Biofilm resilience to desiccation in groundwater aquifers: a laboratory and field study.

PubMed

Weaver, L; Webber, J B; Hickson, A C; Abraham, P M; Close, M E

2015-05-01

Groundwater is used as a precious resource for drinking water worldwide. Increasing anthropogenic activity is putting increasing pressure on groundwater resources. One impact of increased groundwater abstraction coupled with increasing dry weather events is the lowering of groundwater levels within aquifers. Biofilms within groundwater aquifers offer protection to the groundwater by removing contaminants entering the aquifer systems from land use activities. The study presented investigated the impact of desiccation events on the biofilms present in groundwater aquifers using field and laboratory experiments. In both field and laboratory experiments a reduction in enzyme activity (glucosidase, esterase and phosphatase) was seen during desiccation compared to wet controls. However, comparing all the data together no significant differences were seen between either wet or desiccated samples or between the start and end of the experiments. In both field and laboratory experiments enzyme activity recovered to start levels after return to wet conditions. The study shows that biofilms within groundwater systems are resilient and can withstand periods of desiccation (4 months). Copyright © 2014 Elsevier B.V. All rights reserved.

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

PubMed

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.

Transport behavior of groundwater protozoa and protozoan-sized microspheres in sandy aquifer sediments

USGS Publications Warehouse

Harvey, R.W.; Kinner, N.E.; Bunn, A.; MacDonald, D.; Metge, D.

1995-01-01

Transport behaviors of unidentified flagellated protozoa (flagellates) and flagellate-sized carboxylated microspheres in sandy, organically contaminated aquifer sediments were investigated in a small-scale (1 to 4-m travel distance) natural-gradient tracer test on Cape Cod and in flow-through columns packed with sieved (0.5-to 1.0-mm grain size) aquifer sediments. The minute (average in situ cell size, 2 to 3 ??m) flagellates, which are relatively abundant in the Cape Cod aquifer, were isolated from core samples, grown in a grass extract medium, labeled with hydroethidine (a vital eukaryotic stain), and coinjected into aquifer sediments along with bromide, a conservative tracer. The 2-??m flagellates appeared to be near the optimal size for transport, judging from flowthrough column experiments involving a polydispersed (0.7 to 6.2 ??m in diameter) suspension of carboxylated microspheres. However, immobilization within the aquifer sediments accounted for a log unit reduction over the first meter of travel compared with a log unit reduction over the first 10 m of travel for indigenous, free-living groundwater bacteria in earlier tests. High rates of flagellate immobilization in the presence of aquifer sediments also was observed in the laboratory. However, immobilization rates for the laboratory-grown flagellates (initially 4 to 5 ??m) injected into the aquifer were not constant and decreased noticeably with increasing time and distance of travel. The decrease in propensity for grain surfaces was accompanied by a decrease in cell size, as the flagellates presumably readapted to aquifer conditions. Retardation and apparent dispersion were generally at least twofold greater than those observed earlier for indigenous groundwater bacteria but were much closer to those observed for highly surface active carboxylated latex microspheres. Field and laboratory results suggest that 2- ??m carboxylated microspheres may be useful as analogs in investigating several abiotic

Specific yield - laboratory experiments showing the effect of time on column drainage

USGS Publications Warehouse

Prill, Robert C.; Johnson, A.I.; Morris, Donald Arthur

1965-01-01

The increasing use of ground water from many major aquifers in the United States has required a more thorough understanding of gravity drainage, or specific yield. This report describes one phase of specific yield research by the U.S. Geological Survey's Hydrologic Laboratory in cooperation with the California Department of Water Resources. An earlier phase of the research concentrated on the final distribution of moisture retained after drainage of saturated columns of porous media. This report presents the phase that concentrated on the distribution of moisture retained in similar columns after drainage for various periods of time. Five columns, about 4 cm in diameter by 170 cm long, were packed with homogenous sand of very fine, medium, and coarse sizes, and one column was packed with alternating layers of coarse and medium sand. The very fine materials were more uniform in size range than were the medium materials. As the saturated columns drained, tensiometers installed throughout the length recorded changes in moisture tension. The relation of tension to moisture content, determined for each of the materials, was then used to convert the tension readings to moisture content. Data were then available on the distribution of retained moisture for different periods of drainage from 1 to 148 hours. Data also are presented on the final distribution of moisture content by weight and volume and on the degree of saturation. The final zone of capillary saturation was approximately 12 cm for coarse sand, 13 cm for medium sand, and 52 cm for very fine sand. The data showed these zones were 92 to 100 percent saturated. Most of the outflow from the columns occurred in the earlier hours of drainage--90 percent in 1 hour for the coarse materials, 50 percent for the medium, and 60 percent for the very fine. Although the largest percentage of the specific yield was reached during the early hours of .drainage, this study amply demonstrates that a very long time would be

Successful Sampling Strategy Advances Laboratory Studies of NMR Logging in Unconsolidated Aquifers

NASA Astrophysics Data System (ADS)

Behroozmand, Ahmad A.; Knight, Rosemary; Müller-Petke, Mike; Auken, Esben; Barfod, Adrian A. S.; Ferré, Ty P. A.; Vilhelmsen, Troels N.; Johnson, Carole D.; Christiansen, Anders V.

2017-11-01

The nuclear magnetic resonance (NMR) technique has become popular in groundwater studies because it responds directly to the presence and mobility of water in a porous medium. There is a need to conduct laboratory experiments to aid in the development of NMR hydraulic conductivity models, as is typically done in the petroleum industry. However, the challenge has been obtaining high-quality laboratory samples from unconsolidated aquifers. At a study site in Denmark, we employed sonic drilling, which minimizes the disturbance of the surrounding material, and extracted twelve 7.6 cm diameter samples for laboratory measurements. We present a detailed comparison of the acquired laboratory and logging NMR data. The agreement observed between the laboratory and logging data suggests that the methodologies proposed in this study provide good conditions for studying NMR measurements of unconsolidated near-surface aquifers. Finally, we show how laboratory sample size and condition impact the NMR measurements.

Transient groundwater chemistry near a river: Effects on U(VI) transport in laboratory column experiments

USGS Publications Warehouse

Yin, J.; Haggerty, R.; Stoliker, D.L.; Kent, D.B.; Istok, J.D.; Greskowiak, J.; Zachara, J.M.

2011-01-01

In the 300 Area of a U(VI)-contaminated aquifer at Hanford, Washington, USA, inorganic carbon and major cations, which have large impacts on U(VI) transport, change on an hourly and seasonal basis near the Columbia River. Batch and column experiments were conducted to investigate the factors controlling U(VI) adsorption/desorption by changing chemical conditions over time. Low alkalinity and low Ca concentrations (Columbia River water) enhanced adsorption and reduced aqueous concentrations. Conversely, high alkalinity and high Ca concentrations (Hanford groundwater) reduced adsorption and increased aqueous concentrations of U(VI). An equilibrium surface complexation model calibrated using laboratory batch experiments accounted for the decrease in U(VI) adsorption observed with increasing (bi)carbonate concentrations and other aqueous chemical conditions. In the column experiment, alternating pulses of river and groundwater caused swings in aqueous U(VI) concentration. A multispecies multirate surface complexation reactive transport model simulated most of the major U(VI) changes in two column experiments. The modeling results also indicated that U(VI) transport in the studied sediment could be simulated by using a single kinetic rate without loss of accuracy in the simulations. Moreover, the capability of the model to predict U(VI) transport in Hanford groundwater under transient chemical conditions depends significantly on the knowledge of real-time change of local groundwater chemistry. Copyright 2011 by the American Geophysical Union.

Transient groundwater chemistry near a river: Effects on U(VI) transport in laboratory column experiments

USGS Publications Warehouse

Yin, Jun; Haggerty, Roy; Stoliker, Deborah L.; Kent, Douglas B.; Istok, Jonathan D.; Greskowiak, Janek; Zachara, John M.

2011-01-01

In the 300 Area of a U(VI)-contaminated aquifer at Hanford, Washington, USA, inorganic carbon and major cations, which have large impacts on U(VI) transport, change on an hourly and seasonal basis near the Columbia River. Batch and column experiments were conducted to investigate the factors controlling U(VI) adsorption/desorption by changing chemical conditions over time. Low alkalinity and low Ca concentrations (Columbia River water) enhanced adsorption and reduced aqueous concentrations. Conversely, high alkalinity and high Ca concentrations (Hanford groundwater) reduced adsorption and increased aqueous concentrations of U(VI). An equilibrium surface complexation model calibrated using laboratory batch experiments accounted for the decrease in U(VI) adsorption observed with increasing (bi)carbonate concentrations and other aqueous chemical conditions. In the column experiment, alternating pulses of river and groundwater caused swings in aqueous U(VI) concentration. A multispecies multirate surface complexation reactive transport model simulated most of the major U(VI) changes in two column experiments. The modeling results also indicated that U(VI) transport in the studied sediment could be simulated by using a single kinetic rate without loss of accuracy in the simulations. Moreover, the capability of the model to predict U(VI) transport in Hanford groundwater under transient chemical conditions depends significantly on the knowledge of real-time change of local groundwater chemistry.

Surfactant-enhanced remediation of a trichloroethene-contaminated aquifer. 1. Transport of triton X-100

USGS Publications Warehouse

Smith, J.A.; Sahoo, D.; Mclellan, H.M.; Imbrigiotta, T.E.

1997-01-01

Transport of a nonionic surfactant (Triton X-100) at aqueous concentrations less than 400 mg/L through a trichloroethene-contaminated sand-and-gravel aquifer at Picatinny Arsenal, NJ, has been studied through a series of laboratory and field experiments. In the laboratory, batch and column experiments were conducted to quantify the rate and amount of Triton X-100 sorption to the aquifer sediments. In the field, a 400 mg/L aqueous Triton X-100 solution was injected into the aquifer at a rate of 26.5 L/min for a 35-d period. The transport of Triton X-100 was monitored by sampling and analysis of groundwater at six locations surrounding the injection well. Equilibrium batch sorption experiments showed that Triton X-100 sorbs strongly and nonlinearly to the field soil with the sharpest inflection point of the isotherm occurring at an equilibrium aqueous Triton X-100 concentration close to critical micelle concentration. Batch, soil column, and field experimental data were analyzed with zero-, one-, and two- dimensional (respectively) transient solute transport models with either equilibrium or rate-limited sorption. These analyses reveal that Triton X- 100 sorption to the aquifer solids is slow relative to advective and dispersive transport and that an equilibrium sorption model cannot simulate accurately the observed soil column and field data. Comparison of kinetic sorption parameters from batch, column, and field transport data indicate that both physical heterogeneities and Triton X-100 mass transfer between water and soil contribute to the kinetic transport effects.Transport of a nonionic surfactant (Triton X-100) at aqueous concentrations less than 400 mg/L through a trichloroethene-contaminated sand-and-gravel aquifer was studied. Equilibrium batch sorption experiments showed that Triton X-100 sorbs strongly and nonlinearly to the field soil with the sharpest inflection point of the isotherm occurring at an equilibrium aqueous Triton X-100 concentration close to

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

NASA Astrophysics Data System (ADS)

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 < 1 day). Lag-times for the start of degradation of these compounds ranged from < 15 to 30 days. While iodipamide was persistent under aerobic conditions, artificial reductive geochemical conditions promoted via the addition of ethanol, resulted in rapid degradation (half life < 1 days). Pharmaceuticals (carbamazepine and oxazepam) and disinfection by-products (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.

An Automated Distillation Column for the Unit Operations Laboratory

ERIC Educational Resources Information Center

Perkins, Douglas M.; Bruce, David A.; Gooding, Charles H.; Butler, Justin T.

2005-01-01

A batch distillation apparatus has been designed and built for use in the undergraduate unit operations laboratory course. The column is fully automated and is accompanied by data acquisition and control software. A mixture of 1­-propanol and 2-­propanol is separated in the column, using either a constant distillate rate or constant composition…

Laboratory evidence of MTBE biodegradation in Borden aquifer material

NASA Astrophysics Data System (ADS)

Schirmer, Mario; Butler, Barbara J.; Church, Clinton D.; Barker, James F.; Nadarajah, Nalina

2003-02-01

Mainly due to intrinsic biodegradation, monitored natural attenuation can be an effective and inexpensive remediation strategy at petroleum release sites. However, gasoline additives such as methyl tert-butyl ether (MTBE) can jeopardize this strategy because these compounds often degrade, if at all, at a slower rate than the collectively benzene, toluene, ethylbenzene and the xylene (BTEX) compounds. Investigation of whether a compound degrades under certain conditions, and at what rate, is therefore important to the assessment of the intrinsic remediation potential of aquifers. A natural gradient experiment with dissolved MTBE-containing gasoline in the shallow, aerobic sand aquifer at Canadian Forces Base (CFB) Borden (Ontario, Canada) from 1988 to 1996 suggested that biodegradation was the main cause of attenuation for MTBE within the aquifer. This laboratory study demonstrates biologically catalyzed MTBE degradation in Borden aquifer-like environments, and so supports the idea that attenuation due to biodegradation may have occurred in the natural gradient experiment. In an experiment with batch microcosms of aquifer material, three of the microcosms ultimately degraded MTBE to below detection, although this required more than 189 days (or >300 days in one case). Failure to detect the daughter product tert-butyl alcohol (TBA) in the field and the batch experiments could be because TBA was more readily degradable than MTBE under Borden conditions.

Fertilizers mobilization in alluvial aquifer: laboratory experiments

NASA Astrophysics Data System (ADS)

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.

Influence of a compost layer on the attenuation of 28 selected organic micropollutants under realistic soil aquifer treatment conditions: insights from a large scale column experiment.

PubMed

Schaffer, Mario; Kröger, Kerrin Franziska; Nödler, Karsten; Ayora, Carlos; Carrera, Jesús; Hernández, Marta; Licha, Tobias

2015-05-01

Soil aquifer treatment is widely applied to improve the quality of treated wastewater in its reuse as alternative source of water. To gain a deeper understanding of the fate of thereby introduced organic micropollutants, the attenuation of 28 compounds was investigated in column experiments using two large scale column systems in duplicate. The influence of increasing proportions of solid organic matter (0.04% vs. 0.17%) and decreasing redox potentials (denitrification vs. iron reduction) was studied by introducing a layer of compost. Secondary effluent from a wastewater treatment plant was used as water matrix for simulating soil aquifer treatment. For neutral and anionic compounds, sorption generally increases with the compound hydrophobicity and the solid organic matter in the column system. Organic cations showed the highest attenuation. Among them, breakthroughs were only registered for the cationic beta-blockers atenolol and metoprolol. An enhanced degradation in the columns with organic infiltration layer was observed for the majority of the compounds, suggesting an improved degradation for higher levels of biodegradable dissolved organic carbon. Solely the degradation of sulfamethoxazole could clearly be attributed to redox effects (when reaching iron reducing conditions). The study provides valuable insights into the attenuation potential for a wide spectrum of organic micropollutants under realistic soil aquifer treatment conditions. Furthermore, the introduction of the compost layer generally showed positive effects on the removal of compounds preferentially degraded under reducing conditions and also increases the residence times in the soil aquifer treatment system via sorption. Copyright © 2015 Elsevier Ltd. All rights reserved.

Investigation of pharmaceutical transport in saturated sandy aquifers using column experiments: the effect of pH

NASA Astrophysics Data System (ADS)

Börnick, Hilmar; Boxberger, Norman; Licha, Tobias; Worch, Eckhard

2010-05-01

Due to the development of advanced analytical techniques it is increasingly known that a high number of polar organic trace compounds, particularly residues of pharmaceuticals, occur in the aquatic environment. In contrast to the sources and pathways of such compounds, their impact on ecosystems and their fate in different environmental compartments are comparatively less investigated. Because of the spatial extension and time available, the zone between water and natural solids (e.g. sediments or soil in groundwater zones, bank filtration sites and for soil aquifer treatment) plays an important role in the elimination of anthropogenic trace compounds from water phase. Here, degradation and sorption processes mainly influence the content of trace compounds. Correlations, specific for compound groups, between n-octanol-water distribution coefficients, available from experiment or calculations, and sorption coefficients (e.g. KOC) often allow a suitable prognosis of the transport behavior of organic pollutants in an underground passage. In case of polar, ionizable organic compounds such prediction is problematic and often not possible. Here, besides relatively weak non-polar van der Waals attraction, other interaction mechanisms, such as covalent bonding, complex formation, or ion exchange, can dominate. The latter is closely connected with the type of basic and/or acid groups in a molecule. The degree of protonation could be changed in dependence of type and concentration of other ions and of the acidity constants (pKa) and therefore from pH. Laboratory column studies at different pH value (range from 4 to 8) were carried out using natural sandy sediments from aquifers and model water containing selected pharmaceuticals to investigate the influence of degree of protonation on sorption. Eight different pharmaceuticals were chosen for laboratory column experiments. Their selection was based on the presence of basic/acid functional groups, pKa, high production and

Identification of TCE and PCE sorption and biodegradation parameters in a sandy aquifer for fate and transport modelling: batch and column studies.

PubMed

Kret, E; Kiecak, A; Malina, G; Nijenhuis, I; Postawa, A

2015-07-01

The main aim of this study was to determine the sorption and biodegradation parameters of trichloroethene (TCE) and tetrachloroethene (PCE) as input data required for their fate and transport modelling in a Quaternary sandy aquifer. Sorption was determined based on batch and column experiments, while biodegradation was investigated using the compound-specific isotope analysis (CSIA). The aquifer materials medium (soil 1) to fine (soil 2) sands and groundwater samples came from the representative profile of the contaminated site (south-east Poland). The sorption isotherms were approximately linear (TCE, soil 1, K d = 0.0016; PCE, soil 1, K d = 0.0051; PCE, soil 2, K d = 0.0069) except for one case in which the best fitting was for the Langmuir isotherm (TCE, soil 2, K f = 0.6493 and S max = 0.0145). The results indicate low retardation coefficients (R) of TCE and PCE; however, somewhat lower values were obtained in batch compared to column experiments. In the column experiments with the presence of both contaminants, TCE influenced sorption of PCE, so that the R values for both compounds were almost two times higher. Non-significant differences in isotope compositions of TCE and PCE measured in the observation points (δ(13)C values within the range of -23.6 ÷ -24.3‰ and -26.3 ÷-27.7‰, respectively) indicate that biodegradation apparently is not an important process contributing to the natural attenuation of these contaminants in the studied sandy aquifer.

Simulating flow in karst aquifers at laboratory and sub-regional scales using MODFLOW-CFP

NASA Astrophysics Data System (ADS)

Gallegos, Josue Jacob; Hu, Bill X.; Davis, Hal

2013-12-01

Groundwater flow in a well-developed karst aquifer dominantly occurs through bedding planes, fractures, conduits, and caves created by and/or enlarged by dissolution. Conventional groundwater modeling methods assume that groundwater flow is described by Darcian principles where primary porosity (i.e. matrix porosity) and laminar flow are dominant. However, in well-developed karst aquifers, the assumption of Darcian flow can be questionable. While Darcian flow generally occurs in the matrix portion of the karst aquifer, flow through conduits can be non-laminar where the relation between specific discharge and hydraulic gradient is non-linear. MODFLOW-CFP is a relatively new modeling program that accounts for non-laminar and laminar flow in pipes, like karst caves, within an aquifer. In this study, results from MODFLOW-CFP are compared to those from MODFLOW-2000/2005, a numerical code based on Darcy's law, to evaluate the accuracy that CFP can achieve when modeling flows in karst aquifers at laboratory and sub-regional (Woodville Karst Plain, Florida, USA) scales. In comparison with laboratory experiments, simulation results by MODFLOW-CFP are more accurate than MODFLOW 2005. At the sub-regional scale, MODFLOW-CFP was more accurate than MODFLOW-2000 for simulating field measurements of peak flow at one spring and total discharges at two springs for an observed storm event.

Laboratory simulation of the effects of overburden stress on the specific storage of shallow artesian aquifers

USGS Publications Warehouse

Sepúlveda, Nicasio; Zack, A.L.; Krishna, J.H.; Quinones-Aponte, Vicente; Gomez-Gomez, Fernando; Morris, G.L.

1990-01-01

A laboratory experiment to measure the specific storage of an aquifer material was conducted. A known dead load, simulating an overburden load, was applied to a sample of completely saturated aquifer material contained inside a cylinder. After the dead load was applied, water was withdrawn from the sample, causing the hydrostatic pressure to decrease and the effective stress to increase. The resulting compression of the sample and the amount of water withdrawn were measured after equilibrium was reached. The procedure was repeated by increasing the dead load and the hydrostatic pressure followed by withdrawing water to determine new values of effective stress and compaction. The simulated dead loads are typical of those experienced by shallow artesian aquifers. The void ratio and the effective stress of the aquifer sample, as simulated by different dead loads, determine the pore volume compressibility which, in turn, determines the values of specific storage. An analytical algorithm was used to independently determine the stress dependent profile of specific storage. These values are found to be in close agreement with laboratory results. Implications for shallow artesian aquifers, with relatively small overburden stress, are also addressed.

BATCH AND COLUMN STUDIES ON BTEX BIODEGRADATION BY AQUIFER MICROORGANISMS UNDER DENITRIFYING CONDITIONS

EPA Science Inventory

The objective of these laboratory experiments was to determine the role nitrate plays in enhancing the biodegradation of fuel contaminated groundwater. Column studies were conducted to simulate the nitrate field demonstration project carried out earlier at Traverse City, MI so a...

Managed aquifer recharge: the fate of pharmaceuticals from infiltrated treated wastewater investigated through soil column experiments

NASA Astrophysics Data System (ADS)

Silver, Matthew; Selke, Stephanie; Balsaa, Peter; Wefer-Roehl, Annette; Kübeck, Christine; Schüth, Christoph

2017-04-01

The EU FP7 project MARSOL addresses water scarcity challenges in arid regions, where managed aquifer recharge (MAR) is an upcoming technology to recharge depleted aquifers using alternative water sources. Within this framework, column experiments were conducted to investigate the fate of pharmaceuticals when secondary treated wastewater (TWW) is infiltrated through a natural soil (organic matter content 6.8%) being considered for MAR. Three parallel experiments were run under conditions of continuous infiltration (one column) and wetting-drying cycles (two columns, with different analytes) over a 16 month time period. The pharmaceuticals diclofenac, ibuprofen, carbamazepine, naproxen, gemfibrozil, and fenoprofen, as well as the antibiotics doxycycline, sulfadimidine, and sulfamethoxazole, are commonly present in treated wastewater in varying concentrations. For the experiments, concentration variability was reduced by spiking the column inflow water with these compounds. Concentrations were periodically analyzed at different depths in each column and the mass passing each depth over the duration of the experiment was calculated. At the end of the experiments, sorbed pharmaceuticals were extracted from soil samples collected from different depths. A pressurized liquid extraction method was developed and resulted in recoveries from spiked post-experiment soil samples ranging from 64% (gemfibrozil) to 82% (carbamazepine) for the six non-antibiotic compounds. Scaling results by these recovery rates, the total mass of pharmaceuticals sorbed to the soil in the columns was calculated and compared to the calculated attenuated mass (i.e. mass that left the water phase). The difference between the attenuated mass and the sorbed mass is considered to be mass that degraded. Results for continuous infiltration conditions indicate that for carbamazepine and diclofenac, sorption is the primary attenuation mechanism, with missing (i.e. degraded) mass lying within the propagated

Field and laboratory analyses of water from the Columbia aquifer in Eastern Maryland

USGS Publications Warehouse

Bachman, L.J.

1984-01-01

Field and laboratory analyses of pH, alkalinity, and specific conductance from water samples collected from the Columbia aquifer on the Delmarva Peninsula in eastern Maryland were compared to determine if laboratory analyses could be used for making regional water-quality interpretations. Kruskal-Wallis tests of field and laboratory data indicate that the difference between field and laboratory values is usually not enough to affect the outcome of the statistical tests. Thus, laboratory measurements of these constituents may be adequate for making certain regional water-quality interpretations, although they may result in errors if used for geochemical interpretations.

Chemical Treatments for Mobilizing Arsenic from Contaminated Aquifer Solids to Accelerate Remediation

PubMed Central

Wovkulich, Karen; Mailloux, Brian J.; Lacko, Allison; Keimowitz, Alison R.; Stute, Martin; Simpson, H. James; Chillrud, Steven N.

2010-01-01

Arsenic is a prevalent contaminant at US Superfund sites where remediation by pump and treat systems is often complicated by slow desorption of As from Fe and Al (hydr)oxides in aquifer solids. Chemical amendments that either compete with As for sorption sites or dissolve Fe and Al (hydr)oxides can increase As mobility and improve pump and treat remediation efficiency. The goal of this work was to determine optimal amendments for improving pump and treat at As contaminated sites such as the Vineland Chemical Co. Superfund site in southern New Jersey. Extraction and column experiments were performed using As contaminated aquifer solids (81 ± 1 mg/kg), site groundwater, and either phosphate (NaH2PO4·H2O) or oxalic acid (C2H2O4·2H2O). In extraction experiments, phosphate mobilized between 11% and 94% of As from the aquifer solids depending on phosphate concentration and extraction time (1 mM-1 M; 1–24 h) and oxalic acid mobilized between 38 and 102% depending on oxalic acid concentration and extraction time (1–400 mM; 1–24 h). In column experiments, phosphate additions induced more As mobilization in the first few pore volumes but oxalic acid was more effective at mobilizing As overall and at lower amendment concentrations. At the end of the laboratory column experiments, 48% of As had been mobilized from the aquifer sediments with 100 mM phosphate and 88% had been mobilized with 10 mM oxalic acid compared with 5% with ambient groundwater alone. Furthermore, simple extrapolations based on pore volumes suggest that chemical treatments could lower the time necessary for clean up at the Vineland site from 600 a with ambient groundwater alone to potentially as little as 4 a with 10 mM oxalic acid. PMID:21076621

Biogeochemical impacts of aquifer thermal energy storage at 5, 12, 25 and 60°C investigated with anoxic column experiments

NASA Astrophysics Data System (ADS)

Bonte, M.; van Breukelen, B. M.; Van Der Wielen, P. W. J. J.; Stuyfzand, P. J.

2012-04-01

Aquifer thermal energy storage (ATES) uses groundwater to store energy for heating or cooling purposes in the built environment. ATES systems are often located in the same aquifers used for public drinking water supply, leading to urgent questions on its environmental impacts. This contribution presents the results of research on the biogeochemical impacts of ATES in anoxic column experiments at 5, 12, 25, and 60° C. In- and effluents are analyzed for major ions, trace elements, heavy metals, dissolved organic carbon (DOC) and UV extinction. Terminal restriction fragment length polymorphism (T-RFLP) of 16S rRNA genes and analysis of adenosine triphosphate (ATP) were used to detect changes in the microbiological population and activity. Results from the column experiments at 5, 25, and 60° C compared to the reference column at 12° C showed a number of changes in biogeochemical conditions: At 5° C, only changes were observed in alkalinity and calcium concentrations, resulting from calcite dissolution. The 25° C and 60° C column effluents from a sediment containing Fe-(hydr)oxides showed an increase in arsenic concentrations, well above the drinking water limit. This is due to either (reductive) dissolution of, or desorption from, iron(hydro)xides containing arsenic. In addition, at these two temperatures sulfate reduction occurred while this was undetectable at 5 and 12° C within the given timeframe (25 days) and analytical accuracy. The carbon source for sulfate reduction is inferred to be sedimentary organic carbon. Increasing DOC with residence time in the 60° C effluent suggests that at 60° C the terminal sulfate reduction step is rate limiting, while at 25° C the enzymatic hydrolization step in sulfate reducing bacteria is overall rate limiting. Specific ultraviolet absorption (SUVA, the ratio of UV extinction and DOC) however shows a clear decrease in reactivity of the humic acid fraction in DOC. This means that the DOC accumulation at 60° C could

Biodegradation of the surfactant linear alkylbenzenesulfonate in sewage- contaminated groundwater: A comparison of column experiments and field tracer tests

USGS Publications Warehouse

Krueger, C.J.; Radakovich, K.M.; Sawyer, T.E.; Barber, L.B.; Smith, R.L.; Field, J.A.

1998-01-01

Transport and biodegradation of linear alkylbenzenesulfonate (LAS) in sewage-contaminated groundwater were investigated for a range of dissolved oxygen concentrations. Both laboratory column and an 80-day continuous injection tracer test field experiments were conducted. The rates of LAS biodegradation increased with increasing dissolved oxygen concentrations and indicated the preferential biodegradation of the longer alkyl chain LAS homologues (i.e., C12 and C13) and external isomers (i.e., 2-and 3- phenyl). However, for similar dissolved oxygen concentrations, mass removal rates for LAS generally were 2-3 times greater in laboratory column experiments than in the field tracer test. Under low oxygen conditions (<1 mg/L) only a fraction of the LAS mixture biodegraded in both laboratory and field experiments. Biodegradation rate constants for the continuous injection field test (0.002-0.08 day-1) were comparable to those estimated for a 3-h injection (pulsed) tracer test conducted under similar biogeochemical conditions, indicating that increasing the exposure time of aquifer sediments to LAS did not increase biodegradation rates.Transport and biodegradation of linear alkylbenzenesulfonate (LAS) in sewage-contaminated groundwater were investigated for a range of dissolved oxygen concentrations. Both laboratory column and an 80-day continuous injection tracer test field experiments were conducted. The rates of LAS biodegradation increased with increasing dissolved oxygen concentrations and indicated the preferential biodegradation of the longer alkyl chain LAS homologues (i.e., C12 and C13) and external isomers (i.e., 2- and 3-phenyl). However, for similar dissolved oxygen concentrations, mass removal rates for LAS generally were 2-3 times greater in laboratory column experiments than in the field tracer test. Under low oxygen conditions (<1 mg/L) only a fraction of the LAS mixture biodegraded in both laboratory and field experiments. Biodegradation rate constants

ENVIRONMENTAL FACTORS INFLUENCING METHANOGENESIS IN A SHALLOW ANOXIC AQUIFER: A FIELD AND LABORATORY STUDY

EPA Science Inventory

The environmental factors influencing methanogenesis in a shallow anoxic aquifer were probed in a combined field and laboratory study. Field data collected over a year revealed that in situ rates of methane production were depressed in winter and elevated in summer. Over the same...

THE QUANTIFICATION OF AQUEOUS TRACERS IN LABORATORY AQUIFER MODELS USING LIGHT TRANSMISSION VISUALIZATION METHOD

EPA Science Inventory

The quantification of solute concentrations in laboratory aquifer models has been largely limited to the use of sampling ports, from which samples are collected for external analysis. One of the drawbacks to this method is that the act of sampling may disturb plume dynamics and ...

Understanding Uranium Behavior in a Reduced Aquifer

NASA Astrophysics Data System (ADS)

Janot, N.; Lezama-Pacheco, J. S.; Williams, K. H.; Bernier-Latmani, R.; Long, P. E.; Davis, J. A.; Fox, P. M.; Yang, L.; Giammar, D.; Cerrato, J. M.; Bargar, J.

2012-12-01

Uranium contamination of groundwater is a concern at several US Department of Energy sites, such Old Rifle, CO. Uranium transport in the environment is mainly controlled by its oxidation state, since oxidized U(VI) is relatively mobile, whereas U(IV) is relatively insoluble. Bio-remediation of contaminated aquifers aims at immobilizing uranium in a reduced form. Previous laboratory and field studies have shown that adding electron donor (lactate, acetate, ethanol) to groundwater stimulates the activity of metal- and sulfate-reducing bacteria, which promotes U(VI) reduction in contaminated aquifers. However, obtaining information on chemical and physical forms of U, Fe and S species for sediments biostimulated in the field, as well as kinetic parameters such as U(VI) reduction rate, is challenging due to the low concentration of uranium in the aquifers (typically < 10 ppm) and the expense of collecting large number of cores. An in-situ technique has been developed for studying uranium, iron and sulfur reduction dynamics during such bioremediation episodes. This technique uses in-well columns to obtain direct access to chemical and physical forms of U(IV) produced in the aquifer, evolving microbial communities, and trace and major ion groundwater constituents. While several studies have explored bioreduction of uranium under sulfate-reducing conditions, less attention has been paid to the initial iron-reducing phase, noted as being of particular importance to uranium removal. The aim of this work was to assess the formation of U(IV) during the early stages of a bio-remediation experiment at the Old Rifle site, CO, from early iron-reducing conditions to the transition to sulfate-reducing conditions. Several in-well chromatographic columns packed with sediment were deployed and were sampled at different days after the start of bio-reduction. X-ray absorption spectroscopy and X-ray microscopy were used to obtain information on Fe, S and U speciation and distribution

Estimating hydraulic properties using a moving-model approach and multiple aquifer tests.

PubMed

Halford, Keith J; Yobbi, Dann

2006-01-01

A new method was developed for characterizing geohydrologic columns that extended >600 m deep at sites with as many as six discrete aquifers. This method was applied at 12 sites within the Southwest Florida Water Management District. Sites typically were equipped with multiple production wells, one for each aquifer and one or more observation wells per aquifer. The average hydraulic properties of the aquifers and confining units within radii of 30 to >300 m were characterized at each site. Aquifers were pumped individually and water levels were monitored in stressed and adjacent aquifers during each pumping event. Drawdowns at a site were interpreted using a radial numerical model that extended from land surface to the base of the geohydrologic column and simulated all pumping events. Conceptually, the radial model moves between stress periods and recenters on the production well during each test. Hydraulic conductivity was assumed homogeneous and isotropic within each aquifer and confining unit. Hydraulic property estimates for all of the aquifers and confining units were consistent and reasonable because results from multiple aquifers and pumping events were analyzed simultaneously.

Estimating hydraulic properties using a moving-model approach and multiple aquifer tests

USGS Publications Warehouse

Halford, K.J.; Yobbi, D.

2006-01-01

A new method was developed for characterizing geohydrologic columns that extended >600 m deep at sites with as many as six discrete aquifers. This method was applied at 12 sites within the Southwest Florida Water Management District. Sites typically were equipped with multiple production wells, one for each aquifer and one or more observation wells per aquifer. The average hydraulic properties of the aquifers and confining units within radii of 30 to >300 m were characterized at each site. Aquifers were pumped individually and water levels were monitored in stressed and adjacent aquifers during each pumping event. Drawdowns at a site were interpreted using a radial numerical model that extended from land surface to the base of the geohydrologic column and simulated all pumping events. Conceptually, the radial model moves between stress periods and recenters on the production well during each test. Hydraulic conductivity was assumed homogeneous and isotropic within each aquifer and confining unit. Hydraulic property estimates for all of the aquifers and confining units were consistent and reasonable because results from multiple aquifers and pumping events were analyzed simultaneously. Copyright ?? 2005 National Ground Water Association.

Physical versus chemical effects on bacterial and bromide transport as determined from on site sediment column pulse experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hall, James A.; Mailloux, Brian J.; Onstott, Tullis C.

2005-02-01

Twenty eight bacterial and Br transport experiments were performed in the field to determine the effects of physical and chemical heterogeneity of the aquifer sediment. The experiments were performed using groundwater from two field locations to examine the effects of groundwater chemistry on transport. Groundwater was extracted from multilevel samplers and pumped through 7 cm long columns of intact sediment or re-packed sieved and coated or uncoated sediment from the underlying aquifer. Two bacterial strains, Comamonas sp. DA001 and Paenibacillus polymyxa FER-02, were injected along with Br into the influent end of the columns to examine the effect of cellmore » morphology and surface properties on bacterial transport. The effect of column sediment grain size and mineral coatings coupled with groundwater geochemistry were also delineated. Significant irreversible attachment of DA001 was observed in the Fe oxyhydroxide coated columns, but only in the sub-oxic groundwater where the concentrations of dissolved organic carbon (DOC) were ca. 1 ppm. In the oxic groundwater where DOC was ca. 8 ppm, little attachment of DA001 to the Fe oxyhydroxide coated columns was observed. This indicates that DOC can significantly reduce bacterial attachment due electrostatic interactions. The larger and more negatively charged FER-02 displayed increasing attachment with decreasing grain size regardless of DOC concentration, and modeling of FER-02 attachment revealed that the presence of Fe and Al coatings on the sediment also promoted attachment. Finally, the presence of Al coatings and Al containing minerals appeared to significantly retard the Br tracer regardless of the concentration of DOC. These findings suggest that DOC in shallow oxic groundwater aquifers can significantly enhance the transport of bacteria by reducing attachment to Fe, Mn and Al oxyhydroxides. This effect is profound for weakly charged, hydrophilic bacteria and may contribute to differences in observations

Smoothing analysis of slug tests data for aquifer characterization at laboratory scale

NASA Astrophysics Data System (ADS)

Aristodemo, Francesco; Ianchello, Mario; Fallico, Carmine

2018-07-01

The present paper proposes a smoothing analysis of hydraulic head data sets obtained by means of different slug tests introduced in a confined aquifer. Laboratory experiments were performed through a 3D large-scale physical model built at the University of Calabria. The hydraulic head data were obtained by a pressure transducer placed in the injection well and subjected to a processing operation to smooth out the high-frequency noise occurring in the recorded signals. The adopted smoothing techniques working in time, frequency and time-frequency domain are the Savitzky-Golay filter modeled by third-order polynomial, the Fourier Transform and two types of Wavelet Transform (Mexican hat and Morlet). The performances of the filtered time series of the hydraulic heads for different slug volumes and measurement frequencies were statistically analyzed in terms of optimal fitting of the classical Cooper's equation. For practical purposes, the hydraulic heads smoothed by the involved techniques were used to determine the hydraulic conductivity of the aquifer. The energy contents and the frequency oscillations of the hydraulic head variations in the aquifer were exploited in the time-frequency domain by means of Wavelet Transform as well as the non-linear features of the observed hydraulic head oscillations around the theoretical Cooper's equation.

Determining treatment requirements for turbid river water to avoid clogging of aquifer storage and recovery wells in siliceous alluvium.

PubMed

Page, Declan; Vanderzalm, Joanne; Miotliński, Konrad; Barry, Karen; Dillon, Peter; Lawrie, Ken; Brodie, Ross S

2014-12-01

The success of Aquifer Storage and Recovery (ASR) schemes relies on defining appropriate design and operational parameters in order to maintain high rates of recharge over the long term. The main contribution of this study was to define the water quality criteria and hence minimum pre-treatment requirements to allow sustained recharge at an acceptable rate in a medium-coarse sand aquifer. The source water was turbid, natural water from the River Darling, Australia. Three treatments were evaluated: bank filtration; coagulation and chlorine disinfection; and coagulation plus granular activated carbon and chlorine disinfection (GAC). Raw source water and the three treated waters were used in laboratory columns packed with aquifer material in replicate experiments in saturated conditions at constant temperature (19 °C) with light excluded for 37 days. Declines in hydraulic conductivity from a mean of 2.17 m/d occurred over the 37 days of the experiment. The GAC-treated water gave an 8% decline in hydraulic conductivity over the 16 cm length of columns, which was significantly different from the other three source waters, which had mean declines of 26-29%. Within the first 3 cm of column length, where most clogging occurred in each column, the mean hydraulic conductivity declined by 10% for GAC-treated water compared with 40-50% for the other source waters. There was very little difference between the columns until day 21, despite high turbidity (78 NTU) in the source water. Reducing turbidity by treatment was not sufficient to offset the reductions in hydraulic conductivity. Biological clogging was found to be most important as revealed by the accumulation of polysaccharides and bacterial numbers in columns when they were dissected and analysed at the end of the experiment. Further chemical clogging through precipitation of minerals was found not to occur within the laboratory columns, and dispersion of clay was also found to be negligible. Due to the low

Laboratory-Measured and Property-Transfer Modeled Saturated Hydraulic Conductivity of Snake River Plain Aquifer Sediments at the Idaho National Laboratory, Idaho

USGS Publications Warehouse

Perkins, Kim S.

2008-01-01

Sediments are believed to comprise as much as 50 percent of the Snake River Plain aquifer thickness in some locations within the Idaho National Laboratory. However, the hydraulic properties of these deep sediments have not been well characterized and they are not represented explicitly in the current conceptual model of subregional scale ground-water flow. The purpose of this study is to evaluate the nature of the sedimentary material within the aquifer and to test the applicability of a site-specific property-transfer model developed for the sedimentary interbeds of the unsaturated zone. Saturated hydraulic conductivity (Ksat) was measured for 10 core samples from sedimentary interbeds within the Snake River Plain aquifer and also estimated using the property-transfer model. The property-transfer model for predicting Ksat was previously developed using a multiple linear-regression technique with bulk physical-property measurements (bulk density [pbulk], the median particle diameter, and the uniformity coefficient) as the explanatory variables. The model systematically underestimates Ksat,typically by about a factor of 10, which likely is due to higher bulk-density values for the aquifer samples compared to the samples from the unsaturated zone upon which the model was developed. Linear relations between the logarithm of Ksat and pbulk also were explored for comparison.

THE QUANTIFICATION OF AQUEOUS TRACERS IN LABORATORY AQUIFER MODELS USING A LIGHT TRANSMISSION VISUALIZATION METHOD - 3

EPA Science Inventory

The quantification of solute concentrations in laboratory aquifer models has been largely limited to the use of sampling ports, from which samples are collected for external analysis. One of the drawbacks to this method is that the act of sampling may disturb plume dynamics and ...

THE QUANTIFICATION OF AQUEOUS TRACERS IN LABORATORY AQUIFER MODELS USING A LIGHT TRANSMISSION VISUALIZATION METHOD - 2

EPA Science Inventory

The quantification of solute concentrations in laboratory aquifer models has been largely limited to the use of sampling ports, from which samples are collected for external analysis. One of the drawbacks to this method is that the act of sampling may disturb plume dynamics and ...

THE QUANTIFICATION OF AQUEOUS TRACERS IN LABORATORY AQUIFER MODELS USING A LIGHT TRANSMISSION VISUALIZATION METHOD - 1

EPA Science Inventory

The quantification of solute concentrations in laboratory aquifer models has been largely limited to the use of sampling ports, from which samples are collected for external analysis. One of the drawbacks to this method is that the act of sampling may disturb plume dynamics and ...

Aquifer recharge with reclaimed water in the Llobregat Delta. Laboratory batch experiments and field test site.

NASA Astrophysics Data System (ADS)

Tobella, J.

2010-05-01

Summary Spain, as most other Mediterranean countries, faces near future water shortages, generalized pollution and loss of water dependent ecosystems. Aquifer recharge represents a promising option to become a source for indirect potable reuse purposes but presence of pathogens as well as organic and inorganic pollutants should be avoided. To this end, understanding the processes of biogeochemical degradation occurring within the aquifer during infiltration is capital. A set of laboratory batch experiments has been assembled in order to assess the behaviour of selected pesticides, drugs, estrogens, surfactant degradation products, biocides and phthalates under different redox conditions. Data collected during laboratory experiments and monitoring activities at the Sant Vicenç dels Horts test site will be used to build and calibrate a numerical model (i) of the physical-chemical-biochemical processes occurring in the batches and (ii) of multicomponent reactive transport in the unsaturated/saturated zone at the test site. Keywords Aquifer recharge, batch experiments, emerging micropollutants, infiltration, numerical model, reclaimed water, redox conditions, Soil Aquifer Treatment (SAT). 1. Introduction In Spain, the Llobregat River and aquifers, which supply water to Barcelona, have been overexploited for years and therefore, suffer from serious damages: the river dries up on summer, riparian vegetation has disappeared and seawater has intruded the aquifer. In a global context, solutions to water stress problems are urgently needed yet must be sustainable, economical and safe. Recent developments of analytical techniques detect the presence of the so-called "emerging" organic micropollutants in water and soils. Such compounds may affect living organisms when occurring in the environment at very low concentrations (microg/l or ng/l). In wastewater and drinking water treatment plants, a remarkable removal of these chemicals from water can be obtained only using

Modelling biological Cr(VI) reduction in aquifer microcosm column systems.

PubMed

Molokwane, Pulane E; Chirwa, Evans M N

2013-01-01

Several chrome processing facilities in South Africa release hexavalent chromium (Cr(VI)) into groundwater resources. Pump-and-treat remediation processes have been implemented at some of the sites but have not been successful in reducing contamination levels. The current study is aimed at developing an environmentally friendly, cost-effective and self-sustained biological method to curb the spread of chromium at the contaminated sites. An indigenous Cr(VI)-reducing mixed culture of bacteria was demonstrated to reduce high levels of Cr(VI) in laboratory samples. The effect of Cr(VI) on the removal rate was evaluated at concentrations up to 400 mg/L. Following the detailed evaluation of fundamental processes for biological Cr(VI) reduction, a predictive model for Cr(VI) breakthrough through aquifer microcosm reactors was developed. The reaction rate in batch followed non-competitive rate kinetics with a Cr(VI) inhibition threshold concentration of approximately 99 mg/L. This study evaluates the application of the kinetic parameters determined in the batch reactors to the continuous flow process. The model developed from advection-reaction rate kinetics in a porous media fitted best the effluent Cr(VI) concentration. The model was also used to elucidate the logistic nature of biomass growth in the reactor systems.

Mobilization of natural colloids from an iron oxide-coated sand aquifer--Effect of pH and ionic strength

USGS Publications Warehouse

Bunn, Rebecca A.; Magelky, Robin D.; Ryan, Joseph N.; Elimelech, Menachem

2002-01-01

Field and laboratory column experiments were performed to assess the effect of elevated pH and reduced ionic strength on the mobilization of natural colloids in a ferric oxyhydroxide-coated aquifer sediment. The field experiments were conducted as natural gradient injections of groundwater amended by sodium hydroxide additions. The laboratory experiments were conducted in columns of undisturbed, oriented sediments and disturbed, disoriented sediments. In the field, the breakthrough of released colloids coincided with the pH pulse breakthrough and lagged the bromide tracer breakthrough. The breakthrough behavior suggested that the progress of the elevated pH front controlled the transport of the mobilized colloids. In the laboratory, about twice as much colloid release occurred in the disturbed sediments as in the undisturbed sediments. The field and laboratory experiments both showed that the total mass of colloid release increased with increasing pH until the concurrent increase in ionic strength limited release. A decrease in ionic strength did not mobilize significant amounts of colloids in the field. The amount of colloids released normalized to the mass of the sediments was similar for the field and the undisturbed laboratory experiments.

Fate and Transport of CL-20 and RDX in Unsaturated Laboratory Columns

NASA Astrophysics Data System (ADS)

Lemond, L. A.; Gamerdinger, A. P.; Szecsody, J. E.

2005-05-01

This research examines the fate and transport of two explosive compounds, Hexanitrohexaazaisowurtzitane (CL-20) and Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in unsaturated laboratory columns. The transport and fate of these compounds were studied under saturated and unsaturated conditions in three natural soils: coarse sand, sandy loam, and a silt loam. Unsaturated column experiments were conducted using an ultra-centrifugation method. Sorption and degradation parameters were determined by moment analysis and hydrodynamic parameters were assessed with a two-region flow model. Differences in these parameters were evaluated as a function of water content. The fate and transport of CL-20 is highly dependent on 1) the soil type and 2) the compound's residence time in the soil and 3) water content of the media. Sorption of CL-20 was rate-limited. CL-20 degradation in saturated columns produced a half-life of as much as 22hr, but in unsaturated columns the degradation rate increased considerably, producing a half life of as little as 2hr. The fate and transport of RDX are also affected by the soil type, but sorption appeared to be instantaneous. Degradation of RDX was negligible. Our results suggest that at very low water content immobile water regions may become (at least in effect) isolated water regions and significantly alter the retardation of the tracer. In the sandy loam, there was as much as a 20-fold over-prediction of the retardation factor in the unsaturated saturated columns when predicted by Kd values derived from saturated columns. In the coarse sand, Kd values derived from saturated columns over-predicted retardation in the unsaturated columns by as much as 30%. In the silt loam, retardation factors were over-predicted by as much as 80%. At very low water contents, predictions of tracer behavior become very difficult because of changes in the flow regime that cannot be directly accounted for.

Chlorine-36 in the Snake River Plain Aquifer at the Idaho National Engineering Laboratory; origin and implications

USGS Publications Warehouse

Beasley, T.M.; Cecil, L.D.; Sharma, P.; Kubik, P.W.; Fehn, U.; Mann, L.J.; Gove, H.E.

1993-01-01

Between 1952 and 1984, low-level radioactive waste was introduced directly into the Snake River Plain aquifer at the Idaho National Engineering Laboratory (INEL), Idaho Falls, Idaho. These wastes were generated, principally, at the nuclear fuel reprocessing facility on the site. Our measurements of 36C1 in monitoring and production well waters, downgradient from disposal wells and seepage ponds, found easily detectable, nonhazardous concentrations of this radionuclide from the point of injection to the INEL southern site boundary. Comparisons are made between 3H and 36Cl concentrations in aquifer water and the advantages of 36C1 as a tracer of subsurface-water dynamics at the site are discussed.

Impact of recharge water temperature on bioclogging during managed aquifer recharge: a laboratory study

NASA Astrophysics Data System (ADS)

Xia, Lu; Gao, Zongjun; Zheng, Xilai; Wei, Jiuchuan

2018-04-01

To investigate the effect of recharge water temperature on bioclogging processes and mechanisms during seasonal managed aquifer recharge (MAR), two groups of laboratory percolation experiments were conducted: a winter test and a summer test. The temperatures were controlled at 5±2 and 15±3 °C, and the tests involved bacterial inoculums acquired from well water during March 2014 and August 2015, for the winter and summer tests, respectively. The results indicated that the sand columns clogged 10 times faster in the summer test due to a 10-fold larger bacterial growth rate. The maximum concentrations of total extracellular polymeric substances (EPS) in the winter test were approximately twice those in the summer test, primarily caused by a 200 μg/g sand increase of both loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS). In the first half of the experimental period, the accumulation of bacteria cells and EPS production induced rapid bioclogging in both the winter and summer tests. Afterward, increasing bacterial growth dominated the bioclogging in the summer test, while the accumulation of LB-EPS led to further bioclogging in the winter test. The biological analysis determined that the dominant bacteria in experiments for both seasons were different and the bacterial community diversity was 50% higher in the winter test than that for summer. The seasonal inoculums could lead to differences in the bacterial community structure and diversity, while recharge water temperature was considered to be a major factor influencing the bacterial growth rate and metabolism behavior during the seasonal bioclogging process.

Development and validation of a model of bio-barriers for remediation of Cr(VI) contaminated aquifers using laboratory column experiments.

PubMed

Shashidhar, T; Bhallamudi, S Murty; Philip, Ligy

2007-07-16

Bench scale transport and biotransformation experiments and mathematical model simulations were carried out to study the effectiveness of bio-barriers for the containment of hexavalent chromium in contaminated confined aquifers. Experimental results showed that a 10cm thick bio-barrier with an initial biomass concentration of 0.205mg/g of soil was able to completely contain a Cr(VI) plume of 25mg/L concentration. It was also observed that pore water velocity and initial biomass concentration are the most significant parameters in the containment of Cr(VI). The mathematical model developed is based on one-dimensional advection-dispersion reaction equations for Cr(VI) and molasses in saturated, homogeneous porous medium. The transport of Cr(VI) and molasses is coupled with adsorption and Monod's inhibition kinetics for immobile bacteria. It was found that, in general, the model was able to simulate the experimental results satisfactorily. However, there was disparity between the numerically simulated and experimental breakthrough curves for Cr(VI) and molasses in cases where there was high clay content and high microbial activity. The mathematical model could contribute towards improved designs of future bio-barriers for the remediation of Cr(VI) contaminated aquifers.

Effects of clay dispersion on aquifer storage and recovery in coastal aquifers

USGS Publications Warehouse

Konikow, Leonard F.; August, L.L.; Voss, C.I.

2001-01-01

Cyclic injection, storage, and withdrawal of freshwater in brackish aquifers is a form of aquifer storage and recovery (ASR) that can beneficially supplement water supplies in coastal areas. A 1970s field experiment in Norfolk, Virginia, showed that clay dispersion in the unconsolidated sedimentary aquifer occurred because of cation exchange on clay minerals as freshwater displaced brackish formation water. Migration of interstitial clay particles clogged pores, reduced permeability, and decreased recovery efficiency, but a calcium preflush was found to reduce clay dispersion and lead to a higher recovery efficiency. Column experiments were performed in this study to quantify the relations between permeability changes and clay mineralogy, clay content, and initial water salinity. The results of these experiments indicate that dispersion of montmorillonite clay is a primary contributor to formation damage. The reduction in permeability by clay dispersion may be expressed as a linear function of chloride content. Incorporating these simple functions into a radial, cross-sectional, variable-density, ground-water flow and transport model yielded a satisfactory simulation of the Norfolk field test - and represented an improvement over the model that ignored changes in permeability. This type of model offers a useful planning and design tool for ASR operations in coastal clastic aquifer systems.

Laboratory analog and numerical study of groundwater flow and solute transport in a karst aquifer with conduit and matrix domains.

PubMed

Faulkner, Jonathan; Hu, Bill X; Kish, Stephen; Hua, Fei

2009-11-03

New mathematical and laboratory methods have been developed for simulating groundwater flow and solute transport in karst aquifers having conduits imbedded in a porous medium, such as limestone. The Stokes equations are used to model the flow in the conduits and the Darcy equation is used for the flow in the matrix. The Beavers-Joseph interface boundary conditions are adopted to describe the flow exchange at the interface boundary between the two domains. A laboratory analog is used to simulate the conduit and matrix domains of a karst aquifer. The conduit domain is located at the bottom of the transparent plexiglas laboratory analog and glass beads occupy the remaining space to represent the matrix domain. Water flows into and out of the two domains separately and each has its own supply and outflow reservoirs. Water and solute are exchanged through an interface between the two domains. Pressure transducers located within the matrix and conduit domains of the analog provide data that is processed and stored in digital format. Dye tracing experiments are recorded using time-lapse imaging. The data and images produced are analyzed by a spatial analysis program. The experiments provide not only hydraulic head distribution but also capture solute front images and mass exchange measurements between the conduit and matrix domains. In the experiment, we measure and record pressures, and quantify flow rates and solute transport. The results present a plausible argument that laboratory analogs can characterize groundwater water flow, solute transport, and mass exchange between the conduit and matrix domains in a karst aquifer. The analog validates the predictions of a numerical model and demonstrates the need of laboratory analogs to provide verification of proposed theories and the calibration of mathematical models.

Development of Rhizo-Columns for Nondestructive Root System Architecture Laboratory Measurements

NASA Astrophysics Data System (ADS)

Oostrom, M.; Johnson, T. J.; Varga, T.; Hess, N. J.; Wietsma, T. W.

2016-12-01

Numerical models for root water uptake in plant-soil systems have been developing rapidly, increasing the demand for laboratory experimental data to test and verify these models. Most of the increasingly detailed models are either compared to long-term field crop data or do not involve comparisons at all. Ideally, experiments would provide information on dynamic root system architecture (RSA) in combination with soil-pant hydraulics such as water pressures and volumetric water contents. Data obtained from emerging methods such as Spectral Induced Polarization (SIP) and x-ray computed tomography (x-ray CT) may be used to provide laboratory RSA data needed for model comparisons. Point measurements such as polymer tensiometers (PT) may provide soil moisture information over a large range of water pressures, from field capacity to the wilting point under drought conditions. In the presentation, we demonstrate a novel laboratory capability allowing for detailed RSA studies in large columns under controlled conditions using automated SIP, X-ray CT, and PT methods. Examples are shown for pea and corn root development under various moisture regimes.

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

NASA Astrophysics Data System (ADS)

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

2017-04-01

still questionable, as the recharged water remineralization is accompanied by mineral depletion of the pond sediments. Study on the feasibility of this remineralization scheme is currently ongoing using laboratory column experiments and reactive transport modelling.

Chemical Constituents in Groundwater from Multiple Zones in the Eastern Snake River Plain Aquifer at the Idaho National Laboratory, Idaho, 2005-08

USGS Publications Warehouse

Bartholomay, Roy C.; Twining, Brian V.

2010-01-01

From 2005 to 2008, the U.S. Geological Survey's Idaho National Laboratory (INL) Project office, in cooperation with the U.S. Department of Energy, collected water-quality samples from multiple water-bearing zones in the eastern Snake River Plain aquifer. Water samples were collected from six monitoring wells completed in about 350-700 feet of the upper part of the aquifer, and the samples were analyzed for major ions, selected trace elements, nutrients, selected radiochemical constituents, and selected stable isotopes. Each well was equipped with a multilevel monitoring system containing four to seven sampling ports that were each isolated by permanent packer systems. The sampling ports were installed in aquifer zones that were highly transmissive and that represented the water chemistry of the top four to five model layers of a steady-state and transient groundwater-flow model. The model's water chemistry and particle-tracking simulations are being used to better define movement of wastewater constituents in the aquifer. The results of the water chemistry analyses indicated that, in each of four separate wells, one zone of water differed markedly from the other zones in the well. In four wells, one zone to as many as five zones contained radiochemical constituents that originated from wastewater disposal at selected laboratory facilities. The multilevel sampling systems are defining the vertical distribution of wastewater constituents in the eastern Snake River Plain aquifer and the concentrations of wastewater constituents in deeper zones in wells Middle 2051, USGS 132, and USGS 103 support the concept of groundwater flow deepening in the southwestern part of the INL.

Effective range of chlorine transport in an aquifer during disinfection of wells: From laboratory experiments to field application

NASA Astrophysics Data System (ADS)

Paufler, S.; Grischek, T.; Adomat, Y.; Herlitzius, J.; Hiller, K.; Metelica, Y.

2018-04-01

Microbiological contamination usually leads to erratic operation of drinking water wells and disinfection is required after disasters and sometimes to restore proper well performance for aquifer storage and recovery (ASR) and subsurface iron removal (SIR) wells. This study focused on estimating the fate of chlorine around an infiltration well and improving the knowledge about processes that control the physical extent of the disinfected/affected radius. Closed bottle batch tests revealed low chlorine consumption rates for filter gravel and sand (0.005 mg/g/d) and higher rates for clay (0.030 mg/g/d) as well as natural aquifer material (0.054 mg/g/d). Smaller grain sizes <1 mm showed 10- to 70-times higher initial chlorine consumption rates within the first hour after contact compared to the median consumption rates. Initial chlorine concentration most likely does not impact disinfection ability at grain sizes >1 mm, but results in more effective disinfection for very fine material <0.063 mm. Column studies focused on the adaptation of the lab results to an actual SIR waterworks in Khabarovsk, Russia. Results reinforced the previous lab results with low 1st-order decay constants of 16 d-1 for filter material and much higher values of 254 d-1 for natural aquifer material. Application of the chlorine consumption rates to an example well consistently indicated that the filter gravel pack consumes <1% of infiltrated chlorine. The disinfection zone at the example well seems to extend to maximum 3.5 m into the aquifer. Excessive chlorine dosage of >10 mg/l would not further extend the disinfected radius. A preferable way to increase the range of chlorine application is to increase the total infiltrated volume and time. Three approaches are proposed for adapting lab results to actual infiltration wells, that are in principle applicable to any other site.

EFFECT OF REDOX ZONATION ON THE REDUCTIVE TRANSFORMATION OF P-CYANONITROBENZENE IN A LABORATORY SEDIMENT COLUMN

EPA Science Inventory

The reductive transformation of a model compound, p-cyanonitrobenzene (pCNB), was investigated in a laboratory sediment column that had been characterized with respect to redox zonation. Characterization of the redox zones was assessed by measurement of the solution phase concent...

Effects of porous media preparation on bacteria transport through laboratory columns.

PubMed

Brown, Derick G; Stencel, Joseph R; Jaffé, Peter R

2002-01-01

Bacterial and colloid transport experiments related to environmental systems are typically performed in the laboratory, with sand often used as the porous media. In order to prepare the sand, mechanical sieving is frequently used to tighten the sand grain size distribution. However, mechanical sieving has been reported to provide insufficient repeatability between identical colloidal transport experiments. This work examined the deficiencies of mechanical sieving with respect to bacterial transport through sand columns. It was found that sieving with standard brass sieves (1) contaminates the sand with copper and zinc as a linear function of sieving time and (2) inefficiently sizes sand grains below 300 microm (the largest size examined in this study) due to rapid clogging of the sieves. A procedure was developed that allows utilization of brass sieves for sizing the sand grains and removes the metal contamination introduced from the sieves. Bacterial transport experiments utilizing this column preparation procedure gave repeatable breakthrough curves. Further examination of the effects of these treatments on bacterial transport showed interesting results. First, it was found that the metal contamination did not affect the clean-bed bacterial transport. Second. it was found that variations of the column flushing procedure did not alter the clean-bed breakthrough of the bacteria, but did alter the inter-particle blocking. Finally, it was found that the shape of the sand grains (oblong vs. rounded) significantly alters the bacterial transport. with the transport being dominated by the smallest dimension of the oblong grains.

Dehalococcoides abundance and alternate electron acceptor effects on large, flow-through trichloroethene dechlorinating columns.

