rock-groundwater system in karst and fissured aquifers

    Directory of Open Access Journals (Sweden)

    Ajda Koceli

    2013-12-01

    Full Text Available The paper presents a systematic analysis of the isotopic composition of carbon (δ13CCaCO3 in carbonate rocks in central Slovenia, representing karst and fissured aquifers, and share of carbon contributions from carbonate dissolution and degradation of organic matter in aquifers, calculated from the mass balance equation. 59 samples of rocks (mainly dolomites from Upper Permian to Upper Triassic age were analyzed. Samples of carbonate rocks were pulverized and ground to fraction of 45 μm and for determination of δ13CCaCO3 analyzed with mass spectrometer for analyses of stable isotopes of light elements-IRMS. The same method was used for determination of isotopic composition of dissolved inorganic carbon (δ13CDIC in groundwater for 54 of 59 locations. Values of δ13CCaCO3 are in the range from -2.0 ‰ to +4.1 ‰, with an average δ13CCaCO3 value of +2.2 ‰. These values are typical for marine carbonates with δ13CCaCO3 around 0 ‰, although δ13CCaCO3 values differ between groups depending on the origin and age. Early diagenetic dolomites have relatively higher values of δ13CCaCO3 compared to other analyzed samples. The lowest values of δ13CCaCO3 were observed in Cordevolian and Bača dolomite, probably due to late diagenesis, during which meteoric water with lower isotopic carbon composition circulated in the process of sedimentation. Values of δ13CDIC range from -14.6 ‰ to -8.2 ‰. Higher δ13CDIC values (-8.2 ‰ indicate a low proportion of soil CO2 in the aquifer and rapid infiltration, while lower values (-14.6 ‰ indicate higher proportion of soil CO2 in the aquifer and slower infiltration. Calculated contributions of carbon from organic matter / dissolution of carbonates in the karstic and fissured aquifers s how a similar proportion (50 % : 50 %.

  2. Potentially bioavailable natural organic carbon and hydrolyzable amino acids in aquifer sediments

    Science.gov (United States)

    Thomas, Lashun K.; Widdowson, Mark A.; Novak, John T.; Chapelle, Francis H.; Benner, Ronald; Kaiser, Karl

    2012-01-01

    This study evaluated the relationship between concentrations of operationally defined potentially bioavailable organic -carbon (PBOC) and hydrolyzable amino acids (HAAs) in sediments collected from a diverse range of chloroethene--contaminated sites. Concentrations of PBOC and HAA were measured using aquifer sediment samples collected at six selected study sites. Average concentrations of total HAA and PBOC ranged from 1.96 ± 1.53 to 20.1 ± 25.6 mg/kg and 4.72 ± 0.72 to 443 ± 65.4 mg/kg, respectively. Results demonstrated a statistically significant positive relationship between concentrations of PBOC and total HAA present in the aquifer sediment (p amino acids are known to be readily biodegradable carbon compounds, this relationship suggests that the sequential chemical extraction procedure used to measure PBOC is a useful indicator of bioavailable carbon in aquifer sediments. This, in turn, is consistent with the interpretation that PBOC measurements can be used for estimating the amount of natural organic carbon available for driving the reductive dechlorination of chloroethenes in groundwater systems.

  3. The character of organic carbon in recharge water and arsenic mobilization in Bangladesh aquifers

    Science.gov (United States)

    Pracht, L. E.; Fussell, A. H.; Polizzotto, M.; Badruzzaman, A. M.; Ali, M. A.; Neumann, R. B.

    2012-12-01

    In Bangladesh, arsenic-contaminated groundwater, used for both drinking and irrigation supplies, negatively affects the health of millions of people. Past work at our site in Munshiganj suggests that current patterns of arsenic concentration in the aquifer are related to groundwater flow and recharge chemistry. Constructed ponds and groundwater-irrigated rice fields serve as the primary aquifer recharge sources, with pond recharge evolving into high-arsenic groundwater and rice field recharge evolving into low-arsenic groundwater. The composition of these water types vary in concentrations and character of dissolved organic carbon, a presumed key component in the mechanism of arsenic release from sediments. Here we present results from an experiment-based laboratory study that directly tests the role of organic carbon character and bioavailability on arsenic mobilization. Incubation experiments using sediment samples collected from Bangladesh and waters with different carbon sources (e.g., pond and rice field recharge water and artificial water with model carbon compounds) were conducted to show the phase transformations carbon undergoes during arsenic mobilization processes, to isolate the carbon components and characteristics most responsible for mobilization reactions, and to investigate the importance of secondary chemical constituents for completion of these physiochemical reactions. Water, gas, and sediment samples collected from the incubations were analyzed for nutrient, metal, anion, and carbon concentrations, as well as carbon character. The results clarify the chemical components most critical in arsenic mobilization and provide insight into the in situ chemical reactions occurring in the aquifer. Moreover, this better chemical understanding helps elucidate the potential impact of altered recharge patterns and recharge chemistry on arsenic concentrations of Bangladeshi groundwater supplies.

  4. Laboratory Experiments to Evaluate Matrix Diffusion of Dissolved Organic Carbon Carbon-14 in Southern Nevada Fractured-rock Aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Hershey, Ronald L. [Nevada University, Reno, NV (United States). Desert Research Institute; Fereday, Wyatt [Nevada University, Reno, NV (United States). Desert Research Institute

    2016-05-01

    Dissolved inorganic carbon (DIC) carbon-14 (14C) is used to estimate groundwater ages by comparing the DIC 14C content in groundwater in the recharge area to the DIC 14C content in the downgradient sampling point. However, because of chemical reactions and physical processes between groundwater and aquifer rocks, the amount of DIC 14C in groundwater can change and result in 14C loss that is not because of radioactive decay. This loss of DIC 14C results in groundwater ages that are older than the actual groundwater ages. Alternatively, dissolved organic carbon (DOC) 14C in groundwater does not react chemically with aquifer rocks, so DOC 14C ages are generally younger than DIC 14C ages. In addition to chemical reactions, 14C ages may also be altered by the physical process of matrix diffusion. The net effect of a continuous loss of 14C to the aquifer matrix by matrix diffusion and then radioactive decay is that groundwater appears to be older than it actually is. Laboratory experiments were conducted to measure matrix diffusion coefficients for DOC 14C in volcanic and carbonate aquifer rocks from southern Nevada. Experiments were conducted using bromide (Br-) as a conservative tracer and 14C-labeled trimesic acid (TMA) as a surrogate for groundwater DOC. Outcrop samples from six volcanic aquifers and five carbonate aquifers in southern Nevada were used. The average DOC 14C matrix diffusion coefficient for volcanic rocks was 2.9 x 10-7 cm2/s, whereas the average for carbonate rocks was approximately the same at 1.7 x 10-7 cm2/s. The average Br- matrix diffusion coefficient for volcanic rocks was 10.4 x 10-7 cm2/s, whereas the average for carbonate rocks was less at 6.5 x 10-7 cm2/s. Carbonate rocks exhibited greater variability in

  5. Geochemistry of silicate-rich rocks can curtail spreading of carbon dioxide in subsurface aquifers

    Science.gov (United States)

    Cardoso, S. S. S.; Andres, J. T. H.

    2014-12-01

    Pools of carbon dioxide are found in natural geological accumulations and in engineered storage in saline aquifers. It has been thought that once this CO2 dissolves in the formation water, making it denser, convection streams will transport it efficiently to depth, but this may not be so. Here, we assess theoretically and experimentally the impact of natural chemical reactions between the dissolved CO2 and the rock formation on the convection streams in the subsurface. We show that, while in carbonate rocks the streaming of dissolved carbon dioxide persists, the chemical interactions in silicate-rich rocks may curb this transport drastically and even inhibit it altogether. These results challenge our view of carbon sequestration and dissolution rates in the subsurface, suggesting that pooled carbon dioxide may remain in the shallower regions of the formation for hundreds to thousands of years. The deeper regions of the reservoir can remain virtually carbon free.

  6. Interpretation of well logs in a carbonate aquifer. Water-resources investigations (final)

    International Nuclear Information System (INIS)

    Geophysical logs from two core holes in the Edwards aquifer in Texas were analyzed and the results compared to other geologic and hydrologic data obtained from well tests and core studies. The acoustic velocity, sidewall neutron, and density logs are especially useful in the study of carbonate aquifers because porosity, secondary porosity, rock composition, and bulk density can be determined from them. Under some conditions, deeply focused resistivity logs can be used to calculate formation water resistivity and the cementation exponent. The log analysis methods described can be applied to other carbonate systems by hand plotting and a few simple calculations which can be performed on a pocket calculator. The hydrologist is advised of specific criteria which his logs must meet in order to derive maximum value from the analysis

  7. Assessing groundwater availability in a folded carbonate aquifer through the development of a numerical model

    Science.gov (United States)

    Di Salvo, Cristina; Romano, Emanuele; Guyennon, Nicolas; Bruna Petrangeli, Anna; Preziosi, Elisabetta

    2015-04-01

    The study of aquifer systems from a quantitative point of view is fundamental for adopting water management plans aiming at preserving water resources and reducing environmental risks related to groundwater level and discharge changes. This is also what the European Union Water Framework Directive (WFD, 2000/60/EC) states, holding the development of numerical models as a key aspect for groundwater management. The objective of this research is to i) define a methodology for modeling a complex hydrogeological structure in a structurally folded carbonate area and ii) estimate the concurrent effects of exploitation and climate changes on groundwater availability through the implementation of a 3D groundwater flow model. This study concerns the Monte Coscerno karst aquifer located in the Apennine chain in Central Italy in the Nera River Valley.This aquifer, is planned to be exploited in the near future for water supply. Negative trends of precipitation in Central Italy have been reported in relation to global climate changes, which are expected to affect the availability of recharge to carbonate aquifers throughout the region . A great concern is the combined impact of climate change and groundwater exploitation, hence scenarios are needed taking into account the effect of possible temperature and precipitation trends on recharge rates. Following a previous experience with model conceptualization and long-term simulation of groundwater flow, an integrated three-dimensional groundwater model has been developed for the Monte Coscerno aquifer. In a previous paper (Preziosi et al 2014) the spatial distribution of recharge to this aquifer was estimated through the Thornthwaite Mather model at a daily time step using as inputs past precipitation and temperature values (1951-2013) as well as soil and landscape properties. In this paper the numerical model development is described. On the basis of well logs from private consulting companies and literature cross sections the

  8. Megaporosity and permeability of Thalassinoides-dominated ichnofabrics in the Cretaceous karst-carbonate Edwards-Trinity aquifer system, Texas

    Science.gov (United States)

    Cunningham, Kevin J.; Sukop, Michael C.

    2012-01-01

    Current research has demonstrated that trace fossils and their related ichnofabrics can have a critical impact on the fluid-flow properties of hydrocarbon reservoirs and groundwater aquifers. Most petroleum-associated research has used ichnofabrics to support the definition of depositional environments and reservoir quality, and has concentrated on siliciclastic reservoir characterization and, to a lesser degree, carbonate reservoir characterization (for example, Gerard and Bromley, 2008; Knaust, 2009). The use of ichnology in aquifer characterization has almost entirely been overlooked by the hydrologic community because the dynamic reservoir-characterization approach has not caught on with hydrologists and so hydrology is lagging behind reservoir engineering in this area (de Marsily and others, 2005). The objective of this research is to show that (1) ichnofabric analysis can offer a productive methodology for purposes of carbonate aquifer characterization, and (2) a clear relation can exist between ichnofabrics and groundwater flow in carbonate aquifers.

  9. A groundwater conceptual model and karst-related carbon sink for a glacierized alpine karst aquifer, Southwestern China

    Science.gov (United States)

    Zeng, Cheng; Liu, Zaihua; Yang, Jianwen; Yang, Rui

    2015-10-01

    In the Jade Dragon Snow Mountain (JDSM) region, Yunnan Province, SW China, an extensive hydrochemical and stable isotopic study of a glacierized alpine karst aquifer was conducted during the period, 2011-2014. The objectives of the study were: first, to establish a conceptual hydrogeological model of the karst groundwater system; second, to estimate the proportion of extra glacier melt water infiltrating the karst aquifer that is being induced by the regional climate warming; third, to calculate the karst-related flux of carbon into the karst aquifer. Knowledge of the local hydrogeological background from previous work was the starting point of the hydrochemical and stable isotopic study. Some representative spring waters and recharge waters (i.e. glacier melt water and rainwater) were investigated both spatially and temporally by hydrochemical and isotopic techniques, including analysis of major and some minor ions and O and H stable isotopes. A conceptual hydrogeological model of a fracture-diffuse flow karst groundwater aquifer was proposed. The proportion of glacier melt water infiltrating into the karst aquifer was estimated by using the karst spring as a natural pluviometer, and with stable isotope analysis. Results show that (1) the JDSM karst aquifer is a diffuse flow system; (2) it has a number of discharge areas, and the Jinsha River is the karst drainage base level; (3) the proportion of the glacier melt water penetrating the karst aquifer is 29%; and (4) the karst-related carbon sink is 26.67 ± 3.44 t km-2 a-1 (as CO2), which is lower than that in non-glacierized karst aquifers but over ten times larger than the carbon sink flux from silicate weathering in non-karst areas, showing the control of both climate and lithology on the rock weathering-related carbon sink and the significance of carbonate weathering in the global carbon cycle.

  10. DS926 Digital surfaces and thicknesses of selected hydrogeologic units of the Floridan aquifer system in Florida and parts of Georgia, Alabama, and South Carolina -- Area where upper confining unit is thin or absent beneath the surficial aquifer

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Digital surfaces and thicknesses of selected hydrogeologic units of the Floridan aquifer system were developed to define an updated hydrogeologic framework as part...

  11. Geostatistical Borehole Image-Based Mapping of Karst-Carbonate Aquifer Pores.

    Science.gov (United States)

    Sukop, Michael C; Cunningham, Kevin J

    2016-03-01

    Quantification of the character and spatial distribution of porosity in carbonate aquifers is important as input into computer models used in the calculation of intrinsic permeability and for next-generation, high-resolution groundwater flow simulations. Digital, optical, borehole-wall image data from three closely spaced boreholes in the karst-carbonate Biscayne aquifer in southeastern Florida are used in geostatistical experiments to assess the capabilities of various methods to create realistic two-dimensional models of vuggy megaporosity and matrix-porosity distribution in the limestone that composes the aquifer. When the borehole image data alone were used as the model training image, multiple-point geostatistics failed to detect the known spatial autocorrelation of vuggy megaporosity and matrix porosity among the three boreholes, which were only 10 m apart. Variogram analysis and subsequent Gaussian simulation produced results that showed a realistic conceptualization of horizontal continuity of strata dominated by vuggy megaporosity and matrix porosity among the three boreholes. PMID:26174850

  12. Uncertainty assessment of carbon dioxide storage capacity evaluation in deep saline aquifer:a case study in Songliao Basin, China

    Science.gov (United States)

    Liu, Y.; Yang, X.

    2012-12-01

    Carbon dioxide Capture and Storage techniques (CCS) are one of the effective measures for reduction Carbon dioxide emissions to the atmosphere to mitigate the global warming. Among the Carbon dioxide geological storage options, deep saline aquifers offer the largest storage potential and are widely distributed throughout the Earth. Implementation of carbon dioxide capture and geological storage to reduce greenhouse gas emissions requires carbon dioxide storage capacity in deep saline aquifers. The storage capacity estimation depends on the storage trapping mechanisms and the availability, resolution and certainty of data. There are five different types of trapping mechanisms in deep saline aquifers namely structural and stratigraphic trapping, residual gas trapping, solubility trapping, mineral trapping and hydrodynamic trapping in which storage capacity by solubility trapping is the largest. The carbon dioxide storage capacities in deep saline aquifer can be evaluated by the method recommended by Carbon Sequestration Leadership Forum (CSLF), which mainly depends on the area of study area, thickness and porosity of sandstone, density and carbon dioxide content (mass fraction) in formation water at initial and saturated state. Hydrogeological parameters in aquifer are uncertainty because of uncertainty of measurement and the spatial variety, which leads evaluation uncertainty of carbon dioxide storage capacity. In this paper, acceptance of evaluated carbon dioxide storage capacity in deep saline aquifer caused by hydrological parameters was discussed based on geostatistical methods and stochastic simulation. The stratum named Yaojialing group in the center depressed area of Songliao Basin was chosen as study area because of the rich data. The porosity of sandstone, thickness ration of sandstone to stratum and the total dissolved solid in formation water were regarded as the main source of the uncertainty of carbon dioxide storage capacity evaluation in deep saline

  13. Groundwater salinization processes and reversibility of seawater intrusion in coastal carbonate aquifers

    Science.gov (United States)

    Han, Dongmei; Post, Vincent E. A.; Song, Xianfang

    2015-12-01

    Seawater intrusion (SWI) has led to salinization of fresh groundwater reserves in coastal areas worldwide and has forced the closure of water supply wells. There is a paucity of well-documented studies that report on the reversal of SWI after the closure of a well field. This study presents data from the coastal carbonate aquifer in northeast China, where large-scale extraction has ceased since 2001 after salinization of the main well field. The physical flow and concomitant hydrogeochemical processes were investigated by analyzing water level and geochemical data, including major ion chemistry and stable water isotope data. Seasonal water table and salinity fluctuations, as well as changes of δ2H-δ18O values of groundwater between the wet and dry season, suggest local meteoric recharge with a pronounced seasonal regime. Historical monitoring testifies of the reversibility of SWI in the carbonate aquifer, as evidenced by a decrease of the Cl- concentrations in groundwater following restrictions on groundwater abstraction. This is attributed to the rapid flushing in this system where flow occurs preferentially along karst conduits, fractures and fault zones. The partially positive correlation between δ18O values and TDS concentrations of groundwater, as well as high NO3- concentrations (>39 mg/L), suggest that irrigation return flow is a significant recharge component. Therefore, the present-day elevated salinities are more likely due to agricultural activities rather than SWI. Nevertheless, seawater mixing with fresh groundwater cannot be ruled out in particular where formerly intruded seawater may still reside in immobile zones of the carbonate aquifer. The massive expansion of fish farming in seawater ponds in the coastal zone poses a new risk of salinization. Cation exchange, carbonate dissolution, and fertilizer application are the dominant processes further modifying the groundwater composition, which is investigated quantitatively using hydrogeochemical

  14. Variations in hydraulic conductivity with scale of measurement during aquifer tests in heterogeneous, porous carbonate rocks

    Science.gov (United States)

    Schulze-Makuch, Dirk; Cherkauer, Douglas S.

    Previous studies have shown that hydraulic conductivity of an aquifer seems to increase as the portion of the aquifer tested increases. To date, such studies have all relied on different methods to determine hydraulic conductivity at each scale of interest, which raises the possibility that the observed increase in hydraulic conductivity is due to the measurement method, not to the scale. This study analyzes hydraulic conductivity with respect to scale during individual aquifer tests in porous, heterogeneous carbonate rocks in southeastern Wisconsin, USA. Results from this study indicate that hydraulic conductivity generally increases during an individual test as the volume of aquifer impacted increases, and the rate of this increase is the same as the rate of increase determined by using different measurement methods. Thus, scale dependence of hydraulic conductivity during single tests does not depend on the method of measurement. This conclusion is supported by 22 of 26 aquifer tests conducted in porous-flow-dominated carbonate units within the aquifer. Instead, scale dependency is probably caused by heterogeneities within the aquifer, a conclusion supported by digital simulation. All of the observed types of hydraulic-conductivity variations with scale during individual aquifer tests can be explained by a conceptual model of a simple heterogeneous aquifer composed of high-conductivity zones within a low-conductivity matrix. Résumé Certaines études ont montré que la conductivité hydraulique d'un aquifère semble augmenter en même temps que la partie testée de l'aquifère s'étend. Jusqu'à présent, ces études ont toutes reposé sur des méthodes de détermination de la conductivité hydraulique différentes pour chaque niveau d'échelle, ce qui a conduit à penser que l'augmentation observée de la conductivité hydraulique pouvait être due aux méthodes de mesure et non à l'effet d'échelle. Cette étude analyse la conductivité hydraulique par

  15. Geochemical Impacts of Leaking CO2 from Subsurface Storage Reservoirs to an Unconfined Oxidizing Carbonate Aquifer

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guohui; Qafoku, Nikolla; Lawter, Amanda R.; Bowden, Mark E.; Harvey, Omar; Sullivan, E. C.; Brown, Christopher F.

    2015-07-15

    A series of batch and column experiments combined with solid phase characterization studies (i.e., quantitative x-ray diffraction and wet chemical extractions) were conducted to address a variety of scientific issues and evaluate the impacts of the potential leakage of carbon dioxide (CO2) from deep subsurface storage reservoirs. The main objective was to gain an understanding of how CO2 gas influences: 1) the aqueous phase pH; and 2) mobilization of major, minor, and trace elements from minerals present in an aquifer overlying potential CO2 sequestration subsurface repositories. Rocks and slightly weathered rocks representative of an unconfined, oxidizing carbonate aquifer within the continental US, i.e., the Edwards aquifer in Texas, were used in these studies. These materials were exposed to a CO2 gas stream or were leached with a CO2-saturated influent solution to simulate different CO2 gas leakage scenarios, and changes in aqueous phase pH and chemical composition were measured in the liquid samples collected at pre-determined experimental times (batch experiments) or continuously (column experiments). The results from the strong acid extraction tests confirmed that in addition to the usual elements present in most soils, rocks, and sediments, the Edward aquifer samples contain As, Cd, Pb, Cu, and occasionally Zn, which may potentially be mobilized from the solid to the aqueous phase during or after exposure to CO2. The results from the batch and column experiments confirmed the release of major chemical elements into the contacting aqueous phase (such as Ca, Mg, Ba, Sr, Si, Na, and K); the mobilization and possible rapid immobilization of minor elements (such as Fe, Al, and Mn), which are able to form highly reactive secondary phases; and sporadic mobilization of only low concentrations of trace elements (such as As, Cd, Pb, Cu, Zn, Mo, etc.). The results from this experimental research effort will help in developing a systematic understanding of how CO2

  16. Evolution of groundwater in a carbonate-bearing glacigenic aquifer, SW Finland: hydrochemical and isotopic evidence

    International Nuclear Information System (INIS)

    Full text: Unusually high pH values, up to 9.5, are encountered in the glacigenic Virttaankangas aquifer, southwest Finland. This is in strong contrast to the pH values normally recorded in Finnish shallow groundwaters, averaging 6.4. Chemical and isotopic (18O, D, 13C, T, 14C) compositional parameters were determined in order to evaluate the origin of the unusual chemical composition of the groundwater at Virttaankangas. In addition, the mineralogical composition of the aquifer material was examined. The Virttaankangas groundwater formation has been studied extensively, because it has been selected as the site of an artificial recharge plant, intended to start operation in 2007. The project is the largest artificial groundwater scheme in northern Europe. The high pH values have been suggested to be related to the presence of carbonate minerals in glaciogenic sediments. However, only erratic carbonate boulders have been observed, and no outcrops containing carbonate rock have been discovered at the site. The Virttaankangas aquifer is located in a NW-SE esker chain composed of Quartenary deposits. In the studied area of 54 km2 the total thickness of sediments above the bedrock varies from 30 to 90 m. The formation of the stratigraphical succession occurred in three stages. The core of the esker with coarse sand and gravel was deposited in the first stage. The second stage consists of an interlobate glaciofluvial ridge and fine-grained glaciolacustrine deposits. Locally the glaciolacustrine deposits form a confining interlayer holding a perched water table. The uppermost, third stage, is composed of sorted littoral sands formed during the regression of the former Baltic Sea. Accordingly, three distinct hydrogeological units can be identified: 1) an unconfined, highly conductive aquifer in the core of the esker, 2) a semi-confined aquifer, with fairly low hydraulic conductivity underlying the confining interlayer, and 3) an unconfined perched aquifer in the littoral

  17. Evolution of groundwater in a carbonate-bearing glacigenic aquifer, SW Finland: Hydrochemical and isotopic evidence

    International Nuclear Information System (INIS)

    Full text: Unusually high pH values, up to 9.5, are encountered in the glacigenic Virttaankangas aquifer, southwest Finland. This is in strong contrast to the pH values normally recorded in Finnish shallow groundwaters, averaging 6.4. Chemical and isotopic (18O, D, 13C, T, 14C) compositional parameters were determined in order to evaluate the origin of the unusual chemical composition of the groundwater at Virttaankangas. In addition, the mineralogical composition of the aquifer material was examined. The Virttaankangas groundwater formation has been studied extensively, because it has been selected as the site of an artificial recharge plant, intended to start operation in 2007. The project is the largest artificial groundwater scheme in northern Europe. The high pH values have been suggested to be related to the presence of carbonate minerals in glaciogenic sediments. However, only erratic carbonate boulders have been observed, and no outcrops containing carbonate rock have been discovered at the site. The Virttaankangas aquifer is located in a NW-SE esker chain composed of Quartenary deposits. In the studied area of 54 km2 the total thickness of sediments above the bedrock varies from 30 to 90 m. The formation of the stratigraphical succession occurred in three stages. The core of the esker with coarse sand and gravel was deposited in the first stage. The second stage consists of an interlobate glaciofluvial ridge and fine-grained glaciolacustrine deposits. Locally the glaciolacustrine deposits form a confining interlayer holding a perched water table. The uppermost, third stage, is composed of sorted littoral sands formed during the regression of the former Baltic Sea. Accordingly, three distinct hydrogeological units can be identified: 1) an unconfined, highly conductive aquifer in the core of the esker; 2) a semi-confined aquifer, with fairly low hydraulic conductivity underlying the confining interlayer; and 3) an unconfined perched aquifer in the littoral

  18. Electrical Resistivity Tomography (ERT) Applied to Karst Carbonate Aquifers: Case Study from Amdoun, Northwestern Tunisia

    Science.gov (United States)

    Redhaounia, Belgacem; Ilondo, Batobo Ountsche; Gabtni, Hakim; Sami, Khomsi; Bédir, Mourad

    2016-04-01

    The Amdoun region is characterized by a high degree of karstification due to the climate impact (±1500 mm year-1) and the development of fracture network. Survey using electrical resistivity tomography (ERT) is deployed to provide a cost-effective characterization of the subsurface karst environments. A total of seven ERT profiles with lengths of 315 m were evaluated at the Béja governorate (NW Tunisia). The area represents a small syncline of Boudabbous limestone rocks (Lower Eocene), which is covered by a thin layer of clay. In this study, an ERT survey was conducted to examine the spatial distribution and shape of underground cavities in the karst area in Jebel Sabah anticline and Aïn Sallem-Zahret Medien syncline. In this study, geological, hydro-geological and electrical resistivity tomography (ERT) methods were applied to determine the geometry of the perched aquifer in the Amdoun region (NW Tunisia). The area is characterized by fractured and karstic limestone aquifer of Late Cretaceous (Abiod Fm.) and Lower Eocene (Boudabbous Fm.). The aquifers have a karstic functioning and drain aquifers of economical interest, despite some wells exploiting them. Seven resistivity profiles were conducted along the survey area at three sites. The orientation, extension and the degree of inclination of those profiles are shown in the location map. The correct resistivity data were interpreted using Earth Imager 2D software. The results of the interpreted geo-electrical sections showed that the resistivity of the carbonate aquifer varied between 2.5 to over 5794 Ωm. The thickness of the perched aquifer ranged from 15 to 50 m, while its depth from the surface lies between 10 and 60 m. The ERT not only provided precise near surface information, but was also very useful for establishing the 3D geometry and the position of several potential cavities and karts. The results show the presence of small to large isolated cavities at various depths. The low resistivity of cavities

  19. Optimization of Geological Environments for Carbon Dioxide Disposan in Saline Aquifers in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Hovorka, Susan

    1999-02-01

    Recent research and applications have demonstrated technologically feasible methods, defined costs, and modeled processes needed to sequester carbon dioxide (CO{sub 2}) in saline-water-bearing formations (aquifers). One of the simplifying assumptions used in previous modeling efforts is the effect of real stratigraphic complexity on transport and trapping in saline aquifers. In this study we have developed and applied criteria for characterizing saline aquifers for very long-term sequestration of CO{sub 2}. The purpose of this pilot study is to demonstrate a methodology for optimizing matches between CO{sub 2} sources and nearby saline formations that can be used for sequestration. This project identified 14 geologic properties used to prospect for optimal locations for CO{sub 2} sequestration in saline-water-bearing formations. For this demonstration, we digitized maps showing properties of saline formations and used analytical tools in a geographic information system (GIS) to extract areas that meet variably specified prototype criteria for CO{sub 2} sequestration sites. Through geologic models, realistic aquifer properties such as discontinuous sand-body geometry are determined and can be used to add realistic hydrologic properties to future simulations. This approach facilitates refining the search for a best-fit saline host formation as our understanding of the most effective ways to implement sequestration proceeds. Formations where there has been significant drilling for oil and gas resources as well as extensive characterization of formations for deep-well injection and waste disposal sites can be described in detail. Information to describe formation properties can be inferred from poorly known saline formations using geologic models in a play approach. Resulting data sets are less detailed than in well-described examples but serve as an effective screening tool to identify prospects for more detailed work.

  20. Fresh Water Generation from Aquifer-Pressured Carbon Storage: Interim Progress Report

    International Nuclear Information System (INIS)

    This project is establishing the potential for using brine pressurized by Carbon Capture and Storage (CCS) operations in saline formations as the feedstock for desalination and water treatment technologies including nanofiltration (NF) and reverse osmosis (RO). The aquifer pressure resulting from the energy required to inject the carbon dioxide provides all or part of the inlet pressure for the desalination system. Residual brine would be reinjected into the formation at net volume reduction. This process provides additional storage space (capacity) in the aquifer, reduces operational risks by relieving overpressure in the aquifer, and provides a source of low-cost fresh water to offset costs or operational water needs. Computer modeling and laboratory-scale experimentation are being used to examine mineral scaling and osmotic pressure limitations for brines typical of CCS sites. Computer modeling is being used to evaluate processes in the aquifer, including the evolution of the pressure field. This progress report deals mainly with our geochemical modeling of high-salinity brines and covers the first six months of project execution (September, 2008 to March, 2009). Costs and implementation results will be presented in the annual report. The brines typical of sequestration sites can be several times more concentrated than seawater, requiring specialized modeling codes typical of those developed for nuclear waste disposal calculations. The osmotic pressure developed as the brines are concentrated is of particular concern, as are precipitates that can cause fouling of reverse osmosis membranes and other types of membranes (e.g., NF). We have now completed the development associated with tasks (1) and (2) of the work plan. We now have a contract with Perlorica, Inc., to provide support to the cost analysis and nanofiltration evaluation. We have also conducted several preliminary analyses of the pressure effect in the reservoir in order to confirm that reservoir

  1. Compound-specific carbon isotopic fractionation during transport of phthalate esters in sandy aquifer.

    Science.gov (United States)

    Liu, Hui; Li, YanXi; He, Xi; Sissou, Zakari; Tong, Lei; Yarnes, Chris; Huang, Xianyu

    2016-02-01

    The present paper aims to evaluate the carbon isotopic fractionation of phthalate esters (PAEs) during transport in an sandy aquifer. Breakthrough curves of di-methyl phthalate (DMP), di-ethyl phthalate (DEP), and di-n-butyl phthalate (DBP) in mixed solution were determined by miscible displacement experiment, and simulated using HYDRUS-1D software. The stable carbon isotopes (δ(13)C) of 3 PAEs in effluent were analyzed at different times. Results showed that, in the transport process in sandy sediment, PAEs are mainly trapped into the pore space instead of being adsorbed on the surface of particles. At the initial stage of transport, PAEs with lighter carbon tend to run faster in the sandy sediment, and PAEs with heavier carbon run after. However, there is no priority for the transport of PAEs with different carbon isotopes at Stage Ⅱ with mainly time-limited sorption. So the transport-based isotope fractionation occurs in the front area of contaminant plume. This effect may be relevant for interpreting carbon isotope signatures in the real contaminant site. PMID:26539707

  2. Implementation of a 3d numerical model of a folded multilayer carbonate aquifer

    Science.gov (United States)

    Di Salvo, Cristina; Guyennon, Nicolas; Romano, Emanuele; Bruna Petrangeli, Anna; Preziosi, Elisabetta

    2016-04-01

    The main objective of this research is to present a case study of the numerical model implementation of a complex carbonate, structurally folded aquifer, with a finite difference, porous equivalent model. The case study aquifer (which extends over 235 km2 in the Apennine chain, Central Italy) provides a long term average of 3.5 m3/s of good quality groundwater to the surface river network, sustaining the minimum vital flow, and it is planned to be exploited in the next years for public water supply. In the downstream part of the river in the study area, a "Site of Community Importance" include the Nera River for its valuable aquatic fauna. However, the possible negative effects of the foreseen exploitation on groundwater dependent ecosystems are a great concern and model grounded scenarios are needed. This multilayer aquifer was conceptualized as five hydrostratigraphic units: three main aquifers (the uppermost unconfined, the central and the deepest partly confined), are separated by two locally discontinuous aquitards. The Nera river cuts through the two upper aquifers and acts as the main natural sink for groundwater. An equivalent porous medium approach was chosen. The complex tectonic structure of the aquifer requires several steps in defining the conceptual model; the presence of strongly dipping layers with very heterogeneous hydraulic conductivity, results in different thicknesses of saturated portions. Aquifers can have both unconfined or confined zones; drying and rewetting must be allowed when considering recharge/discharge cycles. All these characteristics can be included in the conceptual and numerical model; however, being the number of flow and head target scarce, the over-parametrization of the model must be avoided. Following the principle of parsimony, three steady state numerical models were developed, starting from a simple model, and then adding complexity: 2D (single layer), QUASI -3D (with leackage term simulating flow through aquitards) and

  3. Zinc isotope evidence for a large-scale carbonated mantle beneath eastern China

    Science.gov (United States)

    Liu, Sheng-Ao; Wang, Ze-Zhou; Li, Shu-Guang; Huang, Jian; Yang, Wei

    2016-06-01

    A large set of zinc (Zn) stable isotope data for continental basalts from eastern China were reported to investigate the application of Zn isotopes as a new tracer of deep carbonate cycling. All of the basalts with ages of 120 Ma basalts from eastern China (0.27 ± 0.06‰; 2sd). Given that Zn isotope fractionation during magmatic differentiation is limited (≤0.1‰), the elevated δ66Zn values reflect the involvement of isotopically heavy crustal materials (e.g., carbonates with an average δ66Zn of ∼0.91‰) in the mantle sources. SiO2 contents of the cycling in the Earth's mantle.

  4. Density and Stability of Soil Organic Carbon beneath Impervious Surfaces in Urban Areas

    OpenAIRE

    Wei, Zongqiang; WU, SHAOHUA; Yan, Xiao; Zhou, Shenglu

    2014-01-01

    Installation of impervious surfaces in urban areas has attracted increasing attention due to its potential hazard to urban ecosystems. Urban soils are suggested to have robust carbon (C) sequestration capacity; however, the C stocks and dynamics in the soils covered by impervious surfaces that dominate urban areas are still not well characterized. We compared soil organic C (SOC) densities and their stabilities under impervious surface, determined by a 28-d incubation experiment, with those i...

  5. Growth of crystalline silicon nanowires on nickel-coated silicon wafer beneath sputtered amorphous carbon

    International Nuclear Information System (INIS)

    Growth of crystalline silicon nanowire of controllable diameter directly from Si wafer opens up another avenue for its application in solar cells and optical sensing. Crystalline Si nanowire can be directly grown from Si wafer upon rapid thermal annealing in the presence of the catalyst such as nickel (Ni). However, the accompanying oxidation immediately changes the crystalline Si nanowire to amorphous SiOx. In this study, amorphous carbon layer was sputtered to on top of the catalyst Ni layer to retard the oxidation. Scanning electron microscope, transmission electron microscope, Raman spectroscopy and X-ray photoelectron spectroscopy were employed to characterize the wires and oxidation process. A model was developed to explain the growth and oxidation process of the crystalline Si nanowire. - Highlights: ► Carbon was sputtered on nickel to retard the oxidation of silicon nanowires. ► Silicon core was controlled by carbon layer thickness and annealing duration. ► An oxidation-accompanying solid–liquid–solid growth mechanism was developed

  6. The addition of organic carbon and nitrate affects reactive transport of heavy metals in sandy aquifers

    KAUST Repository

    Satyawali, Yamini

    2011-04-01

    Organic carbon introduction in the soil to initiate remedial measures, nitrate infiltration due to agricultural practices or sulphate intrusion owing to industrial usage can influence the redox conditions and pH, thus affecting the mobility of heavy metals in soil and groundwater. This study reports the fate of Zn and Cd in sandy aquifers under a variety of plausible in-situ redox conditions that were induced by introduction of carbon and various electron acceptors in column experiments. Up to 100% Zn and Cd removal (from the liquid phase) was observed in all the four columns, however the mechanisms were different. Metal removal in column K1 (containing sulphate), was attributed to biological sulphate reduction and subsequent metal precipitation (as sulphides). In the presence of both nitrate and sulphate (K2), the former dominated the process, precipitating the heavy metals as hydroxides and/or carbonates. In the presence of sulphate, nitrate and supplemental iron (Fe(OH)3) (K3), metal removal was also due to precipitation as hydroxides and/or carbonates. In abiotic column, K4, (with supplemental iron (Fe(OH)3), but no nitrate), cation exchange with soil led to metal removal. The results obtained were modeled using the reactive transport model PHREEQC-2 to elucidate governing processes and to evaluate scenarios of organic carbon, sulphate and nitrate inputs. © 2010 Elsevier B.V.

  7. Quantifying and timing of long-term carbonate mobilisation in a limestone aquifer

    Science.gov (United States)

    Kirstein, J.; Gaupp, R.

    2012-04-01

    . The goal is to deliver basic data for a quantification of carbonate export and carbon dioxide consumption within the Thuringian basin Muschelkalk aquifer during the Late Quaternary.

  8. Influence of soil on groundwater geochemistry in a carbonate aquifer, southern Italy

    Directory of Open Access Journals (Sweden)

    Tiziano Boschetti

    2014-01-01

    Full Text Available The role of soil compositions in influencing groundwater geochemistry in carbonate aquifers is still little known. Nothing is known regarding the influence of pyroclastic soils (andisol within the carbonate Apennines in central-southern Italy, despite their wide distribution. In this study we analyze some physical and chemical properties of pyroclastic soil at the Acqua dei Faggi experimental site (southern Italy, to assess its influence on groundwater geochemistry. Chemical analyses were carried out on saturated paste extracts and a physical analogue model was developed through two column experiments. Physico-chemical properties of rainwater and spring water, and some microbiological features of the soil medium were also taken into consideration. The studied soil has a great influence in modifying rainwater chemistry during percolation. About the 50% of HCO3- and Ca2+ in spring water is due to interaction between percolation water and soil medium, and equilibrium with calcite is reached at this stage. The Na+/K+ ratio is buffered by clay minerals in the soil by primary silicates in the pyroclastic cover and then buffered. Cl- and SO42- concentrations in spring water are very close to that of soil infiltration water during short-term interaction with soil, but a decline is showed during long-term cause to the anions adsorption effect in the andisol. Chemical and microbiological investigations show the existence of a soil microbial community that allows denitrification and nitrate reduction. Infiltration processes cause anoxic conditions within the soil medium, therefore the absence of NH4+ in spring water throughout the observation period should be due to anammox processes. These findings suggest that hydrochemistry and spring chemographs may be significantly influenced by several factors, such as relationships between soil and rainwater, vegetation, and microbial communities, which are not necessarily correlated with lithological and structural

  9. Hydrostratigraphy of the Snake River Plain aquifer beneath the Radioactive Waste Management Complex at the Idaho National Engineering Laboratory: A preliminary report

    International Nuclear Information System (INIS)

    Geophysical logs for 6 wells which penetrate the Snake River Plain aquifer at the Radioactive Waste Management Complex (RWMC) were analyzed for preliminary information on the hydrostratigraphy. Using stratigraphic correlation of flow groups worked out by Anderson and Lewis (1989), and by Anderson, as well as gamma signatures of flows within these flow groups, correlation of individual flows is attempted. Within these flows, probable permeable zones, suggested by density and caliper logs, are identified, and zones of hydraulic connection are tentatively correlated. In order to understand the response of density and neutron logs in basalt, the geological characteristics are quantified for the 150-ft section of the well C1A core, from depth 550 to 710 ft. 9 refs., 4 figs

  10. Desorption Behavior of Carbon Tetrachloride and Chloroform in contaminated Low Organic Carbon Aquifer Sediments

    Energy Technology Data Exchange (ETDEWEB)

    Riley, Robert G.; Szecsody, Jim E.; Sklarew, Debbie S.; Mitroshkov, Alexandre V.; Gent, Philip M.; Brown, Christopher F.; Thompson, Christopher J.

    2010-05-01

    Experimental determination of contaminant behavior in deep aquifer sediments is challenging because of the cost and difficulty associated with sample collection. On the other hand, parameter values important to contaminant transport (e.g., distribution coefficient) derived from such sediments may be more accurate than those determined by estimation methods. Furthermore, experiments performed with sediments where the contaminants have been in contact with the sediments for decades are more likely to reveal kinetic controls on contaminant transport not as readily revealed in short contact time experiments. We report the first measurements of CCl4 and CHCl3 distribution coefficients in contaminated Hanford sediments with varying physical/chemical properties.

  11. Hydrochemistry of surface water and groundwater from a fractured carbonate aquifer in the Helwan area, Egypt

    Indian Academy of Sciences (India)

    Fathy A Abdalla; Traugott Scheytt

    2012-02-01

    Groundwater is an important water resource in the Helwan area, not only for drinking and agricultural purposes, but also because several famous mineral springs have their origin in the fractured carbonate aquifer of the region. The area is heavily populated with a high density of industrial activities which may pose a risk for groundwater and surface water resources. The groundwater and surface water quality was investigated as a basis for more future investigations. The results revealed highly variable water hydrochemistry. High values of chloride, sulphate, hardness and significant mineralization were detected under the industrial and high-density urban areas. High nitrate contents in the groundwater recorded in the southern part of the study area are probably due to irrigation and sewage infiltrations from the sewage treatment station. The presence of shale and marl intercalation within the fissured and cavernous limestone aquifer promotes the exchange reactions and dissolution processes. The groundwater type is sodium, sulphate, chloride reflecting more mineralized than surface water. The results also showed that water in the study area (except the Nile water) is unsuitable for drinking purposes, but it can be used for irrigation and industrial purposes with some restrictions.

  12. Hydrochemical changes due to intensive use of groundwater in the carbonate aquifers of Sierra de Estepa (Seville, Southern Spain)

    Science.gov (United States)

    Martos-Rosillo, S.; Moral, F.

    2015-09-01

    The carbonate aquifers of Sierra de Estepa, situated in southern Spain, are undergoing intensive groundwater exploitation. Consequently, the volume of pumping surpasses the average recharge for periods of several consecutive years. Under such conditions, nearby springs have either dried up or only function during short time periods, after very rainy episodes followed by long droughts. During the brief periods when the springs are active, their water and the water extracted by pumping are calcium bicarbonates, with a spatial-temporal variability of their physico-chemical characteristics that is mainly conditioned by the degree of functional karstification of each system. When the springs are inactive, the pumping water gradually increases in salinity and becomes HCO3ClCaNa, ClHCO3NaCa and ClNa. Under the new conditions caused by so much pumping, the main factors determining the hydrochemical changes are the mixing of waters and the subsequent reactions of dissolution-precipitation between (1) the recharge coming from rainwater, (2) the hypersaline inputs from the clay-evaporite aquitards situated on the edges and at the base of the aquifer, and (3) the water stored in each aquifer. The hydrochemical information acquired allowed us to characterize and model the groundwater of these aquifers, to study the causes of its great spatial and temporal variability, and explain the influence of exploitation. This research shows that making sustainable use of water resources associated with carbonate aquifers calls for sound knowledge of the relationship between the aquifer and other bodies of groundwater or surface water, the hydrochemical quality of these possible inputs, and the vulnerability of the aquifer to exploitation, which in turn is conditioned by the ratio between water reserves and recharge.

  13. Carbon Sequestration in Saline Aquifers: Modeling Diffusive and Convective Transport Of a Carbon-­Dioxide Cap

    KAUST Repository

    Allen, Rebecca

    2011-05-01

    An increase in the earth’s surface temperature has been directly linked to the rise of carbon dioxide (CO2) levels In the atmosphere and an enhanced greenhouse effect. CO2 sequestration is one of the proposed mitigation Strategies in the effort to reduce atmospheric CO2 concentrations. Globally speaking, saline aquifers provide an adequate storage capacity for the world’s carbon emissions, and CO2 sequestration projects are currently underway in countries such as Norway, Germany, Japan, USA, and others. Numerical simulators serve as predictive tools for CO2 storage, yet must model fluid transport behavior while coupling different transport processes together accurately. With regards to CO2 sequestration, an extensive amount of research has been done on the diffusive-convective transport that occurs under a cap of CO2-saturated fluid, which results after CO2 is injected into an aquifer and spreads laterally under an area of low permeability. The diffusive-convective modeling reveals an enhanced storage capacity in saline aquifers, due to the density increase between pure fluid and CO2‐saturated fluid. This work presents the transport modeling equations that are used for diffusive- convective modeling. A cell-centered finite difference method is used, and simulations are run using MATLAB. Two cases are explored in order to compare the results from this work’s self-generated code with the results published in literature. Simulation results match relatively well, and the discrepancy for a delayed onset time of convective transport observed in this work is attributed to numerical artifacts. In fact, onset time in this work is directly attributed to the instability of the physical system: this instability arises from non-linear coupling of fluid flow, transport, and convection, but is triggered by numerical errors in these simulations. Results from this work enable the computation of a value for the numerical constant that appears in the onset time equation that

  14. Isotopes as Tracers of Water Origin in and Near a Regional Carbonate Aquifer: The Southern Sacramento Mountains, New Mexico

    Directory of Open Access Journals (Sweden)

    Christopher J. Eastoe

    2014-01-01

    Full Text Available High-elevation groundwater sampled in 2003 in the Sacramento Mountains defines a line resembling an evaporation trend in δD-δ18O space. The trend results from recharge of winter precipitation into fractured limestone, with evaporation prior to recharge in broad mountain valleys. The same trend occurs in basin groundwater east and west of the range, indicating the high Sacramento Mountains as the principal regional water source, either direct from the limestone aquifers or from mountain-derived surface water. Tritium and carbon-14 indicate bulk residence times of a few decades in the high Sacramento Mountains and at Alamogordo, and of thousands of years south of Alamogordo and in the artesian aquifer near Artesia. Stable O, H isotope data fail to demonstrate the presence of Sacramento Mountains water in a saline aquifer of the Hueco Bolson (Texas.

  15. Coupled numerical simulations of CO2 injection into the carbonate aquifer of the Upper Muschelkalk, N-Switzerland

    Science.gov (United States)

    Alt-Epping, P.; Almqvist, B. S. G.; Diamond, L. W.

    2012-04-01

    The Triassic Trigodonus Dolomite unit of Upper Muschelkalk, a saline carbonate-hosted aquifer in Northerm Switzerland, is considered a possible target for sequestering CO2. The porosity of the aquifer ranges from 4-25 %. The porosity can be divided into macropores (mm to cm scale) and micropores (µm to nm scale). Intermittent bedding-parallel layers of macroscopic pores (cm scale) are readily visible, and originate from dissolution of anhydrite nodules and bivalve shells. The porosity of the Muschelkalk therefore exhibits a moderate layered anisotropy. Lab measurements indicate correlated permeabilities with values of 5.1 to 2.7e-18 m2 for low porosity samples to larger than 1e-15 m2 for samples with a large fraction of macropores. The Upper Muschekalk is overlain by the Gipskeuper, an anhydrite-bearing clay-rich rock of low porosity and permeability. The Gipskeuper constitutes a hydraulic barrier to the rising CO2 plume. We use fully coupled reactive transport simulations to assess the implications of injecting CO2 into the Trigodonus Dolomite of the Muschelkalk aquifer. We track the movement of the plume and evaluate the efficiency of physical and chemical trapping mechanisms. Computations show that mineral trapping in the Muschelkalk aquifer is not effective. The global CO2 mass balance indicates the release of additional CO2 due to carbonate dissolution. However, while during and shortly after injection the dissolution of carbonate minerals dominates, after all free CO2 has dissolved into the brine, a rebound in pH at the injection site leads to carbonate re-precipitation. Diffusive influx of HCO3- and H+ from the Muschelkalk aquifer into the Gipskeuper dominates the alteration reactions in the lower part of the Gipskeuper. Clay minerals such as illite dissolve under acidic conditions and the release of cations causes carbonate minerals to precipitate. This in turn reduces the pore-space, enhancing the sealing capacity of the lower Gipskeuper. Thus although

  16. 1:1,000,000-scale hydrographic areas and flow systems for the Great Basin carbonate and alluvial aquifer system of Nevada, Utah, and parts of adjacent states

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset was created in support of a U.S. Geological Survey (USGS) study focusing on groundwater resources in the Great Basin carbonate and alluvial aquifer...

  17. 1:1,000,000-scale potentiometric contours and control points for the Great Basin carbonate and alluvial aquifer system of Nevada, Utah, and parts of adjacent states

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset was created in support of a U.S. Geological Survey (USGS) study focusing on groundwater resources in the Great Basin carbonate and alluvial aquifer...

  18. Selected Basin Characterization Model Parameters for the Great Basin Carbonate and Alluvial Aquifer System of Nevada, Utah, and Parts of Adjacent States

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset was created in support of a study focusing on ground-water resources in the Great Basin carbonate and alluvial aquifer system (GBCAAS). The GBCAAS is a...

  19. Evapotranspiration units in the Basin and Range carbonate-rock aquifer system, White Pine County, Nevada, and adjacent parts of Nevada and Utah

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Accurate estimates of ground-water discharge are crucial in the development of a water budget for the Basin and Range Carbonate-rock Aquifer System (BARCAS) study...

  20. Three-dimensional hydrogeologic framework for the Great Basin carbonate and alluvial aquifer system of Nevada, Utah, and parts of adjacent states

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset was created in support of a study focusing on groundwater resources in the Great Basin carbonate and alluvial aquifer system (GBCAAS). The GBCAAS is a...

  1. Rapid carbon turnover beneath shrub and tree vegetation is associated with low soil carbon stocks at a subarctic treeline.

    Science.gov (United States)

    Parker, Thomas C; Subke, Jens-Arne; Wookey, Philip A

    2015-05-01

    Climate warming at high northern latitudes has caused substantial increases in plant productivity of tundra vegetation and an expansion of the range of deciduous shrub species. However significant the increase in carbon (C) contained within above-ground shrub biomass, it is modest in comparison with the amount of C stored in the soil in tundra ecosystems. Here, we use a 'space-for-time' approach to test the hypothesis that a shift from lower-productivity tundra heath to higher-productivity deciduous shrub vegetation in the sub-Arctic may lead to a loss of soil C that out-weighs the increase in above-ground shrub biomass. We further hypothesize that a shift from ericoid to ectomycorrhizal systems coincident with this vegetation change provides a mechanism for the loss of soil C. We sampled soil C stocks, soil surface CO2 flux rates and fungal growth rates along replicated natural transitions from birch forest (Betula pubescens), through deciduous shrub tundra (Betula nana) to tundra heaths (Empetrum nigrum) near Abisko, Swedish Lapland. We demonstrate that organic horizon soil organic C (SOCorg ) is significantly lower at shrub (2.98 ± 0.48 kg m(-2) ) and forest (2.04 ± 0.25 kg m(-2) ) plots than at heath plots (7.03 ± 0.79 kg m(-2) ). Shrub vegetation had the highest respiration rates, suggesting that despite higher rates of C assimilation, C turnover was also very high and less C is sequestered in the ecosystem. Growth rates of fungal hyphae increased across the transition from heath to shrub, suggesting that the action of ectomycorrhizal symbionts in the scavenging of organically bound nutrients is an important pathway by which soil C is made available to microbial degradation. The expansion of deciduous shrubs onto potentially vulnerable arctic soils with large stores of C could therefore represent a significant positive feedback to the climate system. PMID:25367088

  2. Geochemical modeling of iron, sulfur, oxygen and carbon in a coastal plain aquifer

    Science.gov (United States)

    Brown, C.J.; Schoonen, M.A.A.; Candela, J.L.

    2000-01-01

    Fe(III) reduction in the Magothy aquifer of Long Island, NY, results in high dissolved-iron concentrations that degrade water quality. Geochemical modeling was used to constrain iron-related geochemical processes and redox zonation along a flow path. The observed increase in dissolved inorganic carbon is consistent with the oxidation of sedimentary organic matter coupled to the reduction of O2 and SO4/2- in the aerobic zone, and to the reduction of SO4/2- in the anaerobic zone; estimated rates of CO2 production through reduction of Fe(III) were relatively minor by comparison. The rates of CO2 production calculated from dissolved inorganic carbon mass transfer (2.55 x 10-4 to 48.6 x 10-4 mmol 1-1 yr-1) generally were comparable to the calculated rates of CO2 production by the combined reduction of O2, Fe(III) and SO4/2- (1.31 x 10-4 to 15 x 10-4 mmol 1-1 yr-1). The overall increase in SO4/2- concentrations along the flow path, together with the results of mass-balance calculations, and variations in ??34S values along the flow path indicate that SO4/2- loss through microbial reduction is exceeded by SO4/2- gain through diffusion from sediments and through the oxidation of FeS2. Geochemichal and microbial data on cores indicate that Fe(III) oxyhydroxide coatings on sediment grains in local, organic carbon- and SO4/2- -rich zones have localized SO4/2- -reducing zones in which the formation of iron disulfides been depleted by microbial reduction and resulted in decreases dissolved iron concentrations. These localized zones of SO4/2- reduction, which are important for assessing zones of low dissolved iron for water-supply development, could be overlooked by aquifer studies that rely only on groundwater data from well-water samples for geochemical modeling. (C) 2000 Elsevier Science B.V.Fe(III) reduction in the Magothy aquifer of Long Island, NY, results in high dissolved-iron concentrations that degrade water quality. Geochemical modeling was used to constrain iron

  3. Hydrochemical properties of deep carbonate aquifers in the SW German Molasse basin

    OpenAIRE

    Stober, I.; Bucher, K

    2015-01-01

    Background The Upper Jurassic (Malm) limestone and the Middle Triassic Muschelkalk limestone 18 are the major thermal aquifers in the southwest German alpine foreland. The aquifers 19 are of interest for production of geothermal energy and for balneological purposes. Methods Hydrochemical data from several hundred wells within two deep limestone aquifers in the Molasse basin of SW Germany have been compiled, examined, validated, and analyzed with the aim to characterize the fluids...

  4. Coupling fracture facies with in situ permeability measurements to generate stochastic simulations of tight carbonate aquifer properties: example from the Lower Cretaceous aquifer, Northern Provence, SE France

    Science.gov (United States)

    Bruna, Pierre-Olivier; Guglielmi, Yves; Viseur, Sophie; Lamarche, Juliette

    2015-04-01

    The relationships between fracture facies and permeability distribution have been explored using a well-constrained 3D implicit structural model of hemipelagic low porosity/low permeability carbonate from the Northern Provence region, SE France. Fracture and permeability facies were determined using an extensive dataset of 99 hydrogeological boreholes wells. Data processing was undertaken using a step-by-step approach, involving: i) identification of the fracture facies based on well logs detailing structure and stratigraphy ; ii) determination of permeability facies from the a priori correlation between the dimension of the hydraulic radius of influence (deduced from slug test analyses) and the type of reservoir heterogeneity (fissure, fracture, fault zone, etc.); iii) three dimensional plot of fracture and permeability facies in the geological model using a variographic analysis of data. Thirty-three sequential indicator simulations (SIS) were realised on both fracture and permeability facies. Finally, a connectivity algorithm was developed to compute the probability of connection between selected infiltration areas and the major aquifer springs via moderate-to high-permeability geological bodies. Key results are: i) fault zones have a greater role in controlling permeability facies distribution than on fracture facies repartition; ii) there is little correlation between permeability and fracture facies distributions ; iii) connectivity results highlight the compartmentalization of aquifers in the Cadarache area, the extensions of permeable geological bodies being limited by the N130 faults.

  5. Coupling fracture facies with in-situ permeability measurements to generate stochastic simulations of tight carbonate aquifer properties: Example from the Lower Cretaceous aquifer, Northern Provence, SE France

    Science.gov (United States)

    Bruna, Pierre-Olivier; Guglielmi, Yves; Viseur, Sophie; Lamarche, Juliette; Bildstein, Olivier

    2015-10-01

    The relationships between fracture facies and permeability distribution have been explored using a well-constrained 3D implicit structural model of hemipelagic low porosity/low permeability carbonate from the Northern Provence region, SE France. Fracture and permeability facies were determined using an extensive dataset of 99 hydrogeological wells. Data processing was undertaken using a step-by-step approach, involving: (i) identification of the fracture facies based on well logs detailing structure and stratigraphy; (ii) determination of permeability facies from the a priori correlation between the dimension of the hydraulic radius of influence (deduced from slug test analyses) and the type of reservoir heterogeneity (fissure, fracture, fault zone, etc.); (iii) three dimensional plot of fracture and permeability facies in the geological model using a variographic analysis of data. Thirty-three sequential indicator simulations (SIS) based on geostatistic analyses were realised on both fracture and permeability facies. Finally, a connectivity algorithm was developed to compute the probability of connection between selected infiltration areas and the major aquifer springs via moderate- to high-permeability geological bodies. Key results are: (i) fault zones have a greater role in controlling permeability facies distribution than on fracture facies repartition; (ii) there is little correlation between permeability and fracture facies distributions; (iii) connectivity results highlight the compartmentalisation of aquifers in the Cadarache area, the extensions of permeable geological bodies being limited by the N130 faults.

  6. Disposal of carbon dioxide in aquifers in the U.S.

    Energy Technology Data Exchange (ETDEWEB)

    Winter, E.M.; Bergman, P.D.

    1995-11-01

    Deep saline aquifers were investigated as potential disposal sites for CO{sub 2}. The capacity of deep aquifers for CO{sub 2} disposal in the U.S. is highly uncertain. A rough estimate, derived from global estimates, is 5,500 Gt of CO{sub 2}. Saline aquifers underlie the regions in the U.S. where most utility power plants are situated. Therefore, approximately 65 percent of CO{sub 2} from power plants could possibly be injected directly into deep saline aquifers below these plants, without the need for long pipelines.

  7. A Study of the Connection Among Basin-Fill Aquifers, Carbonate-Rock Aquifers, and Surface-Water Resources in Southern Snake Valley, Nevada

    Science.gov (United States)

    U.S. Geological Survey

    2008-01-01

    The Secretary of the Interior through the Southern Nevada Public Lands Management Act approved funding for research to improve understanding of hydrologic systems that sustain numerous water-dependent ecosystems on Federal lands in Snake Valley, Nevada. Some of the streams and spring-discharge areas in and adjacent to Great Basin National Park have been identified as susceptible to ground-water withdrawals (Elliott and others, 2006) and research has shown a high potential for ground-water flow from southern Spring Valley into southern Snake Valley through carbonate rocks that outcrop along a low topographic divide known as the Limestone Hills (Welch and others, 2007). Comprehensive geologic, hydrologic, and chemical information will be collected and analyzed to assess the hydraulic connection between basin-fill aquifers and surface-water resources, water-dependent ecological features, and the regional carbonate-rock aquifer, the known source of many high-discharge springs. Understanding these connections is important because proposed projects to pump and export ground water from Spring and Snake Valleys in Nevada may result in unintended capture of water currently supplying springs, streams, wetlands, limestone caves, and other biologically sensitive areas (fig. 1). The methods that will be used in this study may be transferable to other areas in the Great Basin. The National Park Service, Bureau of Land Management, U.S. Fish and Wildlife Service, and U.S. Forest Service submitted the proposal for funding this research to facilitate science-based land management. Scientists from the U.S. Geological Survey (USGS) Water Resources and Geologic Disciplines, and the University of Nevada, Reno, will accomplish four research elements through comprehensive data collection and analysis that are concentrated in two distinct areas on the eastern and southern flanks of the Snake Range (fig. 2). The projected time line for this research is from July 2008 through September 2011.

  8. Plume Migration of Different Carbon Dioxide Phases During Geological Storage in Deep Saline Aquifers

    Directory of Open Access Journals (Sweden)

    Chien-Hao Shen

    2015-01-01

    Full Text Available This study estimates the plume migration of mobile supercritical phase (flowing, aqueous phase (dissolved, and ionic phase CO2 (bicarbonate, and evaluates the spatial distribution of immobile supercritical phase (residual and mineral phase CO2 (carbonates when CO2 was sequestered. This utilized a simulation, in an anticline structure of a deep saline aquifer in the Tiechenshan (TCS field, Taiwan. All of the trapping mechanisms and different CO2 phases were studied using the fully coupled geochemical equation-of-state GEM compositional simulator. The mobile supercritical phase CO2 moved upward and then accumulated in the up-dip of the structure because of buoyancy. A large amount of immobile supercritical phase CO2 was formed at the rear of the moving plume where the imbibition process prevailed. Both the aqueous and ionic phase CO2 finally accumulated in the down-dip of the structure because of convection. The plume volume of aqueous phase CO2 was larger than that of the supercritical phase CO2, because the convection process increased vertical sweep efficiency. The up-dip of the structure was not the major location for mineralization, which is different from mobile supercritical phase CO2 accumulation.

  9. Carbon Dioxide Disposal in Deep Aquifers: A Comparison between Modeled and Real Systems.

    Science.gov (United States)

    Apps, J. A.; Xu, T.; Pruess, K.

    2001-05-01

    The deep subsurface geologic disposal of CO2 produced during the burning of fossil fuels is being considered as a means of curtailing its progressive accumulation in the atmosphere. However, the long-term potential chemical consequences of such means of disposal are poorly understood. We are presently exploring these consequences by conducting one-dimensional radial flow "numerical experiments" to study the geochemical evolution in a deep saline aquifer in an arenaceous sedimentary host rock under both natural conditions and following injection of supercritical CO2. Comparison is facilitated through use of TOUGHREACT, a fully featured reactive chemical transport simulator, incorporating specific chemical thermodynamic and kinetic data for the participating minerals. Our modeling considers (1) relevant redox processes, (2) organic matter, (3) the kinetics of chemical interactions between the host rock minerals and the aqueous phase, and (4) CO2 solubility dependence on pressure, temperature and salinity of the system. Changes in porosity due to mineral alteration and the precipitation of secondary phases are monitored during the simulations. Of particular interest is the progressive accumulation of soluble carbonate salts in the aqueous phase at the interface with the advancing supercritical CO2 plume, and the effect this accumulation has on mineral alteration and the formation of secondary carbonate minerals. The simulations provide a basis for comparing model results with field observations of sedimentary diagenesis in relatively low CO2 partial pressure environments as well as with those less frequent occurrences of reservoirs of juvenile CO2 associated with magmatic activity. The simulations also provide useful insights into sequestration mechanisms, and controlling conditions and parameters, and finally, they serve to identify critical parameters that require more rigorous quantification.

  10. Methane and Dissolved Organic Carbon Sustain an Ecosystem within a Density Stratified Coastal Aquifer of the Yucatan Peninsula, Mexico. Evidence for a Subterranean Microbial Loop?

    Science.gov (United States)

    Brankovits, David; Pohlman, John W.; Niemann, Helge; Leigh, Mary Beth; Casso, Michael; Alvarez Noguera, Fernando; Lehmann, Moritz F.; Iliffe, Thomas M.

    2016-04-01

    In coastal karst terrains, anchialine caves that meander in density stratified aquifers provide an exceptional opportunity for scientists to study in situ biogeochemical processes within the groundwater. The Caribbean coast of Mexico's Yucatan Peninsula contains over 1000 km of mapped cave passages, the densest known accumulation of anchialine caves in the world. A decades-old study based on the simple observation of 13C-depleted biomass in the cave-adapted fauna suggested biogeochemical processes related to methane-linked carbon cycling and/or other chemoautotrophic pathways as a source of energy and carbon. In this study, we utilized cave diving and a novel sampling device (the Octopipi) to obtain cm-scale water column profiles of methane, DOC and DIC concentrations and stable carbon isotope ratios to identify the energy sources and microbial processes that sustain life in these subterranean estuaries. High concentrations (up to 9522 nM) low-δ13C (as low as -67.5 permil) methane near the ceiling of the cave (in the fresh water section of the stratified water column) and evidence for methane oxidation in the brackish water portion of the water column suggest methane availability and consumption. Profiles obtained by the Octopipi demonstrate that virtually all of the methane (˜99%) is oxidized at the interface of anoxic freshwater and hypoxic brackish water masses. The high-methane water mass near the ceiling also contained elevated concentrations of DOC (851 μM) that displayed comparatively high δ13C (-27.8 to -28.2 permil), suggesting terrestrial organic matter input from the overlying soils. Low-methane brackish and saline water was characterized by lower DOC concentration (15 to 97 μM), yet with similar δ13C (-25.9 to -27.2 permil), suggesting significant terrestrial organic matter consumption or removal with increasing depth, from fresh to saline water, within the water column. The presence of 13C-depleted fatty acids (e.g., C16:1ω7c with δ13C

  11. Correlation of Benzene, 1,1,1-Trichloroethane, and Naphthalene Distribution Coefficients to the Characteristics of Aquifer Materials With Low Organic Carbon Content

    DEFF Research Database (Denmark)

    Larsen, Thomas; Kjeldsen, Peter; Christensen, Thomas Højlund

    1992-01-01

    Laboratory batch experiments on benzene, 1,1,1-trichloroethane (TCA), and naphthalene (concentration: 100–1600 μg/l) sorption onto 20 aquifer materials of low organic carbon content (0.006–0.21 %) showed that the equilibrium distribution between solute and aquifer material could be expressed by t...... attributed to unknown differences in organic matter composition or to the presence of other sorbing components in the aquifer materials. Fair correlations between Kd values for the studied compounds were observed for the individual aquifer materials.......Laboratory batch experiments on benzene, 1,1,1-trichloroethane (TCA), and naphthalene (concentration: 100–1600 μg/l) sorption onto 20 aquifer materials of low organic carbon content (0.006–0.21 %) showed that the equilibrium distribution between solute and aquifer material could be expressed by the...... distribution coefficient, Kd, since the isotherms were linear: Kd(benzene): 0.05–0.65, Kd(TCA): 0.04–0.55, and Kd(naphthalene): 0.1–15.7 ml/g. Correlating observed Kd values to the organic carbon content of the aquifer materials explained only 52–65 % of the variance in Kd. Introducing the specific surface...

  12. Effect of faults on fluid flow and chloride contamination in a carbonate aquifer system

    Science.gov (United States)

    Maslia, M.L.; Prowell, D.C.

    1990-01-01

    A unified, multidiscipline hypothesis is proposed to explain the anomalous pattern by which chloride has been found in water of the Upper Floridan aquifer in Brunswick, Glynn County, Georgia. Analyses of geophysical, hydraulic, water chemistry, and aquifer test data using the equivalent porous medium (EPM) approach are used to support the hypothesis and to improve further the understanding of the fracture-flow system in this area. Using the data presented herein we show that: (1) four major northeast-southwest trending faults, capable of affecting the flow system of the Upper Floridan aquifer, can be inferred from structural analysis of geophysical data and from regional fault patterns; (2) the proposed faults account for the anomalous northeastward elongation of the potentiometric surface of the Upper Floridan aquifer; (3) the faults breach the nearly impermeable units that confine the Upper Floridan aquifer from below, allowing substantial quantities of water to leak vertically upward; as a result, aquifer transmissivity need not be excessively large (as previously reported) to sustain the heavy, long-term pumpage at Brunswick without developing a steep cone of depression in the potentiometric surface; (4) increased fracturing at the intersection of the faults enhances the development of conduits that allow the upward migration of high-chloride water in response to pumping from the Upper Floridan aquifer; and (5) the anomalous movement of the chloride plume is almost entirely controlled by the faults. ?? 1990.

