Water and Solute Mass Transport in Soils Developed on glacial Drift: A Br Tracer Investigation Using Instrumented Soil Monoliths at an Agricultural Long Term Ecological Research Site (Kellogg Biological Station, Hickory Corners, Southern Michigan)

NASA Astrophysics Data System (ADS)

Jin, L.; Hamilton, S. K.; Walter, L. M.

2004-12-01

Hydrologic processes control the residence time of water in the soil column. This is of central importance in understanding mineral weathering rates in terms of reaction kinetics and solute transport. In order to better quantify the coupling between water and solute mass transport and to better define controls on carbonate and aluminosilicates weathering rates, we have conducted bromide-tracer introduction experiments at four replicate soil monoliths (4 m3 volume) instrumented and managed by the KBS-LTER. Monolith soils are developed on the pitted outwash plain of the morainic system left by the last retreat of the Wisconsin glaciation, around 12,000 years ago. Soil profiles from the monolith sections extend to 200 cm and they were sampled and characterized texturally and mineralogically. Quartz and feldspar are dominant throughout the soil profile, while carbonates and hornblende occur only in deeper soil horizons. The four replicate monoliths are instrumented with gas and soil water sampling devices (Prenart tension lysimeters) at various depths. The monoliths also have a large capacity tray at the bottom, which permits collection of water for weight and chemical determinations. A bromide tracer solution (as lithium bromide) was applied to coincide as closely as possible with a major snowmelt event (2/27/04). The saturated and unsaturated transport of bromide through the four monoliths was followed as a function of time and soil profile depth for the duration of the snowmelt as well as intermittent rain events. Because the soil was saturated at the time of bromide application, the bromide solution is expected to move rapidly through macropores, followed by slower movement into micropores. The unsaturated transport of bromide is largely controlled by the intensity and duration of the rains if it is dominated by piston flow as opposed to preferential channel flow. In general, the tracer moved through the shallow soils very quickly, which is shown by early sharp peaks in bromide concentrations. Transport of bromide into deeper soil horizons, however, differs markedly among the four monoliths. Even within a given monolith, waters sampled at the same depth by different tension lysimeters show a very different pattern of bromide transport over time with some lyimeters suggesting piston flow, while others in the same monolith suggest preferential channel flow. These differences are likely driven by heterogeneous soil textures. The water recovered from the monolith trays over the first three months of the study period is between 80 and 90 percent of the total precipitation recorded at the LTER site. This recovery is reasonable given the fact that temperature was low and crops were not yet actively growing. The recovery of bromide is different among the monoliths and in general is less than 50 percent, which means more than 50 percent of tracer is still in the soils even after three months. Residence time of water has been calculated after some assumptions on the breakthrough curve. The water mass transport constraints imposed by the bromide tracer study will be utilized in concert with additional data on soil water geochemistry.

Estimating groundwater recharge in Hebei Plain, China under varying land use practices using tritium and bromide tracers

NASA Astrophysics Data System (ADS)

Wang, Bingguo; Jin, Menggui; Nimmo, John R.; Yang, Lei; Wang, Wenfeng

2008-07-01

SummaryTritium and bromide were used as applied tracers to determine groundwater recharge in Hebei Plain, North China, to evaluate the impacts of different soil types, land use, irrigation, and crop cultivation practice on recharge. Additional objectives were to evaluate temporal variability of recharge and the effect on results of the particular tracer used. Thirty-nine profiles at representative locations were chosen for investigation. Average recharge rates and recharge coefficient determined by tritium and bromide tracing for different sites were 0.00-1.05 mm/d and 0.0-42.5%, respectively. The results showed relative recharge rates for the following paired influences (items within each pair are listed with the influence producing greater recharge first): flood-irrigated cropland and non-irrigated non-cultivation land, flood irrigation (0.42-0.58 mm/d) and sprinkling irrigation (0.17-0.23 mm/d), no stalk mulch (0.56-0.80 mm/d) and stalk mulch (0.44-0.60 mm/d), vegetable (e.g. Chinese cabbage and garlic, 0.70 mm/d) and wheat-maize (0.38 mm/d), peanut (0.51 mm/d) and peach (0.43 mm/d). The results also showed greater recharge for the first year of tracer travel than for the second. Because total precipitation and irrigation were greater in the first year than in the second, this may reflect temporal variability of recharge. The method may not be applicable where the water table is shallow (less than 3 m). A comparison of the near-ideal tritium tracer with the more common but less ideal bromide showed that bromide moved approximately 23% faster than tritiated water, perhaps because of anion exclusion.

Estimating groundwater recharge in Hebei Plain, China under varying land use practices using tritium and bromide tracers

USGS Publications Warehouse

Wang, B.; Jin, M.; Nimmo, J.R.; Yang, L.; Wang, W.

2008-01-01

Tritium and bromide were used as applied tracers to determine groundwater recharge in Hebei Plain, North China, to evaluate the impacts of different soil types, land use, irrigation, and crop cultivation practice on recharge. Additional objectives were to evaluate temporal variability of recharge and the effect on results of the particular tracer used. Thirty-nine profiles at representative locations were chosen for investigation. Average recharge rates and recharge coefficient determined by tritium and bromide tracing for different sites were 0.00-1.05 mm/d and 0.0-42.5%, respectively. The results showed relative recharge rates for the following paired influences (items within each pair are listed with the influence producing greater recharge first): flood-irrigated cropland and non-irrigated non-cultivation land, flood irrigation (0.42-0.58 mm/d) and sprinkling irrigation (0.17-0.23 mm/d), no stalk mulch (0.56-0.80 mm/d) and stalk mulch (0.44-0.60 mm/d), vegetable (e.g. Chinese cabbage and garlic, 0.70 mm/d) and wheat-maize (0.38 mm/d), peanut (0.51 mm/d) and peach (0.43 mm/d). The results also showed greater recharge for the first year of tracer travel than for the second. Because total precipitation and irrigation were greater in the first year than in the second, this may reflect temporal variability of recharge. The method may not be applicable where the water table is shallow (less than 3 m). A comparison of the near-ideal tritium tracer with the more common but less ideal bromide showed that bromide moved approximately 23% faster than tritiated water, perhaps because of anion exclusion. ?? 2008 Elsevier B.V.

Using predictive uncertainty analysis to optimise tracer test design and data acquisition

NASA Astrophysics Data System (ADS)

Wallis, Ilka; Moore, Catherine; Post, Vincent; Wolf, Leif; Martens, Evelien; Prommer, Henning

2014-07-01

Tracer injection tests are regularly-used tools to identify and characterise flow and transport mechanisms in aquifers. Examples of practical applications are manifold and include, among others, managed aquifer recharge schemes, aquifer thermal energy storage systems and, increasingly important, the disposal of produced water from oil and shale gas wells. The hydrogeological and geochemical data collected during the injection tests are often employed to assess the potential impacts of injection on receptors such as drinking water wells and regularly serve as a basis for the development of conceptual and numerical models that underpin the prediction of potential impacts. As all field tracer injection tests impose substantial logistical and financial efforts, it is crucial to develop a solid a-priori understanding of the value of the various monitoring data to select monitoring strategies which provide the greatest return on investment. In this study, we demonstrate the ability of linear predictive uncertainty analysis (i.e. “data worth analysis”) to quantify the usefulness of different tracer types (bromide, temperature, methane and chloride as examples) and head measurements in the context of a field-scale aquifer injection trial of coal seam gas (CSG) co-produced water. Data worth was evaluated in terms of tracer type, in terms of tracer test design (e.g., injection rate, duration of test and the applied measurement frequency) and monitoring disposition to increase the reliability of injection impact assessments. This was followed by an uncertainty targeted Pareto analysis, which allowed the interdependencies of cost and predictive reliability for alternative monitoring campaigns to be compared directly. For the evaluated injection test, the data worth analysis assessed bromide as superior to head data and all other tracers during early sampling times. However, with time, chloride became a more suitable tracer to constrain simulations of physical transport processes, followed by methane. Temperature data was assessed as the least informative of the solute tracers. However, taking costs of data acquisition into account, it could be shown that temperature data when used in conjunction with other tracers was a valuable and cost-effective marker species due to temperatures low cost to worth ratio. In contrast, the high costs of acquisition of methane data compared to its muted worth, highlighted methanes unfavourable return on investment. Areas of optimal monitoring bore position as well as optimal numbers of bores for the investigated injection site were also established. The proposed tracer test optimisation is done through the application of common use groundwater flow and transport models in conjunction with publicly available tools for predictive uncertainty analysis to provide modelers and practitioners with a powerful yet efficient and cost effective tool which is generally applicable and easily transferrable from the present study to many applications beyond the case study of injection of treated CSG produced water.

Characterization of the intragranular water regime within subsurface sediments: Pore volume, surface area, and mass transfer limitations

USGS Publications Warehouse

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

2011-01-01

Although "intragranular" pore space within grain aggregates, grain fractures, and mineral surface coatings may contain a relatively small fraction of the total porosity within a porous medium, it often contains a significant fraction of the reactive surface area, and can thus strongly affect the transport of sorbing solutes. In this work, we demonstrate a batch experiment procedure using tritiated water as a high-resolution diffusive tracer to characterize the intragranular pore space. The method was tested using uranium-contaminated sediments from the vadose and capillary fringe zones beneath the former 300A process ponds at the Hanford site (Washington). Sediments were contacted with tracers in artificial groundwater, followed by a replacement of bulk solution with tracer-free groundwater and the monitoring of tracer release. From these data, intragranular pore volumes were calculated and mass transfer rates were quantified using a multirate first-order mass transfer model. Tritium-hydrogen exchange on surface hydroxyls was accounted for by conducting additional tracer experiments on sediment that was vacuum dried after reaction. The complementary ("wet" and "dry") techniques allowed for the simultaneous determination of intragranular porosity and surface area using tritium. The Hanford 300A samples exhibited intragranular pore volumes of ???1% of the solid volume and intragranular surface areas of ???20%-35% of the total surface area. Analogous experiments using bromide ion as a tracer yielded very different results, suggesting very little penetration of bromide into the intragranular porosity. Copyright 2011 by the American Geophysical Union.

Characterization of the intragranular water regime within subsurface sediments: pore volume, surface area, and mass transfer limitations

USGS Publications Warehouse

Hay, Michael B.; Stoliker, Deborah L.; Davis, James A.; Zachara, John M.

2011-01-01

Although "intragranular" pore space within grain aggregates, grain fractures, and mineral surface coatings may contain a relatively small fraction of the total porosity within a porous medium, it often contains a significant fraction of the reactive surface area, and can thus strongly affect the transport of sorbing solutes. In this work, we demonstrate a batch experiment procedure using tritiated water as a high-resolution diffusive tracer to characterize the intragranular pore space. The method was tested using uranium-contaminated sediments from the vadose and capillary fringe zones beneath the former 300A process ponds at the Hanford site (Washington). Sediments were contacted with tracers in artificial groundwater, followed by a replacement of bulk solution with tracer-free groundwater and the monitoring of tracer release. From these data, intragranular pore volumes were calculated and mass transfer rates were quantified using a multirate first-order mass transfer model. Tritium-hydrogen exchange on surface hydroxyls was accounted for by conducting additional tracer experiments on sediment that was vacuum dried after reaction. The complementary ("wet" and "dry") techniques allowed for the simultaneous determination of intragranular porosity and surface area using tritium. The Hanford 300A samples exhibited intragranular pore volumes of ~1% of the solid volume and intragranular surface areas of ~20%–35% of the total surface area. Analogous experiments using bromide ion as a tracer yielded very different results, suggesting very little penetration of bromide into the intragranular porosity.

Subsurface fate and transport of sulfamethoxazole, 4-nonylphenol, and 17β-estradiol

USGS Publications Warehouse

Barber, L.B.; Meyer, M.T.; LeBlanc, D.R.; Kolpin, Dana W.; Radley, Paul; Chapelle, F.; Rubio, F.

2008-01-01

Subsurface fate and transport of the antibiotic sulfamethoxazole (SX), the non-ionic surfactant degradation product 4-nonylphenol (NP), and the sex hormone 17β-estradiol (E2) were evaluated in a plume of contaminated groundwater at Cape Cod, Massachusetts, USA. The plume is the result of 60 years of wastewater treatment plant effluent disposal into rapid infiltration beds. Natural-gradient, in situ tracer experiments were used to evaluate subsurface transport of SX, NP, and E2 (injected at 300, 530, and 0.55 µg/L, respectively) relative to the conservative tracer bromide. Two geochemical zones were evaluated: (1) uncontaminated groundwater overlying the plume, and (2) contaminated groundwater within the plume that has recently become oxic after decades of anoxic conditions. The uncontaminated groundwater is characterized by a microbial community unacclimated to treated wastewater, whereas the contaminated groundwater is characterized by microbes acclimated to wastewater contaminants. Results from the tracer tests in both zones showed that the antibiotic SX was co-transported with the conservative tracer bromide, with little retardation or mass removal. In contrast, NP and E2, which are more hydrophobic and biodegradable, showed sorption (relative retardation factors ranged up to 5.9) and mass loss at both the uncontaminated and contaminated sites.

Virus fate and transport during recharge using recycled water at a research field site in the Montebello Forebay, Los Angeles County, California, 1997-2000

USGS Publications Warehouse

Anders, Robert; Yanko, William A.; Schroeder, Roy A.; Jackson, James L.

2004-01-01

Total and fecal coliform bacteria distributions in subsurface water samples collected at a research field site in Los Angeles County were found to increase from nondetectable levels immediately before artificial recharge using tertiary-treated municipal wastewater (recycled water). This rapid increase indicates that bacteria can move through the soil with the percolating recycled water over intervals of a few days and vertical and horizontal distances of about 3 meters. This conclusion formed the basis for three field-scale experiments using bacterial viruses (bacteriophage) MS2 and PRD1 as surrogates for human enteric viruses and bromide as a conservative tracer to determine the fate and transport of viruses in recycled water during subsurface transport under actual recharge conditions. The research field site consists of a test basin constructed adjacent to a large recharge facility (spreading grounds) located in the Montebello Forebay of Los Angeles County, California. The soil beneath the test basin is predominantly medium to coarse, moderately sorted, grayish-brown sand. The three tracer experiments were conducted during August 1997, August-September 1998, and August 2000. For each experiment, prepared solutions of bacteriophage and bromide were sprayed on the surface of the water in the test basin and injected, using peristaltic pumps, directly into the feed pipe delivering the recycled water to the test basin. Extensive data were obtained for water samples collected from the test basin itself and from depths of 0.3, 0.6, 1.0, 1.5, 3.0, and 7.6 meters below the bottom of the test basin. The rate of bacteriophage inactivation in the recycled water, independent of any processes occurring in the subsurface, was determined from measurements on water samples from the test basin. Regression analysis of the ratios of bacteriophage to bromide was used to determine the attenuation rates for MS2 and PRD1, defined as the logarithmic reduction in the ratio during each experiment. Although the inactivation rates increased during the third tracer experiment, they were nearly two orders of magnitude less than the attenuation rates. Therefore, adsorption, not inactivation, is the predominant removal mechanism for viruses during artificial recharge. Using the colloid-filtration model, the collision efficiency was determined for both bacteriophage during the second and third field-scale tracer experiments. The collision efficiency confirms that more favorable attachment conditions existed for PRD1, especially during the third tracer experiment. The different collision efficiencies between the second and third tracer experiments possibly were due to changing hydraulic conditions at the research field site during each experiment. The field data suggest that an optimal management scenario might exist to maximize the amount of recycled water that can be applied to the spreading grounds while still maintaining favorable attachment conditions for virus removal and thereby ensuring protection of the ground-water supply.

Design and hydraulic characteristics of a field-scale bi-phasic bioretention rain garden system for storm water management.

PubMed

Yang, H; Florence, D C; McCoy, E L; Dick, W A; Grewal, P S

2009-01-01

A field-scale bioretention rain garden system was constructed using a novel bi-phasic (i.e. sequence of anaerobic to aerobic) concept for improving retention and removal of storm water runoff pollutants. Hydraulic tests with bromide tracer and simulated runoff pollutants (nitrate-N, phosphate-P, Cu, Pb, and Zn) were performed in the system under a simulated continuous rainfall. The objectives of the tests were (1) to determine hydraulic characteristics of the system, and (2) to evaluate the movement of runoff pollutants through the system. For the 180 mm/24 h rainfall, the bi-phasic bioretention system effectively reduced both peak flow (approximately 70%) and runoff volume (approximately 42%). The breakthrough curves (BTCs) of bromide tracer suggest that the transport pattern of the system is similar to dispersed plug flow under this large runoff event. The BTCs of bromide showed mean 10% and 90% breakthrough times of 5.7 h and 12.5 h, respectively. Under the continuous rainfall, a significantly different transport pattern was found between each runoff pollutant. Nitrate-N was easily transported through the system with potential leaching risk from the initial soil medium, whereas phosphate-P and metals were significantly retained indicating sorption-mediated transport. These findings support the importance of hydraulics, in combination with the soil medium, when creating bioretention systems for bioremediation that are effective for various rainfall sizes and intervals.

Doublet tracer tests to determine the contaminant flushing properties of a municipal solid waste landfill.

PubMed

Woodman, N D; Rees-White, T C; Beaven, R P; Stringfellow, A M; Barker, J A

2017-08-01

This paper describes a programme of research investigating horizontal fluid flow and solute transport through saturated municipal solid waste (MSW) landfill. The purpose is to inform engineering strategies for future contaminant flushing. Solute transport between injection/abstraction well pairs (doublets) is investigated using three tracers over five separate tests at well separations between 5m and 20m. Two inorganic tracers (lithium and bromide) were used, plus the fluorescent dye tracer, rhodamine-WT. There was no evidence for persistent preferential horizons or pathways at the inter-well scale. The time for tracer movement to the abstraction wells varied with well spacing as predicted for a homogeneous isotropic continuum. The time for tracer movement to remote observation wells was also as expected. Mobile porosity was estimated as ~0.02 (~4% of total porosity). Good fits to the tracer breakthrough data were achieved using a dual-porosity model, with immobile regions characterised by block diffusion timescales in the range of about one to ten years. This implies that diffusional exchanges are likely to be very significant for engineering of whole-site contaminant flushing and possibly rate-limiting. Copyright © 2017. Published by Elsevier B.V.

Doublet tracer tests to determine the contaminant flushing properties of a municipal solid waste landfill

NASA Astrophysics Data System (ADS)

Woodman, N. D.; Rees-White, T. C.; Beaven, R. P.; Stringfellow, A. M.; Barker, J. A.

2017-08-01

This paper describes a programme of research investigating horizontal fluid flow and solute transport through saturated municipal solid waste (MSW) landfill. The purpose is to inform engineering strategies for future contaminant flushing. Solute transport between injection/abstraction well pairs (doublets) is investigated using three tracers over five separate tests at well separations between 5 m and 20 m. Two inorganic tracers (lithium and bromide) were used, plus the fluorescent dye tracer, rhodamine-WT. There was no evidence for persistent preferential horizons or pathways at the inter-well scale. The time for tracer movement to the abstraction wells varied with well spacing as predicted for a homogeneous isotropic continuum. The time for tracer movement to remote observation wells was also as expected. Mobile porosity was estimated as 0.02 ( 4% of total porosity). Good fits to the tracer breakthrough data were achieved using a dual-porosity model, with immobile regions characterised by block diffusion timescales in the range of about one to ten years. This implies that diffusional exchanges are likely to be very significant for engineering of whole-site contaminant flushing and possibly rate-limiting.

A laboratory study of colloid and solute transport in surface runoff on saturated soil

NASA Astrophysics Data System (ADS)

Yu, Congrong; Gao, Bin; Muñoz-Carpena, Rafael; Tian, Yuan; Wu, Lei; Perez-Ovilla, Oscar

2011-05-01

SummaryColloids in surface runoff may pose risks to the ecosystems not only because some of them (e.g., pathogens) are toxic, but also because they may facilitate the transport of other contaminants. Although many studies have been conducted to explore colloid fate and transport in the environment, current understanding of colloids in surface runoff is still limited. In this study, we conducted a range of laboratory experiments to examine the transport behavior of colloids in a surface runoff system, made of a soil box packed with quartz sand with four soil drainage outlets and one surface flow outlet. A natural clay colloid (kaolinite) and a conservative chemical tracer (bromide) were applied to the system under a simulated rainfall event (64 mm/h). Effluent soil drainage and surface flow samples were collected to determine the breakthrough concentrations of bromide and kaolinite. Under the experimental conditions tested, our results showed that surface runoff dominated the transport processes. As a result, kaolinite and bromide were found more in surface flow than in soil drainage. Comparisons between the breakthrough concentrations of bromide and kaolinite showed that kaolinite had lower mobility than bromide in the subsurface flow (i.e., soil drainage), but behaved almost identical to bromide in the surface runoff. Student's t-test confirmed the difference between kaolinite and bromide in subsurface flow ( p = 0.02). Spearman's test and linear regression analysis, however, showed a strong 1:1 correlation between kaolinite and bromide in surface runoff ( p < 0.0001). Our result indicate that colloids and chemical solutes may behave similarly in overland flow on bare soils with limited drainage when surface runoff dominates the transport processes.

Tracer test with As(V) under variable redox conditions controlling arsenic transport in the presence of elevated ferrous iron concentrations

USGS Publications Warehouse

Hohn, R.; Isenbeck-Schroter, M.; Kent, D.B.; Davis, J.A.; Jakobsen, R.; Jann, S.; Niedan, V.; Scholz, C.; Stadler, S.; Tretner, A.

