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Sample records for aquifers geochemical results

  1. Hydro-geochemical modeling of subalpine urbanized area: geochemical characterization of the shallow and deep aquifers of the urban district of Como (first results).

    Science.gov (United States)

    Terrana, Silvia; Brunamonte, Fabio; Frascoli, Francesca; Ferrario, Maria Francesca; Michetti, Alessandro Maria; Pozzi, Andrea; Gambillara, Roberto; Binda, Gilberto

    2016-04-01

    characterization of both aquifers and the comprehension of the interaction between the shallow one and deep one. The first results of geochemical and hydrological analyses in nine piezometer, seven in the shallow aquifer and two in the deep one, permit to identify a general characterization of groundwater: the waters of both the aquifers are calcium bicarbonate, with discontinuous enrichment in sulphate and silicate. The conductibility values are higher in the shallow aquifer then in the deep aquifer, this is an indication of the high flow rate of the deep one and of the higher level of vulnerability of the shallow water respect the urban pollutant. Particular is also the relatively high temperature for the deep water (15.5°C to 16.1°C). The next steps of work are an increase of geochemical analysis, with trace element, and the correlation with hydro-chemical surface water.

  2. Geochemical evolution processes and water-quality observations based on results of the National Water-Quality Assessment Program in the San Antonio segment of the Edwards aquifer, 1996-2006

    Science.gov (United States)

    Musgrove, MaryLynn; Fahlquist, Lynne; Houston, Natalie A.; Lindgren, Richard J.; Ging, Patricia B.

    2010-01-01

    increase along flow paths; results for samples of Edwards aquifer groundwater show an increase from shallow/urban unconfined, to unconfined, to confined groundwater categories. These differences are consistent with longer residence times and greater extents of water-rock interaction controlling fluid compositions as groundwater evolves from shallow unconfined groundwater to deeper confined groundwater. Results for stable isotopes of hydrogen and oxygen indicate specific geochemical processes affect some groundwater samples, including mixing with downdip saline water, mixing with recent recharge associated with tropical cyclonic storms, or mixing with recharge water than has undergone evaporation. The composition of surface water recharging the aquifer, as well as mixing with downdip water from the Trinity aquifer or the saline zone, also might affect water quality. A time-series record (1938-2006) of discharge at Comal Springs, one of the major aquifer discharge points, indicates an upward trend for nitrate and chloride concentrations, which likely reflects anthropogenic activities. A small number of organic contaminants were routinely or frequently detected in Edwards aquifer groundwater samples. These were the pesticides atrazine, its degradate deethylatrazine, and simazine; the drinking-water disinfection byproduct chloroform; and the solvent tetrachloroethene. Detection of these contaminants was most frequent in samples of the shallow/urban unconfined groundwater category and least frequent in samples of the unconfined groundwater category. Results indicate that the shallow/urban unconfined part of the aquifer is most affected by anthropogenic contaminants and the unconfined part of the aquifer is the least affected. The high frequency of detection for these anthropogenic contaminants aquifer-wide and in samples of deep, confined groundwater indicates that the entire aquifer is susceptible to water-quality changes as a result of anthropogenic activities. L

  3. Potential environmental issues of CO2 storage in deep saline aquifers: Geochemical results from the Frio-I Brine Pilot test, Texas, USA

    Science.gov (United States)

    Kharaka, Yousif K.; Thordsen, James J.; Hovorka, Susan D.; Nance, H. Seay; Cole, David R.; Phelps, Tommy J.; Knauss, Kevin G.

    2009-01-01

    Sedimentary basins in general, and deep saline aquifers in particular, are being investigated as possible repositories for large volumes of anthropogenic CO2 that must be sequestered to mitigate global warming and related climate changes. To investigate the potential for the long-term storage of CO2 in such aquifers, 1600 t of CO2 were injected at 1500 m depth into a 24-m-thick "C" sandstone unit of the Frio Formation, a regional aquifer in the US Gulf Coast. Fluid samples obtained before CO2 injection from the injection well and an observation well 30 m updip showed a Na–Ca–Cl type brine with ∼93,000 mg/L TDS at saturation with CH4 at reservoir conditions; gas analyses showed that CH4 comprised ∼95% of dissolved gas, but CO2 was low at 0.3%. Following CO2 breakthrough, 51 h after injection, samples showed sharp drops in pH (6.5–5.7), pronounced increases in alkalinity (100–3000 mg/L as HCO3) and in Fe (30–1100 mg/L), a slug of very high DOC values, and significant shifts in the isotopic compositions of H2O, DIC, and CH4. These data, coupled with geochemical modeling, indicate corrosion of pipe and well casing as well as rapid dissolution of minerals, especially calcite and iron oxyhydroxides, both caused by lowered pH (initially ∼3.0 at subsurface conditions) of the brine in contact with supercritical CO2.These geochemical parameters, together with perfluorocarbon tracer gases (PFTs), were used to monitor migration of the injected CO2 into the overlying Frio “B”, composed of a 4-m-thick sandstone and separated from the “C” by ∼15 m of shale and siltstone beds. Results obtained from the Frio “B” 6 months after injection gave chemical and isotopic markers that show significant CO2 (2.9% compared with 0.3% CO2 in dissolved gas) migration into the “B” sandstone. Results of samples collected 15 months after injection, however, are ambiguous, and can be interpreted to show no additional injected CO2 in the “B” sandstone

  4. Geochemical processes during managed aquifer recharge with desalinated seawater

    Science.gov (United States)

    Ganot, Y.; Holtzman, R.; Weisbrod, N.; Russak, A.; Katz, Y.; Kurtzman, D.

    2017-12-01

    In this work we study the geochemical processes along the variably-saturated zone during managed aquifer recharge (MAR) with reverse-osmosis desalinated seawater (DSW) to an infiltration pond at the Menashe site, located above the Israeli coastal aquifer. The DSW is post-treated by calcite dissolution (remineralization) in order to meet the Israeli desalinated water quality criteria. Suction cups and monitoring wells inside the pond were used to monitor water quality during two MAR events on 2015 and 2016. Results show that cation exchange is dominant, driven by the high Ca2+ concentration in the post-treated DSW. Stable isotope analysis shows that the composition of the shallow groundwater is similar to the recharged DSW, but with enrichment of Mg2+, Na+, Ca2+ and HCO3-. A calibrated variably-saturated reactive transport model was used to predict the geochemical evolution during 50 years of MAR with two water quality scenarios: post-treated DSW and soft DSW (without post-treatment). The latter scenario was aimed to test soil-aquifer-treatment as an alternative post-treatment technique. In terms of water quality, the results of the two scenarios were found within the range of the desalinated water criteria. Mg2+ enrichment was stable ( 2.5 mg L-1), higher than the zero concentration found in the Israeli DSW. Calcite content reduction was low (<1%) along the variably-saturated profile, after 50 years of MAR. This suggests that using soil-aquifer-treatment as a remineralization technique for DSW is potentially a sustainable practice, which is limited only by the current hydraulic capacity of the Menashe MAR site.

  5. Groundwater sources and geochemical processes in a crystalline fault aquifer

    Science.gov (United States)

    Roques, Clément; Aquilina, Luc; Bour, Olivier; Maréchal, Jean-Christophe; Dewandel, Benoît; Pauwels, Hélène; Labasque, Thierry; Vergnaud-Ayraud, Virginie; Hochreutener, Rebecca

    2014-11-01

    The origin of water flowing in faults and fractures at great depth is poorly known in crystalline media. This paper describes a field study designed to characterize the geochemical compartmentalization of a deep aquifer system constituted by a graben structure where a permeable fault zone was identified. Analyses of the major chemical elements, trace elements, dissolved gases and stable water isotopes reveal the origin of dissolved components for each permeable domain and provide information on various water sources involved during different seasonal regimes. The geochemical response induced by performing a pumping test in the fault-zone is examined, in order to quantify mixing processes and contribution of different permeable domains to the flow. Reactive processes enhanced by the pumped fluxes are also identified and discussed. The fault zone presents different geochemical responses related to changes in hydraulic regime. They are interpreted as different water sources related to various permeable structures within the aquifer. During the low water regime, results suggest mixing of recent water with a clear contribution of older water of inter-glacial origin (recharge temperature around 7 °C), suggesting the involvement of water trapped in a local low-permeability matrix domain or the contribution of large scale circulation loops. During the high water level period, due to inversion of the hydraulic gradient between the major permeable fault zone and its surrounding domains, modern water predominantly flows down to the deep bedrock and ensures recharge at a local scale within the graben. Pumping in a permeable fault zone induces hydraulic connections with storage-reservoirs. The overlaid regolith domain ensures part of the flow rate for long term pumping (around 20% in the present case). During late-time pumping, orthogonal fluxes coming from the fractured domains surrounding the major fault zone are dominant. Storage in the connected fracture network within the

  6. Geochemical investigations and results

    International Nuclear Information System (INIS)

    Herbert, H.J.; Sander, W.

    1986-01-01

    The following information can be derived from results so far for a final store: - With known mineralogy, precise information can be given on the solution metamorphosis processes to be expected. The previous results of this in-situ experiment have confirmed the theoretical considerations. - Sensors were developed and tested, which make possible continuous monitoring under hydrostatic pressure in a final store in the case of incoming solution, i.e. for exploration bores. - The collection of physical and chemical parameters in open sections and shafts creates the basis for assessing the effect of backfilling from the chemical point of view. (orig./PW) [de

  7. Geochemical Triggers of Arsenic Mobilization during Managed Aquifer Recharge.

    Science.gov (United States)

    Fakhreddine, Sarah; Dittmar, Jessica; Phipps, Don; Dadakis, Jason; Fendorf, Scott

    2015-07-07

    Mobilization of arsenic and other trace metal contaminants during managed aquifer recharge (MAR) poses a challenge to maintaining local groundwater quality and to ensuring the viability of aquifer storage and recovery techniques. Arsenic release from sediments into solution has occurred during purified recycled water recharge of shallow aquifers within Orange County, CA. Accordingly, we examine the geochemical processes controlling As desorption and mobilization from shallow, aerated sediments underlying MAR infiltration basins. Further, we conducted a series of batch and column experiments to evaluate recharge water chemistries that minimize the propensity of As desorption from the aquifer sediments. Within the shallow Orange County Groundwater Basin sediments, the divalent cations Ca(2+) and Mg(2+) are critical for limiting arsenic desorption; they promote As (as arsenate) adsorption to the phyllosilicate clay minerals of the aquifer. While native groundwater contains adequate concentrations of dissolved Ca(2+) and Mg(2+), these cations are not present at sufficient concentrations during recharge of highly purified recycled water. Subsequently, the absence of dissolved Ca(2+) and Mg(2+) displaces As from the sediments into solution. Increasing the dosages of common water treatment amendments including quicklime (Ca(OH)2) and dolomitic lime (CaO·MgO) provides recharge water with higher concentrations of Ca(2+) and Mg(2+) ions and subsequently decreases the release of As during infiltration.

  8. 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

  9. Snowmelt induced hydrologic perturbations drive dynamic microbiological and geochemical behaviors across a shallow riparian aquifer

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    Robert eDanczak

    2016-05-01

    Full Text Available Shallow riparian aquifers represent hotspots of biogeochemical activity in the arid western US. While these environments provide extensive ecosystem services, little is known of how natural environmental perturbations influence subsurface microbial communities and associated biogeochemical processes. Over a six-month period we tracked the annual snowmelt-driven incursion of groundwater into the vadose zone of an aquifer adjacent to the Colorado River, leading to increased dissolved oxygen (DO concentrations in the normally suboxic saturated zone. Strong biogeochemical heterogeneity was measured across the site, with abiotic reactions between DO and sulfide minerals driving rapid DO consumption and mobilization of redox active species in reduced aquifer regions. Conversely, extensive DO increases were detected in less reduced sediments. 16S rRNA gene surveys tracked microbial community composition within the aquifer, revealing strong correlations between increases in putative oxygen-utilizing chemolithoautotrophs and heterotrophs and rising DO concentrations. The gradual return to suboxic aquifer conditions favored increasing abundances of 16S rRNA sequences matching members of the Microgenomates (OP11 and Parcubacteria (OD1 that have been strongly implicated in fermentative processes. Microbial community stability measurements indicated that deeper aquifer locations were relatively less affected by geochemical perturbations, while communities in shallower locations exhibited the greatest change. Reactive transport modeling of the geochemical and microbiological results supported field observations, suggesting that a predictive framework can be applied to develop a greater understanding of such environments.

  10. Snowmelt induced hydrologic perturbations drive dynamic microbiological and geochemical behaviors across a shallow riparian aquifer

    Science.gov (United States)

    Danczak, Robert; Yabusaki, Steven; Williams, Kenneth; Fang, Yilin; Hobson, Chad; Wilkins, Michael

    2016-05-01

    Shallow riparian aquifers represent hotspots of biogeochemical activity in the arid western US. While these environments provide extensive ecosystem services, little is known of how natural environmental perturbations influence subsurface microbial communities and associated biogeochemical processes. Over a six-month period we tracked the annual snowmelt-driven incursion of groundwater into the vadose zone of an aquifer adjacent to the Colorado River, leading to increased dissolved oxygen (DO) concentrations in the normally suboxic saturated zone. Strong biogeochemical heterogeneity was measured across the site, with abiotic reactions between DO and sulfide minerals driving rapid DO consumption and mobilization of redox active species in reduced aquifer regions. Conversely, extensive DO increases were detected in less reduced sediments. 16S rRNA gene surveys tracked microbial community composition within the aquifer, revealing strong correlations between increases in putative oxygen-utilizing chemolithoautotrophs and heterotrophs and rising DO concentrations. The gradual return to suboxic aquifer conditions favored increasing abundances of 16S rRNA sequences matching members of the Microgenomates (OP11) and Parcubacteria (OD1) that have been strongly implicated in fermentative processes. Microbial community stability measurements indicated that deeper aquifer locations were relatively less affected by geochemical perturbations, while communities in shallower locations exhibited the greatest change. Reactive transport modeling of the geochemical and microbiological results supported field observations, suggesting that a predictive framework can be applied to develop a greater understanding of such environments.

  11. Geochemical Processes During Managed Aquifer Recharge With Desalinated Seawater

    Science.gov (United States)

    Ganot, Y.; Holtzman, R.; Weisbrod, N.; Russak, A.; Katz, Y.; Kurtzman, D.

    2018-02-01

    We study geochemical processes along the variably-saturated zone during managed aquifer recharge (MAR) with reverse-osmosis desalinated seawater (DSW). The DSW, post-treated at the desalination plant by calcite dissolution (remineralization) to meet the Israeli water quality standards, is recharged into the Israeli Coastal Aquifer through an infiltration pond. Water quality monitoring during two MAR events using suction cups and wells inside the pond indicates that cation exchange is the dominant subsurface reaction, driven by the high Ca2+ concentration in the post-treated DSW. Stable isotope analysis shows that the shallow groundwater composition is similar to the recharged DSW, except for enrichment of Mg2+, Na+, Ca2+, and HCO3-. A calibrated variably-saturated reactive transport model is used to predict the geochemical evolution during 50 years of MAR for two water quality scenarios: (i) post-treated DSW (current practice) and (ii) soft DSW (lacking the remineralization post-treatment process). The latter scenario was aimed to test soil-aquifer-treatment (SAT) as an alternative post-treatment technique. Both scenarios provide an enrichment of ˜2.5 mg L-1 in Mg2+ due to cation exchange, compared to practically zero Mg2+ currently found in the Israeli DSW. Simulations of the alternative SAT scenario provide Ca2+ and HCO3- remineralization due to calcite dissolution at levels that meet the Israeli standard for DSW. The simulated calcite content reduction in the sediments below the infiltration pond after 50 years of MAR was low (<1%). Our findings suggest that remineralization using SAT for DSW is a potentially sustainable practice at MAR sites overlying calcareous sandy aquifers.

  12. Geochemical processes at a fresh/seawater interface in a shallow sandy aquifer

    DEFF Research Database (Denmark)

    Andersen, Martin Søgaard; Iversen, Vibeke Margrethe Nyvang; Postma, Diederik Jan

    2001-01-01

    Chemical processes in a natural fresh-/seawater mixing zone were studied in a shallow sandy aquifer. The dominant redox-processes are sulfate reduction and methanogenesis. Methanogenesis produces CO2, which causes calcite dissolution. The produced calcium induces ion exchange with sodium. The fin...... result of these interactions between different types of geochemical processes is an anoxic groundwater enriched in bicarbonate and sodium.......Chemical processes in a natural fresh-/seawater mixing zone were studied in a shallow sandy aquifer. The dominant redox-processes are sulfate reduction and methanogenesis. Methanogenesis produces CO2, which causes calcite dissolution. The produced calcium induces ion exchange with sodium. The final...

  13. Coastal Aquifer Contamination and Geochemical Processes Evaluation in Tugela Catchment, South Africa—Geochemical and Statistical Approaches

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    Badana Ntanganedzeni

    2018-05-01

    Full Text Available Assessment of groundwater quality, contamination sources and geochemical processes in the coastal aquifer of Tugela Catchment, South Africa were carried out by the geochemical and statistical approach using major ion chemistry of 36 groundwater samples. Results suggest that the spatial distribution pattern of EC, TDS, Na, Mg, Cl and SO4 are homogenous and elevated concentrations are observed in the wells in the coastal region and few wells near the Tugela River. Wells located far from the coast are enriched by Ca, HCO3 and CO3. Durov diagrams, Gibbs plots, ionic ratios, chloro alkaline indices (CAI1 and CAI2 and correlation analysis imply that groundwater chemistry in the coastal aquifer of Tugela Catchment is regulated by the ion exchange, mineral dissolution, saline sources, and wastewater infiltration from domestic sewage; septic tank leakage and irrigation return flow. Principle component analysis also ensured the role of saline and anthropogenic sources and carbonates dissolution on water chemistry. Spatial distributions of factor score also justify the above predictions. Groundwater suitability assessment indicates that around 80% and 90% of wells exceeded the drinking water standards recommended by the WHO and South African drinking water standards (SAWQG, respectively. Based on SAR, RSC, PI, and MH classifications, most of the wells are suitable for irrigation in the study region. USSL classification suggests that groundwater is suitable for coarse-textured soils and salt-tolerant crops. The study recommends that a proper management plan is required to protect this coastal aquifer efficiently.

  14. Principal aquifers can contribute radium to sources of drinking water under certain geochemical conditions

    Science.gov (United States)

    Szabo, Zoltan; Fischer, Jeffrey M.; Hancock, Tracy Connell

    2012-01-01

    What are the most important factors affecting dissolved radium concentrations in principal aquifers used for drinking water in the United States? Study results reveal where radium was detected and how rock type and chemical processes control radium occurrence. Knowledge of the geochemical conditions may help water-resource managers anticipate where radium may be elevated in groundwater and minimize exposure to radium, which contributes to cancer risk. Summary of Major Findings: * Concentrations of radium in principal aquifers used for drinking water throughout the United States generally were below 5 picocuries per liter (pCi/L), the U.S. Environmental Protection Agency (USEPA) maximum contaminant level (MCL) for combined radium - radium-226 (Ra-226) plus radium-228 (Ra-228) - in public water supplies. About 3 percent of sampled wells had combined radium concentrations greater than the MCL. * Elevated concentrations of combined radium were more common in groundwater in the eastern and central United States than in other regions of the Nation. About 98 percent of the wells that contained combined radium at concentrations greater than the MCL were east of the High Plains. * The highest concentrations of combined radium were in the Mid-Continent and Ozark Plateau Cambro-Ordovician aquifer system and the Northern Atlantic Coastal Plain aquifer system. More than 20 percent of sampled wells in these aquifers had combined radium concentrations that were greater than or equal to the MCL. * Concentrations of Ra-226 correlated with those of Ra-228. Radium-226 and Ra-228 occur most frequently together in unconsolidated sand aquifers, and their presence is strongly linked to groundwater chemistry. * Three common geochemical factors are associated with the highest radium concentrations in groundwater: (1) oxygen-poor water, (2) acidic conditions (low pH), and (3) high concentrations of dissolved solids.

  15. 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

  16. Hydrogeological geochemical and isotopic study of the coastal aquifer of Sousse Eastern, Tunisia

    International Nuclear Information System (INIS)

    Ben-Hamouda, M. F.; Carreira, P.; Marques, J. M.; Eggenkamp, H.

    2012-12-01

    At Sahel, near one of the seaside resort available in Tunisia, the water quantity and quality is a major problem ever at southern center of Tunisia. The Oued Laya coastal system is no exception. The levels, a shallow aquifer up to depths of about 60 m whose reservoir is mainly formed by Mio-Pliocnesediments (with some gypsum lenses dispersed within the geological formations) and deep aquifer, situated between 100 and 250 m depth, located in the Miocene sandstone formations. The results of geochemical and isotopic studies have shown that groundwater salinity seems not be linked with the increasing water well's abstraction. In contrast, water mineralization seems to acquired by dissolution of minerals in the aquifer system especially halie and gypsum. Besides ion exchange processes play also an important role in the groundwater mineralization. Therefore, it clearly appears that several sources might contribute with different mineralization to the selenization of the aquifer through the natural recharge and also through the return of water irrigation. The contamination of the Mio-Pliocene shallow aquifer by a mixture with seawater is confirmed, and stable isotopes data do not support the hypothesis of mixing with seawater. (Author)

  17. 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

  18. Geochemical detection of carbon dioxide in dilute aquifers.

    Science.gov (United States)

    Carroll, Susan; Hao, Yue; Aines, Roger

    2009-03-26

    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 10(3) to 2 x 10(6) 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. 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 >or= 10(4) 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 in the lower most permeable unit and does

  19. Geochemical processes in a calcareous sandstone aquifer during managed aquifer recharge with desalinated seawater

    Science.gov (United States)

    Ganot, Yonatan; Russak, Amos; Siebner, Hagar; Bernstein, Anat; Katz, Yoram; Guttman, Jospeh; Kurtzman, Daniel

    2017-04-01

    In the last three years we monitor Managed Aquifer Recharge (MAR) of post-treated desalinated seawater (PTDES) in an infiltration pond, at the Menashe site that overlies the northern part of the Israeli Coastal Aquifer. The PTDES are stabilized with CaCO3 during post-treatment in the desalination plant and their chemical composition differs from those of any other water recharged to the aquifer and of the natural groundwater. We use suction cups in the unsaturated zone, shallow observation wells within the pond and production wells that encircles the MAR Menashe site, to study the geochemical processes during MAR with PTDES. Ion-enrichment (remineralization) of the recharged water was observed in both unsaturated zone and shallow observation wells samples. Enrichment occurs mainly in the first few meters below the pond surface by ion-exchange processes. Mg2+ enrichment is most prominent due to its deficiency in the PTDES. It is explained by ion-exchange with Ca2+, as the PTDES (enriched with Ca2+) infiltrates through a calcareous-sandstone aquifer with various amount of adsorbed Mg2+ (3-27 meq/kg). Hence, the higher concentration of Ca+2 in the PTDES together with its higher affinity to the sediments promotes the release of Mg2+ ions to the recharged water. Water isotopes analysis of the production wells were used to estimate residence time and mixing with local groundwater. At the end of 2016, it was found that the percentage of PTDES in adjacent down-gradient production wells was around 10%, while more distant or up-gradient wells show no mixing with PTDES. The distinct isotope contrast between the recharged desalinated seawater (δ2H=+11.2±0.2‰) and the local groundwater (δ2H ranged from -22.7 to -16.7‰) is a promising tool to evaluate future mixing processes at the Menshae MAR site. Using the Menashe MAR system for remineralization could be beneficial as a primary or complementary post-treatment technique. However, the sustainability of this process is

  20. Geochemical Investigation of the Arbuckle-Simpson Aquifer, South-Central Oklahoma, 2004-06

    Science.gov (United States)

    Christenson, Scott; Hunt, Andrew G.; Parkhurst, David L.

    2009-01-01

    dolomite. The major ion chemistry for these 34 samples is consistent with a set of water-rock interactions. Rainfall infiltrates the soil zone, where the host rock, limestone or dolomite, dissolves as a result of uptake of carbon dioxide gas. Some continued dissolution of dolomite and precipitation of calcite occur as the water flows through the saturated zone. The major ion chemistry of the two samples from wells completed in the confined part of the aquifer indicates the water is a sodium chloride type. Geochemical inverse modeling determined that mixing of calcite-saturated recharge water with brine and dissolving calcite, dolomite, and gypsum accounts for the water composition of these two samples. One of the two samples, collected at Vendome Well in Chickasaw National Recreation Area, had a mixing fraction of brine of about 1 percent. The brine component of the sample at Vendome Well is likely to account for the relatively large concentrations of many of the trace elements (potassium, fluoride, bromide, iodide, ammonia, arsenic, boron, lithium, selenium, and strontium) measured in the water sample. Carbon-14, helium-3/tritium, and chlorofluorocarbons were used to calculate ground-water ages, recharge temperatures, and mixtures of ground water in the Arbuckle-Simpson aquifer. Thirty four of 36 water samples recharged the aquifer after 1950, indicating that water is moving quickly from recharge areas to discharge at streams and springs. Two exceptions to this classification were noted in samples 6 and 15 (Vendome Well). Ground-water ages determined for these two samples by using carbon-14 are 34,000 years (site 6) and 10,500 years (site 15). Concentrations of dissolved argon, neon, and xenon in water samples were used to determine the temperature of the water when it recharged the aquifer. The mean annual air temperature at Ada, Oklahoma, is 16 degrees Celsius (C) and the median temperature of the 30 reconnaissance water samples was 18.1 C. The av

  1. A geochemical approach to determine sources and movement of saline groundwater in a coastal aquifer.

    Science.gov (United States)

    Anders, Robert; Mendez, Gregory O; Futa, Kiyoto; Danskin, Wesley R

    2014-01-01

    Geochemical evaluation of the sources and movement of saline groundwater in coastal aquifers can aid in the initial mapping of the subsurface when geological information is unavailable. Chloride concentrations of groundwater in a coastal aquifer near San Diego, California, range from about 57 to 39,400 mg/L. On the basis of relative proportions of major-ions, the chemical composition is classified as Na-Ca-Cl-SO4, Na-Cl, or Na-Ca-Cl type water. δ(2)H and δ(18)O values range from -47.7‰ to -12.8‰ and from -7.0‰ to -1.2‰, respectively. The isotopically depleted groundwater occurs in the deeper part of the coastal aquifer, and the isotopically enriched groundwater occurs in zones of sea water intrusion. (87)Sr/(86)Sr ratios range from about 0.7050 to 0.7090, and differ between shallower and deeper flow paths in the coastal aquifer. (3)H and (14)C analyses indicate that most of the groundwater was recharged many thousands of years ago. The analysis of multiple chemical and isotopic tracers indicates that the sources and movement of saline groundwater in the San Diego coastal aquifer are dominated by: (1) recharge of local precipitation in relatively shallow parts of the flow system; (2) regional flow of recharge of higher-elevation precipitation along deep flow paths that freshen a previously saline aquifer; and (3) intrusion of sea water that entered the aquifer primarily during premodern times. Two northwest-to-southeast trending sections show the spatial distribution of the different geochemical groups and suggest the subsurface in the coastal aquifer can be separated into two predominant hydrostratigraphic layers. © 2013, National Ground Water Association.

  2. Interaction between shallow and deep aquifers in the Tivoli Plain (Central Italy) enhanced by groundwater extraction: A multi-isotope approach and geochemical modeling

    International Nuclear Information System (INIS)

    Carucci, Valentina; Petitta, Marco; Aravena, Ramon

    2012-01-01

    In the Tivoli Plain (Rome, Central Italy) the interaction between shallow and deep groundwater flow systems enhanced by groundwater extraction has been investigated using isotopic and chemical tracers. A conceptual model of the groundwater flowpaths has been developed and verified by geochemical modeling. A combined hydrogeochemical and isotopic investigation using ion relationships such as DIC/Cl − , Ca/(Ca + Mg)/SO 4 /(SO 4 + HCO 3 ), and environmental isotopes (δ 18 O, δ 2 H, 87 Sr/ 86 Sr, δ 34 S and δ 13 C) was carried out in order to determine the sources of recharge of the aquifer, the origin of solutes and the mixing processes in groundwater of Tivoli Plain. Multivariate statistical methods such as principal component analysis and Cluster analyses have confirmed the existence of different geochemical facies and the role of mixing in the chemical composition of the groundwater. Results indicate that the hydrochemistry of groundwater is characterized by mixing between end-members coming directly from carbonate recharge areas and to groundwater circulating in a deeply buried Meso-Cenozoic carbonate sequence. The travertine aquifer is fed by both flow systems, but a local contribution by direct input in the Plain has also been recognized. The stable isotope data ( 18 O, 2 H, 13 C and 34 S) supports the flow system conceptual model inferred from the geochemical data and represents key data to quantify the geochemical mixing in the different groundwaters of the Plain. The results of numerical modeling (PHREEQC) are consistent with the flowpaths derived from the hydrogeochemical conceptual model. The inverse models performed generated the main geochemical processes occurring in the groundwater flow system, which also included mixing. Geochemical and isotope modeling demonstrate an increasing influence of groundwater from the deeply buried aquifer in the travertine aquifer, enhanced by lowering of the travertine aquifer water table due to quarry pumping.

  3. Effects of Land-Use Change and Managed Aquifer Recharge on Geochemical Reactions with Implications for Groundwater Quantity and Quality in Atoll Island Aquifers, Roi-Namur, Republic of the Marshall Islands

    Science.gov (United States)

    Hejazian, M.; Swarzenski, P. W.; Gurdak, J. J.; Odigie, K. O.; Storlazzi, C. D.

    2015-12-01

    This study compares the hydrogeochemistry of two contrasting atoll groundwater systems in Roi-Namur, Republic of the Marshall Islands. Roi-Namur houses a U.S. Department of Defense military installation and presents an ideal study location where a human impacted aquifer is co-located next to a natural aquifer as part of two artificially conjoined atoll islands. The hydrogeology and geochemistry of carbonate atoll aquifers has been well studied, particularly because of its small, well-defined hydrologic system that allows for relatively precise modeling. However, it is unknown how changes in land-use/land cover and managed aquifer recharge (MAR) alters natural geochemical processes in atoll aquifers. A better understanding of this has implications on groundwater quantity and quality, carbonate dissolution, and best aquifer management practices in the context of rising sea level and saltwater intrusion. Roi has been heavily modified to house military and civilian operations; here, lack of vegetation and managed recharge has increased the volume of potable groundwater and affected the geochemical processes in the freshwater lens and saltwater transition zone. Namur is heavily vegetated and the hydrogeology is indicative of a natural atoll island. A suite of monitoring wells were sampled across both island settings for major ions, nutrients, trace elements, DOC/DIC, δ13C and δ18O/2H isotopes. By modeling geochemical reactions using a conservative mixing approach, we measure deviations from expected reactions and compare the two contrasting settings using derived geochemical profiles through a wide salinity spectrum. Results indicate that groundwater on Namur is more heavily depleted in δ13C and has greater dissolved inorganic carbon, suggesting higher microbial oxidation and greater dissolution within the carbonate aquifer. This suggests MAR and reduction of vegetation makes the groundwater supply on atoll islands more resilient to sea level rise.

  4. Some results of NURE uranium geochemical studies

    International Nuclear Information System (INIS)

    Price, V. Jr.

    1979-01-01

    Some technical developments of the National Uranium Resource Evaluation Program which are of general application in geochemical exploration are being studied. Results of stream water and suspended and bottom sediment analyses are compared for an area near Williamsport, Pennsylvania. Variations of uranium content of water samples with time in the North Carolina Piedmont are seen to correlate with rainfall. Ground water samples from coastal and piedmont areas were analyzed for helium. All media sampled provide useful information when properly analyzed and interpreted as part of a total geological analysis of an area

  5. Geochemical evolution of groundwater in carbonate aquifers of southern Latium region, central Italy

    Directory of Open Access Journals (Sweden)

    Giuseppe Sappa

    2013-03-01

    Full Text Available Spring and well water samples, from carbonate aquifers of Latium region, have been characterized to determine the hydrochemical processes governing the evolution of the groundwater. Most of the spring samples, issuing from Lepini, Ausoni and Aurunci Mts., are characterized as alkaline earth HCO3 waters, however, some samples show a composition of Cl--SO4 -- alkaline earth waters. Groundwater samples from Pontina Plain shows three different hydrochemical facies: alkaline earth HCO3 type, Cl-- SO4 -- alkaline earth type and Cl--SO4 -- alkaline type waters. Geochemical modeling and saturation index computation of the sampled waters show an interaction with calcareous and calcareous-dolomitic lithologies. Most of the springs and wells was kinetically saturated with respect to calcite and dolomite, and all the samples were below the equilibrium state with gypsum. This indicates that the groundwater has capacity to dissolve the gypsum along the flow paths. The electrical conductivity and Cl- concentrations of the sampled waters show a positive trend with the decrease in the distance from the coast, highlighting seawater intrusion in the coastal area. According to hydrochemistry results and geochemical modeling, the dominant factors in controlling the hydrochemical characteristics of groundwater are: (i water rock interaction with calcareous and calcareous-dolomitic lithologies; (ii seawater intrusion in the coastal area; (iii dissolution and/or precipitation of carbonate and (i.e. dolomite and calcite evaporate minerals (gypsum determined by saturation indexes; (iv mineral weathering process; (the high Mg/Ca ratio due to the weathering of Mg-rich dolomite.

  6. Geochemical prospect ion results of Treinta y Tres aerial photo

    International Nuclear Information System (INIS)

    Zeegers, H.; Bonnefoy, D.; Garau, M.; Spangenberg, J.

    1981-01-01

    This report shows the geochemical prospect ion results carried out within the framework of the multielemental geochemical strategy. The samples were studied by e spectrometry in the laboratories of Orleans.

  7. Geochemical Characterization of the Upper and Middle Floridan Aquifer System, South Florida

    Science.gov (United States)

    Mirecki, J.; Richardson, E.; Bennett, M.; Hendel, J.

    2008-05-01

    Our study focus is to characterize the water quality and geochemical environment of the Floridan Aquifer System (FAS) throughout the regional flowpath. A synoptic survey of 21 wells (n=15, upper FAS; n=6 middle FAS) was supplemented by additional samples (n=11) obtained during exploratory well development at 4 aquifer storage recovery (ASR) pilot sites. Synoptic survey samples were analyzed intensively, yielding a dataset that consists of major and trace dissolved constituents (including metals), stable isotopes (δ18O, δ13C, δD, δ34S in sulfate and sulfide), carbon species (carbonate alkalinity and organic carbon), uranium-series radionuclides, nutrients, and selected microbes and pathogens. The objectives of this study are three-fold: 1) to provide baseline water-quality and geochemical information prior to initiation of ASR activities that are part of the Comprehensive Everglades Restoration Plan; 2) to quantify the major controls on geochemical evolution along upper and middle FAS flowpaths using geochemical modeling methods; and 3) to identify areas where water- quality may limit the feasibility of ASR methods in the FAS. Preliminary interpretations water quality changes along the regional FAS flowpath can be summarized as follows. Concentrations of dissolved constituents increase from north to south along the flow path; generally, the upper FAS has lower total dissolved solids than the middle FAS at locations where well pairs were analyzed. The redox environment changes from oxic to strongly anoxic, very close to the recharge area. Redox measurements, dissolved iron, sulfide, and sulfur isotope data are consistent with sulfate-reducing conditions. Uranium-series isotope concentrations and activities generally are below regulatory criteria, with few exceptions in both the upper and middle FAS. Areas with greater radionuclide activity occur primarily at distal flowpath locations or at the coast.

  8. Geochemical studies of backfill aggregates, lake sediment cores and the Hueco Bolson Aquifer

    Science.gov (United States)

    Thapalia, Anita

    This dissertation comprises of three different researches that focuses on the application of geochemistry from aggregates, lake sediment cores and Hueco Bolson Aquifer. Each study is independent and presented in the publication format. The first chapter is already published and the second chapter is in revision phase. Overall, three studies measure the large scale (field) as well as bench scale (lab) water-rock interactions influenced by the climatic and anthropogenic factors spans from the field of environmental geology to civil engineering. The first chapter of this dissertation addresses the chemical evaluation of coarse aggregates from six different quarries in Texas. The goal of this work is to find out the best geochemical methods for assessing the corrosion potential of coarse aggregates prior to their use in mechanically stabilized earth walls. Electrochemical parameters help to define the corrosion potential of aggregates following two different leaching protocols. Testing the coarse and fine aggregates demonstrate the chemical difference due to size-related kinetic leaching effects. Field fines also show different chemistry than the bulk rock indicating the weathering impact on carbonate rocks. The second chapter investigates zinc (Zn) isotopic signatures from eight lake sediment cores collected both from pristine lakes and those impacted by urban anthropogenic contamination. Zinc from the natural weathering of rocks and anthropogenic atmospheric pollutants are transported to these lakes and the signatures are recorded in the sediments. Isotopic analysis of core samples provides the signature of anthropogenic contamination sources. Dated sediment core and isotopic analysis can identify Zn inputs that are correlated to the landuse and population change of the watersheds. Comparison of isotopic data from both pristine and urban lake sediment core also serves as an analog in other lake sediment cores in the world. The third chapter studies on Hueco Bolson

  9. Occurrence and geochemical behavior of arsenic in a coastal aquifer-aquitard system of the Pearl River Delta, China

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ya [Department of Earth Sciences, The University of Hong Kong, Hong Kong (China); Jiao, Jiu Jimmy, E-mail: jjiao@hku.hk [Department of Earth Sciences, The University of Hong Kong, Hong Kong (China); Cherry, John A. [School of Engineering, University of Guelph, Guelph, ON, Canada N1G 2W1 (Canada)

    2012-06-15

    Elevated concentrations of arsenic, up to 161 {mu}g/L, have been identified in groundwater samples from the confined basal aquifer underlying the aquitard of the Pearl River Delta (PRD). Both aquatic arsenic in pore water and solid arsenic in the sediments in the basal aquifer and aquitard were identified. Arsenic speciation of groundwater in the basal aquifer was elucidated on a pH-Eh diagram. In the PRD, arsenic is enriched in groundwater having both low and high salinity, and arsenic enriched groundwater is devoid of dissolved oxygen, has negative Eh values, is slightly alkaline, and has abnormally high concentrations of ammonium and dissolved organic carbon, but low concentrations of nitrate and nitrite. Results of geochemical and hydrochemical analyses and sequential extraction analysis suggest that reductive dissolution of iron oxyhydroxide could be one of the important processes that mobilized solid arsenic. We speculate that mineralization of sedimentary organic matter could also contribute to aquatic arsenic. Scanning electron microscope analysis confirms that abundant authigenic pyrite is present in the sediments. Sulphate derived from paleo-seawater served as the important sulfur source for authigenic pyrite formation. Co-precipitation of arsenic with authigenic pyrite significantly controlled concentrations of aquatic arsenic in the coastal aquifer-aquitard system. - Highlights: Black-Right-Pointing-Pointer Coastal aquifer and aquitard are treated as an integrate system. Black-Right-Pointing-Pointer Both aquatic arsenic and solid arsenic are observed. Black-Right-Pointing-Pointer Aquatic arsenic is derived from reductive dissolution of iron oxyhydroxide. Black-Right-Pointing-Pointer Aquatic arsenic can also derived from mineralization of sedimentary organic matter. Black-Right-Pointing-Pointer Co-precipitation of arsenic with authigenic pyrite is significant in such a system.

  10. Microbial diversity and impact on carbonate geochemistry across a changing geochemical gradient in a karst aquifer.

    Science.gov (United States)

    Gray, Cassie J; Engel, Annette S

    2013-02-01

    Although microbes are known to influence karst (carbonate) aquifer ecosystem-level processes, comparatively little information is available regarding the diversity of microbial activities that could influence water quality and geological modification. To assess microbial diversity in the context of aquifer geochemistry, we coupled 16S rRNA Sanger sequencing and 454 tag pyrosequencing to in situ microcosm experiments from wells that cross the transition from fresh to saline and sulfidic water in the Edwards Aquifer of central Texas, one of the largest karst aquifers in the United States. The distribution of microbial groups across the transition zone correlated with dissolved oxygen and sulfide concentration, and significant variations in community composition were explained by local carbonate geochemistry, specifically calcium concentration and alkalinity. The waters were supersaturated with respect to prevalent aquifer minerals, calcite and dolomite, but in situ microcosm experiments containing these minerals revealed significant mass loss from dissolution when colonized by microbes. Despite differences in cell density on the experimental surfaces, carbonate loss was greater from freshwater wells than saline, sulfidic wells. However, as cell density increased, which was correlated to and controlled by local geochemistry, dissolution rates decreased. Surface colonization by metabolically active cells promotes dissolution by creating local disequilibria between bulk aquifer fluids and mineral surfaces, but this also controls rates of karst aquifer modification. These results expand our understanding of microbial diversity in karst aquifers and emphasize the importance of evaluating active microbial processes that could affect carbonate weathering in the subsurface.

  11. Geochemical controls on fluoriferous groundwaters of the Pliocene and the more recent aquifers: The case of Aigion region, Greece

    Science.gov (United States)

    Katsanou, K.; Siavalas, G.; Lambrakis, N.

    2013-12-01

    High fluoride concentrations (> 8 mg/L) in the groundwater of the Plio-Pleistocene sediments are rare; however, this is the case around Aigion town, where teeth fluorosis has been detected since the 80s. Aiming to investigate the origin and the mobility mechanism of fluorine in groundwater and sediments a hydrogeological and geochemical research has been conducted. The hydrogeological research revealed that the Na-HCO3 water type of boreholes aligned along a fault and hosted in the confined aquifers display the higher fluoride content. The unconfined aquifer is mostly dominated by Na-Ca-Mg-HCO3-SO4 water, which displays much lower fluoride concentrations. The most permeable sectors of this aquifer host fresh water of Ca-HCO3 type. The geochemical research revealed significant amount of fluorine in the base of a lignite sequence hosted in the Plio-Pleistocene sediments.

  12. Identifying and quantifying geochemical and mixing processes in the Matanza-Riachuelo Aquifer System, Argentina.

    Science.gov (United States)

    Armengol, S; Manzano, M; Bea, S A; Martínez, S

    2017-12-01

    The Matanza-Riachuelo River Basin, in the Northeast of the Buenos Aires Province, is one of the most industrialized and populated region in Argentina and it is worldwide known for its alarming environmental degradation. In order to prevent further damages, the aquifer system, which consists of two overlaid aquifers, is being monitored from 2008 by the river basin authority, Autoridad de la Cuenca Matanza-Riachuelo. The groundwater chemical baseline has been established in a previous paper (Zabala et al., 2016), and this one is devoted to the identification of the main physical and hydrogeochemical processes that control groundwater chemistry and its areal distribution. Thirty five representative groundwater samples from the Upper Aquifer and thirty four from the deep Puelche Aquifer have been studied with a multi-tool approach to understand the origin of their chemical and isotopic values. The resulting conceptual model has been validated though hydrogeochemical modeling. Most of the aquifer system has fresh groundwater, but some areas have brackish and salt groundwater. Water recharging the Upper Aquifer is of the Ca-HCO 3 type as a result of soil CO 2 and carbonate dissolution. Evapotranspiration plays a great role concentrating recharge water. After recharge, groundwater becomes Na-HCO 3 , mostly due to cation exchange with Na release and Ca uptake, which induces calcite dissolution. Saline groundwaters exist in the lower and upper sectors of the basin as a result of Na-HCO 3 water mixing with marine water of different origins. In the upper reaches, besides mixing with connate sea water other sources of SO 4 exist, most probably gypsum and/or sulfides. This work highlights the relevance of performing detailed studies to understand the processes controlling groundwater chemistry at regional scale. Moreover, it is a step forward in the knowledge of the aquifer system, and provides a sound scientific basis to design effective management programs and recovery plans

  13. Modelling of Pesticide Transport During An Injection Experiment In A Physical and Geochemical Heterogeneous Aquifer

    Science.gov (United States)

    Hojberg, A. L.; Engesgaard, P.; Bjerg, P. L.

    The fate of selected pesticides under natural groundwater conditions was studied by natural gradient short and long term injection experiments in a shallow uncon- fined aerobic aquifer. Bentazone, DNOC, MCPP, dichlorprop, isoproturon, and BAM (dichlobenil metabolite) were injected in aqueous solution with bromide as a nonre- active tracer. The Bromide and pesticide plumes were sampled during the initial 25 m of migration in a dense monitoring net of multilevel samplers. The aquifer was physical and geochemical heterogeneous, which affected transport of several of the pesticides. A 3D reactive transport code was developed including one- and two-site linear/nonlinear equilibrium/nonequilibrium sorption and first-order as well as single Monod degradation kinetic coupled to microbial growth. Model simulations demon- strated that microbial growth was likely supported by the phenoxy acids MCPP and dichlorprop, while degradation of DNOC was adequately described by first-order degradation with no initial lag time. An observed vertical increase in pH was observed at the site and implemented in the transport code. The numerical analysis indicated that degradation of the three degradable pesticides may have been affected by vertical pH variations. Spatial variability in observed DNOC sorption was similarly suspected to be an effect of varying pH. pH dependency on DNOC sorption was confirmed by the model recognized by a match to observed breakthrough at the individual sampling points, when pH variation was included in the simulations.

  14. Ground-water-quality assessment of the Central Oklahoma Aquifer, Oklahoma: geochemical and geohydrologic investigations

    Science.gov (United States)

    Parkhurst, David L.; Christenson, Scott C.; Breit, George N.

    1993-01-01

    The National Water-Quality Assessment pilot project for the Central Oklahoma aquifer examined the chemical and isotopic composition of ground water, the abundances and textures of minerals in core samples, and water levels and hydraulic properties in the flow system to identify geochemical reactions occurring in the aquifer and rates and directions of ground-water flow. The aquifer underlies 3,000 square miles of central Oklahoma and consists of Permian red beds, including parts of the Permian Garber Sandstone, Wellington Formation, and Chase, Council Grove, and Admire Groups, and Quaternary alluvium and terrace deposits.In the part of the Garber Sandstone and Wellington Formation that is not confined by the Permian Hennessey Group, calcium, magnesium, and bicarbonate are the dominant ions in ground water; in the confined part of the Garber Sandstone and Wellington Formation and in the Chase, Council Grove, and Admire Groups, sodium and bicarbonate are the dominant ions in ground water. Nearly all of the Central Oklahoma aquifer has an oxic or post-oxic environment as indicated by the large dissolved concentrations of oxygen, nitrate, arsenic(V), chromium(VI), selenium(VI), vanadium, and uranium. Sulfidic and methanic environments are virtually absent.Petrographic textures indicate dolomite, calcite, sodic plagioclase, potassium feldspars, chlorite, rock fragments, and micas are dissolving, and iron oxides, manganese oxides, kaolinite, and quartz are precipitating. Variations in the quantity of exchangeable sodium in clays indicate that cation exchange is occurring within the aquifer. Gypsum may dissolve locally within the aquifer, as indicated by ground water with large concentra-tions of sulfate, but gypsum was not observed in core samples. Rainwater is not a major source for most elements in ground water, but evapotranspiration could cause rainwater to be a significant source of potassium, sulfate, phosphate and nitrogen species. Brines derived from seawater are

  15. Isotopic and geochemical evidence of recharge sources and water quality in the Quaternary aquifer beneath Jinchang city, NW China

    International Nuclear Information System (INIS)

    Ma Jinzhu; Pan Feng; Chen Lihua; Edmunds, W. Mike; Ding Zhenyu; He Jianhua; Zhou Kunpeng; Huang Tianming

    2010-01-01

    Multiple isotopic and hydrogeochemical tracers were utilized to understand the recharge sources and geochemical evolution of groundwater in the Quaternary aquifer beneath Jinchang city and the adjacent Gobi desert area. The groundwater shows markedly depleted stable isotopic composition compared to modern rainfall. The signature of groundwaters from Jinchang and the northern Gobi desert area differ clearly from that of the alluvial fan in the south Yongchang basin and modern rainfall, and has lower or non-detectable 3 H activity, implying that the aquifer is likely maintained by palaeowater. This groundwater in the Gobi desert has a 14 C age older than 12 ka, indicating that the groundwater resources are non-renewable. The build-up of dissolved solids through evaporation is a major control on groundwater composition, and the dominant anion species change systematically from HCO 3 - , SO 4 2- to Cl - , but cations from weathering of albite, calcite, dolomite and gypsum also make a significant contribution. The scientific results have important implications for groundwater management in Jinchang city and as well as in the Shiyang River basin under China's West Development Strategy. It is recommended that the water allocation program of diverting water from the Dongda river to the Minqin basin be reconsidered.

  16. Geochemical effects of CO2 sequestration in sandstones under simulated in situ conditions of deep saline aquifers

    International Nuclear Information System (INIS)

    Wigand, M.; Carey, J.W.; Schuett, H.; Spangenberg, E.; Erzinger, J.

    2008-01-01

    The geochemical effects of brine and supercritical CO 2 (SCCO 2 ) on reservoir rocks from deep (1500-2000 m) saline aquifers were examined via experimental simulation at in situ conditions. Dry sandstone samples were mounted in a triaxial cell and autoclave system, evacuated, and saturated with 1 M NaCl solution. The brine-rock system was allowed to react at 30 MPa confining pressure, 15 MPa pore fluid pressure, and 60 deg. C while SCCO 2 was injected at a pressure gradient of 1-2 MPa. The experiment was conducted for a period of 1496 h, during which fluids were periodically sampled and analyzed. The pH measured in partially degassed fluid samples at 25 deg. C decreased from a starting value of 7.0-4.3 (9 days) and finally 5.1 after saturation with SCCO 2 . Fluid analyses indicate that most of the major (e.g. Ca, Mg, Fe, Mn) and trace elements (e.g. Sr, Ba, Pb) of the sandstone increase in concentration during the reaction with brine and SCCO 2 . These results are supported by scanning electron microscopy which indicates dissolution of dolomite cement, K-feldspar, and albite. In addition to dissolution reactions the formation of montmorillonite was observed. By adjusting surface area and reaction rates of dissolution and precipitation, geochemical modeling of the experiments could reproduce long-term trends in solution chemistry and indicated limited rates of dissolution as the system remained strongly undersaturated with most minerals, including carbonates. The geochemical models could not account for decreases in concentration of some elements, changes in solution composition resulting from changes in imposed pressure gradient, and the observed Ca/Mg and Si/Al ratios in solution

  17. Geochemical prospect ion results of Mariscala aerial photo

    International Nuclear Information System (INIS)

    Filippini, J.

    1989-01-01

    This report shows the geochemical prospect ion results carried out within the framework of the metalical mining prospect ion in Mariscala aerial photo. Lavalleja district belong to the Mining inventory programme of Uruguay.

  18. Geochemical and flow modelling as tools in monitoring managed aquifer recharge

    International Nuclear Information System (INIS)

    Niinikoski, Paula; Saraperä, Sami; Hendriksson, Nina; Karhu, Juha A.

    2016-01-01

    Due to a growing world population and the effects of anthropogenic climate change, access to clean water is a growing global concern. Managed aquifer recharge (MAR) is a method that can help society's response to this increasing demand for pure water. In MAR, the groundwater resources are replenished and the quality of the recharged surface water is improved through effects such as the removal of organic matter. This removal occurs through mechanisms such as microbial decomposition, which can be monitored by studying the isotopic composition of dissolved inorganic carbon (DIC). Nevertheless, the monitoring can be difficult when there are other factors, like dissolving calcite, affecting the isotopic composition of DIC. The aims of this study were to establish a method for monitoring the decomposition of organic matter (dissolved organic carbon – DOC) in cases where calcite dissolution adds another component to the DIC pool, and to use this method to monitor the beginning and amount of DOC decomposition on a MAR site at Virttaankangas, southwestern Finland. To achieve this, we calculated the mean residence times of infiltrated water in the aquifer and the fractions of this water reaching observation wells. We conducted geochemical modelling, using PHREEQC, to estimate the amount of DOC decomposition and the mineral reactions affecting the quality of the water. - Highlights: • The decomposition of DOC in MAR systems is residence time dependent. • High pH environment can delay the beginning of the decomposition process. • Shortest travel times do not correlate with mean residence times in MAR systems.

  19. Preliminary delineation of natural geochemical reactions, Snake River Plain aquifer system, Idaho National Engineering Laboratory and vicinity, Idaho

    International Nuclear Information System (INIS)

    Knobel, L.L.; Bartholomay, R.C.; Orr, B.R.

    1997-05-01

    The U.S. Geological Survey, in cooperation with the U.S. Department of Energy, is conducting a study to determine the natural geochemistry of the Snake River Plain aquifer system at the Idaho National Engineering Laboratory (INEL), Idaho. As part of this study, a group of geochemical reactions that partially control the natural chemistry of ground water at the INEL were identified. Mineralogy of the aquifer matrix was determined using X-ray diffraction and thin-section analysis and theoretical stabilities of the minerals were used to identify potential solid-phase reactants and products of the reactions. The reactants and products that have an important contribution to the natural geochemistry include labradorite, olivine, pyroxene, smectite, calcite, ferric oxyhydroxide, and several silica phases. To further identify the reactions, analyses of 22 representative water samples from sites tapping the Snake River Plain aquifer system were used to determine the thermodynamic condition of the ground water relative to the minerals in the framework of the aquifer system. Principal reactions modifying the natural geochemical system include congruent dissolution of olivine, diopside, amorphous silica, and anhydrite; incongruent dissolution of labradorite with calcium montmorillonite as a residual product; precipitation of calcite and ferric oxyhydroxide; and oxidation of ferrous iron to ferric iron. Cation exchange reactions retard the downward movement of heavy, multivalent waste constituents where infiltration ponds are used for waste disposal

  20. Effects of Subsurface Microbial Ecology on Geochemical Evolution of a Crude-Oil Contaminated Aquifer

    Science.gov (United States)

    Bekins, B. A.; Cozzarelli, I. M.; Godsy, E. M.; Warren, E.; Hostettler, F. D.

    2001-12-01

    We have identified several subsurface habitats for microorganisms in a crude oil contaminated located near Bemidji, Minnesota. These aquifer habitats include: 1) the unsaturated zone contaminated by hydrocarbon vapors, 2) the zones containing separate-phase crude oil, and 3) the aqueous-phase contaminant plume. The surficial glacial outwash aquifer was contaminated when a crude oil pipeline burst in 1979. We analyzed sediment samples from the contaminated aquifer for the most probable numbers of aerobes, iron reducers, fermenters, and three types of methanogens. The microbial data were then related to gas, water, and oil chemistry, sediment extractable iron, and permeability. The microbial populations in the various contaminated subsurface habitats each have special characteristics and these affect the aquifer and contaminant chemistry. In the eight-meter-thick, vapor-contaminated vadose zone, a substantial aerobic population has developed that is supported by hydrocarbon vapors and methane. Microbial numbers peak in locations where access to both hydrocarbons and nutrients infiltrating from the surface is maximized. The activity of this population prevents hydrocarbon vapors from reaching the land surface. In the zone where separate-phase crude oil is present, a consortium of methanogens and fermenters dominates the populations both above and below the water table. Moreover, gas concentration data indicate that methane production has been active in the oily zone since at least 1986. Analyses of the extracted separate-phase oil show that substantial degradation of C15 -C35 n-alkanes has occurred since 1983, raising the possibility that significant degradation of C15 and higher n-alkanes has occurred under methanogenic conditions. However, lab and field data suggest that toxic inhibition by crude oil results in fewer acetate-utilizing methanogens within and adjacent to the separate-phase oil. Data from this and other sites indicate that toxic inhibition of

  1. Geochemical evidence for groundwater behavior in an unconfined aquifer, south Florida

    Science.gov (United States)

    Meyers, Jayson B.; Swart, Peter K.; Meyers', Janet L.

    1993-07-01

    Five well sites have been investigated along an east-west transect across the surfical aquifer system (SAS) of south Florida. Differences between rainfall during wet seasons (June-October) and evaporation during dry seasons (November-May) give surface waters of this region isotopically light ( δ 18O -22‰ and δ D -7.6‰ ) and heavy ( δ 18O +4.2‰ ) compositions, respectively. Surface waters and shallow groundwaters are enriched in 18O and D to the west, which is consistent with westward decrease in equal excess of rainfall. In the shallow portion of the SAS (less than 20 m, Biscayne sub-aquifer) heterogeneous stable isotopic compositions occur over short spans of time (less than 90 days), reflecting seasonal changes in the isotopic composition of recharge and rapid flushing. Homogeneous stable isotopic compositions occur below the Biscayne sub-aquifer, marking the zone of delayed circulation. Surface evaporation calculated from a stable isotope evaporation model agrees with previously published estimates of 75-95% by physical evaporation measurements and water budget calculations. This model contains many parameters that are assumed to be mean values, but short-term variability in some of these parameters may make this model unsuitable for the application of yearly mean values. For the Everglades, changes in the isotopic composition of atmospheric vapor during the dry season may cause the model to yield anomalous results when annual mean values are used. Chloride-enriched waters (more than 280 mg 1 -1) form a plume emanating from the bottom central portion of the transect. Elevated chloride concentration and light stable isotopic composition ( δ 18O ≈ -2‰ , δ D ≈ -8‰ ) suggest this plume is probably caused not by salinity of residual seawater in the aquifer, but by leakage from the minor artesian water-bearing zone of the Floridan aquifer system. Stable isotope values from Floridan aquifer groundwater plot close to the meteoric water line, in the

  2. Rock–water interactions and pollution processes in the volcanic aquifer system of Guadalajara, Mexico, using inverse geochemical modeling

    International Nuclear Information System (INIS)

    Morán-Ramírez, J.; Ledesma-Ruiz, R.; Mahlknecht, J.; Ramos-Leal, J.A.

    2016-01-01

    In order to understand and mitigate the deterioration of water quality in the aquifer system underlying Guadalajara metropolitan area, an investigation was performed developing geochemical evolution models for assessment of groundwater chemical processes. The models helped not only to conceptualize the groundwater geochemistry, but also to evaluate the relative influence of anthropogenic inputs and natural sources of salinity to the groundwater. Mixing processes, ion exchange, water–rock–water interactions and nitrate pollution and denitrification were identified and confirmed using mass-balance models constraint by information on hydrogeology, groundwater chemistry, lithology and stability of geochemical phases. The water–rock interactions in the volcanic setting produced a dominant Na−HCO_3 water type, followed by Na−Mg−Ca−HCO_3 and Na−Ca−HCO_3. For geochemical evolution modeling, flow sections were selected representing recharge and non-recharge processes and a variety of mixing conditions. Recharge processes are dominated by dissolution of soil CO_2 gas, calcite, gypsum, albite and biotite, and Ca/Na exchange. Non-recharge processes show that the production of carbonic acid and Ca/Na exchange are decreasing, while other minerals such as halite and amorphous SiO_2 are precipitated. The origin of nitrate pollution in groundwater are fertilizers in rural plots and wastewater and waste disposal in the urban area. This investigation may help water authorities to adequately address and manage groundwater contamination. - Highlights: • The Inverse geochemical modeling was used to study to processes occurring in a volcanic aquifer. • Three flow sections were selected to apply inverse hydrogeochemical modeling. • Three main groundwater flows were identified: a local, intermediate and regional flow. • The models show that in the study area that groundwater is mixed with local recharge. • In the south, the aquifer has thermal influence.

  3. Geochemical and Isotopic Characteristics of Quaternary Aquifer in Sohag District, Upper Egypt

    International Nuclear Information System (INIS)

    Ahmed, M.A.

    2008-01-01

    Thc Nile River valley represent one of the most important regions for agriculture and land reclamation in our area. Environmental isotopes and hydrochemical compositions in conjunction with geological and hydrogeological data were used to define chemical characteristics, sources of salinity, ground water origin and the possible recharge sources to the Nile Valley aquifer in Sohag district, Upper Egypt. The total dissolved solids of the ground water samples have higher values (445-7828 mg/L) than surface water (291-348 mg/L). The ground water in the Nile flood plain is very similar to that of the river water except at the margins of the basin. This ground water contains isotopic contents comparable to the river Nile with low TDS. The change of water quality at the old alluvium plain could be due to extensive use of fertilizers to improve soil characteristics in new reclamation area. Mineral saturation indices suggest that the dissolution of evaporites and halite is significant in the ground water and responsible for most of the ground water salinization. The relationships between Na + ,Cl - , Ca 2+ , Mg 2+ ,HCO 3 - and SO 4 2- show that complex geochemical processes control the chemical history of ground water: (I) continuous dissolution of evaporites and halite and precipitation of carbonate rocks, (2) cation exchange between ground water and clay minerals, (3) excessive use of fertilizers rich in MgSO 4 in the reclamation projects. The isotopic contents of surface water raged from 2.03 to 2.93%0 for δ 18 O, from 15.3 to 28.4%0 for δ 3 H, and from 4.6 to 7.8 TU for tritium while the isotopic contents of ground water ranged from -8,41 to 3,86% o for δ 18 O, from -67.8 to 29.9%0 for δ 2 H, and from 0.5 to 11.3 TU for tritium. The isotopic data reveals that the rechargability of this water is attributed to Nile flood water which was depleted in its isotopic content. Significant contribution from the palaeowater, which stored in the Nubia sandstone aquifer system

  4. 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)

    Ben Ammar, Safouan

    2007-01-01

    In the semiarid central part of Tunisia the water resources are becoming increasingly rare because of the scarcity and irregularity of the precipitation and a steadily growing need for fresh water. This study addresses the use of geochemical and isotopic data to analyze the relationship between the El Haouareb dam and the Ain El Beidha and the Kairouan alluvial plain aquifers systems for durable groundwater management. In the Ain El Beidha basin the hydrogeological and geochemical investigations showed that: - The general direction of the groundwater flow is mainly from the SW to the NE, i.e. towards the hydraulic sill of El Haouareb which allows the connection between the Ain El Beidha basin and the Kairouan plain, - The salinity distribution displays a zonation in apparent relationship with the lithological variation of the aquifer formation, - Mineral exchange between groundwater and the aquifer matrix is the dominant process in determining groundwater salinity. The isotopic data confirm the flow directions of groundwater and shows that the recharge of Ain El Beidha aquifers takes place from the floods of the Khechem and Ben Zitoun wadies and also by preferential infiltration of runoff at the front of hill slopes area. Close to preferential recharge areas, groundwater 3H contents reflect a recent input of surface water, whereas the radiocarbon data indicate a longer residence time downstream. The isotopic characteristics of Ain El Beidha groundwater (small space and temporal changes) authorize the use of averaged values for the dam-aquifer water exchange. Under natural conditions, groundwater recharge of the alluvial aquifer of Kairouan plain occurs by infiltration of the Merguellil floods and from the Ain el Beidha groundwater flow close the karstic hydraulic sills. Since the construction of the El Haouareb dam, these natural mechanisms have been strongly modified: the dam waters infiltrate into the karst, mix with the Ain el Beidha groundwater, and feed the

  5. Equilibrium geochemical modeling of a seasonal thermal energy storage aquifer field test

    Science.gov (United States)

    Stottlemyre, J. S.

    1980-01-01

    A geochemical mathematical modeling study designed to investigate the well plugging problems encountered at the Auburn University experimental field tests is summarized. The results, primarily of qualitative interest, include: (1) loss of injectivity was probably due to a combination of native particulate plugging and clay swelling and dispersion; (2) fluid-fluid incompatibilities, hydrothermal reactions, and oxidation reactions were of insignificant magnitude or too slow to have contributed markedly to the plugging; and (3) the potential for and contributions from temperature-induced dissolved gas solubility reductions, capillary boundary layer viscosity increases, and microstructural deformation cannot be deconvolved from the available data.

  6. Investigating geochemical aspects of managed aquifer recharge by column experiments with alternating desalinated water and groundwater.

    Science.gov (United States)

    Ronen-Eliraz, Gefen; Russak, Amos; Nitzan, Ido; Guttman, Joseph; Kurtzman, Daniel

    2017-01-01

    Managed aquifer recharge (MAR) events are occasionally carried out with surplus desalinated seawater that has been post-treated with CaCO 3 in infiltration ponds overlying the northern part of the Israeli Coastal Aquifer. This water's chemical characteristics differ from those of any other water recharged to the aquifer and of the natural groundwater. As the MAR events are short (hours to weeks), the sediment under the infiltration ponds will intermittently host desalinated and natural groundwater. As part of comprehensive research on the influence of those events, column experiments were designed to simulate the alternation of the two water types: post-treated desalinated seawater (PTDES) and natural groundwater (GW). Each experiment included three stages: (i) saturation with GW; (ii) inflow of PTDES; (iii) inflow of GW. Three runs were conducted, each with different sediments extracted from the field and representing a different layer below the infiltration pond: (i) sand (<1% CaCO 3 ), (ii) sand containing 7% CaCO 3 , and (iii) crushed calcareous sandstone (35% CaCO 3 ). The results from all columns showed enrichment of K + and Mg 2+ (up to 0.4meq/L for 20 pore volumes) when PTDES replaced GW, whereas an opposite trend of Ca 2+ depletion (up to 0.5meq/L) was observed only in the columns that contained a high percentage of CaCO 3 . When GW replaced PTDES, depletion of Mg 2+ and K + was noted. The results indicated that adsorption/desorption of cations are the main processes causing the observed enrichment/depletion. It was concluded that the high concentration of Ca 2+ (relative to the total concentration of cations) and the low concentration of Mg 2+ in the PTDES relative to natural GW are the factors controlling the main sediment-water interaction. The enrichment of PTDES with Mg 2+ may be viewed as an additional post-treatment. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Geochemical and stable isotopic evolution of the Guarani Aquifer System in the state of São Paulo, Brazil

    Science.gov (United States)

    Sracek, Ondra; Hirata, Ricardo

    2002-09-01

    The purpose of this report is to explain geochemical and stable isotopes trends in the Brazilian unit of the Guarani Aquifer System (Botucatu and Piramboia aquifers) in São Paulo State, Brazil. Trends of dissolved species concentrations and geochemical modeling indicated a significant role of cation exchange and dissolution of carbonates in downgradient evolution of groundwater chemistry. Loss of calcium by the exchange for sodium drives dissolution of carbonates and results in Na-HCO3 type of groundwater. The cation-exchange front moves downgradient at probably much slower rate compared to the velocity of groundwater flow and at present is located near to the cities of Sertãozinho and Águas de Santa Barbara (wells PZ-34 and PZ-148, respectively) in a shallow confined area, 50-70 km from the recharge zone. Part of the sodium probably enters the Guarani Aquifer System. together with chloride and sulfate from the underlying Piramboia Formation by diffusion related to the dissolution of evaporates like halite and gypsum. High concentrations of fluorine (up to 13.3 mg/L) can be explained by dissolution of mineral fluoride also driven by cation exchange. However, it is unclear if the dissolution takes place directly in the Guarani Aquifer System or in the overlying basaltic Serra Geral Formation. There is depletion in δ2H and δ18O values in groundwater downgradient. Values of δ13C(DIC) are enriched downgradient, indicating dissolution of calcite under closed system conditions. Values of δ13C(DIC) in deep geothermal wells are very high (>-6.0‰) and probably indicate isotopic exchange with carbonates with δ13C about -3.0‰. Future work should be based on evaluation of vertical fluxes and potential for penetration of contamination to the Guarani Aquifer System. Résumé. Cet article a pour objet d'expliquer l'évolution de la géochimie et des isotopes stables dans l'unité brésilienne du système aquifère du Guarani (aquifères de Botucatu et Piramboia), dans

  8. Status report on geochemical field results from Atlantic study sites

    International Nuclear Information System (INIS)

    Wilson, T.R.S.; Thomson, J.; Hydes, D.J.; Colley, S.

    1983-01-01

    This report summarises the results of preliminary geochemical investigations at three North Atlantic study areas. The two eastern sites, on the Cape Verde abyssal plain (CV2) and east of Great Meteor Seamount (GME) were visited during 1982. The results presented are preliminary. Studies in the western Atlantic, close to the Nares Abyssal Plain study site are more detailed and are presented in a separate paper. The report shows for the first time the relative redox status of the three sites. The differences are unexpectedly large, the most reduced cores being recovered at GME and the most oxidised at CV2. The sporadic nature of Recent sediment accumulation at these sites is also emphasised. In order to place these preliminary results in context their relevance to the production of mathematical system models is discussed in a closing section. The necessity for such models to rest on sound foundations of geochemical understanding is noted. Suggestions on future research priorities are offered for discussion. (author)

  9. Geochemical evidence of groundwater flow paths and the fate and transport of constituents of concern in the alluvial aquifer at Fort Wingate Depot Activity, New Mexico, 2009

    Science.gov (United States)

    Robertson, Andrew J.; Henry, David W.; Langman, Jeffery B.

    2013-01-01

    accidental spill of perchlorate was spatially limited, and that dilution is the primary attenuation process for these constituents. The explosive concentrations of the nitramine 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) and the oxidizer perchlorate both support that determination. Unlike RDX and perchlorate, there were no detectable concentrations of trinitrotoluene (TNT) in the aquifer. Based on the chemical nature of TNT and the redox conditions found in the aquifer, it is interpreted that TNT is lost to irreversible sorption and aerobic degradation. Nitrate was ubiquitous in the alluvial groundwater in October 2009. The nitrate concentrations in wells associated with the explosives’ groundwater flow path indicate attenuation primarily through dilution, similar to that of RDX. The origin of nitrate concentrations in the wells located in the Administration Area is uncertain but may have resulted from the leakage of aging clay sewage pipes that service most of the structures within that area or as a relic of a former hydrologic regime in which water from the washout operation migrated across a broader area. Sufficient data do not exist to definitively identify the location(s) of water discharge in this area, but transpiration from near the Administration Area is supported by the geochemical concentrations.

  10. Natural and EDTA-complexed lanthanides used as a geochemical probe for aquifers: a case study of Orleans valley's alluvial and karstic aquifers

    International Nuclear Information System (INIS)

    Le Borgne, F.; Treuil, M.; Joron, J.L.; Lepiller, M.

    2005-01-01

    channels direction. During the river descent, horizontal flows are quasi absent and migrations are mainly vertical from the alluvia down to the calcareous part of the aquifer. Due to those hydrodynamic characteristics, alluvia and non fissured limestone have a high dynamic confining capacity. Elements with high affinity for solid or colloidal phases (e.g. light Ln) have an increased confining capacity in the whole aquifer, by sorption and colloid filtration within the alluvia and at the alluvial-calcareous interface, and by colloid decanting within the karstic channels. Overall, this model combines two components. The first one, hydrodynamical, results from the repartition of the loads pulsed by river Loire through the karst. The second one, physico-chemical, results from the element distribution mainly controlled by colloid/solute complexes exchange coefficients. (authors)

  11. Geochemical approach of the salinization mechanisms of coastal aquifers - 14C - 226Ra chronologies

    International Nuclear Information System (INIS)

    Barbecot, F.

    1999-11-01

    Through time, coastal aquifers which constitute a great part of available fresh water resources from sedimentary basins in France, were submitted to changes in hydraulic gradients and hydrodynamic properties mainly due to discharge/recharge phases in response to sea level variations and/or anthropic forcing. Performed in the framework of the European program PALAEAUX ('Management of coastal aquifers in Europe, paleo-waters and natural controls'), this work aimed to understand the salinization process originating from the recharge/discharge conditions and recognized in three study aquifers: the calcareous Dogger aquifers along the Channel (Caen area), and the Atlantic coast (Marais Poitevin), and the Astian sandy aquifer (Cap d'Agde). Besides the conventional hydrogeological and hydrochemical methods, the main tools used are those of isotope geochemistry. For the three sites, the modern, fresh groundwaters are marked by the anthropisation of the recharge area. The evolution of isotopic signatures along a flow path depending on the mineralogy of the aquifer matrix, is linked to water-rock interactions such as cation exchange, and equilibrium with aluminosilicates. For the three study sites, the modern fresh groundwaters are marked by the anthropisation of the recharge area. The evolution of isotopic signatures along a flow path depending on the mineralogy of the aquifer matrix, is linked to water-rock interactions such as cation exchange, and equilibrium with aluminosilicates. Residence times of these fresh groundwater are from Present (Atlantic site) up to the 14 C detection limit (Channel site). Groundwater of the Astian aquifer belongs to Holocene, as determined by both 14 C and 226 Ra. From Present to 3 ka, 14 C and 226 Ra ages are coherent. Beyond, the discrepancy observed can be associated to the under-estimation of in- situ 226 Ra production, but more likely, to the 'buffer' effect of the matrix with respect to the 14 C isotopic equilibration. The salty waters

  12. Geochemical model of uranium and selenium in an aquifer disturbed by in situ uranium mining

    International Nuclear Information System (INIS)

    Johnson, K.; Neumann, M.R.

    1986-01-01

    Restoring ground water to baseline conditions proved to be very difficult, however, and led to the trial of a sodium carbonate/bicarbonate lixiviant. Results of this test indicated the basic lixiviant was unable to address uranium tied up in carbonaceous material. Subsequently, the decision was made to curtail development and restore all affected ground water to the extent achievable through the use of the best practicable technology, such as reverse osmosis. Restoration results, however, were not considered adequate for demonstration of commercial restoration feasibility. Following completion of the restoration effort, regulatory agencies expressed concern as to the long-term fate of certain parameters, such as uranium and selenium, remaining in solution at above baseline levels. Rocky Mountain Energy, through discussions with various consultants, determined that geochemical modeling would be the most appropriate tool for predicting the probable long-term effects. This paper summarizes the results of the subsequent evaluation which was conducted using the PHREEQE computer model. Significant conclusions of the investigation were: (1) the Eh in the ground water decreases regularly after mining activities, as shown by measured Eh values, and (2) the accompanying decrease in uranium and selenium can be predicted by thermodynamic modeling

  13. Geochemical and isotopic tracers of recharge and reclamation of stormwater in an urban aquifer: Adelaide, South Australia

    International Nuclear Information System (INIS)

    Herczeg, A.L.; Rattray, K.J.; Dillon, P.J.; Pavelic, P.C.; Barry, K.J.