  13. Death Valley Lower Carbonate Aquifer Monitoring Program Wells Down gradient of the Proposed Yucca Mountain Nuclear Waste Repository

    Energy Technology Data Exchange (ETDEWEB)

    Inyo County

    2006-07-26

    Inyo County has participated in oversight activities associated with the Yucca Mountain Nuclear Waste Repository since 1987. The overall goal of these studies are the evaluation of far-field issues related to potential transport, by ground water, or radionuclides into Inyo County, including Death Valley, and the evaluation of a connection between the Lower Carbonate Aquifer (LCA) and the biosphere. Our oversight and completed Cooperative Agreement research, and a number of other investigators research indicate that there is groundwater flow between the alluvial and carbonate aquifers both at Yucca Mountain and in Inyo County. In addition to the potential of radionuclide transport through the LCA, Czarnecki (1997), with the US Geological Survey, research indicate potential radionuclide transport through the shallower Tertiary-age aquifer materials with ultimate discharge into the Franklin Lake Playa in Inyo County. The specific purpose of this Cooperative Agreement drilling program was to acquire geological, subsurface geology, and hydrologic data to: (1) establish the existence of inter-basin flow between the Amargosa Basin and Death Valley Basin; (2) characterize groundwater flow paths in the LCA through Southern Funeral Mountain Range, and (3) Evaluation the hydraulic connection between the Yucca Mountain repository and the major springs in Death Valley through the LCA.

  14. Dissolved Organic Carbon Influences Microbial Community Composition and Diversity in Managed Aquifer Recharge Systems

    KAUST Repository

    Li, D.

    2012-07-13

    This study explores microbial community structure in managed aquifer recharge (MAR) systems across both laboratory and field scales. Two field sites, the Taif River (Taif, Saudi Arabia) and South Platte River (Colorado), were selected as geographically distinct MAR systems. Samples derived from unsaturated riverbed, saturated-shallow-infiltration (depth, 1 to 2 cm), and intermediate-infiltration (depth, 10 to 50 cm) zones were collected. Complementary laboratory-scale sediment columns representing low (0.6 mg/liter) and moderate (5 mg/liter) dissolved organic carbon (DOC) concentrations were used to further query the influence of DOC and depth on microbial assemblages. Microbial density was positively correlated with the DOC concentration, while diversity was negatively correlated at both the laboratory and field scales. Microbial communities derived from analogous sampling zones in each river were not phylogenetically significantly different on phylum, class, genus, and species levels, as determined by 16S rRNA gene pyrosequencing, suggesting that geography and season exerted less sway than aqueous geochemical properties. When field-scale communities derived from the Taif and South Platte River sediments were grouped together, principal coordinate analysis revealed distinct clusters with regard to the three sample zones (unsaturated, shallow, and intermediate saturated) and, further, with respect to DOC concentration. An analogous trend as a function of depth and corresponding DOC loss was observed in column studies. Canonical correspondence analysis suggests that microbial classes Betaproteobacteria and Gammaproteobacteria are positively correlated with DOC concentration. Our combined analyses at both the laboratory and field scales suggest that DOC may exert a strong influence on microbial community composition and diversity in MAR saturated zones.

  15. Structural and hydrogeological features of a Lias carbonate aquifer in the Triffa Plain, NE Morocco

    Science.gov (United States)

    Sardinha, J.; Carneiro, J. F.; Zarhloule, Y.; Barkaoui, A.; Correia, A.; Boughriba, M.; Rimi, A.; El Houadi, B.

    2012-09-01

    The rising demand for water and the contamination of shallow water table aquifers has led authorities in NE Morocco to look for deeper groundwater resources in the Triffa Plain, namely in Lower Jurassic (Lias) dolomitic limestones. The liassic aquifer is of strategic importance for the development of the region, however, its hydrodynamic behaviour is poorly understood due to lack of hydrogeological data and block structure. This article presents a first effort towards understanding the structure and hydraulic behaviour of the aquifer. Exploration borehole data and results from geophysical campaigns were integrated into a GIS environment to build a preliminary model of the aquifer structure. The aquifer behaves as an unconfined aquifer in the northern part of the Béni Snassen Mountains (the recharge area), but as it dips to the north, it becomes confined by marls and shales of the Middle/Upper Jurassic. Even though piezometric level data are scarce, a tentative piezometric map was produced. Three blocks separated by NW-SE trending faults in a horst and graben structure, with distinct flow behaviours were identified: Berkane, Fezouane and Sidi Rahmoun blocks. Those blocks also show differences in hydraulic conductivity distribution. As a result of the reaction with the dolomitic limestones, the groundwater is of calcium-magnesium bicarbonate type. Groundwater temperature as measured in springs ranges from 29 °C to 37 °C in springs and constitutes a potential low enthalpy geothermal resource.

  16. Geostatistical Evaluation of Spring Water Quality in an Urbanizing Carbonate Aquifer

    Science.gov (United States)

    McGinty, A.; Welty, C.

    2003-04-01

    As part of an investigation of the impacts of urbanization on the hydrology and ecology of Valley Creek watershed near Philadelphia, Pennsylvania, we have analyzed the chemical composition of 110 springs to assess the relative influence of geology and anthropogenic activities on water quality. The 60 km^2 watershed is underlain by productive fractured rock aquifers composed of Cambrian and Ordovician carbonate rocks in the central valley and Cambrian crystalline and siliciclastic rocks (quartzite and phyllite) in the north and south hills that border the valley. All tributaries of the surface water system originate in the crystalline and siliciclastic hills. The watershed is covered by 17% impervious area and contains 6 major hazardous waste sites, one active quarrying operation and one golf course; 25% of the area utilizes septic systems for sewage disposal. We identified 172 springs, 110 of which had measurable flow rates ranging from 0.002 to 5 l/s. The mapped surficial geology appears as an anisotropic pattern, with long bands of rock formations paralleling the geographic orientation of the valley. Mapped development appears as a more isotropic pattern, characterized by isolated patches of land use that are not coincident with the evident geologic pattern. Superimposed upon these characteristics is a dense array of depressions and shallow sinkholes in the carbonate rocks, and a system of major faults at several formation contacts. We used indicator geostatistics to quantitatively characterize the spatial extent of the major geologic formations and patterns of land use. Maximum correlation scales for the rock types corresponded with strike direction and ranged from 1000 to 3000 m. Anisotropy ratios ranged from 2 to 4. Land-use correlation scales were generally smaller (200 to 500 m) with anisotropy ratios of around 1.2, i.e., nearly isotropic as predicted. Geostatistical analysis of spring water quality parameters related to geology (pH, specific conductance

  17. Evolution of carbon isotope signatures during reactive transport of hydrocarbons in heterogeneous aquifers

    Science.gov (United States)

    Höyng, Dominik; Prommer, Henning; Blum, Philipp; Grathwohl, Peter; Mazo D'Affonseca, Fernando

    2015-03-01

    Compound-specific isotope analysis (CSIA) of organic pollutants has become a well-established tool for assessing the occurrence and extent of biodegradation processes in contaminated aquifers. However, the precision of CSIA is influenced by the degree to which assumptions underlying CSIA data interpretation hold under realistic field-scale conditions. For the first time this study demonstrates how aquifer analogs combined with reactive transport models offer an underexplored way to develop generic process understanding, evaluate monitoring and quantification strategies in highly heterogeneous subsurface settings. Data from high-resolution aquifer analogs were used in numerical experiments to track the propagation of a representative oxidizable organic compound (toluene) within a variety of realistic heterogeneous aquifers and to investigate its detailed fate. The simulations were used to analyze (1) the effects of physical aquifer heterogeneities on spatiotemporal patterns of contaminant concentrations and isotope signatures, (2) the performance of the commonly applied Rayleigh equation and (3) the applicability of an extension of the Rayleigh equation for complex hydrogeological conditions. The results indicate that if field-derived enrichment factors are applied without corrections for dilution, the conventional Rayleigh equation is inaccurate and estimates for biodegradation are typically overestimated and unreliable in heterogeneous aquifers. Underestimations can occur due to the partial source zone depletion. In contrast, if dilution can be accurately accounted for, field-derived enrichment factors comprise a suitable alternative to laboratory-derived and redox-specific enrichment factors. The study also examines to what extent variations in monitoring/sampling strategies influence the obtained results. Especially measurements from long-screened wells (> 1 m) reveal to be inappropriate for the application of the Rayleigh equation in the investigated aquifer

  18. Carbonate metasomatism and CO2 lithosphere-asthenosphere degassing beneath the western Mediterranean: An integrated model arising from petrological and geophysical data

    International Nuclear Information System (INIS)

    We present an integrated petrological, geochemical, and geophysical model that offers an explanation for the present-day anomalously high non-volcanic deep (mantle derived) CO2 emission in the Tyrrhenian region. We investigate how decarbonation or melting of carbonate-rich lithologies from a subducted lithosphere may affect the efficiency of carbon release in the lithosphere-asthenosphere system. We propose that melting of sediments and/or continental crust of the subducted Adriatic-Ionian (African) lithosphere at pressure greater than 4 GPa (130 km) may represent an efficient mean for carbon cycling into the upper mantle and into the exosphere in the Western Mediterranean area. Melting of carbonated lithologies, induced by the progressive rise of mantle temperatures behind the eastward retreating Adriatic-Ionian subducting plate, generates low fractions of carbonate-rich (hydrous-silicate) melts. Due to their low density and viscosity, such melts can migrate upward through the mantle, forming a carbonated partially molten CO2-rich mantle recorded by tomographic images in the depth range from 130 to 60 km. Upwelling in the mantle of carbonate-rich melts to depths less than 60 - 70 km, induces massive outgassing of CO2. Buoyancy forces, probably favored by fluid overpressures, are able to allow migration of CO2 from the mantle to the surface, through deep lithospheric faults, and its accumulation beneath the Moho and within the lower crust. The present model may also explain CO2 enrichment of the Etna active volcano. Deep CO2 cycling is tentatively quantified in terms of conservative carbon mantle flux in the investigated area. (author)

  19. Assessing Connectivity Between an Overlying Aquifer and a Coal Seam Gas Resource Using Methane Isotopes, Dissolved Organic Carbon and Tritium

    Science.gov (United States)

    Iverach, Charlotte P.; Cendón, Dioni I.; Hankin, Stuart I.; Lowry, David; Fisher, Rebecca E.; France, James L.; Nisbet, Euan G.; Baker, Andy; Kelly, Bryce F. J.

    2015-11-01

    Coal seam gas (CSG) production can have an impact on groundwater quality and quantity in adjacent or overlying aquifers. To assess this impact we need to determine the background groundwater chemistry and to map geological pathways of hydraulic connectivity between aquifers. In south-east Queensland (Qld), Australia, a globally important CSG exploration and production province, we mapped hydraulic connectivity between the Walloon Coal Measures (WCM, the target formation for gas production) and the overlying Condamine River Alluvial Aquifer (CRAA), using groundwater methane (CH4) concentration and isotopic composition (δ13C-CH4), groundwater tritium (3H) and dissolved organic carbon (DOC) concentration. A continuous mobile CH4 survey adjacent to CSG developments was used to determine the source signature of CH4 derived from the WCM. Trends in groundwater δ13C-CH4 versus CH4 concentration, in association with DOC concentration and 3H analysis, identify locations where CH4 in the groundwater of the CRAA most likely originates from the WCM. The methodology is widely applicable in unconventional gas development regions worldwide for providing an early indicator of geological pathways of hydraulic connectivity.

  20. Assessing Connectivity Between an Overlying Aquifer and a Coal Seam Gas Resource Using Methane Isotopes, Dissolved Organic Carbon and Tritium.

    Science.gov (United States)

    Iverach, Charlotte P; Cendón, Dioni I; Hankin, Stuart I; Lowry, David; Fisher, Rebecca E; France, James L; Nisbet, Euan G; Baker, Andy; Kelly, Bryce F J

    2015-01-01

    Coal seam gas (CSG) production can have an impact on groundwater quality and quantity in adjacent or overlying aquifers. To assess this impact we need to determine the background groundwater chemistry and to map geological pathways of hydraulic connectivity between aquifers. In south-east Queensland (Qld), Australia, a globally important CSG exploration and production province, we mapped hydraulic connectivity between the Walloon Coal Measures (WCM, the target formation for gas production) and the overlying Condamine River Alluvial Aquifer (CRAA), using groundwater methane (CH4) concentration and isotopic composition (δ(13)C-CH4), groundwater tritium ((3)H) and dissolved organic carbon (DOC) concentration. A continuous mobile CH4 survey adjacent to CSG developments was used to determine the source signature of CH4 derived from the WCM. Trends in groundwater δ(13)C-CH4 versus CH4 concentration, in association with DOC concentration and (3)H analysis, identify locations where CH4 in the groundwater of the CRAA most likely originates from the WCM. The methodology is widely applicable in unconventional gas development regions worldwide for providing an early indicator of geological pathways of hydraulic connectivity. PMID:26530701

  1. Isotopic discontinuities in ground water beneath Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Analytical data for stable isotopes in ground water from beneath Yucca Mountain, when examined in map view, show areal patterns of heterogeneity that can be interpreted in terms of mixing of at least three end members. One end member must be isotopically heavy in terms of hydrogen and oxygen and have a young apparent 14C age such as water found at the north end of Yucca Mountain beneath Fortymile Wash. A second end member must contain isotopically heavy carbon and have an old apparent 14C age such as water from the Paleozoic aquifer. The third end member cannot be tightly defined. It must be isotopically lighter than the first with respect of hydrogen and oxygen and be intermediate to the first and second end members with respect to both apparent 14C age and δ13C. The variable isotopic compositions of hydrogen and oxygen indicate that two of the end members are waters, but the variable carbon isotopic composition could represent either a third water end member or reaction of water with a carbon-bearing solids such as calcite. 15 refs., 4 figs., 1 tab

  2. Influence of initial heterogeneities and recharge limitations on the evolution of aperture distributions in carbonate aquifers

    Directory of Open Access Journals (Sweden)

    B. Hubinger

    2011-12-01

    Full Text Available Karst aquifers evolve where the dissolution of soluble rocks causes the enlargement of discrete pathways along fractures or bedding planes, thus creating highly conductive solution conduits. To identify general interrelations between hydrogeological conditions and the properties of the evolving conduit systems the aperture-size frequency distributions resulting from generic models of conduit evolution are analysed. For this purpose, a process-based numerical model coupling flow and rock dissolution is employed. Initial protoconduits are represented by tubes with log-normally distributed aperture sizes with a mean μ0 = 0.5 mm for the logarithm of the diameters. Apertures are spatially uncorrelated and widen up to the metre range due to dissolution by chemically aggressive waters. Several examples of conduit development are examined focussing on influences of the initial heterogeneity and the available amount of recharge. If the available recharge is sufficiently high the evolving conduits compete for flow and those with large apertures and high hydraulic gradients attract more and more water. As a consequence, the positive feedback between increasing flow and dissolution causes the breakthrough of a conduit pathway connecting the recharge and discharge sides of the modelling domain. Under these competitive flow conditions dynamically stable bimodal aperture distributions are found to evolve, i.e. a certain percentage of tubes continues to be enlarged while the remaining tubes stay small-sized. The percentage of strongly widened tubes is found to be independent of the breakthrough time and decreases with increasing heterogeneity of the initial apertures and decreasing amount of available water. If the competition for flow is suppressed because the availability of water is strongly limited breakthrough of a conduit pathway is inhibited and the conduit pathways widen very slowly. The resulting aperture distributions are found to be

  3. Impact of background flow on dissolution trapping of carbon dioxide injected into saline aquifers

    CERN Document Server

    Rapaka, Saikiran

    2011-01-01

    While there has been a large interest in studying the role of dissolution-driven free convection in the context of geological sequestration, the contribution of forced convection has been largely ignored. This manuscript considers CO$_2$ sequestration in saline aquifers with natural background flow and uses theoretical arguments to compute the critical background velocity needed to establish the forced convective regime. The theoretical arguments are supported by two dimensional high-resolution numerical simulations which demonstrate the importance of forced convection in enhancing dissolution in aquifers characterised by low Rayleigh numbers.

  4. Identifying microbial carbon sources during ethanol and toluene biodegradation in a pilot-scale experimental aquifer system using isotopic analysis

    Science.gov (United States)

    Clay, S.; McLeod, H.; Smith, J. E.; Roy, J. W.; Slater, G. F.

    2013-12-01

    Combining ethanol with gasoline has become increasingly common in order to create more environmentally conscience transportation fuels. These blended fuels are favourable alternatives since ethanol is a non-toxic and highly labile renewable biomass-based resource which is an effective fuel oxygenate that reduces air pollution. Recent research however, has indicated that upon accidental release into groundwater systems, the preferential microbial metabolism of ethanol can cause progressively reducing conditions leading to slower biodegradation of petroleum hydrocarbons. Therefore, the presence of ethanol can result in greater persistence of BTEX compounds and longer hydrocarbon plumes in groundwater systems. Microbial biodegradation and community carbon sources coupled to aqueous geochemistry were monitored in a pilot-scale laboratory tank (80cm x 525cm x 175cm) simulating an unconfined sand aquifer. Dissolved ethanol and toluene were continuously injected into the aquifer at a controlled rate over 330 days. Carbon isotope analyses were performed on phospholipid fatty acid (PLFA) samples collected from 4 different locations along the aquifer. Initial stable carbon isotope values measured over days 160-185 in the bacterial PLFA ranged from δ13C = -10 to -21‰, which is indicative of dominant ethanol incorporation by the micro-organisms based on the isotopic signature of ethanol derived from corn, a C4 plant. A negative shift to δ13C = -10 to -30‰ observed over days 185-200, suggests a change in microbial metabolisms associated with less ethanol incorporation. This generally corresponds to a decrease in ethanol concentrations from day 40 to full attenuation at approximately day 160, and the onset of toluene depletion observed on day 120 and continuing thereafter. In addition, aqueous methane concentrations first detected on day 115 continued to rise to 0.38-0.70 mmol/L at all monitoring locations, demonstrating a significant redox shift to low energy methanogenic

  5. Correlation of Benzene, 1,1,1-Trichloroethane, and Naphthalene Distribution Coefficients to the Characteristics of Aquifer Materials With Low Organic Carbon Content

    DEFF Research Database (Denmark)

    Larsen, Thomas; Kjeldsen, Peter; Christensen, Thomas Højlund

    1992-01-01

    distribution coefficient, Kd, since the isotherms were linear: Kd(benzene): 0.05–0.65, Kd(TCA): 0.04–0.55, and Kd(naphthalene): 0.1–15.7 ml/g. Correlating observed Kd values to the organic carbon content of the aquifer materials explained only 52–65 % of the variance in Kd. Introducing the specific surface...... area of the aquifer materials as a second regression parameter did not significantly improve the correlation. Estimated Koc values were up to 3 times higher than those predicted from regression equations based on the octanol-water partition coefficient. The reason for this is not known, but may be...... attributed to unknown differences in organic matter composition or to the presence of other sorbing components in the aquifer materials. Fair correlations between Kd values for the studied compounds were observed for the individual aquifer materials....

  6. The role of diagenisis in the hydrogeological stratification of carbonate aquifers: an example from the chalk at Fair Cross, Berkshire, UK

    Directory of Open Access Journals (Sweden)

    J. Bloomfield

    1997-01-01

    Full Text Available Carbonate rocks form important aquifers in many parts of the world and in north-west Europe the Chalk is a primary source of potable water. When flushed with relatively fresh groundwaters, the Chalk may undergo significant diagenetic alteration at relatively shallow depths resulting in a physically and hydrogeochemically stratified aquifer. Diagenetic affects may have important implications for the effective exploitable thickness of the Chalk aquifer and for water quality. In order to assess the affects of diagenesis on the properties of carbonate aquifers, matrix porosity, permeability, pore water and rock chemistry profiles have been analysed for a 300 m deep borehole through the Chalk at the western end of the London Basin. An abrupt change in the matrix porosity profile at 155 mbgl indicates a change in dominant mode of historic diagenesis from mechanical compaction above 155 mbgl to predominantly pressure solution compaction below 155 mbgl. Pore water and rock chemistry profiles also change abruptly across this depth interval, suggesting that the present day hydrogeology is controlled by historic diagenetic trends. Below 155 mbgl, pore waters are relatively saline and there is no evidence for groundwater flow; above 155 mbgl pore waters are relatively fresh and geochemical evidence for incon-gruent carbonate dissolution indicates contemporary groundwater circulation. Possible physical and chemical evolution paths for the Chalk at Fair Cross are discussed. The results provide a hydrogeological context for other studies of the long-term response of carbonate aquifers to base-line changes in sea-level and pore water chemistry and also enable studies with relatively short time-frames or of localized phenomena to be placed in the broader context of the evolution of carbonate aquifers.

  7. Reduced-Order Model for the Geochemical Impacts of Carbon Dioxide, Brine and Trace Metal Leakage into an Unconfined, Oxidizing Carbonate Aquifer, Version 2.1

    Energy Technology Data Exchange (ETDEWEB)

    Bacon, Diana H.

    2013-03-31

    The National Risk Assessment Partnership (NRAP) consists of 5 U.S DOE national laboratories collaborating to develop a framework for predicting the risks associated with carbon sequestration. The approach taken by NRAP is to divide the system into components, including injection target reservoirs, wellbores, natural pathways including faults and fractures, groundwater and the atmosphere. Next, develop a detailed, physics and chemistry-based model of each component. Using the results of the detailed models, develop efficient, simplified models, termed reduced order models (ROM) for each component. Finally, integrate the component ROMs into a system model that calculates risk profiles for the site. This report details the development of the Groundwater Geochemistry ROM for the Edwards Aquifer at PNNL. The Groundwater Geochemistry ROM for the Edwards Aquifer uses a Wellbore Leakage ROM developed at LANL as input. The detailed model, using the STOMP simulator, covers a 5x8 km area of the Edwards Aquifer near San Antonio, Texas. The model includes heterogeneous hydraulic properties, and equilibrium, kinetic and sorption reactions between groundwater, leaked CO2 gas, brine, and the aquifer carbonate and clay minerals. Latin Hypercube sampling was used to generate 1024 samples of input parameters. For each of these input samples, the STOMP simulator was used to predict the flux of CO2 to the atmosphere, and the volume, length and width of the aquifer where pH was less than the MCL standard, and TDS, arsenic, cadmium and lead exceeded MCL standards. In order to decouple the Wellbore Leakage ROM from the Groundwater Geochemistry ROM, the response surface was transformed to replace Wellbore Leakage ROM input parameters with instantaneous and cumulative CO2 and brine leakage rates. The most sensitive parameters proved to be the CO2 and brine leakage rates from the well, with equilibrium coefficients for calcite and dolomite, as well as the number of illite and kaolinite

  8. Nitrogen-isotope analysis of groundwater nitrate in carbonate aquifers: Natural sources versus human pollution

    Science.gov (United States)

    Kreitler, Charles W.; Browning, Lawrence A.

    1983-02-01

    Results of nitrogen-isotope analyses of nitrate in the waters of the Cretaceous Edwards aquifer in Texas, U.S.A., indicate that the source of the nitrate is naturally-occurring nitrogen compounds in the recharge streams. In contrast, nitrogen isotopes of nitrate in the fresh waters of the Pleistocene Ironshore Formation on Grand Cayman Island, West Indies, indicate that human wastes are the source of the nitrate. The Cretaceous Edwards Limestone is a prolific aquifer that produces principally from fracture porosity along the Balcones Fault Zone. Recharge is primarily by streams crossing the fault zone. Rainfall is ˜ 70 cm yr. -1, and the water table is generally deeper than 30 m below land surface. The δ15 N of 73 samples of nitrate from Edwards waters ranged from + 1.9 to + 10‰ with an average of + 6.2‰. This δ15 N range is within the range of nitrate in surface water in the recharge streams ( δ 15N range = + 1 to + 8.3‰ ) and within the range of nitrate in surface water from the Colorado River, Texas, ( δ 15N range = + 1 to + 11‰ ). No sample was found to be enriched in 15N, which would suggest the presence of nitrate from animal waste ( δ 15N range = + 10 to + 22‰ ). The Ironshore Formation contains a small freshwater lens that is recharged entirely by percolation through the soil. Average rainfall is 165 cm yr. -1, and the water table is within 3 m of land surface. The δ15 N of four nitrate samples from water samples of the Ironshore Formation ranged from + 18 to + 23.9‰, which indicates a cesspool/septictank source of the nitrate. Limestone aquifers in humid environments that are recharged by percolation through the soil appear to be more susceptible to contamination by septic tanks than are aquifers in subhumid environments that feature thick unsaturated sections and are recharged by streams.

  9. Microbial community evolution during simulated managed aquifer recharge in response to different biodegradable dissolved organic carbon (BDOC) concentrations

    KAUST Repository

    Li, Dong

    2013-05-01

    This study investigates the evolution of the microbial community in laboratory-scale soil columns simulating the infiltration zone of managed aquifer recharge (MAR) systems and analogous natural aquifer sediment ecosystems. Parallel systems were supplemented with either moderate (1.1 mg/L) or low (0.5 mg/L) biodegradable dissolved organic carbon (BDOC) for a period of six months during which time, spatial (1 cm, 30 cm, 60 cm, 90 cm, and 120 cm) and temporal (monthly) analyses of sediment-associated microbial community structure were analyzed. Total microbial biomass associated with sediments was positively correlated with BDOC concentration where a significant decline in BDOC was observed along the column length. Analysis of 16S rRNA genes indicated dominance by Bacteria with Archaea comprising less than 1 percent of the total community. Proteobacteria was found to be the major phylum in samples from all column depths with contributions from Betaproteobacteria, Alphaproteobacteria and Gammaproteobacteria. Microbial community structure at all the phylum, class and genus levels differed significantly at 1 cm between columns receiving moderate and low BDOC concentrations; in contrast strong similarities were observed both between parallel column systems and across samples from 30 to 120 cm depths. Samples from 1 cm depth of the low BDOC columns exhibited higher microbial diversity (expressed as Shannon Index) than those at 1 cm of moderate BDOC columns, and both increased from 5.4 to 5.9 at 1 cm depth to 6.7-8.3 at 30-120 cm depths. The microbial community structure reached steady state after 3-4 months since the initiation of the experiment, which also resulted in an improved DOC removal during the same time period. This study suggested that BDOC could significantly influence microbial community structure regarding both composition and diversity of artificial MAR systems and analogous natural aquifer sediment ecosystems. © 2013 Elsevier Ltd.

  10. The sources and budget for dissolved sulfate in a fractured carbonate aquifer, southern Sacramento Mountains, New Mexico, USA

    International Nuclear Information System (INIS)

    Climate change in the SW USA is likely to involve drier conditions and higher surface temperatures. In order to better understand the evolution of water chemistry and the sources of aqueous SO4 in these semi-arid settings, chemical and S isotope compositions were determined of springs, groundwater, and bedrock associated with a Permian fractured carbonate aquifer located in the southern Sacramento Mountains, New Mexico, USA. The results suggest that the evolution of water chemistry in the semi-arid carbonate aquifer is mainly controlled by dedolomitization of bedrock, which was magnified by increasing temperature and increasing dissolution of gypsum/anhydrite along the groundwater flow path. The δ34S of dissolved SO4 in spring and groundwater samples varied from +9.0‰ to +12.8‰, reflecting the mixing of SO4 from the dissolution of Permian gypsum/anhydrite (+12.3‰ to +13.4‰) and oxidation of sulfide minerals (−24.5‰ to −4.2‰). According to S isotope mass balance constraints, the contribution of sulfide-derived SO4 was considerable in the High Mountain recharge areas, accounting for up to ∼10% of the total SO4 load. However, sulfide weathering decreased in importance in the lower reaches of the watershed. A smaller SO4 input of ∼2–4% was contributed by atmospheric wet deposition. This study implies that the δ34S variation of SO4 in semi-arid environments can be complex, but that S isotopes can be used to distinguish among the different sources of weathering. Here it was found that H2SO4 dissolution due to sulfide oxidation contributes up to 5% of the total carbonate weathering budget, while most of the SO4 is released from bedrock sources during dedolomitization.

  11. Conditions of diamond formation beneath the Sino-Korean craton: paragenesis, temperatures and the isotopic composition of carbon

    International Nuclear Information System (INIS)

    Mineral inclusions (23 pyrope garnets, 30 chromites) have been extracted from 28 diamonds selected from the Pipe 50 kimberlite in Liaoning Province, and the pipes of the Shengli 1 and Hongqi 6 kimberlites in Shandong province. These inclusions, and several from the collection of Meyer et al., (1994), have been analysed for major elements using EMP and for trace elements using the proton microprobe. Carbon-isotope compositions have been measured on 44 diamonds (23 from Liaoning, 21 from Shandong), of which 32 contained identified inclusions. The δ13C values range from +0.9 to -6.0 per mill; the heaviest carbon is found in stones with very low-Ca garnets. This implies that the isotopic composition of carbon in harzburgitic rocks is related to the primary depletion process, which suggests ancient formation of the diamonds

  12. Soil organic carbon beneath croplands and re-established grasslands in the North Dakota prairie pothole region

    Science.gov (United States)

    Grassland ecosystems established under the conservation reserve program (CRP) in the Prairie Pothole Region (PPR) currently provide soil conservation and wildlife habitat services. We aimed to determine if these lands also sequester soil organic carbon (SOC), as compared with neighboring croplands a...

  13. Contribution from carbon and sulphur isotopes to the evaluation of biogeochemical processes in groundwater systems controlled by river bank filtration: An example from the Torgau aquifer (Saxony, Germany)

    International Nuclear Information System (INIS)

    Sulphur and carbon isotopes were used to reveal flow processes and chemical reactions within an aquifer system partially controlled by river bed infiltration. The investigation site, located at the Elbe river, is the most important water supply area of Saxony. An arrangement of about 40 groundwater sampling points, screened in five or three depth levels within a section crossing the Elbe, was used to describe the situation in the Quaternary aquifer. Using 34S (SO4) and 13C (DIC) as tracers, an improved understanding of the flow pattern has been obtained, especially regarding the penetration of groundwater into the aquifer zone below the Elbe bed. Furthermore, groundwater and Elbe water show different isotope signatures. Depletion of 34S in the area between the Elbe and the production wells is attributed to the oxidation of pyritic sulphur. The measured radiocarbon concentrations of groundwater fulvic acids suggest that less than 50% of the DOC originates from old sedimentary organic carbon (SOC) sources in the aquifer. 14C decrease along the flow path from the Elbe to the captation facilities has been observed and is proposed as being due to a simultaneous degradation of Elbe DOC and dissolution of old SOC from the penetrated aquifer. The unusual chemical and isotopic composition of groundwater near the edge of the investigated profile is interpreted as a local influence of ascending waters coming from Zechstein formations and penetrating the overlaying Triassic and Tertiary layers via tectonic faults or geological windows. (author)

  14. Temporal dynamics of groundwater-dissolved inorganic carbon beneath a drought-affected braided stream: Platte River case study

    Science.gov (United States)

    Boerner, Audrey R.; Gates, John B.

    2015-05-01

    Impacts of environmental changes on groundwater carbon cycling are poorly understood despite their potentially high relevance to terrestrial carbon budgets. This study focuses on streambed groundwater chemistry during a period of drought-induced river drying and consequent disconnection between surface water and groundwater. Shallow groundwater underlying vegetated and bare portions of a braided streambed in the Platte River (Nebraska, USA) was monitored during drought conditions in summer 2012. Water temperature and dissolved inorganic carbon (dominated by HCO3-) in streambed groundwater were correlated over a 3 month period coinciding with a decline in river discharge from 35 to 0 m3 s-1. Physical, chemical, and isotopic parameters were monitored to investigate mechanisms affecting the HCO3- trend. Equilibrium thermodynamic modeling suggests that an increase of pCO2 near the water table, coupled with carbonate mineral weathering, can explain the trend. Stronger temporal trends in Ca2+ and Mg2+ compared to Cl- are consistent with carbonate mineral reequilibria rather than evaporative concentration as the primary mechanism of the increased HCO3-. Stable isotope trends are not apparent, providing further evidence of thermodynamic controls rather than evaporation from the water table. A combination of increased temperature and O2 in the dewatered portion of the streambed is the most likely driver of increased pCO2 near the water table. Results of this study highlight potential linkages between surface environmental changes and groundwater chemistry and underscore the need for high-resolution chemical monitoring of alluvial groundwater in order to identify environmental change impacts.

  15. Potential for a process-based monitoring method above geologic carbon storage sites using dissolved gases in freshwater aquifers

    International Nuclear Information System (INIS)

    The process-based method is a new technique for monitoring CO2 storage permanence in the vadose zone above geologic carbon storage (GCS) sites. This method uses ratios of coexisting gas species to understand geochemical processes rather than comparing CO2 concentrations with large baseline data sets, thereby making monitoring more efficient. In the vadose zone, ratios among coexisting gases (CO2, O2, N2 and CH4) have been used to distinguish biologic respiration, water-rock-CO2 interaction, and methane oxidation from a leakage signal. We report the preliminary results of a feasibility test conducted in July 2012 at the Zero Emission Research and Technology Center (ZERT) controlled release site in Montana, USA to discern whether the method could be applied to dissolved gases in groundwater, thereby enhancing groundwater monitoring. Preliminary results are favorable, making the process-based approach potentially useful for monitoring shallow freshwater aquifers above GCS sites. (authors)

  16. Sustainability of natural attenuation of nitrate in agricultural aquifers

    Science.gov (United States)

    Green, Christopher T.; Bekins, Barbara A.

    2010-01-01

    Increased concentrations of nitrate in groundwater in agricultural areas, coinciding with increased use of chemical and organic fertilizers, have raised concern because of risks to environmental and human health. At some sites, these problems are mitigated by natural attenuation of nitrate as a result of microbially mediated reactions. Results from U.S. Geological Survey (USGS) research under the National Water-Quality Assessment (NAWQA) program show that reactions of dissolved nitrate with solid aquifer minerals and organic carbon help lower nitrate concentrations in groundwater beneath agricultural fields. However, increased fluxes of nitrate cause ongoing depletion of the finite pool of solid reactants. Consumption of the solid reactants diminishes the capacity of the aquifer to remove nitrate, calling into question the long-term sustainability of these natural attenuation processes.

  17. Origin of the groundwater salinity and geochemical processes in detrital and carbonate aquifers: Case of Chougafiya basin (Central Tunisia)

    Science.gov (United States)

    Farid, Intissar; Zouari, Kamel; Rigane, Adel; Beji, Ridha

    2015-11-01

    Comprehensive investigations of groundwaters were performed in the detrital and carbonate aquifers of the Chougafiya basin, central Tunisia. In the present review, hydrochemistry and isotopic tools were combined to get an insight into the processes controlling mineralization, recharge conditions, flow pattern of groundwater and C chemistry in the investigated hydrological system. Analysis of the dissolved constituents revealed that several processes controlled the observed chemical composition: (i) the dissolution of evaporitic minerals, (ii) cation exchange reactions, (iii) sulfate reduction under anaerobic conditions, (iv) incongruent dissolution of carbonate minerals (calcite, dolomite) coupled with gypsum dissolution and calcite precipitation, and (v) silicates weathering. Data inferred from 18O and deuterium isotopes in groundwater samples indicated recharge with modern rainfall. Water characterized by lower δ18O and δ2H values is interpreted as recharged by non-evaporated rainfall originating from Mediterranean and Atlantic air masses. However, water with relatively enriched δ18O and δ2H contents is thought to reflect the occurrence of an evaporation process related to the long term practice of flood irrigation. The radiogenic (3H) isotope data provided insight into the presence of two recharge periods in the investigated groundwaters. Waters with 3H contents of 1 TU clearly suggested the occurrence of a contemporaneous recharge probably during the last two decades. Carbon isotopes provided some insights into the timescales of groundwater flow, but mainly revealed that main sources of C are active in the system. These are likely: dissolved biogenic CO2, carbonate dissolution and incongruent reaction of the carbonate matrix. Mean residence times were determined after correction of the initial activities for dead C from the rock matrix and suggest ages ranging from the present day to the Holocene in both Upper Cretaceous and Mio-pliocene groundwaters.

  18. Numerical simulation of the basin scale hydrogeological impacts of carbon sequestration in deep saline aquifers of the St. Lawrence Lowlands

    Science.gov (United States)

    Girou, O.; Lemieux, J. M.; Malo, M.

    2015-12-01

    Full-scale carbon capture and storage in deep saline aquifers implies injecting important quantities of carbon in order to significantly reduce greenhouse gases emissions. At the basin scale, impacts related to CO2 injection are pressure perturbation as well as brine migration into freshwater aquifers. In this study, potential impacts of an industrial-scale carbon capture and storage project in Bécancour (Quebec, Canada), in the St. Lawrence Lowlands basin, are discussed, as well as the role played by regional normal faults that divide the basin into multiple compartments. The basin is 300 km long and 90 km wide, formed by sub-horizontal Paleozoic formations on top of which the Utica and Lorraine shale formations represent the caprock of the potential CO2reservoir. These formations cover most of the basin, except in its eroded northwestern part, located between 10 to 40 km away from the potential injection sites. Three injection scenarios were considered, corresponding to greenhouse gases emissions from large emitters located; in Bécancour industrial park, in a larger area that allow affordable transport and in the entire basin without considering transport costs (1, 5, 10 Mt/yr). The numerical model FEFLOW was used to simulate CO2 injection into different compartments to evaluate pressure build up propagation and brine migration in order to define which compartments are best suited for long-term storage. The simulations considered an injection period of 100 years and post-injections period of 1000 years. Numerical simulations indicate that normal faults, which exhibit a low hydraulic conductivity, play a major role orienting pressure build-up and brine migration. Due to the presence of normal faults, no pressure build up occurred close to the surface. Similarly, preliminary mass transport simulations show very limited brine migration. These first results indicate that basin-scale impacts of carbon injection are low for the 3 injection scenarios, however, the

  19. Hydrochemical evolution of sodium-sulfate and sodium-chloride groundwater beneath the Northern Chihuahuan Desert, Trans-Pecos, Texas, USA

    Science.gov (United States)

    Fisher, R.S.; Mullican, W. F., III

    1997-01-01

    Groundwater beneath the northern Chihuahuan Desert, Trans-Pecos, Texas, USA, occurs in both carbonate and siliciclastic aquifers beneath a thick unsaturated zone and in shallow Rio Grande alluvium. Groundwater hydrochemical evolution was investigated by analyzing soils, soil leachates, bolson-fill sediments, water from the unsaturated zone, and groundwater from three major aquifers. Ionic relations, mineral saturation states, and geochemical modeling show that groundwater compositions are controlled by reactions in the unsaturated zone, mineralogy of unsaturated sediments and aquifers, position in the groundwater flow system, and extensive irrigation. Recharge to aquifers unaffected by irrigation is initially a Ca-HCO3 type as a result of dissolving carbonate surficial salts. With continued flow and mineral-water interaction, saturation with calcite and dolomite is maintained, gypsum is dissolved, and aqueous Ca and Mg are exchanged for adsorbed Na to produce a Na-SO4 water. Groundwater in Rio Grande alluvium is a Na-Cl type, reflecting river-water composition and the effects of irrigation, evapotranspiration, and surficial salt recycling. These results document two hydrochemical evolution paths for groundwater in arid lands. If recharge is dilute precipitation, significant changes in water chemistry can occur in unsaturated media, ion exchange can be as important as dissolution-precipitation reactions in determining groundwater composition, and mineral-water reactions ultimately control groundwater composition. If recharge is return flow of irrigation water that already contains appreciable solutes, mineral-water reactions are less important than irrigation-water composition in determining groundwater chemistry.

  20. Use of Anticlines for Geologic Sequestration of Carbon Dioxide in a Saline Aquifer in Northwestern Taiwan

    Science.gov (United States)

    Lin, Shin-Hsun; Liou, Tai-Sheng

    2013-04-01

    In this study, migration of CO2 in a deep saline aquifer with anticlines under various injection schemes was numerically simulated using the ECO2N simulator. The hypothetical study site was selected at the Taoyuan Plateau near the second largest coal-fired power plant, Datan power plant (annual CO2 emission of 1.5 Mt/yr), in Northwestern Taiwan. A 15x15 km2 simulation domain, containing two sub-parallel east-northeast Hukou and Pingzhen anticlines, was discretized into unstructured grid with spatial refinement at the injection borehole. Kueichulin sandstone and Chinshui shale in the simulation domain were considered as the storage formation and the cap rock, respectively. It was assumed that no CO2 exists in the aquifer prior to injection, and that the aquifer has a hydrostatic pressure distribution and a constant salinity of 3%. All boundaries were assumed to be "open". Isothermal simulations with 1 Mt/yr injection rate and 20 years of injection period were considered. van Genuchten capillary pressure and Corey relative permeability were assumed for all rock formations. Simulation results indicated that pressure buildup characterized the CO2 migration into three different phases: drainage of brine, formation dry-out, and dissolution and gravity take-over . It was found that the worst leakage scenario occurs if a single injection borehole is placed along the anticline axis. In this case, rock formations near the anticline axis provide a leakage path such that CO2 ultimately leaks out of the upper boundary. On the other hand, CO2 can be safely sequestrated in the storage formation if the injection borehole was placed away from the anticline axis. This is because gas phase CO2 migrates along the counter dipping direction of the anticline as a result of buoyancy. More favorable scenarios were found if a multiple-borehole injection scheme was used. In such cases, not only pressure buildup was significantly mitigated but the amount of precipitated salt was reduced. If a

  1. Geological factors affecting the chemical characteristics of the thermal waters of the carbonate karstified aquifers of Northern Vietnam

    Directory of Open Access Journals (Sweden)

    C. Drogue

    2000-01-01

    Full Text Available In northern Vietnam, exposed carbonate rock formations cover an area of more than 50,000 km2 .Their accumulated thickness from the Cambrian to the Triassic is in some places as much as 3000 m. Numerous thermal waters (springs and wells occur in these strongly karstified carbonate massifs. This is the result of significant ancient and present orogenic activity, as the region demonstrates by its strong seismic activity. These karstic formations are water-bearing and strongly recharged by rainfall of between 1600 mm and 2000 mm per year in 90% of the area concerned. In view of the average annual air temperatures (17°C-25°C according to the region, 23 sample springs or wells were chosen with water temperatures of between 29°C and 68°C. Hydrochemical characteristics of these thermal waters emerging in different carbonate-rock units were examined by chemical analyses of major ions. In this large region, thermal waters are divided into four hydrochemical types: the Na-Cl type resulting from the intrusion of sea water for distances of up to several kilometres inland and depths of 1000 m, the Ca-SO4 type, probably resulting from the leaching of deposits of metallic sulphides that are widely distributed in these carbonate-rock units, and finally the Ca-HCO3 and Mg-HCO3 types which are chemically similar to fresh karstic waters in limestones and dolostones. The occurrence of these thermal groundwaters as well as their chemical characteristics seem to indicate the existence of large-scale deepseated groundwater flow systems in the karstic aquifers. Keywords: Vietnam; thermal waters; karst; hydrochemistry

  2. Removal of dissolved organic carbon by aquifer material: Correlations between column parameters, sorption isotherms and octanol-water partition coefficient.

    Science.gov (United States)

    Pradhan, Snigdhendubala; Boernick, Hilmar; Kumar, Pradeep; Mehrotra, Indu

    2016-07-15

    The correlation between octanol-water partition coefficient (KOW) and the transport of aqueous samples containing single organic compound is well documented. The concept of the KOW of river water containing the mixture of organics was evolved by Pradhan et al. (2015). The present study aims at determining the KOW and sorption parameters of synthetic aqueous samples and river water to finding out the correlation, if any. The laboratory scale columns packed with aquifer materials were fed with synthetic and river water samples. Under the operating conditions, the compounds in the samples did not separate, and all the samples that contain more than one organic compound yielded a single breakthrough curve. Breakthrough curves simulated from sorption isotherms were compared with those from the column runs. The sorption parameters such as retardation factor (Rf), height of mass transfer zone (HMTZ), rate of mass transfer zone (RMTZ), breakpoint column capacity (qb) and maximum column capacity (qx) estimated from column runs, sorption isotherms and models developed by Yoon-Nelson, Bohart-Adam and Thomas were in agreement. The empirical correlations were found between the KOW and sorption parameters. The transport of the organics measured as dissolved organic carbon (DOC) through the aquifer can be predicted from the KOW of the river water and other water samples. The novelty of the study is to measure KOW and to envisage the fate of the DOC of the river water, particularly during riverbank filtration. Statistical analysis of the results revealed a fair agreement between the observed and computed values. PMID:27082255

  3. The effect of hydrogeological conditions on variability and dynamic of groundwater recharge in a carbonate aquifer at local scale

    Science.gov (United States)

    Dvory, Noam Zach; Livshitz, Yakov; Kuznetsov, Michael; Adar, Eilon; Yakirevich, Alexander

    2016-04-01

    Groundwater recharge in fractured karstic aquifers is particularly difficult to quantify due to the rock mass's heterogeneity and complexity that include preferential flow paths along karst conduits. The present study's major goals were to assess how the changes in lithology, as well as the fractured karst systems, influence the flow mechanism in the unsaturated zone, and to define the spatial variation of the groundwater recharge at local scale. The study area is located within the fractured carbonate Western Mountain aquifer (Yarkon-Taninim), west of the city of Jerusalem at the Ein Karem (EK) production well field. Field monitoring included groundwater level observations in nine locations in the study area during years 1990-2014. The measured groundwater level series were analyzed with the aid of one-dimensional, dual permeability numerical model of water flow in variably saturated fractured-porous media, which was calibrated and used to estimate groundwater recharge at nine locations. The recharge values exhibit significant spatial and temporal variation with mean and standard deviation values of 216 and 113 mm/year, respectively. Based on simulations, relationships were established between precipitation and groundwater recharge in each of the nine studied sites and compared with similar ones obtained in earlier regional studies. Simulations show that fast and slow flow paths conditions also influence annual cumulative groundwater recharge dynamic. In areas where fast flow paths exist, most of the groundwater recharge occurs during the rainy season (60-80% from the total recharge for the tested years), while in locations with slow flow path conditions the recharge rate stays relatively constant with a close to linear pattern and continues during summer.

  4. Well-based stable carbon isotope leakage monitoring of an aquifer overlying the CO2 storage reservoir at the Ketzin pilot site, Germany

    Science.gov (United States)

    Nowak, Martin; Myrttinen, Anssi; Zimmer, Martin; van Geldern, Robert; Barth, Johannes A. C.

    2014-05-01

    At the pilot site for CO2 storage in Ketzin, a new well-based leakage-monitoring concept was established, comprising geochemical and hydraulic observations of the aquifer directly above the CO2 reservoir (Wiese et al., 2013, Nowak et al. 2013). Its purpose was to allow early detection of un-trapped CO2. Within this monitoring concept, we established a stable carbon isotope monitoring of dissolved inorganic carbon (DIC). If baseline isotope values of aquifer DIC (δ13CDIC) and reservoir CO2 (δ13CCO2) are known and distinct from each other, the δ13CDIC has the potential to serve as an an early indicator for an impact of leaked CO2 on the aquifer brine. The observation well of the overlying aquifer was equipped with an U-tube sampling system that allowed sampling of unaltered brine. The high alkaline drilling mud that was used during well drilling masked δ13CDIC values at the beginning of the monitoring campaign. However, subsequent monitoring allowed observing on-going re-equilibration of the brine, indicated by changing δ13CDIC and other geochemical values, until values ranging around -23 ‰ were reached. The latter were close to baseline values before drilling. Baselineδ13CDIC and δ13CCO2 values were used to derive a geochemical and isotope model that predicts evolution of δ13CDIC, if CO2 from the reservoir would leak into the aquifer. The model shows that equilibrium isotope fractionation would have to be considered if CO2 dissolves in the brine. The model suggests that stable carbon isotope monitoring is a suitable tool to assess the impact of injected CO2 in overlying groundwater aquifers. However, more data are required to close gaps of knowledge about fractionation behaviour within the CO2(g) - DIC system under elevated pressures and temperatures. Nowak, M., Myrttinen, A., Zimmer, M., Wiese, B., van Geldern, R., Barth, J.A.C., 2013. Well-based, Geochemical Leakage Monitoring of an Aquifer Immediately Above a CO2 Storage Reservoir by Stable Carbon

  5. Reactive Transport Modeling of the Enhancement of Density-Driven CO2 Convective Mixing in Carbonate Aquifers and its Potential Implication on Geological Carbon Sequestration.

    Science.gov (United States)

    Islam, Akand; Sun, Alexander Y; Yang, Changbing

    2016-01-01

    We study the convection and mixing of CO2 in a brine aquifer, where the spread of dissolved CO2 is enhanced because of geochemical reactions with the host formations (calcite and dolomite), in addition to the extensively studied, buoyancy-driven mixing. The nonlinear convection is investigated under the assumptions of instantaneous chemical equilibrium, and that the dissipation of carbonate rocks solely depends on flow and transport and chemical speciation depends only on the equilibrium thermodynamics of the chemical system. The extent of convection is quantified in term of the CO2 saturation volume of the storage formation. Our results suggest that the density increase of resident species causes significant enhancement in CO2 dissolution, although no significant porosity and permeability alterations are observed. Early saturation of the reservoir can have negative impact on CO2 sequestration. PMID:27094448

  6. Reactive Transport Modeling of the Enhancement of Density-Driven CO2 Convective Mixing in Carbonate Aquifers and its Potential Implication on Geological Carbon Sequestration

    Science.gov (United States)

    Islam, Akand; Sun, Alexander Y.; Yang, Changbing

    2016-01-01

    We study the convection and mixing of CO2 in a brine aquifer, where the spread of dissolved CO2 is enhanced because of geochemical reactions with the host formations (calcite and dolomite), in addition to the extensively studied, buoyancy-driven mixing. The nonlinear convection is investigated under the assumptions of instantaneous chemical equilibrium, and that the dissipation of carbonate rocks solely depends on flow and transport and chemical speciation depends only on the equilibrium thermodynamics of the chemical system. The extent of convection is quantified in term of the CO2 saturation volume of the storage formation. Our results suggest that the density increase of resident species causes significant enhancement in CO2 dissolution, although no significant porosity and permeability alterations are observed. Early saturation of the reservoir can have negative impact on CO2 sequestration. PMID:27094448

  7. Reactive Transport Modeling of the Enhancement of Density-Driven CO2 Convective Mixing in Carbonate Aquifers and its Potential Implication on Geological Carbon Sequestration

    Science.gov (United States)

    Islam, Akand; Sun, Alexander Y.; Yang, Changbing

    2016-04-01

    We study the convection and mixing of CO2 in a brine aquifer, where the spread of dissolved CO2 is enhanced because of geochemical reactions with the host formations (calcite and dolomite), in addition to the extensively studied, buoyancy-driven mixing. The nonlinear convection is investigated under the assumptions of instantaneous chemical equilibrium, and that the dissipation of carbonate rocks solely depends on flow and transport and chemical speciation depends only on the equilibrium thermodynamics of the chemical system. The extent of convection is quantified in term of the CO2 saturation volume of the storage formation. Our results suggest that the density increase of resident species causes significant enhancement in CO2 dissolution, although no significant porosity and permeability alterations are observed. Early saturation of the reservoir can have negative impact on CO2 sequestration.

  8. Application of isotope techniques to carbonate rock aquifers: Some Indian examples

    International Nuclear Information System (INIS)

    Isotope hydrological investigations were carried out to study the origin of ground water and surface water-ground water interactions in two carbonate rock terrains - Jhamarkotra rock phosphate mine, Rajasthan and Amner river basin, Madhya Pradesh - situated in different settings

  9. 1:1,000,000-scale estimated outer extent of areas of groundwater discharge as evapotranspiration for the Great Basin carbonate and alluvial aquifer system of Nevada, Utah, and parts of adjacent states

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset was created in support of a study focusing on groundwater resources in the Great Basin carbonate and alluvial aquifer system (GBCAAS). The GBCAAS is a...

  10. Micron-scale coupled carbon isotope and nitrogen abundance variations in diamonds: Evidence for episodic diamond formation beneath the Siberian Craton

    Science.gov (United States)

    Wiggers de Vries, D. F.; Bulanova, G. P.; De Corte, K.; Pearson, D. G.; Craven, J. A.; Davies, G. R.

    2013-01-01

    The internal structure and growth history of six macro-diamonds from kimberlite pipes in Yakutia (Russia) were investigated with cathodoluminescence imaging and coupled carbon isotope and nitrogen abundance analyses along detailed core to rim traverses. The diamonds are characterised by octahedral zonation with layer-by-layer growth. High spatial resolution SIMS profiles establish that there is no exchange of the carbon isotope composition across growth boundaries at the μm scale and that isotopic variations observed between (sub)zones within the diamonds are primary. The macro-diamonds have δ13C values that vary within 2‰ of -5.3‰ and their nitrogen contents range between 0-1334 at. ppm. There are markedly different nitrogen aggregation states between major growth zones within individual diamonds that demonstrate Yakutian diamonds grew in multiple growth events. Growth intervals were punctuated by stages of dissolution now associated with <10 μm wide zones of nitrogen absent type II diamond. Across these resorption interfaces carbon isotope ratios and nitrogen contents record shifts between 0.5-2.3‰ and up to 407 at. ppm, respectively. Co-variation in δ13C value-nitrogen content suggests that parts of individual diamonds precipitated in a Rayleigh process from either oxidised or reduced fluids/melts, with two single diamonds showing evidence of both fluid types. Modelling the co-variation establishes that nitrogen is a compatible element in diamond relative to its growth medium and that the nitrogen partition coefficient is different between oxidised (3-4.1) and reduced (3) sources. The reduced sources have δ13C values between -7.3‰ and -4.6‰, while the oxidised sources have higher δ13C values between -5.8‰ and -1.8‰ (if grown from carbonatitic media) or between -3.8‰ and +0.2‰ (if grown from CO2-rich media). It is therefore concluded that individual Yakutian diamonds originate from distinct fluids/melts of variable compositions. The

  11. Isotopic measurements in research on seawater ingression in the carbonate aquifer of the Salentine Peninsula, Southern Italy

    International Nuclear Information System (INIS)

    Cretaceous calcareous and dolomitic rocks, bedded, jointed and karstified, and hence generally very permeable, form the basement of the Salentine Peninsula. These rocks constitute a huge aquifer with fresh and brackish groundwaters that float on groundwaters of marine origin. Sea level constitutes the base level of the ground waters. A basic outline is first given of the hydrogeology and the paleohydrogeology, so as to provide the necessary background information on the seawater intrusion phenomenon and to permit comparison of the results of the isotope data with those obtained by the classical methods of hydrogeological investigation. This is followed by presentation of the results of the isotopic measurements on 18O, D, 13C and 14C. The δ13C contents indicate, in good agreement with the carbon dioxide and bicarbonate concentrations, that seawater ingression leads to the migration of carbon dioxide from the fresh and brackish waters towards the subjacent intrusive waters of marine origin. Along those stretches of coast where the seawaters are in direct communication with the groundwaters, all the isotope data point to very active renewal of groundwaters of marine origin by seawater. In the central parts of the peninsula and along those stretches of coast where direct communication between seawaters and groundwaters is impeded by impervious clays, the 14C contents indicate that the seawater intrusion and consequently the migration of carbon dioxide are either very slow and continuous in time or that they occurred relatively rapidly in the past. Taking into consideration the paleohydrogeology of the peninsula, and the fact that the δ18O and δD values are higher than those of the present seawaters, leads to the belief that seawater intrusion may well have occurred during major variations in the sea level in the past, when climatic conditions were different from those now prevailing. (author)

  12. Spring Database for the Basin and Range Carbonate-Rock Aquifer System, White Pine County, Nevada, and Adjacent Areas in Nevada and Utah

    Science.gov (United States)

    Pavelko, Michael T.

    2007-01-01

    A database containing nearly 3,400 springs was developed for the Basin and Range carbonate-rock aquifer system study area in White Pine County, Nevada, and adjacent areas in Nevada and Utah. The spring database provides a foundation for field verification of springs in the study area. Attributes in the database include location, geographic and general geologic settings, and available discharge and temperature data for each spring.

  13. Alluvial Aquifer

    Data.gov (United States)

    Kansas Data Access and Support Center — This coverage shows the extents of the alluvial aquifers in Kansas. The alluvial aquifers consist of unconsolidated Quaternary alluvium and contiguous terrace...

  14. The Role of Dissolved Organic Carbon and Preadaptation in the Biotransformation of Trace Organic Chemicals during Aquifer Recharge and Recovery

    KAUST Repository

    Ouf, Mohamed

    2012-05-01

    Aquifer recharge and recovery (ARR) is a low-cost and environmentally-friendly treatment technology which uses conventionally treated wastewater effluent for groundwater recharge and subsequent recovery for agricultural, industrial or drinking water uses. This study investigated the effect of different dissolved organic carbon (DOC) composition in wastewater effluent on the fate of trace organic chemicals (TOrCs) during ARR. Four biologically active columns were setup receiving synthetic wastewater effluent with varying DOC compositions. The difference in DOC composition triggered variations in the microbial community’s diversity and hence its ability to degrade TOrCs. It was found that the presence of protein-like DOC enhances the removal of DOC in comparison with the presence of humic-like DOC. On the other hand, the presence of humic-like DOC, which is more difficult to degrade, improved the removal of several degradable TOrCs. Other column experiments were also carried out to investigate the role of previous and continuous exposure to TOrCs in their removal. The use of soil pre-exposed to low concentrations of TOrCs and DOC provided better removal of both DOC and TOrCs. The findings of this study suggest that the presence of more humic-like DOC in the effluent enhances the biotransformation of TOrCs during ARR. In addition, long exposure to both DOC and TOrCs increases the degree of their removal over time

  15. Potential methane reservoirs beneath Antarctica.

    Science.gov (United States)

    Wadham, J L; Arndt, S; Tulaczyk, S; Stibal, M; Tranter, M; Telling, J; Lis, G P; Lawson, E; Ridgwell, A; Dubnick, A; Sharp, M J; Anesio, A M; Butler, C E H

    2012-08-30

    Once thought to be devoid of life, the ice-covered parts of Antarctica are now known to be a reservoir of metabolically active microbial cells and organic carbon. The potential for methanogenic archaea to support the degradation of organic carbon to methane beneath the ice, however, has not yet been evaluated. Large sedimentary basins containing marine sequences up to 14 kilometres thick and an estimated 21,000 petagrams (1 Pg equals 10(15) g) of organic carbon are buried beneath the Antarctic Ice Sheet. No data exist for rates of methanogenesis in sub-Antarctic marine sediments. Here we present experimental data from other subglacial environments that demonstrate the potential for overridden organic matter beneath glacial systems to produce methane. We also numerically simulate the accumulation of methane in Antarctic sedimentary basins using an established one-dimensional hydrate model and show that pressure/temperature conditions favour methane hydrate formation down to sediment depths of about 300 metres in West Antarctica and 700 metres in East Antarctica. Our results demonstrate the potential for methane hydrate accumulation in Antarctic sedimentary basins, where the total inventory depends on rates of organic carbon degradation and conditions at the ice-sheet bed. We calculate that the sub-Antarctic hydrate inventory could be of the same order of magnitude as that of recent estimates made for Arctic permafrost. Our findings suggest that the Antarctic Ice Sheet may be a neglected but important component of the global methane budget, with the potential to act as a positive feedback on climate warming during ice-sheet wastage. PMID:22932387

  16. A 3D density-dependent model for assessment and optimization of water management policy in a coastal carbonate aquifer exploited for water supply and fish farming

    Science.gov (United States)

    Nocchi, M.; Salleolini, M.

    2013-06-01

    The Ansedonia promontory (southern Tuscany, Italy) is characterized by the presence of fish farms that pump thermal saline groundwater. The water is extracted from a carbonate aquifer with high permeability due to fracturing and karstification that is also exploited for irrigation purposes and domestic use. Such exploitation has led to the degradation of groundwater quality, producing conflict among the different users. The conceptualization of the aquifer allowed the development of a 3D finite element density-dependent numerical model using the FEFLOW code. The slightly negative freshwater budget in the very humid hydrologic year of 2004-2005 revealed that the aquifer was overexploited, especially due to the extraction of freshwater (along with seawater) from fish farm wells and pumping from public supply wells. The model was also used to forecast the quantitative and qualitative evolution of resources over time, thus testing the effects of different management hypotheses. Results demonstrate that the sustainable management of the aquifer mostly depends on withdrawals from public supply wells; the quantity extracted by fish farms only significantly affects the freshwater/saltwater interface and, locally, the salinity of groundwater. Actions to counteract seawater intrusion are proposed.

  17. Interconnectivity between the Superficial Aquifer and the Deep Confined Aquifers of the Gnangara Mound, Western Australia

    International Nuclear Information System (INIS)

    Perth groundwater resources are obtained from three major aquifers that occur beneath the Perth metropolitan area: the Superficial aquifer, Leederville aquifer and Yarragadee aquifer. Each aquifer has a unique seasonal water level pattern controlled by soils, geomorphology and geology. Land use is mainly responsible for variations in recharge; however, the hydraulic properties control aquifer response and water level pattern to a greater degree. Groundwater in the three aquifers is generally of very good quality except in localised areas. Salinity increases with depth and in direction of groundwater flow in the three aquifers. The best water quality is in the Superficial aquifer in the Wanneroo well field area. The geochemistry and stable isotope signatures from the three major aquifers revealed distinct water types that suggest very little hydraulic connection or mixing of waters between these aquifers at the present abstraction and recharge regimes. The results also show that the Leederville and Yarragadee aquifers were recharged during earlier cooler times while the Superficial aquifer is being recharged at present

  18. Isotopes of helium, hydrogen, and carbon as groundwater tracers in aquifers along the Colorado River

    OpenAIRE

    Haber, Samuel Ainsworth

    2009-01-01

    Isotopes of hydrogen, carbon, helium, and neon in groundwater from 20 wells in the Lower Colorado River Valley (LCRV) are presented, with the aim of determining the age and mixing characteristics of the groundwater. Groundwaters from thirteen wells have measurable tritium and young ¹⁴C ages, suggesting mixing with at least a portion of recently-recharged (post-1952) groundwater. Groundwaters from the other seven wells are characterized as many thousands of years old and lack discernible triti...

  19. U-isotopes and (226)Ra as tracers of hydrogeochemical processes in carbonated karst aquifers from arid areas.

    Science.gov (United States)

    Guerrero, José Luis; Vallejos, Ángela; Cerón, Juan Carlos; Sánchez-Martos, Francisco; Pulido-Bosch, Antonio; Bolívar, Juan Pedro

    2016-07-01

    Sierra de Gádor is a karst macrosystem with a highly complex geometry, located in southeastern Spain. In this arid environment, the main economic activities, agriculture and tourism, are supported by water resources from the Sierra de Gádor aquifer system. The aim of this work was to study the levels and behaviour of some of the most significant natural radionuclides in order to improve the knowledge of the hydrogeochemical processes involved in this groundwater system. For this study, 28 groundwater and 7 surface water samples were collected, and the activity concentrations of the natural U-isotopes ((238)U, (235)U and (234)U) and (226)Ra by alpha spectrometry were determined. The activity concentration of (238)U presented a large variation from around 1.1 to 65 mBq L(-1). Elevated groundwater U concentrations were the result of oxidising conditions that likely promoted U dissolution. The PHREEQC modelling code showed that dissolved U mainly existed as uranyl carbonate complexes. The (234)U/(238)U activity ratios were higher than unity for all samples (1.1-3.8). Additionally, these ratios were in greater disequilibrium in groundwater than surface water samples, the likely result of greater water-rock contact time. (226)Ra presented a wide range of activity concentrations, (0.8 up to about 4 × 10(2) mBq L(-1)); greatest concentrations were detected in the thermal area of Alhama. Most of the samples showed (226)Ra/(234)U activity ratios lower than unity (median = 0.3), likely the result of the greater mobility of U than Ra in the aquifer system. The natural U-isotopes concentrations were strongly correlated with dissolution of sulphate evaporites (mainly gypsum). (226)Ra had a more complex behaviour, showing a strong correlation with water salinity, which was particularly evident in locations where thermal anomalies were detected. The most saline samples showed the lowest (234)U/(238)U activity ratios, probably due to fast uniform bulk mineral dissolution

  20. Hydrogeological properties of fault zones in a karstified carbonate aquifer (Northern Calcareous Alps, Austria)

    Science.gov (United States)

    Bauer, H.; Schröckenfuchs, T. C.; Decker, K.

    2016-03-01

    This study presents a comparative, field-based hydrogeological characterization of exhumed, inactive fault zones in low-porosity Triassic dolostones and limestones of the Hochschwab massif, a carbonate unit of high economic importance supplying 60 % of the drinking water of Austria's capital, Vienna. Cataclastic rocks and sheared, strongly cemented breccias form low-permeability (factor of 10 and fracture porosities varying by a factor of 3, and dilation breccias with average porosities >3 % and permeabilities >1,000 mD form high-permeability domains. With respect to fault-zone architecture and rock content, which is demonstrated to be different for dolostone and limestone, four types of faults are presented. Faults with single-stranded minor fault cores, faults with single-stranded permeable fault cores, and faults with multiple-stranded fault cores are seen as conduits. Faults with single-stranded impermeable fault cores are seen as conduit-barrier systems. Karstic carbonate dissolution occurs along fault cores in limestones and, to a lesser degree, dolostones and creates superposed high-permeability conduits. On a regional scale, faults of a particular deformation event have to be viewed as forming a network of flow conduits directing recharge more or less rapidly towards the water table and the springs. Sections of impermeable fault cores only very locally have the potential to create barriers.

  1. Hydrogeological properties of fault zones in a karstified carbonate aquifer (Northern Calcareous Alps, Austria)

    Science.gov (United States)

    Bauer, H.; Schröckenfuchs, T. C.; Decker, K.

    2016-08-01

    This study presents a comparative, field-based hydrogeological characterization of exhumed, inactive fault zones in low-porosity Triassic dolostones and limestones of the Hochschwab massif, a carbonate unit of high economic importance supplying 60 % of the drinking water of Austria's capital, Vienna. Cataclastic rocks and sheared, strongly cemented breccias form low-permeability (3 % and permeabilities >1,000 mD form high-permeability domains. With respect to fault-zone architecture and rock content, which is demonstrated to be different for dolostone and limestone, four types of faults are presented. Faults with single-stranded minor fault cores, faults with single-stranded permeable fault cores, and faults with multiple-stranded fault cores are seen as conduits. Faults with single-stranded impermeable fault cores are seen as conduit-barrier systems. Karstic carbonate dissolution occurs along fault cores in limestones and, to a lesser degree, dolostones and creates superposed high-permeability conduits. On a regional scale, faults of a particular deformation event have to be viewed as forming a network of flow conduits directing recharge more or less rapidly towards the water table and the springs. Sections of impermeable fault cores only very locally have the potential to create barriers.