2006-01-01

To study transport and reactions of arsenic under field conditions, a small-scale tracer test was performed in an anoxic, iron-reducing zone of a sandy aquifer at the USGS research site on Cape Cod, Massachusetts, USA. For four weeks, a stream of groundwater with added As(V) (6.7????M) and bromide (1.6??mM), was injected in order to observe the reduction of As(V) to As(III). Breakthrough of bromide (Br-), As(V), and As(III) as well as additional parameters characterizing the geochemical conditions was observed at various locations downstream of the injection well over a period of 104??days. After a short lag period, nitrate and dissolved oxygen from the injectate oxidized ferrous iron and As(V) became bound to the freshly formed hydrous iron oxides. Approximately one week after terminating the injection, anoxic conditions had been reestablished and increases in As(III) concentrations were observed within 1??m of the injection. During the observation period, As(III) and As(V) were transported to a distance of 4.5??m downgradient indicating significant retardation by sorption processes for both species. Sediment assays as well as elevated concentrations of hydrogen reflected the presence of As(V) reducing microorganisms. Thus, microbial As(V) reduction was thought to be one major process driving the release of As(III) during the tracer test in the Cape Cod aquifer. ?? 2006 Elsevier B.V. All rights reserved.

A Tracer Test at the Los Alamos Canyon Weir

NASA Astrophysics Data System (ADS)

Levitt, D. G.; Stone, W. J.; Newell, D. L.; Wykoff, D. S.

2002-12-01

A low-head weir was constructed in the Los Alamos Canyon to reduce the transport of contaminant-bearing sediment caused by fire-enhanced runoff off Los Alamos National Laboratory (LANL) property towards the Rio Grande following the May 2000 Cerro Grande fire at Los Alamos, New Mexico. Fractured basalt was exposed in the channel by grading during construction of the weir, and water temporarily ponds behind the weir following periods of runoff. In order to monitor any downward transport of contaminants into fractured basalt, and potentially downward to the regional ground water, three boreholes (one vertical, one at 43 degrees, and one at 34 degrees from horizontal) were installed for environmental monitoring. The boreholes penetrate to depths ranging from approximately 9 to 82 m below the weir floor. The two angled boreholes are fitted with flexible FLUTe liners with resistance sensors to measure relative moisture content and absorbent sampling pads for contaminant and environmental tracer sampling within the vadose zone. The two angled boreholes are also monitored for relative changes in moisture content by neutron logging. The vertical borehole penetrates three perched water zones and is equipped with four screens and sampling ports. In April 2002, a tracer test was initiated with the application of a 0.2 M (16,000 ppm) solution of potassium bromide (KBr) onto the weir floor. The tracer experiment was intended to provide data on travel times through the complex hydrogeologic media of fractured basalt. A precipitation and runoff event in June 2002 resulted in approximately 0.61 m of standing water behind the weir. If the KBr and flood waters were well mixed, the concentration of KBr in the flood waters was approximately 24 ppm. Bromide was detected in the absorbent membrane in the 43 degree hole at concentrations up to 2 ppm. Resistance sensors in the 43 degree borehole detected moisture increases within 3 days at a depth of 27 m, indicating an average wetting front velocity of 8.9 m per day in the vadose zone. Increases in bromide concentrations were detected in water samples from two of the four sampling ports in the vertical well within 10 days of the precipitation event, indicating an average wetting front velocity of 5.5 m per day to the sample port at a depth of 55 m below the weir floor. Increases in bromide concentrations were detected at the bottom port of the vertical well at a depth of 78 m below the weir floor within 21 days, indicating an average wetting front velocity of 3.7 m per day. Modeling of this tracer test data will improve our understanding of: the impact of the fire on ground-water quality; the impact of the weir on ground-water quality; surface water/ground water interactions; and the hydraulic properties of the Cerros del Rio basalts underlying the eastern Pajarito Plateau.

How ISCO Can Interfere in Soil Pore Distribution and Solute Transport

NASA Astrophysics Data System (ADS)

Favero, M.; Freitas, J. G.; Furquim, S. A. C.; Thomson, N. R.; Cooper, M.

2016-12-01

Recently in situ chemical oxidation (ISCO) has been a remedy of choice for sites contaminated with organic compounds. However, the impact of the chemical oxidant on soil properties and, therefore, on solute transport and remediation efficiency still lacks understanding. This research effort sought to evaluate the changes in soil physical properties and solute transport behavior in a typical tropical soil (Oxisol) resulting from exposure to persulfate. The Oxisol used had a microaggregate structure, resulting in a relatively high hydraulic conductivity despite the high clay content (67%). One-dimensional laboratory experiments were performed using a saturated undisturbed column. The injection of an ideal tracer (bromide), a reactive tracer (phenol) and persulfate (12 ± 1 gL-1 for 30 d) were performed consecutively. The tracer tests were repeated following persulfate injection. Transport parameters (longitudinal dispersivity: αL and retardation factor: R) and the effective porosity (ne) were obtained by fitting the breakthrough curves with an analytical solution for one-dimensional transport. Micromorphological analyses of porosity were conducted on impregnated soil blocks from control and oxidized systems. The bromide and phenol tracer test data yielded αL of 2.431 ± 0.002 cm, ne of 41.99 ± 1.52 %, R of 1.10, and a first-order decay rate coefficient of 6.5x10-5 min-1 prior to persulfate exposure. The effluent persulfate concentration stabilized at C/Co of 0.8 after 4 d of injection and the breakthrough was delayed relative to bromide. Concurrent with the breakthrough of persulfate, the pH decreased and a progressive release of Al (III) over the first 4 d with subsequent stabilization were observed. Following persulfate exposures the hydraulic conductivity increased about one-order of magnitude. Micromorphological analysis showed that persulfate produced alterations in poroids types, with an increase of complex packing voids. It was verified that persulfate promotes the dissolution of soil minerals, and likely affects the microaggregates structure of the Oxisol, resulting in formation of preferential paths and changing the flux patterns within the soil column.

Transport of microspheres and indigenous bacteria through a sandy aquifer: Results of natural- and forced-gradient tracer experiments

USGS Publications Warehouse

Harvey, R.W.; George, L.H.; Smith, R.L.; LeBlanc, D.R.

1989-01-01

Transport of indigenous bacteria through sandy aquifer sediments was investigated in forced- and natural-gradient tracer teste. A diverse population of bacteria was collected and concentrated from groundwater at the site, stained with a DNA-specific fluorochrome, and injected back into the aquifer. Included with the injectate were a conservative tracer (Br- or Cl-) and bacteria-sized (0.2-1.3-??m) microspheres having carboxylated, carbonyl, or neutral surfaces. Transport of stained bacteria and all types and size classes of microspheres was evident. In the natural-gradient test, both surface characteristics and size of microspheres affected attenuation. Surface characteristics had the greatest effect upon retardation. Peak break-through of DAPI-stained bacteria (forced-gradient experiment) occurred well in advance of bromide at the more distal sampler. Transport behavior of bacteria was substantially different from that of carboxylated microspheres of comparable size. ?? 1988 American Chemical Society.

Evaluating 10B-enriched Boric Acid, Bromide, and Heat as Tracers of Recycled Groundwater Flow near MAR Operations

NASA Astrophysics Data System (ADS)

Becker, T.; Clark, J. F.

2012-12-01

Coupled with the unpredictability of a changing climate, the projected growth in human population over the next century requires new and innovative ways to augment already-depleted water supplies. An increasingly popular and promising development is managed aquifer recharge (MAR), a cost-effective method of intentionally storing potable water in groundwater aquifers at engineered sites worldwide. Reclaimed (or recycled) water, defined as cleaned and treated wastewater, will account for a larger portion of MAR water in future years. A crucial component for managing groundwater recharged with reclaimed water is its subsurface travel time. The California Department of Public Health (CDPH), with the most recent draft of regulations issued on November 21, 2011, requires the application of groundwater tracers to demonstrate subsurface residence time. Residence time increases the quality of reclaimed water via soil-aquifer treatment (SAT), which includes mechanisms such as sorption, biological degradation, and microbial inactivation to remove potential contaminants or pathogens. This study addresses the need for an appropriate tracer to determine groundwater residence times near MAR facilities. Standard shallow groundwater dating techniques, such as T/3He and chlorofluorocarbon (CFC) methods, cannot be used because their uncertainties are typically ± 2 years, longer than the target CDPH retention time of ~6 months. These methods also cannot map preferential flow paths. Sulfur hexafluoride (SF6), a nonreactive synthetic gas, is well-established as a deliberate tracer for determining subsurface travel time; however, SF6 is a very strong greenhouse gas and the California Air Resources Board (CARB) is regulating its emission. Other tracers, such as noble gas isotopes, that have successfully determined subsurface retention times are impractical due to their high cost. A multi-tracer experiment at the San Gabriel Spreading Grounds test basin (Montebello Forebay, Los Angeles County, CA, USA) has been in progress since September 6, 2011, following injection of boric acid enriched in boron-10 (10B) and bromide (Br-) tracers. Tracer concentrations are collected at 9 monitoring wells that have pre-experiment estimated travel times between 0.5 to 180 days. Results indicate that 10B-enriched boric acid is an effective deliberate tracer at MAR sites; however, the ion's movement is slightly retarded relative to bromide by the substrate. 10B/Br- travel time ratios range from 1 to 1.4. In addition to the two deliberate geochemical tracers, heat is being evaluated as a possible intrinsic tracer at MAR sites. At the time of the experiment (late summer), reclaimed water was significantly warmer (~20°F) than the native groundwater as it entered the system. Time series are developed from loggers outfitted at each monitoring well, with measurements recorded hourly accurate to one thousandth of a degree. Results are similar to 10B & Br- travel times and validate the potential of heat as an intrinsic tracer.

Multiple-tracer tests for contaminant transport process identification in saturated municipal solid waste

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

Woodman, N.D., E-mail: n.d.woodman@soton.ac.uk; Rees-White, T.C.; Stringfellow, A.M.

2015-04-15

Highlights: • Multiple tracers were applied to saturated MSW to test dual-porosity properties. • Lithium demonstrated to be non-conservative as a tracer. • 260 mm diameter column too small to test transport properties of MSW. • The classical advection-dispersion mode was rejected due to high dispersivity. • Characteristic diffusion times did not vary with the tracer. - Abstract: Two column tests were performed in conditions emulating vertical flow beneath the leachate table in a biologically active landfill to determine dominant transport mechanisms occurring in landfills. An improved understanding of contaminant transport process in wastes is required for developing better predictionsmore » about potential length of the long term aftercare of landfills, currently measured in timescales of centuries. Three tracers (lithium, bromide and deuterium) were used. Lithium did not behave conservatively. Given that lithium has been used extensively for tracing in landfill wastes, the tracer itself and the findings of previous tests which assume that it has behaved conservatively may need revisiting. The smaller column test could not be fitted with continuum models, probably because the volume of waste was below a representative elemental volume. Modelling compared advection-dispersion (AD), dual porosity (DP) and hybrid AD–DP models. Of these models, the DP model was found to be the most suitable. Although there is good evidence to suggest that diffusion is an important transport mechanism, the breakthrough curves of the different tracers did not differ from each other as would be predicted based on the free-water diffusion coefficients. This suggested that solute diffusion in wastes requires further study.« less

Method for assessment of stormwater treatment facilities - Synthetic road runoff addition including micro-pollutants and tracer.

PubMed

Cederkvist, Karin; Jensen, Marina B; Holm, Peter E

2017-08-01

Stormwater treatment facilities (STFs) are becoming increasingly widespread but knowledge on their performance is limited. This is due to difficulties in obtaining representative samples during storm events and documenting removal of the broad range of contaminants found in stormwater runoff. This paper presents a method to evaluate STFs by addition of synthetic runoff with representative concentrations of contaminant species, including the use of tracer for correction of removal rates for losses not caused by the STF. A list of organic and inorganic contaminant species, including trace elements representative of runoff from roads is suggested, as well as relevant concentration ranges. The method was used for adding contaminants to three different STFs including a curbstone extension with filter soil, a dual porosity filter, and six different permeable pavements. Evaluation of the method showed that it is possible to add a well-defined mixture of contaminants despite different field conditions by having a flexibly system, mixing different stock-solutions on site, and use bromide tracer for correction of outlet concentrations. Bromide recovery ranged from only 12% in one of the permeable pavements to 97% in the dual porosity filter, stressing the importance of including a conservative tracer for correction of contaminant retention values. The method is considered useful in future treatment performance testing of STFs. The observed performance of the STFs is presented in coming papers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Tracer-based characterization of hyporheic exchange and benthic biolayers in streams

NASA Astrophysics Data System (ADS)

Knapp, Julia L. A.; González-Pinzón, Ricardo; Drummond, Jennifer D.; Larsen, Laurel G.; Cirpka, Olaf A.; Harvey, Judson W.

2017-02-01

Shallow benthic biolayers at the top of the streambed are believed to be places of enhanced biogeochemical turnover within the hyporheic zone. They can be investigated by reactive stream tracer tests with tracer recordings in the streambed and in the stream channel. Common in-stream measurements of such reactive tracers cannot localize where the processing primarily takes place, whereas isolated vertical depth profiles of solutes within the hyporheic zone are usually not representative of the entire stream. We present results of a tracer test where we injected the conservative tracer bromide together with the reactive tracer resazurin into a third-order stream and combined the recording of in-stream breakthrough curves with multidepth sampling of the hyporheic zone at several locations. The transformation of resazurin was used as an indicator of metabolism, and high-reactivity zones were identified from depth profiles. The results from our subsurface analysis indicate that the potential for tracer transformation (i.e., the reaction rate constant) varied with depth in the hyporheic zone. This highlights the importance of the benthic biolayer, which we found to be on average 2 cm thick in this study, ranging from one third to one half of the full depth of the hyporheic zone. The reach-scale approach integrated the effects of processes along the reach length, isolating hyporheic processes relevant for whole-stream chemistry and estimating effective reaction rates.

Tracer-based characterization of hyporheic exchange and benthic biolayers in streams

USGS Publications Warehouse

Knapp, Julia L.A.; González-Pinzón, Ricardo; Drummond, Jennifer D.; Larsen, Laurel G.; Cirpka, Olaf A.; Harvey, Judson W.

2017-01-01

Shallow benthic biolayers at the top of the streambed are believed to be places of enhanced biogeochemical turnover within the hyporheic zone. They can be investigated by reactive stream tracer tests with tracer recordings in the streambed and in the stream channel. Common in-stream measurements of such reactive tracers cannot localize where the processing primarily takes place, whereas isolated vertical depth profiles of solutes within the hyporheic zone are usually not representative of the entire stream. We present results of a tracer test where we injected the conservative tracer bromide together with the reactive tracer resazurin into a third-order stream and combined the recording of in-stream breakthrough curves with multidepth sampling of the hyporheic zone at several locations. The transformation of resazurin was used as an indicator of metabolism, and high-reactivity zones were identified from depth profiles. The results from our subsurface analysis indicate that the potential for tracer transformation (i.e., the reaction rate constant) varied with depth in the hyporheic zone. This highlights the importance of the benthic biolayer, which we found to be on average 2 cm thick in this study, ranging from one third to one half of the full depth of the hyporheic zone. The reach-scale approach integrated the effects of processes along the reach length, isolating hyporheic processes relevant for whole-stream chemistry and estimating effective reaction rates.

Comparison of denitrification activity measurements in groundwater using cores and natural-gradient tracer tests

USGS Publications Warehouse

Smith, R.L.; Garabedian, S.P.; Brooks, M.H.

1996-01-01

The transport of many solutes in groundwater is dependent upon the relative rates of physical flow and microbial metabolism. Quantifying rates of microbial processes under subsurface conditions is difficult and is most commonly approximated using laboratory studies with aquifer materials. In this study, we measured in situ rates of denitrification in a nitrate- contaminated aquifer using small-scale, natural-gradient tracer tests and compared the results with rates obtained from laboratory incubations with aquifer core material. Activity was measured using the acetylene block technique. For the tracer tests, co-injection of acetylene and bromide into the aquifer produced a 30 ??M increase in nitrous oxide after 10 m of transport (23-30 days). An advection-dispersion transport model was modified to include an acetylene-dependent nitrous oxide production term and used to simulate the tracer breakthrough curves. The model required a 4-day lag period and a relatively low sensitivity to acetylene to match the narrow nitrous oxide breakthrough curves. Estimates of in situ denitrification rates were 0.60 and 1.51 nmol of N2O produced cm-3 aquifer day-1 for two successive tests. Aquifer core material collected from the tracer test site and incubated as mixed slurries in flasks and as intact cores yielded rates that were 1.2-26 times higher than the tracer test rate estimates. Results with the coring-dependent techniques were variable and subject to the small- scale heterogeneity within the aquifer, while the tracer tests integrated the heterogeneity along a flow path, giving a rate estimate that is more applicable to transport at the scale of the aquifer.

Monitoring TCE Degradation by In-situ Bioremediation in TCE-Contaminated site

NASA Astrophysics Data System (ADS)

Han, K.; Hong, U.; Ahn, G.; Jiang, H.; Yoo, H.; Park, S.; Kim, N.; Ahn, H.; Kwon, S.; Kim, Y.

2012-12-01

Trichloroethylene (TCE) is a long-term common groundwater pollutant because the compound with high density is slowly released into groundwater. Physical and chemical remediation processes have been used to clean-up the contaminant, but novel remediation technology is required to overcome a low efficiency of the traditional treatment process. Many researchers focused on biological process using an anaerobic TCE degrading culture, but it still needs to evaluate whether the process can be applied into field scale under aerobic condition. Therefore, in this work we investigated two different tests (i.e., biostimulation and bioaugmentation) of biological remediation through the Well-to-Well test (injection well to extraction well) in TCE-contaminated site. Also solutions (Electron donor & acceptor, tracer) were injected into the aquifer using a liquid coupled with nitrogen gas sparging. In biostimulation, we use 3 phases to monitoring biological remediation. Phase 1: we inject formate solution to get electron donor hydrogen (hydrogen can be generated from fermentation of formate). We also inject bromide as tracer. Phase 2: we made injection solution by formate, bromide and sulfate. The reason why we inject sulfate is that as a kind of electron accepter, sulfate reduction process is helpful to create anaerobic condition. Phase 3: we inject mixed solution made by formate, sulfate, fumarate, and bromide. The degradation of fumarate has the same mechanism and condition with TCE degradation, so we added fumarate to make sure that if the anaerobic TCE degradation by indigenous microorganisms started up (Because low TCE concentration by gas sparging). In the bioaugmentation test, we inject the Evanite culture (containing dehalococcoides spp) and TCE degradation to c-DCE, VC, ETH was monitored. We are evaluating the transport of the Evanite culture in the field by measuring TCE and VC reductases.

Hydrogeological characterization of a bank filtration experiment site at the Rio Grande, El Paso, Texas, USA

NASA Astrophysics Data System (ADS)

Langford, R.; Schulze-Makuch, D.; Pillai, S.; Abdel-Fattah, A.; Widmer, K.

2003-04-01

An experiment site was constructed along an artificial channel of the Rio Grande in El Paso, Texas. The experiment was funded by the EPA and is designed to measure the effectiveness of bank filtration in an arid environment. Regionally, the experiment is important because of the hundreds of thousands of people drinking water from shallow wells drilled in close proximity to septic systems. A pumping well was drilled 17 meters from the stream bank and screened from 3.5 to 8 m depth. A cruciform array of observation wells with several multilevel completions allows detection of downstream and vertical movement of water as well as flow from the stream to the well. All of the wells were continuously cored during drilling. Analysis of the cores reveals that the site consists of two stacked channels filled with sand deposited from the meandering Rio Grande. A grid of ground-penetrating radar lines provided three-dimensional coverage between wells and showed bedding to 6.5 m depth. Constant head hydraulic conductivities show that the aquifer consists of two more permeable units separated by the less permeable upper fill of the lower channel complex, with vertical hydraulic conductivities of (1x10-6 to 2x10-6 m/s?). The intervals above and below this interval have the highest vertical conductivities (up to 3.5x10-5 m/s). A multiple pumping and tracer test was conducted using the cruciform array of the field site that consisted of a pumping well, 16 observation wells, and a stream sampling point. The average hydraulic conductivity of the geological media at the field site was about 2 x 10-3 m/s based on pumping test analysis. However, the type curve responses revealed significant heterogeneity of hydraulic conductivity throughout the field site. For the tracer test, bromide and microspheres were used as tracers. Microspheres were used to mimic the behavior of Giardia and Cryptosporidium. The tracers (bromide and microspheres of different sizes and colors) were injected in one observation wells screened into the riverbank, one observation wells screened into the geological medium at the field site, and into one piezometer pushed into the stream sediments within the stream. The bromide recovery in the pumping well and in the deeper observation wells showed an early and a late peak with a long tail indicating the possibility that the geological medium at the field site behaves like a double-porosity medium allowing the tracer to move relatively quickly through the higher conductivity units while being significantly retarded in the low hydraulic conductivity units. The analysis of the microspheres in the laboratory, which is not yet complete, will shed more light on the transport behavior of pathogens at the field site.