PubMed

Mirza, Babur S; Sorensen, Darwin L; Dupont, R Ryan; McLean, Joan E

2016-03-01

Trichloroethene (TCE) in groundwater is a major health concern and biostimulation/bioaugmentation-based strategies have been evaluated to achieve complete reductive dechlorination with varying success. Different carbon sources were hypothesized to stimulate different extents of TCE reductive dechlorination. Ecological conditions that developed different dechlorination stages were investigated by quantitating Dehalococcoides 16S rRNA (Dhc) and reductive dehalogenase gene abundance, and by describing biogeochemical properties of laboratory columns in response to this biostimulation. Eight large columns (183 cm × 15.2 cm), packed with aquifer material from Hill AFB, Utah, that were continuously fed TCE for 7.5 years. Duplicate columns were biostimulated with whey or one of two different Newman Zone® emulsified oil formulations containing either nonionic surfactant (EOLN) or standard surfactant (EOL). Two columns were non-stimulated controls. Complete (whey amended), partial (EOLN amended), limited (EOL), and non-TCE dehalogenating systems (controls) developed over the course of the study. Bioaugmentation of half of the columns with Bachman Road culture 3 years prior to dismantling did not influence the extent of TCE dehalogenation. Multivariate analysis clustered samples by biostimulation treatments and extent of TCE dehalogenation. Dhc, tceA, and bvcA gene concentrations did not show a consistent relationship with TCE dehalogenation but the vcrA gene was more abundant in completely dehalogenating, whey-treated columns. The whey columns developed strongly reducing conditions producing Fe(II), sulfide, and methane. Biostimulation with different carbon and energy sources can support high concentrations of diverse Dhc, but carbon addition has a major influence on biogeochemical processes effecting the extent of TCE dehalogenation.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hershey, Ronald L.; Fereday, Wyatt

Dissolved inorganic carbon (DIC) carbon-14 ( 14C) is used to estimate groundwater ages by comparing the DIC 14C content in groundwater in the recharge area to the DIC 14C content in the downgradient sampling point. However, because of chemical reactions and physical processes between groundwater and aquifer rocks, the amount of DIC 14C in groundwater can change and result in 14C loss that is not because of radioactive decay. This loss of DIC 14C results in groundwater ages that are older than the actual groundwater ages. Alternatively, dissolved organic carbon (DOC) 14C in groundwater does not react chemically with aquifermore » rocks, so DOC 14C ages are generally younger than DIC 14C ages. In addition to chemical reactions, 14C ages may also be altered by the physical process of matrix diffusion. The net effect of a continuous loss of 14C to the aquifer matrix by matrix diffusion and then radioactive decay is that groundwater appears to be older than it actually is. Laboratory experiments were conducted to measure matrix diffusion coefficients for DOC 14C in volcanic and carbonate aquifer rocks from southern Nevada. Experiments were conducted using bromide (Br-) as a conservative tracer and 14C-labeled trimesic acid (TMA) as a surrogate for groundwater DOC. Outcrop samples from six volcanic aquifers and five carbonate aquifers in southern Nevada were used. The average DOC 14C matrix diffusion coefficient for volcanic rocks was 2.9 x 10 -7 cm 2/s, whereas the average for carbonate rocks was approximately the same at 1.7 x 10 -7 cm 2/s. The average Br- matrix diffusion coefficient for volcanic rocks was 10.4 x 10 -7 cm 2/s, whereas the average for carbonate rocks was less at 6.5 x 10 -7 cm 2/s. Carbonate rocks exhibited greater variability in DOC 14C and Br- matrix diffusion coefficients than volcanic rocks. These results confirmed, at the laboratory scale, that the diffusion of DOC 14C into southern Nevada volcanic and carbonate aquifers is slower than DIC 14C

COLUMN STUDIES ON BTEX BIODEGRADATION UNDER MICROAEROPHILIC AND DENITRIFYING CONDITIONS

EPA Science Inventory

Two column tests were conducted using aquifer material to simulate the nitrate field demonstration project carried out earlier at Traverse City, Michigan. The objectives were to better define the effect nitrate addition had on biodegradation of benzene, toluene, ethylbenzene, xyl...

Rates of microbial metabolism in deep coastal plain aquifers

USGS Publications Warehouse

Chapelle, F.H.; Lovley, D.R.

1990-01-01

Rates of microbial metabolism in deep anaerobic aquifers of the Atlantic coastal plain of South Carolina were investigated by both microbiological and geochemical techniques. Rates of [2-14C]acetate and [U-14C]glucose oxidation as well as geochemical evidence indicated that metabolic rates were faster in the sandy sediments composing the aquifers than in the clayey sediments of the confining layers. In the sandy aquifer sediments, estimates of the rates of CO2 production (millimoles of CO2 per liter per year) based on the oxidation of [2-14C]acetate were 9.4 x 10-3 to 2.4 x 10-1 for the Black Creek aquifer, 1.1 x 10-2 for the Middendorf aquifer, and <7 x 10-5 for the Cape Fear aquifer. These estimates were at least 2 orders of magnitude lower than previously published estimates that were based on the accumulation of CO2 in laboratory incubations of similar deep subsurface sediments. In contrast, geochemical modeling of groundwater chemistry changes along aquifer flowpaths gave rate estimates that ranged from 10-4 to 10-6 mmol of CO2 per liter per year. The age of these sediments (ca. 80 million years) and their organic carbon content suggest that average rates of CO2 production could have been no more than 10-4 mmol per liter per year. Thus, laboratory incubations may greatly overestimate the in situ rates of microbial metabolism in deep subsurface environments. This has important implications for the use of laboratory incubations in attempts to estimate biorestoration capacities of deep aquifers. The rate estimates from geochemical modeling indicate that deep aquifers are among the most oligotrophic aquatic environments in which there is ongoing microbial metabolism.

Combined use of field and laboratory testing to predict preferred flow paths in an heterogeneous aquifer.

PubMed

Gierczak, R F D; Devlin, J F; Rudolph, D L

2006-01-05

Elevated nitrate concentrations within a municipal water supply aquifer led to pilot testing of a field-scale, in situ denitrification technology based on carbon substrate injections. In advance of the pilot test, detailed characterization of the site was undertaken. The aquifer consisted of complex, discontinuous and interstratified silt, sand and gravel units, similar to other well studied aquifers of glaciofluvial origin, 15-40 m deep. Laboratory and field tests, including a conservative tracer test, a pumping test, a borehole flowmeter test, grain-size analysis of drill cuttings and core material, and permeameter testing performed on core samples, were performed on the most productive depth range (27-40 m), and the results were compared. The velocity profiles derived from the tracer tests served as the basis for comparison with other methods. The spatial variation in K, based on grain-size analysis, using the Hazen method, were poorly correlated with the breakthrough data. Trends in relative hydraulic conductivity (K/K(avg)) from permeameter testing compared somewhat better. However, the trends in transient drawdown with depth, measured in multilevel sampling points, corresponded particularly well with those of solute mass flux. Estimates of absolute K, based on standard pumping test analysis of the multilevel drawdown data, were inversely correlated with the tracer test data. The inverse nature of the correlation was attributed to assumptions in the transient drawdown packages that were inconsistent with the variable diffusivities encountered at the scale of the measurements. Collectively, the data showed that despite a relatively low variability in K within the aquifer under study (within a factor of 3), water and solute mass fluxes were concentrated in discrete intervals that could be targeted for later bioremediation.

Comparison of aquifer characterization approaches through steady state groundwater model validation: A controlled laboratory sandbox study

USGS Publications Warehouse

Illman, W.A.; Zhu, J.; Craig, A.J.; Yin, D.

2010-01-01

groundwater model validation is possible in this laboratory sandbox aquifer if the heterogeneous K distribution and forcing functions (boundary conditions and source/sink terms) are characterized sufficiently. ?? 2010 by the American Geophysical Union.

Field and laboratory evidence for intrinsic biodegradation of vinyl chloride contamination in a Fe(III)-reducing aquifer

USGS Publications Warehouse

Bradley, P.M.; Chapelle, F.H.; Wilson, J.T.

1998-01-01

Intrinsic bioremediation of chlorinated ethenes in anaerobic aquifers previously has not been considered feasible, due, in large part, to 1) the production of vinyl chloride during microbial reductive dechlorination of higher chlorinated contaminants and 2) the apparent poor biodegradability of vinyl chloride under anaerobic conditions. In this study, a combination of field geochemical analyses and laboratory radiotracer ([1,2-14C] vinyl chloride) experiments was utilized to assess the potential for intrinsic biodegradation of vinyl chloride contamination in an Fe(III)-reducing, anaerobic aquifer. Microcosm experiments conducted under Fe(III)-reducing conditions with material from the Fe(III)-reducing, chlorinated-ethene contaminated aquifer demonstrated significant oxidation of [1,2-14C] vinyl chloride to 14CO2 with no detectable production of ethene or other reductive dehalogenation products. Rates of degradation derived from the microcosm experiments (0.9-1.3% d-1) were consistent with field-estimated rates (0.03-0.2% d-1) of apparent vinyl chloride degradation. Field estimates of apparent vinyl chloride biodegradation were calculated using two distinct approaches; 1) a solute dispersion model and 2) a mass balance assessment. These findings demonstrate that degradation under Fe(III) reducing conditions can be an environmentally significant mechanism for intrinsic bioremediation of vinyl chloride in anaerobic ground-water systems.

Molecular analysis of microbial community structures in pristine and contaminated aquifers--Field and laboratory microcosm experiments

USGS Publications Warehouse

Shi, Y.; Zwolinski, M.D.; Schreiber, M.E.; Bahr, J.M.; Sewell, G.W.; Hickey, W.J.

1999-01-01

Molecular Analysis of Microbial Community Structures in Pristine and Contaminated Aquifers: Field and Laboratory Microcosm Experimentsvar callbackToken='531E8ACDB6C8511'; var subCode='asmjournal_sub'; var OAS_sitepage = 'aem.asm.org'; This study used phylogenetic probes in hybridization analysis to (i) determine in situ microbial community structures in regions of a shallow sand aquifer that were oxygen depleted and fuel contaminated (FC) or aerobic and noncontaminated (NC) and (ii) examine alterations in microbial community structures resulting from exposure to toluene and/or electron acceptor supplementation (nitrate). The latter objective was addressed by using the NC and FC aquifer materials for anaerobic microcosm studies in which phylogenetic probe analysis was complemented by microbial activity assays. Domain probe analysis of the aquifer samples showed that the communities were predominantlyBacteria; Eucarya and Archaea were not detectable. At the phylum and subclass levels, the FC and NC aquifer material had similar relative abundance distributions of 43 to 65% β- and γ-Proteobacteria (B+G), 31 to 35% α-Proteobacteria (ALF), 15 to 18% sulfate-reducing bacteria, and 5 to 10% high G+C gram positive bacteria. Compared to that of the NC region, the community structure of the FC material differed mainly in an increased abundance of B+G relative to that of ALF. The microcosm communities were like those of the field samples in that they were predominantly Bacteria (83 to 101%) and lacked detectable Archaea but differed in that a small fraction (2 to 8%) of Eucarya was detected regardless of the treatment applied. The latter result was hypothesized to reflect enrichment of anaerobic protozoa. Addition of nitrate and/or toluene stimulated microbial activity in the microcosms, but only supplementation of toluene alone significantly altered community structures. For the NC material, the dominant subclass shifted from B+G to ALF, while in the FC microcosms 55 to 65

Aerobic biotransformation of N-nitrosodimethylamine and N-nitrodimethylamine in methane and benzene amended soil columns

NASA Astrophysics Data System (ADS)

Weidhaas, Jennifer; Dupont, R. Ryan

2013-07-01

Aerobic biotransformation of N-nitrosodimethylamine (NDMA), an emerging contaminant of concern, and its structural analog N-nitrodimethylamine (DMN), was evaluated in benzene and methane amended groundwater passed through laboratory scale soil columns. Competitive inhibition models were used to model the kinetics for NDMA and DMN cometabolism accounting for the concurrent degradation of the growth and cometabolic substrates. Transformation capacities for NDMA and DMN with benzene (13 and 23 μg (mg cells)- 1) and methane (0.14 and 8.4 μg (mg cells)- 1) grown cultures, respectively are comparable to those presented in the literature, as were first order endogenous decay rates estimated to be 2.1 × 10- 2 ± 1.7 × 10- 3 d- 1 and 6.5 × 10- 1 ± 7.1 × 10- 1 d- 1 for the methane and benzene amended cultures, respectively. These studies highlight possible attenuation mechanisms and rates for NDMA and DMN biotransformation in aerobic aquifers undergoing active remediation, natural attenuation or managed aquifer recharge with treated wastewater (i.e., reclaimed water).

Transport and fate of engineered silver nanoparticles in aquifer media

NASA Astrophysics Data System (ADS)

Adrian, Y.; Schneidewind, U.; Azzam, R.

2016-12-01

Engineered silver nanoparticles (AgNPs) are used in various consumer and medical products due to their antimicrobial properties. Their transport behavior in the environment is still under investigation. Previous studies have been focusing on the transport of AgNPs in test systems with pure quartz sand or top soil materials, but studies investigating aquifer material are rare. However, the protection of groundwater resources is an important part in the protection of human health and the assurance of future economic activities. Therefore, expert knowledge regarding the transport, behavior and fate of engineered nanoparticles as potential contaminants in aquifers is essential. The transport and retention behavior of two commercially available engineered AgNPs (one stabilized with a polymere and one with a surfactant) in natural silicate-dominated aquifer material was investigated in saturated laboratory columns. For the experiments a mean grain size diameter of 0.7 mm was chosen with varying silt and clay contents to investigate their effect on the transport behavior of the AgNPs. Typical flow velocities were chosen to represent natural conditions. Particle concentration in the effluent was measured using ICP-MS and the finite element code HYDRUS-1D was used to model the transport and retention processes. The size of the silver nanoparticles in the effluent was analyzed using Flow Field-Flow Fractionation. The obtained results show that silt and clay contents as well as the stabilization of the AgNPs control the transport and retention of AgNPs. Increasing breakthrough was observed with decreasing clay and silt content.

Coupled effect of chemotaxis and growth on microbial distributions in organic-amended aquifer sediments: Observations from laboratory and field studies

USGS Publications Warehouse

Wang, M.; Ford, R.M.; Harvey, R.W.

2008-01-01

The inter-relationship of growth and chemotactic response exhibited by two common soil-inhabiting bacteria was investigated to determine its impact on bacterial migration. Filter-chambers were used to simulate aquifer sediments characterized by vertical gradients of organic contaminants in both artificial groundwater flow systems in the laboratory and within the screened intervals of observation wells in a sandy aquifer. A labile model contaminant (acetate) was added to the top compartments of the three-part chambers, whereas bacteria with a demonstrated propensity to grow on and chemotactically respond to acetate were introduced to the lower compartments, The motility and chemotactic response of Pseudomonas putida F1 resulted in 40 to 110% greater abundances in the upper compartments and concomitant 22 to 70% depletions in the lower compartments relative to the nonchemotactic controls over 2 days. Bacteria were in greatest abundance within the sand plug that separated the upper and lower compartments where sharp acetate gradients induced a strong chemotactic response. This observation was consistent with predictions from a mathematical model. In agreement with the laboratory results, the down-well filter-chamber incubations with Pseudomonas stutzeri in the aquifer indicated that 91% fewer bacteria resided in the lower compartment than the control experiment without acetate at 15 h. The combination of chemotaxis and growth greatly accelerated the migration of bacteria toward and subsequent abundance at the higher acetate concentration. ?? 2008 American Chemical Society.

Characterize Behaviour of Emerging Pollutants in Artificial Recharge: Column Experiments - Experiment Design and Results of Preliminary Tests

NASA Astrophysics Data System (ADS)

Wang, H.; Carrera, J.; Ayora, C.; Licha, T.

2012-04-01

Emerging pollutants (EPs) have been detected in water resources as a result of human activities in recent years. They include pharmaceuticals, personal care products, dioxins, flame retardants, etc. They are a source of concern because many of them are resistant to conventional water treatment, and they are harmful to human health, even in low concentrations. Generally, this study aims to characterize the behaviour of emerging pollutants in reclaimed water in column experiments which simulates artificial recharge. One column set includes three parts: influent, reactive layer column (RLC) and aquifer column (AC). The main influent is decided to be Secondary Effluent (SE) of El Prat Wastewater Treatment Plant, Barcelona. The flow rate of the column experiment is 0.9-1.5 mL/min. the residence time of RLC is designed to be about 1 day and 30-40 days for AC. Both columns are made of stainless steel. Reactive layer column (DI 10cm * L55cm) is named after the filling material which is a mixture of organic substrate, clay and goethite. One purpose of the application of the mixture is to increase dissolve organic carbon (DOC). Leaching test in batchs and columns has been done to select proper organic substrate. As a result, compost was selected due to its long lasting of releasing organic matter (OM). The other purpose of the application of the mixture is to enhance adsorption of EPs. Partition coefficients (Kow) of EPs indicate the ability of adsorption to OM. EPs with logKow>2 could be adsorbed to OM, like Ibuprofen, Bezafibrate and Diclofenac. Moreover, some of EPs are charged in the solution with pH=7, according to its acid dissociation constant (Ka). Positively charged EPs, for example Atenolol, could adsorb to clay. In the opposite, negatively charged EPs, for example Gemfibrozil, could adsorb to goethite. Aquifer column (DI 35cm * L1.5m) is to simulate the processes taking place in aquifer in artificial recharge. The filling of AC has two parts: silica sand and

Apparatus for Demonstrating Confined and Unconfined Aquifer Characteristics.

ERIC Educational Resources Information Center

Gillham, Robert W.; O'Hannesin, Stephanie F.

1984-01-01

Students in hydrogeology classes commonly have difficulty appreciating differences between the mechanisms of water release from confined and unconfined aquifers. Describes a simple and inexpensive laboratory model for demonstrating the hydraulic responses of confined and unconfined aquifers to pumping. Includes a worked example to demonstrate the…

Laboratory investigations on the role of sediment surface and ground water chemistry in transport of bacteria through a contaminated Sandy Aquifer

USGS Publications Warehouse

Scholl, M.A.; Harvey, R.W.

1992-01-01

The effects of pH and sediment surface characteristics on sorption of indigenous groundwater bacteria were determined using contaminated and uncontaminated aquifer material from Cape Cod, MA. Over the pH range of the aquifer (5-7), the extent of bacterial sorption onto sediment in uncontaminated groundwater was strongly pH-dependent, but relatively pH-insensitive in contaminated groundwater from the site. Bacterial sorption was also affected by the presence of oxyhydroxide coatings (iron, aluminum, and manganese). Surface coating effects were most pronounced in uncontaminated groundwater (pH 6.4 at 10??C). Desorption of attached bacteria (up to 14% of the total number of labeled cells added) occurred in both field and laboratory experiments upon adjustment of groundwater to pH 8. The dependence of bacterial sorption upon environmental conditions suggests that bacterial immobilization could change substantially over relatively short distances in contaminated, sandy aquifers and that effects caused by changes in groundwater geochemistry can be significant.

An update of hydrologic conditions and distribution of selected constituents in water, eastern Snake River Plain aquifer and perched groundwater zones, Idaho National Laboratory, Idaho, emphasis 2012-15

USGS Publications Warehouse

Bartholomay, Roy C.; Maimer, Neil V.; Rattray, Gordon W.; Fisher, Jason C.

2017-04-10

Since 1952, wastewater discharged to in ltration ponds (also called percolation ponds) and disposal wells at the Idaho National Laboratory (INL) has affected water quality in the eastern Snake River Plain (ESRP) aquifer and perched groundwater zones underlying the INL. The U.S. Geological Survey (USGS), in cooperation with the U.S. Department of Energy, maintains groundwater-monitoring networks at the INL to determine hydrologic trends and to delineate the movement of radiochemical and chemical wastes in the aquifer and in perched groundwater zones. This report presents an analysis of water-level and water-quality data collected from the ESRP aquifer, multilevel monitoring system (MLMS) wells in the ESRP aquifer, and perched groundwater wells in the USGS groundwater monitoring networks during 2012-15.

Design of Mixed Batch Reactor and Column Studies at Oak Ridge National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Weimin; Criddle, Craig S.

2015-11-16

We (the Stanford research team) were invited as external collaborators to contribute expertise in environmental engineering and field research at the ORNL IFRC, Oak Ridge, TN, for projects carried out at the Argonne National Laboratory and funded by US DOE. Specifically, we assisted in the design of batch and column reactors using ORNL IFRC materials to ensure the experiments were relevant to field conditions. During the funded research period, we characterized ORNL IFRC groundwater and sediments in batch microcosm and column experiments conducted at ANL, and we communicated with ANL team members through email and conference calls and face-to-face meetingsmore » at the annual ERSP PI meeting and national meetings. Microcosm test results demonstrated that U(VI) in sediments was reduced to U(IV) when amended with ethanol. The reduced products were not uraninite but unknown U(IV) complexes associated with Fe. Fe(III) in solid phase was only partially reduced. Due to budget reductions at ANL, Stanford contributions ended in 2011.« less

Transverse bacterial migration induced by chemotaxis in a packed column with structured physical heterogeneity.

PubMed

Wang, Meng; Ford, Roseanne M

2009-08-01

The significance of chemotaxis in directing bacterial migration toward contaminants in natural porous media was investigated under groundwater flow conditions. A laboratory-scale column, with a coarse-grained sand core surrounded by a fine-grained annulus, was used to simulate natural aquifers with strata of different hydraulic conductivities. A chemoattractant source was placed along the central axis of the column to model contaminants trapped in the heterogeneous subsurface. Chemotactic bacterial strains, Escherichia coli HCB1 and Pseudomonas putida F1, introduced into the column by a pulse injection, were found to alter their transport behaviors under the influence of the attractant chemical emanating from the central source. For E. coil HCB1, approximately 18% more of the total population relative to the control without attractant exited the column from the coarse sand layer due to the chemotactic effects of alpha-methylaspartate under an average fluid velocity of 5.1 m/d. Although P. putida F1 demonstrated no observable changes in migration pathways with the model contaminant acetate under the same flow rate, when the flow rate was reduced to 1.9 m/d, approximately 6-10% of the population relative to the control migrated from the fine sand layer toward attractant into the coarse sand layer. Microbial transport properties were further quantified by a mathematical model to examine the significance of bacterial motility and chemotaxis under different hydrodynamic conditions, which suggested important considerations for strain selection and practical operation of bioremediation schemes.

Transport of Escherichia coli in 25 m quartz sand columns

NASA Astrophysics Data System (ADS)

Lutterodt, G.; Foppen, J. W. A.; Maksoud, A.; Uhlenbrook, S.

2011-01-01

To help improve the prediction of bacteria travel distances in aquifers laboratory experiments were conducted to measure the distant dependent sticking efficiencies of two low attaching Escherichia coli strains (UCFL-94 and UCFL-131). The experimental set up consisted of a 25 m long helical column with a diameter of 3.2 cm packed with 99.1% pure-quartz sand saturated with a solution of magnesium sulfate and calcium chloride. Bacteria mass breakthrough at sampling distances ranging from 6 to 25.65 m were observed to quantify bacteria attachment over total transport distances ( αL) and sticking efficiencies at large intra-column segments ( αi) (> 5 m). Fractions of cells retained ( Fi) in a column segment as a function of αi were fitted with a power-law distribution from which the minimum sticking efficiency defined as the sticking efficiency of 0.001% bacteria fraction of the total input mass retained that results in a 5 log removal were extrapolated. Low values of αL in the order 10 - 4 and 10 - 3 were obtained for UCFL-94 and UCFL-131 respectively, while αi-values ranged between 10 - 6 to 10 - 3 for UCFL-94 and 10 - 5 to 10 - 4 for UCFL-131. In addition, both αL and αi reduced with increasing transport distance, and high coefficients of determination (0.99) were obtained for power-law distributions of αi for the two strains. Minimum sticking efficiencies extrapolated were 10 - 7 and 10 - 8 for UCFL-94 and UCFL-131, respectively. Fractions of cells exiting the column were 0.19 and 0.87 for UCFL-94 and UCL-131, respectively. We concluded that environmentally realistic sticking efficiency values in the order of 10 - 4 and 10 - 3 and much lower sticking efficiencies in the order 10 - 5 are measurable in the laboratory, Also power-law distributions in sticking efficiencies commonly observed for limited intra-column distances (< 2 m) are applicable at large transport distances(> 6 m) in columns packed with quartz grains. High fractions of bacteria populations

Field testing of aquifer thermal energy storage

NASA Astrophysics Data System (ADS)

Kannberg, L. D.; Allen, R. D.

1984-03-01

Results of field and laboratory studies of aquifer thermal energy storage (ATES) indicate both the problems and promise of the concept. Geohydrothermal modeling and field testing demonstrated the ability to recover substantial quantities of aquifer stored energy. However, the local hydrologic conditions play an important role in determining the recovery temperature and storage efficiency. Geochemistry is also an important factor, particularly for higher temperature ATES systems.

BIODEGRADATION OF AROMATIC HYDROCARBONS BY AQUIFER MICROORGANISMS UNDER DENITRIFYING CONDITIONS

EPA Science Inventory

A series of laboratory tests were conducted to evaluate whether denitrification would be a suitable alternative for biorestoration of an aquifer contaminated with JP-4 jet fuel. Microcosms were prepared from both uncontaminated and contaminated-aquifer material from the site, in ...

Improved Characterization of Groundwater Flow in Heterogeneous Aquifers Using Granular Polyacrylamide (PAM) Gel as Temporary Grout

NASA Astrophysics Data System (ADS)

Klepikova, Maria V.; Roques, Clement; Loew, Simon; Selker, John

2018-02-01

The range of options for investigation of hydraulic behavior of aquifers from boreholes has been limited to rigid, cumbersome packers, and inflatable sleeves. Here we show how a new temporary borehole sealing technique using soft grains of polyacrylamide (PAM) gel as a sealing material can be used to investigate natural groundwater flow dynamics and discuss other possible applications of the technology. If no compressive stress is applied, the gel packing, with a permeability similar to open gravel, suppresses free convection, allowing for local temperature measurements and chemical sampling through free-flowing gel packing. Active heating laboratory and field experiments combined with temperature measurements along fiber optic cables were conducted in water-filled boreholes and boreholes filled with soft grains of polyacrylamide gel. The gel packing is shown to minimize the effect of free convection within the well column and enable detection of thin zones of relatively high or low velocity in a highly transmissive alluvial aquifer, thus providing a significant improvement compared to temperature measurements in open boreholes. Laboratory experiments demonstrate that under modest compressive stress to the gel media the permeability transitions from highly permeable to nearly impermeable grouting. Under this configuration the gel packing could potentially allow for monitoring local response pressure from the formation with all other locations in the borehole hydraulically isolated.

Do natural biofilm impact nZVI mobility and interactions with porous media? A column study.

PubMed

Crampon, Marc; Hellal, Jennifer; Mouvet, Christophe; Wille, Guillaume; Michel, Caroline; Wiener, Anke; Braun, Juergen; Ollivier, Patrick

2018-01-01

Nanoparticles (NP) used as remediation agents for groundwater treatment may interact with biofilms naturally present, altering NP mobility and/or reactivity and thereby NP effectiveness. The influence of the presence of a multi species biofilm on the mobility of two types of zero-valent iron NP (nZVI; NANOFER 25S and optimized NANOFER STAR, NanoIron s.r.o. (Czech Republic)) was tested in laboratory experiments with columns mimicking aquifer conditions. Biofilms were grown in columns filled with sand in nitrate reducing conditions using groundwater from an industrial site as inoculum. After two months growth, they were composed of several bacterial species, dominated by Pseudomonas stutzeri. Biofilm strongly affected the physical characteristics of the sand, decreasing total porosity from ~30% to ~15%, and creating preferential pathways with high flow velocities. nZVI suspensions were injected into the columns at a seepage velocity of 10mday - 1 . Presence of biofilm did not impact the concentrations of Fe at the column outlet nor the amount of total Fe retained in the sand, as attested by the measurement of magnetic susceptibility. However, it had a significant impact on NP size sorting as well as on total Fe distribution along the column. This suggests nZVI-biofilm interactions that were confirmed by microscopic observations using SEM/STEM coupled with energy-dispersive X-ray spectroscopy. Our study shows that biofilm modifies the water flow velocity in the porous media, favoring the transport of large aggregates and decreased NP mobility due to physical and chemical interactions. Copyright © 2017 Elsevier B.V. All rights reserved.

Geostatistical Modeling of Sediment Abundance in a Heterogeneous Basalt Aquifer at the Idaho National Laboratory, Idaho

USGS Publications Warehouse

Welhan, John A.; Farabaugh, Renee L.; Merrick, Melissa J.; Anderson, Steven R.

2007-01-01

The spatial distribution of sediment in the eastern Snake River Plain aquifer was evaluated and modeled to improve the parameterization of hydraulic conductivity (K) for a subregional-scale ground-water flow model being developed by the U.S. Geological Survey. The aquifer is hosted within a layered series of permeable basalts within which intercalated beds of fine-grained sediment constitute local confining units. These sediments have K values as much as six orders of magnitude lower than the most permeable basalt, and previous flow-model calibrations have shown that hydraulic conductivity is sensitive to the proportion of intercalated sediment. Stratigraphic data in the form of sediment thicknesses from 333 boreholes in and around the Idaho National Laboratory were evaluated as grouped subsets of lithologic units (composite units) corresponding to their relative time-stratigraphic position. The results indicate that median sediment abundances of the stratigraphic units below the water table are statistically invariant (stationary) in a spatial sense and provide evidence of stationarity across geologic time, as well. Based on these results, the borehole data were kriged as two-dimensional spatial data sets representing the sediment content of the layers that discretize the ground-water flow model in the uppermost 300 feet of the aquifer. Multiple indicator kriging (mIK) was used to model the geographic distribution of median sediment abundance within each layer by defining the local cumulative frequency distribution (CFD) of sediment via indicator variograms defined at multiple thresholds. The mIK approach is superior to ordinary kriging because it provides a statistically best estimate of sediment abundance (the local median) drawn from the distribution of local borehole data, independent of any assumption of normality. A methodology is proposed for delineating and constraining the assignment of hydraulic conductivity zones for parameter estimation, based on the

Validating the Goldstein-Wehner Law for the Stratified Positive Column of DC Discharge in an Undergraduate Laboratory

ERIC Educational Resources Information Center

Lisovskiy, V. A.; Koval, V. A.; Artushenko, E. P.; Yegorenkov, V. D.

2012-01-01

In this paper we suggest a simple technique for validating the Goldstein-Wehner law for a stratified positive column of dc glow discharge while studying the properties of gas discharges in an undergraduate laboratory. To accomplish this a simple device with a pre-vacuum mechanical pump, dc source and gas pressure gauge is required. Experiments may…

Reactive Transport of Marcellus Shale Waters in Natural Aquifers: the Role of Mineralogical Compositions and Spatial Distribution Patterns

NASA Astrophysics Data System (ADS)

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

Continuous-flow column study of reductive dehalogenation of PCE upon bioaugmentation with the Evanite enrichment culture

NASA Astrophysics Data System (ADS)

Azizian, Mohammad F.; Behrens, Sebastian; Sabalowsky, Andrew; Dolan, Mark E.; Spormann, Alfred M.; Semprini, Lewis

2008-08-01

A continuous-flow anaerobic column experiment was conducted to evaluate the reductive dechlorination of tetrachloroethene (PCE) in Hanford aquifer material after bioaugmentation with the Evanite (EV) culture. An influent PCE concentration of 0.09 mM was transformed to vinyl chloride (VC) and ethene (ETH) within a hydraulic residence time of 1.3 days. The experimental breakthrough curves were described by the one-dimensional two-site-nonequilibrium transport model. PCE dechlorination was observed after bioaugmentation and after the lactate concentration was increased from 0.35 to 0.67 mM. At the onset of reductive dehalogenation, cis-dichloroethene (c-DCE) concentrations in the column effluent exceeded the influent PCE concentration indicating enhanced PCE desorption and transformation. When the lactate concentration was increased to 1.34 mM, c-DCE reduction to vinyl chloride (VC) and ethene (ETH) occurred. Spatial rates of PCE and VC transformation were determined in batch-incubated microcosms constructed with aquifer samples obtained from the column. PCE transformation rates were highest in the first 5 cm from the column inlet and decreased towards the column effluent. Dehalococcoides cell numbers dropped from ˜ 73.5% of the total Bacterial population in the original inocula, to about 0.5% to 4% throughout the column. The results were consistent with estimates of electron donor utilization, with 4% going towards dehalogenation reactions.

Anaerobic degradation of vinyl chloride in aquifer microcosms.

PubMed

Smits, Theo H M; Assal, Antoine; Hunkeler, Daniel; Holliger, Christof

2011-01-01

The anaerobic degradation potential at a chloroethene-contaminated site was investigated by operating two anoxic column aquifer microcosms enriched in iron(III). One column was fed with vinyl chloride (VC) only (column A) and one with VC and acetate (column B). In column A, after about 600 pore volume exchanges (PVEs), VC started to disappear and reached almost zero VC recovery in the effluent after 1000 PVEs. No formation of ethene was observed. In column B, effluent VC was almost always only a fraction of influent VC. Formation of ethene was observed after 800 PVEs and started to become an important degradation product after 1550 PVEs. However, ethene was never observed in stoichiometric amounts compared with disappeared VC. The average stable isotope enrichment factor for VC disappearance in column A was determined to be -4.3‰. In column B, the isotope enrichment factor shifted from -10.7 to -18.5‰ concurrent with an increase in ethene production. Batch microcosms inoculated with column material showed similar isotope enrichment factors as the column microcosms. These results indicated that two degradation processes occurred, one in column A and two in parallel in column B with increasing importance of reductive dechlorination with time. This study suggests that in addition to reductive dechlorination, other degradation processes such as anaerobic oxidation should be taken into account when evaluating natural attenuation of VC and that isotope analysis can help to differentiate between different pathways of VC removal. American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.

Protists from a sewage‐contaminated aquifer on cape cod, Massachusetts

USGS Publications Warehouse

Novarino, Gianfranco; Warren, Alan; Kinner, Nancy E.; Harvey, Ronald W.

1994-01-01

Several species of flagellates (genera Bodo, Cercomonas, Cryptaulax, Cyathomonas, Goniomonas, Spumella) have been identified in cultures from a plume of organic contamination (treated sewage effluent) within an aquifer on Cape Cod, Massachusetts. Amoebae and numerous unidentifiable 2‐ to 3‐μm flagellates have also been observed. As a rule, flagellates were associated with solid surfaces, or were capable of temporary surface attachment, corroborating earlier observations from in situ and column transport experiments suggesting that protists in the Massachusetts aquifer have a high propensity for association with sediment grain surfaces. Based on the fact that cultures from the uncontaminated part of the aquifer yielded only a few species of protists, it is hypothesized that the greater abundance and variety of food sources in the contaminant plume is capable of supporting a greater number of protistan species.

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

NASA Astrophysics Data System (ADS)

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

2017-04-01

Hydrogen production from excess energy and its storage can help increasing the efficiency of solar and wind in the energy mix. Therefore, hydrogen needs large-scale intermediate storage independent of the intended later use as hydrogen gas or as reactant to produce methane in the Sabatier process. A possible storage solution is using the geological subsurface such as caverns built in salt deposits or aquifers that are not used for drinking water production. However, underground storage of hydrogen gas potentially leads to accidental gas leakages into near-surface potable aquifers triggering subsequent geochemical processes. These leakages pose potential risks that are currently not sufficiently understood. To close this gap in knowledge, a high-pressure laboratory column system was used to simulate a hydrogen gas intrusion into a shallow aquifer. Water and sediment were gained from a sandy Pleistocene aquifer near Neumünster, Germany. In the first stage of the experiment, 100% hydrogen gas was used to simulate dissolved hydrogen concentrations between 800 and 4000 µM by varying pH2 between 2 and 15 bars. pH values rose to between 7.9 and 10.4, partly due to stripping CO2 from the groundwater used during H2 gas addition. In a second stage, the pH was regulated in a range of 6.7 to 7.9 by using a gas mixture of 99% H2 and 1% CO2 at 5 bars of total gas pressure. Observed processes included hydrogen oxidation, sulfate reduction, acetogenesis, formate production, and methanogenesis, which were independent of the hydrogen concentration. Hydrogen oxidation and sulfate reduction showed zeroth order reaction rates and rate constants (106 to 412 µM/h and 12 to 33 µM/h, respectively) in the pH range between 8 and 10. At pH levels between 7 and 8, both reactions started out faster near the column's inflow but then seemed limited towards the columns outflow, suggesting the dependence of sulfate reduction on the pH-value. Acetogenesis dominated the pH range between 8 and 10

Column experiments on organic micropollutants - applications and limitations

NASA Astrophysics Data System (ADS)

Banzhaf, Stefan; Hebig, Klaus

2016-04-01

As organic micropollutants become more and more ubiquitous in the aquatic environment, a sound understanding of their fate and transport behaviour is needed. This is to assure both safe and clean drinking water supply for mankind in the future and to protect the aquatic environment from pollution and negative consequences caused by manmade contamination. Apart from countless field studies, column experiments were and are frequently used to study transport of organic micropollutants. As the transport of (organic) solutes in groundwater is controlled by the chemical and physical properties of the compounds, the solvent (the groundwater including all solutes), and the substrate (the aquifer material), the adjustment and control of these boundary conditions allow to study a multitude of different experimental setups and to address specific research questions. The main purpose, however, remains to study the transport of a specific compound and its sorption and degradation behaviour in a specific sediment or substrate. Apart from the effective control of the individual boundary conditions, the main advantage of columns studies compared to other experimental setups (such as field studies, batch/microcosm studies), is that conservative and reactive solute breakthrough curves are obtained, which represent the sum of the transport processes. The analysis of these curves is well-developed and established. Additionally, limitations of this experimental method are presented here: the effects observed in column studies are often a result of dynamic, non-equilibrium processes. Time (or flow velocity) plays a major role in contrast to batch experiments, in which all processes will be observed until equilibrium is reached in the substrate-solution-system. Slightly modifying boundary conditions in different experiments have a strong influence on transport and degradation behaviour of organic micropollutants. This is a significant severe issue when it comes to general findings on the

Laboratory-Scale Column Testing Using IONSIV IE-911 for Removing Cesium from Acidic Tank Waste Simulant. 2: Determination of Cesium Exchange Capacity and Effective Mass Transfer Coefficient from a 500-cm3 Column Experiement

DOE Office of Scientific and Technical Information (OSTI.GOV)

T.J. Tranter; R.D. Tillotson; T.A. Todd

2005-04-01

A semi-scale column test was performed using a commercial form of crystalline silicotitanate (CST) for removing radio-cesium from a surrogate acidic tank solution, which represents liquid waste stored at the Idaho National Engineering and Environmental Laboratory (INEEL). The engineered form of CST ion exchanger, known as IONSIVtmIE-911 (UOP, Mt. Laurel,NJ, USA), was tested in a 500-cm3 column to obtain a cesium breakthrough curve. The cesium exchange capacity of this column matched that obtained from previous testing with a 15-mc3 column. A numerical algorithm using implicit finite difference approximations was developed to solve the governing mass transport equations for the CSTmore » columns. An effective mass transfer coefficient was derived from solving these equations for previously reported 15 cm3 tests. The effective mass transfer coefficient was then used to predict the cesium breakthrough curve for the 500-cm3 column and compared to the experimental data reported in this paper. The calculated breakthrough curve showed excellent agreement with the data from the 500-cm3 column even though the interstitial velocity was a factor of two greater. Thus, this approach should provide a reasonable method for scale up to larger columns for treating actual tank waste.« less

Column experiments to investigate transport of colloidal humic acid through porous media during managed aquifer recharge

NASA Astrophysics Data System (ADS)

Liu, Dan; Zhou, Jingjing; Zhang, Wenjing; Huan, Ying; Yu, Xipeng; Li, Fulin; Chen, Xuequn

2017-01-01

Colloids act as vectors for pollutants in groundwater, thereby creating a series of environmental problems. While managed aquifer recharge plays an important role in protecting groundwater resources and controlling land subsidence, it has a significant effect on the transport of colloids. In this study, particle size and zeta potential of colloidal humic acid (HA) have been measured to determine the effects of different hydrochemistry conditions. Column experiments were conducted to examine the effects on the transport of colloidal HA under varying conditions of pH (5, 7, 9), ionic strength (<0.0005, 0.02, 0.05 M), cation valence (Na+, Ca2+) and flow rate (0.1, 0.2, 0.4 ml/min) through collectors (glass beads) to model the properties and quality of artificial recharge water and changes in the hydrodynamic field. Breakthrough curves showed that the behavior of colloidal HA being transported varied depending on the conditions. Colloid transport was strongly influenced by hydrochemical and hydrodynamic conditions. With decreasing pH or increasing ionic strength, a decrease in the peak effluent concentration of colloidal HA and increase in deposition could be clearly seen. Comparison of different cation valence tests indicated that changes in transport and deposition were more pronounced with divalent Ca2+ than with monovalent Na+. Changes in hydrodynamic field (flow rate) also had an impact on transportation of colloidal HA. The results of this study highlight the need for further research in this area.

Determining Changes in Groundwater Quality during Managed Aquifer Recharge

NASA Astrophysics Data System (ADS)

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.

The role of silica colloids on facilitated cesium transport through glass bead columns and modeling

NASA Astrophysics Data System (ADS)

Noell, Alan L.; Thompson, Joseph L.; Corapcioglu, M. Yavuz; Triay, Inés R.

1998-05-01

Groundwater colloids can act as a vector which enhances the migration of contaminants. While sorbed to mobile colloids, contaminants can be held in the aqueous phase which prevents them from interacting with immobile aquifer surfaces. In this study, an idealized laboratory set-up was used to examine the influence of amorphous silica colloids on the transport of cesium. Synthetic groundwater and saturated glass bead columns were used to minimize the presence of natural colloidal material. The columns were assembled in replicate, some packed with 150-210 μm glass bead and others packed with 355-420 μm glass beads. The colloids used in these experiments were 100 nm amorphous silica colloids from Nissan Chemical Company. In the absence of these colloids, the retardation factor for cesium was 8.0 in the 150-210 μm glass bead columns and 3.6 in the 355-420 μm glass bead columns. The influence of anthropogenic colloids was tested by injecting 0.09 pore volume slugs of an equilibrated suspension of cesium and colloids into the colloid-free columns. Although there was little noticeable facilitation in the smaller glass bead columns, there was a slight reduction in the retardation of cesium in the larger glass bead columns. This was attributed to cesium having less of a retention time in the larger glass bead columns. When cesium was injected into columns with a constant flux of colloids, the retardation of cesium was reduced by 14-32% in the 150-210 μm glass bead columns and by 38-51% in the 355-420 μm glass bead columns. A model based on Corapcioglu and Jiang (1993) [Corapcioglu, M.Y., Jiang, S., 1993. Colloid-facilitated groundwater contaminant transport, Water Resour. Res., 29 (7) 2215-2226] was compared with the experimental elution data. When equilibrium sorption expressions were used and the flux of colloids through the glass bead columns was constant, the colloid facilitated transport of cesium was able to be described using an effective retardation coefficient

Geochemical interactions between constituents in acidic groundwater and alluvium in an aquifer near Globe, Arizona

USGS Publications Warehouse

Stollenwerk, Kenneth G.

1994-01-01

Acidic water from a copper-mining area has contaminated an alluvial aquifer and stream near Globe, Arizona. The most contaminated groundwater has a pH of 3.3, and contains about 100 mmol/1 SO4, 50 mmol/1 Fe, 11 mmol/1 Al and 3 mmol/1 Cu. Reactions between alluvium and acidic groundwater were first evaluated in laboratory column experiments. A geochemical model was developed and used in the equilibrium speciation program, MINTEQA2, to simulate breakthrough curves for different constituents from the column. The geochemical model was then used to simulate the measured changes in concentration of aqueous constituents along a flow path in the aquifer.The pH was predominantly controlled by reaction with carbonate minerals. Where carbonates had been dissolved, adsorption of H+ by iron oxides was used to simulate pH. Acidic groundwater contained little or no dissolved oxygen, and most aqueous Fe was present as Fe(II). In the anoxic core of the plume, Fe(II) was oxidized by MnO2 to Fe(III), which then precipitated as Fe(OH)3. Attenuation of aqueous Cu, Co, Mn, Ni and Zn was a function of pH and could be quantitatively modeled with the diffuse-layer, surface complexation model in MINTEQA2. Aluminum precipitated as amorphous Al(OH)3 at pH < 4.7 and as AlOHSO4 at pH < 4.7. Aqueous Ca and SO4were close to equilibrium with gypsum.After the alluvium in the column had reached equilibrium with acidic groundwater, uncontaminated groundwater was eluted through the column to evaluate the effect of reactants on groundwater remediation. The concentration of Fe, Mn, Cu, Co, Ni and Zn rapidly decreased to the detection limits within a few pore volumes. All of the gypsum that had precipitated initially redissolved, resulting in elevated Ca and SO4concentrations for about 5 pore volumes. Aluminum and pH exhibited the most potential for continued adverse effects on groundwater quality. As H+ desorbed from Fe(OH)3, pH remained below 4.5 for more than 20 pore volumes, resulting in dissolution

Substantial contribution of biomethylation to aquifer arsenic cycling

USGS Publications Warehouse

Maguffin, Scott C.; Kirk, Matthew F.; Daigle, Ashley R.; Hinkle, Stephen R.; Jin, Qusheng

2015-01-01

Microbes play a prominent role in transforming arsenic to and from immobile forms in aquifers1. Much of this cycling involves inorganic forms of arsenic2, but microbes can also generate organic forms through methylation3, although this process is often considered insignificant in aquifers4, 5, 6, 7. Here we identify the presence of dimethylarsinate and other methylated arsenic species in an aquifer hosted in volcaniclastic sedimentary rocks. We find that dimethylarsinate is widespread in the aquifer and its concentration correlates strongly with arsenite concentration. We use laboratory incubation experiments and an aquifer injection test to show that aquifer microbes can produce dimethylarsinate at rates of about 0.1% of total dissolved arsenic per day, comparable to rates of dimethylarsinate production in surface environments. Based on these results, we estimate that globally, biomethylation in aquifers has the potential to transform 100 tons of inorganic arsenic to methylated arsenic species per year, compared with the 420–1,250 tons of inorganic arsenic that undergoes biomethylation in soils8. We therefore conclude that biomethylation could contribute significantly to aquifer arsenic cycling. Because biomethylation yields arsine and methylarsines, which are more volatile and prone to diffusion than other arsenic species, we further suggest that biomethylation may serve as a link between surface and subsurface arsenic cycling.

Redox-sensitivity and mobility of selected pharmaceutical compounds in a laboratory column experiment

NASA Astrophysics Data System (ADS)

Banzhaf, S.; Nödler, K.; Licha, T.; Krein, A.; Scheytt, T.

2012-04-01

Laboratory column experiments are suitable to investigate the sediment water interaction and to study the transport behaviour of solutes. Processes like retardation and degradation can be identified and quantified. The conducted experiment, which is closely connected to a field study in Luxembourg, investigated the transport behaviour of selected pharmaceutical compounds and their redox-dependent metabolism under water saturated conditions. Fine-grained natural sediment with a low hydraulic conductivity from a study site in Luxembourg was filled into the column. The water for the experiment was taken from a small stream at the same fieldsite. It was spiked with four pharmaceutical compounds (carbamazepine, diclofenac, ibuprofen, sulfamethoxazole) with concentrations between 170 and 300 ng/L for the different substances. The chosen pharmaceuticals were also detected in groundwater and surface water samples at the study site and used to qualify exchange/mixing of surface water and groundwater (BANZHAF et al., 2011). As some of the substances are known to exhibit redox-sensitive degradation, the redox-conditions were systematically varied throughout the experiment. This was realised by adding nitrate at the inflow of the column. During the experiment, which lasted for 2.5 months, four different nitrate concentrations (20-130 mg/L) were applied, beginning with the highest concentration. During the experiment water from the reservoir tank was sampled daily in order to detect a potential degradation of the pharmaceutical compounds before they enter the column. The effluent water was sampled every three hours to guarantee a maximum resolution for the analysis of the pharmaceuticals where necessary. In addition, major ions were analysed in the influent and effluent samples. Throughout the experiment physicochemical parameters (oxidation reduction potential (ORP), dissolved oxygen, electrical conductivity, and pH-value) were measured and logged at the outflow of the column

Hydrologic conditions and distribution of selected radiochemical and chemical constituents in water, Snake River Plain aquifer, Idaho National Engineering Laboratory, Idaho, 1989 through 1991

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bartholomay, R.C.; Orr, B.R.; Liszewski, M.J.

Radiochemical and chemical wastewater discharged since 1952 to infiltration ponds and disposal wells at the Idaho National Engineering Laboratory (INEL) has affected water quality in the Snake River Plain aquifer. The U.S. Geological Survey, in cooperation with the U.S. Department of Energy, maintains a continuous monitoring network at the INEL to determine hydrologic trends and to delineate the movement of radiochemical and chemical wastes in the aquifer. This report presents an analysis of water-level and water-quality data collected from the Snake River Plain aquifer during 1989-91. Water in the eastern Snake River Plain aquifer moves principally through fractures and interflowmore » zones in basalt, generally flows southwestward, and eventually discharges at springs along the Snake River. The aquifer is recharged principally from irrigation water, infiltration of streamflow, and ground-water inflow from adjoining mountain drainage basins. Water levels in wells throughout the INEL generally declined during 1989-91 due to drought. Detectable concentrations of radiochemical constituents in water samples from wells in the Snake River Plain aquifer at the INEL decreased or remained constant during 1989-91. Decreased concentrations are attributed to reduced rates of radioactive-waste disposal, sorption processes, radioactive decay, and changes in waste-disposal practices. Detectable concentrations of chemical constituents in water from the Snake River Plain aquifer at the INEL were variable during 1989-91. Sodium and chloride concentrations in the southern part of the INEL increased slightly during 1989-91 because of increased waste-disposal rates and a lack of recharge from the Big Lost River. Plumes of 1,1,1-trichloroethane have developed near the Idaho Chemical Processing Plant and the Radioactive Waste Management Complex as a result of waste disposal practices.« less

Evaluating Rotavirus and Norovirus transport processes in standardised and natural soil-water columns experiments

NASA Astrophysics Data System (ADS)

Gamazo, Pablo; Schijven, Jack; Victoria, Matias; Alvareda, Elena; López Tort, Fernando; Ramos, Julián; Lizasoain, Andrés; Sapriza, Gonzalo; Castells, Matias; Colina, Rodney

2017-04-01

In Uruguay, as in many developed and developing countries, rotavirus and norovirus are major causes of diarrhea and others symptoms of acute gastroenteritis. In some areas of Uruguay, groundwater is the only source of water for human consumption. In the rural area of the Salto district, virus contamination has been detected in several groundwater wells. Because sewer coverage is low, the most probable sources of contamination are nearby septic systems. This work aims to evaluate the transport of rotavirus and norovirus from clinic samples in two sets of column experiments under saturated conditions: 6.7-cm columns with quartz sand (ionic strength 1mM, pH 7.0) and with sand from the Salto aquifer (Uruguay) (9,2% coarse sand, 47,8% medium sand, 40,5% fine sand, magnesium/calcium bicarbonate water, Ionic strength 15.1 mM, pH 7.2). Both viruses were seeded for 2 pore volumes onto the columns. Samples were collected at the column outlet and viruses were enumerated by Q-PRCR. Breakthrough curves were constructed and fitted to a two-site kinetic attachment/detachment model, including blocking using Hydrus-1D. In the quartz sand column, both rotavirus and norovirus were removed two orders in magnitude. In the Salto sand column, rotavirus was removed 2 log10 as well, but norovirus was removed 4 log10. The fitting of the breakthrough curves indicated that blocking played a role for rotavirus in the Salto sand column. These results are consistent with the field observation where only rotavirus was detected in the Salto aquifer, while similar concentrations in Salto sewer effluent were measured for both viruses. This work, besides reporting actual parameters values for human virus transport modelling, shows the significant differences in transport that human viruses can have in standardised and natural soil-water systems.

Reduced biodegradability of desorption-resistant fractions of polycyclic aromatic hydrocarbons in soil and aquifer solids

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, J.C.; Alexander, M.

1996-11-01

Less of the desorption-resistant fractions of phenanthrene and naphthalene than freshly added phenanthrene and naphthalene was mineralized in columns of aquifer solids, loam, or muck. Slurrying columns of hydrocarbon-amended aquifer solids, loam, or muck enhanced the rate and extent of mineralization of desorption-resistant phenanthrene and naphthalene, but degradation was still less than in slurries amended with fresh compound. A substantial portion of the desorption-resistant compound remained undergraded in the slurry. A surfactant and methanol increased the mineralization of resistant phenanthrene in slurries of loam. A mixed culture of microorganisms enriched on desorption-resistant phenanthrene degraded twice as much of this fractionmore » of compound as a pseudomonad. The authors suggest that predictions of the environment fate of toxic chemicals require information on the biodegradability of the fraction of a compound that is resistant to desorption.« less

A numerical model for simulation of bioremediation of hydrocarbons in aquifers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Munoz, J.F.; Irarrazaval, M.J.

1998-03-01

A numerical model was developed to describe the bioremediation of hydrocarbons in ground water aquifers considering aerobic degradation. The model solves the independent transport of three solutes (oxygen, hydrocarbons, and microorganisms) in ground water flow using the method of characteristics. Interactions between the three solutes, in which oxygen and hydrocarbons are consumed by microorganisms, are represented by Monod kinetics, solved using a Runge-Kutta method. Model simulations showed good correlation as compared with results of soil column experiments. The model was used to estimate the time needed to remediate the columns, which varied from one to two years.

Iodine-129 in the Snake River Plain Aquifer at and Near the Idaho National Laboratory, Idaho, 2003 and 2007

USGS Publications Warehouse

Bartholomay, Roy C.

2009-01-01

From 1953 to 1988, wastewater containing approximately 0.94 curies of iodine-129 (129I) was generated at the Idaho National Laboratory (INL) in southeastern Idaho. Almost all of this wastewater was discharged at or near the Idaho Nuclear Technology and Engineering Center (INTEC) on the INL site. Most of the wastewater was discharged directly into the eastern Snake River Plain aquifer through a deep disposal well until 1984; however, some wastewater also was discharged into unlined infiltration ponds or leaked from distribution systems below the INTEC. In 2003, the U.S. Geological Survey (USGS), in cooperation with the U.S. Department of Energy, collected samples for 129I from 36 wells used to monitor the Snake River Plain aquifer, and from one well used to monitor a perched zone at the INTEC. Concentrations of 129I in the aquifer ranged from 0.0000066 +- 0.0000002 to 0.72 +- 0.051 picocuries per liter (pCi/L). Many wells within a 3-mile radius of the INTEC showed decreases of as much as one order of magnitude in concentration from samples collected during 1990-91, and all of the samples had concentrations less than the Environmental Protection Agency's Maximum Contaminant Level (MCL) of 1 pCi/L. The average concentration of 129I in 19 wells sampled during both collection periods decreased from 0.975 pCi/L in 1990-91 to 0.249 pCi/L in 2003. These decreases are attributed to the discontinuation of disposal of 129I in wastewater after 1988 and to dilution and dispersion in the aquifer. Although water from wells sampled in 2003 near the INTEC showed decreases in concentrations of 129I compared with data collected in 1990-91, some wells south and east of the Central Facilities Area, near the site boundary, and south of the INL showed slight increases. These slight increases may be related to variable discharge rates of wastewater that eventually moved to these well locations as a mass of water from a particular disposal period. In 2007, the USGS collected samples for

In situ treatment of arsenic contaminated groundwater by aquifer iron coating: Experimental study.

PubMed

Xie, Xianjun; Wang, Yanxin; Pi, Kunfu; Liu, Chongxuan; Li, Junxia; Liu, Yaqing; Wang, Zhiqiang; Duan, Mengyu

2015-09-15

In situ arsenic removal from groundwater by an aquifer iron coating method has great potential to be a cost effective and simple groundwater remediation technology, especially in rural and remote areas where groundwater is used as the main water source for drinking. The in situ arsenic removal technology was first optimized by simulating arsenic removal in various quartz sand columns under anoxic conditions. The effectiveness was then evaluated in an actual high-arsenic groundwater environment. The arsenic removal mechanism by the coated iron oxide/hydroxide was investigated under different conditions using scanning electron microscopy (SEM)/X-ray absorption spectroscopy, electron probe microanalysis, and Fourier transformation infrared spectroscopy. Aquifer iron coating method was developed via a 4-step alternating injection of oxidant, iron salt and oxygen-free water. A continuous injection of 5.0 mmol/L FeSO4 and 2.5 mmol/L NaClO for 96 h can form a uniform goethite coating on the surface of quartz sand without causing clogging. At a flow rate of 7.2 mL/min of the injection reagents, arsenic (as Na2HAsO4) and tracer fluorescein sodium to pass through the iron-coated quartz sand column were approximately at 126 and 7 column pore volumes, respectively. The retardation factor of arsenic was 23.0, and the adsorption capacity was 0.11 mol As per mol Fe. In situ arsenic removal from groundwater in an aquifer was achieved by simultaneous injections of As(V) and Fe(II) reagents. Arsenic fixation resulted from a process of adsorption/co-precipitation with fine goethite particles by way of bidentate binuclear complexes. Therefore, the study results indicate that the high arsenic removal efficiency of the in situ aquifer iron coating technology likely resulted from the expanded specific surface area of the small goethite particles, which enhanced arsenic sorption capability and/or from co-precipitation of arsenic on the surface of goethite particles. Copyright © 2015

A microfluidic device for preparing next generation DNA sequencing libraries and for automating other laboratory protocols that require one or more column chromatography steps.

PubMed

Tan, Swee Jin; Phan, Huan; Gerry, Benjamin Michael; Kuhn, Alexandre; Hong, Lewis Zuocheng; Min Ong, Yao; Poon, Polly Suk Yean; Unger, Marc Alexander; Jones, Robert C; Quake, Stephen R; Burkholder, William F

2013-01-01

Library preparation for next-generation DNA sequencing (NGS) remains a key bottleneck in the sequencing process which can be relieved through improved automation and miniaturization. We describe a microfluidic device for automating laboratory protocols that require one or more column chromatography steps and demonstrate its utility for preparing Next Generation sequencing libraries for the Illumina and Ion Torrent platforms. Sixteen different libraries can be generated simultaneously with significantly reduced reagent cost and hands-on time compared to manual library preparation. Using an appropriate column matrix and buffers, size selection can be performed on-chip following end-repair, dA tailing, and linker ligation, so that the libraries eluted from the chip are ready for sequencing. The core architecture of the device ensures uniform, reproducible column packing without user supervision and accommodates multiple routine protocol steps in any sequence, such as reagent mixing and incubation; column packing, loading, washing, elution, and regeneration; capture of eluted material for use as a substrate in a later step of the protocol; and removal of one column matrix so that two or more column matrices with different functional properties can be used in the same protocol. The microfluidic device is mounted on a plastic carrier so that reagents and products can be aliquoted and recovered using standard pipettors and liquid handling robots. The carrier-mounted device is operated using a benchtop controller that seals and operates the device with programmable temperature control, eliminating any requirement for the user to manually attach tubing or connectors. In addition to NGS library preparation, the device and controller are suitable for automating other time-consuming and error-prone laboratory protocols requiring column chromatography steps, such as chromatin immunoprecipitation.

Simultaneous attenuation of pharmaceuticals, organic matter, and nutrients in wastewater effluent through managed aquifer recharge: Batch and column studies.

PubMed

Im, Huncheol; Yeo, Inseol; Maeng, Sung Kyu; Park, Chul Hwi; Choi, Heechul

2016-01-01

Batch and column experiments were conducted to evaluate the removal of organic matter, nutrients, and pharmaceuticals and to identify the removal mechanisms of the target contaminants. The sands used in the experiments were obtained from the Youngsan River located in South Korea. Neutral and cationic pharmaceuticals (iopromide, estrone, and trimethoprim) were removed with efficiencies greater than 80% from different sand media during experiments, due to the effect of sorption between sand and pharmaceuticals. However, the anionic pharmaceuticals (sulfamethoxazole, ketoprofen, ibuprofen, and diclofenac) were more effectively removed by natural sand, compared to baked sand. These observations were mainly attributed to biodegradation under natural conditions of surface organic matter and ATP concentrations. The removal of organic matter and nitrogen was also found to increase under biotic conditions. Therefore, it is indicated that biodegradation plays an important role and act as major mechanisms for the removal of organic matter, nutrients, and selected pharmaceuticals during sand passage and the managed aquifer recharge, which is an effective treatment method for removing target contaminants. However, the low removal efficiencies of pharmaceuticals (e.g., carbamazepine and sulfamethoxazole) require additional processes (e.g., AOPs, NF and RO membrane), a long residence time, and long travel distance for increasing the removal efficiencies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Column Experiments Investigating Wetting and Drying of Soil and Consumption of Organic Contaminants for Managed Aquifer Recharge

NASA Astrophysics Data System (ADS)

Silver, M.; Schueth, C.; Wefer-Roehl, A.; Kuebeck, C.

2014-12-01

The EU FP7 project MARSOL seeks to address water scarcity challenges in arid regions. Within this framework, we conduct a series of experiments to evaluate the potential for water quality improvement and changes in hydraulic conductivity when managed aquifer recharge (MAR) is performed by infiltrating treated wastewater in soils that do not have high potential for sorption. For example, in the Attica (Athens and vicinity) region of Greece, the bedrock is mostly marble, resulting in calcite-rich soils that present little potential for sorption of contaminants to mineral surfaces. This leaves consumption of organic contaminants by microbes as the critical mechanism for water quality improvement, when treated wastewater is infiltrated through such soils. In order to enhance the potential for contaminant consumption by aerobic bacteria in a way that would be realistic to later perform in an infiltration basin, we conduct experiments using a series of wetting and drying cycles. The experimental setup consists of 90-cm long soil columns, fitted with oxygen sensors, time-domain reflectometry sensors (to measure moisture content), sampling ports, oxidation-reduction probes, and head observation tubes. We use the data collected from these sensors and features of the experimental setup to answer the following questions: 1. Does hydraulic conductivity change, from formation of a biofilm or dissolution of calcite (or both)? 2. Are organic contaminants consumed? 3. What effect do wetting and drying cycles have on consumption of organic contaminants? 4. How long can infiltration of treated wastewater last, before oxygen is consumed and conditions become reducing? These questions are investigated by observing the hydraulic head and outflow, performing tracer tests, taking samples from the sampling ports and outflow for chemical analyses, and measuring moisture content and oxygen concentration, in the course of performing multiple wetting and drying cycles. These column

Geochemical Impacts of Leaking CO2 from Subsurface Storage Reservoirs to Unconfined and Confined Aquifers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qafoku, Nikolla; Brown, Christopher F.; Wang, Guohui

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 effortsmore » 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

A Microfluidic Device for Preparing Next Generation DNA Sequencing Libraries and for Automating Other Laboratory Protocols That Require One or More Column Chromatography Steps

PubMed Central

Tan, Swee Jin; Phan, Huan; Gerry, Benjamin Michael; Kuhn, Alexandre; Hong, Lewis Zuocheng; Min Ong, Yao; Poon, Polly Suk Yean; Unger, Marc Alexander; Jones, Robert C.; Quake, Stephen R.; Burkholder, William F.