  2. Monitoring carbon dioxide injection and storage in aquifers and depleted oilfields using carbon and sulfur isotope techniques

    International Nuclear Information System (INIS)

    Fluid and gas monitoring can be used to confirm the security and integrity of geological CO2 storage. The distinct carbon isotopic composition of CO2 from many industrial sources that process or combust hydrocarbons allows the use of isotopic and chemical analyses of produced fluids and gases to trace the injected CO2 and quantify CO2 storage processes in the subsurface. Our four year monitoring programme at the International Energy Agency Weyburn CO2 Monitoring and Storage Project in Saskatchewan, Canada, featured frequent chemical and isotopic measurements of produced fluids and gases from around forty wells. Over the four year period, over four million tonnes of CO2 were injected for storage and enhanced hydrocarbon recovery in the Weyburn oilfield. CO2 concentration and carbon isotopic measurements of produced fluids and gases trace CO2, and confirm that the order of magnitude increase in the amount of CO2 in the subsurface resulted from CO2 injection. The amount of CO2 stored as HCO3- can be quantified using HCO3- concentration and carbon isotopic measurements, while concentration and isotope data for SO42- and H2S indicate that bacterial sulfate reduction was not a major source of HCO3- . To allow widespread application of geological CO2 storage, reliable, cost effective monitoring of storage integrity will be essential. The produced fluid and gas monitoring techniques described here are based on chemical and isotopic techniques that are already widely employed and well understood by environmental isotope hydrologists, and have the potential to play an essential role in future geological CO2 storage monitoring programmes. (author)

  3. Monitoring carbon dioxide injection and storage in aquifers and depleted oilfields using carbon and sulfur isotope techniques

    International Nuclear Information System (INIS)

    Fluid and gas monitoring can be used to confirm the security and integrity of geological CO2 storage. The distinct carbon isotopic composition of CO2 from many industrial sources that process or combust hydrocarbons allows the use of isotopic and chemical analyses of produced fluids and gases to trace the injected CO2 and quantify CO2 storage processes in the subsurface. Our four year monitoring programme at the International Energy Agency Weyburn CO2 Monitoring and Storage Project in Saskatchewan, Canada, featured frequent chemical and isotopic measurements of produced fluids and gases from around forty wells. Over the four year period, over four million tonnes of CO2 were injected for storage and enhanced hydrocarbon recovery in the Weyburn Oilfield. CO2 concentration and carbon isotopic measurements of produced fluids and gases trace CO2, and confirm that the order of magnitude increase in the amount of CO2 in the subsurface resulted from CO2 injection. The amount of CO2 stored as HCO3- can be quantified using HCO3- concentration and carbon isotopic measurements, while concentration and isotope data for SO42- and H2S indicate that bacterial sulfate reduction was not a major source of HCO3-. To allow widespread application of geological CO2 storage, reliable, cost effective monitoring of storage integrity will be essential. The produced fluid and gas monitoring techniques described here are based on chemical and isotopic techniques that are already widely employed and well understood by environmental isotope hydrologists, and have the potential to play an essential role in future geological CO2 storage monitoring programmes. (author)

  4. Geochemical and Mineralogical Investigation for Carbon Capture and Storage, Within the Arbuckle Aquifer, Kansas

    Science.gov (United States)

    Datta, S.; Campbell, B.; Vega, M.; Barker, R. L.; Holubnyak, E.; Watney, W. L.

    2013-12-01

    A class VI permit site under U.S. Department of Energy has been proposed for carbon sequestration in south-central Kansas. In an effort to maintain environmental stability three wells have been drilled to basement rock, two being near the injection site, KGS 1-32 and KGS 1-28, and one being to the western annex, Cutter KGS #1. The western annex site, Cutter, is being utilized as a cross-comparison for mineralogical, geochemical, and structural component to the eastern sites in Wellington. A link will be determined of the continuity of three zones of interest: the Mississippian pay zone (3670'-3700'), a potential baffle zone in the upper Arbuckle (4400'-4550'), and the proposed CO2 injection zone (4900'-5050'). 11 depths within Cutter have been swabbed, and samples taken to investigate the chemistry of the subsurface formation water. The different depths will allow for a quantitative determination of how the brine composition varies with depth, and also provides a baseline for future monitoring. Initial chemical analysis by ICP-OES and HR-ICP-MS show a hyper saline brine (50,000-190,000TDS), dominated by Cl, Na, and Ca ions. pH ranges from 6.4 to 7.5, and total alkalinity from 124 and 378 mg/L of HCO¬3-. One complex, yet intriguing, species is Iron. It could potentially allow for further precipitation of the CO2¬ from the formation of Fe carbonates, such as siderite. Cores and thin sections were taken from a variety of depths ranging from 3681.9' to 5176.9' (Wellington) and 5564.3' to 7540.2' (Cutter). Dominant mineralogy consists of dolomite with varying forms of silicic intrusions, usually in the form of chert nodules with sulfide minerals and argillaceous materials in between. Extensive vugs and microfractures allow for varying porosity within each interval. Pay zone rocks typically display fine-grained cherty dolomite with subhedral to euhedral dolomite rhombs as well as oil stains oriented in parallel blotches. Characteristics such as high porosity and small

  5. An evaluation of aquifer intercommunication between the unconfined and Rattlesnake Ridge aquifers on the Hanford Site

    International Nuclear Information System (INIS)

    During 1986, Pacific Northwest Laboratory conducted a study of a portion of the Rattlesnake Ridge aquifer (confined aquifer) that lies beneath the B Pond - Gable Mountain Pond area of the Hanford Site. The purpose was to determine the extent of intercommunication between the unconfined aquifer and the uppermost regionally extensive confined aquifer, referred to as the Rattlesnake Ridge aquifer. Hydraulic head data and chemical data were collected from the ground water in the study area during December 1986. The hydraulic head data were used to determine the effects caused by water discharged to the ground from B Pond on both the water table of the unconfined aquifer and the potentiometric surface of the confined aquifer. The chemical data were collected to determine the extent of chemical constituents migrating from the unconfined aquifer to the confined aquifer. Analysis of chemical constituents in the Rattlesnake Ridge aquifer demonstrated that communication between the unconfined and confined aquifers had occurred. However, the levels of contaminants found in the Rattlesnake Ridge aquifer during this study were below the DOE Derived Concentration Guides

  6. Influence of Carbon and Microbial Community Priming on the Attenuation of Uranium in a Contaminated Floodplain Aquifer

    Energy Technology Data Exchange (ETDEWEB)

    Mouser, Paula J.; N' Guessan, A. Lucie; Qafoku, Nikolla; Sinha, M.; Williams, K. H.; Dangelmayr, M.; Resch, Charles T.; Peacock, Aaron D.; Wang, Zheming; Figueroa, Linda A.; Long, P. E.

    2015-07-01

    The capacity for subsurface sediments to sequester metal contaminants, such as uranium (U), and retain them after bioremediation efforts are completed is critical to site stewardship. Sediments enriched in natural organic matter are capable of sequestering significant quantities of U, but may also serve as sources to the aquifer, contributing to plume persistence. Two types of sediments were compared to better understand the mechanisms contributing to the sequestration and release of U in the presence of organic matter. Artificially bioreduced sediments were retrieved from a field experimental plot previously stimulated with acetate while naturally bioreduced sediments were collected from a location enriched in organic matter but never subject to acetate amendment. Batch incubations demonstrated that the artificially bioreduced sediments were primed to rapidly remove uranium from the groundwater whereas naturally bioreduced sediments initially released a sizeable portion of sediment U before U(VI)-removal commenced. Column experiments confirmed that U release persisted for 65 pore volumes in naturally bioreduced sediments, demonstrating the sink-source behavior of this sediment. Acetate addition to artificially bioreduced sediments shifted the microbial community from one dominated by sulfate-reducing bacteria within Desulfobacteraceae to the iron-reducing family Geobacteraceae and Firmicutes during U(VI) reduction. In contrast, initial Geobacteraceae communities innaturally reduced sediments were replaced by clone sequences with similarity to opportunistic Pseudomonas spp. during U release, while U(VI) removal occurred concurrent with enrichment of Firmicutes. These investigations stress the importance of characterizing zones with heterogeneous carbon pools at U contaminated sites prior to the determination of a remedial strategy.

  7. Assessing Connectivity Between an Overlying Aquifer and a Coal Seam Gas Resource Using Methane Isotopes, Dissolved Organic Carbon and Tritium

    OpenAIRE

    Iverach, Charlotte P.; Cendón, Dioni I.; Hankin, Stuart I.; David Lowry; Fisher, Rebecca E.; France, James L.; Nisbet, Euan G; Andy Baker; Kelly, Bryce F. J.

    2015-01-01

    Coal seam gas (CSG) production can have an impact on groundwater quality and quantity in adjacent or overlying aquifers. To assess this impact we need to determine the background groundwater chemistry and to map geological pathways of hydraulic connectivity between aquifers. In south-east Queensland (Qld), Australia, a globally important CSG exploration and production province, we mapped hydraulic connectivity between the Walloon Coal Measures (WCM, the target formation for gas production) an...

  8. Modeling groundwater levels on the Calera Aquifer Region in Central Mexico using ModFLow.

    Science.gov (United States)

    A conceptual model for the Calera Aquifer has been created to represent the aquifer system beneath the Calera Aquifer Region (CAR) in the State of Zacatecas, Mexico. The CAR area was uniformly partitioned into a 500 X 500 m grid generating a high resolution model that represented the natural boundar...

  9. Up-Scaling Geochemical Reaction Rates for Carbon Dioxide (CO2) in Deep Saline Aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Peters, Catherine A

    2013-02-28

    Geochemical reactions in deep subsurface environments are complicated by the consolidated nature and mineralogical complexity of sedimentary rocks. Understanding the kinetics of these reactions is critical to our ability to make long-term predictions about subsurface processes such as pH buffering, alteration in rock structure, permeability changes, and formation of secondary precipitates. In this project, we used a combination of experiments and numerical simulation to bridge the gap between our knowledge of these reactions at the lab scale and rates that are meaningful for modeling reactive transport at core scales. The focus is on acid-driven mineral dissolution, which is specifically relevant in the context of CO2-water-rock interactions in geological sequestration of carbon dioxide. The project led to major findings in three areas. First, we modeled reactive transport in pore-network systems to investigate scaling effects in geochemical reaction rates. We found significant scaling effects when CO2 concentrations are high and reaction rates are fast. These findings indicate that the increased acidity associated with geological sequestration can generate conditions for which proper scaling tools are yet to be developed. Second, we used mathematical modeling to investigate the extent to which SO2, if co-injected with CO2, would acidify formation brines. We found that there exist realistic conditions in which the impact on brine acidity will be limited due to diffusion rate-limited SO2 dissolution from the CO2 phase, and the subsequent pH shift may also be limited by the lack of availability of oxidants to produce sulfuric acid. Third, for three Viking sandstones (Alberta sedimentary basin, Canada), we employed backscattered electron microscopy and energy dispersive X-ray spectroscopy to statistically characterize mineral contact with pore space. We determined that for reactive minerals in sedimentary consolidated rocks, abundance alone is not a good predictor of

  10. Groundwater flow in an `underfit' carbonate aquifer in a semiarid climate: application of environmental tracers to the Salt Basin, New Mexico (USA)

    Science.gov (United States)

    Sigstedt, Sophia C.; Phillips, Fred M.; Ritchie, Andre B. O.

    2016-06-01

    The Salt Basin is a semiarid hydrologically closed drainage basin in southern New Mexico, USA. The aquifers in the basin consist largely of Permian limestone and dolomite. Groundwater flows from the high elevations (˜2,500 m) of the Sacramento Mountains south into the Salt Lakes, which are saline playas. The aquifer is `underfit' in the sense that depths to groundwater are great (˜300 m), implying that the aquifer could transmit much more water than it does. In this study, it is speculated that this characteristic is a result of a geologically recent reduction in recharge due to warming and drying at the end of the last glacial period. Water use is currently limited, but the basin has been proposed for large-scale groundwater extraction and export projects. Wells in the basin are of limited utility for hydraulic testing; therefore, the study focused on environmental tracers (major-ion geochemistry, stable isotopes of O, H, and C, and 14C dating) for basin analysis. The groundwater evolves from a Ca-HCO3 type water into a Ca-Mg (Na) - HCO3-Mg (Cl) water as it flows toward the center of the basin due to dedolomitization driven by gypsum dissolution. Carbon-14 ages corrected for dedolomitization ranged from less than 1,000 years in the recharge area to 19,000 years near the basin center. Stable isotopes are consistent with the presence of glacial-period recharge that is much less evaporated than modern. This supports the hypothesis that the underfit nature of the aquifer is a result of a geologically recent reduction in recharge.

  11. Groundwater flow in an `underfit' carbonate aquifer in a semiarid climate: application of environmental tracers to the Salt Basin, New Mexico (USA)

    Science.gov (United States)

    Sigstedt, Sophia C.; Phillips, Fred M.; Ritchie, Andre B. O.

    2016-04-01

    The Salt Basin is a semiarid hydrologically closed drainage basin in southern New Mexico, USA. The aquifers in the basin consist largely of Permian limestone and dolomite. Groundwater flows from the high elevations (˜2,500 m) of the Sacramento Mountains south into the Salt Lakes, which are saline playas. The aquifer is `underfit' in the sense that depths to groundwater are great (˜300 m), implying that the aquifer could transmit much more water than it does. In this study, it is speculated that this characteristic is a result of a geologically recent reduction in recharge due to warming and drying at the end of the last glacial period. Water use is currently limited, but the basin has been proposed for large-scale groundwater extraction and export projects. Wells in the basin are of limited utility for hydraulic testing; therefore, the study focused on environmental tracers (major-ion geochemistry, stable isotopes of O, H, and C, and 14C dating) for basin analysis. The groundwater evolves from a Ca-HCO3 type water into a Ca-Mg (Na) - HCO3-Mg (Cl) water as it flows toward the center of the basin due to dedolomitization driven by gypsum dissolution. Carbon-14 ages corrected for dedolomitization ranged from less than 1,000 years in the recharge area to 19,000 years near the basin center. Stable isotopes are consistent with the presence of glacial-period recharge that is much less evaporated than modern. This supports the hypothesis that the underfit nature of the aquifer is a result of a geologically recent reduction in recharge.

  12. Lattice Boltzmann methods applied to large-scale three-dimensional virtual cores constructed from digital optical borehole images of the karst carbonate Biscayne aquifer in southeastern Florida

    Science.gov (United States)

    Sukop, Michael C.; Cunningham, Kevin J.

    2014-11-01

    Digital optical borehole images at approximately 2 mm vertical resolution and borehole caliper data were used to create three-dimensional renderings of the distribution of (1) matrix porosity and (2) vuggy megaporosity for the karst carbonate Biscayne aquifer in southeastern Florida. The renderings based on the borehole data were used as input into Lattice Boltzmann methods to obtain intrinsic permeability estimates for this extremely transmissive aquifer, where traditional aquifer test methods may fail due to very small drawdowns and non-Darcian flow that can reduce apparent hydraulic conductivity. Variogram analysis of the borehole data suggests a nearly isotropic rock structure at lag lengths up to the nominal borehole diameter. A strong correlation between the diameter of the borehole and the presence of vuggy megaporosity in the data set led to a bias in the variogram where the computed horizontal spatial autocorrelation is strong at lag distances greater than the nominal borehole size. Lattice Boltzmann simulation of flow across a 0.4 × 0.4 × 17 m (2.72 m3 volume) parallel-walled column of rendered matrix and vuggy megaporosity indicates a high hydraulic conductivity of 53 m s-1. This value is similar to previous Lattice Boltzmann calculations of hydraulic conductivity in smaller limestone samples of the Biscayne aquifer. The development of simulation methods that reproduce dual-porosity systems with higher resolution and fidelity and that consider flow through horizontally longer renderings could provide improved estimates of the hydraulic conductivity and help to address questions about the importance of scale.

  13. Evolution of porosity in the saltwater freshwater mixing zone of coastal carbonate aquifers: An alternative modelling approach

    Science.gov (United States)

    Romanov, Douchko; Dreybrodt, Wolfgang

    2006-10-01

    SummaryDissolution of calcium carbonate in the saltwater-freshwater mixing zone in carbonate islands and coastal aquifers up to now has been treated by coupling geochemical equilibrium programmes to a reactive-transport model. The result is a complex nonlinearly coupled set of differential transport-advection equations, which need high computational efforts. If dissolution rates of calcite are sufficiently fast, such that one can assume the solution to be in equilibrium with respect to calcite a highly simplified modelling approach can be used. By use of the concept of Phillips in his book: Flow and Reactions in Permeable Rock, Cambridge University Press, New York (1991) and its more general formulation by De Simoni et al. [De Simoni, M., Carrera, J., Sánchez-Vila, X., Guadagnini, A., 2005. A procedure for the solution of multicomponent reactive transport problems, Water Resource Research, 41, W11410.], it is possible to decouple the complex set of equations. To calculate initial changes of porosity in the rock matrix one needs solely to solve the advection-transport equation for salinity s. Current codes on density driven flow such as SEAWAT can be used. To obtain the dissolution capacity of the mixed saltwater-freshwater solution the calcium equilibrium concentration ceq( s) is obtained as a function of salinity by PHREEQC-2. Initial porosity changes can then be calculated by a simple analytical expression of the gradient of the spatial distribution s( x, y) of salinity, the distribution of flow fluxes q( x, y) and the second derivative of the calcium equilibrium concentration ceq( s) with respect to salinity s. This approach does no longer require large dispersivities on the order of meters; but reasonable results are obtained with dispersivity on the scale of the pore size of the porous rock, which correctly describes mixing on the molecular scale. The method is applied to a simple 1-D-domain without convective flow and a constant gradient of salinity as

  14. Hydrogeological properties of fault zones in a karstified carbonate aquifer and their impact on groundwater circulation (Northern Calcareous Alps, Austria)

    Science.gov (United States)

    Bauer, Helene; Schröckenfuchs, Theresa Christina; Decker, Kurt

    2016-04-01

    This study presents a comparative, field-based hydrogeological characterization of exhumed, inactive fault zones in low porosity Triassic dolostones and limestones of the Hochschwab massif, a carbonate unit of high economic importance supplying 60% of the drinking water of Austria`s capital Vienna. The hydrogeology (groundwater storage and flow) of the massif has been reported to be essentially governed by karstified, large-scale faults. Previous work has shown that faults that formed during the Oligocene to Miocene lateral extrusion of the Eastern Alps act as groundwater pathways draining the karst massif preferably in E-W-direction. We present hydrogeological relevant data from these types of fault zones and a conceptual model, which supports the idea that fault-zone networks also have the potential to contribute significantly to the storage capacity of the aquifer. With respect to fault zone architecture and rock content, four types of faults are presented: (1) faults with single stranded, minor fault cores, (2) faults with single stranded, permeable fault cores, (3) faults with single stranded, impermeable fault cores, and (4) faults with multiple stranded, permeable fault cores. Within these faults cataclastic rocks and strongly cemented cataclastic breccias form low-permeability (factor of 10 show significantly elevated porosities (> 3%) with respect to the country rock ( 3% and permeabilities > 1000 mD form high-permeability domains. Our data illustrates significant differences in the architectural build-up of fault zones in dolostone (multiple-stranded cataclastic fault cores of weak lateral continuity, high volumes of intensely fractured rock) and limestone (laterally distinct, single-stranded fault cores, Riedel-shear fractures dominating fracture patterns). Karstic carbonate dissolution occurs preferentially along faults cores in limestones and, to a lesser degree, dolostones creating superposed high-permeability conduits. All faults contain domains of

  15. Hydrogeological properties of fault zones in a karstified carbonate aquifer and their impact on groundwater circulation (Northern Calcareous Alps, Austria)

    Science.gov (United States)

    Bauer, Helene; Schröckenfuchs, Theresa Christina; Decker, Kurt

    2016-04-01

    This study presents a comparative, field-based hydrogeological characterization of exhumed, inactive fault zones in low porosity Triassic dolostones and limestones of the Hochschwab massif, a carbonate unit of high economic importance supplying 60% of the drinking water of Austria`s capital Vienna. The hydrogeology (groundwater storage and flow) of the massif has been reported to be essentially governed by karstified, large-scale faults. Previous work has shown that faults that formed during the Oligocene to Miocene lateral extrusion of the Eastern Alps act as groundwater pathways draining the karst massif preferably in E-W-direction. We present hydrogeological relevant data from these types of fault zones and a conceptual model, which supports the idea that fault-zone networks also have the potential to contribute significantly to the storage capacity of the aquifer. With respect to fault zone architecture and rock content, four types of faults are presented: (1) faults with single stranded, minor fault cores, (2) faults with single stranded, permeable fault cores, (3) faults with single stranded, impermeable fault cores, and (4) faults with multiple stranded, permeable fault cores. Within these faults cataclastic rocks and strongly cemented cataclastic breccias form low-permeability ( 3%) with respect to the country rock ( 3% and permeabilities > 1000 mD form high-permeability domains. Our data illustrates significant differences in the architectural build-up of fault zones in dolostone (multiple-stranded cataclastic fault cores of weak lateral continuity, high volumes of intensely fractured rock) and limestone (laterally distinct, single-stranded fault cores, Riedel-shear fractures dominating fracture patterns). Karstic carbonate dissolution occurs preferentially along faults cores in limestones and, to a lesser degree, dolostones creating superposed high-permeability conduits. All faults contain domains of brecciated and highly fractured rocks along their

  16. Big burp : Enbridge is using its pipeline and compression expertise to spearhead a project that would pump massive volumes of carbon dioxide into salt water aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Collison, M.

    2008-05-15

    The transportation and sequestration of carbon dioxide (CO{sub 2}) may soon become a large commercial enterprise. This article described a joint project formed by Enbridge and the Alberta Saline Aquifer Project (ASAP) to divert CO{sub 2} from the atmosphere. ASAP will collect, purify, and dehydrate the CO{sub 2} as well as compress it into a liquid and inject it into underground reservoirs of salt water. Carbon capture and storage (CCS) is seen as an appropriate method of storing CO{sub 2} as the oil and gas industry can use its expertise to transport and compress the gas. Enbridge has also been involved for the last 5 years in the Hardisty Caverns salt cavern project. Lined underground salt caverns near the Hardisty terminal are used to store millions of barrels of crude oil. There is currently no regulatory environment in place for CCS projects, despite the fact that extensive groundwork is now being laid for a long-term large-scale integrated CCS system. Representative CO{sub 2} sources are currently also being evaluated in order to evaluate what is required to aggregate different types of CO{sub 2}. Saline aquifers have been selected by ASAP as they are abundant in Alberta. A task force has been created to consider routes and use of existing rights of way and corridors in order to build new pipelines. It was concluded that CCS has the potential to enable hydrocarbon production with reduced environmental impacts. 4 figs.

  17. Ozark Aquifer

    Data.gov (United States)

    Kansas Data Access and Support Center — These digital maps contain information on the altitude of the base and top, the extent, and the potentiometric surface of the Ozark aquifer in Kansas. The Ozark...

  18. Isotopes as Tracers of Water Origin in and Near a Regional Carbonate Aquifer: The Southern Sacramento Mountains, New Mexico

    OpenAIRE

    Christopher J. Eastoe; Ryan Rodney

    2014-01-01

    High-elevation groundwater sampled in 2003 in the Sacramento Mountains defines a line resembling an evaporation trend in δD-δ18O space. The trend results from recharge of winter precipitation into fractured limestone, with evaporation prior to recharge in broad mountain valleys. The same trend occurs in basin groundwater east and west of the range, indicating the high Sacramento Mountains as the principal regional water source, either direct from the limestone aquifers or from mountain-derive...

  19. Approaches to Quantify Potential Contaminant Transport in the Lower Carbonate Aquifer from Underground Nuclear Testing at Yucca Flat, Nevada National Security Site, Nye County, Nevada - 12434

    International Nuclear Information System (INIS)

    Quantitative modeling of the potential for contaminant transport from sources associated with underground nuclear testing at Yucca Flat is an important part of the strategy to develop closure plans for the residual contamination. At Yucca Flat, the most significant groundwater resource that could potentially be impacted is the Lower Carbonate Aquifer (LCA), a regionally extensive aquifer that supplies a significant portion of the water demand at the Nevada National Security Site, formerly the Nevada Test Site. Developing and testing reasonable models of groundwater flow in this aquifer is an important precursor to performing subsequent contaminant transport modeling used to forecast contaminant boundaries at Yucca Flat that are used to identify potential use restriction and regulatory boundaries. A model of groundwater flow in the LCA at Yucca Flat has been developed. Uncertainty in this model, as well as other transport and source uncertainties, is being evaluated as part of the Underground Testing Area closure process. Several alternative flow models of the LCA in the Yucca Flat/Climax Mine CAU have been developed. These flow models are used in conjunction with contaminant transport models and source term models and models of contaminant transport from underground nuclear tests conducted in the overlying unsaturated and saturated alluvial and volcanic tuff rocks to evaluate possible contaminant migration in the LCA for the next 1,000 years. Assuming the flow and transport models are found adequate by NNSA/NSO and NDEP, the models will undergo a peer review. If the model is approved by NNSA/NSO and NDEP, it will be used to identify use restriction and regulatory boundaries at the start of the Corrective Action Decision Document Corrective Action Plan (CADD/CAP) phase of the Corrective Action Strategy. These initial boundaries may be revised at the time of the Closure Report phase of the Corrective Action Strategy. (authors)

  20. Guarani aquifer

    International Nuclear Information System (INIS)

    The environmental protection and sustain ability develop project of Guarani Aquifer System is a join work from Argentina, Brazil, Paraguay and Uruguay with a purpose to increase the knowledge resource and propose technical legal and organizational framework for sustainable management between countries.The Universities funds were created as regional universities support in promotion, training and academic research activities related to environmental al social aspects of the Guarani Aquifer System.The aim of the project is the management and protection of the underground waters resources taking advantage and assesment for nowadays and future generations

  1. Isotopic evidence for induced river recharge to the Dupi Tila aquifer in the Dhaka urban area, Bangladesh

    International Nuclear Information System (INIS)

    The population of the greater Dhaka metropolitan area is over 8 million and growing at a rate of six percent per year. Much of the water supply for the area is obtained from the underlying Dupi Tila sand aquifer. Intensive exploitation of the aquifer has led to a progressive decline in water levels beneath the parts of the city. The resulting cone of depression is thought likely to be causing the infiltration of surface water, largely from the polluted Buriganga waterway. The use of oxygen and hydrogen stable isotopes in unravelling the subsurface hydrology of the Dhaka area is hindered by the lack of data regarding 'baseline' conditions. Nevertheless it is clear from the evidence obtained from tubewells across the city that there is leakage from the Buriganga river extending several kilometres beneath parts of the urban area, possibly as far as the centre of the city. Carbon stable isotopes and major ion chemistry confirm this general picture; though appear to indicate that polluted river water has not penetrated quite so far towards the city centre. The Dupi Tila is regarded as a multi-layer aquifer on the basis of its hydrogeology and water quality variations with depth. Since there is little stable isotopic evidence for stratification, future investigations should include sensitive recent age indicators to investigate this, and the rates of groundwater movement in general. (author)

  2. Bioremediation of RDX in the vadose zone beneath the Pantex Plant

    Energy Technology Data Exchange (ETDEWEB)

    Shull, T.L.; Speitel, G.E. Jr.; McKinney, D.C. [Univ. of Texas, Austin, TX (United States). Dept. of Civil Engineering

    1999-01-01

    The presence of dissolved high explosives (HE), in particular RDX and HMX, is well documented in the perched aquifer beneath the Pantex Plant, but the distribution of HE in the vadose zone has not yet been well defined. Although current remediation activities focus on the contamination in the perched aquifer, eventually regulatory concern is likely to turn to the residual contamination in the vadose zone. Sources of HE include the infiltration of past wastewater discharges from several HE-processing facilities through the ditch drainage system and leachate from former Landfill 3. With limited existing data on the HE distribution in the vadose zone and without preventive action, it must be assumed that residual HE could be leached into infiltrating water, providing a continuing supply of contamination to the perched aquifer. The purpose of this project was to more closely examine the fate and transport of HE in the vadose zone through mathematical modeling and laboratory experimentation. In particular, this report focuses on biodegradation as one possible fate of HE. Biodegradation of RDX in the vadose zone was studied because it is both present in highest concentration and is likely to be of the greatest regulatory concern. This study had several objectives: determine if indigenous soil organisms are capable of RDX biodegradation; determine the impact of electron acceptor availability and nutrient addition on RDX biodegradation; determine the extent of RDX mineralization (i.e., conversion to inorganic carbon) during biodegradation; and estimate the kinetics of RDX biodegradation to provide information for mathematical modeling of fate and transport.

  3. Soil-Gas Identification of Environmental Factors Affecting CO2 Concentrations Beneath a Playa Wetland: Implications for Soil-Gas Monitoring at Carbon Storage Sites

    Science.gov (United States)

    Romanak, K.; Bennett, P.

    2009-12-01

    Strategies for identifying and interpreting the effects of environmental factors on near-surface CO2 concentrations are essential to developing accurate monitoring protocols at carbon storage sites. Based on the results of a three-year study of a natural analogue we present, 1) a method for using soil-gas to identify near-surface CO2 cycling, and 2) a framework for developing monitoring protocols and site evaluation for near-surface monitoring. Near-surface CO2 production, consumption, and re-distribution was observed in the vadose-zone of a highly CO2-reactive playa wetland in the Texas High Plains. Atmospheric conditions, organic and inorganic soil carbon, subsurface pressure, water flux, and surface and groundwater chemistry were compared to real-time background measurements of CO2, CH4, O2+Ar, and N2 from depths up to 45 feet. Carbon isotopes and spatially and temporally variable concentrations of CO2 ≤ 17%, CH4 ≤ 2%, and O2 from 21-0% indicate CO2 and CH4 are produced by microbes. Molar gas ratios of O2 and CO2 distinguish between oxidation of organic matter (CH2O + O2 → CO2 + H2O), CH4 oxidation (CH4 + 2O2 → CO2 + 2H2O), and potentially acetate fermentation (CH3COOH → CH4 + CO2). O2 consumption and distribution is regulated by water flux that supplies dissolved organics to microbes at depth and regulates oxygen supply by blocking vertical permeability and atmospheric gas exchange. A surface flux experiment indicates that when playa floors are dry, subsurface wetting fronts from rain events or previous ponding periods block vertical permeability resulting in surface flux measurements that do not represent subsurface conditions. Samples with CO2+O2 78% identify dissolution of CO2 and carbonate minerals into recharging groundwater resulting in loss of pore pressure and chemically-induced advection of atmosphere into pores. Inverse geochemical reaction modeling (PHREEQC) of playa surface water and perched groundwater in high PCO2 zones support

  4. Water-rock-CO2 interactions in saline aquifers aimed for carbon dioxide storage: Experimental and numerical modeling studies of the Rio Bonito Formation (Permian), southern Brazil

    International Nuclear Information System (INIS)

    Mineral trapping is one of the safest ways to store CO2 underground as C will be immobilized in a solid phase. Carbon dioxide will be, therefore, sequestered for geological periods of time, helping to diminish greenhouse gas emissions and mitigate global warming. Although mineral trapping is considered a fairly long process, owing to the existence of kinetic barriers for mineral precipitation, it has been demonstrated both experimentally and by numerical modeling. Here the results of experimental and numerical modeling studies performed in sandstones of the saline aquifer of the Rio Bonito Formation, Parana Basin, are presented. The Rio Bonito Formation consists of paralic sandstones deposited in the intracratonic Parana Basin, southern Brazil, during the Permian (Artinskian-Kungurian). These rocks have the largest potential for CO2 storage because of their appropriated reservoir quality, depth and proximity to the most important stationary CO2 sources in Brazil. Here it is suggested that CO2 can be permanently stored as carbonates as CO2 reacts with rocks of the Rio Bonito Formation and forms CaCO3 at temperatures and pressures similar to those encountered for CO2 storage in geological formations. Results of this work will be useful for studies of partitioning mechanisms for C trapping in CO2 storage programs.

  5. Geological factors affecting the chemical characteristics of the thermal waters of the carbonate karstified aquifers of Northern Vietnam

    OpenAIRE

    Drogue, C.; Cat, N. N.; Dazy, J.

    2000-01-01

    In northern Vietnam, exposed carbonate rock formations cover an area of more than 50,000 km2 .Their accumulated thickness from the Cambrian to the Triassic is in some places as much as 3000 m. Numerous thermal waters (springs and wells) occur in these strongly karstified carbonate massifs. This is the result of significant ancient and present orogenic activity, as the region demonstrates by its strong seismic activity. These karstic formations are water-bearing and strongly recharge...

  6. Geological factors affecting the chemical characteristics of the thermal waters of the carbonate karstified aquifers of Northern Vietnam

    OpenAIRE

    Drogue, C.; Cat, N. N.; Dazy, J.

    2002-01-01

    In northern Vietnam, exposed carbonate rock formations cover an area of more than 50,000 km2 .Their accumulated thickness from the Cambrian to the Triassic is in some places as much as 3000 m. Numerous thermal waters (springs and wells) occur in these strongly karstified carbonate massifs. This is the result of significant ancient and present orogenic activity, as the region demonstrates by its strong seismic activity. These karstic ...

  7. Impact of CO2 concentration on autotrophic metabolisms and carbon fate in saline aquifers - A case study

    Science.gov (United States)

    Dupraz, Sebastien; Fabbri, Antonin; Joulian, Catherine; Dictor, Marie-Christine; Battaglia-Brunet, Fabienne; Ménez, Bénédicte; Crouzet, Catherine; Henry, Benoît; Garrido, Francis

    2013-10-01

    The purpose of this study was to identify and quantify the fate and speciation of carbon that can occur in mixtures of geological media (crushed rock) and autotrophic microbial communities. A sulfate reducing bacterium (Desulfotomaculum geothermicum) and a methanogenic archaeon (Methanothermococcus thermolithotrophicus) were both tested separately and together, with and without crushed sedimentary rock (carbonaceous sandstone) for different CO2 partial pressures (0.22, 0.88, 3.52, and 8 bar) at 54 °C in saline artificial groundwater. In order to quantify the respective metabolic activities, the inorganic gases of interest (H2, CH4, H2S and CO2) were measured and the speciation of carbon was assessed by measuring volatile, non-purgeable, total and dissolved organic carbon as well as total and dissolved inorganic carbon. Despite a protective effect of the mineral matrix, the results showed a high sensitivity of autotrophic microorganisms to the stress induced by pressures of CO2 superior to one bar and revealed that a part of this stress was due to direct toxic effects. M. thermolithotrophicus demonstrated a better tolerance to CO2 and was dominating the consortia. This ascendancy was interpreted as resulting from equilibrium displacement due to transport effects of methane between the liquid and gas phases. Abiotic dissolution was observed but some biomineralization processes of carbonates were also identified for D. geothermicum. Both strains displayed very different patterns in their conversion of inorganic carbon: while M. thermolithotrophicus was mainly producing methane, D. geothermicum induced the formation of biomass. The availability of crushed rock increased the proportion of sessile biofilms. All these results were analyzed in correlation with a successful PHREEQC simulation and demonstrate the strong influence of the microbial activities and diversity on the carbon fate in the immediate surroundings of geological CCS storage zones.

  8. Development of Kinetic Interface Sensitive Tracers (KIS-Tracer) for Supercritical Carbon Dioxide Injections into Deep Saline Aquifers

    Science.gov (United States)

    Schaffer, M.; Maier, F.; Licha, T.; Sauter, M.

    2012-04-01

    The storage of captured CO2 into geological formations is recently one of the most promising technologies to mitigate anthropogenic greenhouse gas emissions into the earth's atmosphere. Deep saline aquifers are considered as the most potential sequestration sites of CO2 due to their huge storage capacities of several thousand Gt. Ongoing research deals mainly with the investigation of relevant physico-chemical processes, the fate of CO2 and the risk assessment during and after supercritical CO2 (scCO2) injections. The occurring processes at the interface between injected scCO2 and formation brine play a major role to evaluate the fate and behavior of scCO2 in the reservoir. This is because the interface represents a reactive zone where numerous physico-chemical processes like dissolution of scCO2 in water as well as dissolution and precipitation of minerals take place. In most cases it is desired to maximize the interface size to increase the storage efficiency. Therefore, knowledge on interface size and dynamics would allow the observation of plume spreading and the detection of mixing or fingering effects. In order to gain this information innovative tracers are necessary which are able to quantify the temporal and spatial development of scCO2/water interfaces. As a result, it may be possible to assess the storage efficiency and to optimize subsequent injections. Up to now, such time-dependent tracers for reservoir studies are not available and limited to equilibrium tracers (known as partitioning and interfacial tracers, respectively). Therefore, novel reactive tracers (KIS-Tracers) are developed to overcome this gap. The idea is to find suitable molecules which allow the implementation of a defined chemical reaction at the interface. Due to the known kinetic constants the change of interface size can be characterized over time. The new tracer is injected together with the supercritical CO2 (scCO2) into a deep saline aquifer. Afterwards, the tracer adsorbs at

  9. Comparative analysis of the evaluation of the intrinsic vulnerability in carbonate aquifers (Canete Mountain Range, province of Malaga); Analisis comparativo de la evaluacion de la vulnerabilidad intrinseca de acuiferos carbonaticos (Sierra de Canete, provincia de Malaga)

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez Madrid, A.; Carrasco Cantos, F.; Martinez Navarrete, C.

    2009-07-01

    Groundwater of the carbonate aquifers of Canete Mountain Range constitute a basic source for water supply to different populations. Vulnerability intrinsic assesment is one of the most useful tools for the protection of the groundwater bodies, for this reason, this area has been chosen, to realize a comparative analysis, by means of the use of tools of spatial analysis and technical statistics of a Geographical Information System. In this work, Reduced DRASTIC, COP and RISK method have been applied, due to the fact that they are the methods used by Spain, both first ones, to evaluate the vulnerability of the groundwater bodies in the inter communal basins of the whole national territory, and for BRGM of France, the last one, to approach the carbonate aquifers protection. The obtained results show as the COP and RISK methods, specifics of carbonate aquifers, there show results more according to the characteristics of Canete Mountain Range that the obtained ones with Reduced DRASTIC, which unsaturated zone valuation causes an undervaluing the results of vulnerability obtained. (Author) 35 refs.

  10. Risks attributable to water quality changes in shallow potable aquifers from geological carbon sequestration leakage into sediments of variable carbonate content

    DEFF Research Database (Denmark)

    Cahill, Aaron Graham; Jakobsen, Rasmus; Mathiesen, Tina Bay;

    2013-01-01

    Denmark including; siliceous, carbonate and clay materials. Sediments were exposed to CO2 and hydro-geochemical effects were observed in order to improve general understanding of trace metal mobility, quantify carbonate influence, assess risks attributable to fresh water resources from a potential leak...... and aid monitoring measurement and verification (MMV) program design. Results demonstrate control of water chemistry by sediment mineralogy and most significantly carbonate content, for which a potential semi-logarithmic relationship with pH and alkalinity was observed. In addition, control of water...... chemistry by calcite equilibrium was inferred for sediments containing >2% total inorganic carbon (TIC), whereby pH minima and alkalinity maxima of approximately 6 and 20mequiv./l respectively were observed. Carbonate dominated (i.e. >2% TIC) and mixed (i.e. clay containing) sediments showed the most severe...

  11. Water Resources of the Basin and Range Carbonate-Rock Aquifer System, White Pine County, Nevada, and Adjacent Areas in Nevada and Utah - Draft Report

    Science.gov (United States)

    Welch, Alan H., (Edited By); Bright, Daniel J.

    2007-01-01

    Summary of Major Findings This report summarizes results of a water-resources study for White Pine County, Nevada, and adjacent areas in east-central Nevada and western Utah. The Basin and Range carbonate-rock aquifer system (BARCAS) study was initiated in December 2004 through Federal legislation (Section 131 of the Lincoln County Conservation, Recreation, and Development Act of 2004) directing the Secretary of the Interior to complete a water-resources study through the U.S. Geological Survey, Desert Research Institute, and State of Utah. The study was designed as a regional water-resource assessment, with particular emphasis on summarizing the hydrogeologic framework and hydrologic processes that influence ground-water resources. The study area includes 13 hydrographic areas that cover most of White Pine County; in this report however, results for the northern and central parts of Little Smoky Valley were combined and presented as one hydrographic area. Hydrographic areas are the basic geographic units used by the State of Nevada and Utah and local agencies for water-resource planning and management, and are commonly defined on the basis of surface-water drainage areas. Hydrographic areas were further divided into subbasins that are separated by areas where bedrock is at or near the land surface. Subbasins represent subdivisions used in this study for estimating recharge, discharge, and water budget. Hydrographic areas represent the subdivision used for reporting summed and tabulated subbasin estimates.

  12. Mapping Evapotranspiration Units in the Basin and Range Carbonate-Rock Aquifer System, White Pine County, Nevada, and Adjacent Areas in Nevada and Utah

    Science.gov (United States)

    Smith, J. LaRue; Laczniak, Randell J.; Moreo, Michael T.; Welborn, Toby L.

    2007-01-01

    Accurate estimates of ground-water discharge are crucial in the development of a water budget for the Basin and Range carbonate-rock aquifer system study area. One common method used throughout the southwestern United States is to estimate ground-water discharge from evapotranspiration (ET). ET is a process by which water from the Earth's surface is transferred to the atmosphere. The volume of water lost to the atmosphere by ET can be computed as the product of the ET rate and the acreage of vegetation, open water, and moist soil through which ET occurs. The procedure used in the study groups areas of similar vegetation, water, and soil conditions into different ET units, assigns an average annual ET rate to each unit, and computes annual ET from each ET unit within the outer extent of potential areas of ground-water discharge. Data sets and the procedures used to delineate the ET-unit map used to estimate ground-water discharge from the study area and a qualitative assessment of the accuracy of the map are described in this report.

  13. Solute changes during aquifer storage recovery testing in a limestone/clastic aquifer

    Science.gov (United States)

    Mirecki, J.E.; Campbell, B.G.; Conlon, K.J.; Petkewich, M.D.

    1998-01-01

    Aquifer storage recovery (ASR) was tested in the Santee Limestone/Black Mingo Aquifer near Charleston, South Carolina, to assess the feasibility for subsurface storage of treated drinking water. Water quality data obtained during two representative ASR tests were interpreted to show three things: (1) recovery efficiency of ASR in this geological setting; (2) possible changes in physical characteristics of the aquifer during ASR testing; and (3) water quality changes and potability of recovered water during short (one- and six-day) storage durations in the predominantly carbonate aquifer. Recovery efficiency for both ASR tests reported here was 54%. Successive ASR tests increased aquifer permeability of the Santee Limestone/Black Mingo Aquifer. It is likely that aquifer permeability increased during short storage periods due to dissolution of carbonate minerals and amorphous silica in aquifer material by treated drinking water. Dissolution resulted in an estimated 0.3% increase in pore volume of the permeable zones. Ground water composition generally evolved from a sodium-calcium bicarbonate water to a sodium chloride water during storage and recovery. After short duration, stored water can exceed the U.S. Environmental Protection Agency maximum contaminant level (MCL) for chloride (250 mg/L). However, sulfate, fluoride, and trihalomethane concentrations remained below MCLs during storage and recovery.Aquifer storage recovery (ASR) was tested in the Santee Limestone/Black Mingo Aquifer near Charleston, South Carolina, to assess the feasibility for subsurface storage of treated drinking water. Water quality data obtained during two representative ASR tests were interpreted to show three things: (1) recovery efficiency of ASR in this geological setting; (2) possible changes in physical characteristics of the aquifer during ASR testing; and (3) water quality changes and potability of recovered water during short (one- and six-day) storage durations in the predominantly

  14. Reservoir Characterization for CO2 Sequestration: Assessing the Potential of the Devonian Carbonate Nisku Formation of Central Alberta Caractérisation de réservoir en vue du stockage géologique de CO2 : évaluation du potentiel offert par les carbonates dévoniens de la formation de Nisku, en Alberta central

    OpenAIRE

    Eisinger C.; Jensen J

    2011-01-01

    The Wabamun Lake area of Central Alberta, Canada includes several large CO2 point source emitters, collectively producing more than 30 Mt annually. Previous studies established that deep saline aquifers beneath the Wabamun Lake area have good potential for the large-scale injection and storage of CO2. This study reports on the characterization of the Devonian carbonate Nisku Formation for evaluation as a CO2 repository. Major challenges for characterization included sparse well and seis...

  15. High Temperature Aquifer Storage

    Science.gov (United States)

    Ueckert, Martina; Niessner, Reinhard; Baumann, Thomas

    2015-04-01

    Combined heat and power generation (CHP) is highly efficient because excess heat is used for heating and/or process energy. However, the demand of heat energy varies considerably throughout the year while the demand for electrical energy is rather constant. It seems economically and ecologically highly beneficial for municipalities and large power consumers such as manufacturing plants to store excess heat in groundwater aquifers and to recuperate this energy at times of higher demand. Apart from the hydrogeological conditions, high transmissivity and favorable pressure gradients, the hydrochemical conditions are crucial for long-term operation. Within the project High Temperature Aquifer Storage, scientists investigate storage and recuperation of excess heat energy into the bavarian Malm aquifer. After one year of planning, construction, and the successful drilling of a research well to 495 m b.s.l. the first large scale heat storage test in the Malm aquifer was finished just before Christmas 2014. An enormous technical challenge was the disruption of the carbonate equilibrium - modeling results indicated a carbonate precipitation of 10-50 kg/d in the heat exchangers. The test included five injection pulses of hot water (60 °C up to 110 °C) and four tracer pulses, each consisting of a reactive and a conservative fluorescent dye. Injection and production rates were 15 L/s. About 4 TJ of heat energy were necessary to achieve the desired water temperatures. Electrical conductivity, pH and temperature were recorded at a bypass where also samples were taken. A laboratory container at the drilling site was equipped for the analysis of the concentration of the tracers and the cation concentrations at sampling intervals of down to 15 minutes. Additional water samples were taken and analyzed for major ions and trace elements in the laboratory. The disassembled heat exchanger proved that precipitation was successfully prevented by adding CO2 to the water before heating

  16. Using carbon and water isotopes and noble gases to assess the origin of methane in fresh water aquifers in the south of the Netherlands

    Science.gov (United States)

    Broers, Hans Peter; de Weert, Jasperien; Vonhof, Hubert; Janssen, Renee; Sueltenfuss, Juergen; Aeschbach-Hertig, Werner; Castelijns, Jeroen

    2015-04-01

    Groundwater in the Dutch subsurface is known to contain substantial concentrations of methane of which the origin is not always clear. The Dutch subsurface contains relatively high organic matter contents which makes a biogenic origin plausible, however few studies have used water and carbon isotopes to deduce the origin of methane. In relation to possible future exploitation of deep shale gas resources, it is now considered important to assess base line quality of fresh groundwater in overlying aquifers from which drinking water is produced. Therefore, we sampled the raw water of 41 large public supply well fields in the south of the Netherlands which represents a mixture of groundwater of different ages and used the a discrete travel time distribution model (DTTDM, Visser et al. 2013, WRR) in order to quantify the age distribution of the mixture. Measurements included major ion chemistry, 3H, 3He, 4He, 18O, 2H, 14C, 13C-DIC and 13C-CH4 and the full range of noble gases. 13C-CH4 measurements were carried out using a Picarro G2201-i CRDS analyser. The heavier noble gases enable the calculation of the Noble Gas Temperature (NGT) which characterizes the temperature of past recharge conditions. The 14C apparent age of each mixture was derived correcting for dead carbon sources and included carbonate dissolution and methanogenesis as the defining processes. The 13C-CH4 measurements showed a range of δ-values between -70 and -100‰, which give a clear indication for biogenic methane. No clear relations between 13C-CH4 and 13C-DIC or the 4He/CH4 ratio were observed. However, clear spatial patterns indicated that more depleted values are grouped in specific areas. The 13δCH4 values did not show a clear relation with the age distribution of the pumped water, even though a large range of age distributions was observed including old water with an age of > 25 k yrs. We believe that spatial differences in organic matter contents, origin of the geological deposits and/or the

  17. High Temperature Aquifer Storage

    Science.gov (United States)

    Ueckert, Martina; Niessner, Reinhard; Baumann, Thomas

    2016-04-01

    Combined heat and power generation (CHP) is highly efficient because excess heat is used for heating and/or process energy. However, the demand of heat energy varies considerably throughout the year while the demand for electrical energy is rather constant. It seems economically and ecologically highly beneficial for municipalities and large power consumers such as manufacturing plants to store excess heat in groundwater aquifers and to recuperate this energy at times of higher demand. Within the project High Temperature Aquifer Storage, scientists investigate storage and recuperation of excess heat energy into the bavarian Malm aquifer. Apart from high transmissivity and favorable pressure gradients, the hydrochemical conditions are crucial for long-term operation. An enormous technical challenge is the disruption of the carbonate equilibrium - modeling results indicated a carbonate precipitation of 10 - 50 kg/d in the heat exchangers. The test included five injection pulses of hot water (60 °C up to 110 °C) and four tracer pulses, each consisting of a reactive and a conservative fluorescent dye, into a depth of about 300 m b.s.l. resp. 470 m b.s.l. Injection and production rates were 15 L/s. To achieve the desired water temperatures, about 4 TJ of heat energy were necessary. Electrical conductivity, pH and temperature were recorded at a bypass where also samples were taken. A laboratory container at the drilling site was equipped for analysing the concentration of the dyes and the major cations at sampling intervals of down to 15 minutes. Additional water samples were taken and analysed in the laboratory. The disassembled heat exchanger prooved that precipitation was successfully prevented by adding CO2 to the water before heating. Nevertheless, hydrochemical data proved both, dissolution and precipitation processes in the aquifer. This was also suggested by the hydrochemical modelling with PhreeqC and is traced back to mixture dissolution and changing

  18. Analysis of pumping-induced unsaturated regions beneath a perennial river

    Science.gov (United States)

    Su, G.W.; Jasperse, J.; Seymour, D.; Constante, J.; Zhou, Q.

    2007-01-01

    The presence of an unsaturated region beneath a streambed during groundwater pumping near streams can reduce the pumping capacity, change flow paths, and alter the types of biological transformations in the streambed sediments. A three-dimensional, multiphase flow model of two horizontal collector wells along the Russian River near Forestville, California, was developed to investigate the impact of varying the ratio of the aquifer to streambed permeability on (1) the formation of an unsaturated region beneath the stream, (2) the pumping capacity, (3) stream water fluxes through the streambed, and (4) stream water traveltimes to the collector wells. The aquifer to streambed permeability ratio at which the unsaturated region was initially observed ranged from 10 to 100. The size of the unsaturated region beneath the streambed increased as the aquifer to streambed permeability ratio increased. The simulations also indicated that for a particular aquifer permeability, decreasing the streambed permeability by only a factor of 2-3 from the permeability where desaturation initially occurred resulted in reducing the pumping capacity. In some cases, the stream water fluxes increased as the streambed permeability decreased. However, the stream water residence times increased and the fraction of stream water that reached that the wells decreased as the streambed permeability decreased, indicating that a higher streambed flux does not necessarily correlate to greater recharge of stream water around the wells. Copyright 2007 by the American Geophysical Union.

  19. Microbiological monitoring of carbon dioxide storage in a subsurface saline aquifer in Ketzin/Germany within the scope of CO2SINK

    Science.gov (United States)

    Wandrey, M.; Morozova, D.; Zemke, K.; Lerm, S.; Scherf, A.-K.; Vieth, A.; Würdemann, H.; Co2SINK Group

    2009-04-01

    Within the scope of the EU project CO2SINK (www.co2sink.org) a research facility in Ketzin (Germany, west of Berlin) is operated to store CO2 in a saline subsurface aquifer (Würdemann et al., EGU General Assembly 2009). In order to examine the influence of CO2 storage on the environment a comprehensive monitoring program is applied at this site including molecular and microbiological investigations. With the injection of CO2 into the geological formation chemical and physical reservoir characteristics are changed. This may influence the composition and activities of the deep biosphere at the storage horizon. Mineral precipitation, dissolution and corrosion of reservoir casing may be consequences, influencing permeability and long-term stability of the reservoir. The objective of the microbial monitoring program is the characterisation of the microbial community (biocenosis) in fluid samples, as well as in samples from reservoir and cap rock before and during CO2storage using molecular biological methods. 16S rRNA taxonomic studies, Fluorescence in situ hybridisation (FISH), and RealTime PCR are used to examine the composition of the biocenosis. First results of fluid sampling revealed that the microbial community of the saline aquifer is dominated by haloalkaliphilic fermentative bacteria and extremophilic organisms, coinciding with reduced conditions, high salinity and pressure. RealTime RT-PCR of selected genes and the creation and analysis of cDNA libraries will allow the prediction of microbial metabolic activities. In addition, the analysis of organic and inorganic components of the samples will add to the knowledge of possible metabolic shifts during CO2 storage. In order to simulate the storage conditions in situ, long term laboratory experiments in high pressure incubators have been set up using original rock cores from Ketzin. Since DNA and RNA analysis techniques are very sensitive, contamination entries from the adjacent environment have to be excluded

  20. Differential effects of dissolved organic carbon upon re-entrainment and surface properties of groundwater bacteria and bacteria-sized microspheres during transport through a contaminated, sandy aquifer

    Science.gov (United States)

    Harvey, R.W.; Metge, D.W.; Mohanram, A.; Gao, X.; Chorover, J.

    2011-01-01

    Injection-and-recovery studies involving a contaminated, sandy aquifer (Cape Cod, Massachusetts) were conducted to assess the relative susceptibility for in situ re-entrainment of attached groundwater bacteria (Pseudomonas stuzeri ML2, and uncultured, native bacteria) and carboxylate-modified microspheres (0.2 and 1.0 ??m diameters). Different patterns of re-entrainment were evident for the two colloids in response to subsequent injections of groundwater (hydrodynamic perturbation), deionized water (ionic strength alteration), 77 ??M linear alkylbenzene sulfonates (LAS, anionic surfactant), and 76 ??M Tween 80 (polyoxyethylene sorbitan monooleate, a very hydrophobic nonionic surfactant). An injection of deionized water was more effective in causing detachment of micrsopheres than were either of the surfactants, consistent with the more electrostatic nature of microsphere's attachment, their extreme hydrophilicity (hydrophilicity index, HI, of 0.99), and negative charge (zeta potentials, ??, of -44 to -49 mv). In contrast, Tween 80 was considerably more effective in re-entraining the more-hydrophobic native bacteria. Both the hydrophilicities and zeta potentials of the native bacteria were highly sensitive to and linearly correlated with levels of groundwater dissolved organic carbon (DOC), which varied modestly from 0.6 to 1.3 mg L-1. The most hydrophilic (0.52 HI) and negatively charged (?? -38.1 mv) indigenous bacteria were associated with the lowest DOC. FTIR spectra indicated the latter community had the highest average density of surface carboxyl groups. In contrast, differences in groundwater (DOC) had no measurable effect on hydrophilicity of the bacteria-sized microspheres and only a minor effect on their ??. These findings suggest that microspheres may not be very good surrogates for bacteria in field-scale transport studies and that adaptive (biological) changes in bacterial surface characteristics may need to be considered where there is longer

  1. Benchmarking worldwide CO₂ saline aquifer injections

    OpenAIRE

    Hosa, Aleksandra; Esentia, Mina; Stewart, Jamie; Haszeldine, Stuart

    2010-01-01

    Carbon Capture, Transport and Storage is a very active field of research, especially for the past decade. From the UK perspective, a commercially crucial aspect is the saline aquifer research, since there are predicted to be vast storage capacities in the sedimentary formations of the North Sea. The following report reviews the ongoing work on practical injections of CO2 as research tests for storage projects and specifically focuses on industrial sized saline aquifer injections.

  2. The in-situ decontamination of sand and gravel aquifers by chemically enhanced solubilization of multiple-compound DNAPLs with surfactant solutions: Phase 1 -- Laboratory and pilot field-scale testing and Phase 2 -- Solubilization test and partitioning and interwell tracer tests. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-10-24

    Laboratory, numerical simulation, and field studies have been conducted to assess the potential use of micellar-surfactant solutions to solubilize chlorinated solvents contaminating sand and gravel aquifers. Ninety-nine surfactants were screened for their ability to solubilize trichloroethene (TCE), perchloroethylene (PCE), and carbon tetrachloride (CTET). The field test was conducted in the alluvial aquifer which is located 20 to 30 meters beneath a vapor degreasing operation at Paducah Gaseous Diffusion Plant. This aquifer has become contaminated with TCE due to leakage of perhaps 40,000 liters of TCE, which has generated a plume of dissolved TCE extending throughout an area of approximately 3 km{sup 2} in the aquifer. Most of the TCE is believed to be present in the overlying lacustrine deposits and in the aquifer itself as a dense, non-aqueous phase liquid, or DNAPL. The objective of the field test was to assess the efficacy of the surfactant for in situ TCE solubilization. Although the test demonstrated that sorbitan monooleate was unsuitable as a solubilizer in this aquifer, the single-well test was demonstrated to be a viable method for the in situ testing of surfactants or cosolvents prior to proceeding to full-scale remediation.

  3. The in-situ decontamination of sand and gravel aquifers by chemically enhanced solubilization of multiple-compound DNAPLs with surfactant solutions. Phase 1: Laboratory and pilot field-scale testing. Phase 2: Solubilization test and partitioning interwell tracer tests. Final report

    International Nuclear Information System (INIS)

    Laboratory, numerical simulation, and field studies have been conducted to assess the potential use of micellar-surfactant solutions to solubilize chlorinated solvents contaminating sand and gravel aquifers. Ninety-nine surfactants were screened for their ability to solubilize trichloroethene (TCE), perchloroethylene (PCE), and carbon tetrachloride (CTET). The field test was conducted in the alluvial aquifer which is located 20 to 30 meters beneath a vapor degreasing operation at Paducah Gaseous Diffusion Plant. This aquifer has become contaminated with TCE due to leakage of perhaps 40,000 liters of TCE, which has generated a plume of dissolved TCE extending throughout an area of approximately 3 km2 in the aquifer. Most of the TCE is believed to be present in the overlying lacustrine deposits and in the aquifer itself as a dense, non-aqueous phase liquid, or DNAPL. The objective of the field test was to assess the efficacy of the surfactant for in situ TCE solubilization. Although the test demonstrated that sorbitan monooleate was unsuitable as a solubilizer in this aquifer, the single-well test was demonstrated to be a viable method for the in situ testing of surfactants or cosolvents prior to proceeding to full-scale remediation

  4. Tracing groundwater with low-level detections of halogenated VOCs in a fractured carbonate-rock aquifer, Leetown Science Center, West Virginia, USA

    International Nuclear Information System (INIS)

    Highlights: ► Low-level GC–ECD analyses of halogenated VOCs are applied to groundwater tracing. ► Most groundwater samples at the LSC are affected by non-atmospheric anthropogenic sources. ► Low-level detections of halogenated VOCs traced old landfill leakage and chlorinated water. ► Groundwater ages typically range from 4 to 7 years in the fractured, karstic carbonate rocks. ► Groundwater ages are related to climatic and geologic factors. - Abstract: Measurements of low-level concentrations of halogenated volatile organic compounds (VOCs) and estimates of groundwater age interpreted from 3H/3He and SF6 data have led to an improved understanding of groundwater flow, water sources, and transit times in a karstic, fractured, carbonate-rock aquifer at the Leetown Science Center (LSC), West Virginia. The sum of the concentrations of a set of 16 predominant halogenated VOCs (TDVOC) determined by gas chromatography with electron-capture detector (GC–ECD) exceeded that possible for air–water equilibrium in 34 of the 47 samples (median TDVOC of 24,800 pg kg−1), indicating that nearly all the water sampled in the vicinity of the LSC has been affected by addition of halogenated VOCs from non-atmospheric source(s). Leakage from a landfill that was closed and sealed nearly 20 a prior to sampling was recognized and traced to areas east of the LSC using low-level detection of tetrachloroethene (PCE), methyl chloride (MeCl), methyl chloroform (MC), dichlorodifluoromethane (CFC-12), and cis-1,2-dichloroethene (cis-1,2-DCE). Chloroform (CHLF) was the predominant VOC in water from domestic wells surrounding the LSC, and was elevated in groundwater in and near the Fish Health Laboratory at the LSC, where a leak of chlorinated water occurred prior to 2006. The low-level concentrations of halogenated VOCs did not exceed human or aquatic-life health criteria, and were useful in providing an awareness of the intrinsic susceptibility of the fractured karstic groundwater

  5. Chemical transport beneath a uranium mill tailings pile, Riverton, Wyoming

    International Nuclear Information System (INIS)

    A detailed geochemical study at the Riverton site was undertaken in order to define the nature of chemical transport between an inactive tailings pile and the relationship between the underlying shallow groundwater system. Isotopic measurements of oxygen, deuterium, and tritium showed that although both the shallow alluvial aquifer and a deeper aquifer in the Wind River Formation were derived from a similar source, the nearby river, recharge from the tailings pile is occurring only in the shallow alluvium. 34S/32S ratios are used as a conservative tracer in defining zones of tailings water contamination. Offsite, drilling has revealed the existence of a chemical plume in which calcium and sulfate concentrations are an order of magnitude or more above background. The plume is also characterized by high dissolved molybdenum concentrations. Pore waters in the tailings exhibit extremely high concentrations of Al, Fe and SO4 and low pH. The dissolution of calcite occurs in the alluvium beneath the pile which is characterized by high partial pressures of CO/sub 2(g)/ in the tailings while serving to neutralize pH. The groundwater, however remains saturated with CaCO3, suggesting that a buffering capacity is active. Beneath and downgradient from the tailings, the groundwater becomes saturated with gypsum. The chemical speciation code, PHREEQE, was used to model mixing reactions, assuming a hydrologically static system. Reaction path simulations were fit to observed trends of pH that were depressed in the contaminated groundwater. The simulations estimate one percent mixing of tailings-pore water with groundwater from the shallow alluvial aquifer

  6. Review of Aquifer Storage and Recovery Performance in the Upper Floridan Aquifer in Southern Florida

    Science.gov (United States)

    Reese, Ronald S.

    2006-01-01

    Introduction: Interest and activity in aquifer storage and recovery (ASR) in southern Florida has increased greatly during the past 10 to 15 years. ASR wells have been drilled to the carbonate Floridan aquifer system at 30 sites in southern Florida, mostly by local municipalities or counties located in coastal areas. The primary storage zone at these sites is contained within the brackish to saline Upper Floridan aquifer of the Floridan aquifer system. The strategy for use of ASR in southern Florida is to store excess freshwater available during the wet season in an aquifer and recover it during the dry season when needed for supplemental water supply. Each ASR cycle is defined by three periods: recharge, storage, and recovery. This fact sheet summarizes some of the findings of a second phase retrospective assessment of existing ASR facilities and sites.

  7. Arsenic in Groundwater: The Deep Late Pleistocene Aquifers of the Western Bengal Basin.

    Science.gov (United States)

    McArthur, J M; Ghosal, U; Sikdar, P K; Ball, J D

    2016-04-01

    in groundwaters from 145 wells across central West Bengal, India, those from Pleistocene aquifers at depths >70 m beneath paleo-interfluves contain polluted groundwater in overlying aquifers. We postulate that the As was liberated in situ by reduction of minimal iron oxyhydroxides in the gray Pleistocene sands by organic matter infiltrating from riverbeds during late Pleistocene or earliest Holocene times. Mitigation of the widespread As-pollution in shallow aquifers through exploitation of deep Pleistocene aquifers would improve if guided by an understanding of the distribution of buried paleo-channels and paleo-interfluves and the knowledge that As may be present naturally in groundwater at depths >150 m beneath deep paleo-channels. PMID:27010474

  8. Multi-isotope (carbon and chlorine) analysis for fingerprinting and site characterization at a fractured bedrock aquifer contaminated by chlorinated ethenes

    DEFF Research Database (Denmark)

    Palau, Jordi; Marchesi, Massimo; Chambon, Julie Claire Claudia;

    2014-01-01

    pattern observed downstream from the tank's source could be explained by the simultaneous effect of mixing and biodegradation. The results demonstrate that a multi-isotope approach is a valuable tool for characterization of complex sites such as fractured bedrock aquifer contaminated by multiple sources...

  9. Ground Water movement in crystalline rock aquifers

    International Nuclear Information System (INIS)

    Ground water movement studies were performed in crystalline rock aquifers from the upper Acarau River hydrographic basin, state of Ceara, Brazil. The studies included carbon-14, 18O/16O and tritium measurements as well as chemical analysis. A total of 35 wells were surveyed during drought seasons. Carbon-14 values displayed little variation which implied that the water use was adequate despite of the slower recharge conditions. Fairly constant isotopic 18O/16O ratio values in the wells and their similarity with rainwater values indicated that the recharge is done exclusively by pluvial waters. A decreasing tendency within the tritium concentration values were interpreted as a periodic rainwater renewal for these aquifers. The chemical analysis demonstrated that there is in fact no correlation between salinity and the time the water remains in the aquifer itself. (D.J.M.)

  10. Petrophysical laboratory invertigations of carbon dioxide storage in a subsurface saline aquifer in Ketzin/Germany within the scope of CO2SINK

    Science.gov (United States)

    Zemke, K.; Kummmerow, J.; Wandrey, M.; Co2SINK Group

    2009-04-01

    Since June of 2008 carbon dioxide has been injected into a saline aquifer at the Ketzin test site [Würdemann et al., this volume]. The food grade CO2 is injected into a sandstone zone of the Stuttgart formation at ca. 650 m depth at 35°C reservoir temperature and 62 bar reservoir pressure. With the injection of CO2 into the geological formation, chemical and physical reservoir characteristics are changed depending on pressure, temperature, fluid chemistry and rock composition. Fluid-rock interaction could comprise dissolution of non-resistant minerals in CO2-bearing pore fluids, cementing of the pore space by precipitating substances from the pore fluid, drying and disintegration of clay minerals and thus influence of the composition and activities of the deep biosphere. To testing the injection behaviour of CO2 in water saturated rock and to evaluate the geophysical signature depending on the thermodynamic conditions, flow experiments with water and CO2 have been performed on cores of the Stuttgart formation from different locations including new wells of ketzin test site. The studied core material is an unconsolidated fine-grained sandstone with porosity values from 15 to 32 %. Permeability, electrical resistivity, and sonic wave velocities and their changes with pressure, saturation and time have been studied under simulated in situ conditions. The flow experiments conducted over several weeks with brine and CO2 showed no significant changes of resistivity and velocity and a slightly decreasing permeability. Pore fluid analysis showed mobilization of clay and some other components. A main objective of the CO2Sink laboratory program is the assessment of the effect of long-term CO2 exposure on reservoir rocks to predict the long-term behaviour of geological CO2 storage. For this CO2 exposure experiments reservoir rock samples were exposed to CO2 saturated reservoir fluid in corrosion-resistant high pressure vessels under in situ temperature and pressure

  11. Multi-isotope (carbon and chlorine) analysis for fingerprinting and site characterization at a fractured bedrock aquifer contaminated by chlorinated ethenes

    International Nuclear Information System (INIS)

    The use of compound specific multi-isotope approach (C and Cl) in the characterization of a chlorinated ethenes contaminated fractured aquifer allows the identification of several sources and contaminant plumes, as well as the occurrence of biodegradation and mixing processes. The study site is located in Spain with contamination resulting in groundwater concentrations of up to 50 mg/L of trichloroethene (TCE), the most abundant chlorinated ethene, and 7 mg/L of tetrachloroethene (PCE). The potential sources of contamination including abandoned barrels, an underground tank, and a disposal lagoon, showed a wide range in δ13C values from − 15.6 to − 40.5‰ for TCE and from − 18.5 to − 32.4‰ for PCE, allowing the use of isotope fingerprinting for tracing of the origin and migration of these contaminants in the aquifer. In contrast, there is no difference between the δ37Cl values for TCE in the contaminant sources, ranging from + 0.53 to + 0.66‰. Variations of δ37Cl and δ13C in the different contaminant plumes were used to investigate the role of biodegradation in groundwater. Moreover, the isotopic data were incorporated into a reactive transport model for determination of whether the isotope pattern observed downstream from the tank's source could be explained by the simultaneous effect of mixing and biodegradation. The results demonstrate that a multi-isotope approach is a valuable tool for characterization of complex sites such as fractured bedrock aquifer contaminated by multiple sources, providing important information which can be used by consultants and site managers to prioritize and design more successful remediation strategies. - Highlights: • Origin and fate of CAHs in groundwater by means of multi CSIA (13C,35Cl) survey • Innovative/new approach tested in a fractured bedrock site • Differentiation of distinct CAH sources • Biodegradation and source mixing recognition in the aquifer

  12. Sources of Water Supplying Pumpage from Regional Aquifer Systems of the United States

    Science.gov (United States)

    Johnston, Richard H.

    1997-02-01

    During the 1970's and 1980's, groundwater withdrawals in the United States ranged from about 3,100-3,900 m3/s. About 40-50 percent of this pumpage was from 11 regional aquifer systems. Prior to development, four very transmissive carbonate-rock and basaltic-rock aquifer systems had vigorous regional flow regimes. In contrast, seven mostly clastic-rock aquifer systems had comparatively sluggish flow regimes due to a semiarid climate or hydrogeologic characteristics that restrict recharge. Development has greatly altered most of the regional flow regimes. In nine aquifer systems, most of the pumped groundwater is supplied by increased recharge due to: 1) increased percolation from outcrop areas or induced leakage from overlying aquifers, as heads decline in confined parts of the aquifer system; or 2) percolation of excess irrigation water (either imported surface water or pumped groundwater). Pumpage from two aquifer systems was supplied mostly by capture of aquifer discharge to springs and streams or as diffuse leakage. Although water levels have declined in parts of all 11 aquifer systems, large losses in storage have occurred only in the three most heavily pumped aquifer systems - the High Plains aquifer (regional water-table decline), the California Central Valley aquifer system (regional artesian-head decline and land subsidence), and the Gulf Coast aquifer systems (mostly water-table decline in an extensive alluvial aquifer).