Simultaneous Analyses and Applications of Multiple Fluorobenzoate and Halide Tracers in Hydrologic Studies

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

Hu, Q; Moran, J E

2004-01-22

An analytical method that employs ion chromatography has been developed to more fully exploit the use of fluorobenzoic acids (FBAs) and halides as hydrologic tracers. In a single run, this reliable, sensitive, and robust method can simultaneously separate and quantify halides (fluoride, chloride, bromide, and iodide) and up to seven FBAs from other common groundwater constituents (e.g., nitrate and sulfate). The usefulness of this ion chromatographic (IC) analytical method is demonstrated in both field and laboratory tracer experiments. Field experiments in unsaturated tuff featuring fractures or a fault show that this efficient and cost-effective method helps achieve the objectives ofmore » tracer studies that use multiple FBAs and/or diffusivity tracers (simultaneous use of one or more FBA and halide). The field study examines the hydrologic response of fractures and the matrix to different flow rates and the contribution of matrix diffusion in chemical transport. Laboratory tracer experiments with eight geologic media from across the United States--mostly from Department of Energy facilities where groundwater contamination is prevalent and where subsurface characterization employing tracers has been ongoing or is in need--reveal several insights about tracer transport behavior: (1) Bromide and FBAs are not always transported conservatively. (2) The delayed transport of these anionic tracers is likely related to geologic media characteristics, such as organic matter, pH, iron oxide content, and clay mineralogy. (3) Any use of iodine as a hydrologic tracer should take into account the different sorption behaviors of iodide and iodate and the possible conversion of iodine's initial chemical form. (4) The transport behavior of potential FBA and halide tracers under relevant geochemical conditions should be evaluated before beginning ambitious, large-scale field tracer experiments.« less

Estimation of αL, velocity, Kd, and confidence limits from tracer injection data

USGS Publications Warehouse

Broermann, James; Bassett, R.L.; Weeks, Edwin P.; Borgstrom, Mark

1997-01-01

Bromide and boron were used as tracers during an injection experiment conducted at an artificial recharge facility near Stanton, Texas. The Ogallala aquifer at the Stanton site represents a heterogeneous alluvial environment and provides the opportunity to report scale dependent dispersivities at observation distances of 2 to 15 m in this setting. Values of longitudinal dispersivities are compared with other published values. Water samples were collected at selected depths both from piezometers and from fully screened observation wells at radii of 2, 5, 10 and 15 m. An exact analytical solution is used to simulate the concentration breakthrough curves and estimate longitudinal dispersivities and velocity parameters. Greater confidence can be placed on these data because the estimated parameters are error bounded using the bootstrap method. The non-conservative behavior of boron transport in clay rich sections of the aquifer were quantified with distribution coefficients by using bromide as a conservative reference tracer.

Application of Tracer-Injection Techniques to Demonstrate Surface-Water and Ground-Water Interactions Between an Alpine Stream and the North Star Mine, Upper Animas River Watershed, Southwestern Colorado

USGS Publications Warehouse

Wright, Winfield G.; Moore, Bryan

2003-01-01

Tracer-injection studies were done in Belcher Gulch in the upper Animas River watershed, southwestern Colorado, to determine whether the alpine stream infiltrates into underground mine workings of the North Star Mine and other nearby mines in the area. The tracer-injection studies were designed to determine if and where along Belcher Gulch the stream infiltrates into the mine. Four separate tracer-injec-tion tests were done using lithium bromide (LiBr), optical brightener dye, and sodium chloride (NaCl) as tracer solu-tions. Two of the tracers (LiBr and dye) were injected con-tinuously for 24 hours, one of the NaCl tracers was injected continuously for 12 hours, and one of the NaCl tracers was injected over a period of 1 hour. Concentration increases of tracer constituents were detected in water discharging from the North Star Mine, substantiating a surface-water and ground-water connection between Belcher Gulch and the North Star Mine. Different timing and magnitude of tracer breakthroughs indicated multiple flow paths with different residence times from the stream to the mine. The Pittsburgh and Sultan Mines were thought to physically connect to the North Star Mine, but tracer breakthroughs were inconclusive in water from these mines. From the tracer-injection tests and synoptic measure-ments of streamflow discharge, a conceptual model was devel-oped for surface-water and ground-water interactions between Belcher Gulch and the North Star Mine. This information, combined with previous surface geophysical surveys indicat-ing the presence of subsurface voids, may assist with decision-making process for preventing infiltration and for the remedia-tion of mine drainage from these mines.

NATURAL GRADIENT EXPERIMENT ON SOLUTE TRANSPORT IN A SAND AQUIFER. 2. SPATIAL MOMENTS AND THE ADVECTION AND DISPERSION OF NONREACTIVE TRACERS

EPA Science Inventory

The three-dimensional movement of a tracer plume containing bromide and chloride is investigated using the data base from a large-scale natural gradient field experiment on groundwater solute transport. The analysis focuses on the zeroth-, first-, and second-order spatial moments...

THE HYDRAULIC CHARACTERISTICS AND GEOCHEMISTRY OF HYPORHEIC AND PARAFLUVIAL ZONES IN ARCTIC TUNDRA STREAMS, NORTH SLOPE, ALASKA

EPA Science Inventory

Sodium bromide and Rhodamine WT were used as conservative tracers to examine the hydrologic characteristics of seven tundra streams in Arctic Alaska, during the summers of 1994-1996. Continuous tracer additions were conducted in seven rivers ranging from 1st to 5th order with sam...

Analysis of a Multi-Well Tracer Test at a Bank Filtration Site in an Arid Environment of El Paso, Texas

NASA Astrophysics Data System (ADS)

Abdel-Fattah, A. N.; Langford, R.; Schulze-Makuch, D.; Sheng, Z.

2005-12-01

River bank filtered water is an important component of the drinking water production in many areas of the world. In riverbank filtration, the removal of pathogens is an important task for the production of good quality drinking water. The hydrogeological factors and spatial changes in the water's microbiology during the transport from the river to the aquifer have important implications on the quality of the produced water. The goal of this study was to investigate riverbank infiltration effectiveness in arid environments such as that of El Paso, Texas. The hydrostratigraphic units and hydrogeologic conditions were characterized with lithologic samples obtained from all boreholes collected during the construction of twelve observation wells and one production well in the site, which were constructed near the artificial stream to provide geologic and hydrologic information. The shallow aquifer is composed of three unites: high hydraulic conductivity layers on the top and bottom, and low conductivity layer in the middle. In this study advective transport of microspheres was compared with a conservative tracer such as bromide. Bromide was injected into an observation well at the channel margin. Simultaneously, 1, 6 and 10 micron-diameter fluorescent microspheres equivalent to Giardia, Cryptosporidium, and bacteria sizes were injected into the stream bottom and two observation wells to assess the suitability of microspheres as abiotic analogs in future investigations involving the physical aspects of bacteria and protozoa transport behavior. The 17.8 day-tracer test provided valuable results that are relevant to the transport of pathogens through the subsurface under riverbank filtration conditions. The 1 micron-size microspheres were abundant in the pumping and observation wells and showed multiple peaks similar to the bromide results. Microspheres from the three injection sites had distinctly different transport paths and rates. The 6 and 10 micron-size microspheres were observed in low to almost zero concentrations. The very low detection of larger sized microspheres indicates a potential attenuation of Cryptosporidium and Giardia-size microspheres under riverbank filtration conditions.

Evaluation of single- and dual-porosity models for reproducing the release of external and internal tracers from heterogeneous waste-rock piles.

PubMed

Blackmore, S; Pedretti, D; Mayer, K U; Smith, L; Beckie, R D

2018-05-30

Accurate predictions of solute release from waste-rock piles (WRPs) are paramount for decision making in mining-related environmental processes. Tracers provide information that can be used to estimate effective transport parameters and understand mechanisms controlling the hydraulic and geochemical behavior of WRPs. It is shown that internal tracers (i.e. initially present) together with external (i.e. applied) tracers provide complementary and quantitative information to identify transport mechanisms. The analysis focuses on two experimental WRPs, Piles 4 and Pile 5 at the Antamina Mine site (Peru), where both an internal chloride tracer and externally applied bromide tracer were monitored in discharge over three years. The results suggest that external tracers provide insight into transport associated with relatively fast flow regions that are activated during higher-rate recharge events. In contrast, internal tracers provide insight into mechanisms controlling solutes release from lower-permeability zones within the piles. Rate-limited diffusive processes, which can be mimicked by nonlocal mass-transfer models, affect both internal and external tracers. The sensitivity of the mass-transfer parameters to heterogeneity is higher for external tracers than for internal tracers, as indicated by the different mean residence times characterizing the flow paths associated with each tracer. The joint use of internal and external tracers provides a more comprehensive understanding of the transport mechanisms in WRPs. In particular, the tracer tests support the notion that a multi-porosity conceptualization of WRPs is more adequate for capturing key mechanisms than a dual-porosity conceptualization. Copyright © 2018 Elsevier B.V. All rights reserved.

pH dependence and unsuitability of fluorescein dye as a tracer for pesticide mobility studies in acid soil

Treesearch

Chris Peterson

2009-01-01

The mobility of fluorescein and bromide used as tracers in packed soil columns was investigated.Five different soils were used in two application methods: soil surface application and soil incorporation, both of which simulate accepted methods of soil application of termiticides to prevent structural infestation. The...

Body water compartments during bed rest: Evaluation of analytical methods

NASA Technical Reports Server (NTRS)

Young, H. L.; Juhos, L.; Castle, B. L.; Yusken, J.; Greenleaf, J. E.

1973-01-01

Nine healthy young men were studied to determine the reproducibility and interchangeability of the use of radio-iodinated human serum albumin and Evans Blue dye for estimating plasma volume, sodium bromide for extracellular fluid volume, and deuterium oxide for total body water volume. All subjects were tested in a semibasal condition and allowed to rest for at least 30 min. after arriving at the laboratory. The results indicate that there was uniform distribution of I131 and Evans Blue dye 10 min. after injection and of NaBr and D2O 3 hours after oral ingestion; the buildup of residual tracer did not interfere appreciably with the measurement of either or Evans Blue spaces when they are administered at equal intervals, and the buildup of background tracer after ingestion of NaBr and D2O once per week for three consecutive weeks did not affect the accuracy of the measurement. It was found that I131 and Evans Blue may be used interchangeably for estimating plasma volume; for estimating bromide and D2O spaces, one 3-hour equilibrium blood sample gives results similar to the extrapolation of multiple samples.

Fate and Transport of Bacteriophage (MS2 and PRD1) During Field-Scale Infiltration at a Research Site in Los Angeles County, CA

NASA Astrophysics Data System (ADS)

Anders, R.; Chrysikopoulos, C. V.

2003-12-01

As the use of tertiary-treated municipal wastewater (recycled water) for replenishment purposes continues to increase, provisions are being established to protect ground-water resources by ensuring that adequate soil-retention time and distance requirements are met for pathogen removal. However, many of the factors controlling virus fate and transport (e.g. hydraulic conditions, ground-water chemistry, and sediment mineralogy) are interrelated and poorly understood. Therefore, conducting field-scale experiments using surrogates for human enteric viruses at an actual recharge basin that uses recycled water may represent the best approach for establishing adequate setback requirements. Three field-scale infiltration experiments were conducted at such a basin using bacterial viruses (bacteriophage) MS2 and PRD1 as surrogates for human viruses, bromide as a conservative tracer, and recycled water. The specific research site consists of a test basin constructed adjacent to a large recharge facility (spreading grounds) located in the Montebello Forebay of Los Angeles County, California. The soil beneath the test basin is predominantly medium to coarse, moderately sorted, grayish-brown sand. The first experiment was conducted over a 2-day period to determine the feasibility of conducting field-scale infiltration experiments using recycled water seeded with high concentrations of bacteriophage and bromide as tracers. Based on the results of the first experiment, a second experiment was completed when similar hydraulic conditions existed at the test basin. The third infiltration experiment was conducted to confirm the results obtained from the second experiment. Data were obtained for samples collected during the second and third field-scale infiltration experiments from the test basin itself and from depths of 0.3, 0.6, 1.0, 1.5, 3.0, and 7.6 m below the bottom of the test basin. These field-scale tracer experiments indicate bacteriophage are attenuated by removal and (or) inactivation during subsurface transport. To simulate the transport and fate of viruses during infiltration, a nonlinear least-squares regression program was used to fit a one-dimensional virus transport model to the experimental data. The model simulates virus transport in homogeneous, saturated porous media with first-order adsorption (or filtration) and inactivation. Furthermore, the model obtains a semi-analytical solution for the special case of a broad pulse and time-dependent source concentration using the principle of superposition. The fitted parameters include the clogging and declogging rate constants and the inactivation constants of suspended and adsorbed viruses. Preliminary results show a reasonable match of the first arrival of bacteriophage and bromide.

B-10 enriched boric acid, bromide, and heat as tracers of recycled groundwater flow near managed aquifer recharge operations

NASA Astrophysics Data System (ADS)

Clark, J. F.; Becker, T.; Johnson, T. A.

2013-12-01

Recycling wastewater for potable and nonpotable use by artificially recharging aquifers is a decades-old but increasingly popular practice. Natural attenuation processes in the subsurface, known as soil aquifer treatment (SAT), purify recycled water during recharge and subsequent groundwater flow. Travel time criteria are often used to regulate managed aquifer recharge (MAR) operations. California state draft regulations currently gives preference to groundwater tracers to quantify underground residence time, with a target retention time of >6 months from infiltration to drinking water extraction for surface spreading projects using tertiary treated wastewater (less time may be possible if full advanced treated water is utilized). In the past sulfur hexafluoride, a very strong greenhouse gas, has been the principle deliberate tracer for this work. However, its emission has recently become regulated in California and new tracers are needed. Here, two prospective tracers are evaluated: boron-10 (B-10), the least abundant boron isotope, and heat (with recharging water naturally warmed at the sewage treatment plants and in surface-spreading basins). An additional deliberate tracer, bromide (Br), which is a well-studied conservative tracer, was released as a control. Tracer injection occurred at the San Gabriel Spreading Grounds research test basin in Los Angeles County, CA, USA. The basin was constructed and characterized by the US Geological Survey in the mid-1990s. Recycled wastewater was piped directly to this basin at a known rate (about 1.5 m3/day). Down gradient from the test basin are nine high quality monitoring wells in a line that extends from the center of the basin to 150 m down gradient. All of the wells were equipped with temperature loggers that recorded groundwater temperatures every hour with an accuracy of one thousandth of a degree. The pre-experiment expected arrival times ranged from less than one day to six months. Arrival of Br was always coincident or preceded the B-10 arrival, reflecting retardation of B-10 presumably due to exchange with clay surfaces. B-10/Br travel time ratios determined from the center of mass range from 1 to 1.4. Temperature time series were developed from data loggers. The 1.5° C diurnal temperature variation observed in the spreading pond was only apparent at one well that is screen about 3 m below the pond bottom. At the other wells, we observed temperature increases over a period of days to weeks. Basic analysis of temperature profiles yields a reliable estimate of the underground residence time; heat flow travel times are in good agreement with those derived from the geochemical tracers.

A DNA Tracer System for Hydrological Environment Investigations.

PubMed

Liao, Renkuan; Yang, Peiling; Wu, Wenyong; Luo, Dan; Yang, Dayong

2018-02-20

To monitor and manage hydrological pollution effectively, tracing sources of pollutants is of great importance and also is in urgent need. A variety of tracers have been developed such as isotopes, silica, bromide, and dyes; however, practical limitations of these traditional tracers still exist such as lack of multiplexed, multipoint tracing and interference of background noise. To overcome these limitations, a new tracing system based on DNA nanomaterials, namely DNA tracer, has already been developed. DNA tracers possess remarkable advantages including sufficient species, specificity, environmental friendly, stable migration, and high sensitivity as well as allowing for multipoints tracing. In this review article, we introduce the molecular design, synthesis, protection and signal readout strategies of DNA tracers, compare the advantages and disadvantages of DNA tracer with traditional tracers, and summarize the-state-of-art applications in hydrological environment investigations. In the end, we provide our perspective on the future development of DNA tracers.

Nitrate turnover in a peat soil under drained and rewetted conditions: results from a [(15)N]nitrate-bromide double-tracer study.

PubMed

Russow, Rolf; Tauchnitz, Nadine; Spott, Oliver; Mothes, Sibylle; Bernsdorf, Sabine; Meissner, Ralph

2013-01-01

Under natural conditions, peatlands are generally nitrate-limited. However, recent concerns about an additional N input into peatlands by atmospheric N deposition have highlighted the risk of an increased denitrification activity and hence the likelihood of a rise of emissions of the greenhouse gas nitrous oxide. Therefore, the aim of the present study was to investigate the turnover of added nitrate in a drained and a rewetted peatland using a [(15)N]nitrate-bromide double-tracer method. The double-tracer method allows a separation between physical effects (dilution, dispersion and dislocation) and microbial and chemical nitrate transformation by comparing with the conservative Br(-) tracer. In the drained peat site, low NO3(-) consumption rates have been observed. In contrast, NO3(-) consumption at the rewetted peat site rises rapidly to about 100% within 4 days after tracer application. Concomitantly, the (15)N abundances of nitrite and ammonium in soil water increased and lead to the conclusion that, besides commonly known NO3(-) reduction to nitrite (i.e. denitrification), a dissimilatory nitrate reduction to ammonium has simultaneously taken place. The present study reveals that increasing NO3(-) inputs into rewetted peatlands via atmospheric deposition results in a rapid NO3(-) consumption, which could lead to an increase in N2O emissions into the atmosphere.

A novel explicit approach to model bromide and pesticide transport in connected soil structures

NASA Astrophysics Data System (ADS)

Klaus, J.; Zehe, E.

2011-07-01

The present study tests whether an explicit treatment of worm burrows and tile drains as connected structures is feasible for simulating water flow, bromide and pesticide transport in structured heterogeneous soils at hillslope scale. The essence is to represent worm burrows as morphologically connected paths of low flow resistance in a hillslope model. A recent Monte Carlo study (Klaus and Zehe, 2010, Hydrological Processes, 24, p. 1595-1609) revealed that this approach allowed successful reproduction of tile drain event discharge recorded during an irrigation experiment at a tile drained field site. However, several "hillslope architectures" that were all consistent with the available extensive data base allowed a good reproduction of tile drain flow response. Our second objective was thus to find out whether this "equifinality" in spatial model setups may be reduced when including bromide tracer data in the model falsification process. We thus simulated transport of bromide for the 13 spatial model setups that performed best with respect to reproduce tile drain event discharge, without any further calibration. All model setups allowed a very good prediction of the temporal dynamics of cumulated bromide leaching into the tile drain, while only four of them matched the accumulated water balance and accumulated bromide loss into the tile drain. The number of behavioural model architectures could thus be reduced to four. One of those setups was used for simulating transport of Isoproturon, using different parameter combinations to characterise adsorption according to the Footprint data base. Simulations could, however, only reproduce the observed leaching behaviour, when we allowed for retardation coefficients that were very close to one.

A novel explicit approach to model bromide and pesticide transport in soils containing macropores

NASA Astrophysics Data System (ADS)

Klaus, J.; Zehe, E.

2011-01-01

The present study tests whether an explicit treatment of worm burrows is feasible for simulating water flow, bromide and pesticide transport in structured heterogeneous soils. The essence is to represent worm burrows as morphologically connected paths of low flow resistance in the spatially highly resolved model domain. A recent Monte Carlo study (Klaus and Zehe, 2010) revealed that this approach allowed successful reproduction of tile drain event discharge recorded during an irrigation experiment at a tile drained field site. However, several "hillslope architectures" that were all consistent with the available extensive data base allowed a good reproduction of tile drain flow response. Our second objective was thus to find out whether this "equifinality" in spatial model setups may be reduced when including bromide tracer data in the model falsification process. We thus simulated transport of bromide and Isoproturon (IPU) for the 13 spatial model setups, which performed best with respect to reproduce tile drain event discharge, without any further calibration. All model setups allowed a very good prediction of the temporal dynamics of cumulated bromide leaching into the tile drain, while only four of them matched the accumulated water balance and accumulated bromide loss into the tile drain. The number of behavioural model architectures could thus be reduced to four. One of those setups was used for simulating transport of IPU, using different parameter combinations to characterise adsorption according to the Footprint data base. Simulations could, however, only reproduce the observed leaching behaviour, when we allowed for retardation coefficients that were very close to one.

Comparative mobility of sulfonamides and bromide tracer in three soils

USGS Publications Warehouse

Kurwadkar, S.T.; Adams, C.D.; Meyer, M.T.; Kolpin, D.W.

2011-01-01

In animal agriculture, sulfonamides are one of the routinely used groups of antimicrobials for therapeutic and sub-therapeutic purposes. It is observed that, the animals when administered the antimicrobials, often do not completely metabolize them; and excrete the partially metabolized forms into the environment. Due to the continued use of antimicrobials and disposal of untreated waste, widespread occurrence of partially metabolized antimicrobials in aquatic and terrestrial environments has been reported in various scientific journals. In this research, the mobility of two sulfonamides - sulfamethazine (SMN), sulfathiazole (STZ) and a conservative bromide tracer was investigated in three soils collected from regions in the United States with large number of concentrated animal-feed operations. Results of a series of column studies indicate that the mobility of these two sulfonamides was dependent on pH, soil charge density, and contact time. At low pH and high charge density, substantial retention of sulfonamides was observed in all three soils investigated, due to the increased fraction of cationic and neutral forms of the sulfonamides. Conversely, enhanced mobility was observed at high pH, where the sulfonamides are predominantly in the anionic form. The results indicate that when both SMN and STZ are predominantly in anionic forms, their mobility approximates the mobility of a conservative bromide tracer. This observation is consistent for the mobility of both SMN and STZ individually, and also in the presence of several other antimicrobials in all three soils investigated. Higher contact time indicates lower mobility due to increased interaction with soil material. ?? 2011.

Revisiting the cape cod bacteria injection experiment using a stochastic modeling approach

USGS Publications Warehouse

Maxwell, R.M.; Welty, C.; Harvey, R.W.