    2002-01-01

    Artificial recharge and reclamation of stormwater into groundwater is a newly developing strategy to augment water resources in the Adelaide metropolitan area of South Australia. Mixing between injected storm water and native groundwater can be most effectively using naturally occurring chloride ion. Stable isotopes of the water molecule are used more effectively during short term tests (i.e., immediately following injection events), and requires frequent monitoring of the surface water end-member. Biogeochemical processes involving geochemical reactions such as organic matter oxidation, carbonate mineral dissolution and sulfide mineral oxidation are very effectively traced by δ 13 C and 14 C (of TDIC) and δ 34 S (of SO 4 2- ). The most important processes occurring in the Tertiary limestone aquifer in Adelaide were carbonate mineral dissolution which is induced largely by CO 2 production during organic matter oxidation. Sulfide mineral oxidation is a minor process, and is accompanied by an equivalent amount of sulfate reduction after injection of the stormwater. (author)

  14. Geochemical and statistical evidence of recharge, mixing, and controls on spring discharge in an eogenetic karst aquifer

    Science.gov (United States)

    Moore, Paul J.; Martin, Jonathan B.; Screaton, Elizabeth J.

    2009-10-01

    SummaryInformation about sources of recharge, distributions of flow paths, and the extent of water-rock reactions in karst aquifers commonly result from monitoring spring chemistry and discharge. To investigate the relationship between spring characteristics and the complexities of karst aquifers, we couple variations in surface- and groundwater chemistry to physical conditions including river stage, precipitation, and evapotranspiration (ET) within a sink-rise system through a 6-km portion of the Upper Floridan aquifer (UFA) in north-central Florida. Principal component analysis (PCA) of time series major-element compositions suggests that at least three sources of water affect spring discharge, including allogenic recharge into a swallet, diffuse recharge through a thin vadose zone, and water upwelling from deep within the aquifer. The deep-water source exerts the strongest influence on water chemistry by providing a majority of Na +, Mg 2+, K +, Cl -, and SO42- to the system. Anomalously high temperature at one of several monitoring wells reflects vertical flow of about 1 m/year. Mass-balance calculations suggest diffuse recharge and deep-water upwelling can provide up to 50% of the spring discharge; however, their contributions depend on head gradients between the conduit and surrounding aquifer matrix, which are influenced by variations in precipitation, ET, and river stage. Our results indicate that upwelling from deep flow paths may provide significant contributions of water to spring discharge, and that monitoring only springs limits interpretations of karst systems by masking critical components of the aquifer, such as water sources and flow paths. These results also suggest the matrix in eogenetic aquifers is a major pathway for flow even in a system dominated by conduits.

  15. Geomicrobial and Geochemical Redox Processes in a Landfill-Polluted Aquifer

    DEFF Research Database (Denmark)

    Ludvigsen, Liselotte; Heron, Gorm; Albrechtsen, Hans-Jørgen

    1995-01-01

    The distribution of different dominant microbial-mediated redox processes in a landfill leachate-polluted aquifer (Grindsted, Denmark) was investigated. The most probable number method was utilized for detecting bacteria able to use each of the electron acceptors, and unamended incubations were u...

  16. Experimental investigation of geochemical and mineralogical effects of CO2 sequestration on flow characteristics of reservoir rock in deep saline aquifers

    Science.gov (United States)

    Rathnaweera, T. D.; Ranjith, P. G.; Perera, M. S. A.

    2016-01-01

    Interactions between injected CO2, brine, and rock during CO2 sequestration in deep saline aquifers alter their natural hydro-mechanical properties, affecting the safety, and efficiency of the sequestration process. This study aims to identify such interaction-induced mineralogical changes in aquifers, and in particular their impact on the reservoir rock’s flow characteristics. Sandstone samples were first exposed for 1.5 years to a mixture of brine and super-critical CO2 (scCO2), then tested to determine their altered geochemical and mineralogical properties. Changes caused uniquely by CO2 were identified by comparison with samples exposed over a similar period to either plain brine or brine saturated with N2. The results show that long-term reaction with CO2 causes a significant pH drop in the saline pore fluid, clearly due to carbonic acid (as dissolved CO2) in the brine. Free H+ ions released into the pore fluid alter the mineralogical structure of the rock formation, through the dissolution of minerals such as calcite, siderite, barite, and quartz. Long-term CO2 injection also creates a significant CO2 drying-out effect and crystals of salt (NaCl) precipitate in the system, further changing the pore structure. Such mineralogical alterations significantly affect the saline aquifer’s permeability, with important practical consequences for the sequestration process. PMID:26785912

  17. Aquifers of Arkansas: protection, management, and hydrologic and geochemical characteristics of groundwater resources in Arkansas

    Science.gov (United States)

    Kresse, Timothy M.; Hays, Phillip D.; Merriman, Katherine R.; Gillip, Jonathan A.; Fugitt, D. Todd; Spellman, Jane L.; Nottmeier, Anna M.; Westerman, Drew A.; Blackstock, Joshua M.; Battreal, James L.

    2014-01-01

    Sixteen aquifers in Arkansas that currently serve or have served as sources of water supply are described with respect to existing groundwater protection and management programs, geology, hydrologic characteristics, water use, water levels, deductive analysis, projections of hydrologic conditions, and water quality. State and Federal protection and management programs are described according to regulatory oversight, management strategies, and ambient groundwater-monitoring programs that currently (2013) are in place for assessing and protecting groundwater resources throughout the State.

  18. Hydro-geochemical characterization of Treated Domestic Waste Water for possible use in homestead irrigation and managed aquifer recharge in the coastal city of Khulna, Bangladesh

    Science.gov (United States)

    Hamid, T.; Ahmed, K. M.

    2016-12-01

    Bangladesh is among the most densely populated countries in the world. Rapid and unplanned urbanization in Bangladesh has resulted in heterogeneous land use pattern and larger demands for municipal water. To meet the ever-increasing demand of water for such population, the usage of treated domestic waste water (DWW) has become a viable option that can serve specific purposes, i.e. homestead irrigation, managed aquifer recharge (MAR) in major cities like Khulna, the largest city in the southwest coastal region. It is an attractive solution to minimize the deficit between the demand and supply of water in the study area where, in specific parts, city-dwellers suffer year round shortage of potable water due to high salinity in shallow depths. However, certain degree of treatment is mandatory for DWW in order to ensure the compliance of the output water with a set of standards and regulations for the DWW reuse. At present, the DWW is being treated through Constructed Wetlands but the treated water is not used and discharged into the sewer system. Wastewater that has been treated through a constructed wetland is a resource that can be used for productive uses in homestead garden irrigation, artificial aquifer recharge, and other non-potable uses. The study addresses the effectiveness of constructed wetlands in improving the quality of wastewater through on the hydro-geochemical characterization of both raw and treated DWW as well as baseline water quality analysis of surface and ground water in and around the treatment plant with consideration of seasonal variations. The study aims at sustainable development through conservation of water, satisfaction of demands, reliability of water supply, contribution to urban food supply, sustenance of livelihood and replenishment of the depleting aquifer by assessing the suitability of the treated DWW for various non-potable uses and also to provide guidelines for possible uses of treated DWW without adverse impact on environment

  19. GEOCHEMICAL ASSESSMENT OF THE UNCONFINED AQUIFER IN A RECENTLY RECLAIMED WETLAND AREA: A CASE STUDY FROM THE PO RIVER DELTA

    Directory of Open Access Journals (Sweden)

    Dario Di Giuseppe

    2013-09-01

    Full Text Available This study focusses on the distribution of main anions and nitrogen species in the unconfined aquifer of a recently reclaimed land. In a 6 ha experimental field, 10 piezometers for water level measurement and groundwater sampling have been installed. After one year of monitoring, results show that the high chloride and ammonium concentrations are due to inherited from the previous brackish conditions and to organic matter mineralization, respectively. Seasonal variations and Cl/Br ratio show that the 1 m deep sub surface drainage system is the main factor conditioning the chemical characteristics and the piezometric depth of the aquifer

  20. Assessment of the hydrologic setting and mass transport within Saharan and Arabian Aquifers using GRACE, geochemical, geophysical and subsurface data

    Science.gov (United States)

    Sultan, M.; Sturchio, N. C.; Ahmed, M.; Saleh, S.; Mohamed, A.; Abuabdullah, M. M.; Emil, M. K.; Bettadpur, S. V.; Save, H.; Fathy, K.; Chouinard, K.

    2016-12-01

    A better understanding of the hydrologic setting, mass transport, origin, evolution, utilization, sustainability, and paleo-climatic recharge conditions of Saharan and Arabian aquifers was achieved by integrating observation from monthly (04/2002 to 03/2016) Gravity Recovery and Climate Experiment (GRACE)-derived Terrestrial Water Storage (TWS) from multiple GRACE solutions (mascons and spherical harmonic fields) with others from geochemical (solute chemistry), isotopic (O, H, Sr), geochronologic (Chlorine-36, Krypton-81), geophysical (aerogravity and aeromagnetic), and subsurface data. The investigated aquifers are: (1) Nubian Sandstone Aquifer System (NSAS; area: 2×106 km2) in northeast Africa and, (2) Mega Aquifer System (MAS; area: 1.1×106 km2) in Arabia. Our findings indicate the NSAS and MAS were largely recharged in previous wet climatic Pleistocene periods, as evidenced by the groundwater ages (up to 1 million years), yet they receive modest local recharge during interleaving dry periods in areas of relatively high (≥ 20 mm/yr) precipitation. In Sudan and Chad (southern NSAS), the average annual precipitation (AAP) is 95 mm/yr and the recharge is estimated at 3.2 x 109 m3/yr ( 7% of AAP); in the southwest parts of the MAS, the recharge at the foothills of the Red Sea mountains is 1.8 x 109 m3/yr (10% of AAP). Uplifts and/or shear zones orthogonal to groundwater flow impede the south to north flow in the NSAS as evidenced by the large differences in GRACE-derived TWS trends, groundwater ages, and isotopic compositions on either side of the east-west trending Uweinat-Aswan uplift. Similarly west to east groundwater flow in the MAS is impeded and impounded up-gradient from the N-S and/or NW-SE trending basement structures, reactivated during Red Sea opening. Shear zones subparallel to groundwater flow act as preferred flow pathways, as is the case with the NE-SW trending Pelusium shear zone which channels groundwater from the Kufra sub-basin (Libya

  1. Baseline geochemical characterisation of a vulnerable tropical karstic aquifer; Lifou, New Caledonia

    Directory of Open Access Journals (Sweden)

    Eric Nicolini

    2016-03-01

    Full Text Available Study region: Lifou Island, near the main island of New Caledonia. Study focus: Stable oxygen and hydrogen isotopes of groundwater and rainfall were used to characterise baseline values for the main fresh water aquifer of Lifou Island and describe its recharge. Other stable isotope parameters (nitrates and DIC were used to investigate the interaction between surface water (rainfall and groundwater, including anthropogenic effects from human activities. New hydrological insights for the region: This study represents the first baseline isotopic characterisation of Lifou Island’s groundwater aquifer composition and provides a reference for future investigative studies on groundwater quality and security. Groundwater sampled in June and October 2012 had nearly identical isotopic composition. Tap water sampled monthly between February 2012 and January 2014 also had a constant isotopic composition similar to the groundwater. Groundwater recharge was found to occur when monthly precipitation exceeded 140 mm, with the recharge cycle representing 20–30% of the annual rainfall. Relationships between HCO32− content, pH, soil δ13C DIC and satellite photo interpretation suggests a variance of soil pCO2, which is explained by different vegetation cover and higher water use efficiencies in forested areas (high pCO2, more negative δ13C isotope values. The δ15NNO3 values for most groundwater indicate they are uncontaminated with anthropogenic nitrates, although some samples taken in October (dry season showed a slight denitrification, possibly of natural origin. Keywords: Reef islands, Precipitation, Karstic aquifer, Hydrogeology, Stable isotopes, Nitrates

  2. National Geochemical Survey Locations and Results for Iowa

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — The United States Geological Survey (USGS), in collaboration with other state and federal agencies, industry, and academia, is conducting a National Geochemical...

  3. Uruguay mining Inventory: Geochemical prospecting results of Valentines mapping

    International Nuclear Information System (INIS)

    Spangenberg, J.; Filippini, J.

    1985-01-01

    This work is about geochemical prospecting carried out into the Uruguay mining inventory framework. In this case the survey was in Valentines mapping. Florida, Durazno and Treinta y Tres provinces of Uruguay .

  4. Evaluation and development of hydrogeological and geochemical investigation methods for aquifers of low permeability

    International Nuclear Information System (INIS)

    Wijland, G.C.; Langemeijer, H.D.; Stapper, R.A.M.; Glasbergen, P.; Michelot, J.L.

    1991-01-01

    Studies are currently being carried out in the Netherlands to assess the environmental consequences of geological disposal of radioactive waste. In these studies transport models are used to evaluate the geohydrological system in formations overlying the potential host-rock, and to establish the potential pathways for radionuclides to the biosphere. Knowledge of parameter values, and of their variability for the investigated formations, is necessary to construct these models. From preceding work it became obvious that only a poor set of data is available, in particular for Paleogene and Upper Cretaceous deposits, that are present in the overburden of salt structures in the Netherlands. Within the current phase of the Netherlands programme on geological disposal it was considered essential to obtain an overview of methods and their accuracy which would be applicable for a geohydrological research programme first. From this work guidelines for the construction of new boreholes might also be derived. The main purposes of this study were defined as follows: to evaluate and to test techniques to obtain geohydrological data of the aquifers and aquitards of the Upper Cretaceous and Lower Tertiary formations. Also, geohydrochemical methods were evaluated and tested in order to find out whether they could contribute to the understanding of the groundwater flow system in aquifers of low permeability

  5. Seawater intrusion in the gravelly confined aquifer of the coastal Pisan Plain (Tuscany): hydrogeological and geochemical investigation to assess causes and consequences

    Science.gov (United States)

    Doveri, M.; Giannecchini, R.; Butteri, M.

    2012-12-01

    The gravelly horizon of the Pisa plain multilayered system is a confined aquifer tapped by a large number of wells. It hosts a very important water resource for drinking, industrial and irrigable uses, but may be affected by seawater intrusion coming from the coastal area; most wells is distributed inland, anyway a significant exploitation along the coastal area is also present to supply farms and tourist services. Previous hydrogeological and geochemical investigations carried out in coastal area stated maximum percentage of seawater in gravelly aquifer of about 7-9% and suggested the presence of two different mechanisms (Doveri et alii, 2010): i) a direct seawater intrusion from the zone where the gravelly aquifer is in contact with the sea floor; ii) a mixing process between freshwater and seawater, the latter deriving from the Arno river-shallow sandy aquifer system. Basing on these results, since January 2012 a new two-year project was financed by the MSRM Regional Park. Major aims are a better definition of such phenomena and their distribution on the territory, and an assessing of the seawater intrusion trend in relation to groundwater exploitation. Eleven piezometers were realised during first semester of 2012, thus improving the measurement network, which is now made up by 40 wells/piezometers distributed on about 60 km^2. Comparing new and previous borehole data a general confinement of the gravelly aquifer is confirmed, excepting in the northern part where the aquifer is in contact with the superficial sandy one. Preliminary field measurement was performed in June 2012, during which water level (WL) and electrical conductivity (EC) data were collected. WLs below the sea-level were observed on most of the studied area, with a minimum value of about -5 m a.s.l. in the inner part of the northern zone, where major exploitation is present. Moreover, a relative minimum of WL (about -2 m a.s.l.) is present near the shoreline in the southern zone. In the latter

  6. Geochemical controls on shale groundwaters: Results of reaction path modeling

    International Nuclear Information System (INIS)

    Von Damm, K.L.; VandenBrook, A.J.

    1989-03-01

    The EQ3NR/EQ6 geochemical modeling code was used to simulate the reaction of several shale mineralogies with different groundwater compositions in order to elucidate changes that may occur in both the groundwater compositions, and rock mineralogies and compositions under conditions which may be encountered in a high-level radioactive waste repository. Shales with primarily illitic or smectitic compositions were the focus of this study. The reactions were run at the ambient temperatures of the groundwaters and to temperatures as high as 250/degree/C, the approximate temperature maximum expected in a repository. All modeling assumed that equilibrium was achieved and treated the rock and water assemblage as a closed system. Graphite was used as a proxy mineral for organic matter in the shales. The results show that the presence of even a very small amount of reducing mineral has a large influence on the redox state of the groundwaters, and that either pyrite or graphite provides essentially the same results, with slight differences in dissolved C, Fe and S concentrations. The thermodynamic data base is inadequate at the present time to fully evaluate the speciation of dissolved carbon, due to the paucity of thermodynamic data for organic compounds. In the illitic cases the groundwaters resulting from interaction at elevated temperatures are acid, while the smectitic cases remain alkaline, although the final equilibrium mineral assemblages are quite similar. 10 refs., 8 figs., 15 tabs

  7. 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 polygons....

  8. 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

  9. Uruguay Mining inventory. Florida fotoplano geochemical prospecting results

    International Nuclear Information System (INIS)

    Zeegers, H.; Artignan, D.; Vairon, P.

    1982-01-01

    This work is about the geochemical prospecting carried out in Florida fotoplano within the framework of Uruguay Mining inventory. In this work were covered 660 km2 obtaining 752 samples for study which were analyzed by Plasma Emission Spectrometry in Orleans BRGM laboratories

  10. Uruguay Mining inventory. Las Animas fotoplano geochemical prospecting results

    International Nuclear Information System (INIS)

    Zeegers, H.; Spangenberg, J.

    1981-01-01

    This work is about the geochemical prospecting carried out in Las Animas fotoplano within the framework of Uruguay Mining inventory. In this work were covered 660 km2 obtaining 738 samples for study which were analyzed by Plasma Emission Spectrometry in Orleans BRGM laboratories.

  11. Uruguay Mining inventory. Minas fotoplano geochemical prospecting results

    International Nuclear Information System (INIS)

    Zeegers, H.; Artignan, D.; Vairon, P.

    1982-01-01

    This work is about the geochemical prospecting carried out in Minas fotoplano within the framework of Uruguay Mining inventory. In this work were covered 380 km2 obtaining with 433 samples for study which were analized by Plasma Emission Spectrometry in Orleans BRGM laboratories

  12. Mining inventory of Uruguay. Polanco fotoplano geochemical prospecting results

    International Nuclear Information System (INIS)

    Zeegers, H; Artignan, D; Vairon, P

    1982-01-01

    This work is about the geochemical prospecting carried out in Polanco fotoplano within the framework of Uruguay Mining inventory . In this work were covered 660 km2 obtaining 685 samples for study which were analyzed by Plasma Emission Spectrometry in Orleans BRGM laboratories

  13. Comparison of groundwater flow in Southern California coastal aquifers

    Science.gov (United States)

    Hanson, Randall T.; Izbicki, John A.; Reichard, Eric G.; Edwards, Brian D.; Land, Michael; Martin, Peter

    2009-01-01

    Development of the coastal aquifer systems of Southern California has resulted in overdraft, changes in streamflow, seawater intrusion, land subsidence, increased vertical flow between aquifers, and a redirection of regional flow toward pumping centers. These water-management challenges can be more effectively addressed by incorporating new understanding of the geologic, hydrologic, and geochemical setting of these aquifers.

  14. Direct-push geochemical profiling for assessment of inorganic chemical heterogeneity in aquifers

    Science.gov (United States)

    Schulmeister, M.K.; Healey, J.M.; Butler, J.J.; McCall, G.W.

    2004-01-01

    Discrete-depth sampling of inorganic groundwater chemistry is essential for a variety of site characterization activities. Although the mobility and rapid sampling capabilities of direct-push techniques have led to their widespread use for evaluating the distribution of organic contaminants, complementary methods for the characterization of spatial variations in geochemical conditions have not been developed. In this study, a direct-push-based approach for high-resolution inorganic chemical profiling was developed at a site where sharp chemical contrasts and iron-reducing conditions had previously been observed. Existing multilevel samplers (MLSs) that span a fining-upward alluvial sequence were used for comparison with the direct-push profiling. Chemical profiles obtained with a conventional direct-push exposed-screen sampler differed from those obtained with an adjacent MLS because of sampler reactivity and mixing with water from previous sampling levels. The sampler was modified by replacing steel sampling components with stainless-steel and heat-treated parts, and adding an adapter that prevents mixing. Profiles obtained with the modified approach were in excellent agreement with those obtained from an adjacent MLS for all constituents and parameters monitored (Cl, NO3, Fe, Mn, DO, ORP, specific conductance and pH). Interpretations of site redox conditions based on field-measured parameters were supported by laboratory analysis of dissolved Fe. The discrete-depth capability of this approach allows inorganic chemical variations to be described at a level of detail that has rarely been possible. When combined with the mobility afforded by direct-push rigs and on-site methods of chemical analysis, the new approach is well suited for a variety of interactive site-characterization endeavors. ?? 2003 Elsevier B.V. All rights reserved.

  15. Geochemical characterization and heavy metal migration in a coastal polluted aquifer incorporating tidal effects: field investigation in Chongming Island, China.

    Science.gov (United States)

    Liu, Shuguang; Tan, Bo; Dai, Chaomeng; Lou, Sha; Tao, An; Zhong, Guihui

    2015-12-01

    The occurrence and migration of heavy metal in coastal aquifer incorporating tidal effects were investigated in detail by the field geological survey and observation. The continuous groundwater sampling, field observation (for groundwater potentiometric surface elevation, pH, dissolved oxygen, temperature, and salinity), and laboratory analysis (for Cr, Ni, Cu, Zn, Cd, and Pb concentration) were conducted through eight monitoring wells located around the landfill in the northern part of Chongming Island, China. The results showed that the unconfined aquifer medium was estuary-littoral facies deposit of Holocene, mainly gray clayey silt and grey sandy silt, and the groundwater flow was mainly controlled by topography condition of the aquifer formation strike. The background values of Cr, Ni, Cu, Zn, Cd, and Pb in Chongming Island were 3.10 ± 3.09, 0.81 ± 0.25, 1.48 ± 1.09, 43.32 ± 33.06, 0.08 ± 0.16, and 0.88 ± 1.74 μg/L, respectively. Compared with the groundwater samples around the study area, the drinking water was qualified and was free from the seawater intrusion/estuarine facies contaminant encroachment. Pollutant discharge was reflected in water quality parameters, the Cr and Cu concentrations elevated to the peak of 50.07 and 46.00 μg/L, respectively, and meanwhile specific migration regularity was embodied in observation time series as well as other elements. This migration regularity was not fully identical according to correlations between these analyzed elements. Ambient watery environment, anthropogenic disturbance, regional hydrogeological condition, and biogeochemical reactivity on heavy metals reduced/altered the significance of elements correlation in the migration pathway in coastal aquifer.

  16. Geochemical and hydrological characterization of shallow aquifer water following a nearby deep CO2 injection in Wellington, Kansas

    Science.gov (United States)

    Datta, S.; Andree, I.; Johannesson, K. H.; Kempton, P. D.; Barker, R.; Birdie, T. R.; Watney, W. L.

    2017-12-01

    Salinization or CO2 leakage from local Enhanced Oil Recovery (EOR) projects has become a possible source for contamination and water quality degradation for local irrigation or potable well users in Wellington, Kansas. Shallow domestic and monitoring wells, as well as surface water samples collected from the site, were analyzed for a wide array of geochemical proxies including major and trace ions, rare earth elements (REE), stable isotopes, dissolved organic carbon and dissolved hydrocarbons; these analytes were employed as geotracers to understand the extent of hydrologic continuity throughout the Paleozoic stratigraphic section. Previous research by Barker et al. (2012) laid the foundation through a mineralogical and geochemical investigation of the Arbuckle injection zone and assessment of overlying caprock integrity, which led to the conclusion that the 4,910-5,050' interval will safely sequester CO2 with high confidence of a low leakage potential. EOR operations using CO2 as the injectant into the Mississippian 3,677-3,706' interval was initiated in Jan 2016. Two groundwater sampling events were conducted to investigate any temporal changes in the surface and subsurface waters. Dissolved (Ca+Mg)/Na and Na/Cl mass ratio values of two domestic wells and one monitoring well ranged from 0.67 to 2.01 and 0.19 to 0.39, respectively, whereas a nearby Mississippian oil well had values of 0.20 and 0.62, respectively . δ18O and δ2H ranged from -4.74 to -5.41 ‰VSMOW and -31.4 to -34.3 ‰VSMOW, respectively, among the domestic wells and shallowest monitoring well. Conservative ion relationships in drill-stem-test waters from Arbuckle and Mississippian injection zones displayed significant variability, indicating limited vertical hydrologic communication. Total aquifer connectivity is inconclusive based on the provided data; however, a paleoterrace and incised valley within the study site are thought to be connected through a Mississippian salt plume migration

  17. Pathogen Decay during Managed Aquifer Recharge at Four Sites with Different Geochemical Characteristics and Recharge Water Sources.

    Science.gov (United States)

    Sidhu, J P S; Toze, S; Hodgers, L; Barry, K; Page, D; Li, Y; Dillon, P

    2015-09-01

    Recycling of stormwater water and treated effluent via managed aquifer recharge (MAR) has often been hampered because of perceptions of low microbiological quality of recovered water and associated health risks. The goal of this study was to assess the removal of selected pathogens in four large-scale MAR schemes and to determine the influence of aquifer characteristics, geochemistry, and type of recharge water on the pathogen survival times. Bacterial pathogens tested in this study had the shortest one log removal time (, 200 d). Human adenovirus and rotavirus were relatively persistent under anaerobic conditions (, >200 d). Human adenovirus survived longer than all the other enteric virus tested in the study and hence could be used as a conservative indicator for virus removal in groundwater during MAR. The results suggest that site-specific subsurface conditions such as groundwater chemistry can have considerable influence on the decay rates of enteric pathogens and that viruses are likely to be the critical pathogens from a public health perspective. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  18. Arsenic enrichment and mobilization in the Holocene alluvial aquifers of the Chapai-Nawabganj district, Bangladesh: A geochemical and statistical study

    International Nuclear Information System (INIS)

    Reza, A.H.M. Selim; Jean, Jiin-Shuh; Lee, Ming-Kuo; Yang, Huai-Jen; Liu, Chia-Chuan

    2010-01-01

    Research highlights: → Four factors (i.e., salinity factor, As-enrichment factor, reduction factor, and hardness factor) control groundwater geochemistry. → Hydrochemical facies analysis showed that most of the water samples are dominated by Ca and HCO 3 ions. → Cluster 1 water types are highly enriched in As; an alternative water source is thus needed for domestic water supply. Possible solutions are to install tube wells in the deeper Pleistocene aquifers or use clean surface water sources such as reservoirs or rain water. → Cluster 4 water types contain low concentration As, below the Bangladesh standard ( 4 , total dissolved solids (TDS), and electrical conductivity (EC) are grouped under the first factor representing the salinity sources of waters. The second factor, represented by As and Mn, is related to As mobilization processes. The third factor of Fe and alkalinity is strongly influenced by bacterial Fe(III) reduction which would raise both Fe and HCO 3 - concentrations in water. The fourth factor of Ca and Mg reflects the hardness of the Ca-HCO 3 type of groundwater, which is confirmed by the hydrochemical facies analysis. Cluster analysis leads to the formulation of four water types including highly, moderately, and slightly As-enriched groundwater as well as groundwater with elevated SO 4 2- , from anthropogenic sources. Multivariate analyses of the geochemical parameters suggest that Fe- and Mn-oxyhydroxides and mineral phases of phyllosilicates (e.g., biotite) are the main hosts of As in the sediments. Statistical analysis also shows that As is closely associated with Fe and Mn in sediments while As is positively correlated with Mn in groundwater. These correlations along with results of sequential leaching experiments suggest that reductive dissolution of MnOOH and FeOOH mediated by anaerobic bacteria represents an important mechanism for releasing As into the groundwater.

  19. Geochemical and isotopic study to determine sources and processes affecting nitrate and sulphate in groundwater influenced by intensive human activity - carbonate aquifer Gliwice (southern Poland)

    International Nuclear Information System (INIS)

    Jakóbczyk-Karpierz, Sabina; Sitek, Sławomir; Jakobsen, Rasmus; Kowalczyk, Andrzej

    2017-01-01

    A multi-species, multi-stable-isotope approach (δ"1"5N_N_O_3, δ"1"8O_N_O_3_, δ"3"4S_S_O_4, δ"1"8O_S_O_4, δ"1"8O_H_2_O and δ"2H_H_2_O) was used together with environmental tracers (Ar, Ne, CFC-11 and CFC-12) and geochemical modelling to characterize sources and processes controlling concentrations of NO_3"− and SO_4"2"- in groundwater of the carbonate aquifer Gliwice (southern Poland). The study area represents a strongly transformed environment with a range of human activities i.a. Agriculture, urbanization and industry. The δ"1"5N_N_O_3 and δ"1"8O_N_O_3 indicated that most samples contained NO_3"− of mixed sources: artificial fertilizers, municipal and industrial sewage, while very good correlation between NO_3"− and CFC-12 suggested that nitrate originated primarily from residential and industrial sewage. Conversely, isotopic composition of sulphate in groundwater suggested agriculture as well as oxidation of sulphides as dominant. The conclusion was supported by the comparison of CFCs and sulphate concentrations which revealed no relevant correlation. Geochemical modelling confirmed the presence of sulphate reduction in areas where isotopic analyses were not possible due to undetectable sulphate. Thus, the integrated application of stable isotopes, environmental tracers, groundwater chemistry and geochemical modelling shows a complex origin of groundwater pollution in the study area as well as variety of geochemical processes controlling chemistry of groundwater in a triple-porosity aquifer influenced by different types of human activity. - Highlights: • CFCs helped to identify municipal and industrial sources of NO_3"− in groundwater. • δ"1"8O and δ"3"4S suggested domination of SO_4"2"- from agriculture and sulphide oxidation. • Sulphate reduction was confirmed using geochemical modelling for SO_4"2"-free water.

  20. The geochemical evolution of aqueous sodium in the Black Creek Aquifer, Horry and Georgetown counties, South Carolina

    Science.gov (United States)

    Zack, Allen L.; Roberts, Ivan

    1988-01-01

    The Black Creek aquifer contains dilute seawater near the North Carolina State line, probably the result of incomplete flushing of ancient seawater. Data do not indicate that the dilute seawater has migrated toward areas of fresh ground-water withdrawals. The concentration of chloride in ground-water samples ranges from 5 to 720 milligrams per liter and that of sodium from 160 to 690 milligrams per liter. Ion-exchange reactions (sodium for calcium and fluoride for hydroxyl) occur with the calcium carbonate dissolution reaction which produces calcium, bicarbonate, and hydroxyl ions. The reaction sequence and stoichiometry result in an aqueous solution in which the sum of bicarbonate and chloride equivalents per liter is equal to the equivalents per liter of sodium. Calcium ions are exchanged for sodium ions derived from sodium-rich clays upgradient of the dilute seawater. The cation-exchange reaction equilibrates at a sodium concentration of 280 milligrams per liter. Amounts of sodium greater than 280 milligrams per liter are contributed from dilute seawater. The cation-exchange reaction approaches an equilibrium which represents a mass-action limit in terms of the ratio of sodium to calcium in solution versus the ratio of exchangeable sodium to calcium on clay surfaces. Where the limit of calcium carbonate solubility is approached and dissolution ceases, some precipitation of calcite probably takes place. The dissolution of calcite exposes fossil shark teeth which release fluoride ions to the ground water through anion exchange with aqueous hydroxyl ions.

  1. Recharge sources and geochemical evolution of groundwater in the Quaternary aquifer at Atfih area, the northeastern Nile Valley, Egypt

    Science.gov (United States)

    El-Sayed, Salah Abdelwahab; Morsy, Samah M.; Zakaria, Khalid M.

    2018-06-01

    This study addresses the topic of recharge sources and evolution of groundwater in the Atfih area situated in the northeastern part of the Nile Valley, Egypt. Inventory of water wells and collection of groundwater and surface water samples have been achieved. Water samples are analyzed for major ions according to the American Society for Testing and Materials and for the environmental isotopes analysis (oxygen-18 and deuterium) by using a Triple Liquid Isotopic Water Analyzer (Los Gatos). The groundwater is available from the Quaternary aquifer formed mainly of graded sand and gravel interbedded with clay lenses. The hydrogeologic, hydrogeochemical and isotopic investigations indicate the hydrodynamic nature of the aquifer, where different flow paths, recharge sources and evolution mechanisms are distinguished. The directions of groundwater flow are from E, W and S directions suggesting the contribution from Nile River, the Eocene aquifer and the Nile basin, respectively. The groundwater altitudes range from 13 m (MSL) to 44 m (MSL). The hydraulic gradient varies between 0.025 and 0.0015. The groundwater is alkaline (pH > 7) and has salinity ranging from fresh to brackish water (TDS between 528 mg/l and 6070 mg/l). The observed wide range in the ionic composition and water types reflects the effect of different environmental and geological conditions through which the water has flowed. The isotopic compositions of groundwater samples vary between -14.13‰ and +23.56 for δD and between - 2.91‰ and +3.10 for δ18O. The isotopic data indicates that the Quaternary aquifer receive recharge from different sources including the Recent Nile water, surplus irrigation water, old Nile water before the construction of Aswan High Dam, surface runoff of local rains and Eocene aquifer. Evaporation, water rock interaction and mixing between different types of waters are the main processes in the groundwater evolution. Major suggestions are presented to develop the aquifer

  2. Use of a time-domain electromagnetic method with geochemical tracers to explore the salinity anomalies in a small coastal aquifer in north-eastern Tunisia

    Science.gov (United States)

    Chekirbane, Anis; Tsujimura, Maki; Kawachi, Atsushi; Lachaal, Fethi; Isoda, Hiroko; Tarhouni, Jamila

    2014-12-01

    The study area is a small coastal plain in north-eastern Tunisia. It is drained by an ephemeral stream network and is subject to several pollutant discharges such as oilfield brine coming from a neighboring oil company and wastewater from Somâa city, located in the upstream of the plain. Furthermore, a hydraulic head near the coastal part of the aquifer is below sea level, suggesting that seawater intrusion may occur. A time-domain electromagnetic (TDEM) survey, based on 28 soundings, was conducted in Wadi Al Ayn and Daroufa plains to delineate the saline groundwater. Based on longitudinal and transversal resistivity two-dimensional pseudosections calibrated with boring data, the extent of saline water was identified. Geochemical tracers were combined with the resistivity dataset to differentiate the origin of groundwater salinization. In the upstream part of the plain, the infiltration of oilfield brine through the sandy bed of Wadi Al Ayn seems to have a considerable effect on groundwater salinization. However, in the coastal part of the aquifer, groundwater salinization is due to seawater intrusion and the saltwater is reaching an inland extent around 1.3 km from the shoreline. The contribution ratios of saline water bodies derived from the inverted chloride data vary for the oilfield brine from 1 to 13 % and for the seawater from 2 to 21 %.

  3. Origin of nickel in water solution of the chalk aquifer in the north of France and influence of geochemical factors

    Science.gov (United States)

    Bernard, Daniel; El Khattabi, Jamal; Lefevre, Emilie; Serhal, Hani; Bastin-Lacherez, Sabine; Shahrour, Isam

    2008-01-01

    In the north of France, high registers of nickel are sometimes recorded within the chalk aquifer. In a confined context, the presence of pyrite in the covering clays or in the marcasite nodules encrusted in the clay may constitute a natural source of trace metals. With an objective of sanitary control, the limits of chemical contents regulating the quality of water destined for human consumption have been lowered by the European Framework Directive in the field of water policy (2000/60/EC). As a result, nickel limits have been reduced from 50 to 20 μg/l. The analyses, carried out on three water catchment fields in our area of study, were centred on variable parameters (Eh, O2(d), pH, Conductivity, T°), major elements (SO4, NO3) and metals (Fe, Ni, Mn, Co). The acquired data enabled us to identify from one hand, the conditions which are presented within the site, special thanks to the evolution of nitrate and iron contents and on the other hand, the natural origin (geological) of nickel for two of the three sites studied based essentially on the evaluation of the Nickel/Cobalt ratio. Thus, on the first site, the evolution of nickel content and nitrate content showed the influence of the phenomenon of denitrification on the re-mobilisation of the nickel. Whereas on the second site, a high variation of total iron content and oxygen dissolved in solution highlighted a particular phenomenon of oxidation of the pyrite through molecular oxygen. Finally, the correlation with the sulphates clearly showed behaviour of the nickel, once released, that was entirely dependent on the phenomenon of adsorption on the iron and manganese hydroxides.

  4. Hydrogeochemistry of regional aquifer systems from Tuscany (central Italy): the state of the art before the definition of a geochemical baseline

    Science.gov (United States)

    Nisi, Barbara; Battaglini, Raffaele; Raco, Brunella

    2013-04-01

    European Community Water Framework Directive (WFD) and its derivative regulations have recognized the urgent need to adopt specific measures against the contamination of water bodies by individual pollutants that may significantly affect the quality of water itself. Italian regulation takes into account the EU Directives, and charges the regional authorities to create monitoring networks and produce assessment reports on the contamination of groundwater. The knowledge of "natural baseline" for various dissolved elements in groundwaters on a regional scale becomes of primary importance to distinguish natural sources and anthropogenic inputs. The studied area includes the whole Tuscan regional district (central Italy) and covers an area of about 23,000 km2. From a geolithological point of view, Tuscan territory consists of several complexes outcropping regionally, the most typical features being the Mesozoic and Cenozoic carbonate and evaporitic formations, overlain by flysch sequences, as well as granite intrusions and volcanic rocks. Moreover, two geothermal areas (Larderello and Mt. Amiata), a large number of thermal springs and CO2-rich gas vents are mostly present in the central-southern part of Tuscany. Finally in southern Tuscany (e.g. Campiglia M.Ma, Mt. Amiata, Elba Island), mining districts, predominantly characterized by polimetallic sulphides ore deposits, were exploited since the Etruscan time. In this work statistical distribution models are used to develop summary statistics and estimate probabilities of exceeding water-quality standards according to the National Legislative Decree 152/06. Descriptive statistics on solute concentrations are based on geochemical data from the main Tuscan aquifers and investigated by the CNR-IGG (Institute of Geosciences and Earth Resources of Pisa, Italy) and Department of Earth Sciences (University of Florence, Italy). The data processing was carried out on 4,767 water samples collected from 1997 to 2009. According to

  5. Searching for an Acidic Aquifer in the Rio Tinto Basin: First Geobiology Results of MARTE Project

    Science.gov (United States)

    Fernandez-Remolar, D. C.; Prieto-Ballesteros, O.; Stoker, C.

    2004-01-01

    Among the conceivable modern habitats to be explored for searching life on Mars are those potentially developed underground. Subsurface habitats are currently environments that, under certain physicochemical circumstances, have high thermal and hydrochemical stability [1, 2]. In planets like Mars lacking an atmospheric shield, such systems are obviously protected against radiation, which strongly alters the structure of biological macromolecules. Low porosity but fractured aquifers currently emplaced inside ancient volcano/sedimentary and hydrothermal systems act as excellent habitats [3] due to its thermal and geochemical properties. In these aquifers the temperature is controlled by a thermal balance between conduction and advection processes, which are driven by the rock composition, geological structure, water turnover of aquifers and heat generation from geothermal processes or chemical reactions [4]. Moreover, microbial communities based on chemolithotrophy can obtain energy by the oxidation of metallic ores that are currently associated to these environments. Such a community core may sustain a trophic web composed of non-autotrophic forms like heterotrophic bacteria, fungi and protozoa.

  6. Isotopic, hydrochemical, and hydrogeological study of deep aquifer of Sfax: First results

    International Nuclear Information System (INIS)

    Maliki, M. A.; Zouari, K.; Amouri, M.

    1996-01-01

    The water of the chlorinated sodic with chemical facies deep aquifer of Sfax presents a difference on the level of mineralization between the northern sector with a relatively weak salin charge (average of 3,5 g/l) and the southern sector with an important mineralization (about 10g/l). The mineralization of water in linked to dissolution phenomena. Based on the first isotopic results, it seems that the present refill of the deep aquifer of Sfax is very weak (author)

  7. Differential geochemical behaviour of natural isotopes of U and Th in an aquifer in humid tropical terrain

    International Nuclear Information System (INIS)

    Bonotto, D.M.

    1989-01-01

    Uranium and thorium isotopic analyses were performed on spoil samples from the saturated zone of a borehole drilled in the main ore body of a high grade thorium/rare earth ore, and on groundwaters from a borehole drilled in the zone. The deposit is located at Morro do Ferro, a hill near the centre of the Pocos de Caldas Plateau (MG), where an aquifer system developed in the weathered mantle due to in situ intense alteration. For extraction of uranium and thorium a long chemical process was applied to the samples; activities of Th-228 and Th-232 isotopes (4n series) and also of U-238, U-234 and Th-230 isotopes (4n+2 series) were determined by the alpha spectrometry method. U-234/U-238 activity ratios in groundwaters were between 1 and 2 but Th-228/Th-232 activity ratios showed marked isotopic fractionation between these nuclides. The mechanism of mobilization of uranium by complexation with humic substances is considered. U-234/U-238, Th-228/Th-232 and Th-230/U-234 activity ratios in soil samples allowed consider action of other possible mechanisms related to the mobilization of uranium, such as, ion-exchange reaction and adsorption by Fe and Mn oxides. (author) [pt

  8. Water-Rock Interactions in the Peridotite Aquifer of the Oman-UAE Ophiolite: Strontium Isotopic Ratio and Geochemical Evolution of Groundwater

    Science.gov (United States)

    Bompard, Nicolas; Matter, Juerg; Teagle, Damon

    2016-04-01

    The peridotite aquifer in Wadi Tayin, Sultanate of Oman, is a perfect example of natural carbonation of ultramafic rocks. In situ mineral carbonation is considered the most safest and permanent option of CO2 Capture and Sequestration (CCS). However, the process itself is yet to be characterised and a better understanding of the mechanisms involved in natural mineral carbonation is needed before geo-engineering it. We used the 87Sr/86Sr system to follow the water-rock interactions along the groundwater flowpath in the peridotite aquifer and to determine the sources of divalent cations (Mg2+, Ca2+) required for mineral carbonation. The Sr-isotope data of groundwater show that the aquifer rocks are the main source for divalent cations (Mg2+, Ca2+ and Sr2+) and secondary carbonates are their main sink. The groundwater 87Sr/86Sr ratio evolves with its pH: from 87Sr/86Sr = 0.7087 (n=3) to 0.7082 (n=8) between pH 7 and 8, and from 0.7086 (n=6) at pH 9 to 0.07075 (n=9) at pH 11. This evolution seems to support a two-step model for the water-rock interactions in the peridotite aquifer. From pH 7 to 8, secondary Ca-carbonate precipitation buffers the pH rise resulting from peridotite serpentinisation. From pH 9 to 11, peridotite serpentinisation drives the pH to alkaline condition. The change from a Mg-rich to a Ca-rich groundwater at pH 9 seems to confirm the two-step model.

  9. Factors affecting public-supply well vulnerability in two karst aquifers.

    Science.gov (United States)

    Musgrove, MaryLynn; Katz, Brian G; Fahlquist, Lynne S; Crandall, Christy A; Lindgren, Richard J

    2014-09-01

    Karst aquifers occur in a range of climatic and geologic settings. Nonetheless, they are commonly characterized by their vulnerability to water-quality impairment. Two karst aquifers, the Edwards aquifer in south-central Texas and the Upper Floridan aquifer in western Florida, were investigated to assess factors that control the movement of contaminants to public-supply wells (PSWs). The geochemistry of samples from a selected PSW or wellfield in each aquifer was compared with that from nearby monitoring wells and regional PSWs. Geochemistry results were integrated with age tracers, flow modeling, and depth-dependent data to refine aquifer conceptual models and to identify factors that affect contaminant movement to PSWs. The oxic Edwards aquifer is vertically well mixed at the selected PSW/wellfield, although regionally the aquifer is geochemically variable downdip. The mostly anoxic Upper Floridan aquifer is affected by denitrification and also is geochemically variable with depth. In spite of considerable differences in geology and hydrogeology, the two aquifers are similarly vulnerable to anthropogenic contamination. Vulnerability in studied PSWs in both aquifers is strongly influenced by rapid karst flowpaths and the dominance of young (aquifers (nitrate, atrazine, deethylatrazine, tetrachloroethene, and chloroform). Specific consideration of water-quality protection efforts, well construction and placement, and aquifer response times to land-use changes and contaminant loading are discussed, with implications for karst groundwater management. © 2014 The Authors. Groundwater published by Wiley Periodicals, Inc. on behalf of National Ground Water Association.

  10. Uruguay mining inventory. Geochemical prospecting results of the Amarillo aerial map

    International Nuclear Information System (INIS)

    Zeegers, H.; Spangenberg, J.

    1981-01-01

    This report is about the results of the geochemical prospection carried out on the Amarillo aerial map, it placed in the area 24 of Uruguay (G11 section).This prospection was carried out by Geologic Institute team of Uruguay (IGU) with the technical assistance of BRGM. The Amarillo aerial map covers parts of Isla Cristalina. This is the window of the insular precrambrian shelf and it is surounded by geological formation as paleozoic and other more reecently formations too. The precambrian formation are represented by three big whole groups: metamorphic serial; groups of intrusing granites; and metamorphic rocks

  11. 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

  12. Occurrence of geogenic contaminants in private wells from a crystalline bedrock aquifer in western Quebec, Canada: Geochemical sources and health risks

    Science.gov (United States)

    Bondu, Raphaël; Cloutier, Vincent; Rosa, Eric

    2018-04-01

    Nineteen private wells were investigated in order to evaluate the groundwater quality and the issues associated with well water use in a fractured metasedimentary aquifer of the Canadian Shield, in western Quebec (Canada). Groundwater sampling and analysis reveal that the quality of well water is both a potential aesthetic and health concern for the residents. Aesthetic problems are mainly related to the high levels of hardness and dissolved iron and manganese. Potential health risks are associated with the occurrence of brackish groundwater, high manganese concentrations, and arsenic concentrations exceeding the Canadian guideline value of 10 μg/l. Brackish groundwater is suspected to be derived from the mixing of fresh groundwaters with deep calcium-sodium-chloride brines of the Canadian Shield. The occurrences of iron, manganese and arsenic, primarily derived from the natural weathering of bedrock, are highly dependent on the geochemical conditions in groundwater, particularly the redox potential. Arsenic occurs mainly as arsenite (As(III)) and is thought to be released by the dissolution of iron and manganese oxyhydroxides under reducing conditions. Information obtained from well owners indicates that most households use ion exchange water softeners to minimize aesthetic problems of excessive hardness and dissolved iron and manganese concentrations. Homeowners generally take protective measures to reduce their exposure to arsenic when they are aware of the contamination. The exposure to arsenic and manganese may pose health risks for residents that do not take protective measures. The quality of well water is of paramount importance for human health in rural areas. Information on the contaminant sources and individual mitigation measures is essential to assess the health risks associated with groundwater consumption and to ensure the protection of public health.

  13. Hydrogeologic and geochemical characterization and evaluation of two arroyos for managed aquifer recharge by surface infiltration in the Pojoaque River Basin, Santa Fe County, New Mexico, 2014–15

    Science.gov (United States)

    Robertson, Andrew J.; Cordova, Jeffrey; Teeple, Andrew; Payne, Jason; Carruth, Rob

    2017-02-22

    available for storage in the unconsolidated channel sands (about 410 acre-feet in the east arroyo and about 190 acre-feet in the west arroyo) and the potential for the infiltrating water to preferentially flow over the bedrock contact and out of the reach present a challenge for storing water. Although a detailed assessment of the infiltration rate of the Tesuque Formation is beyond the scope of this investigation, one double-ring infiltrometer test was conducted on an outcrop, resulting in an estimated infiltration rate of about 4 feet per day.The shallow groundwater observed in this investigation was determined to be recharged locally on the basis of groundwater elevations and geochemical and isotopic signatures. The channel sands and shallow bedrock were observed to be weathered, indicating contact with oxic groundwater following deposition. This observation was supported by whole-rock elemental analysis and mineralogy of several core samples. The downward groundwater gradient between the shallow wells and those wells screened at greater depths suggests that the shallow groundwater is recharged by local precipitation and has the potential to migrate to the deeper aquifer units. The two age-dating tracers measured in this investigation, however, demonstrate that the shallow groundwater flow paths are very slow and that the deeper flow paths are likely part of a larger regional system.The composition of the shallow, native groundwater suggests that storing water diverted from the Rio Grande is not likely to leach constituents of concern that would cause the stored water to exceed health-based U.S. Environmental Protection Agency Maximum Contaminant Levels.

  14. Carboniferous Granitoid Magmatism of Northern Taimyr: Results of Isotopic-Geochemical Study and Geodynamic Interpretation

    Science.gov (United States)

    Kurapov, M. Yu.; Ershova, V. B.; Makariev, A. A.; Makarieva, E. V.; Khudoley, A. K.; Luchitskaya, M. V.; Prokopiev, A. V.

    2018-03-01

    Data on the petrography, geochemistry, and isotopic geochronology of granites from the northern part of the Taimyr Peninsula are considered. The Early-Middle Carboniferous age of these rocks has been established (U-Pb, SIMS). Judging by the results of 40Ar/39Ar dating, the rocks underwent metamorphism in the Middle Permian. In geochemical and isotopic composition, the granitic rocks have much in common with evolved I-type granites. This makes it possible to specify a suprasubduction marginal continental formation setting. The existence of an active Carboniferous margin along the southern edge of the Kara Block (in presentday coordinates) corroborates the close relationship of the studied region with the continent of Baltia.

  15. Preliminary geochemical, microbiological, and epidemiological investigations into possible linkages between lignite aquifers, pathogenic microbes, and kidney disease in northwestern Louisiana

    Science.gov (United States)

    Bunnell, Joseph E.; Bushon, Rebecca N.; Stoeckel, Donald M.; Gifford, Amie M.; Beck, Marisa; Lerch, Harry E.; Shi, Runhua; McGee, Benton; Hanson, Bradford C.; Kolak, Jonathan; Warwick, Peter D.

    2003-01-01

    detected in 4/8 (50 percent) of the surface water sites sampled. These initial results suggest that additional investigation into these relationships is warranted.

  16. Geochemical modelling of worst-case leakage scenarios at potential CO2-storage sites - CO2 and saline water contamination of drinking water aquifers

    Science.gov (United States)

    Szabó, Zsuzsanna; Edit Gál, Nóra; Kun, Éva; Szőcs, Teodóra; Falus, György

    2017-04-01

    Carbon Capture and Storage is a transitional technology to reduce greenhouse gas emissions and to mitigate climate change. Following the implementation and enforcement of the 2009/31/EC Directive in the Hungarian legislation, the Geological and Geophysical Institute of Hungary is required to evaluate the potential CO2 geological storage structures of the country. Basic assessment of these saline water formations has been already performed and the present goal is to extend the studies to the whole of the storage complex and consider the protection of fresh water aquifers of the neighbouring area even in unlikely scenarios when CO2 injection has a much more regional effect than planned. In this work, worst-case scenarios are modelled to understand the effects of CO2 or saline water leaks into drinking water aquifers. The dissolution of CO2 may significantly change the pH of fresh water which induces mineral dissolution and precipitation in the aquifer and therefore, changes in solution composition and even rock porosity. Mobilization of heavy metals may also be of concern. Brine migration from CO2 reservoir and replacement of fresh water in the shallower aquifer may happen due to pressure increase as a consequence of CO2 injection. The saline water causes changes in solution composition which may also induce mineral reactions. The modelling of the above scenarios has happened at several methodological levels such as equilibrium batch, kinetic batch and kinetic reactive transport simulations. All of these have been performed by PHREEQC using the PHREEQC.DAT thermodynamic database. Kinetic models use equations and kinetic rate parameters from the USGS report of Palandri and Kharaka (2004). Reactive transport modelling also considers estimated fluid flow and dispersivity of the studied formation. Further input parameters are the rock and the original ground water compositions of the aquifers and a range of gas-phase CO2 or brine replacement ratios. Worst-case scenarios

  17. Uruguay mining Inventory: geochemical prospecting results of Cerro de las Cuentas mapping

    International Nuclear Information System (INIS)

    Spangenberg, J.; Filippini, J.

    1986-01-01

    This work is about the geochemical prospecting carried out into the Uruguay mining inventory framework. In this case the survey was in Cerro de las Cuentas mapping. Cerro Largo department. Scale 1 / 50000.

  18. Groundwater-quality data in the Monterey–Salinas shallow aquifer study unit, 2013: Results from the California GAMA Program

    Science.gov (United States)

    Goldrath, Dara A.; Kulongoski, Justin T.; Davis, Tracy A.

    2016-09-01

    constituents (trace elements, nutrients, major and minor ions, silica, total dissolved solids, and alkalinity) were collected at all 170 sites. In addition to these constituents, the samples from grid wells were analyzed for organic constituents (volatile organic compounds, pesticides and pesticide degradates), constituents of special interest (perchlorate and N-nitrosodimethylamine, or NDMA), radioactive constituents (radon-222 and gross-alpha and gross-beta radioactivity), and geochemical and age-dating tracers (stable isotopes of carbon in dissolved inorganic carbon, carbon-14 abundances, stable isotopes of hydrogen and oxygen in water, and tritium activities).Three types of quality-control samples (blanks, replicates, and matrix spikes) were collected at up to 11 percent of the wells in the Monterey–Salinas Shallow Aquifer study unit, and the results for these samples were used to evaluate the quality of the data from the groundwater samples. With the exception of trace elements, blanks rarely contained detectable concentrations of any constituent, indicating that contamination from sample-collection procedures was not a significant source of bias in the data for the groundwater samples. Low concentrations of some trace elements were detected in blanks; therefore, the data were re-censored at higher reporting levels. Replicate samples generally were within the limits of acceptable analytical reproducibility. The median values of matrix-spike recoveries were within the acceptable range (70 to 130 percent) for the volatile organic compounds (VOCs) and N-nitrosodimethylamine (NDMA), but were only approximately 64 percent for pesticides and pesticide degradates.The sample-collection protocols used in this study were designed to obtain representative samples of groundwater. The quality of groundwater can differ from the quality of drinking water because water chemistry can change as a result of contact with plumbing systems or the atmosphere; because of treatment

  19. Use of mass balance and statistical correlation for geochemical and isotopic investigation of the groundwater in the quaternary aquifer of the nile delta, Egypt

    International Nuclear Information System (INIS)

    Awad, M.A.A.; Sadek, M.A.; Salem, W.M.

    1999-01-01

    A hydrochemical and environmental isotopic studies were conducted in the nile delta region, to investigate the sources of salinity and replenishment for the groundwater reservoir which are of importance for land reclamation projects and the establishment of new communities on the west and east side of the nile delta. The hydrogeological properties of the main exploitable aquifer (quaternary) was described. The chemistry of the collected surface and ground-waters was outlined through the analysis of major cations (Na + , K + , Ca ++ , Mg ++ ) and major anions (Ci - , SO 4 - , HCO 3 - ). The variation in chemical composition of examined waters is attributed to the use of fertilizers, leaching of terrestrial salts and ion exchange between soil's minerals and water, in addition to, sea water intrusion in some isolated areas near by saline bodies (mediterranean sea, manzala lake, suez canal). Oxygen-18 and deuterium concentrations were used to identify the mechanism of recharge. The results show a mixing between different sources of water: recent Nile, old Nil water before construction of high Aswan dam, coastal precipitation as well as some contribution from both sea water toward north and palaeo-water at the eastern and western fringes of the nile delta. In some localities the recharge occurs indirectly after evaporation and/or vertical leakage of deep water due to over-pumping rates. This paper also demonstrates the implementation of statistical correlation and mass balance approaches to present the chemical and isotopic characterization of the nile delta quaternary aquifer. Recommendations are given for optimal use of water resources in the area of study

  20. Characterization of recharge processes in shallow and deeper aquifers using isotopic signatures and geochemical behavior of groundwater in an arsenic-enriched part of the Ganga Plain

    International Nuclear Information System (INIS)

    Saha, Dipankar; Sinha, U.K.; Dwivedi, S.N.

    2011-01-01

    Research highlights: → Sub-regional scale aquifers delineated in arsenic-enriched belt in the Ganga Plain. Isotopic fingerprint of the groundwater, from arsenic-enriched and arsenic-safe aquifers established for the first time in the Ganga Plain. → Recharge processes and the water provenances of vertically separated Quaternary aquifers have been established. → Mean residence time of groundwater in the deeper aquifers has been worked out using C-14 isotope. → Water from the deeper aquifer has been correlated with the paleoclimatic model of the Middle Ganga Plain (Mid-Ganga Basin) for 6-2 ka. - Abstract: Arsenic concentrations in groundwater extracted from shallow aquifers in some areas of the Ganga Plain in the states of Bihar and Uttar Pradesh, exceed 50 μg L -1 and locally reach levels in the 400 μg L -1 range. The study covered 535 km 2 of active flood plain of the River Ganga, in Bihar where a two-tier aquifer system has been delineated in a multi-cyclic sequence of Quaternary sand, clay, sandy clay and silty clay all ≤∼250 m below ground surface. The research used isotopic signatures (δ 18 O, δ 2 Η, 3 H, 14 C) and major chemical constituents (HCO 3 - ,SO 4 2- ,NO 3 - ,Cl - ,Ca 2+ ,Mg 2+ ,Na + ,K + ,As total ) of groundwater to understand the recharge processes and groundwater circulation in the aquifers. Values of δ 18 O and δ 2 Η combined with 3 H data indicate that the recharge to the As-enriched top 40 m of the deposits is modern ( -1 ) is hydrologically isolated from the upper aquifer and is characterized by lower 14 C concentration and lower (more negative) δ 18 O values. Groundwater in the lower aquifer is ∼3 ka old, occurs under semi-confined to confined conditions, with hydrostatic head at 1.10 m above the head of the upper aquifer during the pre-monsoon. The recharge areas of the lower aquifer lies in Pleistocene deposits in basin margin areas with the exposed Vindhyan System, at about 55 km south of the area.

  1. Geochemical results of a hydrothermally altered area at Baker Creek, Blaine County, Idaho

    Science.gov (United States)

    Erdman, James A.; Moye, Falma J.; Theobald, Paul K.; McCafferty, Anne E.; Larsen, Richard K.

    2001-01-01

    The area immediately east of Baker Creek, Blaine County, Idaho, is underlain by a thick section of mafic to intermediate lava flows of the Eocene Challis Volcanic Group. Widespread propylitic alteration surrounds a zone of argillic alteration and an inner core of phyllic alteration. Silicified breccia is present along an east-trending fault within the zone of phyllic alteration. As part of a reconnaissance geochemical survey, soils and plants were sampled. Several species of plants (Douglas-fir [ Pseudotsuga menziesii ], mountain big sagebrush [ Artemisia tridentata ssp. vaseyana ], and elk sedge [ Carex geyerii ]) were collected from 10 upland localities and stream sediments, panned concentrates, and aquatic mosses were collected from 16 drainage basin localities all of which were generally within the area of alteration. Geochemical results yielded anomalous concentrations of molybenum, zinc, silver, and lead in at least half of the seven different sample media and of gold, thallium, arsenic, antimony, manganese, boron, cadmium, bismuth, copper, and beryllium in from one to four of the various media. Part of this suite of elements? silver, gold, arsenic, antimony, thallium, and manganese? suggests that the mineralization in the area is epithermal. Barite and pyrite (commonly botryoidal-framboidal) are widespread throughout the area sampled. Visible gold and pyromorphite (a secondary lead mineral) were identified in only one small drainage basin, but high levels of gold were detected in aquatic mosses over a larger area. Data from the upland and stream sampling indicate two possible mineralized areas. The first mineralized area was identified by a grab sample from an outcrop of quartz stockwork that contained 50 ppb Au, 1.5 ppm Ag, and 50 ppm Mo. Although the soil and plant species that were sampled in the area indicated mineralized bedrock, the Douglas-fir samples were the best indicators of the silver anomaly. The second possible mineralized area centers on the

  2. Behaviour and fate of nine recycled water trace organics during managed aquifer recharge in an aerobic aquifer

    Science.gov (United States)

    Patterson, B. M.; Shackleton, M.; Furness, A. J.; Bekele, E.; Pearce, J.; Linge, K. L.; Busetti, F.; Spadek, T.; Toze, S.

    2011-03-01

    The fate of nine trace organic compounds was evaluated during a 12 month large-scale laboratory column experiment. The columns were packed with aquifer sediment and evaluated under natural aerobic and artificial anaerobic geochemical conditions, to assess the potential for natural attenuation of these compounds during aquifer passage associated with managed aquifer recharge (MAR). The nine trace organic compounds were bisphenol A (BPA), 17β-estradiol (E2), 17α-ethynylestradiol (EE2), N-nitrosodimethylamine (NDMA), N-nitrosomorpholine (NMOR), carbamazepine, oxazepam, iohexol and iodipamide. In the low organic carbon content Spearwood sediment, all trace organics were non-retarded with retardation coefficients between 1.0 and 1.2, indicating that these compounds would travel at near groundwater velocities within the aquifer. The natural aerobic geochemical conditions provided a suitable environment for the rapid degradation for BPA, E2, iohexol (half life NDMA and NMOR) did not degrade under either aerobic or anaerobic aquifer geochemical conditions (half life > 50 days). Field-based validation experiments with carbamazepine and oxazepam also showed no degradation. If persistent trace organics are present in recycled waters at concentrations in excess of their intended use, natural attenuation during aquifer passage alone may not result in extracted water meeting regulatory requirements. Additional pre treatment of the recycled water would therefore be required.

  3. Behaviour and fate of nine recycled water trace organics during managed aquifer recharge in an aerobic aquifer.

    Science.gov (United States)

    Patterson, B M; Shackleton, M; Furness, A J; Bekele, E; Pearce, J; Linge, K L; Busetti, F; Spadek, T; Toze, S

    2011-03-25

    The fate of nine trace organic compounds was evaluated during a 12month large-scale laboratory column experiment. The columns were packed with aquifer sediment and evaluated under natural aerobic and artificial anaerobic geochemical conditions, to assess the potential for natural attenuation of these compounds during aquifer passage associated with managed aquifer recharge (MAR). The nine trace organic compounds were bisphenol A (BPA), 17β-estradiol (E2), 17α-ethynylestradiol (EE2), N-nitrosodimethylamine (NDMA), N-nitrosomorpholine (NMOR), carbamazepine, oxazepam, iohexol and iodipamide. In the low organic carbon content Spearwood sediment, all trace organics were non-retarded with retardation coefficients between 1.0 and 1.2, indicating that these compounds would travel at near groundwater velocities within the aquifer. The natural aerobic geochemical conditions provided a suitable environment for the rapid degradation for BPA, E2, iohexol (half life aquifer geochemical conditions (half life >50days). Field-based validation experiments with carbamazepine and oxazepam also showed no degradation. If persistent trace organics are present in recycled waters at concentrations in excess of their intended use, natural attenuation during aquifer passage alone may not result in extracted water meeting regulatory requirements. Additional pre treatment of the recycled water would therefore be required. Crown Copyright © 2010. Published by Elsevier B.V. All rights reserved.

  4. Characterization of 200-UP-1 Aquifer Sediments and Results of Sorption-Desorption Tests Using Spiked Uncontaminated Groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Um, Wooyong; Serne, R JEFFREY.; Bjornstad, Bruce N.; Schaef, Herbert T.; Brown, Christopher F.; Legore, Virginia L.; Geiszler, Keith N.; Baum, Steven R.; Valenta, Michelle M.; Kutnyakov, Igor V.; Vickerman, Tanya S.; Lindberg, Michael J.

    2005-11-16

    Core characterization showed only 4 out of 13 core liner samples were intact samples and that the others were slough material. The intact samples showed typical Ringold Unit E characteristics such as being dominated by gravel and sand. Moderately reducing conditions are inferred in some core from borehole C4299. This reducing condition was caused by the hard tool process used to drill the wells. One core showed significant presence of ferric iron oxide/clay coatings on the gravels. There were no highly contaminated sediments found in the cores from the three new boreholes in UP-1 operable unit, especially for uranium. The presence of slough and ''flour'' caused by hard tooling is a serious challenge to obtaining field relevant sediments for use in geochemical experiments to determine the adsorption-desorption tendencies of redox sensitive elements such as uranium. The adsorption of COCs on intact Ringold Formation sediments and Fe/clay coatings showed that most of the anionic contaminants [Tc(VII), Se(VI), U(VI), Cr(VI), and I(-I)] did not adsorbed very well compared to cationic [Np(V), Sr(II), and Cs(I)] radionuclides. The high hydrous iron oxide content in Fe/clay coatings caused the highest Kd values for U and Np, suggesting these hydrous oxides are the key solid adsorbent in the sediments. Enhanced adsorption behavior for Tc, and Cr and perhaps Se on the sediments was considered an ?artifact? result caused by the induced reducing conditions from the hard tool drilling. Additional U(VI) adsorption Kd studies were performed on Ringold Formation sediments to develop more robust Kd data base for U. The <2 mm size separates of three UP-1 sediments showed a linear U(VI) adsorption isotherm up 1 ppm of total U(VI) concentration in solution. The additional U(VI) Kds obtained from varying carbonate concentration indicated that U(VI) adsorption was strongly influenced by the concentration of carbonate in solution. U(VI) adsorption decreased with

  5. Adsorption of phosphate from municipal effluents using cryptocrystalline magnesite: complementing laboratory results with geochemical modelling

    CSIR Research Space (South Africa)

    Masindi, Vhahangwele

    2015-11-01

    Full Text Available chemisorption. Adsorption isotherms fitted well to Langmuir adsorption isotherm than Freundlich adsorption isotherms, demonstrating monolayer adsorption. PHREEQC geochemical model showed Mg(sub3)(PO(sub4))(sub2) and MgHPO(sub4):3H(sub2)O as the phosphatebearing...

  6. Uruguay mining inventory. Geochemical prospecting results of the Las Flores aerial map

    International Nuclear Information System (INIS)

    Zeegers, H.; Bonnefoy, D.; Garau, M.; Spangenberg, J.

    1981-01-01

    In the context of the Uruguay mining inventory, the aerial photography map Las Flores had been covered by a specific strategic which included geochemical prospecting elements. The surface covered has the 550 km2, and 1042 samples which they have been analized in Orleans France. 22 elements by plasma spectroscopy and gold by atomic absorption and for uranium laser spectroscopy . They have been evidenced the following anomalies: gold, Pb, Pb-Ba-Cu, Ba and Ni-Cr

  7. Microbial and geochemical investigations of dissolved organic carbon and microbial ecology of native waters from the Biscayne and Upper Floridan Aquifers

    Science.gov (United States)

    Lisle, John T.; Harvey, Ron W.; Aiken, George R.; Metge, David W.

    2010-01-01

    Groundwater resources in the United States are under ever-increasing demands for potable, irrigation, and recreational uses. Additionally, aquifer systems are being used or targeted for use as storage areas for treated surface waters and (or) groundwaters via injection (for example, aquifer storage and recovery). To date, the influence that the nutrients, including carbon, in the injected water have on native microbial communities and the biogeochemistry in the subsurface zones used for storage of the injectate has not been determined. In this report, we describe a series of experiments that establishes a baseline dataset for the quantity and quality of organic and inorganic carbon and nutrients in the Biscayne Aquifer (BA) and Upper Floridan Aquifer (UFA) in south Florida. The most significant differences between the BA (26 meters below surface) and UFA (366 meters below surface) are the average specific conductance (0.552 and 6.12 microsiemens per centimeter, respectively), dissolved oxygen (1.6 and 0 milligrams per liter, respectively), and oxidation-reduction potential (40.3 and -358 millivolts, respectively). The dissolved organic carbon from the BA is characterized by carbon originating from terrestrial sources and microbial activities, while the UFA has a distinctive microbial signature. Acetate and lactate are the dominant carbon constituents in both aquifers. Additionally, components of the dissolved organic carbon from the UFA have a total trihalomethane-formation potential that is approximately threefold greater than the maximum contaminat level of 80 micrograms per liter established by the U.S. Environmental Protection Agency. The average native bacterial abundances in the aquifers are similar with 4.69x10^4 cells per milliliter in the BA and 1.33x10^4 cells per milliliter in the UFA. The average bacteriophage abundances are also similar with 1.15x10^5 virus-like particles in the BA and 1.92x10^5 virus-like particles in the UFA. Interestingly, ciliated

  8. Feasibility of Autonomous Monitoring of CO2 Leakage in Aquifers: Results From Controlled Laboratory Experiments

    Science.gov (United States)

    Versteeg, R.; Leger, E.; Dafflon, B.

    2016-12-01

    Geologic sequestration of CO2 is one of the primary proposed approaches for reducing total atmospheric CO2 concentrations. MVAA (Monitoring, Verification, Accounting and Assessment) of CO2 sequestration is an essential part of the geologic CO2 sequestration cycle. MVAA activities need to meet multiple operational, regulatory and environmental objectives, including ensuring the protection of underground sources of drinking water. Anticipated negative consequences of CO2 leakage into groundwater, besides possible brine contamination and release of gaseous CO2, include a significant increase of dissolved CO2 into shallow groundwater systems, which will decrease groundwater pH and can potentially mobilize naturally occurring trace metals and ions that are commonly absorbed to or contained in sediments. Autonomous electrical geophysical monitoring in aquifers has the potential of allowing for rapid and automated detection of CO2 leakage. However, while the feasibility of such monitoring has been demonstrated by a number of different field experiments, automated interpretation of complex electrical resistivity data requires the development of quantitative relationships between complex electrical resistivity signatures and dissolved CO2 in the aquifer resulting from leakage Under a DOE SBIR funded effort we performed multiple tank scale experiments in which we investigated complex electrical resistivity signatures associated with dissolved CO2 plumes in saturated sediments. We also investigated the feasibility of distinguishing CO2 leakage signatures from signatures associated with other processes such as salt water movement, temperature variations and other variations in chemical or physical conditions. In addition to these experiments we also numerically modeled the tank experiments. These experiments showed that (a) we can distinguish CO2 leakage signatures from other signatures, (b) CO2 leakage signatures have a consistent characteristic, (c) laboratory experiments

  9. Results of geochemical and mineralogical studies on uranium in Zechstein copper-bearing strata from Lubin-Polkowice area

    International Nuclear Information System (INIS)

    Bareja, E.

    1977-01-01

    The paper presents the results of geochemical and mineralogical studies on uranium in Zechstein copper-bearing strata from the Lubin-Polkowice area. It was found that particular lithofacial varietes of Zechstein copper-bearing strata are characterized by different concentration of uranium. The mineralogical studies made possible determination of the nature of uranium mineralization and the interdependence between uranium and lithology of copper-bearing strata. An interesting uranium mineralization was found in tectonic breccias which yield black blende and schroeckingerite as well as calcite, gypsum, pyrite, hematite and geothite. Secondary minerals such as schroeckingerite and geothite evidence intense weathering processes acting in the copper deposit. The highest value of geochemical background of uranium in the copper-bearing series is displayed by basel copper-bearing shales (so called pitch-black shales) - 68.10 x 10 -40 /0 U. Statistical distribution of that element is unimodal. Distribution of uranium is polymodal in basal sandstones of the copper-bearing series. The geochemical background of red-coloured sandstones (Rotliegendes) is low, equalling 0.39 x 10 40 /0 U, whilst that of gray-coloured sandstones (Zechstein) - 2.32 x 10 -40 /0 U. An anomallous population (344.0 x 10 -40 /0 U) found in the case of gray sandstones of the Lubin-Polkowice area evidences the effects of secondary processes on concentration of uranium. In sandstones occur black blende, carburanes as well as calcite, hematite and goethite. A bimodal distribution of uranium was found in carbonate series. Limestones are characterized by low value of geochemical background (Dsub(x1) = 0.78 x 10 -40 /0 U) whilst dolomites by markedly higher values of the background (Dsub(x2) = 2.73 x 10 -40 /0 U). (author)

  10. Geochemical modelling baseline compositions of groundwater

    DEFF Research Database (Denmark)

    Postma, Diederik Jan; Kjøller, Claus; Andersen, Martin Søgaard

    2008-01-01

    and variations in water chemistry that are caused by large scale geochemical processes taking place at the timescale of thousands of years. The most important geochemical processes are ion exchange (Valreas and Aveiro) where freshwater solutes are displacing marine ions from the sediment surface, and carbonate......Reactive transport models, were developed to explore the evolution in groundwater chemistry along the flow path in three aquifers; the Triassic East Midland aquifer (UK), the Miocene aquifer at Valreas (F) and the Cretaceous aquifer near Aveiro (P). All three aquifers contain very old groundwaters...... dissolution (East Midlands, Valreas and Aveiro). Reactive transport models, employing the code PHREEQC, which included these geochemical processes and one-dimensional solute transport were able to duplicate the observed patterns in water quality. These models may provide a quantitative understanding...