  13. Groundwater processes, sandplain seeps and interactions with regional aquifer systems in South-Western Australia

    Science.gov (United States)

    George, Richard J.

    1992-06-01

    Groundwater systems were studied in the 4200 ha East Belka catchment in a dryland farming area 300 km east of Perth, W.A., to determine the cause of sandplain seeps. Detailed investigations were carried out on a 200 ha hillslope to determine the characteristics of a shallow aquifer system responsible for the salinization of previously productive agricultural soils. The impact of the shallow aquifer on the regional system was investigated. A shallow (less than 8 m), perched, perennial aquifer was encountered in the deep sandplain materials. Groundwater discharge of about 1000 kl year -1 from the perched aquifer maintained saline soils across a 5 ha sandplain seep. Perching is due to the decreased permeability, geometry and silicification of the top of the mottled and pallid zones, and the convergence of perched ground waters near the seep. Slug test measurements suggest that the sandplain soils have a relatively low hydraulic conductivity (0.15 m day -1). Water qualities in the perched aquifer ranged from brackish to saline (3000-8000 mg l -1 TDS), peaking in the salt-affected area (12 000 mg l -1 TDS). High nitrate and Cl/Br ratios occur in the shallow aquifer and in the regional ground water beneath the sandplain seep. Recharge to the deep aquifer takes place throughout the catchment, but is greatest beneath the sandplain seep, where a perennial groundwater mound occurs. Recharge to the regional aquifer was estimated to be 6 to 15 mm year -1, increasing to between 20 and 60 mm year -1 beneath the seep. By contrast, less than 0.3 mm year -1 is able to leave the catchment as regional groundwater flow. Water-levels in the deep bores are consequently rising by 0.05 to 0.25 m year -1. Recharge to the deep aquifer beneath the seep, and low groundwater gradients, create the potential for groundwater flow to take place beneath the topographic divide and towards the adjoining catchment. However, as the vertical flux to the aquifer is two orders of magnitude greater than

  14. Epigenetic zonation and fluid flow history of uranium-bearing fluvial aquifer systems, south Texas uranium province. Report of Investigations No. 119

    International Nuclear Information System (INIS)

    The Oligocene-Miocene fluvial uranium host aquifers of the South Texas uranium province were deposited principally as syndepositionally oxidized sands and muds. Early intrusion of reactive sulfide-enriched waters produced large intrastratal islands of epigenetic sulfidic alteration, which contain isotopically heavy pyrite exhibiting unique replacement textures. The only known reservoir containing such sulfidic waters is the deeply buried Mesozoic carbonate section beneath the thick, geopressured Tertiary basin fill. Thermobaric waters were expulsed upward along major fault zones into shallow aquifers in response to a pressure head generated by compaction and dehydration in the abyssal ground-water regime. Vertical migration of gaseous hydrogen sulfide was less important. Repeated flushing of the shallow aquifers by oxidizing meteoric waters containing anomalous amounts of uranium, selenium, and molybdenum alternating with sulfidic thermobaric waters caused cyclic precipitation and oxidation of iron disulfide. Uranium deposits formed along hydrologically active oxidation interfaces separating epigenetic sulfidic and epigenetic oxidation zones. Multiple epigenetic events are recorded in imperfectly superimposed, multiple mineralization fronts, in regional and local geometric relations between different alteration zones, and in the bulk matrix geochemistry and mineralogy of alteration zones. The dynamic mineralization model described in this report may reflect processes active in many large, depositionally active basins

  15. Remediating RDX-contaminated ground water with permanganate: laboratory investigations for the Pantex perched aquifer.

    Science.gov (United States)

    Adam, M L; Comfort, S D; Morley, M C; Snow, D D

    2004-01-01

    Ground water beneath the U.S. Department of Energy Pantex Plant is contaminated with the high explosive RDX (hexahydro-1,3,5-trinitro-1,3,5 triazine). The USDOE Innovative Treatment and Remediation Demonstration (ITRD) program identified in situ oxidation by permanganate as a technology fit for further investigation. We evaluated the efficacy of KMnO(4) to transform and mineralize RDX by determining degradation kinetics and carbon mass balances using (14)C-RDX. Aqueous RDX solutions (2-5 mg L(-1)) and RDX-contaminated slurries (50% solids, w/v) were treated with KMnO(4) at 1000, 2000, 4000, and 20000 mg L(-1). Treating an aqueous RDX solution of 2.8 mg L(-1) with 20000 mg KMnO(4) L(-1) decreased RDX to 0.1 mg L(-1) within 11 d while cumulative mineralization proceeded for 14 d until 87% of the labeled carbon was trapped as (14)CO(2). Similar cumulative mineralization was obtained when Pantex aquifer material was included in the solution matrix. Other experiments using 4000 mg KMnO(4) L(-1) showed that initial RDX concentrations (1.3-10.4 mg L(-1)) or initial pH (4-11) had little effect on reaction rates. Attempts to identify RDX degradates and reaction products showed that N(2)O was a product of permanganate oxidation and constituted 20 to 30% of the N balance. Time-course measurements of a (14)C-RDX solution treated with KMnO(4) revealed few (14)C-labeled degradates but through liquid chromatography-mass spectrometry (LC-MS) analysis, we present evidence that 4-nitro-2,4-diaza-butanol is formed. Aquifer microcosm studies confirmed that the transformation products not mineralized by KMnO(4) were much more biodegradable than parent RDX. These results indicate permanganate can effectively transform and mineralize RDX in the presence of aquifer material and support its use as an in situ chemical oxidation treatment for the Pantex perched aquifer. PMID:15537939

  16. Multi-isotope (carbon and chlorine) analysis for fingerprinting and site characterization at a fractured bedrock aquifer contaminated by chlorinated ethenes

    Energy Technology Data Exchange (ETDEWEB)

    Palau, Jordi, E-mail: jordi.palau@unine.ch [Departament de Cristal.lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona, Martí i Franquès, s/n 08028 Barcelona (Spain); Marchesi, Massimo [Departament de Cristal.lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona, Martí i Franquès, s/n 08028 Barcelona (Spain); Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Chambon, Julie C.C. [Department of Environmental Engineering, Technical University of Denmark, 2800 Lyngby (Denmark); Aravena, Ramon [Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Canals, Àngels [Departament de Cristal.lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona, Martí i Franquès, s/n 08028 Barcelona (Spain); Binning, Philip J.; Bjerg, Poul L. [Department of Environmental Engineering, Technical University of Denmark, 2800 Lyngby (Denmark); Otero, Neus; Soler, Albert [Departament de Cristal.lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona, Martí i Franquès, s/n 08028 Barcelona (Spain)

    2014-03-01

    The use of compound specific multi-isotope approach (C and Cl) in the characterization of a chlorinated ethenes contaminated fractured aquifer allows the identification of several sources and contaminant plumes, as well as the occurrence of biodegradation and mixing processes. The study site is located in Spain with contamination resulting in groundwater concentrations of up to 50 mg/L of trichloroethene (TCE), the most abundant chlorinated ethene, and 7 mg/L of tetrachloroethene (PCE). The potential sources of contamination including abandoned barrels, an underground tank, and a disposal lagoon, showed a wide range in δ{sup 13}C values from − 15.6 to − 40.5‰ for TCE and from − 18.5 to − 32.4‰ for PCE, allowing the use of isotope fingerprinting for tracing of the origin and migration of these contaminants in the aquifer. In contrast, there is no difference between the δ{sup 37}Cl values for TCE in the contaminant sources, ranging from + 0.53 to + 0.66‰. Variations of δ{sup 37}Cl and δ{sup 13}C in the different contaminant plumes were used to investigate the role of biodegradation in groundwater. Moreover, the isotopic data were incorporated into a reactive transport model for determination of whether the isotope pattern observed downstream from the tank's source could be explained by the simultaneous effect of mixing and biodegradation. The results demonstrate that a multi-isotope approach is a valuable tool for characterization of complex sites such as fractured bedrock aquifer contaminated by multiple sources, providing important information which can be used by consultants and site managers to prioritize and design more successful remediation strategies. - Highlights: • Origin and fate of CAHs in groundwater by means of multi CSIA ({sup 13}C,{sup 35}Cl) survey • Innovative/new approach tested in a fractured bedrock site • Differentiation of distinct CAH sources • Biodegradation and source mixing recognition in the aquifer.

  17. Effects of a reactive barrier and aquifer geology on metal distribution and mobility in a mine drainage impacted aquifer.

    Science.gov (United States)

    Doerr, Nora A; Ptacek, Carol J; Blowes, David W

    2005-06-01

    The Nickel Rim aquifer has been impacted for five decades by a metal-rich plume generated from the Nickel Rim mine tailings impoundment. Metals released by the oxidation of pyrrhotite in the unsaturated zone of the tailings migrate into the downgradient aquifer, affecting both the groundwater and the aquifer solids. A reactive barrier has been installed in the aquifer to remove sulfate and metals from the groundwater. The effect of the reactive barrier on metal concentrations in the aquifer solids has not previously been studied. In this study, a series of selective extraction procedures was applied to cores of aquifer sediment, to ascertain the distribution of metals among various solid phases present in the aquifer. Extraction results were combined with groundwater chemistry, geochemical modelling and solid-phase microanalyses, to assess the potential mobility of metals under changing geochemical conditions. Reactions within the reactive barrier caused an increase in the solid-phase carbonate content downgradient from the barrier. The concentrations of poorly crystalline, oxidized phases of Mn and Fe, as well as concentrations of Cr(III) associated with oxidized Fe, and poorly crystalline Zn, are lower downgradient from the barrier, whereas total solid-phase metal concentrations remain constant. Iron and Mn accumulate as oxidized, easily extractable forms in a peat layer overlying the aquifer. Although these oxides may buffer reducing plumes, they also have the potential to release metals to the groundwater, should a reduced condition be imposed on the aquifer by remedial actions. PMID:15949605

  18. Experimental and modeling results on geochemical impacts of leaking CO2 from subsurface storage reservoirs to an unconfined oxidizing carbonate aquifer

    Science.gov (United States)

    Qafoku, N. P.; Bacon, D. H.; Shao, H.; Lawter, A.; Wang, G.; Brown, C. F.

    2013-12-01

    Deep subsurface storage and sequestration of CO2 has been identified as a potential mitigation technique for rising atmospheric CO2 concentrations. Sequestered CO2 represents a potential risk to overlying aquifers if the CO2 leaks from the deep storage reservoir. Experimental and modeling work is required to evaluate risks to groundwater quality and develop a systematic understanding on how CO2 leakage may cause important changes in aquifer chemistry and mineralogy by promoting dissolution/precipitation, adsorption/desorption, and redox reactions. Solid materials (rocks and slightly weathered rocks) from an unconfined aquifer, i.e., the Edwards Aquifer in Texas, were used in this investigation. The experimental part consisted of: 1) wet chemical acid extractions (8M HNO3 solution at 90 0C); 2) batch experiments conducted at low solid to solution ratios to study time-dependent releases of major, minor and trace elements during periodic or continuous exposure to CO2 gas; 3) hydraulically saturated column experiments conducted under continuous and stop-flow conditions using a CO2 gas saturated synthetic groundwater; 4) pre- and post-treatment solid phase characterization studies. Major variables tested included reaction time (0-336 hours), CO2 flow rate (50 to 350 ml/min), brine concentration (0.1 and 1 M NaCl), rock type and particle size fraction. We are currently investigating the solution composition effects (i.e., presence of contaminants in the initial solution) on the fate and behavior of potential contaminants (As, Pb and Cd) in these systems. Results from the solid phase characterization studies showed that the mineralogy of the Edwards aquifer materials was dominated by calcite. Quartz and montmorillonite were also present in some samples. Acid extractions confirmed that the solid phase had appreciable amounts of potential contaminants (As, Cd, Cr, Cu, Pb and Zn). However, the results from the batch and column experiments demonstrated that these contaminants

  19. Imaging cross fault multiphase flow using time resolved high pressure-temperature synchrotron fluid tomography: implications for the geological storage of carbon dioxide within sandstone saline aquifers

    Science.gov (United States)

    Seers, Thomas; Andrew, Matthew; Bijeljic, Branko; Blunt, Martin; Dobson, Kate; Hodgetts, David; Lee, Peter; Menke, Hannah; Singh, Kamaljit; Parsons, Aaron

    2015-04-01

    Applied shear stresses within high porosity granular rocks result in characteristic deformation responses (rigid grain reorganisation, dilation, isovolumetric strain, grain fracturing and/or crushing) emanating from elevated stress concentrations at grain contacts. The strain localisation features produced by these processes are generically termed as microfaults (also shear bands), which occur as narrow tabular regions of disaggregated, rotated and/or crushed grains. Because the textural priors that favour microfault formation make their host rocks (esp. porous sandstones) conducive to the storage of geo-fluids, such structures are often abundant features within hydrocarbon reservoirs, aquifers and potential sites of CO2 storage (i.e. sandstone saline aquifers). The porosity collapse which accompanies microfault formation typically results in localised permeability reduction, often encompassing several orders of magnitude. Given that permeability is the key physical parameter that governs fluid circulation in the upper crust, this petrophysical degradation implicates microfaults as being flow impeding structures which may act as major baffles and/or barriers to fluid flow within the subsurface. Such features therefore have the potential to negatively impact upon hydrocarbon production or CO2 injection, making their petrophysical characterisation of considerable interest. Despite their significance, little is known about the pore-scale processes involved in fluid trapping and transfer within microfaults, particularly in the presence of multiphase flow analogous to oil accumulation, production and CO2 injection. With respect to the geological storage of CO2 within sandstone saline aquifers it has been proposed that even fault rocks with relatively low phyllosilicate content or minimal quartz cementation may act as major baffles or barriers to migrating CO2 plume. Alternatively, as ubiquitous intra-reservoir heterogeneities, micro-faults also have the potential to

  20. 14C measurements in aquifers with methane

    International Nuclear Information System (INIS)

    A survey of various groundwater systems indicates that methane is a common trace constituent and occasionally a major carbon species in groundwaters. Thermocatalytic methane had delta13CCH4 > -45%0 and microbially-produced or biogenic methane had delta13CCH4 0. Groundwaters containing significant biogenic methane had abnormally heavy delta13C values for the inorganic carbon. Thermocatalytic methane had no apparent effect on the inorganic carbon. Because methanogenesis seriously affects the carbon isotope geochemistry of groundwaters, the correction of raw 14C ages of affected groundwaters must consider these effects. Conceptual models are developed which adjust the 14C activity of the groundwater for the effects of methanogenesis and for the dilution of carbon present during infiltration by simple dissolution of rock carbonate. These preliminary models are applied to groundwaters from the Alliston sand aquifer where methanogenesis has affected most samples. In this system, methanogenic bacteria using organic matter present in the aquifer matrix as substrate, have added inorganic carbon to the groundwater which has initiated further carbonate rock dissolution. These processes have diluted the inorganic carbon 14C activity. (orig.)

  1. Carbon isotope systematics of the Cambrian–Vendian aquifer system in the northern Baltic Basin: Implications to the age and evolution of groundwater

    International Nuclear Information System (INIS)

    Groundwater in the Cambrian–Vendian aquifer system has a strongly depleted stable isotope composition (δ18O values of about −22‰) and a low radiocarbon concentration, which suggests that the water is of glacial origin from the last Ice Age. The aim of this paper was to elucidate the timing of infiltration of glacial waters and to understand the geochemical evolution of this groundwater. The composition of the dissolved inorganic C (DIC) in Cambrian–Vendian groundwater is influenced by complex reactions and isotope exchange processes between water, organic materials and rock matrix. The δ13C composition of dissolved inorganic C in Cambrian–Vendian water also indicates a bacterial modification of the isotope system. The corrected radiocarbon ages of groundwater are between 14,000 and 27,000 radiocarbon years, which is coeval with the advance of the Weichselian Glacier in the area.

  2. Early Mesozoic basin aquifers

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the extent of the Early Mesozoic basin aquifers in the states of Massachusettes, Connecticut, New York, New Jersey, Pennsylvania, Maryland,...

  3. Lower Cretaceous aquifers

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the extent of the Lower Cretaceous aquifers in the states of Montana, Wyoming, South Dakota, Kansas, Nebraska, Iowa, and Minnesota..

  4. Sequence-Stratigraphic Analysis of the Regional Observation Monitoring Program (ROMP) 29A Test Corehole and Its Relation to Carbonate Porosity and Regional Transmissivity in the Floridan Aquifer System, Highlands County, Florida

    Science.gov (United States)

    Ward, W. C.; Cunningham, K.J.; Renken, R.A.; Wacker, M.A.; Carlson, J.I.

    2003-01-01

    An analysis was made to describe and interpret the lithology of a part of the Upper Floridan aquifer penetrated by the Regional Observation Monitoring Program (ROMP) 29A test corehole in Highlands County, Florida. This information was integrated into a one-dimensional hydrostratigraphic model that delineates candidate flow zones and confining units in the context of sequence stratigraphy. Results from this test corehole will serve as a starting point to build a robust three-dimensional sequence-stratigraphic framework of the Floridan aquifer system. The ROMP 29A test corehole penetrated the Avon Park Formation, Ocala Limestone, Suwannee Limestone, and Hawthorn Group of middle Eocene to Pliocene age. The part of the Avon Park Formation penetrated in the ROMP 29A test corehole contains two composite depositional sequences. A transgressive systems tract and a highstand systems tract were interpreted for the upper composite sequence; however, only a highstand systems tract was interpreted for the lower composite sequence of the deeper Avon Park stratigraphic section. The composite depositional sequences are composed of at least five high-frequency depositional sequences. These sequences contain high-frequency cycle sets that are an amalgamation of vertically stacked high-frequency cycles. Three types of high-frequency cycles have been identified in the Avon Park Formation: peritidal, shallow subtidal, and deeper subtidal high-frequency cycles. The vertical distribution of carbonate-rock diffuse flow zones within the Avon Park Formation is heterogeneous. Porous vuggy intervals are less than 10 feet, and most are much thinner. The volumetric arrangement of the diffuse flow zones shows that most occur in the highstand systems tract of the lower composite sequence of the Avon Park Formation as compared to the upper composite sequence, which contains both a backstepping transgressive systems tract and a prograding highstand systems tract. Although the porous and permeable

  5. Continental crust beneath southeast Iceland.

    Science.gov (United States)

    Torsvik, Trond H; Amundsen, Hans E F; Trønnes, Reidar G; Doubrovine, Pavel V; Gaina, Carmen; Kusznir, Nick J; Steinberger, Bernhard; Corfu, Fernando; Ashwal, Lewis D; Griffin, William L; Werner, Stephanie C; Jamtveit, Bjørn

    2015-04-14

    The magmatic activity (0-16 Ma) in Iceland is linked to a deep mantle plume that has been active for the past 62 My. Icelandic and northeast Atlantic basalts contain variable proportions of two enriched components, interpreted as recycled oceanic crust supplied by the plume, and subcontinental lithospheric mantle derived from the nearby continental margins. A restricted area in southeast Iceland--and especially the Öræfajökull volcano--is characterized by a unique enriched-mantle component (EM2-like) with elevated (87)Sr/(86)Sr and (207)Pb/(204)Pb. Here, we demonstrate through modeling of Sr-Nd-Pb abundances and isotope ratios that the primitive Öræfajökull melts could have assimilated 2-6% of underlying continental crust before differentiating to more evolved melts. From inversion of gravity anomaly data (crustal thickness), analysis of regional magnetic data, and plate reconstructions, we propose that continental crust beneath southeast Iceland is part of ∼350-km-long and 70-km-wide extension of the Jan Mayen Microcontinent (JMM). The extended JMM was marginal to East Greenland but detached in the Early Eocene (between 52 and 47 Mya); by the Oligocene (27 Mya), all parts of the JMM permanently became part of the Eurasian plate following a westward ridge jump in the direction of the Iceland plume. PMID:25825769

  6. Ogallala Aquifer Mapping Program

    International Nuclear Information System (INIS)

    A computerized data file has been established which can be used efficiently by the contour-plotting program SURFACE II to produce maps of the Ogallala aquifer in 17 counties of the Texas Panhandle. The data collected have been evaluated and compiled into three sets, from which SURFACE II can generate maps of well control, aquifer thickness, saturated thickness, water level, and the difference between virgin (pre-1942) and recent (1979 to 1981) water levels. 29 figures, 1 table

  7. Recovery of datable charcoal beneath young lavas: lessons from Hawaii.

    Science.gov (United States)

    Lockwood, J.P.; Lipman, P.W.

    1980-01-01

    Field studies in Hawaii aimed at providing a radiocarbon-based chronology of prehistoric eruptive activity have led to a good understanding of the processes that govern the formation and preservation of charcoal beneath basaltic lava flows. Charcoal formation is a rate-dependent process controlled primarily by temperature and duration of heating, as well as by moisture content, density, and size of original woody material. Charcoal will form wherever wood buried by lava is raised to sufficiently high temperatures, but owing to the availability of oxygen it is commonly burned to ash soon after formation. Wherever oxygen circulation is sufficiently restricted, charcoal will be preserved, but where atmospheric oxygen circulates freely, charcoal will only be preserved at a lower temperature, below that required for charcoal ignition or catalytic oxidation. These factors cause carbonized wood, especially that derived from living roots, to be commonly preserved beneath all parts of pahoehoe flows (where oxygen circulation is restricted), but only under margins of aa. Practical guidelines are given for the recovery of datable charcoal beneath pahoehoe and aa. Although based on Hawaiian basaltic flows, the guidelines should be applicable to other areas. -Authors

  8. Hydrologic analysis of data for the Lost Lake Aquifer Zone of the Steel Pond Aquifer at recovery well RWM-16

    International Nuclear Information System (INIS)

    This report presents the results of an analysis of data obtained from a large-scale, multiple-well aquifer test of the sandy unit referred to as the Lost Lake Aquifer Zone of the Steed Pond Aquifer in an area just south of the A and M Areas. Pumping was conducted at recovery well RWM-16, which is located near the MSB-40 well cluster, approximately 4000 feet south of the M-Area Basin. RWM-16 is located in the lower left portion of Figure 1, which also illustrates the general relationship of the testing site to the A and M Areas and other monitor wells. The data generated from testing RWM-16 was used to calculate estimates of transmissivity and storage for the aquifer system within which RWM-16 is screened. These parameters are related to hydraulic conductivity and storativity of the aquifer system by the vertical thickness of the unit. The leakage coefficient for the overlying confining unit is also estimated. This information is needed to refine conceptual understanding of the groundwater flow system beneath the A and M Areas. The refined conceptual model will more adequately describe the pattern of groundwater flow, and will contribute to updating the open-quotes Zone of Captureclose quotes model that has been used in the initial phases of designing a groundwater remediation system in the A and M Areas

  9. Aquifer recharging in South Carolina: radiocarbon in environmental hydrogeology

    International Nuclear Information System (INIS)

    Radiocarbon activities of dissolved inorganic carbon (and tritium activities where infiltration rates are rapid and aquifers shallow) provide relatively unambiguous and inexpensive evidence for identification of significant recharge areas. Such evidence is for the actual occurrence of modern recharge in the aquifer and thus is less inferential than stratigraphic or potentiometric evidence. These underutilized isotopic techniques are neither arcane nor complex and have been more-or-less standardized by earlier researchers. In South Carolina, isotopic evidence has been used from both calcareous and siliceous sedimentary aquifers and fractured crystalline rock aquifers. The Tertiary limestone aquifer is shown not to be principally recharged in its subcrop area, unlike conditions assumed for many other sedimentary aquifers in southeastern United States, and instead receives considerable lateral recharge from interfingering updip Tertiary sand aquifers in the middle coastal plain. Induced recharging at Hilton Head Island is mixing ancient relict water and modern recharge water. Recharging to deeper portions of the Cretaceous Middendorf basal sand aquifer occurs at least as far coastward as the middle coastal plain, near sampling sites that stratigraphically appear to be confined. Pronounced mineralization of water in fractured rocks cannot be considered as evidence of ancient or relict ground water that is isolated from modern contaminants, some of these waters contain considerable radiocarbon and hydrogen-bomb tritium

  10. Origin and structures of groundwater humic substances from three Danish aquifers

    DEFF Research Database (Denmark)

    Grøn, C.; Wassenaar, L.; Krog, M.

    1996-01-01

    Structural, chemical, and isotopic parameters were used to identify the origins of groundwater humic substances from three Danish aquifers. A variety of analytical techniques (visible light absorption, molecular weight distribution, C-13-NMR spectroscopy, elemental composition with major elements...... geological and hydrogeochemical information. In a third aquifer, source rock identification was inconclusive, and multiple fossil and recent organic carbon sources are suggested....... and halogens, hydrolyzable amino acids and carbohydrates, carbon isotopes) applied to aquatic humic and fulvic acids led to consistent structural interpretations for each of the three aquifers studied. For humic substances in two-aquifers, the analyses suggested source rocks in agreement with...

  11. How important are biogeochemical hotspots at aquifer-river interfaces for surface water and groundwater quality?

    Science.gov (United States)

    Krause, S.; Blume, T.; Weatherill, J.; Munz, M.; Tecklenburg, C.; Angermann, L.; Cassidy, N. J.

    2012-04-01

    The mixing of groundwater (GW) and surface water (SW) can have substantial impact on the transformation of solutes transported between aquifer and river. The assessment of biogeochemical cycling at reactivity hotspots as the aquifer-river interface and its implications for GW and SW quality require detailed understanding of the complex patterns of GW-SW exchange fluxes and residence time distributions in particular under changing climatic and landuse conditions. This study presents combined experimental and model-based investigations of the physical drivers and chemical controls of nutrient transport and transformation at the aquifer-river interfaces of two upland and lowland UK rivers. It combines the application of in-stream geophysical exploration techniques, multi-level mini-piezometer networks, active and passive heat tracing methods (including fibre-optic distributed temperature sensing - FO-DTS) for identifying hyporheic exchange fluxes and residence time distributions with multi-scale approaches of hyporheic pore-water sampling and reactive tracers for analysing the patterns of streambed redox conditions and chemical transformation rates. The analysis of hyporheic pore water from nested multi-level mini piezometers and passive gel probe samplers revealed significant spatial variability in streambed redox conditions and concentration changes of nitrogen species, dissolved oxygen and bio-available organic carbon. Hot spots of increased nitrate attenuation were identified beneath semi-confining peat lenses in the streambed of the investigated lowland river. The intensity of concentration changes underneath the confining peat pockets correlated with the state of anoxia in the pore water as well as the supply of organic carbon and hyporheic residence times. In contrast, at locations where flow inhibiting peat layers were absent or disrupted - fast exchange between aquifer and river caused a break-through of nitrate without significant concentration changes along

  12. On Permeability Dynamics in Carbonaceous Aquifers used in Energy Storage Applications

    Science.gov (United States)

    Brady, Ds; Tilley, Bs; Ueckert, M.; Baumann, T.

    2015-11-01

    Geothermal energy harvesting applications use deep groundwater aquifers to store harvested energy. The impact of this additional energy to the aquifer chemistry is crucial for long-term operation. Gaseous CO2 is added to the injected water to compensate potential precipitates of carbonates and to prevent structural changes to the aquifer. Both of these effects affect the local chemical equilibrium of the aquifer, and we consider an effective model through homogenization which captures the hydrochemistry, heat transfer, fluid flow and permeability dynamics of the aquifer as heated fluid is added to the aquifer (injection), and as it is later removed (production). The impact of these different physical mechanisms of the heat storage performance of the aquifer is discussed. Support from the Bavarian State Ministry for the Economy is gratefully acknowledged.

  13. Review of available fluid sampling tools and sample recovery techniques for groundwater and unconventional geothermal research as well as carbon storage in deep sedimentary aquifers

    Science.gov (United States)

    Wolff-Boenisch, Domenik; Evans, Katy

    2014-05-01

    Sampling fluids from deep wells and subsequent sample treatment prior to gas and liquid analysis requires special equipment and sampling techniques to account for the relatively high temperatures, pressures, and potential gas content present at depth. This paper reviews five major sampling methodologies, ranging from different in situ wireline samplers to producing pumps and the U-tube and discusses their advantages and drawbacks in the light of three principal applications, deep groundwater research, unconventional geothermal exploration, and carbon storage. Geochemical modelling is used to investigate the probability of decarbonation and concomitant carbonate scaling during sampling in geothermal and carbon sequestration applications. The two principal sample recovery techniques associated with the fluid samplers are also presented.

  14. Relationships Between Aquifer Properties and Microbial Populations in the Borden Aquifer

    DEFF Research Database (Denmark)

    Barbaro, Susan Elizabeth; Albrechtsen, Hans-Jørgen; Jensen, Bjorn K.;

    1994-01-01

    , electron transport system (ETS) activity, dissolved oxygen (DO), dissolved organic carbon (DOC), weight fraction of organic carbon (FOC), and hydraulic conductivity (K) were determined for contiguous samples of aquifer material removed at 10.0-cm intervals from the 9 cores. Viable cell counts (0-10-4 cfu...... microbiological and geologic data collected in this study suggests that, in conjunction with low dissolved oxygen, the naturally occurring carbon may be unsuitable to support large numbers of microorganisms. Similarly, an increase in the production of INT-for when aquifer material was amended with nitrogen...... activities were found to be predominantly correlated with depth and dissolved oxygen. Evaluation of these results revealed an oxygen threshold level, occurring at approximately 3.0 mg/L, below which bacterial populations isolated in this study were less able to proliferate. Further evaluation of the...

  15. Three-dimensional conceptual model for the Hanford Site unconfined aquifer system: FY 1994 status report

    Energy Technology Data Exchange (ETDEWEB)

    Thorne, P.D.; Chamness, M.A.; Vermeul, V.R.; Macdonald, Q.C.; Schubert, S.E.

    1994-11-01

    This report documents work conducted during the fiscal year 1994 to development an improved three-dimensional conceptual model of ground-water flow in the unconfined aquifer system across the Hanford Site Ground-Water Surveillance Project, which is managed by Pacific Northwest Laboratory. The main objective of the ongoing effort to develop an improved conceptual model of ground-water flow is to provide the basis for improved numerical report models that will be capable of accurately predicting the movement of radioactive and chemical contaminant plumes in the aquifer beneath Hanford. More accurate ground-water flow models will also be useful in assessing the impacts of changes in facilities and operations. For example, decreasing volumes of operational waste-water discharge are resulting in a declining water table in parts of the unconfined aquifer. In addition to supporting numerical modeling, the conceptual model also provides a qualitative understanding of the movement of ground water and contaminants in the aquifer.

  16. Specific yield, High Plains aquifer

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This raster data set represents specific-yield ranges in the High Plains aquifer of the United States. The High Plains aquifer underlies 112.6 million acres...

  17. Aquifer stability investigations

    Energy Technology Data Exchange (ETDEWEB)

    Allen, R.D.; Doherty, T.J.

    1981-09-01

    The study of compressed air energy storage (CAES) in porous rock reservoirs is carried out within the Reservoir Stability Studies Program at Pacific Northwest Laboratory. The goal of the study is to establish criteria for long-term stability of aquifer CAES reservoirs. These criteria are intended to be guidelines and check lists that utilities and architect-engineering firms may use to evaluate reservoir stability at candidate CAES sites. These criteria will be quantitative where possible, qualitative where necessary, and will provide a focal point for CAES relevant geotechnical knowledge, whether developed within this study or available from petroleum, mining or other geotechnical practices using rock materials. The Reservoir Stability Studies Program had four major activities: a state-of-the-art survey to establish preliminary stability criteria and identify areas requiring research and development; numerical modeling; laboratory testing to provide data for use in numerical models and to investigate fundamental rock mechanics, thermal, fluid, and geochemical response of aquifer materials; and field studies to verify the feasibility of air injection and recovery under CAES conditions in an aquifer, to validate and refine the stability criteria, and to evaluate the accuracy and adequacy of the numerical and experimental methodologies developed in previous work. Three phases of study, including preliminary criteria formulation, numerical model development, and experimental assessment of CAES reservoir materials have been completed. Present activity consists of construction and operation of the aquifer field test, and associated numerical and experimental work in support of that activity. Work is presently planned to be complete by 1983 at the end of the field test. At that time the final stability criteria for aquifers will be issued. Attached here also are preliminary criteria for aquifers.

  18. Robust evidence for random fractal scaling of ground water levels in unconfined aquifers

    OpenAIRE

    Little, Max A.; Bloomfield, John P.

    2010-01-01

    This study introduces new approaches to improve the statistical robustness of techniques for quantifying the fractal scaling of groundwater levels, and uses these techniques to investigate scaling of groundwater levels from a consolidated permeable carbonate aquifer. Six groundwater level time series and an associated river stage time series from the unconfined Chalk aquifer (a dual-porosity, fractured limestone aquifer) in the Pang–Lambourn catchment, UK, have been analysed. Surrogate data o...

  19. Geophysical monitoring and evaluation of coastal plain aquifers.

    Science.gov (United States)

    Land, Lewis A; Lautier, Jeff C; Wilson, Nathaniel C; Chianese, Gabrielle; Webb, Steven

    2004-01-01

    We use time domain electromagnetic (TDEM) soundings to monitor ground water conditions beneath the coastal plain in eastern North Carolina. The TDEM method measures the earth's response to an induced electromagnetic field. The resulting signal is converted, through a complex inversion process, to apparent resistivity values, which can be directly correlated to borehole resistivity logs. TDEM soundings are used to map the interface between fresh and salt water within coastal aquifers, and estimate depth to basement when siting new monitoring wells. Focused TDEM surveys have identified areas of salt water encroachment caused by high volumes of discharge from local supply wells. Electromagnetic sounding, when used in tandem with the state's network of monitoring wells, is an accurate and inexpensive tool for evaluating fresh water/salt water relationships on both local and regional scales within coastal plain aquifers. PMID:14763617

  20. Horizontal and vertical distribution of contaminant solvents introduced during different periods into coastal plain aquifers

    International Nuclear Information System (INIS)

    Within a 10 square mile sector in the NW part of the Savannah River Site, degreasing solvents, trichloroethylene (TCE) and tetrachloroethylene (PCE) from contaminant plumes primarily within Tertiary Coastal Plain strata. In the central area, TCE has migrated farther down-section than PCE; to the north, TCE concentrations are > PCE, although both are significantly lower. SW groundwater flow characterizes aquifers beneath the region. Vertical migration potentials are downward. Within the central area, maximum contaminant concentrations are confined to the upper part of the Steed Pond aquifer. Wells do not penetrate deep enough in the central area to determine if contaminants > 5 ppb occur below the 30-50 ft thick Crouch Branch confining unit (CBcu). In the NE part of the sector, the confining layers are thinner, and contaminants are in the Crouch Branch aquifer (CRa) beneath the CBcu. The plume originating from the NE part of the area extends steeply downward to a 360+ ft depth below the surface (30--20 ft above mean sea level), and extends laterally as two distinct lobes of high concentration in the Middle Sand aquifer zone (MSa) within the CBcu and in the CBa in the Cretaceous part of the stratigraphic section. The plume extending beneath the NE part of the area has the deepest known vertical extent. The PCE plume shows relatively moderate levels of contamination extending down to the Middle Sand aquifer zone, but only very low concentrations at deeper levels. In the central part of the area, multiple plumes of high contaminant concentration are steeply inclined from the vertical in the Steed Pond aquifer, whereas high concentrations of PCE do not show as much areal distribution as TCE

  1. Atmospheric Methane Contributions From Fractured Bedrock Aquifers

    Science.gov (United States)

    Marrin, D. L.

    2013-05-01

    Groundwater is not normally considered as an important contributor of atmospheric methane because the organic carbon content of aquifers is too low to sustain significant methanogenesis. Also, groundwater-generated methane partitions into the gas phase of the overlying soil, where it either dissolves in the pore water or is oxidized to carbon dioxide by methanotrophs. There are, however, localized conditions (related to human activities and hydrogeologic conditions) under which atmospheric contributions of groundwater-generated methane occur at the ground surface. Storing and transporting liquid petroleum products in the subsurface has resulted in the local introduction of high concentrations of degradable organic carbon and the creation of redox conditions that favor methanogenesis over more oxidative biodegradation pathways. Groundwater overlain by fractured bedrock, rather than by unconsolidated porous media, creates a situation where CH4 migrates through discrete fractures, thus limiting the soil volume and the surface area available for methanotrophic activity. The spatial distribution of methane in thin surface soils overlying bedrock suggests that CH4 migrates via fracture networks and that CH4 oxidation is a factor of about 50 less than that measured in typical unconsolidated soils. Atmospheric flux rates associated with contaminated bedrock aquifers were on the order of several grams of carbon (as CH4) per square meter, which is less than that reported for well documented sources (e.g., rice paddies) and probably represents a minor worldwide contribution. Nonetheless, these aquifers can represent an important localized source, can shift soils from a sink to a source of methane, and can permit petroleum products to load carbon (as biogenic CH4 and CO2) to the atmosphere without ever being combusted.

  2. High-resolution stable carbon isotope monitoring indicates variable flow dynamic patterns in a deep saline aquifer at the Ketzin pilot site (Germany)

    International Nuclear Information System (INIS)

    Highlights: • Isotopically very distinct kinds of CO2 are injected at the Ketzin pilot site. • We used these isotope variances at the injection well as a tracer input signal. • We found none of these signals at a monitored observation well. • This indicates that CO2 is immobilised at this point in the reservoir. • After immobilization, the δ13CCO2 value was altered by fractionation processes. - Abstract: Stable isotopes of injected CO2 act as useful tracers in carbon capture and storage (CCS) because the CO2 itself is the carrier of the tracer signal and remains unaffected by sorption or partitioning effects. At the Ketzin pilot site (Germany), carbon stable isotope composition (δ13C) of injected CO2 at the injection well was analyzed over a time period of 4 months. Occurring isotope variances resulted from the injection of CO2 from two different sources (an oil refinery and a natural gas-reservoir). The two gases differed in their carbon isotope composition by more than 27‰. In order to find identifiable patterns of these variances in the reservoir, more than 250 CO2-samples were collected and analyzed for their carbon isotope ratios at an observation well 100 m distant from the injection well. An isotope ratio mass spectrometer connected to a modified Thermo Gasbench system allowed quick and cost effective isotope analyses of a high number of CO2 gas specimens. CO2 gas from the oil refinery (δ13C = −30.9‰, source A) was most frequently injected and dominated the reservoir δ13C values at the injection site. Sporadic injection of the CO2 from the natural gas-reservoir (δ13C = −3.5‰, source B) caused isotope shifts of up to +5‰ at the injection well. These variances provided a potential ideal tracer for CO2 migration behavior. Based on these findings, tracer input signals that were injected during the last 2 years of injection could be reconstructed with the aid of an isotope mixing model and CO2 delivery schedules. However, in contrast to

  3. Design of monitor wells, hydrogeology, and ground-water quality beneath Country Pond, Kingston, New Hampshire

    Science.gov (United States)

    Mack, Thomas J.

    1995-01-01

    Ten monitoring well were installed in May 1993 to collect data on the hydrogeology and ground-water quality beneath Country Pond, in Kingston, New Hampshire. Monitoring wells were installed 4 to 48 feet beneath the pond surface in stratified drift that was up to 40 feet thick. The stratified drift is overlain by up to 35 feet of fine-grained, predominantly organic, lake-bottom sediment. The potentiometric head in the aquifer was at or above the pond surface and up to 0.8 foot above the pond surface at one location. Water-quality analyses detected numerous volatile organic compounds including chloroethane, benzene, dichlorobenzenes, and 1,1-dichloroethane at maximum concentrations of 110, 43, 54, and 92 mg/L, respectively. The maximum concentration of total volatile organic compounds detected in ground water from a monitoring well was 550 mg/L in November 1993. Ground-water samples with high concentrations of volatile organic compounds also had elevated specific conductances indicating the presence of other non-organic contaminants. Water-quality analyses indicate that a plume of contaminated ground water extends at least 300 feet in a northeast direction beneath the pond.

  4. Chemical fractionation of geogenic molybdenum and arsenic in a limestone aquifer and their impact on groundwater quality

    Science.gov (United States)

    Mozaffari Khalf Badam, A.; Pichler, T.

    2014-12-01

    Mobilization of naturally occurring molybdenum (Mo) and arsenic (As) in sedimentary rocks, mainly carbonates, contaminate groundwater in the Lithia area. The sedimentary rocks contains up to 825 mg kg-1 Mo and 144 mg kg-1 As. Mo and As groundwater concentrations reached up to 5000 μg L-1 and 300 μg L-1 and exceed the WHO guidelines of 70 and 10 μg L-1, respectively. In order to asses their fractions and origins, a modified five-step (adsorbed/exchangeable, carbonates, hydrous iron oxides, crystalline iron oxides, sulfides and organic matter (OM)) sequential extraction procedure (SEP) was applied to 10 samples. Determination of the elements was carried out by ICP-MS. The SEP results were compared to values obtained by total digestion with aqua regia. The recovery ranged from 88 to 111 % for Mo and 75 to 116 % for As and RSD was better than 10%. In most samples up to 90 % of the Mo was present in the adsorbed/exchangeable fraction (step 1), characterizing a major Mo source. Pyrite, which is present in the aquifer matrix beneath Lithia, is generally considered a source for Mo. Electron microprobe analysis, did not confirm the presence of Mo in pyrite. Thus oxidation of OM is the main reason for the high Mo content in step 1 and groundwater. Another possible source for Mo in groundwater could be the mineral powellite (CaMoO4). To investigate this possibility powellite saturation was calculated with PHREEQC under alkaline conditions. Powellite was super saturated once Mo concentrations exceeded 3000 μg L-1. Thus powellite was not considered a source, but rather a sink for Mo released form OM. In contrast to Mo, As was present in each extraction step in somewhat similar abundance: step 1 (17%), step 2 (11% ), step 3 (30 %), step 4 (23 %) and step 5 (18%). Hydrous and crystalline iron oxides which were dissolved in step 3 and 4 contained the highest As concentrations. Electron microprobe analysis of pyrite, which was dissolved in step 5, showed concentrations of up to

  5. Evaluation of Confining Layer Integrity Beneath the South District Wastewater Treatment Plant, Miami-Dade Water and Sewer Department, Dade County, Florida

    Energy Technology Data Exchange (ETDEWEB)

    Starr, Robert Charles; Green, Timothy Scott; Hull, Laurence Charles

    2001-02-01

    A review has been performed of existing information that describes geology, hydrogeology, and geochemistry at the South District Wastewater Treatment Plant, which is operated by the Miami-Dade Water and Sewer Department, in Dade County, Florida. Treated sanitary wastewater is injected into a saline aquifer beneath the plant. Detection of contaminants commonly associated with treated sanitary wastewater in the freshwater aquifer that overlies the saline aquifer has indicated a need for a reevaluation of the ability of the confining layer above the saline aquifer to prevent fluid migration into the overlying freshwater aquifer. Review of the available data shows that the geologic data set is not sufficient to demonstrate that a competent confining layer is present between the saline and freshwater aquifers. The hydrogeologic data also do not indicate that a competent confining layer is present. The geochemical data show that the freshwater aquifer is contaminated with treated wastewater, and the spatial patterns of contamination are consistent with upward migration through localized conduits through the Middle Confining Unit, such as leaking wells or natural features. Recommendations for collection and interpretation of additional site characterization data are provided.

  6. Evaluation of Confining Layer Integrity Beneath the South District Wastewater Treatment Plant, Miami-Dade Water and Sewer Department, Dade County, Florida

    Energy Technology Data Exchange (ETDEWEB)

    Starr, R.C.; Green, T.S.; Hull, L.C.

    2001-02-28

    A review has been performed of existing information that describes geology, hydrogeology, and geochemistry at the South District Wastewater Treatment Plant, which is operated by the Miami-Dade Water and Sewer Department, in Dade County, Florida. Treated sanitary wastewater is injected into a saline aquifer beneath the plant. Detection of contaminants commonly associated with treated sanitary wastewater in the freshwater aquifer that overlies the saline aquifer has indicated a need for a reevaluation of the ability of the confining layer above the saline aquifer to prevent fluid migration into the overlying freshwater aquifer. Review of the available data shows that the geologic data set is not sufficient to demonstrate that a competent confining layer is present between the saline and freshwater aquifers. The hydrogeologic data also do not indicate that a competent confining layer is present. The geochemical data show that the freshwater aquifer is contaminated with treated wastewater, and the spatial patterns of contamination are consistent with upward migration through localized conduits through the Middle Confining Unit, such as leaking wells or natural features. Recommendations for collection and interpretation of additional site characterization data are provided.

  7. Hydrochemical processes in a shallow coal seam gas aquifer and its overlying stream–alluvial system: implications for recharge and inter-aquifer connectivity

    International Nuclear Information System (INIS)

    Highlights: • Major ions and isotopes used to study inter-aquifer mixing in a shallow CSG setting. • Considerable heterogeneity in the water composition of the coal-bearing aquifer. • Rapid recharge of the coal-bearing aquifer through highly fractured igneous rocks. • Potential mixing between the coal-bearing aquifer and downstream alluvial aquifer. • Need to consider the seasonal influences on inter-aquifer mixing in CSG settings. - Abstract: In areas of potential coal seam gas (CSG) development, understanding interactions between coal-bearing strata and adjacent aquifers and streams is of highest importance, particularly where CSG formations occur at shallow depth. This study tests a combination of hydrochemical and isotopic tracers to investigate the transient nature of hydrochemical processes, inter-aquifer mixing and recharge in a catchment where the coal-bearing aquifer is in direct contact with the alluvial aquifer and surface drainage network. A strong connection was observed between the main stream and underlying alluvium, marked by a similar evolution from fresh Ca–Mg–HCO3 waters in the headwaters towards brackish Ca–Na–Cl composition near the outlet of the catchment, driven by evaporation and transpiration. In the coal-bearing aquifer, by contrast, considerable site-to-site variations were observed, although waters generally had a Na–HCO3–Cl facies and high residual alkalinity values. Increased salinity was controlled by several coexisting processes, including transpiration by plants, mineral weathering and possibly degradation of coal organic matter. Longer residence times and relatively enriched carbon isotopic signatures of the downstream alluvial waters were suggestive of potential interactions with the shallow coal-bearing aquifer. The examination of temporal variations in deuterium excess enabled detection of rapid recharge of the coal-bearing aquifer through highly fractured igneous rocks, particularly at the catchment

  8. Hydrogeological characterisation and water-supply potential of basement aquifers in tropical Africa

    OpenAIRE

    Chilton, P.J.; Foster, S S D

    1995-01-01

    AbstractCrystalline basement rocks, with a mantle of weathered alternation products, occur beneath very extensive areas of tropical Africa. Low-productivity aquifers are widely, but rather unpredictably, present in this formation. They yield small water supplies vital to the rural population for domestic purposes and for livestock watering. On a more localised basis, a potential may exist to develop larger supplies that are adequate for small towns or for small-scale irrigation. This paper re...

  9. Imaging Magma Plumbing Beneath Askja Volcano, Iceland

    Science.gov (United States)

    Greenfield, T. S.; White, R. S.

    2015-12-01

    Using a dense seismic network we have imaged the plumbing system beneath Askja, a large central volcano in the Northern Volcanic Zone, Iceland. Local and regional earthquakes have been used as sources to solve for the velocity structure beneath the volcano. We find a pronounced low-velocity anomaly beneath the caldera at a depth of ~7 km around the depth of the brittle-ductile transition. The anomaly is ~10% slower than the initial best fitting 1D model and has a Vp/Vs ratio higher than the surrounding crust, suggesting the presence of increased temperature or partial melt. We use relationships between mineralogy and seismic velocities to estimate that this region contains ~10% partial melt, similar to observations made at other volcanoes such as Kilauea. This low-velocity body is deeper than the depth range suggested by geodetic studies of a deflating source beneath Askja. Beneath the large low-velocity zone a region of reduced velocities extends into the lower crust and is coincident with seismicity in the lower crust. This is suggestive of a high temperature channel into the lower crust which could be the pathway for melt rising from the mantle. This melt either intrudes into the lower crust or stalls at the brittle-ductile boundary in the imaged body. Above this, melt can travel into the fissure swarm through large dikes or erupt within the Askja caldera itself.We generate travel time tables using a finite difference technique and the residuals used to simultaneously solve for both the earthquake locations and velocity structure. The 2014-15 Bárðarbunga dike intrusion has provided a 45 km long, distributed source of large earthquakes which are well located and provide accurate arrival time picks. Together with long-term background seismicity these provide excellent illumination of the Askja volcano from all directions.hhhh

  10. Environmental isotope studies related to groundwater flow and saline encroachment in the chalk aquifer of Lincolnshire, England

    International Nuclear Information System (INIS)

    The isotopes of tritium and carbon are used to study part of the North Lincolnshire Chalk aquifer in England. The tritium data support the view that the aquifer is a thin fissure system and indicate that some changes in flow direction have occurred owing to recent abstraction. The data are also consistent with other chemical data in elucidating groundwater entering the Chalk from deeper aquifers. Carbon isotopes are used to distinguish between saline water bodies and suggest that saline water was entrapped within the aquifer in the Eemian and Flandrian stages of the Pleistocene. (author)

  11. Cave levels, safe yield and turnover time in karst aquifers

    International Nuclear Information System (INIS)

    Full text: The presence of cave levels where ground water flow is organized is a typical feature of karstic carbonate aquifers. These cave levels are high conductive paths within a capacitive matrix that differentiates flow velocities, transit times and therefore, the chemical and isotopic composition of groundwater. These two extreme transmissive end points allowed the application of double porosity models to solve flow and transport equations although actually karst aquifers are multiple-porosity systems where flow is rigorously hierarchised. The application of environmental stable and radioactive isotopic models to several Cuban karstic aquifers have shown a well defined stratification of flow varying from three months to 100 years. These so large transit times for 3H suggest that - isotopically - the system is far from steady state conditions and, therefore, the exploitation of the aquifers horizons is strongly restricted by these low renewable resources. While associated with well defined cave systems, transit time of groundwater in karst aquifers is a variable to be considered in the estimation of safe yield and in the engineering measures, as artificial recharge, designed for improve the sustainability of water resources. Depletion of water resources in karst aquifers of the humid tropics could be associated to the exploitation of isotopic 'old' waters not linked with the present hydrologic cycle. (author)

  12. Magma Plumbing beneath Askja Volcano, Iceland

    Science.gov (United States)

    Greenfield, T. S.; White, R. S.

    2013-12-01

    Through a combination of accurate earthquake locations and tomography we have imaged the melt feeding network beneath Askja, a large central volcano, in the Northern Volcanic Zone, Iceland. We have deployed and operated a dense network of 3-component, broadband seismometers around the volcano since 2006 and have recorded a large number of events (on the order of 150 a day). The majority of these are due to an extensive geothermal area within the caldera and tectonically induced earthquakes to the northeast which are not related to the magma plumbing system. More intriguing are the less numerous deeper earthquakes situated in three distinct areas within the volcanic system. These have a lower frequency content to the shallower events which may be the result of highly attenuating lower crust. The deep earthquakes extend from 12-25 km depth, significantly below a well defined brittle-ductile boundary at 8-9 km. These earthquakes indicate the presence of melt moving or degassing at depth as only high strain rates or increased pore fluid pressures would cause brittle fracture in what is normally an aseismic region in the ductile zone. To image the structure beneath Askja, local and regional earthquakes have been used as sources to solve for the velocity structure beneath the volcano. Travel-time tables were created using a finite difference technique and the residuals were used to solve simultaneously for both the earthquake locations and velocity structure. Results showed a pronounced low-velocity anomaly beneath the caldera at a depth of ~5 km. The anomaly is ~10% slower than the initial best fitting 1D model and has a Vp/Vs ratio higher than the surrounding crust, suggesting the presence of increased temperature or partial melt. The body is unlikely to be entirely melt as S-waves are still detected at stations directly above the anomaly. This low-velocity body is slightly deeper than the depth range suggested by InSAR and GPS studies of a deflating source beneath

  13. Lithosphere mapping beneath the North American plate

    Science.gov (United States)

    Griffin, W. L.; O'Reilly, Suzanne Y.; Doyle, B. J.; Pearson, N. J.; Coopersmith, H.; Kivi, K.; Malkovets, V.; Pokhilenko, N.

    2004-09-01

    Major- and trace-element analyses of garnets from heavy-mineral concentrates have been used to derive the compositional and thermal structure of the subcontinental lithospheric mantle (SCLM) beneath 16 areas within the core of the ancient Laurentian continent and 11 areas in the craton margin and fringing mobile belts. Results are presented as stratigraphic sections showing variations in the relative proportions of different rock types and metasomatic styles, and the mean Fo content of olivine, with depth. Detailed comparisons with data from mantle xenoliths demonstrate the reliability of the sections. In the Slave Province, the SCLM in most areas shows a two-layer structure with a boundary at 140-160 km depth. The upper layer shows pronounced lateral variations, whereas the lower layer, after accounting for different degrees of melt-related metasomatism, shows marked uniformity. The lower layer is interpreted as a subcreted plume head, added at ca. 3.2 Ga; this boundary between the layers rises to <100 km depth toward the northern and southern edges of the craton. Strongly layered SCLM suggests that plume subcretion may also have played a role in the construction of the lithosphere beneath Michigan and Saskatchewan. Outside the Slave Province, most North American Archon SCLM sections are less depleted than similar sections in southern Africa and Siberia; this may reflect extensive metasomatic modification. In E. Canada, the degree of modification increases toward the craton margin, and the SCLM beneath the Kapuskasing Structural Zone is typical of that beneath Proterozoic to Phanerozoic mobile belts. SCLM sections from several Proterozoic areas around the margin of the Laurentian continental core (W. Greenland, Colorado-Wyoming district, Arkansas) show discontinuities and gaps that are interpreted as the effects of lithosphere stacking during collisional orogeny. Some areas affected by Proterozoic orogenesis (Wyoming Craton, Alberta, W. Greenland) appear to retain

  14. Subsurface imaging reveals a confined aquifer beneath an ice-sealed Antarctic lake

    DEFF Research Database (Denmark)

    Dugan, H. A.; Doran, P. T.; Tulaczyk, S.;

    2015-01-01

    Liquid water oases are rare under extreme cold desert conditions found in the Antarctic McMurdo Dry Valleys. Here we report geophysical results that indicate that Lake Vida, one of the largest lakes in the region, is nearly frozen and underlain by widespread cryoconcentrated brine. A ground penet...

  15. Nitrogen sources and sinks in a wastewater impacted saline aquifer beneath the Florida Keys, USA

    Science.gov (United States)

    Dillon, Kevin S.; Chanton, Jeffrey P.; Smith, Leslie K.

    2007-06-01

    Groundwater wells surrounding a high volume advance treatment wastewater (ATW) disposal well in the Florida Keys were monitored for nitrate, nitrite, and ammonium concentrations over a 14 month period. Nutrient concentrations in the shallow subsurface (9 m) show a bimodal distribution between the low salinity wastewater plume and the ambient brackish to saline groundwaters. High NO 3- concentrations are found within the ATW plume while the highest NH 4+ concentrations are found in shallow wells outside of the plume. Evidence suggests that the overlying mud layer unique to this study site contributes the bulk of the NH 4+ observed in these wells. NO 3- concentrations at 9 m wells varied by a factor of four in response to concurrent variations in ATW NO 3- loads over the coarse of the study. Estimated NO 3- uptake rates varied from 32 ± 29 to 98 ± 69 and did not directly correlate with ATW NO 3- loading as we hypothesized. We estimate that 70 ± 34% of the NO 3- from the treatment plant is removed from solution in the subsurface of the study site. Considerable decreases in NO 3- concentration and enrichment of 15NO 3- was observed in many wells, indicating significant denitrification or anaerobic ammonium oxidation is occurring in the subsurface. Dissolved inorganic nitrogen concentrations, distributions, and 15N compositions indicate that denitrification is likely the dominant mechanism for N removal in the ATW plume at Key Colony Beach, Florida.

  16. Sole Source Aquifers for NY and NJ

    Data.gov (United States)

    U.S. Environmental Protection Agency — This layer is the designated sole source aquifers of New York and New Jersey. A Sole Source Aquifer, is an aquifer that supplies 50% or more of the drinking water...

  17. Undercover Marketing : The method which lies beneath

    OpenAIRE

    Stenberg, Karolina; Pracic, Sabina

    2005-01-01

    Background: A coming of age of a generation named Generation Y, which holds negative views on commercial messages, has resulted in the need of special marketing methods which are known to be more alternative. Guerrilla Marketing, being such a method holds beneath it Undercover Marketing which is another method and has the potential of reaching this generation. Purpose: Our purpose is firstly to define a theoretical placement of Undercover Marketing, secondly to define the theoretical views on...

  18. Seismic Anisotropy Beneath the Sumatra Subduction Zone

    OpenAIRE

    R. Collings; Rietbrock, A.; S. Mippress; Lange, D.; D. Natawidjaja; B. Suwargadi; Frederik Tilmann

    2011-01-01

    The Sumatra subduction zone is located on the eastern side of the Sunda Arc between the Sunda Strait and the Andaman Islands, where the Indo-Australian plate is subducting beneath the Eurasian plate. An important tool in understanding the style and geometry of deformation within a subduction zone is the measurement of seismic anisotropy, through observations of shear wave splitting, which provides information about the mantle flow. In Sumatra two temporary seismic networks were deployed withi...

  19. Oceanographic conditions beneath Fimbul Ice Shelf, Antarctica

    OpenAIRE

    Abrahamsen, Einar Povl

    2012-01-01

    Antarctic ice shelves play a key role in the global climate system, acting as important sites for the cooling of shelf waters, thereby facilitating deep and bottom water formation. Many of the processes that take place under large ice shelves can be observed more conveniently beneath smaller ice shelves such as Fimbul Ice Shelf, an ice shelf in the eastern Weddell Sea. Fimbul Ice Shelf and nearby ice shelves might also play a significant regional role: although no bottom water is produced in ...

  20. Subsurface storage of liquids in the Floridan aquifer system in south Florida

    Science.gov (United States)

    Meyer, Frederick W.

    1989-01-01

    The Floridan aquifer system in south Florida is composed chiefly of carbonate rocks that range in age from early Miocene to Paleocene. The top of the Floridian aquifer system generally occurs at depths ranging from 500 to 1,000 ft, and the average thickness is about 3,000 ft. It is divided into three general hydrogeologic units that include Upper Floridan aquifer, the middle confining unit, and the Lower Floridan aquifer. Groundwater movement in the Upper Floridan aquifer is generally from the area of highest head in central Florida, eastward to the Straits of Florida, westward to the Gulf of Mexico, and, to a much lesser extent, southward. Injection of nontoxic liquid wastes into deep, saline parts of the Floridan aquifer system as a pollution-control measure began in 1943 with injection of oilfield brine in southwest Florida. Since then, the practice has quickly expanded, and many high capacity municipal and industrial injection wells are now in operation in southeast Florida. The principal use of the Floridan aquifer system in south Florida is for subsurface storage of liquid waste. The Boulder Zone of the Lower Floridan aquifer is extensively used as a receptacle for injected treated municipal wastewater, oilfield brine and, to a lesser extent, industrial wastewater. Pilot studies indicate a potential for cyclic storage of freshwater in the Upper Floridan aquifer in south Florida. (USGS)

  1. Convective shutdown of CO2 in saline aquifers

    Science.gov (United States)

    Neufeld, J. A.; Hewitt, D. R.; Lister, J. R.

    2013-12-01

    Convective flow in a porous medium, driven by a buoyancy source along one boundary, is common in active geothermal aquifers and in the presence of evaporation in saline aquifers. More recently, convection driven by the dissolution of injected CO2 in saline aquifers has been shown to reduce the volume of mobile CO2 in carbon sequestration sites and analogues, thus reducing any concomitant risks of leakage. For carbon sequestration the rates of dissolution can depend strongly on the background CO2 concentration, and hence might be expected to wane in time. Here we present a simple analytic box model of the shutdown of convection in a closed aquifer, and compare these reduced model results against high-resolution numerical and analogue experiments. We find that the box model accurately captures the dynamics of the convective fluxes, and provides time scale over which free-phase CO2 may be completely removed. Furthermore, the model may provide insight into the geochemical record of dissolution in the deep carbon cycle.

  2. Sustainable Ground Water Development in Hard Rock Aquifers in Low-Income Countries and the Role of UNESCO _ IUGS - IGCP projec -GROWNET-

    OpenAIRE

    S. D. Limaye

    2010-01-01

    Hard rock aquifers for the purpose of this Paper mean the non-carbonate, fractured rock aquifers in the terrain covered by crystalline basement complex, metamorphic rocks and also by extensive effusive volcanic rocks like the basalts of western India (Deccan traps. Ground water development in hard rock aquifer areas has always played a secondary role compared to that in the areas having high-yielding unconsolidated or semi-consolidated sediments and carbonate rocks. This has been due to the r...

  3. Yucca Mountain Area Saturated Zone Dissolved Organic Carbon Isotopic Data

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, James; Decker, David; Patterson, Gary; Peterman, Zell; Mihevc, Todd; Larsen, Jessica; Hershey, Ronald

    2007-06-25

    Groundwater samples in the Yucca Mountain area were collected for chemical and isotopic analyses and measurements of water temperature, pH, specific conductivity, and alkalinity were obtained at the well or spring at the time of sampling. For this project, groundwater samples were analyzed for major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC). The U.S. Geological Survey (USGS) performed all the fieldwork on this project including measurement of water chemistry field parameters and sample collection. The major ions dissolved in the groundwater, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) were analyzed by the USGS. All preparation and processing of samples for DOC carbon isotopic analyses and geochemical modeling were performed by the Desert Research Institute (DRI). Analysis of the DOC carbon dioxide gas produced at DRI to obtain carbon-13 and carbon-14 values was conducted at the University of Arizona Accelerator Facility (a NSHE Yucca Mountain project QA qualified contract facility). The major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of DIC were used in geochemical modeling (NETPATH) to determine groundwater sources, flow paths, mixing, and ages. The carbon isotopes of DOC were used to calculate groundwater ages that are independent of DIC model corrected carbon-14 ages. The DIC model corrected carbon-14 calculated ages were used to evaluate groundwater travel times for mixtures of water including water beneath Yucca Mountain. When possible, groundwater travel times were calculated for groundwater flow from beneath Yucca Mountain to down gradient sample sites. DOC carbon-14 groundwater ages were also calculated for groundwaters in the Yucca Mountain area. When possible, groundwater travel times were estimated for groundwater flow from beneath Yucca Mountain to down gradient groundwater sample sites using the DOC calculated

  4. Analysis of groundwater flow beneath ice sheets

    Energy Technology Data Exchange (ETDEWEB)

    Boulton, G. S.; Zatsepin, S.; Maillot, B. [Univ. of Edinburgh (United Kingdom). Dept. of Geology and Geophysics

    2001-03-01

    The large-scale pattern of subglacial groundwater flow beneath European ice sheets was analysed in a previous report. It was based on a two-dimensional flowline model. In this report, the analysis is extended to three dimensions by exploring the interactions between groundwater and tunnel flow. A theory is developed which suggests that the large-scale geometry of the hydraulic system beneath an ice sheet is a coupled, self-organising system. In this system the pressure distribution along tunnels is a function of discharge derived from basal meltwater delivered to tunnels by groundwater flow, and the pressure along tunnels itself sets the base pressure which determines the geometry of catchments and flow towards the tunnel. The large-scale geometry of tunnel distribution is a product of the pattern of basal meltwater production and the transmissive properties of the bed. The tunnel discharge from the ice margin of the glacier, its seasonal fluctuation and the sedimentary characteristics of eskers are largely determined by the discharge of surface meltwater which penetrates to the bed in the terminal zone. The theory explains many of the characteristics of esker systems and can account for tunnel valleys. It is concluded that the large-scale hydraulic regime beneath ice sheets is largely a consequence of groundwater/tunnel flow interactions and that it is essential similar to non-glacial hydraulic regimes. Experimental data from an Icelandic glacier, which demonstrates measured relationships between subglacial tunnel flow and groundwater flow during the transition from summer to winter seasons for a modern glacier, and which support the general conclusions of the theory is summarised in an appendix.

  5. Analysis of groundwater flow beneath ice sheets

    International Nuclear Information System (INIS)

    The large-scale pattern of subglacial groundwater flow beneath European ice sheets was analysed in a previous report. It was based on a two-dimensional flowline model. In this report, the analysis is extended to three dimensions by exploring the interactions between groundwater and tunnel flow. A theory is developed which suggests that the large-scale geometry of the hydraulic system beneath an ice sheet is a coupled, self-organising system. In this system the pressure distribution along tunnels is a function of discharge derived from basal meltwater delivered to tunnels by groundwater flow, and the pressure along tunnels itself sets the base pressure which determines the geometry of catchments and flow towards the tunnel. The large-scale geometry of tunnel distribution is a product of the pattern of basal meltwater production and the transmissive properties of the bed. The tunnel discharge from the ice margin of the glacier, its seasonal fluctuation and the sedimentary characteristics of eskers are largely determined by the discharge of surface meltwater which penetrates to the bed in the terminal zone. The theory explains many of the characteristics of esker systems and can account for tunnel valleys. It is concluded that the large-scale hydraulic regime beneath ice sheets is largely a consequence of groundwater/tunnel flow interactions and that it is essential similar to non-glacial hydraulic regimes. Experimental data from an Icelandic glacier, which demonstrates measured relationships between subglacial tunnel flow and groundwater flow during the transition from summer to winter seasons for a modern glacier, and which support the general conclusions of the theory is summarised in an appendix

  6. Multidisciplinary approach to identify aquifer-peatland connectivity

    Science.gov (United States)

    Larocque, Marie; Pellerin, Stéphanie; Cloutier, Vincent; Ferlatte, Miryane; Munger, Julie; Quillet, Anne; Paniconi, Claudio

    2015-04-01

    In southern Quebec (Canada), wetlands sustain increasing pressures from agriculture, urban development, and peat exploitation. To protect both groundwater and ecosystems, it is important to be able to identify how, where, and to what extent shallow aquifers and wetlands are connected. This study focuses on peatlands which are especially abundant in Quebec. The objective of this research was to better understand aquifer-peatland connectivity and to identify easily measured indicators of this connectivity. Geomorphology, hydrogeochemistry, and vegetation were selected as key indicators of connectivity. Twelve peatland transects were instrumented and monitored in the Abitibi (slope peatlands associated with eskers) and Centre-du-Quebec (depression peatlands) regions of Quebec (Canada). Geomorphology, geology, water levels, water chemistry, and vegetation species were identified/measured on all transects. Flow conditions were simulated numerically on two typical transects. Results show that a majority of peatland transects receives groundwater from a shallow aquifer. In slope peatlands, groundwater flows through the organic deposits towards the peatland center. In depression peatlands, groundwater flows only 100-200 m within the peatland before being redirected through surface routes towards the outlet. Flow modeling and sensitivity analysis have identified that the thickness and hydraulic conductivity of permeable deposits close to the peatland and beneath the organic deposits influence flow directions within the peatland. Geochemical data have confirmed the usefulness of total dissolved solids (TDS) exceeding 14 mg/L as an indicator of the presence of groundwater within the peatland. Vegetation surveys have allowed the identification of species and groups of species that occur mostly when groundwater is present, for instance Carex limosa and Sphagnum russowii. Geomorphological conditions (slope or depression peatland), TDS, and vegetation can be measured

  7. Multi Plumes and Their Flows beneath Arabia and East Africa

    Science.gov (United States)

    Chang, S.; van der Lee, S.