2013-01-01

Library preparation for next-generation DNA sequencing (NGS) remains a key bottleneck in the sequencing process which can be relieved through improved automation and miniaturization. We describe a microfluidic device for automating laboratory protocols that require one or more column chromatography steps and demonstrate its utility for preparing Next Generation sequencing libraries for the Illumina and Ion Torrent platforms. Sixteen different libraries can be generated simultaneously with significantly reduced reagent cost and hands-on time compared to manual library preparation. Using an appropriate column matrix and buffers, size selection can be performed on-chip following end-repair, dA tailing, and linker ligation, so that the libraries eluted from the chip are ready for sequencing. The core architecture of the device ensures uniform, reproducible column packing without user supervision and accommodates multiple routine protocol steps in any sequence, such as reagent mixing and incubation; column packing, loading, washing, elution, and regeneration; capture of eluted material for use as a substrate in a later step of the protocol; and removal of one column matrix so that two or more column matrices with different functional properties can be used in the same protocol. The microfluidic device is mounted on a plastic carrier so that reagents and products can be aliquoted and recovered using standard pipettors and liquid handling robots. The carrier-mounted device is operated using a benchtop controller that seals and operates the device with programmable temperature control, eliminating any requirement for the user to manually attach tubing or connectors. In addition to NGS library preparation, the device and controller are suitable for automating other time-consuming and error-prone laboratory protocols requiring column chromatography steps, such as chromatin immunoprecipitation. PMID:23894273

Transport and retention of surfactant- and polymer-stabilized engineered silver nanoparticles in silicate-dominated aquifer material

USDA-ARS?s Scientific Manuscript database

Packed column experiments were conducted to investigate the transport and blocking behavior of surfactant- and polymer-stabilized engineered silver nanoparticles (Ag-ENPs) in saturated natural aquifer material with varying silt and clay content, background solution chemistry, and flow velocity. Brea...

Denitrification in a low-temperature bioreactor system at two different hydraulic residence times: laboratory column studies.

PubMed

Nordström, Albin; Herbert, Roger B

2017-06-01

Nitrate removal rates in a mixture of pine woodchips and sewage sludge were determined in laboratory column studies at 5°C, 12°C, and 22°C, and at two different hydraulic residence times (HRTs; 58.2-64.0 hours and 18.7-20.6 hours). Baffles installed in the flow path were tested as a measure to reduce preferential flow behavior, and to increase the nitrate removal in the columns. The nitrate removal in the columns was simulated at 5°C and 12°C using a combined Arrhenius-Monod equation controlling the removal rate, and a first-order exchange model for incorporation of stagnant zones. Denitrification in the mixture of pine woodchips and sewage sludge reduced nitrate concentrations of 30 mg N L -1 at 5°C to below detection limits at a HRT of 58.2-64.0 hours. At a HRT of 18.7-20.6 hours, nitrate removal was incomplete. The Arrhenius frequency factor and activation energy retrieved from the low HRT data supported a biochemically controlled reaction rate; the same parameters, however, could not be used to simulate the nitrate removal at high HRT. The results show an inversely proportional relationship between the advection velocity and the nitrate removal rate, suggesting that bioreactor performance could be enhanced by promoting low advection velocities.

Laboratory analogue of a supersonic accretion column in a binary star system.

PubMed

Cross, J E; Gregori, G; Foster, J M; Graham, P; Bonnet-Bidaud, J-M; Busschaert, C; Charpentier, N; Danson, C N; Doyle, H W; Drake, R P; Fyrth, J; Gumbrell, E T; Koenig, M; Krauland, C; Kuranz, C C; Loupias, B; Michaut, C; Mouchet, M; Patankar, S; Skidmore, J; Spindloe, C; Tubman, E R; Woolsey, N; Yurchak, R; Falize, É

2016-06-13

Astrophysical flows exhibit rich behaviour resulting from the interplay of different forms of energy-gravitational, thermal, magnetic and radiative. For magnetic cataclysmic variable stars, material from a late, main sequence star is pulled onto a highly magnetized (B>10 MG) white dwarf. The magnetic field is sufficiently large to direct the flow as an accretion column onto the poles of the white dwarf, a star subclass known as AM Herculis. A stationary radiative shock is expected to form 100-1,000 km above the surface of the white dwarf, far too small to be resolved with current telescopes. Here we report the results of a laboratory experiment showing the evolution of a reverse shock when both ionization and radiative losses are important. We find that the stand-off position of the shock agrees with radiation hydrodynamic simulations and is consistent, when scaled to AM Herculis star systems, with theoretical predictions.

Iodine-129 in the Snake River Plain aquifer at the Idaho National Engineering Laboratory, Idaho

USGS Publications Warehouse

Mann, L.J.; Chew, E.W.; Morton, J.S.; Randolph, R.B.

1988-01-01

From 1953 to 1983, an estimated 0.01 to 0.136 Ci (curies)/year of iodine-129 were contained in wastewater generated by the ICPP (Idaho Chemical Processing Plant) at the Idaho National Engineering Laboratory. The wastewater was directly discharged to the Snake River Plain aquifer through a deep disposal well until February 9, 1984, when the well was replaced by an unlined infiltration pond; a second pond was put into use on October 17, 1985. For 1984-86, the annual amount of iodine-129 in wastewater discharged to the ponds ranged from 0.0064 to 0.039 Ci. In August 1986, iodine-129 concentrations in water from 35 wells near the ICPP ranged from less than the reporting level to 3.6 +or-0.4 pCi/L (picocuries/L). By comparison, in April 1977 the water from 20 wells contained a maximum of 27 +or-1 pCi/L of iodine-129; in 1981, the maximum concentration in water from 32 wells was 41 +or-2 pCi/L. The average concentrations of iodine-129 in water from 18 wells that were sampled in 1977, 1981 and 1986 were 4.0, 6.7 and 1.3 pCi/L, respectively. The marked decrease in the iodine-129 concentration from 1981 to 1986 is the result of three factors: (1) The amount of iodine-129 disposed annually; (2) a change from the routine use of the disposal well to the infiltration ponds; and (3) a dilution of the iodine-129 in the aquifer by recharge from the Big Lost River. (USGS)

High Temperature Aquifer Storage

NASA Astrophysics Data System (ADS)

Ueckert, Martina; Niessner, Reinhard; Baumann, Thomas

2016-04-01

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

Non-Fickian dispersive transport of strontium in laboratory-scale columns: Modelling and evaluation

NASA Astrophysics Data System (ADS)

Liu, Dongxu; Jivkov, Andrey P.; Wang, Lichun; Si, Gaohua; Yu, Jing

2017-06-01

In the context of environmental remediation of contaminated sites and safety assessment of nuclear waste disposal in the near-surface zone, we investigate the leaching and non-Fickian dispersive migration with sorption of strontium (mocking strontium-90) through columns packed with sand and clay. Analysis is based on breakthrough curves (BTCs) from column experiments, which simulated rainfall infiltration and source term release scenario, rather than applying constant tracer solution at the inlet as commonly used. BTCs are re-evaluated and transport parameters are estimated by inverse modelling using two approaches: (1) equilibrium advection-dispersion equation (ADE); and (2) continuous time random walk (CTRW). Firstly, based on a method for calculating leach concentration, the inlet condition with an exponential decay input is identified. Secondly, the results show that approximately 39%-58% of Br- and 16%-49% of Sr2+ are eluted from the columns at the end of the breakthrough experiments. This suggests that trapping mechanisms, including diffusion into immobile zones and attachment of tracer on mineral surfaces, are more pronounced for Sr2+ than for Br-. Thirdly, we demonstrate robustness of CTRW-based truncated power-law (TPL) model in capturing non-Fickian reactive transport with 0 < β < 2, and Fickian transport with β > 2. The non-Fickian dispersion observed experimentally is explained by variations of local flow field from preferential flow paths due to physical heterogeneities. Particularly, the additional sorption process of strontium on clay minerals contributes to the delay of the peak concentration and the tailing features, which leads to an enhanced non-Fickian transport for strontium. Finally, the ADE and CTRW approaches to environmental modelling are evaluated. It is shown that CTRW with a sorption term can describe non-Fickian dispersive transport of strontium at laboratory scale by identifying appropriate parameters, while the traditional ADE with

Behavior of pollutant-degrading microorganisms in aquifers: Predictions for genetically engineered organisms

USGS Publications Warehouse

Krumme, M.L.; Smith, R.L.; Egestorff, J.; Thiem, S.M.; Tiedje, J.M.; Timmis, K.N.; Dwyer, D.F.

1994-01-01

Bioremediation via environmental introductions of degradative microorganisms requires that the microbes survive in substantial numbers and effect an increase in the rate and extent of pollutant removal. Combined field and microcosm studies were used to assess these abilities for laboratory-grown bacteria. Following introduction into a contaminated aquifer, viable cells of Pseudomonas sp. B13 were present in the contaminant plume for 447 days; die-off was rapid in pristine areas. In aquifer microcosms, survival of B13 and FR120, a genetically engineered derivative of B13 having enhanced catabolic capabilities for substituted aromatics, was comparable to B13 field results; both bacteria degraded target pollutants in microcosms made with aquifer samples from the aerobic zone of the pollutant plume. Results suggest that field studies with nonrecombinant microorganisms may be coupled to laboratory studies with derivative strains to estimate their bioremediative efficacy. Furthermore, laboratory strains of bacteria can survive for extended periods of time in nature and thus may have important bioremediative applications. ?? 1994 American Chemical Society.

Integrating borehole logs and aquifer tests in aquifer characterization

USGS Publications Warehouse

Paillet, Frederick L.; Reese, R.S.

2000-01-01

Integration of lithologic logs, geophysical logs, and hydraulic tests is critical in characterizing heterogeneous aquifers. Typically only a limited number of aquifer tests can be performed, and these need to be designed to provide hydraulic properties for the principle aquifers in the system. This study describes the integration of logs and aquifer tests in the development of a hydrostratigraphic model for the surficial aquifer system in and around Big Cypress National Preserve in eastern Collier County, Florida. Borehole flowmeter tests provide qualitative permeability profiles in most of 26 boreholes drilled in the Study area. Flow logs indicate the depth of transmissive units, which are correlated across the study area. Comparison to published studies in adjacent areas indicates that the main limestone aquifer of the 000000Tamiami Formation in the study area corresponds with the gray limestone aquifer in western Dade County and the water table and lower Tamiami Aquifer in western Collier County. Four strategically located, multiwell aquifer tests are used to quantify the qualitative permeability profiles provided by the flowmeter log analysis. The hydrostratigraphic model based on these results defines the main aquifer in the central part of the study area as unconfined to semiconfined with a transmissivity as high as 30,000 m2/day. The aquifer decreases in transmissivity to less than 10,000 m2/day in some parts of western Collier County, and becomes confined to the east and northeast of the study area, where transmissivity decreases to below 5000 m2/day.Integration of lithologic logs, geophysical logs, and hydraulic tests is critical in characterizing heterogeneous aquifers. Typically only a limited number of aquifer tests can be performed, and these need to be designed to provide hydraulic properties for the principle aquifers in the system. This study describes the integration of logs and aquifer tests in the development of a hydrostratigraphic model for the

Impacts of Soil-aquifer Heat and Water Fluxes on Simulated Global Climate

NASA Technical Reports Server (NTRS)

Krakauer, N.Y.; Puma, Michael J.; Cook, B. I.

2013-01-01

Climate models have traditionally only represented heat and water fluxes within relatively shallow soil layers, but there is increasing interest in the possible role of heat and water exchanges with the deeper subsurface. Here, we integrate an idealized 50m deep aquifer into the land surface module of the GISS ModelE general circulation model to test the influence of aquifer-soil moisture and heat exchanges on climate variables. We evaluate the impact on the modeled climate of aquifer-soil heat and water fluxes separately, as well as in combination. The addition of the aquifer to ModelE has limited impact on annual-mean climate, with little change in global mean land temperature, precipitation, or evaporation. The seasonal amplitude of deep soil temperature is strongly damped by the soil-aquifer heat flux. This not only improves the model representation of permafrost area but propagates to the surface, resulting in an increase in the seasonal amplitude of surface air temperature of >1K in the Arctic. The soil-aquifer water and heat fluxes both slightly decrease interannual variability in soil moisture and in landsurface temperature, and decrease the soil moisture memory of the land surface on seasonal to annual timescales. The results of this experiment suggest that deepening the modeled land surface, compared to modeling only a shallower soil column with a no-flux bottom boundary condition, has limited impact on mean climate but does affect seasonality and interannual persistence.

Geochemistry of groundwater in the eastern Snake River Plain aquifer, Idaho National Laboratory and vicinity, eastern Idaho

USGS Publications Warehouse

Rattray, Gordon W.

2018-05-30

Nuclear research activities at the U.S. Department of Energy (DOE) Idaho National Laboratory (INL) in eastern Idaho produced radiochemical and chemical wastes that were discharged to the subsurface, resulting in detectable concentrations of some waste constituents in the eastern Snake River Plain (ESRP) aquifer. These waste constituents may pose risks to the water quality of the aquifer. In order to understand these risks to water quality the U.S. Geological Survey, in cooperation with the DOE, conducted a study of groundwater geochemistry to improve the understanding of hydrologic and chemical processes in the ESRP aquifer at and near the INL and to understand how these processes affect waste constituents in the aquifer.Geochemistry data were used to identify sources of recharge, mixing of water, and directions of groundwater flow in the ESRP aquifer at the INL. The geochemistry data were analyzed from 167 sample sites at and near the INL. The sites included 150 groundwater, 13 surface-water, and 4 geothermal-water sites. The data were collected between 1952 and 2012, although most data collected at the INL were collected from 1989 to 1996. Water samples were analyzed for all or most of the following: field parameters, dissolved gases, major ions, dissolved metals, isotope ratios, and environmental tracers.Sources of recharge identified at the INL were regional groundwater, groundwater from the Little Lost River (LLR) and Birch Creek (BC) valleys, groundwater from the Lost River Range, geothermal water, and surface water from the Big Lost River (BLR), LLR, and BC. Recharge from the BLR that may have occurred during the last glacial epoch, or paleorecharge, may be present at several wells in the southwestern part of the INL. Mixing of water at the INL primarily included mixing of surface water with groundwater from the tributary valleys and mixing of geothermal water with regional groundwater. Additionally, a zone of mixing between tributary valley water and

Adsorption and desorption of hexavalent chromium in an alluvial aquifer near Telluride, Colorado

USGS Publications Warehouse

Stollenwerk, K.G.; Grove, D.B.

1985-01-01

A laboratory investigation of reactions between hexavalent chromium [Cr(VI)] and alluvium was conducted to evaluate reactions of Cr(VI) contaminating an alluvial aquifer near Telluride, CO and to determine the mechanisms responsible for these reactions. Uncontaminated alluvium and groundwater (spiked with CrO42-) from the study site were used in batch and column experiments. Results of these experiments show that Cr(VI) was adsorbed by the alluvium. Distribution coefficients from batch experiments ranged from 52 L/kg at an equilibrium CrO42- concentration of 0.4 ??mol/L to 1.7 L/kg at an equilibrium concentration of 1400 ??mol/L. The zero point of charge for the alluvium was approximately 8.3, and the alluvium had a positive net charge at the groundwater pH of 6.8. Visual and chemical evidence indicated that Fe oxide and hydroxide coatings on the alluvial particles principally were responsible for the absorption of Cr(VI). During column experiments, Cr(VI) initially was desorbed easily from the alluvium by Cr-free groundwater; however, the rate of desorption decreased rapidly, and > 60 pore volumes of groundwater were required to decrease the effluent concentration of Cr(VI) to 3 ??mol/L [drinking water standard for Cr(VI) = 1 ??mol/L]. The quantity of Cr(VI) adsorbed varied with the type and concentration of other anions in solution.

High Temperature Aquifer Storage

NASA Astrophysics Data System (ADS)

Ueckert, Martina; Niessner, Reinhard; Baumann, Thomas

2015-04-01

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

Groundwater dynamics in a two-dimensional aquifer

NASA Astrophysics Data System (ADS)

Jules, Valentin; Devauchelle, Olivier; Lajeunesse, Eric

2017-11-01

During a rain event, water infiltrates into the ground where it flows slowly towards a river. The time scale and the geometry of this flow control the chemical composition and the discharge of the river. We use a tank filled with glass beads to simulate this process in a simplified laboratory experiment. A sprinkler pipe generates rain, which infiltrates into the porous material. Groundwater exits this laboratory aquifer through a side of the tank. Guérin et al. (2014) investigated the case of a quasi-horizontal flow. In nature, however, groundwater often follows non-horizontal flowlines. To create a vertical flow, we place the outlet of our experiment high above its bottom. We find that, during rainfall, the discharge Q increases as the rainfall rate R times the square root of time t (Q Rt 1 / 2). This laboratory aquifer thus responds linearly to the forcing. However, long after the rain has stopped, the discharge decreases as the inverse square of time (Q t-2), although linear systems of finite size typically relax exponentially. We investigate this surprising behavior using a combination of complex analysis and numerical methods.

A Laboratory Experiment To Measure Henry's Law Constants of Volatile Organic Compounds with a Bubble Column and a Gas Chromatography Flame Ionization Detector (GC-FID)

ERIC Educational Resources Information Center

Lee, Shan-Hu; Mukherjee, Souptik; Brewer, Brittany; Ryan, Raphael; Yu, Huan; Gangoda, Mahinda

2013-01-01

An undergraduate laboratory experiment is described to measure Henry's law constants of organic compounds using a bubble column and gas chromatography flame ionization detector (GC-FID). This experiment is designed for upper-division undergraduate laboratory courses and can be implemented in conjunction with physical chemistry, analytical…

Transport and fate of viruses in sediment and stormwater from a managed aquifer recharge site

USDA-ARS?s Scientific Manuscript database

Enteric viruses are one of the major concerns in water reclamation and reuse at managed aquifer recharge (MAR) sites. In this study, the transport and fate of bacteriophages MS2, PRD1, and FX174 were studied in sediment and stormwater (SW) collected from a MAR site in Parafield, Australia. Column ex...

Evidence of polycyclic aromatic hydrocarbon biodegradation in a contaminated aquifer by combined application of in situ and laboratory microcosms using (13)C-labelled target compounds.

PubMed

Bahr, Arne; Fischer, Anko; Vogt, Carsten; Bombach, Petra

2015-02-01

The number of approaches to evaluate the biodegradation of polycyclic aromatic hydrocarbons (PAHs) within contaminated aquifers is limited. Here, we demonstrate the applicability of a novel method based on the combination of in situ and laboratory microcosms using (13)C-labelled PAHs as tracer compounds. The biodegradation of four PAHs (naphthalene, fluorene, phenanthrene, and acenaphthene) was investigated in an oxic aquifer at the site of a former gas plant. In situ biodegradation of naphthalene and fluorene was demonstrated using in situ microcosms (BACTRAP(®)s). BACTRAP(®)s amended with either [(13)C6]-naphthalene or [(13)C5/(13)C6]-fluorene (50:50) were incubated for a period of over two months in two groundwater wells located at the contaminant source and plume fringe, respectively. Amino acids extracted from BACTRAP(®)-grown cells showed significant (13)C-enrichments with (13)C-fractions of up to 30.4% for naphthalene and 3.8% for fluorene, thus providing evidence for the in situ biodegradation and assimilation of those PAHs at the field site. To quantify the mineralisation of PAHs, laboratory microcosms were set up with BACTRAP(®)-grown cells and groundwater. Naphthalene, fluorene, phenanthrene, or acenaphthene were added as (13)C-labelled substrates. (13)C-enrichment of the produced CO2 revealed mineralisation of between 5.9% and 19.7% for fluorene, between 11.1% and 35.1% for acenaphthene, between 14.2% and 33.1% for phenanthrene, and up to 37.0% for naphthalene over a period of 62 days. Observed PAH mineralisation rates ranged between 17 μg L(-1) d(-1) and 1639 μg L(-1) d(-1). The novel approach combining in situ and laboratory microcosms allowed a comprehensive evaluation of PAH biodegradation at the investigated field site, revealing the method's potential for the assessment of PAH degradation within contaminated aquifers. Copyright © 2014 Elsevier Ltd. All rights reserved.

COLUMN EXPERIMENTS AND ANOMALOUS CONDUCTIVITY IN HYDROCARBON-IMPACTED SOILS

EPA Science Inventory

A laboratory experiment was designed to increase the understanding of the geoelectric effects of microbial " degradation of hydrocarbons. Eight large columns were were paired to provide a replicate of each of four experiments. These large-volume columns contained "sterilized" soi...

A Trans-disciplinary Hydrogeological Systems Analysis Approach for Identifying and Assessing Managed Aquifer Recharge Options: Example from the Darling River Floodplain, N.S.W., Australia

NASA Astrophysics Data System (ADS)

Lawrie, K.; Brodie, R. S.; Tan, K. P.; Halas, L.; Magee, J.; Gow, L.; Christensen, N. B.

2013-12-01

(including limited pump tests) and laboratory measurements. Recognition of significant Neogene-to-Present faulting, warping and tilting of the unconsolidated sediments (using AEM, airborne magnetics, regional gravity, LiDAR and drilling data) was critical to understanding recharge, inter-aquifer leakage and potential environmental impacts of MAR options. A program of borehole Nuclear Magnetic Resonance (NMR) logging provided a record of near-continuous variations in K through the saturated sedimentary sequence, with the NMR data integrated with other borehole and AEM data to produce 3D maps of aquifer transmissivity. A priority site was identified where aquifer storage and recovery (ASR) options were assessed. Maximal and residual risk assessments of 12 hazard types included hydrogeological modelling, laboratory column clogging studies and geochemical assessment to identify source water treatment requirements. The study found that the residual scientific/technical risks for ASR at the priority site are low if the supplementary water treatment trains are included.

Airborne electromagnetics (EM) as a three-dimensional aquifer-mapping tool

USGS Publications Warehouse

Wynn, Jeff; Pool, Don; Bultman, Mark; Gettings, Mark; Lemieux, Jean

2000-01-01

The San Pedro River in southeastern Arizona hosts a major migratory bird flyway, and was declared a Riparian Conservation Area by Congress in 1988. Recharge of the adjacent Upper San Pedro Valley aquifer was thought to come primarily from the Huachuca Mountains, but the U. S. Army Garrison of Fort Huachuca and neighboring city of Sierra Vista have been tapping this aquifer for many decades, giving rise to claims that they jointly threatened the integrity of the Riparian Conservation Area. For this reason, the U. S. Army funded two airborne geophysical surveys over the Upper San Pedro Valley (see figure 1), and these have provided us valuable information on the aquifer and the complex basement structure underlying the modern San Pedro Valley. Euler deconvolution performed on the airborne magnetic data has provided a depth-to-basement map that is substantially more complex than a map obtained earlier from gravity data, as would be expected from the higher-resolution magnetic data. However, we found the output of the Euler deconvolution to have "geologic noise" in certain areas, interpreted to be post-Basin-and-Range Tertiary volcanic flows in the sedimentary column above the basement but below the ground surface.

Simulating the 2012 High Plains drought using three single column versions (SCM) of BUGS5

NASA Astrophysics Data System (ADS)

Medina, I. D.; Denning, S.

2013-12-01

The impact of changes in the frequency and severity of drought on fresh water sustainability is a great concern for many regions of the world. One such location is the High Plains, where the local economy is primarily driven by fresh water withdrawals from the Ogallala Aquifer, which accounts for approximately 30% of total irrigation withdrawals from all U.S. aquifers combined. Modeling studies that focus on the feedback mechanisms that control the climate and eco-hydrology during times of drought are limited, and have used conventional General Circulation Models (GCMs) with grid length scales ranging from one hundred to several hundred kilometers. Additionally, these models utilize crude statistical parameterizations of cloud processes for estimating sub-grid fluxes of heat and moisture and have a poor representation of land surface heterogeneity. For this research, we will focus on the 2012 High Plains drought and will perform numerical simulations using three single column versions (SCM) of BUGS5 (Colorado State University (CSU) GCM coupled to the Simple Biosphere Model (SiB3)) at multiple sites overlying the Ogallala Aquifer for the 2011-2012 periods. In the first version of BUGS5, the model will be used in its standard bulk setting (single atmospheric column coupled to a single instance of SiB3), secondly, the Super-Parameterized Community Atmospheric Model (SP-CAM), a cloud resolving model (CRM consists of 64 atmospheric columns), will replace the single CSU GCM atmospheric parameterization and will be coupled to a single instance of SiB3, and for the third version of BUGS5, an instance of SiB3 will be coupled to each CRM column of the SP-CAM (64 CRM columns coupled to 64 instances of SiB3). To assess the physical realism of the land-atmosphere feedbacks simulated at each site by all versions of BUGS5, differences in simulated energy and moisture fluxes will be computed between the 2011 and 2012 period and will be compared to differences calculated using

Mineralization Of PAHs In Coal-Tar Impacted Aquifer Sediments And Associated Microbial Community Structure Investigated With FISH

EPA Science Inventory

The microbial community structure and mineralization of polycyclic aromatic hydrocarbons (PAHs) in a coal-tar contaminated aquifer were investigated spatially using fluorescence in situ hybridization (FISH) and in laboratory-scale incubations of the aquifer sediments. DAPI-detect...

Laboratory investigation of the potential influence of CO2 migration on trace element release from natural aquifer sediments

NASA Astrophysics Data System (ADS)

Lebel, J.; Hakala, A.; Keating, E. H.; Allen, D. E.

2010-12-01

Successful geologic CO2 sequestration requires that risk management practices include efforts to ensure the protection of groundwater resources. In order to determine the level of detail necessary for predictive reactive transport inputs, we focused on CO2-water-rock reactions at a particular natural analog site for CO2 release (Chimayo, NM, USA) that currently is the focus of a broader reactive transport modeling study. At the Chimayo natural analog site, fluids with elevated total dissolved solids (TDS) and CO2 are being released into a shallow aquifer along a series of faults. Although many areas of the shallow aquifer contain elevated TDS and CO2, some areas remain unaffected. The purpose of our study is to investigate whether laboratory-based reactions between CO2, synthetic groundwater (both high and low TDS), and Chimayo aquifer sediments can be used to interpret the geochemical processes that are responsible for elevated metal concentrations in the high-TDS, high-CO2 Chimayo groundwaters. Sediment samples were collected from an outcrop from the Chimayo aquifer (Tesuque Formation, Santa Fe Group). The samples were ground and size fractionated to <60 mesh. Two synthetic groundwater solutions were created based on the major ion chemistries from previous studies of well samples: synthetic Na-HCO3 “background” water and synthetic Na-Ca-Cl “saline” water. Four reactor vessels were constructed to examine CO2-water-rock reactions for two natural sediment samples; for each sample, one reaction contained the background water, and the other contained the saline water. The reactors were continuously sparged with CO2 at a pressure of 1 atm for 14 days, and the reactor vessels were sampled at 6 different time intervals. As expected, the reactors sparged with CO2 showed a pH decrease (ranging from 5.66-6.06); in control reactions without CO2 the pH stayed relatively high and similar to field-measured pH values of low-CO2 Chimayo waters (7.25-8.65). The refractive

Iodine-129 in the Snake River Plain aquifer at and near the Idaho National Engineering Laboratory, Idaho, 1990-91

USGS Publications Warehouse

Mann, L.J.; Beasley, T.M.

1994-01-01

From 1953 to 1990, an estimated 0.56 to 1.18 curies of iodine-129 were contained in wastewater generated by the Idaho Chemical Processing Plant (ICPP) at the Idaho National Engineering Laboratory. The waste- water was discharged directly to the Snake River Plain aquifer through a deep disposal well prior to February 1984 and through unlined disposal ponds in 1984-90. The wastewater did not contain measurable concentrations of iodine-129 in 1989-90. Samples were collected from 51 wells that obtain water from the Snake River Plain aquifer and 1 well that obtains water from a perched ground-water zone. The samples were analyzed for iodine-129 using an accelerator mass spectrometer which is two to six orders of magnitude more sensitive than neutron- activation methods. Therefore, iodine-129 was detectable in samples from a larger number of wells distributed over a larger area than previously was possible. Ground-water flow velocities calculated using iodine-129 data are estimated to be at least 6 feet per day. These velocities compare favorably with those of 4 to 10 feet per day calculated from tritium data and tracer studies at wells down- gradient from the ICPP. In 1990-91, concentrations of iodine-129 in water samples from wells that obtain water from the Snake River Plain aquifer ranged from less than 0.0000006+0.0000002 to 3.82.+0.19 picocuries per liter (pCi/L). The mean concentration in water from 18 wells was 0.81+0.19 pCi/L as compared with 1.30+0.26 pCi/L in 1986. The decrease in the iodine-l29 concentrations from 1986 to 1990-91 chiefly was the result of a decrease in the amount of iodine-129 disposed of annually, and changes in disposal techniques.

Effect of the background solution and material composition on the transport of silver nanoparticles in saturated aquifer materials

NASA Astrophysics Data System (ADS)

Adrian, Yorck; Schneidewind, Uwe; Fernandez-Steeger, Tomas; Azzam, Rafig

2016-04-01

Engineered silver nanoparticles (AgNP) are used in various consumer products such as cloth or personal care products due to their antimicrobial properties (Benn et al., 2010). Their transport behavior in the environment is still under investigation. Previous studies have been focusing on the transport of AgNP in simple test systems with glass beads or soil materials (Braun et al., 2015), but studies investigating aquifer material are rare. However, the protection of fresh water resources in the subsurface is an important part in the protection of human health and the assurance of future economic activities. Therefore, expert knowledge regarding the transport and fate of engineered nanoparticles as potential contaminants in aquifers is essential. Within the scope of the research project NanoMobil funded by German Federal Ministry of Education and Research, the transport and retention behavior of AgNP in aquifer material was investigated under saturated conditions in laboratory columns for different flow velocities, ionic strengths (IS) and background solutions. The used aquifer material consisted mainly of quartz and albite. The quartz grains were partially coated with iron hydroxides and oxides. Furthermore, 1% hematite was present in the silicate dominated aquifer material. The experiments were conducted using NaNO3 and Ca(NO3)2 background solutions to examine the effects of monovalent and divalent cations on the transport of AgNP. Flow velocities in the columns were chosen to represent typical flow velocities of groundwater in the subsurface. For the experiments two mean grain sizes of 0.3 and 0.7 mm were used to investigate the effect of the grain size on the transport behavior. Particle concentration was measured using ICP-MS and particle size was determined using flow field-flow fractionation (FlFFF). HYDRUS-1D (Šimůnek et al., 2013) was used to elucidate the transport and retention processes of the AgNP in the aquifer material. The obtained results show

Carbonate aquifers

USGS Publications Warehouse

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.

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

NASA Astrophysics Data System (ADS)

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

Stratigraphy of the unsaturated zone and the Snake River Plain aquifer at and near the Idaho National Engineering Laboratory, Idaho

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, S.R.; Liszewski, M.J.

1997-08-01

The unsaturated zone and the Snake River Plain aquifer at and near the Idaho National Engineering Laboratory (INEL) are made up of at least 178 basalt-flow groups, 103 sedimentary interbeds, 6 andesite-flow groups, and 4 rhyolite domes. Stratigraphic units identified in 333 wells in this 890-mile{sup 2} area include 121 basalt-flow groups, 102 sedimentary interbeds, 6 andesite-flow groups, and 1 rhyolite dome. Stratigraphic units were identified and correlated using the data from numerous outcrops and 26 continuous cores and 328 natural-gamma logs available in December 1993. Basalt flows make up about 85% of the volume of deposits underlying the area.

Herbicide Leaching Column for a Weed Science Teaching Laboratory.

ERIC Educational Resources Information Center

Ahrens, W. H.

1986-01-01

Presents an experiment which enables weed science students to observe first-hand the process of herbicide leaching in soils. Features of this technique which demonstrate the movement of herbicide within a column of soil are outlined. Diagrams are provided of the apparatus employed in the exercise. (ML)

Laboratory column experiments and transport modeling to evaluate retardation of uranium in an aquifer downgradient of a uranium in-situ recovery site

DOE PAGES

Dangelmayr, Martin A.; Reimus, Paul W.; Wasserman, Naomi L.; ...

2017-05-01

The purpose of this study was to determine the attenuation potential and retardation of uranium in sediments taken from boreholes at the Smith-Ranch Highland in-situ recovery (ISR) site. Five column experiments with four different sediments were conducted to study the effects of variable mineralogy and alkalinity on uranium breakthrough. Uranium transport was modeled with PHREEQC using a generalized composite surface complexation model (GC SCM) with one, two, and, three generic surfaces, respectively. Reactive surface areas were approximated with PEST using BET derived surface areas to constrain fitting parameters. Uranium breakthrough was delayed by a factor of 1.68, 1.69 and 1.47more » relative to the non-reactive tracer for three of the 5 experiments at an alkalinity of 540 mg/l. A sediment containing smectite and kaolinite retained uranium by a factor of 2.80 despite a lower measured BET surface area. Decreasing alkalinity to 360 mg/l from 540 mg/l increased retardation by a factor of 4.26. Model fits correlated well to overall BET surface area in the three columns where clay content was less than 1%. For the sediment with clay, models consistently understated uranium retardation when reactive surface sites were restricted by BET results. Calcite saturation was shown to be a controlling factor for uranium desorption as the pH of the system changes. A pH of 6 during a secondary background water flush remobilized previously sorbed uranium resulting in a secondary uranium peak at twice the influent concentrations. Furthermore, this study demonstrates the potential of GC SCM models to predict uranium transport in sediments with homogenous mineral composition, but highlights the need for further research to understand the role of sediment clay composition and calcite saturation in uranium transport.« less

Laboratory column experiments and transport modeling to evaluate retardation of uranium in an aquifer downgradient of a uranium in-situ recovery site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dangelmayr, Martin A.; Reimus, Paul W.; Wasserman, Naomi L.

The purpose of this study was to determine the attenuation potential and retardation of uranium in sediments taken from boreholes at the Smith-Ranch Highland in-situ recovery (ISR) site. Five column experiments with four different sediments were conducted to study the effects of variable mineralogy and alkalinity on uranium breakthrough. Uranium transport was modeled with PHREEQC using a generalized composite surface complexation model (GC SCM) with one, two, and, three generic surfaces, respectively. Reactive surface areas were approximated with PEST using BET derived surface areas to constrain fitting parameters. Uranium breakthrough was delayed by a factor of 1.68, 1.69 and 1.47more » relative to the non-reactive tracer for three of the 5 experiments at an alkalinity of 540 mg/l. A sediment containing smectite and kaolinite retained uranium by a factor of 2.80 despite a lower measured BET surface area. Decreasing alkalinity to 360 mg/l from 540 mg/l increased retardation by a factor of 4.26. Model fits correlated well to overall BET surface area in the three columns where clay content was less than 1%. For the sediment with clay, models consistently understated uranium retardation when reactive surface sites were restricted by BET results. Calcite saturation was shown to be a controlling factor for uranium desorption as the pH of the system changes. A pH of 6 during a secondary background water flush remobilized previously sorbed uranium resulting in a secondary uranium peak at twice the influent concentrations. Furthermore, this study demonstrates the potential of GC SCM models to predict uranium transport in sediments with homogenous mineral composition, but highlights the need for further research to understand the role of sediment clay composition and calcite saturation in uranium transport.« less

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

NASA Astrophysics Data System (ADS)

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

2014-05-01

continuous quantitative monitoring of the unsaturated zone through the entire soil column down to significant depths below the SAT basin. The above technique will offer continuous monitoring of infiltration rates and possible mechanical clogging effects. The qualitative monitoring of the unsaturated zone will be achieved through the installation of appropriate pore-water samplers within a multi-level basis, ensuring repeatability of sampling of infiltrating water of impaired quality. This study also involves the qualitative and quantitative assessment of the Lavrion multi-aquifer system through continuous monitoring of the performance of (i) the alluvial aquifer and its potential for additional water treatment as well as (ii) the effects of the SAT system for countermeasuring seawater intrusion in the area of Lavrion. Additionally, setup and calibration of numerical flow and transport models for evaluating and optimizing different operational modes of the SAT system within both saturated and unsaturated zones will be conducted. The monitoring system will be connected to an ad-hoc wireless network for continuous data transfer within the SAT facilities. It is envisaged that the development and combined application of all the above technologies will provide an integrated monitoring platform for the evaluation of SAT system performance.

Hydrogeology of the surficial and intermediate aquifer systems in Sarasota and adjacent counties, Florida

USGS Publications Warehouse

Barr, G.L.

1996-01-01

From 1991 to 1995, the hydrogeology of the surficial aquifer system and the major permeable zones and confining units of the intermediate aquifer system in southwest Florida was studied. The study area is a 1,400-square-mile area that includes Sarasota County and parts of Manatee, De Soto, Charlotte, and Lee Counties. Lithologic, geophysical, hydraulic property, and water-level data were used to correlate the hydrogeology and map the extent of the aquifer systems. Water chemistry was evaluated in southwest Sarasota County to determine salinity of the surficial and intermediate aquifer systems. The surficial aquifer is an unconfined aquifer system that overlies the intermediate aquifer system and ranges from a few feet to over 60 feet in thickness in the study area. Hydraulic properties of the surficial aquifer system determined from aquifer and laboratory tests, and model simulations vary considerably across the study area. The intermediate aquifer system, a confined aquifer system that lies between the surficial and the Upper Floridan aquifers, is composed of alternating confining units and permeable zones. The intermediate aquifer system has three major permeable zones that exhibit a wide range of hydraulic properties. Horizontal flow in the intermediate aquifer system is northeast to southwest. Most of the study area is in a discharge area of the intermediate aquifer system. Water ranges naturally from fresh in the surficial aquifer system and upper permeable zones of the intermediate aquifer system to moderately saline in the lower permeable zone. Water-quality data collected in coastal southwest Sarasota County indicate that ground-water withdrawals from major pumping centers have resulted in lateral seawater intrusion and upconing into the surficial and intermediate aquifer systems.

Aquifer-nomenclature guidelines

USGS Publications Warehouse

Laney, R.L.; Davidson, C.B.

1986-01-01

Guidelines and recommendations for naming aquifers are presented to assist authors of geohydrological reports in the United States Geological Survey, Water Resources Division. The hierarchy of terms that is used for water- yielding rocks from largest to smallest is aquifer system, aquifer, and zone. If aquifers are named, the names should be derived from lithologic terms, rock-stratigraphic units, or geographic names. The following items are not recommended as sources of aquifer names: time-stratigraphic names, relative position, alphanumeric designations, depositional environment, depth of occurrence, acronyms, and hydrologic conditions. Confining units should not be named unless doing so clearly promotes understanding of a particular aquifer system. Sources of names for confining units are similar to those for aquifer names, i.e. lithologic terms, rock-stratigraphic units or geographic names. Examples of comparison charts and tables that are used to define the geohydrologic framework are included. Aquifers are defined in 11 hypothetical examples that characterize geohydrologic settings throughout the country. (Author 's abstract)

Stratigraphy of the unsaturated zone and uppermost part of the Snake River Plain aquifer at test area north, Idaho National Engineering Laboratory, Idaho

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, S.R.; Bowers, B.

1995-06-01

A complex sequence of basalt flows and sedimentary interbeds underlies Test Area North (TAN) at the Idaho National Engineering Laboratory in eastern Idaho. Wells drilled to depths of at least 500 feet penetrate 10 basalt-flow groups and 5 to 10 sedimentary interbeds that range in age from about 940,000 to 1.4 million years. Each basalt-flow group consists of one or more basalt flows from a brief, single or compound eruption. All basalt flows of each group erupted from the same vent, and have similar ages, paleomagnetic properties, potassium contents, and natural-gamma emissions. Sedimentary interbeds consist of fluvial, lacustrine, and eolianmore » deposits of clay, silt, sand, and gravel that accumulated for hundreds to hundreds of thousands of years during periods of volcanic quiescence. Basalt and sediment are elevated by hundreds of feet with respect to rocks of equivalent age south and cast of the area, a relation that is attributed to past uplift at TAN. Basalt and sediment are unsaturated to a depth of about 200 feet below land surface. Rocks below this depth are saturated and make up the Snake River Plain aquifer. The effective base of the aquifer is at a depth of 885 feet below land surface. Detailed stratigraphic relations for the lowermost part of the aquifer in the depth interval from 500 to 885 feet were not determined because of insufficient data. The stratigraphy of basalt-flow groups and sedimentary interbeds in the upper 500 feet of the unsaturated zone and aquifer was determined from natural-gamma logs, lithologic logs, and well cores. Basalt cores were evaluated for potassium-argon ages, paleomagnetic properties, petrographic characteristics, and chemical composition. Stratigraphic control was provided by differences in ages, paleomagnetic properties, potassium content, and natural-gamma emissions of basalt-flow groups and sedimentary interbeds.« less

Laboratory-Scale Column Testing Using IONSIV IE-911 for Removing Cesium from Acidic Tank Waste Simulant. 1: Cesium Exchange Capacity of a 15-cm3 Column and Dynamic Stability of the Exchange Media

DOE Office of Scientific and Technical Information (OSTI.GOV)

T.J. Tranter; R.D. Tillotson; T.A. Todd

2005-04-01

Bench-scale column tests were performed using a commercial form of crystalline silicotitanate (CST) for removing radio-cesium from a surrogate acidic tank solution representative of liquid waste stored at the Idaho National Engineering and Environmental Laboratory (INEEL). An engineered form of CST ion exchanger, known as IONSIVtm IE-911 (UOP, Mt Laurel, NJ, USA), was tested in 15 cm3 columns at a flow rate of 5 bed volumes per hour. These experiments showed the ion exchange material to have reasonable selectivity and capacity for removing cesium from the complex chemical matrix of the solution. However, previous testing indicated that partial neutralization ofmore » the feed stream was necessary to increase the stability of the ion exchange media. Thus, in these studies, CST degradation was determined as a function of throughput in order to better assess the stability characteristics of the exchanger for potential future waste treatment applications. Results of these tests indicate that the degradation of the CST reaches a maximum very soon after the acidic feed is introduced to the column and then rapidly declines. Total dissolution of bed material did not exceed 3% under the experimental regime used.« less

Simulating the 2012 High Plains Drought Using Three Single Column Models (SCM)

NASA Astrophysics Data System (ADS)

Medina, I. D.; Baker, I. T.; Denning, S.; Dazlich, D. A.

2015-12-01

The impact of changes in the frequency and severity of drought on fresh water sustainability is a great concern for many regions of the world. One such location is the High Plains, where the local economy is primarily driven by fresh water withdrawals from the Ogallala Aquifer, which accounts for approximately 30% of total irrigation withdrawals from all U.S. aquifers combined. Modeling studies that focus on the feedback mechanisms that control the climate and eco-hydrology during times of drought are limited, and have used conventional General Circulation Models (GCMs) with grid length scales ranging from one hundred to several hundred kilometers. Additionally, these models utilize crude statistical parameterizations of cloud processes for estimating sub-grid fluxes of heat and moisture and have a poor representation of land surface heterogeneity. For this research, we focus on the 2012 High Plains drought and perform numerical simulations using three single column model (SCM) versions of BUGS5 (Colorado State University (CSU) GCM coupled to the Simple Biosphere Model (SiB3)). In the first version of BUGS5, the model is used in its standard bulk setting (single atmospheric column coupled to a single instance of SiB3), secondly, the Super-Parameterized Community Atmospheric Model (SP-CAM), a cloud resolving model (CRM) (CRM consists of 32 atmospheric columns), replaces the single CSU GCM atmospheric parameterization and is coupled to a single instance of SiB3, and for the third version of BUGS5, an instance of SiB3 is coupled to each CRM column of the SP-CAM (32 CRM columns coupled to 32 instances of SiB3). To assess the physical realism of the land-atmosphere feedbacks simulated by all three versions of BUGS5, differences in simulated energy and moisture fluxes are computed between the 2011 and 2012 period and are compared to those calculated using observational data from the AmeriFlux Tower Network for the same period at the ARM Site in Lamont, OK. This research

Iodine-129 in the eastern Snake River Plain aquifer at and near the Idaho National Laboratory, Idaho, 2010-12

USGS Publications Warehouse

Bartholomay, Roy C.

2013-01-01

From 1953 to 1988, approximately 0.941 curies of iodine-129 (129I) were contained in wastewater generated at the Idaho National Laboratory (INL) with almost all of this wastewater discharged at or near the Idaho Nuclear Technology and Engineering Center (INTEC). Most of the wastewater containing 129I was discharged directly into the eastern Snake River Plain (ESRP) aquifer through a deep disposal well until 1984; lesser quantities also were discharged into unlined infiltration ponds or leaked from distribution systems below the INTEC. During 2010–12, the U.S. Geological Survey in cooperation with the U.S. Department of Energy collected groundwater samples for 129I from 62 wells in the ESRP aquifer to track concentration trends and changes for the carcinogenic radionuclide that has a 15.7 million-year half-life. Concentrations of 129I in the aquifer ranged from 0.0000013±0.0000005 to 1.02±0.04 picocuries per liter (pCi/L), and generally decreased in wells near the INTEC, relative to previous sampling events. The average concentration of 129I in groundwater from 15 wells sampled during four different sample periods decreased from 1.15 pCi/L in 1990–91 to 0.173 pCi/L in 2011–12. All but two wells within a 3-mile radius of the INTEC showed decreases in concentration, and all but one sample had concentrations less than the U.S. Environmental Protection Agency maximum contaminant level of 1 pCi/L. These decreases are attributed to the discontinuation of disposal of 129I in wastewater and to dilution and dispersion in the aquifer. The decreases in 129I concentrations, in areas around INTEC where concentrations increased between 2003 and 2007, were attributed to less recharge near INTEC either from less flow in the Big Lost River or from less local snowmelt and anthropogenic sources. Although wells near INTEC sampled in 2011–12 showed decreases in 129I concentrations compared with previously collected data, some wells south and east of the Central Facilities Area

Fate of five pharmaceuticals under different infiltration conditions for managed aquifer recharge.

PubMed

Silver, Matthew; Selke, Stephanie; Balsaa, Peter; Wefer-Roehl, Annette; Kübeck, Christine; Schüth, Christoph

2018-06-18

Infiltration of treated wastewater (TWW) to recharge depleted aquifers, often referred to as managed aquifer recharge, is a solution to replenish groundwater resources in regions facing water scarcity. We present a mass balance approach to infer the amounts of five pharmaceuticals (carbamazepine, diclofenac, fenoprofen, gemfibrozil, and naproxen) degraded in column experiments based on concentrations of pharmaceuticals in the aqueous and solid (sorbed) phases. Column experiments were conducted under three different conditions: continuous infiltration, wetting and drying cycles, and wetting and drying cycles with elevated concentrations of antibiotics (which may reduce microbially aided degradation of other compounds). A mass balance comparing pharmaceutical mass in the water phase over the 16-month duration of the experiments to mass sorbed to the soil was used to infer the mass of pharmaceuticals degraded. Results show sorption as the main attenuation mechanism for carbamazepine. About half of the mass of diclofenac was degraded with wetting and drying cycles, but no significant degradation was found for continuous infiltration, while 32% of infiltrated mass sorbed. Fenoprofen was degraded in the shallow and aerobic part of the soil, but degradation appeared to cease beyond 27 cm depth. Gemfibrozil attenuated through a combination of degradation and sorption, with slight increases in attenuation with depth from both mechanisms. Naproxen degraded progressively with depth, resulting in attenuation of >90% of the mass. In the column with elevated concentrations of antibiotics, the antibiotics attenuated to about 50% or less of inflow concentrations by 27 cm depth and within this zone, less degradation of the other compounds was observed. Copyright © 2018 Elsevier B.V. All rights reserved.

Simulation of ground-water flow in the Intermediate and Floridan aquifer systems in Peninsular Florida

USGS Publications Warehouse

Sepúlveda, Nicasio

2002-01-01

A numerical model of the intermediate and Floridan aquifer systems in peninsular Florida was used to (1) test and refine the conceptual understanding of the regional ground-water flow system; (2) develop a data base to support subregional ground-water flow modeling; and (3) evaluate effects of projected 2020 ground-water withdrawals on ground-water levels. The four-layer model was based on the computer code MODFLOW-96, developed by the U.S. Geological Survey. The top layer consists of specified-head cells simulating the surficial aquifer system as a source-sink layer. The second layer simulates the intermediate aquifer system in southwest Florida and the intermediate confining unit where it is present. The third and fourth layers simulate the Upper and Lower Floridan aquifers, respectively. Steady-state ground-water flow conditions were approximated for time-averaged hydrologic conditions from August 1993 through July 1994 (1993-94). This period was selected based on data from Upper Floridan a quifer wells equipped with continuous water-level recorders. The grid used for the ground-water flow model was uniform and composed of square 5,000-foot cells, with 210 columns and 300 rows.

Impact of material heterogeneity on solute transport behavior in the unsaturated zone of the Calcaire de Beauce aquifer (France)

NASA Astrophysics Data System (ADS)

Viel, Emelie; Coquet, Yves

2016-04-01

Since a few decades, the Calcaire de Beauce aquifer is contaminated with nitrate. The nitrate dynamics in the aquifer and in the surface soil are quite well understood, but its transport through the vadose zone remains largely unknown. When models fail to simulate nitrate concentrations in wells, preferential flow or physical non-equilibrium transport in soil and in the vadose zone is usually put forward to explain this failure. To study transport processes in the vadose zone of the Calcaire de Beauce aquifer, undisturbed cores (30 cm length and 20 cm diameter) have been taken below the deepest soil horizon. At the field scale, the vadose zone is composed of powdery limestone spatially very heterogeneous, and including a variable amount of coarse elements. Two columns were selected: column "6" is made of very fine homogeneous limestone whereas column "8" is very heterogeneous with a large proportion of coarse elements. Elution experiments have been performed on both columns. A tracer (Br- or DFBA) in a solution of 5 mM CaCl2 was spread as a pulse on the top of the column with a rainfall simulator. Input flow rate was kept constant for steady state cases, or suddenly closed for flux interruption cases. Outflow was collected as a function of time for tracer concentration measurement. The collected fractions were analyzed by HPLC (High-performance liquid chromatography) with a UV detector. Three types of experiments took place: • For steady state experiments, three rainfall rates, respectively 4, 8, and 16 mm/h, have been used to study the occurrence of immobile water in the columns. The tracer was injected during 120 min followed by CaCl2 tracer-free solution at same flow rate. • For flux-interruption experiments, only the 4 and 8 mm/h rainfall rates were used. The tracer was injected during 120 min, input and output fluxes were then stopped and restarted seven days later with the same flow rate. • For drainage experiments, only the 4 and 8 mm/h rainfall rates

Arsenic release from Floridan Aquifer rock during incubations simulating aquifer storage and recovery operations.

PubMed

Jin, Jin; Zimmerman, Andrew R; Norton, Stuart B; Annable, Michael D; Harris, Willie G

2016-05-01

While aquifer storage and recovery (ASR) is becoming widely accepted as a way to address water supply shortages, there are concerns that it may lead to release of harmful trace elements such as arsenic (As). Thus, mechanisms of As release from limestone during ASR operations were investigated using 110-day laboratory incubations of core material collected from the Floridan Aquifer, with treatment additions of labile or refractory dissolved organic matter (DOM) or microbes. During the first experimental phase, core materials were equilibrated with native groundwater lacking in DO to simulate initial non-perturbed anaerobic aquifer conditions. Then, ASR was simulated by replacing the native groundwater in the incubations vessels with DO-rich ASR source water, with DOM or microbes added to some treatments. Finally, the vessels were opened to the atmosphere to mimic oxidizing conditions during later stages of ASR. Arsenic was released from aquifer materials, mainly during transitional periods at the beginning of each incubation stage. Most As released was during the initial anaerobic experimental phase via reductive dissolution of Fe oxides in the core materials, some or all of which may have formed during the core storage or sample preparation period. Oxidation of As-bearing Fe sulfides released smaller amounts of As during the start of later aerobic experimental phases. Additions of labile DOM fueled microbially-mediated reactions that mobilized As, while the addition of refractory DOM did not, probably due to mineral sorption of DOM that made it unavailable for microbial utilization or metal chelation. The results suggest that oscillations of groundwater redox conditions, such as might be expected to occur during an ASR operation, are the underlying cause of enhanced As release in these systems. Further, ASR operations using DOM-rich surface waters may not necessarily lead to additional As releases. Copyright © 2016 Elsevier B.V. All rights reserved.

Putting aquifers into atmospheric simulation models: An example from the Mill Creek Watershed, Northeastern Kansas

USGS Publications Warehouse

York, J.P.; Person, M.; Gutowski, W.J.; Winter, T.C.

2002-01-01

Aquifer-atmosphere interactions can be important in regions where the water table is shallow (<2 m). A shallow water table provides moisture for the soil and vegetation and thus acts as a source term for evapotranspiration to the atmosphere. A coupled aquifer-land surface-atmosphere model has been developed to study aquifer-atmosphere interactions in watersheds, on decadal timescales. A single column vertically discretized atmospheric model is linked to a distributed soil-vegetation-aquifer model. This physically based model was able to reproduce monthly and yearly trends in precipitation, stream discharge, and evapotranspiration, for a catchment in northeastern Kansas. However, the calculated soil moisture tended to drop to levels lower than were observed in drier years. The evapotranspiration varies spatially and seasonally and was highest in cells situated in topographic depressions where the water table is in the root zone. Annually, simulation results indicate that from 5-20% of groundwater supported evapotranspiration is drawn from the aquifer. The groundwater supported fraction of evapotranspiration is higher in drier years, when evapotranspiration exceeds precipitation. A long-term (40 year) simulation of extended drought conditions indicated that water table position is a function of groundwater hydrodynamics and cannot be predicted solely on the basis of topography. The response time of the aquifer to drought conditions was on the order of 200 years indicating that feedbacks between these two water reservoirs act on disparate time scales. With recent advances in the computational power of massively parallel supercomputers, it may soon become possible to incorporate physically based representations of aquifer hydrodynamics into general circulation models (GCM) land surface parameterization schemes. ?? 2002 Elsevier Science Ltd. All rights reserved.

Steady-state and transient models of groundwater flow and advective transport, Eastern Snake River Plain aquifer, Idaho National Laboratory and vicinity, Idaho

USGS Publications Warehouse

Ackerman, Daniel J.; Rousseau, Joseph P.; Rattray, Gordon W.; Fisher, Jason C.

2010-01-01

Three-dimensional steady-state and transient models of groundwater flow and advective transport in the eastern Snake River Plain aquifer were developed by the U.S. Geological Survey in cooperation with the U.S. Department of Energy. The steady-state and transient flow models cover an area of 1,940 square miles that includes most of the 890 square miles of the Idaho National Laboratory (INL). A 50-year history of waste disposal at the INL has resulted in measurable concentrations of waste contaminants in the eastern Snake River Plain aquifer. Model results can be used in numerical simulations to evaluate the movement of contaminants in the aquifer. Saturated flow in the eastern Snake River Plain aquifer was simulated using the MODFLOW-2000 groundwater flow model. Steady-state flow was simulated to represent conditions in 1980 with average streamflow infiltration from 1966-80 for the Big Lost River, the major variable inflow to the system. The transient flow model simulates groundwater flow between 1980 and 1995, a period that included a 5-year wet cycle (1982-86) followed by an 8-year dry cycle (1987-94). Specified flows into or out of the active model grid define the conditions on all boundaries except the southwest (outflow) boundary, which is simulated with head-dependent flow. In the transient flow model, streamflow infiltration was the major stress, and was variable in time and location. The models were calibrated by adjusting aquifer hydraulic properties to match simulated and observed heads or head differences using the parameter-estimation program incorporated in MODFLOW-2000. Various summary, regression, and inferential statistics, in addition to comparisons of model properties and simulated head to measured properties and head, were used to evaluate the model calibration. Model parameters estimated for the steady-state calibration included hydraulic conductivity for seven of nine hydrogeologic zones and a global value of vertical anisotropy. Parameters

Application of a Fast Separation Method for Anti-diabetics in Pharmaceuticals Using Monolithic Column: Comparative Study With Silica Based C-18 Particle Packed Column.

PubMed

Hemdan, A; Abdel-Aziz, Omar

2018-04-01

Run time is a predominant factor in HPLC for quality control laboratories especially if there is large number of samples have to be analyzed. Working at high flow rates cannot be attained with silica based particle packed column due to elevated backpressure issues. The use of monolithic column as an alternative to traditional C-18 column was tested for fast separation of pharmaceuticals, where the results were very competitive. The performance comparison of both columns was tested for separation of anti-diabetic combination containing Metformin, Pioglitazone and Glimepiride using Gliclazide as an internal standard. Working at high flow rates with less significant backpressure was obtained with the monolithic column where the run time was reduced from 6 min in traditional column to only 1 min in monolithic column with accepted resolution. The structure of the monolith contains many pores which can adapt the high flow rate of the mobile phase. Moreover, peak symmetry and equilibration time were more efficient with monolithic column.

Using Artificial Soil and Dry-Column Flash Chromatography to Simulate Organic Substance Leaching Process: A Colorful Environmental Chemistry Experiment

ERIC Educational Resources Information Center

de Avellar, Isa G. J.; Cotta, Tais A. P. G.; Neder, Amarilis de V. Finageiv

2012-01-01

Soil is an important and complex environmental compartment and soil contamination contributes to the pollution of aquifers and other water basins. A simple and low-cost experiment is described in which the mobility of three organic compounds in an artificial soil is examined using dry-column flash chromatography. The compounds were applied on top…

Determining the Influence of Groundwater Composition on the Performance of Arsenic Adsorption Columns Using Rapid Small-Scale Column Tests

NASA Astrophysics Data System (ADS)

Aragon, A. R.; Siegel, M.

2004-12-01

The USEPA has established a more stringent drinking water standard for arsenic, reducing the maximum contaminant level (MCL) from 50 μ g/L to 10 μ g/L. This will affect many small communities in the US that lack the appropriate treatment infrastructure and funding to reduce arsenic to such levels. For such communities, adsorption systems are the preferred technology based on ease of operation and relatively lower costs. The performance of adsorption media for the removal of arsenic from drinking water is dependent on site-specific water quality. At certain concentrations, co-occurring solutes will compete effectively with arsenic for sorption sites, potentially reducing the sorption capacity of the media. Due to the site-specific nature of water quality and variations in media properties, pilot scale studies are typically carried out to ensure that a proposed treatment technique is cost effective before installation of a full-scale system. Sandia National Laboratories is currently developing an approach to utilize rapid small-scale columns in lieu of pilot columns to test innovative technologies that could significantly reduce the cost of treatment in small communities. Rapid small-scale column tests (RSSCTs) were developed to predict full-scale treatment of organic contaminants by adsorption onto granular activated carbon (GAC). This process greatly reduced the time and costs required to verify performance of GAC adsorption columns. In this study, the RSSCT methodology is used to predict the removal of inorganic arsenic using mixed metal oxyhydroxide adsorption media. The media are engineered and synthesized from materials that control arsenic behavior in natural and disturbed systems. We describe the underlying theory and application of RSSCTs for the performance evaluation of novel media in several groundwater compositions. Results of small-scale laboratory columns are being used to predict the performance of pilot-scale systems and ultimately to design full

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

USGS Publications Warehouse

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

1995-01-01

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

Molecular Analysis of Microbial Community Structures in Pristine and Contaminated Aquifers: Field and Laboratory Microcosm Experiments

PubMed Central

Shi, Y.; Zwolinski, M. D.; Schreiber, M. E.; Bahr, J. M.; Sewell, G. W.; Hickey, W. J.

1999-01-01

This study used phylogenetic probes in hybridization analysis to (i) determine in situ microbial community structures in regions of a shallow sand aquifer that were oxygen depleted and fuel contaminated (FC) or aerobic and noncontaminated (NC) and (ii) examine alterations in microbial community structures resulting from exposure to toluene and/or electron acceptor supplementation (nitrate). The latter objective was addressed by using the NC and FC aquifer materials for anaerobic microcosm studies in which phylogenetic probe analysis was complemented by microbial activity assays. Domain probe analysis of the aquifer samples showed that the communities were predominantly Bacteria; Eucarya and Archaea were not detectable. At the phylum and subclass levels, the FC and NC aquifer material had similar relative abundance distributions of 43 to 65% β- and γ-Proteobacteria (B+G), 31 to 35% α-Proteobacteria (ALF), 15 to 18% sulfate-reducing bacteria, and 5 to 10% high G+C gram positive bacteria. Compared to that of the NC region, the community structure of the FC material differed mainly in an increased abundance of B+G relative to that of ALF. The microcosm communities were like those of the field samples in that they were predominantly Bacteria (83 to 101%) and lacked detectable Archaea but differed in that a small fraction (2 to 8%) of Eucarya was detected regardless of the treatment applied. The latter result was hypothesized to reflect enrichment of anaerobic protozoa. Addition of nitrate and/or toluene stimulated microbial activity in the microcosms, but only supplementation of toluene alone significantly altered community structures. For the NC material, the dominant subclass shifted from B+G to ALF, while in the FC microcosms 55 to 65% of the Bacteria community was no longer identifiable by the phylum or subclass probes used. The latter result suggested that toluene exposure fostered the proliferation of phylotype(s) that were otherwise minor constituents of the

Reproducibility of up-flow column percolation tests for contaminated soils

PubMed Central

Naka, Angelica; Sakanakura, Hirofumi; Kurosawa, Akihiko; Inui, Toru; Takeo, Miyuki; Inoba, Seiji; Watanabe, Yasutaka; Fujikawa, Takuro; Miura, Toshihiko; Miyaguchi, Shinji; Nakajou, Kunihide; Sumikura, Mitsuhiro; Ito, Kenichi; Tamoto, Shuichi; Tatsuhara, Takeshi; Chida, Tomoyuki; Hirata, Kei; Ohori, Ken; Someya, Masayuki; Katoh, Masahiko; Umino, Madoka; Negishi, Masanori; Ito, Keijiro; Kojima, Junichi; Ogawa, Shohei

2017-01-01

Up-flow column percolation tests are used at laboratory scale to assess the leaching behavior of hazardous substance from contaminated soils in a specific condition as a function of time. Monitoring the quality of these test results inter or within laboratory is crucial, especially if used for Environment-related legal policy or for routine testing purposes. We tested three different sandy loam type soils (Soils I, II and III) to determine the reproducibility (variability inter laboratory) of test results and to evaluate the difference in the test results within laboratory. Up-flow column percolation tests were performed following the procedure described in the ISO/TS 21268–3. This procedure consists of percolating solution (calcium chloride 1 mM) from bottom to top at a flow rate of 12 mL/h through softly compacted soil contained in a column of 5 cm diameter and 30 ± 5 cm height. Eluate samples were collected at liquid-to-solid ratio of 0.1, 0.2, 0.5, 1, 2, 5 and 10 L/kg and analyzed for quantification of the target elements (Cu, As, Se, Cl, Ca, F, Mg, DOC and B in this research). For Soil I, 17 institutions in Japan joined this validation test. The up-flow column experiments were conducted in duplicate, after 48 h of equilibration time and at a flow rate of 12 mL/h. Column percolation test results from Soils II and III were used to evaluate the difference in test results from the experiments conducted in duplicate in a single laboratory, after 16 h of equilibration time and at a flow rate of 36 mL/h. Overall results showed good reproducibility (expressed in terms of the coefficient of variation, CV, calculated by dividing the standard deviation by the mean), as the CV was lower than 30% in more than 90% of the test results associated with Soil I. Moreover, low variability (expressed in terms of difference between the two test results divided by the mean) was observed in the test results related to Soils II and III, with a variability lower than 30% in more

Reactions and reaction rates in the regional aquifer beneath the Pajarito Plateau, north-central New Mexico, USA

NASA Astrophysics Data System (ADS)

Hereford, Anne G.; Keating, Elizabeth H.; Guthrie, George D.; Zhu, Chen

2007-05-01

Reactions and reaction rates within aquifers are fundamental components of critical hydrological processes. However, reactions simulated in laboratory experiments typically demonstrate rates that are much faster than those observed in the field. Therefore, it is necessary to conduct more reaction rate analyses in natural settings. This study of geochemical reactions in the regional aquifer in the Pajarito Plateau near Los Alamos, New Mexico combines modeling with petrographic assessment to further knowledge and understanding of complex natural hydrologic systems. Groundwater geochemistry shows marked evolution along assumed flow paths. The flow path chosen for this study was evaluated using inverse mass balance modeling to calculate the mass transfer. X-ray diffraction and field emission gun scanning electron microscopy were used to identify possible reactants and products. Considering the mineralogy of the aquifer and saturation indices for the regional water refined initial interpretations. Calculations yielded dissolution rates for plagioclase on the order of 10-15 mol s-1 m-2 and for K-feldspar on the order of 10-17 mol s-1 m-2, orders of magnitude slower than laboratory rates. While these rates agree with other aquifer studies, they must be considered in the light of the uncertainty associated with geometric surface area estimates, 14C ages, and aquifer properties.