2007-01-01

Bromide and resting-cell bacteria tracer tests conducted in a sandy aquifer at the U.S. Geological Survey Cape Cod site in 1987 were reinterpreted using a three-dimensional stochastic approach. Bacteria transport was coupled to colloid filtration theory through functional dependence of local-scale colloid transport parameters upon hydraulic conductivity and seepage velocity in a stochastic advection - dispersion/attachment - detachment model. Geostatistical information on the hydraulic conductivity (K) field that was unavailable at the time of the original test was utilized as input. Using geostatistical parameters, a groundwater flow and particle-tracking model of conservative solute transport was calibrated to the bromide-tracer breakthrough data. An optimization routine was employed over 100 realizations to adjust the mean and variance ofthe natural-logarithm of hydraulic conductivity (InK) field to achieve best fit of a simulated, average bromide breakthrough curve. A stochastic particle-tracking model for the bacteria was run without adjustments to the local-scale colloid transport parameters. Good predictions of mean bacteria breakthrough were achieved using several approaches for modeling components of the system. Simulations incorporating the recent Tufenkji and Elimelech (Environ. Sci. Technol. 2004, 38, 529-536) correlation equation for estimating single collector efficiency were compared to those using the older Rajagopalan and Tien (AIChE J. 1976, 22, 523-533) model. Both appeared to work equally well at predicting mean bacteria breakthrough using a constant mean bacteria diameter for this set of field conditions. Simulations using a distribution of bacterial cell diameters available from original field notes yielded a slight improvement in the model and data agreement compared to simulations using an average bacterial diameter. The stochastic approach based on estimates of local-scale parameters for the bacteria-transport process reasonably captured the mean bacteria transport behavior and calculated an envelope of uncertainty that bracketed the observations in most simulation cases. ?? 2007 American Chemical Society.

Effect of different transport observations on inverse modeling results: case study of a long-term groundwater tracer test monitored at high resolution

NASA Astrophysics Data System (ADS)

Rasa, Ehsan; Foglia, Laura; Mackay, Douglas M.; Scow, Kate M.

2013-11-01

Conservative tracer experiments can provide information useful for characterizing various subsurface transport properties. This study examines the effectiveness of three different types of transport observations for sensitivity analysis and parameter estimation of a three-dimensional site-specific groundwater flow and transport model: conservative tracer breakthrough curves (BTCs), first temporal moments of BTCs ( m 1), and tracer cumulative mass discharge ( M d) through control planes combined with hydraulic head observations ( h). High-resolution data obtained from a 410-day controlled field experiment at Vandenberg Air Force Base, California (USA), have been used. In this experiment, bromide was injected to create two adjacent plumes monitored at six different transects (perpendicular to groundwater flow) with a total of 162 monitoring wells. A total of 133 different observations of transient hydraulic head, 1,158 of BTC concentration, 23 of first moment, and 36 of mass discharge were used for sensitivity analysis and parameter estimation of nine flow and transport parameters. The importance of each group of transport observations in estimating these parameters was evaluated using sensitivity analysis, and five out of nine parameters were calibrated against these data. Results showed the advantages of using temporal moment of conservative tracer BTCs and mass discharge as observations for inverse modeling.

Use of carboxylated microspheres to assess transport potential of Cryptosporidium parvum oocysts at the Russian River water supply facility, Sonoma County, California

USGS Publications Warehouse

Metge, D.W.; Harvey, R.W.; Anders, R.; Rosenberry, D.O.; Seymour, D.; Jasperse, James

2007-01-01

Carboxylated microspheres were employed as surrogates to assess the transport potential of Cryptosporidium parvumoocysts during forced- and natural-gradient tests conducted in July and October 2004. The tests involved poorly-sorted, near-surface sediments where groundwater is pumped from an alluvial aquifer underlying the Russian River, Sonoma County, CA. In an off channel infiltration basin and within the river, a mixture (2-, 3-, and 5- ??m diameters) of fluorescently-labeled carboxylated microspheres and bromide tracers were used in two injection and recovery test to assess sediment removal efficiency for the microspheres. Bottom sediments varied considerably in their filtration efficiency for Cryptosporidium.

Rejuvenating the Largest Treatment Wetland in Florida: Tracer Moment and Model Analysis of Wetland Hydraulic Performance

NASA Astrophysics Data System (ADS)

White, J. R.; Wang, H.; Jawitz, J. W.; Sees, M. D.

2004-12-01

The Orlando Easterly Wetland (OEW), the largest municipal treatment wetland in Florida, began operation in 1987 mainly for reducing nutrient loads in tertiary treated domestic wastewater produced by the city of Orlando. After more than ten years of operation, a decrease in total P removal effectiveness has occurred since 1999, even though the effluent concentration of the wetland has remained below the permitted limit of 0.2 mg/L,. Hydraulic inefficiency in the wetland, especially in the front-end cells of the north flow train, was identified as a primary cause of the reduced treatment effectiveness. In order to improve the hydraulic performance of the OEW and maintain its efficient phosphorus treatment, a rejuvenation program (including muck removal followed by re-vegetation) was initiated on the front-end cells of the north flow train in 2002. The effectiveness of this activity for the improvement of hydraulic performance was evaluated with a tracer test and subsequent moment and model analyses for the tracer resident time distribution (RTDs). Results were compared to similar tracer tests conducted prior to rejuvenation activities. The models included one-path tank-in-series (TIS), two-path TIS, one-dimensional transport with inflow and storage (OTIS), plug flow with dispersion (PFD), and plug flow with fractional dispersion (PFFD). The hydraulic performance was characterized by both wetland hydraulic efficiency and the spreading of tracers. The results demonstrated that the rejuvenation considerably improved the hydraulic performance in the restored area. Also presented is a comparison of the wetland response between both bromide and lithium tracers, and the determination of the complete moments of residence time distributions (RTD) in cell-network wetlands.

Characterization of reactive tracers for C-wells field experiments 1: Electrostatic sorption mechanism, lithium

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

Fuentes, H.R.; Polzer, W.L.; Essington, E.H.

1989-11-01

Lithium (Li{sup +}) was introduced as lithium bromide (LiBr), as a retarded tracer for experiments in the C-wells complex at Yucca Mountain, Nevada Test Site, Nevada. The objective was to evaluate the potential of lithium to sorb predominately by physical forces. lithium was selected as a candidate tracer on the basis of high solubility, good chemical and biological stability, and relatively low sorptivity; lack of bioaccumulation and exclusion as a priority pollutant in pertinent federal environmental regulations; good analytical detectability and low natural background concentrations; and a low cost Laboratory experiments were performed with suspensions of Prow Pass cuttings frommore » drill hole UE-25p{number_sign}1 at depths between 549 and 594 m in J-13 water at a pH of approximately 8 and in the temperature range of 25{degree}C to 45{degree}C. Batch equilibrium and kinetics experiments were performed; estimated thermodynamic constants, relative behavior between adsorption and desorption, and potentiometric studies provided information to infer the physical nature of lithium sorption.« less

DESIGN OF A MTBE REMEDIATION TECHNOLOGY EVALUATION

EPA Science Inventory

This study examines the intrinsic variability of dissolved MTBE concentrations in ground water during the course of a pilot-scale bioremedial technology trial in Port Hueneme, California. A pre-trial natural gradient tracer experiment using bromide was conducted in an anaerobic t...

The Impact of Biochar on Bioretention Nitrogen Removal and Hydrologic Performance

NASA Astrophysics Data System (ADS)

Tian, J.; Jin, J.; Chiu, P.; Guo, M.; Imhoff, P. T.

2016-12-01

Poor nitrate removal and substantial land occupation are two factors that limit the application of bioretention facilities. Biochar was evaluated in this study as an amendment of bioretention media to enhance nitrogen removal from runoff as well as improve hydrologic performance. Two pilot-scale bioretention cells (91 cm dia., 1.2 m deep) were constructed in parallel, and both contained 20 cm saturation zone with coarse sand, 76 cm vadose zone with treatment medium, and 5 cm of triple-shredded wood mulch from bottom to top. Treatment medium in the control cell was a mixture of 88% sand, 8% clay, and 4% sawdust by mass, while the biochar cell amended 4% commercial biochar pyrolyzed from Southern Yellow Pine at 550°. Both cells were instrumented with soil moisture sensors, soil potential sensors and temperature sensors. A field infiltration test was conducted in each cell using a tension disc infiltrometer directly on the treatment media to obtain soil hydraulic parameters, then three 24-36-hour tracer tests containing bromide and nitrate pollutant were conducted over a five-month period. Influent, effluent and pore water were continuously sampled for bromide and nitrogen analysis during these tests. In addition, hydrologic performance of the two cells under various conditions of rainfall recurrence interval and duration were simulated using HYDRUS-1D after verification with tracer test data. Results showed that the biochar cell reduced NO3-N concentrations by 30.6-84.7%, while the control cell only reduced NO3-N by -6-43.5%, depending on the storm. Biochar amendment slightly increased the average pH of the vadose zone from 6.3 to 7.3, decreased the average dissolve oxygen content by 43%, and decreased the average oxidation-reduction potential from 22 mV to -115 mV, which contributed to the enhanced nitrate removal. Biochar-amended medium increased saturated hydraulic conductivity by 1.5 times, and increased cell residence time and water retention by 12.6% and 15% respectively during the tracer tests. For a 1-yr interval and 24-hr duration storm simulation, the biochar-amended cell could reduce overflow by 78%, extend the delay of the peak flow by two times and decrease the peak outflow rate by 35%, compared to the control cell.

Use of Nitrogen-15-Enriched Escherichia coli as a Bacterial Tracer in Karst Aquifers.

PubMed

Ward, James W; Warden, John G; Bandy, Ashley M; Fryar, Alan E; Brion, Gail M; Macko, Stephen A; Romanek, Christopher S; Coyne, Mark S

2016-11-01

Karst aquifers are susceptible to contamination by microorganisms, but relatively few studies have used bacteria as tracers. We demonstrate the utility of Escherichia coli enriched in the stable isotope nitrogen-15 ( 15 N) as a novel bacterial tracer. Nonpathogenic E. coli from two springs in central Kentucky were grown on 15 N-enriched media. Survival of E. coli and persistence of the isotopic signal were assessed in two sets of laboratory experiments conducted with sterilized spring water in dark microcosms at 14 °C. First, isotopically labeled bacteria survived for 130 d at concentrations within one log unit of the average initial value, and there was no significant difference in δ 15 N values from Day 1 to Day 130. Second, water samples with E. coli were inoculated with either of two different species of protozoa (Tetrahymena pyriformis or Colpoda steinii). During 7 d, δ 15 N values increased in T. pyriformis while bacterial populations decreased. In a field test, following a 2.1-cm rainfall, 15 N-labeled E. coli, solutes (rhodamine WT dye and bromide), and latex microspheres were injected into a sinkhole approximately 530 m upgradient of a spring. Breakthrough of all tracers coincided, but microspheres were remobilized by subsequent storms, unlike other tracers. Enriched E. coli exhibited more tailing than solute tracers during the initial storm-flow recession. These results indicate that 15 N-enriched E. coli is a viable tracer of bacterial transport in karst aquifers, although predation may attenuate the isotopic signal in systems that are not rapidly flushed. © 2016, National Ground Water Association.

Evaluation of tracer tests completed in 1999 and 2000 on the upper Santa Clara River, Los Angeles and Ventura Counties, California

USGS Publications Warehouse

Cox, Marisa H.; Mendez, Gregory O.; Kratzer, Charles R.; Reichard, Eric G.

2003-01-01

The interaction of surface water and hyporheic water along the Santa Clara River in Los Angeles and Ventura Counties, California, was evaluated by conducting tracer tests and analyzing water-quality data under different flow conditions in October 1999 and May 2000. Tracer and water-quality samples were collected at multiple river and hyporheic sites as well as at the Los Angeles County Sanitation Districts Saugus and Valencia Water Reclamation Plants. These water reclamation plants provide the main source of base flow in the river. Rhodamine WT dye was injected into the river to determine river traveltimes and to indicate when Lagrangian water-quality sampling could be performed at each site. Sodium bromide was injected into the river at a constant rate at the water reclamation plants to evaluate the surface-water and shallow ground-water interactions in the hyporheic zone. In the upper reach of the study area, which extends 2.9 river miles downstream from the Saugus Water Reclamation Plant, traveltime was 3.2 hours during May 2000. In the lower reach, which extends 14.1 river miles downstream from the Valencia Water Reclamation Plant, traveltime was 9.6 hours during October 1999 and 7.1 hours during May 2000. The sodium bromide tracer was detected at both hyporheic locations sampled during October 1999, and at two of the three hyporheic locations sampled during May 2000. On the basis of Rhodamine dye tests, flow curves were constructed from the discharge measurements in the Valencia reach. Flow-curve results indicate net gains in flow throughout most, but not all, of the upper parts of the reach and net losses in flow at the lower part of the reach. Lagrangian water-quality sampling provides information on the changes in chemistry as the water flows downstream from the water reclamation plants. Along both reaches there is an increase in sulfate (40-60 mg/L in the Saugus reach and 160 mg/L in the Valencia reach) and a decrease in chloride (about 45 mg/L in the Saugus reach and about 10 mg/L in the Valencia reach). The increasing sulfate concentrations are consistent with discharge of higher sulfate ground water into the river. Along both reaches there is a trend of decreasing ammonia and slightly increasing nitrate concentrations. This trend is consistent with nitrification. Samples were also analyzed for numerous compounds associated with wastewater, but analysis focused on four indicators. Concentrations of wastewater indicators in the Santa Clara River were low and decreased downstream from the reclamation plants. There is general consistency between the chemical and tracer data collected from the hyporheic and the river-aquifer flow regime within a reach. The water quality at the hyporheic site in a gaining reach of the river resembled that of the local ground water and no wastewater indicators or injected tracers were observed; whereas, the water quality at the hyporheic sites in a losing reach of the river resembled the water quality of the river at the corresponding river site, and injected tracers were observed.

Evaluating Microbial Purification during Soil Treatment of Wastewater with Multicomponent Tracer and Surrogate Tests

USGS Publications Warehouse

Van Cuyk, S.; Siegrist, R.L.; Lowe, K.; Harvey, R.W.

2004-01-01

Soil treatment of wastewater has the potential to achieve high purification efficiency, yet the understanding and predictability of purification with respect to removal of viruses and other pathogens is limited. Research has been completed to quantify the removal of virus and bacteria through the use of microbial surrogates and conservative tracers during controlled experiments with three-dimensional pilot-scale soil treatment systems in the laboratory and during the testing of full-scale systems under field conditions. The surrogates and tracers employed included two viruses (MS-2 and PRID-1 bacteriophages), one bacterium (ice-nucleating active Pseudomonas), and one conservative tracer (bromide ion). Efforts have also been made to determine the relationship between viruses and fecal coliform bacteria in soil samples below the wastewater infiltrative surface, and the correlation between Escherichia coil concentrations measured in percolating soil solution as compared with those estimated from analyses of soil solids. The results suggest episodic breakthrough of virus and bacteria during soil treatment of wastewater and a 2 to 3 log (99-99.9%) removal of virus and near complete removal of fecal coliform bacteria during unsaturated flow through 60 to 90 cm of sandy medium. Results also suggest that the fate of fecal coliform bacteria may be indicative of that of viruses in soil media near the infiltrative surface receiving wastewater effluent. Concentrations of fecal coliform in percolating soil solution may be conservatively estimated from analysis of extracted soil solids.

Evaluation of bromide mass discharge in a sandy aquifer at Vandenberg AFB, CA

NASA Astrophysics Data System (ADS)

Mackay, D. M.; Rasa, E.; Einarson, M.; Kaiser, P.; Chakraborty, I.; Scow, K. M.

2009-12-01

Side-by-side experiments were conducted by UC Davis research team at a former fuel station at Vandenberg Air Force Base (AFB) to evaluate the rate of transformation of methyl tert-butyl ether (MTBE) to tert-butyl alcohol (TBA) impacted by ethanol and to investigate evidence of TBA degradation under sulfate reducing conditions. On one side we injected groundwater amended with ethanol and MTBE. In the other lane we injected groundwater amended with TBA. On both sides, injected ground water was spiked with bromide tracer to provide estimates of groundwater flow direction variations, flow velocity, dispersion, and mobile mass loss resulting from diffusive sequestration into aquitards. 162 monitoring wells were aligned into seven transects located downgradient of the injection wells. The mass discharge approach was used to evaluate the natural attenuation of the injected constituents. In this talk we will focus on calculations of mass discharge of the bromide tracer at each of the seven monitoring well transects. The amount of bromide mass discharged through each transect was calculated for any sampling time using field measurements of break through curves. Cumulative mass discharges were estimated and, by iteration based on mass balance, the flow properties of the aquifer were estimated. The calibration process resulted in subtle but quantitatively important changes in our assumptions regarding key physical properties of the aquifer (thickness, porosity) which could be only approximately estimated by standard methods (coring, CPT, etc.). On the basis of this calibration, a more robust approach was devised for evaluating the source and fate of TBA in the aquifer.

Gas-partitioning tracer test to qualify trapped gas during recharge

USGS Publications Warehouse

Heilweil, Victor M.; Kip, Solomon D.; Perkins, Kim S.; Ellett, Kevin M.

2004-01-01

Dissolved helium and bromide tracers were used to evaluate trapped gas during an infiltration pond experiment. Dissolved helium preferentially partitioned into trapped gas bubbles, or other pore air, because of its low solubility in water. This produced observed helium retardation factors of as much as 12 relative to bromide. Numerical simulations of helium breakthrough with both equilibrium and kinetically limited advection/dispersion/retardation did not match observed helium concentrations. However, better fits were obtained by including a decay term representing the diffusive loss of helium through interconnected, gas-filled pores. Calculations indicate that 7% to more than 26% of the porosity beneath the pond was filled with gas. Measurements of laboratory hydraulic properties indicate that a 10% decrease in saturation would reduce the hydraulic conductivity by at least one order of magnitude in the well-sorted sandstone, but less in the overlying soils. This is consistent with in situ measurements during the experiment, which show steeper hydraulic gradients in sandstone than in soil. Intrinsic permeability of the soil doubled during the first six months of the experiment, likely caused by a combination of dissolution and thermal contraction of trapped gas. Managers of artificial recharge basins may consider minimizing the amount of trapped gas by using wet, rather than dry, tilling to optimize infiltration rates, particularly in well-sorted porous media in which reintroduced trapped gas may cause substantial reductions in permeability. Trapped gas may also inhibit the amount of focused infiltration that occurs naturally during ephemeral flood events along washes and playas.

Gas-partitioning tracer test to quantify trapped gas during recharge

USGS Publications Warehouse

Heilweil, V.M.; Solomon, D.K.; Perkins, K.S.; Ellett, K.M.

2004-01-01

Dissolved helium and bromide tracers were used to evaluate trapped gas during an infiltration pond experiment. Dissolved helium preferentially partitioned into trapped gas bubbles, or other pore air, because of its low solubility in water. This produced observed helium retardation factors of as much as 12 relative to bromide. Numerical simulations of helium breakthrough with both equilibrium and kinetically limited advection/dispersion/retardation did not match observed helium concentrations. However, better fits were obtained by including a decay term representing the diffusive loss of helium through interconnected, gas-filled pores. Calculations indicate that 7% to more than 26% of the porosity beneath the pond was filled with gas. Measurements of laboratory hydraulic properties indicate that a 10% decrease in saturation would reduce the hydraulic conductivity by at least one order of magnitude in the well-sorted sandstone, but less in the overlying soils. This is consistent with in situ measurements during the experiment, which show steeper hydraulic gradients in sandstone than in soil. Intrinsic permeability of the soil doubled during the first six months of the experiment, likely caused by a combination of dissolution and thermal contraction of trapped gas. Managers of artificial recharge basins may consider minimizing the amount of trapped gas by using wet, rather than dry, tilling to optimize infiltration rates, particularly in well-sorted porous media in which reintroduced trapped gas may cause substantial reductions in permeability. Trapped gas may also inhibit the amount of focused infiltration that occurs naturally during ephemeral flood events along washes and playas.

Solute transport and storage mechanisms in wetlands of the Everglades, south Florida

USGS Publications Warehouse

Harvey, Judson W.; Saiers, James E.; Newlin, Jessica T.

2005-01-01

Solute transport and storage processes in wetlands play an important role in biogeochemical cycling and in wetland water quality functions. In the wetlands of the Everglades, there are few data or guidelines to characterize transport through the heterogeneous flow environment. Our goal was to conduct a tracer study to help quantify solute exchange between the relatively fast flowing water in the open part of the water column and much more slowly moving water in thick floating vegetation and in the pore water of the underlying peat. We performed a tracer experiment that consisted of a constant‐rate injection of a sodium bromide (NaBr) solution for 22 hours into a 3 m wide, open‐ended flume channel in Everglades National Park. Arrival of the bromide tracer was monitored at an array of surface water and subsurface samplers for 48 hours at a distance of 6.8 m downstream of the injection. A one‐dimensional transport model was used in combination with an optimization code to identify the values of transport parameters that best explained the tracer observations. Parameters included dimensions and mass transfer coefficients describing exchange with both short (hours) and longer (tens of hours) storage zones as well as the average rates of advection and longitudinal dispersion in the open part of the water column (referred to as the “main flow zone”). Comparison with a more detailed set of tracer measurements tested how well the model's storage zones approximated the average characteristics of tracer movement into and out of the layer of thick floating vegetation and the pore water in the underlying peat. The rate at which the relatively fast moving water in the open water column was exchanged with slowly moving water in the layer of floating vegetation and in sediment pore water amounted to 50 and 3% h−1, respectively. Storage processes decreased the depth‐averaged velocity of surface water by 50% relative to the water velocity in the open part of the water column. As a result, flow measurements made with other methods that only work in the open part of the water column (e.g., acoustic Doppler) would have overestimated the true depth‐averaged velocity by a factor of 2. We hypothesize that solute exchange and storage in zones of floating vegetation and peat pore water increase contact time of solutes with biogeochemically active surfaces in this heterogeneous wetland environment.

Imaging pathways in fractured rock using three-dimensional electrical resistivity tomography

USGS Publications Warehouse

Robinson, Judith; Slater, Lee; Johnson, Timothy B.; Shapiro, Allen M.; Tiedeman, Claire; Ntlargiannis, Dimitrios; Johnson, Carole D.; Day-Lewis, Frederick D.; Lacombe, Pierre; Imbrigiotta, Thomas; Lane, John W.