    2010-12-01

    The three-dimensional S-velocity structure beneath Arabia and East Africa is estimated down to the lower mantle to investigate vertical and horizontal extension of low-velocity anomalies that bear out the presence of mantle plumes and their flows beneath lithosphere. We estimated this model through joint inversion of teleseismic S- and SKS-arrival times, regional S- and Rayleigh waveform fits, fundamental-mode Rayleigh-wave group velocities, and independent Moho constraints from receiver functions, reflection/refraction profiles, and gravity measurements. With the unprecedented resolution in our S-velocity model, we found different flow patterns of hot materials upwelling beneath Afar beneath the Red Sea and the Gulf of Aden. While the low-velocity anomaly from Afar is well confined beneath the Gulf of Aden, inferring mantle flow along the gulf, N-S channel of low velocity is found beneath Arabia, not along the Red Sea. The Afar plume is distinctively separate from the Kenya plume, showing its origin in the lower mantle beneath southwestern Arabia. We identified another low-velocity extension to the lower mantle beneath Jordan and northern Arabia, which is thought to have caused volcanism in Jordan, northern Arabia, and possibly southern Turkey. Comparing locations of mantle plumes from the joint inversion with fast axes of shear-wave splitting, we confirmed horizontal plume flow from Afar in NS direction beneath Arabia and in NE-SW direction beneath Ethiopia as a likely cause of the observed seismic anisotropy.

  8. Factors Affecting Spatial and Temporal Variability in Nutrient and Pesticide Concentrations in the Surficial Aquifer on the Delmarva Peninsula

    Science.gov (United States)

    Debrewer, Linda M.; Ator, Scott W.; Denver, Judith M.

    2007-01-01

    milligrams per liter (as nitrogen). In addition to land use in the aquifer recharge area, concentrations of nitrate in ground water are related to regional patterns in soil drainage that affect underlying aquifer redox conditions. Over the peninsula, nitrate concentrations are not related to recharge date of the water, but are positively correlated with depth in shallow wells screened beneath agricultural areas. Nitrate concentrations increased in oxic areas (dissolved oxygen greater than 1 milligram per liter) of the deeper part of the surficial aquifer used for domestic supply by an average of about 2 milligrams per liter between 1988 and 2001, although no changes were apparent in shallower parts of the aquifer over that same period. Water in the surficial aquifer generally flows from land-surface recharge to surface-water discharge areas in less than 30 years. As a result, the entire flow system in the surficial aquifer has likely been affected by human activities on and near the land surface over the past several decades. Pesticide compounds occurred widely at low levels throughout the surficial aquifer. The most commonly used herbicides (metolachlor, alachlor, and atrazine) were the most commonly detected. These pesticides primarily occurred in ground water in the form of degradation products. The widespread occurrence of these and other pesticide compounds reflects their abundant use as well as chemical properties and aquifer characteristics that allow their movement into ground water. Mixtures of pesticides are common. Most samples contained at least 3 different compounds; several samples contained as many as 11. Pesticide concentrations in the surficial aquifer are relatively high beneath recharge areas with well-drained soils in the shallow part of the aquifer and in oxic environments throughout the surficial aquifer. Concentrations are generally below existing drinking-water standards, although standards are not available for all of the pesticide compound

  9. Imaging the Indian subcontinent beneath the Himalaya.

    Science.gov (United States)

    Schulte-Pelkum, Vera; Monsalve, Gaspar; Sheehan, Anne; Pandey, M R; Sapkota, Som; Bilham, Roger; Wu, Francis

    2005-06-30

    The rocks of the Indian subcontinent are last seen south of the Ganges before they plunge beneath the Himalaya and the Tibetan plateau. They are next glimpsed in seismic reflection profiles deep beneath southern Tibet, yet the surface seen there has been modified by processes within the Himalaya that have consumed parts of the upper Indian crust and converted them into Himalayan rocks. The geometry of the partly dismantled Indian plate as it passes through the Himalayan process zone has hitherto eluded imaging. Here we report seismic images both of the decollement at the base of the Himalaya and of the Moho (the boundary between crust and mantle) at the base of the Indian crust. A significant finding is that strong seismic anisotropy develops above the decollement in response to shear processes that are taken up as slip in great earthquakes at shallower depths. North of the Himalaya, the lower Indian crust is characterized by a high-velocity region consistent with the formation of eclogite, a high-density material whose presence affects the dynamics of the Tibetan plateau. PMID:15988523

  10. Impact of managed aquifer recharge on the chemical and isotopic composition of a karst aquifer, Wala reservoir, Jordan

    Science.gov (United States)

    Xanke, Julian; Goeppert, Nadine; Sawarieh, Ali; Liesch, Tanja; Kinger, Jochen; Ali, Wasim; Hötzl, Heinz; Hadidi, Khair; Goldscheider, Nico

    2015-08-01

    Storm-water harvesting and storage via managed aquifer recharge (MAR) is a promising approach to combat water scarcity in semi-arid regions, but poses a challenge for karst aquifers and regions with highly variable water availability. The infiltration of low-mineralized surface water and its impact on highly mineralized groundwater of a karst aquifer was investigated at Wala reservoir in Jordan over a period of approximately 10 years. The results show significant groundwater-level rise in a wellfield, in response to the yearly average infiltration of about 6.7 million m3. This corresponds to about 60 % of the yearly average abstraction of about 11.7 million m3, confirmed by mixing calculations with tritium. A decreasing trend in infiltration due to sedimentation is observed. Mean groundwater residence times of several thousand years, derived from carbon-14 dating, indicate a large storage capacity of the aquifer. The heterogeneous distribution of the residence times is caused by strong groundwater withdrawals and artificial recharge along with karst-specific aquifer characteristics. Temporal groundwater salinity fluctuations in the wellfield are observed after the first MAR infiltration. Enhanced groundwater flow along the wadi course was demonstrated, which is an important aspect with regards to future MAR projects in similar wadis of the region.

  11. Potential for formation of disinfection by-products from storage of chlorinated surface water in the Basalt aquifer near Fallon, Nevada

    Science.gov (United States)

    Fram, Miranda S.; Maurer, Douglas K.; Lico, Michael S.

    2005-01-01

    that the amount of organic carbon released from the rocks during successive cycles of recharge, storage, and recovery of chlorinated surface water may be relatively small. The chlorine demand of the rocks is so large that all of the free chlorine in the entire volume of recharged water likely would be consumed by only a very small volume of the aquifer surrounding an injection well, or beneath an infiltration bed. The majority of the volume of the aquifer filled by the stored water likely would never come in contact with free chlorine, and the increases in concentration of DOC observed in these experiments likely would occur in a very small volume of the stored water. For this reason, increases in concentration of THMs for the entire volume of water stored also likely would be considerably less than those measured in these experiments. To test this hypothesis, additional laboratory experiments using varying levels of chlorination, varying lengths of reaction periods, and repeated cycles of chlorination would be useful. A field experiment made at a small scale in an isolated part of the basalt aquifer would aid in the design of an operational system.

  12. Shear Wave Splitting Beneath the Galapagos Archipelago

    Science.gov (United States)

    Fontaine, F. R.; Burkett, P. G.; Hooft, E. E.; Toomey, D. R.; Solomon, S. C.; Silver, P. G.

    2004-12-01

    We report measurements of teleseismic shear wave splitting in the Galápagos Archipelago. The inferred lateral variations in azimuthal anisotropy allow us to examine the dynamics of an evolving hotspot-ridge system. The data are from SKS and SKKS phases, as well as S waves from deep sources, recorded by a relatively dense network of 10 portable broadband seismometers deployed from 1999 to 2003 for the IGUANA (Imaging Galápagos Upwelling and Neotectonics of the Archipelago) experiment and from the GSN broadband station in Santa Cruz (PAYG). We find a delay time between fast and slow shear waves of 0.4 to 0.9 s and fast polarization directions of N85-90° E beneath five stations at the leading and southern edge of the archipelago. Despite clear seismic signals, we did not find any anisotropy at the six stations located in the interior of the archipelago. For those stations that show shear wave splitting, there is an increase in the delay time toward the expected location of the Galápagos hotspot at the western edge of the archipelago. With the exception of Española, fast polarization directions (N85-90° E) are close to the current direction of absolute plate motion of the overlying Nazca plate (N91° E). The lack of azimuthal anisotropy in the interior of the archipelago is interpreted as an absence of strongly oriented mantle fabric beneath these stations. The apparent isotropy in this dynamic region, where we expect considerable mantle strain, is surprising. It is not likely that the olivine a-axis is oriented vertically beneath the interior of the archipelago as the Galápagos plume is thought to lie at the western edge. It is also unlikely that there are two layers of perpendicularly-oriented anisotropy which are solely confined to the center of the archipelago. However, there appears to be some correlation between the region of apparent isotropy and a zone of anomalously low upper mantle velocities imaged beneath Santiago and Marchena from surface waves by

  13. Mississippi River Valley alluvial aquifer

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the extent of the Mississippi River Valley alluvial aquifer in the states of Missouri, Kentucky, Tennessee, Arkansas, Mississippi, and...

  14. Southeastern Coastal Plain aquifer system

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the extent of the Southeastern Coastal Plain aquifer system in Kentucky, Tennessee, Mississippi, Alabama, Georgia, and South Carolina.

  15. Region 9 Sole Source Aquifers

    Data.gov (United States)

    U.S. Environmental Protection Agency — There are 7 polygons representing 6 individual sole source aquifer boundaries and one streamflow source area in California, Arizona, and Nevada. Various efforts...

  16. (SUPERCEDED) High Plains aquifer (SUPERCEDED)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the extent of the High Plains aquifer in the states of South Dakota, Wyoming, Nebraska, Colorado, Kansas, New Mexico, Oklahoma, and Texas....

  17. Digital data sets that describe aquifer characteristics of the Enid isolated terrace aquifer in northwestern Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized aquifer boundaries for the Enid isolated terrace aquifer in northwestern Oklahoma. The Enid isolated terrace aquifer covers...

  18. Digital data sets that describe aquifer characteristics of the Elk City aquifer in western Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized aquifer boundaries for the Elk City aquifer in western Oklahoma. The aquifer covers an area of approximately 193,000 acres and...

  19. Hydrogeochemistry and isotopic tracing of nitrate contamination of two aquifer systems on Jeju Island, Korea.

    Science.gov (United States)

    Koh, Eun-Hee; Kaown, Dugin; Mayer, Bernhard; Kang, Bong-Rae; Moon, Hee Sun; Lee, Kang-Kun

    2012-01-01

    The groundwater of Jeju Island (Republic of Korea) is vulnerable to contamination because its aquifers are mainly composed of highly permeable geological units and its agricultural fields are often exposed to excessive use of predominantly synthetic fertilizers. In the Gosan area of Jeju Island, we investigated nitrate contamination in both a perched aquifer above an impermeable clay bed and the regional groundwater beneath this aquitard. The δO and δD values indicate that the perched groundwater is recharged by local precipitation, whereas the regional groundwater is recharged mainly by regional flow from an adjacent mountainous region. The perched groundwater contained very high NO-N concentrations of up to 87 mg/L. The isotopic composition of nitrate in the perched groundwater showed that synthetic fertilizers applied in high excesses of crop N needs were the main cause of aquifer pollution. Elevated nitrate concentrations were also observed in the regional groundwater especially after precipitation events. Concentration and isotopic data revealed that the inflow of shallow perched groundwater along the poorly cemented or uncemented annulus of regional groundwater wells was one of the main reasons for the nitrate contamination observed in the regional groundwater. In both aquifers, δN and δO values showed that the sources of nitrate were derived from synthetic fertilizers that had been recycled in the soil zone by nitrification and in some portions of the perched aquifer (dissolved oxygen concentrations <2 mg/L) indicated that denitrification occurred locally. PMID:23128740

  20. Microbial dynamics in natural aquifers

    OpenAIRE

    Bajracharya, Bijendra Man

    2016-01-01

    Microorganisms in groundwater form ecosystems that can transform chemical compounds. Quantitatively understanding microbial dynamics in soils and groundwater is thus essential for pollutant dynamics and biogeochemistry in the subsurface. This dissertation addresses three factors influencing microbial dynamics in aquifers and soils, namely: (1) the influence of grazing on bacteria in eutrophic aquifers, posing the question whether the carrying capacity of bacteria, which has been observed i...

  1. Aquifer thermal energy storage program

    Science.gov (United States)

    Fox, K.

    1980-01-01

    The purpose of the Aquifer Thermal Energy Storage Demonstration Program is to stimulate the interest of industry by demonstrating the feasibility of using a geological formation for seasonal thermal energy storage, thereby, reducing crude oil consumption, minimizing thermal pollution, and significantly reducing utility capital investments required to account for peak power requirements. This purpose will be served if several diverse projects can be operated which will demonstrate the technical, economic, environmental, and institutional feasibility of aquifer thermal energy storage systems.

  2. Unravelling aquifer-wetland interaction using CSAMT and gravity methods: the Mollina-Camorra aquifer and the Fuente de Piedra playa-lake, southern Spain

    Science.gov (United States)

    Pedrera, A.; Martos-Rosillo, S.; Galindo-Zaldívar, J.; Rodríguez-Rodríguez, M.; Benavente, J.; Martín-Rodríguez, J. F.; Zúñiga-López, M. I.

    2016-06-01

    The hydrological regime of Fuente de Piedra playa-lake (Málaga, southern Spain) has been significantly affected by the intensive exploitation of groundwater in the area. The playa-lake is situated above clays, marls, and gypsum, and under unaltered conditions received surface-subsurface runoff within the watershed as well as groundwater discharge from two carbonate aquifers. We have analyzed the structure of the main one, the Mollina-Camorra carbonate aquifer, by combining controlled source audio magnetotellurics (CSAMT), gravity prospecting, and time-domain electromagnetic (TDEM) soundings. This geophysical information, together with new structural and hydrogeological data, was gathered to develop a new conceptual hydrogeological model. This model allows the hydrological linkage of the carbonate aquifer with the playa-lake system to be established. Moreover, the intensive exploitation in the carbonate aquifer, even outside the watershed of the playa-lake, has affected the hydrological regime of the system. This multidisciplinary work demonstrates the potential of geophysical methods for understanding wetland-aquifer interaction, having important groundwater management implications.

  3. In-situ biodegradation of tetrachloroethene and trichloroethene in contaminated aquifers monitored by stable isotope fractionation.

    Science.gov (United States)

    Vieth, A; Müller, J; Strauch, G; Kästner, M; Gehre, M; Meckenstock, R U; Richnow, H H

    2003-06-01

    Stable carbon isotope analysis of tetrachloroethene (PCE) and trichloroethene (TCE) was applied to evaluatenatural attenuation processes in the upper Quaternary and lower Tertiary aquifer in the area of a former dry-cleaning plant located in Leipzig, Germany. Groundwater samples were taken during one monitoring campaign in 2001. The 13C enrichment in contaminants along the water flow path suggested that both, PCE and TCE were degraded in the Quaternary aquifer. The enrichment of 13C in the residual PCE fraction and an isotope fractionation factor from laboratory experiments were used to calculate the extent of biodegradation in the Quatemary aquifer. These calculations indicated that a major portion of PCE was biodegraded in the course of the plume. In the Tertiary aquifer the carbon isotope ratios of PCE and TCE indicated that the decreasing concentrations of these contaminants were probably not caused by microbial processes. PMID:12872803

  4. Digital model of predevelopment flow in the Tertiary limestone (Floridan) aquifer system in West-Central Florida

    Science.gov (United States)

    Ryder, Paul D.

    1982-01-01

    A computer model was calibrated to approximate predevelopment flow conditions in a multilayered aquifer system in 10,600 square miles in west-central Floria. The lowermost aquifer, called the Floridan aquifer, is confined in most of the study area and consists of carbonate rocks ranging up to 1,300 feet thick. The Floridan aquifer is the chief source for large withdrawals and natural springflow in the study area. Daily springflows within the study area have averaged about 2.4 billion gallons. The secondary artesian and the surficial aquifers are much less permeable than the Floridan aquifer. Where they are present and have heads higher than those in the Floridan aquifer, they provide recharge to the Floridan. Initial estimates of recharge to the Floridan aquifer were from water-balance calculations for surface-water basins; initial estimates of transmissivity were from aquifer tests and flow-net analyses. The model was calibrated for the predevelopment era, wherein steady-state flow conditions were assumed. Calibrated transmissivities for the Floridan aquifer range from less than 15,000 to several million feet squared per day. Recharge to the system was about 3,700 cubic feet per second. About 90% was discharged as springflow, and 10% was upward leakage. (USGS)

  5. PRESSURE FLUCTUATIONS BENEATH SPATIAL HYDRAULIC JUMPS

    Institute of Scientific and Technical Information of China (English)

    YAN Zhong-min; ZHOU Chun-tian; LU Shi-qiang

    2006-01-01

    This article deals with statistical analysis of pressure fluctuations at the bottom of spatial hydraulic jumps with abrupt lateral expansions. The effects of the channel expansion ratio and inflow condition on the power spectral and dominant frequency were examined. Pressure data were recorded for different Froude numbers ranging from 3.52 to 6.86 and channel expansion ratios ranging from 1.5 to 3.0. A sampling frequency of 100 Hz was selected. The measurements were conducted in the bed of a glass-walled laboratory flume by means of pressure transducers and data acquisition systems. Power spectra as well as dominant frequency and some other statistical characteristics of fluctuating pressure beneath hydraulic jumps were obtained. Test results were compared with those of classical jump, which indicates that the peak frequencies and intensity coefficients of pressure fluctuations are higher than those of the corresponding classical jumps.

  6. Major disruption of D″ beneath Alaska

    Science.gov (United States)

    Sun, Daoyuan; Helmberger, Don; Miller, Meghan S.; Jackson, Jennifer M.

    2016-05-01

    D″ represents one of the most dramatic thermal and compositional layers within our planet. In particular, global tomographic models display relatively fast patches at the base of the mantle along the circum-Pacific which are generally attributed to slab debris. Such distinct patches interact with the bridgmanite (Br) to post-bridgmanite (PBr) phase boundary to generate particularly strong heterogeneity at their edges. Most seismic observations for the D″ come from the lower mantle S wave triplication (Scd). Here we exploit the USArray waveform data to examine one of these sharp transitions in structure beneath Alaska. From west to east beneath Alaska, we observed three different characteristics in D″: (1) the western region with a strong Scd, requiring a sharp δVs = 2.5% increase; (2) the middle region with no clear Scd phases, indicating a lack of D″ (or thin Br-PBr layer); and (3) the eastern region with strong Scd phase, requiring a gradient increase in δVs. To explain such strong lateral variation in the velocity structure, chemical variations must be involved. We suggest that the western region represents relatively normal mantle. In contrast, the eastern region is influenced by a relic slab that has subducted down to the lowermost mantle. In the middle region, we infer an upwelling structure that disrupts the Br-PBr phase boundary. Such an interpretation is based upon a distinct pattern of travel time delays, waveform distortions, and amplitude patterns that reveal a circular-shaped anomaly about 5° across which can be modeled synthetically as a plume-like structure rising about 400 km high with a shear velocity reduction of ~5%, similar to geodynamic modeling predictions of upwellings.

  7. Environmental isotope and hydrochemical investigation on groundwater recharge and dynamics of the coastal sedimentary aquifers of Tiruvadanai, Tamilnadu State, India

    International Nuclear Information System (INIS)

    Recharge processes and dynamics of the Tiruvadanai aquifers were investigated using environmental isotopes and hydrochemistry, in conjunction with hydrogeological data. Hydrochemical characterization of the groundwaters indicated that the shallow (3-Cl) to saline type waters and the deeper (350-500 m) Cretaceous aquifer (confined) is a NaCl type. The concentration of various chemical species along the general groundwater flow direction (northwest to east) showed a trend with a decrease in Mg2+ and Ca2+ and an increase in Na+ and K+ in both the aquifers. This change could be attributed to ion-exchange process. Higher pH values of Cretaceous aquifer samples (7.4-8.6) could also be responsible for the lowering of Mg2+ and Ca2+ concentrations by facilitating precipitation of carbonates. A δ2H-δ18O plot shows that the Tertiary aquifer samples fall on an evaporation line. The aquifer 3H values near the ephemeral rivers range from 2 to 5 TU while those away from the rivers have 14CDIC model ages range from 1 to 13 Ka BP. The Cretaceous aquifer samples had 3H values 14CDIC model ages are >20 ka BP, indicating palaeo-waters. Based on 14C model ages, the groundwater velocity was estimated (Tertiary aquifers: 10-2-10-3 m·d-1; Cretaceous aquifer: 10-3 m·d-1). A 13CDIC enrichment along the flowpath of the Cretaceous aquifer was observed and could be due to carbonate mineral dissolution. From the investigation, four types of recharge processes to the aquifer system are discerned, with the overall modern recharge component being low. The Cretaceous aquifer contains fossil groundwaters and hence, the resources may be finite and thus, their exploitation is mining. The most suitable river for implementing large-scale artificial recharge measures was also identified. (author)

  8. 1994 conceptual model of the carbon tetrachloride contamination in the 200 West Area at the Hanford Site

    International Nuclear Information System (INIS)

    Between 1955 and 1973, a total of 363,000 to 580,000 L (577,000 to kg) of liquid carbon tetrachloride, in mixtures with other organic and aqueous, actinide-bearing fluids, were discharged to the soil column at three disposal facilities -- the 216-Z-9 Trench, the 216-Z-lA TiTe Field, and the 216-Z-18 Crib -- in the 200 West Area at the Hanford Site. In the mid-1980's, dissolved carbon tetrachloride was found in the uppermost aquifer beneath the disposal facilities, and in late 1990, the US Environmental Protection Agency and the Washington State Department of Ecology requested that the US Department of Energy proceed with planning and implementation of an expedited response action (ERA) to minimize additional carbon tetrachloride contamination of the groundwater. In February 1992, soil vapor extraction was initiated to remove carbon tetrachloride from the unsaturated zone beneath these disposal facilities. By May 1994, a total of 10,560 L (16,790 kg) of carbon tetrachloride had been removed, amounting to an estimated 2% of the discharged inventory. In the spring of 1991, the Volatile Organic Compounds -- Arid Integrated Demonstration (VOC-Arid ID) program selected the carbon tetrachloride-contaminated site for demonstration and deployment of new technologies for evaluation and cleanup of volatile organic compounds and associated contaminants in soils and groundwater at arid sites. Site investigations conducted in support of both the ERA and the VOC-Arid ID have been integrated because of their shared objective to refine the conceptual model of the site and to promote efficiency. Site characterization data collected in fiscal year 1993 have supported and led to refinement of the conceptual model of the carbon tetrachloride site

  9. Microgravity methods for characterization of groundwater-storage changes and aquifer properties in the karstic Madison aquifer in the Black Hills of South Dakota, 2009-12

    Science.gov (United States)

    Koth, Karl R.; Long, Andrew J.

    2012-01-01

    A study of groundwater storage in the karstic Madison aquifer in the Black Hills of South Dakota using microgravity methods was conducted by the U.S. Geological Survey in cooperation with West Dakota Water Development District, South Dakota Department of Environment and Natural Resources, and Lawrence County. Microgravity measurements from 2009 to 2012 were used to investigate groundwater-storage changes and effective porosity in unconfined areas of the Madison aquifer. Time-lapse microgravity surveys that use portable high-sensitivity absolute and relative gravimeters indicated temporal-gravity changes as a result of changing groundwater mass. These extremely precise measurements of gravity required characterization and removal of internal instrumental and external environmental effects on gravity from the raw data. The corrected data allowed groundwater-storage volume to be quantified with an accuracy of about plus or minus 0.5 foot of water per unit area of aquifer. Quantification of groundwater-storage change, coupled with water-level data from observation wells located near the focus areas, also was used to calculate the effective porosity at specific altitudes directly beneath gravity stations. Gravity stations were established on bedrock outcrops in three separate focus areas for this study. The first area, the Spring Canyon focus area, is located to the south of Rapid City with one gravity station on the rim of Spring Canyon near the area where Spring Creek sinks into the Madison aquifer. The second area, the Doty focus area, is located on outcrops of the Madison Limestone and Minnelusa Formation to the northwest of Rapid City, and consists of nine gravity stations. The third area, the Limestone Plateau focus area, consists of a single gravity station in the northwestern Black Hills located on an outcrop of the Madison Limestone. An absolute-gravity station, used to tie relative-gravity survey data together, was established on a relatively impermeable

  10. Data sources on aquifers - Descriptions; Datengrundlagen zu den Aquiferen

    Energy Technology Data Exchange (ETDEWEB)

    Wyss, R.

    2010-07-01

    This short report for the Swiss Federal Office of Energy (SFOE) is one of a series of appendices dealing with the potential for geological sequestration of carbon dioxide in Switzerland. This appendix provides details on the most important factors concerning CO{sub 2} sequestration in depths of 800 to 2,500 metres such as permeability, hydraulic pressures and salinity. The appendix notes various drilling activities and provides short overviews concerning the properties of the various geological aquifer layers.

  11. Mantle plumes and associated flow beneath Arabia and East Africa

    Science.gov (United States)

    Chang, Sung-Joon; Van der Lee, Suzan

    2011-02-01

    We investigate mantle plumes and associated flow beneath the lithosphere by imaging the three-dimensional S-velocity structure beneath Arabia and East Africa. This image shows elongated vertical and horizontal low-velocity anomalies down to at least mid mantle depths. This three-dimensional S-velocity model is obtained through the joint inversion of teleseismic S- and SKS-arrival times, regional S- and Rayleigh waveform fits, fundamental-mode Rayleigh-wave group velocities, and independent Moho constraints from receiver functions, reflection/refraction profiles, and gravity measurements. In the resolved parts of our S-velocity model we find that the Afar plume is distinctly separate from the Kenya plume, showing the Afar plume's origin in the lower mantle beneath southwestern Arabia. We identify another quasi-vertical low-velocity anomaly beneath Jordan and northern Arabia which extends into the lower mantle and may be related to volcanism in Jordan, northern Arabia, and possibly southern Turkey. Comparing locations of mantle plumes from the joint inversion with fast axes of shear-wave splitting, we confirm horizontal mantle flow radially away from Afar. Low-velocity channels in our model support southwestward flow beneath Ethiopia, eastward flow beneath the Gulf of Aden, but not northwestwards beneath the entire Red Sea. Instead, northward mantle flow from Afar appears to be channeled beneath Arabia.

  12. Saline Groundwater from Coastal Aquifers As a Source for Desalination.

    Science.gov (United States)

    Stein, Shaked; Russak, Amos; Sivan, Orit; Yechieli, Yoseph; Rahav, Eyal; Oren, Yoram; Kasher, Roni

    2016-02-16

    Reverse osmosis (RO) seawater desalination is currently a widespread means of closing the gap between supply and demand for potable water in arid regions. Currently, one of the main setbacks of RO operation is fouling, which hinders membrane performance and induces pressure loss, thereby reducing system efficiency. An alternative water source is saline groundwater with salinity close to seawater, pumped from beach wells in coastal aquifers which penetrate beneath the freshwater-seawater interface. In this research, we studied the potential use of saline groundwater of the coastal aquifer as feedwater for desalination in comparison to seawater using fieldwork and laboratory approaches. The chemistry, microbiology and physical properties of saline groundwater were characterized and compared with seawater. Additionally, reverse osmosis desalination experiments in a cross-flow system were performed, evaluating the permeate flux, salt rejection and fouling propensities of the different water types. Our results indicated that saline groundwater was significantly favored over seawater as a feed source in terms of chemical composition, microorganism content, silt density, and fouling potential, and exhibited better desalination performance with less flux decline. Saline groundwater may be a better water source for desalination by RO due to lower fouling potential, and reduced pretreatment costs. PMID:26810309

  13. Hydrologic and Geochemical Evaluation of Aquifer Storage Recovery in the Santee Limestone/Black Mingo Aquifer, Charleston, South Carolina, 1998-2002

    Science.gov (United States)

    Petkewich, Matthew D.; Parkhurst, David L.; Conlon, Kevin J.; Campbell, Bruce G.; Mirecki, June E.

    2004-01-01

    The hydrologic and geochemical effects of aquifer storage recovery were evaluated to determine the potential for supplying the city of Charleston, South Carolina, with large quantities of potable water during emergencies, such as earthquakes, hurricanes, or hard freezes. An aquifer storage recovery system, including a production well and three observation wells, was installed at a site located on the Charleston peninsula. The focus of this study was the 23.2-meter thick Tertiary-age carbonate and sand aquifer of the Santee Limestone and the Black Mingo Group, the northernmost equivalent of the Floridan aquifer system. Four cycles of injection, storage, and recovery were conducted between October 1999 and February 2002. Each cycle consisted of injecting between 6.90 and 7.19 million liters of water for storage periods of 1, 3, or 6 months. The volume of recovered water that did not exceed the U.S. Environmental Protection Agency secondary standard for chloride (250 milligrams per liter) varied from 1.48 to 2.46 million liters, which is equivalent to 21 and 34 percent of the total volume injected for the individual tests. Aquifer storage recovery testing occurred within two productive zones of the brackish Santee Limestone/Black Mingo aquifer. The individual productive zones were determined to be approximately 2 to 4 meters thick, based on borehole geophysical logs, electromagnetic flow-meter testing, and specific-conductance profiles collected within the observation wells. A transmissivity and storage coefficient of 37 meters squared per day and 3 x 10-5, respectively, were determined for the Santee Limestone/Black Mingo aquifer. Water-quality and sediment samples collected during this investigation documented baseline aquifer and injected water quality, aquifer matrix composition, and changes in injected/aquifer water quality during injection, storage, and recovery. A total of 193 water-quality samples were collected and analyzed for physical properties, major and

  14. Numerical modeling of regional ground-water flow in the deep-basin brine aquifer of the Palo Duro Basin, Texas Panhandle

    International Nuclear Information System (INIS)

    Bedded Permian-age evaporite sequences in the Palo Duro Basin are being considered for a permanent nuclear waste repository by the U.S. Department of Energy. The purpose of this modeling study is to provide an understanding of regional ground-water flow in the formations beneath the Permian evaporite section. From this understanding, more detailed, smaller scale studies can be designed. This study is also intended to provide a better understanding of the boundary conditions and permeabilities of the aquifer and aquitard system as well as provide estimates of ground-water travel times across the basin. Numerical simulations were made of the Wolfcamp aquifer modeled as a single layer and of the entire Deep-Basin Brine aquifer system, including the Wolfcamp aquifer, modeled as a single layer

  15. Hydrogeochemical study of water in some aquifers of the Estado de Mexico

    International Nuclear Information System (INIS)

    The National Institute of Nuclear Research of Mexico (ININ), has developed a technique that allows to study the association of recharge mechanisms, residence times of the water in the aquifers, as well as the local lithology and the geochemical parameters. The viability of this technique was proven on November 2004 in the aquifers (La Perita, El Tunel y El Pedregal) located in the Asuncion Tepexoyuca, Estado de Mexico. It was observed that so much the aquifer El Tunel like La Perita are used for the human consumption, the aquifer of El Pedregal is used for the fish cultivation. The studies were carried out during March 2003 to November 2004. In the aquifer La Perita the maximum values of the radon concentration (0.76 Bq L-1) they were observed in the summertime time (December). In the spring El Tunel the maximum values of the radon concentration (4.08 Bq L-1) they were observed in the rainy season (September) this increment can be due to the contributions of the recharge of aquifers that it allows the haulage of the radon of other alternating roads of infiltration of the rain water. Of the physicochemical and radiochemical analyses carried out in the water samples of the studied aquifers, it is deduced that they are waters of good quality since for the human consumption since that they are inside on the maximum permissible limits as for their potability according to national and international standards. Likewise it was observed that the water of the aquifers is a single aquifer, since that its differences they due to the time of permanency of the water inside the aquifer. The classification of the underground water deduced that it is calcic and/or magnesic bi carbonated water belonging to the type of meteoric waters of recent infiltration. (Author)

  16. As contamination in Mercedes aquifer groundwater

    International Nuclear Information System (INIS)

    This work is about the quality of the groundwater an the arsenic content in different aquifers in Uruguay. The first data obtained of arsenic concentrations are from subterranes water in the Mercedes aquifers

  17. National Sole Source Aquifer GIS Layer

    Data.gov (United States)

    U.S. Environmental Protection Agency — This data set contains indexes and Esri shape files of boundaries of the designated sole source aquifers and related aquifer boundaries. Data provide a vector...

  18. Saturated thickness, High Plains aquifer, 2009

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This raster data set represents the saturated thickness of the High Plains aquifer of the United States, 2009, in feet. The High Plains aquifer underlies...

  19. Investigating Late Cenozoic Mantle Dynamics beneath Yellowstone

    Science.gov (United States)

    Zhou, Q.; Liu, L.

    2015-12-01

    Recent tomography models (Sigloch, 2011; Schmandt & Lin, 2014) reveal unprecedented details of the mantle structure beneath the United States (U.S.). Prominent slow seismic anomalies below Yellowstone, traditionally interpreted as due to a mantle plume, are restricted to depths either shallower than 200 km or between 500 and 1000 km, but a continuation to greater depth is missing. Compared to fast seismic anomalies, which are usually interpreted as slabs or delaminated lithosphere, origin of deep slow seismic anomalies, especially those in the vicinity of subduction zones, is more enigmatic. As a consequence, both the dynamics and evolution of these slow anomalies remain poorly understood. To investigate the origin and evolution of the Yellowstone slow anomaly during the past 20 Myr, we construct a 4D inverse mantle convection model with a hybrid data assimilation scheme. On the one hand, we use the adjoint method to recover the past evolution of mantle seismic structures beyond the subduction zones. On the other hand, we use a high-resolution forward model to simulate the subduction of the oceanic (i.e., Farallon) plate. During the adjoint iterations, features from these two approaches are blended together at a depth of ~200 km below the subduction zone. In practice, we convert fast and slow seismic anomalies to effective positive and negative density heterogeneities. Our preliminary results indicate that at 20 Ma, the present-day shallow slow anomalies beneath the western U.S. were located inside the oceanic asthenosphere, which subsequently entered the mantle wedge, through the segmented Farallon slab. The eastward encroachment of the slow anomaly largely followed the Yellowstone hotspot track migration. The present deep mantle Yellowstone slow anomaly originated at shallower depths (i.e. transition zone), and was then translated down to the lower mantle accompanying the sinking fast anomalies. The temporal evolution of the slow anomalies suggests that the deep

  20. Relationship of regional water quality to aquifer thermal energy storage

    International Nuclear Information System (INIS)

    Aquifer thermal energy storage (ATES) involves injection and withdrawal of temperature-conditioned water into and from a permeable water-bearing formation. The groundwater quality and associated geological characteristics were assessed as they may affect the feasibility of ATES system development in any hydrologic region. Seven physical and chemical mechanisms may decrease system efficiency: particulate plugging, chemical precipitation, clay mineral dispersion, piping corrosion, aquifer disaggregation, mineral oxidation, and the proliferation of biota. Factors affecting groundwater quality are pressure, temperature, pH, ion exchange, evaporation/transpiration, and commingling with diverse waters. Modeling with the MINTEQ code showed three potential reactions: precipitation of calcium carbonate at raised temperatures; solution of silica at raised temperature followed by precipitation at reduced temperatures; and oxidation/precipitation of iron compounds. Low concentrations of solutes are generally favorable for ATES. Near-surface waters in high precipitation regions are low in salinity. Groundwater recharged from fresh surface waters also has reduced salinity. Rocks least likely to react with groundwater are siliceous sandstones, regoliths, and metamorphic rocks. On the basis of known aquifer hydrology, ten US water resource regions are candidates for selected exploration and development, all characterized by extensive silica-rich aquifers

  1. Spatial organization of the impulse response in a karst aquifer

    Science.gov (United States)

    Delbart, C.; Valdés, D.; Barbecot, F.; Tognelli, A.; Couchoux, L.

    2016-06-01

    Karst aquifers are characterized by a strong heterogeneity in their physical properties. The purpose of the study is the spatial variability of water transfers in a carbonated karstic aquifer. To this end, a high spatial density of information about the water transfer is needed. The characteristics of the site, a topographic hill of 13 km2 with eight boreholes, which was monitored hourly over four years, allows the study of the spatial variability of water transfers. The variability of the impulse response of the system is studied using autocorrelation and cross-correlation analysis between the rainfall and piezometric level time series. The shapes of the autocorrelation and cross-correlation functions vary according to the geographical location of the boreholes, that proves a spatial organization of the groundwater transfer. The response time varies depending on the thickness of the unsaturated zone by an unusual inverse correlation. In this case, the water level signal spatially integrates the signal transfer of the unsaturated zone and the signal transfer of the saturated part of the aquifer. Consequently, inertia and response time increased with the distance between the borehole and the top of piezometric dome. This description supports highly organized fast transfers in this karst aquifer and a highly connected fracture network.

  2. Best practice for the storage of CO2 in saline aquifers - observations and guidelines from the SACS and CO2STORE projects

    OpenAIRE

    Chadwick, Andy; Arts, Rob; Bernstone, Christian; May, Franz; Thibeau, Sylvain; Zweigel, Peter

    2008-01-01

    Carbon capture and storage is a subject around which there is a growing level of public awareness. A range of geological scenarios may be used for underground CO2 storage; declining oil and gas fields, saline aquifers and coal seams. Saline aquifers are reckoned to offer the largest overall storage potential and the this book offers key insights into aquifer storage issues. European collaborative projects between 1998 and 2006 have researched the potential for large-scale storage of CO2 ...

  3. Turbulence beneath finite amplitude water waves

    Energy Technology Data Exchange (ETDEWEB)

    Beya, J.F. [Universidad de Valparaiso, Escuela de Ingenieria Civil Oceanica, Facultad de Ingenieria, Valparaiso (Chile); The University of New South Wales, Water Research Laboratory, School of Civil and Environmental Engineering, Sydney, NSW (Australia); Peirson, W.L. [The University of New South Wales, Water Research Laboratory, School of Civil and Environmental Engineering, Sydney, NSW (Australia); Banner, M.L. [The University of New South Wales, School of Mathematics and Statistics, Sydney, NSW (Australia)

    2012-05-15

    Babanin and Haus (J Phys Oceanogr 39:2675-2679, 2009) recently presented evidence of near-surface turbulence generated below steep non-breaking deep-water waves. They proposed a threshold wave parameter a {sup 2}{omega}/{nu} = 3,000 for the spontaneous occurrence of turbulence beneath surface waves. This is in contrast to conventional understanding that irrotational wave theories provide a good approximation of non-wind-forced wave behaviour as validated by classical experiments. Many laboratory wave experiments were carried out in the early 1960s (e.g. Wiegel 1964). In those experiments, no evidence of turbulence was reported, and steep waves behaved as predicted by the high-order irrotational wave theories within the accuracy of the theories and experimental techniques at the time. This contribution describes flow visualisation experiments for steep non-breaking waves using conventional dye techniques in the wave boundary layer extending above the wave trough level. The measurements showed no evidence of turbulent mixing up to a value of a {sup 2}{omega}/{nu} = 7,000 at which breaking commenced in these experiments. These present findings are in accord with the conventional understandings of wave behaviour. (orig.)

  4. Channelization of plumes beneath ice shelves

    KAUST Repository

    Dallaston, M. C.

    2015-11-11

    © 2015 Cambridge University Press. We study a simplified model of ice-ocean interaction beneath a floating ice shelf, and investigate the possibility for channels to form in the ice shelf base due to spatial variations in conditions at the grounding line. The model combines an extensional thin-film description of viscous ice flow in the shelf, with melting at its base driven by a turbulent ocean plume. Small transverse perturbations to the one-dimensional steady state are considered, driven either by ice thickness or subglacial discharge variations across the grounding line. Either forcing leads to the growth of channels downstream, with melting driven by locally enhanced ocean velocities, and thus heat transfer. Narrow channels are smoothed out due to turbulent mixing in the ocean plume, leading to a preferred wavelength for channel growth. In the absence of perturbations at the grounding line, linear stability analysis suggests that the one-dimensional state is stable to initial perturbations, chiefly due to the background ice advection.

  5. Chemical controls on abiotic and biotic release of geogenic arsenic from Pleistocene aquifer sediments to groundwater.

    Science.gov (United States)

    Gillispie, Elizabeth C; Andujar, Erika; Polizzotto, Matthew L

    2016-08-10

    Over 150 million people in South and Southeast Asia consume unsafe drinking water from arsenic-rich Holocene aquifers. Although use of As-free water from Pleistocene aquifers is a potential mitigation strategy, such aquifers are vulnerable to geogenic As pollution, placing millions more people at potential risk. The goal of this research was to define chemical controls on abiotic and biotic release of geogenic As to groundwater. Batch incubations of sediments with natural chemical variability from a Pleistocene aquifer in Cambodia were conducted to evaluate how interactions among arsenic, manganese and iron oxides, and dissolved and sedimentary organic carbon influenced As mobilization from sediments. The addition of labile dissolved organic carbon produced the highest concentrations of dissolved As after >7 months, as compared to sediment samples incubated with sodium azide or without added carbon, and the extent of As release was positively correlated with the percent of initial extractable Mn released from the sediments. The mode of As release was impacted by the source of DOC supplied to the sediments, with biological processes responsible for 81% to 85% of the total As release following incubations with lactate and acetate but only up to 43% to 61% of the total As release following incubations with humic and fulvic acids. Overall, cycling of key redox-active elements and organic-carbon reactivity govern the potential for geogenic As release to groundwater, and results here may be used to formulate better predictions of the arsenic pollution potential of aquifers in South and Southeast Asia. PMID:27463026

  6. The groundwater age in the Middle-Upper Devonian aquifer system, Lithuania

    Science.gov (United States)

    Mokrik, R.; Mažeika, J.; Baublytė, A.; Martma, T.

    2009-06-01

    3H, δ13C and hydrochemical data were used to estimate the corrected groundwater age derived from conventional 14C age of dissolved inorganic carbon (DIC). The Middle-Upper Devonian aquifer system from the Baltic upland recharge area in eastern Lithuania towards the discharge area on the Baltic Sea coast in the west was considered. The concentration of total dissolved solids (TDS) in groundwater changes from 300 to 24,000 mg/L and increases downgradient towards the coast. The other major constituents have the same trend as the TDS. The hydrochemical facies of groundwater vary from an alkali-earth carbonates facies at the eastern upland area to an alkali-earth carbonate-sulfate and chloride facies at transit and discharge areas. Meteoric water percolating through the Quaternary and Devonian aquifers regulate the initial 14C activities of groundwater involving two main members of DIC: soil CO2 with modern 14C activity uptake and dissolution of 14C-free aquifer carbonates. Other sources of DIC are less common. 14C activity of DIC in the groundwater ranged from 60 to 108 pMC at the shallow depths. With an increase of the aquifers depth the dolomitization of aqueous solution and leakage of the “old” groundwater from lower aquifers take place, traced by lower activities (7-30 pMC).

  7. Landfill leachate effects on sorption of organic micropollutants onto aquifer materials

    DEFF Research Database (Denmark)

    Larsen, Thomas; Christensen, Thomas Højlund; Pfeffer, Fred M.;

    1992-01-01

    The effect of dissolved organic carbon as present in landfill leachate, on the sorption of organic micropollutants in aquifer materials was studied by laboratory batch and column experiments involving 15 non-polar organic chemicals, 5 landfill leachates and 4 aquifer materials of low organic carbon...... content. The experiments showed that hydrophobic organic micropollutants do partition into dissolved organic carbon found in landfill leachate potentially increasing their mobility. However, landfill leachate interacted with aquifer materials apparently increases the sorbent affinity for the hydrophobic...... micropollutants. The combination of these two mechanisms affected the observed distribution coefficients within a factor of two, in some cases increasing and in other cases decreasing the sorption of the chemicals. No means for prediction of the effect is currently available, but from a practical point of view...

  8. Spatial variation in microbial community structure, richness, and diversity in an alluvial aquifer.

    Science.gov (United States)

    Medihala, P G; Lawrence, J R; Swerhone, G D W; Korber, D R

    2012-09-01

    Relatively little is known regarding the spatial variability of microbial communities in aquifers where well fouling is an issue. In this study 2 water wells were installed in an alluvial aquifer located adjacent to the North Saskatchewan River and an associated piezometer network developed to facilitate the study of microbial community structure, richness, and diversity. Carbon utilization data analysis revealed reduced microbial activity in waters collected close to the wells. Functional PCR and quantitative PCR analysis indicated spatial variability in the potential for iron-, sulphate-, and nitrate-reducing activity at all locations in the aquifer. Denaturing gradient gel electrophoresis analysis of aquifer water samples using principal components analyses indicated that the microbial community composition was spatially variable, and denaturing gradient gel electrophoresis sequence analysis revealed that bacteria belonging to the genera Acidovorax , Rhodobacter , and Sulfuricurvum were common throughout the aquifer. Shannon's richness (H') and Pielou's evenness (J') indices revealed a varied microbial diversity (H' = 1.488-2.274) and an even distribution of microbial communities within the aquifer (J' = 0.811-0.917). Overall, these analyses revealed that the aquifer's microbial community varied spatially in terms of composition, richness, and metabolic activity. Such information may facilitate the diagnosis, prevention, and management of fouling. PMID:22913282

  9. Aquifer recharge and contamination determination using environmental isotopes: Santiago basin, Chile: A study case

    International Nuclear Information System (INIS)

    Progressive water level descends and nitrate and sulfate contamination have been recorded in Santiago Nor te aquifer since the last decade. This aquifer is almost completely covered by Santiago City which uses groundwater for drinking water, industrial, and commercial uses. Due to the semi-arid conditions of the area and the constant drought periods, groundwater constitutes an extremely important water resource. The accelerated urban growth of Santiago City over the past 30 years has produced impacts on the hydrological cycle and in the degradation of water quality. The impact may be related to the proportion and quality of groundwater recharge induced by urban activities. The study addresses the impact in quality and quantity that urban recharge has in the aquifer beneath the city. In terms of water management, the evaluation of the urban recharge with respect to natural recharge and the determination of the sources of contamination were the main goals of the study. The main results show that the most important natural recharge is associated to the coarse grain facies of the alluvial fan apex of Mapocho River and the local watersheds. The isotopic data shows a minor recharge from direct precipitation over the city. Toward the central sector of the study area, where the oldest part of the city is located and where highly permeable sandy gravel facies over an unconfined aquifer are present, an important source of recharge related to leakage from the drinking water and sewage systems was identified These leaking systems are mainly fed by imported water from another watershed located south of the study area. The distinctive chemical and isotopic signature of this source allows the evaluation of its impact in this area. The remediation of the aquifer will require the reduction of leakages of the water and sewage distribution systems. However, this solution may strongly affect the water balance in the aquifer. (author)

  10. A quantitative analysis of hydraulic interaction processes in stream-aquifer systems

    Science.gov (United States)

    Wang, Wenke; Dai, Zhenxue; Zhao, Yaqian; Li, Junting; Duan, Lei; Wang, Zhoufeng; Zhu, Lin

    2016-01-01

    The hydraulic relationship between the stream and aquifer can be altered from hydraulic connection to disconnection when the pumping rate exceeds the maximum seepage flux of the streambed. This study proposes to quantitatively analyze the physical processes of stream-aquifer systems from connection to disconnection. A free water table equation is adopted to clarify under what conditions a stream starts to separate hydraulically from an aquifer. Both the theoretical analysis and laboratory tests have demonstrated that the hydraulic connectedness of the stream-aquifer system can reach a critical disconnection state when the horizontal hydraulic gradient at the free water surface is equal to zero and the vertical is equal to 1. A boundary-value problem for movement of the critical point of disconnection is established for an analytical solution of the inverted water table movement beneath the stream. The result indicates that the maximum distance or thickness of the inverted water table is equal to the water depth in the stream, and at a steady state of disconnection, the maximum hydraulic gradient at the streambed center is 2. This study helps us to understand the hydraulic phenomena of water flow near streams and accurately assess surface water and groundwater resources.

  11. Monitoring technologies for the evaluation of a Soil-Aquifer-Treatment system in coastal aquifer environments.

    Science.gov (United States)

    Kallioras, Andreas; Tsertou, Athanasia; Foglia, Laura; Bumberger, Jan; Vienken, Thomas; Dietrich, Peter; Schüth, Christoph

    2014-05-01

    Artificial recharge of groundwater has an important role to play in water reuse. Treated sewage effluent can be infiltrated into the ground for recharge of aquifers. As the effluent water moves through the soil and the aquifer, it undergoes significant quality improvements through physical, chemical, and biological processes in the underground environment. Collectively, these processes and the water quality improvement obtained are called soil-aquifer-treatment (SAT) or geopurification. Recharge systems for SAT can be designed as infiltration-recovery systems, where all effluent water is recovered as such from the aquifer, or after blending with native groundwater. SAT typically removes essentially all suspended solids, biochemical oxygen demand (BOD), and pathogens (viruses, bacteria, protozoa, and helminthic eggs). Concentrations of synthetic organic carbon, phosphorous, and heavy metals are greatly reduced. The pilot site of LTCP will involve the employment of infiltration basins, which will be using waters of impaired quality as a recharge source, and hence acting as a Soil-Aquifer-Treatment, SAT, system. T he LTCP site will be employed as a pilot SAT system complemented by new technological developments, which will be providing continuous monitoring of the quantitative and qualitative characteristics of infiltrating groundwater through all hydrologic zones (i.e. surface, unsaturated and saturated zone). This will be achieved through the development and installation of an integrated system of prototype sensors, installed on-site, and offering a continuous evaluation of the performance of the SAT system. An integrated approach of the performance evaluation of any operating SAT system should aim at parallel monitoring of all hydrologic zones, proving the sustainability of all involved water quality treatment processes within unsaturated and saturated zone. Hence a prototype system of Time Domain Reflectometry (TDR) sensors will be developed, in order to achieve

  12. Groundwater Mounding Beneath Stormwater Infiltration Basins

    Science.gov (United States)

    Nimmer, M.; Thompson, A. M.; Misra, D.

    2007-12-01

    An accurate understanding of groundwater mound formation is important in the proper design of stormwater infiltration basins since these basins are often required to recharge a portion of pre-development infiltration volume. Mound formation due to localized recharge may reduce the infiltration rate of the basin and the ability of the soil to filter pollutants. The goal of this research was to understand groundwater mounding and the potential for contaminant transport resulting from recharge beneath stormwater infiltration basins. A 0.10 ha infiltration basin serving a 9.4 ha residential subdivision in Oconomowoc, Wisconsin was used in this study. Subsurface conditions included sand and gravel material and a groundwater table at 2.3 m below grade. Three storm events, 4.9 cm, 2.8 cm, and 4.3 cm, between August 2006 and April 2007 were modeled using the two-dimensional numerical model HYDRUS. The calibrated model was used to evaluate hypothetical basin operation scenarios for various basin sizes, soil types, ponding depths, and water table depths. The groundwater mound intersected the basin floor in most scenarios with loamy sand and sandy loam soils, an unsaturated thickness of 1.52 m, and a ponding depth of 0.61 m. No groundwater table response was observed with ponding depths less than 0.31 m with an unsaturated zone thickness of 6.09 m. The mound height was most sensitive to hydraulic conductivity and unsaturated zone thickness. A 7.6 cm sediment layer delayed the time to reach maximum mound height, but had a minimal effect on the magnitude of the mound. Mound heights increased as infiltration basin size increased.

  13. Active Subduction Beneath The Gibraltar Arc

    Science.gov (United States)

    Gutscher, M.-A.; Malod, J.; Rehault, J.-P.; Contrucci, I.; Klingelhoefer, F.; Spakman, W.; Sismar Scientific Team

    The Gibraltar region features the arcuate Betic - Rif mountain belt with outward di- rected thrusting, surrounding a zone of strong Neogene subsidence and crustal thin- ning in the Western Alboran Sea. Until now its geodynamic interpretation has re- mained controversial. The Gibraltar Arc is located at the eastern end of the Azores- Gibraltar transform, a diffuse transpressional plate boundary between the Iberian and African Plates. Attention has recently been focussed on this plate boundary, while seeking the likely source of the destructive Lisbon great earthquake (M 8.5 - 9) and tsunami of 1755. The SISMAR marine seismic survey conducted in April 2001 ac- quired over 3000 km of 360-channel seismic data with a 4.5 km long streamer and 1000 km of wide-angle data recorded by ocean bottom seismometers (OBS), com- pletely spanning the actively deforming region between the margins of Portugal and northwest Morocco. Results from this seismic survey reveal a thick chaotic sedimen- tary mass west of Gibraltar to be an actively deforming accretionary wedge, with east dipping thrust faults disrupting the seafloor and soleing out to an east dipping decolle- ment. New travel-time tomographic results image a continuous east dipping body with high seismic velocities (i.e. a cold slab of oceanic lithosphere) descending from the Atlantic domain of the Gulf of Cadiz, passing through intermediate depth (60 - 120 km) seismicity beneath the Gibraltar Arc and Western Alboran Sea, and merging with a region of deep focus earthquakes 600 - 660 km below Granada Spain. Together these provide compelling evidence for an active east dipping subduction zone. Slab rollback towards the west provides a plausible mechanism for extension and subsidence in the Alboran Sea, while the associated westward advance of the Gibraltar Arc drives com- pressional deformation in the accretionary wedge where active mud volcanoes have recently been discovered.

  14. Assessing the vulnerability of public-supply wells to contamination: Rio Grande aquifer system in Albuquerque, New Mexico

    Science.gov (United States)

    Jagucki, Martha L.; Bexfield, Laura M.; Heywood, Charles E.; Eberts, Sandra M.

    2012-01-01

    This fact sheet highlights findings from the vulnerability study of a public-supply well in Albuquerque, New Mexico (hereafter referred to as “the study well”). The study well produces about 3,000 gallons of water per minute from the Rio Grande aquifer system. Water samples were collected at the study well, at two other nearby public-supply wells, and at monitoring wells installed in or near the simulated zone of contribution to the study well. Untreated water samples from the study well contained arsenic at concentrations exceeding the Maximum Contaminant Level (MCL) of 10 micrograms per liter (µg/L) established by the U.S. Environmental Protection Agency for drinking water. Volatile organic compounds (VOCs) and nitrate also were detected, although at concentrations at least an order of magnitude less than established drinking-water standards, where such standards exist. Overall, study findings point to four primary influences on the movement and (or) fate of contaminants and the vulnerability of the public-supply well in Albuquerque: (1) groundwater age (how long ago water entered, or recharged, the aquifer), (2) groundwater development (introduction of manmade recharge and discharge sources), (3) natural geochemical conditions of the aquifer, and (4) seasonal pumping stresses. Concentrations of the isotope carbon-14 indicate that groundwater from most sampled wells in the local study area is predominantly water that entered, or recharged, the aquifer more than 6,000 years ago. However, the additional presence of the age tracer tritium in several groundwater samples at concentrations above 0.3 tritium units indicates that young (post-1950) recharge is reaching the aquifer across broad areas beneath Albuquerque. This young recharge is mixing with the thousands-of-years-old water, is migrating to depths as great as 245 feet below the water table, and is traveling to some (but not all) of the public-supply wells sampled. Most groundwater samples containing a

  15. Isotope contribution to geochemical investigations in aquifer storage and recovery

    International Nuclear Information System (INIS)

    Aquifer Storage and Recovery (ASR) is an important resource management tool. An available water source; such as surface water, seasonal rainfall, or sewage effluent, is stored in a suitable aquifer for reuse when required to balance the seasonal demand for irrigation supply, thus relieving the pressure on groundwater resources. In ASR schemes, geochemical and biogeochemical reactions play an important role, impacting on both the aquifer matrix integrity and the recovered water quality. Understanding the driving processes that trigger these reactions is essential for determing the feasibility of new schemes and to adequately manage operating schemes. However the resulting geochemical signature is often due to a complex suite of reactions that is difficult to unravel. Few studies analyse the potential of isotopic tracers to contribute to the understanding of the biogeochemical reactions induced by ASR. This paper investigates the potential of the stable isotopes of the water molecule, carbon-13 and carbon-14 and sulfur-34 to contribute to our understanding of the geochemical processes involved in reclaimed water ASR. The field trial at Bolivar, South Australia is investigating the viability of reclaimed water i.e. nutrient rich water, as an injectant

  16. Aquifer Characteristics Data Report for the Weldon Spring Site chemical plant/raffinate pits and vicinity properties for the Weldon Spring Site Remedial Action Project, Weldon Spring, Missouri

    Energy Technology Data Exchange (ETDEWEB)

    1990-11-01

    This report describes the procedures and methods used, and presents the results of physical testing performed, to characterize the hydraulic properties of the shallow Mississippian-Devonian aquifer beneath the Weldon Spring chemical plant, raffinate pits, and vicinity properties. The aquifer of concern is composed of saturated rocks of the Burlington-Keokuk Limestone which constitutes the upper portion of the Mississippian-Devonian aquifer. This aquifer is a heterogeneous anisotropic medium which can be described in terms of diffuse Darcian flow overlain by high porosity discrete flow zones and conduits. Average hydraulic conductivity for all wells tested is 9.6E-02 meters/day (3.1E-01 feet/day). High hydraulic conductivity values are representative of discrete flow in the fractured and weathered zones in the upper Burlington-Keokuk Limestone. They indicate heterogeneities within the Mississippian-Devonian aquifer. Aquifer heterogeneity in the horizontal plane is believed to be randomly distributed and is a function of fracture spacing, solution voids, and preglacial weathering phenomena. Relatively high hydraulic conductivities in deeper portions of the aquifer are though to be due to the presence of widely spaced fractures. 44 refs., 27 figs., 9 tabs.

  17. Aquifer Characteristics Data Report for the Weldon Spring Site chemical plant/raffinate pits and vicinity properties for the Weldon Spring Site Remedial Action Project, Weldon Spring, Missouri

    International Nuclear Information System (INIS)

    This report describes the procedures and methods used, and presents the results of physical testing performed, to characterize the hydraulic properties of the shallow Mississippian-Devonian aquifer beneath the Weldon Spring chemical plant, raffinate pits, and vicinity properties. The aquifer of concern is composed of saturated rocks of the Burlington-Keokuk Limestone which constitutes the upper portion of the Mississippian-Devonian aquifer. This aquifer is a heterogeneous anisotropic medium which can be described in terms of diffuse Darcian flow overlain by high porosity discrete flow zones and conduits. Average hydraulic conductivity for all wells tested is 9.6E-02 meters/day (3.1E-01 feet/day). High hydraulic conductivity values are representative of discrete flow in the fractured and weathered zones in the upper Burlington-Keokuk Limestone. They indicate heterogeneities within the Mississippian-Devonian aquifer. Aquifer heterogeneity in the horizontal plane is believed to be randomly distributed and is a function of fracture spacing, solution voids, and preglacial weathering phenomena. Relatively high hydraulic conductivities in deeper portions of the aquifer are though to be due to the presence of widely spaced fractures. 44 refs., 27 figs., 9 tabs

  18. Aquifer thermal energy stores in Germany

    International Nuclear Information System (INIS)

    This paper describes the state of essential demonstration projects of heat and cold storage in aquifers in Germany. Into the energy supply system of the buildings of the German Parliament in Berlin, there are integrated both a deep brine-bearing aquifer for the seasonal storage of waste heat from power and heat cogeneration and a shallow-freshwater bearing aquifer for cold storage. In Neubrandenburg, a geothermal heating plant which uses a 1.200 m deep aquifer is being retrofitted into an aquifer heat storage system which can be charged with the waste heat from a gas and steam cogeneration plant. The first centralised solar heating plant including an aquifer thermal energy store in Germany was constructed in Rostock. Solar collectors with a total area of 1000m2 serve for the heating of a complex of buildings with 108 flats. A shallow freshwater-bearing aquifer is used for thermal energy storage. (Authors)

  19. Foundering lithosphere imaged beneath the southern Sierra Nevada, California, USA.

    Science.gov (United States)

    Boyd, Oliver S; Jones, Craig H; Sheehan, Anne F

    2004-07-30

    Seismic tomography reveals garnet-rich crust and mantle lithosphere descending into the upper mantle beneath the southeastern Sierra Nevada. The descending lithosphere consists of two layers: an iron-rich eclogite above a magnesium-rich garnet peridotite. These results place descending eclogite above and east of high P wave speed material previously imaged beneath the southern Great Valley, suggesting a previously unsuspected coherence in the lithospheric removal process. PMID:15286370

  20. Biological transformation of phenols in a sandstone aquifer

    DEFF Research Database (Denmark)

    Broholm, M.; Arvin, E.

    1997-01-01

    Ammonia liquor with very high concentrations of phenols is known to have leaked into the subsurface at a former coal carbonization plant in the UK. High concentrations of ammonium has been encountered in the groundwater reservoir at the site. In spite of this no significant concentrations of...... phenols are found in the groundwater. In this study the potential for transformation of the phenols in the sandstone aquifer at the site under aerobic, nitrate enriched and ''unaltered'' (limited nitrate available, ironoxides and sulphate available) is investigated in laboratory microcosms. Preliminary...... results reveal complete transformation of phenol, cresols and 3,4-xylenol under all 3 conditions and of 2,5-xylenol under aerobic conditions and 3,5-xylenol under anoxic conditions. The potential for natural attenuation of the phenols in this aquifer appear very promising....

  1. Basin-scale conceptual groundwater flow model for an unconfined and confined thick carbonate region

    Science.gov (United States)

    Mádl-Szőnyi, Judit; Tóth, Ádám

    2015-11-01

    Application of the gravity-driven regional groundwater flow (GDRGF) concept to the hydrogeologically complex thick carbonate system of the Transdanubian Range (TR), Hungary, is justified based on the principle of hydraulic continuity. The GDRGF concept informs about basin hydraulics and groundwater as a geologic agent. It became obvious that the effect of heterogeneity and anisotropy on the flow pattern could be derived from hydraulic reactions of the aquifer system. The topography and heat as driving forces were examined by numerical simulations of flow and heat transport. Evaluation of groups of springs, in terms of related discharge phenomena and regional chloride distribution, reveals the dominance of topography-driven flow when considering flow and related chemical and temperature patterns. Moreover, heat accumulation beneath the confined part of the system also influences these patterns. The presence of cold, lukewarm and thermal springs and related wetlands, creeks, mineral precipitates, and epigenic and hypogenic caves validates the existence of GDRGF in the system. Vice versa, groups of springs reflect rock-water interaction and advective heat transport and inform about basin hydraulics. Based on these findings, a generalized conceptual GDRGF model is proposed for an unconfined and confined carbonate region. An interface was revealed close to the margin of the unconfined and confined carbonates, determined by the GDRGF and freshwater and basinal fluids involved. The application of this model provides a background to interpret manifestations of flowing groundwater in thick carbonates generally, including porosity enlargement and hydrocarbon and heat accumulation.

  2. Environmental isotope and hydrochemical investigation on groundwater recharge and dynamics of the coastal sedimentary aquifers of Tiruvadanai, Tamilnadu State, India

    International Nuclear Information System (INIS)

    Recharge processes and dynamics of the Tiruvadanai aquifers were investigated using environmental isotopes and hydro-chemistry, in conjunction with hydrogeological data. Hydro-chemical characterization of the groundwaters indicated that the shallow (2+ and Ca2+ and an increase in Na+ and K+ in both the aquifers. This could be attributed to ion-exchange process. A higher pH value of Cretaceous aquifer samples (7.4-8.6) could also be responsible for the lowering of Mg2+ and Ca2+ concentrations by facilitating precipitation of carbonates in them. δ2H-δ18O plot of the Tertiary aquifer samples fall on an evaporation line. Its 3H values near the ephemeral rivers range from 2 to 5 TU while those away from the rivers have 14CDIC model ages range from 1 to 13 ka BP. The Cretaceous aquifer samples measured 3H values 14CDIC model ages are >20 ka BP, indicating palaeo-waters. Based on 14C model ages, the groundwater velocity was estimated (Tertiary aquifers: 10-2 - 10-3 m.d-1; Cretaceous aquifer: 10-3 m.d-1). The 13CDIC enrichment along the flowpath of Cretaceous aquifer was observed and that could be due to carbonate minerals dissolution. From the investigation, four types of recharge processes to the aquifer system are discerned, with the overall modern recharge component being low. The Cretaceous aquifer contains fossil groundwaters and hence the resources may be finite and their exploitation is mining. The suitable river for implementing large-scale artificial recharge measures was identified. (author)

  3. Isotope hydrological investigation in Thiruvanmiyur aquifer Chennai, Tamil Nadu

    International Nuclear Information System (INIS)

    Hydrosalinity evolution and interconnections between aquifers is examined in Thiruvanmiyur aquifer situated south of Chennai, Tamil Nadu. Different aquifer systems have been differentiated using environmental tritium, stable isotope (18O) and hydrological data. Results show that groundwater salinity is due to dissolution of aquifer material and possibility of aquifer interconnections is remote. (author)

  4. Pesticide sorption by low organic carbon sediments: A sceening for seven herbicides

    DEFF Research Database (Denmark)

    Madsen, Lene; Lindhardt, Bo; Rosenberg, Per;

    2000-01-01

    The sorption of seven pesticides in 10 Danish aquifer sediments has been studied. These sediments all have a total organic carbon (TOC) content below 1 g kg(-1), and include carbonate-bearing and carbonate-free Quatenary sand deposits and a Cretaceous chalk aquifer. Batch experiments were carried...

  5. Considerations in the extraction of uranium from a fresh-water aquifer - Miocene Oakville Sandstone, south Texas

    International Nuclear Information System (INIS)

    The Miocene Oakville Sandstone is a major aquifer and uranium host beneath the Texas Coastal Plain. Present and future uranium mining by either surface or in situ methods could affect the availability and quality of Oakville ground water unless the mining is designed properly. Possible effects of mining, potential natural mitigation of these effects, and approaches to minimizing the impact of mining on the aquifer system are discussed. Both solution and surface mining may affect the availability of ground water by altering recharge characteristics and permeability. Because the volume of the aquifer affected by mining is small compared with its total volume, availability of Oakville ground water will probably not be reduced significantly, except in wells immediately adjacent to a mine. Mining may affect the quality of ground water by introducing chemicals that are not indigenous to the aquifer or by inducing chemical reactions that do not occur naturally or that occur at much slower rates. Most mining companies no longer use concentrated, ammonium-based leaches because of known problems in restoring water to its original chemistry. Natural and induced release of trace elements such as molybdenum is known to occur, but the geochemical controls on mobility and potential mitigating reactions in the aquifer are poorly understood. Because the affected aquifer volume is small, any deterioration of water quality will probably be localized. Observations and recommendations are presented on: regional and local baseline studies, determination of aquifer sensitivity, methods and goals of monitoring during and after mining, and need for research on poorly understood aspects of mining impact. Such impacts include chemical reactions and processes that affect the long-term release of trace elements

  6. Digital data sets that describe aquifer characteristics of the Elk City aquifer in western Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized polygons of constant hydraulic conductivity values for the Elk City aquifer in western Oklahoma. The aquifer covers an area of...

  7. Digital data sets that describe aquifer characteristics of the Enid isolated terrace aquifer in northwestern Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized water-level elevation contours for the Enid isolated terrace aquifer in northwestern Oklahoma. The Enid isolated terrace aquifer...

  8. Digital data sets that describe aquifer characteristics of the Elk City aquifer in western Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized polygons of constant recharge values for the Elk City aquifer in western Oklahoma. The aquifer covers an area of approximately...

  9. Digital data sets that describe aquifer characteristics of the Elk City aquifer in western Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized water-level elevation contours for the Elk City aquifer in western Oklahoma. The aquifer covers an area of approximately 193,000...

  10. Digital data sets that describe aquifer characteristics of the Rush Springs aquifer in western Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized aquifer boundaries for the Rush Springs aquifer in western Oklahoma. This area encompasses all or part of Blaine, Caddo,...

  11. Digital data sets that describe aquifer characteristics of the Antlers aquifer in southeastern Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized aquifer boundaries of the Antlers aquifer in southeastern Oklahoma. The Early Cretaceous-age Antlers Sandstone is an important...

  12. Digital data sets that describe aquifer characteristics of the High Plains aquifer in western Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digital aquifer boundaries for the High Plains aquifer in western Oklahoma. This area encompasses the panhandle counties of Cimarron,...