Column-to-column packing variation of disposable pre-packed columns for protein chromatography.

PubMed

Schweiger, Susanne; Hinterberger, Stephan; Jungbauer, Alois

2017-12-08

In the biopharmaceutical industry, pre-packed columns are the standard for process development, but they must be qualified before use in experimental studies to confirm the required performance of the packed bed. Column qualification is commonly done by pulse response experiments and depends highly on the experimental testing conditions. Additionally, the peak analysis method, the variation in the 3D packing structure of the bed, and the measurement precision of the workstation influence the outcome of qualification runs. While a full body of literature on these factors is available for HPLC columns, no comparable studies exist for preparative columns for protein chromatography. We quantified the influence of these parameters for commercially available pre-packed and self-packed columns of disposable and non-disposable design. Pulse response experiments were performed on 105 preparative chromatography columns with volumes of 0.2-20ml. The analyte acetone was studied at six different superficial velocities (30, 60, 100, 150, 250 and 500cm/h). The column-to-column packing variation between disposable pre-packed columns of different diameter-length combinations varied by 10-15%, which was acceptable for the intended use. The column-to-column variation cannot be explained by the packing density, but is interpreted as a difference in particle arrangement in the column. Since it was possible to determine differences in the column-to-column performance, we concluded that the columns were well-packed. The measurement precision of the chromatography workstation was independent of the column volume and was in a range of±0.01ml for the first peak moment and±0.007 ml 2 for the second moment. The measurement precision must be considered for small columns in the range of 2ml or less. The efficiency of disposable pre-packed columns was equal or better than that of self-packed columns. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Field Investigation of Stream-Aquifer Interactions: A Case Study in Coastal California

NASA Astrophysics Data System (ADS)

Pritchard-Peterson, D.; Malama, B.

2017-12-01

We report here results of a detailed investigation of the dynamic interaction between a stream and an alluvial aquifer at Swanton Pacific Ranch in the Scotts Creek watershed, Santa Cruz County, California. The aquifer is an important source of groundwater for cropland irrigation and for aquatic ecosystem support. Low summer base flows in Scotts Creek are a source of serious concern for land managers, fisheries biologists, and regulatory agencies due to the presence of federally protected steelhead trout and coho salmon. An understanding of the interaction between the stream and pumped aquifer will allow for assessment of the impacts of groundwater extraction on stream flows and is essential to establishing minimum flow requirements. This will aid in the development of sustainable riparian groundwater pumping practices that meet agricultural and ecological needs. Results of extensive direct-push sampling of the subsurface, laboratory falling-head permeameter tests and particle size analysis of aquifer sediments, multi-day pumping tests, long-term passive monitoring of aquifer hydraulic heads and stream stage and discharge, and electrical resistivity interrogation of the subsurface are reported here. Findings indicate that the permeable subsurface formation tapped by irrigation wells is a leaky semi-confined aquifer, overlain by a thin low permeability layer of silt and clay above which lies Scotts Creek. These results are particularly useful to land managers responsible for groundwater abstraction from wells that tap into the aquifer. Additionally, an index of stream-aquifer connectivity is proposed that would allow land managers to conveniently modify groundwater abstraction practices, minimizing concerns of stream depletion.

Geochemical Impacts of Leaking CO2 from Subsurface Storage Reservoirs on the Fate of Metal Contaminants in an Overlaying Groundwater Aquifer

NASA Astrophysics Data System (ADS)

Shao, H.; Qafoku, N. P.; Lawter, A.; Bowden, M. E.; Brown, C. F.

2014-12-01

The leakage of CO2 and the concomitant upward transport of brine solutions and contaminants from deep storage reservoirs to overlaying groundwater aquifers is considered one of the major risks associated with geologic carbon sequestration (GCS). A systematic understanding of how such leakage would impact the geochemistry of potable aquifers is crucial to the maintenance of environmental quality and the widespread acceptance of GCS. A series of batch and column experiments studies were conducted to understand the fate (mobilization and immobilization) of trace metals, such as Cd and As in the groundwater aquifer after the intrusion of CO2 gas and CO2-saturated fluids containing leached metals from deep subsurface storage reservoirs. Sediments from the High Plains aquifer in Kansas, United States, were used in this investigation, which is part of the National Risk Assessment Partnership Program sponsored by the US DOE. This aquifer was selected to be representative of consolidated sand and gravel/sandstone aquifers overlying potential CO2 sequestration repositories within the continental US. The experiments were conducted at room temperature and atmospheric pressure. The results demonstrated that Cd and As that intrude into groundwater aquifers with the leaking CO2 at initial concentrations of 40 and 114 mg/L, respectively, will be adsorbed on the sediments, in spite of the acidic pH (between 5 and 6) due to CO2 dissolution in the groundwater. Cd concentrations were well below its MCL in both the aqueous solution of the batch study and the effluent of the column study, even for one of the sediment samples which had undetectable amount of carbonate minerals to buffer the pH. Arsenic concentrations were also significantly lower than that in the influent, suggesting that natural sediments have the capacity to mitigate the adverse effects of the CO2 leakage. However, the mitigation capacity of sediments is influenced by its geochemical properties. When there are anions

Sources of sulfate supporting anaerobic metabolism in a contaminated aquifer

USGS Publications Warehouse

Ulrich, G.A.; Breit, G.N.; Cozzarelli, I.M.; Suflita, J.M.

2003-01-01

Field and laboratory techniques were used to identify the biogeochemical factors affecting sulfate reduction in a shallow, unconsolidated alluvial aquifer contaminated with landfill leachate. Depth profiles of 35S-sulfate reduction rates in aquifer sediments were positively correlated with the concentration of dissolved sulfate. Manipulation of the sulfate concentration in samples revealed a Michaelis-Menten-like relationship with an apparent Km and Vmax of approximately 80 and 0.83 ??M SO4-2??day-1, respectively. The concentration of sulfate in the core of the leachate plume was well below 20 ??M and coincided with very low reduction rates. Thus, the concentration and availability of this anion could limit in situ sulfate-reducing activity. Three sulfate sources were identified, including iron sulfide oxidation, barite dissolution, and advective flux of sulfate. The relative importance of these sources varied with depth in the alluvium. The relatively high concentration of dissolved sulfate at the water table is attributed to the microbial oxidation of iron sulfides in response to fluctuations of the water table. At intermediate depths, barite dissolves in undersaturated pore water containing relatively high concentrations of dissolved barium (???100 ??M) and low concentrations of sulfate. Dissolution is consistent with the surface texture of detrital barite grains in contact with leachate. Laboratory incubations of unamended and barite-amended aquifer slurries supported the field observation of increasing concentrations of barium in solution when sulfate reached low levels. At a deeper highly permeable interval just above the confining bottom layer of the aquifer, sulfate reduction rates were markedly higher than rates at intermediate depths. Sulfate is supplied to this deeper zone by advection of uncontaminated groundwater beneath the landfill. The measured rates of sulfate reduction in the aquifer also correlated with the abundance of accumulated iron sulfide

PULSED AIR SPARGING IN AQUIFERS CONTAMINATED WITH DENSE NONAQUEOUS PHASE LIQUIDS

EPA Science Inventory

Air sparging was evaluated for remediation of tetrachloroethylene (PCE) present as dense nonaqueous phase liquid (DNAPL) in aquifers. A two-dimensional laboratory tank with a transparent front wall allowed for visual observation of DNAPL mobilization. A DNAPL zone 50 cm high was ...

Field and Laboratory Application of a Gas Chromatograph Low Thermal Mass Resistively Heated Column System in Detecting Traditional and Non-Traditional Chemical Warfare Agents Using Solid Phase Micro-Extraction

DTIC Science & Technology

2005-02-01

followed by extensive sample preparation procedures that are performed in a laboratory. Analysis is typically conducted by injecting a liquid or gas sample...Alfentanil, Remifentanil , Sufentanil, and Carfentanil) in a laboratory. (5) Quantitatively determine a maximum temperature ramping rate at which the LTM...RHT Column combined with a GC-MS can separate and analyze a mixture of non- traditional CWAs (i.e. Fentanyl, Alfentanil, Remifentanil , Sufentanil

Leaching Behavior Of Mineral Processing Waste: Comparison Of Batch And Column Investigations

EPA Science Inventory

In this study, a comparison of laboratory batch and column experiments on metal release profile from a mineral processing waste (MPW) is presented. Batch (equilibrium) and column (dynamic) leaching tests were conducted on ground MPW at different liquid–solid ratios (LS) to determ...

Fate of microbial metabolites of hydrocarbons in a coastal plain aquifer: The role of electron acceptors

USGS Publications Warehouse

Cozzarelli, I.M.; Herman, J.S.; Baedecker, M. Jo

1995-01-01

A combined field and laboratory study was undertaken to understand the distribution and geochemical conditions that influence the prevalence of low molecular weight organic acids in groundwater of a shallow aquifer contaminated with gasoline. Aromatic hydrocarbons from gasoline were degraded by microbially mediated oxidation-reduction reactions, including reduction of nitrate, sulfate, and Fe(III). The biogeochemical reactions changed overtime in response to changes in the hydrogeochemical conditions in the aquifer. Aliphatic and aromatic organic acids were associated with hydrocarbon degradation in anoxic zones of the aquifer. Laboratory microcosms demonstrated that the biogeochemical fate of specific organic acids observed in groundwater varied with the structure of the acid and the availability of electron acceptors. Benzoic and phenylacetic acid were degraded by indigenous aquifer microorganisms when nitrate was supplied as an electron acceptor. Aromatic acids with two or more methyl substituants on the benzene ring persisted under nitrate-reducing conditions. Although iron reduction and sulfate reduction were important processes in situ and occurred in the microcosms, these reactions were not coupled to the biological oxidation of aromatic organic acids that were added to the microcosms as electron donors. ?? 1995 American Chemical Society.

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

USGS Publications Warehouse

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

Development of a regional groundwater flow model for the area of the Idaho National Engineering Laboratory, Eastern Snake River Plain Aquifer

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCarthy, J.M.; Arnett, R.C.; Neupauer, R.M.

This report documents a study conducted to develop a regional groundwater flow model for the Eastern Snake River Plain Aquifer in the area of the Idaho National Engineering Laboratory. The model was developed to support Waste Area Group 10, Operable Unit 10-04 groundwater flow and transport studies. The products of this study are this report and a set of computational tools designed to numerically model the regional groundwater flow in the Eastern Snake River Plain aquifer. The objective of developing the current model was to create a tool for defining the regional groundwater flow at the INEL. The model wasmore » developed to (a) support future transport modeling for WAG 10-04 by providing the regional groundwater flow information needed for the WAG 10-04 risk assessment, (b) define the regional groundwater flow setting for modeling groundwater contaminant transport at the scale of the individual WAGs, (c) provide a tool for improving the understanding of the groundwater flow system below the INEL, and (d) consolidate the existing regional groundwater modeling information into one usable model. The current model is appropriate for defining the regional flow setting for flow submodels as well as hypothesis testing to better understand the regional groundwater flow in the area of the INEL. The scale of the submodels must be chosen based on accuracy required for the study.« less

Guar gum coupled microscale ZVI for in situ treatment of CAHs: continuous-flow column study.

PubMed

Velimirovic, Milica; Simons, Queenie; Bastiaens, Leen

2014-01-30

A column study was performed under in situ conditions to evaluate to which extend the inactivation of the microscale zerovalent iron (mZVI) by guar gum occurs under continuous flow conditions. Five aquifer containing columns were set up under different conditions. Efficient removal of trichloroethene was observed for the column amended by mZVI. Stabilization of the mZVI with guar gum led to slightly reduced activity. More reduced reactivity was observed in the poisoned column containing guar gum stabilized mZVI. This confirms that soil microorganisms can degrade guar gum and that subsequent removal of the oligosaccharides by the groundwater flow (flushing effect) can reactivate the mZVI. After more than six months of continuous operation the columns were dismantled. DNA-based qPCR analysis revealed that mZVI does not significantly affect the bacterial community, while guar gum stabilized mZVI particles can even induce bacterial growth. Overall, this study suggests that the temporarily decreased mZVI reactivity due to guar gum, has a rather limited impact on the performance of in situ reactive zones. The presence of guar gum slightly reduced the reactivity of iron, but also slowed down the iron corrosion rate which prolongs the life time of reactive zone. Copyright © 2013 Elsevier B.V. All rights reserved.

Aquifer Storage Recovery (ASR) of chlorinated municipal drinking water in a confined aquifer

USGS Publications Warehouse

Izbicki, John A.; Petersen, Christen E.; Glotzbach, Kenneth J.; Metzger, Loren F.; Christensen, Allen H.; Smith, Gregory A.; O'Leary, David R.; Fram, Miranda S.; Joseph, Trevor; Shannon, Heather

2010-01-01

About 1.02 x 106 m3 of chlorinated municipal drinking water was injected into a confined aquifer, 94-137 m below Roseville, California, between December 2005 and April 2006. The water was stored in the aquifer for 438 days, and 2.64 x 106 m3 of water were extracted between July 2007 and February 2008. On the basis of Cl data, 35% of the injected water was recovered and 65% of the injected water and associated disinfection by-products (DBPs) remained in the aquifer at the end of extraction. About 46.3 kg of total trihalomethanes (TTHM) entered the aquifer with the injected water and 37.6 kg of TTHM were extracted. As much as 44 kg of TTHMs remained in the aquifer at the end of extraction because of incomplete recovery of injected water and formation of THMs within the aquifer by reactions with freechlorine in the injected water. Well-bore velocity log data collected from the Aquifer Storage Recovery (ASR) well show as much as 60% of the injected water entered the aquifer through a 9 m thick, high-permeability layer within the confined aquifer near the top of the screened interval. Model simulations of ground-water flow near the ASR well indicate that (1) aquifer heterogeneity allowed injected water to move rapidly through the aquifer to nearby monitoring wells, (2) aquifer heterogeneity caused injected water to move further than expected assuming uniform aquifer properties, and (3) physical clogging of high-permeability layers is the probable cause for the observed change in the distribution of borehole flow. Aquifer heterogeneity also enhanced mixing of native anoxic ground water with oxic injected water, promoting removal of THMs primarily through sorption. A 3 to 4-fold reduction in TTHM concentrations was observed in the furthest monitoring well 427 m downgradient from the ASR well, and similar magnitude reductions were observed in depth-dependent water samples collected from the upper part of the screened interval in the ASR well near the end of the extraction

A conceptual model of ground-water flow in the eastern Snake River Plain aquifer at the Idaho National Laboratory and vicinity with implications for contaminant transport

USGS Publications Warehouse

Ackerman, Daniel J.; Rattray, Gordon W.; Rousseau, Joseph P.; Davis, Linda C.; Orr, Brennon R.

2006-01-01

Ground-water flow in the west-central part of the eastern Snake River Plain aquifer is described in a conceptual model that will be used in numerical simulations to evaluate contaminant transport at the Idaho National Laboratory (INL) and vicinity. The model encompasses an area of 1,940 square miles (mi2) and includes most of the 890 mi2 of the INL. A 50-year history of waste disposal associated with research activities at the INL has resulted in measurable concentrations of waste contaminants in the aquifer. A thorough understanding of the fate and movement of these contaminants in the subsurface is needed by the U.S. Department of Energy to minimize the effect that contaminated ground water may have on the region and to plan effectively for remediation. Three hydrogeologic units were used to represent the complex stratigraphy of the aquifer in the model area. Collectively, these hydrogeologic units include at least 65 basalt-flow groups, 5 andesite-flow groups, and 61 sedimentary interbeds. Three rhyolite domes in the model area extend deep enough to penetrate the aquifer. The rhyolite domes are represented in the conceptual model as low permeability, vertical pluglike masses, and are not included as part of the three primary hydrogeologic units. Broad differences in lithology and large variations in hydraulic properties allowed the heterogeneous, anisotropic basalt-flow groups, andesite-flow groups, and sedimentary interbeds to be grouped into three hydrogeologic units that are conceptually homogeneous and anisotropic. Younger rocks, primarily thin, densely fractured basalt, compose hydrogeologic unit 1; younger rocks, primarily of massive, less densely fractured basalt, compose hydrogeologic unit 2; and intermediate-age rocks, primarily of slightly-to-moderately altered, fractured basalt, compose hydrogeologic unit 3. Differences in hydraulic properties among adjacent hydrogeologic units result in much of the large-scale heterogeneity and anisotropy of the

Use of chlorine-36 to determine regional-scale aquifer dispersivity, eastern Snake River Plain aquifer, Idaho/USA

USGS Publications Warehouse

Cecil, L.D.; Welhan, J.A.; Green, J.R.; Grape, S.K.; Sudicky, E.R.

2000-01-01

Chlorine-36 (36Cl) derived from processed nuclear waste that was disposed at the US Department of Energy's Idaho National Engineering and Environmental Laboratory (INEEL) through a deep injection well in 1958, was detected 24-28 yr later in groundwater monitoring wells approximately 26 km downgradient from the source. Groundwater samples covering the period 1966-1995 were selected from the US Geological Survey's archived-sample library at the INEEL and analyzed for 36Cl by accelerator mass spectrometry (AMS). The smaller 36Cl peak concentrations in water from the far-field monitoring wells relative to the input suggest that aquifer dispersivity may be large. However, the sharpness of the 1958 disposal peak of 36Cl is matched by the measured 36Cl concentrations in water from these wells. This implies that a small aquifer dispersivity may be attributed to preferential groundwater flowpaths. Assuming that tracer arrival times at monitoring wells are controlled by preferential flow, a 1-D system-response model was used to estimate dispersivity by comparing the shape of predicted 36Cl-concentration curves to the shape of 36Cl-concentration curves measured in water from these observation wells. The comparisons suggest that a 1-D dispersivity of 5 m provides the best fit to the tracer data. Previous work using a 2-D equivalent porous-media model concluded that longitudinal dispersivity (equivalent to 1-D dispersivity in our model) was 90 m (Ackerman, 1991). A 90 m dispersivity value eliminates the 1958 disposal peak in our model output curves. The implications of the arrival of 36Cl at downgradient monitoring wells are important for three reasons: (1) the arrival times and associated 36Cl concentrations provide quantitative constraints on residence times, velocities, and dispersivities in the aquifer; (2) they help to refine our working hypotheses of groundwater flow in this aquifer and (3) they may suggest a means of estimating the distribution of preferential flowpaths

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

USGS Publications Warehouse

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.

Diagnosis of the Ghiss Nekor aquifer in order to elaborate the aquifer contract

NASA Astrophysics Data System (ADS)

Baite, Wissal; Boukdir, A.; Zitouni, A.; Dahbi, S. D.; Mesmoudi, H.; Elissami, A.; Sabri, E.; Ikhmerdi, H.

2018-05-01

The Ghiss-Nekor aquifer, located in the north-east of the action area of the ABHL, plays a strategic role in the drinkable water supply of the city of Al Hoceima and of the neighboring urban areas. It also participates in the irrigation of PMH. However, this aquifer has problems such as over-exploitation and pollution. In the face of these problems, the only Solution is the establishment of a new mode of governance, which privileges the participation, the involvement and the responsibility of the actors concerned in a negotiated contractual framework, namely the aquifer contract. The purpose of this study is to diagnose the current state of the Ghiss Nekor aquifer, the hydrogeological characterization of the aquifer, the use of the waters of the aquifer, the Problem identification and the introduction of the aquifer contract, which aims at the participatory and sustainable management of underground water resources in the Ghiss- Nekor plain, to ensure sustainable development.

Adaptations of indigenous bacteria to fuel contamination in karst aquifers in south-central Kentucky

USGS Publications Warehouse

Byl, Thomas D.; Metge, David W.; Agymang, Daniel T.; Bradley, Michael W.; Hileman, Gregg; Harvey, Ronald W.

2014-01-01

The karst aquifer systems in southern Kentucky can be dynamic and quick to change. Microorganisms that live in these unpredictable aquifers are constantly faced with environmental changes. Their survival depends upon adaptations to changes in water chemistry, taking advantage of positive stimuli and avoiding negative environmental conditions. The U.S. Geological Survey conducted a study in 2001 to determine the capability of bacteria to adapt in two distinct regions of water quality in a karst aquifer, an area of clean, oxygenated groundwater and an area where the groundwater was oxygen depleted and contaminated by jet fuel. Water samples containing bacteria were collected from one clean well and two jet fuel contaminated wells in a conduit-dominated karst aquifer. Bacterial concentrations, enumerated through direct count, ranged from 500,000 to 2.7 million bacteria per mL in the clean portion of the aquifer, and 200,000 to 3.2 million bacteria per mL in the contaminated portion of the aquifer over a twelve month period. Bacteria from the clean well ranged in size from 0.2 to 2.5 mm, whereas bacteria from one fuel-contaminated well were generally larger, ranging in size from 0.2 to 3.9 mm. Also, bacteria collected from the clean well had a higher density and, consequently, were more inclined to sink than bacteria collected from contaminated wells. Bacteria collected from the clean portion of the karst aquifer were predominantly (,95%) Gram-negative and more likely to have flagella present than bacteria collected from the contaminated wells, which included a substantial fraction (,30%) of Gram-positive varieties. The ability of the bacteria from the clean portion of the karst aquifer to biodegrade benzene and toluene was studied under aerobic and anaerobic conditions in laboratory microcosms. The rate of fuel biodegradation in laboratory studies was approximately 50 times faster under aerobic conditions as compared to anaerobic, sulfur-reducing conditions. The

Long-term behavior of passively aerated compost methanotrophic biofilter columns.

PubMed

Wilshusen, J H; Hettiaratchi, J P A; Stein, V B

2004-01-01

The methane oxidation potential of several types of compost methanotrophic biofilter columns were compared in the laboratory over a period of 220 days. The results indicate an increase in methanotrophic activity over a period of about 100 days, up to a maximum of 400 g m(-2) day(-1), and a gradual decline to about 100 g m(-2) day(-1) within the next 120 days. High methane oxidation rates appear to be restricted to a small area of the column, 10-15 cm thick. Based on the laboratory investigations carried out to determine the cause for the decline in methane oxidation rate, it was concluded that the formation of exopolymeric substances (EPS), at the zones of maximum methane oxidation, was responsible for this decline. In monitoring methane oxidation in a column for up to 600 days, it was observed that mixing of the medium after formation of EPS enabled the column to temporarily recover high performance. The results suggest that stable, homogenous compost, with a low C/N and low ammonium content, mixed on a regular basis, could achieve and maintain high methane oxidation efficiencies. Copyright 2004 Elsevier Ltd.

Biscayne aquifer, southeast Florida

USGS Publications Warehouse

Klein, Howard; Hull, John E.

1978-01-01

Peak daily pumpage from the highly permeable, unconfined Biscayne aquifer for public water-supply systems in southeast Florida in 1975 was about 500 million gallons. Another 165 million gallons was withdrawn daily for irrigation. Recharge to the aquifer is primarily by local rainfall. Discharge is by evapotranspiration, canal drainage, coastal seepage, and pumping. Pollutants can enter the aquifer by direct infiltration from land surface or controlled canals, septic-tank and other drainfields, drainage wells, and solid-waste dumps. Most of the pollutants are concentrated in the upper 20 to 30 feet of the aquifer; public supply wells generally range in depth from about 75 to 150 feet. Dilution, dispersion, and adsorption tend to reduce the concentrations. Seasonal heavy rainfall and canal discharge accelerate ground-water circulation, thereby tending to dilute and flush upper zones of the aquifer. The ultimate fate of pollutants in the aquifer is the ocean, although some may be adsorbed by the aquifer materials en route to the ocean, and some are diverted to pumping wells. (Woodard-USGS)

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1997-10-24

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

Arsenic attenuation by oxidized aquifer sediments in Bangladesh

USGS Publications Warehouse

Stollenwerk, K.G.; Breit, G.N.; Welch, A.H.; Yount, J.C.; Whitney, J.W.; Foster, A.L.; Uddin, M.N.; Majumder, R.K.; Ahmed, N.

2007-01-01

Recognition of arsenic (As) contamination of shallow fluvio-deltaic aquifers in the Bengal Basin has resulted in increasing exploitation of groundwater from deeper aquifers that generally contain low concentrations of dissolved As. Pumping-induced infiltration of high-As groundwater could eventually cause As concentrations in these aquifers to increase. This study investigates the adsorption capacity for As of sediment from a low-As aquifer near Dhaka, Bangladesh. A shallow, chemically-reducing aquifer at this site extends to a depth of 50??m and has maximum As concentrations in groundwater of 900????g/L. At depths greater than 50??m, geochemical conditions are more oxidizing and groundwater has < 5????g/L As. There is no thick layer of clay at this site to inhibit vertical transport of groundwater. Arsenite [As(III)] is the dominant oxidation state in contaminated groundwater; however, data from laboratory batch experiments show that As(III) is oxidized to arsenate [As(V)] by manganese (Mn) minerals that are present in the oxidized sediment. Thus, the long-term viability of the deeper aquifers as a source of water supply is likely to depend on As(V) adsorption. The adsorption capacity of these sediments is a function of the oxidation state of As and the concentration of other solutes that compete for adsorption sites. Arsenite that was not oxidized did adsorb, but to a much lesser extent than As(V). Phosphate (P) caused a substantial decrease in As(V) adsorption. Increasing pH and concentrations of silica (Si) had lesser effects on As(V) adsorption. The effect of bicarbonate (HCO3) on As(V) adsorption was negligible. Equilibrium constants for adsorption of As(V), As(III), P, Si, HCO3, and H were determined from the experimental data and a quantitative model developed. Oxidation of As(III) was modeled with a first-order rate constant. This model was used to successfully simulate As(V) adsorption in the presence of multiple competing solutes. Results from these

EPA Region 1 Sole Source Aquifers

EPA Pesticide Factsheets

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.

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

NASA Astrophysics Data System (ADS)

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.

Mixing effects on apparent reaction rates and isotope fractionation during denitrification in a heterogeneous aquifer

USGS Publications Warehouse

Green, Christopher T.; Böhlke, John Karl; Bekins, Barbara A.; Phillips, Steven P.

2010-01-01

Gradients in contaminant concentrations and isotopic compositions commonly are used to derive reaction parameters for natural attenuation in aquifers. Differences between field‐scale (apparent) estimated reaction rates and isotopic fractionations and local‐scale (intrinsic) effects are poorly understood for complex natural systems. For a heterogeneous alluvial fan aquifer, numerical models and field observations were used to study the effects of physical heterogeneity on reaction parameter estimates. Field measurements included major ions, age tracers, stable isotopes, and dissolved gases. Parameters were estimated for the O2 reduction rate, denitrification rate, O2 threshold for denitrification, and stable N isotope fractionation during denitrification. For multiple geostatistical realizations of the aquifer, inverse modeling was used to establish reactive transport simulations that were consistent with field observations and served as a basis for numerical experiments to compare sample‐based estimates of “apparent” parameters with “true“ (intrinsic) values. For this aquifer, non‐Gaussian dispersion reduced the magnitudes of apparent reaction rates and isotope fractionations to a greater extent than Gaussian mixing alone. Apparent and true rate constants and fractionation parameters can differ by an order of magnitude or more, especially for samples subject to slow transport, long travel times, or rapid reactions. The effect of mixing on apparent N isotope fractionation potentially explains differences between previous laboratory and field estimates. Similarly, predicted effects on apparent O2threshold values for denitrification are consistent with previous reports of higher values in aquifers than in the laboratory. These results show that hydrogeological complexity substantially influences the interpretation and prediction of reactive transport.

Investigation of recharge dynamics and flow paths in a fractured crystalline aquifer in semi-arid India using borehole logs: implications for managed aquifer recharge

NASA Astrophysics Data System (ADS)

Alazard, M.; Boisson, A.; Maréchal, J.-C.; Perrin, J.; Dewandel, B.; Schwarz, T.; Pettenati, M.; Picot-Colbeaux, G.; Kloppman, W.; Ahmed, S.

2016-02-01

The recharge flow paths in a typical weathered hard-rock aquifer in a semi-arid area of southern India were investigated in relation to structures associated with a managed aquifer recharge (MAR) scheme. Despite the large number of MAR structures, the mechanisms of recharge in their vicinity are still unclear. The study uses a percolation tank as a tool to identify the input signal of the recharge and uses multiple measurements (piezometric time series, electrical conductivity profiles in boreholes) compared against heat-pulse flowmeter measurements and geochemical data (major ions and stable isotopes) to examine recharge flow paths. The recharge process is a combination of diffuse piston flow and preferential flow paths. Direct vertical percolation appears to be very limited, in contradiction to the conceptual model generally admitted where vertical flow through saprolite is considered as the main recharge process. The horizontal component of the flow leads to a strong geochemical stratification of the water column. The complex recharge pattern, presented in a conceptual model, leads to varied impacts on groundwater quality and availability in both time and space, inducing strong implications for water management, water quality evolution, MAR monitoring and longer-term socio-economic costs.

Groundwater Dynamics in Fossil Fractured Carbonate Aquifers in Eastern Arabian Peninsula

NASA Astrophysics Data System (ADS)

Farag, A. Z. A.; Heggy, E.; Helal, M.; Thirunavukkarasu, D.; Scabbia, G.; Palmer, E. M.

2017-12-01

The Eastern Arabian Peninsula, notably the Qatar Peninsula, represents one of the highest natural groundwater discharge areas for the Arabian platform fossil aquifer system. Groundwater flow dynamics in these aquifers trace the paleoclimatic conditions that have prevailed the Arabian Peninsula during the Quaternary. In such settings, connections between aquifers strongly affect the flow dynamics, water quality and availability as well as karst formation and landscape evolution. Geological structures such as folds, faults and fractures are central to aquifer connectivity, yet their role on groundwater flow is poorly understood. Herein, we performed a detailed mapping of exposed and buried structural features in Qatar using Landsat, Sentinel and ALOS-PalSAR scenes, correlated with field and laboratory measurements to understand their role in aquifer connectivity and groundwater dynamics. Our results suggest that E-W oriented fold-related faults act as vertical conduits along which artesian upward leakages from the deep aquifers (e.g. Aruma and Umm er Radhuma) take place into the shallower aquifers (e.g. Rus and Dammam). Evidence includes: (1) the high potentiometric surfaces of deep aquifers (6 to 25 m amsl) compare to the shallower aquifers (2-3 m amsl for the same region); (2) anomalous elevation of groundwater levels and steeper hydraulic gradients in densely faulted regions; (3) mixed isotopic composition in shallow aquifers (δ18O: -5 to -2 ‰, δ2H: -40 to -10 ‰) between reported deep fossil waters (δ18O: -6.3 ‰, δ2H: -55 ‰) and modern meteoric waters (weighted average: δ18O: -0.6 ‰, δ2H: 4 ‰); (4) abundant meso-crystalline fibrous gypsum veins along fault zones in the Dammam Formation (up to 28 m amsl) in southern Qatar where the anhydritic member of the Rus Formation predominates the subsurface leading to gypsum oversaturation of groundwater. The similarity of crystal morphology (platy crystals under SEM), mineralogical compositions from XRD

Reliability assessment of slender concrete columns at the stability failure

NASA Astrophysics Data System (ADS)

Valašík, Adrián; Benko, Vladimír; Strauss, Alfred; Täubling, Benjamin

2018-01-01

The European Standard for designing concrete columns within the use of non-linear methods shows deficiencies in terms of global reliability, in case that the concrete columns fail by the loss of stability. The buckling failure is a brittle failure which occurs without warning and the probability of its formation depends on the columns slenderness. Experiments with slender concrete columns were carried out in cooperation with STRABAG Bratislava LTD in Central Laboratory of Faculty of Civil Engineering SUT in Bratislava. The following article aims to compare the global reliability of slender concrete columns with slenderness of 90 and higher. The columns were designed according to methods offered by EN 1992-1-1 [1]. The mentioned experiments were used as basis for deterministic nonlinear modelling of the columns and subsequent the probabilistic evaluation of structural response variability. Final results may be utilized as thresholds for loading of produced structural elements and they aim to present probabilistic design as less conservative compared to classic partial safety factor based design and alternative ECOV method.

Preparation and Characterization of a Polymeric Monolithic Column for Use in High-Performance Liquid Chromatography (HPLC)

ERIC Educational Resources Information Center

Bindis, Michael P.; Bretz, Stacey Lowery; Danielson, Neil D.

2011-01-01

The high-performance liquid chromatography (HPLC) experiment, most often done in the undergraduate analytical instrumentation laboratory course, generally illustrates reversed-phase chromatography using a commercial C[subscript]18 silica column. To avoid the expense of periodic column replacement and introduce a choice of columns with different…

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

PubMed

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.

The effect of feed water dissolved organic carbon concentration and composition on organic micropollutant removal and microbial diversity in soil columns simulating river bank filtration.

PubMed

Bertelkamp, C; van der Hoek, J P; Schoutteten, K; Hulpiau, L; Vanhaecke, L; Vanden Bussche, J; Cabo, A J; Callewaert, C; Boon, N; Löwenberg, J; Singhal, N; Verliefde, A R D

2016-02-01

This study investigated organic micropollutant (OMP) biodegradation rates in laboratory-scale soil columns simulating river bank filtration (RBF) processes. The dosed OMP mixture consisted of 11 pharmaceuticals, 6 herbicides, 2 insecticides and 1 solvent. Columns were filled with soil from a RBF site and were fed with four different organic carbon fractions (hydrophilic, hydrophobic, transphilic and river water organic matter (RWOM)). Additionally, the effect of a short-term OMP/dissolved organic carbon (DOC) shock-load (e.g. quadrupling the OMP concentrations and doubling the DOC concentration) on OMP biodegradation rates was investigated to assess the resilience of RBF systems. The results obtained in this study imply that - in contrast to what is observed for managed aquifer recharge systems operating on wastewater effluent - OMP biodegradation rates are not affected by the type of organic carbon fraction fed to the soil column, in case of stable operation. No effect of a short-term DOC shock-load on OMP biodegradation rates between the different organic carbon fractions was observed. This means that the RBF site simulated in this study is resilient towards transient higher DOC concentrations in the river water. However, a temporary OMP shock-load affected OMP biodegradation rates observed for the columns fed with the river water organic matter (RWOM) and the hydrophilic fraction of the river water organic matter. These different biodegradation rates did not correlate with any of the parameters investigated in this study (cellular adenosine triphosphate (cATP), DOC removal, specific ultraviolet absorbance (SUVA), richness/evenness of the soil microbial population or OMP category (hydrophobicity/charge). Copyright © 2015 Elsevier Ltd. All rights reserved.

Organic molecules as sorbing tracers for the assessment of surface areas in consolidated aquifer systems

NASA Astrophysics Data System (ADS)

Schaffer, Mario; Warner, Wiebke; Kutzner, Susann; Börnick, Hilmar; Worch, Eckhard; Licha, Tobias

2017-03-01

Based on the assumption that the specific surface area to volume ratio Asurf/V of consolidated rock materials is proportional to the surface area available for sorption, several inorganic cations were recently proposed as sorbing (cation exchanging) tracers for estimating these ratios in aquifers (e.g., for deriving the efficient heat exchange area of geothermal reservoirs). The main disadvantages of inorganic ions, however, are the limited number of suitable ions, their potential geogenic background, and their challenging online detection at trace concentrations. In this work, the spectrum of chemical substances used as sorbing tracers expands by considering fluorescent organic compounds that are cationic. They have the advantage of being highly water soluble and easy to measure online at very low concentrations. Results from systematic lab column experiments with seven selected organic cations under various conditions (different salinities and temperatures) are presented, emphasizing the potential of organic molecules as alternative sorbing tracers especially in consolidated aquifer systems. This work is a first stepping stone in identifying suitable molecular structures that can be selected or even individually adapted to the requirements of the tracer tests and prevailing aquifer conditions.

Hydrogeologic atlas of aquifers in Indiana

USGS Publications Warehouse

Fenelon, Joseph M.; Bobay, K.E.; Greeman, T.K.; Hoover, M.E.; Cohen, D.A.; Fowler, K.K.; Woodfield, M.C.; and Durbin, J. M.

1994-01-01

Aquifers in 12 water-management basins of Indiana are identified in a series of 104 hydrogeologic sections and 12 maps that show the thickness and configuration of aquifers. The vertical distribution of water-bearing units and a generalized potentiometric profile are shown along 3,500 miles of section lines that were constructed from drillers' logs of more than 4,200 wells. The horizontal scale of the sections is 1:125,000. Maps of aquifers showing the areal distribution of each aquifer type were drawn at a scale of 1:500,000. Unconsolidated aquifers are the most widely used aquifers in Indiana and include surficial, buried, and discontinuous layers of sand and gravel. Most of the surficial sand and gravel is in large outwash plains in northern Indiana and along the major rivers. Buried sand and gravel aquifers are interbedded with till deposits in much of the northern two-thirds of Indiana. Discontinuous sand and gravel deposits are present as isolated lenses, primarily in glaciated areas. The bedrock aquifers generally have lower yields than most of the sand and gravel aquifers; however, bedrock aquifers are areally widespread and are an important source of water. Bedrock aquifer types consist of carbonates; sandstones; complexly interbedded sandstones, siltstones, shales, limestones, and coals; and an upper weathered zone in low permeability rock. Carbonate aquifers underlie about one-half of Indiana and are the most productive of the bedrock aquifers. The other principal bedrock aquifer type, sandstone, underlies large areas in the southwestern one-fifth of Indiana. No aquifer is known to be present in the southeastern corner of Indiana.

Aquifer thermal-energy-storage modeling

NASA Astrophysics Data System (ADS)

Schaetzle, W. J.; Lecroy, J. E.

1982-09-01

A model aquifer was constructed to simulate the operation of a full size aquifer. Instrumentation to evaluate the water flow and thermal energy storage was installed in the system. Numerous runs injecting warm water into a preconditioned uniform aquifer were made. Energy recoveries were evaluated and agree with comparisons of other limited available data. The model aquifer is simulated in a swimming pool, 18 ft by 4 ft, which was filled with sand. Temperature probes were installed in the system. A 2 ft thick aquifer is confined by two layers of polyethylene. Both the aquifer and overburden are sand. Four well configurations are available. The system description and original tests, including energy recovery, are described.

Digital computer simulation model of the Englishtown aquifer in the northern coastal plain of New Jersey

USGS Publications Warehouse

Nichols, W.D.

1977-01-01

Continued decline of water levels in the Englishtown aquifer, in New Jersey, has caused considerable concern regarding the ability of the aquifer to meet future yield demands. A detailed study of the capability of the aquifer to yield water entailed the use of a digital computer simulation model to evaluate aquifer and confining layer coefficients and to test alternative concepts of the hydrodynamics of the flow system. The modeled area includes about 750 square miles of the northern Coastal Plain of New Jersey and encompasses all the major centers of pumping from the Englishtown aquifer. The simulation model was calibrated by matching computed declines with historical water-level declines over the 12-year period, 1959-70. The volume of transient and steady leakage into the Englishtown aquifer from and through the adjacent confining layers equaled more than 90 percent of the total volume of water withdrawn from the aquifer between 1959 and 1970. The analytical estimate of transient leakage indicates that about 60 percent of the water withdrawn from the Englishtown between 1959 and 1970 was replaced by water released from storage in the adjacent confining beds. An additional 34 percent of the withdrawal over this time period was supported by steady leakage through the overlying confining bed from the Mount Laurel aquifer. Of the more than 30 billion gallons withdrawn from the aquifer over the 12-year period, about 2 billion gallons were obtained from storage in the aquifer. The values of aquifer and confining-layer coefficients used in the model are nearly the same as the average values obtained from field and laboratory data. (Woodard-USGS)

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

USGS Publications Warehouse

Abbott, Marvin M.; Runkle, D.L.; Rea, Alan

1997-01-01

Nonproprietary format files This diskette contains digitized aquifer boundaries and maps of hydraulic conductivity, recharge, and ground-water level elevation contours for the Vamoosa-Ada aquifer in east-central Oklahoma. The Vamoosa-Ada aquifer is an important source of water that underlies about 2,320-square miles of parts of Osage, Pawnee, Payne, Creek, Lincoln, Okfuskee, and Seminole Counties. Approximately 75 percent of the water withdrawn from the Vamoosa-Ada aquifer is for municipal use. Rural domestic use and water for stock animals account for most of the remaining water withdrawn. The Vamoosa-Ada aquifer is defined in a ground-water report as consisting principally of the rocks of the Late Pennsylvanian-age Vamoosa Formation and overlying Ada Group. The Vamoosa-Ada aquifer consists of a complex sequence of fine- to very fine-grained sandstone, siltstone, shale, and conglomerate interbedded with very thin limestones. The water-yielding capabilities of the aquifer are generally controlled by lateral and vertical distribution of the sandstone beds and their physical characteristics. The Vamoosa-Ada aquifer is unconfined where it outcrops in about an 1,700-square-mile area. Most of the lines in the aquifer boundary, hydraulic conductivity, and recharge data sets were extracted from published digital surficial geology data sets based on a scale of 1:250,000, and represent geologic contacts. Some of lines in the data sets were interpolated in areas where the Vamoosa-Ada aquifer is overlain by alluvial and terrace deposits near streams and rivers. These data sets include only the outcrop area of the Vamoosa-Ada aquifer and where the aquifer is overlain by alluvial and terrace deposits. The hydraulic conductivity value and recharge rate are from a ground-water report about the Vamoosa-Ada aquifer. The water-level elevation contours were digitized from a mylar map, at a scale of 1:250,000, used to publish a plate in a ground-water report about the Vamoosa

Hydraulic and mechanical properties affecting ground-water flow and aquifer-system compaction, San Joaquin Valley, California

USGS Publications Warehouse

Sneed, Michelle

2001-01-01

This report summarizes hydraulic and mechanical properties affecting ground-water flow and aquifer-system compaction in the San Joaquin Valley, a broad alluviated intermontane structural trough that constitutes the southern two-thirds of the Central Valley of California. These values will be used to constrain a coupled ground-water flow and aquifer-system compaction model of the western San Joaquin Valley called WESTSIM. A main objective of the WESTSIM model is to evaluate potential future land subsidence that might occur under conditions in which deliveries of imported surface water for agricultural use are reduced and ground-water pumping is increased. Storage values generally are components of the total aquifer-system storage and include inelastic and elastic skeletal storage values of the aquifers and the aquitards that primarily govern the potential amount of land subsidence. Vertical hydraulic conductivity values generally are for discrete thicknesses of sediments, usually aquitards, that primarily govern the rate of land subsidence. The data were compiled from published sources and include results of aquifer tests, stress-strain analyses of borehole extensometer observations, laboratory consolidation tests, and calibrated models of aquifer-system compaction.

Potential impacts of leakage from deep CO2 geosequestration on overlying freshwater aquifers.

PubMed

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).

Transport toward a well in highly heterogeneous aquifer

NASA Astrophysics Data System (ADS)

Di Dato, Mariaines; de Barros, Felipe P. J.; Bellin, Alberto; Fiori, Aldo

2017-04-01

Solute transport toward a well is a challenging subject in subsurface hydrology since the complexity of the mathematical model is tremendously increased by the non-uniformity of the mean flow and heterogeneity of the formation. Up to date, analytical solutions for such flow configurations are limited to low heterogeneous conditions. On the other hand, numerical simulations in 3D highly heterogeneous formations are computationally expensive and plagued by numerical errors. In this work we propose an analytical solution for the Breakthrough Curve (BTC) at the well for an instantaneous linear injection across the aquifer's thickness for any degree of heterogeneity of the porous medium. Our solution makes use of the Multi Indicator Model-Self Consistent Approximation (MIMSCA), by which the aquifer is conceptualized as an ensemble of blocks of constant hydraulic conductivity K randomly drawn from a lognormal distribution. In order to apply MIMSCA, we assume the flow as locally uniform, given that K is uniform within the block. With this approximation, the travel time to the well is equal to the superposition of the time spent by the solute particle within each block. We emphasize that, despite the approximations introduced, the model is able to reproduce the laboratory experiment of [1] without the need to fit any transport parameters. In this work, we present results for two different injection modes: a resident injection (e.g., residual DNAPL) and a flux proportional injection (e.g., leakage from a passive well). The proposed methodology allows to quantify the BTC at the well as a function of few parameters such as the injection mode and the statistical structure of the aquifer (geometric mean, variance and integral scale of the hydraulic conductivity field). Results illustrate that the release condition has a strong impact on the shape of the BTC. Furthermore, the difference between different injection modes increases with the heterogeneity of the K-field. The

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

USGS Publications Warehouse

Becker, C.J.; Runkle, D.L.; Rea, Alan

1997-01-01

ARC/INFO export and nonproprietary format files This diskette contains digitized aquifer boundaries and maps of hydraulic conductivity, recharge, and ground-water level elevation contours for the Elk City aquifer in western Oklahoma. The aquifer covers an area of approximately 193,000 acres and supplies ground water for irrigation, domestic, and industrial purposes in Beckham, Custer, Roger Mills, and Washita Counties along the divide between the Washita and Red River basins. The Elk City aquifer consists of the Elk City Sandstone and overlying terrace deposits, made up of clay, silt, sand and gravel, and dune sands in the eastern part and sand and gravel of the Ogallala Formation (or High Plains aquifer) in the western part of the aquifer. The Elk City aquifer is unconfined and composed of very friable sandstone, lightly cemented with clay, calcite, gypsum, or iron oxide. Most of the grains are fine-sized quartz but the grain size ranges from clay to cobble in the aquifer. The Doxey Shale underlies the Elk City aquifer and acts as a confining unit, restricting the downward movement of ground water. All of the data sets were digitized and created from information and maps in a ground-water modeling thesis and report of the Elk City aquifer. The maps digitized were published at a scale of 1:63,360. Ground-water flow models are numerical representations that simplify and aggregate natural systems. Models are not unique; different combinations of aquifer characteristics may produce similar results. Therefore, values of hydraulic conductivity and recharge used in the model and presented in this data set are not precise, but are within a reasonable range when compared to independently collected data.

Research approach to teaching groundwater biodegradation in karst aquifers

USGS Publications Warehouse

King, L.; Byl, T.; Painter, R.

2006-01-01

TSU in partnership with the USGS has conducted extensive research regarding biode??gradation of contaminants in karst aquifers. This research resulted in the development of a numerical approach to modeling biodegradation of contaminants in karst aquifers that is taught to environmental engineering students in several steps. First, environmental engineering students are taught chemical-reaction engineering principles relating to a wide variety of environmental fate and transport issues. Second, as part of TSU's engineering course curriculum, students use a non-ideal flow laboratory reactor system and run a tracer study to establish residence time distribution (RTD). Next, the students couple that formula to a first-order biodegradation rate and predict the removal of a biodegradable contaminant as a function of residence time. Following this, students are shown data collected from karst bedrock wells that suggest that karst aquifers are analogous to non-ideal flow reactors. The students are challenged to develop rates of biodegradation through lab studies and use their results to predict biodegradaton at an actual contaminated karst site. Field studies are also conducted to determine the accuracy of the students' predictions. This academic approach teaches biodegradation processes, rate-kinetic processes, hydraulic processes and numerical principles. The students are able to experience how chemical engineering principles can be applied to other situations, such as, modeling biodegradation of contaminants in karst aquifers. This paper provides background on the chemical engineering principles and karst issues used in the research-enhanced curriculum. ?? American Society for Engineering Education, 2006.

Wall-Friction Support of Vertical Loads in Submerged Sand and Gravel Columns

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walton, O. R.; Vollmer, H. J.; Hepa, V. S.

Laboratory studies of the ‘floor-loads’ under submerged vertical columns of sand and/or gravel indicate that such loads can be approximated by a buoyancy-corrected Janssen-silo-theory-like relationship. Similar to conditions in storage silos filled with dry granular solids, most of the weight of the sand or gravel is supported by wall friction forces. Laboratory measurements of the loads on the floor at the base of the water-filled columns (up to 25-diameters tall) indicate that the extra floor-load from the addition of the granular solid never exceeded the load that would exist under an unsupported (wide) bed of submerged sand or gravel thatmore » has a total depth corresponding to only two column-diameters. The measured floorloads reached an asymptotic maximum value when the depth of granular material in the columns was only three or four pipe-diameters, and never increased further as the columns were filled to the top (e.g. up to heights of 10 to 25 diameters). The floor-loads were stable and remained the same for days after filling. Aggressive tapping (e.g. hitting the containing pipe on the outside, manually with a wrench up and down the height and around the circumference) could increase (and occasionally decrease) the floor load substantially, but there was no sudden collapse or slumping to a state without significant wall friction effects. Considerable effort was required, repeatedly tapping over almost the entire column wall periphery, in order to produce floor-loads that corresponded to the total buoyancy-corrected weight of granular material added to the columns. Projecting the observed laboratory behavior to field conditions would imply that a stable floor-load condition, with only a slightly higher total floor pressure than the preexisting hydrostatic-head, would exist after a water-filled bore-hole is filled with sand or gravel. Significant seismic vibration (either a large nearby event or many micro-seismic events over an extended period) would

Monitoring Uranium Transformations Determined by the Evolution of Biogeochemical Processes: Design of Mixed Batch Reactor and Column Studies at Oak Ridge National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Criddle, Craig S.; Wu, Weimin

2013-04-17

With funds provided by the US DOE, Argonne National Laboratory subcontracted the design of batch and column studies to a Stanford University team with field experience at the ORNL IFRC, Oak Ridge, TN. The contribution of the Stanford group ended in 2011 due to budget reduction in ANL. Over the funded research period, the Stanford research team characterized ORNL IFRC groundwater and sediments and set up microcosm reactors and columns at ANL to ensure that experiments were relevant to field conditions at Oak Ridge. The results of microcosm testing demonstrated that U(VI) in sediments was reduced to U(IV) with themore » addition of ethanol. The reduced products were not uraninite but were instead U(IV) complexes associated with Fe. Fe(III) in solid phase was only partially reduced. The Stanford team communicated with the ANL team members through email and conference calls and face to face at the annual ERSP PI meeting and national meetings.« less

Steady-State and Transient Groundwater Flow and Advective Transport, Eastern Snake River Plain Aquifer, Idaho National Laboratory and Vicinity, Idaho

NASA Astrophysics Data System (ADS)

Fisher, J. C.; Ackerman, D. J.; Rousseau, J. P.; Rattray, G. W.

2009-12-01

Three-dimensional steady-state and transient models of groundwater flow and advective transport through the fractured basalts and interbedded sediments of the Eastern Snake River Plain (ESRP) aquifer were developed by the U.S. Geological Survey in cooperation with the U.S. Department of Energy. The model domain covers an area of 1,940 square miles that includes most of the Idaho National Laboratory (INL). A 50-year history of waste disposal at the INL has resulted in measurable concentrations of waste contaminants in the aquifer. Numerical models simulated 1980 steady-state conditions and transient flow for 1980-95. In the transient model, streamflow infiltration was the major stress. The models were calibrated using the parameter-estimation program incorporated in MODFLOW-2000. The steady-state model reasonably simulated the observed water-table altitude and gradients. Simulation of transient conditions reproduced changes in the flow system resulting from episodic infiltration from the Big Lost River. Analysis of simulations shows that flow is (1) dominantly horizontal through interflow zones in basalt, vertical anisotropy resulting from contrasts in hydraulic conductivity of different types of basalt and the interbedded sediments, (2) temporally variable due to streamflow infiltration from the Big Lost River, and (3) moving downward downgradient of the INL. Particle-tracking simulations were used to evaluate how simulated groundwater flow paths and travel times differ between the steady-state and transient flow models, and how well model-derived groundwater flow directions and velocities compare to independently-derived estimates. Particle tracking also was used to simulate the growth of tritium plumes originating at two INL facilities over a 16 year period under steady-state and transient flow conditions (1953-68). The shape, dimensions, and areal extent of these plumes were compared to a map of the plumes for 1968 from tritium releases beginning in 1952

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

PubMed Central

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

2016-01-01

The hydraulic relationship between the stream and aquifer can be altered from hydraulic connection to disconnection when the pumping rate exceeds the maximum seepage flux of the streambed. This study proposes to quantitatively analyze the physical processes of stream-aquifer systems from connection to disconnection. A free water table equation is adopted to clarify under what conditions a stream starts to separate hydraulically from an aquifer. Both the theoretical analysis and laboratory tests have demonstrated that the hydraulic connectedness of the stream-aquifer system can reach a critical disconnection state when the horizontal hydraulic gradient at the free water surface is equal to zero and the vertical is equal to 1. A boundary-value problem for movement of the critical point of disconnection is established for an analytical solution of the inverted water table movement beneath the stream. The result indicates that the maximum distance or thickness of the inverted water table is equal to the water depth in the stream, and at a steady state of disconnection, the maximum hydraulic gradient at the streambed center is 2. This study helps us to understand the hydraulic phenomena of water flow near streams and accurately assess surface water and groundwater resources. PMID:26818442

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

DOE PAGES

Wang, Wenke; Dai, Zhenxue; Zhao, Yaqian; ...

2016-01-28

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

Regional aquifer systems

NASA Astrophysics Data System (ADS)

The fifth in the American Water Resources Association (AWRA) Monograph series “Regional Aquifer Systems of the United States” has just been published as Monograph Series No. 13, “Aquifers of the Midwestern Area,” edited by L. A. Swain and A. Ivan Johnson. The 238-page publication is available for $18 to AWRA members and $21 for nonmembers.Each AWRA Annual Conference since 1985 has sponsored special seminars describing hydrologic, geochemical, and geologic characteristics of the Regional Aquifer System Analysis (RASA) studies carried out by the U.S. Geological Survey

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thorne, P.D.; Chamness, M.A.; Vermeul, V.R.

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

Hydrogeology of Ljubljana polje perched aquifers

NASA Astrophysics Data System (ADS)

Šram, D.; Brenčič, M.

2012-04-01

Ljubljana polje aquifer lies in central part of Slovenia and is one of the biggest and most important aquifers in Slovenia. Aquifer was formed in quaternary basin which was filled with sediments from local rivers. River Sava is the biggest and the most important among them. Thickness of the aquifer varies from 20 m to 100 m. In general it is an unconfined aquifer, but locally, between gravel and sand sediments which have good hydraulic conductivity, layers with low hydraulic conductivity, such as silt and clay, appear. Those layers or lenses can form perched aquifers. Perched aquifers are important for prevention of pollution of the main aquifer and also for the water recharge in the time periods with high precipitation. The perched aquifers were located by boreholes, while their spatial distribution has not been studied yet. Within the project INCOME all the existing lithological borehole logs were collected and analysed with Jewel Suite 2011 software. A geostatistical method sequential indicator simulation was used to create spatial distribution of five hydrofacies at the Ljubljana polje aquifer. The layers/lenses that are bigger than 0.07 km2 and have hydraulic conductivity lower than K = 10-7 m/s were defined as lenses that can potentially form perched aquifers. In the modelling area, two areas with higher concentration of lenses with low hydraulic conductivity were defined. At those areas, according to the borehole data, perched aquifers appear few meters below surface to the depth around 30 m. At the other parts of the model area lenses with low hydraulic conductivity are less abundant. With spatial information (lateral and vertical extension) of perched aquifers in Ljubljana polje improvement of existing hydrogeological models can be made which can help to improve the qualitative and quantitative status of the Ljubljana polje main aquifer.

Aquifer test to determine hydraulic properties of the Elm aquifer near Aberdeen, South Dakota

USGS Publications Warehouse

Schaap, Bryan D.

2000-01-01

The Elm aquifer, which consists of sandy and gravelly glacial-outwash deposits, is present in several counties in northeastern South Dakota. An aquifer test was conducted northeast of Aberdeen during the fall of 1999 to determine the hydraulic properties of the Elm aquifer in that area. An improved understanding of the properties of the aquifer will be useful in the possible development of the aquifer as a water resource. Historical water-level data indicate that the saturated thickness of the Elm aquifer can change considerably over time. From September 1977 through November 1985, water levels at three wells completed in the Elm aquifer near the aquifer test site varied by 5.1 ft, 9.50 ft, and 11.1 ft. From June 1982 through October 1999, water levels at five wells completed in the Elm aquifer near the aquifer test site varied by 8.7 ft, 11.4 ft, 13.2 ft, 13.8 ft, and 19.7 ft. The water levels during the fall of 1999 were among the highest on record, so the aquifer test was affected by portions of the aquifer being saturated that might not be saturated during drier times. The aquifer test was conducted using five existing wells that had been installed prior to this study. Well A, the pumped well, has an operating irrigation pump and is centrally located among the wells. Wells B, C, D, and E are about 70 ft, 1,390 ft, 2,200 ft, and 3,100 ft, respectively, in different directions from Well A. Using vented pressure transducers and programmable data loggers, water-level data were collected at the five wells prior to, during, and after the pumping, which started on November 19, 1999, and continued a little over 72 hours. Based on available drilling logs, the Elm aquifer near the test area was assumed to be unconfined. The Neuman (1974) method theoretical response curves that most closely match the observed water-level changes at Wells A and B were calculated using software (AQTESOLV for Windows Version 2.13-Professional) developed by Glenn M. Duffield of Hydro

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

USGS Publications Warehouse

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

Hydrologeology and water quality of the Floridan aquifer system and effect of Lower Floridan aquifer pumping on the Upper Floridan aquifer, Pooler, Chatham County, Georgia, 2011–2012

USGS Publications Warehouse

Gonthier, Gerard

2012-01-01

Two test wells were completed in Pooler, Georgia, in 2011 to investigate the potential of using the Lower Floridan aquifer as a source of water for municipal use. One well was completed in the Lower Floridan aquifer at a depth of 1,120 feet (ft) below land surface; the other well was completed in the Upper Floridan aquifer at a depth of 486 ft below land surface. At the Pooler test site, the U.S. Geological Survey performed flowmeter surveys, packer-isolated slug tests within the Lower Floridan confining unit, slug tests of the entire Floridan aquifer system, and aquifer tests of the Upper and Lower Floridan aquifers. Drill cuttings, geophysical logs, and borehole flowmeter surveys indicate that the Upper Floridan aquifer extends 333 –515 ft below land surface, the Lower Floridan confining unit extends 515–702 ft below land surface, and the Lower Floridan aquifer extends 702–1,040 ft below land surface. Flowmeter surveys indicate that the Upper Floridan aquifer contains two water-bearing zones at depth intervals of 339 –350 and 375–515 ft; the Lower Floridan confining unit contains one zone at a depth interval of 550–620 ft; and the Lower Floridan aquifer contains five zones at depth intervals of 702–745, 745–925, 925–984, 984–1,015, and 1,015–1,040 ft. Flowmeter testing of the test borehole open to the entire Floridan aquifer system indicated that the Upper Floridan aquifer contributed 92.4 percent of the total flow rate of 708 gallons per minute; the Lower Floridan confining unit contributed 3.0 percent; and the Lower Floridan aquifer contributed 4.6 percent. Horizontal hydraulic conductivity of the Lower Floridan confining unit derived from slug tests within three packer-isolated intervals ranged from 0.5 to 10 feet per day (ft/d). Aquifer-test analyses yielded values of transmissivity for the Upper Floridan aquifer, Lower Floridan confining unit, and the Lower Floridan aquifer of 46,000, 700, and 4,000 feet squared per day (ft2/d

Non-linear wave interaction in a plasma column

NASA Technical Reports Server (NTRS)

Larsen, J.-M.; Crawford, F. W.

1979-01-01

Non-linear three-wave interaction is analysed for propagation along a cylindrical plasma column surrounded by an infinite dielectric, in the absence of a static magnetic field. An averaged-Lagrangian method is used, and the results are specialized to parametric interaction and mode conversion, assuming an undepleted pump wave. The theory for these two types of interactions is extended to include imperfect synchronism, and the effects of loss. Computations are presented indicating that parametric growth rates of the order of a fraction of a decibel per centimeter should be obtainable for plausible laboratory plasma column parameters.

Using Novel Laboratory Incubations and Field Experiments to Identify the Source and Fate of Reactive Organic Carbon in an Arsenic-contaminated Aquifer System

NASA Astrophysics Data System (ADS)

Stahl, M.; Tarek, M. H.; Badruzzaman, B.; Harvey, C. F.