2016-01-01

Major challenges exist in delineating bedrock fracture zones because these cause abrupt changes in geological and hydrogeological properties over small distances. Borehole observations cannot sufficiently capture heterogeneity in these systems. Geophysical techniques offer the potential to image properties and processes in between boreholes. We used three-dimensional cross borehole electrical resistivity tomography (ERT) in a 9 m (diameter) × 15 m well field to capture high-resolution flow and transport processes in a fractured mudstone contaminated by chlorinated solvents, primarily trichloroethylene. Conductive (sodium bromide) and resistive (deionized water) injections were monitored in seven boreholes. Electrode arrays with isolation packers and fluid sampling ports were designed to enable acquisition of ERT measurements during pulsed tracer injections. Fracture zone locations and hydraulic pathways inferred from hydraulic head drawdown data were compared with electrical conductivity distributions from ERT measurements. Static ERT imaging has limited resolution to decipher individual fractures; however, these images showed alternating conductive and resistive zones, consistent with alternating laminated and massive mudstone units at the site. Tracer evolution and migration was clearly revealed in time-lapse ERT images and supported by in situ borehole vertical apparent conductivity profiles collected during the pulsed tracer test. While water samples provided important local information at the extraction borehole, ERT delineated tracer migration over spatial scales capturing the primary hydrogeological heterogeneity controlling flow and transport. The fate of these tracer injections at this scale could not have been quantified using borehole logging and/or borehole sampling methods alone.

Percolation and transport in a sandy soil under a natural hydraulic gradient

USGS Publications Warehouse

Green, Christopher T.; Stonestrom, David A.; Bekins, Barbara A.; Akstin, Katherine C.; Schulz, Marjorie S.

2005-01-01

Unsaturated flow and transport under a natural hydraulic gradient in a Mediterranean climate were investigated with a field tracer experiment combined with laboratory analyses and numerical modeling. Bromide was applied to the surface of a sandy soil during the dry season. During the subsequent rainy season, repeated sediment sampling tracked the movement of bromide through the profile. Analysis of data on moisture content, matric pressure, unsaturated hydraulic conductivity, bulk density, and soil texture and structure provides insights into parameterization and use of the advective‐dispersive modeling approach. Capturing the gross features of tracer and moisture movement with model simulations required an order‐of‐magnitude increase in laboratory‐measured hydraulic conductivity. Wetting curve characteristics better represented field results, calling into question the routine estimation of hydraulic characteristics based only on drying conditions. Measured increases in profile moisture exceeded cumulative precipitation in early winter, indicating that gains from dew drip can exceed losses from evapotranspiration during periods of heavy (“Tule”) fog. A single‐continuum advective‐dispersive modeling approach could not reproduce a peak of bromide that was retained near the soil surface for over 3 years. Modeling of this feature required slow exchange of solute at a transfer rate of 0.5–1 × 10−4 d−1 with an immobile volume approaching the residual moisture content.

Simulation of variable-density flow and transport of reactive and nonreactive solutes during a tracer test at Cape Cod, Massachusetts

USGS Publications Warehouse

Zhang, Hubao; Schwartz, Frank W.; Wood, Warren W.; Garabedian, S.P.; LeBlanc, D.R.

1998-01-01

A multispecies numerical code was developed to simulate flow and mass transport with kinetic adsorption in variable-density flow systems. The two-dimensional code simulated the transport of bromide (Br−), a nonreactive tracer, and lithium (Li+), a reactive tracer, in a large-scale tracer test performed in a sand-and-gravel aquifer at Cape Cod, Massachusetts. A two-fraction kinetic adsorption model was implemented to simulate the interaction of Li+ with the aquifer solids. Initial estimates for some of the transport parameters were obtained from a nonlinear least squares curve-fitting procedure, where the breakthrough curves from column experiments were matched with one-dimensional theoretical models. The numerical code successfully simulated the basic characteristics of the two plumes in the tracer test. At early times the centers of mass of Br− and Li+ sank because the two plumes were closely coupled to the density-driven velocity field. At later times the rate of downward movement in the Br− plume due to gravity slowed significantly because of dilution by dispersion. The downward movement of the Li+ plume was negligible because the two plumes moved in locally different velocity regimes, where Li+ transport was retarded relative to Br−. The maximum extent of downward transport of the Li+ plume was less than that of the Br− plume. This study also found that at early times the downward movement of a plume created by a three-dimensional source could be much more extensive than the case with a two-dimensional source having the same cross-sectional area. The observed shape of the Br− plume at Cape Cod was simulated by adding two layers with different hydraulic conductivities at shallow depth across the region. The large dispersion and asymmetrical shape of the Li+ plume were simulated by including kinetic adsorption-desorption reactions.

Processes affecting the dissipation of the herbicide isoxaflutole and its diketonitrile metabolite in agricultural soils under field conditions.

PubMed

Papiernik, Sharon K; Yates, Scott R; Koskinen, William C; Barber, Brian

2007-10-17

Two-year field dissipation studies were conducted in three soil types in Minnesota to examine the processes affecting the dissipation of the herbicide isoxaflutole and its phytotoxic diketonitrile metabolite (DKN) under relatively cool, wet soil conditions. Plots of cuphea were treated with isoxaflutole and potassium bromide, a nonsorbed, nondegraded tracer. Replicate soil cores were collected six times during the growing season to a depth of 1 m, and the bromide or herbicide concentration was measured in each of five depth increments. The dissipation half-life (DT50) of isoxaflutole + DKN was 8-18 days in each soil. Bromide and herbicide concentrations were low at depths >40 cm throughout the study, and herbicide concentrations in soil 100 days after application were usually undetectable. Simulation modeling using Hydrus-1D for the loam soil suggested that plant uptake was an important mechanism of dissipation.

TRANSPORT OF CHROMIUM AND SELENIUM IN A PRISTINE SAND AND GRAVEL AQUIFER: ROLE OF ADSORPTION PROCESSES

EPA Science Inventory

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...

Transport of pesticides and artificial tracers in vertical-flow lab-scale wetlands

NASA Astrophysics Data System (ADS)

Durst, Romy; Imfeld, Gwenaël.; Lange, Jens

2013-01-01

Wetland systems can be hydrologically connected to a shallow aquifer and intercept upward flow of pesticide-contaminated water during groundwater discharge. However, pesticide transport and attenuation through wetland sediments (WSs) intercepting contaminated water is rarely evaluated quantitatively. The use of artificial tracers to evaluate pesticide transport and associated risks is a fairly new approach that requires evaluation and validation. Here we evaluate during 84 days the transport of two pesticides (i.e., isoproturon (IPU) and metalaxyl (MTX)) and three tracers (i.e., bromide (Br), uranine (UR), and sulforhodamine B (SRB)) in upward vertical-flow vegetated and nonvegetated lab-scale wetlands. The lab-scale wetlands were filled with outdoor WSs and were continuously supplied with tracers and the pesticide-contaminated water. The transport of IPU and UR was characterized by high solute recovery (approximately 80%) and low retardation compared to Br. The detection of desmethylisoproturon in the wetlands indicated IPU degradation. SRB showed larger retardation (>3) and lower recovery (approximately 60%) compared to Br, indicating that sorption controlled SRB transport. MTX was moderately retarded (approximately 1.5), and its load attenuation in the wetland reached 40%. In the vegetated wetland, preferential flow along the roots decreased interactions between solutes and sediments, resulting in larger pesticide and tracer recovery. Our results show that UR and IPU have similar transport characteristics under the tested subsurface-flow conditions, whereas SRB may serve as a proxy for less mobile and more persistent pesticides. Since UR and SRB are not significantly affected by degradation, their use as proxies for fast degrading pollutants may be limited. We anticipate our results to be a starting point for considering artificial tracers for investigating pesticide transport in environments at groundwater/surface-water interfaces.

Imaging Pathways in Fractured Rock Using Three-Dimensional Electrical Resistivity Tomography.

PubMed

Robinson, Judith; Slater, Lee; Johnson, Timothy; Shapiro, Allen; Tiedeman, Claire; Ntarlagiannis, Dimitrios; Johnson, Carole; Day-Lewis, Frederick; Lacombe, Pierre; Imbrigiotta, Thomas; Lane, John

2016-03-01

Major challenges exist in delineating bedrock fracture zones because these cause abrupt changes in geological and hydrogeological properties over small distances. Borehole observations cannot sufficiently capture heterogeneity in these systems. Geophysical techniques offer the potential to image properties and processes in between boreholes. We used three-dimensional cross borehole electrical resistivity tomography (ERT) in a 9 m (diameter) × 15 m well field to capture high-resolution flow and transport processes in a fractured mudstone contaminated by chlorinated solvents, primarily trichloroethylene. Conductive (sodium bromide) and resistive (deionized water) injections were monitored in seven boreholes. Electrode arrays with isolation packers and fluid sampling ports were designed to enable acquisition of ERT measurements during pulsed tracer injections. Fracture zone locations and hydraulic pathways inferred from hydraulic head drawdown data were compared with electrical conductivity distributions from ERT measurements. Static ERT imaging has limited resolution to decipher individual fractures; however, these images showed alternating conductive and resistive zones, consistent with alternating laminated and massive mudstone units at the site. Tracer evolution and migration was clearly revealed in time-lapse ERT images and supported by in situ borehole vertical apparent conductivity profiles collected during the pulsed tracer test. While water samples provided important local information at the extraction borehole, ERT delineated tracer migration over spatial scales capturing the primary hydrogeological heterogeneity controlling flow and transport. The fate of these tracer injections at this scale could not have been quantified using borehole logging and/or borehole sampling methods alone. © 2015, National Ground Water Association.

Labile Dissolved Organic Carbon Availability Controls Hyporheic Denitrification: a 15N Tracer Study

NASA Astrophysics Data System (ADS)

Zarnetske, J. P.; Haggerty, R.; Wondzell, S. M.; Baker, M. A.

2009-12-01

We used an in situ 15N-labeled nitrate (15NO3-) and acetate injection experiment to determine how the availability of labile dissolved organic carbon (DOC) as acetate influences microbial denitrification in the hyporheic zone (HZ) of an upland (3rd-order) agricultural stream. A 48 h steady-state injection of a conservative tracer, chloride, and 15NO3- was used to quantify ambient HZ denitrification via 15N2 production. Following ambient plateau measurements of denitrification during the first 24 h, a second conservative tracer, bromide, and labile DOC source, acetate, were co-injected for an additional 24 h to measure HZ denitrification under increased DOC supply. Conservative tracers were observed at 4 of the 6 down gradient wells. Receiving wells represented HZ median residence times of 7.0 to 13.1 h, nominal flowpath lengths of 0.7 to 3.7 m, and hypoxic conditions (7.5 to 9.3 mg-O2 L-1 deficit). All 4 receiving wells demonstrated 15N2 production during ambient conditions indicating that the HZ was an active denitrification environment. Acetate addition stimulated significant increases in 15N2 production by factors of 2.7 to 26.1 in all receiving wells, and significant decreases of NO3- and DOC aromaticity (via SUVA254) in the two wells most hydrologically connected to the injection. In all receiving wells, increases of bromide and 15N2 production occurred without concurrent increases in acetate indicating that 100% of acetate was retained in the HZ, a portion of which is due to biological consumption. These results support our hypothesis that microbial denitrification in anaerobic portions of the hyporheic zone is limited by labile DOC supply.

Protein binding of isofluorophate in vivo after coexposure to multiple chemicals.

PubMed Central

Vogel, John S; Keating, Garrett A; Buchholz, Bruce A

2002-01-01

Full toxicologic profiles of chemical mixtures, including dose-response extrapolations to realistic exposures, is a prohibitive analytical problem, even for a restricted class of chemicals. We present an approach to probing in vivo interactions of pesticide mixtures at relevant low doses using a monitor compound to report the response of biochemical pathways shared by mixture components. We use accelerator mass spectrometry (AMS) to quantify [14C]-diisopropylfluorophosphate as a tracer at attomole levels with 1-5% precision after coexposures to parathion (PTN), permethrin (PER), and pyridostigmine bromide separately and in conjunction. Pyridostigmine shows an overall protective effect against tracer binding in plasma, red blood cells, muscle, and brain that is not explained as competitive protein binding. PTN and PER induce a significant 25-30% increase in the amount of tracer reaching the brain with or without pyridostigmine. The sensitivity of AMS for isotope-labeled tracer compounds can be used to probe the physiologic responses of specific biochemical pathways to multiple compound exposures. PMID:12634135

Hydrological parameter estimations from a conservative tracer test with variable-density effects at the Boise Hydrogeophysical Research Site

NASA Astrophysics Data System (ADS)

Dafflon, B.; Barrash, W.; Cardiff, M.; Johnson, T. C.

2011-12-01

Reliable predictions of groundwater flow and solute transport require an estimation of the detailed distribution of the parameters (e.g., hydraulic conductivity, effective porosity) controlling these processes. However, such parameters are difficult to estimate because of the inaccessibility and complexity of the subsurface. In this regard, developments in parameter estimation techniques and investigations of field experiments are still challenging and necessary to improve our understanding and the prediction of hydrological processes. Here we analyze a conservative tracer test conducted at the Boise Hydrogeophysical Research Site in 2001 in a heterogeneous unconfined fluvial aquifer. Some relevant characteristics of this test include: variable-density (sinking) effects because of the injection concentration of the bromide tracer, the relatively small size of the experiment, and the availability of various sources of geophysical and hydrological information. The information contained in this experiment is evaluated through several parameter estimation approaches, including a grid-search-based strategy, stochastic simulation of hydrological property distributions, and deterministic inversion using regularization and pilot-point techniques. Doing this allows us to investigate hydraulic conductivity and effective porosity distributions and to compare the effects of assumptions from several methods and parameterizations. Our results provide new insights into the understanding of variable-density transport processes and the hydrological relevance of incorporating various sources of information in parameter estimation approaches. Among others, the variable-density effect and the effective porosity distribution, as well as their coupling with the hydraulic conductivity structure, are seen to be significant in the transport process. The results also show that assumed prior information can strongly influence the estimated distributions of hydrological properties.

Assessment of nitrification potential in ground water using short term, single-well injection experiments

USGS Publications Warehouse

Smith, R.L.; Baumgartner, L.K.; Miller, D.N.; Repert, D.A.; Böhlke, J.K.

2006-01-01

Nitrification was measured within a sand and gravel aquifer on Cape Cod, MA, using a series of single-well injection tests. The aquifer contained a wastewater-derived contaminant plume, the core of which was anoxic and contained ammonium. The study was conducted near the downgradient end of the ammonium zone, which was characterized by inversely trending vertical gradients of oxygen (270 to 0 μM) and ammonium (19 to 625 μM) and appeared to be a potentially active zone for nitrification. The tests were conducted by injecting a tracer solution (ambient ground water + added constituents) into selected locations within the gradients using multilevel samplers. After injection, the tracers moved by natural ground water flow and were sampled with time from the injection port. Rates of nitrification were determined from changes in nitrate and nitrite concentration relative to bromide. Initial tests were conducted with 15N-enriched ammonium; subsequent tests examined the effect of adding ammonium, nitrite, or oxygen above background concentrations and of adding difluoromethane, a nitrification inhibitor. In situ net nitrate production exceeded net nitrite production by 3- to 6- fold and production rates of both decreased in the presence of difluoromethane. Nitrification rates were 0.02–0.28 μmol (L aquifer)−1 h−1 with in situ oxygen concentrations and up to 0.81 μmol (L aquifer)−1 h−1 with non-limiting substrate concentrations. Geochemical considerations indicate that the rates derived from single-well injection tests yielded overestimates of in situ rates, possibly because the injections promoted small-scale mixing within a transport-limited reaction zone. Nonetheless, these tests were useful for characterizing ground water nitrification in situ and for comparing potential rates of activity when the tracer cloud included non-limiting ammonium and oxygen concentrations.

Percent recovery of low influent concentrations of microorganism surrogates in small sand columns

NASA Astrophysics Data System (ADS)

Stevenson, M. E.; Blaschke, A. P.

2012-04-01

In order to develop a dependable method to calculate the setback distance of a drinking water well from a potential point of microbiological contamination, surrogates are used to perform field tests to avoid using pathogenic micro-organisms. One such surrogate used to model the potential travel time of microbial contamination is synthetic microspheres. The goal of this study is to examine the effect of differing influent colloid concentrations on the percent recovery of microbial surrogates after passing through a soil column. Similar studies have been done to investigate blocking of ideal attachment sites using concentrations between 106 and 1010 particles ml-1. These high concentrations were necessary due to the detection limit of the measuring technique used; however, our measuring technique allows us to test input concentrations ranging from 101 to 106 particles ml-1. These low concentrations are more similar to the concentrations of pathogenic microorganisms present in nature. We have tested the enumeration of 0.5 μm microspheres using a solid-phase cytometer and evaluated their transport in small sand columns. Fluorescent microspheres were purchased for this study with carboxylated surfaces. The soil columns consist of Plexiglas tubes, 30 cm long and 7 cm in diameter, both filled with the same coarse sand. Bromide was used as a conservative tracer, to estimate pore-water velocity and dispersivity, and bromide concentrations were analysed using ion chromatography and bromide probes. Numerical modelling was done using CXTFIT and HYDRUS-1D software programs. The 0.5 μm beads were enumerated in different environmental waters using solid-phase cytometry and compared to counts in sterile water in order to confirm the accuracy of the method. The solid-phase cytometer was able to differentiate the 0.5 μm beads from naturally present autofluorescent particles and bacteria, and therefore, is an appropriate method to enumerate this surrogate.

Push-pull tests for estimating effective porosity: expanded analytical solution and in situ application

NASA Astrophysics Data System (ADS)

Paradis, Charles J.; McKay, Larry D.; Perfect, Edmund; Istok, Jonathan D.; Hazen, Terry C.

2018-03-01

The analytical solution describing the one-dimensional displacement of the center of mass of a tracer during an injection, drift, and extraction test (push-pull test) was expanded to account for displacement during the injection phase. The solution was expanded to improve the in situ estimation of effective porosity. The truncated equation assumed displacement during the injection phase was negligible, which may theoretically lead to an underestimation of the true value of effective porosity. To experimentally compare the expanded and truncated equations, single-well push-pull tests were conducted across six test wells located in a shallow, unconfined aquifer comprised of unconsolidated and heterogeneous silty and clayey fill materials. The push-pull tests were conducted by injection of bromide tracer, followed by a non-pumping period, and subsequent extraction of groundwater. The values of effective porosity from the expanded equation (0.6-5.0%) were substantially greater than from the truncated equation (0.1-1.3%). The expanded and truncated equations were compared to data from previous push-pull studies in the literature and demonstrated that displacement during the injection phase may or may not be negligible, depending on the aquifer properties and the push-pull test parameters. The results presented here also demonstrated the spatial variability of effective porosity within a relatively small study site can be substantial, and the error-propagated uncertainty of effective porosity can be mitigated to a reasonable level (< ± 0.5%). The tests presented here are also the first that the authors are aware of that estimate, in situ, the effective porosity of fine-grained fill material.

Evaluation of multidimensional transport through a field-scale compacted soil liner

USGS Publications Warehouse

Willingham, T.W.; Werth, C.J.; Valocchi, A.J.; Krapac, I.G.; Toupiol, C.; Stark, T.D.; Daniel, D.E.

2004-01-01

A field-scale compacted soil liner was constructed at the University of Illinois at Urbana-Champaign by the U.S. Environmental Protection Agency (USEPA) and Illinois State Geological Survey in 1988 to investigate chemical transport rates through low permeability compacted clay liners (CCLs). Four tracers (bromide and three benzoic acid tracers) were each added to one of four large ring infiltrometers (LRIs) while tritium was added to the pond water (excluding the infiltrometers). Results from the long-term transport of Br- from the localized source zone of LRI are presented in this paper. Core samples were taken radially outward from the center of the Br- LRI and concentration depth profiles were obtained. Transport properties were evaluated using an axially symmetric transport model. Results indicate that (1) transport was diffusion controlled; (2) transport due to advection was negligible and well within the regulatory limits of ksat???1 ?? 10-7 cm/s; (3) diffusion rates in the horizontal and vertical directions were the same; and (4) small positioning errors due to compression during soil sampling did not affect the best fit advection and diffusion values. The best-fit diffusion coefficient for bromide was equal to the molecular diffusion coefficient multiplied by a tortuosity factor of 0.27, which is within 8% of the tortuosity factor (0.25) found in a related study where tritium transport through the same liner was evaluated. This suggests that the governing mechanisms for the transport of tritium and bromide through the CCL were similar. These results are significant because they address transport through a composite liner from a localized source zone which occurs when defects or punctures in the geomembrane of a composite system are present. ?? ASCE.

Interactions between soil texture and placement of dairy slurry application: I. Flow characteristics and leaching of nonreactive components.

PubMed

Glaesner, Nadia; Kjaergaard, Charlotte; Rubaek, Gitte H; Magid, Jakob

2011-01-01

Land application of manure can exacerbate nutrient and contaminant transfers to the aquatic environment. This study examined the effect of injecting a dairy cattle (Bostaurus L.) manure slurry on mobilization and leaching of dissolved, nonreactive slurry components across a range of agricultural soils. We compared leaching of slurry-applied bromide through intact soil columns (20 cm diam., 20 cm high) of differing textures following surface application or injection of slurry. The volumetric fraction of soil pores >30 microm ranged from 43% in a loamy sand to 28% in a sandy loam and 15% in a loam-textured soil. Smaller active flow volumes and higher proportions of preferential flow were observed with increasing soil clay content. Injection of slurry in the loam soil significantly enhanced diffusion of applied bromide into the large fraction of small pores compared with surface application. The resulting physical protection against leaching of bromide was reflected by 60.2% of the bromide tracer was recovered in the effluent after injection, compared with 80.6% recovery after surface application. No effect of slurry injection was observed in the loamy sand and sandy loam soils. Our findings point to soil texture as an important factor influencing leaching of dissolved, nonreactive slurry components in soils amended with manure slurry.