  13. Hydrochemistry of New Zealand's aquifers

    International Nuclear Information System (INIS)

    Groundwater chemistry on a national scale has never been studied in New Zealand apart from a few studies on nitrate concentrations and pesticides. These studies are covered in Chapter 8 of this book. However general studies of groundwater chemistry, groundwater-rock interaction and regional characteristics of water quality have not been previously addressed in much detail. This is partly because New Zealand aquifers are relatively small on a world scale and are geologically and tectonically diverse (see Chapter 3). But New Zealand has also recently lacked a centralised agency responsible for groundwater quality, and therefore, no national assessments have been undertaken. In recent years, the Institute of Geological and Nuclear Sciences has managed a programme of collecting and analysing the groundwater chemistry of key New Zealand aquifers. This programme is called the National Groundwater Monitoring Programme (NGMP) and is funded by the New Zealand Public Good Science Fund. The programme started in 1990 using only 22 wells, with four regional authorities of the country participating. The NGMP now includes all 15 regional and unitary authorities that use groundwater and over 100 monitoring sites. The NGMP is considered a nationally significant database by the New Zealand Foundation for Research Science and Technology. The NGMP allows a national comparison of aquifer chemistries because the samples are all analysed at one laboratory in a consistent manner and undergo stringent quality control checks. Poor quality analyses are thus minimised. In addition, samples are collected quarterly so that long-term seasonal trends in water quality can be analysed, and the effects of changes in land use and the vulnerability of aquifers to contaminant leaching can be assessed. This chapter summarises the water quality data collected for the NGMP over the past 10 years. Some records are much shorter than others, but most are greater than three years. Additional information is

  14. Data to Accompany the Regional Potentiometric-Surface Map of the Great Basin Carbonate and Alluvial Aquifer System in Snake Valley and Surrounding Areas, Juab, Millard, and Beaver Counties, Utah and White Pine and Lincoln Counties, Nevada

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Water-level measurements from 190 wells were used to develop a potentiometric-surface map of the east-central portion of the regional Great Basin carbonate and...

  15. Data Intensive Simulation and Analysis of Groundwater Flow and Transport in the Los Alamos aquifer

    Science.gov (United States)

    Mishra, P. K.; Harp, D.; Miller, T. A.; Vesselinov, V. V.

    2011-12-01

    Characterization of the groundwater flow and transport in regional aquifer systems is a challenging task. In most practical cases, there is not sufficient hydrogeologic information that can be applied to evaluate aquifer properties. In addition, the development, execution and analyses of large-scale numerical models are computational demanding requiring advanced high-performance codes and state-of-the-art computational resources. We have developed a complex 3D regional groundwater flow model of the regional aquifer beneath the Los Alamos National Laboratory (LANL) site to provide a better understanding of hydrogeologic properties, recharge sources, groundwater travel times, migration pathways for potential contaminants, and potential contaminant concentrations at water supply wells. The 3D computational grid is generated using sophisticated grid generating software, LaGriT (http://lagrit.lanl.gov). LaGriT allows the use of unstructured meshing strategies, which capture the details of complex groundwater flow of the LANL site, including wellbore geometries and hydrostratigraphy. The numerical simulation is performed using the FEHM (Finite Element Heat and Mass transfer) (http://fehm.lanl.gov) codes. Long-term groundwater level monitoring at LANL started in the mid-1940s; the monitoring data is currently collected at more than 70 regional monitoring wells providing an extensive water-level observation data set. The water-level data represent over 62 years of recorded drawdowns and recovery caused by the spatially and temporally variable pumping at six municipal water-supply wells. The water-level data is applied in the 3D flow model to inversely estimate the aquifer parameters. The model calibration, uncertainty quantification, and sensitivity analyses are performed using the code MADS (Model Analyses and Decision Support; http://ees.lanl.gov/staff/monty/codes/mads). The research utilizes high performance computational resources (multiprocessor clusters) at LANL. In

  16. Bacterial migration through low-permeability fault zones in compartmentalised aquifer systems: a case study in Southern Italy

    OpenAIRE

    Antonio Bucci; Emma Petrella; Gino Naclerio; Sabrina Gambatese; Fulvio Celico

    2014-01-01

    The aim of this study was to experimentally verify the significance of microbial transport through low-permeability fault zones in a compartmentalised carbonate aquifer system in Southern Italy. The temporal variability of microbial communities in two springs fed by the same aquifer system, but discharging up- and down-gradient of two low-permeability fault zones, was analysed using a 16S rDNA polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE)-based approach. At b...

  17. Heat storage in the Hettangian aquifer in Berlin - results from a column experiment

    Science.gov (United States)

    Milkus, Chri(Sch)augott

    2015-04-01

    Aquifer Thermal Energy Storage (ATES) is a sustainable alternative for storage and seasonal availability of thermal energy. However, its impact on the subsurface flow regime is not well known. In Berlin (Germany), the Jurassic (Hettangian) sandstone aquifer with highly mineralized groundwater (TDS 27 g/L) is currently used for heat storage. The aim of this study was to examine the hydrogeochemical changes that are caused by the induced temperature shift and its effects on the hydraulic permeability of the aquifer. Column experiments were conducted, in which stainless steel columns were filled with sediment from the aquifer and flushed with native groundwater for several weeks. The initial temperature of the experiment was 20°C, comparable to the in-situ conditions within the aquifer. After reaching equilibrium between sediment and water, the temperature was increased to simulate heating of the aquifer. During the experiment, physical and chemical parameters (pH, ORP, dissolved oxygen and dissolved carbon dioxide) were measured at the outflow of the column and the effluent water was sampled. Using a Scanning Electron Microscope, the deposition of precipitated minerals and biofilm on sediment grains was analyzed. Changes in hydraulic properties of the sediment were studied by the use of tracer tests with Uranin.

  18. 3-D time-lapse electrical resistivity monitoring of injected CO2 in a shallow aquifer

    DEFF Research Database (Denmark)

    Doetsch, Joseph A. J.A.; Auken, Esben; Christiansen, Anders Vest C A.V.C.; Fiandaca, Gianluca G.

    Contamination of potable groundwater by leaking CO2 is a potential risk of carbon sequestration. With the help of a field experiment, we investigate if surface electrical resistivity tomography (ERT) can detect dissolved CO2 in a shallow aquifer. For this purpose, we injected CO2 at a depth of 5 ...

  19. Viruses and Bacteria in Karst and Fractured Rock Aquifers in East Tennessee, USA

    Science.gov (United States)

    A survey of enteric viruses and indicator bacteria was carried out in eight community water supply sources (four wells and four springs) in east Tennessee. Seven of the sites were in carbonate aquifers and the other was in fractured sandstone. Four sites (three wells and one sp...

  20. The University of Minnesota aquifer thermal energy storage (ATES) field test facility -- system description, aquifer characterization, and results of short-term test cycles

    Energy Technology Data Exchange (ETDEWEB)

    Walton, M.; Hoyer, M.C.; Eisenreich, S.J.; Holm, N.L.; Holm, T.R.; Kanivetsky, R.; Jirsa, M.A.; Lee, H.C.; Lauer, J.L.; Miller, R.T.; Norton, J.L.; Runke, H. (Minnesota Geological Survey, St. Paul, MN (United States))

    1991-06-01

    Phase 1 of the Aquifer Thermal Energy Storage (ATES) Project at the University of Minnesota was to test the feasibility, and model, the ATES concept at temperatures above 100{degrees}C using a confined aquifer for the storage and recovery of hot water. Phase 1 included design, construction, and operation of a 5-MW thermal input/output field test facility (FTF) for four short-term ATES cycles (8 days each of heat injection, storage, and heat recover). Phase 1 was conducted from May 1980 to December 1983. This report describes the FTF, the Franconia-Ironton-Galesville (FIG) aquifer used for the test, and the four short-term ATES cycles. Heat recovery; operational experience; and thermal, chemical, hydrologic, and geologic effects are all included. The FTF consists of monitoring wells and the source and storage well doublet completed in the FIG aquifer with heat exchangers and a fixed-bed precipitator between the wells of the doublet. The FIG aquifer is highly layered and a really anisotropic. The upper Franconia and Ironton-Galesville parts of the aquifer, those parts screened, have hydraulic conductivities of {approximately}0.6 and {approximately}1.0 m/d, respectively. Primary ions in the ambient ground water are calcium and magnesium bicarbonate. Ambient temperature FIG ground water is saturated with respect to calcium/magnesium bicarbonate. Heating the ground water caused most of the dissolved calcium to precipitate out as calcium carbonate in the heat exchanger and precipitator. Silica, calcium, and magnesium were significantly higher in recovered water than in injected water, suggesting dissolution of some constituents of the aquifer during the cycles. Further work on the ground water chemistry is required to understand water-rock interactions.

  1. Groundwater Remediation in a Floodplain Aquifer at Shiprock, New Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, Dave [Navarro Research and Engineering; Miller, David [Navarro Research and Engineering; Kautsky, Mark [U. S. Department of Energy, Office of Legacy Management; Dander, David [Navarro Research and Engineering; Nofchissey, Joni [Navajo Nation Division of Natural Resources

    2016-03-06

    A uranium- and vanadium-ore-processing mill operated from 1954 to 1968 within the Navajo Nation near Shiprock, New Mexico. By September 1986, all tailings and structures on the former mill property were encapsulated in a disposal cell built on top of two existing tailings piles on the Shiprock site (the site) [1]. Local groundwater was contaminated by multiple inorganic constituents as a result of the milling operations. The U.S. Department of Energy (DOE) took over management of the site in 1978 as part of the Uranium Mill Tailings Remedial Action (UMTRA) Project. The DOE Office of Legacy Management currently manages ongoing activities at the former mill facility, including groundwater remediation. Remediation activities are designed primarily to reduce the concentrations and total plume mass of the mill-related contaminants sulfate, uranium, and nitrate. In addition to contaminating groundwater in alluvial and bedrock sediments directly below the mill site, ore processing led to contamination of a nearby floodplain bordering the San Juan River. Groundwater in a shallow alluvial aquifer beneath the floodplain is strongly influenced by the morphology of the river channel as well as changing flows in the river, which provides drainage for regional runoff from the San Juan Mountains of Colorado. As part of a recent study of the floodplain hydrology, a revised conceptual model was developed for the alluvial aquifer along with an updated status of contaminant plumes that have been impacted by more than 10 years of groundwater pumping for site remediation purposes. Several findings from the recent study will be discussed here.

  2. Initiation of liquid-solid contact beneath an impacting drop

    Science.gov (United States)

    Rubinstein, Shmuel; Kolinski, John

    2015-11-01

    Before an impacting drop contacts the solid surface it must first drain the air beneath it. As a prelude to wetting, before any contact occurs, the impinging liquid confines the intervening air into a nanometers-thin film. Once liquid-solid contact initiates by the spontaneous formation of a liquid bridge, the fluid rapidly wicks through the thin film of air, permanently binding the drop to the surface. Here, we experimentally examine these initial stages in the formation of the liquid solid contact beneath the impacting drop. Fast TIR microscopy enables unprecedented spatial and temporal resolution of the wetting process beneath the impacting drop and permits 3-dimensional imaging of the real contact line as well as nanometer-resolution of the thin film of air separating the liquid from the solid.

  3. Mantle discontinuities beneath Izu-Bonin and the implications

    Institute of Scientific and Technical Information of China (English)

    臧绍先; 周元泽; 蒋志勇

    2003-01-01

    The SdP, pdP and sdP phases are picked up with the Nth root slant stack method from the digital waveform data recorded by the networks and arrays in USA, Germany and Switzerland for the earthquakes occurring beneath Izu-Bonin and Japan Sea. The mantle discontinuities and the effects of subducting slab on the 660 km and 410 km discontinuities are studied. It is found that there are mantle discontinuities existing at the depths of 170, 220, 300, 410, 660, 850 and 1150 km. Beneath Izu-Bonin, the 410 km discontinuity is elevated, while the 660 km discontinuity is depressed; for both discontinuities, there are regionalized differences. Beneath Japan Sea, however, there is no depth variation of the 410 km discontinuity, and the 660 km discontinuity is depressed without obvious effect of the subducting slab.

  4. Relationships between microbial community structure and hydrochemistry in a landfill leachate-polluted aquifer.

    Science.gov (United States)

    Röling, W F; van Breukelen, B M; Braster, M; Lin, B; van Verseveld, H W

    2001-10-01

    Knowledge about the relationship between microbial community structure and hydrogeochemistry (e.g., pollution, redox and degradation processes) in landfill leachate-polluted aquifers is required to develop tools for predicting and monitoring natural attenuation. In this study analyses of pollutant and redox chemistry were conducted in parallel with culture-independent profiling of microbial communities present in a well-defined aquifer (Banisveld, The Netherlands). Degradation of organic contaminants occurred under iron-reducing conditions in the plume of pollution, while upstream of the landfill and above the plume denitrification was the dominant redox process. Beneath the plume iron reduction occurred. Numerical comparison of 16S ribosomal DNA (rDNA)-based denaturing gradient gel electrophoresis (DGGE) profiles of Bacteria and Archaea in 29 groundwater samples revealed a clear difference between the microbial community structures inside and outside the contaminant plume. A similar relationship was not evident in sediment samples. DGGE data were supported by sequencing cloned 16S rDNA. Upstream of the landfill members of the beta subclass of the class Proteobacteria (beta-proteobacteria) dominated. This group was not encountered beneath the landfill, where gram-positive bacteria dominated. Further downstream the contribution of gram-positive bacteria to the clone library decreased, while the contribution of delta-proteobacteria strongly increased and beta-proteobacteria reappeared. The beta-proteobacteria (Acidovorax, Rhodoferax) differed considerably from those found upstream (Gallionella, Azoarcus). Direct comparisons of cloned 16S rDNA with bands in DGGE profiles revealed that the data from each analysis were comparable. A relationship was observed between the dominant redox processes and the bacteria identified. In the iron-reducing plume members of the family Geobacteraceae made a strong contribution to the microbial communities. Because the only known

  5. Reconstruction of the Friuli Venezia Giulia Plain aquifers

    Science.gov (United States)

    Calligaris, Chiara; Cimolino, Aurelie; Cucchi, Franco; Deana, Alberto; Treu, Francesco; Zini, Luca

    2010-05-01

    The constantly increasing of water demand for human consumptions has necessitated a reconstruction of the hydrogeologic characteristics and properties as well isotopic features of the aquifers of the Friuli Venezia Giulia Plain (FP). The DiSGAM and DICA have been engaged by the Hydraulic Survey of the FVG Region in order to coordinate an integrated study finalized to the FP confined and unconfined aquifer geometries reconstruction and to provide guide-lines for water rational exploitation (Agreement D.G.R. n. 1827 dd. 27.07.2007). The Friuli Venezia Giulia Plain, located in the northeastern sector of Italy, hosts well developed Plio-Quaternary unconfined and confined alluvial aquifers. The main surface drainage of the Plain is the Tagliamento River. The regional hydrogeological situation is characterized in the north by an extensive alluvial unconfined aquifer mostly contained in carbonate gravels. This area extends from the Pre-Alps to the resurgence belt. The resurgence belt is 2 to 8 km wide and 80 kilometres long. In this area the water table intersects the topographic surface forming numerous plain springs and rivers. The resurgence belt sets a geohydrological boundary between the Upper and Lower Friulian Plain. In this strip the unconfined aquifer changes into a multi-layered confined that reach a thickness of up to 500 m with a progressive increase in a westward direction towards the Adriatic Sea. In order to define underground aquifer relations and patterns, more than 1800 stratigraphic columns have been collected from different public departments water well database. Well logs have been georeferred, missing elevations calculated by regional DTM, possible correspondences controlled and datasets updated. In order to better correlate spatial data, an unique implemented lithostratigraphy legend has been created from present different ones; it is composed of: Lithological Entries (relating lithology and granulometric features; permeability linked different

  6. Use of environmental isotopes to characterize the groundwaters from tertiary aquifers of Kuttanad, Kerala, India

    International Nuclear Information System (INIS)

    Kuttanad area commonly known as the 'rice bowl' of Kerala is of importance as it contributes to the majority of rice production of the state. Even though more than 75% of the area is covered by surface waters and wetlands, groundwater is the only source of potable water supply to the nearby Alleppey town and the rural areas of Kuttanad because of contamination and inherent water quality problems in surface waters. Due to large-scale exploitation of groundwater resources for almost five decades, it is important to understand the sustainability of aquifers in this area in view of the increasing demand for domestic and irrigation requirements. Since the hydraulic gradient is mild and owing to the lowering of piezometric heads over the years, seawater ingression and deterioration of water quality in some parts of this coastal aquifer is apprehended. More over, the impact of agricultural pollution by the excessive use of fertilizers and pesticides need to be dealt with for the protection and mitigation of pollution in aquifers. As a pre-requisite to address the above problems, a systematic environmental isotope (oxygen 18, tritium, carbon 13 and carbon 14)) study is carried out to understand the flow pattern, source and process of replenishment and possible hydraulic interconnection between aquifers and surface waters of this region. From the hydrogeological settings, it is seen that Kuttanad is a multiaquifer system of formations of Eocene to Recent age. Quarternary Alluvium and Laterite form the top phreatic aquifer and is underlain by Tertiary sediments that are under confined condition. Archaean crystalline rock forms the basement and is exposed at the eastern periphery of the area. There are four distinct groups of formations in Tertiary sediments namely, Warkali bed, Quilon bed, Vaikom bed and Alleppey bed of which Vaikom and Warkali are potential aquifers. Pre-monsoon (May, 2000) and post-monsoon (November 2000) samples were collected from tube wells tapping

  7. Complex slab structure and arc magmatism beneath the Japanese Islands

    Science.gov (United States)

    Hasegawa, Akira; Nakajima, Junichi; Yanada, Takahiro; Uchida, Naoki; Okada, Tomomi; Zhao, Dapeng; Matsuzawa, Toru; Umino, Norihito

    2013-12-01

    A dense nationwide seismic network recently constructed in Japan has resulted in the production of a large amount of high-quality data that have enabled the high-resolution imaging of deep seismic structures in the Japanese subduction zone. Seismic tomography, precise locations of earthquakes, and focal mechanism research have allowed the identification of the complex structure of subducting slabs beneath Japan, revealing that the subducting Philippine Sea slab underneath southwestern Japan has an undulatory configuration down to a depth of 60-200 km, and is continuous from Kanto to Kyushu without disruption or splitting, even within areas north of the Izu Peninsula. Analysis of the geometry of the Pacific and Philippine Sea slabs identified a broad contact zone beneath the Kanto Plain that causes anomalously deep interplate and intraslab earthquake activity. Seismic tomographic inversions using both teleseismic and local events provide a clear image of the deep aseismic portion of the Philippine Sea slab beneath the Japan Sea north of Chugoku and Kyushu, and beneath the East China Sea west of Kyushu down to a depth of ˜450 km. Seismic tomography also allowed the identification of an inclined sheet-like seismic low-velocity zone in the mantle wedge beneath Tohoku. A recent seismic tomography work further revealed clear images of similar inclined low-velocity zones in the mantle wedge for almost all other areas of Japan. The presence of the inclined low-velocity zones in the mantle wedge across the entirety of Japan suggests that it is a common feature to all subduction zones. These low-velocity zones may correspond to the upwelling flow portion of subduction-induced convection systems. These upwelling flows reach the Moho directly beneath active volcanic areas, suggesting a link between volcanism and upwelling.

  8. Digital data sets that describe aquifer characteristics of the Vamoosa-Ada aquifer in east-central Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized aquifer boundaries for the Vamoosa-Ada aquifer in east-central Oklahoma. The Vamoosa-Ada aquifer is an important source of water...

  9. Digital data sets that describe aquifer characteristics of the Tillman terrace and alluvial aquifer in southwestern Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digital aquifer boundaries for the Tillman terrace and alluvial aquifer in southwestern Oklahoma. The Tillman terrace aquifer encompasses...

  10. Using hydrogeochemistry to understand inter-aquifer mixing in the on-shore part of the Gippsland Basin, southeast Australia

    International Nuclear Information System (INIS)

    Highlights: ► First 14C data for the inter-mountainous Gippsland Basin. ► Hydrogeochemistry shows inter-aquifer mixing, which is not possible with head data. ► Groundwater flow occurs across aquifer boundaries horizontally and vertically. ► Isotope data indicate chemical processes such as methanogenesis in some aquifers. ► Although 14C age correction is difficult, we correct for geochemical processes. - Abstract: Groundwater in the Latrobe Valley in the Gippsland Basin of southeast Australia is important for domestic, agricultural and industrial uses. This sedimentary basin contains a number of aquifers that are used for water supply, dewatered for open pit coal mining, and which are potentially influenced by off-shore oil and gas production. Major ion chemistry together with stable and Sr isotope data imply that the main hydrogeochemical processes are evapotranspiration with minor silicate and carbonate weathering; methanogenesis and SO4 reduction in reduced groundwater associated with coal deposits have also occurred. Groundwater has estimated 14C ages of up to 36 ka and is largely 3H free. Carbon-14 ages are irregularly distributed and poorly correlated with depth and distance from the basin margins. The observations that the geochemistry of groundwater in aquifers with different mineralogies are similar and the distribution of 14C ages is irregular implies that the aquifers are hydraulically connected and horizontal as well as vertical inter-aquifer mixing occurs. The connection of shallow and deeper aquifers poses a risk for the groundwater resources in Gippsland as contaminants can migrate across aquifers and dewatering of shallow units may impact deeper parts of the groundwater system

  11. Stress from NaCl crystallization by CO2 injection in aquifers

    OpenAIRE

    OSSELIN, Florian; Fabbri, Antonin; FEN CHONG, Teddy; DANGLA, Patrick; Pereira, Jean-Michel; Lassin, Arnault

    2015-01-01

    The goal of this paper is to identify the mechanical impact of water evaporation and salt crystallisation during supercritical carbon dioxide injection (drying-out process) in aquifer rocks. The precipitation of salt and the resulting crystallisation pressure are inferred from the chemical equilibrium of the carbon dioxide-rich gas phase, the in-pore brine and the crystal. The induced rock strain and equivalent tensile stress are then estimated within the framework of isotropic linear poroela...

  12. Physical and chemical effects of CO2 storage in saline aquifers of the southern North Sea

    OpenAIRE

    Heinemann, Niklas

    2013-01-01

    One of the most promising mitigation strategies for greenhouse gas accumulation in the atmosphere is carbon capture and storage (CCS). Deep saline aquifers are seen as the most efficient carbon dioxide (CO2) storage sites, mainly because of their vast size and worldwide distribution. Injecting CO2 into brine filled media will cause a physical and chemical disequilibrium in the formation. This PhD thesis documents the investigation of some of the resulting effects which occur at th...

  13. Hydrogeophysical methods for analyzing aquifer storage and recovery systems

    Energy Technology Data Exchange (ETDEWEB)

    Minsley, B.J.; Ajo-Franklin, J.; Mukhopadhyay, A.; Morgan, F.D.

    2009-12-01

    Hydrogeophysical methods are presented that support the siting and monitoring of aquifer storage and recovery (ASR) systems. These methods are presented as numerical simulations in the context of a proposed ASR experiment in Kuwait, although the techniques are applicable to numerous ASR projects. Bulk geophysical properties are calculated directly from ASR flow and solute transport simulations using standard petrophysical relationships and are used to simulate the dynamic geophysical response to ASR. This strategy provides a quantitative framework for determining site-specific geophysical methods and data acquisition geometries that can provide the most useful information about the ASR implementation. An axisymmetric, coupled fluid flow and solute transport model simulates injection, storage, and withdrawal of fresh water (salinity {approx}500 ppm) into the Dammam aquifer, a tertiary carbonate formation with native salinity approximately 6000 ppm. Sensitivity of the flow simulations to the correlation length of aquifer heterogeneity, aquifer dispersivity, and hydraulic permeability of the confining layer are investigated. The geophysical response using electrical resistivity, time-domain electromagnetic (TEM), and seismic methods is computed at regular intervals during the ASR simulation to investigate the sensitivity of these different techniques to changes in subsurface properties. For the electrical and electromagnetic methods, fluid electric conductivity is derived from the modeled salinity and is combined with an assumed porosity model to compute a bulk electrical resistivity structure. The seismic response is computed from the porosity model and changes in effective stress due to fluid pressure variations during injection/recovery, while changes in fluid properties are introduced through Gassmann fluid substitution.

  14. Evaluation of Hydrochemical and Hydrogeological Characteristics of Riverbank Filtration Aquifer

    Science.gov (United States)

    Ko, K.; Suk, H.

    2009-12-01

    The riverbank filtration is a feasible method to secure potable water resources where surface water cannot be directly provided. Bank filtrate water has been recently recognized as an alternative water resource around Nakdong River area in South Korea. The high manganese and iron, which are mainly produced from microbial reduction of aquifer, are frequently observed problems in bank filtrated water and the causes of them have been studied by restricted researchers. To understand the source and occurrence of manganese and iron in bank filtration water, we examined the hydrochemical and isotopic characteristics of water and the features of aquifer sediments which are collected from two bank filtration application area, Ddan Island and Jeungsan-ri. Most of waters collected from Ddan island have Ca-(Cl+SO4) type and the variation of water chemistry are mainly induced by anions such as bicarbonate and nitrate that are sensitive to the redox condition of aquifer. Nitrate is not detected in deep (>20m) water with low dissolved oxygen (preventing the inflow of river water to the production wells. In addition, the aquifer underneath the clay layer is under reducing condition, which might cause the high concentration of reduced iron and manganese. Manganese in the sediments was in the form of easily reducible and exchangeable phase but iron were present dominantly in the form of reducible and carbonate phase from the modified sequential analysis. This indicates the different reactivity of manganese and iron for redox state. From the above results, manganese was extracted under weakly reduced condition but iron was extracted strong reducing condition.

  15. Imaging of seismic scatterers beneath the Gauribidanur (GBA) array

    International Nuclear Information System (INIS)

    A study has been conducted to image seismic scatterers beneath the Gauribidanur (GBA) array in the Precambrian shield of south India. Short period digital data from teleseisms and regional events recorded over the 20 station L shaped array was used to image seismic scatterers beneath the array employing semblance technique. The results indicate a zone of dominant scattering encompassing the crust in a region west of GBA. The inferred zone of scattering coincides with a large N-S elongated granitic intrusion believed to be Precambrian suture zone between the East and West Dharwar craton. (author). 16 refs, 7 figs, 1 tab

  16. Soil aquifer treatment using advanced primary effluent

    KAUST Repository

    Sharma, Saroj K.

    2011-08-01

    Soil aquifer treatment (SAT) using primary effluent (PE) is an attractive option for wastewater treatment and reuse in many developing countries with no or minimal wastewater treatment. One of the main limitations of SAT of PE is rapid clogging of the infiltration basin due to high suspended solid concentrations. Some pre-treatment of PE before infiltration is likely to reduce this limitation, improve performance of SAT and help to implement this technology effectively. The effects of three pre-treatment options namely sedimentation (SED), coagulation (COAG) and horizontal roughing filtration (HRF) on SAT were analyzed by conducting laboratory-scale batch and soil column experiments. The sedimentation and coagulation pre-treatments led to less head loss development and reduction of clogging effect. The head loss development in soil column using PE + COAG and PE + SED was reduced by 85 and 72%, respectively, compared to PE alone without any pretreatment. The overall dissolved organic carbon (DOC) removal of pre-treatments and soil column collectively were 34, 44, 51 and 43.5% for PE without any pre-treatment, PE + SED, PE+ COAG and PE + HRF, respectively. Coagulation pre-treatment of PE was found to be the most effective option in terms of suspended solids, DOC and nitrogen removal. Sedimentation pre-treatment of PE could be attractive where land is relatively less expensive for the construction of sedimentation basins. © IWA Publishing 2011.

  17. Chlorine isotope investigation of natural attenuation of trichloroethene in an aerobic aquifer

    International Nuclear Information System (INIS)

    Natural attenuation of chlorinated aliphatic hydrocarbons (CAHs) can be an important mechanism for groundwater remediation. It is difficult to determine the effectiveness of natural CAH attenuation from chemical analyses of groundwater samples because mixing, dispersion, and secondary reactions can mask the chemical evidence of attenuation. In this paper, the authors explore the application of stable chlorine isotope ratio measurements as a new tool for evaluating natural attenuation of CAHs. They report stable isotope ratios of chlorine in both trichloroethene (TCE) and inorganic chloride in groundwater from an aerobic aquifer beneath an extensively contaminated industrial site, the Paducah Gaseous Diffusion Plant in western Kentucky. Variations in the concentrations and chlorine isotope ratios of TCE and chloride in the groundwater are consistent with those expected from natural attenuation. These data support a model in which partial TCE degradation occurred in relatively impermeable, clay-rich sediments above the aquifer, and little or no further degradation of TCE occurred within the aquifer. A record of changing conditions within the TCE source area can be inferred from the spatial variation of chlorine isotope ratios for TCE and chloride within the plume

  18. Biogeochemistry of Methane-Driven Destruction of Trichloroethylene in a Basalt Aquifer

    Science.gov (United States)

    Colwell, F.; Conrad, M.; Paszcynski, A.; Brodie, E.; Delwiche, M.; Radtke, C.; Lee, H.; Paidisetti, R.; Crawford, R.; Bernardini, N.; Johnson, A.; Starr, R.; Swift, D.; Newby, D.; Barnes, J.

    2008-12-01

    We studied the biogeochemical processes responsible for cycling methane and the fortuitous destruction of trichloroethylene (TCE) across spatially distinct locations in a basalt aquifer. This field study was accomplished by examining the attached and unattached microbial communities inherent to the aquifer by using a flow-through in situ reactor (FTISR) and large volumes of aquifer water from which microbial communities were concentrated. After incubation for 238 days, basalt and water were collected from the FTISR and analyzed using proteomics, gene expression, metabolic activity, microbial community structure, and kinetics of TCE degradation. Stable carbon isotopes and PhyloChip gene hybridization analyses were done on groundwater samples. Microbes from the FTSIR co-metabolically degraded approximately 7.5 mg of TCE per liter of groundwater. Proteins from aerobic methanotrophs were detected in the aquifer and on the basalt from the FTISR. Methanotrophic activity in the groundwater and on the FTISR basalt was also confirmed by combined use of enzyme biochemical probes and fluorescent in situ hybridization. Real-time PCR identified ca. 3000 copies of mmoX (a methanotrophic gene) per g of basalt and reverse transcriptase PCR determined that the mmoX subunit was actively transcribed. Stable carbon isotope ratios of dissolved inorganic carbon (DIC) and dissolved methane indicated increased levels of methane oxidation with distance from the source of the TCE (-55 to 28 per mil for methane; >8 to -13 per mil for DIC) corresponding to increased dissolved oxygen concentrations in the aquifer. These geochemistry data are consistent with community composition and activity determinations that identified a gradient of methanogenic to methanotrophic populations along the contaminant plume. Multiple analyses using samples from the FTISR and aquifer water comprehensively demonstrate that both attached and unattached microbial communities are responsible for methane-driven co

  19. Atrazine removal in Danish anaerobic aquifers

    DEFF Research Database (Denmark)

    Pedersen, Philip Grinder; Arildskov, N.P.; Albrechtsen, Hans-Jørgen

    2002-01-01

    The pesticide atrazine (6-chloro-N-2-ethyl-N-4-isopropyl-1,3,5-triazine -2,4-diamine) was removed from the water phase in anaerobic laboratory batch incubations with sediment and groundwater from a number of Danish anaerobic aquifers, but not in incubations from aerobic aquifers. The removal...

  20. Geohydrology of the Cerro Prieto geothermal aquifer

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez R, J.; de la Pena L, A.

    1981-01-01

    The most recent information on the Cerro Prieto geothermal aquifer is summarized, with special emphasis on the initial production zone where the wells completed in the Alpha aquifer are located. These wells produce steam for power plant units 1 and 2. Brief comments also are made on the Beta aquifer, which underlies the Alpha aquifer in the Cerro Prieto I area and which extends to the east to what is known as the Cerro Prieto II and Cerro Prieto III areas. The location of the area studied is shown. The Alpha and Beta aquifers differ in their mineralogy and cementing mineral composition, temperatures, and piezometric levels. The difference in piezometric levels indicates that there is no local communication between the two aquifers. This situation has been verified by a well interference test, using well E-1 as a producer in the Beta aquifer and well M-46 as the observation well in the Alpha aquifer. No interference between them was observed. Information on the geology, geohydrology, and geochemistry of Cerro Prieto is presented.

  1. VULNERABILITY OF KARST AQUIFERS TO CHEMICAL CONTAMINATION

    Science.gov (United States)

    Ground water flow in karst aquifers is very different from flow in granular or fractured aquifers. arst ground water flow is often turbulent within discrete conduits that are convergent in the upper reaches and divergent in the lower, simulating discharge to one or more springs. ...

  2. Sources of high-chloride water and managed aquifer recharge in an alluvial aquifer in California, USA

    Science.gov (United States)

    O'Leary, David R.; Izbicki, John A.; Metzger, Loren F.

    2015-11-01

    As a result of pumping in excess of recharge, water levels in alluvial aquifers within the Eastern San Joaquin Groundwater Subbasin, 130 km east of San Francisco (California, USA), declined below sea level in the early 1950s and have remained so to the present. Chloride concentrations in some wells increased during that time and exceeded the US Environmental Protection Agency's secondary maximum contaminant level of 250 mg/L, resulting in removal of some wells from service. Sources of high-chloride water include irrigation return in 16 % of sampled wells and water from delta sediments and deeper groundwater in 50 % of sampled wells. Chloride concentrations resulting from irrigation return commonly did not exceed 100 mg/L, although nitrate concentrations were as high as 25 mg/L as nitrogen. Chloride concentrations ranged from less than 100-2,050 mg/L in wells affected by water from delta sediments and deeper groundwater. Sequential electromagnetic logs show movement of high-chloride water from delta sediments to pumping wells through permeable interconnected aquifer layers. δD and δ18O data show most groundwater originated as recharge along the front of the Sierra Nevada, but tritium and carbon-14 data suggest recharge rates in this area are low and have decreased over recent geologic time. Managed aquifer recharge at two sites show differences in water-level responses to recharge and in the physical movement of recharged water with depth related to subsurface geology. Well-bore flow logs also show rapid movement of water from recharge sites through permeable interconnected aquifer layers to pumping wells.

  3. Shallow Aquifer Methane Gas Source Assessment

    Science.gov (United States)

    Coffin, R. B.; Murgulet, D.; Rose, P. S.; Hay, R.

    2014-12-01

    Shale gas can contribute significantly to the world's energy demand. Hydraulic fracturing (fracking) on horizontal drill lines developed over the last 15 years makes formerly inaccessible hydrocarbons economically available. From 2000 to 2035 shale gas is predicted to rise from 1% to 46% of the total natural gas for the US. A vast energy resource is available in the United States. While there is a strong financial advantage to the application of fracking there is emerging concern about environmental impacts to groundwater and air quality from improper shale fracking operations. Elevated methane (CH4) concentrations have been observed in drinking water throughout the United States where there is active horizontal drilling. Horizontal drilling and hydraulic-fracturing can increase CH4 transport to aquifers, soil and the vadose zone. Seepage can also result from casing failure in older wells. However, there is strong evidence that elevated CH4 concentrations can be associated with topographic and hydrogeologic features, rather than shale-gas extraction processes. Carbon isotope geochemistry can be applied to study CH4source(s) in shallow vadose zone and groundwater systems. A preliminary TAMU-CC isotope data set from samples taken at different locations in southern Texas shows a wide range of CH4 signatures suggesting multiple sources of methane and carbon dioxide. These data are interpreted to distinguish regions with methane contributions from deep-sourced horizontal drilling versus shallow system microbial production. Development of a thorough environmental assessment using light isotope analysis can provide understanding of shallow anthropogenic versus natural CH4sources and assist in identifying regions that require remedial actions.

  4. Groundwater evolution beneath Hat Yai, a rapidly developing city in Thailand

    Science.gov (United States)

    Lawrence, A. R.; Gooddy, D. C.; Kanatharana, P.; Meesilp, W.; Ramnarong, V.

    2000-09-01

    Many cities and towns in South and Southeast Asia are unsewered, and urban wastewaters are often discharged either directly to the ground or to surface-water canals and channels. This practice can result in widespread contamination of the shallow groundwater. In Hat Yai, southern Thailand, seepage of urban wastewaters has produced substantial deterioration in the quality of the shallow groundwater directly beneath the city. For this reason, the majority of the potable water supply is obtained from groundwater in deeper semi-confined aquifers 30-50 m below the surface. However, downward leakage of shallow groundwater from beneath the city is a significant component of recharge to the deeper aquifer, which has long-term implications for water quality. Results from cored boreholes and shallow nested piezometers are presented. The combination of high organic content of the urban recharge and the shallow depth to the water table has produced strongly reducing conditions in the upper layer and the mobilisation of arsenic. A simple analytical model shows that time scales for downward leakage, from the surface through the upper aquitard to the semi-confined aquifer, are of the order of several decades. Résumé. De nombreuses villes du sud et du sud-est de l'Asie ne possèdent pas de réseaux d'égouts et les eaux usées domestiques s'écoulent souvent directement sur le sol ou dans des canaux et des cours d'eau de surface. Ces pratiques peuvent provoquer une contamination dispersée de la nappe phréatique. A Hat Yai (sud de la Thaïlande), les infiltrations d'eaux usées domestiques sont responsables d'une détérioration notable de la qualité de la nappe phréatique directement sous la ville. Pour cette raison, la majorité de l'eau potable est prélevée dans des aquifères semi-captifs plus profonds, situés entre 30 et 50 m sous la surface. Cependant, une drainance à partir de la nappe phréatique sous la ville constitue une composante significative de la recharge

  5. Origin and residence times of the groundwater in the multilayered aquifer of Tadla (Morocco)

    International Nuclear Information System (INIS)

    Ninety-four samples were collected from the multilayered aquifer (Mio-Plio- Quaternary, Eocene, Senonian and Turonian) of Tadla (Morocco) and have been analyzed for their major chemical elements and the stable and radioactive isotopes of the molecule of water (18O, 2H, 3H) and of the Total Inorganic Dissolved Carbon TDIC (13C and 14C). The multidimensional statistical study of these parameters by the Main Component Analysis (MCA) indicates the existence of two big groups of groundwater that are distinguished by their chemical and isotopic characteristics. These two groups correspond to the unconfined and the confined zones of the different aquifers. The isotopes indicate that the present recharge continues to function, notably in the North part of the basin, where all the aquifers outcrops. The present recharge continues also to function in the Turonian aquifer in its East and Southwest outcrop. The present recharge is done rapidly for the Turonian aquifer and after a certain time of retention in the unsaturated zone for the Senonian and Eocene aquifers, where the groundwater undergoes a kinetic evaporation. All the chemical and isotopic parameters indicate indeed, the existence of a large intercommunications between the different aquifers 'per descendum' in their unconfined parts and 'per acsensum' in their confined parts. All isotopes showed that the springs which are located in the South-West of the basin and supposed to be, by the previous studies, the natural outlet of the different aquifers, are very recent, with high 18O and 2H signatures due to the high altitude (Atlasic recharge type). It was concluded that the present recharge of the aquifers of Tadla basin continue to function principally to the level of the North outcrops. For the Turonian aquifer, it exists a contribution of Atlasic type to the level of the outcrops of southerly West and of the East. Two other periods of recharges could be considered. They took place under a cold climate, probably

  6. Death Valley Lower Carbonate Aquifer Monitoring Program Wells Down Gradient of the Proposed Yucca Mountain Nuclear Waste Repository, U. S. Department of Energy Grant DE-RW0000233 2010 Project Report, prepared by The Hydrodynamics Group, LLC for Inyo County Yucca Mountain Repository Assessment Office

    Energy Technology Data Exchange (ETDEWEB)

    King, Michael J; Bredehoeft, John D., Dr.

    2010-09-03

    Inyo County completed the first year of the U.S. Department of Energy Grant Agreement No. DE-RW0000233. This report presents the results of research conducted within this Grant agreement in the context of Inyo County's Yucca Mountain oversight program goals and objectives. The Hydrodynamics Group, LLC prepared this report for Inyo County Yucca Mountain Repository Assessment Office. The overall goal of Inyo County's Yucca Mountain research program is the evaluation of far-field issues related to potential transport, by ground water, of radionuclide into Inyo County, including Death Valley, and the evaluation of a connection between the Lower Carbonate Aquifer (LCA) and the biosphere. Data collected within the Grant is included in interpretive illustrations and discussions of the results of our analysis. The centeral elements of this Grant prgoram was the drilling of exploratory wells, geophysical surveys, geological mapping of the Southern Funeral Mountain Range. The cullimination of this research was 1) a numerical ground water model of the Southern Funeral Mountain Range demonstrating the potential of a hydraulic connection between the LCA and the major springs in the Furnace Creek area of Death Valley, and 2) a numerical ground water model of the Amargosa Valley to evaluate the potential for radionuclide transport from Yucca Mountain to Inyo County, California. The report provides a description of research and activities performed by The Hydrodynamics Group, LLC on behalf of Inyo County, and copies of key work products in attachments to this report.

  7. Economics of Managed Aquifer Recharge

    Directory of Open Access Journals (Sweden)

    Robert G. Maliva

    2014-05-01

    Full Text Available Managed aquifer recharge (MAR technologies can provide a variety of water resources management benefits by increasing the volume of stored water and improving water quality through natural aquifer treatment processes. Implementation of MAR is often hampered by the absence of a clear economic case for the investment to construct and operate the systems. Economic feasibility can be evaluated using cost benefit analysis (CBA, with the challenge of monetizing benefits. The value of water stored or treated by MAR systems can be evaluated by direct and indirect measures of willingness to pay including market price, alternative cost, value marginal product, damage cost avoided, and contingent value methods. CBAs need to incorporate potential risks and uncertainties, such as failure to meet performance objectives. MAR projects involving high value uses, such as potable supply, tend to be economically feasible provided that local hydrogeologic conditions are favorable. They need to have low construction and operational costs for lesser value uses, such as some irrigation. Such systems should therefore be financed by project beneficiaries, but dichotomies may exist between beneficiaries and payers. Hence, MAR projects in developing countries may be economically viable, but external support is often required because of limited local financial resources.

  8. Aquifer vulnerability to pesticide pollution - Combining soil, land-use and aquifer properties with molecular descriptors

    Science.gov (United States)

    Worrall, F.; Kolpin, D.W.

    2004-01-01

    This study uses an extensive survey of herbicides in groundwater across the midwest United States to predict occurrences of a range of compounds across the region from a combination of their molecular properties and the properties of the catchment of a borehole. The study covers 100 boreholes and eight pesticides. For each of the boreholes its catchment the soil, land-use and aquifer properties were characterized. Discriminating boreholes where pollution occurred from those where no pollution occurred gave a model that was 74% correct with organic carbon content, percentage sand content and depth to the water table being significant properties of the borehole catchment. Molecular topological descriptors as well as Koc, solubility and half-life were used to characterize each compound included in the study. Inclusion of molecular properties makes it possible to discriminate between occurrence and non-occurrence of each compound in each well. The best-fit model combines: organic carbon content, percentage sand content and depth to the water table with molecular descriptors representing molecular size, molecular branching and functional group composition of the herbicides.

  9. Carbonate-sulfate volcanism on Venus?

    Science.gov (United States)

    Kargel, Jeffrey S.; Kirk, Randolph L.; Fegley, Bruce, Jr.

    1994-01-01

    Venusian canali, outflow channels, and associated volcanic deposits resemble fluvial landforms more than they resmeble volcanic features on Earth and Mars. Some canali have meandering habits and features indicative of channel migration that are very similar to meandering river channels and flood plains on Earth, venusian outflow channels closely resemble water-carved outflow channels on Mars and the Channeled Scabland in Washington, collapsed terrains at the sources of some venusian channels resemble chaotic terrains at the sources of martian outflow channels, venusian lava deltas are similar to bird's-foot deltas such as the Mississippi delta, and venusian valley networks indicate sapping. We have developed an alternative possibility that the lava had a water-like rheology and a melting point slightly greater than Venus' surface temperature, thus accounting for the unusual behavior of the lava. Unlike silicate lavas, some carbonatites (including carbonate-sulfate-rich liquids) have these properties; thus they can flow great distances while retaining a high fluidity, significant mechanical erosiveness, and substantial capacity to transport and deposit sediment. Venusian geochemistry and petrology are consistent with extensive eruptions of carbonatite lavas, which could have crustal and/or mantle origins. Venus' atmosphere (especially CO2, HCl, and HF abundances) and rocks may be in local chemical equilibrium, which suggests that the upper crust contains large amounts of calcite, anhydrite, and other salts. Chemical analyses indicate, according to some models, that Venusian rocks may contain 4-19% calcite and anhydrite. Mixtures of crustal salts could melt at temperatures a few tens to a few hundred Kelvins higher than Venus' surface temperature; hence, melting may be induced by modest endogenetic or impact heating. Salts may have many of the same geologic roles on Venus as water and ice have on Mars. A molten salt (carbonatite) 'aquifer' may exist beneath a few

  10. Candidates of M7-Class Earthquake Beneath Greater Tokyo Area

    Science.gov (United States)

    Okada, Y.

    2003-12-01

    In greater Tokyo area, the occurrence of M7-class earthquake is thought to be imminent by the following reasons. (1) In these 20 years, maximum size of shallow microearthquakes beneath Tokyo is steadily increasing. (2) In recent 80 years after Kanto earthquake, maximum size of the earthquakes in Kanto region is gradually increasing. (3) In these 400 years, it was observed twice that two M7-class earthquakes precede the M8 interplate earthquakes in the latter half of the interseismic period. Taking into consideration these background, the Central Disaster Management Council, Japan issued _gGuideline for Countermeasures to the Earthquakes Beneath Southern Kanto Region _h on August 1994, and proposed 19 fault models along the upper boundary of Philippine Sea plate as the candidates of the forthcoming M7-class earthquake. At present, we have no data of abnormal seismic activity or crustal movement to select preferable one among these 19 fault models. Here, we will try to constrain the candidates which may have relatively higher possibility of the occurrence by a elimination method. It seems to be possible to exclude some of the fault models by the following ways. (1) Adopting characteristic earthquake concept, we can exclude 5 models which overlap to the focal region of 1923 Kanto earthquake. (2) A belt like zone of serpentine are found from tomography results at 30-40km depth along the Philippine Sea plate beneath the Kanto Plain and no microearthquake activities are generated along this zone (Kamiya and Kobayashi, GRL, 2000). We can eliminate 4 models which lie in this zone. (3) Beneath the eastern Boso Peninsula, it was found that slow slips of M6.5-class are repeated every 5-6 years. We can exclude 2 models in the area (4) Since plate collision is undertaken beneath eastern Yamanashi Prefecture, we can exclude 1 model in this area. Finally, it remains 7 fault models as the possible candidates of M7-class earthquake beneath Tokyo area. They are 3 models just beneath

  11. Potential Risks of Freshwater Aquifer Contamination with Geosequestration

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Robert

    2013-09-30

    Substantial leakage of CO{sub 2} from deep geological strata to shallow potable aquifers is likely to be rare, but chemical detection of potential leakage nonetheless remains an integral component of any safe carbon capture and storage system. CO{sub 2} that infiltrates an unconfined freshwater aquifer will have an immediate impact on water chemistry by lowering pH in most cases and by altering the concentration of total dissolved solids. Chemical signatures in affected waters provide an important opportunity for early detection of leaks. In the presence of CO{sub 2}, trace elements such as Mn, Fe, and Ca can increase by an order of magnitude or more above control concentrations within 100 days. Therefore, these and other elements should be monitored along with pH as geochemical markers of potential CO{sub 2} leaks. Dissolved inorganic carbon and alkalinity can also be rapidly responsive to CO{sub 2} and are stable indicators of a leak. Importantly, such changes may be detectable long before direct changes in CO{sub 2} are observed. The experimental results also suggest that the relative severity of the impact of leaks on overlying drinking-water aquifers should be considered in the selection of CO{sub 2} sequestration sites. One primary selection criteria should be metal and metalloid availability, such as uranium and arsenic abundance, to carefully monitor chemical species that could trigger changes above maximum contaminant levels (MCLs). Overall, the risks of leakage from underground CO{sub 2} storage are real but appear to be manageable if systems are closely monitored.

  12. Geohydrology and water quality of the Inyan Kara, Minnelusa, and Madison aquifers of the northern Black Hills, South Dakota and Wyoming, and Bear Lodge Mountains, Wyoming

    Science.gov (United States)

    Kyllonen, D.P.; Peter, K.D.

    1987-01-01

    The Inyan Kara, Minnelusa, and Madison aquifers are the principal sources of ground water in the northern Black Hills, South Dakota and Wyoming, and Bear Lodge Mountains, Wyoming. The aquifers are exposed in the Bear Lodge Mountains and the Black Hills and are about 3,000 to 5,000 ft below the land surface in the northeast corner of the study area. The direction of groundwater movement is from the outcrop area toward central South Dakota. Recharge is by infiltration of precipitation and streamflow is by springs and well withdrawals. All three aquifers yield water to flowing wells in some part of the area. Measured and reported well yields in each of the three aquifers exceed 100 gal/min (gpm). A well open to the Minnelusa Formation and the upper part of the Madison Limestone yielded more than 2 ,000 gpm. Water from the Inyan Kara aquifer may require treatment for gross alpha radiation, iron, manganese, sulfate, and hardness before use in public water systems. Water from the Minnelusa aquifer in the northern one-half of the study area may require treatment for sulfate and hardness before use in public water systems. Water from the Madison aquifer in the northern one-half of the study area may require treatment of fluoride, gross alpha radiation, sulfate, and hardness before use in public water systems. Water from the Minnelusa and Madison aquifers in the southern one-half of the study area, though very hard (more than 180 mg/L hardness as calcium carbonate), is suitable for public water systems and irrigation. Flow between the Minnelusa and the Inyan Kara aquifers appears to be insignificant, based on the results of a digital model results. The model indicated there may be significant recharge to the Minnelusa and Madison aquifers by leakage between these two aquifers and perhaps deeper aquifers. (Author 's abstract)

  13. Hot mantle upwelling across the 660 beneath Yellowstone

    Science.gov (United States)

    Schmandt, Brandon; Dueker, Kenneth; Humphreys, Eugene; Hansen, Steven

    2012-05-01

    P-to-s receiver functions mapped to depth through P and S body-wave tomography models image continuous 410 and 660 km discontinuities beneath the area covered by USArray prior to the year 2011. Mean depths to the 410 and 660 km discontinuities of 410 and 656 km imply a mantle transition zone that is about 4 km thicker than the global average and hence has a slightly cooler mean temperature and/or enhanced water content. Compared to the mean 660 depth beneath this ~ 2000 km wide area, the 660 beneath the Yellowstone hotspot is deflected upward by 12-18 km over an area about 200 km wide. This is the most anomalous shallowing of the 660 imaged and its horizontal extent is similar to the area where P and S tomography image low-velocity mantle extending from the top of the transition zone to about 900 km depth. Together, these results indicate a high-temperature, plume-like upwelling extending across the 660. The depth of 410 km discontinuity beneath the Yellowstone region is within 5 km of the mean depth implying that the plume is vertically heterogeneous and possibly discontinuous. Tomography indicates a similar vertically heterogeneous thermal plume. The irregular plume structure may be intrinsic to the dynamics of upwelling through the transition zone, or distortion may be caused by subduction-induced mantle flow. Topography of the 410 and 660 confirms that subducted slabs beneath the western U.S. are highly segmented, as inferred from recent tomography studies. We find no evidence of regionally pervasive velocity discontinuities between 750 and 1400 km depth. The plume's depth of origin within the lower mantle remains uncertain.

  14. Distribution of hydrous minerals in the subduction system beneath Mexico

    Science.gov (United States)

    Kim, YoungHee; Clayton, Robert W.; Jackson, Jennifer M.

    2012-08-01

    Teleseismic converted phases are used to probe the composition of the downgoing oceanic crust as a function of depth along the Cocos slab in central and southern Mexico. Previously, modeling of the receiver function (RF) conversion amplitude of the flat Cocos slab beneath central Mexico at 45 km depth revealed a thin low-velocity upper oceanic crust of a thickness of 4±1 km, which has much lower seismic velocities (∼20-30% reduction in shear wave velocities) than (normal) lower crust. High Vp/Vs ratio (∼2.0) also suggested a large concentration of hydrous minerals such as talc in combination of high pore-fluid pressure in the horizontal segment. We extend this previous effort to examine seismic properties of both the steeply subducting Cocos oceanic crust beneath the Trans-Mexican Volcanic Belt (TMVB) in central Mexico and the shallowly dipping crust beneath southern Mexico. Inverted seismic velocities using the converted amplitudes at the top and bottom of the dipping oceanic crust are compared with experimentally constrained seismic velocities of candidate mineral phases in a range of likely pressures and temperatures. The composition of the oceanic crust downdip in the steep part of slab beneath the TMVB includes the minerals such as lawsonite and zoisite at 60-100 km depth, and the eclogitization occurs around 100 km depth. This is related to arc volcanism in the TMVB directly above the slab as well as the slab rollback. In contrast, the dominant mineral phase in the upper oceanic crust of southern Mexico beneath the Isthmus of Tehauntepec is amphibole on top of unaltered gabbroic oceanic crust. The difference in mineral assemblages of the subducted oceanic crust may help explain the difference in slab geometries between central and southern Mexico.

  15. Large sedimentary aquifer systems functioning. Constraints by classical isotopic and chemical tools, and REE in the Eocene sand aquifer, SW France

    Science.gov (United States)

    Petelet-Giraud, E.; Negrel, P. J.; Millot, R.; Guerrot, C.; Brenot, A.; Malcuit, E.

    2010-12-01

    Large sedimentary aquifer systems often constitute strategic water resources for drinking water supply, agriculture irrigation and industry, but can also represent an energetic resource for geothermal power. Large water abstractions can induce complete modification of the natural functioning of such aquifer systems, e.g. with seepage between aquifer layers that can lead to water quality degradation. These large aquifer systems thus require rational water management at the sedimentary basin scale in order to preserve both water quantity and quality. In addition to hydrogeological modelling mainly dealing with water quantity, chemical and isotopic methods were applied to evidence the spatial variability of water characteristics and to turn this into better understanding of hydrosystems functioning. The large Eocene Sand aquifer system of the Adour-Garonne sedimentary basin was studied through various hydrological, chemical and isotopic tools. This system extends over 116,000 km2 (one-fifth of the French territory, located in the South west part). The aquifer being artesian in the west of the district and confined with piezometric levels around 250-m depth in the east. The ‘Eocene Sands’, composed of sandy Tertiary sediments alternating with carbonate deposits, is a multi-layer system with high permeability and a thickness of several tens of metres to a hundred metres..The Eocene Sand aquifer system comprises at least five aquifers: Paleocene, Eocene infra-molassic sands (IMS), early Eocene, middle Eocene, and late Eocene. According to δ18O and δ2H values and estimated 14C ages, both present-day recharge (mainly located in the north of the area) and old recharge (16-35 ky) can be evidenced. High spatial variability was evidenced within a same aquifer layer, with temporal variability over one hydrological cycle limited to a few points located in the recharge areas. These results and especially the very old waters recharged under colder climate combined with the

  16. Recharge beneath low-impact design rain gardens and the influence of El Niño Southern Oscillation on urban, coastal groundwater resources

    Science.gov (United States)

    Newcomer, M. E.; Gurdak, J. J.

    2011-12-01

    Groundwater resources in urban, coastal environments are highly vulnerable to increased human pressures and climate variability. Impervious surfaces, such as buildings, roads, and parking lots prevent infiltration, reduce recharge to underlying aquifers, and increase contaminants in surface runoff that often overflow sewage systems. To mitigate these effects, cities worldwide are adopting low impact design (LID) approaches that direct runoff into natural vegetated systems, such as rain gardens that reduce, filter, and slow stormwater runoff, and are hypothesized to increase infiltration and recharge rates to aquifers. The effects of LID on recharge rates and quality is unknown, particularly during intense precipitation events for cities along the Pacific coast in response to interannual variability of the El Niño Southern Oscillation (ENSO). Using vadose zone monitoring sensors and instruments, I collected and monitored soil, hydraulic, and geochemical data to quantify the rates and quality of infiltration and recharge to the California Coastal aquifer system beneath a LID rain garden and traditional turf-lawn setting in San Francisco, CA. The data were used to calibrate a HYDRUS-3D model to simulate recharge rates under historical and future variability of ENSO. Understanding these processes has important implications for managing groundwater resources in urban, coastal environments.

  17. Techniques for Source Zone and Plume Characterization of Tetrachloroethene in Fractured Limestone Aquifers

    DEFF Research Database (Denmark)

    Fjordbøge, Annika Sidelmann; Mosthaf, Klaus; Janniche, Gry S.;

    Characterization of chlorinated solvents in fractured limestone aquifers is essential for proper development of site specific conceptual models and subsequent risk assessment and remediation. High resolution characterization is challenged by the difficulties involved in collection of intact core...... fractured limestone aquifers. The two sites represent different scales (source and plume) and contaminant levels (DNAPL and dissolved). The scope of the investigations was to evaluate different techniques for characterization of the contaminant distribution in the limestone aquifers and to obtain an...... of the FACT field measurements, which allows the conversion of discrete activated carbon concentrations to aqueous concentrations at given hydraulic parameters and FACT parameters. The passive groundwater sampling with snap samplers resulted in significantly different concentration levels and...

  18. Attenuation of contaminants of emerging concern during surface-spreading aquifer recharge.

    Science.gov (United States)

    Laws, Bonnie V; Dickenson, Eric R V; Johnson, Theodore A; Snyder, Shane A; Drewes, Jörg E

    2011-02-15

    The attenuation of a diverse suite of contaminants of emerging concern (CECs) and bulk water quality changes was evaluated at a surface-spreading aquifer recharge operation across a detailed subsurface profile (9 locations), representing both short- and long-travel times (10 h to 60 days). Seventeen CECs were detected in the recharge basin and the concentrations of all were reduced during soil aquifer treatment (SAT), with 11 of the target compounds attenuated by >80% after 60 days of travel time. Select CECs (atenolol, gemfibrozil, N,N-diethly-3-methylbenzamide, meprobamate, tris(2-chloroethyl)phosphate, and primidone) and bulk water organic-carbon measurements (total organic carbon, biodegradable organic carbon, size-exclusion chromatography and fluorescence excitation-emission matrices) were identified as monitoring parameters that can be used to assess SAT performance at surface-spreading operations. PMID:21211820

  19. Regional water quality patterns in an alluvial aquifer: Direct and indirect influences of rivers

    Science.gov (United States)

    Baillieux, A.; Campisi, D.; Jammet, N.; Bucher, S.; Hunkeler, D.

    2014-11-01

    The influence of rivers on the groundwater quality in alluvial aquifers can be twofold: direct and indirect. Rivers can have a direct influence via recharge and an indirect one by controlling the distribution of fine-grained, organic-carbon rich flood deposits that induce reducing conditions. These direct and indirect influences were quantified for a large alluvial aquifer on the Swiss Plateau (50 km2) in interaction with an Alpine river using nitrate as an example. The hydrochemistry and stable isotope composition of water were characterized using a network of 115 piezometers and pumping stations covering the entire aquifer. Aquifer properties, land use and recharge zones were evaluated as well. This information provided detailed insight into the factors that control the spatial variability of groundwater quality. Three main factors were identified: (1) diffuse agricultural pollution sources; (2) dilution processes resulting from river water infiltrations, revealed by the δ18OH2O and δ2HH2O contents of groundwater; and (3) denitrification processes, controlled by the spatial variability of flood deposits governed by fluvial depositional processes. It was possible to quantify the dependence of the nitrate concentration on these three factors at any sampling point of the aquifer using an end-member mixing model, where the average nitrate concentration in recharge from the agricultural area was evaluated at 52 mg/L, and the nitrate concentration of infiltrating river at approximately 6 mg/L. The study shows the importance of considering the indirect and direct impacts of rivers on alluvial aquifers and provides a methodological framework to evaluate aquifer scale water quality patterns.

  20. Stimulating in situ denitrification in an aerobic, highly permeable municipal drinking water aquifer

    Science.gov (United States)

    Critchley, K.; Rudolph, D. L.; Devlin, J. F.; Schillig, P. C.

    2014-12-01

    A preliminary trial of a cross-injection system (CIS) was designed to stimulate in situ denitrification in an aquifer servicing an urban community in southern Ontario. It was hypothesized that this remedial strategy could be used to reduce groundwater nitrate in the aquifer such that it could remain in use as a municipal supply until the beneficial effects of local reduced nutrient loadings lead to long-term water quality improvement at the wellfield. The CIS application involved injecting a carbon source (acetate) into the subsurface using an injection-extraction well pair positioned perpendicular to the regional flow direction, up-gradient of the water supply wells, with the objective of stimulating native denitrifying bacteria. The pilot remedial strategy was targeted in a high nitrate flux zone within an aerobic and heterogeneous section of the glacial sand and gravel aquifer. Acetate injections were performed at intervals ranging from daily to bi-daily. The carbon additions led to general declines in dissolved oxygen concentrations; decreases in nitrate concentration were localized in aquifer layers where velocities were estimated to be less than 0.5 m/day. NO3-15N and NO3-18O isotope data indicated the nitrate losses were due to denitrification. Relatively little nitrate was removed from groundwater in the more permeable strata, where velocities were estimated to be on the order of 18 m/day or greater. Overall, about 11 percent of the nitrate mass passing through the treatment zone was removed. This work demonstrates that stimulating in situ denitrification in an aerobic, highly conductive aquifer is challenging but achievable. Further work is needed to increase rates of denitrification in the most permeable units of the aquifer.

  1. Recharge from rectangular areas to finite aquifers

    Science.gov (United States)

    Rao, N. H.; Sarma, P. B. S.

    1981-10-01

    A generalized analytical solution is derived for the growth of groundwater mound in finite aquifers bounded by open water bodies, in response to recharge from rectangular areas. Finite Fourier transforms are used to solve the linearized differential equation of groundwater flow. Unlike earlier solutions, the method presented here does not require the use of tables for evaluation of complicated functions. The solution is evaluated by comparison with existing numerical and analytical results. In stream-aquifer systems similar to those described above, application of the proposed solution is more realistic than using solutions available for infinite aquifers.

  2. Aquifer restoration at in-situ leach uranium mines: evidence for natural restoration processes

    Energy Technology Data Exchange (ETDEWEB)

    Deutsch, W.J.; Serne, R.J.; Bell, N.E.; Martin, W.J.

    1983-04-01

    Pacific Northwest Laboratory conducted experiments with aquifer sediments and leaching solution (lixiviant) from an in-situ leach uranium mine. The data from these laboratory experiments and information on the normal distribution of elements associated with roll-front uranium deposits provide evidence that natural processes can enhance restoration of aquifers affected by leach mining. Our experiments show that the concentration of uranium (U) in solution can decrease at least an order of magnitude (from 50 to less than 5 ppM U) due to reactions between the lixiviant and sediment, and that a uranium solid, possibly amorphous uranium dioxide, (UO/sub 2/), can limit the concentration of uranium in a solution in contact with reduced sediment. The concentrations of As, Se, and Mo in an oxidizing lixiviant should also decrease as a result of redox and precipitation reactions between the solution and sediment. The lixiviant concentrations of major anions (chloride and sulfate) other than carbonate were not affected by short-term (less than one week) contact with the aquifer sediments. This is also true of the total dissolved solids level of the solution. Consequently, we recommend that these solution parameters be used as indicators of an excursion of leaching solution from the leach field. Our experiments have shown that natural aquifer processes can affect the solution concentration of certain constituents. This effect should be considered when guidelines for aquifer restoration are established.

  3. An effect of CO2 leakage from deep geological formations on the quality of shallow aquifers

    Science.gov (United States)

    Wang, Sookyun; Nam, Ji Eun

    2013-04-01

    Injection of CO2 into deep geological formations is a promising technique for Sequestration of large amount of CO2. If some fraction of the stored CO2 were to leak and reach shallow groundwater aquifers, however, it would lead to geochemical alteration that could have detrimental effects on the water quality. A series of experiments were performed on dissolution kinetics of a trace metal, galena, to evaluate the change in groundwater pH and the enhanced dissolution as carbon dioxide introduces into the aquifer. The conventional rate law was applied to obtain reaction parameters on dissolution kinetics for further modeling studies. The results from batch experiments and kinetic analysis were applied to develop a 1D mathematical model to simulate the fate and transport of dissolved trace metals in shallow aquifers. Results show that CO2 dissolution in groundwater aquifers can solubilize trace metals to levels that exceed drinking water standards. This approach allows for a reasonable assessment of the risks on tha quality of freshwater aquifers due to the escape of CO2 from deep geological formations.

  4. Aquifer restoration at in-situ leach uranium mines: evidence for natural restoration processes

    International Nuclear Information System (INIS)

    Pacific Northwest Laboratory conducted experiments with aquifer sediments and leaching solution (lixiviant) from an in-situ leach uranium mine. The data from these laboratory experiments and information on the normal distribution of elements associated with roll-front uranium deposits provide evidence that natural processes can enhance restoration of aquifers affected by leach mining. Our experiments show that the concentration of uranium (U) in solution can decrease at least an order of magnitude (from 50 to less than 5 ppM U) due to reactions between the lixiviant and sediment, and that a uranium solid, possibly amorphous uranium dioxide, (UO2), can limit the concentration of uranium in a solution in contact with reduced sediment. The concentrations of As, Se, and Mo in an oxidizing lixiviant should also decrease as a result of redox and precipitation reactions between the solution and sediment. The lixiviant concentrations of major anions (chloride and sulfate) other than carbonate were not affected by short-term (less than one week) contact with the aquifer sediments. This is also true of the total dissolved solids level of the solution. Consequently, we recommend that these solution parameters be used as indicators of an excursion of leaching solution from the leach field. Our experiments have shown that natural aquifer processes can affect the solution concentration of certain constituents. This effect should be considered when guidelines for aquifer restoration are established

  5. Assessing controls on perched saturated zones beneath the Idaho Nuclear Technology and Engineering Center, Idaho

    Science.gov (United States)

    Mirus, Benjamin B.; Perkins, Kim S.; Nimmo, John R.

    2011-01-01

    Waste byproducts associated with operations at the Idaho Nuclear Technology and Engineering Center (INTEC) have the potential to contaminate the eastern Snake River Plain (ESRP) aquifer. Recharge to the ESRP aquifer is controlled largely by the alternating stratigraphy of fractured volcanic rocks and sedimentary interbeds within the overlying vadose zone and by the availability of water at the surface. Beneath the INTEC facilities, localized zones of saturation perched on the sedimentary interbeds are of particular concern because they may facilitate accelerated transport of contaminants. The sources and timing of natural and anthropogenic recharge to the perched zones are poorly understood. Simple approaches for quantitative characterization of this complex, variably saturated flow system are needed to assess potential scenarios for contaminant transport under alternative remediation strategies. During 2009-2011, the U.S. Geological Survey (USGS), in cooperation with the U.S. Department of Energy, employed data analysis and numerical simulations with a recently developed model of preferential flow to evaluate the sources and quantity of recharge to the perched zones. Piezometer, tensiometer, temperature, precipitation, and stream-discharge data were analyzed, with particular focus on the possibility of contributions to the perched zones from snowmelt and flow in the neighboring Big Lost River (BLR). Analysis of the timing and magnitude of subsurface dynamics indicate that streamflow provides local recharge to the shallow, intermediate, and deep perched saturated zones within 150 m of the BLR; at greater distances from the BLR the influence of streamflow on recharge is unclear. Perched water-level dynamics in most wells analyzed are consistent with findings from previous geochemical analyses, which suggest that a combination of annual snowmelt and anthropogenic sources (for example, leaky pipes and drainage ditches) contribute to recharge of shallow and

  6. Models for wellhead protection in regional unconfined aquifers and stratified aquifers

    OpenAIRE

    Feseker, T.; Krijgsman, B; J. P. Lobo Ferreira

    2004-01-01

    Mathematical concepts are used for the development of wellhead protection and zoning methodologies, based on analytical solutions and on groundwater flow and particle tracking finite differences. Wellhead protection limits are a function of the local geology, of the aquifer parameters and the regional hydraulic characteristics of the aquifer, and of the extraction rates or of the productivity of the aquifer. In the vertical dimension the analysis was performed using an axisymmetric flow model...

  7. Influence of aquifer heterogeneity on the design and modelling of Aquifer Thermal Energy Storage (ATES) systems

    OpenAIRE

    Bridger, David W.