2017-12-01

Characterizing the sources and fate of organic matter (OM) within aquifer systems is key to our understanding of both the broader global carbon cycle as well as the quality of our groundwater resources. The linkage between the subsurface carbon cycle and groundwater quality is perhaps nowhere more apparent than in the aquifer systems of South and Southeast Asia, where the contamination of groundwater with geogenic arsenic (As) is widespread and threatens the health of millions of individuals. OM fuels the biogeochemical processes driving As mobilization within these aquifers, however the source (i.e., modern surface-derived or aged sedimentary OM) of the reactive OM is widely debated. To characterize the sources of OM driving aquifer redox processes we tracked DIC and DOC concentrations and isotopes (stable and radiocarbon) along groundwater flow-paths and beneath an instrumented study pond at a field site in Bangladesh. We also conducted a set of novel groundwater incubation experiments, where we carbon-dated the DOC at the start and end of a experiment in order to determine the age of the OM that was mineralized. Our carbon/isotope balance reveals that aquifer recharge introduces a large quantity of young (i.e. near modern) OM that is efficiently mineralized within the upper few meters of the aquifer, effectively limiting this pool of reactive surface-sourced OM from being transported deeper into the aquifer where significant As mobilization takes place. The OM mineralized past the upper few meters is an aged, sedimentary source. Consistent with our field data, our incubation experiments show that past the upper few meters of the aquifer the reactive DOC is significantly older than the bulk DOC and has an age consistent with sedimentary OM. Combining our novel set of incubation experiments and a carbon/isotope balance along groundwater flow-paths and beneath our study pond we have identified the sources of reactive OM across different aquifer depths in a

Arsenic Attenuation By Oxidized Aquifer Sediments in Bangladesh

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stollenwerk, K.G.; Breit, G.N.; Welch, A.H.

2007-07-13

Recognition of arsenic (As) contamination of shallow fluvio-deltaic aquifers in the Bengal Basin has resulted in increasing exploitation of groundwater from deeper aquifers that generally contain low concentrations of dissolved As. Pumping-induced infiltration of high-As groundwater could eventually cause As concentrations in these aquifers to increase. This study investigates the adsorption capacity for As of sediment from a low-As aquifer near Dhaka, Bangladesh. A shallow, chemically-reducing aquifer at this site extends to a depth of 50 m and has maximum As concentrations in groundwater of 900 {micro}g/L. At depths greater than 50 m, geochemical conditions are more oxidizing and groundwatermore » has < 5 {micro}g/L As. There is no thick layer of clay at this site to inhibit vertical transport of groundwater. Arsenite [As(III)] is the dominant oxidation state in contaminated groundwater; however, data from laboratory batch experiments show that As(III) is oxidized to arsenate [As(V)] by manganese (Mn) minerals that are present in the oxidized sediment. Thus, the long-term viability of the deeper aquifers as a source of water supply is likely to depend on As(V) adsorption. The adsorption capacity of these sediments is a function of the oxidation state of As and the concentration of other solutes that compete for adsorption sites. Arsenite that was not oxidized did adsorb, but to a much lesser extent than As(V). Phosphate (P) caused a substantial decrease in As(V) adsorption. Increasing pH and concentrations of silica (Si) had lesser effects on As(V) adsorption. The effect of bicarbonate (HCO{sub 3}) on As(V) adsorption was negligible. Equilibrium constants for adsorption of As(V), As(III), P, Si, HCO3, and H were determined from the experimental data and a quantitative model developed. Oxidation of As(III) was modeled with a first-order rate constant. This model was used to successfully simulate As(V) adsorption in the presence of multiple competing solutes

AUTOMATED WATER LEVEL MEASUREMENTS IN SMALL-DIAMETER AQUIFER TUBES

DOE Office of Scientific and Technical Information (OSTI.GOV)

PETERSEN SW; EDRINGTON RS; MAHOOD RO

2011-01-14

Groundwater contaminated with hexavalent chromium, strontium-90, and uranium discharges into the Columbia River along approximately 16 km (10 mi) of the shoreline. Various treatment systems have and will continue to be implemented to eliminate the impact of Hanford Site contamination to the river. To optimize the various remediation strategies, it is important to understand interactions between groundwater and the surface water of the Columbia River. An automated system to record water levels in aquifer sampling tubes installed in the hyporheic zone was designed and tested to (1) gain a more complete understanding of groundwater/river water interactions based on gaining andmore » losing conditions ofthe Columbia River, (2) record and interpret data for consistent and defensible groundwater/surface water conceptual models that may be used to better predict subsurface contaminant fate and transport, and (3) evaluate the hydrodynamic influence of extraction wells in an expanded pump-and-treat system to optimize the treatment system. A system to measure water levels in small-diameter aquifer tubes was designed and tested in the laboratory and field. The system was configured to allow manual measurements to periodically calibrate the instrument and to permit aquifer tube sampling without removing the transducer tube. Manual measurements were collected with an e-tape designed and fabricated especially for this test. Results indicate that the transducer system accurately records groundwater levels in aquifer tubes. These data are being used to refine the conceptual and numeric models to better understand interactions in the hyporheic zone of the Columbia River and the adjacent river water and groundwater, and changes in hydrochemistry relative to groundwater flux as river water recharges the aquifer and then drains back out in response to changes in the river level.« less

VIEW OF TWO HEAVY WATER STORAGE TANKS (BEHIND SUPPORT COLUMNS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF TWO HEAVY WATER STORAGE TANKS (BEHIND SUPPORT COLUMNS AND STEEL BEAMS), SUB-BASEMENT LEVEL -27’, LOOKING SOUTHWEST - Physics Assembly Laboratory, Area A/M, Savannah River Site, Aiken, Aiken County, SC

U(VI) adsorption on aquifer sediments at the Hanford Site.

PubMed

Um, Wooyong; Serne, R Jeffrey; Brown, Christopher F; Last, George V

2007-08-15

Aquifer sediments collected via split-spoon sampling in two new groundwater wells in the 200-UP-1 operable unit at the Hanford Site were characterized and showed typical Ringold Unit E Formation properties dominated by gravel and sand. High iron-oxide content in Fe oxide/clay coatings caused the highest U(VI) adsorption as quantified by batch K(d) values, indicating iron oxides are the key solid adsorbent in the 200-UP-1 sediments that affect U(VI) fate and mobility. Even though U(VI) adsorption on the gravel-sized fraction of the sediments is considered to be negligible, careful characterization should be conducted to determine U(VI) adsorption on gravel, because of presence of Fe oxides coatings and diffusion-controlled adsorption into the gravel particles' interior surfaces. A linear adsorption isotherm was observed up to 10(-6) M (238 microg/L) of total U(VI) concentration in batch U(VI) adsorption tests with varying total U(VI) concentrations in spiked groundwater. U(VI) adsorption decreased with increasing concentrations of dissolved carbonate, because strong anionic aqueous uranium-carbonate complexes formed at high pH and high alkalinity conditions. Noticeable uranium desorption hysteresis was observed in a flow-through column experiment, suggesting that desorption K(d) values for aged uranium-contaminated sediments at the Hanford Site can be larger than adsorption K(d) values determined in short-term laboratory experiments and slow uranium release from contaminated sediments into the groundwater is expected.

Effects of effluent organic matter characteristics on the removal of bulk organic matter and selected pharmaceutically active compounds during managed aquifer recharge: Column study

NASA Astrophysics Data System (ADS)

Maeng, Sung Kyu; Sharma, Saroj K.; Abel, Chol D. T.; Magic-Knezev, Aleksandra; Song, Kyung-Guen; Amy, Gary L.

2012-10-01

Soil column experiments were conducted to investigate the effects of effluent organic matter (EfOM) characteristics on the removal of bulk organic matter (OM) and pharmaceutically active compounds (PhACs) during managed aquifer recharge (MAR) treatment processes. The fate of bulk OM and PhACs during an MAR is important to assess post-treatment requirements. Biodegradable OM from EfOM, originating from biological wastewater treatment, was effectively removed during soil passage. Based on a fluorescence excitation-emission matrix (F-EEM) analysis of wastewater effluent-dominated (WWE-dom) surface water (SW), protein-like substances, i.e., biopolymers, were removed more favorably than fluorescent humic-like substances under oxic compared to anoxic conditions. However, there was no preferential removal of biopolymers or humic substances, determined as dissolved organic carbon (DOC) observed via liquid chromatography with online organic carbon detection (LC-OCD) analysis. Most of the selected PhACs exhibited removal efficiencies of greater than 90% in both SW and WWE-dom SW. However, the removal efficiencies of bezafibrate, diclofenac and gemfibrozil were relatively low in WWE-dom SW, which contained more biodegradable OM than did SW (copiotrophic metabolism). Based on this study, low biodegradable fractions such as humic substances in MR may have enhanced the degradation of diclofenac, gemfibrozil and bezafibrate by inducing an oligotrophic microbial community via long term starvation. Both carbamazepine and clofibric acid showed persistent behaviors and were not influenced by EfOM.

Specific Yield--Column drainage and centrifuge moisture content

USGS Publications Warehouse

Johnson, A.I.; Prill, R.C.; Morris, D.A.

1963-01-01

The specific yield of a rock or soil, with respect to water, is the ratio of (1) the volume of water which, after being saturated, it will yield by gravity to (2) its own volume. Specific retention represents the water retained against gravity drainage. The specific yield and retention when added together are equal to the total interconnected porosity of the rock or soil. Because specific retention is more easily determined than specific yield, most methods for obtaining yield first require the determination of specific retention. Recognizing the great need for developing improved methods of determining the specific yield of water-bearing materials, the U.S. Geological Survey and the California Department of Water Resources initiated a cooperative investigation of this subject. The major objectives of this research are (1) to review pertinent literature on specific yield and related subjects, (2) to increase basic knowledge of specific yield and rate of drainage and to determine the most practical methods of obtaining them, (3) to compare and to attempt to correlate the principal laboratory and field methods now commonly used to obtain specific yield, and (4) to obtain improved estimates of specific yield of water-bearing deposits in California. An open-file report, 'Specific yield of porous media, an annotated bibliography,' by A. I. Johnson, D. A. Morris, and R. C. Prill, was released in 1960 in partial fulfillment of the first objective. This report describes the second phase of the specific-yield study by the U.S. Geological Survey Hydrologic Laboratory at Denver, Colo. Laboratory research on column drainage and centrifuge moisture equivalent, two methods for estimating specific retention of porous media, is summarized. In the column-drainage study, a wide variety of materials was packed into plastic columns of 1- to 8-inch diameter, wetted with Denver tap water, and drained under controlled conditions of temperature and humidity. The effects of cleaning the

Monitoring Aquifer Depletion from Space: Case Studies from the Saharan and Arabian Aquifers

NASA Astrophysics Data System (ADS)

Ahmed, M.; Sultan, M.; Wahr, J. M.; Yan, E.

2013-12-01

Access to potable fresh water resources is a human right and a basic requirement for economic development in any society. In arid and semi-arid areas, the characterization and understanding of the geologic and hydrologic settings of, and the controlling factors affecting, these resources is gaining increasing importance due to the challenges posed by increasing population. In these areas, there is immense natural fossil fresh water resources stored in large extensive aquifers, the transboundary aquifers. Yet, natural phenomena (e.g., rainfall patterns and climate change) together with human-related factors (e.g., population growth, unsustainable over-exploitation, and pollution) are threatening the sustainability of these resources. In this study, we are developing and applying an integrated cost-effective approach to investigate the nature (i.e., natural and anthropogenic) and the controlling factors affecting the hydrologic settings of the Saharan (i.e., Nubian Sandstone Aquifer System [NSAS], Northwest Sahara Aquifer System [NWSA]) and Arabian (i.e., Arabian Peninsula Aquifer System [APAS]) aquifer systems. Analysis of the Gravity Recovery and Climate Experiment (GRACE)-derived Terrestrial Water Storage (TWS) inter-annual trends over the NSAS and the APAS revealed two areas of significant TWS depletions; the first correlated with the Dakhla Aquifer System (DAS) in the NSAS and second with the Saq Aquifer System (SAS) in the APAS. Annual depletion rates were estimated at 1.3 × 0.66 × 109 m3/yr and 6.95 × 0.68 × 109 m3/yr for DAS and SAS, respectively. Findings include (1) excessive groundwater extraction, not climatic changes, is responsible for the observed TWS depletions ;(2) the DAS could be consumed in 350 years if extraction rates continue to double every 50 years and the APAS available reserves could be consumed within 60-140 years at present extraction (7.08 × 109 m3/yr) and depletion rates; and (3) observed depletions over DAS and SAS and their

Column Chromatography To Obtain Organic Cation Sorption Isotherms.

PubMed

Jolin, William C; Sullivan, James; Vasudevan, Dharni; MacKay, Allison A

2016-08-02

Column chromatography was evaluated as a method to obtain organic cation sorption isotherms for environmental solids while using the peak skewness to identify the linear range of the sorption isotherm. Custom packed HPLC columns and standard batch sorption techniques were used to intercompare sorption isotherms and solid-water sorption coefficients (Kd) for four organic cations (benzylamine, 2,4-dichlorobenzylamine, phenyltrimethylammonium, oxytetracycline) with two aluminosilicate clay minerals and one soil. A comparison of Freundlich isotherm parameters revealed isotherm linearity or nonlinearity was not significantly different between column chromatography and traditional batch experiments. Importantly, skewness (a metric of eluting peak symmetry) analysis of eluting peaks can establish isotherm linearity, thereby enabling a less labor intensive means to generate the extensive data sets of linear Kd values required for the development of predictive sorption models. Our findings clearly show that column chromatography can reproduce sorption measures from conventional batch experiments with the benefit of lower labor-intensity, faster analysis times, and allow for consistent sorption measures across laboratories with distinct chromatography instrumentation.

Digital data set that describe aquifer characteristics of the Antlers aquifer in southeastern Oklahoma

USGS Publications Warehouse

Abbott, Marvin M.; Runkle, D.L.; Rea, Alan

1997-01-01

ARC/INFO export and nonproprietary format file This diskette contains digitized aquifer boundaries and maps of hydraulic conductivity, recharge, and ground-water level elevation contours for the Antlers aquifer in southeastern Oklahoma. The Early Cretaceous-age Antlers Sandstone is an important source of water in an area that underlies about 4,400-square miles of all or part of Atoka, Bryan, Carter, Choctaw, Johnston, Love, Marshall, McCurtain, and Pushmataha Counties. The Antlers aquifer consists of sand, clay, conglomerate, and limestone in the outcrop area. The upper part of the Antlers aquifer consists of beds of sand, poorly cemented sandstone, sandy shale, silt, and clay. The Antlers aquifer is unconfined where it outcrops in about an 1,800-square-mile area. The recharge, hydraulic conductivity, and aquifer boundaries data sets include the outcrop area of the Antlers Sandstone in Oklahoma and areas where the Antlers is overlain by alluvial and terrace deposits and a few small thin outcrops of the Goodland Limestone. Most of the lines in these data sets were extracted from published digital geology data sets. Some of the lines were interpolated in areas where the Antlers aquifer is overlain by alluvial and terrace deposits near streams and rivers. The interpolated lines are very similar to the aquifer boundaries published in a ground-water modeling report for the Antlers aquifer. The maps from which this data set was derived were scanned or digitized from maps published at a scale of 1:250,000. The water-level elevation contours were digitized from a map at a scale of 1:250,000 that was used to prepare the final map published in a ground-water flow model report. Hydraulic conductivity and recharge values also are published in the ground-water model report for the Antlers aquifer. Ground-water flow models are numerical representations that simplify and aggregate natural systems. Models are not unique; different combinations of aquifer characteristics may

Influence of humic substances on electrochemical degradation of trichloroethylene in limestone aquifers

PubMed Central

Rajic, Ljiljana; Fallahpour, Noushin; Nazari, Roya; Alshawabkeh, Akram N.

2015-01-01

In this study we investigate the influence of humic substances (HS) on electrochemical transformation of trichloroethylene (TCE) in groundwater from limestone aquifers. A laboratory flow-through column with an electrochemical reactor that consists of a palladized iron foam cathode followed by a MMO anode was used to induce TCE electro-reduction in groundwater. Up to 82.9% TCE removal was achieved in the absence of HS. Presence of 1, 2, 5, and 10 mgTOC L−1 reduced TCE removal to 70.9%, 61.4%, 51.8% and 19.5%, respectively. The inverse correlation between HS content and TCE removal was linear. Total organic carbon (TOC), dissolved organic carbon (DOC) and absorption properties (A=254 nm, 365 nm and 436 nm) normalized to DOC, were monitored during treatment to understand the behavior and impacts of HS under electrochemical processes. Changes in all parameters occurred mainly after contact with the cathode, which implies that the HS are reacting either directly with electrons from the cathode or with H2 formed at the cathode surface. Since hydrodechlorination is the primary TCE reduction mechanism in this setup, reactions of the HS with the cathode limit transformation of TCE. The presence of limestone gravel reduced the impact of HS on TCE removal. The study concludes that presence of humic substances adversely affects TCE removal from contaminated groundwater by electrochemical reduction using palladized cathodes. PMID:26549889

Determination of Aflatoxins and Ochratoxin A in Traditional Turkish Concentrated Fruit Juice Products by Multi-Immunoaffinity Column Cleanup and LC Fluorescence Detection: Single-Laboratory Validation.

PubMed

Kaymak, Tugrul; Türker, Levent; Tulay, Hüseyin; Stroka, Joerg

2018-04-27

Background : Pekmez and pestil are traditional Turkish foods made from concentrated grapejuice, which can be contaminated with mycotoxins such as aflatoxins and ochratoxin A (OTA). Objective : To carry out a single-laboratory validation of a method to simultaneously determine aflatoxins B 1 , B₂, G 1 , and G₂ and ochratoxin A in pekmez and pestil. Methods : The homogenized sample is extracted with methanol-water (80 + 20) using a high-speed blender. The (sample) extract is filtered, diluted with phosphate-buffered saline solution, and applied to a multi-immunoaffinity column (AFLAOCHRA PREP®). Aflatoxins and ochratoxin A are removed with (neat) methanol and then directly analyzed by reversed-phase LC with fluorescence detection using post-column bromination (Kobra cell®). Results : Test portions of blank pekmez and pestil were spiked with a mixture of aflatoxins and ochratoxin A to give levels ranging from 2.6 to 10.4 μg/kg and 1.0-4.0 μg/kg, respectively. Recoveries for total aflatoxins and ochratoxin A ranged from 84 to 106% and 80-97%, respectively, for spiked samples. Based on results for spiked pekmez and pestil (30 replicates each at three levels), the repeatability RSD ranged from 1.6 to 12% and 2.7-11% for total aflatoxins and ochratoxin A, respectively. Conclusions : The method performance in terms of recovery, repeatability, and detection limits has been demonstrated to be suitable for use as an Official Method. Highlights : First immunoaffinity column method validated for simultaneous analysis of aflatoxins and ochratoxin A in pekmez and pestil. Suitability for use for official purposes in Turkey, demonstrated by single-laboratory validation. Co-occurrence of aflatoxins and OTA in mulberry and carob pekmez reported for the first time.

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

NASA Astrophysics Data System (ADS)

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

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

USGS Publications Warehouse

Becker, C.J.; Runkle, D.L.; Rea, Alan

1997-01-01

ARC/INFO export files This diskette contains digitized aquifer boundaries and maps of hydraulic conductivity, recharge, and ground-water level elevation contours for the High Plains aquifer in western Oklahoma. This area encompasses the panhandle counties of Cimarron, Texas, and Beaver, and the western counties of Harper, Ellis, Woodward, Dewey, and Roger Mills. The High Plains aquifer underlies approximately 7,000 square miles of Oklahoma and is used extensively for irrigation. The High Plains aquifer is a water-table aquifer and consists predominately of the Tertiary-age Ogallala Formation and overlying Quaternary-age alluvial and terrace deposits. In some areas the aquifer is absent and the underlying Triassic, Jurassic, or Cretaceous-age rocks are exposed at the surface. These rocks are hydraulically connected with the aquifer in some areas. The High Plains aquifer is composed of interbedded sand, siltstone, clay, gravel, thin limestones, and caliche. The proportion of various lithological materials changes rapidly from place to place, but poorly sorted sand and gravel predominate. The rocks are poorly to moderately well cemented by calcium carbonate. The aquifer boundaries, hydraulic conductivity, and recharge data sets were created by extracting geologic contact lines from published digital surficial geology maps based on a scale of 1:125,000 for the panhandle counties and 1:250,000 for the western counties. The water-level elevation contours and some boundary lines were digitized from maps in a published water-level elevation map for 1980 based on a scale of 1:250,000. The hydraulic conductivity and recharge values in this report were used as input to the ground-water flow model on the High Plains aquifer. Ground-water flow models are numerical representations that simplify and aggregate natural systems. Models are not unique; different combinations of aquifer characteristics may produce similar results. Therefore, values of hydraulic conductivity and

Data for ground-water test hole near Nicolaus, Central Valley aquifer project, California

USGS Publications Warehouse

French, James J.; Page, R.W.; Bertoldi, Gilbert L.

1983-01-01

Preliminary data are provided for the third of seven test holes drilled as a part of the Central Valley Aquifer Project which is part of the National Regional Aquifer Systems Analysis Program. The test hole was drilled in the SW 1/4 NE 1/4 sec. 2, T.12N., R.3E., Sutter County, California, about 1 1/2 miles northwest of the town of Nicolaus. Drilled to a depth of 1,150 feet below land surface, the hole is cased to a depth of 100 feet and equipped with three piezometer tubes to depths of 311, 711, and 1,071 feet. A 5-foot well screen is set in sand at the bottom of each piezometer. Each screened interval has a cement plug above and below it to isolate it from other parts of the aquifer, and the well bore is filled between the plugs with sediment. Thirty-one cores and 34 sidewall cores were recovered. Laboratory tests were made for minerology, consolidation, grain-size distribution, Atterberg limits, X-ray diffraction, thermal conductivity, and chemical analysis of water. Geophysical and thermal gradient logs were made. The hole is sampled periodically for chemical analysis of the three tapped zones and measured for water level. This report presents methods used to obtain field samples, laboratory procedures, and the data obtained. (USGS)

Significance of Iron(II,III) Hydroxycarbonate Green Rust in Arsenic Remediation Using Zerovalent Iron in Laboratory Column Tests

EPA Science Inventory

We examined the corrosion products of zerovalent iron used in three column tests for removing arsenic from water under dynamic flow conditions. Each column test lasted three- to four-months using columns consisting of a 10.3-cm depth of 50 : 50 (w : w, Peerless iron : sand) in t...

GRAPHITE BLOCKS ARE ARRAYED IN "THERMAL COLUMN" ON NORTH SIDE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

GRAPHITE BLOCKS ARE ARRAYED IN "THERMAL COLUMN" ON NORTH SIDE OF REACTOR. INL NEGATIVE NO. 4000. Unknown Photographer, 12/28/1951 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

The effect of column purification on cDNA indirect labelling for microarrays

PubMed Central

Molas, M Lia; Kiss, John Z

2007-01-01

Background The success of the microarray reproducibility is dependent upon the performance of standardized procedures. Since the introduction of microarray technology for the analysis of global gene expression, reproducibility of results among different laboratories has been a major problem. Two of the main contributors to this variability are the use of different microarray platforms and different laboratory practices. In this paper, we address the latter question in terms of how variation in one of the steps of a labelling procedure affects the cDNA product prior to microarray hybridization. Results We used a standard procedure to label cDNA for microarray hybridization and employed different types of column chromatography for cDNA purification. After purifying labelled cDNA, we used the Agilent 2100 Bioanalyzer and agarose gel electrophoresis to assess the quality of the labelled cDNA before its hybridization onto a microarray platform. There were major differences in the cDNA profile (i.e. cDNA fragment lengths and abundance) as a result of using four different columns for purification. In addition, different columns have different efficiencies to remove rRNA contamination. This study indicates that the appropriate column to use in this type of protocol has to be experimentally determined. Finally, we present new evidence establishing the importance of testing the method of purification used during an indirect labelling procedure. Our results confirm the importance of assessing the quality of the sample in the labelling procedure prior to hybridization onto a microarray platform. Conclusion Standardization of column purification systems to be used in labelling procedures will improve the reproducibility of microarray results among different laboratories. In addition, implementation of a quality control check point of the labelled samples prior to microarray hybridization will prevent hybridizing a poor quality sample to expensive micorarrays. PMID:17597522

The effect of column purification on cDNA indirect labelling for microarrays.

PubMed

Molas, M Lia; Kiss, John Z

2007-06-27

The success of the microarray reproducibility is dependent upon the performance of standardized procedures. Since the introduction of microarray technology for the analysis of global gene expression, reproducibility of results among different laboratories has been a major problem. Two of the main contributors to this variability are the use of different microarray platforms and different laboratory practices. In this paper, we address the latter question in terms of how variation in one of the steps of a labelling procedure affects the cDNA product prior to microarray hybridization. We used a standard procedure to label cDNA for microarray hybridization and employed different types of column chromatography for cDNA purification. After purifying labelled cDNA, we used the Agilent 2100 Bioanalyzer and agarose gel electrophoresis to assess the quality of the labelled cDNA before its hybridization onto a microarray platform. There were major differences in the cDNA profile (i.e. cDNA fragment lengths and abundance) as a result of using four different columns for purification. In addition, different columns have different efficiencies to remove rRNA contamination. This study indicates that the appropriate column to use in this type of protocol has to be experimentally determined. Finally, we present new evidence establishing the importance of testing the method of purification used during an indirect labelling procedure. Our results confirm the importance of assessing the quality of the sample in the labelling procedure prior to hybridization onto a microarray platform. Standardization of column purification systems to be used in labelling procedures will improve the reproducibility of microarray results among different laboratories. In addition, implementation of a quality control check point of the labelled samples prior to microarray hybridization will prevent hybridizing a poor quality sample to expensive micorarrays.

Characterizing Sources of Recharge and Groundwater Quality in Sacramento Aquifers Following California's Historic Drought

NASA Astrophysics Data System (ADS)

Robertson, C. A.; Paukert Vankeuren, A. N.; Wagner, A. J.; Blackburn, C.; Druecker, D.

2016-12-01

Characterizing recharge will be critical for sustainable groundwater use, particularly following California's historic five-year drought . Groundwater is of great importance to Sacramento, which is a high priority basin as determined by the Sustainable Groundwater Management Act of 2014. The California State University, Sacramento (CSUS) campus has 18 monitoring wells, making it an ideal laboratory for examination of recharge sources and water quality in confined and unconfined aquifers in the Central Valley aquifer system. Historically, CSUS aquifers appear to have been recharged by water from the Western Sierra Nevada. The campus is bounded by the Lower American River, and some of its wells are in hydraulic connection with the river1. Lower than average river stage during the drought may have affected recharge to the aquifers from the river. Additionally, low impact development (LID) stormwater-management ponds have recently been installed on campus in an effort to increase infiltration and to help mitigate contamination of the aquifers and American River from campus runoff. The recently installed LID ponds on campus may have increased infiltration of local precipitation into the unconfined aquifer. Data collected from the monitoring wells allow for the examination of differences between the confined and unconfined aquifer systems in the Central Valley. To identify recharge sources, stable isotope and major ion analyses for samples collected from both campus aquifers are compared to samples from local precipitation and rivers in the Western Sierra Nevada feeding the American River. These results are used to assess current water quality and compared to historic datasets collected by the USGS to reveal changes that have occurred as a result of the recent drought. These data are the first in a dataset developed by CSUS Geology students for long-term monitoring of local groundwater quality. 1Moran et al., 2004. LLNL, UCR-203258.

Investigating Attachment Behaviors of Cryptosporidium Parvum Oocysts Using Collision Efficiency in Laboratory Column Experiments

NASA Astrophysics Data System (ADS)

Park, Y.; Hou, L.; Atwill, R.; Packman, A. I.; Harter, T.

2009-12-01

Cryptosporidium is one of the most common enteric parasites of humans and domestic animals, and a number of outbreaks of Cryprosporidiosis, a diarrheal disease caused by Cryptosporidium have been reported worldwide. Natural porous media has been demonstrated to be an effective filter for removing Cryptosporidium parvum from contaminated water and the amount of Cryptosporidium filtered is known to be highly dependent on physical and chemical conditions of the porous media and the water. Cryptosporidium deposition in saturated porous media involves two main steps: approach and attachment. In contrast to the approach mechanisms, attachment processes have not been systematically described to predict a priori because theories that represent attachment behavior (colloid stability) such as DLVO are insufficient to explain experimental data. For this reason, attachment efficiency is calculated based on empirical data, typically experimental breakthrough curves in laboratory columns or field experiments. In this study, collision (attachment) efficiencies (α) of C. parvum oocyst were calculated to test the effect of chemical property changes on the association of oocysts with sand grains. The breakthrough curve data obtained from twelve column experiments and three models were employed to calculate single collector efficiency (η) and α. The first ten experiments were conducted by changing ionic strength and pH, and mixing with natural sediments under the same physical properties (same η). Our experiment results show that iron coating or clay/suspended solids mixture drastically enhanced oocyst deposition. The experiments also showed that increase in ionic strength and decrease in pH enhanced the attachment efficiency. However, the experiment with 100mM NaCl resulted in low attachment efficiency and the experiment with pH 8.5 showed similar attachment efficiency to the one at pH 7. Based on the results from two additional experiments with different flow velocities, it

Enhanced reductive dechlorination in columns treated with edible oil emulsion

NASA Astrophysics Data System (ADS)

Long, Cameron M.; Borden, Robert C.

2006-09-01

The effect of edible oil emulsion treatment on enhanced reductive dechlorination was evaluated in a 14 month laboratory column study. Experimental treatments included: (1) emulsified soybean oil and dilute HCl to inhibit biological activity; (2) emulsified oil only; (3) emulsified oil and anaerobic digester sludge; and (4) continuously feeding soluble substrate. A single application of emulsified oil was effective in generating strongly reducing, anaerobic conditions for over 14 months. PCE was rapidly reduced to cis-DCE in all three live columns. Bioaugmentation with a halorespiring enrichment culture resulted in complete dechlorination of PCE to ethene in the soluble substrate column (yeast extract and lactate). However, an additional treatment with a pulse of yeast extract and bioaugmentation culture was required to stimulate complete dechlorination in the emulsion treated columns. Once the dechlorinating population was established, the emulsion only column degraded PCE from 90-120 μM to below detection with concurrent ethene production in a 33 day contact time. The lower biodegradation rates in the emulsion treated columns compared to the soluble substrate column suggest that emulsified oil barriers may require a somewhat longer contact time for effective treatment. In the HCl inhibited column, partitioning of PCE to the retained oil substantially delayed PCE breakthrough. However, reduction of PCE to more soluble degradation products ( cis-DCE, VC and ethene) greatly reduced the impact of oil-water partitioning in live columns. There was only a small decline in the hydraulic conductivity ( K) of column #1 (low pH + emulsion, Kfinal/ Kinitial = 0.57) and column #2 (live + emulsion, Kfinal/ Kinitial = 0.73) indicating emulsion injection did not result in appreciable clogging of the clayey sand. However, K loss was greater in column #3 (sludge +emulsion, Kfinal/ Kinitial = 0.12) and column #4 (soluble substrate, Kfinal/ Kinitial = 0.03) indicating clogging due

Hydrogeochemical Analysis of an Overexploited Aquifer In Bangladesh Toward Managed Aquifer Recharge Project Implementation

NASA Astrophysics Data System (ADS)

Rahman, M. A.; Wiegand, B. A.; Pervin, M.; Sauter, M.

2012-12-01

In most parts of the upper Dupitila aquifer (Dhaka City, Bangladesh) the average groundwater depletion reaches 2-3 m/year due to increasing water demands of the growing population. To counteract overexploitation of the aquifer, a more sustainable water management is required. The analysis of the local water resources system suggests that Managed Aquifer Recharge (MAR) would help to restore groundwater resources to strengthen water supply of Dhaka City, e.g., by using collected urban monsoon runoff and excess surface water from rivers. To assess possible effects of surface water or rainwater injection on groundwater quality, a comprehensive hydrogeochemical survey of the Dupitila aquifer is required. This paper presents hydrogeochemical data to document the current status of groundwater quality and to evaluate potential groundwater pollution by mobilization of hazardous chemicals as a result of changes in the hydrochemical equilibria. We performed a comprehensive review of available secondary data sources and will present new results from hydrochemical and Sr isotope investigations of water samples that were conducted within this study. Currently, groundwater quality in the upper Dupitila aquifer is characterized by variations in the electrical conductivity in the range of 200 to 1100 μS/cm, which may indicate some anthropogenic contamination by leakage from waste disposal including the sewage network and from surface water infiltration into the groundwater aquifer. Dissolved oxygen concentrations range from 1.0 to 4.9 mg/L (average 2.5 mg/L) in the upper Dupitila aquifer, while the lower Dupilita aquifer shows dissolved oxygen concentrations in the range 0 to 0.7 mg/L. Concentrations of major ions show some variation primarily due to a sedimentologically/mineralogically heterogeneous aquifer composition (sand, gravel, clay horizons), but may also be affected by anthropogenic processes. The groundwater composition is predominated by Ca-Mg-HCO3 and saturation values

Application of laboratory permeability data

USGS Publications Warehouse

Johnson, A.I.

1963-01-01

Some of the basic material contained in this report originally was prepared in 1952 as instructional handouts for ground-water short courses and for training of foreign participants. The material has been revised and expanded and is presented in the present form to make it more readily available to the field hydrologist. Illustrations now present published examples of the applications suggested in the 1952 material. For small areas, a field pumping test is sufficient to predict the characteristics of an aquifer. With a large area under study, the aquifer properties must be determined at many different locations and it is not usually economically feasible to make sufficient field tests to define the aquifer properties in detail for the whole aquifer. By supplementing a few field tests with laboratory permeability data and geologic interpretation, more point measurements representative of the hydrologic properties of the aquifer may be obtained. A sufficient number of samples seldom can be obtained to completely identify the permeability or transmissibility in detail for a project area. However, a few judiciously chosen samples of high quality, combined with good geologic interpretation, often will permit the extrapolation of permeability information over a large area with a fair degree of reliability. The importance of adequate geologic information, as well as the importance of collecting samples representative of at least all major textural units lying within the section or area of study, cannot be overemphasized.

Effects of slow recovery rates on water column geochemistry in aquitard wells

USGS Publications Warehouse

Schilling, K.E.

2011-01-01

Monitoring wells are often installed in aquitards to verify effectiveness for preventing migration of surface contaminants to underlying aquifers. However, water sampling of aquitard wells presents a challenge due to the slow recovery times for water recharging the wells, which can take as long as weeks, months or years to recharge depending on the sample volume needed. In this study, downhole profiling and sampling of aquitard wells was used to assess geochemical changes that occur in aquitard wells during water level recovery. Wells were sampled on three occasions spanning 11years, 1year and 1week after they were purged and casing water showed substantial water chemistry variations. Temperature decreased with depth, whereas pH and specific conductance increased with depth in the water column after 11years of water level recovery. Less stable parameters such as dissolved O2 (DO) and Eh showed strong zonation in the well column, with DO stratification occurring as the groundwater slowly entered the well. Oxidation of reduced till groundwater along with degassing of CO2 from till pore water affects mineral solubility and dissolved solid concentrations. Recommendations for sampling slowly recovering aquitard wells include identifying the zone of DO and Eh stratification in the well column and collecting water samples from below the boundary to better measure unstable geochemical parameters. ?? 2011 Elsevier Ltd.

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

USGS Publications Warehouse

Becker, C.J.; Runkle, D.L.; Rea, Alan

1997-01-01

ARC/INFO export and nonproprietary format files The data sets in this report include digitized aquifer boundaries and maps of hydraulic conductivity, recharge, and ground-water level elevation contours for the Enid isolated terrace aquifer in northwestern Oklahoma. The Enid isolated terrace aquifer covers approximately 82 square miles and supplies water for irrigation, domestic, municipal, and industrial use for the City of Enid and western Garfield County. The Quaternary-age Enid isolated terrace aquifer is composed of terrace deposits that consist of discontinuous layers of clay, sandy clay, sand, and gravel. The aquifer is unconfined and is bounded by the underlying Permian-age Hennessey Group on the east and the Cedar Hills Sandstone Formation of the Permian-age El Reno Group on the west. The Cedar Hills Sandstone Formation fills a channel beneath the thickest section of the Enid isolated terrace aquifer in the midwestern part of the aquifer. All of the data sets were digitized and created from information and maps in a ground-water modeling thesis and report of the Enid isolated terrace aquifer. The maps digitized were published at a scale of 1:62,500. Ground-water flow models are numerical representations that simplify and aggregate natural systems. Models are not unique; different combinations of aquifer characteristics may produce similar results. Therefore, values of hydraulic conductivity and recharge used in the model and presented in this data set are not precise, but are within a reasonable range when compared to independently collected data.

Delineation and description of the regional aquifer systems of Tennessee; Cumberland Plateau aquifer system

USGS Publications Warehouse

Brahana, J.V.; Macy, J.A.; Mulderink, Dolores; Zemo, Dawn

1986-01-01

The Cumberland Plateau aquifer system consists of Pennsylvanian sandstones, conglomerates, shales, and coals which underlie the Cumberland Plateau in Tennessee. Major water-bearing zones occur within the sandstones and conglomerates in interconnected fractures. The water-bearing formations are separated by shale and siltstone that retard the vertical circulation of ground water, The Pennington Formation serves as the base of this aquifer system and is an effective confining unit, The Cumberland Plateau aquifer system is an important water source for the Cumberland Plateau, wells and springs from the aquifer system supply most of the rural domestic and public drinking-water supplies, water from wells drilled into the Cumberland Plateau aquifer system is generally of good to excellent quality. Of the 32 water-quality analyses on file from this aquifer. only 2 had dissolved-solids concentrations greater than 500 milligrams per liter, and about three-fourths had less than 200 milligrams per liter dissolved solids, However, no samples from depths greater than 300 feet below land surface have been recorded. Ground water from locations where the sandstones are buried deeply, such as the Wartburg basin, may contain dissolved-solids concentrations greater than 1,000 milligrams per liter.

Preliminary delineation and description of the regional aquifers of Tennessee : Cumberland Plateau aquifer system

USGS Publications Warehouse

Brahana, J.V.; Macy, Jo Ann; Mulderink, Dolores; Zemo, Dawn

1986-01-01

The Cumberland Plateau aquifer system consists of Pennsylvanian sandstones, conglomerates, shales, and coals which underlie the Cumberland Plateau in Tennessee. Major water-bearing zones occur within the sandstones and conglomerates in interconnected fractures. The water-bearing formations are separated by shale and siltstone that retard the vertical circulation of ground water. The Pennington Formation serves as the base of this aquifer system and is an effective confining unit. The Cumberland Plateau aquifer system is an important water source for the Cumberland Plateau. Wells and springs from the aquifer system supply most of the rural domestic and public drinking-water supplies. Water from wells drilled into the Cumberland Plateau aquifer system is generally of good to excellent quality. Of the 32 water-quality analyses on file from this aquifer, only 2 had dissolved-solids concentrations greater than 500 milligrams per liter, and about three-fourths had less than 200 milligrams per liter dissolved solids. However, no samples from depths greater than 300 feet below land surface have been recorded. Ground water from locations where the sandstones are buried deeply, such as the Wartburg basin, may contain dissolved-solids concentrations greater than 1,000 milligrams per liter.

Measurement of bromate in bread by liquid chromatography with post-column flow reactor detection.

PubMed

Himata, K; Noda, M; Ando, S; Yamada, Y

2000-01-01

This method is suitable for the determination of bromate residues in a variety of baked goods. The peer-verified method trial was performed on white bread, multigrain bread, and coffee cake spiked with known levels of potassium bromate. The analytical portion is extracted with deionized water to remove bromate from the bulk of the baked product. The aqueous extract is carried through a series of steps to remove co-extractives that would interfere with the liquid chromatography (LC) in the determinative step or hasten the deterioration of the LC column. The extract is filtered before passing it through a reversed-phase solid-phase extraction (SPE) column and a cation-exchange column in the silver form to remove lipids and chloride, respectively. Ultrafiltration is then used to remove proteins with molecular weights of >30,000 daltons. Finally, a cation-exchange column in the sodium form is used to remove silver ions from the extract. The determinative step uses LC with a reversed-phase column and an ion-pairing agent in the mobile phase. Detection is based on the post-column reaction of bromate with o-dianisidine to form an oxidation product that is quantitated spectrophotometrically at 450 nm. Overall agreement between the submitting and peer laboratories was quite good. For bromate levels of 10-52 ppb, overall mean recoveries were 76.9 and 78.8% for the submitting and peer laboratories, respectively. The standard deviations were higher for the results of the peer laboratory, probably because of the generally higher level of baseline noise present in the chromatograms. The results demonstrate that the method provides adequate accuracy with low-fat as well as high-fat foods. Bromate at levels as low as 5 ppb (ng/g) can be detected with the method.

Settling behavior of unpurified Cryptosporidium oocysts in laboratory settling columns.

PubMed

Young, Pamela L; Komisar, Simeon J

2005-04-15

The settling behavior of fresh and aged unpurified oocysts was examined in settling column suspensions with varied ionic strengths and concentrations of calcium and magnesium. Independent measurements of the size and density of unpurified oocysts were performed to determine a theoretical settling velocity for the test populations. Viability of the oocysts was assessed using a dye permeability assay. Latex microspheres were included to provide a standard by which to assess the settling conditions in the columns. Mean settling velocities for viable oocysts measured in this work were faster than predicted and faster than measured for purified oocysts in other work: 1.31 (+/-0.21) microm/s for viable oocysts from populations having a low percentage of viable oocysts and 1.05 (+/-0.20) microm/s for viable oocysts from populations with a high percentage of viable oocysts. Results were attributed to the higher than previously reported densities measured for oocysts in this study and the presence of fecal material, which allowed opportunity for particle agglomeration. Settling velocity of oocysts was significantly related to the viability of the population, particle concentration, ionic strength, and presence of calcium and magnesium in the suspending medium. Behavior of the latex microspheres was not entirely predictive of the behavior of the oocysts under the test conditions. Viable oocysts may have a greater probability of settling than previously assumed; however, nonviable, and especially nonintact, oocysts have the potential to be significantly transported in water. This work underscores the importance of assessing the viability of oocysts to predict their response to environmental and experimental conditions.

MOLECULAR ANALYSIS OF MICROBIAL COMMUNITY STRUCTURES IN PRISTINE AND CONTAMINATED AQUIFERS: FIELD AND LABORATORY MICROCOSM EXPERIMENTS

EPA Science Inventory

This study used phylogenetic probes in hybridization analysis to (i) determine in situ microbial community structures in regions of a shallow sand aquifer that were oxygen depleted and fuel contaminated (FC) or aerobic and noncontaminted (NC) and (ii) examine alterations in micro...

A field, laboratory and modeling study of reactive transport of groundwater arsenic in a coastal aquifer

PubMed Central

Jung, Hun Bok; Charette, Matthew A.; Zheng, Yan

2009-01-01

A field, laboratory, and modeling study of As in groundwater discharging to Waquoit Bay, MA, shed light on coupled control of chemistry and hydrology on reactive transport of As in a coastal aquifer. Dissolved Fe(II) and As(III) in a reducing groundwater plume bracketed by an upper and a lower redox interface are oxidized as water flows towards the bay. This results in precipitation of Fe(III) oxides, along with oxidation and adsorption of As to sediment at the redox interfaces where concentrations of sedimentary HCl-leachable Fe (80~90% Fe(III)) are 734±232 mg kg-1, sedimentary phosphate extractable As (90~100% As(V)) are 316±111 μg kg-1, and are linearly correlated. Batch adsorption of As(III) onto orange, brown and gray sediments follows Langmuir isotherms, and can be fitted by a surface complexation model (SCM) assuming a diffuse layer for ferrihydrite. The sorption capacity and distribution coefficient for As increase with decreasing sediment Fe(II)/Fe. To allow accumulation of the amount of sediment As, similar hydrogeochemical conditions would have been operating for thousands of years at Waquoit Bay. The SCM simulated the observed dissolved As concentration better than a parametric approach based on Kd. Site specific isotherms should be established for Kd or SCM based models. PMID:19708362

Digital data sets that describe aquifer characteristics of the Central Oklahoma Aquifer in central Oklahoma

USGS Publications Warehouse

Runkle, D.L.; Christenson, S.C.; Rea, Alan

1997-01-01

ARC/INFO export files The data sets in this report include digitized aquifer boundaries and maps of hydraulic conductivity, recharge, and ground-water level elevation contours for the Central Oklahoma aquifer in central Oklahoma. This area encompasses all or part of Cleveland, Lincoln, Logan, Oklahoma, Payne, and Pottawatomie Counties. The Central Oklahoma aquifer includes the alluvial and terrace deposits along major streams, the Garber Sandstone and Wellington Formations, and the Chase, Council Grove, and Admire Groups. The Quaternary-age alluvial and terrace deposits consist of unconsolidated clay, silt, sand, and gravel. The Permian-age Garber Sandstone and Wellington Formations consist of sandstone with interbedded siltstone and mudstone. The Permian-age Chase, Council Grove, and Admire Groups consist of sandstone, shale, and thin limestone. The Central Oklahoma aquifer underlies about 3,000 square miles of central Oklahoma where the aquifer is used extensively for municipal, industrial, commercial, and domestic water supplies. Most of the usable ground water within the aquifer is from the Garber Sandstone and Wellington Formations. Substantial quantities of usable ground water also are present in the Chase, Council Grove, and Admire Groups, and in alluvial and terrace deposits associated with the major streams. The aquifer boundaries, hydraulic conductivity and recharge values, and ground-water level elevation contours are from previously published reports.

Modeling Stone Columns.

PubMed

Castro, Jorge

2017-07-11

This paper reviews the main modeling techniques for stone columns, both ordinary stone columns and geosynthetic-encased stone columns. The paper tries to encompass the more recent advances and recommendations in the topic. Regarding the geometrical model, the main options are the "unit cell", longitudinal gravel trenches in plane strain conditions, cylindrical rings of gravel in axial symmetry conditions, equivalent homogeneous soil with improved properties and three-dimensional models, either a full three-dimensional model or just a three-dimensional row or slice of columns. Some guidelines for obtaining these simplified geometrical models are provided and the particular case of groups of columns under footings is also analyzed. For the latter case, there is a column critical length that is around twice the footing width for non-encased columns in a homogeneous soft soil. In the literature, the column critical length is sometimes given as a function of the column length, which leads to some disparities in its value. Here it is shown that the column critical length mainly depends on the footing dimensions. Some other features related with column modeling are also briefly presented, such as the influence of column installation. Finally, some guidance and recommendations are provided on parameter selection for the study of stone columns.

Modeling Stone Columns

PubMed Central

2017-01-01

This paper reviews the main modeling techniques for stone columns, both ordinary stone columns and geosynthetic-encased stone columns. The paper tries to encompass the more recent advances and recommendations in the topic. Regarding the geometrical model, the main options are the “unit cell”, longitudinal gravel trenches in plane strain conditions, cylindrical rings of gravel in axial symmetry conditions, equivalent homogeneous soil with improved properties and three-dimensional models, either a full three-dimensional model or just a three-dimensional row or slice of columns. Some guidelines for obtaining these simplified geometrical models are provided and the particular case of groups of columns under footings is also analyzed. For the latter case, there is a column critical length that is around twice the footing width for non-encased columns in a homogeneous soft soil. In the literature, the column critical length is sometimes given as a function of the column length, which leads to some disparities in its value. Here it is shown that the column critical length mainly depends on the footing dimensions. Some other features related with column modeling are also briefly presented, such as the influence of column installation. Finally, some guidance and recommendations are provided on parameter selection for the study of stone columns. PMID:28773146

Simulation of interaction between ground water in an alluvial aquifer and surface water in a large braided river

USGS Publications Warehouse

Leake, S.A.; Lilly, M.R.

1995-01-01

The Fairbanks, Alaska, area has many contaminated sites in a shallow alluvial aquifer. A ground-water flow model is being developed using the MODFLOW finite-difference ground-water flow model program with the River Package. The modeled area is discretized in the horizontal dimensions into 118 rows and 158 columns of approximately 150-meter square cells. The fine grid spacing has the advantage of providing needed detail at the contaminated sites and surface-water features that bound the aquifer. However, the fine spacing of cells adds difficulty to simulating interaction between the aquifer and the large, braided Tanana River. In particular, the assignment of a river head is difficult if cells are much smaller than the river width. This was solved by developing a procedure for interpolating and extrapolating river head using a river distance function. Another problem is that future transient simulations would require excessive numbers of input records using the current version of the River Package. The proposed solution to this problem is to modify the River Package to linearly interpolate river head for time steps within each stress period, thereby reducing the number of stress periods required.

Micro- and Nano-scale Diffusion Domains Acting as Kinetic Controls for U(VI) Release to the Hanford 300-Area Aquifer

NASA Astrophysics Data System (ADS)

Stoliker, D. L.; Hay, M. B.; Davis, J. A.; Zachara, J. M.

2008-12-01

The 300-Area of the Hanford reservation, a cold-war era nuclear processing facility, is plagued by long-term elevated concentrations of U(VI) in the underlying aquifer. While the sediment U(VI) concentration is relatively low, it continues to act as a source and sink for the contaminant, allowing for persistent groundwater concentrations well above the maximum contamination limit (MCL). Simple Kd modeling of the attenuation of U(VI) in the aquifer predicted that groundwater U(VI) concentrations would decrease to below the drinking water standard by the year 2002. However, grain-scale morphology of the aquifer material suggests that intra-grain flow paths and mineral coatings, in which sorption complexes and precipitates formed over years of waste disposal, provide a significant kinetic constraint that slows groundwater flushing of the sediments. In order to quantify the impact of diffusion kinetics on the release of U(VI), high-resolution, non-reactive tracer studies were conducted on vadose zone sediments in both column and batch reactors. Systems were equilibrated for long time scales with tritated artificial groundwater and then flushed with flow and stop-flow events included for columns. Previously collected U(VI) release data from batch dissolution/desorption studies is compared with tritium tracer diffusion kinetics as well as porosimetry and detailed microscopy characterization. The micro-scale and nano-scale diffusion regimes, including intra-granular regions as well as mineral coatings, represent a significant potential long-term source of contaminant U(VI). Understanding the physical kinetic limitations coupled with the complex chemistry of U(VI) sorption processes within natural systems is an important step forward in providing information to strengthen field-scale reactive transport simulations.

In situ and laboratory investigations into contaminant migration

NASA Astrophysics Data System (ADS)

Williams, G. M.; Higgo, J. J. W.

1994-07-01

Predicting the spread of groundwater pollution demands a detailed understanding of the physical, chemical and microbial processes that control contaminant mobility in aquifers. Many field studies have been carried out around pollutant sources in an attempt to understand these processes, but quantitative results are often difficult to obtain because of the number of assumptions that have to be made about the flow regime or the source term which has given rise to the pollution. Models can be constructed with emphases on different processes to describe the known distribution of contaminants at any one time. However, if these models are to be used for predictive purposes, or to help remediation, it is important to identify and quantify individual processes precisely by independent or direct methods and not to rely on inference alone. Laboratory tests suffer from the fact that aquifer material has to be sampled and transferred to the laboratory. In the process, the sample may be disturbed physically thus altering its porosity, permeability and dispersive properties. It may be oxidised, thereby altering its chemistry, and the numbers, activity and character of any microbial population may change. In situ tracer experiments attempt to overcome the limitations of the laboratory by maintaining natural conditions, but at the same time allowing the injection of solute to be accurately defined and the hydraulic regime to be well controlled and monitored. Examples are given showing how integrated laboratory and field approaches have been used to study: (1) organic degradation in a pollution plume resulting from the disposal of industrial wastes and (2) the role of colloids in transporting radionuclides in an intergranular aquifer.

Ammonia-oxidizing archaea versus bacteria in two soil aquifer treatment systems.

PubMed

Ding, Kun; Wen, Xianghua; Li, Yuyang; Shen, Bo; Zhang, Bing

2015-02-01

So far, the contribution of ammonia-oxidizing archaea (AOA) to ammonia oxidation in wastewater treatment processes has not been well understood. In this study, two soil aquifer treatment (SATs) systems were built up to treat synthetic domestic wastewater (column 1) and secondary effluent (column 4), accomplishing an average of 95% ammonia removal during over 550 days of operation. Except at day 322, archaeal amoA genes always outnumbered bacterial amoA genes in both SATs as determined by using quantitative polymerase chain reaction (q-PCR). The ratios of archaeal amoA to 16S rRNA gene averaged at 0.70 ± 0.56 and 0.82 ± 0.62 in column 1 and column 4, respectively, indicating that all the archaea could be AOA carrying amoA gene in the SATs. The results of MiSeq-pyrosequencing targeting on archaeal and bacterial 16S rRNA genes with the primer pair of modified 515R/806R indicated that Nitrososphaera cluster affiliated with thaumarchaeal group I.1b was the dominant AOA species, while Nitrosospira cluster was the dominant ammonia-oxidizing bacteria (AOB). The statistical analysis showed significant relationship between AOA abundance (compared to AOB abundance) and inorganic and total nitrogen concentrations. Based on the mathematical model calculation for microbial growth, AOA had much greater capacity of ammonia oxidation as compared to the specific influent ammonia loading for AOA in the SATs, implying that a small fraction of the total AOA would actively work to oxidize ammonia chemoautotrophically whereas most of AOA would exhibit some level of functional redundancy. These results all pointed that AOA involved in microbial ammonia oxidation in the SATs.

Data for ground-water test hole near Butte City, Central Valley aquifer project, California

USGS Publications Warehouse

French, James J.; Page, R.W.; Bertoldi, G.L.

1983-01-01

This report provides preliminary data for the third of seven test holes drilled as part of the Central Valley Aquifer Project which is part of the National Regional Aquifer Systems Analysis Program. The test hole was drilled in the SW 1/4 NE 1/4 sec. 32, T. 19 N., R. 1 W., Glenn County, California, about one-half mile south of the town of Butte City. Drilled to a depth of 1,432 feet below land surface, the hole is cased to a depth of 82 feet and equipped with three piezometer tubes to depths of 592 feet, 968 feet, and 1,330 feet. A 5-foot well screen is at the bottom of each piezometer. Each screened interval has a cement plug above and below it to isolate it from other parts of the aquifer , and the well bore is filled between the plugs with sediment. Nine cores and 49 sidewall cores were recovered. Laboratory tests were made for mineralogy, hydraulic conductivity, porosity , consolidation, grain-size distribution, Atterberg limits, X-ray diffraction, and chemical quality of water. Geophysical and thermal gradient logs were made. The hole is sampled periodically for chemical analysis and measured for water level in the three tapped zones. This report presents methods used to obtain field samples, laboratory procedures, and the data obtained. (USGS)

Uncertainty Quantification and Risk Mitigation of CO2 Leakage in Groundwater Aquifers

NASA Astrophysics Data System (ADS)

Sun, Y.; Tong, C.; Mansoor, K.; Carroll, S.

2013-12-01

The risk of CO2 leakage into shallow aquifers through various pathways such as faults and abandoned wells is a concern of CO2 geological sequestration. If a leak is detected in an aquifer system, a contingency plan is required to manage the CO2 storage and to protect the groundwater source. Among many remediation and mitigation strategies, the simplest is to stop CO2 leakage at a wellbore. Therefore, it is necessary to address whether and when the CO2 leaks should be sealed, and how much risk can be mitigated. In the presence of various uncertainties, including geological-structure uncertainty and parametric uncertainty, the risk of CO2 leakage into an aquifer needs to be assessed with probabilistic distributions of uncertain parameters. In this study, we developed an integrated model to simulate multiphase flow of CO2 and brine in a deep storage reservoir, through a leaky well at an uncertain location, and subsequently multicomponent reactive transport in a shallow aquifer. Each sub-model covers its domain-specific physics. Uncertainties of geological structure and parameters are considered together with decision variables (CO2 injection rate and mitigation time) for risk assessment of leakage-impacted aquifer volume. High-resolution and less-expensive reduced-order models (ROMs) of risk profiles are approximated as polynomial functions of decision variables and all uncertain parameters. These reduced-order models are then used in the place of computationally-expensive numerical models for future decision-making on if and when the leaky well is sealed. The tradeoff between CO2 storage capacity in the reservoir and the leakage-induced risk in the aquifer is evaluated. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

Mobility and dissipation of chlorpyriphos and quinalphos in sandy clay loam in an agroecosystem-a laboratory-based soil column study.

PubMed

G P, Bindumol; C C, Harilal

2017-09-15

Leaching potential of pesticides, apart from climatological factors, depends on soil physical properties, soil-pesticide interaction and chemical nature of the molecule. Recent investigations have revealed the presence of various organophosphate pesticides in various agroecosystems. The present study investigated the soil transport mechanism of commonly used organophosphate pesticides in acidic sandy clay loam soils of Kerala State, India. Packed soil column experiment was undertaken under laboratory condition for 30 days. Unsaturated flow was carried out using distilled water/0.01 M CaCl 2 solution after applying chlorpyriphos and quinalphos at the rate of 0.04% a.i.ha -1 and 0.025% a.i.ha -1 , respectively. The study revealed the retention of residues of chlorpyriphos and quinalphos in the top 5-cm layer. Irrespective of the applied concentration of chlorpyriphos and quinalphos, the relative concentration of the pesticides in soil was similar. About 56% of the applied chemicals were dissipated in 30 days of unsaturated flow. A new dissipation compound iron, tricarbonyl [N-(phenyl-2-pyridinylmethyene) benzenamine-N, N'], was detected in GCMS analysis of soil extract from distilled water percolated soil. The dissipation of chlorpyriphos and quinalphos was faster in 0.01 M CaCl 2 -treated soil column. Among the pesticides analysed, the residue of quinalphos was detected in leachate.

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

USGS Publications Warehouse

Reese, Ronald S.

2006-01-01

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

Flow dynamics and salt transport in a coastal aquifer driven by a stratified saltwater body: Lab experiment and numerical modeling

NASA Astrophysics Data System (ADS)

Oz, Imri; Shalev, Eyal; Yechieli, Yoseph; Gavrieli, Ittai; Gvirtzman, Haim

2014-04-01

This paper examines the transient development and the steady-state configuration of groundwater within a coastal aquifer adjacent to a stratified saltwater body. Such systems consist of three different water types: the regional fresh groundwater, and low and high salinity brines forming the upper and lower water layers of the stratified water body, respectively. The dynamics, location and the geometry of the interfaces and the density-driven circulation flows that develop in the aquifer are examined using laboratory experiments and numerical modeling at the same scale. The results show that the transient intrusion of the different water bodies into the aquifer takes place at different rates, and that the locations of the interfaces between them change with time, before reaching steady-state. Under steady-state conditions both the model and the experiments show the existence of three interfaces between the three water types. The numerical model, which is calibrated against the salinity distribution and groundwater discharge rate in the laboratory experiments, allows the quantification of the flow rates and flow patterns within the aquifer. These flow patterns, which cannot be derived from laboratory experiments, show the transient development of three circulation cells which are confined between the three interfaces. These results confirm the hypothesis that has been previously suggested based solely on a steady-state numerical modeling defined by a conceptual understanding. Parametric analysis shows that the creation of three circulation cells and three interfaces is limited to certain conditions and defines the ranges for the creation of this unique system.

Aquifer characteristics, water availability, and water quality of the Quaternary aquifer, Osage County, northeastern Oklahoma, 2001-2002

USGS Publications Warehouse

Mashburn, Shana L.; Cope, Caleb C.; Abbott, Marvin M.

2003-01-01

of 5,100 feet squared per day. Water in storage in the alluvium was estimated to be approximately 200,000 acre-feet. The amount of water annually recharging the aquifer was estimated to be approximately 4,800 acre-feet. Specific conductance for all water samples ranged from 161 to 6,650 microsiemens per centimeter. Median specific conductance for the alluvium was 683 microsiemens per centimeter and for the terrace deposits was 263 microsiemens per centimeter. Dissolved-solids concentrations, estimated from specific conductance, for water samples from the aquifer ranged from 88 to 3,658 milligrams per liter. Estimated median dissolved- solids concentration for the alluvium was 376 milligrams per liter and for the terrace deposits was 145 milligrams per liter. More than half of the samples from the Quaternary aquifer were estimated to contain less than 500 milligrams per liter dissolved solids. Field-screened nitrate concentrations for the sampling in December 2001-August 2002 ranged from 0 to 15 milligrams per liter. The field-screened nitrate concentrations for the second sampling in September 2002 were less than corresponding laboratory reported values.

Sole Source Aquifers for NY and NJ

EPA Pesticide Factsheets

This layer is the designated sole source aquifers of New York and New Jersey. A Sole Source Aquifer, is an aquifer that supplies 50% or more of the drinking water for a given area where there are no reasonably available alternative sources should the aquifer become contaminated.

Aquifer Tests and Characterization of Transmissivity, Ada-Vamoosa Aquifer on the Osage Reservation, Osage County, Oklahoma, 2006

USGS Publications Warehouse

Abbott, Marvin M.; DeHay, Kelli

2008-01-01

The Ada-Vamoosa aquifer of northeastern Oklahoma is a sedimentary bedrock aquifer of Pennsylvanian age that crops out over 800 square miles of the Osage Reservation. The Osage Nation needed additional information regarding the production potential of the aquifer to aid them in future development planning. To address this need, the U.S. Geological Survey, in cooperation with the Osage Nation, conducted a study of aquifer properties in the Ada-Vamoosa aquifer. This report presents the results of the aquifer tests from 20 wells in the Ada-Vamoosa aquifer and one well in a minor aquifer east of the Ada-Vamoosa outcrop on the Osage Reservation. Well information for 17 of the 21 wells in this report was obtained from the Indian Health Service. Data collected by the U.S. Geological Survey during this investigation are pumping well data from four domestic wells collected during the summer of 2006. Transmissivity values were calculated from well pumping data or were estimated from specific capacity values depending on the reliability of the data. The estimated transmissivity values are 1.1 to 4.3 times greater than the calculated transmissivity values. The calculated and estimated transmissivity values range from 5 to 1,000 feet squared per day.

Hydrology of the shallow aquifer and uppermost semiconfined aquifer near El Paso, Texas

USGS Publications Warehouse

White, D.E.; Baker, E.T.; Sperka, Roger

1997-01-01

The reversal from upward to downward in vertical hydraulic gradient between the Rio Grande alluvium and the underlying Hueco bolson aquifer has induced shallow water in the alluvium to move downward into the deeper aquifer. The introduction of water from the alluvium probably has led to a gradual water-quality deterioration of ground water in the Hueco bolson aquifer. The extent of any deterioration is a major concern because the dissolved solids concentration in water from some wells is approaching 1,000 milligrams per liter and already has exceeded this limit in other wells.