Ground water pollution by roof runoff infiltration evidenced with multi-tracer experiments.

PubMed

Ammann, Adrian A; Hoehn, Eduard; Koch, Sabine

2003-03-01

The infiltration of urban roof runoff into well permeable subsurface material may have adverse effects on the ground water quality and endanger drinking water resources. Precipitation water from three different roofs of an industrial complex was channelled to a pit and infiltrated into a perialpine glaciofluvial gravel-and-sand aquifer. A shaft was constructed at the bottom of the pit and equipped with an array of TDR probes, lysimeters and suction cups that allowed measuring and sampling soil water at different depths. A fast infiltration flow was observed during natural rainfall events and during artificial infiltration experiments. For a better understanding of the behaviour of contaminants, experiments were conducted with cocktails of compounds of different reactivity (ammonium, strontium, atratone) and of non-reactive tracers (uranine, bromide, naphthionate), which represent different classes of pollutants. The experiment identified cation exchange reactions influencing the composition of the infiltrating water. These processes occurred under preferential flow conditions in macropores of the material. Measuring concentration changes under the controlled inflow of tracer experiments, the pollution potential was found to be high. Non-reactive tracers exhibited fast breakthrough and little sorption.

Fate of herbicides in a shallow aerobic aquifer: A continuous field injection experiment (Vejen, Denmark)

NASA Astrophysics Data System (ADS)

Broholm, Mette M.; Rügge, Kirsten; Tuxen, Nina; HøJberg, Anker L.; MosbæK, Hans; Bjerg, Poul L.

2001-12-01

A continuous, natural gradient, field injection experiment, involving six herbicides and a tracer, was performed in a shallow aerobic aquifer near Vejen, Denmark. Bentazone, (±)-2-(4-chloro-2-methylphenoxy) propanoic acid (MCPP), dichlorprop, isoproturon, and the dichlobenil metabolite 2,6-dichlor-benzamide (BAM) were injected along with 2-methyl-4,6-dinitrophenol (not discussed in this paper) and the tracer bromide. The injection lasted for 216 days and created a continuous plume in the aquifer. The plume was monitored in three dimensions in 96 multilevel samplers of 6-9 points each for 230 days, with selected individual points for a longer period. The bromide plume followed a complex path through the monitoring network downgradient of the injection wells. The plume movement was controlled by spatially varied hydraulic conductivities of the sand deposit and influenced by asynchronous seasonal variation in groundwater potentials. An average flow velocity of 0.5 m/d was observed, as depicted by bromide. Bentazone, BAM, MCPP, and dichlorprop retardation was negligible, and only slight retardation of isoproturon was observed in the continuous injection experiment and a preceding pulse experiment. No degradation of bentazone was observed in the aerobic aquifer during the monitoring period. BAM and isoproturon were not degraded within 5 m downgradient of the injection. The two phenoxy acids MCPP and dichlorprop were both degraded in the aerobic aquifer. Near the source a lag phase was observed followed by fast degradation of the phenoxy acids, indicating growth kinetics. The phenoxy acids were completely degraded within l m downgradient of the injection wells, resulting in the plumes being divided into small plumes at the injection wells and pulses farther downgradient. During the lag phase, phenoxy acids had spread beyond the 25 m long monitoring network. However, the mass of the phenoxy acids passing the 10-25 m fences never matched the corresponding bentazone or bromide masses, and the pulse was observed to shrink in size. This indicates that this pulse of phenoxy acids was being partially degraded at a low rate as it traveled through the aquifer.

Two-dimensional distribution of microbial activity and flow patterns within naturally fractured chalk.

PubMed

Arnon, Shai; Ronen, Zeev; Adar, Eilon; Yakirevich, Alexander; Nativ, Ronit

2005-10-01

The two-dimensional distribution of flow patterns and their dynamic change due to microbial activity were investigated in naturally fractured chalk cores. Long-term biodegradation experiments were conducted in two cores ( approximately 20 cm diameter, 31 and 44 cm long), intersected by a natural fracture. 2,4,6-tribromophenol (TBP) was used as a model contaminant and as the sole carbon source for aerobic microbial activity. The transmissivity of the fractures was continuously reduced due to biomass accumulation in the fracture concurrent with TBP biodegradation. From multi-tracer experiments conducted prior to and following the microbial activity, it was found that biomass accumulation causes redistribution of the preferential flow channels. Zones of slow flow near the fracture inlet were clogged, thus further diverting the flow through zones of fast flow, which were also partially clogged. Quantitative evaluation of biodegradation and bacterial counts supported the results of the multi-tracer tests, indicating that most of the bacterial activity occurs close to the inlet. The changing flow patterns, which control the nutrient supply, resulted in variations in the concentrations of the chemical constituents (TBP, bromide and oxygen), used as indicators of biodegradation.

Analytical and experimental analysis of solute transport in heterogeneous porous media.

PubMed

Wu, Lei; Gao, Bin; Tian, Yuan; Muñoz-Carpena, Rafael

2014-01-01

Knowledge of solute transport in heterogeneous porous media is crucial to monitor contaminant fate and transport in soil and groundwater systems. In this study, we present new findings from experimental and mathematical analysis to improve current understanding of solute transport in structured heterogeneous porous media. Three saturated columns packed with different sand combinations were used to examine the breakthrough behavior of bromide, a conservative tracer. Experimental results showed that bromide had different breakthrough responses in the three types of sand combinations, indicating that heterogeneity in hydraulic conductivity has a significant effect on the solute transport in structured heterogeneous porous media. Simulations from analytical solutions of a two-domain solute transport model matched experimental breakthrough data well for all the experimental conditions tested. Experimental and model results show that under saturated flow conditions, advection dominates solute transport in both fast-flow and slow-flow domains. The sand with larger hydraulic conductivity provided a preferential flow path for solute transport (fast-flow domain) that dominates the mass transfer in the heterogeneous porous media. Importantly, the transport in the slow-flow domain and mass exchange between the domains also contribute to the flow and solute transport processes and thus must be considered when investigating contaminant transport in heterogeneous porous media.

Modeling flow and solute transport at a tile drain field site by explicit representation of preferential flow structures: Equifinality and uncertainty

NASA Astrophysics Data System (ADS)

Zehe, E.; Klaus, J.

2011-12-01

Rapid flow in connected preferential flow paths is crucial for fast transport of water and solutes through soils, especially at tile drained field sites. The present study tests whether an explicit treatment of worm burrows is feasible for modeling water flow, bromide and pesticide transport in structured heterogeneous soils with a 2-dimensional Richards based model. The essence is to represent worm burrows as morphologically connected paths of low flow resistance and low retention capacity in the spatially highly resolved model domain. The underlying extensive database to test this approach was collected during an irrigation experiment, which investigated transport of bromide and the herbicide Isoproturon at a 900 sqm tile drained field site. In a first step we investigated whether the inherent uncertainty in key data causes equifinality i.e. whether there are several spatial model setups that reproduce tile drain event discharge in an acceptable manner. We found a considerable equifinality in the spatial setup of the model, when key parameters such as the area density of worm burrows and the maximum volumetric water flows inside these macropores were varied within the ranges of either our measurement errors or measurements reported in the literature. Thirteen model runs yielded a Nash-Sutcliffe coefficient of more than 0.9. Also, the flow volumes were in good accordance and peak timing errors where less than or equal to 20 min. In the second step we investigated thus whether this "equifinality" in spatial model setups may be reduced when including the bromide tracer data into the model falsification process. We simulated transport of bromide for the 13 spatial model setups, which performed best with respect to reproduce tile drain event discharge, without any further calibration. Four of this 13 model setups allowed to model bromide transport within fixed limits of acceptability. Parameter uncertainty and equifinality could thus be reduced. Thirdly, we selected one of those four setups for simulating transport of Isoproturon, which was applied the day before the irrigation experiment, and tested different parameter combinations to characterise adsorption according to the footprint data base. Simulations could, however, only reproduce the observed event based leaching behaviour, when we allowed for retardation coefficients that were very close to one. This finding is consistent with observations various field observations. We conclude: a) A realistic representation of dominating structures and their topology is of key importance for predicting preferential water and mass flows at tile drained hillslopes. b) Parameter uncertainty and equifinality could be reduced, but a system inherent equifinality in a 2-dimensional Richards based model has to be accepted.

First Evaluation of Radioiodinated Flavonoids as Necrosis-Avid Agents and Application in Early Assessment of Tumor Necrosis.

PubMed

Liang, Jiajia; Sun, Ziping; Zhang, Dongjian; Jin, Qiaomei; Cai, Lingqiao; Ma, Lin; Liu, Wei; Ni, Yicheng; Zhang, Jian; Yin, Zhiqi

2018-01-02

A rapid and accurate identification of necrotic tissues is of great importance to define disease severity, predict prognosis, and monitor responses to therapies. To seek necrosis-avid agents with clinically translational potential, we first evaluated the necrosis avidity of flavonoids in rodent models of muscular, myocardial, and tumoral necrosis. In this study, the necrosis avidity of eight radioiodinated 5,7-dihydroxyflavones was tested by ex vivo gamma counting, histochemical staining, and autoradiography in mouse models of ethanol-induced muscular necrosis. The necrosis avidity of a lead tracer, 131 I-5, was further assessed in rat models of myocardial infarction and reperfusion. Therapy response was evaluated by 131 I-5 single photon emission computed tomography/computed tomography imaging 24 h after combretastatin A-4 disodium phosphate (CA4P) therapy on rats bearing W256 breast carcinomas. The necrosis avidity mechanism for the tracers was studied by in vitro DNA binding experiments of 12 5,7-dihydroxyflavones and in vivo blocking experiments of 131 I-5. In the results, all 131 I-5,7-dihydroxyflavones showed intense uptake to necrotic muscles, and 131 I-5 emerged as the most potential tracer among them. 131 I-5 obtained a necrotic-viable myocardium ratio of 5.0 ± 0.9 in post-mortem biodistribution on reperfused myocardial infarction models and achieved necrosis imaging on CA4P-treated W256 tumors 4 h after tracer injection. DNA binding studies suggested that necrosis avidity was related to DNA binding to a certain extent. The uptake of 131 I-5 in necrotic muscle was markedly blocked by excessive ethidium bromide and cold 5 with a 51.95% and 64.29% decline at 1 h after coinjection, respectively. In conclusion, flavonoids are necrosis-avid agents. Furthermore, 131 I-5 can serve as a promising necrosis-avid diagnostic tracer for the rapid imaging of necrotic tissues, supporting the further molecular design of radiotracer based on 5.

Influence of water chemistry and travel distance on bacteriophage PRD-1 transport in a sandy aquifer

USGS Publications Warehouse

Blanford, W.J.; Brusseau, M.L.; Jim Yeh, T.-C.; Gerba, C.P.; Harvey, R.

2005-01-01

Experiments were conducted to evaluate the impact of groundwater chemistry and travel distance on the transport and fate behavior of PRD-1, a bacteriophage employed as a surrogate tracer for pathogenic enteric viruses. The experiments were conducted in the unconfined aquifer at the United States Geological Survey Cape Cod Toxic-Substances Hydrology Research Site in Falmouth, Massachusetts. The transport behavior of bromide (Br-) and PRD-1 were evaluated in a sewage-effluent contaminated zone and a shallower uncontaminated zone at this site. Several multilevel sampling devices located along a 13-m transect were used to collect vertically discrete samples to examine longitudinal and vertical variability of PRD-1 retardation and attenuation. The concentration of viable bacteriophage in the aqueous phase decreased greatly during the first few meters of transport. This decrease is attributed to a combination of colloid filtration (attachment) and inactivation. The removal was greater (10 -12 relative recovery) and occurred within the first meter for the uncontaminated zone, whereas it was lesser (10-9 relative recovery) and occurred over 4 m in the contaminated zone. The lesser removal observed for the contaminated zone is attributed to the influence of sorbed and dissolved organic matter, phosphate, and other anions, which are present in higher concentrations in the contaminated zone, on PRD-1 attachment. After the initial decrease, the aqueous PRD-1 concentrations remained essentially constant in both zones for the remainder of the tests (total travel distances of 13 m), irrespective of variations in geochemical properties within and between the two zones. The viable, mobile PRD-1 particles traveled at nearly the rate of bromide, which was used as a non-reactive tracer. The results of this study indicate that a small fraction of viable virus particles may persist in the aqueous phase and travel significant distances in the subsurface environment. ?? 2005 Elsevier Ltd. All rights reserved.

Field Demonstration of Propane Biosparging for In Situ Remediation of N-Nitrosodimethylamine (NDMA) in Groundwater

DTIC Science & Technology

2015-12-01

and metamorphic rocks that make up the Sierra Nevada Mountain Range. Aerojet is underlain by fluvial and marine sedimentary deposits ranging in...age from Cretaceous to Recent. These sedimentary deposits unconformably overlie Jurassic-aged metamorphic basement rocks that dip to the west. These...BSW-1. Figure 5-3. Bromide concentrations in PMW-2, PMW-3 ( used as injection well), and PMW-4 during 14-day tracer study. Figure 5-4. Darcy

Effect of Bromide-Hypochlorite Bactericides on Microorganisms1

PubMed Central

Shere, Lewis; Kelley, Maurice J.; Richardson, J. Harold

1962-01-01

A new principle in compounding stable, granular bactericidal products led to unique combinations of a water-soluble inorganic bromide salt with a hypochlorite-type disinfectant of either inorganic or organic type. Microbiological results are shown for an inorganic bactericide composed of chlorinated trisodium phosphate containing 3.1% “available chlorine” and 2% potassium bromide, and for an organic bactericide formulated from sodium dichloroisocyanurate so as to contain 13.4% “available chlorine” and 8% potassium bromide. Comparison of these products with their nonbromide counterparts are reported for Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Streptococcus lactis, Aerobacter aerogenes, and Proteus vulgaris. Test methods employed were the Chambers test, the A.O.A.C. Germicidal and Detergent Sanitizer-Official test, and the Available Chlorine Germicidal Equivalent Concentration test. The minimal killing concentrations for the bromide-hypochlorite bactericides against this variety of organisms were reduced by a factor 2 to 24 times those required for similar hypochlorite-type disinfectants not containing the bromide. PMID:13977149

Sampling design for groundwater solute transport: Tests of methods and analysis of Cape Cod tracer test data

USGS Publications Warehouse

Knopman, Debra S.; Voss, Clifford I.; Garabedian, Stephen P.

1991-01-01

Tests of a one-dimensional sampling design methodology on measurements of bromide concentration collected during the natural gradient tracer test conducted by the U.S. Geological Survey on Cape Cod, Massachusetts, demonstrate its efficacy for field studies of solute transport in groundwater and the utility of one-dimensional analysis. The methodology was applied to design of sparse two-dimensional networks of fully screened wells typical of those often used in engineering practice. In one-dimensional analysis, designs consist of the downstream distances to rows of wells oriented perpendicular to the groundwater flow direction and the timing of sampling to be carried out on each row. The power of a sampling design is measured by its effectiveness in simultaneously meeting objectives of model discrimination, parameter estimation, and cost minimization. One-dimensional models of solute transport, differing in processes affecting the solute and assumptions about the structure of the flow field, were considered for description of tracer cloud migration. When fitting each model using nonlinear regression, additive and multiplicative error forms were allowed for the residuals which consist of both random and model errors. The one-dimensional single-layer model of a nonreactive solute with multiplicative error was judged to be the best of those tested. Results show the efficacy of the methodology in designing sparse but powerful sampling networks. Designs that sample five rows of wells at five or fewer times in any given row performed as well for model discrimination as the full set of samples taken up to eight times in a given row from as many as 89 rows. Also, designs for parameter estimation judged to be good by the methodology were as effective in reducing the variance of parameter estimates as arbitrary designs with many more samples. Results further showed that estimates of velocity and longitudinal dispersivity in one-dimensional models based on data from only five rows of fully screened wells each sampled five or fewer times were practically equivalent to values determined from moments analysis of the complete three-dimensional set of 29,285 samples taken during 16 sampling times.

Characterization of Solute Transport in Subsurface Using Permeable Pavement and Artificial Precipitation

NASA Astrophysics Data System (ADS)

HAN, K.; Hong, U.; Yeum, Y.; Yoon, J.; Lee, J.; Song, K.; Kwon, S.; Kim, Y.

2016-12-01

Permeable block as low impact development (LID) management can reduce storm water runoff, improve surface water quality and increase groundwater recharge. Recently, in Korea, application of the permeable block has growing trend for urban planning. However, few studies have evaluated how infiltrated rainfall through permeable block affect groundwater quality. Therefore, we conducted monitoring and evaluating of contaminants transport from permeable block surface to aquifer at LID installed three test-bed site. Pollutant materials as total nitrogen (T-N), nitrate (NO3-), ammonium (NH4+), total phosphorus (T-P), phosphate (PO42-), total organic carbon (TOC), sodium (Na+) and bromide (Br-) such as nonreactive tracer were sprinkled under permeable block and sprayed artificial precipitation of 100 mm/hr intensity during a 4 hours by rainfall simulator. All the test-bed area is 2 m x 2 m and monitoring wells were drilled a maximum depth of 10 m. Test-bed 1,2 and 3 groundwater level was approximately 1.9 m, 3.6 m and 4.6 m below ground surface, respectively. Test-bed 1 and 2, time to maximum concentration of Br- as tracer were 0.15 day and 1.71 day after simulated rainfall. In the test-bed 1, average normalized concentration (C* = Cmonitoring/C0, C0 is mass of sprinkled pollutant divide by sprayed water volume) of Br-, T-N, NO3-, NH4+, T-P, PO42-, TOC and Na+ were observed 0.26, 0.08, 0.14, N.D(not detected), 0.05, 0.05, 0.13 and 0.11, respectively. C* of tracer and other solutes on test-bed 2 were 0.52, 0.15, 0.25, N.D, 0.02, 0.02, 0.16 and 0.15, respectively. These phenomena that distinctions between C* of Br-and other solutes indicate to occur retardation by physical/chemical and biological process while pollutant containing water permeate from unsaturated soil to saturated aquifer. However, at the test-bed 3 distinct concentration of all solutes were not detected until 40 days. In this study evaluated the effects of groundwater quality by rainfall leachate from permeable block. Infiltration rate of solutes were measured NO3- > TOC > Na+ >>> PO42- > NH4+. Especially, these results suggested that organic N and T-P (PO42-) need not consideration for groundwater quality at permeable LID system.

Physical and Chemical Factors Influencing the Transport and Fate of Microorganisms in Soils with Preferential Flow

NASA Astrophysics Data System (ADS)

Wang, Y.; Bradford, S. A.; Simunek, J.

2011-12-01

Laboratory and numerical studies were conducted to investigate the influence of physical and chemical factors on the transport of E.coli O157:H7 and coliphage φX174 through preferential flow systems. Preferential flow systems were created in 13.2 cm diameter and 20 cm length columns by embedding sand lens of various grain size, length, and vertical position into finer textured matrix sand. Tracer solutions containing bromide and microbes were prepared at different ionic strength (IS) and sprayed onto the surface of the columns at desired steady rates using a rain simulator to achieve saturated or unsaturated conditions. Effluents were collected at the column bottom continuously and analyzed for concentrations of bromide, φX174, and E.coli. Complementary numerical simulations were conducted using the HYDRUS 2D code over a wider range of physical and chemical conditions, and to analyze bromide and microbe transport in the columns. Results indicated that preferential transport of the microbes was dependent on the hydraulic contrasts between the matrix and lens, the length of the lens, the size of microorganism, and the water saturation. The IS also influenced the preferential transport of microbes. In particular, increasing retention with IS decreased the overall microbe transport but increased the relative importance of preferential flow.

Validation of an automated fluorescein method for determining bromide in water

USGS Publications Warehouse

Fishman, M. J.; Schroder, L.J.; Friedman, L.C.

1985-01-01

Surface, atmospheric precipitation and deionized water samples were spiked with ??g l-1 concentrations of bromide, and the solutions stored in polyethylene and polytetrafluoroethylene bottles. Bromide was determined periodically for 30 days. Automated fluorescein and ion chromatography methods were used to determine bromide in these prepared samples. Analysis of the data by the paired t-test indicates that the two methods are not significantly different at a probability of 95% for samples containing from 0.015 to 0.5 mg l-1 of bromide. The correlation coefficient for the same sets of paired data is 0.9987. Recovery data, except for the surface water samples to which 0.005 mg l-1 of bromide was added, range from 89 to 112%. There appears to be no loss of bromide from solution in either type of container.Surface, atmospheric precipitation and deionized water samples were spiked with mu g l** minus **1 concentrations of bromide, and the solutions stored in polyethylene and polytetrafluoroethylene bottles. Bromide was determined periodically for 30 days. Automated fluorescein and ion chromatography methods were used to determine bromide in these prepared samples. Analysis of the data by the paired t-test indicates that the two methods are not significantly different at a probability of 95% for samples containing from 0. 015 to 0. 5 mg l** minus **1 of bromide. The correlation coefficient for the same sets of paired data is 0. 9987. Recovery data, except for the surface water samples to which 0. 005 mg l** minus **1 of bromide was added, range from 89 to 112%. Refs.

Questa baseline and pre-mining ground-water quality investigation. 2. Low-flow (2001) and snowmelt (2002) synoptic/tracer water chemistry for the Red River, New Mexico

USGS Publications Warehouse

McCleskey, R. Blaine; Nordstrom, D. Kirk; Steiger, Judy I.; Kimball, Briant A.; Verplanck, Philip L.