  11. Using enteric pathogens to assess sources of fecal contamination in the Silurian Dolomite Aquifer: Preliminary results

    Science.gov (United States)

    Muldoon, Maureen A; Borchardt, Mark A.; Spencer, Susan K.; Hunt, Randall J.; Owens, David

    2018-01-01

    The fractured Silurian dolomite aquifer is an important, but vulnerable, source of drinking water in northeast Wisconsin (Sherrill in Geology and ground water in Door County, Wisconsin, with emphasis on contamination potential in the Silurian dolomite, 1978; Bradbury and Muldoon in Hydrogeology and groundwater monitoring of fractured dolomite in the Upper Door Priority Watershed, Door County, Wisconsin, 1992; Muldoon and Bradbury in Assessing seasonal variations in recharge and water quality in the Silurian aquifer in areas with thicker soil cover. p 45, 2010). Areas underlain by the Silurian dolomite aquifer are extremely vulnerable to groundwater contamination from various land-use activities, especially the disposal of human wastewater and dairy manure. Currently there is no consensus as to which source of wastewater generates the greater impact to the aquifer.

  12. Relation between "terra rossa" from the Apulia aquifer of Italy and the radon content of groundwater: Experimental results and their applicability to radon occurrence in the aquifer

    Science.gov (United States)

    Tadolini, T.; Spizzico, M.

    The radon-222 (222Rn) activity in groundwater of the Apulian karstic aquifer in southern Italy is as great as 500 Becquerel per liter (Bq/L) locally. Normal radium-226 (226Ra) activity in the limestone and calcareous dolomites of the aquifer is not enough to explain such a high level. Laboratory investigations identified high 226Ra activity in the "terra rossa," the residuum occupying fissures and cavities in the bedrock, and also the relation between (1) 226Ra-bearing bedrock and "terra rossa" and (2) 222Rn in water. The "terra rossa" is the primary source of the radon in the groundwater. The experimental results show the need to characterize the "terra rossa" of Apulia on the basis of 226Ra activity and also to study the distribution and variations in 222Rn activity over time in the aquifer. Résumé L'activité du radon-222 (222Rn) dans les eaux souterraines de l'aquifère karstique des Pouilles, dans le sud de l'Italie, atteint localement 500 Becquerel par litre (Bq/L). L'activité normale du radium-226 (226Ra) dans les calcaires et dans les calcaires dolomitiques de l'aquifère n'est pas assez élevée pour expliquer des valeurs aussi élevées. Des analyses de laboratoire ont mis en évidence une forte activité en 226Ra dans la terra rossa, remplissage de fissures et de cavités de la roche, ainsi qu'une relation entre (1) la roche et la terra rossa contenant du 226Ra et (2) le 222Rn dans l'eau. La terra rossa est la source primaire de radon dans l'eau souterraine. Les résultats expérimentaux montrent qu'il est nécessaire de caractériser la terra rossa des Pouilles par son activité en 226Ra et d'étudier la distribution et les variations de l'activité en 222Rn au cours du temps dans l'aquifère. Resumen La actividad del radon-222 (222Rn) en el agua subterránea del acuífero cárstico de Apulia, al sur de Italia, alcanza localmente los 500Bq/L. La actividad normal del radio-226 (226Ra) en las calcitas y dolomitas del acuífero no es suficiente para

  13. 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.

  14. Geochemistry of the Springfield Plateau aquifer of the Ozark Plateaus Province in Arkansas, Kansas, Missouri and Oklahoma, USA

    Science.gov (United States)

    Adamski, J.C.

    2000-01-01

    Geochemical data indicate that the Springfield Plateau aquifer, a carbonate aquifer of the Ozark Plateaus Province in central USA, has two distinct hydrochemical zones. Within each hydrochemical zone, water from springs is geochemically and isotopically different than water from wells. Geochemical data indicate that spring water generally interacts less with the surrounding rock and has a shorter residence time, probably as a result of flowing along discrete fractures and solution openings, than water from wells. Water type throughout most of the aquifer was calcium bicarbonate, indicating that carbonate-rock dissolution is the primary geochemical process occurring in the aquifer. Concentrations of calcium, bicarbonate, dissolved oxygen and tritium indicate that most ground water in the aquifer recharged rapidly and is relatively young (less than 40 years). In general, field-measured properties, concentrations of many chemical constituents, and calcite saturation indices were greater in samples from the northern part of the aquifer (hydrochemical zone A) than in samples from the southern part of the aquifer (hydrochemical zone B). Factors affecting differences in the geochemical composition of ground water between the two zones are difficult to identify, but could be related to differences in chert content and possibly primary porosity, solubility of the limestone, and amount and type of cementation between zone A than in zone B. In addition, specific conductance, pH, alkalinity, concentrations of many chemical constituents and calcite saturation indices were greater in samples from wells than in samples from springs in each hydrochemical zone. In contrast, concentrations of dissolved oxygen, nitrite plus nitrate, and chloride generally were greater in samples from springs than in samples from wells. Water from springs generally flows rapidly through large conduits with minimum water-rock interactions. Water from wells flow through small fractures, which restrict

  15. New results of microfaunal and geochemical investigations in the Permian-Triassic boundary interval from the Jadar Block (NW Serbia)

    Science.gov (United States)

    Sudar, Milan N.; Kolar-Jurkovšek, Tea; Nestell, Galina P.; Jovanović, Divna; Jurkovšek, Bogdan; Williams, Jeremy; Brookfield, Michael; Stebbins, Alan

    2018-04-01

    Detail results of microfaunal, sedimentological and geochemical investigations are documented from a newly discovered section of the Permian-Triassic boundary (PTB) interval in the area of the town of Valjevo (northwestern Serbia). The presence of various and abundant microfossils (conodonts, foraminifers, and ostracodes) found in the Upper Permian "Bituminous limestone" Formation enabled a determination of the Changhsingian Hindeodus praeparvus conodont Zone. This paper is the first report of latest Permian strata from the region, as well as from all of Serbia, where the PTB interval sediments have been part of a complex/integrated study by means of biostratigraphy and geochemistry.

  16. New results of microfaunal and geochemical investigations in the Permian–Triassic boundary interval from the Jadar Block (NW Serbia

    Directory of Open Access Journals (Sweden)

    Sudar Milan N.

    2018-04-01

    Full Text Available Detail results of microfaunal, sedimentological and geochemical investigations are documented from a newly discovered section of the Permian–Triassic boundary (PTB interval in the area of the town of Valjevo (northwestern Serbia. The presence of various and abundant microfossils (conodonts, foraminifers, and ostracodes found in the Upper Permian “Bituminous limestone” Formation enabled a determination of the Changhsingian Hindeodus praeparvus conodont Zone. This paper is the first report of latest Permian strata from the region, as well as from all of Serbia, where the PTB interval sediments have been part of a complex/integrated study by means of biostratigraphy and geochemistry.

  17. Geophysics- and geochemistry-based assessment of the geochemical characteristics and groundwater-flow system of the U.S. part of the Mesilla Basin/Conejos-Médanos aquifer system in Doña Ana County, New Mexico, and El Paso County, Texas, 2010–12

    Science.gov (United States)

    Teeple, Andrew P.

    2017-06-16

    (reported but not used in the assessment), and environmental tracers. The data obtained from these samples (with the exception of the pesticide data) were used to gain insights into processes controlling the groundwater movement through the groundwater system in the study area. Results from the geophysical and geochemical assessments facilitated the interpretation of the geochemical characteristics of the groundwater sources and geochemical groups within the groundwater system.The groundwater-flow system in the study area consists primarily of the Mesilla Basin aquifer system, which can be divided into four hydrogeologic units by using an informal classification scheme based on basin-fill stratigraphy and sedimentology with an emphasis on aquifer characteristics. The four hydrogeologic units are (1) the Rio Grande alluvium, which is the shallow aquifer of the Mesilla Basin within the confines of the Mesilla Valley, and the three hydrogeologic units that compose the Santa Fe Group: (2) the lower part of the Santa Fe Group, which is the least productive zone, (3) the middle part of the Santa Fe Group, which is the primary water-bearing hydrogeologic unit in the basin and is generally saturated, and (4) the upper part of the Santa Fe Group, which is the most productive water-bearing unit within the Santa Fe Group but is only partially saturated in the north and largely unsaturated in the south and western parts of the Mesilla Basin.The helicopter frequency domain electromagnetic survey results indicated that approximately half of the resistivity values were less than 10 ohm-meters at depths of 50 and 100 feet with a transition where the resistivity values changed from relatively high values (greater than 20 ohm-meters) to relatively low resistivity values (less than 10 ohm-meters) near Vado, New Mexico. Slightly more than 25 percent of the gridded resistivity values from the three-dimensional grid of the combined inverse modeling results of the direct-current resistivity and

  18. Results of the determination of He in cenozoic aquifers using the GC method.

    Science.gov (United States)

    Kotowski, Tomasz; Najman, Joanna

    2015-04-01

    Applications of the Helium (He) method known so far consisted mainly of 4He measurements using a special mass spectrometer. 4He measurements for groundwater dating purposes can be replaced by total He (3He+4He) concentration measurements because the content of 3He can be ignored. The concentrations of 3He are very low and 3He/4 He ratios do not exceed 1.0·10(-5) in most cases. In this study, the total He concentrations in groundwater were determined using the gas chromatographic (GC) method as an alternative to methods based on spectrometry measurement. He concentrations in groundwater were used for the determination of residence time and groundwater circulation. Additionally, the radiocarbon method was used to determine the value of the external He flux (JHe) in the study area. Obtained low He concentrations and their small variation within the ca. 65 km long section along which groundwater flows indicate that it is likely there is relatively short residence time and a strong hydraulic connection between the aquifers. The estimated residence time (ca. 3000 years) is heavily dependent on the great uncertainty of the He concentration resulting from the low concentrations of He, the external 4He flux value adopted for calculation purposes and the 14C ages used to estimate the external 4He flux. © 2015, National Ground Water Association.

  19. Seismo-Geochemical Variations in SW Taiwan: Multi-Parameter Automatic Gas Monitoring Results

    Science.gov (United States)

    Yang, T. F.; Fu, C.-C.; Walia, V.; Chen, C.-H.; Chyi, L. L.; Liu, T.-K.; Song, S.-R.; Lee, M.; Lin, C.-W.; Lin, C.-C.

    2006-04-01

    Gas variations of many mud volcanoes and hot springs distributed along the tectonic sutures in southwestern Taiwan are considered to be sensitive to the earthquake activity. Therefore, a multi-parameter automatic gas station was built on the bank of one of the largest mud-pools at an active fault zone of southwestern Taiwan, for continuous monitoring of CO2, CH4, N2 and H2O, the major constituents of its bubbling gases. During the year round monitoring from October 2001 to October 2002, the gas composition, especially, CH4 and CO2, of the mud pool showed significant variations. Taking the CO2/CH4 ratio as the main indicator, anomalous variations can be recognized from a few days to a few weeks before earthquakes and correlated well with those with a local magnitude >4.0 and local intensities >2. It is concluded that the gas composition in the area is sensitive to the local crustal stress/strain and is worthy to conduct real-time monitoring for the seismo-geochemical precursors.

  20. On the interaction of pure and impure supercritical CO2 with rock forming minerals in saline aquifers: An experimental geochemical approach

    International Nuclear Information System (INIS)

    Wilke, Franziska D.H.; Vásquez, Mónica; Wiersberg, Thomas; Naumann, Rudolf; Erzinger, Jörg

    2012-01-01

    The aim of this experimental study was to evaluate and compare the geochemical impact of pure and impure CO 2 on rock forming minerals of possible CO 2 storage reservoirs. This geochemical approach takes into account the incomplete purification of industrial captured CO 2 and the related effects during injection, and provides relevant data for long-term storage simulations of this specific greenhouse gas. Batch experiments were conducted to investigate the interactions of supercritical CO 2 , brine and rock-forming mineral concentrates (albite, microcline, kaolinite, biotite, muscovite, calcite, dolomite and anhydrite) using a newly developed experimental setup. After up to 42 day (1000 h) experiments using pure and impure supercritical CO 2 the dissolution and solution characteristics were examined by XRD, XRF, SEM and EDS for the solid, and ICP–MS and IC for the fluid reactants, respectively. Experiments with mixtures of supercritical CO 2 (99.5 vol.%) and SO 2 or NO 2 impurities (0.5 vol.%) suggest the formation of H 2 SO 4 and HNO 3 , reflected in pH values between 1 and 4 for experiments with silicates and anhydrite and between 5 and 6 for experiments with carbonates. These acids should be responsible for the general larger amount of cations dissolved from the mineral phases compared to experiments using pure CO 2 . For pure CO 2 a pH of around 4 was obtained using silicates and anhydrite, and 7–8 for carbonates. Dissolution of carbonates was observed after both pure and impure CO 2 experiments. Anhydrite was corroded by approximately 50 wt.% and gypsum precipitated during experiments with supercritical CO 2 + NO 2 . Silicates do not exhibit visible alterations during all experiments but released an increasing amount of cations in the reaction fluid during experiments with impure CO 2 . Nonetheless, precipitated secondary carbonates could not be identified.

  1. Geochemical And Hydrodynamic Behavior Of The Karstic Aquifer System In The Portion Between Akumal And Boca Paila, In The South Eastern Coast Of The Yucatan Peninsula.

    Science.gov (United States)

    Velazquez Oliman, G.; Leal Bautista, R. M.; Perry, E. C.; Carrol, M.; Wagner, N.; Castillo Oliman, P.

    2008-12-01

    We report here aspects of the geochemistry and hydrodynamics of a nearly 450 km2 area that constitutes part of the rapidly developing tourist corridor between Akumal and Boca Paila, Quintana Roo, Mexico. Some of the largest explored submerged cave systems in the world, including Nohoch Nah Chic and Dos Ojos, are within the study area. The presence of these and other highly permeable conduits highlights the importance of a better understanding of the aquifer system both to assess its vulnerability and to facilitate sustainable water management. This study focuses on major ion, trace element, and stable isotope geochemistry of groundwater and on monitoring system hydrodynamics through water levels measurements. Sampling along approximately 30 km of coast was accomplished by means of a network of 29 sampling sites arranged along three NW-SE transverse lines running approximately perpendicular to the coast and each extending about 16 km inland. To date 52 samples have been taken. In addition, vertical specific conductivity profiles have helped delineate the thickness of the freshwater lens, which has a maximum thickness of 33.5 m in the southwestern part of the study area, approximately 13.5 km from the coast. In the northeastern corner of the study area, 7.5 m of brackish water overlies sea water near the coast. Water level monitoring is by means of Schlumberger pressure transducers installed at 11 sites. Water table changes record tidal oscillation, confirming the interconnectedness of the system, an observation supported by conductivity measurements that indicate oscillatory vertical movement of the saline interface. (SO4/Cl) ratios, expressed as 1000(SO4/Cl) in meq/kg, are useful tracers of groundwater provenance. The ratio is approximately 100 for seawater and is much greater for groundwater in southern Quintana Roo that has dissolved evaporite (Perry et al, 2002). Ratios in the study area, which are 100 or less, indicate no contact with evaporite. Background

  2. A convenient method for estimating the contaminated zone of a subsurface aquifer resulting from radioactive waste disposal into ground

    International Nuclear Information System (INIS)

    Fukui, Masami; Katsurayama, Kousuke; Uchida, Shigeo.

    1981-01-01

    Studies were conducted to estimate the contamination spread resulting from the radioactive waste disposal into a subsurface aquifer. A general equation, expressing the contaminated zone as a function of radioactive decay, the physical and chemical parameters of soil is presented. A distribution coefficient was also formulated which can be used to judge the suitability of a site for waste disposal. Moreover, a method for predicting contaminant concentration in groundwater at a site boundary is suggested for a heterogeneous media where the subsurface aquifer has different values of porosity, density, flow velocity, distribution coefficient and so on. A general equation was also developed to predict the distribution of radionuclides resulting from the disposal of a solid waste material. The distributions of contamination was evaluated for 90 Sr and 239 Pu which obey a linear adsorption model and a first order kinetics respectively. These equations appear to have practical utility for easily estimating groundwater contamination. (author)

  3. Review of simulation techniques for Aquifer Thermal Energy Storage (ATES)

    Science.gov (United States)

    Mercer, J. W.; Faust, C. R.; Miller, W. J.; Pearson, F. J., Jr.

    1981-03-01

    The analysis of aquifer thermal energy storage (ATES) systems rely on the results from mathematical and geochemical models. Therefore, the state-of-the-art models relevant to ATES were reviewed and evaluated. These models describe important processes active in ATES including ground-water flow, heat transport (heat flow), solute transport (movement of contaminants), and geochemical reactions. In general, available models of the saturated ground-water environment are adequate to address most concerns associated with ATES; that is, design, operation, and environmental assessment. In those cases where models are not adequate, development should be preceded by efforts to identify significant physical phenomena and relate model parameters to measurable quantities.

  4. Results from a workshop on research needs for modeling aquifer thermal energy storage systems

    Science.gov (United States)

    Drost, M. K.

    1990-08-01

    A workshop an aquifer thermal energy storage (ATES) system modeling was conducted by Pacific Northwest Laboratory (PNL). The goal of the workshop was to develop a list of high priority research activities that would facilitate the commercial success of ATES. During the workshop, participants reviewed currently available modeling tools for ATES systems and produced a list of significant issues related to modeling ATES systems. Participants assigned a priority to each issue on the list by voting and developed a list of research needs for each of four high-priority research areas; the need for a feasibility study model, the need for engineering design models, the need for aquifer characterization, and the need for an economic model. The workshop participants concluded that ATES commercialization can be accelerated by aggressive development of ATES modeling tools and made specific recommendations for that development.

  5. Hydric results in Guarani Aquifer System formation zone through by hydrogeological monitoring in representative basin

    International Nuclear Information System (INIS)

    Wendland, E.; Barreto, C.; Gomes, L.; Dias Paiva, J.

    2007-01-01

    This work describes the direct and deep recharge in the Guarani Aquifer System, based on the evaluation of data acquired at the Ribeirao da Onca watershed, which is located at the outcrop zone of the GAS in Sao Paulo State, Brazil. During one year hydrological data (precipitation, temperature, discharge etc) have been monitored at the watershed. Using water level fluctuation measured in 23 monitoring wells, the direct recharge, the free aquifer storage and the base flow could be evaluated.The direct recharge of the system at the watershed has been estimated to 29% of the total precipitation in the period. Due to the drainage by the Ribeirao da Onca, the deep recharge, which effectively reaches the GAS, is reduced to 3,5% of the annual precipitation

  6. Geochemical and mineralogical characterization of the Eagle Ford Shale: Results from the USGS Gulf Coast #1 West Woodway core

    Science.gov (United States)

    Birdwell, Justin E.; Boehlke, Adam; Paxton, Stanley T.; Whidden, Katherine J.; Pearson, Ofori N.

    2017-01-01

    The Eagle Ford shale is a major continuous oil and gas resource play in southcentral Texas and a source for other oil accumulations in the East Texas Basin. As part of the U.S. Geological Survey’s (USGS) petroleum system assessment and research efforts, a coring program to obtain several immature, shallow cores from near the outcrop belt in central Texas has been undertaken. The first of these cores, USGS Gulf Coast #1 West Woodway, was collected near Waco, Texas, in September 2015 and has undergone extensive geochemical and mineralogical characterization using routine methods to ascertain variations in the lithologies and chemofacies present in the Eagle Ford at this locale. Approximately 270 ft of core was examined for this study, focusing on the Eagle Ford Group interval between the overlying Austin Chalk and underlying Buda Limestone (~20 ft of each). Based on previous work to identify the stratigraphy of the Eagle Ford Group in the Waco area and elsewhere (Liro et al., 1994; Robison, 1997; Ratcliffe et al., 2012; Boling and Dworkin, 2015; Fairbanks et al., 2016, and references therein), several lithological units were expected to be present, including the Pepper Shale (or Woodbine), the Lake Waco Formation (or Lower Eagle Ford, including the Bluebonnet, Cloice, and Bouldin or Flaggy Cloice members), and the South Bosque Member (Upper Eagle Ford). The results presented here indicate that there are three major chemofacies present in the cored interval, which are generally consistent with previous descriptions of the Eagle Ford Group in this area. The relatively high-resolution sampling (every two ft above the Buda, 432.8 ft depth, and below the Austin Chalk, 163.5 ft depth) provides great detail in terms of geochemical and mineralogical properties supplementing previous work on immature Eagle Ford Shale near the outcrop belt.

  7. 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.

  8. Managed aquifer recharge in the Marecchia alluvial fan (Rimini - Italy, start of the test and first results

    Directory of Open Access Journals (Sweden)

    Paolo Severi

    2014-09-01

    Full Text Available Among the actions designed to manage the water crisis that have taken place in the summers of recent years in the southeastern part of the Emilia-Romagna Region, it has recently launched a trial of managed aquifer recharge in the alluvial fan of the Marecchia river (Rimini, where annually are withdrawn about 28 million m3 of water, 19 of witch for drinking water use. This test consists in conveying into quarry lake, located in the recharge area of the alluvial fan, an additional volume of water through a channel. The increase in the volume of water in the lake, should result in a rapid increase in the availability of water in the aquifers. To verify the recharge efficacy a special monitoring network consisting of 20 measuring points, 5 of which are specially drilled, it has been implemented. In 9 of these points a data logger for the continuous measure of level, temperature and electric conductivity at 20°C, it has been installed. A data logger has also been positioned in the channel from which the water flows into the lake. For about a month groundwater level was monitored prior to the recharge experiment. On 25 February 2014 managed aquifer recharge began and the volume of water flowing through the canal to lake until April 30, 2014, was approximately 600,000 m3. In this period it was possible to observe that the intervention produces the expected effects, thus inducing an increase in the groundwater level which is maximum near the lake and decreases away from it. The rise in the water level of the lake has been rapid and substantial. Within the area of the lake have settled some protected bird species in need of a precise environmental balance for nesting; an excessive increase of the lake level could put at risk of flooding some nests present. The objective of the following phases of the study will be to calibrate an adequate water level of the lake, to the purposes of managed aquifer recharge and to maintain the existing ecosystem. At the

  9. Managed aquifer recharge of treated wastewater: water quality changes resulting from infiltration through the vadose zone.

    Science.gov (United States)

    Bekele, Elise; Toze, Simon; Patterson, Bradley; Higginson, Simon

    2011-11-01

    Secondary treated wastewater was infiltrated through a 9 m-thick calcareous vadose zone during a 39 month managed aquifer recharge (MAR) field trial to determine potential improvements in the recycled water quality. The water quality improvements of the recycled water were based on changes in the chemistry and microbiology of (i) the recycled water prior to infiltration relative to (ii) groundwater immediately down-gradient from the infiltration gallery. Changes in the average concentrations of several constituents in the recycled water were identified with reductions of 30% for phosphorous, 66% for fluoride, 62% for iron and 51% for total organic carbon when the secondary treated wastewater was infiltrated at an applied rate of 17.5 L per minute with a residence time of approximately four days in the vadose zone and less than two days in the aquifer. Reductions were also noted for oxazepam and temazepam among the pharmaceuticals tested and for a range of microbial pathogens, but reductions were harder to quantify as their magnitudes varied over time. Total nitrogen and carbamazepine persisted in groundwater down-gradient from the infiltration galleries. Infiltration does potentially offer a range of water quality improvements over direct injection to the water table without passage through the unsaturated zone; however, additional treatment options for the non-potable water may still need to be considered, depending on the receiving environment or the end use of the recovered water. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

  10. Mining inventory of Uruguay. Results of geochemical prospecting of Cerro Partido fotoplano

    International Nuclear Information System (INIS)

    Zeegers, H.; Artignan, D.; Vairon, P.

    1982-01-01

    This work is about the analitical results of the geological prospection carried out in Cerro Partido zone within the framework of Mining inventory of Uruguay. In this fotoplano (Esc. 1/50.000 and 1/400.000 there are metamorphic, mesozoic and carbonated formations

  11. Results of a hydrogeological and hydrogeochemical study of a semi-arid karst aquifer in Tezbent plateau, Tebessa region, northeast of Algeria

    Science.gov (United States)

    Belfar, Dalila; Fehdi, Chemseddine; Baali, Fethi; Salameh, Elias

    2017-06-01

    The Hammamet Plain, situated in the northwest of the Tezbent mountain range, northeast of Algeria, drains carbonate aquifers through some important karst springs. The physical and chemical characteristics of spring and well water samples were studied for 2 years to assess the origin of groundwater and determine the factors driving the geochemical composition. The ionic speciation and mineral dissolution/precipitation was calculated. Water wells, characterizing groundwater circulation at shallow depths, are moderate to high mineralized waters of Na-HCO3 type. In contrast to the shallow environment, the CO2-rich, deeper waters are of the Ca-HCO3-SO4 type and undergo significant changes in the baseline chemistry along flow lines with increasing residence time. The main factors controlling the groundwater composition and its seasonal variations are the geology, because of the presence of carbonate formations, the elevation and the rate of karst development. In both groups, the carbonate chemistry is diagnostic of the effect of karst development. The supersaturation with respect to calcite indicates CO2 degassing, occurring either inside the aquifer in open conduits, or at the outlet in reservoirs. The undersaturation with respect to calcite shows the existence of fast flow and short residence time conditions inside the aquifer. Interaction between groundwater and surrounding host rocks is believed to be the main process responsible for the observed chemical characteristics of groundwater in the study area.

  12. Geochemical Results of Lysimeter Sampling at the Manning Canyon Repository in the Mercur Mining District, Utah

    Science.gov (United States)

    Earle, John; Choate, LaDonna

    2010-01-01

    This report presents chemical characteristics of transient unsaturated-zone water collected by lysimeter from the Manning Canyon repository site in Utah. Data collected by U.S. Geological Survey and U.S. Department of the Interior, Bureau of Land Management scientists under an intragovernmental order comprise the existing body of hydrochemical information on unsaturated-zone conditions at the site and represent the first effort to characterize the chemistry of the soil pore water surrounding the repository. Analyzed samples showed elevated levels of arsenic, barium, chromium, and strontium, which are typical of acidic mine drainage. The range of major-ion concentrations generally showed expected soil values. Although subsequent sampling is necessary to determine long-term effects of the repository, current results provide initial data concerning reactive processes of precipitation on the mine tailings and waste rock stored at the site and provide information on the effectiveness of reclamation operations at the Manning Canyon repository.

  13. Preliminary geochemical results of corals from the Puerto Morelos Reef, Southeastern Mexico

    Science.gov (United States)

    Marquez, N.; Kasper, J.

    2012-04-01

    A microprobe (MB), major, trace and rare earth elements (REE) analyses were carried out in three coral species Acropora palmata, Acropora cervicornis and Gorgonia ventalina at Puerto Morelos, Reef, Southeastern Mexico. This was done to assess the degree in which the corals developed under the different chemical-physical natural and artificial conditions. The corals were cut at the top and middle and based upon the observations by using the MB analysis, results showed the highest concentrations of Ag, Cu, Cr, Ni, S, Sr, Zn y Zr in Gorgonia Ventalina suggesting an impact coming from the industrial discharges and/or rusting of boats in the area. The results of X-ray fluorescence analysis for major and trace elements showed that the Fe , Sr and Zr increase their content in the skeletons of Acropora palmata y Gorgonia ventalina also asociated with the presence of human activity since the area is composed mainly by carbonate source sediments. The rare earth elements (REE) analysis showed that the negative anomaly of Ce suggests a well oxygenated, highly oxidative modern shallow waters, and high nutrients related to suspended matter for Acropora Palmata, Acropora cervicornis y Gorgonia ventalina, The Positive Eu anomaly in the corals are due to the development of the reef linked to the concentration of waters enriched in La. The Nd/Yb ratio indicates a shallow water development for the corals. This is also supported by the Ce/Ce* vs. Pr/Pr* ratios that indicate shallow marine waters in the development of the three corals studied (Ce*= 0.5La+0.5Pr and Pr*= 0.5Ce+0.5Nd). Enrichment of heavy rare earth elements (Gd-Lu) in the corals may be associated with high pH values and CO, OH- ions in the sea water.

  14. Seasonal Hydrologic Controls on Uranium and Iron Biogeochemistry in a Riparian Aquifer

    Science.gov (United States)

    Wilkins, M.; Williams, K. H.; Danczak, R. E.; Yabusaki, S.; Fang, Y.; Hobson, C.

    2015-12-01

    The maintenance of geochemically reducing conditions is generally optimal for the formation and preservation of reduced metals and mineral phases that can limit contaminant fate and transport. At a riparian aquifer near Rifle, CO, we tracked over six months the biogeochemical response within the aquifer to an annual pulse of dissolved oxygen (DO) that results from snowmelt-driven changes in Colorado River stage. In reduced portions of the aquifer (naturally reduced zones; NRZs) the re-oxidation of abundant iron sulfide minerals was the dominant oxygen-consuming process, and resulted in little DO intrusion into the deeper aquifer. In less reduced areas, DO intruded through the entire vertical profile of the aquifer. Across both regions, these perturbations resulted in changes to the microbial community structure, and aqueous metal pools. Two potentially different mechanisms of uranium mobilization were observed; (1) re-oxidation of reduced U(IV) phases in response to DO intrusion, and (2) mobilization of U(VI) from the vadose zone during water table rise. This high-resolution, long-term monitoring of aquifer biogeochemistry at the Rifle site has revealed dynamic microbial and geochemical responses to predictable, annual hydrologic perturbations, and offers an opportunity to further refine modeling approaches for such regions.

  15. Hydrochemical and isotopic studies of ground water from Botucatu Aquifer - Partial results for North region of Parana Basin

    International Nuclear Information System (INIS)

    Silva, R.B.G. da; Kimmelmann, A.A.; Cunha Reboucas, A. da

    1985-01-01

    The first results of an investigation, to study the flow path, the processes controlling the chemical composition, the recharge, as well as, the origin, apparent ages and dynamic of the groundwater of the Botucatu Aquifer in the Brazilian part of the Parana Basin (818.000 Km 2 ), using hydrochemical and environmental isotope technics ( 2 H, 18 O, 13 C, 3 H, 14 C), are presented. Samples of 20 deep wells, located in the northern part of the Basin (states of Sao Paulo, Mato Grosso do Sul and Goias), were analysed. (Author) [pt

  16. On the Representation of Aquifer Compressibility in General Subsurface Flow Codes: How an Alternate Definition of Aquifer Compressibility Matches Results from the Groundwater Flow Equation

    Science.gov (United States)

    Birdsell, D.; Karra, S.; Rajaram, H.

    2017-12-01

    The governing equations for subsurface flow codes in deformable porous media are derived from the fluid mass balance equation. One class of these codes, which we call general subsurface flow (GSF) codes, does not explicitly track the motion of the solid porous media but does accept general constitutive relations for porosity, density, and fluid flux. Examples of GSF codes include PFLOTRAN, FEHM, STOMP, and TOUGH2. Meanwhile, analytical and numerical solutions based on the groundwater flow equation have assumed forms for porosity, density, and fluid flux. We review the derivation of the groundwater flow equation, which uses the form of Darcy's equation that accounts for the velocity of fluids with respect to solids and defines the soil matrix compressibility accordingly. We then show how GSF codes have a different governing equation if they use the form of Darcy's equation that is written only in terms of fluid velocity. The difference is seen in the porosity change, which is part of the specific storage term in the groundwater flow equation. We propose an alternative definition of soil matrix compressibility to correct for the untracked solid velocity. Simulation results show significantly less error for our new compressibility definition than the traditional compressibility when compared to analytical solutions from the groundwater literature. For example, the error in one calculation for a pumped sandstone aquifer goes from 940 to <70 Pa when the new compressibility is used. Code users and developers need to be aware of assumptions in the governing equations and constitutive relations in subsurface flow codes, and our newly-proposed compressibility function should be incorporated into GSF codes.

  17. Hydrological and geochemical consequences of river regulation - hyporheic perspective

    Science.gov (United States)

    Siergieiev, Dmytro; Lundberg, Angela; Widerlund, Anders

    2014-05-01

    River-aquifer interfaces, essential for ecosystem functioning in terms of nutrient exchange and biological habitat, appear greatly threatened worldwide. Although river regulation is a vast pressure on river-aquifer interaction, influencing entire watersheds, knowledge about hyporheic exchange in regulated rivers is rather limited. In this study, we combine two decades of research on hydrological and geochemical impacts of hydropower regulation on river water and hyporheic zone in two large boreal rivers, unregulated Kalix River and regulated Lule River. Altered river discharge, with reduced spring peaks, daily summer fluctuations and elevated winter base flow severely modified Lule River water geochemistry and thus the transport of solutes to the Bothnian Bay (Baltic Sea). Further, these river modifications changed the river-aquifer exchange on both daily and seasonal scale, which resulted in deteriorated hyporheic conditions with reduced riverbed hydraulic conductivity (formation of a clogging layer) reflected in a declined hyporheic flux. Altered hydrological regime of the hyporheic zone created quasi-stagnant conditions beneath the river-aquifer interface and promoted the formation of geochemically suboxic environment. Taken that hyporheic water is a mixture of river water and groundwater, mixing models for the regulated site demonstrate a considerable addition of Fe, Mn, Al, NH4 and removal of dissolved oxygen and nitrate, which suggests the hyporheic zone in the Lule River to be a source of solutes. This contradicts the observations from the hyporheic zone in the unregulated river, with opposite behaviour functioning as a barrier. These results suggest that the hyporheic zone function is dependent on the river discharge and the state of the river-aquifer connectivity. Improved knowledge about the latter on a watershed scale will substantially increase our understanding about the status and potential pressures of riverine ecosystems and assist management and

  18. Lead-210 and polonium-210 as marine geochemical tracers: review and discussion of results from the Laborador Sea

    International Nuclear Information System (INIS)

    Bacon, M.P.; Spencer, D.W.; Brewer, P.G.

    1980-01-01

    Because of their suitable half-lives and their accurately measurable rates of supply to the oceans by decay of parent radionuclides, 210 Pb and 210 Po have become increasingly important as tracers in the study of marine geochemical processes. Short removal times characterize the behavior of both nuclides in the biologically productive surface layers of the sea. Release from particles at depth is efficient for 210 Po but does not appear to be significant for 210 Pb. Scavenging processes in the deep sea are revealed by 210 Pb/ 226 Ra and 210 Po/ 210 Pb disequilibriums. Adsorption by particles sinking in the water column and reaction at the seafloor both appear to be important removal mechanisms. Results from four stations in the Labrador Sea are shown to be consistent with many earlier observations. Significant 210 Pb depletions, however, are found only at depths greater than 1500 m. Below 1500 m, 210 Pb/ 226 Ra ratios decrease steadily with depth to very low values in the Iceland-Scotland Overflow and Denmark Straits Overflow waters. The intense interaction of these water masses with the seafloor may account for this trend

  19. Method of forecasting pollutant transfer in an aquifer initial results obtained in a sandy medium (Barp site, Gironde)

    International Nuclear Information System (INIS)

    Madoz-Escande, C.; Peyrus, J.-C.

    1979-01-01

    Hydrogeological studies are undertaken in the context of the radiological safety of nuclear plants to forecast consequences of accidental releases of radioactive pollutants into an aquifer (transfer time, concentration at points of emergence). This quantitative forecast is obtained with the aid of a mathematical model with sequential emission. This requires a knowledge of the physical parameters of the aquifer and of the behavior of the pollutant in relation to the water-bearing medium. The physical parameters of a saturated porous medium are presented with the aid of radioactive tracer tests on a model and also in the field. The initial results obtained in a sandy medium are presented. In view of the difficulty of extrapolating to field conditions the conclusions of tests on models, it was necessary to set up a mobile laboratory with which in situ studies could be undertaken. The behavior of the pollutant in relation to the water-bearing medium is the subject of preliminary laboratory research on the laws of adsorption under different pH and temperature conditions. The numerical results obtained call for confirmation in the field. A description is given of a method which should enable the distribution coefficients to be evaluated in situ

  20. Uruguay mining inventory. Geochemical prospecting results of the Amarillo aerial map[Study of Uranium geochemical prospection in Uruguay]; Inventario minero del Uruguay. Resultados de la prospeccion geoquimica del fotoplano Amarillo

    Energy Technology Data Exchange (ETDEWEB)

    Zeegers, H; Spangenberg, J

    1981-07-01

    This report is about the results of the geochemical prospection carried out on the Amarillo aerial map, it placed in the area 24 of Uruguay (G11 section).This prospection was carried out by Geologic Institute team of Uruguay (IGU) with the technical assistance of BRGM. The Amarillo aerial map covers parts of Isla Cristalina. This is the window of the insular precrambrian shelf and it is surounded by geological formation as paleozoic and other more reecently formations too. The precambrian formation are represented by three big whole groups: metamorphic serial; groups of intrusing granites; and metamorphic rocks.

  1. Groundwater conservation and monitoring activities in the middle Brenta River plain (Veneto Region, Northern Italy: preliminary results about aquifer recharge

    Directory of Open Access Journals (Sweden)

    Andrea Sottani

    2014-09-01

    Full Text Available In the middle Brenta River plain there is a unconfined aquifer that represents an important groundwater resource in Veneto region. In this area the main groundwater recharge factor is related to the stream seepage: the water dispersion from the Brenta river is active with variable intensity from the foothill to the alignment Nove di Bassano - Cartigliano (Province of Vicenza. In order to mitigate the expected groundwater effects, due to future important waterworks withdrawals provided by the regional water resources management plans, an experimental project of Managed Aquifer Recharge has started, by means of the realization of some river transversal ramps. The construction of pilot works, partially completed, were preceded by a specific hydrogeological monitoring program, aimed to the evaluation of the effectiveness of the MAR actions in terms of comparison between pre-and post-operam conditions. Thanks to the development of a site-specific methodology, aimed to the quantification of the artificial infiltration rate, and after some years of monitoring controls of the hydrological and hydrogeological regimes, it is now possible to evaluate the extent and the rate of the recharge effects in groundwater due to ramps realization. The monitoring plan will be continued in the medium-long term. Some innovative approaches, based for example on the use of groundwater temperature measurements as recharge tracer, will help to validate the preliminary results.

  2. Geochemistry of the Arbuckle-Simpson Aquifer

    Science.gov (United States)

    Christenson, Scott; Hunt, Andrew G.; Parkhurst, David L.; Osborn, Noel I.

    2009-01-01

    The Arbuckle-Simpson aquifer in south-central Oklahoma provides water for public supply, farms, mining, wildlife conservation, recreation, and the scenic beauty of springs, streams, and waterfalls. A new understanding of the aquifer flow system was developed as part of the Arbuckle-Simpson Hydrology Study, done in 2003 through 2008 as a collaborative research project between the State of Oklahoma and the Federal government. The U.S. Geological Survey collected 36 water samples from 32 wells and springs in the Arbuckle-Simpson aquifer in 2004 through 2006 for geochemical analyses of major ions, trace elements, isotopes of oxygen and hydrogen, dissolved gases, and dating tracers. The geochemical analyses were used to characterize the water quality in the aquifer, to describe the origin and movement of ground water from recharge areas to discharge at wells and springs, and to determine the age of water in the aquifer.

  3. Geochemical study of the Sakalol-Harralol geothermal field (Republic of Djibouti): Evidences of a low enthalpy aquifer between Manda-Inakir and Asal rift settings

    Science.gov (United States)

    Awaleh, Mohamed Osman; Boschetti, Tiziano; Soubaneh, Youssouf Djibril; Baudron, Paul; Kawalieh, Ali Dirir; Dabar, Omar Assowe; Ahmed, Moussa Mahdi; Ahmed, Samaleh Idriss; Daoud, Mohamed Ahmed; Egueh, Nima Moussa; Mohamed, Jalludin

    2017-02-01

    Eighty-six sodium bicarbonate to sodium chloride hot springs and four water wells in the Tadjourah Region of Djibouti were investigated for major, minor (B, Br, F, Sr, Li) chemistry and isotope composition of water and dissolved components (87Sr/86Sr, 11B/10B, 13C/12C and 14C of DIC, 34S/32S and 18O/16O of sulfate). The deep saline Na-Cl reservoir at 143 °C shows affinity with the shallow geothermal water from the "active" Asal rift. Asal water is a diluted and recycled seawater component with the major cation composition obliterated by equilibration with Stratoid basalt. Locally, the deep reservoir is differentiated in term of recharge, and re-equilibration with rocks and mixing. In particular, two spring groups reveal contributions from evaporites typical of the "passive" graben setting of the Afar. A model on 34S/32S and 18O/16O demonstrates the isotope imprint of magmatic SO2 disproportionation on dissolved and solid sulfate, whose values probably persists in a sedimentary environment without trace of seawater. On the other hand a seawater signature, modified by mixing and secondary fractionation effects, is partially maintained according to the boron isotope composition (up to + 27.4‰). Temperature estimation in low-enthalpy geothermal reservoirs is notoriously difficult, especially where mixing with fluids of differing genesis and/or conduction cooling take place. From a geothermometric point of view, the multi-method approach followed in this study (up-to-date theoretical and thermodynamic equations, ad-hoc silica geothermometers inferred from local rocks, checking of the results on a 18Oαsulfate-water vs. temperature diagram) provides some insights and perspectives on how to tackle the problem. Table S2. Sampling locations, T, pH, EC, TDS and hydrochemical types of the sampled waters. Table S3. Chemical analyses of thermal and cold waters from Sakalaol-Haralol geothermal field. Table S4. Mineral saturation indices of SHGF hot springs waters calculated

  4. Kinetic rate of iron release during artificial CO{sub 2} injection in a shallow aquifer: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Rillard, J. [Earth Sciences Department UMR CNRS 5276 University of Lyon 1, Villeurbanne (France); INERIS French National Institut of Environmental and Industrial Risk Survey, Underground Risk Division,, Verneuil en Hallate (France); Gombert, P.; Toulhoat, P. [INERIS French National Institut of Environmental and Industrial Risk Survey, Underground Risk Division,, Verneuil en Hallate (France); Zuddas, P. [Earth Sciences Department UMR CNRS 5276 University of Lyon 1, Villeurbanne (France); University Pierre and Marie Curie Paris-Sorbonne, ISTEP, Paris (France)

    2013-07-01

    We performed an injection of CO{sub 2}-saturated water in a shallow aquifer following a 'push-pull' test protocol. A specific protocol was designed to measure in situ fluid pH and redox potential with careful sampling. We found increases of dissolved calcium, magnesium, alkalinity, iron and manganese, and other trace elements. Concentrations of Fe resulting from reactivity were estimated using measured concentrations of Fe corrected by a calculated fluid dynamics coefficient. Thermodynamic equilibrium calculations suggested that ferri-hydrite Fe(OH){sub 3} dissolution is the main source of iron release. The kinetic rate of Fe(OH){sub 3} dissolution estimated by a surface protonation model indicates that the reaction order is two. Since laboratory experimental results show a reaction order of zero, we propose that the mechanism of ferri-hydrite dissolution proceeds by a more complex mechanism under natural conditions. (authors)

  5. 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...

  6. Hydrogeology and results of aquifer tests in the vicinity of a hazardous-waste disposal site near Byron, Illinois

    Science.gov (United States)

    Kay, Robert T.; Olson, David N.; Ryan, Barbara J.

    1989-01-01

    The U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, conducted an investigation of a Superfund Site near Byron, Illinois. The purpose of the investigation was to determine the hydrogeologic properties of the Galena-Platteville and St. Peter aquifers, the primary water-supply aquifers for domestic supply in the area. The Galena and Platteville Groups and older St. Peter Sandstone are separated by the Harmony Hill Shale Member of the Glenwood Formation. The Harmony Hill Shale Member is a semiconfining unit. Groundwater flow in the study area is from the site northwestward to the Rock River. Movement of groundwater in the dolomites is mainly through joints, fractures, and solution openings. Analysis of the Galena-Platteville aquifer-test data indicates that the calculated aquifer transmissivity ranges from 490 to 670 sq ft/day, and the calculated specific yield ranges from 0.017 to 0.140. Aquifer test data also indicate that the Galena-Platteville aquifer is heterogeneous and anisotropic. Analysis of the St. Peter aquifer-test data indicates that the calculated transmissivity of the aquifer ranges from 1,200 to 1 ,305 sq ft/day, storativity ranges from 0.000528 to 0.00128, horizontal hydraulic conductivity ranges from 2.9 to 3.1 ft/day, and leakage through the Harmony Hill Shale Member ranges from .000123 to .000217 ft/day/ft. (USGS)

  7. Leachate Geochemical Results for Ash Samples from the June 2007 Angora Wildfire Near Lake Tahoe in Northern California

    Science.gov (United States)

    Hageman, Philip L.; Plumlee, Geoffrey S.; Martin, Deborah A.; Hoefen, Todd M.; Adams, Monique; Lamothe, Paul J.; Todorov, Todor I.; Anthony, Michael W.

    2008-01-01

    This report releases leachate geochemical data for ash samples produced by the Angora wildfire that burned from June 24 to July 2, 2007, near Lake Tahoe in northern California. The leaching studies are part of a larger interdisciplinary study whose goal is to identify geochemical characteristics and properties of the ash that may adversely affect human health, water quality, air quality, animal habitat, endangered species, debris flows, and flooding hazards. The leaching study helps characterize and understand the interactions that occur when the ash comes in contact with rain or snowmelt, and helps identify the constituents that may be mobilized as run-off from these materials. Similar leaching studies were conducted on ash and burned soils from the October 2007 southern California wildfires (Hageman and others, 2008; Plumlee and others, 2007).

  8. Evaluation of mercury and physicochemical parameters in different depths of aquifer water of Thar coalfield, Pakistan.

    Science.gov (United States)

    Ali, Jamshed; Kazi, Tasneem G; Tuzen, Mustafa; Ullah, Naeem

    2017-07-01

    In the current study, mercury (Hg) and physicochemical parameters have been evaluated in aquifer water at different depths of Thar coal field. The water samples were collected from first aquifer (AQ 1 ), second aquifer (AQ 2 ), and third aquifer (AQ 3 ) at three depths, 50-60, 100-120, and 200-250 m, respectively. The results of aquifer water of three depths were interpreted by using different multivariate statistical techniques. Validation of desired method was checked by spiking standard addition method in studied aquifer water samples. The content of Hg in aquifer water samples was measured by cold vapor atomic absorption spectrometer (CV-AAS). These determined values illustrate that the levels of Hg were higher than WHO recommended values for drinking water. All physicochemical parameters were higher than WHO permissible limits for drinking water except pH and SO 4 2- in aquifer water. The positive correlation of Hg with other metals in aquifer water samples of AQ 1 , AQ 2 , and AQ 3 of Thar coalfield except HCO 3 - was observed which might be caused by geochemical minerals. The interpretation of determined values by the cluster technique point out the variations within the water quality parameter as well as sampling location of studied field. The aquifer water AQ 2 was more contaminated with Hg as compared to AQ 1 and AQ 3 ; it may be due to leaching of Hg from coal zone. The concentration of Hg in aquifer water obtained from different depths was found in the following decreasing order: AQ 2  < AQ 1  < AQ 3 .

  9. Surface complexation modeling of groundwater arsenic mobility: Results of a forced gradient experiment in a Red River flood plain aquifer, Vietnam

    Science.gov (United States)

    Jessen, Søren; Postma, Dieke; Larsen, Flemming; Nhan, Pham Quy; Hoa, Le Quynh; Trang, Pham Thi Kim; Long, Tran Vu; Viet, Pham Hung; Jakobsen, Rasmus

    2012-12-01

    Three surface complexation models (SCMs) developed for, respectively, ferrihydrite, goethite and sorption data for a Pleistocene oxidized aquifer sediment from Bangladesh were used to explore the effect of multicomponent adsorption processes on As mobility in a reduced Holocene floodplain aquifer along the Red River, Vietnam. The SCMs for ferrihydrite and goethite yielded very different results. The ferrihydrite SCM favors As(III) over As(V) and has carbonate and silica species as the main competitors for surface sites. In contrast, the goethite SCM has a greater affinity for As(V) over As(III) while PO43- and Fe(II) form the predominant surface species. The SCM for Pleistocene aquifer sediment resembles most the goethite SCM but shows more Si sorption. Compiled As(III) adsorption data for Holocene sediment was also well described by the SCM determined for Pleistocene aquifer sediment, suggesting a comparable As(III) affinity of Holocene and Pleistocene aquifer sediments. A forced gradient field experiment was conducted in a bank aquifer adjacent to a tributary channel to the Red River, and the passage in the aquifer of mixed groundwater containing up to 74% channel water was observed. The concentrations of As (SCM correctly predicts desorption for As(III) but for Si and PO43- it predicts an increased adsorption instead of desorption. The goethite SCM correctly predicts desorption of both As(III) and PO43- but failed in the prediction of Si desorption. These results indicate that the prediction of As mobility, by using SCMs for synthetic Fe-oxides, will be strongly dependent on the model chosen. The SCM based on the Pleistocene aquifer sediment predicts the desorption of As(III), PO43- and Si quite superiorly, as compared to the SCMs for ferrihydrite and goethite, even though Si desorption is still somewhat under-predicted. The observation that a SCM calibrated on a different sediment can predict our field results so well suggests that sediment based SCMs may be a

  10. Arsenic release during managed aquifer recharge (MAR)

    Science.gov (United States)

    Pichler, T.; Lazareva, O.; Druschel, G.

    2013-12-01

    The mobilization and addition of geogenic trace metals to groundwater is typically caused by anthropogenic perturbations of the physicochemical conditions in the aquifer. This can add dangerously high levels of toxins to groundwater, thus compromising its use as a source of drinking water. In several regions world-wide, aquifer storage and recovery (ASR), a form of managed aquifer recharge (MAR), faces the problem of arsenic release due to the injection of oxygenated storage water. To better understand this process we coupled geochemical reactive transport modeling to bench-scale leaching experiments to investigate and verify the mobilization of geogenic arsenic (As) under a range of redox conditions from an arsenic-rich pyrite bearing limestone aquifer in Central Florida. Modeling and experimental observations showed similar results and confirmed the following: (1) native groundwater and aquifer matrix, including pyrite, were in chemical equilibrium, thus preventing the release of As due to pyrite dissolution under ambient conditions; (2) mixing of oxygen-rich surface water with oxygen-depleted native groundwater changed the redox conditions and promoted the dissolution of pyrite, and (3) the behavior of As along a flow path was controlled by a complex series of interconnected reactions. This included the oxidative dissolution of pyrite and simultaneous sorption of As onto neo-formed hydrous ferric oxides (HFO), followed by the reductive dissolution of HFO and secondary release of adsorbed As under reducing conditions. Arsenic contamination of drinking water in these systems is thus controlled by the re-equilibration of the system to more reducing conditions rather than a purely oxidative process.

  11. Temporal and spatial variations in groundwater quality resulting from policy-induced reductions in nitrate leaching to the Rabis Creek aquifer, Denmark

    Science.gov (United States)

    Jessen, Søren; Engesgaard, Peter; Thorling, Lærke; Müller, Sascha; Leskelä, Jari; Postma, Dieke

    2016-04-01

    -gradient along the transect. During the 25 year monitoring period the redoxcline has moved by one to a few decimeters, as controlled by the aquifer sediment's pyrite content. Further, the data indicate that no zero-valent sulfur is precipitated during pyrite oxidation in the aquifer, while most of the pyritic iron is precipitated. Nickel (Ni2+) is released at the redoxcline resulting in concentrations more than twice the 20 μg/L Danish drinking water limit. The data clearly indicate that this Ni2+ contamination can be ascribed to the agricultural nitrate loading and would not occur under natural conditions. A 2D reactive transport model was constructed (PHAST 3) to simulate the temporal and spatial development in nitrate and sulfate concentrations in the aquifer while taking into account effects of dispersion. The model predictions indicate that sulfate concentrations, despite dispersive mixing, is still increasing along down-gradient stretches of the aquifer, where flow paths surface from the deeper up-gradient part of the aquifer, to eventually discharge into the Rabis Creek.

  12. Geochemical evolution of groundwater in the Mud Lake area, eastern Idaho, USA

    Science.gov (United States)

    Rattray, Gordon W.

    2015-01-01

    Groundwater with elevated dissolved-solids concentrations—containing large concentrations of chloride, sodium, sulfate, and calcium—is present in the Mud Lake area of Eastern Idaho. The source of these solutes is unknown; however, an understanding of the geochemical sources and processes controlling their presence in groundwater in the Mud Lake area is needed to better understand the geochemical sources and processes controlling the water quality of groundwater at the Idaho National Laboratory. The geochemical sources and processes controlling the water quality of groundwater in the Mud Lake area were determined by investigating the geology, hydrology, land use, and groundwater geochemistry in the Mud Lake area, proposing sources for solutes, and testing the proposed sources through geochemical modeling with PHREEQC. Modeling indicated that sources of water to the eastern Snake River Plain aquifer were groundwater from the Beaverhead Mountains and the Camas Creek drainage basin; surface water from Medicine Lodge and Camas Creeks, Mud Lake, and irrigation water; and upward flow of geothermal water from beneath the aquifer. Mixing of groundwater with surface water or other groundwater occurred throughout the aquifer. Carbonate reactions, silicate weathering, and dissolution of evaporite minerals and fertilizer explain most of the changes in chemistry in the aquifer. Redox reactions, cation exchange, and evaporation were locally important. The source of large concentrations of chloride, sodium, sulfate, and calcium was evaporite deposits in the unsaturated zone associated with Pleistocene Lake Terreton. Large amounts of chloride, sodium, sulfate, and calcium are added to groundwater from irrigation water infiltrating through lake bed sediments containing evaporite deposits and the resultant dissolution of gypsum, halite, sylvite, and bischofite.

  13. Methods for geochemical analysis

    Science.gov (United States)

    Baedecker, Philip A.

    1987-01-01

    The laboratories for analytical chemistry within the Geologic Division of the U.S. Geological Survey are administered by the Office of Mineral Resources. The laboratory analysts provide analytical support to those programs of the Geologic Division that require chemical information and conduct basic research in analytical and geochemical areas vital to the furtherance of Division program goals. Laboratories for research and geochemical analysis are maintained at the three major centers in Reston, Virginia, Denver, Colorado, and Menlo Park, California. The Division has an expertise in a broad spectrum of analytical techniques, and the analytical research is designed to advance the state of the art of existing techniques and to develop new methods of analysis in response to special problems in geochemical analysis. The geochemical research and analytical results are applied to the solution of fundamental geochemical problems relating to the origin of mineral deposits and fossil fuels, as well as to studies relating to the distribution of elements in varied geologic systems, the mechanisms by which they are transported, and their impact on the environment.

  14. Bacterial community and groundwater quality changes in an anaerobic aquifer during groundwater recharge with aerobic recycled water.

    Science.gov (United States)

    Ginige, Maneesha P; Kaksonen, Anna H; Morris, Christina; Shackelton, Mark; Patterson, Bradley M

    2013-09-01

    Managed aquifer recharge offers the opportunity to manage groundwater resources by storing water in aquifers when in surplus and thus increase the amount of groundwater available for abstraction during high demand. The Water Corporation of Western Australia (WA) is undertaking a Groundwater Replenishment Trial to evaluate the effects of recharging aerobic recycled water (secondary treated wastewater subjected to ultrafiltration, reverse osmosis, and ultraviolet disinfection) into the anaerobic Leederville aquifer in Perth, WA. Using culture-independent methods, this study showed the presence of Actinobacteria, Alphaproteobacteria, Bacilli, Betaproteobacteria, Cytophaga, Flavobacteria, Gammaproteobacteria, and Sphingobacteria, and a decrease in microbial diversity with an increase in depth of aquifer. Assessment of physico-chemical and microbiological properties of groundwater before and after recharge revealed that recharging the aquifer with aerobic recycled water resulted in elevated redox potentials in the aquifer and increased bacterial numbers, but reduced microbial diversity. The increase in bacterial numbers and reduced microbial diversity in groundwater could be a reflection of an increased denitrifier and sulfur-oxidizing populations in the aquifer, as a result of the increased availability of nitrate, oxygen, and residual organic matter. This is consistent with the geochemical data that showed pyrite oxidation and denitrification within the aquifer after recycled water recharge commenced. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  15. Spatial and temporal changes in sulphate-reducing groundwater bacterial community structure in response to Managed Aquifer Recharge.

    Science.gov (United States)

    Reed, D A; Toze, S; Chang, B

    2008-01-01

    The population dynamics of bacterial able to be cultured under sulphate reducing condition was studied in conjunction with changes in aquifer geochemistry using multivariate statistics for two contrasting Managed Aquifer Recharge (MAR) techniques at two different geographical locations (Perth, Western Australia and Adelaide, South Australia). Principal component analysis (PCA) was used to investigate spatial and temporal changes in the overall chemical signature of the aquifers using an array of chemical analytes which demonstrated a migrating geochemical plume. Denaturing Gradient Gel Electrophoresis (DGGE) using DNA from sulphate-reducing bacteria cultures was used to detect spatial and temporal changes in population dynamics. Bacterial and geochemical evidence suggested that groundwater at greatest distance from the nutrient source was least affected by treated effluent recharge. The results suggested that bacterial populations that were able to be cultured in sulphate reducing media responded to the migrating chemical gradient and to the changes in aquifer geochemistry. Most noticeably, sulphate-reducing bacterial populations associated with the infiltration galleries were stable in community structure over time. Additionally, the biodiversity of these culturable bacteria was restored when aquifer geochemistry returned to ambient conditions during the recovery phase at the Adelaide Aquifer Storage and Recovery site. Copyright CSIRO 2008.

  16. Carbonate aquifers

    Science.gov (United States)

    Cunningham, Kevin J.; Sukop, Michael; Curran, H. Allen

    2012-01-01

    Only limited hydrogeological research has been conducted using ichnology in carbonate aquifer characterization. Regardless, important applications of ichnology to carbonate aquifer characterization include its use to distinguish and delineate depositional cycles, correlate mappable biogenically altered surfaces, identify zones of preferential groundwater flow and paleogroundwater flow, and better understand the origin of ichnofabric-related karst features. Three case studies, which include Pleistocene carbonate rocks of the Biscayne aquifer in southern Florida and Cretaceous carbonate strata of the Edwards–Trinity aquifer system in central Texas, demonstrate that (1) there can be a strong relation between ichnofabrics and groundwater flow in carbonate aquifers and (2) ichnology can offer a useful methodology for carbonate aquifer characterization. In these examples, zones of extremely permeable, ichnofabric-related macroporosity are mappable stratiform geobodies and as such can be represented in groundwater flow and transport simulations.

  17. Aquifer test results, 200-UP-1 operable unit IRM plume: Wells 299-W19-39 and 299-W19-36

    International Nuclear Information System (INIS)

    Swanson, L.C.

    1996-03-01

    An aquifer test was conducted at 200-UP-1 extraction well 299-W19-39 from September 6 to 8, 1995. The testing process consisted of pumping groundwater from the extraction well, using the surface treatment system to purify the water, and reinjecting the water through well 299-W19-36. Multiple observation wells were used to measure the response of the aquifer during the pumping and recovery phases of the test. Tables 1 and 2 list each well monitored and give well location and configuration information. Pretest monitoring initiated on August 31, 1995 was used to establish water-level trends and barometric pressure responses in the extraction, injection, and observation wells. Water-level monitoring continued for about 2 weeks after pumping ceased. The objectives of the aquifer test were to determine large-scale aquifer properties to confirm hydraulic conductivity input values used in previous numerical modeling work, to evaluate the long-term performance of the extraction and monitoring wells, and to estimate the radial extent of the drawdown cone (i.e., the expected capture area and depth). All of the test objectives were met. A discussion of the test results follows

  18. Simulation of groundwater flow in the Edwards-Trinity and related aquifers in the Pecos County region, Texas

    Science.gov (United States)

    Clark, Brian R.; Bumgarner, Johnathan R.; Houston, Natalie A.; Foster, Adam L.

    2014-01-01

    The Edwards-Trinity aquifer is a vital groundwater resource for agricultural, industrial, and public supply uses in the Pecos County region of western Texas. The U.S. Geological Survey completed a comprehensive, integrated analysis of available hydrogeologic data to develop a numerical groundwater-flow model of the Edwards-Trinity and related aquifers in the study area in parts of Brewster, Jeff Davis, Pecos, and Reeves Counties. The active model area covers about 3,400 square miles of the Pecos County region of Texas west of the Pecos River, and its boundaries were defined to include the saturated areas of the Edwards-Trinity aquifer. The model is a five-layer representation of the Pecos Valley, Edwards-Trinity, Dockum, and Rustler aquifers. The Pecos Valley aquifer is referred to as the alluvial layer, and the Edwards-Trinity aquifer is divided into layers representing the Edwards part of the Edwards-Trinity aquifer and the Trinity part of the Edwards-Trinity aquifer, respectively. The calibration period of the simulation extends from 1940 to 2010. Simulated hydraulic heads generally were in good agreement with observed values; 1,684 out of 2,860 (59 percent) of the simulated values were within 25 feet of the observed value. The average root mean square error value of hydraulic head for the Edwards-Trinity aquifer was 34.2 feet, which was approximately 4 percent of the average total observed change in groundwater-level altitude (groundwater level). Simulated spring flow representing Comanche Springs exhibits a pattern similar to observed spring flow. Independent geochemical modeling corroborates results of simulated groundwater flow that indicates groundwater in the Edwards-Trinity aquifer in the Leon-Belding and Fort Stockton areas is a mixture of recharge from the Barilla and Davis Mountains and groundwater that has upwelled from the Rustler aquifer.

  19. An overview of nitrate sources and operating processes in arid and semiarid aquifer systems.

    Science.gov (United States)

    Gutiérrez, Mélida; Biagioni, Richard N; Alarcón-Herrera, Maria Teresa; Rivas-Lucero, Bertha A

    2018-05-15

    Nitrate concentration in most aquifers in arid and semi-arid areas has increased in the past several decades as a result of human activities. Under the predominantly oxic conditions of these aquifers, denitrification is inhibited, allowing nitrate, a soluble and stable form of nitrogen (N), to accumulate. Because of its close association with municipal and agricultural wastes, nitrate is commonly used as an indicator of anthropogenic contamination. Aquifers affected by agricultural waste may contain salts from irrigation returns and herbicides in addition to nitrates. Preventing leakage from soil to deeper parts of the aquifer is thus a priority in the sustainable management of aquifers in arid and semiarid areas. Studies report a wide range of nitrate concentrations distributed non-uniformly within the aquifer, with roughly 40% and 20% of sampled wells exceeding 50mg/L nitrate in shallow and deep parts of the aquifer respectively. In aquifers at risk of becoming contaminated, nitrate isotopes (δ 15 N, δ 18 O, Δ 17 O) can be used to identify the source of nitrogen as mineral or organic fertilizer, sewage, or atmospheric deposition. A variety of mathematical models (crop, hydrological, geochemical, or a combination of them) have been successful in identifying best practices that minimize N leakage without negatively affecting crop yield. In addition, field research in crop management, e.g., conservation agriculture, has yielded promising results in determining the adequate dosage and time of application of fertilizers to reduce N losses. Examples of key dryland aquifers impacted by nitrate are discussed, and some of the most pressing challenges to achieve sustainability are presented. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Isotopes to Study the coastal aquifer plain, Cap Bon, Tunisia

    International Nuclear Information System (INIS)

    Ben Hamouda, M. F.; Zouari, Kamel; Tarhouni, J.; Gaye, C.B.; Oueslati, M.N.

    2005-01-01

    The study area is located in the northeastern part of Tunisia about 60 km south of the Tunis city. It is bounded by the Gulf of Haematite in the East, Djebel Sidi Aberahmane in the West, The town of Nabeul in the south and the area of the town Kelibia in the north. The landscape is a coastal plain slightly sloping (3%) towards the sea. The groundwater of the Oriental coast aquifer system occurs mainly at two levels, a shallow aquifer up to depths of about 50 m whose reservoir is consisted by sediments of the Plio quaternary and a deep aquifer between about 150 and 400 m located in the sand stone formations of Miocene of the anticline of Djebel Sidi Abderrahmene. The climate of the region is semi-arid to sub-humid and of Mediterranean type. There are no perennial rivers in this region; but intense storms occasionally cause surface runoff, which is discharged by the oueds. The study is related to a technical cooperation project with the International Atomic Energy Agency, Vienna, Austria, aimed at the use of isotope techniques to study the seawater intrusion into the coastal aquifers of Cap Bon in Tunisia. In this regard, a better understanding of the recharge and flow regime as well as the origin or salinity of the groundwater was required. To reach this goal, isotope and geochemical investigations were carried out. Water samples were taken from wells, boreholes from deep and shallow aquifer of the Oriental coastal aquifer located between Beni Khiar in the south and Kelibia in the north. The samples were analysed for their chemical and isotopic compositions (18O, 2H, 3H, 13C, 14C, 34S). In the following, the results of these analyses are presented and discussed in terms of the recharge and flow regime of the groundwater and the origin and evolution of its salinity. The results of geochemical and isotopic studies have shown that the groundwater is very eterogeneous and suggest the aquifer is replenished by recent water coming from direct infiltration from rain. At

  1. Laboratory investigations into the reactive transport module of carbon dioxide sequestration and geochemical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Heidaryan, E. [Islamic Azad Univ., Tehran (Iran, Islamic Republic of). Masjidosolayman Branch; Enayati, M.; Mokhtari, B. [Iranian Offshore Oil Co., Tehran (Iran, Islamic Republic of)

    2008-07-01

    Over long time periods, geological sequestration in some systems shows mineralization effects or mineral sequestration of carbon dioxide, converting the carbon dioxide to a less mobile form. However, a detailed investigation of these geological systems is needed before disposing of carbon dioxide into these formations. Depleted oil and gas reservoirs and underground aquifers are proposed candidates for carbon dioxide injection. This paper presented an experimental investigation into the reactive transport module for handling aquifer sequestration of carbon dioxide and modeling of simultaneous geochemical reactions. Two cases of laboratory carbon dioxide sequestration experiments, conducted for different rock systems were modeled using the fully coupled geochemical compositional simulator. The relevant permeability relationships were compared to determine the best fit with the experimental results. The paper discussed the theory of modeling; geochemical reactions and mineral trapping of carbon dioxide; and application simulator for modeling including the remodeling of flow experiments. It was concluded that simulated changes in porosity and permeability could mimic experimental results to some extent. The study satisfactorily simulated the results of experimental observations and permeability results could be improved if the Kozeny-Carman equation was replaced by the Civan power law. 6 refs., 2 tabs., 21 figs.

  2. Isotope characterization of shallow aquifers in the Horombe region, South of Madagascar

    International Nuclear Information System (INIS)

    Fareze, L.P.; Rajaobelison, J.; Ramaroson, V.; Raoelina Andriambololona; Andriamiarintsoa, G.; Razafitsalama, P.R.; Rahobisoa, J.J.; Randrianarison, H.; Ranaivoarisoa, A.; Marah, H.

    2011-01-01

    The present study deals with the problem of evaluation of the recharge mechanism and the characterization of the groundwater flow system in the basement shallow aquifer, which is one of the groundwater resource in the semi-arid South region of Madagascar. Stable isotopes (deuterium and oxygen-18) and tritium are used to achieve with accuracy the hydrogeological and geochemical dynamics study. Chemical analysis is used to provide complementary information to the investigation. A space distribution of tritium concentration and isotopic composition in groundwater shows evidence of two opposite categories of aquifers, which is confirmed by the chemical analysis results and by the geological features of the study site. Some groundwater flow path directions have been identified in the study area thanks to the tritium concentration space distribution and the geological formation. Besides, the groundwater recharge of the shallow aquifers in the South of Madagascar has been characterized by the exponential mixing model.

  3. Groundwater geochemistry of a Mio-Pliocene aquifer in the northeastern Algerian Sahara (Djamaa region)

    Science.gov (United States)

    Houari, Idir Menad; Nezli, Imed Eddine; Belksier, Mohamed Salah

    2018-05-01

    The groundwater resources in the Northern Sahara are represented by two superimposed major aquifer systems: the Intercalary Continental (CI) and the Terminal Complex (CT). The waters of these aquifers pose serious physical and chemical quality problems; they are highly mineralized and very hard. The present work aims to describe the water's geochemical evolution of sand groundwater (Mio-Pliocene) of the Terminal Complex in the area of Djamaa, by the research of the relationship between water's chemical composition and lithology of aquifer formations through. The results obtained show that the water's chemistry is essentially governed by the dissolution of evaporate formations, which gives to, waters an excessive mineralization expressed by high concentrations of sulfates, chlorides and sodium.

  4. 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...

  5. Statistical interpretation of geochemical data

    International Nuclear Information System (INIS)

    Carambula, M.

    1990-01-01

    Statistical results have been obtained from a geochemical research from the following four aerial photographies Zapican, Carape, Las Canias, Alferez. They have been studied 3020 samples in total, to 22 chemical elements using plasma emission spectrometry methods.

  6. Impact of Varying Wave Conditions on the Mobility of Arsenic in a Nearshore Aquifer on the Great Lakes

    Science.gov (United States)

    Rakhimbekova, S.; O'Carroll, D. M.; Robinson, C. E.

    2017-12-01

    Groundwater-coastal water interactions play an important role in controlling the behavior of inorganic chemicals in nearshore aquifers and the subsequent flux of these chemicals to receiving coastal waters. Previous studies have shown that dynamic groundwater flows and water exchange across the sediment-water interface can set up strong geochemical gradients and an important reaction zone in a nearshore aquifer that affect the fate of reactive chemicals. There is limited understanding of the impact of transient coastal forcing such as wave conditions on groundwater dynamics and geochemistry in a nearshore aquifer. The goal of this study was to assess the impact of intensified wave conditions on the behavior of arsenic in a nearshore aquifer and to determine the hydrological and geochemical factors controlling its fate and ultimate delivery to receiving coastal waters. Field investigations were conducted over the period of intensified wave conditions on a freshwater beach on Lake Erie, Canada. High spatial resolution aqueous and sediment sampling was conducted to characterize the subsurface distribution of inorganic species in the nearshore aquifer. Numerical groundwater flow and transport simulations were conducted to evaluate wave-induced perturbations in the flow dynamics including characterizing changes in the groundwater flow recirculations in the nearshore aquifer. The combination of field data and numerical simulations reveal that varying wave conditions alter groundwater flows and set up geochemical transition zones within the aquifer resulting in the release and sequestration of arsenic. Interactions between oxic surface water, mildly reducing shallow groundwater, and reducing sulfur- and iron-rich deep groundwater promote dynamic iron, sulfur and manganese cycling which control the mobility of arsenic in the aquifer. The findings of this study have potential implications for the fate and transport of other reactive chemicals (e.g. phosphorus, mercury) in

  7. Characterisation of organic matter associated with groundwater arsenic in reducing aquifers of southwestern Taiwan.

    Science.gov (United States)

    Al Lawati, Wafa M; Jean, Jiin-Shuh; Kulp, Thomas R; Lee, Ming-Kuo; Polya, David A; Liu, Chia-Chuan; van Dongen, Bart E

    2013-11-15

    Arsenic (As) in groundwaters extensively used by people across the world constitutes a serious public health threat. The importance of organic matter (OM) as an electron donor in microbially-mediated reduction of As(V) or Fe(III)-bearing As-host minerals leading to mobilisation of solid-phase arsenic is widely recognised. Notwithstanding this, there are few studies characterising OM in such aquifers and, in particular, there is a dearth of data from the classic arsenic bearing aquifers in southwestern Taiwan. Organic geochemical analyses of sediments from a known groundwater arsenic hot-spot in southwestern Taiwan revealed contributions of thermally mature and plant derived origin, consistent with OM sources in all other Asian groundwater aquifer sediments analysed to date, indicating comparable sources and routes of OM transfer. The combined results of amended As(V) reduction assays with the organic geochemical analysis revealed that the microbiological process of dissimilatory As(V) reduction is active in this aquifer, but it is not controlled by a specific source of analysed OM. These indicate that (i) part of the OM that was considered to be less bio-available could still be used as an electron donor or (ii) other electron donors, not analysed in present study, could be controlling the rate of As release. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Attenuation of landfill leachate by UK Triassic sandstone aquifer materials. 1. Fate of inorganic pollutants in laboratory columns

    Science.gov (United States)

    Thornton, Steven F.; Tellam, John H.; Lerner, David N.

    2000-05-01

    The attenuation of inorganic contaminants in acetogenic and methanogenic landfill leachate by calcareous and carbonate-deficient, oxide-rich Triassic sandstone aquifer materials from the English Midlands was examined in laboratory columns. Aqueous equilibrium speciation modelling, simple transport modelling and chemical mass balance approaches are used to evaluate the key processes and aquifer geochemical properties controlling contaminant fate. The results indicate that leachate-rock interactions are dominated by ion-exchange processes, acid-base and redox reactions and sorption/precipitation of metal species. Leachate NH 4 is attenuated by cation exchange with the aquifer sediments; however, NH 4 migration could be described with a simple model using retardation factors. Organic acids in the acetogenic leachate buffered the system pH at low levels during flushing of the calcareous aquifer material. In contrast, equilibrium with Al oxyhydroxide phases initially buffered pH (˜4.5) during flushing of the carbonate-deficient sandstone with methanogenic leachate. This led to the mobilisation of sorbed and oxide-bound heavy metals from the aquifer sediment which migrated as a concentrated pulse at the leachate front. Abiotic reductive dissolution of Mn oxyhydroxides on each aquifer material by leachate Fe 2+ maintains high concentrations of dissolved Mn and buffers the leachate inorganic redox system. This feature is analogous to the Mn-reducing zones found in leachate plumes and in the experiments provides a sink for the leachate Fe load and other heavy metals. The availability of reactive solid phase Mn oxyhydroxides limits the duration of redox buffering and Fe attenuation by these aquifer sediments. Aquifer pH and redox buffering capacity exert a fundamental influence on leachate inorganic contaminant fate in these systems. The implications for the assessment of aquifer vulnerability at landfills are discussed and simple measurements of aquifer properties which

  9. Land-use change and managed aquifer recharge effects on the hydrogeochemistry of two contrasting atoll island aquifers, Roi-Namur Island, Republic of the Marshall Islands

    International Nuclear Information System (INIS)

    Hejazian, Mehrdad; Gurdak, Jason J.; Swarzenski, Peter; Odigie, Kingsley O.; Storlazzi, Curt D.