Geospatial compilation of historical water-level changes in the Chicot and Evangeline aquifers 1977-2013 and Jasper aquifer 2000-13, Gulf Coast aquifer system, Houston-Galveston region, Texas

USGS Publications Warehouse

Johnson, Michaela R.; Linard, Joshua I.

2014-01-01

The U.S. Geological Survey (USGS) in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District has produced an annual series of reports that depict water-level changes in the Chicot, Evangeline, and Jasper aquifers of the Gulf Coast aquifer system in the Houston-Galveston region, Texas, from 1977 to 2013. Changes are determined from water-level measurements between December and March of each year from groundwater wells screened in one of the three aquifers. Existing published maps and unpublished geographic information system (GIS) datasets were compiled into a comprehensive geodatabase of all water-level-change maps produced as part of this multiagency effort. Annual water-level-change maps were georeferenced and digitized where existing GIS data were unavailable (1979–99). Existing GIS data available for 2000–13 were included in the geodatabase. The compilation contains 121 datasets showing water-level changes for each primary aquifer of the Gulf Coast aquifer system: 56 for the Chicot aquifer (1977; 1979–2013 and 1990; 1993–2013), 56 for the Evangeline aquifer (1977; 1979–2013 and 1990; 1993–2013), and 9 for the Jasper aquifer (2000; 2005–13).

High-density PhyloChip profiling of stimulated aquifer microbial communities reveals a complex response to acetate amendment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Handley, Kim M.; Wrighton, Kelly E.; Piceno, Y. M.

2012-06-13

There is increasing interest in harnessing the functional diversity of indigenous microbial communities to transform and remediate a wide range of environmental contaminants. Understanding the response of communities to stimulation, including flanking taxa, presents important opportunities for optimizing remediation approaches. We used high-density PhyloChip microarray analysis to comprehensively determine community membership and abundance patterns amongst a suite of samples from U(VI) bioremediation experiments. Samples were unstimulated or collected during Fe(III) and sulfate reduction from an acetate-augmented aquifer in Rifle, Colorado, and from laboratory experiments using field-collected materials. Results showed the greatest diversity in abundant SRB lineages was present in naturally-reducedmore » sediment. Desulfuromonadales and Desulfobacterales were consistently identified as the dominant Fe(III)- and sulfate-reducing bacteria (IRB and SRB) throughout acetate amendment experiments. Stimulated communities also exhibited a high degree of functional redundancy amongst enriched flanking members. Not surprisingly, competition for both sulfate and iron was evident amongst abundant taxa, but the distribution and abundance of these ancillary SRB (Peptococcaceae, Desulfovibrionales and Syntrophobacterales), and lineages containing IRB (excluding Desulfobacteraceae) was heterogeneous amongst sample types. Interesting, amongst the most abundant taxa, particularly during sulfate reduction, were Epsilonproteobacteria that perform microaerobic or nitrate-dependant sulfur oxidation, and a number of bacteria other than Geobacteraceae that may enzymatically reduce U(VI). Finally, in depth community probing with PhyloChip determined the efficacy of experimental approaches, notably revealing striking similarity amongst stimulated sediment (from drill cores and in-situ columns) and groundwater communities, and demonstrating that sediment-packed in-situ (down-well) columns

Miniaturized protein separation using a liquid chromatography column on a flexible substrate

NASA Astrophysics Data System (ADS)

Yang, Yongmo; Chae, Junseok

2008-12-01

We report a prototype protein separator that successfully miniaturizes existing technology for potential use in biocompatible health monitoring implants. The prototype is a liquid chromatography (LC) column (LC mini-column) fabricated on an inexpensive, flexible, biocompatible polydimethylsiloxane (PDMS) enclosure. The LC mini-column separates a mixture of proteins using size exclusion chromatography (SEC) with polydivinylbenzene beads (5-20 µm in diameter with 10 nm pore size). The LC mini-column is smaller than any commercially available LC column by a factor of ~11 000 and successfully separates denatured and native protein mixtures at ~71 psi of the applied fluidic pressure. Separated proteins are analyzed using NuPAGE-gel electrophoresis, high-performance liquid chromatography (HPLC) and an automated electrophoresis system. Quantitative HPLC results demonstrate successful separation based on intensity change: within 12 min, the intensity between large and small protein peaks changed by a factor of ~20. In further evaluation using the automated electrophoresis system, the plate height of the LC mini-column is between 36 µm and 100 µm. The prototype LC mini-column shows the potential for real-time health monitoring in applications that require inexpensive, flexible implant technology that can function effectively under non-laboratory conditions.

Hydrogeology and water-quality characteristics of the Lower Floridan aquifer in east-central Florida

USGS Publications Warehouse

O'Reilly, Andrew M.; Spechler, Rick M.; McGurk, Brian E.

2002-01-01

surface of the Lower Floridan aquifer ranged from about 16 to 113 feet above sea level, and altitudes in May 1999 were about 2 to 7 feet lower than those measured in September 1998. The potentiometric surface of the Floridan aquifer system is constantly fluctuating, mainly in response to seasonal variations in rainfall and ground-water withdrawals. Seasonal fluctuations in the Lower Floridan aquifer typically range from about 2 to 10 feet. Water samples from 50 Lower Floridan aquifer wells were collected during this study. Most samples were analyzed in the field for temperature, pH, and specific conductance, and in the laboratory for major cations and anions. Specific conductance ranged from 147 to 6,710 microsiemens per centimeter. Chloride concentrations ranged from 3.0 to 2,188 milligrams per liter; sulfate concentrations ranged from 0.2 to 750 milli-grams per liter; and hardness ranged from 69 to 940 milligrams per liter. Water was least mineralized in the recharge areas of the Lower Floridan aquifer in the western part of the study area. The most mineralized water in the Lower Floridan aquifer occurred along parts of the Wekiva and St. Johns Rivers and in much of the eastern and southern parts of the study area. The altitude of the base of freshwater in the Floridan aquifer system (where chloride concentrations are equal to 250 milligrams per liter) is variable throughout the study area. The estimated position of the 250 milligram per liter isochlor surface is less than 200 feet below sea level in much of the eastern part of the study area, including the areas along the St. Johns River in Lake, Seminole, and Volusia Counties and near the Wekiva River in western Seminole County. The altitude of the 250 milligram per liter isochlor exceeds 3,000 feet below sea level in the extreme southwestern part of the study area.

Uranium Sequestration During Biostimulated Reduction and In Response to the Return of Oxic Conditions In Shallow Aquifers

USGS Publications Warehouse

Fuller, Christopher C.; Johnson, Kelly J.; Akstin, Katherine; Singer, David M.; Yabusaki, Steven B.; Fang, Yilin; Fuhrmann, M.

2015-01-01

A proposed approach for groundwater remediation of uranium contamination is to generate reducing conditions by stimulating the growth of microbial populations through injection of electron donor compounds into the subsurface. Sufficiently reducing conditions will result in reduction of soluble hexavalent uranium, U(VI), and precipitation of the less soluble +4 oxidation state uranium, U(IV). This process is termed biostimulated reduction. A key issue in the remediation of uranium (U) contamination in aquifers by biostimulated reduction is the long term stability of the sequestered uranium. Three flow-through column experiments using aquifer sediment were used to evaluate the remobilization of bioreduced U sequestered under conditions in which biostimulation extended well into sulfate reduction to enhance precipitation of reduced sulfur phases such as iron sulfides. One column received added ferrous iron, Fe(II), increasing production of iron sulfides, to test their effect on remobilization of the sequestered uranium, either by serving as a redox buffer by competing for dissolved oxygen, or by armoring the reduced uranium. During biostimulation of the ambient microbial population with acetate, dissolved uranium was lowered by a factor of 2.5 or more with continued removal for over 110 days of biostimulation, well after the onset of sulfate reduction at ~30 days. Sequestered uranium was essentially all U(IV) resulting from the formation of nano-particulate uraninite that coated sediment grains to a thickness of a few 10’s of microns, sometimes in association with S and Fe. A multicomponent biogeochemical reactive transport model simulation of column effluents during biostimulation was generally able to describe the acetate oxidation, iron, sulfate, and uranium reduction for all three columns using parameters derived from simulations of field scale biostimulation experiments. Columns were eluted with artificial groundwater at equilibrium with atmospheric oxygen to

Influence of the heterogeneity on the hydraulic conductivity of a real aquifer

NASA Astrophysics Data System (ADS)

Carmine, Fallico; Aldo Pedro, Ferrante; Chiara, Vita Maria; Bartolo Samuele, De

2010-05-01

Many factors influence the flux in the porous media therefore the values of the representative parameters of the aquifer such as the hydraulic conductivity (k). A lot of studies have shown that this parameter increases with the portion of the aquifer tested. The main cause of this behaviour is the heterogeneity in the aquifer (Sànchez-Vila et al., 1996). It was also verified that the scale dependence of hydraulic conductivity does not depend on the specific method of measurement (Schulze-Makuch and Cherkauer, 1998). An experimental approach to study this phenomenon is based on sets of measurements carried out at different scales. However, one should consider that for the lower scale values k can be determined by direct measurements, performed in the laboratory using samples of different dimensions; whyle, for the large scales the measurement of the hydraulic conductivity requires indirect methods (Johnson and Sen, 1988; Katz and Thompson, 1986; Bernabé and Revil, 1995). In this study the confined aquifer of Montalto Uffugo test field was examined. This aquifer has the geological characteristics of a recently formed valley, with conglomeratic and sandy alluvial deposits; specifically the layer of sands and conglomerates, with a significant percentage of silt at various levels, lies about 55-60 m below the ground surface, where there is a heavy clay formation. Moreover in the test field, for the considered confined aquifer, there are one completely penetrating well, five partially penetrating wells and two completely penetrating piezometers. Along two vertical lines a series of cylindrical samples (6.4 cm of diameter and 15 cm of head) were extracted and for each one of them the k value was measured in laboratory by direct methods, based on the use of flux cells. Also indirect methods were used; in fact, a series of slug tests was carried out, determining the corresponding k values and the radius of influence (R). Moreover another series of pumping tests was

Use of column experiments to investigate the fate of organic micropollutants - a review

NASA Astrophysics Data System (ADS)

Banzhaf, Stefan; Hebig, Klaus H.

2016-09-01

Although column experiments are frequently used to investigate the transport of organic micropollutants, little guidance is available on what they can be used for, how they should be set up, and how the experiments should be carried out. This review covers the use of column experiments to investigate the fate of organic micropollutants. Alternative setups are discussed together with their respective advantages and limitations. An overview is presented of published column experiments investigating the transport of organic micropollutants, and suggestions are offered on how to improve the comparability of future results from different experiments. The main purpose of column experiments is to investigate the transport and attenuation of a specific compound within a specific sediment or substrate. The transport of (organic) solutes in groundwater is influenced by the chemical and physical properties of the compounds, the solvent (i.e., the groundwater, including all solutes), and the substrate (the aquifer material). By adjusting these boundary conditions a multitude of different processes and related research questions can be investigated using a variety of experimental setups. Apart from the ability to effectively control the individual boundary conditions, the main advantage of column experiments compared to other experimental setups (such as those used in field experiments, or in batch microcosm experiments) is that conservative and reactive solute breakthrough curves can be derived, which represent the sum of the transport processes. There are well-established methods for analyzing these curves. The effects observed in column studies are often a result of dynamic, non-equilibrium processes. Time (or flow velocity) is an important factor, in contrast to batch experiments where all processes are observed until equilibrium is reached in the substrate-solution system. Slight variations in the boundary conditions of different experiments can have a marked influence on

ADAPTATION OF AQUIFER MICROBIAL COMMUNITIES TO THE BIODEGRADATION OF XENOBIOTIC COMPOUNDS: INFLUENCE OF SUBSTRATE CONCENTRATION AND PREEXPOSURE

EPA Science Inventory

Studies were conducted to examine the adaptation response of aquifer microbial communities to xenobiotic compounds and the influence of chemical preexposure in the laboratory and in situ on adaptation. Adaptation and biodegradation were assessed as mineralization and cellular inc...

FIELD AND LABORATORY EVIDENCE FOR INTRINSIC BIODEGRADATION OF VINYL CHLORIDE CONTAMINATION IN A FE(III)-REDUCING AQUIFER

EPA Science Inventory

Intrinsic bioremediation of chlorinated ethenes in anaerobic aquifers previously has not been considered feasible, due, in large part, to 1) the production of vinyl chloride during microbial reductive dechlorination of higher chlorinated contaminants and 2) the apparent poor biod...

Estimated withdrawals from principal aquifers in the United States, 2000

USGS Publications Warehouse

Maupin, Molly A.; Barber, Nancy L.

2005-01-01

Fresh ground-water withdrawals from 66 principal aquifers in the United States were estimated for irrigation, public-supply, and self-supplied industrial water uses for the year 2000. Total ground-water withdrawals were 76,500 million gallons per day, or 85,800 thousand acre-feet per year for these three uses. Irrigation used the largest amount of ground water, 56,900 million gallons per day, followed by public supply with 16,000 million gallons per day, and self-supplied industrial with 3,570 million gallons per day. These three water uses represented 92 percent of the fresh groundwater withdrawals for all uses in the United States, the remaining 8 percent included self-supplied domestic, aquaculture, livestock, mining, and thermoelectric power uses. Aquifer withdrawals were categorized by five lithologic groups: unconsolidated and semiconsolidated sand and gravel aquifers, carbonate-rock aquifers, igneous and metamorphic-rock aquifers, sandstone aquifers, and sandstone and carbonate-rock aquifers. Withdrawals from aquifers that were not included in one of the 66 principal aquifers were reported in an “Other” aquifers group. The largest withdrawals in the United States were from unconsolidated and semiconsolidated sand and gravel aquifers, which accounted for 80 percent of total withdrawals from all aquifers. Carbonate-rock aquifers provided 8 percent of the withdrawals, and igneous and metamorphic-rock aquifers, 6 percent. Withdrawals from sandstone aquifers, from sandstone and carbonate-rock aquifers, and from the “Other” aquifers category each constituted about 2 percent of the total withdrawals reported.Fifty-five percent of the total withdrawals for irrigation, public-supply, and self-supplied industrial water uses were provided by the High Plains aquifer, California Central Valley aquifer system, the Mississippi River Valley alluvial aquifer, and the Basin and Range basin-fill aquifers. These aquifers provided most of the withdrawals for irrigation

Insights into arsenic retention dynamics of Pleistocene aquifer sediments by in situ sorption experiments.

PubMed

Neidhardt, Harald; Winkel, Lenny H E; Kaegi, Ralf; Stengel, Caroline; Trang, Pham T K; Lan, Vi M; Viet, Pham H; Berg, Michael

2018-02-01

The migration of arsenic (As) enriched groundwater into Pleistocene aquifers as a consequence of extensive groundwater abstraction represents an increasing threat to the precious water resources in Asian delta regions. Pleistocene aquifer sediments are typically rich in FeIII-(hydr)oxides and are capable to adsorb high amounts of As. This results in a pronounced accumulation of As in Pleistocene aquifers, where high As groundwater infiltrates from adjacent Holocene aquifers. However, As retention by Pleistocene aquifers over long-term time scales remains largely unknown. We studied As sorption in situ by placing natural Pleistocene sediments and pure mineral phases directly inside groundwater monitoring wells at a study site near Hanoi (Vietnam). This in situ exposure allows for constant flushing of the samples with unaltered groundwater and the establishment of undisturbed sorption equilibria similar to those in local aquifer sediments, which is not readily attainable in traditional laboratory sorption experiments. The groundwaters in our experimental wells were characterized by different As concentrations (0.01-6.63 μmol/L) and redox states, reaching from suboxic to anoxic conditions (E h of +159 to -4 mV). Results show that adsorption is the dominant As retention mechanism, independent from the respective groundwater chemistry (i.e. concentrations of dissolved P, HCO 3 - and Si). Whilst most of the As sorbed within the first week, sorption further increased slowly but consistently by 6-189%, respectively, within six months. Hence, the As sorption behavior of Pleistocene aquifer sediments should be determined over longer periods to avoid an underestimation of the As sorption capacity. Accompanying desorption experiments revealed that about 51% of the sorbed As was remobilized within six months when exposed to low As groundwater. We therefore conclude that a considerable proportion of the As accumulated in the aquifer sediments is prone to remobilization once

Geohydrology of the Vamoosa-Ada aquifer east-central Oklahoma with a section on chemical quality of water

USGS Publications Warehouse

D'Lugosz, Joseph J.; McClaflin, Roger G.; Marcher, Melvin V.

1986-01-01

water in the Vamoosa-Ada aquifer generally is suitable for municipal, domestic, and stock use. Of 55 water samples analyzed in the laboratory, about 75 percent were of the sodium bicarbonate or sodium calcium bicarbonate type; the remainder were of the sodium sulfate, calcium sulfate, sodium chloride, or indeterminate types. Laboratory and on-site chemical-quality data indicate that mineralization of both ground and surface waters is greater than normal in some areas. Water samples from 7 wells and 12 stream sites had concentrations of bromide exceeding 1 milligram per liter; the only known source of bromide in the area is brine associated with petroleum production.

In situ treatment of arsenic contaminated groundwater by aquifer iron coating: Experimental Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Xianjun; Wang, Yanxin; Pi, Kunfu

In situ arsenic removal from groundwater by an iron coating method has great potential to be a cost effective and simple groundwater remediation technique, especially in rural and remote areas where groundwater is used as the main source of drinking water. The in situ arsenic removal technique was first optimized by simulating arsenic removal in various quartz sand columns under anoxic conditions., Its effectiveness was then evaluated in an actual high-arsenic groundwater environment. The mechanism of arsenic removal by the iron coating was investigated under different conditions using scanning electron microscopy (SEM)/X-ray absorption spectroscopy, an electron microprobe, and Fourier transformationmore » infrared spectroscopy. A 4-step alternative cycle aquifer iron coating method was developed. A continuous injection of 5 mmol/L FeSO4 and 2.5 mmol/L NaClO for 96 hours can create a uniform coating of crystalline goethite on the surface of quartz sand in the columns without causing clogging. At a flow rate of 0.45 cm/min of the injection reagents (vi), the time for arsenic (as Na2HAsO4) to pass through the iron-coated quartz sand column was approximately 35 hours, which was much longer than that for tracer fluorescein sodium (approximately 2 hours). The retardation factor of arsenic was 23, and its adsorption capacity was 0.11 mol As per mol Fe, leading to an excellent arsenic removal. In situ arsenic removal from groundwater in an aquifer was achieved by simultaneous injections of As (V) and Fe (II) reagents. When the arsenic content in the groundwater was 233 μg/L, the aqueous phase arsenic was completely removed with an arsenic adsorption of 0.05 mol As per mol Fe. Arsenic fixation resulted from a process of adsorption/co-precipitation, in which arsenic and iron likely formed the arsenic-bearing iron mineral phases with poor crystallinity by way of bidentate binuclear complexes. Thus, the high arsenic removal efficiency of the technique likely resulted from

Surfactant-enhanced remediation of a trichloroethene-contaminated aquifer. 2. Transport of TCE

USGS Publications Warehouse

Sahoo, D.; Smith, J.A.; Imbrigiotta, T.E.; Mclellan, H.M.

1998-01-01

Field studies were conducted under an induced gradient in a trichloroethene (TCE)-contaminated aquifer at Picatinny Arsenal, NJ, to study (a) the rate-limited desorption of TCE from aquifer sediments to water and (b) the effect of a surfactant (Triton X-100) on the desorption and transport of TCE. Clean water was injected into the contaminated aquifer for 206 day. Triton X-100 was added for a 36-day period (days 36-71 from the start of clean water injection). The effect of Triton X-100 on the desorption and transport of TCE in the field was examined by observing the concentrations of these two solutes in four monitoring wells 3-9 m from the injection wells. These data show a small but discernible increase in the TCE concentration in two of the wells corresponding approximately to the time when surfactant reaches the wells; in the other two monitoring wells, the increase in TCE concentration is negligible. A solute transport model that assumes local sorption equilibrium and used a laboratory-derived distribution coefficient could not adequately describe TCE desorption and transport observed in the aquifer. Two model formulations that accounted for rate-limited sorption - two-site and multisite models - fit the data well. TCE concentrations after surfactant injection were underpredicted by the models unless mass transfer rate was increased to account for the effect of surfactant on the rate of TCE desorption. The concentration data from the two wells and the model analysis suggest that the rate of TCE desorption is increased (by approximately 30%) as a result of Triton X-100 injection.Field studies were conducted under an induced gradient in a trichloroethene (TCE)-contaminated aquifer at Picatinny Arsenal, NJ, to study (a) the rate-limited desorption of TCE from aquifer sediments to water and (b) the effect of a surfactant (Triton X-100) on the desorption and transport of TCE. Clean water was injected into the contaminated aquifer for 206 day. Triton X-100 was added

Hydrogeologic framework of the North Carolina Coastal Plain aquifer system

USGS Publications Warehouse

Winner, M.D.; Coble, R.W.

1989-01-01

The hydrogeologic framework of the North Carolina Coastal Plain aquifer system consists of ten aquifers separated by nine confining units. From top to bottom the aquifers are: the surficial aquifer, Yorktown aquifer, Pungo River aquifer, Castle Hayne aquifer, Beaufort aquifer, Peedee aquifer, Black Creek aquifer, upper Cape Fear aquifer, lower Cape Fear aquifer, and the Lower Cretaceous aquifer. The uppermost aquifer (the surficial aquifer in most places) is a water-table aquifer and the bottom of the system is underlain by crystalline bedrock. The sedimentary deposits forming the aquifers are of Holocene to Cretaceous age and are composed mostly of sand with lesser amounts of gravel and limestone. Confining units between aquifers are composed primarily of clay and silt. The thickness of the aquifers ranges from zero along the Fall Line to more than 10,000 feet at Cape Hatteras. Prominent structural features are the increasing easterly homoclinal dip of the sediments and the Cape Fear arch, the axis of which trends in a southeast direction. The stratigraphic continuity is determined from correlations of 161 geophysical logs along with data from drillers' and geologists' logs. Aquifers were defined by means of these logs plus water-level and water-quality data and evidence of the continuity of pumping effects. Eighteen hydrogeologic sections depict the correlation of these aquifers throughout the Coastal Plain.

Hydraulic characterization of aquifers by thermal response testing

NASA Astrophysics Data System (ADS)

Wagner, Valentin; Blum, Philipp; Bayer, Peter

2014-05-01

Temperature as a major physical quantity of the subsurface, and naturally occurring thermal anomalies are recognized as promising passive tracers to characterize the subsurface. Accelerated by the increasing popularity of geothermal energy, also active thermal field experiments have gained interest in hydrogeology. Such experiments involve artificial local ground heating or cooling. Among these, the thermal response test (TRT) is one of the most established field investigation techniques in shallow geothermal applications. It is a common method to investigate important subsurface heat transport parameters to design sustainable ground-source heat pump (GSHP) systems. During the test, the borehole heat exchanger (BHE) is heated up with a defined amount of energy by circulating a heat carrier fluid. By comparing temperature change between BHE inlet and outlet, the ability of the BHE to transfer heat or cold to the ambient ground is assessed. However, standard interpretation does not provide any insight into the governing processes of in-situ heat transfer. We utilize a groundwater advection sensitive TRT evaluation approach based on the analytical moving line source equation. It is shown that the TRT as a classical geothermal field test can also be used as a hydrogeological field test. Our approach benefits from the fact that thermal properties, such as thermal conductivity, of natural aquifers typically are much less variable than hydraulic properties, such as hydraulic conductivity. It is possible to determine a relatively small hydraulic conductivity range with our TRT evaluation approach, given realistic ranges for thermal conductivity, volumetric heat capacity, thermal dispersivity and thermal borehole resistance. The method is successfully tested on a large-scale geothermal laboratory experiment (9 m × 6 m × 4.5 m) and with a commercially performed TRT in the field scale. The laboratory experiment consists of a layered artificial aquifer, which is penetrated

NORTH BASEMENT WALL. IBEAM COLUMNS HAVE BEEN ENCASED IN CONCRETE. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

NORTH BASEMENT WALL. I-BEAM COLUMNS HAVE BEEN ENCASED IN CONCRETE. STEEL BEAMS LAY ACROSS FIRST FLOOR AWAITING CONCRETE POUR. CAMERA LOOKS SOUTHWEST. INL NEGATIVE NO. 735. Unknown Photographer, 10/6/1950 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

Empirical analysis of the stress-strain relationship between hydraulic head and subsidence in the San Joaquin Valley Aquifer

NASA Astrophysics Data System (ADS)

Neff, K. L.; Farr, T.

2016-12-01

Aquifer subsidence due to groundwater abstraction poses a significant threat to aquifer sustainability and infrastructure. The need to prevent permanent compaction to preserve aquifer storage capacity and protect infrastructure begs a better understanding of how compaction is related to groundwater abstraction and aquifer hydrogeology. The stress-strain relationship between hydraulic head changes and aquifer compaction has previously been observed to be hysteretic in both empirical and modeling studies. Here, subsidence data for central California's San Joaquin Valley derived from interferometric synthetic aperture radar (InSAR) for the period 2007-2016 is examined relative to hydraulic head levels in monitoring and production wells collected by the California Department of Water Resources. Such a large and long-term data set is available for empirical analysis for the first time thanks to advances in InSAR data collection and geospatial data management. The California Department of Water Resources (DWR) funded this work to provide the background and an update on subsidence in the Central Valley to support future policy. Part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA.

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

PubMed

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

2015-03-01

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

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

USGS Publications Warehouse

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

2012-01-01

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

Protistan communities in aquifers: A review

USGS Publications Warehouse

Novarino, G.; Warren, A.; Butler, H.; Lambourne, G.; Boxshall, A.; Bateman, J.; Kinner, N.E.; Harvey, R.W.; Mosse, R.A.; Teltsch, B.

1997-01-01

Eukaryotic microorganisms (protists) are a very important component of microbial communities inhabiting groundwater aquifers This is not unexpected when one considers that many protists feed heterotrophically, by means of either phagotrophy (bacterivory) or osmotrophy. Protistan numbers are usually low (<102 per g dw of aquifer material) in pristine, uncontaminated aquifers but may increase by several orders of magnitude in aquifers subject to organic pout on Stoa flagellates (typically 2-3(5) ??m in size in situ) are by far the dominant protists in aquifers although amoebae and occasionally ciliates may also be present much lower numbers. A though a wealth of new taxonomic information is waiting to be brought to light, interest in the identity of aquifer protists is not exclusively academic If verified, the following hypotheses may prove to be important towards our understanding of the functioning of microbial communities in aquifers: (1) Differences in swimming behavior between species of flagellates lead to feeding heterogeneity and niche differentiation, implying that bacterivorous flagellates graze on different subsets of the bacterial community, and therefore play different roles in controlling bacterial densities. (2) Bacterivorous flagellates grazing on bacteria capable of degrading Organic compounds have an indirect effect on the overall rates of biodegradation.

Treatment of Copper Contaminated Municipal Wastewater by Using UASB Reactor and Sand-Chemically Carbonized Rubber Wood Sawdust Column

PubMed Central

Biswas, Swarup; Mishra, Umesh

2016-01-01

The performance of a laboratory scale upflow anaerobic sludge blanket (UASB) reactor and its posttreatment unit of sand-chemically carbonized rubber wood sawdust (CCRWSD) column system for the treatment of a metal contaminated municipal wastewater was investigated. Copper ion contaminated municipal wastewater was introduced to a laboratory scale UASB reactor and the effluent from UASB reactor was then followed by treatment with sand-CCRWSD column system. The laboratory scale UASB reactor and column system were observed for a period of 121 days. After the posttreatment column the average removal of monitoring parameters such as copper ion concentration (91.37%), biochemical oxygen demand (BODT) (93.98%), chemical oxygen demand (COD) (95.59%), total suspended solid (TSS) (95.98%), ammonia (80.68%), nitrite (79.71%), nitrate (71.16%), phosphorous (44.77%), total coliform (TC) (99.9%), and fecal coliform (FC) (99.9%) was measured. The characterization of the chemically carbonized rubber wood sawdust was done by scanning electron microscope (SEM), X-ray fluorescence spectrum (XRF), and Fourier transforms infrared spectroscopy (FTIR). Overall the system was found to be an efficient and economical process for the treatment of copper contaminated municipal wastewater. PMID:26904681

Treatment of Copper Contaminated Municipal Wastewater by Using UASB Reactor and Sand-Chemically Carbonized Rubber Wood Sawdust Column.

PubMed

Biswas, Swarup; Mishra, Umesh

2016-01-01

The performance of a laboratory scale upflow anaerobic sludge blanket (UASB) reactor and its posttreatment unit of sand-chemically carbonized rubber wood sawdust (CCRWSD) column system for the treatment of a metal contaminated municipal wastewater was investigated. Copper ion contaminated municipal wastewater was introduced to a laboratory scale UASB reactor and the effluent from UASB reactor was then followed by treatment with sand-CCRWSD column system. The laboratory scale UASB reactor and column system were observed for a period of 121 days. After the posttreatment column the average removal of monitoring parameters such as copper ion concentration (91.37%), biochemical oxygen demand (BODT) (93.98%), chemical oxygen demand (COD) (95.59%), total suspended solid (TSS) (95.98%), ammonia (80.68%), nitrite (79.71%), nitrate (71.16%), phosphorous (44.77%), total coliform (TC) (99.9%), and fecal coliform (FC) (99.9%) was measured. The characterization of the chemically carbonized rubber wood sawdust was done by scanning electron microscope (SEM), X-ray fluorescence spectrum (XRF), and Fourier transforms infrared spectroscopy (FTIR). Overall the system was found to be an efficient and economical process for the treatment of copper contaminated municipal wastewater.

Microbially mediated clinoptilolite regeneration in a multifunctional permeable reactive barrier used to remove ammonium from landfill leachate contamination: laboratory column evaluation.

PubMed

Nooten, Thomas Van; Diels, Ludo; Bastiaens, Leen

2010-05-01

This study focuses on multifunctional permeable reactive barrier (multibarrier) technology, combining microbial degradation and abiotic ion exchange processes for removal of ammonium from landfill leachate contamination. The sequential multibarrier concept relies on the use of a clinoptilolite-filled buffer compartment to ensure a robust ammonium removal in case of temporary insufficient microbial activities. An innovative strategy was developed to allow in situ clinoptilolite regeneration. Laboratory-scale clinoptilolite-filled columns were first saturated with ammonium, using real landfill leachate as well as synthetic leachates as feed media. Other inorganic metal cations, typically present in landfill leachate, had a detrimental influence on the ammonium removal capacity by competing for clinoptilolite exchange sites. On the other hand, the metals had a highly favorable impact on regeneration of the saturated material. Feeding the columns with leachate deprived from ammonium (e.g., by microbial nitrification in an upgradient compartment), resulted in a complete release of the previously sorbed ammonium from the clinoptilolite, due to exchange with metal cations present in the leachate. The released ammonium is then available for microbial consumption in a downgradient compartment. The regeneration process resulted in a slightly increased ammonium exchange capacity afterward. The described strategy throws a new light on sustainable use of sorption materials for in situ groundwater remediation, by avoiding the need for material replacement and the use of external chemical regenerants.

Influence of Aquifer Thermal Energy Storage (ATES) on groundwater chemistry: an overview of several cases in Belgium

NASA Astrophysics Data System (ADS)

Possemiers, Mathias; Huysmans, Marijke; Batelaan, Okke

2013-04-01

Environmental concerns and an increasing pressure on fossil fuels cause a rapidly growing interest in renewable energy. An interesting provider of such renewable energy is Aquifer Thermal Energy Storage (ATES), where groundwater in the aquifer is used as storage medium for summer heat and winter cold. The number of ATES systems has been continually increasing over the last years and will continue to increase in the future. Because ATES is often applied in aquifers also used for the production of drinking water, drinking water companies and environmental agencies are concerned about the impact of all these ATES systems on the groundwater quality in the long term. Because most ATES systems operate at relatively small temperature differences, ranging to several °C above and below the natural groundwater temperature, several studies show that the temperature influence on the groundwater quality is negligible. Mixing of the water column, on the other hand, possibly affects groundwater quality. The water is often extracted over a large portion of the aquifer in order to come to the desired flow rates. The composition of the groundwater on this interval may, however, differ from the top to the bottom by interaction with the surrounding aquifer material. The aim of this study is to evaluate the influence that Aquifer Thermal Energy Storage may have on the groundwater quality. Therefore the groundwater chemistry around seven ATES installations in the north of Belgium (Flanders) is evaluated. The selected ATES systems are located in several aquifers, which have major groundwater resources. The warm and cold wells of the different ATES installations were sampled and analyzed for the main chemical constituents during 4 to 7 years. The time series of the different chemical compounds are investigated per ATES well and compared with time series of several monitoring wells in the exploited aquifer. Results confirm that the temperatures occurring in the ATES systems do not affect

Integrated monitoring technologies for the management of a Soil-Aquifer-Treatment (SAT) system.

NASA Astrophysics Data System (ADS)

Papadopoulos, Alexandros; Kallioras, Andreas; Kofakis, Petros; Bumberger, Jan; Schmidt, Felix; Athanasiou, Georgios; Uzunoglou, Nikolaos; Amditis, Angelos; Dietrich, Peter

2016-04-01

Artificial recharge of groundwater has an important role to play in water reuse as treated wastewater effluent can be infiltrated into the ground for aquifer recharge. As the effluent moves through the soil and the aquifer, it undergoes significant quality improvements through physical, chemical, and biological processes in the underground environment. Collectively, these processes and the water quality improvement obtained are called soil-aquifer-treatment (SAT) or geopurification. The pilot site of Lavrion Technological & Cultural Park (LTCP) of the National Technical University of Athens (NTUA), involves the employment of plot infiltration basins at experimental scale, which will be using waters of impaired quality as a recharge source, and hence acting as a Soil-Aquifer-Treatment, SAT, system. Τhe LTCP site will be employed as a pilot SAT system complemented by new technological developments, which will be providing continuous monitoring of the quantitative and qualitative characteristics of infiltrating groundwater through all hydrologic zones (i.e. surface, unsaturated and saturated zone). This will be achieved by the development and installation of an integrated system of prototype sensing technologies, installed on-site, and offering a continuous evaluation of the performance of the SAT system. An integrated approach of the performance evaluation of any operating SAT system should aim at parallel monitoring of all hydrologic zones, proving the sustainability of all involved water quality treatment processes within unsaturated and saturated zone. Hence a prototype system of Time and Frequency Domain Reflectometry (TDR & FDR) sensors is developed and will be installed, in order to achieve continuous quantitative monitoring of the unsaturated zone through the entire soil column down to significant depths below the SAT basin. Additionally, the system contains two different radar-based sensing systems that will be offering (i) identification of preferential

Sea water in coastal aquifers

USGS Publications Warehouse

Cooper, Hilton Hammond

1964-01-01

Investigations in the coastal part of the Biscayne aquifer, a highly productive aquifer of limestone and sand in the Miami area, Florida, show that the salt-water front is dynamically stable as much as 8 miles seaward of the position computed according to the Ghyben-Herzberg principle. This discrepancy results, at least in part, from the fact that the salt water in the Biscayne aquifer is not static, as explanations of the dynamic balance commonly assume. Cross sections showing lines of equal fresh-water potential indicate that during periods of heavy recharge, the fresh-water head is high enough to cause the fresh water, the salt water, and the zone of diffusion between them to move seaward. When the fresh-water head is low, salt water in the lower part of the aquifer intrudes inland, but some of the diluted sea water in the zone of diffusion continues to flow seaward. Thus, salt water circulates inland from the floor of the sea through the lower part of the aquifer becoming progressively diluted with fresh water to a line along which there is no horizontal component of flow, after which it moves upward and returns to the sea. This cyclic flow is demonstrated by a flow net which is constructed by the use of horizontal gradients determined from the low-head equipotential diagram. The flow net shows that about seven-eights of the total discharge at the shoreline originates as fresh water in inland parts of the aquifer. The remaining one-eighth represents a return of sea water entering the aquifer through the floor of the sea.

Kinetic and microbial community analysis of methyl ethyl ketone biodegradation in aquifer sediments.

PubMed

Fahrenfeld, N; Pruden, A; Widdowson, M

2017-02-01

Methyl ethyl ketone (MEK) is a common groundwater contaminant often present with more toxic compounds of primary interest. Because of this, few studies have been performed to determine the effect of microbial community structure on MEK biodegradation rates in aquifer sediments. Here, microcosms were prepared with aquifer sediments containing MEK following a massive spill event and compared to laboratory-spiked sediments, with MEK biodegradation rates quantified under mixed aerobic/anaerobic conditions. Biodegradation was achieved in MEK-contaminated site sediment microcosms at about half of the solubility (356 mg/L) with largely Firmicutes population under iron-reducing conditions. MEK was biodegraded at a higher rate [4.0 ± 0.74 mg/(L days)] in previously exposed site samples compared to previously uncontaminated sediments [0.51 ± 0.14 mg/(L days)]. Amplicon sequencing and denaturing gradient gel electrophoresis of 16S rRNA genes were combined to understand the relationship between contamination levels, biodegradation, and community structure across the plume. More heavily contaminated sediments collected from an MEK-contaminated field site had the most similar communities than less contaminated sediments from the same site despite differences in sediment texture. The more diverse microbial community observed in the laboratory-spiked sediments reduced MEK concentration 47 % over 92 days. Results of this study suggest lower rates of MEK biodegradation in iron-reducing aquifer sediments than previously reported for methanogenic conditions and biodegradation rates comparable to previously reported nitrate- and sulfate-reducing conditions.

Microbial succession and stimulation following a test well injection simulating CO2 leakage into shallow Newark Basin aquifers

NASA Astrophysics Data System (ADS)

Dueker, M.; Clauson, K.; Yang, Q.; Umemoto, K.; Seltzer, A. M.; Zakharova, N. V.; Matter, J. M.; Stute, M.; Takahashi, T.; Goldberg, D.; O'Mullan, G. D.

2012-12-01

Despite growing appreciation for the importance of microbes in altering geochemical reactions in the subsurface, the microbial response to geological carbon sequestration injections and the role of microbes in altering metal mobilization following leakage scenarios in shallow aquifers remain poorly constrained. A Newark Basin test well was utilized in field experiments to investigate patterns of microbial succession following injection of CO2 saturated water into isolated aquifer intervals. Additionally, laboratory mesocosm experiments, including microbially-active and inactive (autoclave sterilized) treatments, were used to constrain the microbial role in mineral dissolution, trace metal release, and gas production (e.g. hydrogen and methane). Hydrogen production was detected in both sterilized and unsterilized laboratory mesocosm treatments, indicating abiotic hydrogen production may occur following CO2 leakage, and methane production was detected in unsterilized, microbially active mesocosms. In field experiments, a decrease in pH following injection of CO2 saturated aquifer water was accompanied by mobilization of trace elements (e.g. Fe and Mn), the production of hydrogen gas, and increased bacterial cell concentrations. 16S ribosomal RNA clone libraries, from samples collected before and after the test well injection, were compared in an attempt to link variability in geochemistry to changes in aquifer microbiology. Significant changes in microbial composition, compared to background conditions, were found following the test well injection, including a decrease in Proteobacteria, and an increased presence of Firmicutes, Verrucomicrobia, Acidobacteria and other microbes associated with iron reducing and syntrophic metabolism. The concurrence of increased microbial cell concentration, and rapid microbial community succession, with increased concentrations of hydrogen gas suggests that abiotically produced hydrogen may serve as an ecologically-relevant energy

[Laboratory evaluation of remediation of nitrobenzene contaminated aquifer by using groundwater circulation well].

PubMed

Bai, Jing; Zhao, Yong-Sheng; Sun, Chao; Qin, Chuan-Yu; Yu, Ling

2014-10-01

A two-dimension simulated sand box was set up to investigate the influencing factors, such as the initial groundwater level, aeration rate and the initial groundwater rate, that affect groundwater circulation well (GCW) by determining the intensity of groundwater circulation which was characterized by the variation of groundwater level before and after aeration. The optimal operating parameters were used to remediate nitrobenzene contaminated aquifer. The results demonstrated that: GCW could be well operated under the conditions of 45 cm groundwater level, 0.7 m3 · h(-1) aeration rate. The effects of groundwater velocity less than 1.0 m · d(-1) could be ignored. The lateral mobility rate of nitrobenzene was faster than that of longitudinal. The average concentration of nitrobenzene was 246.97 mg · L(-1) on day 50 of leakage. During the remediation of circulation well, an efficient organics remediation region was gradually formed around the circulation well. The organics in this region was removed preferentially, and the concentration decreased continuously. Besides the efficient remediation region, there was a transient region, where the concentration of organics was influenced by the combined effects of adsorption/desorption and migration potential of organics. During the whole remediation process, the concentration of nitrobenzene went through three stages described as rapid removal, slow removal. After 14h aeration, the nitrobenzene average concentration was reduced to 71.19 mg L(-1). The residual nitrobenzene was distributed in regions far away from GCW. Therefore, nitrobenzene contaminated aquifer could be well remediated by GCW, and there were optimal operation conditions and appropriate remediation time which guaranteed the best remediation effect.

Contaminant sequestration in karstic aquifers: Experiments and quantification

NASA Astrophysics Data System (ADS)

Li, Guangquan; Loper, David E.; Kung, Robin

2008-02-01

A karstic aquifer typically has significant secondary porosity consisting of an interconnected system of caves or conduits. Conduit-borne contaminants can enter the contiguous limestone matrix, remain inside for a longer time than in the conduit, and subsequently be flushed out. This retention or sequestration can significantly influence the fate of contaminants within the aquifer and alter the shape of the breakthrough curve. The mechanisms involved in sequestration have been identified and quantified by analysis of the breakthrough curves generated by a set of laboratory experiments in which a conduit, porous limestone matrix, and conservative contaminant were simulated by a porous-walled pipe, chamber of closely packed glass beads, and salt, respectively. Experiments were conducted with both active and passive transfer of water between conduit and matrix, simulating differing hydrogeologic regimes. In active transfer the primary control parameter is the volume of water transferred; sequestration is primarily due to advection with the effects of diffusion and dispersion being minimal. In passive transfer the control parameters are the conduit Reynolds number and the duration that contaminant resides in the conduit; sequestration is caused by the combined effects of the conduit pressure drop, pressure variation due to bedform, and diffusion. Active and passive transfer can be unified by analyzing the ratio of the scale of pressure variation to the conduit length. In accordance with the resolved mechanisms a variety of models have been constructed to recover solute distributions in the matrix and to regenerate breakthrough curves. These analyses and models provide a potential approach to investigate contaminant migration in karstic aquifers.

Mitigation of Oil in Water Column: Concept Development

DTIC Science & Technology

2016-06-01

Argonne National Laboratory (ANL) proposes to use polyurethane foam , a commonly used material for many general purposes, as the material of choice to...adsorb submerged oil. Prior to use, the foam undergoes a series of chemical processes in order to render it oleophilic and thus more susceptible to...17. Key Words Adsorbent Foam , Adhesion, Microbubble, Sinking Oil, Submerged Oil, Oil Mitigation, Sorbent, Water Column 18. Distribution Statement

Transport of viruses through saturated and unsaturated columns packed with sand

USGS Publications Warehouse

Anders, R.; Chrysikopoulos, C.V.

2009-01-01

Laboratory-scale virus transport experiments were conducted in columns packed with sand under saturated and unsaturated conditions. The viruses employed were the male-specific RNA coliphage, MS2, and the Salmonella typhimurium phage, PRD1. The mathematical model developed by Sim and Chrysikopoulos (Water Resour Res 36:173-179, 2000) that accounts for processes responsible for removal of viruses during vertical transport in one-dimensional, unsaturated porous media was used to fit the data collected from the laboratory experiments. The liquid to liquid-solid and liquid to air-liquid interface mass transfer rate coefficients were shown to increase for both bacteriophage as saturation levels were reduced. The experimental results indicate that even for unfavorable attachment conditions within a sand column (e.g., phosphate-buffered saline solution; pH = 7.5; ionic strength = 2 mM), saturation levels can affect virus transport through porous media. ?? Springer Science+Business Media B.V. 2008.

The Sparta aquifer in Arkansas' critical ground-water areas: Response of the aquifer to supplying future water needs

USGS Publications Warehouse

Hays, Phillip D.; Fugitt, D. Todd

1999-01-01

The Sparta aquifer is a confined aquifer of great regional importance that comprises a sequence of unconsolidated sand, silt, and clay units extending across much of eastern and southeastern Arkansas and into adjoining States. Water use from the aquifer has doubled since 1975 and continues to increase, and large water-level declines are occurring in many areas of the aquifer. To focus State attention and resources on the growing problem and to provide a mechanism for locally based education and management, the Arkansas Soil and Water Conservation Commission has designated Critical Ground-Water Areas in some counties (see page 6, ?What is a Critical Ground-Water Area??). Ground-water modeling study results show that the aquifer cannot continue to meet growing water-use demands. Dewatering of the primary producing sands is predicted to occur within 10 years in some areas if current trends continue. The predicted dewatering will cause reduced yields and damage the aquifer. Modeling also shows that a concerted ground-water conservation management plan could enable sustainable use of the aquifer. Water-conservation measures and use of alternative sources that water managers in Union County (an area of high demand and growth in Arkansas' initial five-county Critical Ground-Water Area) think to be realistic options result in considerable recovery in water levels in the aquifer during a 30-year model simulation.

An update of hydrologic conditions and distribution of selected constituents in water, Snake River Plain aquifer, Idaho National Laboratory, Idaho, Emphasis 1999-2001

USGS Publications Warehouse

Davis, Linda C.

2006-01-01

Radiochemical and chemical wastewater discharged since 1952 to infiltration ponds, evaporation ponds, and disposal wells at the Idaho National Laboratory (INL) has affected water quality in the Snake River Plain aquifer underlying the INL. The U.S. Geological Survey (USGS), in cooperation with the U.S. Department of Energy, maintains ground-water monitoring networks at the INL to determine hydrologic trends, and to delineate the movement of radiochemical and chemical wastes in the aquifer. This report presents an analysis of water-level and water-quality data collected from wells in the USGS ground-water monitoring networks during 1999-2001. Water in the Snake River Plain aquifer moves principally through fractures and interflow zones in basalt, generally flows southwestward, and eventually discharges at springs along the Snake River. The aquifer is recharged principally from infiltration of irrigation water, infiltration of streamflow, ground-water inflow from adjoining mountain drainage basins, and infiltration of precipitation. Water levels in wells rose in the northern and west-central parts of the INL by 1 to 3 feet, and declined in the southwestern parts of the INL by up to 4 feet during 1999-2001. Detectable concentrations of radiochemical constituents in water samples from wells in the Snake River Plain aquifer at the INL generally decreased or remained constant during 1999-2001. Decreases in concentrations were attributed to decreased rates of radioactive-waste disposal, radioactive decay, changes in waste-disposal methods, and dilution from recharge. Tritium concentrations in water samples decreased as much as 8.3 picocuries per milliliter (pCi/mL) during 1999-2001, ranging from 0.43?0.14 to 13.6?0.6 pCi/mL in October 2001. Tritium concentrations in five wells near the Idaho Nuclear Technology and Engineering Center (INTEC) increased a few picocuries per milliliter from October 2000 to October 2001. Strontium-90 concentrations decreased or remained

Virus and bacteria transport in a sandy aquifer, Cape Cod, MA

USGS Publications Warehouse

Bales, Roger C.; Li, Shimin; Maguire, Kimberly M.; Yahya, Moyasar T.; Gerba, Charles P.; Harvey, Ronald W.

1995-01-01

Transport of the bacteriophage PRD-1, bacteria, and latex microspheres was studied in a sandy aquifer under natural-gradient conditions. The field injection was carried out at the U.S. Geological Survey's Toxic Substances Hydrology research site on Cape Cod. The three colloids and a salt tracer (Br−) moved along the same path. There was significant attenuation of the phage, with PRD-1 peak concentrations less than 0.001 percent of Br− peaks 6 m from the source; but the low detection limit (one per ml) enabled tracking movement of the PRD-1 plume for 12 m downgradient over the 25-day experiment. Attenuation of phage was apparently due to retention on soil particles (adsorption). Attenuation of bacteria and microspheres was less, with peak concentrations 6 m from the source on the order of 10 and 0.4 percent of Br−, respectively. Injection of a high-pH pulse of water 20 days into the experiment resulted in significant remobilization of retained phage, demonstrating that attached phage remained viable, and that PRD-1 attachment to and detachment from the sandy soil particles was highly pH dependent. Phage behavior in this experiment, i.e. attenuation at pH 5.7 and rapid resuspension at pH 6–8, was consistent with that observed previously in laboratory column studies. Results illustrate that biocolloids travel in a fairly narrow plume in sandy (relatively homogeneous) media, with virus concentrations dropping below detection limit several meters away from the source; bacteria concentrations above detection limits can persist over longer distances.

Estimation of septic tank setback distances based on transport of E. coli and F-RNA phages.

PubMed

Pang, Liping; Close, Murray; Goltz, Mark; Sinton, Lester; Davies, Helen; Hall, Carollyn; Stanton, Greg

2004-01-01

Setback distances between septic tank systems and the shorelines of Lake Okareka, New Zealand were determined from model simulations for a worst-case scenario, using the highest hydraulic conductivity and gradient measured in the field, removal rates of the microbial indicators (Escherichia coli and F-RNA phages) determined from a column experiment, and maximum values of the design criteria for the disposal system, and assuming an absence of an unsaturated zone, a continuous discharge of the raw effluent from a failed or non-complying treatment system (both indicators at concentrations of 1x10(7) counts/100 ml) into the groundwater and no sorption of pathogens in the aquifer. Modelling results suggest that the minimal setback distances were 16 m to satisfy the New Zealand Recreational Water Quality Guidelines for E. coli <126 per 100 ml (Ministry for the Environment, 1999) and 48 m to meet the Drinking-Water Standards for New Zealand 2000 for enteric virus <1 per 100 l (Ministry of Health, 2000). These distances may be applicable for other lakeshores in pumice sand aquifers with groundwater velocities <7 m/day. Findings of laboratory column and batch experiments provided an insight into the microbial attenuation and transport processes in pumice sand aquifers. Bacterial removal was predominately through filtration (87-88%) and partially by die-off (12-13%), while viral removal was by both die-off (45%) and filtration (55%). In addition, microbial die-off in groundwater without aquifer material (i.e., free microbes) was much lower than die-off in groundwater with aquifer material (i.e., sorbed microbes) and contributed only 2-6% to the total removal. This implies that the setback distances estimated from die-off rates for the free microbes, determined in the laboratory without considering aquifer media and other removal processes, which are often reported in the literature, could be larger than necessary.

Dynamics of an experimental unconfined aquifer

NASA Astrophysics Data System (ADS)

Lajeunesse, E.; Guérin, A.; Devauchelle, O.

2015-12-01

During a rain event, water infiltrates into the ground where it flows slowly towards rivers. We use a tank filled with glass beads to simulate this process in a simplified laboratory experiment. A sprinkler pipe generates rain, which infiltrates into the porous material. Groundwater exits this laboratory aquifer through one side of the tank. The resulting water discharge increases rapidly during rainfall, and decays slowly after the rain has stopped.A theoretical analysis based on Darcy's law and the shallow-water approximation reveals two asymptotic regimes. At the beginning of a rain event, the water discharge increases linearly with time, with a slope proportional to the rainfall rate at the power of 3/2. Long after the rain has stopped, it decreases as the inverse time squared, as predicted by Polubarinova-Kochina (1962). These predictions compare well against our experimental data.Field measurements from two distinct catchments exhibit the same asymptotic behaviours as our experiment. This observation suggests that, despite the simplicity of the setup, our experimental results could be extended to natural groundwater flows.

An update of hydrologic conditions and distribution of selected constituents in water, Snake River Plain aquifer and perched groundwater zones, Idaho National Laboratory, Idaho, emphasis 2006-08

USGS Publications Warehouse

Davis, Linda C.

2010-01-01

Since 1952, radiochemical and chemical wastewater discharged to infiltration ponds (also called percolation ponds), evaporation ponds, and disposal wells at the Idaho National Laboratory (INL) has affected water quality in the eastern Snake River Plain aquifer and perched groundwater zones underlying the INL. The U.S. Geological Survey, in cooperation with the U.S. Department of Energy, maintains groundwater monitoring networks at the INL to determine hydrologic trends, and to delineate the movement of radiochemical and chemical wastes in the aquifer and in perched groundwater zones. This report presents an analysis of water-level and water-quality data collected from aquifer and perched groundwater wells in the USGS groundwater monitoring networks during 2006-08. Water in the Snake River Plain aquifer primarily moves through fractures and interflow zones in basalt, generally flows southwestward, and eventually discharges at springs along the Snake River. The aquifer primarily is recharged from infiltration of irrigation water, infiltration of streamflow, groundwater inflow from adjoining mountain drainage basins, and infiltration of precipitation. From March-May 2005 to March-May 2008, water levels in wells generally remained constant or rose slightly in the southwestern corner of the INL. Water levels declined in the central and northern parts of the INL. The declines ranged from about 1 to 3 feet in the central part of the INL, to as much as 9 feet in the northern part of the INL. Water levels in perched groundwater wells around the Advanced Test Reactor Complex (ATRC) also declined. Detectable concentrations of radiochemical constituents in water samples from wells in the Snake River Plain aquifer at the INL generally decreased or remained constant during 2006-08. Decreases in concentrations were attributed to decreased rates of radioactive-waste disposal, radioactive decay, changes in waste-disposal methods, and dilution from recharge and underflow. In April

Estimating Aquifer Properties Using Sinusoidal Pumping Tests

NASA Astrophysics Data System (ADS)

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.

Sorption and transport of acetaminophen, 17alpha-ethynyl estradiol, nalidixic acid with low organic content aquifer sand.

PubMed

Lorphensri, Oranuj; Sabatini, David A; Kibbey, Tohren C G; Osathaphan, Khemarath; Saiwan, Chintana

2007-05-01

The sorption and transport of three pharmaceutical compounds (acetaminophen, an analgesic; nalidixic acid, an antibiotic; and 17alpha-ethynyl estradiol, a synthetic hormone) were examined by batch sorption experiments and solute displacement in columns of silica, alumina, and low organic carbon aquifer sand at neutral pH. Silica and alumina were used to represent negatively-charged and positively-charged fractions of subsurface media. Column transport experiments were also conducted at pH values of 4.3, 6.2, and 8.2 for the ionizable nalidixic acid. The computer program UFBTC was used to fit the breakthrough data under equilibrium and nonequilibrium conditions with linear/nonlinear sorption. Good agreement was observed between the retardation factors derived from column model studies and estimated from equilibrium batch sorption studies. The sorption and transport of nalidixic acid was observed to be highly pH dependent, especially when the pH was near the pK(a) of nalidixic acid (5.95). Thus, near a compound's pK(a) it is especially important that the batch studies be performed at the same pH as the column experiment. While for ionic pharmaceuticals, ion exchange to oppositely-charged surfaces, appears to be the dominant adsorption mechanism, for neutral pharmaceuticals (i.e., acetaminophen, 17alpha-ethynyl estradiol) the sorption correlated well with the K(ow) of the pharmaceuticals, suggesting hydrophobically motivated sorption as the dominant mechanism.

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

USGS Publications Warehouse

Runkle, D.L.; Becker, M.F.; Rea, Alan

1997-01-01

This diskette contains digitized aquifer boundaries and maps of hydraulic conductivity, recharge, and ground-water level elevation contours for the Rush Spring aquifer in western Oklahoma. This area encompasses all or part of Blaine, Caddo, Canadian, Comanche, Custer, Dewey, Grady, Stephens, and Washita Counties. These digital data sets were developed by Mark F. Becker to use as input into a computer model that simulated ground-water flow in the Rush Springs aquifer (Mark F. Becker, U.S. Geological Survey, written commun., 1997). For the purposes of modeling the ground-water flow in the Rush Springs aquifer, Mark F. Becker (written commun., 1997) defined the Rush Springs aquifer to include the Rush Springs Formation, alluvial and terrace deposits along major streams, and parts of the Marlow Formations, particularly in the eastern part of the aquifer boundary area. The Permian-age Rush Springs Formation consists of highly cross-bedded sandstone with some interbedded dolomite and gypsum. The Rush Springs Formation is overlain by Quaternary-age alluvial and terrace deposits that consist of unconsolidated clay, silt, sand, and gravel. The Rush Springs Formation is underlain by the Permian-age Marlow Formation that consists of interbedded sandstones, siltstones, mudstones, gypsum-anhydrite, and dolomite beds (Mark F. Becker, written commun., 1997). The parts of the Marlow Formation that have high permeability and porosity are where the Marlow Formation is included as part of the Rush Springs aquifer. The Rush Springs aquifer underlies about 2,400 square miles of western Oklahoma and is an important source of water for irrigation, livestock, industrial, municipal, and domestic use. Irrigation wells are reported to have well yields greater than 1,000 gallons per minute (Mark F. Becker, written commun., 1997). Mark F. Becker created some of the aquifer boundaries, hydraulic conductivity, and recharge data sets by digitizing parts of previously published surficial geology

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

USGS Publications Warehouse

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

2004-01-01

As part of the Yellowstone River Basin National Water Quality Assessment study, ground-water samples were collected from Quaternary unconsolidated-deposit and lower Tertiary aquifers in the Bighorn Basin of Wyoming and Montana from 1999 to 2001. Samples from 54 wells were analyzed for physical characteristics, major ions, trace elements, nutrients, dissolved organic carbon, radionuclides, pesticide compounds, and volatile organic compounds (VOCs) to evaluate current water-quality conditions in both aquifers. Water-quality samples indicated that waters generally were suitable for most uses, and that natural conditions, rather than the effects of human activities, were more likely to limit uses of the waters. Waters in both types of aquifers generally were highly mineralized, and total dissolved-solids concentrations frequently exceeded the U.S. Environmental Protection Agency (USEPA) Secondary Maximum Contaminant Level (SMCL) of 500 milligrams per liter (mg/L). Because of generally high mineralization, waters from nearly one-half of the samples from Quaternary aquifers and more than one-half of the samples from lower Tertiary aquifers were not classified as fresh (dissolved-solids concentration were not less than 1,000 mg/L). The anions sulfate, fluoride, and chloride were measured in some ground-water samples at concentrations greater than SMCLs. Most waters from the Quaternary aquifers were classified as very hard (hardness greater than 180 mg/L), but hardness varied much more in waters from the lower Tertiary aquifers and ranged from soft (less than 60 mg/L) to very hard (greater than 180 mg/L). Major-ion chemistry varied with dissolved-solids concentrations. In both types of aquifers, the predominant anion changes from bicarbonate to sulfate with increasing dissolved-solids concentrations. Samples from Quaternary aquifers with fresh waters generally were calcium-bicarbonate, calcium-sodium-bicarbonate, and calcium-sodium-sulfate-bicarbonate type waters, whereas

Data for ground-water test hole near Zamora, Central Valley Aquifer Project, California

USGS Publications Warehouse

French, J.J.; Page, R.W.; Bertoldi, G.L.

1982-01-01

Preliminary data are presented for the first of seven test holes drilled as a part of the Central Valley Aquifer Project which is part of the National Regional Aquifer Systems Analysis Program. The test hole was drilled in the SW 1/4 SE 1/4 sec. 34, T. 12 N. , R. 1 E., Yolo County, California, about 3 miles northeast of the town of Zamora. Drilled to a depth of 2,500 feet below land surface, the hole is cased to a depth of 190 feet and equipped with three piezometer tubes to depths of 947, 1,401, and 2,125 feet. A 5-foot well screen is at the bottom of each piezometer. Eighteen cores and 68 sidewall cores were recovered. Laboratory tests were made for mineralogy, hydraulic conductivity, porosity , consolidation, grain-size distribution, Atterberg limits, X-ray diffraction, diatom identification, thermal conductivity, and chemical analysis of water. Geophysical and thermal gradient logs were made. The hole is sampled periodically for chemical analysis and measured for water level in the three tapped zones. This report presents methods used to obtain field samples, laboratory procedures, and the data obtained. (USGS)

Ground-water quality of the surficial aquifer system and the upper Floridan Aquifer, Ocala National Forest and Lake County, Florida, 1990-99

USGS Publications Warehouse

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

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

PubMed

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

2005-06-01

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

WTAQ - A computer program for aquifer-test analysis of confined and unconfined aquifers

USGS Publications Warehouse

Barlow, P.M.; Moench, A.F.

2004-01-01

Computer program WTAQ was developed to implement a Laplace-transform analytical solution for axial-symmetric flow to a partially penetrating, finite-diameter well in a homogeneous and anisotropic unconfined (water-table) aquifer. The solution accounts for wellbore storage and skin effects at the pumped well, delayed response at an observation well, and delayed or instantaneous drainage from the unsaturated zone. For the particular case of zero drainage from the unsaturated zone, the solution simplifies to that of axial-symmetric flow in a confined aquifer. WTAQ calculates theoretical time-drawdown curves for the pumped well and observation wells and piezometers. The theoretical curves are used with measured time-drawdown data to estimate hydraulic parameters of confined or unconfined aquifers by graphical type-curve methods or by automatic parameter-estimation methods. Parameters that can be estimated are horizontal and vertical hydraulic conductivity, specific storage, and specific yield. A sample application illustrates use of WTAQ for estimating hydraulic parameters of a hypothetical, unconfined aquifer by type-curve methods. Copyright ASCE 2004.

Summary and evaluation of hydraulic property data available for the Hanford Site upper basalt confined aquifer system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spane, F.A. Jr.; Vermeul, V.R.