2003-01-01

Water analyses are reported for 259 samples collected from the Red River, New Mexico, and its tributaries during low-flow(2001) and spring snowmelt (2002) tracer studies. Water samples were collected along a 20-kilometer reach of the Red River beginning just east of the town of Red River and ending at the U.S. Geological Survey streamflow-gaging station located east of Questa, New Mexico. The study area was divided into three sections where separate injections and synoptic sampling events were performed during the low-flow tracer study. During the spring snowmelt tracer study, three tracer injections and synoptic sampling events were performed bracketing the areas with the greatest metal loading into the Red River as determined from the low-flow tracer study. The lowflow tracer synoptic sampling events were August 17, 20, and 24, 2001. The synoptic sampling events for the spring snowmelt tracer were March 30, 31, and April 1, 2002. Stream and large inflow water samples were sampled using equal-width and depth-integrated sampling methods and composited into half-gallon bottles. Grab water samples were collected from smaller inflows. Stream temperatures were measured at the time of sample collection. Samples were transported to a nearby central processing location where pH and specific conductance were measured and the samples processed for chemical analyses. Cations, trace metals, iron redox species, and fluoride were analyzed at the U.S. Geological Survey laboratory in Boulder, Colorado. Cations and trace metal concentrations were determined using inductively coupled plasma-optical emission spectrometry and graphite furnace atomic absorption spectrometry. Arsenic concentrations were determined using hydride generation atomic absorption spectrometry, iron redox species were measured using ultraviolet-visible spectrometry, and fluoride concentrations were determined using an ion-selective electrode. Alkalinity was measured by automated titration, and sulfate, chloride, and bromide were analyzed by ion chromatography at the U.S. Geological Survey laboratory in Salt Lake City, Utah.

Movement and fate of atrazine and bromide in central Kansas croplands

USGS Publications Warehouse

Sophocleous, M.; Townsend, M.A.; Whittemore, Donald O.

1990-01-01

Two flooding experiments were conducted at two sites with different soils to study the transport and fate of the commonly used herbicide atrazine and inorganic chemicals in the Great Bend Prairie croplands of south-central Kansas. The instantaneous profile method supplemented by the use of an organic (atrazine) and an inorganic (bromide) tracer chemical was used to characterize in situ the hydraulic and chemical properties of the appropriately instrumented field sites. Atrazine readily degraded to hydroxyatrazine and biodegradation by-products and was not detected deeper in the soil profile and underlying shallow aquifer. The classical processes of chemical movement based on porous media-equilibrium-diffuse flow did not fit the data well at either site. Incompletely mixed, slug flow appeared to predominate at one of the sites and preferential flow at the other. The slug movement caused 'piston-type' displacement of more saline solutions in the soil profile to the shallow water table. Recommendations for conducting related field studies based on our sampling experience are given. ?? 1990.

The transport and behaviour of isoproturon in unsaturated chalk cores

NASA Astrophysics Data System (ADS)

Besien, T. J.; Williams, R. J.; Johnson, A. C.

2000-04-01

A batch sorption study, a microcosm degradation study, and two separate column leaching studies were used to investigate the transport and fate of isoproturon in unsaturated chalk. The column leaching studies used undisturbed core material obtained from the field by dry percussion drilling. Each column leaching study used 25 cm long, 10 cm wide unsaturated chalk cores through which a pulse of isoproturon and bromide was eluted. The cores were set-up to simulate conditions in the unsaturated zone of the UK Chalk aquifer by applying a suction of 1 kPa (0.1 m H 2O) to the base of each column, and eluting at a rate corresponding to an average recharge rate through the unsaturated Chalk. A dye tracer indicated that the flow was through the matrix under these conditions. The results from the first column study showed high recovery rates for both isoproturon (73-92%) and bromide (93-96%), and that isoproturon was retarded by a factor of about 1.23 relative to bromide. In the second column study, two of the four columns were eluted with non-sterile groundwater in place of the sterile groundwater used on all other columns, and this study showed high recovery rates for bromide (85-92%) and lower recovery rates for isoproturon (66-79% — sterile groundwater, 48-61% — non-sterile groundwater). The enhanced degradation in the columns eluted with non-sterile groundwater indicated that groundwater microorganisms had increased the degradation rate within these columns. Overall, the reduced isoproturon recovery in the second column study was attributed to increased microbial degradation as a result of the longer study duration (162 vs. 105 days). The breakthrough curves (BTCs) for bromide had a characteristic convection-dispersion shape and were accurately simulated with the minimum of calibration using a simple convection-dispersion model (LEACHP). However, the isoproturon BTCs had an unusual shape and could not be accurately simulated.

Evaluating equilibrium and non-equilibrium transport of bromide and isoproturon in disturbed and undisturbed soil columns.

PubMed

Dousset, S; Thevenot, M; Pot, V; Simunek, J; Andreux, F

2007-12-07

In this study, displacement experiments of isoproturon were conducted in disturbed and undisturbed columns of a silty clay loam soil under similar rainfall intensities. Solute transport occurred under saturated conditions in the undisturbed soil and under unsaturated conditions in the sieved soil because of a greater bulk density of the compacted undisturbed soil compared to the sieved soil. The objective of this work was to determine transport characteristics of isoproturon relative to bromide tracer. Triplicate column experiments were performed with sieved (structure partially destroyed to simulate conventional tillage) and undisturbed (structure preserved) soils. Bromide experimental breakthrough curves were analyzed using convective-dispersive and dual-permeability (DP) models (HYDRUS-1D). Isoproturon breakthrough curves (BTCs) were analyzed using the DP model that considered either chemical equilibrium or non-equilibrium transport. The DP model described the bromide elution curves of the sieved soil columns well, whereas it overestimated the tailing of the bromide BTCs of the undisturbed soil columns. A higher degree of physical non-equilibrium was found in the undisturbed soil, where 56% of total water was contained in the slow-flow matrix, compared to 26% in the sieved soil. Isoproturon BTCs were best described in both sieved and undisturbed soil columns using the DP model combined with the chemical non-equilibrium. Higher degradation rates were obtained in the transport experiments than in batch studies, for both soils. This was likely caused by hysteresis in sorption of isoproturon. However, it cannot be ruled out that higher degradation rates were due, at least in part, to the adopted first-order model. Results showed that for similar rainfall intensity, physical and chemical non-equilibrium were greater in the saturated undisturbed soil than in the unsaturated sieved soil. Results also suggested faster transport of isoproturon in the undisturbed soil due to higher preferential flow and lower fraction of equilibrium sorption sites.

Evaluating equilibrium and non-equilibrium transport of bromide and isoproturon in disturbed and undisturbed soil columns

NASA Astrophysics Data System (ADS)

Dousset, S.; Thevenot, M.; Pot, V.; Šimunek, J.; Andreux, F.

2007-12-01

In this study, displacement experiments of isoproturon were conducted in disturbed and undisturbed columns of a silty clay loam soil under similar rainfall intensities. Solute transport occurred under saturated conditions in the undisturbed soil and under unsaturated conditions in the sieved soil because of a greater bulk density of the compacted undisturbed soil compared to the sieved soil. The objective of this work was to determine transport characteristics of isoproturon relative to bromide tracer. Triplicate column experiments were performed with sieved (structure partially destroyed to simulate conventional tillage) and undisturbed (structure preserved) soils. Bromide experimental breakthrough curves were analyzed using convective-dispersive and dual-permeability (DP) models (HYDRUS-1D). Isoproturon breakthrough curves (BTCs) were analyzed using the DP model that considered either chemical equilibrium or non-equilibrium transport. The DP model described the bromide elution curves of the sieved soil columns well, whereas it overestimated the tailing of the bromide BTCs of the undisturbed soil columns. A higher degree of physical non-equilibrium was found in the undisturbed soil, where 56% of total water was contained in the slow-flow matrix, compared to 26% in the sieved soil. Isoproturon BTCs were best described in both sieved and undisturbed soil columns using the DP model combined with the chemical non-equilibrium. Higher degradation rates were obtained in the transport experiments than in batch studies, for both soils. This was likely caused by hysteresis in sorption of isoproturon. However, it cannot be ruled out that higher degradation rates were due, at least in part, to the adopted first-order model. Results showed that for similar rainfall intensity, physical and chemical non-equilibrium were greater in the saturated undisturbed soil than in the unsaturated sieved soil. Results also suggested faster transport of isoproturon in the undisturbed soil due to higher preferential flow and lower fraction of equilibrium sorption sites.

Geology, hydrology, and results of tracer testing in the Galena-Platteville aquifer at a waste-disposal site near Byron, Illinois

USGS Publications Warehouse

Kay, Robert T.; Yeskis, Douglas J.; Prinos, Scott T.; Morrow, William S.; Vendl, Mark

1999-01-01

A study was conducted by the U.S. Geological Survey and the U.S. Environmental Protection Agency of the geohydrology of the dolomite bedrock at a waste-disposal site near Byron, Illinois. The study was designed to identify and characterize the flow pathways through the bedrock aquifer beneath the site. The geologic units of concern at the site are the Glenwood Formation of the Ancell Group, and the Platteville and Galena Groups. These deposits compose the Galena-Platteville aquifer and the underlying Harmony Hill Shale semiconfining unit. The Galena-Platteville aquifer is an unconfined aquifer. Geophysical logging, water levels, and aquifer-test data indicate the presence of interconnected, hydraulically active fractures in the middle of the Galena-Platteville aquifer (the upper flow pathway), and a second set of hydraulically active fractures (the lower flow pathway). The lower flow pathway may be present through much of the site. Few hydraulically active fractures are present in the upper part of the aquifer near the center of the site, but appear to be more numerous in the upper part of the aquifer in the western and northeastern parts of the site. Water-level data obtained during the tracer test indicate that pumping effects were present near the pumped wells. Pumping effects may have been present at several wells located along directions of identified fracture orientation from the pumped well. The upper part of the aquifer did not appear to be hydraulically well connected to the flow pathways supplying water to the pumped well. Large background changes in water levels obscured the effects of pumping and prevented calculation of aquifer properties. The velocity of the bromide tracer through the lower flow pathway under the hydraulic gradient resulting from the pumping was about 152 feet per day. Solution of the Darcy velocity equation results in a calculated effective porosity for this interval of 3.5 percent, indicating hydraulic interconnection between the fractures and the aquifer matrix. Ground-water velocity through the lower flow pathway was calculated to be 15.4 feet per day under hydrostatic conditions.

Keeping the secret: Insights from repeated catchment-scale tracer experiments under transient conditions

NASA Astrophysics Data System (ADS)

Bogner, Christina; Hauhs, Michael; Lange, Holger

2016-04-01

Catchment-level tracer experiments are generally performed to identify site-specific hydrological response functions of the catchment. The existence and uniqueness of these response functions are hardly ever questioned. Here, we report on a series of replicated tracer experiments in two small first-order catchments, G1 (0.6 ha, roofed) and F4 (2.3 ha, without roof) at Gårdsjön in SW Sweden. The soils in both catchments are shallow (< 50 cm) with the bedrock partly visible at the surface. In G1 (irrigated area approximately 1000 m2), tracer experiments were conducted under a roof between 1993 and 2003 during steady state flow conditions. In contrast, in F4 (irrigated area approximately 500 m2) the experiments were done without a roof mostly at transient conditions. The catchment F4 was equipped with a sprinkler system with a watering capacity of around 38-45 m3 day-1. Natural rainfall comes in addition. A bromide tracer solution was injected to groundwater at a single location about 40 m upstream the weir over a period of less than an hour, and was monitored using a set of groundwater tubes and the weir at the outlet over the following 4 days. In addition, discharge was measured. The experiments were repeated each summer from 2007 to 2015. While steady state conditions were guaranteed in G1, steady runoff has been achieved only four times in F4. We investigated tracer recovery rates against cumulated runoff since tracer application. Substantially different transit times and qualitatively different behaviour of the breakthrough curves were observed, even under steady state conditions. In G1, no single system response function could be identified in 5 replicates. Similarly, the catchment response functions in F4 under steady state differed between experiments. However, they remained in a similar range as in G1. Based on these results, we question the identifiability of flow paths and system properties, such as saturated water content or hydrologic transmissivity, at the catchment scale using tracer experiments. Rather, the series demonstrate the utter importance of the initial and boundary conditions which largely determine the response of the system to inert tracer pulses.

Journal: A Review of Some Tracer-Test Design Equations for Tracer-Mass Estimation and Sample Collection Frequency

EPA Science Inventory

Determination of necessary tracer mass, initial sample-collection time, and subsequent sample-collection frequency are the three most difficult aspects to estimate for a proposed tracer test prior to conducting the tracer test. To facilitate tracer-mass estimation, 33 mass-estima...

Operate A Chemical Surety Program And Studies Supporting The Medical Chemical Defense Research Program

DTIC Science & Technology

2010-05-01

23 Task Execution Plan 34 – Temperature Testing of Pyridostigmine Bromide (PB) .......... 23 KEY RESEARCH ACCOMPLISHMENTS...29, 2010. Staff was assembled and materials have been ordered. Task Execution Plan (TEP) 0034 – Temperature Testing of Pyridostigmine Bromide

A comparative modeling study of a dual tracer experiment in a large lysimeter under atmospheric conditions

NASA Astrophysics Data System (ADS)

Stumpp, C.; Nützmann, G.; Maciejewski, S.; Maloszewski, P.

2009-09-01

SummaryIn this paper, five model approaches with different physical and mathematical concepts varying in their model complexity and requirements were applied to identify the transport processes in the unsaturated zone. The applicability of these model approaches were compared and evaluated investigating two tracer breakthrough curves (bromide, deuterium) in a cropped, free-draining lysimeter experiment under natural atmospheric boundary conditions. The data set consisted of time series of water balance, depth resolved water contents, pressure heads and resident concentrations measured during 800 days. The tracer transport parameters were determined using a simple stochastic (stream tube model), three lumped parameter (constant water content model, multi-flow dispersion model, variable flow dispersion model) and a transient model approach. All of them were able to fit the tracer breakthrough curves. The identified transport parameters of each model approach were compared. Despite the differing physical and mathematical concepts the resulting parameters (mean water contents, mean water flux, dispersivities) of the five model approaches were all in the same range. The results indicate that the flow processes are also describable assuming steady state conditions. Homogeneous matrix flow is dominant and a small pore volume with enhanced flow velocities near saturation was identified with variable saturation flow and transport approach. The multi-flow dispersion model also identified preferential flow and additionally suggested a third less mobile flow component. Due to high fitting accuracy and parameter similarity all model approaches indicated reliable results.

Tracer-Test Planning Using the Efficient Hydrologic Tracer-Test Design (Ehtd) Program (2005)

EPA Science Inventory

Hydrological tracer testing is the most reliable diagnostic technique available for establishing flow trajectories and hydrologic connections and for determining basic hydraulic and geometric parameters necessary for establishing operative solute-transport processes. Tracer-test ...

Tracer-Test Planning Using the Efficient Hydrologic Tracer-Test Design (Ehtd) Program (2003)

EPA Science Inventory

Hydrological tracer testing is the most reliable diagnostic technique available for establishing flow trajectories and hydrologic connections and for determining basic hydraulic and geometric parameters necessary for establishing operative solute-transport processes. Tracer-test ...

Borehole flowmeter logging for the accurate design and analysis of tracer tests.

PubMed

Basiricò, Stefano; Crosta, Giovanni B; Frattini, Paolo; Villa, Alberto; Godio, Alberto

2015-04-01

Tracer tests often give ambiguous interpretations that may be due to the erroneous location of sampling points and/or the lack of flow rate measurements through the sampler. To obtain more reliable tracer test results, we propose a methodology that optimizes the design and analysis of tracer tests in a cross borehole mode by using vertical borehole flow rate measurements. Experiments using this approach, herein defined as the Bh-flow tracer test, have been performed by implementing three sequential steps: (1) single-hole flowmeter test, (2) cross-hole flowmeter test, and (3) tracer test. At the experimental site, core logging, pumping tests, and static water-level measurements were previously carried out to determine stratigraphy, fracture characteristics, and bulk hydraulic conductivity. Single-hole flowmeter testing makes it possible to detect the presence of vertical flows as well as inflow and outflow zones, whereas cross-hole flowmeter testing detects the presence of connections along sets of flow conduits or discontinuities intercepted by boreholes. Finally, the specific pathways and rates of groundwater flow through selected flowpaths are determined by tracer testing. We conclude that the combined use of single and cross-borehole flowmeter tests is fundamental to the formulation of the tracer test strategy and interpretation of the tracer test results. © 2014, National Ground Water Association.

Temperature effect on the transport of bromide and E. coli NAR in saturated soils

NASA Astrophysics Data System (ADS)

Gharabaghi, B.; Safadoust, A.; Mahboubi, A. A.; Mosaddeghi, M. R.; Unc, A.; Ahrens, B.; Sayyad, Gh.

2015-03-01

In this study we investigated the transport of nalidixic acid-resistant Escherichia coli (E. coli NAR) and bromide (Br-) through two soils, a sandy loam (SL) and clay loam (CL). Soils were repacked in columns (45 cm length × 22 cm diameter) and subjected to physical (freeze/thaw, and wet/dry cycles) and biological (by earthworms, Eisenia fetida) weathering for 12 months. Saturated flow conditions were maintained using a tension infiltrometer. Tests were carried out at either 5 or 20 °C. After steady-state flow conditions were established, a suspension containing E. coli NAR and Br- was sprayed onto the surface of soil columns. Leachate was sampled at three depths, 15, 30 and 45 cm. Time to maximum concentration (Cmax) of E. coli NAR was greater for SL at all depths. Both tracers had rapid breakthrough curves (BTCs) shortly after the suspension injection followed by prolonged tailing indicating the presence of preferential pathways and thus soil heterogeneity regenerated after the induced physical and biological weathering. About 40% of the E. coli NAR and 79% of the Br- leached through the entire 45 cm soil columns during the experiments. Leaching with cold water (5 °C) led to lower hydraulic conductivity and flow rate and consequently enhanced bacterial filtration for both soils. Very low values for the detachment coefficient for E. coli NAR at 5 °C suggest an irreversible process of bacterial attachment in heterogeneous soils. BTCs were well described by the mobile-immobile model (MIM) in HYDRUS-1D. Soil texture/structure and temperature had a significant effect on the model's fitted parameters.

COMPARISON OF THREE TRACER TESTS AT THE RAFT RIVER GEOTHERMAL SITE

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

Earl D Mattson; Mitchell Plummer; Carl Palmer

2011-02-01

Three conservative tracer tests have been conducted through the Bridge Fault fracture zone at the Raft River Geothermal (RRG) site. All three tests were conducted between injection well RRG-5 and production wells RRG-1 (790 m distance) and RRG-4 (740 m distance). The injection well is used during the summer months to provide pressure support to the production wells. The first test was conducted in 2008 using 136 kg of fluorescein tracer. Two additional tracers were injected in 2010. The first 2010 tracer injected was 100 kg fluorescein disodium hydrate salt on June, 21. The second tracer (100 kg 2,6-naphthalene disulfonicmore » acid sodium salt) was injected one month later on July 21. Sampling of the two productions wells is still being performed to obtain the tail end of the second 2010 tracer test. Tracer concentrations were measured using HPLC with a fluorescence detector. Results for the 2008 test, suggest 80% tracer recover at the two production wells. Of the tracer recovered, 85% of tracer mass was recovered in well RRG-4 indicating a greater flow pathway connection between injection well and RRG-4 than RRG-1. Fluorescein tracer results appear to be similar between the 2008 and 2010 tests for well RRG-4 with peak concentrations arriving approximately 20 days after injection despite the differences between the injection rates for the two tests (~950 gpm to 475 gpm) between the 2008 and 2010. The two 2010 tracer tests will be compared to determine if the results support the hypothesis that rock contraction along the flow pathway due to the 55 oC cooler water injection alters the flow through the ~140 oC reservoir.« less

Bromism caused by mix-formulated analgesic injectables.

PubMed

Hsieh, P F; Tsan, Y T; Hung, D Z; Hsu, C L; Lee, Y C; Chang, M H

2007-12-01

Bromism, chronic bromide intoxication, can be caused by a variety of medicines, but bromism due to pain-relieving injectable medications has not been reported. In this study, the methods used were internet searching on bromide-containing injectables available in Taiwan and the first case report of bromism due to mixed-formulated injectable medication. Many analgesic/antipyretic and antihistamine injections containing bromides are still being used in Taiwan. They contain sodium bromide up to 1000 mg/ampoule or calcium bromide up to 800 mg/amp. A 25-year-old female suffered from forgetfulness and unstable gait after long-term frequent injections of a preparation to relieve head and neck pain. Blood tests showed hyperchloremia (171 mEq/L) and a negative anion gap (-48.7 mEq/L). Serum bromide measured 2150 mg/L. She recovered completely in 3 days with saline treatment. Many bromide-containing injections are still being used in Taiwan. Clinicians should keep alert on this issue to avoid iatrogenic bromism or making misdiagnoses.

Test report : Raytheon / KTech RK30 Energy Storage System

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

Rose, David Martin; Schenkman, Benjamin L.; Borneo, Daniel R.

2013-10-01

The Department of Energy Office of Electricity (DOE/OE), Sandia National Laboratories (SNL) and the Base Camp Integration Lab (BCIL) partnered together to incorporate an energy storage system into a microgrid configured Forward Operating Base to reduce the fossil fuel consumption and to ultimately save lives. Energy storage vendors will be sending their systems to SNL Energy Storage Test Pad (ESTP) for functional testing and then to the BCIL for performance evaluation. The technologies that will be tested are electro-chemical energy storage systems comprising of lead acid, lithium-ion or zinc-bromide. Raytheon/KTech has developed an energy storage system that utilizes zinc-bromide flowmore » batteries to save fuel on a military microgrid. This report contains the testing results and some limited analysis of performance of the Raytheon/KTech Zinc-Bromide Energy Storage System.« less

Large-scale, on-site confirmatory, and varietal testing of a methyl bromide quarantine treatment to control codling moth (Lepidoptera: Tortricidae) in nectarines exported to Japan.