    2017-01-01

    Freshwater resources on low-lying atoll islands are highly vulnerable to climate change and sea-level rise. In addition to rainwater catchment, groundwater in the freshwater lens is a critically important water resource on many atoll islands, especially during drought. Although many atolls have high annual rainfall rates, dense natural vegetation and high evapotranspiration rates can limit recharge to the freshwater lens. Here we evaluate the effects of land-use/land-cover change and managed aquifer recharge on the hydrogeochemistry and supply of groundwater on Roi-Namur Island, Republic of the Marshall Islands. Roi-Namur is an artificially conjoined island that has similar hydrogeology on the Roi and Namur lobes, but has contrasting land-use/land-cover and managed aquifer recharge only on Roi. Vegetation removal and managed aquifer recharge operations have resulted in an estimated 8.6 × 10"5 m"3 of potable groundwater in the freshwater lens on Roi, compared to only 1.6 × 10"4 m"3 on Namur. We use groundwater samples from a suite of 33 vertically nested monitoring wells, statistical testing, and geochemical modeling using PHREEQC to show that the differences in land-use/land-cover and managed aquifer recharge on Roi and Namur have a statistically significant effect on several groundwater-quality parameters and the controlling geochemical processes. Results also indicate a six-fold reduction in the dissolution of carbonate rock in the freshwater lens and overlying vadose zone of Roi compared to Namur. Mixing of seawater and the freshwater lens is a more dominant hydrogeochemical process on Roi because of the greater recharge and flushing of the aquifer with freshwater as compared to Namur. In contrast, equilibrium processes and dissolution-precipitation non-equilibrium reactions are more dominant on Namur because of the longer residence times relative to the rate of geochemical reactions. Findings from Roi-Namur Island support selective land

  10. Impact assessment of artificial recharge and geo-chemical characterization of the waters of the slick Tebolba (Eastern Tunisia)

    International Nuclear Information System (INIS)

    Ferchichi, Hajer

    2007-01-01

    This study concerned the impact assessment of artificial recharge of a coastal aquifer (Tebolba) from the waters of the dam Nebhana and chemical characterization of its waters. The analysis maps piezometric drawn and salinity at various dates since 1940, the establishment of chronic recharge from the years 1992 to 2006, as well as geochemical study of groundwater in the slick Tebolba have enabled us to reach the many results. This study using a multidisciplinary approach (hydrodynamics and geochemical) seeks an assessment of impacts of recharging the water table in Tebolba from the waters of the dam Nebhana through the history of the qualitative and quantitative water the water and a hydro-geochemical study the current state of the waters of the water. (Author). 45 refs

  11. A Geochemical Reaction Model for Titration of Contaminated Soil and Groundwater at the Oak Ridge Reservation

    Science.gov (United States)

    Zhang, F.; Parker, J. C.; Gu, B.; Luo, W.; Brooks, S. C.; Spalding, B. P.; Jardine, P. M.; Watson, D. B.

    2007-12-01

    This study investigates geochemical reactions during titration of contaminated soil and groundwater at the Oak Ridge Reservation in eastern Tennessee. The soils and groundwater exhibits low pH and high concentrations of aluminum, calcium, magnesium, manganese, various trace metals such as nickel and cobalt, and radionuclides such as uranium and technetium. The mobility of many of the contaminant species diminishes with increasing pH. However, base additions to increase pH are strongly buffered by various precipitation/dissolution and adsorption/desorption reactions. The ability to predict acid-base behavior and associated geochemical effects is thus critical to evaluate remediation performance of pH manipulation strategies. This study was undertaken to develop a practical but generally applicable geochemical model to predict aqueous and solid-phase speciation during soil and groundwater titration. To model titration in the presence of aquifer solids, an approach proposed by Spalding and Spalding (2001) was utilized, which treats aquifer solids as a polyprotic acid. Previous studies have shown that Fe and Al-oxyhydroxides strongly sorb dissolved Ni, U and Tc species. In this study, since the total Fe concentration is much smaller than that of Al, only ion exchange reactions associated with Al hydroxides are considered. An equilibrium reaction model that includes aqueous complexation, precipitation, ion exchange, and soil buffering reactions was developed and implemented in the code HydroGeoChem 5.0 (HGC5). Comparison of model results with experimental titration curves for contaminated groundwater alone and for soil- water systems indicated close agreement. This study is expected to facilitate field-scale modeling of geochemical processes under conditions with highly variable pH to develop practical methods to control contaminant mobility at geochemically complex sites.

  12. Characterizing a complex aquifer system using geophysics, hydrodynamics and geochemistry: A new distribution of Miocene aquifers in the Zéramdine and Mahdia-Jébéniana blocks (east-central Tunisia)

    Science.gov (United States)

    Lachaal, Fethi; Bédir, Mourad; Tarhouni, Jamila; Gacha, Ayadi Ben; Leduc, Christian

    2011-06-01

    The Zéramdine and Mahdia-Jébéniana blocks are located in the Sahel region in east-central Tunisia. Active tectonics have divided the region into numerous sub-units, as result of multiple phases of distension and compression. The Miocene fluvio-deltaic sediment sandy layers have aquiferous capacities but their hydraulic properties are still unknown, due to the lack of investigation wells. This study proposes a new description of the regional hydrogeology of Miocene deposits. Seismic-reflection and wireline logging of petroleum and water wells were used to understand the structure and the geometry of the Miocene reservoirs. The groundwater flow and its relationship to the sedimentary and tectonic context were then identified by studying piezometry and hydrochemistry. Two Miocene deep aquifer systems were identified: (1) Zéramdine-Béni Hassen to the north and (2) Jébéniana-Ksour Essef to the south. These aquifers are separated by the Mahdia graben. Other major tectonic structures, such as the Zéramdine fault corridor, the Moknine graben, and the El-Jem half-graben represent lateral boundaries for these aquifers. Other deeper sandy and clayey-sandy reservoirs were also identified in the area. Their repartition, thickness and depth vary from one block to other. Hydrodynamics of the deep aquifers seems to be controlled by geological structures. Two independent compartments were identified: in the northern block groundwater flows from West to East and from Northwest to Southeast, while in the southern block it flows from Northwest to Southeast. Geochemical facies are of two types: Na-Ca-Cl-SO 4 for the Zéramdine-Béni Hassen deep aquifer and Na-Cl for the Jébéniana-Ksour Essef deep aquifer. The hydrodynamic and geochemical results confirm the sharing of the Miocene sediments into two aquifers.

  13. Characterisation of organic matter associated with groundwater arsenic in reducing aquifers of southwestern Taiwan

    International Nuclear Information System (INIS)

    Al Lawati, Wafa M.; Jean, Jiin-Shuh; Kulp, Thomas R.; Lee, Ming-Kuo; Polya, David A.; Liu, Chia-Chuan; Dongen, Bart E. van

    2013-01-01

    Highlights: ► First lipid analysis of Taiwanese aquifer sediments from groundwater As-prone region. ► Both plant-derived terrestrial and mature hydrocarbon lipid sources identified. ► Organic matter sources similar to those of other high As groundwater aquifers. ► Groundwater arsenic at depth controlled by biotic As mobilisation processes. ► Biotic As mobilisation not controlled by a specific source of analysed organic matter. -- Abstract: Arsenic (As) in groundwaters extensively used by people across the world constitutes a serious public health threat. The importance of organic matter (OM) as an electron donor in microbially-mediated reduction of As(V) or Fe(III)-bearing As-host minerals leading to mobilisation of solid-phase arsenic is widely recognised. Notwithstanding this, there are few studies characterising OM in such aquifers and, in particular, there is a dearth of data from the classic arsenic bearing aquifers in southwestern Taiwan. Organic geochemical analyses of sediments from a known groundwater arsenic hot-spot in southwestern Taiwan revealed contributions of thermally mature and plant derived origin, consistent with OM sources in all other Asian groundwater aquifer sediments analysed to date, indicating comparable sources and routes of OM transfer. The combined results of amended As(V) reduction assays with the organic geochemical analysis revealed that the microbiological process of dissimilatory As(V) reduction is active in this aquifer, but it is not controlled by a specific source of analysed OM. These indicate that (i) part of the OM that was considered to be less bio-available could still be used as an electron donor or (ii) other electron donors, not analysed in present study, could be controlling the rate of As release

  14. Characterisation of organic matter associated with groundwater arsenic in reducing aquifers of southwestern Taiwan

    Energy Technology Data Exchange (ETDEWEB)

    Al Lawati, Wafa M. [School of Earth, Atmospheric and Environmental Sciences, Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester (United Kingdom); Higher College of Technology, Ministry of Manpower, Muscat (Oman); Jean, Jiin-Shuh [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan (China); Kulp, Thomas R. [Department of Earth Sciences and Environmental Studies, State University of New York, Binghamton, NY (United States); Lee, Ming-Kuo [Department of Geology and Geography, Auburn University, Auburn, AL (United States); Polya, David A. [School of Earth, Atmospheric and Environmental Sciences, Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester (United Kingdom); Liu, Chia-Chuan [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan (China); Dongen, Bart E. van, E-mail: Bart.vanDongen@manchester.ac.uk [School of Earth, Atmospheric and Environmental Sciences, Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester (United Kingdom)

    2013-11-15

    Highlights: ► First lipid analysis of Taiwanese aquifer sediments from groundwater As-prone region. ► Both plant-derived terrestrial and mature hydrocarbon lipid sources identified. ► Organic matter sources similar to those of other high As groundwater aquifers. ► Groundwater arsenic at depth controlled by biotic As mobilisation processes. ► Biotic As mobilisation not controlled by a specific source of analysed organic matter. -- Abstract: Arsenic (As) in groundwaters extensively used by people across the world constitutes a serious public health threat. The importance of organic matter (OM) as an electron donor in microbially-mediated reduction of As(V) or Fe(III)-bearing As-host minerals leading to mobilisation of solid-phase arsenic is widely recognised. Notwithstanding this, there are few studies characterising OM in such aquifers and, in particular, there is a dearth of data from the classic arsenic bearing aquifers in southwestern Taiwan. Organic geochemical analyses of sediments from a known groundwater arsenic hot-spot in southwestern Taiwan revealed contributions of thermally mature and plant derived origin, consistent with OM sources in all other Asian groundwater aquifer sediments analysed to date, indicating comparable sources and routes of OM transfer. The combined results of amended As(V) reduction assays with the organic geochemical analysis revealed that the microbiological process of dissimilatory As(V) reduction is active in this aquifer, but it is not controlled by a specific source of analysed OM. These indicate that (i) part of the OM that was considered to be less bio-available could still be used as an electron donor or (ii) other electron donors, not analysed in present study, could be controlling the rate of As release.

  15. Uruguay mining inventory. Geochemical prospecting results of the Las Flores aerial map[Study of Uranium geochemical prospection in Uruguay]; Inventario minero del Uruguay. Resultados de la prospeccion geoquimica del fotoplano Las Flores

    Energy Technology Data Exchange (ETDEWEB)

    Zeegers, H; Bonnefoy, D; Garau, M; Spangenberg, J

    1981-07-01

    In the context of the Uruguay mining inventory, the aerial photography map Las Flores had been covered by a specific strategic which included geochemical prospecting elements. The surface covered has the 550 km2, and 1042 samples which they have been analized in Orleans France. 22 elements by plasma spectroscopy and gold by atomic absorption and for uranium laser spectroscopy . They have been evidenced the following anomalies: gold, Pb, Pb-Ba-Cu, Ba and Ni-Cr.

  16. Instrumenting caves to collect hydrologic and geochemical data: case study from James Cave, Virginia

    Science.gov (United States)

    Schreiber, Madeline E.; Schwartz, Benjamin F.; Orndorff, William; Doctor, Daniel H.; Eagle, Sarah D.; Gerst, Jonathan D.

    2015-01-01

    Karst aquifers are productive groundwater systems, supplying approximately 25 % of the world’s drinking water. Sustainable use of this critical water supply requires information about rates of recharge to karst aquifers. The overall goal of this project is to collect long-term, high-resolution hydrologic and geochemical datasets at James Cave, Virginia, to evaluate the quantity and quality of recharge to the karst system. To achieve this goal, the cave has been instrumented for continuous (10-min interval) measurement of the (1) temperature and rate of precipitation; (2) temperature, specific conductance, and rate of epikarst dripwater; (3) temperature of the cave air; and (4) temperature, conductivity, and discharge of the cave stream. Instrumentation has also been installed to collect both composite and grab samples of precipitation, soil water, the cave stream, and dripwater for geochemical analysis. This chapter provides detailed information about the instrumentation, data processing, and data management; shows examples of collected datasets; and discusses recommendations for other researchers interested in hydrologic and geochemical monitoring of cave systems. Results from the research, briefly described here and discussed in more detail in other publications, document a strong seasonality of the start of the recharge season, the extent of the recharge season, and the geochemistry of recharge.

  17. Toward a better understanding of the complex geochemical processes governing subsurface contaminant transport

    International Nuclear Information System (INIS)

    Puls, R.W.

    1990-01-01

    Identification and understanding of the geochemical processes, including ion exchange, precipitation, organic partitioning, chemisorption, aqueous complexation, and colloidal stability and transport, controlling subsurface contamination is essential for making accurate predictions of the fate and transport of these constituents. Current approaches to quantify the effect of these processes primarily involve laboratory techniques, including the use of closed static systems (batch experiments) where small amounts of aquifer solids or minerals are contacted with an aqueous phase containing the components of interest for relatively short durations; and dynamic systems (column experiments) where a larger segment of the aquifer is investigated by analyzing the breakthrough profiles of reactive and non-reactive species. Both approaches are constrained by differences in scale, alteration of media during sample collection and use, and spatial variability. More field reactivity studies are needed to complement established laboratory approaches for the determination of retardation factors and scaling factors, corroboration of batch and column results, and validation of sampling techniques. These studies also serve to accentuate areas of geochemical process research where data deficiencies exist, such as the kinetics of adsorption-desorption, metal-organic-mineral interactions, and colloidal mobility. The advantages and disadvantages of the above approaches are discussed in the context of achieving a more completely integrated approach to geochemical transport experiments, with supportive data presented from selected studies. (Author) (16 refs., 4 figs., 2 tabs.)

  18. Evaluation of the fate of arsenic-contaminated groundwater at different aquifers of Thar coalfield Pakistan.

    Science.gov (United States)

    Ali, Jamshed; Kazi, Tasneem G; Baig, Jameel A; Afridi, Hassan I; Arain, Mariam S; Ullah, Naeem; Brahman, Kapil D; Arain, Sadaf S; Panhwar, Abdul H

    2015-12-01

    In present study, the ground water at different aquifers was evaluated for physicochemical parameters, iron, total arsenic, total inorganic arsenic and arsenic species (arsenite and arsenate). The samples of groundwater were collected at different depths, first aquifer (AQ1) 50-60 m, second aquifer (AQ2) 100-120 m, and third aquifer (AQ3) 200-250 m of Thar coalfield, Pakistan. Total inorganic arsenic was determined by solid phase extraction using titanium dioxide as an adsorbent. The arsenite was determined by cloud point extraction using ammonium pyrrolidinedithiocarbamate as a chelating reagent, and resulted complex was extracted by Triton X-114. The resulted data of groundwater were reported in terms of basic statistical parameters, principal component, and cluster analysis. The resulted data indicated that physicochemical parameters of groundwater of different aquifers were exceeded the World Health Organization provisional guideline for drinking water except pH and SO4(2-). The positive correlation was observed between arsenic species and physicochemical parameters of groundwater except F(-) and K(+), which might be caused by geochemical minerals. Results of cluster analysis indicated that groundwater samples of AQ1 was highly contaminated with arsenic species as compared to AQ2 and AQ3 (p > 0.05).

  19. Geochemical modeling: a review

    International Nuclear Information System (INIS)

    Jenne, E.A.

    1981-06-01

    Two general families of geochemical models presently exist. The ion speciation-solubility group of geochemical models contain submodels to first calculate a distribution of aqueous species and to secondly test the hypothesis that the water is near equilibrium with particular solid phases. These models may or may not calculate the adsorption of dissolved constituents and simulate the dissolution and precipitation (mass transfer) of solid phases. Another family of geochemical models, the reaction path models, simulates the stepwise precipitation of solid phases as a result of reacting specified amounts of water and rock. Reaction path models first perform an aqueous speciation of the dissolved constituents of the water, test solubility hypotheses, then perform the reaction path modeling. Certain improvements in the present versions of these models would enhance their value and usefulness to applications in nuclear-waste isolation, etc. Mass-transfer calculations of limited extent are certainly within the capabilities of state-of-the-art models. However, the reaction path models require an expansion of their thermodynamic data bases and systematic validation before they are generally accepted

  20. Geochemical modeling: a review

    Energy Technology Data Exchange (ETDEWEB)

    Jenne, E.A.

    1981-06-01

    Two general families of geochemical models presently exist. The ion speciation-solubility group of geochemical models contain submodels to first calculate a distribution of aqueous species and to secondly test the hypothesis that the water is near equilibrium with particular solid phases. These models may or may not calculate the adsorption of dissolved constituents and simulate the dissolution and precipitation (mass transfer) of solid phases. Another family of geochemical models, the reaction path models, simulates the stepwise precipitation of solid phases as a result of reacting specified amounts of water and rock. Reaction path models first perform an aqueous speciation of the dissolved constituents of the water, test solubility hypotheses, then perform the reaction path modeling. Certain improvements in the present versions of these models would enhance their value and usefulness to applications in nuclear-waste isolation, etc. Mass-transfer calculations of limited extent are certainly within the capabilities of state-of-the-art models. However, the reaction path models require an expansion of their thermodynamic data bases and systematic validation before they are generally accepted.

  1. Guarani aquifer

    International Nuclear Information System (INIS)

    2007-01-01

    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

  2. Arsenic in groundwater of the Red River floodplain, Vietnam: Controlling geochemical processes and reactive transport modeling

    DEFF Research Database (Denmark)

    Postma, Diederik Jan; Larsen, Flemming; Hue, N.T.M.

    2007-01-01

    The mobilization of arsenic (As) to the groundwater was studied in a shallow Holocene aquifer on the Red River flood plain near Hanoi, Vietnam. The groundwater chemistry was investigated in a transect of 100 piezometers. Results show an anoxic aquifer featuring organic carbon decomposition......(III) but some As(V) is always found. Arsenic correlates well with NH4, relating its release to organic matter decomposition and the source of As appears to be the Fe-oxides being reduced. Part of the produced Fe(II) is apparently reprecipitated as siderite containing less As. Results from sediment extraction...... chemistry over depth is homogeneous and a reactive transport model was constructed to quantify the geochemical processes along the vertical groundwater flow component. A redox zonation model was constructed using the partial equilibrium approach with organic carbon degradation in the sediment as the only...

  3. Uruguay mining Inventory: Geochemical prospecting results of Valentines mapping; Inventario minero del Uruguay : Resultados de la prospeccion geoquimica del fotoplano Valentines

    Energy Technology Data Exchange (ETDEWEB)

    Spangenberg, J; Filippini, J

    1985-07-01

    This work is about geochemical prospecting carried out into the Uruguay mining inventory framework. In this case the survey was in Valentines mapping. Florida, Durazno and Treinta y Tres provinces of Uruguay .

  4. AQUIFER IN AJAOKUTA, SOUTHWESTERN NIGERIA

    African Journals Online (AJOL)

    2005-03-08

    Mar 8, 2005 ... To establish the feasibility of water supply in a basement complex area ofAjaokuta, Southwestern Nigeria, pumping test results were used to investigate the storage properties and groundwater potential of the aquifer. The aquifer system consists of weathered and weathered/fractured zone of decomposed ...

  5. The fluoride in the groundwater of Guarani Aquifer System: the origin associated with black shales of Paraná Basin

    Science.gov (United States)

    Kern, M. L.; Vieiro, A. P.; Machado, G.

    2008-09-01

    This work presents petrological and geochemical results of the black shales interval from Permian and Devonian strata of the Paraná Basin, Brazil and its relationships with fluoride of groundwater from Guarani Aquifer System. The Guarani Aquifer, located in South Brazil, Uruguay, Paraguay and Argentine, presents contents of fluoride higher than the Brazilian accepted potability limits. Several hypotheses have been presented for the origin of the fluoride in the groundwater of the Guarani Aquifer. Microcrystalline fluorite was registered in black shales of Ponta Grossa and Irati formations from Paraná Basin. The results shown in this work suggest that fluoride present in groundwater of Guarani Aquifer can be originated in deeper groundwater that circulates in Ponta Grossa and Irati formations. The interaction of the groundwater coming from deeper black shales with the groundwater-bearing Aquifer Guarani System occurs through regional fragile structures (faults and fractures) that constitute excellent hydraulic connectors between the two sedimentary packages. The microcrystalline fluorite registered in Ponta Grossa and Irati Formations can be dissolved promoting fluoride enrichment in groundwater of these black shales and Guarani Aquifer System.

  6. Surface complexation modeling of groundwater arsenic mobility: Results of a forced gradient experiment in a Red River flood plain aquifer, Vietnam

    DEFF Research Database (Denmark)

    Jessen, Søren; Postma, Dieke; Larsen, Flemming

    2012-01-01

    , suggesting a comparable As(III) affinity of Holocene and Pleistocene aquifer sediments. A forced gradient field experiment was conducted in a bank aquifer adjacent to a tributary channel to the Red River, and the passage in the aquifer of mixed groundwater containing up to 74% channel water was observed......Three surface complexation models (SCMs) developed for, respectively, ferrihydrite, goethite and sorption data for a Pleistocene oxidized aquifer sediment from Bangladesh were used to explore the effect of multicomponent adsorption processes on As mobility in a reduced Holocene floodplain aquifer......(III) while PO43− and Fe(II) form the predominant surface species. The SCM for Pleistocene aquifer sediment resembles most the goethite SCM but shows more Si sorption. Compiled As(III) adsorption data for Holocene sediment was also well described by the SCM determined for Pleistocene aquifer sediment...

  7. A geochemical and isotopic approach to recharge evaluation in semi-arid zones. Past and present

    International Nuclear Information System (INIS)

    Edmunds, W.M.; Walton, N.R.G.

    1980-01-01

    The magnitude of any recharge to aquifers in semi-arid and arid zones is the principal uncertainty in estimating a water balance. Recent studies in Cyprus and Libyan Arab Jamahiriya are currently being used to demonstrate the application of geochemical and isotopic techniques, to the determination of both current and palaeo-recharge. In Cyprus, solute profiles of the unsaturated zone have been interpreted to provide estimates of the direct recharge component using a steady-state, mass-balance approach; results from the chloride profiles compare well with recharge estimates using tritium. In addition, it is found that some solute peaks, notably for specific electrical conductance, give a reasonably accurate record of the rainfall history during the period 1950-1975. The solute profile method is relatively unsophisticated and could be more widely applied to recharge estimation in other semi-arid areas of the world. In Libya, a clear distinction can be made using the combined isotopic, hydrological and geochemical results between regional groundwaters recharged to the upper, unconfined aquifer of the Sirte Basin before 13,000 years BP and younger waters recharged locally during the period 5000-7800 years BP. A well-defined fresh-water channel, superimposed upon the regional water quality pattern, can be traced within the aquifer for some 130 km and represents direct evidence of recharge during the Holocene. Some shallow groundwaters of similar composition to the fresh-water channel are also considered to represent recent, if intermittent, recharge which took place during historical times. It is concluded that geochemical and isotopic studies of both the unsaturated zone and of shallow groundwaters in semi-arid regions, can be used to determine not only the present-day direct recharge component, but also a recharge chronology of immediate historic times, which may be important in the estimation of long-term water resources. (author)

  8. Fate of inorganic contaminants post treatment of acid mine drainage by cryptocrystalline magnesite: Complimenting experimental results with a geochemical model

    CSIR Research Space (South Africa)

    Masindi, V

    2016-03-01

    Full Text Available at an optimum solid: liquid ratio of 1:100 and contact time of 60 min led to an increase in pH, reaching a maximum pH of 10, resulting in significant precipitation of most metal species. Increase of pH in solution with contact time caused the removal...

  9. Land-use change and managed aquifer recharge effects on the hydrogeochemistry of two contrasting atoll island aquifers, Roi-Namur Island, Republic of the Marshall Islands

    Science.gov (United States)

    Hejazian, Mehrdad; Gurdak, Jason J.; Swarzenski, Peter W.; Odigie, Kingsley; Storlazzi, Curt

    2017-01-01

    Freshwater resources on low-lying atoll islands are highly vulnerable to climate change and sea-level rise. In addition to rainwater catchment, groundwater in the freshwater lens is a critically important water resource on many atoll islands, especially during drought. Although many atolls have high annual rainfall rates, dense natural vegetation and high evapotranspiration rates can limit recharge to the freshwater lens. Here we evaluate the effects of land-use/land-cover change and managed aquifer recharge on the hydrogeochemistry and supply of groundwater on Roi-Namur Island, Republic of the Marshall Islands. Roi-Namur is an artificially conjoined island that has similar hydrogeology on the Roi and Namur lobes, but has contrasting land-use/land-cover and managed aquifer recharge only on Roi. Vegetation removal and managed aquifer recharge operations have resulted in an estimated 8.6 x 105 m3 of potable groundwater in the freshwater lens on Roi, compared to only 1.6 x 104 m3 on Namur. We use groundwater samples from a suite of 33 vertically nested monitoring wells, statistical testing, and geochemical modeling using PHREEQC to show that the differences in land-use/land-cover and managed aquifer recharge on Roi and Namur have a statistically significant effect on several groundwater-quality parameters and the controlling geochemical processes. Results also indicate a seven-fold reduction in the dissolution of carbonate rock in the freshwater lens and overlying vadose zone of Roi compared to Namur. Mixing of seawater and the freshwater lens is a more dominant hydrogeochemical process on Roi because of the greater recharge and flushing of the aquifer with freshwater as compared to Namur. In contrast, equilibrium processes and dissolution-precipitation non-equilibrium reactions are more dominant on Namur because of the longer residence times relative to the rate of geochemical reactions. Findings from Roi-Namur Island support selective land-use/land-cover change and

  10. Predicting salt intrusion into freshwater aquifers resulting from CO2 injection – A study on the influence of conservative assumptions

    DEFF Research Database (Denmark)

    Walter, Lena; Binning, Philip John; Class, Holger

    2013-01-01

    . A crucial task is to choose an appropriate conceptual model and relevant scenarios. Overly conservative assumptions may lead to estimation of unacceptably high risks, and thus prevent the implementation of a CO2 storage project unnecessarily. On the other hand, risk assessment should not lead...... to an underestimation of hazards. This study compares two conceptual model approaches for the numerical simulation of brine-migration scenarios through a vertical fault and salt intrusion into a fresh water aquifer. The first approach calculates salt discharge into freshwater using an immiscible two-phase model...... with constant salinity in the brine phase. The second approach takes compositional effects into account and considers salinity as a variable parameter in the water phase. A spatial model coupling is introduced to adapt the increased model complexity to the required complexity of the physics. The immiscible two...

  11. Modern Processes of Hydrocarbon Migration and Re-Formation of Oil and Gas Fields (Based on the Results of Monitoring and Geochemical Studies)

    Science.gov (United States)

    Plotnikova, Irina; Salakhidinova, Gulmira; Nosova, Fidania; Pronin, Nikita; Ostroukhov, Sergey

    2015-04-01

    Special geochemical studies of oils allowed to allocate a movable migration component of oils in the industrial oil deposits. In the field the migration component of oils varies in different parts of the field. The largest percentage of the light migration component (gas condensate of the oil) was detected in the central part of the Kama-Kinel troughs system. Monitoring of the composition of water, oil and gas (condensate light oil component) in the sedimentary cover and ni crystalline basement led to the conclusion of modern migration of hydrocarbons in sedimentary cover. This proves the existence of the modern processes of formation and reformation of oil and gas fields. This presentation is dedicated to the problem of definition of geochemical criteria of selection of hydrocarbons deposit reformation zone in the sample wells of Minibaevskaya area of Romashkinskoye field. While carrying out this work we examined 11 samples of oil from the Upper Devonian Pashiysky horizon. Four oil samples were collected from wells reckoned among the "anomalous" zones that were marked out according to the results of geophysical, oil field and geological research. Geochemical studies of oils were conducted in the laboratory of geochemistry of the Kazan (Volga-region) Federal University. The wells where the signs of hydrocarbons influx from the deep zones of the crust were recorded are considered to be "anomalous". A number of scientists connect this fact to the hypothesis about periodic influx of deep hydrocarbons to the oil deposits of Romashkinskoye field. Other researchers believe that the source rocks of the adjacent valleys sedimentary cover generate gases when entering the main zone of gas formation, which then migrate up the section and passing through the previously formed deposits of oil, change and "lighten" their composition. Regardless of the point of view on the source of the hydrocarbons, the study of the process of deposits refilling with light hydrocarbons is an

  12. Radium and radon isotope investigations as tool for aquifer diagnostics considering the geochemical and hydrochemical conditions in the ground water aquifer; Radium- und Radon-Isotopen-Untersuchungen als Hilfsmittel fuer die Aquiferdiagnose unter besonderer Beruecksichtigung der geochemischen und hydrochemischen Verhaeltnisse im Grundwasserleiter

    Energy Technology Data Exchange (ETDEWEB)

    Hurst, Stephanie

    2014-12-12

    The thesis was aimed to the development of methods for enhanced interpretation of the hydraulic conditions in a groundwater aquifer based on the determination of the Rn-222/Ra-226 ration. Further investigations concerned rocks and rock surfaces (secondary minerals) with respect to the solubility and the mobility of radium in the ground water. The samples were withdrawn in the region of the continental deep borehole (KTB Oberpfalz) and the Czech Republic (Egergraben).

  13. Geochemical computer codes. A review

    International Nuclear Information System (INIS)

    Andersson, K.

    1987-01-01

    In this report a review of available codes is performed and some code intercomparisons are also discussed. The number of codes treating natural waters (groundwater, lake water, sea water) is large. Most geochemical computer codes treat equilibrium conditions, although some codes with kinetic capability are available. A geochemical equilibrium model consists of a computer code, solving a set of equations by some numerical method and a data base, consisting of thermodynamic data required for the calculations. There are some codes which treat coupled geochemical and transport modeling. Some of these codes solve the equilibrium and transport equations simultaneously while other solve the equations separately from each other. The coupled codes require a large computer capacity and have thus as yet limited use. Three code intercomparisons have been found in literature. It may be concluded that there are many codes available for geochemical calculations but most of them require a user that us quite familiar with the code. The user also has to know the geochemical system in order to judge the reliability of the results. A high quality data base is necessary to obtain a reliable result. The best results may be expected for the major species of natural waters. For more complicated problems, including trace elements, precipitation/dissolution, adsorption, etc., the results seem to be less reliable. (With 44 refs.) (author)

  14. Mesozoic Magmatism and Base-Metal Mineralization in the Fortymile Mining District, Eastern Alaska - Initial Results of Petrographic, Geochemical, and Isotopic Studies in the Mount Veta Area

    Science.gov (United States)

    Dusel-Bacon, Cynthia; Slack, John F.; Aleinikoff, John N.; Mortensen, James K.

    2009-01-01

    We present here the initial results of a petrographic, geochemical, and isotopic study of Mesozoic intrusive rocks and spatially associated Zn-Pb-Ag-Cu-Au prospects in the Fortymile mining district in the southern Eagle quadrangle, Alaska. Analyzed samples include mineralized and unmineralized drill core from 2006 and 2007 exploration by Full Metal Minerals, USA, Inc., at the Little Whiteman (LWM) and Fish prospects, and other mineralized and plutonic samples collected within the mining district is part of the USGS study. Three new ion microprobe U-Pb zircon ages are: 210 +- 3 Ma for quartz diorite from LWM, 187 +- 3 Ma for quartz monzonite from Fish, and 70.5 +- 1.1 Ma for altered rhyolite porphyry from Fish. We also present 11 published and unpublished Mesozoic thermal ionization mass spectrometric U-Pb zircon and titanite ages and whole-rock geochemical data for the Mesozoic plutonic rocks. Late Triassic and Early Jurassic plutons generally have intermediate compositions and are slightly foliated, consistent with synkinematic intrusion. Several Early Jurassic plutons contain magmatic epidote, indicating emplacement of the host plutons at mesozonal crustal depths of greater than 15 km. Trace-element geochemical data indicate an arc origin for the granitoids, with an increase in the crustal component with time. Preliminary study of drill core from the LWM Zn-Pb-Cu-Ag prospect supports a carbonate-replacement model of mineralization. LWM massive sulfides consist of sphalerite, galena, and minor pyrite and chalcopyrite, in a gangue of calcite and lesser quartz; silver resides in Sb-As-Ag sulfosalts and pyrargyrite, and probably in submicroscopic inclusions within galena. Whole-rock analyses of LWM drill cores also show elevated In, an important metal in high-technology products. Hypogene mineralized rocks at Fish, below the secondary Zn-rich zone, are associated with a carbonate host and also may be of replacement origin, or alternatively, may be a magnetite

  15. Review of simulation techniques for aquifer thermal energy storage (ATES)

    Energy Technology Data Exchange (ETDEWEB)

    Mercer, J.W.; Faust, C.R.; Miller, W.J.; Pearson, F.J. Jr.

    1981-03-01

    The storage of thermal energy in aquifers has recently received considerable attention as a means to conserve and more efficiently use energy supplies. The analysis of aquifer thermal energy storage (ATES) systems will rely on the results from mathematical and geochemical models. Therefore, the state-of-the-art models relevant to ATES was reviewed and evaluated. These models describe important processes active in ATES including ground-water flow, heat transport (heat flow), solute transport (movement of contaminants), and geochemical reactions. In general, available models of the saturated ground-water environment are adequate to address most concerns associated with ATES; that is, design, operation, and environmental assessment. In those cases where models are not adequate, development should be preceded by efforts to identify significant physical phenomena and relate model parameters to measurable quantities. Model development can then proceed with the expectation of an adequate data base existing for the model's eventual use. Review of model applications to ATES shows that the major emphasis has been on generic sensitivity analysis and site characterization. Assuming that models are applied appropriately, the primary limitation on model calculations is the data base used to construct the model. Numerical transport models are limited by the uncertainty of subsurface data and the lack of long-term historical data for calibration. Geochemical models are limited by the lack of thermodynamic data for the temperature ranges applicable to ATES. Model applications undertaken with data collection activities on ATES sites should provide the most important contributions to the understanding and utilization of ATES. Therefore, the primary conclusion of this review is that model application to field sites in conjunction with data collection activities is essential to the development of this technology.

  16. Characterization of geochemical constituents and bacterial populations associated with As mobilization in deep and shallow tube wells in Bangladesh.

    Science.gov (United States)

    Sutton, Nora B; van der Kraan, Geert M; van Loosdrecht, Mark C M; Muyzer, Gerard; Bruining, Johannes; Schotting, Ruud J

    2009-04-01

    While millions of people drink arsenic-contaminated tube well water across Bangladesh, there is no recent scientific explanation which is able to either comprehensively explain arsenic mobilization or to predict the spatial distribution of affected wells. Rather, mitigation strategies have focused on the sinking of deep tube wells into the currently arsenic-free Pleistocene aquifer. In this study, Bangladesh shallow tube wells identified as contaminated and uncontaminated, as well as deep tube wells, were analyzed for geochemical and in situ microbiological composition. Whereas arsenic was detected in all Holocene aquifer wells, no arsenic was found in wells accessing the Pleistocene aquifer. Bacterial genera, including Comamonadaceae, Acidovorax, Acinetobacter, and Hydrogenophaga, associated with tolerance of high arsenic concentrations, rather than dissimilatory Fe(III) or As(V) reduction, were identified in shallow tube wells, indicating that mobilization may not occur at depth, but is rather due to drawdown of surface contaminated water. Deep tube wells contained microbes indicative of aerobic conditions, including the genera Aquabacterium, Limnobacter, and Roseomonas. It is concluded that through drawdown of arsenic or organic matter, further utilization of the Pleistocene aquifer could result in contamination similar to that observed in the Holocene aquifer.

  17. Demonstrating managed aquifer recharge as a solution for climate change adaptation: results from Gabardine project and asemwaterNet coordination action in the Algarve region (Portugal

    Directory of Open Access Journals (Sweden)

    João Paulo Lobo Ferreira

    2014-09-01

    Full Text Available In the Algarve southern Portugal region, Managed Aquifer Recharge (MAR research activities have been developed to provide not only water surplus storage in aquifers during wet years, focusing in the Querença-Silves aquifer (FP6 ASEMWATERNet Coordination Action, but also groundwater quality rehabilitation in the Campina de Faro aquifer (FP6 Gabardine Project. Following MAR research potentialities in southern Portugal, this paper describes the objectives, conceptual demonstration, background and capabilities of one of the selected Circum-Mediterranean pilot sites (in Portugal that will be researched in the new FP7-ENV-2013-WATER-INNO-DEMO MARSOL project, which started Dec. 1st, 2013. In the Algarve pilot site, several case-study areas will be located in the Querença-Silves aquifer and in the Campina de Faro aquifer.

  18. Groundwater-quality data for the Madera/Chowchilla–Kings shallow aquifer study unit, 2013–14: Results from the California GAMA Program

    Science.gov (United States)

    Shelton, Jennifer L.; Fram, Miranda S.

    2017-02-03

    Groundwater quality in the 2,390-square-mile Madera/Chowchilla–Kings Shallow Aquifer study unit was investigated by the U.S. Geological Survey from August 2013 to April 2014 as part of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment Program’s Priority Basin Project. The study was designed to provide a statistically unbiased, spatially distributed assessment of untreated groundwater quality in the shallow aquifer systems of the Madera, Chowchilla, and Kings subbasins of the San Joaquin Valley groundwater basin. The shallow aquifer system corresponds to the part of the aquifer system generally used by domestic wells and is shallower than the part of the aquifer system generally used by public-supply wells. This report presents the data collected for the study and a brief preliminary description of the results.Groundwater samples were collected from 77 wells and were analyzed for organic constituents, inorganic constituents, selected isotopic and age-dating tracers, and microbial indicators. Most of the wells sampled for this study were private domestic wells. Unlike groundwater from public-supply wells, the groundwater from private domestic wells is not regulated for quality in California and is rarely analyzed for water-quality constituents. To provide context for the sampling results, however, concentrations of constituents measured in the untreated groundwater were compared with regulatory and non-regulatory benchmarks established for drinking-water quality by the U.S. Environmental Protection Agency, the State of California, and the U.S. Geological Survey.Of the 319 organic constituents assessed in this study (90 volatile organic compounds and 229 pesticides and pesticide degradates), 17 volatile organic compounds and 23 pesticides and pesticide degradates were detected in groundwater samples; concentrations of all but 2 were less than the respective benchmarks. The fumigants 1,2-dibromo-3-chloropropane (DBCP

  19. Geochemical tracing and hydrogeochemical modelling of water-rock interactions during salinization of alluvial groundwater (Upper Rhine Valley, France)

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, Y., E-mail: yann.lucas@eost.u-strasbg.fr [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France); Schmitt, A.D., E-mail: anne-desiree.schmitt@univ-fcomte.fr [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France)] [Universite de Franche-Comte et CNRS-UMR 6249, Chrono-Environnement, 16, Route de Gray, 25030 Besancon Cedex (France); Chabaux, F., E-mail: francois.chabaux@eost.u-strasbg.fr [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France); Clement, A.; Fritz, B. [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France); Elsass, Ph. [BRGM, GEODERIS, 1, rue Claude Chappe, 57070 Metz (France); Durand, S. [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France)

    2010-11-15

    Research highlights: {yields} Major and trace elements along with strontium and uranium isotopic ratios show that groundwater geochemical characteristics along the saline plumes cannot reflect a conservative mixing. {yields} A coupled hydrogeochemical model demonstrates that cationic exchange between alkalis from polluted waters and alkaline-earth elements from montmorillonite present in the host rock of the aquifer is the primary process. {yields} The model requires only a small amount of montmorillonite. {yields} It is necessary to consider the pollution history to explain the important chloride, sodium and calcium concentration modifications. {yields} The model shows that the rapidity of the cationic exchange reactions insures a reversibility of the cation fixation on clays in the aquifer. - Abstract: In the southern Upper Rhine Valley, groundwater has undergone intensive saline pollution caused by the infiltration of mining brines, a consequence of potash extraction carried out during the 20th century. Major and trace elements along with Sr and U isotopic ratios show that groundwater geochemical characteristics along the saline plumes cannot reflect conservative mixing between saline waters resulting from the dissolution of waste heaps and one or more unpolluted end-members. The results imply the occurrence of interactions between host rocks and polluted waters, and they suggest that cationic exchange mechanisms are the primary controlling process. A coupled hydrogeochemical model has been developed with the numerical code KIRMAT, which demonstrates that cationic exchange between alkalis from polluted waters and alkaline-earth elements from montmorillonite present in the host rock of the aquifer is the primary process controlling the geochemical evolution of the groundwater. The model requires only a small amount of montmorillonite (between 0.75% and 2.25%), which is in agreement with the observed mineralogical composition of the aquifer. The model also proves

  20. Palaeoclimatic trends deduced from the hydrochemistry of a Triassic sandstone aquifer, U.K

    International Nuclear Information System (INIS)

    Bath, A.H.; Edmunds, W.M.; Andrews, J.N.

    1978-01-01

    A detailed geochemical study (elemental, isotopic and dissolved inert gases) of unconfined and confined sections of the Triassic non-marine sandstone aquifer in Eastern England has been undertaken. Aspects of the recharge history of this aquifer over the past 40 000 years are revealed by examination of the data. (orig./HK) [de

  1. Fate of nine recycled water trace organic contaminants and metal(loid)s during managed aquifer recharge into a anaerobic aquifer: Column studies.

    Science.gov (United States)

    Patterson, B M; Shackleton, M; Furness, A J; Pearce, J; Descourvieres, C; Linge, K L; Busetti, F; Spadek, T

    2010-03-01

    Water quality changes associated with the passage of aerobic reverse osmosis (RO) treated recycled water through a deep anaerobic pyritic aquifer system was evaluated in sediment-filled laboratory columns as part of a managed aquifer recharge (MAR) strategy. The fate of nine recycled water trace organic compounds along with potential negative water quality changes such as the release of metal(loid)s were investigated in large-scale columns over a period of 12 months. The anaerobic geochemical conditions provided a suitable environment for denitrification, and rapid (half-life 100 days). High retardation coefficients (R) determined for many of the trace organics (R 13 to 67) would increase aquifer residence time and be beneficial for many of the slow degrading compounds. However, for the trace organics with low R values (1.1-2.6) and slow degradation rates (half-life > 100 days), such as N-nitrosodimethylamine, N-nitrosomorpholine and iohexol, substantial biodegradation during aquifer passage may not occur and additional investigations are required. Only minor transient increases in some metal(loid) concentrations were observed, as a result of either pyrite oxidation, mineral dissolution or pH induced metal desorption, followed by metal re-sorption downgradient in the oxygen depleted zone. Crown Copyright 2009. Published by Elsevier Ltd. All rights reserved.

  2. Geochemical and isotopic characterization of the ground water of Oued Laya

    International Nuclear Information System (INIS)

    Hkiri, Sabrine

    2010-01-01

    In the Sahel region of Sousse (Tunisia Center East), almost all of the deep groundwater has undergone over the last decade, a general decline of groundwater level. This decrease is caused by two factors, the intensive farming and drought. These aquifers, despite their often poor quality (high salinity), are increasingly used, so they are now home to intense exploitation, whose consequences have emerged as significant declines of groundwater level and degradation of the chemical quality of their water. This study concerns a groundwater aquifer that is under stress and anthropogenic climate severe enough: the coastal aquifer of Wad Laya present quality of groundwater qualified low salinity point of view compared to other neighboring aquifers. The salinity is apparently not related to over exploitation as the majority of coastal aquifers but seems it is due to the geological nature which forms the water table. The region's climate is semiarid with an average annual rainfall of 320 mm by 100 years; the FTE is 1750 mm / year resulting in a water deficit of more than 1.4 m / year. Renewable resources are estimated at 3.3 million m3, while for the levy is estimated to be 2.7 million m3 which the dry residue is currently spent 5g / l (CRDA Sousse, 2009). The objective of this study included hydrogeological characterization of the aquifer using geophysical tools and identification of mechanisms of salination using geochemical and isotopic tools to determine the possible origins of mineralization. For this campaign sampling and measurement was made in the region over a thirty water points in order to measure the electrical conductivity, groundwater level and analyze the chemical composition (major and trace elements). Initial findings from this study are summarized in: Completion of piezometric maps and potentiometric study of the evolution in some wells show a decline of water table caused by the increased exploitation and lower rainfall, which resulted in an increase in

  3. Basin-scale hydrogeological, geophysical, geochemical and isotopic characterization: an essential tool for building a Decision Support System for the sustainable management of alluvial aquifer systems within the provinces of Milan and Monza-Brianza (Northern Italy

    Directory of Open Access Journals (Sweden)

    Maurizio Gorla

    2016-10-01

    Full Text Available CAP Group is a public company, supplying the municipalities within the provinces of Milan and Monza/Brianza (Northern Italy with the integrated water service: 197 municipalities and more than 2 million users served, 887 wells, 154 wall-mounted tanks and hubs, a water supply network of over 7500 km, from which approximately 250 million cubic metres of water per year are withdrawn. The drinking water supply comes exclusively from groundwater resources, circulating in several overlapping aquifer systems. Basin-scale water resource management, as required by the European Water Framework Directive (2000/60/EC, is an extremely complex task. In view of this backdrop, CAP is currently developing a project called Infrastructural Aqueduct Plan that relies on a Decision Support System approach. The paper describes the preliminary steps concerning the design of a prototype Decision Support System aiming at the management of groundwater resources on a basin scale (Ticino and Adda rivers area. CAP Group Decision Support System is intended to be a package allowing for water resource assessment, identification of boundary conditions, climatic driving forces and demographic pressures, simulation and investigation of future forecasts and comparison of alternative policy measures. The project has been designed in steps including Geodatabase building, geographic information system (GIS analysis (including multilayer analysis and numerical modelling. The data collected in the geodatabase were analyzed to design GIS quantitative and qualitative thematic maps in order to perform the multilayer analysis of current and future state and impacts, for providing the decision maker with a comprehensive picture of the water system. The multilayer analysis relies on specific indicators based on some quantitative and qualitative data: hydrogeological, chemical, isotopic, soil use and hazards, climatic and demographic. Each parameter belonging to these macro areas were

  4. Reaction of subsurface coastal aquifers to climate and land use changes in Greece: modelling of groundwater refreshening patterns under natural recharge conditions

    Science.gov (United States)

    Lambrakis, N.; Kallergis, G.

    2001-05-01

    This paper studies the multicomponent ion exchange process and freshening time under natural recharge conditions for three coastal aquifers in Greece. Due to over-pumping and the dry years of 1980-1990 decline in groundwater quality has been observed in most of the Greek coastal aquifers. This decline is caused by a lack of reliable water resource management, water abstraction from great depths, and seawater intrusion resulting in a rise of the fresh/salt water interface (salinisation process) due to a negative water balance. The reverse phenomenon, which should lead to groundwater freshening, is a long process. The freshening process shows chromatographic patterns that are due to chemical reactions such as calcite dissolution and cation exchange, and simultaneously occurring transport and dispersion processes. Using the geochemical simulation codes PHREEQE and PHREEQM (Parkhurst et al., US Geol. Surv. Water Resour. Invest., 80-96 (1980) 210; Appelo and Postma, Geochemistry, Groundwater and Pollution (1994)), these patterns were analysed and the above-mentioned processes were simulated for carefully selected aquifers in Peloponnesus and Crete (Greece). Aquifers of the Quaternary basin of Glafkos in Peloponnesus, the Neogene formations in Gouves, Crete, and the carbonate aquifer of Malia, Crete, were examined as representative examples of Greek coastal aquifer salinisation. The results show that when pumping was discontinued, the time required for freshening under natural conditions of the former two aquifers is long and varies between 8000 and 10,000 years. The Malia aquifer on the other hand, has a freshening time of 15 years. Freshening time was shown to depend mainly on cation exchange capacities and the recharge rate of the aquifers.

  5. Brine migration resulting from CO2 injection into saline aquifers – An approach to risk estimation including various levels of uncertainty

    DEFF Research Database (Denmark)

    Walter, Lena; Binning, Philip John; Oladyshkin, Sergey

    2012-01-01

    resulting from displaced brine. Quantifying risk on the basis of numerical simulations requires consideration of different kinds of uncertainties and this study considers both, scenario uncertainty and statistical uncertainty. Addressing scenario uncertainty involves expert opinion on relevant geological......Comprehensive risk assessment is a major task for large-scale projects such as geological storage of CO2. Basic hazards are damage to the integrity of caprocks, leakage of CO2, or reduction of groundwater quality due to intrusion of fluids. This study focuses on salinization of freshwater aquifers...... for large-scale 3D models including complex physics. Therefore, we apply a model reduction based on arbitrary polynomial chaos expansion combined with probabilistic collocation method. It is shown that, dependent on data availability, both types of uncertainty can be equally significant. The presented study...

  6. Deposition, persistence and turnover of pollutants: first results from the EU project AquaTerra for selected river basins and aquifers

    DEFF Research Database (Denmark)

    Barth, J.A.C.; Steidle, D.; Kuntz, D.

    2007-01-01

    in laboratory studies with soils and aquifer material from selected sites. For sediment transport of contaminants, new flood sampling techniques revealed highest deposition rates of beta-hexachlorocyclohexane (beta-HCH) in river sediments at hotspot areas on the Mulde River in the Bitterfeld region (Elbe Basin...... that range from biogeochemistry, environmental engineering, computer modelling and chemistry to socio-economic sciences. Field study areas are the river basins of the Ebro, the Meuse, the Elbe and the Danube as well as the 3-km(2) French catchment of the Brevilles Spring. Within the first 2 years...... of the project more than 1700 samples of atmospherically deposited particles, sediments, and water have been collected in the above-mentioned systems. Results show clear spatial patterns of deposition of polyaromatic hydrocarbons (PAHs) with the highest rates in the Meuse Basin. For local inputs...

  7. Geochemical Constraints for Mercury's PCA-Derived Geochemical Terranes

    Science.gov (United States)

    Stockstill-Cahill, K. R.; Peplowski, P. N.

    2018-05-01

    PCA-derived geochemical terranes provide a robust, analytical means of defining these terranes using strictly geochemical inputs. Using the end members derived in this way, we are able to assess the geochemical implications for Mercury.

  8. Multivariate analysis of the heterogeneous geochemical processes controlling arsenic enrichment in a shallow groundwater system.

    Science.gov (United States)

    Huang, Shuangbing; Liu, Changrong; Wang, Yanxin; Zhan, Hongbin

    2014-01-01

    The effects of various geochemical processes on arsenic enrichment in a high-arsenic aquifer at Jianghan Plain in Central China were investigated using multivariate models developed from combined adaptive neuro-fuzzy inference system (ANFIS) and multiple linear regression (MLR). The results indicated that the optimum variable group for the AFNIS model consisted of bicarbonate, ammonium, phosphorus, iron, manganese, fluorescence index, pH, and siderite saturation. These data suggest that reductive dissolution of iron/manganese oxides, phosphate-competitive adsorption, pH-dependent desorption, and siderite precipitation could integrally affect arsenic concentration. Analysis of the MLR models indicated that reductive dissolution of iron(III) was primarily responsible for arsenic mobilization in groundwaters with low arsenic concentration. By contrast, for groundwaters with high arsenic concentration (i.e., > 170 μg/L), reductive dissolution of iron oxides approached a dynamic equilibrium. The desorption effects from phosphate-competitive adsorption and the increase in pH exhibited arsenic enrichment superior to that caused by iron(III) reductive dissolution as the groundwater chemistry evolved. The inhibition effect of siderite precipitation on arsenic mobilization was expected to exist in groundwater that was highly saturated with siderite. The results suggest an evolutionary dominance of specific geochemical process over other factors controlling arsenic concentration, which presented a heterogeneous distribution in aquifers. Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of Environmental Science and Health, Part A, to view the supplemental file.

  9. Assessment of Drywells as Effective Tools for Stormwater Management and Aquifer Recharge: Results of a Two-Year Field and Numerical Modeling Study

    Science.gov (United States)

    Edwards, E.; Washburn, B.; Harter, T.; Fogg, G. E.; Nelson, C.; Lock, B.; Li, X.

    2016-12-01

    Drywells are gravity-fed, excavated pits with perforated casings used to facilitate stormwater infiltration and groundwater recharge in areas with low permeability soils or cover. Stormwater runoff that would otherwise be routed to streams or drains in urban areas can be used as a source of aquifer recharge, potentially mitigating the effects of drought and harm to natural water bodies. However, the potential for groundwater contamination caused by urban runoff bypassing surface soil and near surface sediment attenuation processes has prevented more widespread use of drywells as a recharge mechanism. A field study was conducted in Elk Grove, CA, to determine the effects of drywell-induced stormwater infiltration on the local hydrogeologic system. Two drywells 13.5 meters in depth were constructed for the project: one in a preexisting drainage basin fed by residential lots, and one at an industrial site. Both sites were outfitted with vegetated pretreatments, and upgradient and downgradient groundwater monitoring wells. Site stormwater and groundwater were sampled between November, 2014, and May, 2016, and analyzed for contaminants. Results of water quality sampling have been statistically analyzed for trends and used to determine the contaminants of interest and the concentrations of these contaminants in influent stormwater. The fate and transport of these contaminants have been simulated using a 1D variably saturated flow and transport model and site specific parameters to predict long-term effects of stormwater infiltration on the surrounding hydrogeologic system. The potential for remobilization of geogenic heavy metals from changes in subsurface hydrochemistry caused by drywell infiltration have also been assessed. The results of the field study and numerical modeling assessment indicate that the study's drywells do not pose a long-term threat to groundwater quality and may be an effective source of aquifer recharge and tool for urban stormwater management.

  10. Appliance of geochemical engineering in radioactive waste disposal

    International Nuclear Information System (INIS)

    Li Shuang; Zhang Chengjiang; Ni Shijun; Li Kuanliang

    2008-01-01

    The basic foundation of applying geochemical engineering to control environment, common engineering models of disposal radioactive waste and the functions of the engineering barriers are introduced in this paper. The authors take the geochemical engineering barrier materiel research of a radioactive waste repository as an example to explain the appliance of geochemical engineering in the disposal of radioactive waste. And the results show that it can enhance the security of the nuclear waste repository if we use geochemical engineering barrier. (authors)

  11. New results for Palaeozoic volcanic phases in the Prague Basin – magnetic and geochemical studies of Lištice, Czech Republic

    Directory of Open Access Journals (Sweden)

    Tiiu Elbra

    2015-02-01

    Full Text Available Palaeo-, rock magnetic and geochemical studies were conducted on volcanic samples from the Lištice area to improve the knowledge of Palaeozoic volcanic evolution in the Prague Basin. The magnetic data display no significant differences between two studied localities, indicating one magnetizing event for both localities. Geochemical data suggest that Lištice basalt could have originated from deep melting of the garnet peridotite mantle source during the attenuation and rifting of the continental lithosphere connected with asthenospheric mantle upwelling. The dataset furthermore supports the evidence of syn- or post-intrusive fluid interactions and low-temperature stages of alteration. The Ti-magnetite within amygdales of the samples was found to be carrying the characteristic remanent magnetization and reflects probably the Permo-Carboniferous remagnetization of volcanic phases.

  12. Raw material variability as archaeological tools: Preliminary results from a geochemical study of the basalt vessel workshop at Iron Age Tel Hazor, Israel

    Directory of Open Access Journals (Sweden)

    Tatjana Gluhak

    2016-10-01

    Full Text Available The discovery of a basalt vessel workshop at Tel Hazor, one of the most important Iron Age sites in the Near East, marks a turning point in our understanding of stone artifact production and distribution during the1st millennium BCE. It offers a rare opportunity to characterize ancient raw material sources, production sites, and study production, trade and distribution systems. The basalt vessel workshop, the only one of its kind in the Levant, produced large quantities of bowl preforms and production waste. To better understand the production and distribution systems behind this specialized production center, in 2011 we initiated a focused geochemical project that concentrated on the products of this unique workshop.  We measured the major and trace element composition of 44 unfinished basalt vessels from the workshop and other contexts at Hazor, and can demonstrate that the majority of these objects were derived from one specific, geochemically well-constrained, basaltic rock source. Only a few bowls clearly deviate from this geochemical composition and were produced using raw material from other sources. Thus, we believe that one major quarry existed that supplied the Hazor workshop with the majority of the basaltic raw material. The products from this specific extraction site provide us with a “Hazor reference group” that can be used to test whether or not finished vessels from Hazor and contemporary sites were produced in the Hazor workshop.

  13. Geochemical exploration for uranium

    International Nuclear Information System (INIS)

    1988-01-01

    This Technical Report is designed mainly to introduce the methods and techniques of uranium geochemical exploration to exploration geologists who may not have had experience with geochemical exploration methods in their uranium programmes. The methods presented have been widely used in the uranium exploration industry for more than two decades. The intention has not been to produce an exhaustive, detailed manual, although detailed instructions are given for a field and laboratory data recording scheme and a satisfactory analytical method for the geochemical determination of uranium. Rather, the intention has been to introduce the concepts and methods of uranium exploration geochemistry in sufficient detail to guide the user in their effective use. Readers are advised to consult general references on geochemical exploration to increase their understanding of geochemical techniques for uranium

  14. Hydrogeophysics and geochemistry reveal heterogeneity and water quality improvements in aquifer recharge and recovery (ARR) (Invited)

    Science.gov (United States)

    Parsekian, A.; Regnery, J.; Wing, A.; Knight, R. J.; Drewes, J. E.

    2013-12-01

    Aquifer recharge and recover (ARR) is the process of infiltrating water into the ground for storage and withdrawal through wells at a later time. Two significant challenges faced during the design of ARR systems are 1) evaluating aquifer heterogeneity and 2) understanding the rock fluid interactions; these knowledge gaps may have profound impacts on the volume of recoverable water and the improvement in water quality in comparison with the source-water. Our objective in this research is to leverage the advantages of hydrogeophysical measurements and geochemical sampling to reveal the properties of an aquifer through which ARR water travels with the goal of informing current operations and future design decisions. Combined geophysical and geochemical investigations reveal subsurface heterogeneity, indicate possible flow paths though the aquifer and quantify specific reductions in contaminant concentrations. Ground penetrating radar (GPR), electromagnetic induction (EMI) and electrical resistivity tomography (ERT) were used to image the subsurface throughout two key infiltration/extraction areas of an ARR site in Colorado, USA. The most valuable results came from 2.5D ERT revealing the structural patterns and suggesting the distribution of textural composition of unconsolidated sediments. Geochemical measurements on transects intersecting the geophysical measurements resolved bulk parameters (i.e. total organic carbon, cations, anions) and trace organic contaminants (e.g. trace organic compounds) and were also used to estimate mixing and water travel times and assess the performance of the ARR site regarding water quality and quantity. Our results indicate that the subsurface is highly heterogeneous at our study site and that the coarse-grained sedimentary units, acting as the best conduit for transporting water, are likely discontinuous. The electrical resistivity measurements indicate certain areas of the infiltration basins may have good hydraulic connections to

  15. Detailed geochemical survey for east-central Minnesota, geology and geochemistry of selected uranium targets

    International Nuclear Information System (INIS)

    Morey, G.B.; Lively, R.S.

    1980-01-01

    Results of a detailed geochemical survey of approximately 6820 km 2 in parts of Aitkin, Carlton, Kanabec, and Pine Counties, east-central Minnesota are reported. Geochemical data are presented for 883 groundwater samples and 200 bedrock samples. Although all of the groundwaters in the study area have similar major-element concentrations and therefore presumably a common ancestry, small differences in the minor-element concentrations serve to characterize various aquifers, both in the Quaternary deposits and in the bedrock. All of the aquifers locally yield waters having statistically anomalous concentrations of uranium or radon, but these anomalies are spatially coincident only in a few places and particularly in three geologic environments considered favorable for uranium mineralization. These include the following: (1) Thomson Formation near the unconformably overlying Fond du Lac Formation, (2) Hinckley Sandstone near a major fault system, and (3) Denham Formation near the unconformity with the McGrath Gneiss, particularly where these rocks are faulted and overlain by the Fond du Lac Formation. One additional uranium environment characterized by thin laminae of uraniferous apatite was located in the Thomson Formation during outcrop reconnaissance and sampling. The coincidence of this and other anomalously high uranium values in the bedrock with specific uranium and radon anomalies in the groundwater confirms the usefulness of the hydrogeochemical data to uranium exploration in this glaciated terrane

  16. Numerical simulation of CO2 disposal by mineral trapping in deep aquifers

    International Nuclear Information System (INIS)

    Xu Tianfu; Apps, John A.; Pruess, Karsten

    2004-01-01

    Carbon dioxide disposal into deep aquifers is a potential means whereby atmospheric emissions of greenhouse gases may be reduced. However, our knowledge of the geohydrology, geochemistry, geophysics, and geomechanics of CO 2 disposal must be refined if this technology is to be implemented safely, efficiently, and predictably. As a prelude to a fully coupled treatment of physical and chemical effects of CO 2 injection, the authors have analyzed the impact of CO 2 immobilization through carbonate mineral precipitation. Batch reaction modeling of the geochemical evolution of 3 different aquifer mineral compositions in the presence of CO 2 at high pressure were performed. The modeling considered the following important factors affecting CO 2 sequestration: (1) the kinetics of chemical interactions between the host rock minerals and the aqueous phase, (2) CO 2 solubility dependence on pressure, temperature and salinity of the system, and (3) redox processes that could be important in deep subsurface environments. The geochemical evolution under CO 2 injection conditions was evaluated. In addition, changes in porosity were monitored during the simulations. Results indicate that CO 2 sequestration by matrix minerals varies considerably with rock type. Under favorable conditions the amount of CO 2 that may be sequestered by precipitation of secondary carbonates is comparable with and can be larger than the effect of CO 2 dissolution in pore waters. The precipitation of ankerite and siderite is sensitive to the rate of reduction of Fe(III) mineral precursors such as goethite or glauconite. The accumulation of carbonates in the rock matrix leads to a considerable decrease in porosity. This in turn adversely affects permeability and fluid flow in the aquifer. The numerical experiments described here provide useful insight into sequestration mechanisms, and their controlling geochemical conditions and parameters

  17. Basement and alluvial aquifers of Malawi: An overview of ...

    African Journals Online (AJOL)

    Elizabeth B Mapoma

    2014-02-17

    Feb 17, 2014 ... Rowland HAL, Gault AG, Lythgoe P, Polya DA (2008) Geochemistry of aquifer sediments and arsenic-rich groundwaters from Kandal. Province, Cambodia. Appl. Geochem. 23: 3029–3046. Sajidu SM, Masumbu FFF, Fabiano E, Ngongondo C (2007). Drinking water quality and identification of fluoritic areas ...

  18. Hydrogeochemical and isotopic investigation and water quality assessment of groundwater in the Sisseb El Alem Nadhour Saouaf aquifer (SANS), northeastern Tunisia

    Science.gov (United States)

    Hamdi, Mohamed; Zagrarni, Mohamed Faouzi; Jerbi, Hamza; Tarhouni, Jamila

    2018-05-01

    In the Sisseb El Alem Nadhour Saouaf basin (SANS), as in all other arid regions, surface water is scarce and groundwater is the greatest most important source of water for all uses. This study aims to identify the processes governing groundwater mineralization in order to assess the suitability of the groundwater for drinking and agriculture purposes. This research used a geodatabase which includes information on hydrogeology, geochemistry, land cover, and geology. We identified the most important factors involved in the deterioration of water quality, including anhydrite and gypsum dissolution, silicate weathering, downward leakage between aquifers, evaporation, groundwater over-exploitation, and the overuse of fertilizers. Furthermore, the two following important factors were identified: the intrusion of Sebkhat El Kelbia and the vertical flow from the deep aquifer. Results were used to develop a conceptual geochemical model, wherein three geochemical regions were differentiated. Statistical techniques, such as Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were used to confirm the water affinities and the presence of three different geochemical regions. The water quality index (WQI), Wilcox and Richards's diagrams were performed to assess the suitability of groundwater to drinking and irrigation purposes. These indexes confirm the fact that the groundwater of this aquifer is not suitable for irrigation, neither for drinking. Furthermore, 18O and deuterium isotope data indicate the importance of evaporation in the basin, and the recharge with modern rainfall.

  19. Electrical Conductivity Model of the Mantle Lithosphere of the Slave Craton (NW Canada) and its tectonic interpretation in the context of Geochemical Results

    Science.gov (United States)

    Lezaeta, P.; Chave, A.; Evans, R.; Jones, A. G.; Ferguson, I.

    2002-12-01

    The Slave Craton, northwestern Canada, contains the oldest known rocks on Earth, with exposed outcrop over an area of about 600x400 km2. The discovery of economic diamondiferous kimberlite pipes during the early 1990s motivated extensive research in the region. Over the last six years, four types of deep-probing magnetotelluric (MT) surveys were conducted within the framework of diverse geoscientific programs, aimed at determining the regional-scale electrical structures of the craton. Two of the surveys involved novel acquisition; one through frozen lake ice along ice roads during winter, and the second deploying ocean-bottom instrumentation from float planes during summer. The latter surveys required one year of recording between summers, thus allowing long period transfer functions that lead to mantle penetration depths of over 300 km. Two-dimensional modeling of the MT data from along the winter road showed the existence of a high conductivity zone at depths of 80-120 km beneath the central Slave craton. This anomalous region is spatially coincident with an ultradepleted harzburgitic layer in the upper mantle that was interpreted by others to be related to a subducted slab emplaced during the mid-Archean. A 3-D electrical conductivity model of the Slave lithosphere has been obtained, by trial and error, to fit the magnetic transfer and MT response functions from the lake experiments. This 3-D model traces the central Slave conductor as a NE-SW oriented mantle structure. Its NE-SW orientation coincides with that of a late fold belt system, with the first phase of craton-wide plutonism at ca 2630-2590 Ma, three-part subdivision of the craton based on SKS results, and with a G10 (garnet) geochemical mantle boundaries. All of these highlight a NE-SW structural grain to the lithospheric mantle of the craton, in sharp contrast to the N-S grain of the crust. Constraints on the depth range and lateral extension of the electrical conductive structure are obtained

  20. Geochemical and hydrologic controls on the mobilization of arsenic derived from herbicide application

    International Nuclear Information System (INIS)

    Fitzmaurice, Arthur G.; Bilgin, A. Azra; O'Day, Peggy A.; Illera, Virginia; Burris, David R.; Reisinger, H. James; Hering, Janet G.

    2009-01-01

    The fate and transport of As was examined at an industrial site where soil- and groundwater contamination are derived from the application of As 2 O 3 as a herbicide. Application of arsenical herbicides was discontinued in the 1970s and soils in the source area were partially excavated in 2003. Arsenic contamination (up to 280 mg/kg) remains in the source area soils and a plume of As-contaminated groundwater persists in the surficial aquifer downgradient of the source area with maximum observed As concentrations of 1200 μg/L near the source area. The spatial extent of As contamination as defined by the 10 μg/L contour appears to have remained relatively stable over the period 1996-2006; the boundary of the 1000 μg/L contour has retreated over the same time period indicating a decrease in total As mass in the surficial groundwater. In column experiments conducted with source area soil, the As concentrations in the column effluent were comparable to those observed in groundwater near the source area. A substantial fraction of the As could be leached from the source area soil with ammonium sulfate and ammonium phosphate. Exhaustive extraction with background groundwater removed most of the total As. These results indicate that As in the source area soils is geochemically labile. Source area soils are low in extractable Fe, Mn and Al, and characterization by X-ray absorption spectroscopy and electron microscopy indicated that As is present primarily as arsenate sorbed to (alumino)silicate minerals. Batch sorption experiments showed much less sorption on surficial aquifer sediments than on sediments from the Jackson Bluff Formation (JBF), a presumed confining layer. This limited capacity of the surficial aquifer sediments for As sorption is consistent with the similar As contents observed for these sediments within and upgradient of the As plume. The apparent stability of the As plume cannot be explained by sequestration of As within the surficial aquifer. Sorption

  1. Arsenic mobilization in an oxidizing alkaline groundwater: Experimental studies, comparison and optimization of geochemical modeling parameters

    International Nuclear Information System (INIS)

    Hafeznezami, Saeedreza; Lam, Jacquelyn R.; Xiang, Yang; Reynolds, Matthew D.; Davis, James A.; Lin, Tiffany; Jay, Jennifer A.

    2016-01-01

    Arsenic (As) mobilization and contamination of groundwater affects millions of people worldwide. Progress in developing effective in-situ remediation schemes requires the incorporation of data from laboratory experiments and field samples into calibrated geochemical models. In an oxidizing aquifer where leaching of high pH industrial waste from unlined surface impoundments led to mobilization of naturally occurring As up to 2 mg L −1 , sequential extractions of solid phase As as well as, batch sediment microcosm experiments were conducted to understand As partitioning and solid-phase sorptive and buffering capacity. These data were combined with field data to create a series of geochemical models of the system with modeling programs PHREEQC and FITEQL. Different surface complexation modeling approaches, including component additivity (CA), generalized composite (GC), and a hybrid method were developed, compared and fitted to data from batch acidification experiments to simulate potential remediation scenarios. Several parameters strongly influence the concentration of dissolved As including pH, presence of competing ions (particularly phosphate) and the number of available sorption sites on the aquifer solids. Lowering the pH of groundwater to 7 was found to have a variable, but limited impact (<63%) on decreasing the concentration of dissolved As. The models indicate that in addition to lowering pH, decreasing the concentration of dissolved phosphate and/or increasing the number of available sorption sites could significantly decrease the As solubility to levels below 10 μg L −1 . The hybrid and GC modeling results fit the experimental data well (NRMSE<10%) with reasonable effort and can be implemented in further studies for validation. - Highlights: • Samples were collected from an oxidizing aquifer where high pH waste has led to mobilization of naturally occurring As. • Three surface complexation modeling approaches were used in modeling adsorption

  2. Hydrogeological study of the aquifer system of the northern Sahara in the Algero-Tunisian border: A case study of Oued Souf region

    Science.gov (United States)

    Halassa, Younes; Zeddouri, Aziez; Mouhamadou, Ould Babasy; Kechiched, Rabah; Benhamida, Abdeldjebbar Slimane

    2018-05-01

    The aquifer system in The Algero-Tunisian border and Chotts region is mainly composed of two aquifers: The first is the Complex Terminal (CT) and the second is the Intercalary aquifer (CI). This study aims the identification and spatial evolution of factors that controlling the water quality in the Complex Terminal aquifer (CT) in the Chotts region (Oued Souf region - Southeastern of Algeria). The concentration of major elements, temperature, pH and salinity were monitored during 2015 in 34 wells from the CT aquifer. The geological, geophysical, hydrogeological and hydrochemical methods were applied in order to carried out a model for the investigated aquifer system and to characterize the hydrogeological and the geochemical behavior, as well as the geometrical and the lithological configuration. Multivariate statistical analyses such as Principal Component Analysis (PCA) were also used for the treatment of several data. Results show that the salinity follows the same regional distribution of Chloride, Sodium, Magnesium, Sulfate and Calcium. Note that the salinity shows low contents in the upstream part of investigated region suggesting restricted dissolution of salts. Hydro-chemical study and saturation indexes highlight the dominance of the dissolution and the precipitation of calcite, dolomite, anhydrite, gypsum and halite. The PCA analysis indicates that Na+, Cl-, Ca2+, Mg2+, SO42- and K+ variables that influence the water mineralization.

  3. Determining origin of underground water in coal mines by means of natural isotopes and other geochemical parameters

    Energy Technology Data Exchange (ETDEWEB)

    Dolenec, T; Pezdic, J; Herlec, U; Kuscer, D; Mitrevski, G [Institut Josef Stefan, Ljubljana (Yugoslavia)

    1989-07-01

    Presents a preliminary report on origin of water in Slovenian brown coal mines. Water, coal and strata samples from the Hrastnik and Ojstro mines were analyzed for changes in chemical composition. Water samples were also analyzed for changes in isotopic composition and inorganic carbon and sulfur contents. Chemical, isotopic and geochemical techniques are described and results are presented with 21 diagrams. An attempt is made to explain the origin and age of water flowing from mine aquifers into mine rooms, and to explain the interdependence of surface and underground water flow. 10 refs.