Pacific Northwest Laboratory, as part of the Hanford Site Ground-Water Surveillance Project, examines the potential for offsite migration of contamination within the upper basalt confined aquifer system. For the past 40 years, hydrologic testing of the upper basalt confined aquifer has been conducted by a number of Hanford Site programs. Hydraulic property estimates are important for evaluating aquifer flow characteristics (i.e., ground-water flow patterns, flow velocity, transport travel time). Presented are the first comprehensive Hanford Site-wide summary of hydraulic properties for the upper basalt confined aquifer system (i.e., the upper Saddle Mountains Basalt). Available hydrologic test data were reevaluated usingmore » recently developed diagnostic test analysis methods. A comparison of calculated transmissivity estimates indicates that, for most test results, a general correspondence within a factor of two between reanalysis and previously reported test values was obtained. For a majority of the tests, previously reported values are greater than reanalysis estimates. This overestimation is attributed to a number of factors, including, in many cases, a misapplication of nonleaky confined aquifer analysis methods in previous analysis reports to tests that exhibit leaky confined aquifer response behavior. Results of the test analyses indicate a similar range for transmissivity values for the various hydro-geologic units making up the upper basalt confined aquifer. Approximately 90% of the calculated transmissivity values for upper basalt confined aquifer hydrogeologic units occur within the range of 10{sup 0} to 10{sup 2} m{sup 2}/d, with 65% of the calculated estimate values occurring between 10{sup 1} to 10{sup 2} m{sup 2}d. These summary findings are consistent with the general range of values previously reported for basalt interflow contact zones and sedimentary interbeds within the Saddle Mountains Basalt.« less

Aquifers of the Denver Basin, Colorado

USGS Publications Warehouse

Topper, R.

2004-01-01

Development of the Denver Basin for water supply has been ongoing since the late 1800s. The Denver Basin aquifer system consists of the water-yielding strata of Tertiary and Cretaceous sedimentary rocks within four overlying formations. The four statutory aquifers contained in these formations are named the Dawson, Denver, Arapahoe, and Laramie-Fox Hills. For water rights administrative purposes, the outcrop/subcrop of the Laramie-Fox Hills aquifer defines the margins of the Basin. Initial estimates of the total recoverable groundwater reserves in storage, under this 6700-mi2 area, were 295 million acre-ft. Recent geologic evidence indicates that the aquifers are very heterogeneous and their composition varies significantly with distance from the source area of the sediments. As a result, available recoverable reserves may be one-third less than previously estimated. There is no legal protection for pressure levels in the aquifer, and water managers are becoming increasingly concerned about the rapid water level declines (30 ft/yr). Approximately 33,700 wells of record have been completed in the sedimentary rock aquifers of the Denver Basin for municipal, industrial, agricultural, and domestic uses.

Analytical solution of groundwater flow in a sloping aquifer with stream-aquifer interaction.

NASA Astrophysics Data System (ADS)

Liu, X.; Zhan, H.

2017-12-01

This poster presents a new analytical solution to study water exchange, hydraulic head distribution and water flow in a stream-unconfined aquifer interaction system with a sloping bed and stream of varying heads in presence of two thin vertical sedimentary layers. The formation of a clogging bed of fine-grained sediments allows the interfaces among a sloping aquifer and two rivers as the third kind and Cauchy boundary conditions. The numerical solution of the corresponding nonlinear Boussinesq equation is also developed to compare the performance of the analytical solution. The effects of precipitation recharge, bed slope and stage variation rate of two rivers for water flow in the sloping aquifer are discussed in the results.

Geochemistry of the Arbuckle-Simpson Aquifer

USGS Publications Warehouse

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.

Development of a Control Optimization System for Real Time Monitoring of Managed Aquifer Recharge and Recovery Systems Using Intelligent Sensors

NASA Astrophysics Data System (ADS)

Smits, K. M.; Drumheller, Z. W.; Lee, J. H.; Illangasekare, T. H.; Regnery, J.; Kitanidis, P. K.

2015-12-01

Aquifers around the world show troubling signs of irreversible depletion and seawater intrusion as climate change, population growth, and urbanization lead to reduced natural recharge rates and overuse. Scientists and engineers have begun to revisit the technology of managed aquifer recharge and recovery (MAR) as a means to increase the reliability of the diminishing and increasingly variable groundwater supply. Unfortunately, MAR systems remain wrought with operational challenges related to the quality and quantity of recharged and recovered water stemming from a lack of data-driven, real-time control. This research seeks to develop and validate a general simulation-based control optimization algorithm that relies on real-time data collected though embedded sensors that can be used to ease the operational challenges of MAR facilities. Experiments to validate the control algorithm were conducted at the laboratory scale in a two-dimensional synthetic aquifer under both homogeneous and heterogeneous packing configurations. The synthetic aquifer used well characterized technical sands and the electrical conductivity signal of an inorganic conservative tracer as a surrogate measure for water quality. The synthetic aquifer was outfitted with an array of sensors and an autonomous pumping system. Experimental results verified the feasibility of the approach and suggested that the system can improve the operation of MAR facilities. The dynamic parameter inversion reduced the average error between the simulated and observed pressures between 12.5 and 71.4%. The control optimization algorithm ran smoothly and generated optimal control decisions. Overall, results suggest that with some improvements to the inversion and interpolation algorithms, which can be further advanced through testing with laboratory experiments using sensors, the concept can successfully improve the operation of MAR facilities.

Physical and numerical modeling of seawater intrusion in coastal aquifers

NASA Astrophysics Data System (ADS)

Crestani, Elena; Camporese, Matteo; Salandin, Paolo

2016-04-01

Seawater intrusion in coastal aquifers is a worldwide problem caused, among others factors, by aquifer overexploitation, rising sea levels, and climate changes. To limit the deterioration of both surface water and groundwater quality caused by saline intrusion, in recent years many research studies have been developed to identify possible countermeasures, mainly consisting of underground barriers. In this context, physical models are fundamental to study the saltwater intrusion, since they provide benchmarks for numerical model calibrations and for the evaluation of the effectiveness of general solutions to contain the salt wedge. This work presents a laboratory experiment where seawater intrusion was reproduced in a specifically designed sand-box. The physical model, built at the University of Padova, represents the terminal part of a coastal aquifer and consists of a flume 500 cm long, 30 cm wide and 60 cm high, filled for an height of 49 cm with glass beads characterized by a d50 of 0.6 mm and a uniformity coefficient d60/d10 ≈ 1.5. The resulting porous media is homogeneous, with porosity of about 0.37 and hydraulic conductivity of about 1.3×10-3 m/s. Upstream from the sand-box, a tank filled by freshwater provides the recharge to the aquifer. The downstream tank simulates the sea and red food dye is added to the saltwater to easily visualize the salt wedge. The volume of the downstream tank is about five times the upstream one, and, due to the small filtration discharge, salt concentration variations (i.e., water density variations) due to the incoming freshwater flow are negligible. The hydraulic gradient during the tests is constant, due to the fixed water level in the two tanks. Water levels and discharged flow rate are continuously monitored. The experiment presented here had a duration of 36 h. For the first 24 h, the saltwater wedge was let to evolve until quasi stationary condition was obtained. In the last 12 h, water withdrawal was carried out at a

Geologic Controls of Hydraulic Conductivity in the Snake River Plain Aquifer At and Near the Idaho National Engineering and Environmental Laboratory, Idaho

DOE Office of Scientific and Technical Information (OSTI.GOV)

S. R. Anderson; M. A. Kuntz; L. C. Davis

1999-02-01

The effective hydraulic conductivity of basalt and interbedded sediment that compose the Snake River Plain aquifer at and near the Idaho National Engineering and Environmental Laboratory (INEEL) ranges from about 1.0x10 -2 to 3.2x10 4 feet per day (ft/d). This six-order-of-magnitude range of hydraulic conductivity was estimated from single-well aquifer tests in 114 wells, and is attributed mainly to the physical characteristics and distribution of basalt flows and dikes. Hydraulic conductivity is greatest in thin pahoehoe flows and near-vent volcanic deposits. Hydraulic conductivity is least in flows and deposits cut by dikes. Estimates of hydraulic conductivity at and near themore » INEEL are similar to those measured in similar volcanic settings in Hawaii. The largest variety of rock types and the greatest range of hydraulic conductivity are in volcanic rift zones, which are characterized by numerous aligned volcanic vents and fissures related to underlying dikes. Three broad categories of hydraulic conductivity corresponding to six general types of geologic controls can be inferred from the distribution of wells and vent corridors. Hydraulic conductivity of basalt flows probably is increased by localized fissures and coarse mixtures of interbedded sediment, scoria, and basalt rubble. Hydraulic conductivity of basalt flows is decreased locally by abundant alteration minerals of probable hydrothermal origin. Hydraulic conductivity varies as much as six orders of magnitude in a single vent corridor and varies from three to five orders of magnitude within distances of 500 to 1,000 feet. Abrupt changes in hydraulic conductivity over short distances suggest the presence of preferential pathways and local barriers that may greatly affect the movement of ground water and the dispersion of radioactive and chemical wastes downgradient from points of waste disposal.« less

First Commissioning of a Cryogenic Distillation Column for Low Radioactivity Underground Argon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Back, H. O.; Alexander, T.; Alton, A.

2012-04-01

We report on the performance and commissioning of a cryogenic distillation column for low radioactivity underground argon at Fermi National Accelerator Laboratory. The distillation column is designed to accept a mixture of argon, helium, and nitrogen and return pure argon with a nitrogen contamination less than 10 ppm. In the first commissioning, we were able to run the distillation column in a continuous mode and produce argon that is 99.9% pure. After running in a batch mode, the argon purity was increased to 99.95%, with 500 ppm of nitrogen remaining. The efficiency of collecting the argon from the gas mixturemore » was between 70% and 81%, at an argon production rate of 0.84-0.98 kg/day.« less

Non-linear wave interaction in a magnetoplasma column. I - Theory. II Experiment

NASA Technical Reports Server (NTRS)

Larsen, J.-M.; Crawford, F. W.

1979-01-01

The paper presents an analysis of non-linear three-wave interaction for propagation along a cylindrical plasma column surrounded either by a metallic boundary, or by an infinite dielectric, and immersed in an infinite, static, axial magnetic field. An averaged Lagrangian method is used and the results are specialized to parametric amplification and mode conversion, assuming an undepleted pump wave. Computations are presented for a magneto-plasma column surrounded by free space, indicating that parametric growth rates of the order of a fraction of a decibel per centimeter should be obtainable for plausible laboratory plasma parameters. In addition, experiments on non-linear mode conversion in a cylindrical magnetoplasma column are described. The results are compared with the theoretical predictions and good qualitative agreement is demonstrated.

Virus transport during infiltration of a wetting front into initially unsaturated sand columns.

PubMed

Kenst, Andrew B; Perfect, Edmund; Wilhelm, Steven W; Zhuang, Jie; McCarthy, John F; McKay, Larry D

2008-02-15

We investigated the effect of different flow conditions on the transport of bacteriophage phiX174 in Memphis aquifer sand. Virus transport associated with a wetting front moving into an initially unsaturated horizontal sand column was experimentally compared with that observed under steady-state saturated vertical flow. Results obtained by sectioning the sand columns showthattotal (retained and free) resident virus concentrations decreased approximately exponentially with the travel distance. The rate of decline was similar under both transient unsaturated flow and steady-state saturated flow conditions. Total resident virus concentrations near the inlet were an order of magnitude greater than the virus concentration of the influent solution in both experiments, indicating continuous virus sorption during flow through this zone. Virus retardation was quantified using the ratio of the centroids of the relative saturation and virus concentration versus relative distance functions. The mean retardation factors were 6.43 (coefficient of variation, CV = 14.4%) and 8.22 (CV = 8.22%) for the transient unsaturated and steady-state saturated flow experiments, respectively. Attest indicated no significant difference between these values at P < 0.05. Air-water and air-water-solid interfaces are thought to enhance virus inactivation and sorption to solid particles. The similar retardation factors obtained may be attributable to the reduced presence of these interfaces in the two flow systems investigated as compared to steady-state unsaturated flow experiments in which these interfaces occur throughout the entire column.

Inelastic column behavior

NASA Technical Reports Server (NTRS)

Duberg, John E; Wilder, Thomas W , III

1952-01-01

The significant findings of a theoretical study of column behavior in the plastic stress range are presented. When the behavior of a straight column is regarded as the limiting behavior of an imperfect column as the initial imperfection (lack of straightness) approaches zero, the departure from the straight configuration occurs at the tangent-modulus load. Without such a concept of the behavior of a straight column, one is led to the unrealistic conclusion that lateral deflection of the column can begin at any load between the tangent-modulus value and the Euler load, based on the original elastic modulus. A family of curves showing load against lateral deflection is presented for idealized h-section columns of various lengths and of various materials that have a systematic variation of their stress-strain curves.

Degradation of TCE, Cr(VI), sulfate, and nitrate mixtures by granular iron in flow-through columns under different microbial conditions.

PubMed

Gandhi, Sumeet; Oh, Byung-Taek; Schnoor, Jerald L; Alvarez, Pedro J J

2002-04-01

Flow-through aquifer columns packed with a middle layer of granular iron (Fe0) were used to study the applicability and limitations of bio-enhanced Fe0 barriers for the treatment of contaminant mixtures in groundwater. Concentration profiles along the columns showed extensive degradation of hexavalent chromium Cr(VI), nitrate, sulfate, and trichloroethene (TCE), mainly in the Fe0 layer. One column was bioaugmented with Shevanella algae BRY, an iron-reducing bacterium that could enhance Fe0 reactivity by reductive dissolution of passivating iron oxides. This strain did not enhance Cr(VI), which was rapidly reduced by iron, leaving little room for improvement by microbial participation. Nevertheless, BRY-enhanced nitrate removal (from 15% to 80%), partly because this strain has a wide range of electron acceptors, including nitrate. Sulfate was removed (55%) only in a column that was bioaugmented with a mixed culture containing sulfate-reducing bacteria. Apparently, these bacteria used H2 (produced by Fe0 corrosion) as electron donor to respire sulfate. Most of the TCE was degraded in the zone containing Fe0 (50-70%), and bioaugmentation with BRY slightly increased the removal efficiency to about 80%. Microbial colonization of the Fe0 surface was confirmed by scanning electron microscopy.

Bubble Size Distribution in a Vibrating Bubble Column

NASA Astrophysics Data System (ADS)

Mohagheghian, Shahrouz; Wilson, Trevor; Valenzuela, Bret; Hinds, Tyler; Moseni, Kevin; Elbing, Brian

2016-11-01

While vibrating bubble columns have increased the mass transfer between phases, a universal scaling law remains elusive. Attempts to predict mass transfer rates in large industrial scale applications by extrapolating laboratory scale models have failed. In a stationary bubble column, mass transfer is a function of phase interfacial area (PIA), while PIA is determined based on the bubble size distribution (BSD). On the other hand, BSD is influenced by the injection characteristics and liquid phase dynamics and properties. Vibration modifies the BSD by impacting the gas and gas-liquid dynamics. This work uses a vibrating cylindrical bubble column to investigate the effect of gas injection and vibration characteristics on the BSD. The bubble column has a 10 cm diameter and was filled with water to a depth of 90 cm above the tip of the orifice tube injector. BSD was measured using high-speed imaging to determine the projected area of individual bubbles, which the nominal bubble diameter was then calculated assuming spherical bubbles. The BSD dependence on the distance from the injector, injector design (1.6 and 0.8 mm ID), air flow rates (0.5 to 5 lit/min), and vibration conditions (stationary and vibration conditions varying amplitude and frequency) will be presented. In addition to mean data, higher order statistics will also be provided.

Plan for assessment of the occurrence, status, and distribution of volatile organic compounds in aquifers of the United States

USGS Publications Warehouse

Lapham, W.W.; Tadayon, Saeid

1996-01-01

aquifers, that are currently used or have the potential to be used as sources of water supplies, using data collected as part of local, State, and Federal ground-water monitoring programs since 1985. Assessment by aquifer and comparison of results among aquifers will be completed for those aquifers for which adequate spatial or depth-related data are available. Assessment of VOCs in aquifers also will be completed at regional and national scales. A set of criteria for well-network design, well construction, sample-collection methods, and methods of laboratory analysis must be met before VOC data are used for assessment. An appropriate well-network design will provide a generally unbiased, random, equal-area distribution of sampling sites throughout the aquifer, or part of the aquifer, of interest. Well-construction information must be sufficient to ensure that the hydrogeologic unit (or units) represented by the water level measured and the hydrologic unit (or units) contributing water to the well are known. In addition, the well construction and pumping equipment in the well need to be of a type that are not likely to affect concentrations of VOCs in the water sample. VOC data will be considered suitable for use in the occurrence assessment if nationally accepted methods for collection and analysis were used and if the quantitation level for VOC analytes was less than about 5 micrograms per liter; laboratory analysis was done by a laboratory certified by the U.S. Environ- mental Protection Agency; and the sample was collected from untreated (raw) water at or near the well head before being held in a pressure tank or holding tank.

The Sparta Aquifer: A Sustainable Water Resource?

USGS Publications Warehouse

McKee, Paul W.; Hays, Phillip D.

2002-01-01

Introduction The Sparta aquifer is an aquifer of regional importance within the Mississippi embayment aquifer system. It consists of varying amounts of unconsolidated sand, inter-stratified with silt and clay lenses within the Sparta Sand of the Claiborne Group. It extends from south Texas, north into Louisiana, Arkansas, and Tennessee, and eastward into Mississippi and Alabama (fig. 1). On both the west and east sides of the Mississippi embayment, the Sparta aquifer is exposed at the surface (outcrops) and is locally unconfined; it becomes confined as it dips toward the axis of the embayment, (generally corresponding with the Mississippi River) and southward toward the Gulf of Mexico where it is deeply buried in the subsurface (Hosman, 1968). Generalized ground-water flow in the Sparta aquifer is from the outcrop areas to the axis (center) of the embayment (fig. 2). In Arkansas, the Sparta aquifer outcrops parallel to the Fall Line at the western extreme of the Mississippi embayment (the Fall Line is a line dividing the mountainous highlands of Arkansas from the lowland area); and the formation dips from its outcrop area to the southeast. The Sparta aquifer supplies water for municipalities, industries such as paper production, and to a lesser degree, irrigation of agricultural crops (fig. 3). This report highlights hydrologic conditions of the aquifer in Arkansas County as an example of how water use is affecting water levels.

Geohydrologic systems in Kansas physical framework of the upper aquifer unit in the western interior plains aquifer system

USGS Publications Warehouse

Hansen, Cristi V.; Spinazola, Joseph M.; Underwood, E.J.; Wolf, R.J.

1992-01-01

The purpose of this Hydrologic Investigations Atlas is to provide a description of the principal geohydrologic systems in Upper Cambrian through Lower Cretaceous rocks in Kansas. This investigation was made as part of the Central Midwest Regional Aquifer-System Analysis (CMRASA). The CMRASA is one of several major investigations by the U.S. Geological Survey of regional aquifer systems in the United States. These regional investigations are designed to increase knowledge of the flow regime and hydrologic properties of major aquifer systems and to provide quantitative information for the assessment, development, and management water supplies. The CMRASA study area includes all or parts of 10 Central Midwestern States (Jorgensen and Signor, 1981), as shown on the envelope cover.This Hydrologic Investigations Atlas, which consists of a series of nine chapters, presents a description of the physical framework and the geohydrology of principal aquifers and confining systems in Kansas. Chapter D presents maps that show the areal extent, altitude and configuration of the top, and thickness of Mississippian rocks that compose the upper aquifer unit of the Western Interior Plains aquifer system in Kansas, The chapter is limited to the presentation of the physical framework of the upper aquifer unit. The interpretation of the physical framework of the upper aquifer unit is based on selected geophysical and lithologic logs and published maps of stratigraphically equivalent units. Maps indicating the thickness and the altitude and configuration of the top of the upper aquifer unit in the Western Interior Plains aquifer system have been prepared as part of a series of interrelated maps that describe the stratigraphic interval from the Precambrian basement through Lower Cretaceous rocks. A concerted effort was made to ensure that maps of each geohydrologic unit are consistent with the maps of underlying and overlying units. Chapter A of this atlas series (Wolf and others, 1990

Mg Isotope Evolution During Water-Rock Interaction in a Carbonate Aquifer

NASA Astrophysics Data System (ADS)

Zhang, Z.; Jacobson, A. D.; Lundstrom, C. C.; Huang, F.

2008-12-01

To better understand how Mg isotopes behave during weathering and aqueous transport, we used a Nu Plasma MC-ICP-MS to measure δ26Mg values (relative to DSM-3) in water samples along a 236 km flow path in the Madison aquifer of South Dakota, a confined carbonate aquifer recharging in the igneous Black Hills. We also analyzed local granite and dolomite samples to characterize the Mg isotope composition of source rocks constituting the recharge zone and aquifer, respectively. Repeated analyses of Mg standard solutions yielded external precisions (2σ) better than 0.1 permil for δ26Mg(CAM-1, - 2.584±0.071, n=13; UIMg-1, -2.217±0.087, n=9.). The Madison aquifer provides a unique opportunity to quantify Mg isotope effects during water-rock interaction because (1) fluids and rock have chemically equilibrated over a much longer timescale (up to ~15 kyr) than can be simulated in laboratory experiments and (2) previous studies have determined the rates and mass-balances of de- dolomitization and other geochemical reactions controlling solute evolution along the flow path. Reactions important for changing the concentration and isotope composition of Mg include dolomite dissolution, Mg-for- Na ion exchange, calcite precipitation, and isotope exchange. δ26Mg values within the recharge region (0-17 km along flow path) vary between -1.08 and -1.63 permil, and then remain essentially constant at -1.408±0.010 permil(1σ, 5 samples) from 17 to 189 km. A final sample at 236 km shows an increase to -1.09 permil. Either mixing between different recharge waters or rapid isotope exchange between infiltrating waters and dolomite could control δ26Mg variability between 0 and 17 km. Likewise, reactive transport modeling suggests that preferential uptake of 24Mg during Mg-for-Na ion exchange might cause an increase in δ26Mg between 189 and 236 km. However, unchanging δ26Mg values observed throughout most of the aquifer clearly demonstrate that Mg isotopes are not fractionated during

Effect of hypersaline cooling canals on aquifer salinization

USGS Publications Warehouse

Hughes, Joseph D.; Langevin, Christian D.; Brakefield-Goswami, Linzy

2010-01-01

The combined effect of salinity and temperature on density-driven convection was evaluated in this study for a large (28 km2) cooling canal system (CCS) at a thermoelectric power plant in south Florida, USA. A two-dimensional cross-section model was used to evaluate the effects of hydraulic heterogeneities, cooling canal salinity, heat transport, and cooling canal geometry on aquifer salinization and movement of the freshwater/saltwater interface. Four different hydraulic conductivity configurations, with values ranging over several orders of magnitude, were evaluated with the model. For all of the conditions evaluated, aquifer salinization was initiated by the formation of dense, hypersaline fingers that descended downward to the bottom of the 30-m thick aquifer. Saline fingers reached the aquifer bottom in times ranging from a few days to approximately 5 years for the lowest hydraulic conductivity case. Aquifer salinization continued after saline fingers reached the aquifer bottom and coalesced by lateral movement away from the site. Model results showed that aquifer salinization was most sensitive to aquifer heterogeneity, but was also sensitive to CCS salinity, temperature, and configuration.

Immunoaffinity column cleanup with liquid chromatography using postcolumn bromination for the determination of aflatoxins in black and white sesame seed: single-laboratory validation.

PubMed

Liu, Guihua; Zhu, Zhou; Cheng, Jinquan; Senyuva, Hamide Z

2012-01-01

A single-laboratory validation was conducted to establish the effectiveness of an immunoaffinity column cleanup procedure followed by LC with fluorescence detection for the determination of aflatoxins B1, B2, G1, and G2 in sesame seeds. The sample is homogenized with 50% water (w/w) to form a slurry, then the test portion is extracted with methanol-water (60 + 40, v/v) using a high-speed blender. The sample extract is filtered, diluted with 15% Tween 20 in phosphate-buffered saline solution, and applied to an immunoaffinity column. Aflatoxins are removed with neat methanol, then directly determined by RP-LC with fluorescence detection using postcolumn bromination (Kobra cell). Test portions of blank white sesame seed slurry were spiked with a mixture of aflatoxins to give total levels of 4 and 10 microg/kg. Recoveries for individual and total aflatoxins ranged from 92.7 to 110.3% for spiked samples. Based on results for spiked sesame paste (triplicates at two levels), the RSD for repeatability (RSD(r)) averaged 1.1% for total aflatoxins and 1.4% for aflatoxin B1. The method was demonstrated to be applicable to naturally contaminated samples of black and white sesame seeds obtained from local markets in China.

Transport of chromium and selenium in a pristine sand and gravel aquifer: Role of adsorption processes

USGS Publications Warehouse

Kent, D.B.; Davis, J.A.; Anderson, L.C.D.; Rea, B.A.

1995-01-01

Field transport experiments were conducted in an oxic sand and gravel aquifer using Br (bromide ion), Cr (chromium, injected as Cr(VI)), Se (selenium, injected as Se(VI)), and other tracers. The aquifer has mildly acidic pH values and low concentrations of dissolved salts. Within analytical errors, all mobile Cr was present as Cr(VI). All mobile Se was probably present as Se(VI). Adsorption of Cr and Se onto aquifer sediments caused retardation of both tracers. Breakthrough curves for Cr and Se had extensive tails, which caused large decreases in their maximum concentrations relative to the nonreactive Br tracer after only 2.0 m of transport. A surface complexation model was applied to the results of laboratory studies of Cr(VI) adsorption on aquifer solids from the site based on adsorption onto hydrous ferric oxide. The modeling results suggested that the dominant adsorbents in the aquifer solids have lower affinities for anion adsorption than pure hydrous ferric oxide. The steep rising limbs and extensive tails observed in most of the breakthrough curves are qualitatively consistent with the equilibrium surface complexation model; however, slow rates of adsorption and desorption may have contributed to these features. Variations during transport in the concentrations of Cr, Se, and other anions competing for adsorption sites likely gave rise to variations in the extent of adsorption. Adequate description of the observed retardation of Cr and Se would require a coupled transport-adsorption model that can account for these effects. Companion experiments in the mildly reducing zone of the aquifer (Kent et al., 1994) showed a loss of Cr mass, probably resulting from reduction to Cr(III), and little retardation of mobile Cr and Se during transport; this contrast illustrates the influence of aquifer chemistry on the transport of redox-sensitive solutes.

Digital spatial data for predicted nitrate and arsenic concentrations in basin-fill aquifers of the Southwest Principal Aquifers study area

USGS Publications Warehouse

McKinney, Tim S.; Anning, David W.

2012-01-01

This product "Digital spatial data for predicted nitrate and arsenic concentrations in basin-fill aquifers of the Southwest Principal Aquifers study area" is a 1:250,000-scale vector spatial dataset developed as part of a regional Southwest Principal Aquifers (SWPA) study (Anning and others, 2012). The study examined the vulnerability of basin-fill aquifers in the southwestern United States to nitrate contamination and arsenic enrichment. Statistical models were developed by using the random forest classifier algorithm to predict concentrations of nitrate and arsenic across a model grid that represents local- and basin-scale measures of source, aquifer susceptibility, and geochemical conditions.

Aquifer geochemistry at potential aquifer storage and recovery sites in coastal plain aquifers in the New York city area, USA

USGS Publications Warehouse

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

JCE Feature Columns

NASA Astrophysics Data System (ADS)

Holmes, Jon L.

1999-05-01

The Features area of JCE Online is now readily accessible through a single click from our home page. In the Features area each column is linked to its own home page. These column home pages also have links to them from the online Journal Table of Contents pages or from any article published as part of that feature column. Using these links you can easily find abstracts of additional articles that are related by topic. Of course, JCE Online+ subscribers are then just one click away from the entire article. Finding related articles is easy because each feature column "site" contains links to the online abstracts of all the articles that have appeared in the column. In addition, you can find the mission statement for the column and the email link to the column editor that I mentioned above. At the discretion of its editor, a feature column site may contain additional resources. As an example, the Chemical Information Instructor column edited by Arleen Somerville will have a periodically updated bibliography of resources for teaching and using chemical information. Due to the increase in the number of these resources available on the WWW, it only makes sense to publish this information online so that you can get to these resources with a simple click of the mouse. We expect that there will soon be additional information and resources at several other feature column sites. Following in the footsteps of the Chemical Information Instructor, up-to-date bibliographies and links to related online resources can be made available. We hope to extend the online component of our feature columns with moderated online discussion forums. If you have a suggestion for an online resource you would like to see included, let the feature editor or JCE Online (jceonline@chem.wisc.edu) know about it. JCE Internet Features JCE Internet also has several feature columns: Chemical Education Resource Shelf, Conceptual Questions and Challenge Problems, Equipment Buyers Guide, Hal's Picks, Mathcad

Column Liquid Chromatography.

ERIC Educational Resources Information Center

Majors, Ronald E.; And Others

1984-01-01

Reviews literature covering developments of column liquid chromatography during 1982-83. Areas considered include: books and reviews; general theory; columns; instrumentation; detectors; automation and data handling; multidimensional chromatographic and column switching techniques; liquid-solid chromatography; normal bonded-phase, reversed-phase,…

Experimental Research of FRP Composite Tube Confined Steel-reinforced Concrete Stub Columns Under Axial Compression

NASA Astrophysics Data System (ADS)

Wang, Ji Zhong; Cheng, Lu; Wang, Xin Pei

2018-06-01

A new column of FRP composite tube confined steel-reinforced concrete (FTCSRC) column was proposed. This paper elaborates on laboratorial and analytical studies on the behavior of FCTSRC columns subjected to axial compressive load. Eight circular FTCSRC stub columns and one circular steel tube confined concrete (STCC) stub column were tested to investigate the failure mode and axial compression performance of circular FTCRSC columns. Parametric analysis was implemented to inquire the influence of confinement material (CFRP-steel tube or CFRP-GFRP tube), internal steel and CFRP layers on the ultimate load capacity. CFRP-steel composite tube was composed of steel tube and CFRP layer which was wrapped outside the steel tube, while CFRP-GFRP composite tube was composite of GFRP tube and CFRP layer. The test results indicate that the confinement effect of CFRP-steel tube is greatly superior to CFRP-GFRP tube. The ductility performance of steel tube confined high-strength concrete column can be improved obviously by encasing steel in the core concrete. Furthermore, with the increase in the layers of FRP wraps, the axial load capacity increases greatly.

Optimal remediation of unconfined aquifers: Numerical applications and derivative calculations

NASA Astrophysics Data System (ADS)

Mansfield, Christopher M.; Shoemaker, Christine A.

1999-05-01

This paper extends earlier work on derivative-based optimization for cost-effective remediation to unconfined aquifers, which have more complex, nonlinear flow dynamics than confined aquifers. Most previous derivative-based optimization of contaminant removal has been limited to consideration of confined aquifers; however, contamination is more common in unconfined aquifers. Exact derivative equations are presented, and two computationally efficient approximations, the quasi-confined (QC) and head independent from previous (HIP) unconfined-aquifer finite element equation derivative approximations, are presented and demonstrated to be highly accurate. The derivative approximations can be used with any nonlinear optimization method requiring derivatives for computation of either time-invariant or time-varying pumping rates. The QC and HIP approximations are combined with the nonlinear optimal control algorithm SALQR into the unconfined-aquifer algorithm, which is shown to compute solutions for unconfined aquifers in CPU times that were not significantly longer than those required by the confined-aquifer optimization model. Two of the three example unconfined-aquifer cases considered obtained pumping policies with substantially lower objective function values with the unconfined model than were obtained with the confined-aquifer optimization, even though the mean differences in hydraulic heads predicted by the unconfined- and confined-aquifer models were small (less than 0.1%). We suggest a possible geophysical index based on differences in drawdown predictions between unconfined- and confined-aquifer models to estimate which aquifers require unconfined-aquifer optimization and which can be adequately approximated by the simpler confined-aquifer analysis.

Reconsideration at Field Scale of the Relationship between Hydraulic Conductivity and Porosity: The Case of a Sandy Aquifer in South Italy

PubMed Central

2014-01-01

To describe flow or transport phenomena in porous media, relations between aquifer hydraulic conductivity and effective porosity can prove useful, avoiding the need to perform expensive and time consuming measurements. The practical applications generally require the determination of this parameter at field scale, while most of the empirical and semiempirical formulas, based on grain size analysis and allowing determination of the hydraulic conductivity from the porosity, are related to the laboratory scale and thus are not representative of the aquifer volumes to which one refers. Therefore, following the grain size distribution methodology, a new experimental relation between hydraulic conductivity and effective porosity, representative of aquifer volumes at field scale, is given for a confined aquifer. The experimental values used to determine this law were obtained for both parameters using only field measurements methods. The experimental results found, also if in the strict sense valid only for the investigated aquifer, can give useful suggestions for other alluvial aquifers with analogous characteristics of grain-size distribution. Limited to the investigated range, a useful comparison with the best known empirical formulas based on grain size analysis was carried out. The experimental data allowed also investigation of the existence of a scaling behaviour for both parameters considered. PMID:25180202

Radiogenic 4He as a conservative tracer in buried‐valley aquifers

USGS Publications Warehouse

Van der Hoven, Stephen J.; Wright, R. Erik; Carstens, David A.; Hackley, Keith C.

2005-01-01

The accumulation of 4He in groundwater can be a powerful tool in hydrogeologic investigations. However, the use of 4He often suffers from disagreement or uncertainty related to in situ and external sources of 4He. In situ sources are quantified by several methods, while external sources are often treated as calibration parameters in modeling. We present data from direct laboratory measurements of 4He release from sediments and field data of dissolved 4He in the Mahomet Aquifer, a well‐studied buried‐valley aquifer in central Illinois. The laboratory‐derived accumulation rates (0.13–0.91 μcm3 STP kgwater−1 yr−1) are 1–2 orders of magnitude greater than the accumulation rates based on the U and Th concentrations of the sediments (0.004–0.009 μcm3 STP kgwater−1 yr−1). The direct measurement of accumulation rates are more consistent with dissolved concentrations of 4He in the groundwater. We suggest that the direct measurement method is applicable in a variety of hydrogeologic settings. The patterns of accumulation of 4He are consistent with the conceptual model of flow in the aquifer based on hydraulic and geochemical evidence and show areas where in situ production and external sources of 4He are dominant. In the southwestern part of the study area, Ne concentrations are less than atmospheric solubility, indicating gases have been lost from the groundwater. Available evidence indicates that the gases are lost as groundwater passes by pockets of CH4 in glacial deposits overlying the aquifer. However, the external flux from the underlying bedrock appears to dominate the accumulation of radiogenic 4He in the aquifer in the southwestern part of the study area, and the loss or gain of helium as groundwater passes through the overlying sediments is minor in comparison.

Surface complexation modeling for predicting solid phase arsenic concentrations in the sediments of the Mississippi River Valley alluvial aquifer, Arkansas, USA

USGS Publications Warehouse

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.

On the aquitard-aquifer interface flow and the drawdown sensitivity with a partially penetrating pumping well in an anisotropic leaky confined aquifer

NASA Astrophysics Data System (ADS)

Feng, Qinggao; Zhan, Hongbin

2015-02-01

A mathematical model for describing groundwater flow to a partially penetrating pumping well of a finite diameter in an anisotropic leaky confined aquifer is developed. The model accounts for the jointed effects of aquitard storage, aquifer anisotropy, and wellbore storage by treating the aquitard leakage as a boundary condition at the aquitard-aquifer interface rather than a volumetric source/sink term in the governing equation, which has never developed before. A new semi-analytical solution for the model is obtained by the Laplace transform in conjunction with separation of variables. Specific attention was paid on the flow across the aquitard-aquifer interface, which is of concern if aquitard and aquifer have different pore water chemistry. Moreover, Laplace-domain and steady-state solutions are obtained to calculate the rate and volume of (total) leakage through the aquitard-aquifer interface due to pump in a partially penetrating well, which is also useful for engineers to manager water resources. The sensitivity analyses for the drawdown illustrate that the drawdown is most sensitive to the well partial penetration. It is apparently sensitive to the aquifer anisotropic ratio over the entire time of pumping. It is moderately sensitive to the aquitard/aquifer specific storage ratio at the intermediate times only. It is moderately sensitive to the aquitard/aquifer vertical hydraulic conductivity ratio and the aquitard/aquifer thickness ratio with the identical influence at late times.

Transformations of Nitrogen from Secondary Treated Wastewater when Infiltrated in Managed Aquifer Recharge Schemes

NASA Astrophysics Data System (ADS)

Silver, Matthew; Wefer-Roehl, Annette; Kübeck, Christine; Schüth, Christoph

2016-04-01

The EU FP7 project MARSOL seeks to address water scarcity challenges in arid regions, where managed aquifer recharge (MAR) is an upcoming technology to recharge depleted aquifers using alternative water sources. Within this framework, we conduct column experiments to investigate transformations of nitrogen species when secondary treated wastewater (STWW) is infiltrated through two natural soils being considered for managed aquifer recharge. The soils vary considerably in organic matter content, with total organic matter determined by loss on ignition of 6.8 and 2.9 percent by mass for Soil 1 and Soil 2, respectively. Ammonium (NH4+) concentrations as high as 8.6 mg/L have been measured in pore water samples from Soil #1, indicating that ammonium could be a contaminant of concern in MAR applications using STWW, with consideration of the EU limit of 0.5 mg/L for NH4+. The two forms of nitrogen with the highest concentrations in the secondary treated wastewater are nitrate (NO3-) and dissolved organic nitrogen (DON). In water samples taken from the soil columns, a mass balance of measured ions shows a deficit of nitrogen in ionic form in the upper to middle depths of the soil, suggesting the presence of unmeasured species. These are likely nitrous oxide or dinitrogen gas, which would signify that denitrification is occurring. Measurements of N2O from water samples will verify its presence and spatial variation. The ammonium concentrations increase slowly in the upper parts of the soil but then increase more sharply at greater depth, after NO3- is depleted, suggesting that DON is the source of the produced NH4+. The production of NH4+ is presumed to be facilitated microbiologically. It is hypothesized that at higher organic carbon to total nitrogen (C:N) ratios, more NH4+ will be formed. To test this, in the experiments with Soil #2, three different inflow waters are used, listed in order of decreasing C:N ratio: STWW, STWW with NO3- added to a concentration of 80 mg

Optimization of the Implementation of Managed Aquifer Recharge - Effects of Aquifer Heterogeneity

NASA Astrophysics Data System (ADS)

Maliva, Robert; Missimer, Thomas; Kneppers, Angeline

2010-05-01

Managed aquifer recharge (MAR) has become a key component of integrated water resources management, especially in water scarce regions. MAR can serve the dual role of increasing the supply of available water and improving the quality of recharged water through natural attenuation processes. The performance of MAR systems is highly dependent upon site-specific hydrogeological conditions. Aquifer heterogeneity, such as the presence of high-permeability preferential flow zones and dual or even the so-called triple-porosity conditions, has been responsible for the under performance or failure of some MAR systems. Aquifer heterogeneity can result in much more rapid and unpredictable movement and mixing of recharged water and the bypassing of natural attenuation processes. A critical element of MAR projects is a detailed aquifer characterization and the development of groundwater flow and solute transport models at the appropriate spatial and temporal scales that accurately simulate local heterogeneous flow systems. Geochemical modeling based on high-quality, site-specific mineralogical and water chemistry data can also be used to predict the potential for adverse water-rock interactions such as the leaching of arsenic and trace metals into recharged water. Hydrogeological conditions that could lead to poor system performance should be identified early in the project development before the investment is made to construct a full-scale system. Hydrogeological conditions that have lead to poor MAR system performance are typically identifiable at the exploratory well stage of projects. Early detection of adverse hydrogeological conditions provides an opportunity to either abandon a likely under-performing project, select an alternative site with more favorable conditions, or modify the system design to be more compatible with local hydrogeology. Advanced borehole geophysical techniques and workflow software can allow for enhanced aquifer characterization and thus allow for

Hydrological controls on transient aquifer storage in a karst watershed

NASA Astrophysics Data System (ADS)

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.

Arsenic Remediation Enhancement Through Chemical Additions to Pump and Treat Operations

NASA Astrophysics Data System (ADS)

Wovkulich, K.; Mailloux, B. J.; Stute, M.; Simpson, H. J.; Keimowitz, A. R.; Powell, A.; Lacko, A.; Chillrud, S. N.

2008-12-01

Arsenic is a contaminant found at more than 500 US Superfund sites. Since pump and treat technologies are widely used for remediation of contaminated groundwater, increasing the efficiency of contaminant removal at such sites should allow limited financial resources to clean up more sites. The Vineland Chemical Company Superfund site is extensively contaminated with arsenic after waste arsenic salts were stored and disposed of improperly for much of the company's 44 year manufacturing lifetime. Despite approximately eight years of pump and treat remediation, arsenic concentrations in the recovery wells can still be greater than 1000 ppb. The arsenic concentrations in the groundwater remain high because of slow desorption of arsenic from contaminated aquifer solids. Extrapolation of laboratory column experiments suggest that continuing the current groundwater remediation practice based on flushing ambient groundwater through the system may require on the order of hundreds of years to clean the site. However, chemical additions of phosphate or oxalic acid into the aquifer could decrease the remediation time scale substantially. Laboratory results from a soil column experiment using input of 10 mM oxalic acid suggest that site clean up of groundwater could be decreased to as little as four years. Pilot scale forced gradient field experiments will help establish whether chemical additions can be effective for increasing arsenic mobilization from aquifer solids and thus substantially decrease pump and treat clean up time.

In-situ biochemical remediation of chlorinated organic compounds present as DNAPL using vitamin B12 and reduced titanium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lesage, S.; Sorel, D.; Cherry, J.A.

1995-12-31

The feasibility of using a biochemical treatment for the cleanup of DNAPL solvents in the saturated zone was tested using an in-situ large vertical column. Laboratory column studies have shown that a mixture of vitamin B12 and titanium citrate pumped through a column containing 100 {mu}L of tetrachloroethene can completely dissolve and degrade the residual to ethene in a few days. A vertical test column, 80 cm in diameter was installed within a sheet-pile cell isolating a portion of aquifer at CFB Borden. An equimolar mixture of tetrachloroethene and 1,1,1-trichloroethane was injected below the water table to form a residualmore » DNAPL. The injection withdrawal system was operated in an upward flow mode over a 2 m height. In order for the reaction to be proceed, the in-situ pH must be greater than 7 and the Eh lower than -480 mV. The redox of the aquifer and the formation of reaction products was monitored on site, through 8 side pods equipped with stainless steel tubing terminated with 40 {mu}m porous cups, installed at different heights in the test column. The volatile products at the withdrawal well were monitored on-line by dynamic headspace analysis/gas chromatography.« less

Experimental Design for One Dimensional Electrolytic Reactive Barrier for Remediation of Munition Constituent in Groundwater

PubMed Central

Gent, David B.; Wani, Altaf; Alshawabkeh, Akram N.

2012-01-01

A combination of direct electrochemical reduction and in-situ alkaline hydrolysis has been proposed to decompose energetic contaminants such as 1,3,5-Trinitroperhydro- 1,3,5-triazine and 2,4,6-Trinitrotoluene (RDX) in deep aquifers. This process utilizes natural groundwater convection to carry hydroxide produced by an upstream cathode to remove the contaminant at the cathode as well as in the pore water downstream as it migrates toward the anode. Laboratory evaluation incorporated fundamental principles of column design coupled with reactive contaminant modeling including electrokinetics transport. Batch and horizontal sand-packed column experiments included both alkaline hydrolysis and electrochemical treatment to determine RDX decomposition reaction rate coefficients. The sand packed columns simulated flow through a contaminated aquifer with a seepage velocity of 30.5 cm/day. Techniques to monitor and record the transient electric potential, hydroxide transport and contaminant concentration within the column were developed. The average reaction rate coefficients for both the alkaline batch (0.0487 hr−1) and sand column (0.0466 hr−1) experiments estimated the distance between the cathode and anode required to decompose 0.5 mg/L RDX to the USEPA drinking water lifetime Health Advisory level of 0.002 mg/L to be 145 and 152 cm. PMID:23472044

Estimating Preferential Flow in Karstic Aquifers Using Statistical Mixed Models

PubMed Central

Anaya, Angel A.; Padilla, Ingrid; Macchiavelli, Raul; Vesper, Dorothy J.; Meeker, John D.; Alshawabkeh, Akram N.

2013-01-01

Karst aquifers are highly productive groundwater systems often associated with conduit flow. These systems can be highly vulnerable to contamination, resulting in a high potential for contaminant exposure to humans and ecosystems. This work develops statistical models to spatially characterize flow and transport patterns in karstified limestone and determines the effect of aquifer flow rates on these patterns. A laboratory-scale Geo-HydroBed model is used to simulate flow and transport processes in a karstic limestone unit. The model consists of stainless-steel tanks containing a karstified limestone block collected from a karst aquifer formation in northern Puerto Rico. Experimental work involves making a series of flow and tracer injections, while monitoring hydraulic and tracer response spatially and temporally. Statistical mixed models are applied to hydraulic data to determine likely pathways of preferential flow in the limestone units. The models indicate a highly heterogeneous system with dominant, flow-dependent preferential flow regions. Results indicate that regions of preferential flow tend to expand at higher groundwater flow rates, suggesting a greater volume of the system being flushed by flowing water at higher rates. Spatial and temporal distribution of tracer concentrations indicates the presence of conduit-like and diffuse flow transport in the system, supporting the notion of both combined transport mechanisms in the limestone unit. The temporal response of tracer concentrations at different locations in the model coincide with, and confirms the preferential flow distribution generated with the statistical mixed models used in the study. PMID:23802921

Effects Of Evaporation Rate of Some Common Organic Contaminants on Hydraulic Conductivity of Aquifer Sand

NASA Astrophysics Data System (ADS)

Saud, Q. J.; Hasan, S. E.

2014-12-01

As part of a larger study to investigate potential effects of hydrocarbons on the geotechnical properties of aquifer solids, a series of laboratory experiments were carried out to ascertain the influence of evaporation rate of some common and widespread organic contaminants on the hydraulic conductivity of aquifer sand. Gasoline and its constituent chemicals-benzene, toluene, ethylbenzene, xylene (BTEX), isooctane- and trichloroethylene (TCE) were used to contaminate sand samples collected from the aquifer and vadose zone, at varying concentrations for extended periods of time. The goal was to study any change in the chemical makeup of the contaminants and its control on hydraulic conductivity of the sand. It was found that: (a) gasoline breaks down into constituent compounds when subjected to evaporation, e.g. during oil spills and leaks; and (b) lighter compounds volatilize faster and in the following order: TCE> benzene > isooctane > toluene > gasoline> ethylbenzene > xylene. In addition, these contaminants also caused a decrease in hydraulic conductivity of sand by up to 60% as compared to the uncontaminated sand. The inherent differences in the chemical structure of contaminating chemicals influenced hydraulic conductivity such that the observed decrease was greater for aliphatic than aromatic and chlorinated hydrocarbons. The presentation includes details of the experimental set up; evaporation rate, and geotechnical tests; X-ray diffraction and scanning electron microscope studies; and data analyses and interpretation. Rate of evaporation test indicates that residual LNAPLs will occupy a certain portion of the pores in the soil either as liquid or vapor phase in the vadose zone, and will create a coating on the adjacent solid mineral grains in the aquifer. Replacement of air by the LNAPLs along with grain coatings and the intramolecular forces would impede groundwater movement, thus affecting overall permeability of contaminated aquifers. Keywords: aquifer

Source, variability, and transformation of nitrate in a regional karst aquifer: Edwards aquifer, central Texas.

USGS Publications Warehouse

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

Hydrogeology and simulation of ground-water flow and land-surface subsidence in the Chicot and Evangeline aquifers, Houston area, Texas

USGS Publications Warehouse

Kasmarek, Mark C.; Strom, Eric W.

2002-01-01

In November 1997, the U.S. Geological Survey, in cooperation with the City of Houston Utilities Planning Section and the City of Houston Department of Public Works & Engineering, began an investigation of the Chicot and Evangeline aquifers in the greater Houston area in Texas to better understand the hydrology, flow, and associated land-surface subsidence. The principal part of the investigation was a numerical finite-difference model (MODFLOW) developed to simulate ground-water flow and land-surface subsidence in an 18,100-square-mile area encompassing greater Houston.The focus of the study was Harris and Galveston Counties, but other counties were included to achieve the appropriate boundary conditions. The model was vertically discretized into three 103-row by 109-column layers resulting in a total of 33,681 grid cells. Layer 1 represents the water table using a specified head, layer 2 represents the Chicot aquifer, and layer 3 represents the Evangeline aquifer.Simulations were made under transient conditions for 31 ground-water-withdrawal (stress) periods spanning 1891–1996. The years 1977 and 1996 were chosen as potentiometric-surface calibration periods for the model. Simulated and measured potentiometric surfaces of the Chicot and Evangeline aquifers for 1977 match closely. Waterlevel measurements indicate that by 1977, large ground-water withdrawals in east-central and southeastern areas of Harris County had caused the potentiometric surfaces to decline as much as 250 feet below sea level in the Chicot aquifer and as much as 350 feet below sea level in the Evangeline aquifer. Simulated and measured potentiometric surfaces of the Chicot and Evangeline aquifers for 1996 also match closely. The large potentiometric-surface decline in 1977 in the southeastern Houston area showed significant recovery by 1996. The 1996 centers of potentiometric-surface decline are located much farther northwest. Potentiometric-surface declines of more than 200 feet below sea

Evaluation of a pumping test of the Snake River Plain aquifer using axial-flow numerical modeling

NASA Astrophysics Data System (ADS)

Johnson, Gary S.; Frederick, David B.; Cosgrove, Donna M.

2002-06-01

The Snake River Plain aquifer in southeast Idaho is hosted in a thick sequence of layered basalts and interbedded sediments. The degree to which the layering impedes vertical flow has not been well understood, yet is a feature that may exert a substantial control on the movement of contaminants. An axial-flow numerical model, RADFLOW, was calibrated to pumping test data collected by a straddle-packer system deployed at 23 depth intervals in four observation wells to evaluate conceptual models and estimate properties of the Snake River Plain aquifer at the Idaho National Engineering and Environmental Laboratory. A delayed water-table response observed in intervals beneath a sediment interbed was best reproduced with a three-layer simulation. The results demonstrate the hydraulic significance of this interbed as a semi-confining layer. Vertical hydraulic conductivity of the sediment interbed was estimated to be about three orders of magnitude less than vertical hydraulic conductivity of the lower basalt and upper basalt units. The numerical model was capable of representing aquifer conceptual models that could not be represented with any single analytical technique. The model proved to be a useful tool for evaluating alternative conceptual models and estimating aquifer properties in this application.

40 CFR 147.3003 - Aquifer exemptions.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., Ute Mountain Ute, and All Other New Mexico Tribes § 147.3003 Aquifer exemptions. (a) Aquifer... cleanup plan shall include an analysis of pre-injection water quality for the constituents required by the...

40 CFR 147.3003 - Aquifer exemptions.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., Ute Mountain Ute, and All Other New Mexico Tribes § 147.3003 Aquifer exemptions. (a) Aquifer... cleanup plan shall include an analysis of pre-injection water quality for the constituents required by the...

Aquifer Recharge Estimation In Unsaturated Porous Rock Using Darcian And Geophysical Methods.

NASA Astrophysics Data System (ADS)

Nimmo, J. R.; De Carlo, L.; Masciale, R.; Turturro, A. C.; Perkins, K. S.; Caputo, M. C.

2016-12-01

Within the unsaturated zone a constant downward gravity-driven flux of water commonly exists at depths ranging from a few meters to tens of meters depending on climate, medium, and vegetation. In this case a steady-state application of Darcy's law can provide recharge rate estimates.We have applied an integrated approach that combines field geophysical measurements with laboratory hydraulic property measurements on core samples to produce accurate estimates of steady-state aquifer recharge, or, in cases where episodic recharge also occurs, the steady component of recharge. The method requires (1) measurement of the water content existing in the deep unsaturated zone at the location of a core sample retrieved for lab measurements, and (2) measurement of the core sample's unsaturated hydraulic conductivity over a range of water content that includes the value measured in situ. Both types of measurements must be done with high accuracy. Darcy's law applied with the measured unsaturated hydraulic conductivity and gravitational driving force provides recharge estimates.Aquifer recharge was estimated using Darcian and geophysical methods at a deep porous rock (calcarenite) experimental site in Canosa, southern Italy. Electrical Resistivity Tomography (ERT) and Vertical Electrical Sounding (VES) profiles were collected from the land surface to water table to provide data for Darcian recharge estimation. Volumetric water content was estimated from resistivity profiles using a laboratory-derived calibration function based on Archie's law for rock samples from the experimental site, where electrical conductivity of the rock was related to the porosity and water saturation. Multiple-depth core samples were evaluated using the Quasi-Steady Centrifuge (QSC) method to obtain hydraulic conductivity (K), matric potential (ψ), and water content (θ) estimates within this profile. Laboratory-determined unsaturated hydraulic conductivity ranged from 3.90 x 10-9 to 1.02 x 10-5 m

Ground-water flow directions and estimation of aquifer hydraulic properties in the lower Great Miami River Buried Valley aquifer system, Hamilton Area, Ohio

USGS Publications Warehouse

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

COMBINED LABORATORY/FIELD STUDY ON THE USE OF NITRATE FOR IN SITU BIOREMEDIATION OF A FUEL-CONTAMINATED AQUIFER

EPA Science Inventory

A pilot demonstration project was conducted at Eglin Air Force Base, FL, to compare the extent of bioremediation of a fuel-contaminated aquifer using sprinkler application with and without nitrate addition on two adjacent 30 m x 30 m cells. Target compound groups included both B...

Multilevel groundwater monitoring of hydraulic head and temperature in the eastern Snake River Plain aquifer, Idaho National Laboratory, Idaho, 2009–10

USGS Publications Warehouse

Twining, Brian V.; Fisher, Jason C.

2012-01-01

During 2009 and 2010, the U.S. Geological Survey’s Idaho National Laboratory Project Office, in cooperation with the U.S. Department of Energy, collected quarterly, depth-discrete measurements of fluid pressure and temperature in nine boreholes located in the eastern Snake River Plain aquifer. Each borehole was instrumented with a multilevel monitoring system consisting of a series of valved measurement ports, packer bladders, casing segments, and couplers. Multilevel monitoring at the Idaho National Laboratory has been ongoing since 2006. This report summarizes data collected from three multilevel monitoring wells installed during 2009 and 2010 and presents updates to six multilevel monitoring wells. Hydraulic heads (heads) and groundwater temperatures were monitored from 9 multilevel monitoring wells, including 120 hydraulically isolated depth intervals from 448.0 to 1,377.6 feet below land surface. Quarterly head and temperature profiles reveal unique patterns for vertical examination of the aquifer’s complex basalt and sediment stratigraphy, proximity to aquifer recharge and discharge, and groundwater flow. These features contribute to some of the localized variability even though the general profile shape remained consistent over the period of record. Major inflections in the head profiles almost always coincided with low-permeability sediment layers and occasionally thick sequences of dense basalt. However, the presence of a sediment layer or dense basalt layer was insufficient for identifying the location of a major head change within a borehole without knowing the true areal extent and relative transmissivity of the lithologic unit. Temperature profiles for boreholes completed within the Big Lost Trough indicate linear conductive trends; whereas, temperature profiles for boreholes completed within the axial volcanic high indicate mostly convective heat transfer resulting from the vertical movement of groundwater. Additionally, temperature profiles

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

USGS Publications Warehouse

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

2004-01-01

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

Aquifers in coastal reclaimed lands - real world assessments

NASA Astrophysics Data System (ADS)

Saha, A.; Bironne, A.; Vonhögen-Peeters, L.; Lee, W. K.; Babovic, V. M.; Vermeulen, P.; van Baaren, E.; Karaoulis, M.; Blanchais, F.; Nguyen, M.; Pauw, P.; Doornenbal, P.

2017-12-01

Climate change and population growth are significant concerns in coastal regions around the world, where more than 30% of the world's population reside. The numbers continue to rise as coastal areas are increasingly urbanized. Urbanization creates land shortages along the coasts, which has spurred coastal reclamation activities as a viable solution. In this study, we focus on these reclamation areas; reclaimed areas in Singapore, and in the Netherlands, and investigate the potential of these reclaimed bodies as artificial aquifers that could attenuate water shortage problems in addition to their original purpose. We compare how the reclamation methods determine the hydrogeological characteristics of these manmade aquifers. We highlight similarities in freshwater lens development in the artificial shallow aquifers under natural recharge under diverse conditions, i.e. tropical and temperate zones, using numerical models. The characteristics and responses of these aquifers with dynamic freshwater-saltwater interface are contrasted against naturally occurring coastal aquifers where equilibrium was disturbed by anthropogenic activities. Finally, we assess the risks associated with subsidence and saltwater intrusion, combining measurements and numerical models, in case these aquifers are planned for Aquifer Storage and Recovery (ASR) or Managed Aquifer Recharge (MAR) strategies. Relative performances of some ASR schemes are simulated and compared in the reclaimed lands.

The Coffee Sand and Ripley aquifers in Mississippi

USGS Publications Warehouse

Boswell, E.H.

1978-01-01

The Coffee Sand and Ripley aquifers, of Cretaceous age, are in the Selma Group in northern Mississippi. The aquifers contain freshwater in an area of about 4,400 square miles in northern Mississippi. Water produced from the aquifers by public water systems and numerous industries in 1975 averaged about 4 Mgal/d. Regional water-level declines have been very small and the aquifers have a moderate potential for future development. The aquifers are used in some areas where there are no other significant sources of ground water. The most common problems in developing water supplies are low yields to wells and hard water. (Kosco-USGS)

Post monitoring of a cyclodextrin remeditated chlorinated solvent contaminated aquifer

NASA Astrophysics Data System (ADS)

Blanford, W. J.

2006-12-01

Hydroxypropyl-â-cyclodextrin (HPâCD) has been tested successfully in the laboratory and in the field for enhanced flushing of low-polarity contaminants from aquifers. The cyclodextrin molecule forms a toroidal structure, which has a hydrophobic cavity. Within this cavity, organic compounds of appropriate shape and size can form inclusion complexes, which is the basis for the use of cyclodextrin in groundwater remediation. The hydrophilic exterior of the molecule makes cyclodextrin highly water-soluble. The solubility of cyclodextrins can be further enhanced by adding functional groups, such as hydroxypropyl groups, to the cyclodextrin core. The aqueous solubility of HPâCD exceeds 950 g/L. These high solubilities are advantageous for field applications because they permit relatively high concentrations of the flushing agent. In order for cyclodextrin to become a feasible remediative alternative, it must be demonstrate a short term resistance to biodegradation during field application, but ultimately biodegrade so as not to pose a long term presence in the aquifer. The potential for degradation of cyclodextrin as well as changes in the chlorinated solvents and groundwater geochemistry were examined during the post monitoring of a field demonstration in a shallow aquifer at Little Creek Naval Amphibious Base in Virginia. It was found that a portion of the cyclodextrin remaining in the aquifer after the cessation of field activities biodegraded during the 425 days of post monitoring. This degradation also led to the degradation of the chlorinated solvents trichloroethylene and 1,1-trichloroethane through both biological and chemical processes. The aquifer remained anaerobic with average dissolved oxygen levels below 0.5 mg/L. Dissolved nitrate and sulfate concentrations within the cyclodextrin plume decreased due their being used as terminal electron acceptors during the degradation of the cyclodextrin. The concentrations of total iron at the field site showed no

Chemometrics applications in biotechnology processes: predicting column integrity and impurity clearance during reuse of chromatography resin.

PubMed

Rathore, Anurag S; Mittal, Shachi; Lute, Scott; Brorson, Kurt

2012-01-01

Separation media, in particular chromatography media, is typically one of the major contributors to the cost of goods for production of a biotechnology therapeutic. To be cost-effective, it is industry practice that media be reused over several cycles before being discarded. The traditional approach for estimating the number of cycles a particular media can be reused for involves performing laboratory scale experiments that monitor column performance and carryover. This dataset is then used to predict the number of cycles the media can be used at manufacturing scale (concurrent validation). Although, well accepted and widely practiced, there are challenges associated with extrapolating the laboratory scale data to manufacturing scale due to differences that may exist across scales. Factors that may be different include: level of impurities in the feed material, lot to lot variability in feedstock impurities, design of the column housing unit with respect to cleanability, and homogeneity of the column packing. In view of these challenges, there is a need for approaches that may be able to predict column underperformance at the manufacturing scale over the product lifecycle. In case such an underperformance is predicted, the operators can unpack and repack the chromatography column beforehand and thus avoid batch loss. Chemometrics offers one such solution. In this article, we present an application of chemometrics toward the analysis of a set of chromatography profiles with the intention of predicting the various events of column underperformance including the backpressure buildup and inefficient deoxyribonucleic acid clearance. Copyright © 2012 American Institute of Chemical Engineers (AIChE).

Quality of water in the fractured-bedrock aquifer of New Hampshire

USGS Publications Warehouse

Moore, Richard Bridge

2004-01-01

Over the past few decades, New Hampshire has experienced considerable population growth, which is forcing some communities to look for alternative public and private water supplies in the bedrock aquifer. Because the quality of water from the aquifer can vary, the U.S. Geological Survey statistically analyzed well data from 1,353 domestic and 360 public-supply bedrock wells to characterize the ground water. The domestic-well data were from homeowner-collected samples analyzed by the New Hampshire Department of Environmental Services (NHDES) Environmental Laboratory from 1984 to 1994. Bedrock water in New Hampshire often contains high concentrations of iron, manganese, arsenic, and radon gas. Water samples from 21 percent of the domestic bedrock wells contained arsenic above the U.S. Environmental Protection Agency (USEPA) 10 micrograms per liter (?g/L) drinking-water standard for public-water supplies, and 96 percent had radon concentrations greater than the USEPA-proposed 300 picocurie per liter (pCi/L) standard for public-water supplies. Some elevated fluoride concentrations (2 percent of samples) were above the 4 milligrams per liter (mg/L) USEPA drinking-water standard for public-water supplies. Water from the bedrock aquifer also typically is soft to moderately hard, and has a pH greater than 7.0. Variations in bedrock water quality were discernable when the data were compared to lithochemical groupings of the bedrock, indicating that the type of bedrock has an effect on the quality of water in the bedrock aquifer of New Hampshire. Ground-water samples from the metasedimentary lithochemical group have greater concentrations of total iron and total manganese than do the felsic and mafic igneous lithochemical groups. Ground-water samples from the felsic igneous group have higher concentrations of total fluoride than do those from the other lithochemical groups. For arsenic, the calcareous metasedimentary group was identified, using the public-supply database, as

Sedimentologic and diagenetic controls on aquifer properties, Lower Cretaceous Edwards Carbonate Aquifer, Texas: Implications for aquifer management

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hovorka, S.D.; Dutton, A.R.; Ruppel, S.C.