    2006-01-01

    A modelling study was carried out to evaluate the influence of aquifer heterogeneity, as represented by geologic layering, on heat transport and storage in aquifer thermal energy storage (ATES) systems. An existing ATES system installed within a heterogeneous aquifer system in Agassiz, British Columbia, Canada was used as a case study. Two 3D heat transport models of the study site were developed and calibrated using the heat transport code FEFLOW, including: a "simple" model domain with unif...

  8. Radial Dupuit interface flow to assess the aquifer storage and recovery potential of saltwater aquifers

    OpenAIRE

    Bakker, M.

    2009-01-01

    A new accurate numerical solution is presented for aquifer storage and recovery (ASR) systems in coastal aquifers; flow is approximated as radial Dupuit interface flow. The radial velocities of points on the interface are a function of time, the vertical coordinate, and the dimensionless parameter D (the discharge of the well divided by the product of the hydraulic conductivity, the square of the aquifer thickness, and the dimensionless density difference). The recovery efficiency of an ASR s...

  9. The vulnerability of the Dupi Tila Aquifer, Dhaka, Bangladesh

    OpenAIRE

    Hasan, M. K.

    1999-01-01

    The Dupi Tila aquifer in Bangladesh is of national importance, providing over 95% of the water supply for the capital city, Dhaka. The demand for water is rising inexorably. There is concern about the sustainability of the aquifer and its vulnerability to contamination. In Dhaka, the Dupi Tila aquifer is confined by the Madhupur Clay. Natural recharge to the aquifer is by vertical leakage through the Madhupur Clay. However, large-scale development of the aquifer since 1971 has ...

  10. Using 14C and 3H to delineate a recharge 'window' into the Perth Basin aquifers, North Gnangara groundwater system, Western Australia.

    Science.gov (United States)

    Meredith, Karina; Cendón, Dioni I; Pigois, Jon-Philippe; Hollins, Suzanne; Jacobsen, Geraldine

    2012-01-01

    The Gnangara Mound and the underlying Perth Basin aquifers are the largest source of groundwater for the southwest of Australia, supplying between 35 and 50% of Perth's potable water (2009-2010). However, declining health of wetlands on the Mound coupled with the reduction in groundwater levels from increased irrigation demands and drier climatic conditions means this resource is experiencing increased pressures. The northern Gnangara is an area where the Yarragadee aquifer occurs at shallow depths (~50 m) and is in direct contact with the superficial aquifer, suggesting the possibility of direct recharge into a generally confined aquifer. Environmental isotopes ((14)C and (3)H) and hydrochemical modelling were used to assess the presence of a recharge 'window' as well as understand the groundwater residence time within different aquifers. Forty-nine groundwater samples were collected from depths ranging from 11 to 311 m below ground surface. The isotopic variation observed in the superficial aquifer was found to be controlled by the different lithologies present, i.e. quartz-rich Bassendean Sand and carbonate-rich sediments of the Ascot Formation. Rainfall recharge into the Bassendean Sand inherits its dissolved inorganic carbon from the soil CO(2). Organic matter throughout the soil profile is degraded by oxidation leading to anoxic/acidic groundwater, which if in contact with the Ascot Formation leads to enhanced dissolution of carbonates. Hydrochemical mass balance modelling showed that carbonate dissolution could contribute 1-2 mmol kg(-1) of carbon to groundwaters recharged through the Ascot Formation. The corrected groundwater residence times of the Yarragadee aquifer in the northern part of the study area ranged from 23 to 35 ka, while waters in the southeastern corner ranged from sub-modern to 2 ka. Groundwater ages increase with distance radiating from the recharge 'window'. This study delineates a recharge 'window' into the commonly presumed confined

  11. Soil nematode communities are ecologically more mature beneath late- than early-successional stage biological soil crusts

    Science.gov (United States)

    Darby, B.J.; Neher, D.A.; Belnap, J.

    2007-01-01

    Biological soil crusts are key mediators of carbon and nitrogen inputs for arid land soils and often represent a dominant portion of the soil surface cover in arid lands. Free-living soil nematode communities reflect their environment and have been used as biological indicators of soil condition. In this study, we test the hypothesis that nematode communities are successionally more mature beneath well-developed, late-successional stage crusts than immature, early-successional stage crusts. We identified and enumerated nematodes by genus from beneath early- and late-stage crusts from both the Colorado Plateau, Utah (cool, winter rain desert) and Chihuahuan Desert, New Mexico (hot, summer rain desert) at 0-10 and 10-30 cm depths. As hypothesized, nematode abundance, richness, diversity, and successional maturity were greater beneath well-developed crusts than immature crusts. The mechanism of this aboveground-belowground link between biological soil crusts and nematode community composition is likely the increased food, habitat, nutrient inputs, moisture retention, and/or environmental stability provided by late-successional crusts. Canonical correspondence analysis of nematode genera demonstrated that nematode community composition differed greatly between geographic locations that contrast in temperature, precipitation, and soil texture. We found unique assemblages of genera among combinations of location and crust type that reveal a gap in scientific knowledge regarding empirically derived characterization of dominant nematode genera in deserts soils and their functional role in a crust-associated food web. ?? 2006 Elsevier B.V. All rights reserved.

  12. Lithospheric thinning beneath rifted regions of Southern California.

    Science.gov (United States)

    Lekic, Vedran; French, Scott W; Fischer, Karen M

    2011-11-11

    The stretching and break-up of tectonic plates by rifting control the evolution of continents and oceans, but the processes by which lithosphere deforms and accommodates strain during rifting remain enigmatic. Using scattering of teleseismic shear waves beneath rifted zones and adjacent areas in Southern California, we resolve the lithosphere-asthenosphere boundary and lithospheric thickness variations to directly constrain this deformation. Substantial and laterally abrupt lithospheric thinning beneath rifted regions suggests efficient strain localization. In the Salton Trough, either the mantle lithosphere has experienced more thinning than the crust, or large volumes of new lithosphere have been created. Lack of a systematic offset between surface and deep lithospheric deformation rules out simple shear along throughgoing unidirectional shallow-dipping shear zones, but is consistent with symmetric extension of the lithosphere. PMID:21979933

  13. Volcanic and sedimentary-rock aquifers

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the extent of the Volcanic and sedimentary-rock aquifers in the states of Montana, Wyoming, Idaho, Nevada, California, Oregon, and...

  14. North Atlantic Coastal Plain aquifer system

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the extent of the North Atlantic Coastal Plain aquifer system in North Carolina, Virginia, Maryland, Deleware, and New Jersey.

  15. As contamination in Mercedes (Uruguay) aquifer groundwater

    International Nuclear Information System (INIS)

    The study presents data on the concentration of arsenic in groundwater aquifer Mercedes, where the highest concentration area is located in New Palmira.A geological formation decryption of the Mercedes for the Upper Cretaceous is made.

  16. Hydrogeologic characterization of devonian aquifers in Uruguay

    International Nuclear Information System (INIS)

    This article carried out the assistance research project implementation in devonian sedimentary units as a potentials aquifers and their best use to school supplying and rural population in central area of Uruguay.

  17. Aquifer vulnerability for Colorado and New Mexico

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. Geological Survey Data Series provides raster data representing an estimate of aquifer vulnerability calculated for each 30-meter raster cell. Depth to...

  18. New interpretation of the deep mantle structure beneath eastern China

    Science.gov (United States)

    Ma, Pengfei; Liu, Shaofeng; Lin, Chengfa; Yao, Xiang

    2016-04-01

    Recent study of high resolution seismic tomography presents a large mass of high velocity abnormality beneath eastern China near the phase change depth, expanding more than 1600km-wide in East-west cross-section across the North China plate. This structure high is generally believed to be the subducted slab of Pacific plate beneath the Eurasia continent, while its origin and dynamic effect on the Cenozoic tectonic evolution of eastern China remain to be controversial. We developed a subduction-driven geodynamic mantle convection model that honors a set of global plate reconstruction data since 230Ma to help understand the formation and evolution of mantle structure beneath eastern China. The assimilation of plate kinematics, continuous evolving plate margin, asymmetric subduction zone, and paleo seafloor age data enables the spatial and temporal consistency between the geologic data and the mantle convection model, and guarantees the conservation of the buoyancy flux across the lithosphere and subducted slabs. Our model achieved a first order approximation between predictions and the observed data. Interestingly, the model suggests that the slab material stagnated above discontinuity didn't form until 15Ma, much later than previous expected, and the fast abnormality in the mid-mantle further west in the tomographic image is interpreted to be the remnants of the Mesozoic Izanagi subduction. Moreover, detailed analysis suggests that the accelerated subduction of Philippine Sea plate beneath Eurasia plate along the Ryukyu Trench and Nankai Trough since 15Ma may largely contribute to extending feature above 670km discontinuity. The long distance expansion of the slab material in the East-west direction may be an illusion caused by the approximate spatial perpendicularity between the cross-section and the subduction direction of the Philippine Sea plate. Our model emphasizes the necessity of the re-examination on the geophysical observation and its tectonic and

  19. On Irrotational Flows Beneath Periodic Traveling Equatorial Waves

    Science.gov (United States)

    Quirchmayr, Ronald

    2016-08-01

    We discuss some aspects of the velocity field and particle trajectories beneath periodic traveling equatorial surface waves over a flat bed in a flow with uniform underlying currents. The system under study consists of the governing equations for equatorial ocean waves within a non-inertial frame of reference, where Euler's equation of motion has to be suitably adjusted, in order to account for the influence of the earth's rotation.

  20. Analysis of SKS Phase Regarding Dynamic Structure Beneath Turkey

    International Nuclear Information System (INIS)

    Shear wave splitting parameters were determined by using tele seismic data that recorded by most of all broadband stations in Turkey. Nearly all stations in central and eastern Anatolia have a NE-SW fast direction and delay times indicate that the anisotropic fabric may be relatively uniform throughout the upper mantle beneath the Anatolia block. Also, the results in the western Anatolia showed that the fast polarization direction is parallel to extension direction of the region

  1. Kelvin-Helmholtz wave generation beneath hovercraft skirts

    Science.gov (United States)

    Sullivan, P. A.; Walsh, C.; Hinchey, M. J.

    1993-05-01

    When a hovercraft is hovering over water, the air flow beneath its skirts can interact with the water surface and generate waves. These, in turn, can cause the hovercraft to undergo violent self-excited heave motions. This note shows that the wave generation is due to the classical Kelvin-Helmholtz mechanism where, beyond a certain air flow rate, small waves at the air water interface extract energy from the air stream and grow.

  2. The Dumbarton Oaks Tlazolteotl: looking beneath the surface

    OpenAIRE

    MacLaren Walsh, Jane

    2014-01-01

    The Dumbarton Oaks Tlazolteotl: looking beneath the surface. Some of the earliest and most revered pre-Columbian artifacts in the world’s major museum and private collections were collected prior to the advent of systematic, scientific archaeological excavation, and have little or no reliable provenience data. They have consistently posed problems for researchers due to anomalies of theme, material, size, technical virtuosity and iconography. This paper offers a historical and scientific appr...

  3. Predicting the denitrification capacity of sandy aquifers from shorter-term incubation experiments and sediment properties

    Directory of Open Access Journals (Sweden)

    W. Eschenbach

    2013-02-01

    Full Text Available Knowledge about the spatial variability of denitrification rates and the lifetime of denitrification in nitrate-contaminated aquifers is crucial to predict the development of groundwater quality. Therefore, regression models were derived to estimate the measured cumulative denitrification of aquifer sediments after one year of incubation from initial denitrification rates and several sediment parameters, namely total sulphur, total organic carbon, extractable sulphate, extractable dissolved organic carbon, hot water soluble organic carbon and potassium permanganate labile organic carbon.

    For this purpose, we incubated aquifer material from two sandy Pleistocene aquifers in Northern Germany under anaerobic conditions in the laboratory using the 15N tracer technique. The measured amount of denitrification ranged from 0.19 to 56.2 mg N kg−1 yr−1. The laboratory incubations exhibited high differences between non-sulphidic and sulphidic aquifer material in both aquifers with respect to all investigated sediment parameters. Denitrification rates and the estimated lifetime of denitrification were higher in the sulphidic samples. For these samples, the cumulative denitrification measured during one year of incubation (Dcum(365 exhibited distinct linear regressions with the stock of reduced compounds in the investigated aquifer samples. Dcum(365 was predictable from sediment variables within a range of uncertainty of 0.5 to 2 (calculated Dcum(365/measured Dcum(365 for aquifer material with a Dcum(365 > 20 mg N kg−1 yr−1. Predictions were poor for samples with lower Dcum(365, such as samples from the NO3 bearing groundwater zone, which includes the non-sulphidic samples, from the upper part of both aquifers where denitrification is not sufficient to

  4. Simultaneous Injection of Wastewater and CO2 in a Heterogeneous Aquifer

    Science.gov (United States)

    Okwen, R.; Thomas, M. W.; Stewart, M.; Trotz, M.; Cunningham, J. A.

    2011-12-01

    One of the major obstacles to development, implementation, and deployment of carbon capture and storage(CCS) is cost. As a result, sustainably combining CCS with existing technologies to make CCS less costly or profitable is vital. We propose a CCS strategy in which captured anthropogenic carbon dioxide (CO2) and municipal wastewater are simultaneously injected into a confined saline aquifer. Numerical simulations of simultaneous injection of CO2 and wastewater into a confined saline aquifer were conducted under both isotropic and vertically heterogeneous conditions. The results of the simulations were quantified based on changes in mineral volume fractions and spatial distributions of gas saturation, pH, ionic species concentrations, and pressure, over an injection period of 50 years. Results from the simulation of CO2-wastewater injection (3214 tons/day each) into a carbonate saline aquifer predict very low gas saturations (0.4 maximum after 50 years) and enhancement of dissolved CO2 mass fraction as a result of the dissolution of CO2 into wastewater and resident brine. Transfer of supercritical CO2 to the dissolved phase reduces buoyancy effects and traps CO2 in a more stable phase, increasing storage efficiency. Vertical baffling as a result of vertical heterogeneity also increases sequestration efficiency from about 4% in the homogeneous case to 6% in the vertically heterogeneous case. A simulation of wastewater injection alone into the same saline aquifer predicts near-wellbore scaling from mineral precipitation. However, little or no mineral precipitation is simulated for the CO2-wastewater injection case because the CO2 causes reduction in pH near the wellbore, inhibiting mineral precipitation. These results suggest that co-injection of CO2 and wastewater in deep confined saline aquifers enhances CO2 storage efficiency and security and reduces scaling problems encountered during deep well injection of wastewater.

  5. Geochemical Impacts of Leaking CO2 from Subsurface Storage Reservoirs to Unconfined and Confined Aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Qafoku, Nikolla; Brown, Christopher F.; Wang, Guohui; Sullivan, E. C.; Lawter, Amanda R.; Harvey, Omar R.; Bowden, Mark

    2013-04-15

    Experimental research work has been conducted and is undergoing at Pacific Northwest National Laboratory (PNNL) to address a variety of scientific issues related with the potential leaks of the carbon dioxide (CO2) gas from deep storage reservoirs. The main objectives of this work are as follows: • Develop a systematic understanding of how CO2 leakage is likely to influence pertinent geochemical processes (e.g., dissolution/precipitation, sorption/desorption and redox reactions) in the aquifer sediments. • Identify prevailing environmental conditions that would dictate one geochemical outcome over another. • Gather useful information to support site selection, risk assessment, policy-making, and public education efforts associated with geological carbon sequestration. In this report, we present results from experiments conducted at PNNL to address research issues related to the main objectives of this effort. A series of batch and column experiments and solid phase characterization studies (quantitative x-ray diffraction and wet chemical extractions with a concentrated acid) were conducted with representative rocks and sediments from an unconfined, oxidizing carbonate aquifer, i.e., Edwards aquifer in Texas, and a confined aquifer, i.e., the High Plains aquifer in Kansas. These materials were exposed to a CO2 gas stream simulating CO2 gas leaking scenarios, and changes in aqueous phase pH and chemical composition were measured in liquid and effluent samples collected at pre-determined experimental times. Additional research to be conducted during the current fiscal year will further validate these results and will address other important remaining issues. Results from these experimental efforts will provide valuable insights for the development of site-specific, generation III reduced order models. In addition, results will initially serve as input parameters during model calibration runs and, ultimately, will be used to test model predictive capability and

  6. Improving Aquifer Thermal Energy Storage Efficiency

    OpenAIRE

    S. Kranz; G. Blöcher; Ali Saadat

    2015-01-01

    Aquifer thermal energy storage systems play an important role for the future energy supply systems. Such systems can decouple energy availability (e.g. fluctuating renewable energy, waste heat) and energy supply in times of demand. In order to fully contribute to the sustainability of energy supply, the essential requirements of energy storages are high energy efficiency, high reliability, cost effectiveness, as well as operational flexibility. Aquifer Thermal Energy Storage Systems (ATES) me...

  7. Estimating aquifer thickness using multiple pumping tests

    OpenAIRE

    Maréchal, Jean-Christophe; Vouillamoz, Jean-Michel; Mohan Kumar, M.S.; Dewandel, Benoit

    2010-01-01

    A method to estimate aquifer thickness and hydraulic conductivity has been developed, consisting of multiple pumping tests. The method requires short-duration pumping cycles on an unconfined aquifer with significant seasonal water-table fluctuations. The interpretation of several pumping tests at a site in India under various initial conditions provides information on the change in hydrodynamic parameters in relation to the initial water-table level. The transmissivity linearly decreases comp...

  8. Monitoring induced denitrification in an artificial aquifer recharge system.

    Science.gov (United States)

    Grau-Martinez, Alba; Torrentó, Clara; Folch, Albert; Domènech, Cristina; Otero, Neus; Soler, Albert

    2014-05-01

    As demands on groundwater increase, artificial recharge is becoming a common method for enhancing groundwater supply. The Llobregat River is a strategic water supply resource to the Barcelona metropolitan area (Catalonia, NE Spain). Aquifer overexploitation has leaded to both a decrease of groundwater level and seawater intrusion, with the consequent deterioration of water quality. In the middle section of the aquifer, in Sant Vicenç del Horts, decantation and infiltration ponds recharged by water from the Llobregat River (highly affected from wastewater treatment plant effluents), were installed in 2007, in the framework of the ENSAT Life+ project. At the bottom of the infiltration pond, a vegetal compost layer was installed to promote the growth of bacteria, to induce denitrification and to create favourable conditions for contaminant biodegradation. This layer consists on a mixture of compost, aquifer material, clay and iron oxide. Understanding the fate of contaminants, such as nitrate, during artificial aquifer recharge is required to evaluate the impact of artificial recharge in groundwater quality. In order to distinguish the source of nitrate and to evaluate the capability of the organic reactive layer to induce denitrification, a multi-isotopic approach coupled with hydrogeochemical data was performed. Groundwater samples, as well as river samples, were sampled during artificial and natural recharge periods. The isotopic analysis included: δ15N and δ18O of dissolved nitrate, δ34S and δ18O of dissolved sulphate, δ13C of dissolved inorganic carbon, and δ2H and δ18O of water. Dissolved nitrate isotopic composition (δ15NNO3 from +9 to +21 o and δ18ONO3 from +3 to +16 ) demonstrated that heterotrophic denitrification induced by the reactive layer was taking place during the artificial recharge periods. An approximation to the extent of nitrate attenuation was calculated, showing a range between 95 and 99% or between 35 and 45%, by using the extreme

  9. Why are there few seedlings beneath the myrmecophyte Triplaris americana?

    Science.gov (United States)

    Larrea-Alcázar, Daniel M.; Simonetti, Javier A.

    2007-07-01

    We compared the relative importance of chemical alellopathy, pruning behaviour of resident ants and other non-related agents to ant-plant mutualism for seedling establishment beneath Triplaris americana L. (Polygonaceae), a myrmecophyte plant. We also included a preliminary analysis of effects of fragmentation on these ecological processes. Seeds and seedlings of Theobroma cacao L. (Sterculiaceae) were used as the target species in all experiments. Leaf-tissue extracts of the myrmecophyte plant did not inhibit germination of cacao seeds. Resident Pseudomyrmex triplarinus Weddell (Pseudomyrmecinae) ants did not remove seeds under the canopy of their host plants. The main seed consumer was the leaf-cutting ant Atta sexdens L. (Myrmicinae). Leaves of cacao seedlings were partially or totally pruned by Pseudomyrmex ants mainly in forest fragments studied. We offer evidence pointing to the possibility that the absence of seedlings beneath Triplaris may result from effects of both ant species. We discuss the benefits of pruning behaviour for the resident ant colony and the effects of ant-ant interactions on seedling establishment beneath this ant-plant system.

  10. Flow separation and resuspension beneath shoaling nonlinear internal waves

    Science.gov (United States)

    Boegman, Leon; Ivey, Gregory N.

    2009-02-01

    Laboratory observations are presented showing the structure and dynamics of the turbulent bottom boundary layer beneath nonlinear internal waves (NLIWs) of depression shoaling upon sloping topography. The adverse pressure gradient beneath the shoaling waves causes the rear face to steepen, flow separation to occur, and wave-induced near-bottom vortices to suspend bed material. The resuspension is directly attributed to the near-bed viscous stress and to near-bed patches of elevated positive Reynolds stress generated by the vortical structures. These results are consistent with published field observations of resuspension events beneath shoaling NLIWs. Elevated near-bed viscous stresses are found throughout the domain at locations that are not correlated to the resuspension events. Near-bed viscous stress is thus required for incipient sediment motion but is not necessarily a precursor for resuspension. Resuspension is dependent on the vertical velocity field associated with positive Reynolds stress and is also found to occur where the mean (wave-averaged) vertical velocity is directed away from the bed. The results are interpreted by analogy to the eddy-stress and turbulent bursting resuspension models developed for turbulent channel flows.

  11. Transuranic distribution beneath a retired underground disposal facility, Hanford Site

    International Nuclear Information System (INIS)

    Past liquid waste disposal practices at the Hanford Site included the discharge of solutions containing low-level concentrations of transuranics directly to the ground via structures collectively termed cribs. A study was conducted to determine the present spatial distribution of plutonium and americium beneath the retired 216-Z-1A Crib, which contains one of the highest cumulative plutonium inventories, 57 kilograms. Sixteen shallow wells were drilled in the unsaturated sediments underlying the facility using specialized, totally contained drilling techniques. Samples from each well were analyzed to obtain profiles of both sediment type and plutonium and americium concentrations as a function of depth beneath the facility. The results of the study show that the highest concentration of plutonium (>104 nCi/g of sediment) occurs within the first 3 meters of sediment beneath the central distribution pipe. The high activity at this position is tentatively attributed to the removal of solid particles from the waste stream by sediment filtration. The distributions of plutonium and americium in the sediments are similar. Peak transuranic activity in the sediment profile is generally associated with silt lenses or with major sedimentary unit interfaces (ie, sand to gravel). The maximum vertical extent of transuranic activity found is approximately 30 meters below the bottom of the crib or approximately 25 meters above the regional water table. No contamination greater than the instrumental limit of detection of 10-5 nCi/g of sediment was found from a depth of 30 to 40 meters, the maximum depth of sampling

  12. Convective upwelling in the mantle beneath the Gulf of California.

    Science.gov (United States)

    Wang, Yun; Forsyth, Donald W; Savage, Brian

    2009-11-26

    In the past six million years, Baja California has rifted obliquely apart from North America, opening up the Gulf of California. Between transform faults, seafloor spreading and rifting is well established in several basins. Other than hotspot-dominated Iceland, the Gulf of California is the only part of the world's seafloor-spreading system that has been surrounded by enough seismometers to provide horizontal resolution of upper-mantle structure at a scale of 100 kilometres over a distance great enough to include several spreading segments. Such resolution is needed to address the long-standing debate about the relative importance of dynamic and passive upwelling in the shallow mantle beneath spreading centres. Here we use Rayleigh-wave tomography to image the shear velocity in the upper 200 kilometres or so of the mantle. Low shear velocities similar to those beneath the East Pacific Rise oceanic spreading centre underlie the entire length of the Gulf, but there are three concentrated locations of anomalously low velocities spaced about 250 kilometres apart. These anomalies are 40 to 90 kilometres beneath the surface, at which depths petrological studies indicate that extensive melting of passively upwelling mantle should begin. We interpret these seismic velocity anomalies as indicating that partial melting triggers dynamic upwelling driven by either the buoyancy of retained melt or by the reduced density of depleted mantle. PMID:19940924

  13. Geochemical evolution and time scale of seawater intrusion into the coastal aquifer of Israel

    International Nuclear Information System (INIS)

    The dynamics of seawater intrusion into a coast is commonly estimated by a rise in salinity and/or by theoretical hydrological models. Estimations using radioactive isotopes are reported only in several works. Here we present an attempt to quantify the geochemical processes and the time scale of seawater intrusion into a coastal aquifer from the changes in the major ions composition of the waters and the natural distribution of the cosmogenic isotopes Carbon 14 and tritium. Saline and brackish groundwaters were sampled from observation and pumping wells in the Israeli coastal aquifer. In addition, detailed profiles across the fresh-saline groundwater interface (resolution of 10 cm) were provided using a Multi Layer Sampler (MLS) that was installed three times in this zone. All groundwater samples were analyzed for their chemical composition, stable carbon and oxygen isotopes, Carbon 14 CDIC in the dissolved inorganic carbon) and tritium activity. The coastal rock was analyzed for its chemical contents and stable and radioactive carbon isotope composition of the carbonate and of the organic matter. The chemical and the stable isotope data revealed three distinct water types (end members) that are placed in different zones in the coastal aquifer: 1. Slightly modified Mediterranean seawater with its salinity (SWS); 2. Slightly diluted (with up to 20% fresh groundwater) saline groundwater (SDS); and 3. Fresh groundwater (FGW). The SWS waters show in most cases excess in total alkalinity and DIC and depletion in Carbon 13 and Carbon 14 C with respect to normal seawater, indicating that anaerobic oxidation of organic matter is the first diagenetic reaction that affect seawater during its penetration into the bottom sediments. Later on, the SWS waters dilutes, gain Ca 2+ and Sr 2+ and deplete in K+ suggesting that mixing with fresh water and cation exchange are the main diagenetic processes that transforms SWS into SDS. At the fresh-saline water interface, SDS waters show

  14. Biotite and chlorite weathering at 25 degrees C: the dependence of pH and (bi)carbonate on weathering kinetics, dissolution stoichiometry, and solubility; and the relation to redox conditions in granitic aquifers

    International Nuclear Information System (INIS)

    We have studied the kinetics and thermodynamics of biotite and chlorite weathering in the pH range 22-102 year); and 2. the development of characteristic Fe(III) concentrations (10-5 M in 10-1 years). The Fe(III)-bearing clay minerals formed during these experiments are similar to the fracture-filling-material observed at the Aespoe Hard Rock Laboratory. Such clays can provide reducing capacity to a repository. They can help maintain anoxic conditions by consuming oxygen that enters the repository during the construction and operation phases thereby helping maintain the redox stability of the repository regarding canister corrosion. The half-life of oxygen trapped in the repository at the time of closure depends on the rate of oxygen uptake by Fe(II) minerals, sulfide minerals and organic carbon. Fe(II)-clay minerals are important to the redox stability of a repository, as well as providing a sorption barrier to radionuclide migration. 107 refs, 52 figs, 35 tabs

  15. Localized Corrosion of Zn-Plated Carbon Steel Used as a Fire Sprinkler Pipe

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jin Hee [SK Engineering and Construction Corp., Seoul (Korea, Republic of); Lee, You Kee [Ui duk University, Gyeongju (Korea, Republic of); Lee, Kyu Hwan [Korea Institute of Materials Science, Changwon (Korea, Republic of); Kim, Dong Kyu; Lee, Sung Gun; Lee, Sang Hwa; Kim, In Soo [Dong-A University, Busan (Korea, Republic of)

    2009-08-15

    The failure of a Zn-plated carbon steel pipe that served as a fire sprinkler was investigated in terms of the pope's corrosion products. The pipes leaked through holes formed beneath the tubercles. The formation of oxygen concentration cell involves colonization of metal surface by aerobic bacteria or other slime formers, and anodic reaction beneath tubercle is accelerated by the presence of SRB, leading to the formation of hole beneath tubercle.

  16. Tracing Recharge Sources and Salinization Processes of the Quaternary Aquifer Using Stable Isotopes and Hydrogeochemistry, South of the Ismailia Canal, Egypt

    Science.gov (United States)

    Khalil, M. M. A. M.; Tokunaga, T.

    2014-12-01

    The reclamation policy to alleviate overpopulation problem of the Nile Delta, Egypt, has created both quality and quantity problems for the Quaternary aquifer beneath the reclaimed areas. It is partly because of the less well managed way for land use planning and lack of the environmental impact assessment at least at the early stage of the development. A stable isotopic ( δ 18O and δ 2H) and hydrochemical investigation was carried out in the reclaimed area at the south of the Ismailia Canal to identify recharge sources, and mixing and salinization processes of the Quaternary aquifer. On the basis of the isotopic data, four end-members, i.e., the Quaternary aquifer, the Miocene aquifer, surface freshwater and wastewater ponds were found to be mixed in different degree in the study area. As a consequence of mixing with groundwater in the Miocene aquifer which shows highly saline and depleted isotopic signature, groundwater in the Quaternary aquifer was found to have a depleted isotopic trend towards south, i.e., toward structural highs. On the contrary, northward trends of the enriched isotopic values and lower EC values in the Quaternary aquifer indicated the mixing with surface water. Local abnormal EC values at an agricultural area and the vicinity of well field were considered to be related to the excessive pumping for irrigation and reclamation activities which in turn resulted in upconing of deeper saline groundwater. Mixing pattern also suggested local contribution of the wastewater ponds to the recharge process, which is consistent with the previously reported heavy metal contamination in the vicinity of these ponds, indicating the necessity to protect and remediate the subsurface water resources in the area.

  17. Soil microbial activities beneath Stipa tenacissima L. and in surrounding bare soil

    Science.gov (United States)

    Novosadová, I.; Ruiz Sinoga, J. D.; Záhora, J.; Fišerová, H.

    2010-05-01

    open steppe dominated by Stipa tenacissima. In February 2009 representative soil samples from the top 10 cm were taken beneath grass tussock and from bare soil. Soil samples in three replicates were incubated after rewetting with distilled water (basal microbial activities) and after rewetting with the glucose solution and with the mixture of glucose and peptone solution (potential microbial activities). The CO2, C2H4 evolved under controlled conditions (60% WHC, 24°C) during a 37-day aerobic incubation were determined. Ammonia and nitrate nitrogen were estimated in percolates after simulated rainfall (on the 16th day of incubation) and in the incubated soil samples at the end of incubation. Net ammonification and net nitrification rates were determined by subtracting initial soil mineral N from both mineral N in percolates plus final mineral N contents at 37th day. Basal, potential microbial respiration and net nitrification in the soils beneath S. tenacissima were, in general, not significantly different from the bare soils. The differences between plant-covered soil and bare soil in cumulative values of CO2 production and in amounts of accumulated NO3--N (net nitrification) were less than ± 10%. Greater differences were found in the net ammonification, which were higher beneath S. tenacissima, mainly in the control (basal activities) variant (about 38 %). Significantly less ethylene produced by microbial activity in soils beneath S. tenacissima after the addition of glucose indicates the dependence of rhizospheric microbial communities on available carbon compounds mainly from root exudates. It can be concluded, similarly as published Goberna et al., (2007), that the distribution of soil microbial properties in semi-arid Mediterranean ecosystems is not necessarily associated with the patchy plant distribution and that some microbial activities characteristics can be unexpectedly homogenous.

  18. Isotope contribution to geochemical investigations in aquifer storage and recovery

    International Nuclear Information System (INIS)

    Aquifer Storage and Recovery (ASR) is an important resource management tool. An available water source; such as surface water, seasonal rainfall, or sewage effluent, is stored in a suitable aquifer for reuse when required to balance the seasonal demand for irrigation supply, thus relieving the pressure on groundwater resources. In ASR schemes, geochemical and biogeochemical reactions play an important role, impacting on both the aquifer matrix integrity and the recovered water quality. Understanding the driving processes that trigger these reactions is essential for determining the feasibility of new schemes and to adequately manage operating schemes. However the resulting geochemical signature is often due to a complex suite of reactions that is difficult to unravel. Few studies analyse the potential of isotopic tracers to contribute to the understanding of the biogeochemical reactions induced by ASR. This paper investigates the potential of the stable isotopes of the water molecule, carbon-13 and carbon-14 and sulfur-34 to contribute to our understanding of the geochemical processes involved in reclaimed water ASR. The field trial at Bolivar, South Australia is investigating the viability of reclaimed water i.e. nutrient rich water, as an injectant. The stable isotopes of the water molecule, can be used as conservative tracers to calculate the extent of mixing as the stable isotopic signature of the reclaimed water and the native groundwater of the carbonate aquifer are significantly different. The δ2H and δ18O of native groundwater are fairly constant at -26±1 and -4.4±0.1 per mille vs. SMOW respectively, while the injectant signature is more enriched and more variable, with δ2H ranging from -10.6 to -3.6 per mille and δ18O from -1.74 to -0.21 per mille. The variation in the injectant signature is attributed to seasonal variation in the degree of evaporation occurring in storage lagoons. The seasonal signature variation is maintained as injectant

  19. Investigating the Spatial and Temporal Variability of Water Saturation Within the Greenland Firn Aquifer Using Ground Penetrating Radar

    Science.gov (United States)

    Brautigam, N.

    2015-12-01

    Ground Penetrating Radar (GPR) is used to investigate the spatial and temporal saturation of the Greenland firn aquifer, using a method recently developed on a Svalbard icesheet (Christianson et. al., 2015). Currently, saturation of the firn is assumed to be 100% (Koenig et. al., 2014; Forster et. al., 2014), and using a firn density correction this saturation level drives the present liquid water volume estimate (140±20 Gt) of the Greenland firn aquifer (Koenig et. al., 2014). Based on earlier studies on mountain glacier firn aquifers, we suspect that saturation levels vary with depth, annual precipitation patterns, and local topography (Fountain, 1989; Christianson et. al., 2015). Refining the liquid water volume estimation is an important parameter as it allows for a better determination of the amount of water potentially available for release and consequent sea level rise, as well as to better model glacial processes such as englacial flow, crevasse fracture, and basal lubrication. GPR and GPS data collected along a 2.6 km transect in 2011, 2013, and 2014 in southeastern Greenland is used to measure the spatial and temporal variability of saturation levels within the aquifer. A bright reflector seen in the GPR at the water table depth responds to local topography. At surface lows, the reflector rises, intersecting annual density change layers visible in the GPR data. At these intersections, the annual layers deflect down beneath the water table before being lost due to signal attenuation. We assume that this deflection is due to a change in dielectric permittivity, and that by measuring the angle of deflection, and implementing a mixing model and density correction from nearby firn cores, we can determine the saturation level at each point along a deflection. This allows us to investigate the spatial and temporal variability of saturation within the firn aquifer.

  20. Quantifying the fate of agricultural nitrogen in an unconfined aquifer: Stream-based observations at three measurement scales

    Science.gov (United States)

    Gilmore, Troy E.; Genereux, David P.; Solomon, D. Kip; Solder, John E.; Kimball, Briant A.; Mitasova, Helena; Birgand, François

    2016-03-01

    We compared three stream-based sampling methods to study the fate of nitrate in groundwater in a coastal plain watershed: point measurements beneath the streambed, seepage blankets (novel seepage-meter design), and reach mass-balance. The methods gave similar mean groundwater seepage rates into the stream (0.3-0.6 m/d) during two 3-4 day field campaigns despite an order of magnitude difference in stream discharge between the campaigns. At low flow, estimates of flow-weighted mean nitrate concentrations in groundwater discharge ([NO3-]FWM) and nitrate flux from groundwater to the stream decreased with increasing degree of channel influence and measurement scale, i.e., [NO3-]FWM was 654, 561, and 451 µM for point, blanket, and reach mass-balance sampling, respectively. At high flow the trend was reversed, likely because reach mass-balance captured inputs from shallow transient high-nitrate flow paths while point and blanket measurements did not. Point sampling may be better suited to estimating aquifer discharge of nitrate, while reach mass-balance reflects full nitrate inputs into the channel (which at high flow may be more than aquifer discharge due to transient flow paths, and at low flow may be less than aquifer discharge due to channel-based nitrate removal). Modeling dissolved N2 from streambed samples suggested (1) about half of groundwater nitrate was denitrified prior to discharge from the aquifer, and (2) both extent of denitrification and initial nitrate concentration in groundwater (700-1300 µM) were related to land use, suggesting these forms of streambed sampling for groundwater can reveal watershed spatial relations relevant to nitrate contamination and fate in the aquifer.

  1. Storm pulse chemographs of saturation index and carbon dioxide pressure: implications for shifting recharge sources during storm events in the karst aquifer at Fort Campbell, Kentucky/Tennessee, USA

    Science.gov (United States)

    Vesper, Dorothy J.; White, William B.

    Continuous records of discharge, specific conductance, and temperature were collected through a series of storm pulses on two limestone springs at Fort Campbell, western Kentucky/Tennessee, USA. Water samples, collected at short time intervals across the same storm pulses, were analyzed for calcium, magnesium, bicarbonate, total organic carbon, and pH. Chemographs of calcium, calcite saturation index, and carbon dioxide partial pressure were superimposed on the storm hydrographs. Calcium concentration and specific conductance track together and dip to a minimum either coincident with the peak of the hydrograph or lag slightly behind it. The CO2 pressure continues to rise on the recession limb of the hydrograph and, as a result, the saturation index decreases on the recession limb of the hydrograph. These results are interpreted as being due to dispersed infiltration through CO2-rich soils lagging the arrival of quickflow from sinkhole recharge in the transport of storm flow to the springs. Karst spring hydrographs reflect not only the changing mix of base flow and storm flow but also a shift in source of recharge water over the course of the storm. L'enregistrement en continu du débit, de la conductivité et de la température de l'eau a été réalisé au cours d'une série de crues à deux sources émergeant de calcaires, à Fort Campbell (Kentucky occidental, Tennessee, États-Unis). Des échantillons d'eau, prélevés à de courts pas de temps lors de ces crues, ont été analysés pour le calcium, le magnésium, les bicarbonates, le carbone organique total et le pH. Les chimiogrammes de calcium, d'indice de saturation de la calcite et de la pression partielle en CO2 ont été superposés aux hydrogrammes de crue. La concentration en calcium et la conductivité de l'eau se suivent bien et passent par un minimum correspondant au pic de l'hydrogramme ou légèrement retardé. La pression partielle en CO2 continue de croître au cours de la récession de l

  2. Using 14C and 3H to delineate a recharge ‘window’ into the Perth Basin aquifers, North Gnangara groundwater system, Western Australia

    International Nuclear Information System (INIS)

    The Gnangara Mound and the underlying Perth Basin aquifers are the largest source of groundwater for the southwest of Australia, supplying between 35 and 50% of Perth's potable water (2009–2010). However, declining health of wetlands on the Mound coupled with the reduction in groundwater levels from increased irrigation demands and drier climatic conditions means this resource is experiencing increased pressures. The northern Gnangara is an area where the Yarragadee aquifer occurs at shallow depths (∼ 50 m) and is in direct contact with the superficial aquifer, suggesting the possibility of direct recharge into a generally confined aquifer. Environmental isotopes (14C and 3H) and hydrochemical modelling were used to assess the presence of a recharge ‘window’ as well as understand the groundwater residence time within different aquifers. Forty-nine groundwater samples were collected from depths ranging from 11 to 311 m below ground surface. The isotopic variation observed in the superficial aquifer was found to be controlled by the different lithologies present, i.e. quartz-rich Bassendean Sand and carbonate-rich sediments of the Ascot Formation. Rainfall recharge into the Bassendean Sand inherits its dissolved inorganic carbon from the soil CO2. Organic matter throughout the soil profile is degraded by oxidation leading to anoxic/acidic groundwater, which if in contact with the Ascot Formation leads to enhanced dissolution of carbonates. Hydrochemical mass balance modelling showed that carbonate dissolution could contribute 1–2 mmol kg−1 of carbon to groundwaters recharged through the Ascot Formation. The corrected groundwater residence times of the Yarragadee aquifer in the northern part of the study area ranged from 23 to 35 ka, while waters in the southeastern corner ranged from sub-modern to 2 ka. Groundwater ages increase with distance radiating from the recharge ‘window’. This study delineates a recharge ‘window’ into the commonly presumed

  3. Using {sup 14}C and {sup 3}H to delineate a recharge 'window' into the Perth Basin aquifers, North Gnangara groundwater system, Western Australia

    Energy Technology Data Exchange (ETDEWEB)

    Meredith, Karina, E-mail: kmj@ansto.gov.au [Australian Nuclear Science and Technology Organisation, Institute for Environmental Research, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Cendon, Dioni I. [Australian Nuclear Science and Technology Organisation, Institute for Environmental Research, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Pigois, Jon-Philippe [Department of Water, PO Box K822 Perth WA 6842 (Australia); Hollins, Suzanne; Jacobsen, Geraldine [Australian Nuclear Science and Technology Organisation, Institute for Environmental Research, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia)

    2012-01-01

    The Gnangara Mound and the underlying Perth Basin aquifers are the largest source of groundwater for the southwest of Australia, supplying between 35 and 50% of Perth's potable water (2009-2010). However, declining health of wetlands on the Mound coupled with the reduction in groundwater levels from increased irrigation demands and drier climatic conditions means this resource is experiencing increased pressures. The northern Gnangara is an area where the Yarragadee aquifer occurs at shallow depths ({approx} 50 m) and is in direct contact with the superficial aquifer, suggesting the possibility of direct recharge into a generally confined aquifer. Environmental isotopes ({sup 14}C and {sup 3}H) and hydrochemical modelling were used to assess the presence of a recharge 'window' as well as understand the groundwater residence time within different aquifers. Forty-nine groundwater samples were collected from depths ranging from 11 to 311 m below ground surface. The isotopic variation observed in the superficial aquifer was found to be controlled by the different lithologies present, i.e. quartz-rich Bassendean Sand and carbonate-rich sediments of the Ascot Formation. Rainfall recharge into the Bassendean Sand inherits its dissolved inorganic carbon from the soil CO{sub 2}. Organic matter throughout the soil profile is degraded by oxidation leading to anoxic/acidic groundwater, which if in contact with the Ascot Formation leads to enhanced dissolution of carbonates. Hydrochemical mass balance modelling showed that carbonate dissolution could contribute 1-2 mmol kg{sup -1} of carbon to groundwaters recharged through the Ascot Formation. The corrected groundwater residence times of the Yarragadee aquifer in the northern part of the study area ranged from 23 to 35 ka, while waters in the southeastern corner ranged from sub-modern to 2 ka. Groundwater ages increase with distance radiating from the recharge 'window'. This study delineates a recharge

  4. Aquifer Storage Recovery (ASR) of chlorinated municipal drinking water in a confined aquifer

    Science.gov (United States)

    Izbicki, John A.; Petersen, Christen E.; Glotzbach, Kenneth J.; Metzger, Loren F.; Christensen, Allen H.; Smith, Gregory A.; O'Leary, David R.; Fram, Miranda S.; Joseph, Trevor; Shannon, Heather

    2010-01-01

    About 1.02 x 106 m3 of chlorinated municipal drinking water was injected into a confined aquifer, 94-137 m below Roseville, California, between December 2005 and April 2006. The water was stored in the aquifer for 438 days, and 2.64 x 106 m3 of water were extracted between July 2007 and February 2008. On the basis of Cl data, 35% of the injected water was recovered and 65% of the injected water and associated disinfection by-products (DBPs) remained in the aquifer at the end of extraction. About 46.3 kg of total trihalomethanes (TTHM) entered the aquifer with the injected water and 37.6 kg of TTHM were extracted. As much as 44 kg of TTHMs remained in the aquifer at the end of extraction because of incomplete recovery of injected water and formation of THMs within the aquifer by reactions with freechlorine in the injected water. Well-bore velocity log data collected from the Aquifer Storage Recovery (ASR) well show as much as 60% of the injected water entered the aquifer through a 9 m thick, high-permeability layer within the confined aquifer near the top of the screened interval. Model simulations of ground-water flow near the ASR well indicate that (1) aquifer heterogeneity allowed injected water to move rapidly through the aquifer to nearby monitoring wells, (2) aquifer heterogeneity caused injected water to move further than expected assuming uniform aquifer properties, and (3) physical clogging of high-permeability layers is the probable cause for the observed change in the distribution of borehole flow. Aquifer heterogeneity also enhanced mixing of native anoxic ground water with oxic injected water, promoting removal of THMs primarily through sorption. A 3 to 4-fold reduction in TTHM concentrations was observed in the furthest monitoring well 427 m downgradient from the ASR well, and similar magnitude reductions were observed in depth-dependent water samples collected from the upper part of the screened interval in the ASR well near the end of the extraction

  5. Water quality and chemical evolution of ground water within the north coast limestone aquifers of Puerto Rico

    Science.gov (United States)

    Roman-Mas, Angel J.; Lee, Roger W.

    1985-01-01

    Waters within the north coastal limestoneaquifers are suitable for public supply, industrial and agricultural uses. For the artesian aquifer and the updip parts of the watertable aquifer, calcium and bicarbonate are the dominant ionic species with total dissolved solids and chloride concentrations below 500 and 250 mg/L, respectively. In coastal areas of thewater table aquifer, where a freshwater-saltwater mixing zone occurs, the calcium bicarbonate facie grade to a sodium-chloride facie. Within this zone, concentrations of total dissolved solids and chloride are greater than 250 and 500 mg/L respectively, affecting the suitability of the water for some uses. Geochemical models were constructed to determine the physical and chemicalreasons for the prevailing water quality patterns of the north coastlimestone aquifers. Models indicate that calcite and carbon dioxide dissolution, precipitation or degassing are the primary processes. The mixing of recharge water or saltwater with aquifer waters is an important feature within the water table aquifer. The models provide further evidence that support the circulation of groundwater within the north coast limestone.

  6. Fast-track aquifer characterization and bioremediation of groundwater

    International Nuclear Information System (INIS)

    A short duration step-drawdown pumping test has been used to characterize a highly permeable aquifer contaminated with petroleum hydrocarbons in support of an in situ, closed loop extraction and reinjection bioremediation system for groundwater. The short-term pumping test produces a manageable quantity of contaminated groundwater while yielding a range of values for transmissivity and specific yield parameters. This range of aquifer coefficients is used in an analytical model to estimate a range of groundwater extraction rates that provide a suitable radius of influence for the extraction and reinjection system. A multi-enzyme complex catalyzed bioremediation process has been used to aerobically degrade petroleum hydrocarbons. Enzymes, amino acids, and biosurfactants are supplied to the extracted groundwater to significantly speed up the degradation by naturally occurring bacteria. During the process, amino acids promote the rapid growth of the microbial population while enzymes and bacteria attach to hydrocarbons forming a transformation state complex that degrades to fatty acids, carbon dioxide, and water. This paper presents a case study of a fast-track bioremediation using pumping test data, analytical modeling, and an enzyme technology

  7. Basement Aquifers : How Useful Are Gravity Data ?

    Science.gov (United States)

    Genthon, P.; Mouhouyouddine, A. H.; Hinderer, J.; Hector, B.; Yameogo, S.

    2014-12-01

    Gravity data with a few microgal precision were proved to be able to constrain the specific yield of various kinds of aquifer in West Africa from annual fluctuations of both the gravimetric and piezometric signals (Pfeffer et al., Geophys. J. Int., 2011; Hector et al., Geophys. J. Int., 2013). However some recent papers reported a disappointing potential of gravity measurements during a pumping experiment in a sandy aquifer (Blainey et al., WRR, 2007; Herckenrath et al., WRR, 2012) and their poor ability in constraining the transmissity and specific yield of the aquifer, which are the parameters to which pumping tests give access. Fresh basement rocks present generally a null porosity and the structure of basement aquifers is given by the weathering profile. In tropical climate, this profile consists of a few tens meter thick saprolite layer, with noticeable porosity but low permeability overlying the weathering front. This weathering front includes in many instances a fractured medium and presents a high permeability with variable porosity. It is hardly sampled in coring experiments. We present some numerical simulation results on the ability of gravity to constrain the transmissivity of this medium. Due to poroelasticity of clay minerals in the saprolite, soil subsidence is expected to occur during pumping with a significant gravity effect. Gravity measurements have therefore to be completed with leveling data at a millimetric precision. We present first the results of numerical modeling of the gravity and subsidence for a theoretical horizontally stratified basement aquifer, and show that gravity and leveling are able to provide independently the poroelasticity coefficient and a single transmissivity coefficient for the bottom of the aquifer, if the properties of the upper saprolites are known. We will discuss then the general case, where the aquifer presents a vertical fracture where the weathering profile thickens.

  8. Multidepth pumping tests in deep aquifers.

    Science.gov (United States)

    Alam, N; Olsthoorn, T N

    2014-09-01

    Multidepth pumping tests (MDPTs), in which different sections of a screen are pumped in sequence, are not being used by hydrogeologists, despite the capability of such tests to resolve uncertainties in the estimation of aquifer characteristics. MDPTs can be used to discern the effects of partial penetration and vertical anisotropy. This article demonstrates the use of MDPTs for a deep and vertically anisotropic aquifer, based on a real and unique series of pumping tests conducted in the Indus Basin. Traditional single-layer methods, which incorporate partial penetration and vertical scaling, were employed to evaluate these tests. However, the drawdowns of the 19 piezometers at different depths for which times series data were available could not be matched, presumably because of the layered structure of the aquifer. Numerical (MODFLOW) and multilayer analytical (Hemker and Maas 1987; Hemker 1999) approaches were used to assess the benefits of using MDPTs in the analysis of deep layered and anisotropic aquifers. The multilayer analytical solution results are consistent with the measured and numerically computed drawdowns. The original step-drawdown data were used to verify the model independently. The results of statistical analyses indicate that the parameters for a three-layer system are uniquely estimated. A sensitivity analysis showed that aquifer depths greater than 900 m do not affect the drawdown. The multilayer analytical solution was implemented in MATLAB and can be found in the online version of this article. This multilayer analytical approach was implemented in MLU by Hemker and Randall (2013) for up to 40 layers. The results of this study will be useful in groundwater management, exploration, and optimal well depth estimation for the Indus Basin aquifer and other vertically heterogeneous aquifers. PMID:24428328

  9. Insights from the salinity origins and interconnections of aquifers in a regional scale sedimentary aquifer system (Adour-Garonne district, SW France): Contributions of δ34S and δ18O from dissolved sulfates and the 87Sr/86Sr ratio

    International Nuclear Information System (INIS)

    Highlights: • Regional sedimentary aquifer on the Aquitaine Basin (SW France). • Dealing with limited number of groundwater wells available. • Strong control of evaporite dissolution on groundwater dissolved elements. • Guidelines for decision-makers to manage water resources. - Abstract: The multi-layered Eocene aquifer is a regional scale sedimentary aquifer system occupying ∼120,000 km2 within the Adour-Garonne district (France). Local authorities have recently identified the aquifer as being at risk from extensive irrigation abstractions, threatening the sustainability of this key resource. Because large water abstractions for human activities can significantly influence the natural functioning of such aquifer systems, e.g., with leakage between aquifer layers, which can lead to water quality degradation, the characterization of such large systems constitutes a key point to protect and prevent further deterioration of aquatic ecosystems. This study provides further insight on this large aquifer through a geochemical approach, which addresses the limited number of groundwater wells where sampling is possible. For that purpose, a geochemical analysis combining two isotope systems (δ34SSO4, δ18OSO4 and 87Sr/86Sr) has been applied. The Eocene sedimentary aquifer system (detrital to carbonate deposits) is made up of four aquifer layers, Eocene Infra-Molassic sand, Early Eocene, Middle Eocene and Late Eocene, and has a mineralized area north of the Aquitaine Basin, where groundwater shows strong mineralization and anomalous levels of critical substances (SO4, F, etc.), increasing the difficulty of resource exploitation. The extreme heterogeneity of the geochemical composition of the groundwater between the aquifers and within a single aquifer is discussed in terms of the lithological control induced by the lateral variation of facies and interconnections between aquifer layers. Geochemical tools, especially the δ34S and δ18O from dissolved sulfates and

  10. Estimating annual effective infiltration coefficient and groundwater recharge for karst aquifers of the southern Apennines

    Directory of Open Access Journals (Sweden)

    V. Allocca

    2013-08-01

    Full Text Available To assess the mean annual groundwater recharge of the karst aquifers in southern Apennines (Italy, the estimation of the mean annual effective infiltration coefficient (AEIC was conducted by means of an integrated approach based on hydrogeological, hydrological, geomorphological, land use and soil cover analyses. We studied a large part of the southern Apennines that is covered by a meteorological network and containing 40 principal karst aquifers. Using precipitation and air temperature time series gathered through monitoring stations operating in the period 1926–2012, the annual effective precipitation (AEP was estimated, and its distribution was modelled, by considering the orographic barrier and rain shadow effects of the Apennines chain, as well as the altitudinal control. Four sample karst aquifers with available long spring discharge time series were identified for estimating the AEIC by means of the hydrological budget equation. The resulting AEIC values were correlated with other parameters that control groundwater recharge, such as the extension of outcropping karst-rock, morphological settings, land use and covering soil type. A simple correlation relationship between AEIC, lithology and the summit flat and endorheic areas was found. This empirical model has been used to estimate AEIC and mean annual groundwater recharge in other regional karst aquifers. The estimated AEIC values ranged between 48% and 78%, thus matching intervals estimated for other karst aquifers in European and Mediterranean countries. These results represent a deeper understanding of an aspect of groundwater hydrology in karst aquifers which is fundamental for the formulation of appropriate management models of groundwater resources, also taking into account mitigation strategies for climate change impacts. Finally, the proposed hydrological characterisations are also perceived as useful for the assessment of mean annual runoff over carbonate mountains, which is

  11. Estimating annual effective infiltration coefficient and groundwater recharge for karst aquifers of the southern Apennines

    Science.gov (United States)

    Allocca, V.; Manna, F.; De Vita, P.

    2013-08-01

    To assess the mean annual groundwater recharge of the karst aquifers in southern Apennines (Italy), the estimation of the mean annual effective infiltration coefficient (AEIC) was conducted by means of an integrated approach based on hydrogeological, hydrological, geomorphological, land use and soil cover analyses. We studied a large part of the southern Apennines that is covered by a meteorological network and containing 40 principal karst aquifers. Using precipitation and air temperature time series gathered through monitoring stations operating in the period 1926-2012, the annual effective precipitation (AEP) was estimated, and its distribution was modelled, by considering the orographic barrier and rain shadow effects of the Apennines chain, as well as the altitudinal control. Four sample karst aquifers with available long spring discharge time series were identified for estimating the AEIC by means of the hydrological budget equation. The resulting AEIC values were correlated with other parameters that control groundwater recharge, such as the extension of outcropping karst-rock, morphological settings, land use and covering soil type. A simple correlation relationship between AEIC, lithology and the summit flat and endorheic areas was found. This empirical model has been used to estimate AEIC and mean annual groundwater recharge in other regional karst aquifers. The estimated AEIC values ranged between 48% and 78%, thus matching intervals estimated for other karst aquifers in European and Mediterranean countries. These results represent a deeper understanding of an aspect of groundwater hydrology in karst aquifers which is fundamental for the formulation of appropriate management models of groundwater resources, also taking into account mitigation strategies for climate change impacts. Finally, the proposed hydrological characterisations are also perceived as useful for the assessment of mean annual runoff over carbonate mountains, which is another important

  12. Predicting long-term denitrification capacity of sandy aquifers from incubation experiments and sediment properties

    Directory of Open Access Journals (Sweden)

    W. Eschenbach

    2012-07-01

    Full Text Available Knowledge about the spatial variability of denitrification rates and the lifetime of denitrification in nitrate-contaminated aquifers is crucial to predict the development of groundwater quality. Therefore, regression models were derived to estimate the measured denitrification capacity of incubated aquifer sediments from initial denitrification rates and several sediment parameters, namely total sulphur, total organic carbon, extractable sulfate, extractable dissolved organic carbon, hot water soluble organic carbon and potassium permanganate labile organic carbon.

    For this purpose, we incubated aquifer material from two sandy Pleistocene aquifers in Northern Germany under anaerobic conditions in the laboratory using the 15N tracer technique. The measured long-term denitrification capacities ranged from 0.18 to 56.2 mg N kg−1 yr−1. The laboratory incubations exhibited high differences between non-sulphidic and sulphidic aquifer material in both aquifers with respect to all investigated sediment parameters. Denitrification rates and the estimated lifetime of denitrification were higher in the sulphidic samples. Denitrification capacity measured during one year of incubation (Dcap was predictable from sediment variables within a range of uncertainty of 0.5 to 2 (calculated Dcap/measured Dcap for aquifer material with a Dcap > 20 mg N kg−1 yr−1. Predictions were poor for samples with lower Dcap like samples from the NO3-bearing groundwater zone, which includes the non-sulphidic samples, from the upper part of both aquifers where Dcap is not sufficient to protect groundwater from anthropogenic NO3 input. Calculation of Dcap from initial denitrification rates was only successful for samples from the NO

  13. Simulation of flow in the Edwards Aquifer, San Antonio region, Texas, and refinement of storage and flow concepts

    Science.gov (United States)

    Maclay, R.W.; Land, L.F.

    1987-01-01

    The Edwards aquifer is a complexly faulted, carbonate aquifer lying within the Balcones fault zone of south-central Texas. The aquifer is recharged mainly by streamflow losses in the outcrop area of the Edwards aquifer and is discharged by major springs located at considerable distances, as much as 150 mi, from the areas of recharge, and by wells. Groundwater flow within the Edwards aquifer of the San Antonio region was simulated to investigate concepts relating to the storage and flow characteristics. A general purpose, finite difference model, modified to provide the capability of representing barrier faults, was used to simulate groundwater flow and storage in the aquifer. The simulations investigated the effects of complex geologic structures and significant changes in transmissivity, anisotropy, and storage coefficient, with initial values based on concepts developed in previous studies. Results of the simulations confirmed the original estimates of transmissivity values (> 100 sq ft/sec) in the confined zone of the aquifer between San Antonio and Comal Springs. A storage coefficient of 0.05 in the unconfined zone of the aquifer produced the best simulation of water levels and springflow. A major interpretation resulting from the simulations is that two essentially independent areas of regional flow were identified in the west and central part of the study area. Flow from the two areas converges at Comal Springs. The directions of computed flux vectors reflected the presence of major barrier faults which locally deflect patterns of groundwater movement. The most noticeable deflection is the convergence of flow through the geologic structural opening, the Knippa gap, in eastern Uvalde County. A second significant interpretation is that groundwater flow in northeastern Bexar, Comal, and Hays Counties is diverted by barrier faults toward San Marcos Springs, a regional discharge point. (Lantz-PTT)

  14. Hydrogeology, digital solute-transport simulation, and geochemistry of the Lower Cretaceous aquifer system near Baltimore, Maryland

    Science.gov (United States)

    Chapelle, Francis H.; with a section compiled by Kean, Tracey M.

    1985-01-01

    aquifer has a smaller zone of brackish-water contamination that has decreased in size since 1945. Borehole data demonstrate that the Arundel Formation has been breached by Pleistocene river channels near the Harbor district. These erosional channels provide a conduit for brackish water to intrude into the Patuxent aquifer. A two-dimensional areal solute-transport model of the Patuxent aquifer was constructed. This model was designed to estimate the future movement of the brackish-water plume based on alternative scenarios of aquifer use. Model simulations suggest that the plume will remain relatively immobile if 1982 pumping patterns continue into the foreseeable future. However, increased pumpage in the Marley Neck peninsula could draw the plume to the southeast and increase contamination of the Fairfield area. The water quality of the Patuxent aquifer is extremely variable. Because of this variability, it is useful to divide the aquifer into three water-quality zones: Zone 1 -- This zone corresponds to the plume of brackish-water contamination. Zone 2 -- This zone exhibits evidence of urbanization-related contamination such as measurable concentrations of organic chemicals and elevated concentrations of trace elements and total organic carbon. Zone 3 -- Water composition in this zone is controlled exclusively by naturally occurring chemical processes. These processes are dominated by reactions involving dissolved iron. Near the outcrop area, oxidation of pyrite and lignite consumes dissolved oxygen and produces ledges of iron hydroxide-cemented sandstones and conglomerates. The predominant dissolved iron species in oxic water is Fe(OH)2+. Downgradient, the water becomes anoxic and sulfate reduction becomes an important process. The predominant dissolved iron species in anoxic water is Fe2+.

  15. Effect of preozonation on wastewater reclamation by the combination of ozonation and soil aquifer treatment

    OpenAIRE

    Echigo, S.; Nakatsuji, M.; Takabe, Y.; Itoh, S.

    2015-01-01

    A series of column experiments and risk evaluation showed that preozonation was a better option to enhance the performance of soil aquifer treatment (SAT) than ozonation after SAT with respect to dissolved organic carbon, trace organic contaminants, and disinfection byproducts. This is a good example to show that upgrading pretreatments can be more effective than adding extra treatments after SAT, and that it is important to optimize a water reclamation system as a whole system.

  16. Borehole seismic monitoring of CO2 storage within a saline aquifer at Ketzin, Germany

    OpenAIRE

    Götz, Julia

    2014-01-01

    Die vorliegende Dissertation befasst sich mit der Überwachung von CO2-Speicherung in einem salinen Aquifer bei Ketzin, Deutschland, mittels bohrlochseismischer Methoden. CO2-Speicherung ist Teil des Prozesses "CO2-Abscheidung, Transport und Speicherung" (englisch CCS - Carbon Dioxide Capture and Storage). Als Treibhausgas trägt CO2 zur globalen Erwärmung bei, weshalb es notwendig ist, den Anstieg der CO2-Konzentration in der Atmosphäre zu verlangsamen. CCS wird erforscht, da fossile Energietr...

  17. CO2 reactive transport simulations in an Italian deep saline aquifer

    OpenAIRE

    Cantucci, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Montegrossi, G.; CNR-IGG Firenze; Lucci, F.; Roma Tre University; Buttinelli, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Vaselli, O.; Deprtment of earth science; Quattrocchi, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia

    2009-01-01

    In this study numerical simulations of reactive transport in an off-shore deep saline aquifer for the geological sequestration of carbon dioxide are presented and discussed. The main goals are to assess: i) the CO2 injection impact in the reservoir and ii) the cap-rock stability, both being strategic requisites for feasibility studies that are about to be started in Italy. The stratigraphic succession is characterized by a sedimentary succession: from Triassic anhydrites to Jurassic Tuscan...

  18. Percolation and Particle Transport in the Unsaturated Zone of a Karst Aquifer

    OpenAIRE

    Pronk, Michiel; Goldscheider, Nicola; ZOPFI, JAKOB; Zwahlen, François

    2009-01-01

    Recharge and contamination of karst aquifers often occur via the unsaturated zone, but the functioning of this zone has not yet been fully understood. Therefore, irrigation and tracer experiments, along with monitoring of rainfall events, were used to examine water percolation and the transport of solutes, particles, and fecal bacteria between the land surface and a water outlet into a shallow cave. Monitored parameters included discharge, electrical conductivity, temperature, organic carbon,...

  19. Innovative reactive layer to enhance soil aquifer treatment: successful installation in the Llobregat aquifer (Catalonia, ne Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, M.; Gilbert, O.; Bernat, X.; Valhondo, C.; Kock-Schulmeyer, M.; Huerta-Fontela, M.; Colomer, M. V.

    2014-10-01

    The Life+ ENSAT project has demonstrated the effectiveness of a reactive organic layer on the improvement of recharge water quality in an aquifer recharge system. The vegetal compost layer was installed at the bottom of an existing infiltration pond in the Llobregat Lower Valley (Barcelona region) with the purpose of promoting biodegradation and improving the removal emerging micro-pollutants from Llobregat River water. A comprehensive monitoring of water quality including bulk chemistry, emerging micro-pollutants and priority substances indicated that hydro biochemical changes within the organic layer enhance denitrification processes and reduce the levels of gemfibrozil and carbamazepine TP. This effect is due to the release of dissolved organic carbon which promotes biodegradation processes at local scale in the unsaturated zones, without affecting the furthest piezometers. The reactive layer is still active more than 3 years after its installation. The economic assessment of this innovative reactive layer shows that it is a promising solution for the improvement of aquifer recharge with low quality waters, not only technically but also from the economic sustainability standpoint. (Author)

  20. Innovative reactive layer to enhance soil aquifer treatment: successful installation in the Llobregat aquifer (Catalonia, ne Spain)

    International Nuclear Information System (INIS)

    The Life+ ENSAT project has demonstrated the effectiveness of a reactive organic layer on the improvement of recharge water quality in an aquifer recharge system. The vegetal compost layer was installed at the bottom of an existing infiltration pond in the Llobregat Lower Valley (Barcelona region) with the purpose of promoting biodegradation and improving the removal emerging micro-pollutants from Llobregat River water. A comprehensive monitoring of water quality including bulk chemistry, emerging micro-pollutants and priority substances indicated that hydro biochemical changes within the organic layer enhance denitrification processes and reduce the levels of gemfibrozil and carbamazepine TP. This effect is due to the release of dissolved organic carbon which promotes biodegradation processes at local scale in the unsaturated zones, without affecting the furthest piezometers. The reactive layer is still active more than 3 years after its installation. The economic assessment of this innovative reactive layer shows that it is a promising solution for the improvement of aquifer recharge with low quality waters, not only technically but also from the economic sustainability standpoint. (Author)

  1. Evaluation of Main Compositions of Water Chemistry Data By Graphical Methods, Edremit (Balikesir) Alluvial Aquifer System

    Science.gov (United States)

    Ertekin, Can; Sedat Çetiner, Ziya

    2015-04-01

    This case study aims to characterize and compare hydrogeochemistry based on major ion composition belonging to the year of 1970's, 2007 and 2008 for Edremit alluvial aquifer system which lies on the northwestern coast of Anatolia. Graphical representations including Piper, Schoeller, Stiff and Durov diagrams are applied to ease a systematic interpretation of a wide range of well chemistry data sets. In Piper diagram, water types of the aquifer system are mainly dominated with calcium, carbonate-bicarbonate and sulphate ions. Water types of the site are separated as sulphate or carbonate-bicarbonate ion dominated zones for 1970's data. Comparing data of 1970's, 2007 and 2008 the newest data set is clustered into magnesium dominate zone. This is related to relatively deep groundwater chemistry affect probably resulting from long term groundwater withdrawal for irrigation in the aquifer system. The Schoeller diagram portrays differences of the data set of 1970's, 2007 and 2008 more clearly comparing the Piper diagram. In this diagram, higher portions of magnesium and sulphate composition of the well data belonging to the year of 2007 and 2008 are possibly related to deep routes of groundwater flow paths of the site and/or geothermal water mixing. In Durov diagram, the data set was projected to a rectangular shape and it was not immediately clear to differentiate ionic composition of the water. This is not coincidence because the fact that pH values do not change significantly over the years and its contribution is not substantial comparing to major ion chemistry. Finally, application of hydrogeochemical modeling as a further step was touched upon herein to further depict undergone processes and end-members in the whole aquifer system on Edremit Plain. Keywords: Edremit, groundwater, aquifer, hydrogeochemistry, facies

  2. Deconstructing nitrate isotope dynamics in aquifers

    Science.gov (United States)

    Granger, J.

    2012-12-01

    The natural abundance N and O stable isotope ratios of nitrate provide an invaluable tool to differentiate N sources to the environment, track their dispersal, and monitor their attenuation by biological transformations. The interpretation of patterns in isotope abundances relies on knowledge of the isotope ratios of the source end-members, as well as on constraints on the isotope discrimination imposed on nitrate by respective biological processes. Emergent observations from mono-culture experiments of denitrifying bacteria reveal nitrate fractionation trends that appear at odds with trends ascribed to denitrification in soils and aquifers. This discrepancy raises the possibility that additional biological N transformations may be acting in tandem with denitrification. Here, the N and O isotope enrichments associated with nitrate removal by denitrification in aquifers are posited to bear evidence of coincident biological nitrate production - from nitrification and/or from anammox. Simulations are presented from a simple time-dependent one-box model of a groundwater mass ageing that is subject to net nitrate loss by denitrification with coincident nitrate production by nitrification or anammox. Within boundary conditions characteristic of freshwater aquifers, the apparent slope of the parallel enrichments in nitrate N and O isotopes associated with net N loss to denitrification can vary in proportion to the nitrate added simultaneous by oxidative processes. Pertinent observations from nitrate plumes in suboxic to anoxic aquifers are examined to validate this premise. In this perspective, nitrate isotope distributions suggest that we may be missing important N fluxes inherent to most aquifers.