  4. Using geochemical indicators to distinguish high biogeochemical activity in floodplain soils and sediments

    Energy Technology Data Exchange (ETDEWEB)

    Kenwell, Amy [Hydrologic Sciences and Engineering Program, Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); Navarre-Sitchler, Alexis, E-mail: asitchle@mines.edu [Hydrologic Sciences and Engineering Program, Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); Prugue, Rodrigo [Hydrologic Sciences and Engineering Program, Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); Spear, John R. [Department of Civil and Environmental Engineering, Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); Hering, Amanda S. [Department of Applied Mathematics and Statistics, Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); Maxwell, Reed M. [Hydrologic Sciences and Engineering Program, Colorado School of Mines, 1500 Illinois St., Golden, CO 80401 (United States); Carroll, Rosemary W.H. [Desert Research Institute, Division of Hydrologic Sciences, 2215 Raggio Parkway, Reno, NV 89512 (United States); Williams, Kenneth H. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2016-09-01

    A better understanding of how microbial communities interact with their surroundings in physically and chemically heterogeneous subsurface environments will lead to improved quantification of biogeochemical reactions and associated nutrient cycling. This study develops a methodology to predict potential elevated rates of biogeochemical activity (microbial “hotspots”) in subsurface environments by correlating microbial DNA and aspects of the community structure with the spatial distribution of geochemical indicators in subsurface sediments. Multiple linear regression models of simulated precipitation leachate, HCl and hydroxylamine extractable iron and manganese, total organic carbon (TOC), and microbial community structure were used to identify sample characteristics indicative of biogeochemical hotspots within fluvially-derived aquifer sediments and overlying soils. The method has been applied to (a) alluvial materials collected at a former uranium mill site near Rifle, Colorado and (b) relatively undisturbed floodplain deposits (soils and sediments) collected along the East River near Crested Butte, Colorado. At Rifle, 16 alluvial samples were taken from 8 sediment cores, and at the East River, 46 soil/sediment samples were collected across and perpendicular to 3 active meanders and an oxbow meander. Regression models using TOC and TOC combined with extractable iron and manganese results were determined to be the best fitting statistical models of microbial DNA (via 16S rRNA gene analysis). Fitting these models to observations in both contaminated and natural floodplain deposits, and their associated alluvial aquifers, demonstrates the broad applicability of the geochemical indicator based approach. - Highlights: • Biogeochemical characterization of alluvial floodplain soils and sediments was performed to investigate parameters that may indicate microbial hot spot formation. • A correlation between geochemical parameters (total organic carbon and

  5. Using geochemical indicators to distinguish high biogeochemical activity in floodplain soils and sediments

    International Nuclear Information System (INIS)

    Kenwell, Amy; Navarre-Sitchler, Alexis; Prugue, Rodrigo; Spear, John R.; Hering, Amanda S.; Maxwell, Reed M.; Carroll, Rosemary W.H.; Williams, Kenneth H.

    2016-01-01

    A better understanding of how microbial communities interact with their surroundings in physically and chemically heterogeneous subsurface environments will lead to improved quantification of biogeochemical reactions and associated nutrient cycling. This study develops a methodology to predict potential elevated rates of biogeochemical activity (microbial “hotspots”) in subsurface environments by correlating microbial DNA and aspects of the community structure with the spatial distribution of geochemical indicators in subsurface sediments. Multiple linear regression models of simulated precipitation leachate, HCl and hydroxylamine extractable iron and manganese, total organic carbon (TOC), and microbial community structure were used to identify sample characteristics indicative of biogeochemical hotspots within fluvially-derived aquifer sediments and overlying soils. The method has been applied to (a) alluvial materials collected at a former uranium mill site near Rifle, Colorado and (b) relatively undisturbed floodplain deposits (soils and sediments) collected along the East River near Crested Butte, Colorado. At Rifle, 16 alluvial samples were taken from 8 sediment cores, and at the East River, 46 soil/sediment samples were collected across and perpendicular to 3 active meanders and an oxbow meander. Regression models using TOC and TOC combined with extractable iron and manganese results were determined to be the best fitting statistical models of microbial DNA (via 16S rRNA gene analysis). Fitting these models to observations in both contaminated and natural floodplain deposits, and their associated alluvial aquifers, demonstrates the broad applicability of the geochemical indicator based approach. - Highlights: • Biogeochemical characterization of alluvial floodplain soils and sediments was performed to investigate parameters that may indicate microbial hot spot formation. • A correlation between geochemical parameters (total organic carbon and

  6. Geochemical and isotopic determination of deep groundwater contributions and salinity to the shallow groundwater and surface water systems, Mesilla Basin, New Mexico, Texas, and Mexico

    Science.gov (United States)

    Robertson, A.; Carroll, K. C.; Kubicki, C.; Purtshert, R.

    2017-12-01

    The Mesilla Basin/Conejos-Médanos aquifer system, extending from southern New Mexico to Chihuahua, Mexico, is a priority transboundary aquifer under the 2006 United States­-Mexico Transboundary Aquifer Assessment Act. Declining water levels, deteriorating water quality, and increasing groundwater use by municipal, industrial, and agricultural users on both sides of the international border raise concerns about long-term aquifer sustainability. Relative contributions of present-day and "paleo" recharge to sustainable fresh groundwater yields has not been determined and evidence suggests that a large source of salinity at the distal end of the Mesilla Basin is saline discharge from deep groundwater flow. The magnitude and distribution of those deep saline flow paths are not determined. The contribution of deep groundwater to discharge and salinity in the shallow groundwater and surface water of the Mesilla Basin will be determined by collecting discrete groundwater samples and analyzing for aqueous geochemical and isotopic tracers, as well as the radioisotopes of argon and krypton. Analytes include major ions, trace elements, the stable isotopes of water, strontium and boron isotopes, uranium isotopes, the carbon isotopes of dissolved inorganic carbon, noble gas concentrations and helium isotope ratios. Dissolved gases are extracted and captured from groundwater wells using membrane contactors in a process known as ultra-trace sampling. Gas samples are analyzed for radioisotope ratios of krypton by the ATTA method and argon by low-level counting. Effectiveness of the ultra-trace sampling device and method was evaluated by comparing results of tritium concentrations to the krypton-85 content. Good agreement between the analyses, especially in samples with undetectable tritium, indicates that the ultra-trace procedure is effective and confirms that introduction of atmospheric air has not occurred. The geochemistry data indicate a complex system of geochemical

  7. Mobilization of arsenic and other naturally occurring contaminants in groundwater of the Main Ethiopian Rift aquifers.

    Science.gov (United States)

    Rango, Tewodros; Vengosh, Avner; Dwyer, Gary; Bianchini, Gianluca

    2013-10-01

    This study investigates the mechanisms of arsenic (As) and other naturally occurring contaminants (F(-), U, V, B, and Mo) mobilization from Quaternary sedimentary aquifers of the Main Ethiopian Rift (MER) and their enrichment in the local groundwater. The study is based on systematic measurements of major and trace elements as well as stable oxygen and hydrogen isotopes in groundwater, coupled with geochemical and mineralogical analyses of the aquifer rocks. The Rift Valley aquifer is composed of rhyolitic volcanics and Quaternary lacustrine sediments. X-ray fluorescence (XRF) results revealed that MER rhyolites (ash, tuff, pumice and ignimbrite) and sediments contain on average 72 wt. % and 65 wt. % SiO2, respectively. Petrographic studies of the rhyolites indicate predominance of volcanic glass, sanidine, pyroxene, Fe-oxides and plagioclase. The As content in the lacustrine sediments (mean = 6.6 mg/kg) was higher than that of the rhyolites (mean: 2.5 mg/kg). The lacustrine aquifers of the Ziway-Shala basin in the northern part of MER were identified as high As risk zones, where mean As concentration in groundwater was 22.4 ± 33.5 (range of 0.60-190 μg/L) and 54% of samples had As above the WHO drinking water guideline value of 10 μg/L. Field As speciation measurements showed that most of the groundwater samples contain predominantly (~80%) arsenate-As(V) over arsenite-As(III) species. The As speciation together with field data of redox potential (mean Eh = +73 ± 65 mV) and dissolved-O2 (6.6 ± 2.2 mg/L) suggest that the aquifer is predominantly oxidative. Water-rock interactions, including the dissolution of volcanic glass produces groundwater with near-neutral to alkaline pH (range 6.9-8.9), predominance of Na-HCO3 ions, and high concentration of SiO2 (mean: 85.8 ± 11.3 mg/L). The groundwater data show high positive correlation of As with Na, HCO3, U, B, V, and Mo (R(2) > 0.5; p groundwater indicates that Fe-oxides and oxyhydroxides minerals were saturated

  8. Reconnaissance Geochemical Study

    African Journals Online (AJOL)

    distribution patterns. The geochemical distribution maps of the elements reveal that Cu, Pb, Zn, Co, Sc, Ni, Cr, .... After filtration, the leached solutions were diluted with ultra ...... some other rare earth elements in the study area. The occurrence ...

  9. Modeling carbon dioxide sequestration in saline aquifers: Significance of elevated pressures and salinities

    International Nuclear Information System (INIS)

    Allen, D.E.; Strazisar, B.R.; Soong, Y.; Hedges, S.W.

    2005-01-01

    The ultimate capacity of saline formations to sequester carbon dioxide by solubility and mineral trapping must be determined by simulating sequestration with geochemical models. These models, however, are only as reliable as the data and reaction scheme on which they are based. Several models have been used to make estimates of carbon dioxide solubility and mineral formation as a function of pressure and fluid composition. Intercomparison of modeling results indicates that failure to adjust all equilibrium constants to account for elevated carbon dioxide pressures results in significant errors in both solubility and mineral formation estimates. Absence of experimental data at high carbon dioxide pressures and high salinities make verification of model results difficult. Results indicate standalone solubility models that do not take mineral reactions into account will underestimate the total capacity of aquifers to sequester carbon dioxide in the long term through enhanced solubility and mineral trapping mechanisms. Overall, it is difficult to confidently predict the ultimate sequestration capacity of deep saline aquifers using geochemical models. (author)

  10. Control of As and Ni releases from a uranium mill tailings neutralization circuit: Solution chemistry, mineralogy and geochemical modeling of laboratory study results

    Energy Technology Data Exchange (ETDEWEB)

    Mahoney, John [MWH Americas, Inc., 1801 California Street, Denver, CO 80202 (United States)], E-mail: john.j.mahoney@mwhglobal.com; Slaughter, Maynard [Earth Science, University of Northern Colorado, Greeley, CO 80639 (United States); Langmuir, Donald [Hydrochem Systems Corp., P.O. Box 23257, Silverthorne, CO 80498 (United States); Rowson, John [AREVA Resources Canada Inc., P.O. Box 9204, Saskatoon, SK, S7K 3X5 (Canada)

    2007-12-15

    Processing U ores in the JEB Mill of the McClean Lake Operation in northern Saskatchewan produces spent leaching solutions (raffinates) with pH {<=} 1.5, and As and Ni concentrations up to 6800 and 5200 mg L{sup -1}, respectively. Bench-scale neutralization experiments (pH 2-8) were performed to help optimize the design of mill processes for reducing As and Ni concentrations in tailings and raffinates to {<=}1 mg L{sup -1} prior to their disposal. Precipitate mineralogy determined by chemical analysis, XRD, SEM, EM, XM and EXAFS methods, included gypsum (the dominant precipitate), poorly crystalline scorodite (precipitated esp. from pH 2-4), annabergite, hydrobasaluminite, ferrihydrite, green rust II and theophrastite. The As was mostly in scorodite with smaller amounts in annabergite and trace As adsorbed and/or co-precipitated, probably by ferrihydrite. Geochemical modeling indicated that above pH 2, the ion activity product (IAP) of scorodite lies between the solubility products of amorphous and crystalline phases (log K{sub sp} = -23.0 and -25.83, respectively). The IAP decreases with increasing pH, suggesting that the crystallinity of the scorodite increases with pH. Forward geochemical models support the assumption that during neutralization, particles of added base produce sharp local pH gradients and disequilibrium with bulk solutions, facilitating annabergite and theophrastite precipitation.

  11. Monitoring active volcanoes: The geochemical approach

    Directory of Open Access Journals (Sweden)

    Takeshi Ohba

    2011-06-01

    Full Text Available

    The geochemical surveillance of an active volcano aims to recognize possible signals that are related to changes in volcanic activity. Indeed, as a consequence of the magma rising inside the volcanic "plumbing system" and/or the refilling with new batches of magma, the dissolved volatiles in the magma are progressively released as a function of their relative solubilities. When approaching the surface, these fluids that are discharged during magma degassing can interact with shallow aquifers and/or can be released along the main volcano-tectonic structures. Under these conditions, the following main degassing processes represent strategic sites to be monitored.

    The main purpose of this special volume is to collect papers that cover a wide range of topics in volcanic fluid geochemistry, which include geochemical characterization and geochemical monitoring of active volcanoes using different techniques and at different sites. Moreover, part of this volume has been dedicated to the new geochemistry tools.

  12. Hydrogeochemical impact of CO{sub 2} leakage from geological sequestration on shallow potable aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Cahill, A.G.

    2013-09-15

    Over the past 10 years scientists have worked in earnest to understand the potential effects of leakage in order that an informed decision on CCGS implementation can be made. This research can be broadly described as aiming to answer two key questions; how deleterious is leakage of CCGS to groundwater resources? and can it be detected geochemically? Some common hydrochemical development is apparent from the literature however many aspects of hydrogeological and hydrogeochemical impact of leakage into shallow aquifers used in water supply remain unclear. In this Ph.D. study an integrated approach was employed in order to answer the two key questions regarding leakage of CO{sub 2} into shallow aquifers. Consequently a combination of laboratory and field investigations were conducted supported by numerical geochemical modeling in order to identify, constrain and quantify processes controlling groundwater chemistry evolution. The output is 4 journal articles and 3 technical reports. In paper I and technical report I simple batch reactors were employed coupled to comprehensive sediment characterization to determine the likely effects of CO{sub 2} on water chemistry in a range of shallow aquifers. Results showed aquifers can be broadly divided into three types; carbonate dominated, silicate dominated and mixed. Each aquifer type showed distinct water chemistry evolution thus inherent risks vary. These studies also highlighted the complexity of risk assessment and detection caused by the range of formation types potentially overlying storage reservoirs. Investigations described in Papers II, III and technical report II increase applicability to real leakage by observing in situ effects including groundwater flow. A silicate dominated shallow aquifer in Vroegum, western Denmark forms the focus of study upon which a series of investigations were conducted. The main field study involved injection of 1600 kg of gas phase CO{sub 2} into the shallow Vroegum aquifer over 72 days

  13. Arsenic Contamination in Groundwater of Bangladesh: Perspectives on Geochemical, Microbial and Anthropogenic Issues

    Directory of Open Access Journals (Sweden)

    Shafi M. Tareq

    2011-11-01

    Full Text Available A groundwater, sediment and soil chemistry and mineralogical study has been performed to investigate the sources and mobilization process of Arsenic (As in shallow aquifers of Bangladesh. The groundwater from the shallow aquifers is characterized by high concentrations of Arsenic (47.5–216.8 µg/L, iron (0.85–5.83 mg/L, and phosphate, along with high electrical conductivity (EC. The groundwater has both very low oxidation-reduction potential (Eh and dissolved oxygen (DO values indicating reducing conditions. By contrast, the deep aquifers and surface waters (pond, canal have very low concentrations of Arsenic ( < 6 µg/L, iron (0.12–0.39 mg/L, and phosphate along with a relatively low EC. Furthermore, the values of Eh and DO are high, indicating oxic to suboxic conditions. Arsenic is inversely correlated with Eh values in the upper aquifer, whereas no relationship in the deeper aquifer is observed. These results suggest that As mobilization is clearly linked to the development of reducing conditions. The clayey silt, enriched in Fe, Mn, Al oxides and organic matter, and deposited in the middle unit of shallow aquifers, contains moderately high concentrations of As, whereas the sediments of deep aquifers and silty mud surface soils from paddy fields and ponds contain a low content of As (Daudkandi area. Arsenic is strongly correlated with the concentrations of Fe, Mn and Al oxides in the core samples from the Daudkandi and Marua areas. Arsenic is present in the oxide phase of Fe and Mn, phyllosilicate minerals and in organic matter in sediments. This study suggests that adsorption or precipitation of As-rich Fe oxyhydroxide on the surface or inner sites of biotite might be responsible for As concentrations found in altered biotite minerals by Seddique et al. Microbially or geochemically mediated reductive dissolution of Fe oxyhydroxides is the main mechanism for As release. The reducing conditions are caused by respiratory decomposition of

  14. Fertilizers mobilization in alluvial aquifer: laboratory experiments

    Science.gov (United States)

    Mastrocicco, M.; Colombani, N.; Palpacelli, S.

    2009-02-01

    In alluvial plains, intensive farming with conspicuous use of agrochemicals, can cause land pollution and groundwater contamination. In central Po River plain, paleo-channels are important links between arable lands and the underlaying aquifer, since the latter is often confined by clay sediments that act as a barrier against contaminants migration. Therefore, paleo-channels are recharge zones of particular interest that have to be protected from pollution as they are commonly used for water supply. This paper focuses on fertilizer mobilization next to a sand pit excavated in a paleo-channel near Ferrara (Italy). The problem is approached via batch test leaking and columns elution of alluvial sediments. Results from batch experiments showed fast increase in all major cations and anions, suggesting equilibrium control of dissolution reactions, limited availability of solid phases and geochemical homogeneity of samples. In column experiments, early elution and tailing of all ions breakthrough was recorded due to preferential flow paths. For sediments investigated in this study, dispersion, dilution and chemical reactions can reduce fertilizers at concentration below drinking standards in a reasonable time frame, provided fertilizer loading is halted or, at least, reduced. Thus, the definition of a corridor along paleo-channels is recommended to preserve groundwater quality.

  15. Hydrological connectivity of perched aquifers and regional aquifers in semi-arid environments: a case study from Namibia

    Science.gov (United States)

    Hamutoko, J. T.; Wanke, H.

    2017-12-01

    Integrated isotopic and hydrological tracers along with standard hydrological data are used to understand complex dry land hydrological processes on different spatial and temporal scales. The objective of this study is to analyse the relationship between the perched aquifers and the regional aquifer using hydrochemical data and isotopic composition in the Cuvelai-Etosha Basin in Namibia. This relation between the aquifers will aid in understanding groundwater recharge processes and flow dynamics. Perched aquifers are discontinuous shallow aquifers with water level ranging from 0 to 30 meters below ground level. The regional aquifer occurs in semi-consolidated sandstone at depths between about 60 and 160 meters below ground level. Water samples were collected from both aquifers in 10 villages and were analysed for major ions and stable isotopes. The results show overlapping hydrochemistry and isotopic compositions of both aquifers in 8 villages which suggest the possibility of perched aquifer water infiltrating into the regional aquifer. In two villages the hydrochemistry and isotopic composition of the aquifers are totally different and this suggests that there is no interaction between this aquifers. Areas where perched aquifers are connected to regional aquifers maybe recharge zones. These finding have important implications for groundwater resource management.

  16. Geochemical survey of an illegal waste disposal site under a waste emergency scenario (Northwest Naples, Italy).

    Science.gov (United States)

    Ferrara, L; Iannace, M; Patelli, A M; Arienzo, M

    2013-03-01

    Since the mid 1980s, Naples and the Campania region have suffered from the dumping of wastes into overfilled landfills. The aim was to characterise a former cave located in Roccarainola (Naples, Italy) for its eventual destination to a controlled landfill site. A detailed hydro-geochemical survey of the area was carried out through drilling of 14 boreholes and four monitoring wells. Samples of water, sediment and soil were analysed for heavy metals and organic contaminants from a dew pond placed in the middle of the cave. The underneath aquifer was also surveyed. The nature of gases emitted from the site was investigated. Results of the geognostic survey revealed the presence of huge volumes of composite wastes, approximately half a million of cubic metre, which accumulated up to a thickness of 25.6 m. In some points, wastes lie below the free surface level of the aquifer. The sampled material from the boreholes revealed levels of As, Cd, Cr, Cu, Hg, Pb, Sn, Tl and Zn exceeding the intervention legal limits. Outstanding loads of Cd, Pb and Zn were found, with levels exceeding of about 50, 100 and 1,870 times the limit. In several points, polycyclic aromatic hydrocarbon load was extremely high, 35 vs 1 mg kg(-1) of the threshold. The aquifer was also very heavily polluted by Cd, Cr-tot, Cu, Fe, Mn, Ni, Pb and Zn, with impressive high load of Cr and Mn, up to 250-370 times the limits. Hot gases up to 62 °C with presence of xylene and ethylbenzene were found. Results indicated that the site needs an urgent intervention of recovery to avoid compromising the surrounding areas and aquifers of the Campania plain.

  17. Characterising aquifer treatment for pathogens in managed aquifer recharge.

    Science.gov (United States)

    Page, D; Dillon, P; Toze, S; Sidhu, J P S

    2010-01-01

    In this study the value of subsurface treatment of urban stormwater during Aquifer Storage Transfer Recovery (ASTR) is characterised using quantitative microbial risk assessment (QMRA) methodology. The ASTR project utilizes a multi-barrier treatment train to treat urban stormwater but to date the role of the aquifer has not been quantified. In this study it was estimated that the aquifer barrier provided 1.4, 2.6, >6.0 log(10) removals for rotavirus, Cryptosporidium and Campylobacter respectively based on pathogen diffusion chamber results. The aquifer treatment barrier was found to vary in importance vis-à-vis the pre-treatment via a constructed wetland and potential post-treatment options of UV-disinfection and chlorination for the reference pathogens. The risk assessment demonstrated that the human health risk associated with potable reuse of stormwater can be mitigated (disability adjusted life years, DALYs aquifer is integrated with suitable post treatment options into a treatment train to attenuate pathogens and protect human health.

  18. Using hydrochemical data and modelling to enhance the knowledge of groundwater flow and quality in an alluvial aquifer of Zagreb, Croatia

    Energy Technology Data Exchange (ETDEWEB)

    Marković, Tamara, E-mail: tmarkovic@hgi-cgs.hr; Brkić, Željka; Larva, Ozren

    2013-08-01

    The Zagreb alluvial aquifer system is located in the southwest of the Pannonian Basin in the Sava Valley in Croatia. It is composed of Quaternary unconsolidated deposits and is highly utilised, primarily as a water supply for the more than one million inhabitants of the capital city of Croatia. To determine the origin and dynamics of the groundwater and to enhance the knowledge of groundwater flow and the interactions between the groundwater and surface water, extensive hydrogeological and hydrochemical investigations have been completed. The groundwater levels monitored in nested observation wells and the lithological profile indicate that the aquifer is a single hydrogeologic unit, but the geochemical characteristics of the aquifer indicate stratification. The weathering of carbonate and silicate minerals has an important role in groundwater chemistry, especially in the area where old meanders of the Sava River existed. Groundwater quality was observed to be better in the deeper parts of the aquifer than in the shallower parts. Furthermore, deterioration of the groundwater quality was observed in the area under the influence of the landfill. The stable isotopic composition of all sampled waters indicates meteoric origin. NETPATH-WIN was used to calculate the mixing proportions between initial waters (water from the Sava River and groundwater from “regional” flow) in the final water (groundwater sampled from observation wells). According to the results, the mixing proportions of “regional” flow and the river water depend on hydrological conditions, the duration of certain hydrological conditions and the vicinity of the Sava River. Moreover, although the aquifer system behaves as a single hydrogeologic unit from a hydraulic point of view, it still clearly demonstrates geochemical stratification, which could be a decisive factor in future utilisation strategies for the aquifer system. - Highlights: • The Zagreb aquifer is the largest utilised source of

  19. 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.

  20. The chemical behavior of the transuranic elements and the barrier function in natural aquifer systems

    International Nuclear Information System (INIS)

    Jewett, J.R.

    1997-01-01

    In a geological repository for long-lived radioactive wastes, such as actinides and certain fission products, most of the stored radionuclides remain immobile in the particular geological formation. If any of these could possibly become mobile, only trace concentrations of a few radionuclides would result. Nevertheless, with an inventory in the repository of many tonnes of transuranic elements, the amounts that could disperse cannot be neglected. A critical assessment of the chemical behavior of these nuclides, especially their migration properties in the aquifer system around the repository site, is mandatory for analysis of the long-term safety. The chemistry requited for this includes many geochemical multicomponent reactions that are so far only partially understood and hich therefore can be quantified only incompletely. A few of these reactions have been discussed in this paper based on present knowledge. If a comprehensive discussion of the subject is impossible because of this ack of information then an attempt to emphasize the importance of the predominant geochemical reactions of the transuranic elements in various aquifer systems should be made

  1. Hydrodynamic analysis of the artificial recharge of aquifers during the planning stage. Results obtained in the Quaternary aquifer in the Valley of the Guadalquivir (Spain); Analisis hidrodinamico de la recarga artificial de acuiferos durante la etapa de planificacion. Resultados obtenidos en el acuifero cuaternario del valle del Guadalquivir (Espana)

    Energy Technology Data Exchange (ETDEWEB)

    Murillo, J. M.

    2014-10-01

    This paper shows a study on the viability of an artificial recharge in the flood-plain aquifer of the Guadalquivir River (Andalucia, Spain). The method used to the evaluation of the artificial recharge project is as follows: A simple model (one cell). The code has been made on the use of an EXCEL spreadsheet. A distributed parameters-flow model using a standard code (Modflow). A pilot recharge plant. The simple model has been applied in different zones. The model has only 5 parameters. It evaluates the artificial recharge by means of the depletion coefficient. The model was calibrated for a monthly time-step, although the water balances in the soil and in the aquifer were calculated daily. The calibration the distributed parameter-flow model shows a high transmissivity, storage coefficient and porosity. The pilot recharge plant is a trench with recharge wells within it. The water available for recharge is obtained from an irrigation canal. A network of control points has been established to monitor the piezometric levels. The results obtained show a high storage coefficient and porosity. These parameters show a rapid groundwater velocity. Finally, the paper compares and contrasts the results obtained with the simple model, distributed parameter- flow model and the pilot recharge plant. The results are quite similar. The groundwater velocity is rapid. Water remains in the aquifer for a few days before returning to the river. (Author)

  2. Sedimentological, mineralogical, and geochemical results from surface sediments and the sediment record from Site 2 of the ICDP drilling project at Lake Towuti, Indonesia

    Science.gov (United States)

    Hasberg, A. K.; Melles, M.; Wennrich, V.; Vogel, H.; Just, J.; Russell, J. M.; Bijaksana, S.; Morlock, M.; Opitz, S.

    2017-12-01

    More than 1000 m of sediment core were recovered in spring 2015 from three different drill sites in tropical Lake Towuti (2.5°S, 121°E), Indonesia, during the Towuti Drilling Project (TDP) of the International Continental Scientific Drilling Program (ICDP). Furthermore, a set of 84 lake surface sediment samples, distributed over the entire lake, was collected in order to better understand modern sedimentary processes. The surface samples were investigated for physical, chemical, mineralogical, and biological properties at the University of Cologne (UoC), Germany. On the sediment cores macro- and microscopical lithological descriptions, line-scan imaging, logging of physical properties (MSCL), and subsampling was conducted at the National Lacustrine Core Facility of the University of Minnesota, USA, in November 2015 and January 2016. Afterwards, the archive core halves and 672 subsamples of TDP Site 2 were shipped to the UoC for X-Ray Fluorescence (XRF) scanning and sedimentological, geochemical, and mineralogical analyses, respectively, supplemented by visible to near-infrared spectroscopy (VNIR) at Brown University, USA. The data from the surface samples evidence that allochthonous sedimentation in Lake Towuti today is dominated by fluvial supply from five distinguishable source areas: (i) the Mahalona River to the north, which drains lakes Mahalona and Matano, (ii) inlets around the village of Timampu to the northwest, (iii) the Loeha River to the east, (iv) the Lengke River to the south, and (v) the Lemo-Lemo River to the northeast of Lake Towuti. Of these, source areas (ii) and (iii) as well as (iv) and (v) have similar geochemical compositions, respectively. In addition, the lake sedimentation is significantly influenced by gravitational sediment supply from steep slopes as well as lake-internal gravitational and density-driven processes. The uppermost 41 m of sediment core 2A consist of pelagic sediments (totaling 11 m) and event layers from mass movement

  3. Development Report on the Idaho National Laboratory Sitewide Three-Dimensional Aquifer Model

    Energy Technology Data Exchange (ETDEWEB)

    Thomas R. Wood; Catherine M. Helm-Clark; Hai Huang; Swen Magnuson; Travis McLing; Brennon Orr; Michael J. Rohe; Mitchell A. Plummer; Robert Podgorney; Erik Whitmore; Michael S. Roddy

    2007-09-01

    A sub-regional scale, three-dimensional flow model of the Snake River Plain Aquifer was developed to support remediation decisions for Waste Area Group 10, Operable Unit 10 08 at the Idaho National Laboratory (INL) Site. This model has been calibrated primarily to water levels and secondarily to groundwater velocities interpreted from stable isotope disequilibrium studies and the movement of anthropogenic contaminants in the aquifer from facilities at the INL. The three-dimensional flow model described in this report is one step in the process of constructing a fully three-dimensional groundwater flow and contaminant transport model as prescribed in the Idaho National Engineering and Environmental Laboratory Operable Unit 10-08 Sitewide Groundwater Model Work Plan. An updated three-dimensional hydrogeologic conceptual model is presented along with the geologic basis for the conceptual model. Sediment-dominated three-dimensional volumes were used to represent the geology and constrain groundwater flow as part of the conceptual model. Hydrological, geochemical, and geological data were summarized and evaluated to infer aquifer behavior. A primary observation from development and evaluation of the conceptual model was that relative to flow on a regional scale, the aquifer can be treated with steady-state conditions. Boundary conditions developed for the three-dimensional flow model are presented along with inverse simulations that estimate parameterization of hydraulic conductivity. Inverse simulations were performed using the pilot-point method to estimate permeability distributions. Thermal modeling at the regional aquifer scale and at the sub-regional scale using the inverted permeabilities is presented to corroborate the results of the flow model. The results from the flow model show good agreement with simulated and observed water levels almost always within 1 meter. Simulated velocities show generally good agreement with some discrepancies in an interpreted low

  4. Geologic, geochemical, microbiologic, and hydrologic characterization at the In Situ Redox Manipulation Test Site

    International Nuclear Information System (INIS)

    Vermeul, V.R.; Teel, S.S.; Amonette, J.E.

    1995-07-01

    This report documents results from characterization activities at the In Situ Redox Manipulation (ISRM) Field Test Site which is located within the 100-HR-3 Operable Unit of the US Department of Energy's (DOE's) Hanford Site in Richland, Washington. Information obtained during hydrogeologic characterization of the site included sediment physical properties, geochemical properties, microbiologic population data, and aquifer hydraulic properties. The purpose of obtaining this information was to improve the conceptual understanding of the hydrogeology beneath the ISRM test site and provide detailed, site specific hydrogeologic parameter estimates. The resulting characterization data will be incorporated into a numerical model developed to simulate the physical and chemical processes associated with the field experiment and aid in experiment design and interpretation

  5. Geochemical modeling of reactions and partitioning of trace metals and radionuclides during titration of contaminated acidic sediments.

    Science.gov (United States)

    Zhang, Fan; Luo, Wensui; Parker, Jack C; Spalding, Brian P; Brooks, Scott C; Watson, David B; Jardine, Philip M; Gu, Baohua

    2008-11-01

    Many geochemical reactions that control aqueous metal concentrations are directly affected by solution pH. However, changes in solution pH are strongly buffered by various aqueous phase and solid phase precipitation/dissolution and adsorption/desorption reactions. The ability to predict acid-base behavior of the soil-solution system is thus critical to predict metal transport under variable pH conditions. This studywas undertaken to develop a practical generic geochemical modeling approach to predict aqueous and solid phase concentrations of metals and anions during conditions of acid or base additions. The method of Spalding and Spalding was utilized to model soil buffer capacity and pH-dependent cation exchange capacity by treating aquifer solids as a polyprotic acid. To simulate the dynamic and pH-dependent anion exchange capacity, the aquifer solids were simultaneously treated as a polyprotic base controlled by mineral precipitation/ dissolution reactions. An equilibrium reaction model that describes aqueous complexation, precipitation, sorption and soil buffering with pH-dependent ion exchange was developed using HydroGeoChem v5.0 (HGC5). Comparison of model results with experimental titration data of pH, Al, Ca, Mg, Sr, Mn, Ni, Co, and SO4(2-) for contaminated sediments indicated close agreement suggesting that the model could potentially be used to predictthe acid-base behavior of the sediment-solution system under variable pH conditions.

  6. Hydrogeochemical characteristics of groundwater in the coal-bearing aquifer of the Wugou coal mine, northern Anhui Province, China

    Science.gov (United States)

    Chen, Song; Gui, Herong

    2017-07-01

    Major ions, trace elements, and isotope concentrations were measured in 11 representative groundwater samples that were collected from a series of aquifers in the Wugou coal mine, Anhui Province. The geochemical characteristics of the groundwater samples were examined using conventional graphical and multivariate statistical approaches, and the results showed that almost all of the groundwater samples collected from the coal-bearing aquifer were the Na-SO4 type, whereas the samples from the Quaternary and the limestone aquifer were the Ca-SO4 and Na-Cl types, respectively. The groundwater in the study area is not suitable for drinking without treatment because of the higher values of total dissolved solids and other parameters, whereas the lower value of the sodium adsorption ratio indicates that it can be used for irrigation. The total rare earth element concentrations ranged from 0.0398 to 0.1874 mg/L, and had an average of 0.075 mg/L. There were negative cerium and positive europium anomalies in the groundwater. The δD and δ 18O values in groundwater ranged from -9.01 to -8.81 ‰, and from -74.7 to -71.4 ‰, respectively. Meteoric water with variable degrees of evaporation is the main source of the groundwater in the coal-bearing aquifer.

  7. Relationship between pyrite Stability and arsenic mobility during aquifer storage and recovery in southwest central Florida.

    Science.gov (United States)

    Jones, Gregg W; Pichler, Thomas

    2007-02-01

    Elevated arsenic concentrations are common in water recovered from aquifer storage and recovery (ASR) systems in west-central Florida that store surface water. Investigations of the Suwannee Limestone of the Upper Floridan aquifer, the storage zone for ASR systems, have shown that arsenic is highest in pyrite in zones of high moldic porosity. Geochemical modeling was employed to examine pyrite stability in limestone during simulated injections of surface water into wells open only to the Suwannee Limestone with known mineralogy and water chemistry. The goal was to determine if aquifer redox conditions could be altered to the degree of pyrite instability. Increasing amounts of injection water were added to native storage-zone water, and resulting reaction paths were plotted on pyrite stability diagrams. Native storage-zone water plotted within the pyrite stability field, indicating that conditions were sufficiently reducing to allow for pyrite stability. Thus, arsenic is immobilized in pyrite, and its groundwater concentration should be low. This was corroborated by analysis of water samples, none of which had arsenic concentrations above 0.036 microg/L. During simulation, however, as injection/native storage-zone water ratios increased, conditions became less reducing and pyrite became unstable. The result would be release of arsenic from limestone into storage-zone water.

  8. PHAST Version 2-A Program for Simulating Groundwater Flow, Solute Transport, and Multicomponent Geochemical Reactions

    Science.gov (United States)

    Parkhurst, David L.; Kipp, Kenneth L.; Charlton, Scott R.

    2010-01-01

    The computer program PHAST (PHREEQC And HST3D) simulates multicomponent, reactive solute transport in three-dimensional saturated groundwater flow systems. PHAST is a versatile groundwater flow and solute-transport simulator with capabilities to model a wide range of equilibrium and kinetic geochemical reactions. The flow and transport calculations are based on a modified version of HST3D that is restricted to constant fluid density and constant temperature. The geochemical reactions are simulated with the geochemical model PHREEQC, which is embedded in PHAST. Major enhancements in PHAST Version 2 allow spatial data to be defined in a combination of map and grid coordinate systems, independent of a specific model grid (without node-by-node input). At run time, aquifer properties are interpolated from the spatial data to the model grid; regridding requires only redefinition of the grid without modification of the spatial data. PHAST is applicable to the study of natural and contaminated groundwater systems at a variety of scales ranging from laboratory experiments to local and regional field scales. PHAST can be used in studies of migration of nutrients, inorganic and organic contaminants, and radionuclides; in projects such as aquifer storage and recovery or engineered remediation; and in investigations of the natural rock/water interactions in aquifers. PHAST is not appropriate for unsaturated-zone flow, multiphase flow, or density-dependent flow. A variety of boundary conditions are available in PHAST to simulate flow and transport, including specified-head, flux (specified-flux), and leaky (head-dependent) conditions, as well as the special cases of rivers, drains, and wells. Chemical reactions in PHAST include (1) homogeneous equilibria using an ion-association or Pitzer specific interaction thermodynamic model; (2) heterogeneous equilibria between the aqueous solution and minerals, ion exchange sites, surface complexation sites, solid solutions, and gases; and

  9. Geochemical exploration for uranium

    International Nuclear Information System (INIS)

    Rose, A.W.

    1977-01-01

    The processes and types of dispersion that produce anomalies in stream water, stream sediment, and ground water, and the factors that must be considered in planning and interpreting geochemical surveys are reviewed. Examples of surveys near known deposits show the types of results to be expected. Background values depend mainly on the content of U in rocks of the drainage area. In igneous rocks, U tends to increase with potassium from ultramafic rocks (0.01 ppM) to granitic rocks (1 to 5 ppM). Some alkalic rocks have unusually high contents of U (15 to 100 ppM). Uranium-rich provinces marked by igneous rocks unusually rich in U are recognized in several areas and appear to have a deep crustal or mantle origin. In western U.S., many tertiary tuffaceous rocks have a high U content. Sandstones, limestones, and many shales approximate the crustal abundance at 0.5 to 4 ppM, but black shales, phosphates, and some organic materials are notably enriched in U. Uranium is very soluble in most oxidizing waters at the earth's surface, but is precipitated by reducing agents (organic matter, H 2 S) and adsorbed by organic material and some Fe oxides. In most surface and ground waters, U correlates approximately with the total dissolved solids, conductivity, and bicarbonate concentration of the water, and with the U content of rocks it comes into contact with. Most surveys of stream water near known districts show distinct anomalies extending a few km to tens of km downstream. A complication with water is the large variability with time, up to x 50, as a result of changes in the ratio of ground water to direct runoff, and changes in rate of oxidation and leaching. Collection and analysis of water samples also pose some difficulties

  10. Geochemical prospecting in Guiana

    International Nuclear Information System (INIS)

    Coulomb, R.

    1957-01-01

    During the last few years geochemical prospecting techniques have become common usage in the field of mineral deposit prospecting. The real scope of these methods lies in their use in the prospecting of large areas. The most promising use of the geochemistry and hydro-geochemistry of uranium is in heavily forested tropical territories, with few outcrops, where radiometry is strongly handicapped. (author) [fr

  11. A geochemical and geophysical reappraisal to the significance of the recent unrest at Campi Flegrei caldera (Southern Italy)

    Science.gov (United States)

    Moretti, Roberto; De Natale, Giuseppe; Troise, Claudia

    2017-04-01

    Volcanic unrest at calderas involve complex interaction between magma, hydrothermal fluids and crustal stress and strain. Campi Flegrei caldera (CFc), located in the Naples (Italy) area and characterised by the highest volcanic risk on Earth for the extreme urbanisation, undergoes unrest phenomena involving several meters of uplift and intense shallow micro-seismicity since several decades. Despite unrest episodes display in the last decade only moderate ground deformation and seismicity, current interpretations of geochemical data point to a highly pressurized hydrothermal system. We show that at CFc, the usual assumption of vapour-liquid coexistence in the fumarole plumes leads to largely overestimated hydrothermal pressures and, accordingly, interpretations of elevated unrest. By relaxing unconstrained geochemical assumptions, we infer an alternative model yielding better agreement between geophysical and geochemical observations. The model reconciles discrepancies between what observed 1) for two decades since the 1982-84 large unrest, when shallow magma was supplying heat and fluids to the hydrothermal system, and 2) in the last decade. Compared to the 1980's unrest, the post-2005 phenomena are characterized by much lower aquifers overpressure and magmatic involvement, as indicated by geophysical data and despite large changes in geochemical indicators. Our interpretation points out a model in which shallow sills, intruded during 1969-1984, have completely cooled, so that fumarole emissions are affected now by deeper, CO2-richer, magmatic gases producing a relatively modest heating and overpressure of the hydrothermal system. Our results do have important implications on the short-term eruption hazard assessment and on the best strategies for monitoring and interpreting geochemical data.

  12. Hydrology of the Claiborne aquifer and interconnection with the Upper Floridan aquifer in southwest Georgia

    Science.gov (United States)

    Gordon, Debbie W.; Gonthier, Gerard

    2017-04-24

    The U.S. Geological Survey conducted a study, in cooperation with the Georgia Environmental Protection Division, to define the hydrologic properties of the Claiborne aquifer and evaluate its connection with the Upper Floridan aquifer in southwest Georgia. The effort involved collecting and compiling hydrologic data from the aquifer in subarea 4 of southwestern Georgia. Data collected for this study include borehole geophysical logs in 7 wells, and two 72-hour aquifer tests to determine aquifer properties.The top of the Claiborne aquifer extends from an altitude of about 200 feet above the North American Vertical Datum of 1988 (NAVD 88) in Terrell County to 402 feet below NAVD 88 in Decatur County, Georgia. The base of the aquifer extends from an altitude of about 60 feet above NAVD 88 in eastern Sumter County to about 750 feet below NAVD 88 in Decatur County. Aquifer thickness ranges from about 70 feet in eastern Early County to 400 feet in Decatur County.The transmissivity of the Claiborne aquifer, determined from two 72-hour aquifer tests, was estimated to be 1,500 and 700 feet squared per day in Mitchell and Early Counties, respectively. The storage coefficient was estimated to be 0.0006 and 0.0004 for the same sites, respectively. Aquifer test data from Mitchell County indicate a small amount of leakage occurred during the test. Groundwater-flow models suggest that the source of the leakage was the underlying Clayton aquifer, which produced about 2.5 feet of drawdown in response to pumping in the Claiborne aquifer. The vertical hydraulic conductivity of the confining unit between the Claiborne and Clayton aquifers was simulated to be about 0.02 foot per day.Results from the 72-hour aquifer tests run for this study indicated no interconnection between the Claiborne and overlying Upper Floridan aquifers at the two test sites. Additional data are needed to monitor the effects that increased withdrawals from the Claiborne aquifer may have on future water resources.

  13. Estimating Aquifer Properties Using Sinusoidal Pumping Tests

    Science.gov (United States)

    Rasmussen, T. C.; Haborak, K. G.; Young, M. H.

    2001-12-01

    We develop the theoretical and applied framework for using sinusoidal pumping tests to estimate aquifer properties for confined, leaky, and partially penetrating conditions. The framework 1) derives analytical solutions for three boundary conditions suitable for many practical applications, 2) validates the analytical solutions against a finite element model, 3) establishes a protocol for conducting sinusoidal pumping tests, and 4) estimates aquifer hydraulic parameters based on the analytical solutions. The analytical solutions to sinusoidal stimuli in radial coordinates are derived for boundary value problems that are analogous to the Theis (1935) confined aquifer solution, the Hantush and Jacob (1955) leaky aquifer solution, and the Hantush (1964) partially penetrated confined aquifer solution. The analytical solutions compare favorably to a finite-element solution of a simulated flow domain, except in the region immediately adjacent to the pumping well where the implicit assumption of zero borehole radius is violated. The procedure is demonstrated in one unconfined and two confined aquifer units near the General Separations Area at the Savannah River Site, a federal nuclear facility located in South Carolina. Aquifer hydraulic parameters estimated using this framework provide independent confirmation of parameters obtained from conventional aquifer tests. The sinusoidal approach also resulted in the elimination of investigation-derived wastes.

  14. A conceptual model for groundwater flow and geochemical evolution in the southern Outaouais Region, Québec, Canada

    International Nuclear Information System (INIS)

    Montcoudiol, N.; Molson, J.; Lemieux, J.-M.; Cloutier, V.

    2015-01-01

    Highlights: • Geochemical and isotope data help constrain the 2D conceptual flow model. • Stable isotopes indicate recharge occurring under conditions similar to current climate. • Mixing was found between younger ( 3 H) and older ( 14 C and 4 He) groundwater. • Mixing occurred under natural flow conditions and/or was induced during sampling. • The new conceptual model shows dominant local and intermediate flow systems. - Abstract: A conceptual model was developed for a hydrogeological flow system in the southern Outaouais Region, Quebec, Canada, where the local population relies heavily on groundwater pumped from shallow overburden aquifers and from deeper fractured crystalline bedrock. The model is based on the interpretation of aqueous inorganic geochemical data from 14 wells along a cross-section following the general flow direction, of which 9 were also analysed for isotopes (δ 18 O, δ 2 H, 3 H, δ 13 C, 14 C) and 4 for noble gases (He, Ne, Ar, Xe, Kr). Three major water types were identified: (1) Ca–HCO 3 in the unconfined aquifer as a result of silicate (Ca-feldspar) weathering, (2) Na–Cl as a remnant of the post-glacial Champlain Sea in stagnant confined zones of the aquifer, and (3) Na–HCO 3 , resulting from freshening of the confined aquifer due to Ca–Na cation exchange. Chemical data also allowed the identification of significant mixing zones. Isotope and noble gas data confirm the hypothesis of remnant water from the Champlain Sea and also support the hypothesis of mixing processes between a young tritium-rich component with an older component containing high 4 He concentrations. It is still unclear if the mixing occurs under natural flow conditions or if it is induced by pumping during the sampling, most wells being open boreholes in the bedrock. It is clear, however, that the hydrogeochemical system is dynamic and still evolving from induced changes since the last glaciation. As a next step, the conceptual model will serve as a

  15. Carbon isotopes of dissolved inorganic carbon reflect utilization of different carbon sources by microbial communities in two limestone aquifer assemblages

    Directory of Open Access Journals (Sweden)

    M. E. Nowak

    2017-08-01

    Full Text Available Isotopes of dissolved inorganic carbon (DIC are used to indicate both transit times and biogeochemical evolution of groundwaters. These signals can be complicated in carbonate aquifers, as both abiotic (i.e., carbonate equilibria and biotic factors influence the δ13C and 14C of DIC. We applied a novel graphical method for tracking changes in the δ13C and 14C of DIC in two distinct aquifer complexes identified in the Hainich Critical Zone Exploratory (CZE, a platform to study how water transport links surface and shallow groundwaters in limestone and marlstone rocks in central Germany. For more quantitative estimates of contributions of different biotic and abiotic carbon sources to the DIC pool, we used the NETPATH geochemical modeling program, which accounts for changes in dissolved ions in addition to C isotopes. Although water residence times in the Hainich CZE aquifers based on hydrogeology are relatively short (years or less, DIC isotopes in the shallow, mostly anoxic, aquifer assemblage (HTU were depleted in 14C compared to a deeper, oxic, aquifer complex (HTL. Carbon isotopes and chemical changes in the deeper HTL wells could be explained by interaction of recharge waters equilibrated with post-bomb 14C sources with carbonates. However, oxygen depletion and δ13C and 14C values of DIC below those expected from the processes of carbonate equilibrium alone indicate considerably different biogeochemical evolution of waters in the upper aquifer assemblage (HTU wells. Changes in 14C and 13C in the upper aquifer complexes result from a number of biotic and abiotic processes, including oxidation of 14C-depleted OM derived from recycled microbial carbon and sedimentary organic matter as well as water–rock interactions. The microbial pathways inferred from DIC isotope shifts and changes in water chemistry in the HTU wells were supported by comparison with in situ microbial community structure based on 16S rRNA analyses. Our findings

  16. Comparison of aquifer characteristics derived from local and regional aquifer tests.

    Science.gov (United States)

    Randolph, R.B.; Krause, R.E.; Maslia, M.L.

    1985-01-01

    A comparison of the aquifer parameter values obtained through the analysis of a local and a regional aquifer test involving the same area in southeast Georgia is made in order to evaluate the validity of extrapolating local aquifer-test results for use in large-scale flow simulations. Time-drawdown and time-recovery data were analyzed by using both graphical and least-squares fitting of the data to the Theis curve. Additionally, directional transmissivity, transmissivity tensor, and angle of anisotropy were computed for both tests. -from Authors Georgia drawdown transmissivity regional aquifer tests

  17. Groundwater-quality data in the North San Francisco Bay Shallow Aquifer study unit, 2012: results from the California GAMA Program

    Science.gov (United States)

    Bennett, George L.; Fram, Miranda S.

    2014-01-01

    Groundwater quality in the 1,850-square-mile North San Francisco Bay Shallow Aquifer (NSF-SA) study unit was investigated by the U.S. Geological Survey (USGS) from April to August 2012, as part of the California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring and Assessment (GAMA) Program’s Priority Basin Project (PBP). The GAMA-PBP was developed in response to the California Groundwater Quality Monitoring Act of 2001 and is being conducted in collaboration with the SWRCB and Lawrence Livermore National Laboratory (LLNL). The NSF-SA study unit was the first study unit to be sampled as part of the second phase of the GAMA-PBP, which focuses on the shallow aquifer system.

  18. Nonstationary porosity evolution in mixing zone in coastal carbonate aquifer using an alternative modeling approach.

    Science.gov (United States)

    Laabidi, Ezzeddine; Bouhlila, Rachida

    2015-07-01

    In the last few decades, hydrogeochemical problems have benefited from the strong interest in numerical modeling. One of the most recognized hydrogeochemical problems is the dissolution of the calcite in the mixing zone below limestone coastal aquifer. In many works, this problem has been modeled using a coupling algorithm between a density-dependent flow model and a geochemical model. A related difficulty is that, because of the high nonlinearity of the coupled set of equations, high computational effort is needed. During calcite dissolution, an increase in permeability can be identified, which can induce an increase in the penetration of the seawater into the aquifer. The majority of the previous studies used a fully coupled reactive transport model in order to model such problem. Romanov and Dreybrodt (J Hydrol 329:661-673, 2006) have used an alternative approach to quantify the porosity evolution in mixing zone below coastal carbonate aquifer at steady state. This approach is based on the analytic solution presented by Phillips (1991) in his book Flow and Reactions in Permeable Rock, which shows that it is possible to decouple the complex set of equation. This equation is proportional to the square of the salinity gradient, which can be calculated using a density driven flow code and to the reaction rate that can be calculated using a geochemical code. In this work, this equation is used in nonstationary step-by-step regime. At each time step, the quantity of the dissolved calcite is quantified, the change of porosity is calculated, and the permeability is updated. The reaction rate, which is the second derivate of the calcium equilibrium concentration in the equation, is calculated using the PHREEQC code (Parkhurst and Apello 1999). This result is used in GEODENS (Bouhlila 1999; Bouhlila and Laabidi 2008) to calculate change of the porosity after calculating the salinity gradient. For the next time step, the same protocol is used but using the updated porosity

  19. Dissolved {sup 210}Po and {sup 210}Pb in Guarani aquifer groundwater, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Bonotto, D.M. [Departamento de Petrologia e Metalogenia, Universidade Estadual Paulista (UNESP), Av. 24-A No. 1515, C.P. 178, CEP 13506-900 Rio Claro, Sao Paulo (Brazil)], E-mail: danielbonotto@yahoo.com.br; Caprioglio, L.; Bueno, T.O.; Lazarindo, J.R. [Departamento de Petrologia e Metalogenia, Universidade Estadual Paulista (UNESP), Av. 24-A No. 1515, C.P. 178, CEP 13506-900 Rio Claro, Sao Paulo (Brazil)

    2009-03-15

    The huge Guarani aquifer located in the South American continent is a very important resource for the region, and its drinking water quality has been investigated according to international standards, inclusive radiological parameters. This paper describes {sup 210}Po and {sup 210}Pb activity concentration data in groundwater samples collected at the Brazilian portion of Guarani aquifer, that is characterized by a great variability of temperature (18-70 deg. C), pH (4.0-9.9), sodium content (0.3-322 mg/l), bicarbonate content (0.1-318 mg/l), etc. Non-expensive alpha counting following some radiochemical steps for extracting and depositing dissolved {sup 210}Po was used. The results of the measurements for samples collected in duplicate yielded a maximum {sup 210}Po activity concentration of 3.7 mBq/L and a maximum {sup 210}Pb activity concentration of 6.7 mBq/l, that are values greatly lower than the guidance level of 0.1 Bq/l established by the WHO for their presence in drinking water. The high sensitivity of the method allowed its applicability on the identification of complexes geochemical and hydrogeological processes occurring in Guarani aquifer as well on the evaluation of the drinking water quality in terms of dose calculations.

  20. Dissolved 210Po and 210Pb in Guarani aquifer groundwater, Brazil

    International Nuclear Information System (INIS)

    Bonotto, D.M.; Caprioglio, L.; Bueno, T.O.; Lazarindo, J.R.

    2009-01-01

    The huge Guarani aquifer located in the South American continent is a very important resource for the region, and its drinking water quality has been investigated according to international standards, inclusive radiological parameters. This paper describes 210 Po and 210 Pb activity concentration data in groundwater samples collected at the Brazilian portion of Guarani aquifer, that is characterized by a great variability of temperature (18-70 deg. C), pH (4.0-9.9), sodium content (0.3-322 mg/l), bicarbonate content (0.1-318 mg/l), etc. Non-expensive alpha counting following some radiochemical steps for extracting and depositing dissolved 210 Po was used. The results of the measurements for samples collected in duplicate yielded a maximum 210 Po activity concentration of 3.7 mBq/L and a maximum 210 Pb activity concentration of 6.7 mBq/l, that are values greatly lower than the guidance level of 0.1 Bq/l established by the WHO for their presence in drinking water. The high sensitivity of the method allowed its applicability on the identification of complexes geochemical and hydrogeological processes occurring in Guarani aquifer as well on the evaluation of the drinking water quality in terms of dose calculations.

  1. Intrinsic bioremediation of petroleum hydrocarbons in a gas condensate-contaminated aquifer

    International Nuclear Information System (INIS)

    Gieg, L.M.; McInerney; Tanner, R.S.; Harris, S.H. Jr.; Sublette, K.L.; Suflita, J.M.; Kolhatkar, R.V.

    1999-01-01

    A study was designed to determine if the intrinsic bioremediation of gas condensate hydrocarbons represented an important fate process in a shallow aquifer underlying a natural gas production site. For over 4 yr, changes in the groundwater, sediment, and vadose zone chemistry in the contaminated portion of the aquifer were interpreted relative to a background zone. Changes included decreased dissolved oxygen and sulfate levels and increased alkalinity, Fe(II), and methane concentrations in the contaminated groundwater, suggesting that aerobic heterotrophic respiration depleted oxygen reserves leaving anaerobic conditions in the hydrocarbon-impacted subsurface. Dissolved hydrogen levels in the contaminated groundwater indicated that sulfate reduction and methanogenesis were predominant biological processes, corroborating the geochemical findings. Furthermore, 10--1000-fold higher numbers of sulfate reducers and methanogens were enumerated in the contaminated sediment relative to background. Putative metabolites were also detected in the contaminated groundwater, including methylbenzylsuccinic acid, a signature intermediate of anaerobic xylene decay. Laboratory incubations showed that benzene, toluene, ethylbenzene, and each of the xylene isomers were biodegraded under sulfate-reducing conditions as was toluene under methanogenic conditions. These results coupled with a decrease in hydrocarbon concentrations in contaminated sediment confirm that intrinsic bioremediation contributes to the attenuation of hydrocarbons in this aquifer

  2. Assessing the efficiency of a coastal Managed Aquifer Recharge (MAR) system in Cyprus.

    Science.gov (United States)

    Tzoraki, Ourania; Dokou, Zoi; Christodoulou, George; Gaganis, Petros; Karatzas, George

    2018-06-01

    Managed Aquifer Recharge (MAR) is becoming an attractive water management option, with more than 223 sites operating in European countries. The quality of the produced water, available for drinking or irrigation processes is strongly depended on the aquifer's hydrogeochemical characteristics and on the MAR system design and operation. The objective of this project is the assessment of the operation efficiency of a MAR system in Cyprus. The coupling of alternative methodologies is used such as water quality monitoring, micro-scale sediment sorption experiments, simulation of groundwater flow and phosphate and copper transport in the subsurface using the FEFLOW model and evaluation of the observed change in the chemical composition of water due to mixing using the geochemical model PHREEQC. The above methodology is tested in the Ezousa MAR project in Cyprus, where treated effluent from the Paphos Waste Water Treatment Plant, is recharged into the aquifer through five sets of artificial ponds along the riverbed. Additionally, groundwater is pumped for irrigation purposes from wells located nearby. A slight attenuation of nutrients is observed, whereas copper in groundwater is overcoming the EPA standards. The FEFLOW simulations reveal no effective mixing in some intermediate infiltration ponds, which is validated by the inverse modeling simulation of the PHREEQC model. Based on the results, better control of the infiltration capacity of some of the ponds and increased travel times are some suggestions that could improve the efficiency of the system. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. Hydrological controls on transient aquifer storage in a karst watershed

    Science.gov (United States)

    Spellman, P.; Martin, J.; Gulley, J. D.

    2017-12-01

    While surface storage of floodwaters is well-known to attenuate flood peaks, transient storage of floodwaters in aquifers is a less recognized mechanism of flood peak attenuation. The hydraulic gradient from aquifer to river controls the magnitude of transient aquifer storage and is ultimately a function of aquifer hydraulic conductivity, and effective porosity. Because bedrock and granular aquifers tend to have lower hydraulic conductivities and porosities, their ability to attenuate flood peaks is generally small. In karst aquifers, however, extensive cave systems create high hydraulic conductivities and porosities that create low antecedent hydraulic gradients between aquifers and rivers. Cave springs can reverse flow during high discharges in rivers, temporarily storing floodwaters in the aquifer thus reducing the magnitude of flood discharge downstream. To date however, very few studies have quantified the magnitude or controls of transient aquifer storage in karst watersheds. We therefore investigate controls on transient aquifer storage by using 10 years of river and groundwater data from the Suwannee River Basin, which flows over the karstic upper Floridan aquifer in north-central Florida. We use multiple linear regression to compare the effects of three hydrological controls on the magnitude of transient aquifer storage: antecedent stage, recharge and slope of hydrograph rise. We show the dominant control on transient aquifer storage is antecedent stage, whereby lower stages result in greater magnitudes of transient aquifer storage. Our results suggest that measures of groundwater levels prior to an event can be useful in determining whether transient aquifer storage will occur and may provide a useful metric for improving predictions of flood magnitudes.

  4. Changing the scale of hydrogeophysical aquifer heterogeneity characterization

    Science.gov (United States)

    Paradis, Daniel; Tremblay, Laurie; Ruggeri, Paolo; Brunet, Patrick; Fabien-Ouellet, Gabriel; Gloaguen, Erwan; Holliger, Klaus; Irving, James; Molson, John; Lefebvre, Rene

    2015-04-01

    Contaminant remediation and management require the quantitative predictive capabilities of groundwater flow and mass transport numerical models. Such models have to encompass source zones and receptors, and thus typically cover several square kilometers. To predict the path and fate of contaminant plumes, these models have to represent the heterogeneous distribution of hydraulic conductivity (K). However, hydrogeophysics has generally been used to image relatively restricted areas of the subsurface (small fractions of km2), so there is a need for approaches defining heterogeneity at larger scales and providing data to constrain conceptual and numerical models of aquifer systems. This communication describes a workflow defining aquifer heterogeneity that was applied over a 12 km2 sub-watershed surrounding a decommissioned landfill emitting landfill leachate. The aquifer is a shallow, 10 to 20 m thick, highly heterogeneous and anisotropic assemblage of littoral sand and silt. Field work involved the acquisition of a broad range of data: geological, hydraulic, geophysical, and geochemical. The emphasis was put on high resolution and continuous hydrogeophysical data, the use of direct-push fully-screened wells and the acquisition of targeted high-resolution hydraulic data covering the range of observed aquifer materials. The main methods were: 1) surface geophysics (ground-penetrating radar and electrical resistivity); 2) direct-push operations with a geotechnical drilling rig (cone penetration tests with soil moisture resistivity CPT/SMR; full-screen well installation); and 3) borehole operations, including high-resolution hydraulic tests and geochemical sampling. New methods were developed to acquire high vertical resolution hydraulic data in direct-push wells, including both vertical and horizontal K (Kv and Kh). Various data integration approaches were used to represent aquifer properties in 1D, 2D and 3D. Using relevant vector machines (RVM), the mechanical and

  5. Remediation of a contaminated thin aquifer by horizontal wells

    Energy Technology Data Exchange (ETDEWEB)

    Breh, W.; Suttheimer, J.; Hoetzl, H. [Univ. of Karlsruhe (Germany); Frank, K. [GEO-Service GmbH, Rheinmuenster (Germany)

    1997-12-31

    At an industrial site in Bruchsal (Germany) a huge trichloroethene contamination was found. After common remedial actions proved to be widely ineffective, new investigations led to a highly contaminated thin aquifer above the main aquifer. The investigation and the beginning of the remediation of the thin aquifer by two horizontal wells is described in this paper. Special attention was given to the dependence between precipitation and the flow direction in the thin aquifer and to hydraulic connections between the thin and the main aquifer. Also a short introduction into a new remedial technique by horizontal wells and first results of the test phase of the horizontal wells are given.

  6. Hydrochemical evaluation and identification of geochemical processes in the shallow and deep wells in the Ramganga Sub-Basin, India.

    Science.gov (United States)

    Rajmohan, Natarajan; Patel, Neelam; Singh, Gaurav; Amarasinghe, Upali A

    2017-09-01

    Groundwater samples were collected from 44 wells in the Ramganga Sub-Basin (RSB), India, and analysed for major ions, nutrients and trace metals. The primary goal of this study is to evaluate the hydrochemistry and to identify the geochemical processes that govern the water chemistry in the shallow and deep tube wells in the study area using geochemical methods. The knowledge of changes in hydrochemistry of the aquifers is important for both groundwater recharge and use in the region. This study found that there are substantial differences of water chemistry between shallow and deep wells. In the shallow wells, the average concentrations of total dissolved solid (TDS), Na, K, Ca, Mg, HCO 3 , Cl, SO 4 , NO 3 , PO 4 , F, Cu, Mn, Fe and Cr are twofold higher than the deep wells. The concentrations of dissolved silica in the groundwater do not vary with the depth, which implies that the variation in the water chemistry is not due to mineral dissolution alone. Major ion ratios and saturation indices suggest that the water chemistry is predominantly controlled by dissolution of carbonate minerals, silicate weathering and ion exchange reactions. Thermodynamic evaluation (ion activity ratios and stability filed diagrams) indicates that the kaolinite and gibbsite controlled the water chemistry in the both shallow and deep wells. In addition, the groundwater chemistry in the shallow wells is affected by the vertical infiltration of contaminated water from surface contamination sources and nitrification process. In the deep wells, absence of NO 3 and low concentrations of Cl, SO 4 , PO 4 and F imply the role of regional flow and denitrification in the groundwater. Results concluded that proper management plan is necessary to protect the shallow aquifer in the RSB since shallow aquifer pumping is less expensive than the deeper one.

  7. The relationship of the Yucca Mountain repository block to the regional ground-water system: A geochemical model

    International Nuclear Information System (INIS)

    Matuska, N.A.; Hess, J.W.

    1989-08-01

    Yucca Mountain, in southern Nevada, is being studied by the Department of Energy and the State of Nevada as the site of a high-level nuclear waste repository. Geochemical and isotopic modeling were used in this study to define the relationship of the volcanic tuff aquifers and aquitards to the underlying regional carbonate ground-water system. The chemical evolution of a ground water as it passes through a hypothetical tuffaceous aquifer was developed using computer models PHREEQE, WATEQDR and BALANCE. The tuffaceous system was divided into five parts, with specific mineralogies, reaction steps and temperatures. The initial solution was an analysis of a soil water from Rainier Mesa. The ending solution in each part became the initial solution in the next part. Minerals consisted of zeolites, smectites, authigenic feldspars and quartz polymorphs from described diagentic mineral zones. Reaction steps were ion exchange with zeolites. The solution from the final zone, Part V, was chosen as most representative, in terms of pH, element molalities and mineral solubilities, of tuffaceous water. This hypothetical volcanic water from Part V was mixed with water from the regional carbonate aquifer, and the results compared to analyses of Yucca Mountain wells. Mixing and modeling attempts were conducted on wells in which studies indicated upward flow

  8. Groundwater quality of the Gulf Coast aquifer system, Houston, Texas, 2010

    Science.gov (United States)

    Oden, Jeannette H.; Brown, Dexter W.; Oden, Timothy D.

    2011-01-01

    During March–December 2010, the U.S. Geological Survey, in cooperation with the city of Houston, collected source-water samples from 60 municipal supply wells in the Houston area. These data were collected as part of an ongoing study to determine concentrations, spatial extent, and associated geochemical conditions that might be conducive for mobility and transport of selected naturally occurring contaminants (selected trace elements and radionuclides) in the Gulf Coast aquifer system in the Houston area. In the summers of 2007 and 2008, a reconnaissance-level survey of these constituents in untreated water from 28 municipal supply wells was completed in the Houston area. Included in this report are the complete analytical results for 47 of the 60 samples collected in 2010—those results which were received from the laboratories and reviewed by the authors as of December 31, 2010. All of the wells sampled were screened in the Gulf Coast aquifer system; 22 were screened entirely in the Evangeline aquifer, and the remaining 25 wells contained screened intervals that intersected both Evangeline and Chicot aquifers. The data documented in this report were collected as part of an ongoing study to characterize source-water-quality conditions in untreated groundwater prior to drinking-water treatment. An evaluation of contaminant occurrence in source water provides background information regarding the presence of a contaminant in the environment. Because source-water samples were collected prior to any treatment or blending that potentially could alter contaminant concentrations, the water-quality results documented by this report represent the quality of the source water, not the quality of finished drinking water provided to the public.

  9. A General Solution for Groundwater Flow in Estuarine Leaky Aquifer System with Considering Aquifer Anisotropy

    Science.gov (United States)

    Chen, Po-Chia; Chuang, Mo-Hsiung; Tan, Yih-Chi

    2014-05-01

    In recent years the urban and industrial developments near the coastal area are rapid and therefore the associated population grows dramatically. More and more water demand for human activities, agriculture irrigation, and aquaculture relies on heavy pumping in coastal area. The decline of groundwater table may result in the problems of seawater intrusion and/or land subsidence. Since the 1950s, numerous studies focused on the effect of tidal fluctuation on the groundwater flow in the coastal area. Many studies concentrated on the developments of one-dimensional (1D) and two-dimensional (2D) analytical solutions describing the tide-induced head fluctuations. For example, Jacob (1950) derived an analytical solution of 1D groundwater flow in a confined aquifer with a boundary condition subject to sinusoidal oscillation. Jiao and Tang (1999) derived a 1D analytical solution of a leaky confined aquifer by considered a constant groundwater head in the overlying unconfined aquifer. Jeng et al. (2002) studied the tidal propagation in a coupled unconfined and confined costal aquifer system. Sun (1997) presented a 2D solution for groundwater response to tidal loading in an estuary. Tang and Jiao (2001) derived a 2D analytical solution in a leaky confined aquifer system near open tidal water. This study aims at developing a general analytical solution describing the head fluctuations in a 2D estuarine aquifer system consisted of an unconfined aquifer, a confined aquifer, and an aquitard between them. Both the confined and unconfined aquifers are considered to be anisotropic. The predicted head fluctuations from this solution will compare with the simulation results from the MODFLOW program. In addition, the solutions mentioned above will be shown to be special cases of the present solution. Some hypothetical cases regarding the head fluctuation in costal aquifers will be made to investigate the dynamic effects of water table fluctuation, hydrogeological conditions, and

  10. Long term rise of a free aquifer in Sahel: hydrodynamic and radioisotopic estimations (3H, 14C) of the recharge in SW Niger

    International Nuclear Information System (INIS)

    Favreau, G.

    2001-01-01

    This article summarizes an hydrodynamic and geochemical survey carried out in SW Niger in order to estimate the impact of rainfall changes and deforestation on the recharge of the uppermost Cretaceous aquifer. 14 C and 3 H activities of the total dissolved inorganic carbon have been used to quantify the long-term recharge of the aquifer. (J.S.)

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

    Energy Technology Data Exchange (ETDEWEB)

    Allen, R.D.

    1983-11-01

    Ground-water quality and associated geologic characteristics may affect the feasibility of aquifer thermal energy storage (ATES) system development in any hydrologic region. This study sought to determine the relationship between ground-water quality parameters and the regional potential for ATES system development. Information was collected from available literature to identify chemical and physical mechanisms that could adversely affect an ATES system. Appropriate beneficiation techniques to counter these potential geochemical and lithologic problems were also identified through the literature search. Regional hydrology summaries and other sources were used in reviewing aquifers of 19 drainage regions in the US to determine generic geochemical characteristics for analysis. Numerical modeling techniques were used to perform geochemical analyses of water quality from 67 selected aquifers. Candidate water resources regions were then identified for exploration and development of ATES. This study identified six principal mechanisms by which ATES reservoir permeability may be impaired: (1) particulate plugging, (2) chemical precipitation, (3) liquid-solid reactions, (4) formation disaggregation, (5) oxidation reactions, and (6) biological activity. Specific proven countermeasures to reduce or eliminate these effects were found. Of the hydrologic regions reviewed, 10 were identified as having the characteristics necessary for ATES development: (1) Mid-Atlantic, (2) South-Atlantic Gulf, (3) Ohio, (4) Upper Mississippi, (5) Lower Mississippi, (6) Souris-Red-Rainy, (7) Missouri Basin, (8) Arkansas-White-Red, (9) Texas-Gulf, and (10) California.

  12. Multielement geochemical reconnaissance for uranium in the Palmyrides region of central Syria

    International Nuclear Information System (INIS)

    Jubeli, Y.M.; Hale, M.

    1988-01-01

    Multielement reconnaissance geochemistry coupled with ground scintillation gamma ray measurements has been used to investigate the dispersion patterns of uranium and other major and trace elements in the arid Palmyrides region of central Syria. Over 500 geochemical samples of outcropping rock, wadi and playa sediments, overburden and groundwaters were taken over an area of approximately 9000 sq km. Most samples were analyzed for 25 major and trace elements by nebulization ICPAES; for As, Sb, Bi and Se by hydride generation and ICPAES; and for U, Th and La and other REE by neutron activation analysis. The resulting data were interpreted with the aid of univariate and multivariate statistical methods. The areal distributions of U, its associated elements, multivariate geochemical functions and factor scores were mapped using computer graphics. Results of the factor analysis indicate that the primary lithogeochemical dispersion patterns of uranium and associated elements are controlled by a combination of structural, lithological and environmental factors. Uranium and associated elements have subsequently been leached out of the phosphorite and other U enriched clayey limestones and carbonate rocks into the hydro- geologic regime. Redistribution of these elements is taking place along fracture zones and major faults. A degree of urnaium accumulation in a Neogene aquifer of the Ad-Daww basin is evident

  13. Probabilistic, sediment-geochemical parameterisation of the groundwater compartment of the Netherlands for spatially distributed, reactive transport modelling

    Science.gov (United States)

    Janssen, Gijs; Gunnink, Jan; van Vliet, Marielle; Goldberg, Tanya; Griffioen, Jasper

    2017-04-01

    Pollution of groundwater aquifers with contaminants as nitrate is a common problem. Reactive transport models are useful to predict the fate of such contaminants and to characterise the efficiency of mitigating or preventive measures. Parameterisation of a groundwater transport model on reaction capacity is a necessary step during building the model. Two Dutch, national programs are combined to establish a methodology for building a probabilistic model on reaction capacity of the groundwater compartment at the national scale: the Geological Survey program and the NHI Netherlands Hydrological Instrument program. Reaction capacity is considered as a series of geochemical characteristics that control acid/base condition, redox condition and sorption capacity. Five primary reaction capacity variables are characterised: 1. pyrite, 2. non-pyrite, reactive iron (oxides, siderite and glauconite), 3. clay fraction, 4. organic matter and 5. Ca-carbonate. Important reaction capacity variables that are determined by more than one solid compound are also deduced: 1. potential reduction capacity (PRC) by pyrite and organic matter, 2. cation-exchange capacity (CEC) by organic matter and clay content, 3. carbonate buffering upon pyrite oxidation (CPBO) by carbonate and pyrite. Statistical properties of these variables are established based on c. 16,000 sediment geochemical analyses. The first tens of meters are characterised based on 25 regions using combinations of lithological class and geological formation as strata. Because of both less data and more geochemical uniformity, the deeper subsurface is characterised in a similar way based on 3 regions. The statistical data is used as input in an algoritm that probabilistically calculates the reaction capacity per grid cell. First, the cumulative frequency distribution (cfd) functions are calculated from the statistical data for the geochemical strata. Second, all voxel cells are classified into the geochemical strata. Third, the

  14. Alaska Geochemical Database (AGDB)-Geochemical data for rock, sediment, soil, mineral, and concentrate sample media

    Science.gov (United States)

    Granitto, Matthew; Bailey, Elizabeth A.; Schmidt, Jeanine M.; Shew, Nora B.; Gamble, Bruce M.; Labay, Keith A.

    2011-01-01

    The Alaska Geochemical Database (AGDB) was created and designed to compile and integrate geochemical data from Alaska in order to facilitate geologic mapping, petrologic studies, mineral resource assessments, definition of geochemical baseline values and statistics, environmental impact assessments, and studies in medical geology. This Microsoft Access database serves as a data archive in support of present and future Alaskan geologic and geochemical projects, and contains data tables describing historical and new quantitative and qualitative geochemical analyses. The analytical results were determined by 85 laboratory and field analytical methods on 264,095 rock, sediment, soil, mineral and heavy-mineral concentrate samples. Most samples were collected by U.S. Geological Survey (USGS) personnel and analyzed in USGS laboratories or, under contracts, in commercial analytical laboratories. These data represent analyses of samples collected as part of various USGS programs and projects from 1962 to 2009. In addition, mineralogical data from 18,138 nonmagnetic heavy mineral concentrate samples are included in this database. The AGDB includes historical geochemical data originally archived in the USGS Rock Analysis Storage System (RASS) database, used from the mid-1960s through the late 1980s and the USGS PLUTO database used from the mid-1970s through the mid-1990s. All of these data are currently maintained in the Oracle-based National Geochemical Database (NGDB). Retrievals from the NGDB were used to generate most of the AGDB data set. These data were checked for accuracy regarding sample location, sample media type, and analytical methods used. This arduous process of reviewing, verifying and, where necessary, editing all USGS geochemical data resulted in a significantly improved Alaska geochemical dataset. USGS data that were not previously in the NGDB because the data predate the earliest USGS geochemical databases, or were once excluded for programmatic reasons

  15. Towards sustainable groundwater management in Karst aquifers in semi-arid environments: Central West Bank, Palestine

    Science.gov (United States)

    Jebreen, H.; Banning, A.; Wohnlich, S.