1994-09-01

The three-dimensional distribution of water in the Edwards aquifer was assessed using a core and log-based study. Porosity distribution reflects both depositional fabric and subsequent diagenesis. Vertical facies stacking patterns influence the depositional porosity as well as dolomitization and diagentic porosity modification. Subtidal facies deposited during sea level highstands are generally undolomitized and exhibit low porosity (5-10%); platform grainstones typically have high depositional porosity and significant solution enhancement (20-42% porosity). Dolomitized subtidal facies in tidal-flat-capped cycles have very high porosity (20-40%) because of selective dolomite dissolution in the freshwater aquifer. Porosity in gypsum beds is high in some areas becausemore » of dissolution and collapse, but low where gypsum was replaced by calcite cement. Low-energy subtidal and evaporitic units in the Maverick basin have porosity generally less than 15%. The overlying basinal packstones and grainstones have solution-enhanced porosities of 25 to 35%. Diagenesis associated with fluctuations in water chemistry near the saline-freshwater interface may explain one high-porosity trend. Other complex patterns of high and low porosity are attributed to structurally and hydrologically controlled porosity enhancement and cementation. Three-dimensional mapping of porosity trends provides data for improved aquifer management. Only about 3% of the maximum stored water lies above the water table at which natural spring flow is diminished. An average specific yield of 42% in the unconfined aquifer is determined from total porosity, changes in the water-table elevation, and changes in estimated recharge and discharge. Average storativity of 2.6 x 10{sup -4} in the confined Edwards is estimated using average porosity and barometric efficiency calculated from comparing water-level hydrographs and atmospheric pressure changes.« less

Estimating harvested rainwater at greenhouses in south Portugal aquifer Campina de Faro for potential infiltration in Managed Aquifer Recharge.

NASA Astrophysics Data System (ADS)

Costa, Luís; Monteiro, José Paulo; Leitão, Teresa; Lobo-Ferreira, João Paulo; Oliveira, Manuel; Martins de Carvalho, José; Martins de Carvalho, Tiago; Agostinho, Rui

2015-04-01

The Campina de Faro (CF) aquifer system, located on the south coast of Portugal, is an important source of groundwater, mostly used for agriculture purposes. In some areas, this multi-layered aquifer is contaminated with high concentration of nitrates, possibly arising from excessive usage of fertilizers, reaching to values as high as 300 mg/L. In order to tackle this problem, Managed Aquifer Recharge (MAR) techniques are being applied at demonstration scale to improve groundwater quality through aquifer recharge, in both infiltration basins at the river bed of ephemeral river Rio Seco and existing traditional large diameter wells located in this aquifer. In order to assess the infiltration capacity of the existing infrastructures, in particular infiltration basins and large diameter wells at CF aquifer, infiltration tests were performed, indicating a high infiltration capacity of the existing infrastructures. Concerning the sources of water for recharge, harvested rainwater at greenhouses was identified in CF aquifer area as one of the main potential sources for aquifer recharge, once there is a large surface area occupied by these infrastructures at the demo site. This potential source of water could, in some cases, be redirected to the large diameter wells or to the infiltration basins at the riverbed of Rio Seco. Estimates of rainwater harvested at greenhouses were calculated based on a 32 year average rainfall model and on the location of the greenhouses and their surface areas, the latter based on aerial photograph. Potential estimated annual rainwater intercepted by greenhouses at CF aquifer accounts an average of 1.63 hm3/year. Nonetheless it is unlikely that the totality of this amount can be harvested, collected and redirected to aquifer recharge infrastructures, for several reasons, such as the lack of appropriate greenhouse infrastructures, conduits or a close location between greenhouses and large diameter wells and infiltration basins. Anyway, this

Geohydrologic systems in Kansas, geohydrology of the upper aquifer unit in the western interior plains aquifer system

USGS Publications Warehouse

Kenny, J.F.; Wolf, R.J.; Hansen, Cristi V.

1993-01-01

The purpose of the investigation is to provide a description of the principal geohydrologic systems in Upper Cambrian through Lower Cretaceous rocks in Kansas. This investigation was made as part of the Central Midwest Regional Aquifer-System Analysis (CMRASA). The CMRASA is one of several major investigations by the U.S. Geological Survey of regional aquifer systems in the United States. These regional investigations are designed to increase knowledge of the flow regime and hydrologic properties of major aquifer systems and to provide quantitative information for the assessment, development, and management of water supplies. The CMRASA study area includes all or parts of 10 Central Midwestern States (Jorgensen and Signor, 1981), as shown of the envelope cover,This Hydrologic Investigations Atlas, which consists of a series of chapters, presents a description of the physical framework and geohydrology of principal aquifers and confining systems in Kansas. Chapter H presents the geohydrology of the upper aquifer unit in the Western Interior Plains aquifer system. The physical framework of the aquifer system in relation to other systems is described by maps and sections showing areal extent and the thickness of rocks that compose the unit. The physical framework of the upper aquifer unit is described in detail in chapter D of the atlas (Hansen and others, in press). The hydrology of the system in relation to that of other systems is described in this chapter by maps showing the altitude of fluid levels and the direction of water movement within the unit. The chemical composition of water in the system is described by maps that show the distribution of dissolved-solids concentrations and the differences in water types on the basis of principal chemical constituents. Chapter A of this atlas series (Wolf and others, 1990) describes the relation of principal geohydrologic systems in Kansas and presents a more detailed discussion of the methods and data used to prepare

Ground-Water Flow Model for the Spokane Valley-Rathdrum Prairie Aquifer, Spokane County, Washington, and Bonner and Kootenai Counties, Idaho

USGS Publications Warehouse

Hsieh, Paul A.; Barber, Michael E.; Contor, Bryce A.; Hossain, Md. Akram; Johnson, Gary S.; Jones, Joseph L.; Wylie, Allan H.

2007-01-01

This report presents a computer model of ground-water flow in the Spokane Valley-Rathdrum Prairie (SVRP) aquifer in Spokane County, Washington, and Bonner and Kootenai Counties, Idaho. The aquifer is the sole source of drinking water for more than 500,000 residents in the area. In response to the concerns about the impacts of increased ground-water withdrawals resulting from recent and projected urban growth, a comprehensive study was initiated by the Idaho Department of Water Resources, the Washington Department of Ecology, and the U.S. Geological Survey to improve the understanding of ground-water flow in the aquifer and of the interaction between ground water and surface water. The ground-water flow model presented in this report is one component of this comprehensive study. The primary purpose of the model is to serve as a tool for analyzing aquifer inflows and outflows, simulating the effects of future changes in ground-water withdrawals from the aquifer, and evaluating aquifer management strategies. The scale of the model and the level of detail are intended for analysis of aquifer-wide water-supply issues. The SVRP aquifer model was developed by the Modeling Team formed within the comprehensive study. The Modeling Team consisted of staff and personnel working under contract with the Idaho Department of Water Resources, personnel working under contract with the Washington Department of Ecology, and staff of the U.S. Geological Survey. To arrive at a final model that has the endorsement of all team members, decisions on modeling approach, methodology, assumptions, and interpretations were reached by consensus. The ground-water flow model MODFLOW-2000 was used to simulate ground-water flow in the SVPR aquifer. The finite-difference model grid consists of 172 rows, 256 columns, and 3 layers. Ground-water flow was simulated from September 1990 through September 2005 using 181 stress periods of 1 month each. The areal extent of the model encompasses an area of

Quantifying Linkages between Biogeochemical Processes in a Contaminated Aquifer-Wetland System Using Multivariate Statistics and HP1

NASA Astrophysics Data System (ADS)

Arora, B.; Mohanty, B. P.; McGuire, J. T.

2009-12-01

Fate and transport of contaminants in saturated and unsaturated zones in the subsurface is controlled by complex biogeochemical processes such as precipitation, sorption-desorption, ion-exchange, redox, etc. In dynamic systems such as wetlands and anaerobic aquifers, these processes are coupled and can interact non-linearly with each other. Variability in measured hydrological, geochemical and microbiological parameters thus corresponds to multiple processes simultaneously. To infer the contributing processes, it is important to eliminate correlations and to identify inter-linkages between factors. The objective of this study is to develop quantitative relationships between hydrological (initial and boundary conditions, hydraulic conductivity ratio, and soil layering), geochemical (mineralogy, surface area, redox potential, and organic matter) and microbiological factors (MPN) that alter the biogeochemical processes at the column scale. Data used in this study were collected from controlled flow experiments in: i) two homogeneous soil columns, ii) a layered soil column, iii) a soil column with embedded clay lenses, and iv) a soil column with embedded clay lenses and one central macropore. The soil columns represent increasing level of soil structural heterogeneity to better mimic the Norman Landfill research site. The Norman Landfill is a closed municipal facility with prevalent organic contamination. The sources of variation in the dataset were explored using multivariate statistical techniques and dominant biogeochemical processes were obtained using principal component analysis (PCA). Furthermore, artificial neural networks (ANN) coupled with HP1 was used to develop mathematical rules identifying different combinations of factors that trigger, sustain, accelerate/decelerate, or discontinue the biogeochemical processes. Experimental observations show that infiltrating water triggers biogeochemical processes in all soil columns. Similarly, slow release of water

Hydrogeology and Aquifer Storage and Recovery Performance in the Upper Floridan Aquifer, Southern Florida

USGS Publications Warehouse

Reese, Ronald S.; Alvarez-Zarikian, Carlos A.

2007-01-01

Well construction, hydraulic well test, ambient water-quality, and cycle test data were inventoried and compiled for 30 aquifer storage and recovery facilities constructed in the Floridan aquifer system in southern Florida. Most of the facilities are operated by local municipalities or counties in coastal areas, but five sites are currently being evaluated as part of the Comprehensive Everglades Restoration Plan. The relative performance of all sites with adequate cycle test data was determined, and compared with four hydrogeologic and design factors that may affect recovery efficiency. Testing or operational cycles include recharge, storage, and recovery periods that each last days or months. Cycle test data calculations were made including the potable water (chloride concentration of less than 250 milligrams per liter) recovery efficiency per cycle, total recovery efficiency per cycle, and cumulative potable water recovery efficiencies for all of the cycles at each site. The potable water recovery efficiency is the percentage of the total amount of potable water recharged for each cycle that is recovered; potable water recovery efficiency calculations (per cycle and cumulative) were the primary measures used to evaluate site performance in this study. Total recovery efficiency, which is the percent recovery at the end of each cycle, however, can be substantially higher and is the performance measure normally used in the operation of water-treatment plants. The Upper Floridan aquifer of the Floridan aquifer system currently is being used, or planned for use, at 29 of the aquifer storage and recovery sites. The Upper Floridan aquifer is continuous throughout southern Florida, and its overlying confinement is generally good; however, the aquifer contains brackish to saline ground water that can greatly affect freshwater storage and recovery due to dispersive mixing within the aquifer. The hydrogeology of the Upper Floridan varies in southern Florida; confinement

Factors Affecting Public-Supply Well Vulnerability in Two Karst Aquifers

PubMed Central

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

2014-01-01

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 (<10 years) groundwater. Vulnerability was demonstrated by the frequent detection of similar constituents of concern in both 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. PMID:24841501

Factors affecting public-supply well vulnerability in two karst aquifers

USGS Publications Warehouse

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

2014-01-01

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 (<10 years) groundwater. Vulnerability was demonstrated by the frequent detection of similar constituents of concern in both 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.

An Update of Hydrologic Conditions and Distribution of Selected Constituents in Water, Snake River Plain Aquifer and Perched-Water Zones, Idaho National Laboratory, Idaho, Emphasis 2002-05

USGS Publications Warehouse

Davis, Linda C.

2008-01-01

Radiochemical and chemical wastewater discharged since 1952 to infiltration ponds, evaporation ponds, and disposal wells at the Idaho National Laboratory (INL) has affected water quality in the Snake River Plain aquifer and perched-water zones underlying the INL. The U.S. Geological Survey, in cooperation with the U.S. Department of Energy, maintains ground-water monitoring networks at the INL to determine hydrologic trends, and to delineate the movement of radiochemical and chemical wastes in the aquifer and in perched-water zones. This report presents an analysis of water-level and water-quality data collected from aquifer and perched-water wells in the USGS ground-water monitoring networks during 2002-05. Water in the Snake River Plain aquifer primarily moves through fractures and interflow zones in basalt, generally flows southwestward, and eventually discharges at springs along the Snake River. The aquifer is recharged primarily from infiltration of irrigation water, infiltration of streamflow, ground-water inflow from adjoining mountain drainage basins, and infiltration of precipitation. From March-May 2001 to March-May 2005, water levels in wells declined throughout the INL area. The declines ranged from about 3 to 8 feet in the southwestern part of the INL, about 10 to 15 feet in the west central part of the INL, and about 6 to 11 feet in the northern part of the INL. Water levels in perched water wells declined also, with the water level dropping below the bottom of the pump in many wells during 2002-05. For radionuclides, concentrations that equal 3s, wheres s is the sample standard deviation, represent a measurement at the minimum detectable concentration, or 'reporting level'. Detectable concentrations of radiochemical constituents in water samples from wells in the Snake River Plain aquifer at the INL generally decreased or remained constant during 2002-05. Decreases in concentrations were attributed to decreased rates of radioactive-waste disposal

Virus movement in soil columns flooded with secondary sewage effluent.

PubMed Central

Lance, J C; Gerba, C P; Melnick, J L

1976-01-01

Secondary sewage effluent containing about 3 X 10(4) plaque-forming units of polio virus type 1 (LSc) per ml was passed through columns 250 cm in length packed with calcareous sand from an area in the Salt River bed used for ground-water recharge of secondary sewage effluent. Viruses were not detected in 1-ml samples extracted from the columns below the 160-cm level. However, viruses were detected in 5 of 43 100-ml samples of the column drainage water. Most of the viruses were adsorbed in the top 5 cm of soil. Virus removal was not affected by the infiltration rate, which varied between 15 and 55 cm/day. Flooding a column continuosly for 27 days with the sewage water virus mixture did not saturate the top few centimeters of soil with viruses and did not seem to affect virus movement. Flooding with deionized water caused virus desorption from the soil and increased their movement through the columns. Adding CaCl2 to the deionized water prevented most of the virus desorption. Adding a pulse of deionized water followed by sewage water started a virus front moving through the columns, but the viruses were readsorbed and none was detected in outflow samples. Drying the soil for 1 day between applying the virus and flooding with deionized water greatly reduced desorption, and drying for 5 days prevented desorption. Large reductions (99.99% or more) of virus would be expected after passage of secondary sewage effluent through 250 cm of the calcareous sand similar to that used in our laboratory columns unless heavy rains fell within 1 day after the application of sewage stopped. Such virus movement could be minimized by the proper management of flooding and drying cycles. PMID:185960

Spokane Valley-Rathdrum Prairie aquifer, Washington and Idaho

USGS Publications Warehouse

Drost, B.W.; Seitz, Harold R.

1977-01-01

The Spokane Valley-Rathdrum Prairie aquifer is composed of unconsolidated Quaternary glaciofluvial deposits underlying an area of about 350 square miles. Transmissivities in the aquifer range from about 0.13 million to 11 million feet squared per day and ground-water velocities exceed 60 feet per day in some areas. The water-table gradient ranges from about 2 feet per mile to more than 60 feet per mile, and during a year the water table fluctuates on the order of 5 to 10 feet. For most of the aquifer the water table is between 40 and 400 feet below land surface. The aquifer is recharged and discharged at an average rate of about 1,320 cubic feet per second. Water is presently (1976) pumped from the aquifer at an average rate of about 239 cubic feet per second for domestic, industrial, and agricultural uses. Most of this is discharged to the Spokane River, lost to evapotranspiration, or applied to the land surface with little or no change in quality. However, about 34 cubic feet per second becomes waste water generated by domestic and industrial activities and is returned to the aquifer by percolation from cesspools and drain fields. The quality of water in the aquifer is generally good. Less than one-half of 1 percent of the 3,300 analyses available exceeded the maximum contaminant levels specified in the National Interim Primary (or Proposed Secondary) Drinking Water Regulations (U.S. Environmental Protection Agency, 1975) for constituents which may be hazardous to health. Of the 6,300 analyses for constituents considered detrimental to the esthetic quality of water, about 1.4 percent have yielded values which exceeded the recommended levels. Alternative water sources for the area supplied by the aquifer are the Spokane and Little Spokane Rivers, lakes adjacent to the aquifer, and other aquifers. All of these potential sources are less desirable than the Spokane Valley-Rathdrum Prairie aquifer because of insufficient supplies, poor water quality, and (or

Geohydrology of the High Plains Aquifer, western Kansas

USGS Publications Warehouse

Stullken, L.E.; Watts, Kenneth R.; Lindgren, R.J.

1985-01-01

The High Plains aquifer underlies 174,050 sq mi of eight states (Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming) and contains approximately 3.3 billion acre-ft of water in storage. Saturated thicknesses within the aquifer are as great as 600 ft near the southern border of southwest Kansas. The aquifer is replenished primarily by infiltration from precipitation. Average precipitation at the Garden City Experiment Station is 18.93 in/yr. Groundwater flow is generally from west to east under unconfined conditions. Hydraulic connection with subcropping consolidated aquifers allows ground water to flow vertically in minor quantities. The aquifer is depleted primarily by irrigation. Hydraulic conductivity estimates from 1,612 lithologic logs had an average value of 75 ft/day, with a standard deviation of 35 ft/day. Specific yields estimated from the same lithologic logs had a mean of 0.17 and a standard deviation of 0.047. Water from the High Plains aquifer in Kansas generally is suitable for human and animal consumption and irrigation of crops. Typically, it is a calcium bicarbonate type water, with concentrations of total dissolved solids ranging from 250 to 500 mg/L. The quality of water in the aquifer deteriorates toward the east due to mixing with recharge water containing dissolved minerals leached from the overlying soil and unsaturated zones and mineralized water from adjacent bedrock units. The simulated water budget for the steady state model of predevelopment (pre-1950) conditions in the High Plains aquifer in northwest Kansas showed that annual recharge to the aquifer from infiltration of precipitation was 87,000 acre-ft/yr and from boundary inflow, 21,000 acre-ft/yr. Annual discharge from the aquifer was 108,000 acre-ft/yr, including 81,000 acre-ft/yr from leakage to streams, 23,000 acre-ft from outflow at the boundaries of the aquifer, and 4,000 acre-ft from municipal and industrial pumpage. (Lantz-PTT)

Bedrock aquifers of eastern San Juan County, Utah

USGS Publications Warehouse

Avery, Charles

1986-01-01

This study is one of a series of studies appraising the waterbearing properties of the Navajo Sandstone and associated formations in southern Utah.  The stu<¥ area is al:x>dy area is about 4,600 square miles, extending from the Utah-Arizona State line northward to the San Juan-Grand County line and westward from the Utah-Colorado State line to the longitude of about 109°50'.Some of the water-yielding formations are grouped into aquifer systems. The C aquifer is comprised of the DeChelly Sandstone Member of the Cutler Formation.  The P aquifer is comprised of the Cedar Mesa Member of the Cutler Formation and the undifferentiated Cutler Formation. The N aquifer is comprised of the sedimentary section that includes the Wingate Sandstone, Kayenta Formation, Navajo Sandstone, Carmel Formation, and Entrada sandstone.  The M aquifer is comprised of the Bluff Sandstone Member and other sandstone units of the Morrison Formation.  The D aquifer is comprised of the Burro Canyon Formation and Dakota Sandstone.  Discharge from the ground-water reservoir to the San Juan River between gaging stations at Four Corners and Mexican Hat is about 66 cubic feet per second.The N aquifer is the main aquifer in the study area. Recharge by infiltration of precipitation is estimated to be 25,000 acre-feet per year.  A major ground-water divide exists under the broad area east of Monticello.  The thickness of the N aquifer, where the sedimentary section is fully preserved and saturated, generally is 750 to 1,250 feet.   Hydraulic conductivity values obtained from aquifer tests range from 0.02 to 0.34 foot per day.  The total volume of water in transient storage is about 11 million acre-feet. Well discharge somewhat exceeded 2,340 acre-feet during 1981.  Discharge to the San Juan River from the N aquifer is estimated to be 6.9 cubic feet per second. Water quality ranges from a calcium bicarbonate to sodium chloride type water

Genomic and Physiological Characterization of the Chromate-Reducing, Aquifer-Derived Firmicute Pelosinus sp. Strain HCF1

NASA Astrophysics Data System (ADS)

Beller, H. R.; Han, R.; Karaoz, U.; Lim, H.; Brodie, E. L.

2012-12-01

Pelosinus species are fermentative firmicutes that were recently reported to be prominent members of microbial communities at contaminated subsurface sites in multiple locations. Here we report metabolic characteristics and their putative genetic basis in Pelosinus sp. strain HCF1, an isolate that predominated anaerobic, Cr(VI)-reducing columns constructed with Hanford 100H aquifer sediment (constituting 80% of the total bacterial population in the columns). Strain HCF1 ferments lactate to propionate and acetate (a complete fermentation pathway was identified in the genome) and its genome encodes both [NiFe]- and [FeFe]-hydrogenases for H2 cycling. This bacterium has unexpected capabilities and gene content associated with reduction of nitrogen oxides. In this strain, either H2 or lactate can act as a sole electron donor for nitrate, Cr(VI), and Fe(III) reduction. Transcriptional studies demonstrated differential expression of nitrate reductases and hydrogenases. Overall, the unexpected metabolic capabilities and gene content reported here broaden our perspective on what biogeochemical and ecological roles this species might play as a prominent member of microbial communities in subsurface environments.

High-density PhyloChip profiling of stimulated aquifer microbial communities reveals a complex response to acetate amendment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Handley, Kim M.; Wrighton, Kelly C.; Piceno, Yvette M.

2012-04-13

There is increasing interest in harnessing the functional capacities of indigenous microbial communities to transform and remediate a wide range of environmental contaminants. Information about which community members respond to stimulation can guide the interpretation and development of remediation approaches. To comprehensively determine community membership and abundance patterns among a suite of samples associated with uranium bioremediation experiments we employed a high-density microarray (PhyloChip). Samples were unstimulated, naturally reducing, or collected during Fe(III) (early) and sulfate reduction (late biostimulation) from an acetate re-amended/amended aquifer in Rifle, Colorado, and from laboratory experiments using field-collected materials. Deep community sampling with PhyloChip identifiedmore » hundreds-to-thousands of operational taxonomic units (OTUs) present during amendment, and revealed close similarity among highly enriched taxa from drill-core and groundwater well-deployed column sediment. Overall, phylogenetic data suggested stimulated community membership was most affected by a carryover effect between annual stimulation events. Nevertheless, OTUs within the Fe(III)- and sulfate-reducing lineages, Desulfuromonadales and Desulfobacterales, were repeatedly stimulated. Less consistent, co-enriched taxa represented additional lineages associated with Fe(III) and sulfate reduction (for example, Desulfovibrionales; Syntrophobacterales; Peptococcaceae) and autotrophic sulfur oxidation (Sulfurovum; Campylobacterales). These data imply complex membership among highly stimulated taxa, and by inference biogeochemical responses to acetate, a non-fermentable substrate.« less

Geomorphic Controls on Aquifer Geometry in Northwestern India

NASA Astrophysics Data System (ADS)

van Dijk, W. M.; Densmore, A. L.; Sinha, R.; Gupta, S.; Mason, P. J.; Singh, A.; Joshi, S. K.; Nayak, N.; Kumar, M.; Shekhar, S.

2014-12-01

The Indo-Gangetic foreland basin suffers from one of the highest rates of groundwater extraction in the world, especially in the Indian states of Punjab, Haryana and Rajasthan. To understand the effects of this extraction on ground water levels, we must first understand the geometry and sedimentary architecture of the aquifer system, which in turn depend upon its geomorphic setting. We use satellite images and digital elevation models to map the geomorphology of the Sutlej and Yamuna river systems, while aquifer geometry is assessed using ~250 wells that extend to ~300 m depth in Punjab and Haryana. The Sutlej and Yamuna rivers have deposited large sedimentary fans at their outlets. Elongate downslope ridges on the fan surfaces form distributary networks that radiate from the Sutlej and Yamuna fan apices, and we interpret these ridges as paleochannel deposits associated with discrete fan lobes. Paleochannels picked out by soil moisture variations illustrate a complex late Quaternary history of channel avulsion and incision, probably associated with variations in monsoon intensity. Aquifer bodies on the Sutlej and Yamuna fans have a median thickness of 7 and 6 m, respectively, and follow a heavy-tailed distribution, probably because of stacked sand bodies. The percentage of aquifer material in individual lithologs decreases downstream, although the exponent on the thickness distribution remains the same, indicating that aquifer bodies decrease in number down fan but do not thin appreciably. Critically, the interfan area between the Sutlej and Yamuna fans has thinner aquifers and a lower proportion of aquifer material, despite its proximal location. Our data show that the Sutlej and Yamuna fan systems form the major aquifer systems in this area, and that their geomorphic setting therefore provides a first-order control on aquifer distribution and geometry. The large spatial heterogeneity of the system must be considered in any future aquifer management scheme.

Glass-silicon column

DOEpatents

Yu, Conrad M.

2003-12-30

A glass-silicon column that can operate in temperature variations between room temperature and about 450.degree. C. The glass-silicon column includes large area glass, such as a thin Corning 7740 boron-silicate glass bonded to a silicon wafer, with an electrode embedded in or mounted on glass of the column, and with a self alignment silicon post/glass hole structure. The glass/silicon components are bonded, for example be anodic bonding. In one embodiment, the column includes two outer layers of silicon each bonded to an inner layer of glass, with an electrode imbedded between the layers of glass, and with at least one self alignment hole and post arrangement. The electrode functions as a column heater, and one glass/silicon component is provided with a number of flow channels adjacent the bonded surfaces.

SIMULATION OF SURFACTANT-ENHANCED AQUIFER REMEDIATION

EPA Science Inventory

Surfactant-enhanced aquifer remediation (SEAR) is currently under active investigation as one of the most promising alternatives to conventional pump-and-treat remediation for aquifers contaminated by dense nonaqueous phase organic liquids. An existing three-dimensional finite-di...

Retardation of arsenic transport through a Pleistocene aquifer

PubMed Central

van Geen, Alexander; Bostick, Benjamín C.; Trang, Pham Thi Kim; Lan, Vi Mai; Mai, Nguyen-Ngoc; Manh, Phu Dao; Viet, Pham Hung; Radloff, Kathleen; Aziz, Zahid; Mey, Jacob L.; Stahl, Mason O.; Harvey, Charles F.; Oates, Peter; Weinman, Beth; Stengel, Caroline; Frei, Felix; Kipfer, Rolf; Berg, Michael

2013-01-01

Groundwater drawn daily from shallow alluvial sands by millions of wells over large areas of South and Southeast Asia exposes an estimated population of over 100 million to toxic levels of arsenic (1). Holocene aquifers are the source of widespread arsenic poisoning across the region (2, 3). In contrast, Pleistocene sands deposited in this region more than ~12,000 years ago mostly do not host groundwater with high levels of arsenic. Pleistocene aquifers are increasingly used as a safe source of drinking water (4) and it is therefore important to understand under what conditions low levels of arsenic can be maintained. Here we reconstruct the initial phase of contamination of a Pleistocene aquifer near Hanoi, Vietnam. We demonstrate that changes in groundwater flow conditions and the redox state of the aquifer sands induced by groundwater pumping caused the lateral intrusion of arsenic contamination over 120 m from Holocene aquifer into a previously uncontaminated Pleistocene aquifer. We also find that arsenic adsorbs onto the aquifer sands and that there is a 16–20 fold retardation in the extent of the contamination relative to the reconstructed lateral movement of groundwater over the same period. Our findings suggest that arsenic contamination of Pleistocene aquifers in South and Southeast Asia as a consequence of increasing levels of groundwater pumping have been delayed by the retardation of arsenic transport. PMID:24025840

Geochemical and isotopic composition of ground water with emphasis on sources of sulfate in the upper Floridan Aquifer and intermediate aquifer system in southwest Florida

USGS Publications Warehouse

Sacks, Laura A.; Tihansky, Ann B.

1996-01-01

In southwest Florida, sulfate concentrations in water from the Upper Floridan aquifer and overlying intermediate aquifer system are commonly above 250 milligrams per liter (the drinking water standard), particularly in coastal areas. Possible sources of sulfate include dissolution of gypsum from the deeper part of the Upper Floridan aquifer or the middle confining unit, saltwater in the aquifer, and saline waters from the middle confining unit and Lower Floridan aquifer. The sources of sulfate and geochemical processes controlling ground-water composition were evaluated for the Peace and Myakka River Basins and adjacent coastal areas of southwest Florida. Samples were collected from 63 wells and a saline spring, including wells finished at different depth intervals of the Upper Floridan aquifer and intermediate aquifer system at about 25 locations. Sampling focused along three ground-water flow paths (selected based on a predevelopment potentiometric-surface map). Ground water was analyzed for major ions, selected trace constituents, dissolved organic carbon, and stable isotopes (delta deuterium, oxygen-18, carbon-13 of inorganic carbon, and sulfur-34 of sulfate and sulfide); the ratio of strontium-87 to strontium-86 was analyzed for waters along one of the flow paths. Chemical and isotopic data indicate that dedolomitization reactions (gypsum and dolomite dissolution and calcite precipitation) control the chemical composition of water in the Upper Floridan aquifer in inland areas. This is confirmed by mass-balance modeling between wells in the shallowest interval in the aquifer along the flow paths. However, gypsum occurs deeper in the aquifer than these wells. Upwelling of sulfate-rich water that previously dissolved gypsum in deeper parts of the aquifer is a more likely source of sulfate than gypsum dissolution in shallow parts of the aquifer. This deep ground water moves to shallower zones in the aquifer discharge area. Saltwater from the Upper Floridan aquifer

Systems for column-based separations, methods of forming packed columns, and methods of purifying sample components

DOEpatents

Egorov, Oleg B.; O'Hara, Matthew J.; Grate, Jay W.; Chandler, Darrell P.; Brockman, Fred J.; Bruckner-Lea, Cynthia J.

2000-01-01

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber. In another aspect, the invention includes a system for column-based separations, comprising: a) a fluid passageway, the fluid passageway comprising a column chamber and a flow path in fluid communication with the column chamber, the flow path being obstructed by a retaining material permeable to a carrier fluid and impermeable to a column matrix material suspended in the carrier fluid, the flow path extending through the column chamber and through the retaining material, the flow path being configured to form a packed column within the column chamber when a suspension of the fluid and the column matrix material is flowed along the flow path; and b) the fluid passageway extending through a valve intermediate the column chamber and the retaining material.

Systems For Column-Based Separations, Methods Of Forming Packed Columns, And Methods Of Purifying Sample Components

DOEpatents

Egorov, Oleg B.; O'Hara, Matthew J.; Grate, Jay W.; Chandler, Darrell P.; Brockman, Fred J.; Bruckner-Lea, Cynthia J.

2006-02-21

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber. In another aspect, the invention includes a system for column-based separations, comprising: a) a fluid passageway, the fluid passageway comprising a column chamber and a flow path in fluid communication with the column chamber, the flow path being obstructed by a retaining material permeable to a carrier fluid and impermeable to a column matrix material suspended in the carrier fluid, the flow path extending through the column chamber and through the retaining material, the flow path being configured to form a packed column within the column chamber when a suspension of the fluid and the column matrix material is flowed along the flow path; and b) the fluid passageway extending through a valve intermediate the column chamber and the retaining material.

Systems For Column-Based Separations, Methods Of Forming Packed Columns, And Methods Of Purifying Sample Components.

DOEpatents

Egorov, Oleg B.; O'Hara, Matthew J.; Grate, Jay W.; Chandler, Darrell P.; Brockman, Fred J.; Bruckner-Lea, Cynthia J.

2004-08-24

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber. In another aspect, the invention includes a system for column-based separations, comprising: a) a fluid passageway, the fluid passageway comprising a column chamber and a flow path in fluid communication with the column chamber, the flow path being obstructed by a retaining material permeable to a carrier fluid and impermeable to a column matrix material suspended in the carrier fluid, the flow path extending through the column chamber and through the retaining material, the flow path being configured to form a packed column within the column chamber when a suspension of the fluid and the column matrix material is flowed along the flow path; and b) the fluid passageway extending through a valve intermediate the column chamber and the retaining material.

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

PubMed

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 (<10 years) groundwater. Vulnerability was demonstrated by the frequent detection of similar constituents of concern in both 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.

Modeling water infiltration and pesticides transport in unsaturated zone of a sedimentary aquifer

NASA Astrophysics Data System (ADS)

Sidoli, Pauline; Angulo-Jaramillo, Rafael; Baran, Nicole; Lassabatère, Laurent

2015-04-01

Groundwater quality monitoring has become an important environmental, economic and community issue since increasing needs drinking water at the same time with high anthropic pressure on aquifers. Leaching of various contaminants as pesticide into the groundwater is closely bound to water infiltration in the unsaturated zone which whom solute transport can occur. Knowledge's about mechanisms involved in the transfer of pesticides in the deep unsaturated zone are lacking today. This study aims to evaluate and to model leaching of pesticides and metabolites in the unsaturated zone, very heterogeneous, of a fluvio-glacial aquifer, in the South-East of France, where contamination of groundwater resources by pesticides is frequently observed as a consequence of intensive agricultural activities. Water flow and pesticide transport were evaluated from column tests under unsaturated conditions and from adsorption batch experiments onto the predominant lithofacies collected, composed of a mixture of sand and gravel. A maize herbicide, S-metolachlor, applied on the study site and worldwide and its two major degradation products (metolachlor ethanesulfonic acid and metolachlor oxanilic acid) were studied here. A conservative tracer, bromide ion, was used to determine water dispersive parameters of porous media. Elution curves were obtained from pesticide concentrations analyzed by an ultra-performance liquid chromatography system interfaced to a triple quadrupole mass spectrometer and from bromide concentrations measured by ionic chromatography system. Experimental data were implemented into Hydrus to model flow and solute transfer through a 1D profile in the vadose zone. Nonequilibrium solute transport model based on dual-porosity model with mobile and immobile water is fitting correctly elution curves. Water dispersive parameters show flow pattern realized in the mobile phase. Exchanges between mobile and immobile water are very limited. Because of low adsorptions onto

ANALYTICAL ELEMENT MODELING OF COASTAL AQUIFERS

EPA Science Inventory

Four topics were studied concerning the modeling of groundwater flow in coastal aquifers with analytic elements: (1) practical experience was obtained by constructing a groundwater model of the shallow aquifers below the Delmarva Peninsula USA using the commercial program MVAEM; ...

Influence of colloids on the attenuation and transport of phosphorus in alluvial gravel aquifer and vadose zone media.

PubMed

Pang, Liping; Lafogler, Mark; Knorr, Bastian; McGill, Erin; Saunders, Darren; Baumann, Thomas; Abraham, Phillip; Close, Murray

2016-04-15

Phosphorous (P) leaching (e.g., from effluents, fertilizers) and transport in highly permeable subsurface media can be an important pathway that contributes to eutrophication of receiving surface waters as groundwater recharges the base-flow of surface waters. Here we investigated attenuation and transport of orthophosphate-P in gravel aquifer and vadose zone media in the presence and absence of model colloids (Escherichia coli, kaolinite, goethite). Experiments were conducted using repacked aquifer media in a large column (2m long, 0.19m in diameter) and intact cores (0.4m long, 0.24m in diameter) of vadose zone media under typical field flow rates. In the absence of the model colloids, P was readily traveled through the aquifer media with little attenuation (up to 100% recovery) and retardation, and P adsorption was highly reversible. Conversely, addition of the model colloids generally resulted in reduced P concentration and mass recovery (down to 28% recovery), and increased retardation and adsorption irreversibility in both aquifer and vadose zone media. The degree of colloid-assisted P attenuation was most significant in the presence of fine material and Fe-containing colloids at low flow rate but was least significant in the presence of coarse gravels and E. coli at high flow rate. Based on the experimental results, setback distances of 49-53m were estimated to allow a reduction of P concentrations in groundwater to acceptable levels in the receiving water. These estimates were consistent with field observations in the same aquifer media. Colloid-assisted P attenuation can be utilized to develop mitigation strategies to better manage effluent applications in gravelly soils. To efficiently retain P within soil matrix and reduce P leaching to groundwater, it is recommended to select soils that are rich in iron oxides, to periodically disturb soil preferential flow paths by tillage, and to apply a low irrigation rate. Copyright © 2016 Elsevier B.V. All rights

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

NASA Astrophysics Data System (ADS)

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.

Geochemical heterogeneity of a gasoline-contaminated aquifer

USGS Publications Warehouse

Cozzarelli, Isabelle M.; Herman, Janet S.; Baedecker, Mary Jo; Fischer, Jeffrey M.

1999-01-01

The scale of biogeochemical reactions was studied in a physically and chemically heterogeneous surficial Coastal Plain aquifer contaminated by a gasoline spill. The physical heterogeneity of the aquifer is manifested in two hydrologic units, a shallow local aquifer of perched water and a regional sandy aquifer. Over the studied vertical interval of 21.3 ft (6.5 m), concentrations of reactive species varied by orders of magnitude, and the impact of biodegradation was expressed to widely varying degrees. A thin (3 ft thick) section of the perched-water zone was the most contaminated; total aromatic hydrocarbons were as high as 19.4 mg/l. Hydrocarbons were degraded by microbially mediated reactions that varied over short vertical distances and time. Anaerobic processes dominated within the low-permeability clay unit, whereas in the more permeable sandy layers nitrate reduction and aerobic degradation occurred. Hydrocarbons were more persistent over time in the low-permeability layer due to the limited availability of electron acceptors for degradation. The microbial degradation of hydrocarbons was linked to sulfate and iron reduction in the clay unit and led to alterations in the aquifer solids; electron microscopy revealed the presence of FeS minerals encrusting primary aquifer grains. High concentrations of Fe2+ in groundwater, up to 34.5 mg/l, persist in kinetic disequilibrium in the presence of elevated H2S levels of 1.0 mg/l. Assessment of aquifer heterogeneities and groundwater contamination was possible due to sample discrimination at a scale of approximately 2 ft (∼0.6 m), a much finer resolution than is attempted in many remedial investigations of polluted aquifers. The information obtained in this type of study is essential to the development of models capable of estimating the fate of hydrocarbons at a site scale.

Hydrogeology of the surficial aquifer system, Dade County, Florida

USGS Publications Warehouse

Fish, J.E.; Stewart, M.T.

1991-01-01

An investigation of the surficial aquifer system in Dade County, begun in 1983, is part of a regional study of the aquifer system in southeastern Florida. Test drilling for lithologic samples, flow measurements during drilling, aquifer testing, and analyses of earlier data permitted delineation of the hydraulic conductivity distribution (on hydrogeologic sections), the aquifers in the system, the generalized transmissivity distribution, and interpretation of the ground-water flow system. The surficial aquifer system, in which an unconfined ground-water flow system exists, is composed of the sediments from land surface downward to the top of a regionally extensive zone of sediments of low permeability called the intermediate confining unit. The aquifer system units, which vary in composition from clay-size sediments to cavernous limestone, are hydro stratigraphically divided into the Biscayne aquifer at the top; an intervening semiconfining unit that consists principally of clayey sand; a predominantly gray limestone aquifer in the Tamiami Formation in western and west-central Dade County; and sand or clayey sand near the base of the surficial aquifer system. The base of the surficial aquifer system ranges from a depth of about 175 to 210 feet below land surface in westernmost Dade County to greater than 270 feet in northeastern Dade County. Test drilling and aquifer-test data indicate a complex hydraulic conductivity distribution. Hydraulic conductivities of the very highly permeable zone of the Biscayne aquifer commonly exceed 10,000 feet per day; in the gray limestone aquifer, they range from 210 to 780 feet per day. Transmissivities of the surficial aquifer system vary locally but have a recognizable areal trend. Estimated values generally are about 300,000 feet squared per day or greater in nearly all of central and eastern Dade County. Transmissivity is lower to the west, decreasing to less than 75,000 feet squared per day in western Dade County. High

Family of columns isospectral to gravity-loaded columns with tip force: A discrete approach

NASA Astrophysics Data System (ADS)

Ramachandran, Nirmal; Ganguli, Ranjan

2018-06-01

A discrete model is introduced to analyze transverse vibration of straight, clamped-free (CF) columns of variable cross-sectional geometry under the influence of gravity and a constant axial force at the tip. The discrete model is used to determine critical combinations of loading parameters - a gravity parameter and a tip force parameter - that cause onset of dynamic instability in the CF column. A methodology, based on matrix-factorization, is described to transform the discrete model into a family of models corresponding to weightless and unloaded clamped-free (WUCF) columns, each with a transverse vibration spectrum isospectral to the original model. Characteristics of models in this isospectral family are dependent on three transformation parameters. A procedure is discussed to convert the isospectral discrete model description into geometric description of realistic columns i.e. from the discrete model, we construct isospectral WUCF columns with rectangular cross-sections varying in width and depth. As part of numerical studies to demonstrate efficacy of techniques presented, frequency parameters of a uniform column and three types of tapered CF columns under different combinations of loading parameters are obtained from the discrete model. Critical combinations of these parameters for a typical tapered column are derived. These results match with published results. Example CF columns, under arbitrarily-chosen combinations of loading parameters are considered and for each combination, isospectral WUCF columns are constructed. Role of transformation parameters in determining characteristics of isospectral columns is discussed and optimum values are deduced. Natural frequencies of these WUCF columns computed using Finite Element Method (FEM) match well with those of the given gravity-loaded CF column with tip force, hence confirming isospectrality.

Aquifer test results, Green Swamp area, Florida

USGS Publications Warehouse

Tibbals, C.H.; Grubb, Hayes F.

1982-01-01

An aquifer test conducted in the Green Swamp area December 15-16 , 1975 was designed to stress the uppermost part of the Floridan aquifer so that the leakage characteristics of the overlying confining bed could be determined. A well tapping the upper part of the Floridan aquifer was pumped at a rate of about 1,040 gallons per minute for 35 hours; drawdown was measured in the Floridan aquifer and in two horizons in the confining bed. Analysis of the data indicates that the transmissivity of the uppper 160 feet of the Floridan is 13,000 square feet per day, the storage coefficient is about 0.0002.5, and the overlying confining bed leakance coefficient is about 0.02 to 0.025 per day. The vertical hydraulic diffusivity of the confining bed ranged from 610 square feet per day to 16,000 square feet per day. Results of the test indicate that, in the area of the test site, a Floridan aquifer well field would induce additional recharge to the Floridan. As a result of that increased recharge , water levels in the surficial aquifer would tend to stand lower, runoff from the area would tend to be less, and, perhaps, evapotranspiration would be less than normal.(USGS)

Integrating Predictive Modeling with Control System Design for Managed Aquifer Recharge and Recovery Applications

NASA Astrophysics Data System (ADS)

Drumheller, Z. W.; Regnery, J.; Lee, J. H.; Illangasekare, T. H.; Kitanidis, P. K.; Smits, K. M.

2014-12-01

Aquifers around the world show troubling signs of irreversible depletion and seawater intrusion as climate change, population growth, and urbanization led to reduced natural recharge rates and overuse. Scientists and engineers have begun to re-investigate the technology of managed aquifer recharge and recovery (MAR) as a means to increase the reliability of the diminishing and increasingly variable groundwater supply. MAR systems offer the possibility of naturally increasing groundwater storage while improving the quality of impaired water used for recharge. Unfortunately, MAR systems remain wrought with operational challenges related to the quality and quantity of recharged and recovered water stemming from a lack of data-driven, real-time control. Our project seeks to ease the operational challenges of MAR facilities through the implementation of active sensor networks, adaptively calibrated flow and transport models, and simulation-based meta-heuristic control optimization methods. The developed system works by continually collecting hydraulic and water quality data from a sensor network embedded within the aquifer. The data is fed into an inversion algorithm, which calibrates the parameters and initial conditions of a predictive flow and transport model. The calibrated model is passed to a meta-heuristic control optimization algorithm (e.g. genetic algorithm) to execute the simulations and determine the best course of action, i.e., the optimal pumping policy for current aquifer conditions. The optimal pumping policy is manually or autonomously applied. During operation, sensor data are used to assess the accuracy of the optimal prediction and augment the pumping strategy as needed. At laboratory-scale, a small (18"H x 46"L) and an intermediate (6'H x 16'L) two-dimensional synthetic aquifer were constructed and outfitted with sensor networks. Data collection and model inversion components were developed and sensor data were validated by analytical measurements.

Distillation Column Flooding Predictor

DOE Office of Scientific and Technical Information (OSTI.GOV)

George E. Dzyacky

2010-11-23

The Flooding Predictor™ is a patented advanced control technology proven in research at the Separations Research Program, University of Texas at Austin, to increase distillation column throughput by over 6%, while also increasing energy efficiency by 10%. The research was conducted under a U. S. Department of Energy Cooperative Agreement awarded to George Dzyacky of 2ndpoint, LLC. The Flooding Predictor™ works by detecting the incipient flood point and controlling the column closer to its actual hydraulic limit than historical practices have allowed. Further, the technology uses existing column instrumentation, meaning no additional refining infrastructure is required. Refiners often push distillationmore » columns to maximize throughput, improve separation, or simply to achieve day-to-day optimization. Attempting to achieve such operating objectives is a tricky undertaking that can result in flooding. Operators and advanced control strategies alike rely on the conventional use of delta-pressure instrumentation to approximate the column’s approach to flood. But column delta-pressure is more an inference of the column’s approach to flood than it is an actual measurement of it. As a consequence, delta pressure limits are established conservatively in order to operate in a regime where the column is never expected to flood. As a result, there is much “left on the table” when operating in such a regime, i.e. the capacity difference between controlling the column to an upper delta-pressure limit and controlling it to the actual hydraulic limit. The Flooding Predictor™, an innovative pattern recognition technology, controls columns at their actual hydraulic limit, which research shows leads to a throughput increase of over 6%. Controlling closer to the hydraulic limit also permits operation in a sweet spot of increased energy-efficiency. In this region of increased column loading, the Flooding Predictor is able to exploit the benefits of higher liquid

The High Plains Aquifer, USA: Groundwater development and sustainability

USGS Publications Warehouse

Dennehy, K.F.; Litke, D.W.; McMahon, P.B.

2002-01-01

The High Plains Aquifer, located in the United States, is one of the largest freshwater aquifers in the world and is threatened by continued decline in water levels and deteriorating water quality. Understanding the physical and cultural features of this area is essential to assessing the factors that affect this groundwater resource. About 27% of the irrigated land in the United States overlies this aquifer, which yields about 30% of the nation's groundwater used for irrigation of crops including wheat, corn, sorghum, cotton and alfalfa. In addition, the aquifer provides drinking water to 82% of the 2.3 million people who live within the aquifer boundary. The High Plains Aquifer has been significantly impacted by human activities. Groundwater withdrawals from the aquifer exceed recharge in many areas, resulting in substantial declines in groundwater level. Residents once believed that the aquifer was an unlimited resource of high-quality water, but they now face the prospect that much of the water may be gone in the near future. Also, agricultural chemicals are affecting the groundwater quality. Increasing concentrations of nitrate and salinity can first impair the use of the water for public supply and then affect its suitability for irrigation. A variety of technical and institutional measures are currently being planned and implemented across the aquifer area in an attempt to sustain this groundwater resource for future generations. However, because groundwater withdrawals remain high and water quality impairments are becoming more commonplace, the sustainability of the High Plains Aquifer is uncertain.

Estimating preferential flow in karstic aquifers using statistical mixed models.

PubMed

Anaya, Angel A; Padilla, Ingrid; Macchiavelli, Raul; Vesper, Dorothy J; Meeker, John D; Alshawabkeh, Akram N

2014-01-01

Karst aquifers are highly productive groundwater systems often associated with conduit flow. These systems can be highly vulnerable to contamination, resulting in a high potential for contaminant exposure to humans and ecosystems. This work develops statistical models to spatially characterize flow and transport patterns in karstified limestone and determines the effect of aquifer flow rates on these patterns. A laboratory-scale Geo-HydroBed model is used to simulate flow and transport processes in a karstic limestone unit. The model consists of stainless steel tanks containing a karstified limestone block collected from a karst aquifer formation in northern Puerto Rico. Experimental work involves making a series of flow and tracer injections, while monitoring hydraulic and tracer response spatially and temporally. Statistical mixed models (SMMs) are applied to hydraulic data to determine likely pathways of preferential flow in the limestone units. The models indicate a highly heterogeneous system with dominant, flow-dependent preferential flow regions. Results indicate that regions of preferential flow tend to expand at higher groundwater flow rates, suggesting a greater volume of the system being flushed by flowing water at higher rates. Spatial and temporal distribution of tracer concentrations indicates the presence of conduit-like and diffuse flow transport in the system, supporting the notion of both combined transport mechanisms in the limestone unit. The temporal response of tracer concentrations at different locations in the model coincide with, and confirms the preferential flow distribution generated with the SMMs used in the study. © 2013, National Ground Water Association.

Combined use of heat and saline tracer to estimate aquifer properties in a forced gradient test

NASA Astrophysics Data System (ADS)

Colombani, N.; Giambastiani, B. M. S.; Mastrocicco, M.

2015-06-01

Usually electrolytic tracers are employed for subsurface characterization, but the interpretation of tracer test data collected by low cost techniques, such as electrical conductivity logging, can be biased by cation exchange reactions. To characterize the aquifer transport properties a saline and heat forced gradient test was employed. The field site, located near Ferrara (Northern Italy), is a well characterized site, which covers an area of 200 m2 and is equipped with a grid of 13 monitoring wells. A two-well (injection and pumping) system was employed to perform the forced gradient test and a straddle packer was installed in the injection well to avoid in-well artificial mixing. The contemporary continuous monitor of hydraulic head, electrical conductivity and temperature within the wells permitted to obtain a robust dataset, which was then used to accurately simulate injection conditions, to calibrate a 3D transient flow and transport model and to obtain aquifer properties at small scale. The transient groundwater flow and solute-heat transport model was built using SEAWAT. The result significance was further investigated by comparing the results with already published column experiments and a natural gradient tracer test performed in the same field. The test procedure shown here can provide a fast and low cost technique to characterize coarse grain aquifer properties, although some limitations can be highlighted, such as the small value of the dispersion coefficient compared to values obtained by natural gradient tracer test, or the fast depletion of heat signal due to high thermal diffusivity.

Radial solute transport in highly heterogeneous aquifers: Modeling and experimental comparison

NASA Astrophysics Data System (ADS)

Di Dato, Mariaines; Fiori, Aldo; de Barros, Felipe P. J.; Bellin, Alberto

2017-07-01

We analyze solute transport in a radially converging 3-D flow field in a porous medium with spatially heterogeneous hydraulic conductivity (K). The aim of the paper is to analyze the impact of heterogeneity and the mode of injection on BreakThrough Curves (BTCs) detected at a well pumping a contaminated aquifer. The aquifer is conceptualized as an ensemble of blocks of uniform but contrasting K and the analysis makes use of the travel time approach. Despite the approximations introduced, the model reproduces a laboratory experiment without calibration of transport parameters. Our results also show excellent agreement with numerical simulations for different levels of heterogeneity. We focus on the impact on the BTC of both heterogeneity in K and solute release conditions. It is shown that the injection mode matters, and the differences in the BTCs between uniform and flux-proportional injection increase with the heterogeneity of the K-field. Furthermore, we study the effect of heterogeneity and mode of injection on early and late arrivals at the well.

Overview of the Ogallala Aquifer Program

USDA-ARS?s Scientific Manuscript database

Irrigation increased markedly on the Southern High Plains during the second half of the 20th century, drawing water primarily from the Ogallala Aquifer. During this time, irrigation sustained regional farm incomes and rural economies. Withdrawals from the aquifer, however, have exceeded recharge, re...

4. TYPICAL COLUMN BASE (COLUMN #1 ON PHOTO ELEVATION PLAN) ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. TYPICAL COLUMN BASE (COLUMN #1 ON PHOTO ELEVATION PLAN) FACING SOUTH. - U.S. Naval Base, Pearl Harbor, Signal Tower, Corner of Seventh Street & Avenue D east of Drydock No. 1, Pearl City, Honolulu County, HI

Groundwater vulnerability mapping of Qatar aquifers

NASA Astrophysics Data System (ADS)

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.

Nuclear reactor control column

DOEpatents

Bachovchin, Dennis M.

1982-01-01

The nuclear reactor control column comprises a column disposed within the nuclear reactor core having a variable cross-section hollow channel and containing balls whose vertical location is determined by the flow of the reactor coolant through the column. The control column is divided into three basic sections wherein each of the sections has a different cross-sectional area. The uppermost section of the control column has the greatest cross-sectional area, the intermediate section of the control column has the smallest cross-sectional area, and the lowermost section of the control column has the intermediate cross-sectional area. In this manner, the area of the uppermost section can be established such that when the reactor coolant is flowing under normal conditions therethrough, the absorber balls will be lifted and suspended in a fluidized bed manner in the upper section. However, when the reactor coolant flow falls below a predetermined value, the absorber balls will fall through the intermediate section and into the lowermost section, thereby reducing the reactivity of the reactor core and shutting down the reactor.

Design and Prototype of an Automated Column-Switching HPLC System for Radiometabolite Analysis.

PubMed

Vasdev, Neil; Collier, Thomas Lee

2016-08-17

Column-switching high performance liquid chromatography (HPLC) is extensively used for the critical analysis of radiolabeled ligands and their metabolites in plasma. However, the lack of streamlined apparatus and consequently varying protocols remain as a challenge among positron emission tomography laboratories. We report here the prototype apparatus and implementation of a fully automated and simplified column-switching procedure to allow for the easy and automated determination of radioligands and their metabolites in up to 5 mL of plasma. The system has been used with conventional UV and coincidence radiation detectors, as well as with a single quadrupole mass spectrometer.

Programmable selectivity for GC with series-coupled columns using pulsed heating of the second column.

PubMed

Whiting, Joshua; Sacks, Richard

2003-05-15

A series-coupled ensemble of a nonpolar dimethyl polysiloxane column and a polar trifluoropropylmethyl polysiloxane column with independent at-column heating is used to obtain pulsed heating of the second column. For mixture component bands that are separated by the first column but coelute from the column ensemble, a temperature pulse is initiated after the first of the two components has crossed the column junction point and is in the second column, while the other component is still in the first column. This accelerates the band for the first component. If the second column cools sufficiently prior to the second component band crossing the junction, the second band experiences less acceleration, and increased separation is observed for the corresponding peaks in the ensemble chromatogram. High-speed at-column heating is obtained by wrapping the fused-silica capillary column with resistance heater wire and sensor wire. Rapid heating for a temperature pulse is obtained with a short-duration linear heating ramp of 1000 degrees C/min. During a pulse, the second-column temperature increases by 20-100 degrees C in a few seconds. Using a cold gas environment, cooling to a quiescent temperature of 30 degrees C can be obtained in approximately 25 s. The effects of temperature pulse initiation time and amplitude on ensemble peak separation and resolution are described. A series of appropriately timed temperature pulses is used to separate three coeluting pairs of components in a 13-component mixture.

Transient well flow in leaky multiple-aquifer systems

NASA Astrophysics Data System (ADS)

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.

Water quality of the Edwards Aquifer and streams recharging the aquifer in the San Antonio region, Texas

USGS Publications Warehouse

Roddy, W.R.

1992-01-01

The Edwards aquifer in south-central Texas is one of the most productive and most important aquifers in the State, with an average annual discharge of about 608,000 acre-ft of water during 1932-82 (Reeves and Ozuna, 1985).  The Edwards aquifer is the principal source of water for municipal, industrial, and irrigation use in all or parts of five counties- Bexar, Comal, hays, Medina, and Uvalde- and is the only source of water for San Antonio, the tenth-largest city in the United States (1980 population, 786,000) (A.H. Belo Corporation, 1985).

Column Selection for Biomedical Analysis Supported by Column Classification Based on Four Test Parameters.

PubMed

Plenis, Alina; Rekowska, Natalia; Bączek, Tomasz

2016-01-21

This article focuses on correlating the column classification obtained from the method created at the Katholieke Universiteit Leuven (KUL), with the chromatographic resolution attained in biomedical separation. In the KUL system, each column is described with four parameters, which enables estimation of the FKUL value characterising similarity of those parameters to the selected reference stationary phase. Thus, a ranking list based on the FKUL value can be calculated for the chosen reference column, then correlated with the results of the column performance test. In this study, the column performance test was based on analysis of moclobemide and its two metabolites in human plasma by liquid chromatography (LC), using 18 columns. The comparative study was performed using traditional correlation of the FKUL values with the retention parameters of the analytes describing the column performance test. In order to deepen the comparative assessment of both data sets, factor analysis (FA) was also used. The obtained results indicated that the stationary phase classes, closely related according to the KUL method, yielded comparable separation for the target substances. Therefore, the column ranking system based on the FKUL-values could be considered supportive in the choice of the appropriate column for biomedical analysis.

The Fire Resistance Performance of Recycled Aggregate Concrete Columns with Different Concrete Compressive Strengths

PubMed Central

Dong, Hongying; Cao, Wanlin; Bian, Jianhui; Zhang, Jianwei

2014-01-01

In order to ascertain the fire resistance performance of recycled aggregate concrete (RAC) components with different concrete compressive strengths, four full-scaled concrete columns were designed and tested under high temperature. Two of the four specimens were constructed by normal concrete with compressive strength ratings of C20 and C30, respectively, while the others were made from recycled coarse aggregate (RCA) concrete of C30 and C40, respectively. Identical constant axial forces were applied to specimens while being subjected to simulated building fire conditions in a laboratory furnace. Several parameters from the experimental results were comparatively analyzed, including the temperature change, vertical displacement, lateral deflection, fire endurance, and failure characteristics of specimens. The temperature field of specimens was simulated with ABAQUS Software (ABAQUS Inc., Provindence, RI, USA) and the results agreed quite well with those from the experiments. Results show that the rate of heat transfer from the surface to the interior of the column increases with the increase of the concrete’s compressive strength for both RAC columns and normal concrete columns. Under the same initial axial force ratio, for columns with the same cross section, those with lower concrete compressive strengths demonstrate better fire resistance performance. The fire resistance performance of RAC columns is better than that of normal concrete columns, with the same concrete compressive strength. PMID:28788279

The Fire Resistance Performance of Recycled Aggregate Concrete Columns with Different Concrete Compressive Strengths.

PubMed

Dong, Hongying; Cao, Wanlin; Bian, Jianhui; Zhang, Jianwei

2014-12-08

In order to ascertain the fire resistance performance of recycled aggregate concrete (RAC) components with different concrete compressive strengths, four full-scaled concrete columns were designed and tested under high temperature. Two of the four specimens were constructed by normal concrete with compressive strength ratings of C20 and C30, respectively, while the others were made from recycled coarse aggregate (RCA) concrete of C30 and C40, respectively. Identical constant axial forces were applied to specimens while being subjected to simulated building fire conditions in a laboratory furnace. Several parameters from the experimental results were comparatively analyzed, including the temperature change, vertical displacement, lateral deflection, fire endurance, and failure characteristics of specimens. The temperature field of specimens was simulated with ABAQUS Software (ABAQUS Inc., Provindence, RI, USA) and the results agreed quite well with those from the experiments. Results show that the rate of heat transfer from the surface to the interior of the column increases with the increase of the concrete's compressive strength for both RAC columns and normal concrete columns. Under the same initial axial force ratio, for columns with the same cross section, those with lower concrete compressive strengths demonstrate better fire resistance performance. The fire resistance performance of RAC columns is better than that of normal concrete columns, with the same concrete compressive strength.

Stability of column-supported embankments.

DOT National Transportation Integrated Search

2006-01-01

Column-supported embankments have a great potential for application in the coastal regions of Virginia, where highway embankments are often constructed on soft ground. The columns can be driven piles, vibro-concrete columns, deep-mixing-method column...

Geohydrology of the Dakota Aquifer

NASA Astrophysics Data System (ADS)

Johnson, Ivan

This book is the result of a symposium on the geology and hydrology of the Dakota Aquifer system. The symposium and this proceedings were dedicated to C. V. Theis, who is widely considered to be the father of modern quantitative methods in groundwater hydrology. The aquifer area that is discussed in this series o f papers coincides to a great extent with the Central Midwest Regional Aquifer System Analysis (RASA) project. This was was one of the many RASA projects shown in the map on the cover of the April 14, 1987, Eos. The proceedings provides a multidisciplinary look at details concerning the hydrology and geology overviews, as well as more specialized discussions of the hydrodynamics of petroleum accumulation, geothermal assessment, hydrochemistry, and water use in the Dakota Sandstone and equivalent units.

Potentiometric surface of the intermediate aquifer system, west- central Florida, May 1987

USGS Publications Warehouse

Lewelling, B.R.

1988-01-01

The intermediate aquifer system within the Southwest Florida Water Management District underlies a 5,000 sq mi area of De Soto, Sarasota, Hardee, Manatee, and parts of Charlotte, Hillsborough, Highlands, and Polk Counties. The intermediate aquifer system occurs between the overlying surficial aquifer system and the underlying Floridan aquifer system, and consists of layers of sand, shell, clay, marl, limestone, and dolom of the Tamiami, Hawthorn, and Tampa Formations of late Tertiary age. The intermediate aquifer system contains one or more water-bearing units separated by discontinuous confining units. This aquifer system is the principal source of potable water in the southwestern part of the study area and is widely used as a source of water in other parts where wells are open to the intermediate aquifer system or to both the intermediate and Floridan aquifer systems. Yields of individual wells open to the intermediate aquifer system range from a few gallons to several hundred gallons per minute. The volume of water withdrawn from the intermediate aquifer system is considerably less than that withdrawn from the Floridan aquifer system in the study area. The surface was mapped by determining the altitude of water levels in a network of wells and is represented on maps by contours that connect points of equal altitude. The compos potentiometric surface of all water-bearing units within the intermediate aquifer system is shown. In areas where multiple aquifers exist, wells open to all aquifers were selected for water level measurements whenever possible. In the southwestern and lower coastal region of the study area, two aquifers and confining units are described for the intermediate aquifer system: the Tamiami-upper Hawthorn aquifer and the underlying lower Hawthorn-upper Tampa aquifer. The potentiometric surface of the Tamiami-upper Hawthorn aquifer is also shown. Water levels are from wells drilled and open exclusively to that aquifer. The exact boundary for the