  3. Three-dimensional attenuation structure beneath North Island, New Zealand

    Science.gov (United States)

    Satake, Kenji; Hashida, Toshihiko

    1989-03-01

    Three-dimensional attenuation structure beneath North Island, New Zealand is determined by inversion of seismic intensity data. The method developed by Hashida and Shimazaki is used; the seismic intensity is converted to the maximum acceleration of the S-wave to obtain the acceleration at a point source and the attenuation structure. Because seismic intensity data have been accumulated on a uniform scale in New Zealand since the 1950's, we were able to use more than 2000 seismic intensity data from 26 earthquakes. The results show a remarkable contrast in the attenuation structure. In the top crustal layer, a low-Q area corresponding to the Central Volcanic Region is found. This low-Q area becomes wider to the northeast of North Island, suggesting that the Central Volcanic Region continues to the Havre Trough, a young back-arc basin. The southeastern part of the upper mantle beneath North Island shows high Q while the northwestern part shows low Q. The cross section shows that the high-Q region is dipping to the northwest, with a large amount of dip in the northeast and a smaller dip in the southwestern part of North Island. A comparison of the attenuation structure with microearthquake distribution indicates that this high-Q zone is the obliquely subducting Pacific plate. A zone of abnormally low Q which has cut the high-Q slab is found at a depth range of 130 to 230 km beneath the active volcanoes in the Taupo Volcanic Zone. A tear in the Pacific plate is suggested by this discontinuity in the attenuation structure. (1984).

  4. Evidence for dike emplacement beneath Iliamna Volcano, Alaska in 1996

    Science.gov (United States)

    Roman, D.C.; Power, J.A.; Moran, S.C.; Cashman, K.V.; Doukas, M.P.; Neal, C.A.; Gerlach, T.M.

    2004-01-01

    Two earthquake swarms, comprising 88 and 2833 locatable events, occurred beneath Iliamna Volcano, Alaska, in May and August of 1996. Swarm earthquakes ranged in magnitude from -0.9 to 3.3. Increases in SO2 and CO2 emissions detected during the fall of 1996 were coincident with the second swarm. No other physical changes were observed in or around the volcano during this time period. No eruption occurred, and seismicity and measured gas emissions have remained at background levels since mid-1997. Earthquake hypocenters recorded during the swarms form a cluster in a previously aseismic volume of crust located to the south of Iliamna's summit at a depth of -1 to 4 km below sea level. This cluster is elongated to the NNW-SSE, parallel to the trend of the summit and southern vents at Iliamna and to the regional axis of maximum compressive stress determined through inversion of fault-plane solutions for regional earthquakes. Fault-plane solutions calculated for 24 swarm earthquakes located at the top of the new cluster suggest a heterogeneous stress field acting during the second swarm, characterized by normal faulting and strike-slip faulting with p-axes parallel to the axis of regional maximum compressive stress. The increase in earthquake rates, the appearance of a new seismic volume, and the elevated gas emissions at Iliamna Volcano indicate that new magma intruded beneath the volcano in 1996. The elongation of the 1996-1997 earthquake cluster parallel to the direction of regional maximum compressive stress and the accelerated occurrence of both normal and strike-slip faulting in a small volume of crust at the top of the new seismic volume may be explained by the emplacement and inflation of a subvertical planar dike beneath the summit of Iliamna and its southern satellite vents. ?? 2003 Elsevier B.V. All rights reserved.

  5. Seismic Velocity Anomalies beneath Tatun Volcano Group, Northern Taiwan

    Science.gov (United States)

    Lin, Tzu-yu; Lin, Cheng-Horng; Yang, Tsanyao Frank; Chang, Li-Chin

    2015-04-01

    Volcanic eruption has been a natural disaster for human society. Taiwan is located in the Pacific Ring of Fire. Although there is no obvious phenomenon of volcanic activity in Taiwan, some volcanoes need to be monitored, especially the Tatun Volcano Group (TVG), which exhibits very active hydrothermal activity, is located on the tip of southwestern Ryukyu arc. TVG is about 15 km north to Taipei, capital of Taiwan, and is nearby two nuclear power plants along the northern coast of Taiwan. If TVG erupts, there must be a serious impact and damage to Taiwan. Since TVG is located within the Yangmingshan National Park, any artificial seismic source is not allowed to estimate possible eruption site and the degree of volcanic disaster. Instead, we use natural seismic waves generated by earthquakes to image the possible velocity anomaly of magma chamber and/or hydrothermal system beneath TVG. We systematically compare the differences of arrival times generated by some local earthquakes and recorded at 42 seismic stations in 2014 for finding any low-velocity zone within the crust. The results show that the arrival times always appeared significant delay at some particular seismic stations, such as Chi-Hsin-Shan (CHS), Siao-You-Keng (SYK) and some other stations at TVG, no matter where the earthquakes occurred. It implies that possible low-velocity zones, which could be the location of magma chamber and/or active hydrothermal system, exist beneath the CHS and SYK areas. This feature is generally consistent with the clustered micro-earthquakes in the shallow crust beneath the CHS area in the last decade.

  6. A magmatic probe of dynamic topography beneath western North America

    Science.gov (United States)

    Klöcking, M.; White, N. J.; Maclennan, J.

    2014-12-01

    A region centered on the Yellowstone hotspot and encompassing the Colorado Plateau sits at an elevation 2 km higher than the cratonic North America. This difference broadly coincides with tomographically observed variations in lithospheric thickness: ~120 km beneath western North America, ~240 km beneath the craton. Thermochronology of the Grand Canyon area, sedimentary flux to the Gulf of Mexico, and river profile inversion all suggest that regional uplift occurred in at least two separate stages. High resolution seismic tomographic models, using USArray data, have identified a ring of low velocity material beneath the edges of the Colorado Plateau. Magmatism coincides with these low velocity zones and shows distinct phases: an overall increase in volume around 40 Ma and a change from lithospheric to asthenospheric signatures around 5 Ma. Volcanism is also observed to migrate north-east with time. Here, we attempt to integrate these different observations with lithospheric thickness. A dynamic topography model of progressive lithospheric erosion over a hot mantle plume might account for uplift as well as the temporal and spatial distribution of magmatism across western North America. Thinning of the lithosphere around the edges of the Colorado Plateau in combination with the hotter mantle potential temperature of a plume could create isostatic and dynamic uplift as well as allowing for melt production. To test this model, we have analysed around 100 samples from volcanic centers across western North America by ICP-MS for rare earth elements (REE). Most of the samples are younger than 5 Ma, and all of them have previously been analysed by XRF. Using trace element ratios such as La/Yb and Nb/Y we assess depth of melting and melt fraction, respectively. In addition, we use REE inversion modelling to estimate melt fractions as a function of depth and temperature of melting. The results are compared to existing constraints on lithospheric thickness and mantle potential

  7. The flow beneath a periodic travelling surface water wave

    International Nuclear Information System (INIS)

    We discuss some recent results on the behaviour of the velocity field, pressure and particle trajectories beneath a periodic travelling wave propagating at the surface of water with a flat bed, in a flow without underlying currents. By analysing the governing equations we avoid approximations, thus ensuring the validity of the results without restrictions on the wave amplitude. In particular, the presented approach applies to waves of large amplitude. We also formulate some open problems, venturing into the relatively unexplored field of wave–current interactions. (topical review)

  8. Crustal structure beneath China from receiver function analysis

    Science.gov (United States)

    Chen, Youlin; Niu, Fenglin; Liu, Ruifeng; Huang, Zhibin; TkalčIć, Hrvoje; Sun, Li; Chan, Winston

    2010-03-01

    We collected and processed a large amount of high-quality broadband teleseismic waveform data recorded by the 48 Chinese National Digital Seismic Network stations to estimate large-scale lateral variations of crustal thickness and Vp/Vs ratio (hence Poisson's ratio) beneath China. A statistical method was used to select mutually coherent receiver functions at each station, which yielded over 200 traces for most of the stations. With the conventional H-κ (the crustal thickness and Vp/Vs ratio) approach, there is a large trade-off between H and κ. Consequently, multiple maxima are frequently observed in the H-κ domain. We introduced a weight function that measures the coherence between the P-to-S conversion and the reverberation phases at each H-κ grid to reduce the trade-off. A 4th-root stacking method was further applied to reduce uncorrelated noise relative to the linear stack. These modifications turned out to be very effective in reducing the H-κ trade-off and yielded reliable estimates of crustal thickness and Vp/Vs ratio. The crust beneath eastern China is as thin as 31-33 km and the underlying Moho is relatively flat and sharp. In the western part of China, the crust is considerably thicker and shows large variations. The Moho is observed at about 51 km depth along the Tian Shan fold system and about 84 km deep beneath the central part of the Tibetan Plateau. The transition occurs at the so-called N-S belt between about 100° and 110°E, which is featured by unusually high seismicity and large gravity anomalies. The average Vp/Vs ratio over the mainland China crust is about 1.730 (σ = 0.249), significantly lower than the global average 1.78 (σ = 0.27) of the continental crust. This lower Vp/Vs ratio may suggest a general absence of mafic lowermost crustal layer beneath China.

  9. On the Turbulence Beneath Finite Amplitude Water Waves

    CERN Document Server

    Babanin, Alexander V

    2015-01-01

    The paper by Beya et al. (2012, hereinafter BPB) has a general title of Turbulence Beneath Finite Amplitude Water Waves, but is solely dedicated to discussing the experiment by Babanin and Haus (2009, hereinafter BH) who conducted measurements of wave-induced non-breaking turbulence by particle image velocimetry (PIV). The authors of BPB conclude that their observations contradict those of BH. Here we argue that the outcomes of BPB do not contradict BH. In addition, although the main conclusion of BPB is that there is no turbulence observed in their experiment, it actually is observed.

  10. The ionospheric heating beneath the magnetospheric cleft revisited

    Directory of Open Access Journals (Sweden)

    G. W. Prölss

    2005-03-01

    Full Text Available A prominent peak in the electron temperature of the topside ionosphere is observed beneath the magnetospheric cleft. The present study uses DE-2 data obtained in the Northern Winter Hemisphere to investigate this phenomenon. First, the dependence of the location and magnitude of the temperature peak on the magnetic activity is determined. Next, using a superposed epoch analysis, the mean latitudinal profile of the temperature enhancement is derived. The results of the present study are compared primarily with those obtained by Titheridge (1976, but also with more recent observations and theoretical predictions.

  11. Occurrence of human enteroviruses in a groundwater aquifer recharged with tertiary wastewater effluents

    Energy Technology Data Exchange (ETDEWEB)

    Vaughn, J M; Landry, E F

    1978-01-01

    A two-year study of the impact of human viruses on a tertiary treatment-groundwater recharge system located on Long Island is currently nearing completion. Raw influents, chlorinated tertiary effluents, and groundwater from beneath a uniquely designed recharge basin were assayed on a weekly basis for the presence of indigenous human enteroviruses and coliform bacteria. While high concentrations of viruses were routinely isolated from sewage influents, the chlorinated tertiary effluents were positive for virus in only 3 of 20 samples. In spite of the high quality effluent being recharged, viruses were detected in the groundwater aquifer on several occasions indicating their ability to percolate through the recharge basin. This finding was confirmed by the results of two poliovirus seeding experiments carried out at the field installation. At both high (75 to 100 cm/hr) and low (6 cm/hr) infiltration rates seeded polioviruses were detected at all sampling levels as well as in the groundwater aquifer, 7.62 m below the recharge basin. It would appear that lower infiltration rates promote better virus removal in the specific type of soil used in this study.

  12. Isotope studies on mechanisms of groundwater recharge to an alluvial aquifer in Gatton, Queensland, Australia

    International Nuclear Information System (INIS)

    Gatton is an important agricultural area for Queensland where about 40% of its vegetables needs are produced using groundwater as the main source. An alluvial Aquifer is located about 30m beneath the layers of alluvial sediments ranging from black soils of volcanic origin on top, layers of alluvial sands, clays and beds of sand and gravel. The leakage of creek flows has been considered to be the main source of recharge to this aquifer. A number of weirs have been built across the Lockyer and Laidley creeks to allow surface water to infiltrate through the beds when the creeks flow. Water levels in bores in a section located in the middle of the alluvial plain (Crowley Vale) have been declining for the last 20 years with little or no success in recharging from the creeks. Acute water shortages have been experienced in the Gatton area during the droughts of 1980-81, 1986-87 and 1994-97. Naturally occurring stable isotopes, 2H, 180 and 13C as well as radioisotopes 3H and 14C have been used to delineate sources of recharge and active recharge areas. Tritium tracing of soil moisture in the unsaturated soil was also used to determine direct infiltration rates

  13. Metabolic interdependencies between phylogenetically novel fermenters and respiratory organisms in an unconfined aquifer

    Energy Technology Data Exchange (ETDEWEB)

    Wrighton, Kelly C.; Castelle, Cindy; Wilkins, Michael J.; Hug, Laura A.; Sharon, I.; Thomas, Brian C.; Handley, Kim M.; Mullin, Sean W.; Nicora, Carrie D.; Singh, Andrea; Lipton, Mary S.; Long, Philip E.; Williams, Kenneth H.; Banfield, Jillian F.

    2014-07-08

    Fermentation-based metabolism is an important ecosystem function often associated with environments rich in organic carbon, such as wetlands, sewage sludge, and the mammalian gut. The diversity of microorganisms and pathways involved in carbon and hydrogen cycling in sediments and aquifers and the impacts of these processes on other biogeochemical cycles remain poorly understood. Here we used metagenomics and proteomics to characterize microbial communities sampled from an aquifer adjacent to the Colorado River at Rifle, Colorado, USA, and document interlinked microbial roles in geochemical cycling. The organic carbon content in the aquifer was elevated via two acetate-based biostimulation treatments. Samples were collected at three time points, with the objective of extensive genome recovery to enable metabolic reconstruction of the community. Fermentative community members include genomes from a new phylum (ACD20), phylogenetically novel members of the Chloroflexi and Bacteroidetes, as well as candidate phyla genomes (OD1, BD1-5, SR1, WWE3, ACD58, TM6, PER, and OP11). These organisms have the capacity to produce hydrogen, acetate, formate, ethanol, butyrate, and lactate, activities supported by proteomic data. The diversity and expression of hydrogenases suggests the importance of hydrogen currency in the subsurface. Our proteogenomic data further indicate the consumption of fermentation intermediates by Proteobacteria can be coupled to nitrate, sulfate, and iron reduction. Thus, fermentation carried out by previously unstudied members of sediment microbial communities may be an important driver of diverse subsurface biogeochemical cycles.

  14. Unprotected karst resources in western Iran: the environmental impacts of intensive agricultural pumping on the covered karstic aquifer, a case in Kermanshah province

    Science.gov (United States)

    Taheri, Kamal; Taheri, Milad; Parise, Mario

    2015-04-01

    Bare and covered karst areas, with developed karstic aquifers, cover 35 percent of the Kermanshah province in western Iran. These aquifers are the vital sources for drinking and agricultural water supplies. Over the past decade, intensive groundwater use (exploitation) for irrigation imposed a significant impact on the carbonate environments. The huge amount of groundwater over-exploitations has been carried out and still goes on by local farmers in the absence of appropriate governance monitoring control. Increasing in water demands, for more intense crop production, is an important driving force toward groundwater depletion in alluvial aquifers. Progressive groundwater over-exploitations from underlying carbonate rocks have led to dramatic drawdown in alluvial aquifers and deep karst water tables. Detecting new sources of groundwater extractions and prohibiting the karst water utilization for agricultural use could be the most effective strategy to manage the sustainability of covered karst aquifers. Anthropogenic pressures on covered karst aquifers have magnified the drought impacts and caused dryness of most of the karst springs and deep wells. In this study, the combination of geophysical and geological studies was used to estimate the most intensively exploited agricultural zones of Islam Abad plain in the southwestern Kermanshah province using GIS. The results show that in the past decade a great number of deep wells were drilled through the overburden alluvial aquifer and reached the deep karst water resources. However, the difficulties involved in monitoring deep wells in covered karst aquifer were the main cause of karst water depletion. Overexploitation from both alluvial and karst aquifers is the main reason for drying out the Arkawazi, Sharafshah, Gawrawani karst springs, and the karst drinking water wells 1, 3 and 5 of Islam Abad city. Karst spring landscape destructions, fresh water supply deficit for inhabitants, decreasing of tourism and

  15. Hydrogeochemical study of water in some aquifers of the Estado de Mexico; Estudio hidrogeoquimico de agua de algunos manantiales del Estado de Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Pena, P.; Lopez, A.; Balcazar, M.; Flores, J.H.; Cardenas, S. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Schubert, M. [UFZ Centre for Environmental Research Leipzig-Halle GMBH, Permoser Str. 15, 04318 Leipzig (Germany)

    2005-07-01

    The National Institute of Nuclear Research of Mexico (ININ), has developed a technique that allows to study the association of recharge mechanisms, residence times of the water in the aquifers, as well as the local lithology and the geochemical parameters. The viability of this technique was proven on November 2004 in the aquifers (La Perita, El Tunel y El Pedregal) located in the Asuncion Tepexoyuca, Estado de Mexico. It was observed that so much the aquifer El Tunel like La Perita are used for the human consumption, the aquifer of El Pedregal is used for the fish cultivation. The studies were carried out during March 2003 to November 2004. In the aquifer La Perita the maximum values of the radon concentration (0.76 Bq L{sup -1}) they were observed in the summertime time (December). In the spring El Tunel the maximum values of the radon concentration (4.08 Bq L{sup -1}) they were observed in the rainy season (September) this increment can be due to the contributions of the recharge of aquifers that it allows the haulage of the radon of other alternating roads of infiltration of the rain water. Of the physicochemical and radiochemical analyses carried out in the water samples of the studied aquifers, it is deduced that they are waters of good quality since for the human consumption since that they are inside on the maximum permissible limits as for their potability according to national and international standards. Likewise it was observed that the water of the aquifers is a single aquifer, since that its differences they due to the time of permanency of the water inside the aquifer. The classification of the underground water deduced that it is calcic and/or magnesic bi carbonated water belonging to the type of meteoric waters of recent infiltration. (Author)

  16. Water-level change, High Plains aquifer, 1995 to 2000

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This raster data set represents water-level change in the High Plains aquifer of the United States from 1995 to 2000, in feet. The High Plains aquifer underlies...

  17. Aquifers of Alluvial and Glacial Origin - Direct Download

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the extent of the alluvial and glacial aquifers north of the southern-most line of glaciation. Aquifers are shown in the States of Maine,...

  18. Water-level change, High Plains aquifer, 2005 to 2009

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This raster data set represents water-level change in the High Plains aquifer of the United States from 2005 to 2009, in feet. The High Plains aquifer underlies...

  19. Water-level change, High Plains aquifer, 1980 to 1995

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This raster data set represents water-level change in the High Plains aquifer of the United States from 1980 to 1995, in feet. The High Plains aquifer underlies...

  20. Water-level change, High Plains aquifer, 2000 to 2005

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This raster data set represents water-level change in the High Plains aquifer of the United States from 2000 to 2005, in feet. The High Plains aquifer underlies...

  1. Modelling the effects of tides and storm surges on coastal aquifers using a coupled surface-subsurface approach.

    Science.gov (United States)

    Yang, Jie; Graf, Thomas; Herold, Maria; Ptak, Thomas

    2013-06-01

    Coastal aquifers are complex hydrologic systems because many physical processes interact: (i) variably saturated flow, (ii) spatial-temporal fluid density variations, (iii) tidal fluctuations, (iv) storm surges overtopping dykes, and (v) surface runoff of storm water. The HydroGeoSphere model is used to numerically simulate coastal flow dynamics, assuming a fully coupled surface-subsurface approach, accounting for all processes listed above. The diffusive wave approximation of the St. Venant equation is used to describe surface flow. Surface flow and salt transport are fully coupled with subsurficial variably saturated, variable-density flow and salt transport through mathematical terms that represent exchange of fluid mass and solute mass, respectively. Tides and storm surges induce a time-variant head that is applied to nodes of the surface domain. The approach is applied to real cases of tide and storm surge events. Tide simulation results confirm the existence of a recirculating zone, forming beneath the upper part of the intertidal zone. By monitoring the exchange fluid flux rates through the beach, it was found that the major inflow to the aquifer takes place at the upper part of the intertidal zone, which explains the formation of the recirculating zone. The recirculating zone is forming particularly during rising tide. Results from a storm surge simulation show that plume fingers develop below the flooded land surface. Natural remediation by seaward flowing freshwater is relatively slow, such that reducing the salt concentration in the aquifer down to drinking water standards takes up to 10 years. PMID:23603354

  2. Numerical modelling to determine freshwater/saltwater interface configuration in a low-gradient coastal wetland aquifer

    Science.gov (United States)

    Swain, E.; Wolfert, M.

    2007-01-01

    A coupled hydrodynamic surface-water/groundwater model with salinity transport is used to examine the aquifer salinity interface in the coastal wetlands of Everglades National Park in Florida, USA. The hydrology differs from many other coastal areas in that inland water levels are often higher than land surface, the flow gradients are small, and, along parts of the coastline, the wetland is separated from the offshore waters by a natural embankment. Examining the model-simulated aquifer salinities along a transect that cuts the coastal embankment, a small zone of fresh groundwater is seen beneath the embankment, which varies seasonally in size and salinity. The simulated surface-water and groundwater levels suggest that this zone exists because of ponding of surface water at the coastal embankment, creating freshwater underflow to the offshore waters. The seasonal variability in the freshwater zone indicates that it is sensitive to the wetland flows and water levels. The small size of the zone in the simulation indicates that a model with a higher spatial resolution could probably depict the zone more accurately. The coastal ecology is strongly affected by the salinity of the shallow groundwater and the coastal freshwater zone is sensitive to wetland flows and levels. In this environment, predicting the aquifer salinity interface in coastal wetlands is important in examining the effects of changing water deliveries associated with ecosystem restoration efforts.

  3. Aquifer parameter estimation from surface resistivity data.

    Science.gov (United States)

    Niwas, Sri; de Lima, Olivar A L

    2003-01-01

    This paper is devoted to the additional use, other than ground water exploration, of surface geoelectrical sounding data for aquifer hydraulic parameter estimation. In a mesoscopic framework, approximated analytical equations are developed separately for saline and for fresh water saturations. A few existing useful aquifer models, both for clean and shaley sandstones, are discussed in terms of their electrical and hydraulic effects, along with the linkage between the two. These equations are derived for insight and physical understanding of the phenomenon. In a macroscopic scale, a general aquifer model is proposed and analytical relations are derived for meaningful estimation, with a higher level of confidence, of hydraulic parameter from electrical parameters. The physical reasons for two different equations at the macroscopic level are explicitly explained to avoid confusion. Numerical examples from existing literature are reproduced to buttress our viewpoint. PMID:12533080

  4. Nitrate reduction in an unconfined sandy aquifer

    DEFF Research Database (Denmark)

    Postma, Diederik Jan; Boesen, Carsten; Kristiansen, Henning; Larsen, Flemming

    1991-01-01

    Nitrate distribution and reduction processes were investigated in an unconfined sandy aquifer of Quaternary age. Groundwater chemistry was studied in a series of eight multilevel samplers along a flow line, deriving water from both arable and forested land. Results show that plumes of nitrate......-contaminated groundwater emanate from the agricultural areas and spread through the aquifer. The aquifer can be subdivided into an upper 10- to 15-m thick oxic zone that contains O2 and NO3-, and a lower anoxic zone characterized by Fe2+-rich waters. The redox boundary is very sharp, which suggests that reduction...... processes of O2 and NO3- occur at rates that are fast compared to the rate of downward water transport. Nitrate-contaminated groundwater contains total contents of dissolved ions that are two to four times higher than in groundwater derived from the forested area. The persistence of the high content of...

  5. Evaluation of Four Water Management Policies for Ogallala Aquifer Sustainability in the Texas High Plains

    Science.gov (United States)

    Hernandez, J. E.; Gowda, P. H.; Howell, T. A.; Marek, T. H.; Ha, W.; Almas, L. K.

    2010-12-01

    Diminishing groundwater supply in the Ogallala Aquifer will severely reduce regional crop and animal production in the absence of a sustainable water management policy. It is essential to mitigate adverse impacts on the regional economy due to future withdrawals of the limited groundwater resource. Currently, approximately ten alternative water management policies are being debated by policy makers in the Central and Southern High Plains of the Ogallala Aquifer region. Before implementing any new policy or modifying current policies, newer alternative policies should be evaluated for their impact on groundwater levels with eventual extension to regional economic impacts. The main objective of this study was to evaluate four water management policies, from the debated ones, on future groundwater levels in the Ogallala Aquifer beneath four heavily irrigated counties (Dallam, Sherman, Hartley, and Moore) located in the northwest corner of the Texas High Plains using a calibrated ModFlow model. The four water management policies were (1) voluntary permanent conversion to dry land production up to 10% of the total irrigated area, (2) adoption of advances in biotechnology that allow water use reductions at a rate of 1% per year up to 10% of current use, (3) mandatory water use reduction to decrease the total water pumped by 10% (volume per unit land area per year), and (4) voluntary temporary conversion to dry land production during 15 years for a maximum area of 10% of the total irrigated area. The water management policies were converted into water demand rates for ModFlow model inputs. Simulations were conducted for a 50-year (2010-2060) period. Preliminary results indicate that a combination of more than one policy will be required to produce a significant reduction in the current groundwater depletion rates.

  6. Estimating specific yield and storage change in an unconfined aquifer using temporal gravity surveys

    Science.gov (United States)

    Gehman, Carter L.; Harry, Dennis L.; Sanford, William E.; Stednick, John D.; Beckman, Nathaniel A.

    2009-04-01

    Two high-precision gravity surveys were conducted to determine groundwater mass changes at a managed groundwater recharge site in northeastern Colorado. Gravity data were collected during pumping and two months after pumping ceased. During pumping, gravity was lower by as much as 46 μGal near the pumping wells and higher by as much as 90 μGal near the recharge ponds in comparison to data collected after pumping had ceased. These differences are attributed to changes in groundwater mass associated with drawdown and infiltration. Inverse modeling of the gravity data indicates a 5.1 × 105 m3 decrease in storage beneath the recharge ponds between the two surveys, which we attribute to dissipation of the groundwater mound created by recharge during pumping. This estimate of the change in groundwater storage is made independently of assumptions of physical properties of the aquifer. Dividing the change in water volume per unit area determined from the gravity modeling by the change in water level measured in wells provides an estimate of specific yield (Sy) of 0.21 ± 0.03, which is within the range of specific yield estimates derived from aquifer tests at the site. Water level changes predicted from the gravity data agree on average to within ±0.45 m of those measured, which we take to be an estimate of the uncertainty in water table depth predictions that can be obtained from gravimetric data in unconfined aquifers. The study covers a 3.2 km2 area, providing a prototype for similar studies at larger scales.

  7. Estimating annual groundwater recharge coefficient for karst aquifers of the southern Apennines (Italy)

    Science.gov (United States)

    Allocca, V.; Manna, F.; De Vita, P.

    2014-02-01

    aspect of groundwater hydrology in karst aquifers which is fundamental for the formulation of appropriate management models of groundwater resources at a regional scale, also taking into account mitigation strategies for climate change impacts. Finally, the proposed hydrological characterizations are also supposed to be useful for the assessment of mean annual runoff over carbonate mountains, which is another important topic concerning water management in the southern Apennines.

  8. The Investigation of Mass Transfer in the Karasu Karstic Aquifer, Konya, Turkey

    Science.gov (United States)

    Ozdemir, Adnan; Nalbantcilar, Tahir

    2002-09-01

    In this study, the changes in the chemical composition of the groundwater along a flow path were examined by using the water samples collected from unconfined, semi-confined and confined parts of the Karasu karstic aquifer. It was determined that transport of bicarbonate, calcium, and magnesium was dominant in unconfined and semi-confined parts of the aquifer, whereas calcite and dolomite precipitate in the confined parts. On the other hand, gypsum dissolution is present in all parts of the aquifer. In addition, the computed saturation indices explain the occurrences and precipitation of travertines in the Goksu Valley, which is the discharge area for the aquifer. Résumé. Les modifications de la composition chimique de l'eau souterraine le long d'un axe d'écoulement ont été étudiées à partir d'échantillons prélevés dans les parties libres, semi-captives et captives de l'aquifère karstique de Karasu. On a mis en évidence que le transport de carbonate, de calcium et de magnésium est prépondérant dans les parties libres et semi-captives de l'aquifère, alors que la calcite et la dolomite précipitent dans les parties captives. En outre, la dissolution du gypse se produit dans toutes les parties de l'aquifère. Par ailleurs, les indices de saturation calculés rendent compte de l'existence et de la précipitation des travertins dans la vallée du Göksu, qui est la zone de décharge de cet aquifère. Resumen. En este estudio, se han examinado los cambios de composición química en las aguas subterráneas a lo largo de una línea de corriente mediante el análisis de muestras recogidas en partes libres, semiconfinadas y cautivas del acuífero cárstico de Karasu. Se ha determinado que el transporte de bicarbonato, calcio y magnesio es dominante en las zonas libres y semiconfinadas, mientras que la calcita y la dolomita precipitan en las zonas confinadas. Por otro lado, la disolución de yesos ocurre en todo el ámbito del acuífero. Además, los

  9. Aquifer thermal energy storage. International symposium: Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-05-01

    Aquifers have been used to store large quantities of thermal energy to supply process cooling, space cooling, space heating, and ventilation air preheating, and can be used with or without heat pumps. Aquifers are used as energy sinks and sources when supply and demand for energy do not coincide. Aquifer thermal energy storage may be used on a short-term or long-term basis; as the sole source of energy or as a partial storage; at a temperature useful for direct application or needing upgrade. The sources of energy used for aquifer storage are ambient air, usually cold winter air; waste or by-product energy; and renewable energy such as solar. The present technical, financial and environmental status of ATES is promising. Numerous projects are operating and under development in several countries. These projects are listed and results from Canada and elsewhere are used to illustrate the present status of ATES. Technical obstacles have been addressed and have largely been overcome. Cold storage in aquifers can be seen as a standard design option in the near future as it presently is in some countries. The cost-effectiveness of aquifer thermal energy storage is based on the capital cost avoidance of conventional chilling equipment and energy savings. ATES is one of many developments in energy efficient building technology and its success depends on relating it to important building market and environmental trends. This paper attempts to provide guidance for the future implementation of ATES. Individual projects have been processed separately for entry onto the Department of Energy databases.

  10. Unconfined Aquifer Flow Theory - from Dupuit to present

    OpenAIRE

    Mishra, Phoolendra K.; Kuhlman, Kristopher L.

    2013-01-01

    Analytic and semi-analytic solution are often used by researchers and practicioners to estimate aquifer parameters from unconfined aquifer pumping tests. The non-linearities associated with unconfined (i.e., water table) aquifer tests makes their analysis more complex than confined tests. Although analytical solutions for unconfined flow began in the mid-1800s with Dupuit, Thiem was possibly the first to use them to estimate aquifer parameters from pumping tests in the early 1900s. In the 195...

  11. Conceptual and numerical modeling approach of the Guarani Aquifer System

    OpenAIRE

    Rodríguez, L.; Vives, L; Gomez, A.

    2013-01-01

    In large aquifers, relevant for their considerable size, regional groundwater modeling remains challenging given geologic complexity and data scarcity in space and time. Yet, it may be conjectured that regional scale groundwater flow models can help in understanding the flow system functioning and the relative magnitude of water budget components, which are important for aquifer management. The Guaraní Aquifer System is the largest transboundary aquifer in South America. It contains an enormo...

  12. Aquifer properties of the Chalk of England

    OpenAIRE

    MacDonald, Alan M.; Allen, David J

    2001-01-01

    Aquifer properties data from 2100 pumping tests carried out in the Chalk aquifer have been collated as part of a joint British Geological Survey/Environment Agency project. The dataset is highly biased: most pumping tests have been undertaken in valley areas where the yield of the Chalk is highest. Transmissivity values from measured sites give the appearance of log-normality, but are not truly log-normal. The median of available data is 540 m2/d and the 25th and 75th percentiles 190 m2/d and...

  13. Cold water aquifer storage. [air conditioning

    Science.gov (United States)

    Reddell, D. L.; Davison, R. R.; Harris, W. B.

    1980-01-01

    A working prototype system is described in which water is pumped from an aquifer at 70 F in the winter time, chilled to a temperature of less than 50 F, injected into a ground-water aquifer, stored for a period of several months, pumped back to the surface in the summer time. A total of 8.1 million gallons of chilled water at an average temperature of 48 F were injected. This was followed by a storage period of 100 days. The recovery cycle was completed a year later with a total of 8.1 million gallons recovered. Approximately 20 percent of the chill energy was recovered.

  14. Isotope geochemistry and modelling of the multi-aquifer system in the eastern part of Lithuania

    Science.gov (United States)

    Mokrik, Robert; Juodkazis, Vytautas; Štuopis, Anicetas; Mažeika, Jonas

    2014-06-01

    A steady-state groundwater flow model of three Quaternary intertill aquifers in the eastern part of Lithuania has been compiled. The distinction of separate modelled layers is based on hydraulic and isotope-hydrochemistry data criteria. 3H data were used to estimate the corrected groundwater age and were coupled with a groundwater-flow-dynamics model of the Quaternary aquifer system along a cross-section flow pathway from the Baltic Upland recharge area in eastern Lithuania towards the discharge area in the lowlands near the city of Kaunas in central Lithuania. The bicarbonate content in groundwater (214-462 mg/l) increases downgradient towards the lowland area. The other major constituents and total dissolved solids (TDS) have a trend analogous to the bicarbonate. The 14C activity of dissolved inorganic carbon (DIC) in the groundwater ranges from 41.4 to 85.7 pMC. With aquifer-system depth, active precipitation of aqueous solution takes place by dissolving minerals of calcite and dolomite and leakage of "old" groundwater from lower aquifers; the process is also traced by lower 14C and 3H activities and by more positive δ18O values in lowland areas.

  15. On Pore Dynamics and Calcite Solubility in Carbonaceous Aquifers used in Energy Storage Applications

    Science.gov (United States)

    Tilley, Bs; Brady, Ds; Ueckert, M.; Baumann, T.

    2015-11-01

    Geothermal energy harvesting applications use deep groundwater aquifers to store harvested energy. The impact of this additional energy to the aquifer chemistry is crucial for long-term operation. Gaseous CO2 is added to the injected water to compensate potential precipitates of carbonates and to prevent structural changes to the aquifer. Both of these effects affect the local chemical equilibrium of the aquifer, and we consider a long-wave model of this process for a single axisymmetric pore where gaseous CO2 concentration, temperature, fluid flow and hydrochemistry modify the pore radius in space and time. Substrates are composed of calcite and dolomite, whose composition evolution is part of the full pore problem. During oscillatory flow conditions, concentration levels of the dissolved species can be sufficient to overcome elevated temperature levels and promote pore closure for sufficiently thin pores. We identify the conditions under which this pore closure takes place. Support from the Bavarian State Ministry for the Economy is gratefully acknowledged.

  16. Measurement and modeling of CO2 diffusion coefficient in Saline Aquifer at reservoir conditions

    Science.gov (United States)

    Azin, Reza; Mahmoudy, Mohamad; Raad, Seyed; Osfouri, Shahriar

    2013-12-01

    Storage of CO2 in deep saline aquifers is a promising techniques to mitigate global warming and reduce greenhouse gases (GHG). Correct measurement of diffusivity is essential for predicting rate of transfer and cumulative amount of trapped gas. Little information is available on diffusion of GHG in saline aquifers. In this study, diffusivity of CO2 into a saline aquifer taken from oil field was measured and modeled. Equilibrium concentration of CO2 at gas-liquid interface was determined using Henry's law. Experimental measurements were reported at temperature and pressure ranges of 32-50°C and 5900-6900 kPa, respectively. Results show that diffusivity of CO2 varies between 3.52-5.98×10-9 m2/s for 5900 kPa and 5.33-6.16×10-9 m2/s for 6900 kPa initial pressure. Also, it was found that both pressure and temperature have a positive impact on the measures of diffusion coefficient. Liquid swelling due to gas dissolution and variations in gas compressibility factor as a result of pressure decay was found negligible. Measured diffusivities were used model the physical model and develop concentration profile of dissolved gas in the liquid phase. Results of this study provide unique measures of CO2 diffusion coefficient in saline aquifer at high pressure and temperature conditions, which can be applied in full-field studies of carbon capture and sequestration projects.

  17. Geochemical analyses of ground-water ages, recharge rates, and hydraulic conductivity of the N aquifer, Black Mesa area, Arizona

    Science.gov (United States)

    Lopes, Thomas J.; Hoffmann, John P.

    1997-01-01

    The Navajo Nation and Hopi Tribe of the Black Mesa area, Arizona, depend on ground water from the N aquifer to meet most tribal and industrial needs. Increasing use of this aquifer is creating concerns about possible adverse effects of increased ground-water withdrawals on the water resources of the region. A thorough understanding of the N aquifer is necessary to assess the aquifer's response to ground-water withdrawals. This study used geochemical techniques as an independent means of improving the conceptual model of ground-water flow in the N aquifer and to estimate recharge rates and hydraulic conductivity. Ground water flows in a south-southeastward direction from the recharge area around Shonto into the confined part of the N aquifer underneath Black Mesa. Ground-water flow paths diverge in the confined part of the aquifer to the northeast and south. The N aquifer thins to extinction south of Black Mesa. This discontinuity could force ground water to diverge along paths of least resistance. Ground water discharges from the confined part of the aquifer into Laguna Creek and Moenkopi Wash and from springs southwest of Kykotsmovi and southeast of Rough Rock after a residence time of about 35,000 years or more. Recent recharge along the periphery of Black Mesa mixes with older ground water that discharges from the confined part of the aquifer and flows away from Black Mesa. Dissolved-ion concentrations, ratios of dissolved ions, dissolved-gas concentrations, tritium, carbon-13, and chlorine-36 data indicate that water in the overlying D aquifer could be leaking into the confined part of the N aquifer in the southeastern part of Black Mesa. The boundary between the leaky and nonleaky zones is defined roughly by a line from Rough Rock to Second Mesa and separates ground waters that have significantly different chemistries. The Dakota Sandstone and Entrada Formation of the D aquifer could be the sources of leakage. Adjusted radiocarbon ground-water ages and data on

  18. Predicted nitrate and arsenic concentrations in basin-fill aquifers of the Southwest Principal Aquifers study area

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This product "Predicted nitrate and arsenic concentrations in basin-fill aquifers of the Southwest Principal Aquifers study area" is a 1:250,000-scale vector...

  19. Digital data sets that describe aquifer characteristics of the Vamoosa-Ada aquifer in east-central Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized polygons of constant recharge values for the Vamoosa-Ada aquifer, in east-central Oklahoma. The Vamoosa-Ada aquifer is an...

  20. Digital data sets that describe aquifer characteristics of the Vamoosa-Ada aquifer in east-central Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized polygons of constant hydraulic conductivity values for the Vamoosa-Ada aquifer in east-central Oklahoma. The Vamoosa-Ada aquifer...

  1. Digital data sets that describe aquifer characteristics of the Vamoosa-Ada aquifer in east-central Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized water-level elevation contours for the Vamoosa-Ada aquifer in east-central Oklahoma. The Vamoosa-Ada aquifer is an important...

  2. EPA Region 6 Sole Source Aquifers in Louisiana, Geographic NAD83, EPA (1996) [sole_source_aquifers_LA_EPA_1996

    Data.gov (United States)

    Louisiana Geographic Information Center — Polygon layer of EPA Region 6 sole source aquifers in Louisiana. The sole source aquifers represented are Chicot and Southern Hills in Louisiana/Mississippi.

  3. Examples of transient sounding from groundwater exploration in sedimentary aquifers

    Science.gov (United States)

    Fitterman, D.V.

    1987-01-01

    Examples of the use of transient electromagnetic soundings for three groundwater exploration problems in sedimentary aquifers are given. The examples include: 1) estimating depths to water table and bedrock in an alluvium-filled basin, 2) mapping a confined freshwater aquifer in bedrock sediments, and 3) locating a freshwater/saltwater interface in a glacial-outwash aquifer. -from Author

  4. Groundwater modeling of the Calera Aquifer region in Central Mexico

    Science.gov (United States)

    The Calera Aquifer is the main source of water for irrigated agriculture, industrial, and drinking water purposes in the Calera Aquifer Region (CAR) in the state of Zacatecas, Mexico. Irrigated agriculture accounts for 80% of the total groundwater extracted from the Calera Aquifer. In recent years, ...

  5. Review: The Yucatán Peninsula karst aquifer, Mexico

    DEFF Research Database (Denmark)

    Bauer-Gottwein, Peter; Gondwe, Bibi Ruth Neuman; Charvet, Guillaume;

    2011-01-01

    The Yucatán Peninsula karst aquifer is one of the most extensive and spectacular karst aquifer systems on the planet. This transboundary aquifer system extends over an area of approximately 165,000 km2 in México, Guatemala and Belize. The Triassic to Holocene Yucatán limestone platform is located...

  6. Contribution to the hydrogeological, geochemical and isotopic study of Ain El Beidha and Merguellil (Kairouan plain) aquifers: Implication for the dam-aquifer relationship

    International Nuclear Information System (INIS)

    karst before reaching the Kairouan plain aquifer (springs). Groundwater under flow is estimated at 9 M m3 year-1 and the karstic spring flow is evaluated at 10 M m3 year-1. The spring waters show an intermediate isotope composition between dam reservoir water and the upper catchment of Ain el Beidha basin. The contribution of dam water in mixed water (spring) varies between 21 to 66% depending on time. Values from 18O and 2H ratio are well correlated with the karstic spring flow and with the water level in the reservoir. The hydrogeological study helped to understand the hydrodynamic functioning of the Kairouan plain aquifer system and identified a decline of the water table levels (1.5 m year-1). This decrease is explained mainly by over exploitation (4.8 M m3 year-1). The hydrochemical investigation indicated that the rock-water interaction is the main process contributing to the groundwater salinization. All the samples collected in the Merguellil basin are of the main hydrochemical type: Cl-SO4-Na. Stable isotope values measured in the upstream part of plain, closer the dam, differ from other parts of the aquifer, therefore suggesting a significant input from evaporated dam waters mixed with Ain el Beidha groundwater (spring water coming from the karst). This contamination can be observed as far as 7 km downstream. However, isotopic imprint of the previous recharge process (infiltration of wadi floods) are still noticeable. The residence time of the groundwater was estimated by carbon-14 dating that shows variable values of transit velocity of the groundwater ranging from 3.36 to 0.44 m year-1 depending on the groundwater flow and on the lithological variability of the aquifer. (Author).

  7. Study of the feasibility of an aquifer storage and recovery system in a deep aquifer in Belgium

    OpenAIRE

    Vandenbohede, A.; Van Houtte, E.; Lebbe, L.

    2008-01-01

    The feasibility of aquifer storage and recovery (ASR) was tested in a deep aquifer near Koksijde, Belgium. To achieve this, oxic drinking water was injected into a deep aquifer (the Tienen Formation) that contains anoxic brackish water. The hydraulic properties of the aquifer were determined using a step-drawdown test. Chemical processes caused by the injection of the water were studied by two push—pull tests. The step-drawdown test was interpreted by means of an inverse numerical model, resu...

  8. Aquifer geochemistry at potential aquifer storage and recovery sites in coastal plain aquifers in the New York city area, USA

    Science.gov (United States)

    Brown, C.J.; Misut, P.E.

    2010-01-01

    The effects of injecting oxic water from the New York city (NYC) drinking-water supply and distribution system into a nearby anoxic coastal plain aquifer for later recovery during periods of water shortage (aquifer storage and recovery, or ASR) were simulated by a 3-dimensional, reactive-solute transport model. The Cretaceous aquifer system in the NYC area of New York and New Jersey, USA contains pyrite, goethite, locally occurring siderite, lignite, and locally varying amounts of dissolved Fe and salinity. Sediment from cores drilled on Staten Island and western Long Island had high extractable concentrations of Fe, Mn, and acid volatile sulfides (AVS) plus chromium-reducible sulfides (CRS) and low concentrations of As, Pb, Cd, Cr, Cu and U. Similarly, water samples from the Lloyd aquifer (Cretaceous) in western Long Island generally contained high concentrations of Fe and Mn and low concentrations of other trace elements such as As, Pb, Cd, Cr, Cu and U, all of which were below US Environmental Protection Agency (USEPA) and NY maximum contaminant levels (MCLs). In such aquifer settings, ASR operations can be complicated by the oxidative dissolution of pyrite, low pH, and high concentrations of dissolved Fe in extracted water.The simulated injection of buffered, oxic city water into a hypothetical ASR well increased the hydraulic head at the well, displaced the ambient groundwater, and formed a spheroid of injected water with lower concentrations of Fe, Mn and major ions in water surrounding the ASR well, than in ambient water. Both the dissolved O2 concentrations and the pH of water near the well generally increased in magnitude during the simulated 5-a injection phase. The resultant oxidation of Fe2+ and attendant precipitation of goethite during injection provided a substrate for sorption of dissolved Fe during the 8-a extraction phase. The baseline scenario with a low (0.001M) concentration of pyrite in aquifer sediments, indicated that nearly 190% more water

  9. Preliminary model of the pre-Tertiary basement rocks beneath Yucca Flat, Nevada Test Site, Nevada, based on analysis of gravity and magnetic data

    Science.gov (United States)

    Phelps, Geoffrey A.; McKee, Edwin H.; Sweetkind, D.; Langenheim, V.E.

    2000-01-01

    The Environmental Restoration Program of the U.S. Department of Energy, Nevada Operations Office, was developed to investigate the possible consequences to the environment of 40 years of nuclear testing on the Nevada Test Site. The majority of the tests were detonated underground, introducing contaminants into the ground-water system (Laczniak and others, 1996). An understanding of the ground-water flow paths is necessary to evaluate the extent of ground-water contamination. This report provides information specific to Yucca Flat on the Nevada Test Site. Critical to understanding the ground-water flow beneath Yucca Flat is an understanding of the subsurface geology, particularly the structure and distribution of the pre-Tertiary rocks, which comprise both the major regional aquifer and aquitard sequences (Winograd and Thordarson, 1975; Laczniak and others, 1996). Because the pre-Tertiary rocks are not exposed at the surface of Yucca Flat their distribution must be determined through well logs and less direct geophysical methods such as potential field studies. In previous studies (Phelps and others, 1999; Phelps and Mckee, 1999) developed a model of the basement surface of the Paleozoic rocks beneath Yucca Flat and a series of normal faults that create topographic relief on the basement surface. In this study the basement rocks and structure of Yucca Flat are examined in more detail using the basement gravity anomaly derived from the isostatic gravity inversion model of Phelps and others (1999) and high-resolution magnetic data, as part of an effort to gain a better understanding of the Paleozoic rocks beneath Yucca Flat in support of groundwater modeling.

  10. Factors affecting groundwater quality in the Valley and Ridge aquifers, eastern United States, 1993-2002

    Science.gov (United States)

    Johnson, Gregory C.; Zimmerman, Tammy M.; Lindsey, Bruce D.; Gross, Eliza L.

    2011-01-01

    Chemical and microbiological analyses of water from 230 wells and 35 springs in the Valley and Ridge Physiographic Province, sampled between 1993 and 2002, indicated that bedrock type (carbonate or siliciclastic rock) and land use were dominant factors influencing groundwater quality across a region extending from northwestern Georgia to New Jersey. The analyses included naturally occurring compounds (major mineral ions and radon) and anthropogenic contaminants [pesticides and volatile organic compounds (VOCs)], and contaminants, such as nitrate and bacteria, which commonly increase as a result of human activities. Natural factors, such as topographic position and the mineral composition of underlying geology, act to produce basic physical and geochemical conditions in groundwater that are reflected in physical properties, such as pH, temperature, specific conductance, and alkalinity, and in chemical concentrations of dissolved oxygen, radon, and major mineral ions. Anthropogenic contaminants were most commonly found in water from wells and springs in carbonate-rock aquifers. Nitrate concentrations exceeded U.S. Environmental Protection Agency maximum contaminant levels in 12 percent of samples, most of which were from carbonate-rock aquifers. Escherichia coli (E. coli), pesticide, and VOC detection frequencies were significantly higher in samples from sites in carbonate-rock aquifers. Naturally occurring elements, such as radon, iron, and manganese, were found in higher concentrations in siliciclastic-rock aquifers. Radon levels exceeded the proposed maximum contaminant level of 300 picocuries per liter in 74 percent of the samples, which were evenly distributed between carbonate- and siliciclastic-rock aquifers. The land use in areas surrounding wells and springs was another significant explanatory variable for the occurrence of anthropogenic compounds. Nitrate and pesticide concentrations were highest in samples collected from sites in agricultural areas and

  11. Digital data sets that describe aquifer characteristics of the Rush Springs aquifer in western Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized water-level elevation contours for the Rush Springs aquifer in western Oklahoma. This area encompasses all or part of Blaine,...

  12. Digital data sets that describe aquifer characteristics of the Enid isolated terrace aquifer in northwestern Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized polygons of constant hydraulic conductivity values for the Enid isolated terrace aquifer in northwestern Oklahoma. The Enid...

  13. State Aquifer Recharge Atlas Plates, Geographic NAD83, LDEQ (1999) [aquifer_recharge_potential_LDEQ_1988

    Data.gov (United States)

    Louisiana Geographic Information Center — This is a polygon dataset depicting the boundaries of aquifer systems in the state of Louisiana and adjacent areas of Texas, Arkansas and a portion of Mississippi....

  14. Digital data sets that describe aquifer characteristics of the Antlers aquifer in southeastern Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized water-level elevation contours for the Antlers aquifer in southeastern Oklahoma. The Early Cretaceous-age Antlers Sandstone is...

  15. Digital data sets that describe aquifer characteristics of the Enid isolated terrace aquifer in northwestern Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of a digitized polygon of a constant recharge value for the Enid isolated terrace aquifer in northwestern Oklahoma. The Enid isolated terrace...

  16. Digital data sets that describe aquifer characteristics of the Antlers aquifer in southeastern Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized polygons of constant recharge values for the Antlers aquifer in southeastern Oklahoma. The Early Cretaceous-age Antlers...

  17. Digital data sets that describe aquifer characteristics of the High Plains aquifer in western Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digital polygons of constant recharge rates for the High Plains aquifer in Oklahoma. This area encompasses the panhandle counties of...

  18. Digital data sets that describe aquifer characteristics of the Rush Springs aquifer in western Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized polygons of constant hydraulic conductivity values for the Rush Springs aquifer in western Oklahoma. This area encompasses all...

  19. Digital data sets that describe aquifer characteristics of the Central Oklahoma aquifer in central Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized polygons of a constant recharge value for the Central Oklahoma aquifer in central Oklahoma. This area encompasses all or part of...

  20. Digital data sets that describe aquifer characteristics of the Rush Springs aquifer in western Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized polygons of constant recharge values for the Rush Springs aquifer in western Oklahoma. This area encompasses all or part of...

  1. Aquifer Boundary of the Wood River Valley Aquifer System, South-Central Idaho

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset contains the boundary of the Wood River Valley aquifer system as modified and expanded from that defined by Skinner and others (2007): It has been...

  2. Digital data sets that describe aquifer characteristics of the Central Oklahoma aquifer in central Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized polygons of a constant hydraulic conductivity value for the Central Oklahoma aquifer in central Oklahoma. This area encompasses...

  3. Digital data sets that describe aquifer characteristics of the Central Oklahoma aquifer in central Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized water-level elevation contours for the Central Oklahoma aquifer in central Oklahoma. This area encompasses all or part of...

  4. Digital data sets that describe aquifer characteristics of the High Plains aquifer in western Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digital polygons of constant hydraulic conductivity values for the High Plains aquifer in Oklahoma. This area encompasses the panhandle...

  5. Digital data sets that describe aquifer characteristics of the High Plains aquifer in western Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized water-level elevation contours for the High Plains aquifer in western Oklahoma. This area encompasses the panhandle counties of...

  6. Digital data sets that describe aquifer characteristics of the Antlers aquifer in southeastern Oklahoma

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of digitized polygons of a constant hydraulic conductivity value for the Antlers aquifer in southeastern Oklahoma. The Early Cretaceous-age...

  7. Hydrogeochemical Analysis of an Overexploited Aquifer In Bangladesh Toward Managed Aquifer Recharge Project Implementation

    Science.gov (United States)

    Rahman, M. A.; Wiegand, B. A.; Pervin, M.; Sauter, M.

    2012-12-01

    In most parts of the upper Dupitila aquifer (Dhaka City, Bangladesh) the average groundwater depletion reaches 2-3 m/year due to increasing water demands of the growing population. To counteract overexploitation of the aquifer, a more sustainable water management is required. The analysis of the local water resources system suggests that Managed Aquifer Recharge (MAR) would help to restore groundwater resources to strengthen water supply of Dhaka City, e.g., by using collected urban monsoon runoff and excess surface water from rivers. To assess possible effects of surface water or rainwater injection on groundwater quality, a comprehensive hydrogeochemical survey of the Dupitila aquifer is required. This paper presents hydrogeochemical data to document the current status of groundwater quality and to evaluate potential groundwater pollution by mobilization of hazardous chemicals as a result of changes in the hydrochemical equilibria. We performed a comprehensive review of available secondary data sources and will present new results from hydrochemical and Sr isotope investigations of water samples that were conducted within this study. Currently, groundwater quality in the upper Dupitila aquifer is characterized by variations in the electrical conductivity in the range of 200 to 1100 μS/cm, which may indicate some anthropogenic contamination by leakage from waste disposal including the sewage network and from surface water infiltration into the groundwater aquifer. Dissolved oxygen concentrations range from 1.0 to 4.9 mg/L (average 2.5 mg/L) in the upper Dupitila aquifer, while the lower Dupilita aquifer shows dissolved oxygen concentrations in the range 0 to 0.7 mg/L. Concentrations of major ions show some variation primarily due to a sedimentologically/mineralogically heterogeneous aquifer composition (sand, gravel, clay horizons), but may also be affected by anthropogenic processes. The groundwater composition is predominated by Ca-Mg-HCO3 and saturation values

  8. Development of a three-dimensional ground-water model of the Hanford Site unconfined aquifer system: FY 1995 status report

    International Nuclear Information System (INIS)

    A three-dimensional numerical model of ground-water flow was developed for the uppermost unconfined aquifer at the Hanford Site in south-central Washington. Development of the model is supported by the Hanford Site Ground-Water Surveillance Project, managed by the Pacific Northwest National Laboratory, which is responsible for monitoring the sitewide movement of contaminants in ground water beneath the Hanford Site. Two objectives of the Ground-Water Surveillance Project are to (1) identify and quantify existing, emerging, or potential ground-water quality problems, and (2) assess the potential for contaminants to migrate from the Hanford Site through the ground-water pathway. Numerical models of the ground-water flow system are important tools for estimating future aquifer conditions and predicting the movement of contaminants through ground water. The Ground-Water Surveillance Project has supported development and maintenance of a two-dimensional model of the unconfined aquifer. This report describes upgrade of the two-dimensional model to a three-dimensional model. The numerical model is based on a three-dimensional conceptual model that will be continually refined and updated as additional information becomes available. This report presents a description of the three-dimensional conceptual model of ground-water flow in the unconfined aquifer system and then discusses the cur-rent state of the three-dimensional numerical model

  9. Pn anisotropic tomography and mantle dynamics beneath China

    Science.gov (United States)

    Zhou, Zhigang; Lei, Jianshe

    2016-08-01

    We present a new high-resolution Pn anisotropic tomographic model of the uppermost mantle beneath China inferred from 52,061 Pn arrival-time data manually picked from seismograms recorded at provincial seismic stations in China and temporary stations in Tibet and the Tienshan orogenic belt. Significant features well correlated with surface geology are revealed and provide new insights into the deep dynamics beneath China. Prominent high Pn velocities are visible under the stable cratonic blocks (e.g., the Tarim, Junngar, and Sichuan basins, and the Ordos block), whereas remarkable low Pn velocities are observed in the tectonically active areas (e.g., Pamir, the Tienshan orogenic belt, central Tibet and the Qilian fold belt). A distinct N-S trending low Pn velocity zone around 86°E is revealed under the rift running from the Himalayan block through the Lhasa block to the Qiangtang block, which indicates the hot material upwelling due to the breaking-off of the subducting Indian slab. Two N-S trending low Pn velocity belts with an approximate N-S Pn fast direction along the faults around the Chuan-Dian diamond block suggest that these faults may serve as channels of mantle flow from Tibet. The fast Pn direction changes from N-S in the north across 27°N to E-W in the south, which may reflect different types of mantle deformation. The anisotropy in the south could be caused by the asthenospheric flow resulted from the eastward subduction of the Indian plate down to the mantle transition zone beneath the Burma arc. Across the Talas-Fergana fault in the Tienshan orogenic belt, an obvious difference in velocity and anisotropy is revealed. To the west, high Pn velocities and an arc-shaped fast Pn direction are observed, implying the Indo-Asian collision, whereas to the east low Pn velocities and a range-parallel Pn fast direction are imaged, reflecting the northward underthrusting of the Tarim lithosphere and the southward underthrusting of the Kazakh lithosphere. In

  10. Seismic tomography reveals magma chamber location beneath Uturuncu volcano (Bolivia)

    Science.gov (United States)

    Kukarina, Ekaterina; West, Michael; Koulakov, Ivan

    2014-05-01

    Uturuncu volcano belongs to the Altiplano-Puna Volcanic Complex in the central Andes, the product of an ignimbrite ''flare-up''. The region has been the site of large-scale silicic magmatism since 10 Ma, producing 10 major eruptive calderas and edifices, some of which are multiple-eruption resurgent complexes as large as the Yellowstone or Long Valley caldera. Satellite measurements show that the hill has been rising more than half an inch a year for almost 20 years, suggesting that the Uturuncu volcano, which has erupted last time more than 300,000 years ago, is steadily inflating, which makes it fertile ground for study. In 2009 an international multidisciplinary team formed a project called PLUTONS to study Uturuncu. Under this project a 100 km wide seismic network was set around the volcano by seismologists from University of Alaska Fairbanks. Local seismicity is well distributed and provides constraints on the shallow crust. Ray paths from earthquakes in the subducting slab complement this with steep ray paths that sample the deeper crust. Together the shallow and deep earthquakes provide strong 3D coverage of Uturuncu and the surrounding region. To study the deformation source beneath the volcano we performed simultaneous tomographic inversion for the Vp and Vs anomalies and source locations, using the non-linear passive source tomographic code, LOTOS. We estimated both P and S wave velocity structures beneath the entire Uturuncu volcano by using arrival times of P and S waves from more than 600 events registered by 33 stations. To show the reliability of the results, we performed a number of different tests, including checkerboard synthetic tests and tests with odd/even data. Obtained Vp/Vs ratio distribution shows increased values beneath the south Uturuncu, at a depth of about 15 km. We suggest the high ratio anomaly is caused by partial melt, presented in expanding magma chamber, responsible for the volcano inflation. The resulting Vp, Vs and the ratio

  11. The structure and nature of the Moho beneath Central Iberia

    Science.gov (United States)

    Ehsan, Siddique Akhtar; Carbonell, Ramon; Ayarza, Puy; Martí, David; Poyatos, David Martínez; Pérez-Estaún, Andrés

    2015-11-01

    The Moho is the most conspicuous feature in the ALCUDIA deep normal incidence and wide-angle seismic reflection datasets acquired across the Central Iberia Zone. This discontinuity appears to be sub-horizontal with a slight dip toward the center of the Iberian Peninsula, beneath the Tajo Basin. Densely spaced wide-angle seismic reflection data reveal conspicuous PmP and SmS reflections in the shot records. These reflections, arriving over a 1.5 s time window and characterized by a relatively low frequency content, are used to infer the internal structure and characteristics of this crustal boundary in an effort to place constraints on its nature beneath the studied area. The wide-angle shot records were processed in order to generate low-fold stacks that reveal gradual deepening of Moho PmP phases from 10.2 s TWT (~ 31 km) in the Central Iberian Zone to 11.8 s TWT (~ 36 km) beneath the Tajo Basin. The Moho seismic signature was the main objective of a series of 1-D and 2-D synthetic modeling simulations. Reflectivity modeling was used as the 1-D modeling approach and an elastic finite difference scheme was used for the 2-D modeling. The Moho can be considered to be a self-similar/fractal heterogeneous media with a bimodal velocity distribution, alternating crustal and mantle values, with horizontal correlation lengths that range between 1 and 4 km and vertical correlation lengths that range from 0.2 to 1 km. The depth of this boundary is most probably the result of late to post-variscan re-equilibration processes affecting a previously deformed and laminated lower crust. The mechanisms that took part in this process might have differed to the north and south of the sampled Central Iberian Zone, being more thermally induced to the north, near the Central System. Processes leading to the layered structure of the Moho boundary, either tectonic or magmatic, should be further investigated.

  12. Groundwater sustainability assessment in coastal aquifers

    Science.gov (United States)

    Lathashri, U. A.; Mahesha, A.

    2016-08-01

    The present work investigates the response of shallow, coastal unconfined aquifers to anticipated overdraft conditions and climate change effect using numerical simulation. The groundwater flow model MODFLOW and variable density groundwater model SEAWAT are used for this investigation. The transmissivity and specific yield estimated from the existing database range from 10 to 810 m 2/day and 0.08% to 10.92% respectively. After successful calibration with Nash-Sutcliffe efficiency greater than 0.80, the values of horizontal hydraulic conductivity and specific yield of the unconfined aquifer were set in the range 1.85-61.90 m/day and 0.006-0.24 respectively. After validating the model, it is applied for forecasting the aquifer's response to anticipated future scenarios of groundwater draft, recharge rate and sea level rise. The findings of the study illustrate that saltwater intrusion is intensified in the area adjoining the tidal rivers, rather than that due to the sea alone. Of all the scenarios simulated, the immense negative impact on groundwater quality emerges due to overdraft conditions and reduced recharge with the areal extent of seawater intrusion exceeding about 67% (TDS >1 kg/m 3). The study also arrives at the conclusion that, regional sea level rise of 1 mm/year has no impact on the groundwater dynamics of the aquifer.

  13. Steady state phreatic surfaces in sloping aquifers

    Science.gov (United States)

    Loáiciga, Hugo A.

    2005-08-01

    Steady state groundwater flow driven by constant recharge in an unconfined aquifer overlying sloping bedrock is shown to be represented, using the Dupuit approximation, by an ordinary differential equation of the Abel type y(x) . y'(x) + a . y(x) + x = 0, whose analytical solution is derived in this work. This article first investigates the case of zero saturated thickness at the upstream boundary, a flow system reminiscent of perched groundwater created by percolation of precipitation or irrigation in a sloping aquifer fully draining at its downstream boundary. A variant of this flow system occurs when the phreatic surface mounds and produces groundwater discharge toward the upstream boundary. This variant is a generalization of the classical groundwater flow problem involving two lakes connected by an aquifer, the latter being on sloping terrain in this instance. Analytical solutions for the phreatic surface's steady state geometry are derived for the case of monotonically declining hydraulic head as well as for the case of a mounded phreatic surface. These solutions are of practical interest in drainage studies, slope stability, and runoff formation investigations. It is shown that the flow factor a = -$\\sqrt{{\\rm K}/{\\rm N} tan β (where K, N, and tan β are the hydraulic conductivity, vertical recharge, and aquifer slope, respectively) has a commanding role on the phreatic surface's solutions. Two computational examples illustrate the implementation of this article's results.

  14. Transport of nonlinearly biodegradable contaminants in aquifers

    NARCIS (Netherlands)

    Keijzer, H.

    2001-01-01

    This thesis deals with the transport behavior of nonlinearly biodegradable contaminants in aquifers. Such transport occurs during in situ bioremediation which is based on the injection of an electron acceptor or electron donor. The main interests in this thesis are the mutual influences of underlyin

  15. 40 CFR 147.102 - Aquifer exemptions.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 22 2010-07-01 2010-07-01 false Aquifer exemptions. 147.102 Section 147.102 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS...) Granite Point. (ii) McArthur River Field. (iii) Middle Ground Shoal Field. (iv) Trading Bay Field. (3)...

  16. Biogeochemical aspects of aquifer thermal energy storage.

    NARCIS (Netherlands)

    Brons, H.J.

    1992-01-01

    During the process of aquifer thermal energy storage the in situ temperature of the groundwater- sediment system may fluctuate significantly. As a result the groundwater characteristics can be considerably affected by a variety of chemical, biogeochemical and microbiological reactions. The inter

  17. PREDICTING CONTAMINANT MIGRATION IN KARST AQUIFERS

    Science.gov (United States)

    Time-of-travel transport estimation is employed to predict contaminant migration in karst aquifers. stimation of time-of-travel transport is conditioned on the set of hydraulic-flow and geometric parameters that describe different transport processes that occur within karst condu...

  18. Monitoring CO2 gas-phase migration in a shallow sand aquifer using cross-borehole ground penetrating radar

    DEFF Research Database (Denmark)

    Lassen, Rune Nørbæk; Sonnenborg, T.O.; Jensen, Karsten Høgh;

    2015-01-01

    Understanding potential pathways of gaseous CO2 into and through the shallow subsurface from deep geological storage is one of many requirements related to risk assessment of a carbon capture and storage (CCS) site. In this study, a series of field experiments were carried out at a site located in...... Vrøgum in western Denmark. Up to 45 kg of gaseous CO2 was injected into a shallow aquifer approximately 8 m below the groundwater table. In the upper 6 m, the aquifer consisted of fine Aeolian sand underlain by coarser glacial sand. The migration of the gaseous CO2 was tracked using cross-borehole ground...... penetrating radar (GPR). A total of six GPR-boreholes were installed around the injection well and in the dominant flow direction of the groundwater. The GPR measurements were collected before, during, and after the CO2-injection. The GPR method proved to be very sensitive to desaturation of the aquifer when...

  19. Role of Isotopes in the Development of a General Hydrogeological Conceptual Model of the Guarani Aquifer System (Gas)

    International Nuclear Information System (INIS)

    The Guarani Aquifer System (GAS) is one of the most important groundwater reservoirs in South America, and it represents a typical example of a large transboundary aquifer, shared by Argentina, Brazil, Paraguay and Uruguay. Groundwater flow shows a regional trend from north to south, controlled by the topography and regional hydraulic gradients. Recharge occurs in outcrop areas, mainly in the northern and eastern borders of the GAS. Discharge zones were identified in the southern and western borders. Four main hydrodynamic domains are recognized, related to the major tectonic structures of the Parana Basin. The spatial distribution and the large range of stable isotope contents of groundwater in the confined part of the GAS indicate that recharge has occurred under different climatic conditions. Carbon-14 contents above the detection limit are only found along a narrow band parallel to the outcrop areas, indicating the existence of very old groundwaters in the central portion of the aquifer. (author)

  20. The quality of our nation's waters: water quality in the Principal Aquifers of the Piedmont, Blue Ridge, and Valley and Ridge regions, eastern United States, 1993-2009

    Science.gov (United States)

    Lindsey, Bruce D.; Zimmerman, Tammy M.; Chapman, Melinda J.; Cravotta, Charles A., III; Szabo, Zoltan

    2015-01-01

    The aquifers of the Piedmont, Blue Ridge, and Valley and Ridge regions underlie an area with a population of more than 40 million people in 10 states. The suburban and rural population is large, growing rapidly, and increasingly dependent on groundwater as a source of supply, with more than 550 million gallons per day withdrawn from domestic wells for household use. Water from some of these aquifers does not meet human-health benchmarks for drinking water for contaminants with geologic or human sources. Water from samples in crystalline- and siliciclastic-rock aquifers frequently exceeded standards for contaminants with geologic sources, and samples in carbonate-rock aquifers frequently exceeded standards for contaminants with human sources, most often nitrate and bacteria.