    2017-12-01

    The Central West Bank (CWB) is characterized by karstified carbonate aquifers in the semiarid climate zone, where groundwater resources are frequently threatened by overexploitation and pollution. Despite often limited system knowledge, quantitative and qualitative factors such as groundwater recharge rate, aquifer parameters, flow and transport dynamics, anthropogenic impacts, and groundwater vulnerability need to be assessed. Therefore, sustainable groundwater use in the CWB is of critical importance. In the present study, we explore the scale of the groundwater problems in CWB as well as the possibility of sustainable management through different scenarios: 1) Managed aquifer recharge using a water balance model, stable isotopes (2H & 18O) and chloride mass balance, 2) Geochemical evolution and renewability of groundwater, and 3) Anthropogenic impacts. A total of 20 spring water samples were collected and analyzed for pH, electrical conductivity, total dissolved solids (TDS), hardness, major-ion chemistry (Cl-, HCO3-, SO42-, Na+, K+, Ca2+ and Mg2+), trace elements (Li, Be, Al, Ba, Tl, Pb, Bi, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Rb, Sr, Mo, Ag and Cd), microbiological data (total and fecal coliforms bacteria), and stable isotopes (2H & 18O). The results show a spatialized recharge rate, which ranges from 111-211 mm/year, representing 17-33 % of the long-term mean annual rainfall. The mean annual actual evapotranspiration was about 19-37 % of precipitation. The chemical composition of groundwater of the study area is strongly influenced by rock-water interaction, dissolution and deposition of carbonate and silicate minerals. Stable isotopes show that precipitation is the source of recharge to the groundwater system. All analyzed spring waters are suitable for irrigation but not for drinking purposes. This studýs results can serve as a basis for decision makers, and will lead to an increased understanding of the sustainable management of the Central West Bank

  16. Rare earth elements and uranium in groundwater under influence of distinct aquifers in Campinas, SP, Brazil; Elementos terras raras e uranio em aguas subterraneas sob influencia de aquiferos distintos em Campinas (SP)

    Energy Technology Data Exchange (ETDEWEB)

    Bulia, Isabella Longhi; Enzweiler, Jacinta, E-mail: isabellalonghi@ige.unicamp.br, E-mail: jacinta@ige.unicamp.br [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Instituto de Geociencias

    2015-07-01

    The composition of groundwaters results mainly from water-rock reactions within aquifers. Among the various constituents of water, the rare earth elements (REE) and uranium can serve as tracers of geochemical processes and hydrological flow paths. The main objective of this study was to associate the chemical composition of groundwaters extracted from three distinct aquifer systems (crystalline, diabase and sedimentary) with that of the respective hosts rocks. The area of the study is located at the campus of University of Campinas (Campinas, SP). Samples of groundwater collected from four tubular wells were used to determine physicochemical parameters, major ions and trace elements, including the REE. The results confirm that the water of two wells (IMECC and IB) is predominantly influenced by the crystalline and diabase aquifers, while the other two (GM and FEF) by the sedimentary aquifer. Both the individual and normalized REE values of the four wells are distinct from each other, pointing to the heterogeneity of the local geology. The uranium concentration in the water of one well (GM) exceeded the guideline value for this element in drinking water. The U probably results from the oxidative dissolution of U-bearing phases in the sedimentary aquifer. However, the hydrochemical modeling indicated Ca{sub 2}UO{sub 2}(CO{sub 3}){sub 3} and CaUO{sub 2}(CO{sub 3}){sub 2}{sup 2-} as the major U dissolved species, which are considered non-toxic and non-bioavailable according to literature data. (author)

  17. Relationship between tectonic structures and hydrogeochemical compartmentalization in aquifers: Example of the “Jeffara de Medenine” system, south–east Tunisia

    Directory of Open Access Journals (Sweden)

    Hayet Chihi

    2015-09-01

    The kriged maps of major-ion concentrations and of total dissolved solids in the aquifers were then analyzed and compared with the reservoir facies distribution for each compartment, the geometric characteristics of the aquifer, and the piezometric level trends. This allowed to characterize the hydraulic behavior of the Medenine fault and to understand the underlying physical and chemical processes having led to the spatial distribution of the geochemical properties, and thus, the hydrogeochemical functioning of the aquifers.

  18. Determining Changes in Groundwater Quality during Managed Aquifer Recharge

    Science.gov (United States)

    Gambhir, T.; Houlihan, M.; Fakhreddine, S.; Dadakis, J.; Fendorf, S. E.

    2016-12-01

    Managed aquifer recharge (MAR) is becoming an increasingly prevalent technology for improving the sustainability of freshwater supply. However, recharge water can alter the geochemical conditions of the aquifer, mobilizing contaminants native to the aquifer sediments. Geochemical alterations on deep (>300 m) injection of highly treated recycled wastewater for MAR has received limited attention. We aim to determine how residual disinfectants used in water treatment processes, specifically the strong oxidants chloramine and hydrogen peroxide, affect metal mobilization within deep injection wells of the Orange County Water District. Furthermore, as the treated recharge water has very low ionic strength (44.6 mg L-1 total dissolved solids), we tested how differing concentrations of magnesium chloride and calcium chloride affected metal mobilization within deep aquifers. Continuous flow experiments were conducted on columns dry packed with sediments from a deep injection MAR site in Orange County, CA. The effluent was analyzed for shifts in water quality, including aqueous concentrations of arsenic, uranium, and chromium. Interaction between the sediment and oxic recharge solution causes naturally-occurring arsenopyrite to repartition onto iron oxides. The stability of arsenic on the newly precipitated iron oxides is dependent on pH changes during recharge.

  19. Identifying functional zones of denitrification in heterogeneous aquifer systems by numerical simulations - a case study

    Science.gov (United States)

    Jang, E.; Kalbacher, T.; He, W.; Shao, H.; Schueth, C.; Kolditz, O.

    2014-12-01

    Nitrate contamination in shallow groundwater is still one of the common problems in many countries. Because of its high solubility and anionic nature, nitrate can easily leach through soil and persist in groundwater for decades. High nitrate concentration has been suggested as a major cause of accelerated eutrophication, methemoglobinemia and gastric cancer. There are several factors influencing the fate of nitrate in groundwater system, which is e.g. distribution of N- sources to soil and groundwater, distribution and amount of reactive substances maintaining denitrification, rate of nitrate degradation and its kinetics, and geological characteristics of the aquifer. Nitrate transport and redox transformation processes are closely linked to complex and spatially distributed physical and chemical interaction, therefore it is difficult to predict and quantify in the field and laboratory experiment. Models can play a key role in elucidation of nitrate reduction pathway in groundwater system and in the design and evaluation of field tests to investigate in situ remediation technologies as well. The goal of the current study is to predict groundwater vulnerability to nitrate, to identify functional zones of denitrification in heterogeneous aquifer systems and to describe the uncertainty of the predictions due to scale effects. For this aim, we developed a kinetic model using multi-component mass transport code OpenGeoSys coupling with IPhreeqc module of the geochemical solver PHREEQC. The developed model included sequential aerobic and nitrate-based respiration, multi-Monod kinetics, multi-species biogeochemical reactions, and geological characteristics of the groundwater aquifer. Moreover water-rock interaction such as secondary mineral precipitation was also included in this model. In this presentation, we focused on the general modelling approach and present the simulation results of nitrate transport simulation in a hypothetical aquifer systems based on data from

  20. Geochemical Characteristics of Shallow Groundwater in Jiaoshiba Shale Gas Production Area: Implications for Environmental Concerns

    Directory of Open Access Journals (Sweden)

    Yiman Li

    2016-11-01

    Full Text Available The geochemical characteristics of shallow groundwater are essential for environmental impact studies in the shale gas production area. Jiaoshiba in the Sichuan basin is the first commercial-scale shale gas production area in China. This paper studied the geochemical and isotopic characteristics of the shallow groundwater of the area for future environmental concerns. Results show that the average pH of the shallow groundwater is 7.5 and the total dissolved solids (TDS vary from 150 mg/L to 350 mg/L. The main water types are HCO3-Ca and HCO3-Ca·Mg due to the carbonates dissolution equilibrium in karst aquifers. The concentrations of major ions and typical toxic elements including Mn, Cr, Cu, Zn, Ba, and Pb are below the drinking water standard of China and are safe for use as drinking water. The high nitrate content is inferred to be caused by agricultural pollution. The shallow groundwater is recharged by local precipitation and flows in the vertical circulation zone. Evidences from low TDS, water isotopes, and high 3H and 14C indicate that the circulation rate of shallow groundwater is rapid, and the lateral groundwater has strong renewability. Once groundwater pollution from deep shale gas production occurs, it will be recovered soon by enough precipitation.

  1. Version 4. 00 of the MINTEQ geochemical code

    Energy Technology Data Exchange (ETDEWEB)

    Eary, L.E.; Jenne, E.A.

    1992-09-01

    The MINTEQ code is a thermodynamic model that can be used to calculate solution equilibria for geochemical applications. Included in the MINTEQ code are formulations for ionic speciation, ion exchange, adsorption, solubility, redox, gas-phase equilibria, and the dissolution of finite amounts of specified solids. Since the initial development of the MINTEQ geochemical code, a number of undocumented versions of the source code and data files have come into use at the Pacific Northwest Laboratory (PNL). This report documents these changes, describes source code modifications made for the Aquifer Thermal Energy Storage (ATES) program, and provides comprehensive listings of the data files. A version number of 4.00 has been assigned to the MINTEQ source code and the individual data files described in this report.

  2. Version 4.00 of the MINTEQ geochemical code

    Energy Technology Data Exchange (ETDEWEB)

    Eary, L.E.; Jenne, E.A.

    1992-09-01

    The MINTEQ code is a thermodynamic model that can be used to calculate solution equilibria for geochemical applications. Included in the MINTEQ code are formulations for ionic speciation, ion exchange, adsorption, solubility, redox, gas-phase equilibria, and the dissolution of finite amounts of specified solids. Since the initial development of the MINTEQ geochemical code, a number of undocumented versions of the source code and data files have come into use at the Pacific Northwest Laboratory (PNL). This report documents these changes, describes source code modifications made for the Aquifer Thermal Energy Storage (ATES) program, and provides comprehensive listings of the data files. A version number of 4.00 has been assigned to the MINTEQ source code and the individual data files described in this report.

  3. Application of cluster analysis to geochemical compositional data for identifying ore-related geochemical anomalies

    Science.gov (United States)

    Zhou, Shuguang; Zhou, Kefa; Wang, Jinlin; Yang, Genfang; Wang, Shanshan

    2017-12-01

    Cluster analysis is a well-known technique that is used to analyze various types of data. In this study, cluster analysis is applied to geochemical data that describe 1444 stream sediment samples collected in northwestern Xinjiang with a sample spacing of approximately 2 km. Three algorithms (the hierarchical, k-means, and fuzzy c-means algorithms) and six data transformation methods (the z-score standardization, ZST; the logarithmic transformation, LT; the additive log-ratio transformation, ALT; the centered log-ratio transformation, CLT; the isometric log-ratio transformation, ILT; and no transformation, NT) are compared in terms of their effects on the cluster analysis of the geochemical compositional data. The study shows that, on the one hand, the ZST does not affect the results of column- or variable-based (R-type) cluster analysis, whereas the other methods, including the LT, the ALT, and the CLT, have substantial effects on the results. On the other hand, the results of the row- or observation-based (Q-type) cluster analysis obtained from the geochemical data after applying NT and the ZST are relatively poor. However, we derive some improved results from the geochemical data after applying the CLT, the ILT, the LT, and the ALT. Moreover, the k-means and fuzzy c-means clustering algorithms are more reliable than the hierarchical algorithm when they are used to cluster the geochemical data. We apply cluster analysis to the geochemical data to explore for Au deposits within the study area, and we obtain a good correlation between the results retrieved by combining the CLT or the ILT with the k-means or fuzzy c-means algorithms and the potential zones of Au mineralization. Therefore, we suggest that the combination of the CLT or the ILT with the k-means or fuzzy c-means algorithms is an effective tool to identify potential zones of mineralization from geochemical data.

  4. Hydro geochemistry and isotopic approach of coastal aquifer systems of Cap Bon : The case of tablecloths and the eastern coast of El Haourai - Tunisia

    International Nuclear Information System (INIS)

    Ben Hammouda, Fethi

    2008-01-01

    As many other semi-arid regions, the Cap Bon peninsula (N.E. Tunisia) shows a parallel increase in overexploitation and mineralization of groundwater resources. In the eastern coast and El Haouaria aquifers, the groundwater quality is threatened. Surveys including level measurements, water sampling, chemical analysis (ions Na+, Cl., Ca2+, Mg2+, Br.) and sotopes (18O, 2H, 3H, 13C, 14C) were performed in 2001, 2002 and 2003. Several analysis types were conducted and results are compared with the hydrodynamic information for identifying the main processes involved in the mineralization increase. Particularly, the isotopes were permitting the understanding of the hydrogeological of the concerned aquifers and the localization of the recharge zones. Because the regional situation along the seashore, the seawater intrusion in the unconfined Plio-quaternary aquifer, resulting from the groundwater overexploitation, and obvious explanation for the rising salinity is identified but is not the only cause of the qualitative degradation: the irrigation development that induces the soil leaching and the fertilizers transfer to groundwater over the whole aquifer extent is another major reason of the mineralization increase. Piezometric and salinity maps of the Plio-quaternary aquifer were established. The continuous increase in pumping has created several depressions in the water table, up to 12 m below msl and induced a deterioration of the water quality. The temporal changes in water-table level and salinity are often similar which suggests a strong link between them. Several geochemical approaches were performed to identify the importance of the marine intrusion in the increase in mineralization. The salinity of the groundwater appears to originate from dissolution of minerals in the aquifer system

  5. Quantification of anthropogenic impact on groundwater-dependent terrestrial ecosystem using geochemical and isotope tools combined with 3-D flow and transport modelling

    Science.gov (United States)

    Zurek, A. J.; Witczak, S.; Dulinski, M.; Wachniew, P.; Rozanski, K.; Kania, J.; Postawa, A.; Karczewski, J.; Moscicki, W. J.

    2015-02-01

    Groundwater-dependent ecosystems (GDEs) have important functions in all climatic zones as they contribute to biological and landscape diversity and provide important economic and social services. Steadily growing anthropogenic pressure on groundwater resources creates a conflict situation between nature and man which are competing for clean and safe sources of water. Such conflicts are particularly noticeable in GDEs located in densely populated regions. A dedicated study was launched in 2010 with the main aim to better understand the functioning of a groundwater-dependent terrestrial ecosystem (GDTE) located in southern Poland. The GDTE consists of a valuable forest stand (Niepolomice Forest) and associated wetland (Wielkie Błoto fen). It relies mostly on groundwater from the shallow Quaternary aquifer and possibly from the deeper Neogene (Bogucice Sands) aquifer. In July 2009 a cluster of new pumping wells abstracting water from the Neogene aquifer was set up 1 km to the northern border of the fen. A conceptual model of the Wielkie Błoto fen area for the natural, pre-exploitation state and for the envisaged future status resulting from intense abstraction of groundwater through the new well field was developed. The main aim of the reported study was to probe the validity of the conceptual model and to quantify the expected anthropogenic impact on the studied GDTE. A wide range of research tools was used. The results obtained through combined geologic, geophysical, geochemical, hydrometric and isotope investigations provide strong evidence for the existence of upward seepage of groundwater from the deeper Neogene aquifer to the shallow Quaternary aquifer supporting the studied GDTE. Simulations of the groundwater flow field in the study area with the aid of a 3-D flow and transport model developed for Bogucice Sands (Neogene) aquifer and calibrated using environmental tracer data and observations of hydraulic head in three different locations on the study area

  6. Why 1D electrical resistivity techniques can result in inaccurate siting of boreholes in hard rock aquifers and why electrical resistivity tomography must be preferred: the example of Benin, West Africa

    Science.gov (United States)

    Alle, Iboukoun Christian; Descloitres, Marc; Vouillamoz, Jean-Michel; Yalo, Nicaise; Lawson, Fabrice Messan Amen; Adihou, Akonfa Consolas

    2018-03-01

    Hard rock aquifers are of particular importance for supplying people with drinking water in Africa and in the world. Although the common use of one-dimensional (1D) electrical resistivity techniques to locate drilling site, the failure rate of boreholes is usually high. For instance, about 40% of boreholes drilled in hard rock aquifers in Benin are unsuccessful. This study investigates why the current use of 1D techniques (e.g. electrical profiling and electrical sounding) can result in inaccurate siting of boreholes, and checks the interest and the limitations of the use of two-dimensional (2D) Electrical Resistivity Tomography (ERT). Geophysical numerical modeling and comprehensive 1D and 2D resistivity surveys were carried out in hard rock aquifers in Benin. The experiments carried out at 7 sites located in different hard rock groups confirmed the results of the numerical modeling: the current use of 1D techniques can frequently leads to inaccurate siting, and ERT better reveals hydrogeological targets such as thick weathered zone (e.g. stratiform fractured layer and preferential weathering associated with subvertical fractured zone). Moreover, a cost analysis demonstrates that the use of ERT can save money at the scale of a drilling programme if ERT improves the success rate by only 5% as compared to the success rate obtained with 1D techniques. Finally, this study demonstrates, using the example of Benin, that the use of electrical resistivity profiling and sounding for siting boreholes in weathered hard rocks of western Africa should be discarded and replaced by the use of ERT technique, more efficient.

  7. Groundwater-quality data in the Santa Cruz, San Gabriel, and Peninsular Ranges Hard Rock Aquifers study unit, 2011-2012: results from the California GAMA program

    Science.gov (United States)

    Davis, Tracy A.; Shelton, Jennifer L.

    2014-01-01

    Groundwater quality in the 2,400-square-mile Santa Cruz, San Gabriel, and Peninsular Ranges Hard Rock Aquifers (Hard Rock) study unit was investigated by the U.S. Geological Survey (USGS) from March 2011 through March 2012, as part of the California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring and Assessment (GAMA) Program’s Priority Basin Project (PBP). The GAMA-PBP was developed in response to the California Groundwater Quality Monitoring Act of 2001 and is being conducted in collaboration with the SWRCB and Lawrence Livermore National Laboratory (LLNL). The Hard Rock study unit was the 35th study unit to be sampled as part of the GAMA-PBP.

  8. Analysis of mineral trapping for CO{sub 2} disposal in deep aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tianfu; Apps, John A.; Pruess, Karsten

    2001-07-20

    CO{sub 2} disposal into deep aquifers has been suggested as a potential means whereby atmospheric emissions of greenhouse gases may be reduced. However, our knowledge of the geohydrology, geochemistry, geophysics, and geomechanics of CO{sub 2} disposal must be refined if this technology is to be implemented safely, efficiently, and predictably. As a prelude to a fully coupled treatment of physical and chemical effects of CO{sub 2} injection, we have analyzed the impact of CO{sub 2} immobilization through carbonate precipitation. A survey of all major classes of rock-forming minerals, whose alteration would lead to carbonate precipitation, indicated that very few minerals are present in sufficient quantities in aquifer host rocks to permit significant sequestration of CO{sub 2}. We performed batch reaction modeling of the geochemical evolution of three different aquifer mineralogies in the presence of CO{sub 2} at high pressure. Our modeling considered (1) redox processes that could be important in deep subsurface environments, (2) the presence of organic matter, (3) the kinetics of chemical interactions between the host rock minerals and the aqueous phase, and (4) CO{sub 2} solubility dependence on pressure, temperature and salinity of the system. The geochemical evolution under both natural background and CO{sub 2} injection conditions was evaluated. In addition, changes in porosity were monitored during the simulations. Results indicate that CO{sub 2} sequestration by matrix minerals varies considerably with rock type. Under favorable conditions the amount of CO{sub 2} that may be sequestered by precipitation of secondary carbonates is comparable with and can be larger than the effect of CO{sub 2} dissolution in pore waters. The precipitation of ankerite and siderite is sensitive to the rate of reduction of ferric mineral precursors such as glauconite, which in turn is dependent on the reactivity of associated organic material. The accumulation of carbonates in

  9. Analysis of mineral trapping for CO(sub 2) disposal in deep aquifers; TOPICAL

    International Nuclear Information System (INIS)

    Xu, Tianfu; Apps, John A.; Pruess, Karsten

    2001-01-01

    CO(sub 2) disposal into deep aquifers has been suggested as a potential means whereby atmospheric emissions of greenhouse gases may be reduced. However, our knowledge of the geohydrology, geochemistry, geophysics, and geomechanics of CO(sub 2) disposal must be refined if this technology is to be implemented safely, efficiently, and predictably. As a prelude to a fully coupled treatment of physical and chemical effects of CO(sub 2) injection, we have analyzed the impact of CO(sub 2) immobilization through carbonate precipitation. A survey of all major classes of rock-forming minerals, whose alteration would lead to carbonate precipitation, indicated that very few minerals are present in sufficient quantities in aquifer host rocks to permit significant sequestration of CO(sub 2). We performed batch reaction modeling of the geochemical evolution of three different aquifer mineralogies in the presence of CO(sub 2) at high pressure. Our modeling considered (1) redox processes that could be important in deep subsurface environments, (2) the presence of organic matter, (3) the kinetics of chemical interactions between the host rock minerals and the aqueous phase, and (4) CO(sub 2) solubility dependence on pressure, temperature and salinity of the system. The geochemical evolution under both natural background and CO(sub 2) injection conditions was evaluated. In addition, changes in porosity were monitored during the simulations. Results indicate that CO(sub 2) sequestration by matrix minerals varies considerably with rock type. Under favorable conditions the amount of CO(sub 2) that may be sequestered by precipitation of secondary carbonates is comparable with and can be larger than the effect of CO(sub 2) dissolution in pore waters. The precipitation of ankerite and siderite is sensitive to the rate of reduction of ferric mineral precursors such as glauconite, which in turn is dependent on the reactivity of associated organic material. The accumulation of carbonates in

  10. Occurrence and geochemical behavior of arsenic in a coastal aquifer–aquitard system of the Pearl River Delta, China

    International Nuclear Information System (INIS)

    Wang, Ya; Jiao, Jiu Jimmy; Cherry, John A.

    2012-01-01

    Elevated concentrations of arsenic, up to 161 μg/L, have been identified in groundwater samples from the confined basal aquifer underlying the aquitard of the Pearl River Delta (PRD). Both aquatic arsenic in pore water and solid arsenic in the sediments in the basal aquifer and aquitard were identified. Arsenic speciation of groundwater in the basal aquifer was elucidated on a pH-Eh diagram. In the PRD, arsenic is enriched in groundwater having both low and high salinity, and arsenic enriched groundwater is devoid of dissolved oxygen, has negative Eh values, is slightly alkaline, and has abnormally high concentrations of ammonium and dissolved organic carbon, but low concentrations of nitrate and nitrite. Results of geochemical and hydrochemical analyses and sequential extraction analysis suggest that reductive dissolution of iron oxyhydroxide could be one of the important processes that mobilized solid arsenic. We speculate that mineralization of sedimentary organic matter could also contribute to aquatic arsenic. Scanning electron microscope analysis confirms that abundant authigenic pyrite is present in the sediments. Sulphate derived from paleo-seawater served as the important sulfur source for authigenic pyrite formation. Co-precipitation of arsenic with authigenic pyrite significantly controlled concentrations of aquatic arsenic in the coastal aquifer–aquitard system. - Highlights: ► Coastal aquifer and aquitard are treated as an integrate system. ► Both aquatic arsenic and solid arsenic are observed. ► Aquatic arsenic is derived from reductive dissolution of iron oxyhydroxide. ► Aquatic arsenic can also derived from mineralization of sedimentary organic matter. ► Co-precipitation of arsenic with authigenic pyrite is significant in such a system.

  11. Comment on An Alternative View on the Origin of Chemical and Isotopic Patterns in Groundwater From the Milk River Aquifer, Canada by M.J. Hendry and F.W. Schwartz

    International Nuclear Information System (INIS)

    Phillips, F.M.; Knowlton, R.G.; Bentley, H.W.

    1990-01-01

    The Milk River aquifer in southern Alberta combines apparently simple, classical confined aquifer hydrodynamics with somewhat enigmatic groundwater geochemistry of conservative solutes. Over the past 10 years, five major papers have focused on the geochemistry of Milk River aquifer groundwater. Most recently, Hendry and Schwartz (1988) have proposed a different mechanism, aquitard diffusion, to explain the Milk River geochemistry. They described and evaluated previously proposed geochemical processes, especially ion filtration. Hendry and Schwartz (1988) concluded that ion filtration and the other proposed mechanisms were not supported by the data. They then described the aquitard diffusion mechanism and used a simple analytical model to simulate observed aquifer trends in Cl - and 18 O. From the results of this exercise they concluded that diffusion from the aquitards was controlling the solute distributions in the aquifer. Finally, they interpreted previously published 36 Cl data and new profiles of Cl - in the aquitards in terms of the diffusion model. Upon review, the authors do not find the arguments against ion filtration to be as damaging as Hendry and Schwartz indicate, nor do they find the evidence for aquitard diffusion to be as persuasive. In this study they will first evaluate Hendry and Schwartz's arguments against ion filtration, then they will review the arguments in favor of aquitard diffusion, and finally the authors will address the implications for the interpretation of the vertical Cl - profiles and the 36 Cl data

  12. Mercury mobilization and speciation linked to bacterial iron oxide and sulfate reduction: A column study to mimic reactive transfer in an anoxic aquifer.

    Science.gov (United States)

    Hellal, Jennifer; Guédron, Stéphane; Huguet, Lucie; Schäfer, Jörg; Laperche, Valérie; Joulian, Catherine; Lanceleur, Laurent; Burnol, André; Ghestem, Jean-Philippe; Garrido, Francis; Battaglia-Brunet, Fabienne

    2015-09-01

    Mercury (Hg) mobility and speciation in subsurface aquifers is directly linked to its surrounding geochemical and microbial environment. The role of bacteria on Hg speciation (i.e., methylation, demethylation and reduction) is well documented, however little data is available on their impact on Hg mobility. The aim of this study was to test if (i) Hg mobility is due to either direct iron oxide reduction by iron reducing bacteria (IRB) or indirect iron reduction by sulfide produced by sulfate reducing bacteria (SRB), and (ii) to investigate its subsequent fate and speciation. Experiments were carried out in an original column setup combining geochemical and microbiological approaches that mimic an aquifer including an interface of iron-rich and iron depleted zones. Two identical glass columns containing iron oxides spiked with Hg(II) were submitted to (i) direct iron reduction by IRB and (ii) to indirect iron reduction by sulfides produced by SRB. Results show that in both columns Hg was leached and methylated during the height of bacterial activity. In the column where IRB are dominant, Hg methylation and leaching from the column was directly correlated to bacterial iron reduction (i.e., Fe(II) release). In opposition, when SRB are dominant, produced sulfide induced indirect iron oxide reduction and rapid adsorption of leached Hg (or produced methylmercury) on neoformed iron sulfides (e.g., Mackinawite) or its precipitation as HgS. At the end of the SRB column experiment, when iron-oxide reduction was complete, filtered Hg and Fe concentrations increased at the outlet suggesting a leaching of Hg bound to FeS colloids that may be a dominant mechanism of Hg transport in aquifer environments. These experimental results highlight different biogeochemical mechanisms that can occur in stratified sub-surface aquifers where bacterial activities play a major role on Hg mobility and changes in speciation. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. A Black Hills-Madison Aquifer origin for Dakota Aquifer groundwater in northeastern Nebraska.

    Science.gov (United States)

    Stotler, Randy; Harvey, F Edwin; Gosselin, David C

    2010-01-01

    Previous studies of the Dakota Aquifer in South Dakota attributed elevated groundwater sulfate concentrations to Madison Aquifer recharge in the Black Hills with subsequent chemical evolution prior to upward migration into the Dakota Aquifer. This study examines the plausibility of a Madison Aquifer origin for groundwater in northeastern Nebraska. Dakota Aquifer water samples were collected for major ion chemistry and isotopic analysis ((18)O, (2)H, (3)H, (14)C, (13)C, (34)S, (18)O-SO(4), (87)Sr, (37)Cl). Results show that groundwater beneath the eastern, unconfined portion of the study area is distinctly different from groundwater sampled beneath the western, confined portion. In the east, groundwater is calcium-bicarbonate type, with delta(18)O values (-9.6 per thousand to -12.4 per thousand) similar to local, modern precipitation (-7.4 per thousand to -10 per thousand), and tritium values reflecting modern recharge. In the west, groundwater is calcium-sulfate type, having depleted delta(18)O values (-16 per thousand to -18 per thousand) relative to local, modern precipitation, and (14)C ages 32,000 to more than 47,000 years before present. Sulfate, delta(18)O, delta(2)H, delta(34)S, and delta(18)O-SO(4) concentrations are similar to those found in Madison Aquifer groundwater in South Dakota. Thus, it is proposed that Madison Aquifer source water is also present within the Dakota Aquifer beneath northeastern Nebraska. A simple Darcy equation estimate of groundwater velocities and travel times using reported physical parameters from the Madison and Dakota Aquifers suggests such a migration is plausible. However, discrepancies between (14)C and Darcy age estimates indicate that (14)C ages may not accurately reflect aquifer residence time, due to mixtures of varying aged water.

  14. Spatial Distribution of Field Physico-Chemical Parameters in the Vulcano Island (Italy Coastal Aquifer: Volcanological and Hydrogeological Implications

    Directory of Open Access Journals (Sweden)

    Paolo Madonia

    2015-06-01

    Full Text Available Vulcano, the southernmost of the Aeolian island arc (Italy, is characterized by a shallow coastal aquifer resulting from the mixing of seawater, meteoric recharge and volcanogenic fluids. The aquifer has been intensively studied during the last decades, but a comprehensive hydrogeological model has never been developed due to the lack of direct information about the litho-stratigraphic columns of the wells and the depth of water bearing levels. We present and discuss here the time and spatial analysis of water table elevation, temperature and electric conductivity data, acquired during the last 20 years in 33 wells located at Vulcano Island, with the aim of developing a groundwater circulation scheme able to fit the field observations. We retrieved a circulation scheme characterized by an intricate geometry of flow paths driven by horizontal and vertical permeability variations, accounting for the strong variability of geochemical data evidenced in this area by the related scientific literature. Extending these results to a general context, particular care must be taken in approaching the study of aquifers in volcanic islands, because a strong, small spatial scale variability of the hydrogeochemical parameters is expected, and a reliable knowledge of the local conditions is required for developing successful groundwater circulation schemes.

  15. EPA Sole Source Aquifers

    Data.gov (United States)

    U.S. Environmental Protection Agency — Information on sole source aquifers (SSAs) is widely used in assessments under the National Environmental Policy Act and at the state and local level. A national...

  16. Tracers Detect Aquifer Contamination

    National Research Council Canada - National Science Library

    Enfield, Carl

    1995-01-01

    The EPA's National Laboratory (NRMRL) at Ada, OK, along with the University of Florida and the University of Texas, have developed a tracer procedure to detect the amount of contamination in aquifer formations...

  17. Assessment of microbial in situ activity in contaminated aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Kaestner, M. [UFZ-Umweltforschungszentrum Leipzig-Halle GmbH, Department Bioremediation, Permoserstrasse 15, 04318 Leipzig (Germany); Fischer, A.; Nijenhuis, I.; Stelzer, N.; Bombach, P.; Richnow, H.H. [UFZ-Umweltforschungszentrum Leipzig-Halle GmbH, Department Isotopenbiogeochemie, Permoserstrasse 15, 04318 Leipzig (Germany); Geyer, R. [UFZ-Umweltforschungszentrum Leipzig-Halle GmbH, Department Umweltmikrobiologie, Permoserstrasse 15, 04318 Leipzig (Germany); Tebbe, C.C. [Institut fuer Agraroekologie, Bundesforschungsanstalt fuer Landwirtschaft (FAL), D-38116 Braunschweig (Germany)

    2006-06-15

    Microbial ecologists and environmental engineers share the interest in identifying the key microorganisms responsible for compound turnover in the environment and in estimating the respective transformation rates. For the successful application of Natural Attenuation processes, a reliable assessment of the in situ turnover of a contaminant in an aquifer is essential. Here, we review and present new details of two recently developed approaches concerning the assessment of in situ biodegradation: (i) determination of biodegradation caused by microbial metabolism in a contamination plume by stable isotope fractionation analysis (SIFA) and (ii) determination of the actual degradation under the respective environmental conditions in the aquifer by using in situ microcosms (BACTRAPS registered) amended with {sup 13}C-labeled substrates as tracer compounds. Based on stable isotope fractionation analysis, the degradation occurring under anoxic biogeochemical conditions at a respective site can be calculated for the entire plume. This has been shown for benzene and toluene at the Zeitz site and partly for chlorobenzene at the Bitterfeld site. By use of the in situ microcosm approach with {sup 13}C-labeled compounds, the microbial in situ degradation under strictly anaerobic conditions could be proven for benzene and toluene in Zeitz and for chlorobenzene in Bitterfeld. The transformation of {sup 13}C-carbon of the labeled substrate into microbial fatty acids confirmed the assimilation of the pollutant resulting in the formation of biomass. In addition, metabolites such as benzylsuccinic acid were found in the toluene-amended microcosms indicating anaerobic degradation of toluene. This result corresponds to the geochemical conditions found at the field site and therefore, the microcosm approach with {sup 13}C-labeled compounds can be used to assign the predominant in situ degradation pathways in a contaminated aquifer. Since fatty acids profiles alone are often too

  18. Geochemical controls on the composition of soil pore waters beneath a mixed waste disposal site in the unsaturated zone

    International Nuclear Information System (INIS)

    Rawson, S.A.; Hubbell, J.M.

    1989-01-01

    Soil pore waters are collected routinely to monitor a thick unsaturated zone that separates a mixed waste disposal site containing transuranic and low-level radioactive wastes from the Snake River Plain aquifer. The chemistry of the soil pore waters has been studied to evaluate the possible control on the water composition by mineral equilibria and determine the extent, if any, of migration of radionuclides from the disposal site. Geochemical codes were used to perform speciation calculations for the waters. The results of speciation calculations suggest that the installation of the lysimeters affects the observed silica contents of the soil pore waters. The results also establish those chemical parameters that are controlled by secondary mineral precipitation. 15 refs., 6 figs., 1 tab

  19. Ogallala Aquifer Mapping Program

    International Nuclear Information System (INIS)

    1984-10-01

    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

  20. Hydrogeochemical Impact of CO2 Leakage from Geological Sequestration on Shallow Potable Aquifers

    DEFF Research Database (Denmark)

    Cahill, Aaron Graham

    . Although considered highly unlikely following appropriate site selection, leakage of CO2 from CCGS forms a major concern for both scientists and the public. Leakage would potentially occur through faults or abandoned boreholes and ultimately result in upward migration and discharge to the atmosphere....... During migration CO2 would dissolve into groundwater forming carbonic acid, induce water-rock reactions and thus change groundwater chemistry. Therefore prior to implementation of this potentially necessary technology, environmental risks associated with leakage must be understood. Over the past 10 years...... it be detected geochemically? Some common hydrochemical development is apparent from the literature however many aspects of hydrogeological and hydrogeochemical impact of leakage into shallow aquifers used in water supply remain unclear. In this Ph.D. study an integrated approach was employed in order to answer...

  1. New isotopic evidence for the origin of groundwater from the Nubian Sandstone Aquifer in the Negev, Israel

    Science.gov (United States)

    Vengosh, A.; Hening, S.; Ganor, J.; Mayer, B.; Weyhenmeyer, C.E.; Bullen, T.D.; Paytan, A.

    2007-01-01

    The geochemistry and isotopic composition (H, O, S, Osulfate, C, Sr) of groundwater from the Nubian Sandstone (Kurnub Group) aquifer in the Negev, Israel, were investigated in an attempt to reconstruct the origin of the water and solutes, evaluate modes of water-rock interactions, and determine mean residence times of the water. The results indicate multiple recharge events into the Nubian sandstone aquifer characterized by distinctive isotope signatures and deuterium excess values. In the northeastern Negev, groundwater was identified with deuterium excess values of ???16???, which suggests local recharge via unconfined areas of the aquifer in the Negev anticline systems. The ??18OH2O and ??2H values (-6.5??? and -35.4???) of this groundwater are higher than those of groundwater in the Sinai Peninsula and southern Arava valley (-7.5??? and -48.3???) that likewise have lower deuterium excess values of ???10???. Based on the geochemical differences between groundwater in the unconfined and confined zones of the aquifer, a conceptual geochemical model for the evolution of the groundwater in the Nubian sandstone aquifer has been reconstructed. The isotopic composition of shallow groundwater from the unconfined zone indicates that during recharge oxidation of pyrite to SO4 (??34SSO4 ???-13???; ??18OSO4 ???+7.7???) and dissolution of CaCO3 (87Sr/86Sr ???0.70787; ??13CDIC = -3.7???) occur. In the confined zone of the aquifer, bacterial SO4 reduction removes a significant part of dissolved SO42 -, thereby modifying its isotopic composition (??34SSO4 ???-2???; ??18OSO4 ???+8.5???) and liberating dissolved inorganic C that contains little or no radiocarbon (14C-free) with low ??13CDIC values (contribution of external groundwater sources to the Nubian Sandstone aquifer, resulting in further modifications of the groundwater chemical and isotopic signatures. In the northeastern Negev, it is shown that SO4-rich groundwater from the underlying Jurassic aquifer contributes

  2. Anoxic nitrate reduction coupled with iron oxidation and attenuation of dissolved arsenic and phosphate in a sand and gravel aquifer

    Science.gov (United States)

    Smith, Richard L.; Kent, Douglas B.; Repert, Deborah A.; Böhlke, J.K.

    2017-01-01

    Nitrate has become an increasingly abundant potential electron acceptor for Fe(II) oxidation in groundwater, but this redox couple has not been well characterized within aquifer settings. To investigate this reaction and some of its implications for redox-sensitive groundwater contaminants, we conducted an in situ field study in a wastewater-contaminated aquifer on Cape Cod. Long-term (15 year) geochemical monitoring within the contaminant plume indicated interacting zones with variable nitrate-, Fe(II)-, phosphate-, As(V)-, and As(III)-containing groundwater. Nitrate and phosphate were derived predominantly from wastewater disposal, whereas Fe(II), As(III), and As(V) were mobilized from the aquifer sediments. Multiple natural gradient, anoxic tracer tests were conducted in which nitrate and bromide were injected into nitrate-free, Fe(II)-containing groundwater. Prior to injection, aqueous Fe(II) concentrations were approximately 175 μM, but sorbed Fe(II) accounted for greater than 90% of the total reactive Fe(II) in the aquifer. Nitrate reduction was stimulated within 1 m of transport for 100 μM and 1000 μM nitrate additions, initially producing stoichiometric quantities of nitrous oxide (>300 μM N). In subsequent injections at the same site, nitrate was reduced even more rapidly and produced less nitrous oxide, especially over longer transport distances. Fe(II) and nitrate concentrations decreased together and were accompanied by Fe(III) oxyhydroxide precipitation and decreases in dissolved phosphate, As(III), and As(V) concentrations. Nitrate N and O isotope fractionation effects during nitrate reduction were approximately equal (ε15N/ε18O = 1.11) and were similar to those reported for laboratory studies of biological nitrate reduction, including denitrification, but unlike some reported effects on nitrate by denitrification in aquifers. All constituents affected by the in situ tracer experiments returned to pre-injection levels after several

  3. Geochemical Survey of Pernambuco

    International Nuclear Information System (INIS)

    Horowitz, A.; Duarte, P.J.; Almeida, M.G. de; Medeiros, M.O.

    1988-01-01

    The area studied i this work is located in a triangle formed by the Sibiro and Boca da Mata Sugar-Mills and Serinhaem country. In the Cabo Formation the search determinated conglomerates, arcos and clays. Although the highest geochemical activity have been done in the decomposed crystalin, and the values from Cabo Formation don't be encourager, this formation has lithology compatible with uranium mineralization. The Cabo Formation's sediments presents lithologic variations very expressives, with conglomerates, arcoses and clay silts, which determinate the choise of the area. This area presented favorable to uranium prospecting and to others elements interesting to ragional geochemistry. The atomic absorption analysis, fluorimetry and spectrometry were done for the following elements: Zn, V, Ti, Ni, Pb, Mn, Ga, Cu, Co, Bi, Ag, B, Mo, and U. (C.D.G.) [pt

  4. Geochemistry of shallow ground water in coastal plain environments in the southeastern United States: implications for aquifer susceptibility

    International Nuclear Information System (INIS)

    Tesoriero, Anthony J.; Spruill, Timothy B.; Eimers, Jo L.

    2004-01-01

    Ground-water chemistry data from coastal plain environments have been examined to determine the geochemical conditions and processes that occur in these areas and assess their implications for aquifer susceptibility. Two distinct geochemical environments were studied to represent a range of conditions: an inner coastal plain setting having more well-drained soils and lower organic carbon (C) content and an outer coastal plain environment that has more poorly drained soils and high organic C content. Higher concentrations of most major ions and dissolved inorganic and organic C in the outer coastal plain setting indicate a greater degree of mineral dissolution and organic matter oxidation. Accordingly, outer coastal plain waters are more reducing than inner coastal plain waters. Low dissolved oxygen (O 2 ) and nitrate (NO 3 - ) concentrations and high iron (Fe) concentrations indicate that ferric iron (Fe (III)) is an important electron acceptor in this setting, while dissolved O 2 is the most common terminal electron acceptor in the inner coastal plain setting. The presence of a wide range of redox conditions in the shallow aquifer system examined here underscores the importance of providing a detailed geochemical characterization of ground water when assessing the intrinsic susceptibility of coastal plain settings. The greater prevalence of aerobic conditions in the inner coastal plain setting makes this region more susceptible to contamination by constituents that are more stable under these conditions and is consistent with the significantly (p 3 - found in this setting. Herbicides and their transformation products were frequently detected (36% of wells sampled), however concentrations were typically low (<0.1 μg/L). Shallow water table depths often found in coastal plain settings may result in an increased risk of the detection of pesticides (e.g., alachlor) that degrade rapidly in the unsaturated zone

  5. Process-based reactive transport model to quantify arsenic mobility during aquifer storage and recovery of potable water.

    Science.gov (United States)

    Wallis, Ilka; Prommer, Henning; Pichler, Thomas; Post, Vincent; Norton, Stuart B; Annable, Michael D; Simmons, Craig T

    2011-08-15

    Aquifer storage and recovery (ASR) is an aquifer recharge technique in which water is injected in an aquifer during periods of surplus and withdrawn from the same well during periods of deficit. It is a critical component of the long-term water supply plan in various regions, including Florida, USA. Here, the viability of ASR as a safe and cost-effective water resource is currently being tested at a number of sites due to elevated arsenic concentrations detected during groundwater recovery. In this study, we developed a process-based reactive transport model of the coupled physical and geochemical mechanisms controlling the fate of arsenic during ASR. We analyzed multicycle hydrochemical data from a well-documented affected southwest Floridan site and evaluated a conceptual/numerical model in which (i) arsenic is initially released during pyrite oxidation triggered by the injection of oxygenated water (ii) then largely complexes to neo-formed hydrous ferric oxides before (iii) being remobilized during recovery as a result of both dissolution of hydrous ferric oxides and displacement from sorption sites by competing anions.

  6. Contribution to the geochemical knowledge of the uranium-radium and thorium families in the southern Vosges. Applications of some results in the prospecting of uranium deposits

    International Nuclear Information System (INIS)

    Jurain, G.

    1962-01-01

    This work's aim is to lead to a more accurate knowledge of the geochemistry of the Uranium-Radium and Thorium families in the Southern Vosges and to apply some of the results to the prospecting of uraniferous deposits: It has been showed: a bond between Calcium-Magnesium and Uranium-Thorium in the calco-alkaline granites. The host minerals of Uranium and Thorium are hornblende, biotite, titanite and epidote. a concentration of Uranium, at present time with secular disequilibrium in a thermal zone where the satellite mineralizations form an epithermal paragenesis. a disequilibrium of the Uranium-Radium family in the supergene minerals of the lead (phosphate and vanadate) showing the present circulations of Uranium. a bond between the radon grade of the spring waters and Uranium-Radium of the rocks. Such a relation allow to realize a prospecting method based on the determination of radioactive gases from the cold spring-waters of a common country. (author) [fr

  7. Effect of transient wave forcing on the behavior of arsenic in a sandy nearshore aquifer

    Science.gov (United States)

    Rakhimbekova, S.; O'Carroll, D. M.; Robinson, C. E.

    2016-12-01

    Waves cause large quantities of coastal water to recirculate across the groundwater-coastal water interface in addition to inducing complex groundwater flows in the nearshore aquifer. Due to the distinct chemical composition of recirculating coastal water compared with discharging terrestrial groundwater, wave-induced recirculations and flows can alter geochemical gradients in the nearshore aquifer which may subsequently affect the mobilization and transport of reactive pollutants (e.g., arsenic). The impact of seasonal geochemical and hydrological variability on the occurrence and mobility of arsenic near the groundwater-surface water interface has been shown previously in riverine settings, however, the impact of high frequency geochemical variations (e.g., varying wave conditions) on arsenic mobility in groundwater-surface water environments is unclear. The objective of the study was to assess the impact of intensified wave conditions on the behavior of arsenic in a nearshore aquifer to determine the factors regulating its mobility and transport to receiving coastal waters. Field investigations were conducted at a permeable beach on the Great Lakes during a period of intensified wave conditions (wave event). High spatial resolution pore water sampling captured the geochemical conditions in the nearshore aquifer prior to the wave event, immediately after the wave event and over a recovery period of 3 weeks following the wave event. Shifts in pH and redox potential (ORP) gradients in response to varying wave conditions caused shifts in the iron and arsenic distributions in the aquifer. Sediment analysis was combined with the pore water distributions to assess the release of sediment-bound arsenic in response to the varying wave conditions. Insight into the effect of transient forcing on arsenic mobility and transport in groundwater-surface water environments is important for evaluating the potential risks associated with this toxic metalloid. The findings of this

  8. Impacts of geochemical and environmental factors on seasonal variation of heavy metals in a coastal lagoon Yucatan, Mexico.

    Science.gov (United States)

    Arcega-Cabrera, F; Garza-Pérez, R; Noreña-Barroso, E; Oceguera-Vargas, I

    2015-01-01

    This study investigated the influence of geochemical and environmental factors on seasonal variation in metals in Yucatan's Chelem lagoon. Anthropogenic activities discharge non-treated wastewater directly into it with detrimental environmental consequences. Accordingly, this study established the spatial and temporal patterns of fine grain sediments and concentrations of heavy metals. Multivariate analyses showed fine grain facies deposition, transition sites dominated by fine grain transport, and fine grain erosion sites. Spatial and temporal variations of heavy metals concentration were significant for Cd, Cu, Cr, and Pb. As, Cd, and Sn were as much as 12 times higher than SQuiRTs standards (Buchman 2008). The results indicate that aquifer water is bringing metals from relatively far inland and releasing them into the lagoon. Thus, it appears that the contamination of this lagoon is highly complex and must take into account systemic connections with inland anthropogenic activates and pollution, as well as local factors.

  9. Processes Governing Alkaline Groundwater Chemistry within a Fractured Rock (Ophiolitic Mélange Aquifer Underlying a Seasonally Inhabited Headwater Area in the Aladağlar Range (Adana, Turkey

    Directory of Open Access Journals (Sweden)

    Cüneyt Güler

    2017-01-01

    Full Text Available The aim of this study was to investigate natural and anthropogenic processes governing the chemical composition of alkaline groundwater within a fractured rock (ophiolitic mélange aquifer underlying a seasonally inhabited headwater area in the Aladağlar Range (Adana, Turkey. In this aquifer, spatiotemporal patterns of groundwater flow and chemistry were investigated during dry (October 2011 and wet (May 2012 seasons utilizing 25 shallow hand-dug wells. In addition, representative samples of snow, rock, and soil were collected and analyzed to constrain the PHREEQC inverse geochemical models used for simulating water-rock interaction (WRI processes. Hydrochemistry of the aquifer shows a strong interseasonal variability where Mg–HCO3 and Mg–Ca–HCO3 water types are prevalent, reflecting the influence of ophiolitic and carbonate rocks on local groundwater chemistry. R-mode factor analysis of hydrochemical data hints at geochemical processes taking place in the groundwater system, that is, WRI involving Ca- and Si-bearing phases; WRI involving amorphous oxyhydroxides and clay minerals; WRI involving Mg-bearing phases; and atmospheric/anthropogenic inputs. Results from the PHREEQC modeling suggested that hydrogeochemical evolution is governed by weathering of primary minerals (calcite, chrysotile, forsterite, and chromite, precipitation of secondary minerals (dolomite, quartz, clinochlore, and Fe/Cr oxides, atmospheric/anthropogenic inputs (halite, and seasonal dilution from recharge.

  10. Summary of hydrologic testing of the Floridan aquifer system at Fort Stewart, coastal Georgia, 2009-2010

    Science.gov (United States)

    Gonthier, Gerald J.

    2011-01-01

    Two test wells were completed at Fort Stewart, coastal Georgia, to investigate the potential for using the Lower Floridan aquifer as a source of water to satisfy anticipated, increased water needs. The U.S. Geological Survey, in cooperation with the U.S. Department of the Army, completed hydrologic testing of the Floridan aquifer system at the study site, including flowmeter surveys, slug tests, and 24- and 72-hour aquifer tests by mid-March 2010. Analytical approaches and model simulation were applied to aquifer-test results to provide estimates of transmissivity and hydraulic conductivity of the multilayered Floridan aquifer system. Data from a 24-hour aquifer test of the Upper Floridan aquifer were evaluated by using the straight-line Cooper-Jacob analytical method. Data from a 72-hour aquifer test of the Lower Floridan aquifer were simulated by using axisymmetric model simulations. Results of aquifer testing indicated that the Upper Floridan aquifer has a transmissivity of 100,000 feet-squared per day, and the Lower Floridan aquifer has a transmissivity of 7,000 feet-squared per day. A specific storage for the Floridan aquifer system as a result of model calibration was 3E-06 ft–1. Additionally, during a 72-hour aquifer test of the Lower Floridan aquifer, a drawdown response was observed in two Upper Floridan aquifer wells, one of which was more than 1 mile away from the pumped well.

  11. Geochemical mapping study of Panjang island

    International Nuclear Information System (INIS)

    Sutisna; Sumardjo

    2010-01-01

    Impact of industrial and regional development are not only related to an improvement of socio-economic, but also to an environmental conservation and sustainable. This impact could be observed on a change of geochemical mapping before and after an operational of the industry. In the relation with a regional development and resources utilization, the geochemical mapping have been done in the aim to know a resources and an elemental distribution at Panjang island. In this research, ko-Instrumental Neutron Activation Analysis (k_0-INAA) have been applied in an elemental quantification on the geochemical mapping. Pencuplikan of geochemical sample have been carried out by using a grid systematic method with a sample density of about 10 sample per square kilometre involved 85 pencuplikan point. The geochemical sample of sediment and soil have been provided as a dry weight of 100 mesh. Internal quality control have done by using a number of Standard Reference Materials obtained from US. Geological Survey. Fifteen elements of Sc, Co, In, Rb, Mo, Ba, Ce, Nd, Eu, La, Yb, Th, U, lr and Hf contained in standard materials have been evaluated. The analysis result show that a relative standard deviation less than 11 %, except for Mo (13 %) and lr (26 %). Fourteen elements of Al, Br, Ca, Co, Eu, Fe, La, U, Na, Ce, Mn, As, Sc and Th have been mapped and presented in this paper. The major elements of Ca, Al and Fe, and minor elements of Mn, U and Sc are distributed at all region. The lanthanide elements of La, Ce and Eu have vary concentration and could be found at the middle to the north of the island. (author)

  12. Geochemical baseline studies of soil in Finland

    Science.gov (United States)

    Pihlaja, Jouni

    2017-04-01

    The soil element concentrations regionally vary a lot in Finland. Mostly this is caused by the different bedrock types, which are reflected in the soil qualities. Geological Survey of Finland (GTK) is carrying out geochemical baseline studies in Finland. In the previous phase, the research is focusing on urban areas and mine environments. The information can, for example, be used to determine the need for soil remediation, to assess environmental impacts or to measure the natural state of soil in industrial areas or mine districts. The field work is done by taking soil samples, typically at depth between 0-10 cm. Sampling sites are chosen to represent the most vulnerable areas when thinking of human impacts by possible toxic soil element contents: playgrounds, day-care centers, schools, parks and residential areas. In the mine districts the samples are taken from the areas locating outside the airborne dust effected areas. Element contents of the soil samples are then analyzed with ICP-AES and ICP-MS, Hg with CV-AAS. The results of the geochemical baseline studies are published in the Finnish national geochemical baseline database (TAPIR). The geochemical baseline map service is free for all users via internet browser. Through this map service it is possible to calculate regional soil baseline values using geochemical data stored in the map service database. Baseline data for 17 elements in total is provided in the map service and it can be viewed on the GTK's web pages (http://gtkdata.gtk.fi/Tapir/indexEN.html).

  13. Alligator Rivers Analogue project. Geochemical Data Bases

    International Nuclear Information System (INIS)

    Bennett, D.G.; Read, D.

    1992-01-01

    The Koongarra uranium deposit in the Northern Territory of Australia is being studied to evaluate the processes involved in the geochemical alteration of the ore body and the formation of the uranium dispersion fan. A broad range of research is being undertaken into the geochemistry and hydrology of the site with the aim of understanding the transport of radionuclides through the system. During the project a range of geochemical and hydrogeochemical models have been developed to account for measured data from the site and with which to predict site evolution. The majority of these models are based on the premise of thermodynamic chemical equilibrium and employ fundamental thermodynamic data to characterise the chemistry of the system. From the differences which exist between the thermodynamic data bases (Appendices I and II) it is possible to gain a view of the level of uncertainty associated with thermodynamic data in each set of calculations. This report gives a brief introduction to the geochemical processes underlying the models, and details the equations used to quantify the more common of these processes (e.g. aqueous speciation and mineral solubility). A description is given of the computer codes (EQ3/6, PHREEQE, MINTEQ) most commonly used during the project for geochemical modelling. Their key features are highlighted and comparisons made. It is concluded that the degree of uncertainty in geochemical modelling studies arising as a result of using one code rather than another is relatively insignificant when compared to that related to differences in the underlying data bases. 73 refs., 3 figs

  14. Occurrence and origin of methane in groundwater in Alberta (Canada): Gas geochemical and isotopic approaches

    International Nuclear Information System (INIS)

    Humez, P.; Mayer, B.; Ing, J.; Nightingale, M.; Becker, V.; Kingston, A.; Akbilgic, O.; Taylor, S.

    2016-01-01

    To assess potential future impacts on shallow aquifers by leakage of natural gas from unconventional energy resource development it is essential to establish a reliable baseline. Occurrence of methane in shallow groundwater in Alberta between 2006 and 2014 was assessed and was ubiquitous in 186 sampled monitoring wells. Free and dissolved gas sampling and measurement approaches yielded comparable results with low methane concentrations in shallow groundwater, but in 28 samples from 21 wells methane exceeded 10 mg/L in dissolved gas and 300,000 ppmv in free gas. Methane concentrations in free and dissolved gas samples were found to increase with well depth and were especially elevated in groundwater obtained from aquifers containing coal seams and shale units. Carbon isotope ratios of methane averaged − 69.7 ± 11.1‰ (n = 63) in free gas and − 65.6 ± 8.9‰ (n = 26) in dissolved gas. δ"1"3C values were not found to vary with well depth or lithology indicating that methane in Alberta groundwater was derived from a similar source. The low δ"1"3C values in concert with average δ"2H_C_H_4 values of − 289 ± 44‰ (n = 45) suggest that most methane was of biogenic origin predominantly generated via CO_2 reduction. This interpretation is confirmed by dryness parameters typically > 500 due to only small amounts of ethane and a lack of propane in most samples. Comparison with mud gas profile carbon isotope data revealed that methane in the investigated shallow groundwater in Alberta is isotopically similar to hydrocarbon gases found in 100–250 meter depths in the WCSB and is currently not sourced from thermogenic hydrocarbon occurrences in deeper portions of the basin. The chemical and isotopic data for methane gas samples obtained from Alberta groundwater provide an excellent baseline against which potential future impact of deeper stray gases on shallow aquifers can be assessed. - Highlights: • Analysis of gas geochemical data from 186 monitoring wells in

  15. Occurrence and origin of methane in groundwater in Alberta (Canada): Gas geochemical and isotopic approaches

    Energy Technology Data Exchange (ETDEWEB)

    Humez, P., E-mail: phumez@ucalgary.ca [Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4 (Canada); Mayer, B.; Ing, J.; Nightingale, M.; Becker, V.; Kingston, A. [Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4 (Canada); Akbilgic, O. [Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4 (Canada); UTHSC-ORNL Center for Biomedical Informatics, 910 Madison Avenue, Memphis, TN, 38104 (United States); Taylor, S. [Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4 (Canada)

    2016-01-15

    To assess potential future impacts on shallow aquifers by leakage of natural gas from unconventional energy resource development it is essential to establish a reliable baseline. Occurrence of methane in shallow groundwater in Alberta between 2006 and 2014 was assessed and was ubiquitous in 186 sampled monitoring wells. Free and dissolved gas sampling and measurement approaches yielded comparable results with low methane concentrations in shallow groundwater, but in 28 samples from 21 wells methane exceeded 10 mg/L in dissolved gas and 300,000 ppmv in free gas. Methane concentrations in free and dissolved gas samples were found to increase with well depth and were especially elevated in groundwater obtained from aquifers containing coal seams and shale units. Carbon isotope ratios of methane averaged − 69.7 ± 11.1‰ (n = 63) in free gas and − 65.6 ± 8.9‰ (n = 26) in dissolved gas. δ{sup 13}C values were not found to vary with well depth or lithology indicating that methane in Alberta groundwater was derived from a similar source. The low δ{sup 13}C values in concert with average δ{sup 2}H{sub CH4} values of − 289 ± 44‰ (n = 45) suggest that most methane was of biogenic origin predominantly generated via CO{sub 2} reduction. This interpretation is confirmed by dryness parameters typically > 500 due to only small amounts of ethane and a lack of propane in most samples. Comparison with mud gas profile carbon isotope data revealed that methane in the investigated shallow groundwater in Alberta is isotopically similar to hydrocarbon gases found in 100–250 meter depths in the WCSB and is currently not sourced from thermogenic hydrocarbon occurrences in deeper portions of the basin. The chemical and isotopic data for methane gas samples obtained from Alberta groundwater provide an excellent baseline against which potential future impact of deeper stray gases on shallow aquifers can be assessed. - Highlights: • Analysis of gas geochemical data from 186

  16. Artificial Intelligence-Based Models for the Optimal and Sustainable Use of Groundwater in Coastal Aquifers

    Science.gov (United States)

    Sreekanth, J.; Datta, Bithin

    2011-07-01

    Overexploitation of the coastal aquifers results in saltwater intrusion. Once saltwater intrusion occurs, it involves huge cost and long-term remediation measures to remediate these contaminated aquifers. Hence, it is important to have strategies for the sustainable use of coastal aquifers. This study develops a methodology for the optimal management of saltwater intrusion prone aquifers. A linked simulation-optimization-based management strategy is developed. The methodology uses genetic-programming-based models for simulating the aquifer processes, which is then linked to a multi-objective genetic algorithm to obtain optimal management strategies in terms of groundwater extraction from potential well locations in the aquifer.

  17. Solute geochemistry of the Snake River Plain regional aquifer system, Idaho and eastern Oregon

    International Nuclear Information System (INIS)

    Wood, W.W.; Low, W.H.

    1987-01-01

    Three geochemical methods were used to determine chemical reactions that control solute concentrations in the Snake River Plain regional aquifer system: (1) calculation of a regional solute balance within the aquifer and of mineralogy in the aquifer framework to identify solute reactions, (2) comparison of thermodynamic mineral saturation indices with plausible solute reactions, and (3) comparison of stable isotope ratios of the groundwater with those in the aquifer framework. The geothermal groundwater system underlying the main aquifer system was examined by calculating thermodynamic mineral saturation indices, stable isotope ratios of geothermal water, geothermometry, and radiocarbon dating. Water budgets, hydrologic arguments, and isotopic analyses for the eastern Snake River Plain aquifer system demonstrate that most, if not all, water is of local meteoric and not juvenile or formation origin. Solute balance, isotopic, mineralogic, and thermodynamic arguments suggest that about 20% of the solutes are derived from reactions with rocks forming the aquifer framework. Reactions controlling solutes in the western Snake river basin are believed to be similar to those in the eastern basin but the regional geothermal system that underlies the Snake river Plain contains total dissolved solids similar to those in the overlying Snake River Plain aquifer system but contains higher concentrations of sodium, bicarbonate, silica, fluoride, sulfate, chloride, arsenic, boron, and lithium, and lower concentrations of calcium, magnesium, and hydrogen. 132 refs., 30 figs., 27 tabs

  18. Assessment of Managed Aquifer Recharge through Modeling—A Review

    Directory of Open Access Journals (Sweden)

    Jana Ringleb

    2016-12-01

    Full Text Available Managed aquifer recharge (MAR is the purposeful recharge of an aquifer for later recovery or environmental benefits and represents a valuable method for sustainable water resources management. Models can be helpful tools for the assessment of MAR systems. This review encompasses a survey and an analysis of case studies which apply flow and transport models to evaluate MAR. The observed modeling objectives include the planning or optimization of MAR schemes as well as the identification and quantification of geochemical processes during injection, storage and recovery. The water recovery efficiency and the impact of the injected water on the ambient groundwater are further objectives investigated in the reviewed studies. These objectives are mainly solved by using groundwater flow models. Unsaturated flow models, solute transport models, reactive geochemical models as well as water balance models are also frequently applied and often coupled. As each planning step to setup a new MAR facility requires cost and time investment, modeling is used to minimize hazard risks and assess possible constraints of the system such as low recovery efficiency, clogging and geochemical processes.

  19. Hydrogeology and water quality of the Floridan aquifer system and effect of Lower Floridan aquifer withdrawals on the Upper Floridan aquifer at Barbour Pointe Community, Chatham County, Georgia, 2013

    Science.gov (United States)

    Gonthier, Gerard; Clarke, John S.

    2016-06-02

    Two test wells were completed at the Barbour Pointe community in western Chatham County, near Savannah, Georgia, in 2013 to investigate the potential of using the Lower Floridan aquifer as a source of municipal water supply. One well was completed in the Lower Floridan aquifer at a depth of 1,080 feet (ft) below land surface; the other well was completed in the Upper Floridan aquifer at a depth of 440 ft below land surface. At the Barbour Pointe test site, the U.S. Geological Survey completed electromagnetic (EM) flowmeter surveys, collected and analyzed water samples from discrete depths, and completed a 72-hour aquifer test of the Floridan aquifer system withdrawing from the Lower Floridan aquifer.Based on drill cuttings, geophysical logs, and borehole EM flowmeter surveys collected at the Barbour Pointe test site, the Upper Floridan aquifer extends 369 to 567 ft below land surface, the middle semiconfining unit, separating the two aquifers, extends 567 to 714 ft below land surface, and the Lower Floridan aquifer extends 714 to 1,056 ft below land surface.A borehole EM flowmeter survey indicates that the Upper Floridan and Lower Floridan aquifers each contain four water-bearing zones. The EM flowmeter logs of the test hole open to the entire Floridan aquifer system indicated that the Upper Floridan aquifer contributed 91 percent of the total flow rate of 1,000 gallons per minute; the Lower Floridan aquifer contributed about 8 percent. Based on the transmissivity of the middle semiconfining unit and the Floridan aquifer system, the middle semiconfining unit probably contributed on the order of 1 percent of the total flow.Hydraulic properties of the Upper Floridan and Lower Floridan aquifers were estimated based on results of the EM flowmeter survey and a 72-hour aquifer test completed in Lower Floridan aquifer well 36Q398. The EM flowmeter data were analyzed using an AnalyzeHOLE-generated model to simulate upward borehole flow and determine the transmissivity of

  20. Water-quality characteristics of quaternary unconsolidated-deposit aquifers and lower tertiary aquifers of the Bighorn Basin, Wyoming and Montana, 1999-2001

    Science.gov (United States)

    Bartos, Timothy T.; Eddy-Miller, Cheryl A.; Norris, Jody R.; Gamper, Merry E.; Hallberg, Laura L.

    2004-01-01

    samples with larger concentrations generally were calcium-sodium-sulfate, calcium-sulfate, or sodium-sulfate-type waters. In the lower Tertiary aquifers, samples with fresh waters generally were sodium-bicarbonate or sodium-bicarbonate-sulfate type waters, whereas samples with larger concentrations were sodium-sulfate or calcium-sodium-sulfate types. Concentrations of most trace elements in both types of aquifers generally were small and most were less than applicable USEPA standards. The trace elements that most often did not meet USEPA secondary drinking-water standards were iron and manganese. In fact, the SMCL for manganese was the most frequently exceeded standard; 68 percent of the samples from the Quaternary aquifers and 31 percent of the samples from the lower Tertiary aquifers exceeded the manganese standard. Geochemical conditions may control manganese in both aquifers as concentrations in Quaternary aquifers were negatively correlated with dissolved oxygen concentrations and concentrations in lower Tertiary aquifers decreased with increasing pH. Elevated nitrate concentrations, in addition to detection of pesticides and VOCs in both aquifers, indicated some effects of human activities on ground-water quality. Nitrate concentrations in 36 percent of the wells in Quaternary aquifers and 28 percent of the wells in lower Tertiary aquifers were greater than 1 mg/L, which may indicate ground-water contamination from human sources. The USEPA drinking-water Maximum Contaminant Level (MCL) for nitrate, 10 mg/L, was exceeded in 8 percent of samples collected from Quaternary aquifers and 3 percent from lower Tertiary aquifers. Nitrate concentrations in Quaternary aquifers were positively correlated with the percentage of cropland and other agricultural land (non-cropland), and negatively correlated with rangeland and riparian land. In the lower Tertiary aquifers, nitrate concentrations only were correlated with the percentage of cropland. Concentratio

  1. Straddle-packer aquifer test analyses of the Snake River Plain aquifer at the Idaho National Engineering Laboratory

    International Nuclear Information System (INIS)

    Johnson, G.S.; Frederick, D.B.

    1997-01-01

    The State of Idaho INEL Oversight Program, with the University of Idaho, Idaho State University, Boise State University, and the Idaho Geologic Survey, used a straddle-packer system to investigate vertical variations in characteristics of the Snake River Plain aquifer at the Idaho National Engineering Laboratory in southeast Idaho. Sixteen single-well aquifer tests were conducted on.isolated intervals in three observation wells. Each of these wells has approximately 200 feet of open borehole below the water table, penetrating the E through G and I basalt flow groups and interbedded sediments of the Snake River Plain aquifer. The success of the aquifer tests was limited by the inability to induce measurable drawdown in several zones. Time-drawdown data from aquifer tests were matched to type curves for 8 of the 16 zones tested. A single aquifer test at the water table exhibited greater curvature than those at depth. The increased degree of curvature suggests an unconfined response and resulted in an estimate of specific yield of 0.03. Aquifer tests below the water table generally yielded time-drawdown graphs with a rapid initial response followed by constant drawdown throughout the duration of the tests; up to several hours in length. The rapid initial response implies that the aquifer responds as a confined system during brief pumping periods. The nearly constant drawdown suggests a secondary source of water, probably vertical flow from overlying and underlying aquifer layers. Three analytical models were applied for comparison to the conceptual model and to provide estimates of aquifer properties. This, Hantush-Jacob leaky aquifer, and the Moench double-porosity fractured rock models were fit to time-drawdown data. The leaky aquifer type curves of Hantush and Jacob generally provided the best match to observed drawdown. A specific capacity regression equation was also used to estimate hydraulic conductivity

  2. Transient well flow in vertically heterogeneous aquifers

    Science.gov (United States)

    Hemker, C. J.

    1999-11-01

    A solution for the general problem of computing well flow in vertically heterogeneous aquifers is found by an integration of both analytical and numerical techniques. The radial component of flow is treated analytically; the drawdown is a continuous function of the distance to the well. The finite-difference technique is used for the vertical flow component only. The aquifer is discretized in the vertical dimension and the heterogeneous aquifer is considered to be a layered (stratified) formation with a finite number of homogeneous sublayers, where each sublayer may have different properties. The transient part of the differential equation is solved with Stehfest's algorithm, a numerical inversion technique of the Laplace transform. The well is of constant discharge and penetrates one or more of the sublayers. The effect of wellbore storage on early drawdown data is taken into account. In this way drawdowns are found for a finite number of sublayers as a continuous function of radial distance to the well and of time since the pumping started. The model is verified by comparing results with published analytical and numerical solutions for well flow in homogeneous and heterogeneous, confined and unconfined aquifers. Instantaneous and delayed drainage of water from above the water table are considered, combined with the effects of partially penetrating and finite-diameter wells. The model is applied to demonstrate that the transient effects of wellbore storage in unconfined aquifers are less pronounced than previous numerical experiments suggest. Other applications of the presented solution technique are given for partially penetrating wells in heterogeneous formations, including a demonstration of the effect of decreasing specific storage values with depth in an otherwise homogeneous aquifer. The presented solution can be a powerful tool for the analysis of drawdown from pumping tests, because hydraulic properties of layered heterogeneous aquifer systems with

  3. Impact of pH on hydrogen oxidizing redox processes in aquifers due to gas intrusions

    Science.gov (United States)

    Metzgen, Adrian; Berta, Marton; Dethlefsen, Frank; Ebert, Markus; Dahmke, Andreas

    2017-04-01

    (first order rate constants between 0.029 and 0.036 1/h). Between pH 7 and 8, acetogenesis showed a linear trend (zeroth order rates between 3 and 5 µM/h) whereas formate production became the main process (zeroth order rates between 38 to 197 µM/h) together with methanogenesis as a minor process. The results indicated a strong dependency of the biogeochemical hydrogenotrophic redox reactions on the pH milieu. Thus, pH buffers such as dissolved or solid phase carbonates should be taken into account when predicting effects a hydrogen leakage may have on shallow aquifers. Additionally, parameters derived from the observed processes and their rates allow the design of a process based numerical model simulating a hydrogen intrusion into a shallow aquifer. Consequently the presented outcomes allow an exemplary quantification of the resulting geochemical effects. This study was carried out within the ANGUS+ project and was funded by the German Federal Ministry of Education and Research (BMBF) energy storage funding initiative.

  4. The limited role of aquifer heterogeneity on metal reduction in an Atlantic coastal plain determined by push-pull tests

    International Nuclear Information System (INIS)

    Mailloux, Brian J.; Devlin, Stephanie; Fuller, Mark E.; Onstott, T.C.; De Flaun, Mary F.; Choi, K.-H.; Green-Blum, Maria; Swift, Donald J.P.; McCarthy, John; Dong Hailiang

    2007-01-01

    Sixty push-pull experiments were conducted to determine the factors controlling Fe(III) and Mn(IV) reduction in a well-characterized, shallow, coastal plain aquifer near Oyster, VA, USA. The five multi-level samplers each equipped with 12 ports sampled a heterogeneous portion of the aquifer from 4.4 to 8m-bgs. Each multi-level sampler (MLS) was injected with groundwater that contained NO 3 - and Br - along with: (1) just groundwater (control treatment), (2) humics, (3) lactate (conducted twice) and (4) lactate plus humics. Microbially mediated Fe(III) reduction caused the aqueous Fe Tot concentrations to increase at every depth in the lactate treatment with significant increases within 1 day even while NO 3 - was present. Little change in the Fe Tot concentrations were observed in the control and humics treatment. Humics may have acted as an electron shuttle to increase Fe(III) reduction in the lactate plus humics treatment. The amount of Mn(IV) reduction was significantly lower than that of Fe(III) reduction. Geochemical modeling indicated that gas formation, sorption on reactive surfaces, and mineral precipitation were important processes and that Fe(III) and SO 4 2- reduction were co-occurring. Conditions were favorable for the precipitation of Fe-carbonates, Fe-sulfides and Fe-silicates. In the lactate treatment protist concentrations increased then decreased and planktonic cell concentrations steadily increased, whereas no change was observed in the control treatment. Correlations of Fe(III) reduction with physical and chemical heterogeneity were weak, probably as a result of the abundance of Fe(III) bearing minerals relative to electron donor abundance and that the push-pull test sampled a representative elemental volume that encompassed the microbial diversity within the aquifer. This work indicates that stimulating metal reduction in aquifer systems is a feasible method for remediating heterogeneous subsurface sites contaminated with metals and

  5. Palaeoclimatic trends deduced from the hydrochemistry of a Triassic sandstone aquifer, United Kingdom

    International Nuclear Information System (INIS)

    Bath, A.H.; Edmunds, W.M.; Andrews, J.N.

    1979-01-01

    A detailed geochemical study (elemental, isotopic and dissolved inert gases) of unconfined and confined sections of the Triassic non-marine sandstone aquifer in eastern England has been undertaken. Aspects of the recharge history of this aquifer over the past 40,000 years are revealed by examination of the data. 14 C activity and delta 13 C values show downgradient decrease and increase, respectively, the latter from -12 to -13 per mille (PDB) at outcrop to -8.5 per mille in deep confined groundwaters, indicating a continuing reaction between water and carbonate mineral phases. Although the bulk carbonate contained in sandstone samples gives delta 13 C around -7 per mille, modelling of the carbon isotopic evolution and consideration of the resulting 14 C age corrections suggest that a carbonate with delta 13 C closer to 0 per mille has played a major role in at least the earlier stages of hydrochemical evolution. The corrected radiocarbon age ranges, generated by the computer program WATEQF-ISOTOP, are used as a framework in which the palaeo-environmental information from oxygen and hydrogen isotope data, inert gas contents, and chloride levels are discussed. The measurement of dissolved helium levels demonstrates an excess of 4 He in many samples, which correlates with radiocarbon ages. The assumption of bulk chemical and physical properties for the aquifer rock allows independent 'excess 4 He' ages to be computed, which are mostly in excess of the corrected 14 C ages. The trend of delta 18 O is from about -8 per mille at outcrop to -9.7 per mille (SMOW) downgradient, which is significantly more depleted than has been found in previous studies of UK basins. The delta 2 H and delta 18 O values are related by the regression line delta 2 H=6.6delta 18 O+1; data from other UK studies also lie close to this trend

  6. Predictive geochemical mapping using environmental correlation

    International Nuclear Information System (INIS)

    Wilford, John; Caritat, Patrice de; Bui, Elisabeth

    2016-01-01

    methods. Furthermore, insights can be gained into the landscape processes controlling element concentration, distribution and mobility from analysis of the covariates used in the model. This modelling approach can be extended to groups of elements (indices), element ratios, isotopes or mineralogy over a range of scales and in a variety of environments. - Highlights: • Predictive geochemical modelling using environmental covariates. • Environmental correlation compared with geostatistical approaches. • Resulting predictions inherit high spatial resolution of covariate datasets. • Approach provides insights into processes controlling surface chemistry. • Approach has broad application in environmental science and mineral exploration.

  7. 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)

    Brenot, Agnès; Négrel, Philippe; Petelet-Giraud, Emmanuelle; Millot, Romain; Malcuit, Eline

    2015-01-01

    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 km 2 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 (δ 34 S SO4 , δ 18 O SO4 and 87 Sr/ 86 Sr) 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 (SO 4 , 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 δ 34 S and δ 18 O from

  8. Hydrochemical Regions of the Glacial Aquifer System, Northern United States, and Their Environmental and Water-Quality Characteristics

    Science.gov (United States)

    Arnold, Terri L.; Warner, Kelly L.; Groschen, George E.; Caldwell, James P.; Kalkhoff, Stephen J.

    2008-01-01

    The glacial aquifer system in the United States is a large (953,000 square miles) regional aquifer system of heterogeneous composition. As described in this report, the glacial aquifer system includes all unconsolidated geologic material above bedrock that lies on or north of the line of maximum glacial advance within the United States. Examining ground-water quality on a regional scale indicates that variations in the concentrations of major and minor ions and some trace elements most likely are the result of natural variations in the geologic and physical environment. Study of the glacial aquifer system was designed around a regional framework based on the assumption that two primary characteristics of the aquifer system can affect water quality: intrinsic susceptibility (hydraulic properties) and vulnerability (geochemical properties). The hydrochemical regions described in this report were developed to identify and explain regional spatial variations in ground-water quality in the glacial aquifer system within the hypothetical framework context. Data analyzed for this study were collected from 1991 to 2003 at 1,716 wells open to the glacial aquifer system. Cluster analysis was used to group wells with similar ground-water concentrations of calcium, chloride, fluoride, magnesium, potassium, sodium, sulfate, and bicarbonate into five unique groups. Maximum Likelihood Classification was used to make the extrapolation from clustered groups of wells, defined by points, to areas of similar water quality (hydrochemical regions) defined in a geospatial model. Spatial data that represented average annual precipitation, average annual temperature, land use, land-surface slope, vertical soil permeability, average soil clay content, texture of surficial deposits, type of surficial deposit, and potential for ground-water recharge were used in the Maximum Likelihood Classification to classify the areas so the characteristics of the hydrochemical regions would resemble the

  9. Quality of groundwater at and near an aquifer storage and recovery site, Bexar, Atascosa, and Wilson Counties, Texas, June 2004-August 2008

    Science.gov (United States)

    Otero, Cassi L.; Petri, Brian L.

    2010-01-01

    The U.S. Geological Survey, in cooperation with the San Antonio Water System, did a study during 2004-08 to characterize the quality of native groundwater from the Edwards aquifer and pre- and post-injection water from the Carrizo aquifer at and near an aquifer storage and recovery (ASR) site in Bexar, Atascosa, and Wilson Counties, Texas. Groundwater samples were collected and analyzed for selected physical properties and constituents to characterize the quality of native groundwater from the Edwards aquifer and pre- and post-injection water from the Carrizo aquifer at and near the ASR site. Geochemical and isotope data indicated no substantial changes in major-ion, trace-element, and isotope chemistry occurred as the water from the Edwards aquifer was transferred through a 38-mile pipeline to the aquifer storage and recovery site. The samples collected from the four ASR recovery wells were similar in major-ion and stable isotope chemistry compared to the samples collected from the Edwards aquifer source wells and the ASR injection well. The similarity could indicate that as Edwards aquifer water was injected, it displaced native Carrizo aquifer water, or, alternatively, if mixing of Edwards and Carrizo aquifer waters was occurring, the major-ion and stable isotope signatures for the Carrizo aquifer water might have been obscured by the signatures of the injected Edwards aquifer water. Differences in the dissolved iron and dissolved manganese concentrations indicate that either minor amounts of mixing occurred between the waters from the two aquifers, or as Edwards aquifer water displaced Carrizo aquifer water it dissolved the iron and manganese directly from the Carrizo Sand. Concentrations of radium-226 in the samples collected at the ASR recovery wells were smaller than the concentrations in samples collected from the Edwards aquifer source wells and from the ASR injection well. The smaller radium-226 concentrations in the samples collected from the ASR

  10. Joint Russian-American hydrogeological-geochemical studies of the Karachai-Mishelyak system, South Urals, Russia

    International Nuclear Information System (INIS)

    Drozhko, E.G.; Glagolenko, Y.U.; Mokrov, Y.G.; Postovalova, G.A.; Samsonova, L.M.; Glagolev, A.V.; Ter-Saakian, S.A.; Glinsky, M.L.; Vasil'kova, N.A.; Skokov, A.V.; Wollenberg, H.A.; Tsan, C.F.; Frangos, W.; Solbau, R.D.; Stevenson, K.A.

    1997-01-01

    In September 1994, a Russian-American team conducted hydrogeological, geochemical, geophysical, and radiometric measurements in the teritory of the Mayak Production Association, Russia. The primary purpose of these operations was to examine the frontal area of a radioelement- and nitrate-laden groundwater plume moving from the disposal site, Lake Karachai, toward the Mishelyak River. Activities encompassed (1) isolation of hydrologic intervgals in two wells and production of water from these intervals, to comapre isolated versus open-well sampling methods and to determine hydraulic transmissivities of the aquifer(s); (2) surface and soil-water sampling, accompanying radiometric measurements and subsequent chemical analyses; and (3) electrical resistivity profiling in areas of expected contrasting resistivity. Preliminary results indicate that (1) 60 Co, 137 Cs, and 90 Sr are present in small concentrations (∝0.1% of permissible levels) in water of the Mishelyak River; (2) analyses of water samples collected by a downhole sampler and of water produced from packed-off intevals agree within limits of laboratory accuracy, attesting to the efficacy of the sampling methods presently used by the Russian workers; (3) considerable differences in contaminant concentrations exist between nearby wells, supporting the concept that the plume from Lake Karachai toward the Mishelyak River is controlled by steeply dipping fractures and shear zones; and (4) strong contrasts occur between the electrical resistivities of soil and bedrock. (orig./SR)

  11. Geochemical, hydrological, and biological cycling of energy residual. Research plan

    International Nuclear Information System (INIS)

    Wobber, F.J.

    1983-03-01

    Proposed research goals and specific research areas designed to provide a base of fundamental scientific information so that the geochemical, hydrological, and biophysical mechanisms that contribute to the transport and long term fate of energy residuals in natural systems can be understood are described. Energy development and production have resulted in a need for advanced scientific information on the geochemical transformations, transport rates, and potential for bioaccumulation of contaminants in subsurface environments

  12. Integrated geophysical-geochemical methods for archaeological prospecting

    OpenAIRE

    Persson, Kjell

    2005-01-01

    A great number of field measurements with different methods and instruments were conducted in attempts to develop a method for an optimal combination of various geochemical and geophysical methods in archaeological prospecting. The research presented in this thesis focuses on a study of how different anthropogenic changes in the ground can be detected by geochemical and geophysical mapping and how the results can be presented. A six-year pilot project, Svealand in Vendel and Viking periods (S...

  13. Geochemical modelling of groundwater evolution using chemical equilibrium codes

    International Nuclear Information System (INIS)

    Pitkaenen, P.; Pirhonen, V.

    1991-01-01

    Geochemical equilibrium codes are a modern tool in studying interaction between groundwater and solid phases. The most common used programs and application subjects are shortly presented in this article. The main emphasis is laid on the approach method of using calculated results in evaluating groundwater evolution in hydrogeological system. At present in geochemical equilibrium modelling also kinetic as well as hydrologic constrains along a flow path are taken into consideration

  14. Groundwater vulnerability mapping of Qatar aquifers

    Science.gov (United States)

    Baalousha, Husam Musa

    2016-12-01

    Qatar is one of the most arid countries in the world with limited water resources. With little rainfall and no surface water, groundwater is the only natural source of fresh water in the country. Whilst the country relies mainly on desalination of seawater to secure water supply, groundwater has extensively been used for irrigation over the last three decades, which caused adverse environmental impact. Vulnerability assessment is a widely used tool for groundwater protection and land-use management. Aquifers in Qatar are carbonate with lots of fractures, depressions and cavities. Karst aquifers are generally more vulnerable to contamination than other aquifers as any anthropogenic-sourced contaminant, especially above a highly fractured zone, can infiltrate quickly into the aquifer and spread over a wide area. The vulnerability assessment method presented in this study is based on two approaches: DRASTIC and EPIK, within the framework of Geographical Information System (GIS). Results of this study show that DRASTIC vulnerability method suits Qatar hydrogeological settings more than EPIK. The produced vulnerability map using DRASTIC shows coastal and karst areas have the highest vulnerability class. The southern part of the country is located in the low vulnerability class due to occurrence of shale formation within aquifer media, which averts downward movement of contaminants.

  15. Preliminary reactive geochemical transport simulation study on CO2 geological sequestration at the Changhua Coastal Industrial Park Site, Taiwan

    Science.gov (United States)

    Sung, R.; Li, M.

    2013-12-01

    assumed throughout the simulation domain. Comparisons among simulated results with different mesh systems of nested meshes and non-nested meshes and considerations of multiphase reactive transport and physical transport were demonstrated in this study. Preliminary results of injection CO2 for 50 years are: (1) about 7 wt.% of injected CO2 was trapped as carbonate minerals mainly as ankerite; (2) porosities were decreased by 0.014 % and increased by 0.102 % at the injection point and beneath the cap rock, respectively, and were subsequently decreased with time due to minerals precipitation mostly as illite and ankerite; (3) differences of simulated aquifer responses between reactive transport and physical transport were insignificant; and (4) projected CO2 plumes with the nested meshes was smaller than those by the non-nested meshes after cease of CO2 injection. Keywords: CO2-Saline-Mineral Interaction, Reactive Geochemical Transport, TOUGHREACT, Mineral Trapping Assessment, Changhua Costal Industrial Park Site, Taiwan Reference: Marini, L., 2006, Geological Sequestration of Carbon Dioxide, Volume 11: Thermodynamics, Kinetics, and Reaction Path Modeling, Elsevier Science, pp.470. Xu, T., J. A. Apps and K. Pruess, 2004, Numerical simulation of CO2 disposal by mineral trapping in deep aquifers, Applied Geochemistry, Vol. 19:917-936.

  16. Geochemical and isotopic evidences for a severe anthropogenic boron contamination: A case study from Castelluccio (Arezzo, central Italy)

    International Nuclear Information System (INIS)

    Venturi, Stefania; Vaselli, Orlando; Tassi, Franco; Nisi, Barbara; Pennisi, Maddalena; Cabassi, Jacopo; Bicocchi, Gabriele; Rossato, Luca

    2015-01-01

    In 2009 a deterioration of garden plants watered with domestic wells was related to high boron concentrations (up to 57 mg/L) measured in the shallow aquifer from the industrial area of Castelluccio (Tuscany, Italy), where several factories are or were using boron compounds for their industrial processes. Since 2012 a geochemical and isotopic survey of stream, ground and waste waters, and sediment samples was performed. In addition, monthly geochemical surveys were carried out from January to September 2013, during which concentrations of boron up to 139 mg/L were measured. The geochemical dataset also included raw (borax and sodium boron-hydride) and anthropogenic materials (B-rich slags and muds stored in one of the local factories), the latter being, to the best of our knowledge, analyzed for the first time in this work for bulk and leachate boron concentration and isotopic ratios. The results highlighted that the high concentrations of boron found in the local shallow aquifer had unequivocally an anthropogenic source. It was suggested that prolonged interaction between industrial (presently stored at ground level or buried) by-products and waste and meteoric waters was likely the main process responsible of the groundwater contamination as supported by the analysis of the major solutes. The dispersion of the contaminant could not clearly be observed downward the shallow hydrogeological circuit. Consequently, the presence of other sources of boron in the industrial area of Castelluccio cannot be excluded. This would also explain the reason why no univocal results were obtained by the "1"1B/"1"0B isotopic ratios measured in water, sediment and (bulk and leachate) anthropogenic samples. To minimize the boron contamination a hydraulic barrier should be constructed where the highest concentrations of boron were measured. - Highlights: • High boron concentrations were measured in a groundwater system near Arezzo (Italy). • Several factories in the local

  17. Potential impacts of leakage from deep CO2 geosequestration on overlying freshwater aquifers.

    Science.gov (United States)

    Little, Mark G; Jackson, Robert B

    2010-12-01

    Carbon Capture and Storage may use deep saline aquifers for CO(2) sequestration, but small CO(2) leakage could pose a risk to overlying fresh groundwater. We performed laboratory incubations of CO(2) infiltration under oxidizing conditions for >300 days on samples from four freshwater aquifers to 1) understand how CO(2) leakage affects freshwater quality; 2) develop selection criteria for deep sequestration sites based on inorganic metal contamination caused by CO(2) leaks to shallow aquifers; and 3) identify geochemical signatures for early detection criteria. After exposure to CO(2), water pH declines of 1-2 units were apparent in all aquifer samples. CO(2) caused concentrations of the alkali and alkaline earths and manganese, cobalt, nickel, and iron to increase by more than 2 orders of magnitude. Potentially dangerous uranium and barium increased throughout the entire experiment in some samples. Solid-phase metal mobility, carbonate buffering capacity, and redox state in the shallow overlying aquifers influence the impact of CO(2) leakage and should be considered when selecting deep geosequestration sites. Manganese, iron, calcium, and pH could be used as geochemical markers of a CO(2) leak, as their concentrations increase within 2 weeks of exposure to CO(2).

  18. Effects of Sea Level Rise on Groundwater Flow Paths in a Coastal Aquifer System

    Science.gov (United States)

    Morrissey, S. K.; Clark, J. F.; Bennett, M. W.; Richardson, E.; Stute, M.

    2008-05-01

    Changes in groundwater flow in the Floridan aquifer system, South Florida, from the rise in sea level at the end of the last glacial period may be indicative of changes coastal aquifers will experience with continued sea level rise. As sea level rises, the hydraulic head near the coast increases. Coastal aquifers can therefore experience decreased groundwater gradients (increased residence times) and seawater intrusion. Stable isotopes of water, dissolved noble gas temperatures, radiocarbon and He concentrations were analyzed in water collected from 68 wells in the Floridan aquifer system throughout South Florida. Near the recharge area, geochemical data along groundwater flow paths in the Upper Floridan aquifer show a transition from recently recharged groundwater to glacial-aged water. Down gradient from this transition, little variation is apparent in the stable isotopes and noble gas recharge temperatures, indicating that most of the Upper Floridan aquifer contains groundwater recharged during the last glacial period. The rapid 120-meter rise in sea level marking the end of the last glacial period increased the hydraulic head in the Floridan aquifer system near the coast, slowing the flow of groundwater from the recharge area to the ocean and trapping glacial-aged groundwater. The raised sea level also flooded half of the Florida platform and caused seawater to intrude into the Lower Floridan. This circulation of seawater in the Lower Floridan continues today as our data indicate that the groundwater is similar to modern seawater with a freshwater component entering vertically from the recharge area to the Upper Floridan.

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

    International Nuclear Information System (INIS)

    Pena, P.; Lopez, A.; Balcazar, M.; Flores, J.H.; Cardenas, S.; Schubert, M.

    2005-01-01

    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 -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)

  20. Summary report on geochemical barrier special study

    International Nuclear Information System (INIS)

    1988-12-01

    Long-term management of uranium mill tailings must provide assurance that soluble contaminants will not migrate beyond the Point of Compliance. Conventional management alternatives provide containment through the use of physical barriers which are designed to prevent migration of water through the tailings pile. An alternative is to geochemically modify the tailings to immobilize the contaminants. This investigation examined three potential geochemical modifiers to determine their ability to immobilize inorganic groundwater contaminants found in uranium mill tailings. These modifiers were hydrated lime (Ca(OH) 2 ), limestone (CaCO 3 ), and a sphaegnum peat moss. This investigation focused on both the geochemical interactions between the tailings and the modifiers, and the effects the modifiers had on the physical strength of the tailings. The geochemical investigations began with characterization of the tailings by X-ray diffraction and scanning electron microscopy. This was followed by batch leaching experiments in which various concentrations of each modifier were added to tailings in shaker flasks and allowed to come to equilibrium. Finally, column experiments were conducted to simulate flow through a tailings pile. The results show that all of the modifiers were at least moderately effective at immobilizing most of the groundwater contaminants of concern at uranium mill tailings sites. Hydrated lime was able to achieve 90 percent concentration reduction of arsenic, cadmium, selenium, uranium, and sulfate when added at a two percent concentration. Limestone was somewhat less effective and peat removed greater than 90 percent of arsenic, lead, uranium, and sulfate at a one percent concentration. The column tests showed that kinetic and/or mass transfer limitations are important and that sufficient time must be allowed for the immobilization reactions to occur

  1. PHAST--a program for simulating ground-water flow, solute transport, and multicomponent geochemical reactions

    Science.gov (United States)

    Parkhurst, David L.; Kipp, Kenneth L.; Engesgaard, Peter; Charlton, Scott R.

    2004-01-01

    The computer program PHAST simulates multi-component, reactive solute transport in three-dimensional saturated ground-water flow systems. PHAST is a versatile ground-water flow and solute-transport simulator with capabilities to model a wide range of equilibrium and kinetic geochemical reactions. The flow and transport calculations are based on a modified version of HST3D that is restricted to constant fluid density and constant temperature. The geochemical reactions are simulated with the geochemical model PHREEQC, which is embedded in PHAST. PHAST is applicable to the study of natural and contaminated ground-water systems at a variety of scales ranging from laboratory experiments to local and regional field scales. PHAST can be used in studies of migration of nutrients, inorganic and organic contaminants, and radionuclides; in projects such as aquifer storage and recovery or engineered remediation; and in investigations of the natural rock-water interactions in aquifers. PHAST is not appropriate for unsaturated-zone flow, multiphase flow, density-dependent flow, or waters with high ionic strengths. A variety of boundary conditions are available in PHAST to simulate flow and transport, including specified-head, flux, and leaky conditions, as well as the special cases of rivers and wells. Chemical reactions in PHAST include (1) homogeneous equilibria using an ion-association thermodynamic model; (2) heterogeneous equilibria between the aqueous solution and minerals, gases, surface complexation sites, ion exchange sites, and solid solutions; and (3) kinetic reactions with rates that are a function of solution composition. The aqueous model (elements, chemical reactions, and equilibrium constants), minerals, gases, exchangers, surfaces, and rate expressions may be defined or modified by the user. A number of options are available to save results of simulations to output files. The data may be saved in three formats: a format suitable for viewing with a text editor; a

  2. Sharp fronts within geochemical transport problems

    International Nuclear Information System (INIS)

    Grindrod, P.

    1995-01-01

    The authors consider some reactive geochemical transport problems in groundwater systems. When incoming fluid is in disequilibrium with the mineralogy sharp transition fronts may develop. They show that this is a generic property for a class of systems where the timescales associated with reaction and diffusion phenomena are much shorter than those associated with advective transport. Such multiple timescale problems are relevant to a variety of processes in natural systems: mathematically methods of singular perturbation theory reduce the dimension of the problems to be solved locally. Furthermore, they consider how spatial heterogeneous mineralogy can impact upon the propagation of sharp geochemical fronts. The authors developed an asymptotic approach in which they solve equations for the evolving geometry of the front and indicate how the non-smooth perturbations due to natural heterogeneity of the mineralogy on underlying ground water flow field are balanced against the smoothing effect of diffusion/dispersive processes. Fronts are curvature damped, and the results here indicate the generic nature of separate front propagation within both model (idealized) and natural (heterogeneous) geochemical systems

  3. Long-distance electron transfer by cable bacteria in aquifer sediments

    DEFF Research Database (Denmark)

    Müller, Hubert; Bosch, Julian; Griebler, Christian

    2016-01-01

    recycling of sulfate by electron transfer over 1–2-cm distance. Sediments were taken from a hydrocarbon-contaminated aquifer, amended with iron sulfide and saturated with water, leaving the sediment surface exposed to air. Steep geochemical gradients developed in the upper 3 cm, showing a spatial separation...... recently been discovered in marine sediments to couple spatially separated redox half reactions over centimeter scales. Here we provide primary evidence that such sulfur-oxidizing cable bacteria can also be found at oxic–anoxic interfaces in aquifer sediments, where they provide a means for the direct...

  4. Carbon dioxide (CO2) sequestration in deep saline aquifers and formations: Chapter 3

    Science.gov (United States)

    Rosenbauer, Robert J.; Thomas, Burt

    2010-01-01

    Carbon dioxide (CO2) capture and sequestration in geologic media is one among many emerging strategies to reduce atmospheric emissions of anthropogenic CO2. This chapter looks at the potential of deep saline aquifers – based on their capacity and close proximity to large point sources of CO2 – as repositories for the geologic sequestration of CO2. The petrochemical characteristics which impact on the suitability of saline aquifers for CO2 sequestration and the role of coupled geochemical transport models and numerical tools in evaluating site feasibility are also examined. The full-scale commercial CO2 sequestration project at Sleipner is described together with ongoing pilot and demonstration projects.

  5. Haemorrhagic diarrhoea and reproductive failure in Bonsmara cattle resulting from anomalous heavy metal concentrations in soils, forages and drinking water associated with geochemical anomalies of toxic elements on the farm Puntlyf, South Africa

    Science.gov (United States)

    Elsenbroek, J. H.; Meyer, J.; Myburgh, J.

    2003-05-01

    Poor livestock health conditions are associated with geochemical Pb anomalies on a farm approximately 40km east of Pretoria, South Africa. A generic risk assessment of drinking water for Bonsmara cattle obtained from three separate subterranean water sources on the farm, revealed the presence of several potentially hazardous constituents suspected for the development of adverse health effects in the herd. The two main symptoms of the herd, namely, severe haemorrhagic diarrhoea in calves and reproductive failure in cows, have been investigated. A selenium-induced copper deficiency was proposed as the main cause to the calf diarrhoea, due to complexing between high concentrations of Se, Mo, Hg and Pb in drinking water. It was also anticipated that such Cu deficiencies would lead to low systemic Se inducing hypothyroidism in the cows due to inadequate iodine activation required for thyroid hormone formation and consequently adversely affect reproduction. The anomalous Pb in borehole drinking water on the southem part of the farm, suggests a clear genetic link with the underlying geochemical Pb anomalies detected by means of an ongoing regional geochemical survey.

  6. Role of Dissolved Organic Matter and Geochemical Controls on Arsenic Cycling from Sediments to Groundwater along the Meghna River, Bangladesh: Tracking possible links to permeable natural reactive barrier

    Science.gov (United States)

    Datta, S.; Berube, M.; Knappett, P.; Kulkarni, H. V.; Vega, M.; Jewell, K.; Myers, K.

    2017-12-01

    Elevated levels of dissolved arsenic (As), iron (Fe) and manganese (Mn) are seen in the shallow groundwaters of southeast Bangladesh on the Ganges Brahmaputra Meghna River delta. This study takes a multi disciplinary approach to understand the extent of the natural reactive barrier (NRB) along the Meghna River and evaluate the role of the NRB in As sequestration and release in groundwater aquifers. Shallow sediment cores, and groundwater and river water samples were collected from the east and west banks of the Meghna. Groundwater and river water samples were tested for FeT, MnT, and AsT concentrations. Fluorescence spectroscopic characterization of groundwater dissolved organic matter (DOM) provided insight into the hydro geochemical reactions active in the groundwater and the hyporheic zones. Eight sediment cores of 1.5 m depth were collected 10 m away from the edge of the river. Vertical solid phase concentration profiles of Fe, Mn and As were measured via 1.2 M HCl digestion which revealed solid phase As accumulation along the riverbanks up to concentrations of 1500 mg/kg As. Microbial interactions with DOM prompts the reduction of Fe3+ to Fe2+, causing As to mobilize into groundwater and humic-like DOM present in the groundwater may catalyze this process. The extent to which microbially mediated release of As occurs is limited by labile dissolved organic carbon (DOC) availability. Aqueous geochemical results showed the highest dissolved As concentrations in shallow wells (groundwater was found to contain microbial and terrestrial derived DOC, and decomposed, humified and aromatic DOM. Deeper aquifers had a significantly larger microbial OM signature than the shallower aquifers and was less aromatic, decomposed and humified. The results from this study illustrate the potential for humic substances to contribute to As cycling and quantify the extent of As accumulation in the sediments and groundwater along a 1 km stretch of the Meghna. These findings contribute

  7. Geochemical evolution of groundwater salinity at basin scale: a case study from Datong basin, Northern China.

    Science.gov (United States)

    Wu, Ya; Wang, Yanxin

    2014-05-01

    A hydrogeochemical investigation using integrated methods of stable isotopes ((18)O, (2)H), (87)Sr/(86)Sr ratios, Cl/Br ratios, chloride-mass balance, mass balance and hydrogeochemical modeling was conducted to interpret the geochemical evolution of groundwater salinity in Datong basin, northern China. The δ(2)H, δ(18)O ratios in precipitation exhibited a local meteoric water line of δ(2)H = 6.4 δ(18)O -5 (R(2) = 0.94), while those in groundwater suggested their meteoric origin in a historically colder climatic regime with a speculated recharge rate of less than 20.5 mm overall per year, in addition to recharge from a component of deep residual ancient lake water enriched with Br. According to the Sr isotope binary mixing model, the mixing of recharges from the Shentou karst springs (24%), the western margins (11%) and the eastern margins (65%) accounts for the groundwater from the deep aquifers of the down-gradient parts in the central basin is a possible mixing mechanism. In Datong, hydrolysis of silicate minerals is the most important hydrogeochemical process responsible for groundwater chemistry, in addition to dissolution of carbonate and evaporites. In the recharge areas, silicate chemical weathering is typically at the bisiallitization stage, while that in the central basin is mostly at the monosiallitization stage with limited evidence of being in equilibrium with gibbsite. Na exchange with bound Ca, Mg prevails at basin scale, and intensifies with groundwater salinity, while Ca, Mg exchange with bound Na locally occurs in the east pluvial and alluvial plains. Although groundwater salinity increases with the progress of water-rock/sediment interactions along the flow path, as a result of carbonate solubility control and continuous evapotranspiration, Na-HCO3 and Na-Cl-SO4 types of water are usually characterized respectively in the deep and the shallow aquifers of an inland basin with a silicate terrain in an arid climatic regime.

  8. Ground-water quality of the surficial aquifer system and the upper Floridan Aquifer, Ocala National Forest and Lake County, Florida, 1990-99

    Science.gov (United States)

    Adamski, J.C.; Knowles, Leel

    2001-01-01

    Data from 217 ground-water samples were statistically analyzed to assess the water quality of the surficial aquifer system and Upper Floridan aquifer in the Ocala National Forest and Lake County, Florida. Samples were collected from 49 wells tapping the surficial aquifer system, 141 wells tapping the Upper Floridan aquifer, and from 27 springs that discharge water from the Upper Floridan aquifer. A total of 136 samples was collected by the U.S. Geological Survey from 1995 through 1999. These data were supplemented with 81 samples collected by the St. Johns River Water Management District and Lake County Water Resources Management from 1990 through 1998. In general, the surficial aquifer system has low concentrations of total dissolved solids (median was 41 milligrams per liter) and major ions. Water quality of the surficial aquifer system, however, is not homogeneous throughout the study area. Concentrations of total dissolved solids, many major ions, and nutrients are greater in samples from Lake County outside the Ocala National Forest than in samples from within the Forest. These results indicate that the surficial aquifer system in Lake County outside the Ocala National Forest probably is being affected by agricultural and (or) urban land-use practices. High concentrations of dissolved oxygen (less than 0.1 to 8.2 milligrams per liter) in the surficial aquifer system underlying the Ocala National Forest indicate that the aquifer is readily recharged by precipitation and is susceptible to surface contamination. Concentrations of total dissolved solids were significantly greater in the Upper Floridan aquifer (median was 182 milligrams per liter) than in the surficial aquifer system. In general, water quality of the Upper Floridan aquifer was homogeneous, primarily being a calcium or calciummagnesium- bicarbonate water type. Near the St. Johns River, the water type of the Upper Floridan aquifer is sodium-chloride, corresponding to an increase in total dissolved

  9. Concerning evaluation of eco-geochemical background in remediation strategy

    Science.gov (United States)

    Korobova, Elena; Romanov, Sergey

    2015-04-01

    The geochemical concept of biosphere developed by V.I. Vernadsky states the geological role of the living organisms in the course of their active chemical interaction with the inert matter (Vernadsky, 1926, 1960). Basing on this theory it is reasonable to suggest that coevolution of living organisms and their environment led to development of the dynamically stable biogeocenoses precisely adequate to their geochemical environment. Soil cover was treated by V.I. Vernadsky as a balanced bio-inert matter resulting from this interaction. Appearance of human mind and then a civilization led to global expansion of human beings, first able to survive in unfavorable geochemical conditions and then starting chemical transformation of the environment to satisfy the growing demands of mankind in food and energy. The residence in unfavorable environment and local contamination was followed by appearance of endemic diseases of plants, animals and man. Therefore zonal, regional and local chemical composition of the soil cover formed in natural conditions may be used for estimation of the optimum geochemical background, most adequate for the corresponding zonal biogeocenoses and species. Moreover, the natural geochemical background and technogenic fields have unequal spatial structure and this facilitates their identification that may be relatively easy realized in remediation strategy. On the assumption of the foregoing, the adequate methodical approach to remediation of technogenically affected areas should account of the interaction of the existing natural and the newly formed technogenic geochemical fields and include the following steps: 1) the study and mapping of geochemical structure of the natural geochemical background basing on soil maps; 2) the study of contaminants and mapping spatial distribution of technogenic releases; 3) construction of risk maps for the target risk groups with due regard to natural ecological threshold concentration in context of risk degree for

  10. 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.

  11. Observation of a Distinct Transition in Transport Response to Injection Stress in the Floridan Aquifer System, Southeastern Florida, U.S.A

    Science.gov (United States)

    King, J. N.; Cunningham, K. J.; Foster, A. L.

    2011-12-01

    The Miami-Dade Water and Sewer Department (MDWASD) injects effluent approximately one km below land surface into the Boulder Zone (BZ) at the North District Wastewater Treatment Plant (NDWWTP). The BZ is highly conductive and composed of fractured dolomite. MDWASD monitors upward effluent migration 450 m below land surface in the Avon Park Permeable Zone (APPZ). The BZ and APPZ---units within the Floridan aquifer system---are separated by a series of inter-bedded aquifers and leaky confining units with hydraulic conductivities that are orders of magnitude smaller than the BZ. MDWASD injected effluent at the NDWWTP during two distinct periods: (1) July 1997 to September 1999, and (2) August 2004 to January 2011. No effluent was injected between October 1999 and July 2004. A few months after the July 1997 injection, MDWASD observed effluent constituents in the APPZ (Figure 1). Some confinement bypass feature permits effluent constituents to be transported from the BZ to the APPZ. Bypass features may include poorly-cased wells, or natural conduits such as fractures, faults, or karst collapse systems. It is possible to describe confinement bypass features with conductance KA/L, where K is hydraulic conductivity, A is cross-sectional area, and L is length. MDWASD observed a distinct transition in the transport response to injection stress of total dissolved solids (TDS) concentration in the APPZ. The conductance required to describe early system response (1997-1999) is one order-of-magnitude larger than the conductance required to describe late system response (2004-2011). Hypotheses to explain transient conductance include clogging of bypass features by some geochemical or biological process that results from the mixing of effluent with groundwater; dissolution or precipitation; or changes in bypass-feature geometry forced by cyclical changes in aquifer-fluid pressure associated with injection. Hypotheses may be tested with geochemical analyses, tracer tests, hydraulic

  12. Geochemistry and origins of mineralized waters in the Floridan aquifer system, northeastern Florida

    Science.gov (United States)

    Phelps, G.G.

    2001-01-01

    Increases in chloride concentration have been observed in water from numerous wells tapping the Floridan aquifer system in northeastern Florida. Although most increases have been in the eastern part of Duval County, Florida, no spatial pattern in elevated chloride concentrations is discernible. Possible sources of the mineralized water include modern seawater intrusion; unflushed Miocene-to-Pleistocene-age seawater or connate water in aquifer sediments; or mineralized water from deeper zones of the aquifer system or from formations beneath the Floridan aquifer system. The purpose of this study was to document the chemical and isotopic characteristics of water samples from various aquifer zones, and from geochemical and hydrogeologic data, to infer the source of the increased mineralization. Water samples were collected from 53 wells in northeastern Florida during 1997-1999. Wells tapped various zones of the aquifer including: the Fernandina permeable zone (FPZ), the upper zone of the Lower Floridan aquifer (UZLF), the Upper Floridan aquifer (UFA), and both the UFA and the UZLF. Water samples were analyzed for major ions and trace constituents and for isotopes of carbon, oxygen, hydrogen, sulfur, strontium, chlorine, and boron. Samples of rock from the aquifer were analyzed for isotopes of oxygen, carbon, and strontium. In general, water from various aquifer zones cannot be differentiated based on chemistry, except for water from FPZ wells. Major-ion concentrations vary as much within the upper zone of the Lower Floridan aquifer and the Upper Floridan aquifer as between these two zones. Simple models of mixing between fresh ground water and either modern seawater or water from the FPZ as a mineralized end member show that many water samples from the UZLF aquifer and the UFA are enriched in bicarbonate, calcium, magnesium, sulfate, fluoride, and silica and are depleted in sodium and potassium (as compared to concentrations predicted by simple mixing). Chemical mass

  13. Corrigenda: Epigean and hypogean Palaemonetes sp. (Decapoda, Palaemonidae from Edwards Aquifer: An examination of trophic structure and metabolism. Subterranean Biology 14: 79–102.

    Directory of Open Access Journals (Sweden)

    Renee Bishop

    2015-06-01

    Full Text Available This study addresses the causes of the metabolic depression observed when examining the metabolism of hypogean versus epigean organisms. We examined the two current hypotheses regarding the cause of metabolic cave adaptation, a paucity of food and low oxygen availability, both necessary for ATP production, by first determining if the hypogean environment examined, Edwards Aquifer, was resource limited. Stable isotope analyses indicate that there is extensive microbial chemolithoautotrophic production providing resources for the hypogean organisms. δ13C values ( ≤30‰ were well below that of terrestrial biome indicating that C in the aquifer originates from chemolithoautotrophic inorganic carbon fixation, not photosynthetically derived material resulting from terrigenous sources. Data suggest the artesian system is a complex geochemical ecosystem providing inorganic energy sources from both methane and sulfates. Metabolism, examined via key aerobic and anaerobic proxies, and organismal proximate composition indicated there was no difference between metabolic rates and energy storage of Palaemonetes antrorum (stygobitic and Palaemonetes kadiakensis (epigean. This indicates that resources within the oxic aquifer are not limited. We demonstrate that it is necessary for one, or both, of these selective pressures to be present for metabolic cave adaptation to occur.

  14. Geochemical and mineralogical characteristics of Lithomargic clay

    African Journals Online (AJOL)

    Administrator

    Geochemical and mineralogical characteristics of Lithomargic clay. GEOCHEMICAL AND .... tries, as filling material in the pulp and paper, toothpaste and paint industries as well ..... tions very vital to human health and other ac- tivities of man.

  15. NOAA and MMS Marine Minerals Geochemical Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Marine Minerals Geochemical Database was created by NGDC as a part of a project to construct a comprehensive computerized bibliography and geochemical database...

  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

  17. Oak Ridge Geochemical Reconnaissance Program

    International Nuclear Information System (INIS)

    Arendt, J.W.

    1977-03-01

    The Oak Ridge reconnaissance program is responsible for the geochemical survey in a 12-state area covering Texas, Oklahoma, Kansas, Nebraska, South Dakota, North Dakota, Minnesota, Wisconsin, Michigan, Iowa, Indiana, and Illinois as part of the National Uranium Resource Evaluation Program. The program concept is outlined and the planning and organization of the program is discussed

  18. Granite-repository - geochemical environment

    International Nuclear Information System (INIS)

    1979-04-01

    Some geochemical data of importance for a radioactive waste repository in hard rock are reviewed. The ground water composition at depth is assessed. The ground water chemistry in the vicinity of uranium ores is discussed. The redox system in Swedish bedrock is described. Influences of extreme climatic changes and of repository mining and construction are also evaluated

  19. Coastal groundwater salinization: Focus on the vertical variability in a multi-layered aquifer through a multi-isotope fingerprinting (Roussillon Basin, France)

    Energy Technology Data Exchange (ETDEWEB)

    Petelet-Giraud, Emmanuelle, E-mail: e.petelet@brgm.fr [BRGM, Avenue C. Guillemin, BP 36009, 45060 Orléans Cedex 02 (France); Négrel, Philippe [BRGM, Avenue C. Guillemin, BP 36009, 45060 Orléans Cedex 02 (France); Aunay, Bertrand [BRGM, Réunion Agency, 5, rue Sainte-Anne, CS 51016, 97404 Saint Denis Cedex (France); Ladouche, Bernard; Bailly-Comte, Vincent [BRGM Montpellier Agency, 1039, rue de Pinville, 34000 Montpellier (France); Guerrot, Catherine; Flehoc, Christine [BRGM, Avenue C. Guillemin, BP 36009, 45060 Orléans Cedex 02 (France); Pezard, Philippe; Lofi, Johanna [Géosciences Montpellier, UMR 5243, Université de Montpellier, cc069, Place Eugène Bataillon, 34095 Montpellier Cedex 05 (France); Dörfliger, Nathalie [BRGM, Avenue C. Guillemin, BP 36009, 45060 Orléans Cedex 02 (France)

    2016-10-01

    The Roussillon sedimentary Basin (South France) is a complex multi-layered aquifer, close to the Mediterranean Sea facing seasonally increases of water abstraction and salinization issues. We report geochemical and isotopic vertical variability in this aquifer using groundwater sampled with a Westbay System® at two coastal monitoring sites: Barcarès and Canet. The Westbay sampling allows pointing out and explaining the variation of water quality along vertical profiles, both in productive layers and in the less permeable ones where most of the chemical processes are susceptible to take place. The aquifer layers are not equally impacted by salinization, with electrical conductivity ranging from 460 to 43,000 μS·cm{sup −1}. The δ{sup 2}H–δ{sup 18}O signatures show mixing between seawater and freshwater components with long water residence time as evidenced by the lack of contribution from modern water using {sup 3}H, {sup 14}C and CFCs/SF6. S(SO{sub 4}) isotopes also evidence seawater contribution but some signatures can be related to oxidation of pyrite and/or organically bounded S. In the upper layers {sup 87}Sr/{sup 86}Sr ratios are close to that of seawater and then increase with depth, reflecting water–rock interaction with argillaceous formations while punctual low values reflect interaction with carbonate. Boron isotopes highlight secondary processes such as adsorption/desorption onto clays in addition to mixings. At the Barcarès site (120 m deep), the high salinity in some layers appear to be related neither to present day seawater intrusion, nor to Salses-Leucate lagoonwater intrusion. Groundwater chemical composition thus highlights binary mixing between fresh groundwater and inherited salty water together with cation exchange processes, water–rock interactions and, locally, sedimentary organic matter mineralisation probably enhanced by pyrite oxidation. Finally, combining the results of this study and those of Caballero and Ladouche (2015

  20. Arsenic levels in groundwater aquifer

    African Journals Online (AJOL)

    Miodrag Jelic

    resistance (ρ); dielectric constant (ε); magnetic permeability (η); electrochemical activity ..... comprises grey sands of different particle size distribution ..... groundwater: testing pollution mechanisms for sedimentary aquifers in. Bangladesh.

  1. Assessing the vulnerability of public-supply wells to contamination—Edwards aquifer near San Antonio, Texas

    Science.gov (United States)

    Jagucki, Martha L.; Musgrove, MaryLynn; Lindgren, Richard J.; Fahlquist, Lynne; Eberts, Sandra M.

    2011-01-01

    This fact sheet highlights findings from the vulnerability study of a public-supply well field in San Antonio, Texas. The well field consists of six production wells that tap the Edwards aquifer. Typically, one or two wells are pumped at a time, yielding an average total of 20-21 million gallons per day. Water samples were collected from public-supply wells in the well field and from monitoring wells installed along general directions of flow to the well field. Samples from the well field contained some constituents of concern for drinking-water quality, including nitrate; the pesticide compounds atrazine, deethylatrazine, and simazine; and the volatile organic compounds tetrachloroethene (also called perchloroethene, or PCE), chloroform, bromoform, and dibromochloromethane. These constituents were detected in untreated water at concentrations much less than established drinking-water standards, where such standards exist. Overall, the study findings point to four primary factors that affect the movement and fate of contaminants and the vulnerability of the public-supply well field in San Antonio, Texas: (1) groundwater age (how long ago water entered, or recharged, the aquifer), (2) fast pathways for flow of groundwater through features formed or enlarged by dissolution of bedrock, (3) recharge characteristics of the aquifer, and (4) natural geochemical processes within the aquifer. A computer-model simulation of groundwater flow and transport was used to estimate the traveltime (or age) of water particles entering public-supply well W4 in the well field. Modeled findings show that almost half of the water reaching the public-supply well is less than 2 years old. Such a large percentage of very young water indicates that (1) contaminants entering the aquifer may be transported rapidly to the well, (2) there is limited time for chemical reactions to occur in the aquifer that may attenuate contaminants, and (3) should recharge water become contaminated with

  2. EPA Region 1 Sole Source Aquifers

    Data.gov (United States)

    U.S. Environmental Protection Agency — This coverage contains boundaries of EPA-approved sole source aquifers. Sole source aquifers are defined as an aquifer designated as the sole or principal source of...

  3. 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

  4. Mercury concentration, speciation and budget in volcanic aquifers: Italy and Guadeloupe (Lesser Antilles)

    Science.gov (United States)

    Bagnato, E.; Aiuppa, A.; Parello, F.; D'Alessandro, W.; Allard, P.; Calabrese, S.

    2009-01-01

    Quantifying the contribution of volcanism to global mercury (Hg) emissions is important to understand the pathways and the mechanisms of Hg cycling through the Earth's geochemical reservoirs and to assess its environmental impacts. While previous studies have suggested that degassing volcanoes might contribute importantly to the atmospheric budget of mercury, little is known about the amount and behaviour of Hg in volcanic aquifers. Here we report on detailed investigations of both the content and the speciation of mercury in aquifers of active volcanoes in Italy and Guadeloupe Island (Lesser Antilles). In the studied groundwaters, total Hg (THg) concentrations range from 10 to 500 ng/l and are lower than the 1000 ng/l threshold value for human health protection fixed by the World Health Organization [WHO (1993): WHO Guidelines for Drinking Water Quality- http://www.who.int/water_sanitation_health/GDWQ/index.htlm]. Positive co-variations of (THg) with sulphate indicate that Hg-SO 4-rich acid groundwaters receive a direct input of magmatic/hydrothermal gases carrying mercury as Hg 0(gas). Increasing THg in a volcanic aquifer could thus be a sensitive tracer of magmatic gas input prior to an eruption. Since the complex behaviour and toxicity of mercury in waters depend on its chemical speciation, we carefully determined the different aqueous forms of this element in our samples. We find that dissolved elemental Hg 0(aq) and particulate-bound Hg (Hg P) widely prevail in volcanic aquifers, in proportions that highlight the efficiency of Hg adsorption onto colloidal particles. Moreover, we observe that dissolved Hg 0aq and Hg(II) forms coexist in comparable amount in most of the waters, in stark contrast to the results of thermodynamic equilibrium modelling. Therefore, chemical equilibrium between dissolved mercury species in volcanic waters is either prevented by natural kinetic effects or not preserved in collected waters due to sampling/storage artefacts. Finally, we

  5. Depth and temporal variations in water quality of the Snake River Plain aquifer in well USGS-59 near the Idaho Chemical Processing Plant at the Idaho National Engineering and Environmental Laboratory

    International Nuclear Information System (INIS)

    Frederick, D.B.; Johnson, G.S.

    1997-03-01

    In-situ measurements of the specific conductance and temperature of ground water in the Snake River Plain aquifer were collected in observation well USGS-59 near the Idaho Chemical Processing Plant at the Idaho National Engineering and Environmental Laboratory. These parameters were monitored at various depths in the aquifer from October 1994 to August 1995. The specific conductance of ground water in well USGS-59, as measured in the borehole, ranged from about 450 to 900 microS/cm at standard temperature (25 C). The pumping cycle of the production wells at the Idaho Chemical Processing Plant causes changes in borehole circulation patterns, and as a result the specific conductance of ground water at some depths in the well varies by up to 50% over a period of about 14 hours. However, these variations were not observed at all depths, or during each pumping cycle. The temperature of ground water in the well was typically between 12.8 and 13.8 C. The results of this study indicate that temporal variations in specific conductance of the ground water at this location are caused by an external stress on the aquifer--pumping of a production well approximately 4,000 feet away. These variations are believed to result from vertical stratification of water quality in the aquifer and a subsequent change in intrawell flow related to pumping. When sampling techniques that do not induce a stress on the aquifer (i.e., thief sampling) are used, knowledge of external stresses on the system at the time of sampling may aid in the interpretation of geochemical data

  6. Reactive Transport of Marcellus Shale Waters in Natural Aquifers: the Role of Mineralogical Compositions and Spatial Distribution Patterns

    Science.gov (United States)

    Cai, Z.; Wen, H.; Li, L.

    2017-12-01

    Accidental release of Marcellus Shale waters (MSW) can release high concentrations of chemicals that can deteriorate groundwater quality. It is important to understand the reactive transport and fate of chemicals from MSW. Natural aquifers typically have complex mineralogical compositions and are heterogeneous with large spatial variation in terms of physical and geochemical properties. To investigate the effects of mineralogical compositions, flow-through experiments and reactive transport modeling were carried out using 3 large columns (5 cm×50 cm, Quartz, Calcite, and Vermiculite). Results indicate calcite immobilizes heavy metals by precipitation and solid solution partitioning (coprecipitation). Vermiculite retards heavy metals through ion exchange. The sorbed chemicals however slowly release back to the groundwater. Na and Ca transport similarly to Br in Qtz and Cal columns however become sorbed in Vrm column during release through ion exchange by 27.8% and 46.5%, respectively and later slowly release back to aqueous phase. To understand the role of mineral spatial patterns, three 2D flow-cell (40 cm×12 cm×1 cm) experiments were carried out. All flow cells have the same clay mass within quartz matrix but different spatial patterns characterized by the relative length of the clay zone ( 0, ¼, ½) of the domain length (L). Results show that in the uniform column, ion exchange dominates and most Ba sorbs to the solid phase, to an extent Ba cannot precipitate out with SO4 as barite. In 1/2-Zone, however, most Ba precipitates as barite. In 1/4-Zone, both ion exchange and mineral precipitation occur. In general, the 1/2-Zone has the smallest ion exchange capacity for other species including Na, Ca, Mg, K and heavy metals (Mn, Cu, Zn, Cd and Pb) as well. Our flow cell experiment emphasizes the importance of mineral spatial patterns in regulating not only reaction rates but also the type of reactions in controlling the reactive transport of MSW chemicals. The

  7. Surface complexation modeling for predicting solid phase arsenic concentrations in the sediments of the Mississippi River Valley alluvial aquifer, Arkansas, USA

    Science.gov (United States)

    Sharif, M.S.U.; Davis, R.K.; Steele, K.F.; Kim, B.; Hays, P.D.; Kresse, T.M.; Fazio, J.A.

    2011-01-01

    The potential health impact of As in drinking water supply systems in the Mississippi River Valley alluvial aquifer in the state of Arkansas, USA is significant. In this context it is important to understand the occurrence, distribution and mobilization of As in the Mississippi River Valley alluvial aquifer. Application of surface complexation models (SCMs) to predict the sorption behavior of As and hydrous Fe oxides (HFO) in the laboratory has increased in the last decade. However, the application of SCMs to predict the sorption of As in natural sediments has not often been reported, and such applications are greatly constrained by the lack of site-specific model parameters. Attempts have been made to use SCMs considering a component additivity (CA) approach which accounts for relative abundances of pure phases in natural sediments, followed by the addition of SCM parameters individually for each phase. Although few reliable and internally consistent sorption databases related to HFO exist, the use of SCMs using laboratory-derived sorption databases to predict the mobility of As in natural sediments has increased. This study is an attempt to evaluate the ability of the SCMs using the geochemical code PHREEQC to predict solid phase As in the sediments of the Mississippi River Valley alluvial aquifer in Arkansas. The SCM option of the double-layer model (DLM) was simulated using ferrihydrite and goethite as sorbents quantified from chemical extractions, calculated surface-site densities, published surface properties, and published laboratory-derived sorption constants for the sorbents. The model results are satisfactory for shallow wells (10.6. m below ground surface), where the redox condition is relatively oxic or mildly suboxic. However, for the deep alluvial aquifer (21-36.6. m below ground surface) where the redox condition is suboxic to anoxic, the model results are unsatisfactory. ?? 2011 Elsevier Ltd.

  8. Geophysical Monitoring of Coupled Microbial and Geochemical Processes During Stimulated Subsurface Bioremediation

    International Nuclear Information System (INIS)

    Williams, Kenneth H.; Kemna, Andreas; Wilkins, Michael J.; Druhan, Jennifer L.; Arntzen, Evan V.; N'Guessan, A. Lucie; Long, Philip E.; Hubbard, Susan S.; Banfield, Jillian F.

    2009-01-01

    Understanding how microorganisms alter their physical and chemical environment during bioremediation is hindered by our inability to resolve subsurface microbial activity with high spatial resolution. Here we demonstrate the use of a minimally invasive geophysical technique to monitor stimulated microbial activity during acetate amendment in an aquifer near Rifle, Colorado. During electrical induced polarization (IP) measurements, spatiotemporal variations in the phase response between imposed electric current and the resultant electric field correlated with changes in groundwater geochemistry accompanying stimulated iron and sulfate reduction and sulfide mineral precipitation. The magnitude of the phase response varied with measurement frequency (0.125 and 1 Hz) and was dependent upon the dominant metabolic process. The spectral effect was corroborated using a biostimulated column experiment containing Rifle sediments and groundwater. Fluids and sediments recovered from regions exhibiting an anomalous phase response were enriched in Fe(II), dissolved sulfide, and cell-associated FeS nanoparticles. The accumulation of mineral precipitates and electroactive ions altered the ability of pore fluids to conduct electrical charge, accounting for the anomalous IP response and revealing the usefulness of multifrequency IP measurements for monitoring mineralogical and geochemical changes accompanying stimulated subsurface bioremediation

  9. Genesis and evolution of the fumaroles of vulcano (Aeolian Islands, Italy): a geochemical model

    Science.gov (United States)

    Carapezza, M.; Nuccio, P. M.; Valenza, M.

    1981-09-01

    A geochemical model explaining the presence of fumaroles having different gas composition and temperature at the top of the crater and along the northeastern coast of Vulcano island is proposed. A pressurized biphase (liquid-vapor) reservoir at the depth of about 2 km is hypothesized. Energy and mass balance sheets control P-T conditions in the system. P-T must vary along a boiling curve of brine as liquid is present. The CO2 content in the steam is governed by the thermodynamic properties of the fluids in the H2-NaCl-CO2 system. On the assumption that oxygen fugacity in the system is between the HM-FMQ oxygen buffers, observed SO2/H2S, CO2/CO, CO/CH4 ratios in the fumarolic gases at the Fossa crater appear in equilibrium with a temperature higher than that observed, such as may exist at depth. The more reduced gas phases present on the sea-side may result from re-equilibrium processes in shallower aquifers. The suggested model would help in monitoring changes in volcanic activity by analyzing fumarolic gases.

  10. Source, variability, and transformation of nitrate in a regional karst aquifer: Edwards aquifer, central Texas

    Energy Technology Data Exchange (ETDEWEB)

    Musgrove, M., E-mail: mmusgrov@usgs.gov [U.S. Geological Survey, 1505 Ferguson Lane, Austin, TX 78754 (United States); Opsahl, S.P. [U.S. Geological Survey, 5563 DeZavala, Ste. 290, San Antonio, TX 78249 (United States); Mahler, B.J. [U.S. Geological Survey, 1505 Ferguson Lane, Austin, TX 78754 (United States); Herrington, C. [City of Austin Watershed Protection Department, Austin, TX 78704 (United States); Sample, T.L. [U.S. Geological Survey, 19241 David Memorial Dr., Ste. 180, Conroe, TX 77385 (United States); Banta, J.R. [U.S. Geological Survey, 5563 DeZavala, Ste. 290, San Antonio, TX 78249 (United States)

    2016-10-15

    Many karst regions are undergoing rapid population growth and expansion of urban land accompanied by increases in wastewater generation and changing patterns of nitrate (NO{sub 3}{sup −}) loading to surface and groundwater. We investigate variability and sources of NO{sub 3}{sup −} in a regional karst aquifer system, the Edwards aquifer of central Texas. Samples from streams recharging the aquifer, groundwater wells, and springs were collected during 2008–12 from the Barton Springs and San Antonio segments of the Edwards aquifer and analyzed for nitrogen (N) species concentrations and NO{sub 3}{sup −} stable isotopes (δ{sup 15}N and δ{sup 18}O). These data were augmented by historical data collected from 1937 to 2007. NO{sub 3}{sup −} concentrations and discharge data indicate that short-term variability (days to months) in groundwater NO{sub 3}{sup −} concentrations in the Barton Springs segment is controlled by occurrence of individual storms and multi-annual wet-dry cycles, whereas the lack of short-term variability in groundwater in the San Antonio segment indicates the dominance of transport along regional flow paths. In both segments, longer-term increases (years to decades) in NO{sub 3}{sup −} concentrations cannot be attributed to hydrologic conditions; rather, isotopic ratios and land-use change indicate that septic systems and land application of treated wastewater might be the source of increased loading of NO{sub 3}{sup −}. These results highlight the vulnerability of karst aquifers to NO{sub 3}{sup −} contamination from urban wastewater. An analysis of N-species loading in recharge and discharge for the Barton Springs segment during 2008–10 indicates an overall mass balance in total N, but recharge contains higher concentrations of organic N and lower concentrations of NO{sub 3}{sup −} than does discharge, consistent with nitrification of organic N within the aquifer and consumption of dissolved oxygen. This study demonstrates

  11. Source, variability, and transformation of nitrate in a regional karst aquifer: Edwards aquifer, central Texas

    International Nuclear Information System (INIS)

    Musgrove, M.; Opsahl, S.P.; Mahler, B.J.; Herrington, C.; Sample, T.L.; Banta, J.R.

    2016-01-01

    Many karst regions are undergoing rapid population growth and expansion of urban land accompanied by increases in wastewater generation and changing patterns of nitrate (NO 3 − ) loading to surface and groundwater. We investigate variability and sources of NO 3 − in a regional karst aquifer system, the Edwards aquifer of central Texas. Samples from streams recharging the aquifer, groundwater wells, and springs were collected during 2008–12 from the Barton Springs and San Antonio segments of the Edwards aquifer and analyzed for nitrogen (N) species concentrations and NO 3 − stable isotopes (δ 15 N and δ 18 O). These data were augmented by historical data collected from 1937 to 2007. NO 3 − concentrations and discharge data indicate that short-term variability (days to months) in groundwater NO 3 − concentrations in the Barton Springs segment is controlled by occurrence of individual storms and multi-annual wet-dry cycles, whereas the lack of short-term variability in groundwater in the San Antonio segment indicates the dominance of transport along regional flow paths. In both segments, longer-term increases (years to decades) in NO 3 − concentrations cannot be attributed to hydrologic conditions; rather, isotopic ratios and land-use change indicate that septic systems and land application of treated wastewater might be the source of increased loading of NO 3 − . These results highlight the vulnerability of karst aquifers to NO 3 − contamination from urban wastewater. An analysis of N-species loading in recharge and discharge for the Barton Springs segment during 2008–10 indicates an overall mass balance in total N, but recharge contains higher concentrations of organic N and lower concentrations of NO 3 − than does discharge, consistent with nitrification of organic N within the aquifer and consumption of dissolved oxygen. This study demonstrates that subaqueous nitrification of organic N in the aquifer, as opposed to in soils, might be a

  12. Significance of geochemical characterization to performance at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Simmons, A.M.

    1993-01-01

    The U.S. concept for permanent disposal of high-level radioactive waste resembles those of other countries in that it relies upon burial in a deep geologic medium. This concept relies upon multiple barriers to retard transport of radionuclides to the accessible environment; those barriers consist of the waste form, waste container, engineered barrier system (including possible backfill) and retardant properties of the host rock. Because mobilization of radionuclides is fundamentally a geochemical problem, an understanding of past, present, and future geochemical processes is a requisite part of site characterization studies conducted by the U.S. Department of Energy at Yucca Mountain, Nevada. Geochemical information is needed for evaluating three favorable conditions (the rates of geochemical processes, conditions that promote precipitation or sorption of radionuclides or prohibit formation of colloids, and stable mineral assemblages) and four potentially adverse conditions of the site (groundwater conditions that could increase the chemical reactivity of the engineered barried system or reduce sorption, potential for gaseous radionuclide movement, and oxidizing groundwaters) for key issues of radionuclide release, groundwater quality, and stability of the geochemical environment. Preliminary results of long-term heating experiments indicate that although zeolites can be modified by long-term, low temperature reactions, their beneficial sorptive properties will not be adversely affected. Mineral reactions will be controlled by the aqueous activity of silica in groundwater with which the minerals are in contact. Geochemical barriers alone may satisfy release requirements to the accessible environment for many radionuclides; however, additional site specific geochemical and mineralogical data are needed to test existing and future radionuclide transport models

  13. New methodology for aquifer influx status classification for single wells in a gas reservoir with aquifer support

    Directory of Open Access Journals (Sweden)

    Yong Li

    2016-10-01

    Full Text Available For gas reservoirs with strong bottom or edge aquifer support, the most important thing is avoiding aquifer breakthrough in a gas well. Water production in gas wells does not only result in processing problems in surface facilities, but it also explicitly reduces well productivity and reservoir recovery. There are a lot of studies on the prediction of water breakthrough time, but they are not completely practicable due to reservoir heterogeneity. This paper provides a new method together with three diagnostic curves to identify aquifer influx status for single gas wells; the aforementioned curves are based on well production and pressure data. The whole production period of a gas well can be classified into three periods based on the diagnostic curves: no aquifer influx period, early aquifer influx period, and middle-late aquifer influx period. This new method has been used for actual gas well analysis to accurately identify gas well aquifer influx status and the water breakthrough sequence of all wells in the same gas field. Additionally, the evaluation results are significantly beneficial for well production rate optimization and development of an effective gas field.

  14. Field demonstration of CO2 leakage detection in potable aquifers with a pulselike CO2-release test.

    Science.gov (United States)

    Yang, Changbing; Hovorka, Susan D; Delgado-Alonso, Jesus; Mickler, Patrick J; Treviño, Ramón H; Phillips, Straun

    2014-12-02

    This study presents two field pulselike CO2-release tests to demonstrate CO2 leakage detection in a shallow aquifer by monitoring groundwater pH, alkalinity, and dissolved inorganic carbon (DIC) using the periodic groundwater sampling method and a fiber-optic CO2 sensor for real-time in situ monitoring of dissolved CO2 in groundwater. Measurements of groundwater pH, alkalinity, DIC, and dissolved CO2 clearly deviated from their background values, showing responses to CO2 leakage. Dissolved CO2 observed in the tests was highly sensitive in comparison to groundwater pH, DIC, and alkalinity. Comparison of the pulselike CO2-release tests to other field tests suggests that pulselike CO2-release tests can provide reliable assessment of geochemical parameters indicative of CO2 leakage. Measurements by the fiber-optic CO2 sensor, showing obvious leakage signals, demonstrated the potential of real-time in situ monitoring of dissolved CO2 for leakage detection at a geologic carbon sequestration (GCS) site. Results of a two-dimensional reactive transport model reproduced the geochemical measurements and confirmed that the decrease in groundwater pH and the increases in DIC and dissolved CO2 observed in the pulselike CO2-release tests were caused by dissolution of CO2 whereas alkalinity was likely affected by carbonate dissolution.

  15. CO2/Brine transport into shallow aquifers along fault zones.

    Science.gov (United States)

    Keating, Elizabeth H; Newell, Dennis L; Viswanathan, Hari; Carey, J W; Zyvoloski, G; Pawar, Rajesh

    2013-01-02

    Unintended release of CO(2) from carbon sequestration reservoirs poses a well-recognized risk to groundwater quality. Research has largely focused on in situ CO(2)-induced pH depression and subsequent trace metal mobilization. In this paper we focus on a second mechanism: upward intrusion of displaced brine or brackish-water into a shallow aquifer as a result of CO(2) injection. Studies of two natural analog sites provide insights into physical and chemical mechanisms controlling both brackish water and CO(2) intrusion into shallow aquifers along fault zones. At the Chimayó, New Mexico site, shallow groundwater near the fault is enriched in CO(2) and, in some places, salinity is significantly elevated. In contrast, at the Springerville, Arizona site CO(2) is leaking upward through brine aquifers but does not appear to be increasing salinity in the shallow aquifer. Using multiphase transport simulations we show conditions under which significant CO(2) can be transported through deep brine aquifers into shallow layers. Only a subset of these conditions favor entrainment of salinity into the shallow aquifer: high aspect-ratio leakage pathways and viscous coupling between the fluid phases. Recognition of the conditions under which salinity is favored to be cotransported with CO(2) into shallow aquifers will be important in environmental risk assessments.

  16. Groundwater residence time and movement in the Maltese islands - A geochemical approach

    Energy Technology Data Exchange (ETDEWEB)

    Stuart, M.E., E-mail: mest@bgs.ac.uk [British Geological Survey, Wallingford, Oxfordshire OX10 8BB (United Kingdom); Maurice, L. [British Geological Survey, Wallingford, Oxfordshire OX10 8BB (United Kingdom); Heaton, T.H.E. [British Geological Survey, NERC Isotope Geoscience Laboratory, Keyworth, Nottinghamshire NG12 5GG (United Kingdom); Sapiano, M.; Micallef Sultana, M. [Malta Resources Authority, Marsa MRS 9065 (Malta); Gooddy, D.C.; Chilton, P.J. [British Geological Survey, Wallingford, Oxfordshire OX10 8BB (United Kingdom)

    2010-05-15

    The Maltese islands are composed of two limestone aquifers, the Upper and Lower Coralline Limestone separated by an aquitard, the 'Blue Clay'. The Lower Coralline Limestone is overlain in part by the poorly permeable Globigerina Limestone. The upper perched aquifers are discontinuous and have very limited saturated thickness and a short water level response time to rainfall. Frequent detections of coliforms suggest a rapid route to groundwater. However, the unsaturated zone has a considerable thickness in places and the primary porosity of the Upper Coralline Limestone is high, so there is likely to be older recharge by slow matrix flow as well as rapid recharge from fractures. Measurement of SF{sub 6} from a pumping station in a deep part of one of the perched aquifers indicated a mean saturated zone age of about 15 a. The Main Sea Level aquifers (MSL) on both Malta and Gozo have a large unsaturated thickness as water levels are close to sea level. On Malta, parts of the aquifer are capped by the perched aquifers and more extensively by the Globigerina Limestone. The limited detection of coliform bacteria suggests only some rapid recharge from the surface via fractures or karst features. Transmissivity is low and {sup 3}H and CFC/SF{sub 6} data indicate that saturated zone travel times are in the range 15-40 a. On Gozo the aquifer is similar but is more-extensively capped by impermeable Blue Clay. CFC data show the saturated zone travel time is from 25 a to possibly more than 60 a. Groundwater age is clearly related to the extent of low-permeability cover. The {delta}{sup 13}C signature of groundwater is related to the geochemical processes which occur along the flowpath and is consistent with residence time ages in the sequence; perched aquifers < Malta MSL < Gozo MSL. The {sup 18}O and {sup 2}H enriched isotopic signature of post 1983 desalinated water can be seen in more-modern groundwater, particularly the urbanized areas of the perched and Malta MSL

  17. Geochemical controls on groundwater chemistry in shales

    International Nuclear Information System (INIS)

    Von Damm, K.L.

    1989-01-01

    The chemistry of groundwaters is one of the most important parameters in determining the mobility of species within a rock formation. A three pronged approach was used to determine the composition of, and geochemical controls, on groundwaters specifically within shale formations: (1) available data were collected from the literature, the US Geological Survey WATSTORE data base, and field sampling, (2) the geochemical modeling code EQ3/6 was used to simulate interaction of various shales and groundwaters, and (3) several types of shale were reacted with synthetic groundwaters in the laboratory. The comparison of model results to field and laboratory data provide a means of validating the models, as well as a means of deconvoluting complex field interactions. Results suggest that groundwaters in shales have a wide range in composition and are primarily of the Na-Cl-HCO 3 - type. The constancy of the Na:Cl (molar) ratio at 1:1 and the Ca:Mg ratio from 3:1 to 1:1 suggests the importance of halite and carbonates in controlling groundwater compositions. In agreement with the reaction path modeling, most of the groundwaters are neutral to slightly alkaline at low temperatures. Model and experimental results suggest that reaction (1) at elevated temperatures, or (2) in the presence of oxygen will lead to more acidic conditions. Some acetate was found to be produced in the experiments; depending on the constraints applied, large amounts of acetate were produced in the model results. 13 refs., 1 tab

  18. Origin of water salinity in the coastal Sarafand aquifer (South-Lebanon)

    International Nuclear Information System (INIS)

    Hashash, Adnan; Aranyossy, J.F.

    1996-01-01

    Author.The geochemical and isotopic study, based on the analysis of twenty water samples from well in the coastal plain of Sarafand (South-Lebanon), permit to eliminate the hypothesis of marine intrusion in this aquifer. The increase of salinity observed in certain wells is due to the contamination of cretaceous aquifer water by the quaternary formations. The two poles of mixing are respectively characterized: by weak tritium contents (between 2 and 3 UT) and a value of stable isotopes (-5,9<0,18<-5,5) corresponding to the appearance of cretaceous formation area; by the high tritium contents and enrichment relative to heavy isotope in the mineralized water of superficial formations. On the other hand, the isotope contents permit the set a rapid renewal of the cretaceous aquifer water due to quick circulation in the Karstic system

  19. Hydrogeochemistry and statistical analysis applied to understand fluoride provenance in the Guarani Aquifer System, Southern Brazil.

    Science.gov (United States)

    Marimon, Maria Paula C; Roisenberg, Ari; Suhogusoff, Alexandra V; Viero, Antonio Pedro

    2013-06-01

    High fluoride concentrations (up to 11 mg/L) have been reported in the groundwater of the Guarani Aquifer System (Santa Maria Formation) in the central region of the state of Rio Grande do Sul, Southern Brazil. In this area, dental fluorosis is an endemic disease. This paper presents the geochemical data and the combination of statistical analysis (Principal components and cluster analyses) and geochemical modeling to achieve the hydrogeochemistry of the groundwater and discusses the possible fluoride origin. The groundwater from the Santa Maria Formation is comprised of four different geochemical groups. The first group corresponds to a sodium chloride groundwater which evolves to sodium bicarbonate, the second one, both containing fluoride anomalies. The third group is represented by calcium bicarbonate groundwater, and in the fourth, magnesium is the distinctive parameter. The statistical and geochemical analyses supported by isotopic measurements indicated that groundwater may have originated from mixtures of deeper aquifers and the fluoride concentrations could be derived from rock/water interactions (e.g., desorption from clay minerals).

  20. Saltwater intrusion in the surficial aquifer system of the Big Cypress Basin, southwest Florida, and a proposed plan for improved salinity monitoring

    Science.gov (United States)

    Prinos, Scott T.

    2013-01-01

    The installation of drainage canals, poorly cased wells, and water-supply withdrawals have led to saltwater intrusion in the primary water-use aquifers in southwest Florida. Increasing population and water use have exacerbated this problem. Installation of water-control structures, well-plugging projects, and regulation of water use have slowed saltwater intrusion, but the chloride concentration of samples from some of the monitoring wells in this area indicates that saltwater intrusion continues to occur. In addition, rising sea level could increase the rate and extent of saltwater intrusion. The existing saltwater intrusion monitoring network was examined and found to lack the necessary organization, spatial distribution, and design to properly evaluate saltwater intrusion. The most recent hydrogeologic framework of southwest Florida indicates that some wells may be open to multiple aquifers or have an incorrect aquifer designation. Some of the sampling methods being used could result in poor-quality data. Some older wells are badly corroded, obstructed, or damaged and may not yield useable samples. Saltwater in some of the canals is in close proximity to coastal well fields. In some instances, saltwater occasionally occurs upstream from coastal salinity control structures. These factors lead to an incomplete understanding of the extent and threat of saltwater intrusion in southwest Florida. A proposed plan to improve the saltwater intrusion monitoring network in the South Florida Water Management District’s Big Cypress Basin describes improvements in (1) network management, (2) quality assurance, (3) documentation, (4) training, and (5) data accessibility. The plan describes improvements to hydrostratigraphic and geospatial network coverage that can be accomplished using additional monitoring, surface geophysical surveys, and borehole geophysical logging. Sampling methods and improvements to monitoring well design are described in detail. Geochemical analyses

  1. Calcite raft geochemistry as a hydrological proxy for Holocene aquifer conditions in Hoyo Negro and Ich Balam (Sac Actun Cave System), Quintana Roo, Mexico

    Science.gov (United States)

    Kovacs, Shawn E.; Reinhardt, Eduard G.; Chatters, James C.; Rissolo, Dominique; Schwarcz, Henry P.; Collins, Shawn V.; Kim, Sang-Tae; Nava Blank, Alberto; Luna Erreguerena, Pilar

    2017-11-01

    Two cores from calcite rafts deposits located in Cenote Ich Balam and Hoyo Negro were dated and analyzed for 87Sr/86Sr, δ18O, δ13C, Sr/Ca and Cl/Ca. The geochemical records show changing aquifer salinity spanning the last ∼ 8.5 cal kyrs BP and interrelationships with Holocene climate trends (wet and dry periods). During the wet mid-Holocene, the salinity of the meteoric Water Mass (WM; at 7.8-8.3 cal kyrs BP) was relatively high at 1.5-2.7 ppt and then became less saline (1.0-1.5 ppt) during the last ∼ 7000 yrs as climate became progressively drier. High salinity of the meteoric WM during the wet mid-Holocene is attributed to increased turbulent mixing between the meteoric and underlying marine WM. Increased precipitation, in terms of amount, frequency, and intensity (e.g. hurricanes) causes higher flow of meteoric water towards the coast and mixing at the halocline, a phenomenon recorded with recent instrumental monitoring of the aquifer. Conversely, during dry periods reduced precipitation and flow in the meteoric WM would result in lower salinity. Karst properties and Holocene sea-level rise also seem to have an effect on the aquifer. When the regionally extensive network of shallow cave passages (∼ 10-12 m water depth) are flooded at ∼ 8000 cal yrs BP, there is a rapid shift in salinity. This study demonstrates that calcite raft deposits can be used as paleo-environmental recorders documenting the effects of sea level and climate change on aquifer condition.

  2. Groundwater level responses to precipitation variability in Mediterranean insular aquifers

    Science.gov (United States)

    Lorenzo-Lacruz, Jorge; Garcia, Celso; Morán-Tejeda, Enrique

    2017-09-01

    Groundwater is one of the largest and most important sources of fresh water on many regions under Mediterranean climate conditions, which are exposed to large precipitation variability that includes frequent meteorological drought episodes, and present high evapotranspiration rates and water demand during the dry season. The dependence on groundwater increases in those areas with predominant permeable lithologies, contributing to aquifer recharge and the abundance of ephemeral streams. The increasing pressure of tourism on water resources in many Mediterranean coastal areas, and uncertainty related to future precipitation and water availability, make it urgent to understand the spatio-temporal response of groundwater bodies to precipitation variability, if sustainable use of the resource is to be achieved. We present an assessment of the response of aquifers to precipitation variability based on correlations between the Standardized Precipitation Index (SPI) at various time scales and the Standardized Groundwater Index (SGI) across a Mediterranean island. We detected three main responses of aquifers to accumulated precipitation anomalies: (i) at short time scales of the SPI (24 months). The differing responses were mainly explained by differences in lithology and the percentage of highly permeable rock strata in the aquifer recharge areas. We also identified differences in the months and seasons when aquifer storages are more dependent on precipitation; these were related to climate seasonality and the degree of aquifer exploitation or underground water extraction. The recharge of some aquifers, especially in mountainous areas, is related to precipitation variability within a limited spatial extent, whereas for aquifers located in the plains, precipitation variability influence much larger areas; the topography and geological structure of the island explain these differences. Results indicate large spatial variability in the response of aquifers to precipitation in

  3. Recharge sources and residence times of groundwater as determined by geochemical tracers in the Mayfield Area, southwestern Idaho, 2011–12

    Science.gov (United States)

    Hopkins, Candice B.

    2013-01-01

    Parties proposing residential development in the area of Mayfield, Idaho are seeking a sustainable groundwater supply. During 2011–12, the U.S. Geological Survey, in cooperation with the Idaho Department of Water Resources, used geochemical tracers in the Mayfield area to evaluate sources of aquifer recharge and differences in groundwater residence time. Fourteen groundwater wells and one surface-water site were sampled for major ion chemistry, metals, stable isotopes, and age tracers; data collected from this study were used to evaluate the sources of groundwater recharge and groundwater residence times in the area. Major ion chemistry varied along a flow path between deeper wells, suggesting an upgradient source of dilute water, and a downgradient source of more concentrated water with the geochemical signature of the Idaho Batholith. Samples from shallow wells had elevated nutrient concentrations, a more positive oxygen-18 signature, and younger carbon-14 dates than deep wells, suggesting that recharge comes from young precipitation and surface-water infiltration. Samples from deep wells generally had higher concentrations of metals typical of geothermal waters, a more negative oxygen-18 signature, and older carbon-14 values than samples from shallow wells, suggesting that recharge comes from both infiltration of meteoric water and another source. The chemistry of groundwater sampled from deep wells is somewhat similar to the chemistry in geothermal waters, suggesting that geothermal water may be a source of recharge to this aquifer. Results of NETPATH mixing models suggest that geothermal water composes 1–23 percent of water in deep wells. Chlorofluorocarbons were detected in every sample, which indicates that all groundwater samples contain at least a component of young recharge, and that groundwater is derived from multiple recharge sources. Conclusions from this study can be used to further refine conceptual hydrological models of the area.

  4. Geochemical characteristics of peat from two raised bogs of Germany

    Science.gov (United States)

    Mezhibor, A. M.

    2016-11-01

    Peat has a wide range of applications in different spheres of human activity, and this is a reason for a comprehensive study. This research represents the results of an ICP-MS study of moss and peat samples from two raised bogs of Germany. Because of the wide use of sphagnum moss and peat, determining their geochemical characteristics is an important issue. According to the results obtained, we can resume that the moss samples from Germany are rich in Cu, As, Y, Zr, Nb, and REE. The geochemical composition of the bogs reflects the regional environmental features and anthropogenic influence.

  5. Geochemical Investigations of Groundwater Stability

    International Nuclear Information System (INIS)

    Bath, Adrian

    2006-05-01

    The report describes geochemical parameters and methods that provide information about the hydrodynamic stability of groundwaters in low permeability fractured rocks that are potential hosts for radioactive waste repositories. Hydrodynamic stability describes the propensity for changes in groundwater flows over long timescales, in terms of flow rates and flow directions. Hydrodynamic changes may also cause changes in water compositions, but the related issue of geochemical stability of a potential repository host rock system is outside the scope of this report. The main approaches to assessing groundwater stability are numerical modelling, measurement and interpretation of geochemical indicators in groundwater compositions, and analyses and interpretations of secondary minerals and fluid inclusions in these minerals. This report covers the latter two topics, with emphasis on geochemical indicators. The extent to which palaeohydrogeology and geochemical stability indicators have been used in past safety cases is reviewed. It has been very variable, both in terms of the scenarios considered, the stability indicators considered and the extent to which the information was explicitly or implicitly used in assessing FEPs and scenarios in the safety cases. Geochemical indicators of hydrodynamic stability provide various categories of information that are of hydrogeological relevance. Information about groundwater mixing, flows and water sources is potentially provided by the total salinity of groundwaters, their contents of specific non-reactive solutes (principally chloride) and possibly of other solutes, the stable isotopic ratio of water, and certain characteristics of secondary minerals and fluid inclusions. Information pertaining directly to groundwater ages and the timing of water and solute movements is provided by isotopic systems including tritium, carbon-14, chlorine-36, stable oxygen and hydrogen isotopes, uranium isotopes and dissolved mobile gases in

  6. Geochemical Investigations of Groundwater Stability

    Energy Technology Data Exchange (ETDEWEB)

    Bath, Adrian [Intellisci Ltd., Loughborough (United Kingdom)

    2006-05-15

    The report describes geochemical parameters and methods that provide information about the hydrodynamic stability of groundwaters in low permeability fractured rocks that are potential hosts for radioactive waste repositories. Hydrodynamic stability describes the propensity for changes in groundwater flows over long timescales, in terms of flow rates and flow directions. Hydrodynamic changes may also cause changes in water compositions, but the related issue of geochemical stability of a potential repository host rock system is outside the scope of this report. The main approaches to assessing groundwater stability are numerical modelling, measurement and interpretation of geochemical indicators in groundwater compositions, and analyses and interpretations of secondary minerals and fluid inclusions in these minerals. This report covers the latter two topics, with emphasis on geochemical indicators. The extent to which palaeohydrogeology and geochemical stability indicators have been used in past safety cases is reviewed. It has been very variable, both in terms of the scenarios considered, the stability indicators considered and the extent to which the information was explicitly or implicitly used in assessing FEPs and scenarios in the safety cases. Geochemical indicators of hydrodynamic stability provide various categories of information that are of hydrogeological relevance. Information about groundwater mixing, flows and water sources is potentially provided by the total salinity of groundwaters, their contents of specific non-reactive solutes (principally chloride) and possibly of other solutes, the stable isotopic ratio of water, and certain characteristics of secondary minerals and fluid inclusions. Information pertaining directly to groundwater ages and the timing of water and solute movements is provided by isotopic systems including tritium, carbon-14, chlorine-36, stable oxygen and hydrogen isotopes, uranium isotopes and dissolved mobile gases in

  7. Geochemical Exploration Techniques Applicable in the Search for Copper Deposits

    Science.gov (United States)

    Chaffee, Maurice A.

    1975-01-01

    media. Samples of ice and snow have been used for limited geochemical surveys. Both geobotanical and biogeochemical surveys have been successful in locating copper deposits in many parts of the world. Micro-organisms, including bacteria and algae, are other unproved media that should be studied. Animals can be used in geochemical-prospecting programs. Dogs have been used quite successfully to sniff out hidden and exposed sulfide minerals. Tennite mounds are commonly composed of subsurface material, but have not as yet proved to be useful in locating buried mineral deposits. Animal tissue and waste products are essentially unproved but potentially valuable sampling media. Knowledge of the location of areas where trace-element-associated diseases in animals and man are endemic as well as a better understanding of these diseases, may aid in identifying regions that are enriched in or depleted of various elements, including copper. Results of analyses of gases in the atmosphere are proving valuable in mineral-exploration surveys. Studies involving metallic compounds exhaled by plants into the atmosphere, and of particulate matter suspended in the atmosphere are reviewed these methods may become important in the future. Remote-sensing techniques are useful for making indirect measurements of geochemical responses. Two techniques applicable to geochemical exploration are neutron-activation analysis and gamma-ray spectrometry. Aerial photography is especially useful in vegetation surveys. Radar imagery is an unproved but potentially valuable method for use in studies of vegetation in perpetually clouded regions. With the advent of modern computers, many new techniques, such as correlation analysis, regression analysis, discriminant analysis, factor analysis, cluster analysis, trend-surface analysis, and moving-average analysis can be applied to geochemical data sets. Selective use of these techniques can provide new insights into the interpretatio

  8. Recharge and Aquifer Response: Manukan Island’s Aquifer, Sabah, Malaysia

    Directory of Open Access Journals (Sweden)

    Sarva Mangala Praveena

    2010-01-01

    Full Text Available Manukan Island is a small island located in North-West of Sabah, Malaysia was used as a case study area for numerical modeling of an aquifer response to recharge and pumping rates. The results in this study present the variations of recharge into the aquifer under the prediction simulations. The recharge rate increases the water level as indicated by hydraulic heads. This shows that it can alter groundwater of Manukan Island which has been suffering from an overexploration in its unconfined the aquifer. The increase in recharge rate (from 600 mm/year to 750 mm/year increases the water level indicated by hydraulic heads. A reduction in pumping rate (from 0.072 m3/day to 0.058 m3/day not only increases the amount of water levels in aquifer but also reduces the supply hence a deficit in supply. The increase in hydraulic heads depends on the percentage reduction of pumping and recharges rates. The well water has 1978.3 mg/L chloride with current pumping (0.072 m3/day and recharge rates (600 mm/year. However, with an increased of recharge rate and current pumping rate it has decreased about 1.13%. In addition, reduction in pumping rate made the chloride concentration decreased about 2.8%. In general, a reduction in pumping with an increase in recharge rate leads to a decreased in chloride concentrations within the vicinity of cone of depression. Next, to further develop the numerical model, the model should focus on climate change variables such as consequences of climate change are increase in air temperature, increase in sea surface temperature, and more extreme weather conditions. These parameters are considered critical parameters for climate change impact modeling in aquifers. The behavior of the aquifer and its sustainable pumping rate can be done by applying a computer modeling component.

  9. Alternative geochemical barrier materials

    International Nuclear Information System (INIS)

    1991-07-01

    Previous investigations of the effects of neutralization and reduction on uranium mill tailings pore fluids by the Technical Support Contractor indicated that arsenic, selenium, and molybdenum continue to remain in solution in all but reducing conditions. These hazardous constituents are present in groundwaters as oxyanions and, therefore, are not expected to be removed by adsorption into clays and most other soil constituents. It was decided to investigate the attenuation capacity of two commonly available crystalline iron oxides, taconite and scoria, and a zeolite, a network aluminosilicate with a cage structure. Columns of the candidate materials were exposed to solutions of individual constituents, including arsenic, molybdenum, selenium, and, uranium, and to the spiked tailings pore fluid from the Bodo Canyon disposal cell near Durango, Colorado. In addition to the single material columns, a homogeneous blend of the three materials and layers of the materials were exposed to spiked tailings pore fluids. The results of these experiments indicate that with the exception of molybdenum, the constituents of concern are attenuated by the taconite; however, they are not sufficiently attenuated to meet the groundwater protection standards applicable to the UMTRA Project. Therefore, the candidate barrier materials did not prove to be useful to the UMTRA Project for the cleanup of groundwaters

  10. Distribution of sulphur isotopes of sulphates in groundwaters from the principal artesian aquifer of Florida and the Edwards aquifer of Texas, United States of America

    International Nuclear Information System (INIS)

    Rightmire, C.T.; Pearson, F.J. Jr.; Back, W.; Rye, R.O.; Hanshaw, B.B.

    1974-01-01

    New information on the sources of sulphate dissolved in groundwater is obtainable from the measurement of the sulphur isotope composition of sulphates. Field studies in the Floridan aquifer, Florida, and the Edwards aquifer, Texas, show that the use of sulphur isotope data in conjunction with hydrologic and geochemical techniques permits refinements of interpretation. In the Floridan the interpretation of the chemical data, particularly the SO 4 2- concentration and the SO 4 2- /Cl - ratio, leads to the conclusion that recharging maritime rainfall, solution of intraformational gypsum, and mixing with ocean-like saline waters are the sources of sulphate in the groundwater. Sulphur isotope data substantiate this interpretation. The Edwards in the area studied can be separated into two hydrologie units on the basis of water chemistry and aquifer characteristics. The sulphide-free waters in the part of the aquifer upgradient from a distinct sulphide boundary are low in sulphate (less than 100 mg/1) and contain no sulphide. The waters downgradient from that boundary contain greater than 150 mg/1 sulphate and all contain measurable quantities of sulphide. Interpretation of the SO 4 2- concentration and SO 4 2- /Cl ratio on the basis of the Florida study leads to the erroneous conclusion that the solution of intraformational gypsum is again a major source of sulphate in the sulphide-free part of the aquifer. Isotope analyses, however, show that the gypsum is likely to be Permian in age and introduced into the aquifer by the recharge water. The absence of evidence for enrichment in 34 S in the sulphate in the sulphide-bearing portion of the aquifer leads to the possibility of H 2 S migration upgradient from downdip oil fields. (author)

  11. Ground-water flow directions and estimation of aquifer hydraulic properties in the lower Great Miami River Buried Valley aquifer system, Hamilton Area, Ohio

    Science.gov (United States)

    Sheets, Rodney A.; Bossenbroek, Karen E.

    2005-01-01

    The Great Miami River Buried Valley Aquifer System is one of the most productive sources of potable water in the Midwest, yielding as much as 3,000 gallons per minute to wells. Many water-supply wells tapping this aquifer system are purposely placed near rivers to take advantage of induced infiltration from the rivers. The City of Hamilton's North Well Field consists of 10 wells near the Great Miami River, all completed in the lower Great Miami River Buried Valley Aquifer System. A well-drilling program and a multiple-well aquifer test were done to investigate ground-water flow directions and to estimate aquifer hydraulic properties in the lower part of the Great Miami River Buried Valley Aquifer System. Descriptions of lithology from 10 well borings indicate varying amounts and thickness of clay or till, and therefore, varying levels of potential aquifer confinement. Borings also indicate that the aquifer properties can change dramatically over relatively short distances. Grain-size analyses indicate an average bulk hydraulic conductivity value of aquifer materials of 240 feet per day; the geometric mean of hydraulic conductivity values of aquifer material was 89 feet per day. Median grain sizes of aquifer material and clay units were 1.3 millimeters and 0.1 millimeters, respectively. Water levels in the Hamilton North Well Field are affected by stream stage in the Great Miami River and barometric pressure. Bank storage in response to stream stage is evident. Results from a multiple-well aquifer test at the well field indicate, as do the lithologic descriptions, that the aquifer is semiconfined in some areas and unconfined in others. Transmissivity and storage coefficient of the semiconfined part of the aquifer were 50,000 feet squared per day and 5x10-4, respectively. The average hydraulic conductivity (450 feet per day) based on the aquifer test is reasonable for glacial outwash but is higher than calculated from grain-size analyses, implying a scale effect

  12. Combination of a crop model and a geochemical model as a new approach to evaluate the sustainability of an intensive agriculture system.

    Science.gov (United States)

    Mohammed, Gihan; Trolard, Fabienne; Gillon, Marina; Cognard-Plancq, Anne-Laure; Chanzy, André; Bourrié, Guilhem

    2017-10-01

    By combining a crop model (STICS) and a geochemical model (PHREEQC), a new approach to assess the sustainability of agrosystems is proposed. It is based upon aqueous geochemistry and the stepwise modifications of soil solution during its transfer from the surface till aquifer. Meadows of Crau (SE France), irrigated since the 16th century, were field monitored (2012-2015) and modelled. Except for N, the mineral requirements of hay are largely covered by dissolved elements brought by irrigation water with only slight deficits in K and P, which are compensated by P-K fertilizers and the winter pasture by sheep. N cycle results in a very small nitrate leakage. The main determinants of the chemical composition changes of water are: concentration by evaporation, equilibration with soil pCO 2 , mineral nutrition of plants, input of fertilizers, sheep grazing, mineral-solution interactions in superficial formations till the aquifer, including ion exchange. Inverse modelling with PHREEQC allows for quantifying these processes. For groundwater, measured composition fit statistically very well with those computed, validating thus this approach. This long-term established agrosystem protects both soil and water resources: soil nutritional status remains constant with even some P and (minor) K fixation in soils; long-term decarbonatation occurs but it is greatly slowed by saturation of irrigation water by carbonate; P fixation in soil protects groundwater from eutrophication. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Geochemical features and effects on deep-seated fluids during the May-June 2012 southern Po Valley seismic sequence

    Directory of Open Access Journals (Sweden)

    Francesco Italiano

    2012-10-01

    Full Text Available A periodic sampling of the groundwaters and dissolved and free gases in selected deep wells located in the area affected by the May-June 2012 southern Po Valley seismic sequence has provided insight into seismogenic-induced changes of the local aquifer systems. The results obtained show progressive changes in the fluid geochemistry, allowing it to be established that deep-seated fluids were mobilized during the seismic sequence and reached surface layers along faults and fractures, which generated significant geochemical anomalies. The May-June 2012 seismic swarm (mainshock on May 29, 2012, M 5.8; 7 shocks M >5, about 200 events 3 > M > 5 induced several modifications in the circulating fluids. This study reports the preliminary results obtained for the geochemical features of the waters and gases collected over the epicentral area from boreholes drilled at different depths, thus intercepting water and gases with different origins and circulation. The aim of the investigations was to improve our knowledge of the fluids circulating over the seismic area (e.g. origin, provenance, interactions, mixing of different components, temporal changes. This was achieved by collecting samples from both shallow and deep-drilled boreholes, and then, after the selection of the relevant sites, we looked for temporal changes with mid-to-long-term monitoring activity following a constant sampling rate. This allowed us to gain better insight into the relationships between the fluid circulation and the faulting activity. The sampling sites are listed in Table 1, along with the analytical results of the gas phase. […

  14. Groundwater evolution in the Continental Intercalaire aquifer of southern Algeria and Tunisia: trace element and isotopic indicators

    International Nuclear Information System (INIS)

    Edmunds, W.M.; Guendouz, A.H.; Mamou, A.; Moulla, A.; Shand, P.; Zouari, K.

    2003-01-01

    The geochemical processes taking place along an 800 km flow line in the non-carbonate Continental Intercalaire aquifer (CI) aquifer in North Africa are described using chemical (major and trace element) and isotopic indicators. The aquifer is hydraulically continuous from the Atlas Mountains in Algeria to the Chotts of Tunisia and the geochemical evidence corroborates this. The highest discharge temperature is 73 deg. C but silica geothermometry indicates a maximum temperature of 94 deg. C at depth. Chloride concentrations increase from 200 to 800 mg l -1 and the Br/Cl ratios confirm the dissolution of non-marine evaporites or interstitial waters as the main source of salinity. Fluoride concentrations are low and are likely to be derived from rainfall, recording oscillations in source. Radiocarbon ages, except near outcrop, are at or near detection limits and the δ 18 O and δ 2 H values indicate a cooler recharge regime with rainfall having lower primary evaporation than today. This is shown by the fact that mean isotope ratios of CI waters are around 3 per mille lighter than the present-day weighted mean value for rain. Major ion ratios and most trace elements indicate that despite the complex structure and stratigraphy, uniform evolution with continuous water-rock interaction takes place along the flow lines, which are only disturbed near the Tunisian Chotts by groundwater converging from additional flow lines. The ageing of the water can also be followed by the smooth increase in several indicator elements such as Li, K and Mn which are least affected by solubility controls. Similarly the influence of marine facies in the Tunisian sector may be recognised by the changing Mg/Ca and higher Br/Cl as well as trace element indicators. The groundwaters are oxidising up to 300 km from outcrop (dissolved O 2 has persisted for at least 20 ka) and within this zone the concentrations of several elements forming oxy-anions, such as U and Cr, increase and NO 3 remains

  15. Radial flow towards well in leaky unconfined aquifer

    Science.gov (United States)

    Mishra, P. K.; Kuhlman, K. L.

    2012-12-01

    An analytical solution is developed for three-dimensional flow towards a partially penetrating large- diameter well in an unconfined aquifer bounded below by a leaky aquitard of finite or semi-infinite extent. The analytical solution is derived using Laplace and Hankel transforms, then inverted numerically. Existing solutions for flow in leaky unconfined aquifers neglect the unsaturated zone following an assumption of instantaneous drainage due to Neuman. We extend the theory of leakage in unconfined aquifers by (1) including water flow and storage in the unsaturated zone above the water table, and (2) allowing the finite-diameter pumping well to partially penetrate the aquifer. The investigation of model-predicted results shows that aquitard leakage leads to significant departure from the unconfined solution without leakage. The investigation of dimensionless time-drawdown relationships shows that the aquitard drawdown also depends on unsaturated zone properties and the pumping-well wellbore storage effects.

  16. Quantification of the impacts of coalmine water irrigation on the underlying aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Vermeulen, D.; Usher, B.; van Tonder, G. [University of Free State, Bloemfontein (South Africa). Institute of Groundwater Studies

    2009-07-15

    It is predicted that vast volumes of affected mine water will be produced by mining activities in the Mpumalanga coalfields of South Africa, The potential environmental impact of this excess water is of great concern in a water-scarce country like South Africa. Research over a period of more than 10 years has shown that this water can be used successfully for the irrigation of a range of crops. There is, however, continuing concern from the local regulators regarding the long-term impact that large-scale mine water irrigation may have on groundwater quality and quantity. Detailed research has been undertaken over the last three years to supplement the groundwater monitoring programme at five different pilot sites, on both virgin soils (greenfields) and in coalmining spoils. These sites range from sandy soils to very clayey soils. The research has included soil moisture measurements, collection of in situ soil moisture over time, long-term laboratory studies of the leaching and attenuation properties of different soils and the impact of irrigation on acid rock drainage processes, and in depth determination of the hydraulic properties of the subsurface at each of these sites, including falling head tests, pumping tests and point dilution tests. This has been supported by geochemical modelling of these processes to quantify the impacts. The results indicate that many of the soils have considerable attenuation capacities and that in the period of irrigation, a large proportion of the salts have been contained in the upper portions of the unsaturated zones below each irrigation pivot. The volumes and quality of water leaching through to the aquifers have been quantified at each site. From this mixing ratios have been calculated in order to determine the effect of the irrigation water on the underlying aquifers.

  17. Fluorescence in situ hybridization (CARD-FISH) of microorganisms in hydrocarbon contaminated aquifer sediment samples.

    Science.gov (United States)

    Tischer, Karolin; Zeder, Michael; Klug, Rebecca; Pernthaler, Jakob; Schattenhofer, Martha; Harms, Hauke; Wendeberg, Annelie

    2012-12-01

    Groundwater ecosystems are the most important sources of drinking water worldwide but they are threatened by contamination and overexploitation. Petroleum spills account for the most common source of contamination and the high carbon load results in anoxia and steep geochemical gradients. Microbes play a major role in the transformation of petroleum hydrocarbons into less toxic substances. To investigate microbial populations at the single cell level, fluorescence in situ hybridization (FISH) is now a well-established technique. Recently, however, catalyzed reporter deposition (CARD)-FISH has been introduced for the detection of microbes from oligotrophic environments. Nevertheless, petroleum contaminated aquifers present a worst case scenario for FISH techniques due to the combination of high background fluorescence of hydrocarbons and the presence of small microbial cells caused by the low turnover rates characteristic of groundwater ecosystems. It is therefore not surprising that studies of microorganisms from such sites are mostly based on cultivation techniques, fingerprinting, and amplicon sequencing. However, to reveal the population dynamics and interspecies relationships of the key participants of contaminant degradation, FISH is an indispensable tool. In this study, a protocol for FISH was developed in combination with cell quantification using an automated counting microscope. The protocol includes the separation and purification of microbial cells from sediment particles, cell permeabilization and, finally, CARD-FISH in a microwave oven. As a proof of principle, the distribution of Archaea and Bacteria was shown in 60 sediment samples taken across the contaminant plume of an aquifer (Leuna, Germany), which has been heavily contaminated with several ten-thousand tonnes of petroleum hydrocarbons since World War II. Copyright © 2012 Elsevier GmbH. All rights reserved.

  18. A Combined Radio- and Stable-Isotopic Study of a California Coastal Aquifer System

    Directory of Open Access Journals (Sweden)

    Michael Land

    2013-04-01

    Full Text Available Stable and radioactive tracers were utilized in concert to characterize geochemical processes in a complex coastal groundwater system and to provide constraints on the kinetics of rock/water interactions. Groundwater samples from wells within the Dominguez Gap region of Los Angeles County, California were analyzed for a suite of major cations (Na+, K+, Mg2+, Ca2+ and anions (Cl−, SO42−, silica, alkalinity, select trace elements (Ba, B, Sr, dissolved oxygen, stable isotopes of hydrogen (δD, oxygen (δ18O, dissolved inorganic carbon (δ13CDIC, and radioactive isotopes (3H, 222Rn and 223,224,226,228Ra. In the study area, groundwater may consist of a complex mixture of native groundwater, intruded seawater, non-native injected water, and oil-field brine water. In some wells, Cl− concentrations attained seawater-like values and in conjunction with isotopically heavier δ18O values, these tracers provide information on the extent of seawater intrusion and/or mixing with oil-field brines. Groundwater 3H above 1 tritium unit (TU was observed only in a few select wells close to the Dominguez Gap area and most other well groundwater was aged pre-1952. Based on an initial 14C value for the study site of 90 percent modern carbon (pmc, groundwater age estimates likely extend beyond 20 kyr before present and confirm deep circulation of some native groundwater through multiple aquifers. Enriched values of groundwater δ13CDIC in the absence of SO42− imply enhanced anaerobic microbial methanogenesis. While secular equilibrium was observed for 234U/238U (activity ratios ~1 in host matrices, strong isotopic fractionation in these groundwater samples can be used to obtain information of adsorption/desorption kinetics. Calculated Ra residence times are short, and the associated desorption rate constant is about three orders of magnitude slower than that of the adsorption rate constant. Combined stable- and radio-isotopic results provide unique insights

  19. Solid phases limiting the concentration of dissolved constituents in basalt aquifers of the Columbia Plateau in eastern Washington

    International Nuclear Information System (INIS)

    Deutsch, W.J.; Jenne, E.A.; Krupka, K.M.

    1981-01-01

    The purposes of this study were: (1) to provide information on the solid phases which are in apparent equilibrium with ground waters of basalt aquifers, and (2) to further develop the capability of geochemical modeling to support solute transport studies and performance assessments of nuclear waste repositories. The basalt aquifers of the Columbia Plateau in eastern Washington were chosen as the study area because: (1) regional ground-water analyses are readily available, (2) these basalts are a potential medium for a nuclear-waste repository, and (3) mineralogical analyses from local site studies are available

  20. Insight into Groundwater Flow within a Crystalline Aquifer. Case Study of the Ursuya Mount, Northern Basque Country (France)

    International Nuclear Information System (INIS)

    Jaunat, J.; Huneau, F.; Dupuy, A.; Franceschi, M.; Coustumer, P. Le; Celle-Jeanton, H.

    2011-01-01

    The Ursuya Mount is one of the main water supplies of the Northern Basque Country. A study is being conducted since 2009 on this aquifer in order to improve the knowledge on its potential and its hydrodynamics properties. Two hydrological cycles are required to get the necessary data to meet the following objectives: clarifying the aquifer potential of the site both quantitatively and qualitatively; determining the geographic and seasonal variations; understanding the origin and the flow pattern of the groundwater; evaluating the groundwater residence times and the areas of preferential recharge. Here, we present only some geochemical and isotopic data. Thus, structural or hydrodynamic approaches will not be discussed.

  1. aquifer in ajaokuta, southwestern nigeria

    African Journals Online (AJOL)

    2005-03-08

    Mar 8, 2005 ... (1969) straight line method (observation well) of draw-down analysis in an unconfined aquifer (B=1) yield ... April) and a short wet season (May-September). .... DECOMPOSED. GRANITIC ROCK WITH. QUARTZ VEINS. 13.

  2. Determination of 222Rn and its physico-chemical and biological characteristics in aquifers of Toluca valley

    International Nuclear Information System (INIS)

    Hernandez, A.; Aranda, P.; Ceballos, S.; Cruz, D.; Jauregui, B.; Lopez, R.; Pena, P.; Salazar, S.; Segovia, N.; Tamez, E.

    1997-01-01

    In this work it is realized a geochemical study which includes the evaluation of 222 Rn concentration in drinking water wells at Toluca city and a spring water of Almoloya de Juarez municipality at State of mexico. the same is studied about evolution of 222 Rn concentration in water of the hydrating which supply it to those wells. the geochemical evaluation also covers the determination of major and minor elements or trace and the biological analysis of water. The study includes two seasonal cycles, the low water mark one and other the rainy for being able to evaluate the aquifers reloading effects in the water composition. (Author)

  3. Semi-analytical solutions for flow to a well in an unconfined-fractured aquifer system

    Science.gov (United States)

    Sedghi, Mohammad M.; Samani, Nozar

    2015-09-01

    Semi-analytical solutions of flow to a well in an unconfined single porosity aquifer underlain by a fractured double porosity aquifer, both of infinite radial extent, are obtained. The upper aquifer is pumped at a constant rate from a pumping well of infinitesimal radius. The solutions are obtained via Laplace and Hankel transforms and are then numerically inverted to time domain solutions using the de Hoog et al. algorithm and Gaussian quadrature. The results are presented in the form of dimensionless type curves. The solution takes into account the effects of pumping well partial penetration, water table with instantaneous drainage, leakage with storage in the lower aquifer into the upper aquifer, and storativity and hydraulic conductivity of both fractures and matrix blocks. Both spheres and slab-shaped matrix blocks are considered. The effects of the underlying fractured aquifer hydraulic parameters on the dimensionless drawdown produced by the pumping well in the overlying unconfined aquifer are examined. The presented solution can be used to estimate hydraulic parameters of the unconfined and the underlying fractured aquifer by type curve matching techniques or with automated optimization algorithms. Errors arising from ignoring the underlying fractured aquifer in the drawdown distribution in the unconfined aquifer are also investigated.

  4. Origins and delineation of saltwater intrusion in the Biscayne aquifer and changes in the distribution of saltwater in Miami-Dade County, Florida

    Science.gov (United States)

    Prinos, Scott T.; Wacker, Michael A.; Cunningham, Kevin J.; Fitterman, David V.

    2014-01-01

    Intrusion of saltwater into parts of the shallow karst Biscayne aquifer is a major concern for the 2.5 million residents of Miami-Dade County that rely on this aquifer as their primary drinking water supply. Saltwater intrusion of this aquifer began when the Everglades were drained to provide dry land for urban development and agriculture. The reduction in water levels caused by this drainage, combined with periodic droughts, allowed saltwater to flow inland along the base of the aquifer and to seep directly into the aquifer from the canals. The approximate inland extent of saltwater was last mapped in 1995. An examination of the inland extent of saltwater and the sources of saltwater in the aquifer was completed during 2008–2011 by using (1) all available salinity information, (2) time-series electromagnetic induction log datasets from 35 wells, (3) time-domain electromagnetic soundings collected at 79 locations, (4) a helicopter electromagnetic survey done during 2001 that was processed, calibrated, and published during the study, (5) cores and geophysical logs collected from 8 sites for stratigraphic analysis, (6) 8 new water-quality monitoring wells, and (7) analyses of 69 geochemical samples. The results of the study indicate that as of 2011 approximately 1,200 square kilometers (km2) of the mainland part of the Biscayne aquifer were intruded by saltwater. The saltwater front was mapped farther inland than it was in 1995 in eight areas totaling about 24.1 km2. In many of these areas, analyses indicated that saltwater had encroached along the base of the aquifer. The saltwater front was mapped closer to the coast than it was in 1995 in four areas totaling approximately 6.2 km2. The changes in the mapped extent of saltwater resulted from improved spatial information, actual movement of the saltwater front, or a combination of both. Salinity monitoring in some of the canals in Miami-Dade County between 1988 and 2010 indicated influxes of saltwater, with maximum

  5. Geochemical indicators of intrinsic bioremediation

    International Nuclear Information System (INIS)

    Borden, R.C.; Gomez, C.A.; Becker, M.T.

    1995-01-01

    A detailed field investigation has been completed at a gasoline-contaminated aquifer near Rocky Point, NC, to examine possible indicators of intrinsic bioremediation and identify factors that may significantly influence the rae and extent of bioremediation. The dissolved plume of benzene, toluene, ethylbenzene, and xylene (BTEX) in ground water is naturally degrading. Toluene and o-xylene are most rapidly degraded followed by m-, p-xylene, and benzene. Ethylbenzene appears to degrade very slowly under anaerobic conditions present in the center of the plume. The rate and extent of biodegradation appears to be strongly influenced by the type and quantity of electron acceptors present in the aquifer. At the upgradient edge of the plume, nitrate, ferric iron, and oxygen are used as terminal electron acceptors during hydrocarbon biodegradation. The equivalent of 40 to 50 mg/l of hydrocarbon is degraded based on the increase in dissolved CO 2 relative to background ground water. Immediately downgradient of the source area, sulfate and iron are the dominant electron acceptors. Toluene and o-xylene are rapidly removed in this region. Once the available oxygen, nitrate, and sulfate are consumed, biodegradation is limited and appears to be controlled by mixing and aerobic biodegradation at the plume fringes

  6. Hydrogeology and Aquifer Storage and Recovery Performance in the Upper Floridan Aquifer, Southern Florida

    Science.gov (United States)

    Reese, Ronald S.; Alvarez-Zarikian, Carlos A.

    2007-01-01

    between flow zones is better in southwestern Florida than in southeastern Florida. Vertical hydraulic conductivity in the upper part of the aquifer also may be higher in southeastern Florida because of unconformities present at formation contacts within the aquifer that may be better developed in this area. Recovery efficiencies per cycle varied widely. Eight sites had recovery efficiencies of less than about 10 percent for the first cycle, and three of these sites had not yet achieved recoveries exceeding 10 percent, even after three to five cycles. The highest recovery efficiency achieved per cycle was 94 percent. Three southeastern coastal sites and two southwestern coastal sites have achieved potable water recoveries per cycle exceeding 60 percent. One of the southeastern coastal sites and both of the southwestern coastal sites achieved good recoveries, even with long storage periods (from 174 to 191 days). The high recovery efficiencies for some cycles apparently resulted from water banking?an operational approach whereby an initial cycle with a large recharge volume of water is followed by cycles with much smaller recharge volume. This practice flushes out the aquifer around the well and builds up a buffer zone that can maintain high recovery efficiency in the subsequent cycles. The relative performance of all sites with adequate cycle test data was determined. Performance was arbitrarily grouped into ?high? (greater than 40 percent), ?medium? (between 20 and 40 percent), and ?low? (less than 20 percent) categories based primarily on their cumulative recovery efficiency for the first seven cycles, or projected to seven cycles if fewer cycles were conducted. The ratings of three sites, considered to be borderline, were modified using the overall recharge rate derived from the cumulative recharge volumes. A higher overall recharge rate (greater than 300 million gallons per year) can improve recovery efficiency because of the water-bankin

  7. Status report on geochemical modelling

    International Nuclear Information System (INIS)

    Read, D.

    1991-12-01

    This report describes the findings of a review undertaken on behalf of the project management group of the programme 'Endlagersicherheit in der Nachbetriebsphase' based at GSF-IfT (Forschungszentrum fuer Umwelt und Gesundheit - Institut fuer Tieflagerung) to establish the current status of research into the simulation of geochemical processes relevant to radiological assessment. The review is intended to contribute to Stage 1 of a strategy formulated to enhance the use of geochemical models in Germany. Emphasis has been placed on processes deemed to be of greatest relevance to performance assessment for a HLW-repository in a salt dome principally, speciation-solubility in high salinity solutions, complexation by natural organics and generation-transport of colloids. For each of these and other topics covered, a summary is given of fundamental concepts, theoretical representations and their limitations, highlighting, where appropriate, the advantages and disadvantages of alternative approaches. The availability of data to quantify any given representation is addressed, taking into account the need for information at elevated temperatures and pressures. Mass transfer is considered in terms of aqueous, particulate and gas-mediated transport, respectively. (orig.) [de

  8. Study of Aquifer Thermal Energy Storage

    Science.gov (United States)

    Okuyama, Masaaki; Umemiya, Hiromichi; Shibuya, Ikuko; Haga, Eiji

    Yamagata University 'Aquifer Thermal Energy Storage (ATES)' is the experimental system which has been running since 1982. From the results for along terms of experiments, we obtain many important knowledge. This paper presents the accomplishments for 16 years and the characteristics of thermal energy storage in thermal energy storage well. The conclusions show as follows. 1)In recent years, the thermal recovery factor of warm energy storage well becomes almost constant at about 60%. 2) The thermal recovery factor of cool energy storage well increases gradually and becomes at about 15%. 3) Since the ferric colloidal dam is formed in aquifer, thermal recovery factor increase year after year. 4) Back wash can remove clogging for ferric colloidal dam. 5) The apparent thermal diffusivity decrease gradually due to ferric colloidal dam.

  9. Perched aquifers - their potential impact on contaminant transport in the southern High Plains, Texas

    International Nuclear Information System (INIS)

    Mullican, W.F. III; Fryar, A.E.; Johns, N.D.

    1993-01-01

    Understanding the hydrogeology and hydrochemistry of perched aquifers at potential and known contaminated waste sites has become increasingly important because of the impact these aquifers may have on contaminant transport independent of regional aquifer processes. Investigations of a perched aquifer above the Ogallala aquifer are being conducted in the region of the U.S. Department of Energy's Pantex Plant, a proposed Superfund site, located approximately 20 mi northeast of Amarillo, Texas. Since the early 1950s, a small playa basin located on the Pantex Plant has been used as a waste-water discharge pond with daily discharge rates ranging from 400,000 to 1 million gal. The focus of this investigation is an unconfined, perched aquifer that overlies a thick silty clay sequence within the upper, mostly unsaturated part of the Ogallala Formation (Neogene). In the area of the Pantex Plant, measured depths to the perched aquifer range from 200 to 300 ft below land surface, whereas depth to the regional Ogallala aquifer ranges from 375 to 500 ft. The potentiometric surface of the perched aquifer typically represents groundwater mounds proximal to the playas and thins into trough in the interplaya areas. Hydrologic gradients of the primary mound under investigation are relatively high, ranging from 28 to 45 ft/mi. Calculated transmissivities have a geometric mean of 54 ft 2 /day, with saturated thicknesses ranging from 4 to 1000 ft. Modeling of the perched aquifer was designed to determine how much, if any, discharge to the small playa basin has enhanced recharge to the perched aquifers and increased the vertical and lateral extent of the perched aquifer. Preliminary results indicate that measurements of vertical conductance through the perching silty-clay sequence and recharge rates through playas are critical for calibrating the model. Accurate delineation of rates and flow directions in the perched aquifer is critical to any successful remediation effort

  10. TAPIR--Finnish national geochemical baseline database.

    Science.gov (United States)

    Jarva, Jaana; Tarvainen, Timo; Reinikainen, Jussi; Eklund, Mikael

    2010-09-15

    In Finland, a Government Decree on the Assessment of Soil Contamination and Remediation Needs has generated a need for reliable and readily accessible data on geochemical baseline concentrations in Finnish soils. According to the Decree, baseline concentrations, referring both to the natural geological background concentrations and the diffuse anthropogenic input of substances, shall be taken into account in the soil contamination assessment process. This baseline information is provided in a national geochemical baseline database, TAPIR, that is publicly available via the Internet. Geochemical provinces with elevated baseline concentrations were delineated to provide regional geochemical baseline values. The nationwide geochemical datasets were used to divide Finland into geochemical provinces. Several metals (Co, Cr, Cu, Ni, V, and Zn) showed anomalous concentrations in seven regions that were defined as metal provinces. Arsenic did not follow a similar distribution to any other elements, and four arsenic provinces were separately determined. Nationwide geochemical datasets were not available for some other important elements such as Cd and Pb. Although these elements are included in the TAPIR system, their distribution does not necessarily follow the ones pre-defined for metal and arsenic provinces. Regional geochemical baseline values, presented as upper limit of geochemical variation within the region, can be used as trigger values to assess potential soil contamination. Baseline values have also been used to determine upper and lower guideline values that must be taken into account as a tool in basic risk assessment. If regional geochemical baseline values are available, the national guideline values prescribed in the Decree based on ecological risks can be modified accordingly. The national geochemical baseline database provides scientifically sound, easily accessible and generally accepted information on the baseline values, and it can be used in various

  11. 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)

    Duvert, Clément; Raiber, Matthias; Owen, Daniel D.R.; Cendón, Dioni I.; Batiot-Guilhe, Christelle; Cox, Malcolm E.

    2015-01-01

    margins. Most waters collected from the coal-bearing aquifer also showed an enhanced influence of weathering during the wet season, which was likely triggered by the water–rock interaction with fresh recharge waters. An increase in both residual alkalinity and carbon isotopic ratios at two locations indicated inter-aquifer mixing between alluvium and bedrock during the wet season. The results of this study emphasise the need for conducting baseline hydrochemical surveys prior to CSG development in order to describe the transient nature of recharge and inter-aquifer mixing processes

  12. Preliminary petrological and geochemical results from the Salton Sea Geothermal Field, California: A near-field natural analog of a radioactive waste repository in salt: Topical report No. 2

    International Nuclear Information System (INIS)

    Elders, W.A.; Cohen, L.H.; Williams, A.E.; Neville, S.; Collier, P.; Oakes, C.

    1986-03-01

    High concentrations of radionuclides and high temperatures are not naturally encountered in salt beds. For this reason, the Salton Sea Geothermal Field (SSGF) may be the best available geologic analog of some of the processes expected to occur in high level nuclear waste repositories in salt. Subsurface temperatures and brine concentrations in the SSGF span most of the temperature range and fluid inclusion brine range expected in a salt repository, and the clay-rich sedimentary rocks are similar to those which host bedded or domal salts. As many of the chemical processes observed in the SSGF are similar to those expected to occur in or near a salt repository, data derived from it can be used in the validation of geochemical models of the near-field of a repository in salt. This report describes preliminary data on petrology and geochemistry, emphasizing the distribution of rare earth elements and U and Th, of cores and cuttings from several deep wells chosen to span a range of temperature gradients and salinities. Subsurface temperature logs have been augmented by fluid inclusion studies, to reveal the effects of brines of varying temperature and salinity. The presence of brines with different oxygen isotopic signatures also indicate lack of mixing. Whole rock major, minor and trace element analyses and data on brine compositions are being used to study chemical migration in these sediments. 65 refs., 20 figs., 3 tabs

  13. Effect of source integration on the geochemical fluxes from springs

    International Nuclear Information System (INIS)

    Frisbee, Marty D.; Phillips, Fred M.; White, Art F.; Campbell, Andrew R.; Liu, Fengjing

    2013-01-01

    Geochemical fluxes from watersheds are typically defined using mass-balance methods that essentially lump all weathering processes operative in a watershed into a single flux of solute mass measured in streamflow at the watershed outlet. However, it is important that we understand how weathering processes in different hydrological zones of a watershed (i.e., surface, unsaturated, and saturated zones) contribute to the total geochemical flux from the watershed. This capability will improve understanding of how geochemical fluxes from these different zones may change in response to climate change. Here, the geochemical flux from weathering processes occurring solely in the saturated zone is investigated. This task, however, remains exceedingly difficult due to the sparsity of subsurface sampling points, especially in large, remote, and/or undeveloped watersheds. In such cases, springflow is often assumed to be a proxy for groundwater (defined as water residing in fully saturated geologic formations). However, springflow generation may integrate different sources of water including, but not limited to, groundwater. The authors’ hypothesis is that long-term estimates of geochemical fluxes from groundwater using springflow proxies will be too large due to the integrative nature of springflow generation. Two conceptual models of springflow generation are tested using endmember mixing analyses (EMMA) on observations of spring chemistries and stable isotopic compositions in a large alpine watershed in the San Juan Mountains of southwestern Colorado. In the “total springflow” conceptual model, springflow is assumed to be 100% groundwater. In the “fractional springflow” conceptual model, springflow is assumed to be an integration of different sources of water (e.g., groundwater, unsaturated flow, preferential flow in the soil, etc.) and groundwater is only a fractional component. The results indicate that groundwater contributions in springflow range from 2% to 100

  14. Hydrogeochemical characterization and groundwater quality assessment in intruded coastal brine aquifers (Laizhou Bay, China).

    Science.gov (United States)

    Zhang, Xiaoying; Miao, Jinjie; Hu, Bill X; Liu, Hongwei; Zhang, Hanxiong; Ma, Zhen

    2017-09-01

    The aquifer in the coastal area of the Laizhou Bay is affected by salinization processes related to intense groundwater exploitation for brine resource and for agriculture irrigation during the last three decades. As a result, the dynamic balances among freshwater, brine, and seawater have been disturbed and the quality of groundwater has deteriorated. To fully understand the groundwater chemical distribution and evolution in the regional aquifers, hydrogeochemical and isotopic studies have been conducted based on the water samples from 102 observation wells. Groundwater levels and salinities in four monitoring wells are as well measured to inspect the general groundwater flow and chemical patterns and seasonal variations. Chemical components such as Na + , K + , Ca 2+ , Mg 2+ , Sr 2+ , Cl - , SO 4 2- , HCO 3 - , NO 3 - , F - , and TDS during the same period are analyzed to explore geochemical evolution, water-rock interactions, sources of salt, nitrate, and fluoride pollution in fresh, brackish, saline, and brine waters. The decreased water levels without typical seasonal variation in the southeast of the study area confirm an over-exploitation of groundwater. The hydrogeochemical characteristics indicate fresh-saline-brine-saline transition pattern from inland to coast where evaporation is a vital factor to control the chemical evolution. The cation exchange processes are occurred at fresh-saline interfaces of mixtures along the hydraulic gradient. Meanwhile, isotopic data indicate that the brine in aquifers was either originated from older meteoric water with mineral dissolution and evaporation or repeatedly evaporation of retained seawater with fresher water recharge and mixing in geological time. Groundwater suitability for drinking is further evaluated according to water quality standard of China. Results reveal high risks of nitrate and fluoride contamination. The elevated nitrate concentration of 560 mg/L, which as high as 28 times of the standard content

  15. Transient well flow in leaky multiple-aquifer systems

    Science.gov (United States)

    Hemker, C. J.

    1985-10-01

    A previously developed eigenvalue analysis approach to groundwater flow in leaky multiple aquifers is used to derive exact solutions for transient well flow problems in leaky and confined systems comprising any number of aquifers. Equations are presented for the drawdown distribution in systems of infinite extent, caused by wells penetrating one or more of the aquifers completely and discharging each layer at a constant rate. Since the solution obtained may be regarded as a combined analytical-numerical technique, a type of one-dimensional modelling can be applied to find approximate solutions for several complicating conditions. Numerical evaluations are presented as time-drawdown curves and include effects of storage in the aquitard, unconfined conditions, partially penetrating wells and stratified aquifers. The outcome of calculations for relatively simple systems compares very well with published corresponding results. The proposed multilayer solution can be a valuable tool in aquifer test evaluation, as it provides the analytical expression required to enable the application of existing computer methods to the determination of aquifer characteristics.

  16. EPA Region 1 Sole Source Aquifers

    Science.gov (United States)

    This coverage contains boundaries of EPA-approved sole source aquifers. Sole source aquifers are defined as an aquifer designated as the sole or principal source of drinking water for a given aquifer service area; that is, an aquifer which is needed to supply 50% or more of the drinking water for the area and for which there are no reasonable alternative sources should the aquifer become contaminated.The aquifers were defined by a EPA hydrogeologist. Aquifer boundaries were then drafted by EPA onto 1:24000 USGS quadrangles. For the coastal sole source aquifers the shoreline as it appeared on the quadrangle was used as a boundary. Delineated boundaries were then digitized into ARC/INFO.

  17. Geochemical Fractionations and Mobility of Arsenic, Lead and Cadmium in Sediments of the Kanto Plain, Japan.

    Science.gov (United States)

    Hossain, Sushmita; Oguchi, Chiaki T.; Hachinohe, Shoichi; Ishiyama, Takashi; Hamamoto, Hideki

    2014-05-01

    Lowland alluvial and floodplain sediment play a major role in transferring heavy metals and other elements to groundwater through sediment water interaction in changing environmental conditions. However identification of geochemical forms of toxic elements such as arsenic (As), lead (Pb) and cadmium (Cd) requires risk assessment of sediment and subsequent groundwater pollution. A four steps sequential extraction procedure was applied to characterize the geochemical fractionations of As, Pb and Cd for 44 sediment samples including one peat sample from middle basin area of the Nakagawa river in the central Kanto plain. The studied sediment profile extended from the bottom of the river to 44 m depth; sediment samples were collected at 1m intervals from a bored core. The existing sedimentary facies in vertical profile are continental, transitional and marine. There are two aquifers in vertical profile; the upper aquifer (15-20m) contains fine to medium sand whereas medium to coarse sand and gravelly sand contain in lower aquifer (37-44m). The total As and Pb contents were measured by the X-Ray Fluorescence analysis which ranged from 4 to 23 mg/kg of As and 10 to 27 mg/kg of Pb in sediment profile. The three trace elements and major heavy metals were determined by ICP/MS and ICP/AES, and major ions were measured by an ion chromatograph. The marine sediment is mainly Ca-SO4 type. The Geochemical analysis showed the order of mobility trends to be As > Pb > Cd for all the steps. The geochemical fractionations order was determined to be Fe-Mn oxide bound > carbonate bound > ion exchangeable > water soluble for As and Pb whereas the order for Cd is carbonate bound > Fe-Mn oxide bound > ion exchangeable > water soluble. The mobility tendency of Pb and Cd showed high in fine silty sediment of marine environment than for those from continental and transitional environments. In the case of As, the potential mobility is very high (>60%) in the riverbed sediments and clayey silt

  18. Interpolation of extensive routine water pollution monitoring datasets: methodology and discussion of implications for aquifer management

    OpenAIRE

    Yuval; Y. Rimon; E. R. Graber; A. Furman

    2013-01-01

    A large fraction of the fresh water available for human use is stored in groundwater aquifers. Since human activities such as mining, agriculture, industry and urbanization often result in incursion of various pollutants to groundwater, routine monitoring of water quality is an indispensable component of judicious aquifer management. Unfortunately, groundwater pollution monitoring is expensive and usually cannot cover an aquifer with the spatial resolution necessary for making adequate...

  19. Hydrochemical Processes in the Alluvial Aquifer of the Gwydir River (Northern New South Wales, Australia)

    OpenAIRE

    Menció, Anna; Mas-Pla, Josep; Korbel, Kathryn; Hose, Grant C.

    2013-01-01

    The hydrochemistry of the Narrabri Formation, the shallow aquifer system of the alluvial fan of the Gwydir River (NSW, Australia), is analyzed to better understand the hydrogeological processes involved in aquifer recharge, and to set up future management options that preserve the quantity and quality of water resources. Results show that groundwater hydrochemistry in this alluvial aquifer is mainly controlled by silicate weathering and cation exchange. However, salt remobilization in specifi...

  20. Coupled geochemical and solute transport code development

    International Nuclear Information System (INIS)

    Morrey, J.R.; Hostetler, C.J.

    1985-01-01

    A number of coupled geochemical hydrologic codes have been reported in the literature. Some of these codes have directly coupled the source-sink term to the solute transport equation. The current consensus seems to be that directly coupling hydrologic transport and chemical models through a series of interdependent differential equations is not feasible for multicomponent problems with complex geochemical processes (e.g., precipitation/dissolution reactions). A two-step process appears to be the required method of coupling codes for problems where a large suite of chemical reactions must be monitored. Two-step structure requires that the source-sink term in the transport equation is supplied by a geochemical code rather than by an analytical expression. We have developed a one-dimensional two-step coupled model designed to calculate relatively complex geochemical equilibria (CTM1D). Our geochemical module implements a Newton-Raphson algorithm to solve heterogeneous geochemical equilibria, involving up to 40 chemical components and 400 aqueous species. The geochemical module was designed to be efficient and compact. A revised version of the MINTEQ Code is used as a parent geochemical code

  1. Proceedings of the workshop on geochemical modeling

    International Nuclear Information System (INIS)

    1986-01-01

    The following collection of papers was presented at a workshop on geochemical modeling that was sponsored by the Office of Civilian Radioactive Waste Management Program at the Lawrence Livermore National Laboratory (LLNL). The LLNL Waste Management Program sponsored this conference based on their belief that geochemical modeling is particularly important to the radioactive waste disposal project because of the need to predict the consequences of long-term water-rock interactions at the proposed repository site. The papers included in this volume represent a subset of the papers presented at the Fallen Leaf Lake Conference and cover a broad spectrum of detail and breadth in a subject that reflects the diverse research interests of the conference participants. These papers provide an insightful look into the current status of geochemical modeling and illustrate how various geochemical modeling codes have been applied to problems of geochemical interest. The emphasis of these papers includes traditional geochemical modeling studies of individual geochemical systems, the mathematical and theoretical development and refinement of new modeling capabilities, and enhancements of data bases on which the computations are based. The papers in this proceedings volume have been organized into the following four areas: Geochemical Model Development, Hydrothermal and Geothermal Systems, Sedimentary and Low Temperature Environments, and Data Base Development. The participants of this symposium and a complete list of the talks presented are listed in the appendices

  2. Proceedings of the workshop on geochemical modeling

    Energy Technology Data Exchange (ETDEWEB)

    1986-01-01

    The following collection of papers was presented at a workshop on geochemical modeling that was sponsored by the Office of Civilian Radioactive Waste Management Program at the Lawrence Livermore National Laboratory (LLNL). The LLNL Waste Management Program sponsored this conference based on their belief that geochemical modeling is particularly important to the radioactive waste disposal project because of the need to predict the consequences of long-term water-rock interactions at the proposed repository site. The papers included in this volume represent a subset of the papers presented at the Fallen Leaf Lake Conference and cover a broad spectrum of detail and breadth in a subject that reflects the diverse research interests of the conference participants. These papers provide an insightful look into the current status of geochemical modeling and illustrate how various geochemical modeling codes have been applied to problems of geochemical interest. The emphasis of these papers includes traditional geochemical modeling studies of individual geochemical systems, the mathematical and theoretical development and refinement of new modeling capabilities, and enhancements of data bases on which the computations are based. The papers in this proceedings volume have been organized into the following four areas: Geochemical Model Development, Hydrothermal and Geothermal Systems, Sedimentary and Low Temperature Environments, and Data Base Development. The participants of this symposium and a complete list of the talks presented are listed in the appendices.

  3. Bioremediation of a diesel fuel contaminated aquifer: simulation studies in laboratory aquifer columns

    Science.gov (United States)

    Hess, A.; Höhener, P.; Hunkeler, D.; Zeyer, J.

    1996-08-01

    The in situ bioremediation of aquifers contaminated with petroleum hydrocarbons is commonly based on the infiltration of groundwater supplemented with oxidants (e.g., O 2, NO 3-) and nutrients (e.g., NH 4+, PO 43-). These additions stimulate the microbial activity in the aquifer and several field studies describing the resulting processes have been published. However, due to the heterogeneity of the subsurface and due to the limited number of observation wells usually available, these field data do not offer a sufficient spatial and temporal resolution. In this study, flow-through columns of 47-cm length equipped with 17 sampling ports were filled with homogeneously contaminated aquifer material from a diesel fuel contaminated in situ bioremediation site. The columns were operated over 96 days at 12°C with artificial groundwater supplemented with O 2, NO 3- and PO 43-. Concentration profiles of O 2, NO 3-, NO 2-, dissolved inorganic and organic carbon (DIC and DOC, respectively), protein, microbial cells and total residual hydrocarbons were measured. Within the first 12 cm, corresponding to a mean groundwater residence time of < 3.6 h, a steep O 2 decrease from 4.6 to < 0.3 mg l -1, denitrification, a production of DIC and DOC, high microbial cell numbers and a high removal of hydrocarbons were observed. Within a distance of 24 to 40.5 cm from the infiltration, O 2 was below 0.1 mg l -1 and a denitrifying activity was found. In the presence and in the absence of O 2, n-alkanes were preferentially degraded compared to branched alkanes. The results demonstrate that: (1) infiltration of aerobic groundwater into columns filled with aquifer material contaminated with hydrocarbons leads to a rapid depletion of O 2; (2) O 2 and NO 3- can serve as oxidants for the mineralization of hydrocarbons; and (3) the modelling of redox processes in aquifers has to consider denitrifying activity in presence of O 2.

  4. Hydrochemistry of the Mahomet Bedrock Valley Aquifer, East-Central Illinois: indicators of recharge and ground-water flow

    Science.gov (United States)

    Panno, S.V.; Hackley, Keith C.; Cartwright, K.; Liu, Chao-Li

    1994-01-01

    A conceptual model of the ground-water flow and recharge to the Mahomet Bedrock Valley Aquifer (MVA), east-central Illinois, was developed using major ion chemistry and isotope geochemistry. The MVA is a 'basal' fill in the east-west trending buried bedrock valley composed of clean, permeable sand and gravel to thicknesses of up to 61 m. It is covered by a thick sequence of glacial till containing thinner bodies of interbedded sand and gravel. Ground water from the MVA was found to be characterized by clearly defined geochemical regions with three distinct ground-water types. A fourth ground-water type was found at the confluence of the MVA and the Mackinaw Bedrock Valley Aquifer (MAK) to the west. Ground water in the Onarga Valley, a northeastern tributary of the MVA, is of two types, a mixed cation-SO42- type and a mixed cation-HCO3- type. The ground water is enriched in Na+, Ca2+, Mg2+, and SO42- which appears to be the result of an upward hydraulic gradient and interaction of deeper ground water with oxidized pyritic coals and shale. We suggest that recharge to the Onarga Valley and overlying aquifers is 100% from bedrock (leakage) and lateral flow from the MVA to the south. The central MVA (south of the Onarga Valley) is composed of relatively dilute ground water of a mixed cation-HCO3- type, with low total dissolved solids, and very low concentrations of Cl- and SO42-. Stratigraphic relationships of overlying aquifers and ground-water chemistry of these and the MVA suggest recharge to this region of the MVA (predominantly in Champaign County) is relatively rapid and primarily from the surface. Midway along the westerly flow path of the MVA (western MVA), ground water is a mixed cation-HCO3- type with relatively high Cl-, where Cl- increases abruptly by one to ??? two orders of magnitude. Data suggest that the increase in Cl- is the result of leakage of saline ground water from bedrock into the MVA. Mass-balance calculations indicate that approximately 9.5% of

  5. Estimating Groundwater Mounding in Sloping Aquifers for Managed Aquifer Recharge.

    Science.gov (United States)

    Zlotnik, Vitaly A; Kacimov, Anvar; Al-Maktoumi, Ali

    2017-11-01

    Design of managed aquifer recharge (MAR) for augmentation of groundwater resources often lacks detailed data, and simple diagnostic tools for evaluation of the water table in a broad range of parameters are needed. In many large-scale MAR projects, the effect of a regional aquifer base dip cannot be ignored due to the scale of recharge sources (e.g., wadis, streams, reservoirs). However, Hantush's (1967) solution for a horizontal aquifer base is commonly used. To address sloping aquifers, a new closed-form analytical solution for water table mound accounts for the geometry and orientation of recharge sources at the land surface with respect to the aquifer base dip. The solution, based on the Dupiuit-Forchheimer approximation, Green's function method, and coordinate transformations is convenient for computing. This solution reveals important MAR traits in variance with Hantush's solution: mounding is limited in time and space; elevation of the mound is strongly affected by the dip angle; and the peak of the mound moves over time. These findings have important practical implications for assessment of various MAR scenarios, including waterlogging potential and determining proper rates of recharge. Computations are illustrated for several characteristic MAR settings. © 2017, National Ground Water Association.

  6. Geochemical prospecting for uranium and thorium deposits

    International Nuclear Information System (INIS)

    Boyle, R.W.

    1980-01-01

    A brief review of analytical geochemical prospecting methods for uranium and thorium is given excluding radiometric techniques, except those utilized in the determination of radon. The indicator (pathfinder) elements useful in geochemical surveys are listed for each of the types of known uranium and thorium deposits; this is followed by sections on analytical geochemical surveys based on rocks (lithochemical surveys), unconsolidated materials (pedochemical surveys), natural waters and sediments (hydrochemical surveys), biological materials (biogeochemical surveys) and gases (atmochemical surveys). All of the analytical geochemical methods are applicable in prospecting for thorium and uranium, particularly where radiometric methods fail due to attenuation by overburden, water, deep leaching and so on. Efficiency in the discovery of uranium and/or thorium orebodies is promoted by an integrated methods approach employing geological pattern recognition in the localization of deposits, analytical geochemical surveys, and radiometric surveys. (author)

  7. Similar sediment provenance of low and high arsenic aquifers in Bangladesh

    Science.gov (United States)

    Zheng, Y.; Yang, Q.; Li, S.; Hemming, S. R.; Zhang, Y.; Rasbury, T.; Hemming, G.

    2017-12-01

    Geogenic arsenic (As) in drinking water, especially in groundwater, is estimated to have affected the health of over 100 million people worldwide, with nearly half of the total at risk population in Bangladesh. Sluggish flow and reducing biogeochemical environment in sedimentary aquifers have been shown as the primary controls for the release of As from sediment to the shallower groundwater in the Holocene aquifer. In contrast, deeper groundwater in the Pleistocene aquifer is depleted in groundwater As and sediment-extractable As. This study assesses the origin of the sediment in two aquifers of Bangladesh that contain distinctly different As levels to ascertain whether the source of the sediment is a factor in this difference through measurements of detrital mica Ar-Ar age, detrital zircon U-Pb age, as well as sediment silicate Sr and Nd isotopes. Whole rock geochemical data were also used to illuminate the extent of chemical weathering. Detrital mica 40Ar/39Ar cooling ages and detrital zircon U-Pb ages show no statistical difference between high-As Holocene sediment and low-As Pleistocene sediment, but suggest an aquifer sediment source of both the Brahmaputra and the Ganges rivers. Silicate 87Sr/86Sr and 143Nd/144Nd further depict a major sediment source from the Brahmaputra river, which is supported by a two end member mixing model using 87Sr/86Sr and Sr concentrations. Pleistocene and Holocene sediments show little difference in weathering of mobile elements including As, while coarser sediments and a longer history of the Pleistocene aquifer suggest that sorting and flushing play more important roles in regulating the contrast of As occurrence between these two aquifers.

  8. Source, variability, and transformation of nitrate in a regional karst aquifer: Edwards aquifer, central Texas.

    Science.gov (United States)

    Musgrove, MaryLynn; Opsahl, Stephen P.; Mahler, Barbara J.; Herrington, Chris; Sample, Thomas; Banta, John

    2016-01-01

    Many karst regions are undergoing rapid population growth and expansion of urban land accompanied by increases in wastewater generation and changing patterns of nitrate (NO3−) loading to surface and groundwater. We investigate variability and sources of NO3− in a regional karst aquifer system, the Edwards aquifer of central Texas. Samples from streams recharging the aquifer, groundwater wells, and springs were collected during 2008–12 from the Barton Springs and San Antonio segments of the Edwards aquifer and analyzed for nitrogen (N) species concentrations and NO3− stable isotopes (δ15N and δ18O). These data were augmented by historical data collected from 1937 to 2007. NO3− concentrations and discharge data indicate that short-term variability (days to months) in groundwater NO3− concentrations in the Barton Springs segment is controlled by occurrence of individual storms and multi-annual wet-dry cycles, whereas the lack of short-term variability in groundwater in the San Antonio segment indicates the dominance of transport along regional flow paths. In both segments, longer-term increases (years to decades) in NO3− concentrations cannot be attributed to hydrologic conditions; rather, isotopic ratios and land-use change indicate that septic systems and land application of treated wastewater might be the source of increased loading of NO3−. These results highlight the vulnerability of karst aquifers to NO3− contamination from urban wastewater. An analysis of N-species loading in recharge and discharge for the Barton Springs segment during 2008–10 indicates an overall mass balance in total N, but recharge contains higher concentrations of organic N and lower concentrations of NO3−than does discharge, consistent with nitrification of organic N within the aquifer and consumption of dissolved oxygen. This study demonstrates that subaqueous nitrification of organic N in the aquifer, as opposed to in soils, might be a previously

  9. Small scale changes of geochemistry and flow field due to transient heat storage in aquifers

    Science.gov (United States)

    Bauer, S.; Boockmeyer, A.; Li, D.; Beyer, C.

    2013-12-01

    Heat exchangers in the subsurface are increasingly installed for transient heat storage due to the need of heating or cooling of buildings as well as the interim storage of heat to compensate for the temporally fluctuating energy production by wind or solar energy. For heat storage to be efficient, high temperatures must be achieved in the subsurface. Significant temporal changes of the soil and groundwater temperatures however effect both the local flow field by temperature dependent fluid parameters as well as reactive mass transport through temperature dependent diffusion coefficients, geochemical reaction rates and mineral equilibria. As the use of heat storage will be concentrated in urban areas, the use of the subsurface for (drinking) water supply and heat storage will typically coincide and a reliable prognosis of the processes occurring is needed. In the present work, the effects of a temporal variation of the groundwater temperature, as induced by a local heat exchanger introduced into a groundwater aquifer, are studied. For this purpose, the coupled non-isothermal groundwater flow, heat transport and reactive mass transport is simulated in the near filed of such a heat exchanger. By explicitly discretizing and incorporating the borehole, the borehole cementation and the heat exchanger tubes, a realistic geometrical and process representation is obtained. The numerical simulation code OpenGeoSys is used in this work, which incorporates the required processes of coupled groundwater flow, heat and mass transport as well as temperature dependent geochemistry. Due to the use of a Finite Element Method, a close representation of the geometric effects can be achieved. Synthetic scenario simulations for typical settings of salt water formations in northern Germany are used to investigate the geochemical effects arising from a high temperature heat storage by quantifying changes in groundwater chemistry and overall reaction rates. This work presents the

  10. Uncertainty in geochemical modelling of CO2 and calcite dissolution in NaCl solutions due to different modelling codes and thermodynamic databases

    International Nuclear Information System (INIS)

    Haase, Christoph; Dethlefsen, Frank; Ebert, Markus; Dahmke, Andreas

    2013-01-01

    Highlights: • CO 2 and calcite dissolution is calculated. • The codes PHREEQC, Geochemist’s Workbench, EQ3/6, and FactSage are used. • Comparison with Duan and Li (2008) shows lowest deviation using phreeqc.dat and wateq4f.dat. • Using Pitzer databases does not improve accurate calculations. • Uncertainty in dissolved CO 2 is largest using the geochemical models. - Abstract: A prognosis of the geochemical effects of CO 2 storage induced by the injection of CO 2 into geologic reservoirs or by CO 2 leakage into the overlaying formations can be performed by numerical modelling (non-invasive) and field experiments. Until now the research has been focused on the geochemical processes of the CO 2 reacting with the minerals of the storage formation, which mostly consists of quartzitic sandstones. Regarding the safety assessment the reactions between the CO 2 and the overlaying formations in the case of a CO 2 leakage are of equal importance as the reactions in the storage formation. In particular, limestone formations can react very sensitively to CO 2 intrusion. The thermodynamic parameters necessary to model these reactions are not determined explicitly through experiments at the total range of temperature and pressure conditions and are thus extrapolated by the simulation code. The differences in the calculated results lead to different calcite and CO 2 solubilities and can influence the safety issues. This uncertainty study is performed by comparing the computed results, applying the geochemical modelling software codes The Geochemist’s Workbench, EQ3/6, PHREEQC and FactSage/ChemApp and their thermodynamic databases. The input parameters (1) total concentration of the solution, (2) temperature and (3) fugacity are varied within typical values for CO 2 reservoirs, overlaying formations and close-to-surface aquifers. The most sensitive input parameter in the system H 2 O–CO 2 –NaCl–CaCO 3 for the calculated range of dissolved calcite and CO 2 is the

  11. The usefulness of multi-well aquifer tests in heterogeneous aquifers

    International Nuclear Information System (INIS)

    Young, S.C.; Benton, D.J.; Herweijer, J.C.; Sims, P.

    1990-01-01

    Three large-scale (100 m) and seven small-scale (3-7 m) multi-well aquifer tests were conducted in a heterogeneous aquifer to determine the transmissivity distribution across a one-hectare test site. Two of the large-scale tests had constant but different rates of discharge; the remaining large-scale test had a discharge that was pulsed at regulated intervals. The small-scale tests were conducted at two well clusters 20 m apart. The program WELTEST was written to analyze the data. By using the methods of non-linear least squares regression analysis and Broyden's method to solve for non-linear extrema, WELTEST automatically determines the best values of transmissivity and the storage coefficient. The test results show that order of magnitude differences in the calculated transmissivities at a well location can be realized by varying the discharge rate at the pumping well, the duration of the aquifer test, and/or the location of the pumping well. The calculated storage coefficients for the tests cover a five-order magnitude range. The data show a definite trend for the storage coefficient to increase with the distance between the pumping and the observation wells. This trend is shown to be related to the orientation of high hydraulic conductivity zones between the pumping and the observation wells. A comparison among single-well aquifer tests, geological investigations and multi-well aquifer tests indicate that the multi-well tests are poorly suited for characterizing a transmissivity field. (Author) (11 refs., 14 figs.)

  12. Geochemical mole-balance modeling with uncertain data

    Science.gov (United States)

    Parkhurst, David L.

    1997-01-01

    Geochemical mole-balance models are sets of chemical reactions that quantitatively account for changes in the chemical and isotopic composition of water along a flow path. A revised mole-balance formulation that includes an uncertainty term for each chemical and isotopic datum is derived. The revised formulation is comprised of mole-balance equations for each element or element redox state, alkalinity, electrons, solvent water, and each isotope; a charge-balance equation and an equation that relates the uncertainty terms for pH, alkalinity, and total dissolved inorganic carbon for each aqueous solution; inequality constraints on the size of the uncertainty terms; and inequality constraints on the sign of the mole transfer of reactants. The equations and inequality constraints are solved by a modification of the simplex algorithm combined with an exhaustive search for unique combinations of aqueous solutions and reactants for which the equations and inequality constraints can be solved and the uncertainty terms minimized. Additional algorithms find only the simplest mole-balance models and determine the ranges of mixing fractions for each solution and mole transfers for each reactant that are consistent with specified limits on the uncertainty terms. The revised formulation produces simpler and more robust mole-balance models and allows the significance of mixing fractions and mole transfers to be evaluated. In an example from the central Oklahoma aquifer, inclusion of up to 5% uncertainty in the chemical data can reduce the number of reactants in mole-balance models from seven or more to as few as three, these being cation exchange, dolomite dissolution, and silica precipitation. In another example from the Madison aquifer, inclusion of the charge-balance constraint requires significant increases in the mole transfers of calcite, dolomite, and organic matter, which reduce the estimated maximum carbon 14 age of the sample by about 10,000 years, from 22,700 years to

  13. Geochemical behavior of uranium mill tailings leachate in the subsurface

    International Nuclear Information System (INIS)

    Brookins, D.G.

    1993-01-01

    Leachate generated from surface disposal of acidic uranium mill tailings at Maybell, CO has impacted groundwater quality within the underlying mineralized Browns Park Formation. The extent of groundwater contamination, however, is located directly beneath the tailings impoundment. The milling process consisted of sulfuric acid extraction of uranium from the feed ore by a complex chemical leaching and precipitation process. Tailings leachate at the site contains elevated concentrations of Al, As, Cd, Mo, Ni, NO 3 , Se, U, and other solutes. From column leach tests, the concentrations of contaminants within tailings pore fluid are SO 4 >NH 4 >NO 3 >U>Se>Ni>As>Cd at pH 4.0. The carbonate buffering capacity of the tailings subsoil has decreased because of calcite dissolution in the presence of acidic leachate. Groundwater quality data, mineralogical and microbiological studies, and geochemical modeling suggest that As, NO 3 , Se, U and other solutes are being removed from solution through precipitation, adsorption, and denitrification processes under reducing conditions. Presence of hydrogen sulfide, liquid and gaseous hydrocarbons, dissolved organic, and abundant pyrite within the Browns Park Formations have maintained reducing conditions subjacent to the tailings impoundment. Groundwater is in close equilibrium with coffinite and uraninite, the primary U(IV) minerals extracted from the Browns Parks Formation. Denitrifying bacteria identified in this study catalyze redox reactions involving NO 3 . Subsequently, contaminant distributions of NO 3 decrease 1000 times beneath the tailings impoundment. Applying geochemical and biochemical processes occurring at Maybell provides an excellent model for in situ aquifer restoration programs considered at other uranium tailings and heavy-metal-mixed waste contaminated sites. (author) 4 figs., 4 tabs., 27 refs

  14. Assessing water quality and pollution origin of the Bou-Areg aquifer (north east Morocco)

    OpenAIRE

    Alonso, A.; Sbaa, M.; Vanclooster, M.

    2011-01-01

    This study aims to evaluate the quality of the groundwater and the sources of pollution of the Bou-Areg aquifer, situated in the Oriental region, in the northeast part of Morocco. We first elaborated the aquifer pollution risk map by crossing a vulnerability map, principally based on the physical characteristics of the area, with a pressures map based on the soil occupation. The resulting map showed that the aquifer is subjected to a medium to high risk for at least half of the total aquifer ...

  15. Application of the top specified boundary layer (TSBL) approximation to initial characterization of an inland aquifer mineralization: 2. Seepage of saltwater through semi-confining layers

    Science.gov (United States)

    Rubin, H.; Buddemeier, R.W.

    1998-01-01

    This paper presents a generalized basic study that addresses practical needs for an understanding of the major mechanisms involved in the mineralization of groundwater in the Great Bend Prairie aquifer in south- central Kansas. This Quaternary alluvial aquifer and associated surface waters are subject to contamination by saltwater, which in some areas seeps from the deeper Permian bedrock formation into the overlying freshwater aquifer through semiconfining layers. A simplified conceptual model is adopted. It incorporates the freshwater aquifer whose bottom is comprised of a semiconfining layer through which a hydrologically minor but geochemically important saline water discharge seeps into the aquifer. A hierarchy of approximate approaches is considered to analyze the mineralization processes taking place in the aquifer