PubMed

Yokoyama, V Y; Miller, G T; Hartsell, P L; Leesch, J G

2000-06-01

In total, 30,491 codling moth, Cydia pomonella (L.), 1-d-old eggs on May Grand nectarines in two large-scale tests, and 17,410 eggs on Royal Giant nectarines in four on-site confirmatory tests were controlled with 100% mortality after fumigation with a methyl bromide quarantine treatment (48 g3 for 2 h at > or = 21 degrees C and 50% volume chamber load) on fruit in shipping containers for export to Japan. Ranges (mean +/- SEM) were for percentage sorption 34.7 +/- 6.2 to 46.5 +/- 2.5, and for concentration multiplied by time products 54.3 +/- 0.9 to 74.5 +/- 0.6 g.h/m3 in all tests. In large-scale tests with May Grand nectarines, inorganic bromide residues 48 h after fumigation ranged from 6.8 +/- 0.7 to 6.9 +/- 0.5 ppm, which were below the U.S. Environmental Protection Agency tolerance of 20 ppm; and, organic bromide residues were < 0.01 ppm after 1 d and < 0.001 ppm after 3 d in storage at 0-1 degree C. After completion of larger-scale and on-site confirmatory test requirements, fumigation of 10 nectarine cultivars in shipping containers for export to Japan was approved in 1995. Comparison of LD50s developed for methyl bromide on 1-d-old codling moth eggs on May Grand and Summer Grand nectarines in 1997 versus those developed for nine cultivars in the previous 11 yr showed no significant differences in codling moth response among the cultivars.

The use of One-Dimensional Laboratory Experiments to Assess Hydraulic Processes in Wastewater Soil Absorption Systems

NASA Astrophysics Data System (ADS)

Huntzinger, D. N.; McCray, J. E.; Siegrist, R.; Lowe, K.; VanCuyk, S.

2001-05-01

Sixteen, one-dimensional column lysimeters have been developed to evaluate the influence of loading regime and infiltrative surface character on hydraulic performance in wastewater soil absorption systems. A duplicate design was utilized to evaluate two infiltrative surface conditions (gravel-free vs. gravel-laden) under four hydraulic loading regimes representative of possible field conditions. By loading the columns at rates of 25 to 200 cm/day, the 17 weeks of column operation actually reflect up to approximately 13 yrs of field operation (at 5 cm/day). Therefore, the cumulative mass throughput and infiltrative rate loss for each loading regime can be examined to determine the viability of accelerated loading as a means to compress the time scale of observation, while still producing meaningfully results for the field scale. During operation, the columns were loaded with septic tank effluent at a prescribed rate and routinely monitoring for applied effluent composition, infiltration rate, time-dependant soil water content, water volume throughput, and percolate composition. Bromide tracer tests were completed prior to system startup and at weeks 2, 6, and 17 of system operation. Hydraulic characterization of the columns is based on measurements of the hydraulic loading rate, volumetric throughput, soil water content, and bromide breakthrough curves. Incipient ponding of wastewater developed during the 1st week of operation for columns loaded at the highest hydraulic rate (loading regimes 1 and 2), and during the 3rd and 6th week of operation for loading regimes 3 and 4, respectfully. The bromide breakthrough curves exhibit later breakthrough and tailing as system life increases, indicating the development of spatially variability in hydraulic conductivity within the column and the development of a clogging zone at the infiltrative surface. Throughput is assessed for each loading regime to determine the infiltration rate loss versus days of operation. Loading regimes 1 and 2 approach a comparable long-term throughput rate less than 20 cm/day, while loading regimes 3 and 4 reach a long-term throughput rate of less than 10 cm/day. These one-dimensional columns allow for the analysis of infiltrative rate loss and hydraulic behavior as a result of infiltrative surface character and loading regime.

Journal: Efficient Hydrologic Tracer-Test Design for Tracer ...

EPA Pesticide Factsheets

Hydrological tracer testing is the most reliable diagnostic technique available for the determination of basic hydraulic and geometric parameters necessary for establishing operative solute-transport processes. Tracer-test design can be difficult because of a lack of prior knowledge of the basic hydraulic and geometric parameters desired and the appropriate tracer mass to release. A new efficient hydrologic tracer-test design (EHTD) methodology has been developed to facilitate the design of tracer tests by root determination of the one-dimensional advection-dispersion equation (ADE) using a preset average tracer concentration which provides a theoretical basis for an estimate of necessary tracer mass. The method uses basic measured field parameters (e.g., discharge, distance, cross-sectional area) that are combined in functional relatipnships that descrive solute-transport processes related to flow velocity and time of travel. These initial estimates for time of travel and velocity are then applied to a hypothetical continuous stirred tank reactor (CSTR) as an analog for the hydrological-flow system to develop initial estimates for tracer concentration, tracer mass, and axial dispersion. Application of the predicted tracer mass with the hydraulic and geometric parameters in the ADE allows for an approximation of initial sample-collection time and subsequent sample-collection frequency where a maximum of 65 samples were determined to be necessary for descri

EVALUATION OF LEAKAGE FROM FUME HOODS USING TRACER GAS, TRACER NANOPARTICLES AND NANOPOWDER HANDLING TEST METHODOLOGIES

PubMed Central

Dunn, Kevin H.; Tsai, Candace Su-Jung; Woskie, Susan R.; Bennett, James S.; Garcia, Alberto; Ellenbecker, Michael J.

2015-01-01

The most commonly reported control used to minimize workplace exposures to nanomaterials is the chemical fume hood. Studies have shown, however, that significant releases of nanoparticles can occur when materials are handled inside fume hoods. This study evaluated the performance of a new commercially available nano fume hood using three different test protocols. Tracer gas, tracer nanoparticle, and nanopowder handling protocols were used to evaluate the hood. A static test procedure using tracer gas (sulfur hexafluoride) and nanoparticles as well as an active test using an operator handling nanoalumina were conducted. A commercially available particle generator was used to produce sodium chloride tracer nanoparticles. Containment effectiveness was evaluated by sampling both in the breathing zone (BZ) of a mannequin and operator as well as across the hood opening. These containment tests were conducted across a range of hood face velocities (60, 80, and 100 feet/minute) and with the room ventilation system turned off and on. For the tracer gas and tracer nanoparticle tests, leakage was much more prominent on the left side of the hood (closest to the room supply air diffuser) although some leakage was noted on the right side and in the BZ sample locations. During the tracer gas and tracer nanoparticle tests, leakage was primarily noted when the room air conditioner was on for both the low and medium hood exhaust air flows. When the room air conditioner was turned off, the static tracer gas tests showed good containment across most test conditions. The tracer gas and nanoparticle test results were well correlated showing hood leakage under the same conditions and at the same sample locations. The impact of a room air conditioner was demonstrated with containment being adversely impacted during the use of room air ventilation. The tracer nanoparticle approach is a simple method requiring minimal setup and instrumentation. However, the method requires the reduction in background concentrations to allow for increased sensitivity. PMID:25175285

Evaluation of leakage from fume hoods using tracer gas, tracer nanoparticles and nanopowder handling test methodologies.

PubMed

Dunn, Kevin H; Tsai, Candace Su-Jung; Woskie, Susan R; Bennett, James S; Garcia, Alberto; Ellenbecker, Michael J

2014-01-01

The most commonly reported control used to minimize workplace exposures to nanomaterials is the chemical fume hood. Studies have shown, however, that significant releases of nanoparticles can occur when materials are handled inside fume hoods. This study evaluated the performance of a new commercially available nano fume hood using three different test protocols. Tracer gas, tracer nanoparticle, and nanopowder handling protocols were used to evaluate the hood. A static test procedure using tracer gas (sulfur hexafluoride) and nanoparticles as well as an active test using an operator handling nanoalumina were conducted. A commercially available particle generator was used to produce sodium chloride tracer nanoparticles. Containment effectiveness was evaluated by sampling both in the breathing zone (BZ) of a mannequin and operator as well as across the hood opening. These containment tests were conducted across a range of hood face velocities (60, 80, and 100 ft/min) and with the room ventilation system turned off and on. For the tracer gas and tracer nanoparticle tests, leakage was much more prominent on the left side of the hood (closest to the room supply air diffuser) although some leakage was noted on the right side and in the BZ sample locations. During the tracer gas and tracer nanoparticle tests, leakage was primarily noted when the room air conditioner was on for both the low and medium hood exhaust airflows. When the room air conditioner was turned off, the static tracer gas tests showed good containment across most test conditions. The tracer gas and nanoparticle test results were well correlated showing hood leakage under the same conditions and at the same sample locations. The impact of a room air conditioner was demonstrated with containment being adversely impacted during the use of room air ventilation. The tracer nanoparticle approach is a simple method requiring minimal setup and instrumentation. However, the method requires the reduction in background concentrations to allow for increased sensitivity.

Circadian Rhythms of Heart Rate and Locomotion After Treatment With Low-Dose Acetylcholinesterase Inhibitors

DTIC Science & Technology

2006-01-01

with pyridostigmine bromide (PB), a carbamate AChE by air conditioned vans and air-freight to the Laboratory inhibitor that does not cross the blood ...15. SUBJECT TERMS Nerve agents, sarin, pyridostigmine bromide, cerebral glucose utilization, cerebrovascular circulation, low dose cholinesterase ...March 2006" Accepted 12 May 2006 ABSTRACT: This study tested the hypothesis that repeated exposure to low levels of sarin, pyridostigmine bromide (PB

SYBR safeTM efficiently replaces ethidium bromide in Aspergillus fumigatus gene disruption.

PubMed

Canela, H M S; Takami, L A; Ferreira, M E S

2017-02-08

Invasive aspergillosis is a disease responsible for high mortality rates, caused mainly by Aspergillus fumigatus. The available drugs are limited and this disease continues to occur at an unacceptable frequency. Gene disruption is essential in the search for new drug targets. An efficient protocol for A. fumigatus gene disruption was described but it requires ethidium bromide, a genotoxic agent, for DNA staining. Therefore, the present study tested SYBR safe TM , a non-genotoxic DNA stain, in A. fumigatus gene disruption protocol. The chosen gene was cipC, which has already been disrupted successfully in our laboratory. A deletion cassette was constructed in Saccharomyces cerevisiae and used in A. fumigatus transformation. There was no statistical difference between the tested DNA stains. The success rate of S. cerevisiae transformation was 63.3% for ethidium bromide and 70% for SYBR safe TM . For A. fumigatus gene disruption, the success rate for ethidium bromide was 100 and 97% for SYBR safe TM . In conclusion, SYBR safe TM efficiently replaced ethidium bromide, making this dye a safe and efficient alternative for DNA staining in A. fumigatus gene disruption.

Application of multiple tracers (SF6 and chloride) to identify the transport by characteristics of contaminant at two separate contaminated sites

NASA Astrophysics Data System (ADS)

Lee, K. K.; Lee, S. S.; Kim, H. H.; Koh, E. H.; Kim, M. O.; Lee, K.; Kim, H. J.

2016-12-01

Multiple tracers were applied for source and pathway detection at two different sites. CO2 gas injected in the subsurface for a shallow-depth CO2 injection and leak test can be regarded as a potential contaminant source. Therefore, it is necessary to identify the migration pattern of CO2 gas. Also, at a DNAPL contaminated site, it is important to figure out the characteristics of plume evolution from the source zone. In this study, multiple tracers (SF6 and chloride) were used to evaluate the applicability of volatile and non-volatile tracers and to identify the characteristics of contaminant transport at each CO2 injection and leak test site and DNAPL contaminated site. Firstly, at the CO2 test site, multiple tracers were used to perform the single well push-drift-pull tracer test at total 3 specific depth zones. As results of tests, volatile and non-volatile tracers showed different mass recovery percentage. Most of chloride mass was recovered but less than half of SF6 mass was recovered due to volatile property. This means that only gaseous SF6 leak out to unsaturated zone. However, breakthrough curves of both tracers indicated similar peak time, effective porosity, and regional groundwater velocity. Also, at both contaminated sites, natural gradient tracer tests were performed with multiple tracers. With the results of natural gradient tracer test, it was possible to confirm the applicability of multiple tracers and to understand the contaminant transport in highly heterogeneous aquifer systems through the long-term monitoring of tracers. Acknowledgement: financial support was provided by the R&D Project on Environmental Management of Geologic CO2 Storage)" from the KEITI (Project Number: 2014001810003) and Korea Ministry of Environment as "The GAIA project (2014000540010)".

Ease of intubation: A randomized, double-blind study to compare two doses of rocuronium bromide for endotracheal intubation.

PubMed

Shukla, Aparna; Misra, Shilpi

2016-01-01

Clinical need for a nondepolarizing agent with a rapid onset time and a brief duration of action has led to the development of rocuronium bromide. The aim of this study was to evaluate optimal dose of rocuronium bromide for intubation and to compare the onset time, duration of action, intubating conditions, and hemodynamic effects of two doses of rocuronium bromide. A prospective, randomized, double-blind study. All the patients were divided in a randomized, double-blind fashion into two groups of twenty patients each. Group I patients received rocuronium bromide 0.6 mg/kg intravenously and intubated at 60 s, Group II patients received rocuronium bromide 0.9 mg/kg and intubated at 60 s. The neuromuscular block was assessed using single twitch stimulation of 0.1 Hz at adductor pollicis muscle of hand at every 10 s. The results were compiled and analyzed statistically using Chi-square test for qualitative data and Student's t -test for quantitative data. Time of onset was significantly shorter ( P < 0.01) and duration of action was prolonged ( P < 0.001) for Group II as compared to Group I. The intubating conditions were (excellent + good) in 100% patients of Group II and (excellent + good) in 80% of Group I. There was no significant change in pulse rate and mean arterial pressure from the baseline value after the administration of muscle relaxants in either of the two groups. Rocuronium bromide 0.9 mg/kg is a safer alternative to rocuronium bromide 0.6 mg/kg for endotracheal intubation with shorter time of onset and better intubating conditions.

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 fluvio-glacial deposits, retention of S-metolachlor and its ionic metabolites is low in column tests and high mobility was observed meaning these molecules are prone to reach groundwater.

Journal: Efficient Hydrologic Tracer-Test Design for Tracer-Mass Estimation and Sample Collection Frequency, 1 Method Development

EPA Science Inventory

Hydrological tracer testing is the most reliable diagnostic technique available for the determination of basic hydraulic and geometric parameters necessary for establishing operative solute-transport processes. Tracer-test design can be difficult because of a lack of prior knowl...

Emission of methyl bromide from biomass burning

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

Manoe, S.; Andreae, M.O.

1994-03-04

Bromine is, per atom, far more efficient than chlorine in destroying stratospheric ozone, and methyl bromide is the single largest source of stratospheric bromine. The two main previously known sources of this compound are emissions from the ocean and from the compound's use as an agricultural pesticide. Laboratory biomass combustion experiments showed that methyl bromide was emitted in the smoke from various fuels tested. Methyl bromide was also found in smoke plumes from wildfires in savannas, chaparral, and boreal forest. Global emissions of methyl bromide from biomass burning are estimated to be in the range of 10 to 50 gigagramsmore » per year, which is comparable to the amount produced by ocean emission and pesticide use and represents a major contribution ([approximately]30 percent) to the stratospheric bromine budget.« less

Transport and fate of estrogenic hormones in slurry-treated soil monoliths.

PubMed

Laegdsmand, Mette; Andersen, Henrik; Jacobsen, Ole Hørbye; Halling-Sørensen, Bent

2009-01-01

The naturally occurring hormones, such as 17-beta-estradiol, 17-alpha-estradiol, and estrone, present in livestock manure may have detrimental environmental effects if released into surface waters. In areas where manure application is intensive, estrogens have been found in surface waters in concentrations known to affect the endocrine system of fish and amphibians. How the estrogens reach the surface waters is unclear. To investigate whether leaching through the soil profile plays a significant role, we conducted leaching experiments on intact soil cores. Lysimeter soil monoliths (60 cm in diameter and 100 cm long) were excavated from two sites in Denmark (one loamy and one sandy soil). The soil monoliths were treated with pig slurry containing estrogenic hormones and amended with an estrogen tracer (17-alpha-ethinylestradiol) and a conservative tracer (bromide). 17-alpha-ethinylestradiol is a synthetic analog of 17-beta-estradiol with sorption characteristics and molecular structure similar to those of the naturally occurring estrogens in slurry. The monoliths were exposed to a short-term irrigation event (12 h) followed by a long-term semi-field experiment (16 wk), during which leaching of natural estrogens and tracers was followed. Estrogens from slurry were transported to a depth of 1 m in loamy soil and sandy soil. The estrogen concentrations in the leachate were at a level known to affect the endocrine system of aquatic organisms.

Journal: A Review of Some Tracer-Test Design Equations for ...

EPA Pesticide Factsheets

Determination of necessary tracer mass, initial sample-collection time, and subsequent sample-collection frequency are the three most difficult aspects to estimate for a proposed tracer test prior to conducting the tracer test. To facilitate tracer-mass estimation, 33 mass-estimation equations are reviewed here, 32 of which were evaluated using previously published tracer-test design examination parameters. Comparison of the results produced a wide range of estimated tracer mass, but no means is available by which one equation may be reasonably selected over the others. Each equation produces a simple approximation for tracer mass. Most of the equations are based primarily on estimates or measurements of discharge, transport distance, and suspected transport times. Although the basic field parameters commonly employed are appropriate for estimating tracer mass, the 33 equations are problematic in that they were all probably based on the original developers' experience in a particular field area and not necessarily on measured hydraulic parameters or solute-transport theory. Suggested sampling frequencies are typically based primarily on probable transport distance, but with little regard to expected travel times. This too is problematic in that tends to result in false negatives or data aliasing. Simulations from the recently developed efficient hydrologic tracer-test design methodology (EHTD) were compared with those obtained from 32 of the 33 published tracer-

The Effects of Subsurface Bioremediation on Soil Structure, Colloid Formation, and Contaminant Transport

NASA Astrophysics Data System (ADS)

Wang, Y.; Liang, X.; Zhuang, J.; Radosevich, M.

2016-12-01

Anaerobic bioremediation is widely applied to create anaerobic subsurface conditions designed to stimulate microorganisms that degrade organic contaminants and immobilize toxic metals in situ. Anaerobic conditions that accompany such techniques also promotes microbially mediated Fe(III)-oxide mineral reduction. The reduction of Fe(III) could potentially cause soil structure breakdown, formation of clay colloids, and alternation of soil surface chemical properties. These processes could then affect bioremediation and the migration of contaminants. Column experiments were conducted to investigate the impact of anaerobic bioreduction on soil structure, hydraulic properties, colloid formation, and transport of three tracers (bromide, DFBA, and silica shelled silver nanoparticles). Columns packed with inoculated water stable soil aggregates were placed in anaerobic glovebox, and artificial groundwater media was pumped into the columns to simulate anaerobic bioreduction process for four weeks. Decent amount of soluble Fe(II) accompanied by colloids were detected in the effluent from bioreduction columns a week after initiation of bioreduction treatment, which demonstrated bioreduction of Fe(III) and formation of colloids. Transport experiments were performed in the columns before and after bioreduction process to assess the changes of hydraulic and surface chemical properties through bioreduction treatment. Earlier breakthrough of bromide and DFBA after treatment indicated alterations in flow paths (formation of preferential flow paths). Less dispersion of bromide and DFBA, and less tailing of DFBA after treatment implied breakdown of soil aggregates. Dramatically enhanced transport and early breakthrough of silica shelled silver nanoparticles after treatment supported the above conclusion of alterations in flow paths, and indicated changes of soil surface chemical properties.

Colorimetric susceptibility testing for Aspergillus fumigatus: comparison of menadione-augmented 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide and Alamar blue tests.

PubMed Central

Jahn, B; Stüben, A; Bhakdi, S

1996-01-01

Two colorimetric methods that use Alamar Blue or 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) for assaying the in vitro activities of antifungal agents have been described. We report that both tests performed similarly when the antifungal activity of amphotericin B against Candida albicans was determined. However, only the MTT test generated interpretable data when Aspergillus fumigatus was used. PMID:8818910

Preferential flow and pesticide transport in a clay-rich till: Field, laboratory, and modeling analysis

NASA Astrophysics Data System (ADS)

JøRgensen, Peter R.; Hoffmann, Martin; Kistrup, Jens P.; Bryde, Claus; Bossi, Rossana; Villholth, Karen G.

2002-11-01

This study investigates vertical flow and pesticide transport along fractures in water saturated unoxidized clayey till. From two experimental fields, each 40 m2, 96% and 98%, respectively, of total vertical flow was conducted along fractures in the till, while the remaining 2-4% of flow occurred in the clay matrix at very slow flow rate. An applied dye tracer was observed only along 10-26% of the total fracture length measured on the horizontal surface of the experimental fields. In vertical sections the dyed fracture portions constituted root channels, which penetrated the till vertically along the fractures into the local aquifer at 5 m depth. No dye tracer was observed in the fractures without root channels or in the unfractured clay matrix, suggesting that root growth along the fracture surfaces was the principal agent of fracture aperture enhancement. Using hydraulic fracture aperture values determined from large undisturbed column (LUC) collected from one of the experimental fields, it was estimated that 94% of flow in the fractures was conducted along the fracture root channels, while only 6% of flow was conducted along the fracture sections without root channels. For natural vertical hydraulic gradients (0.8-2.3 at the site), flow rates of 0.8-2 km/d were determined for a fracture root channel, while fracture sections without root channels revealed flow rates of 9-22 m/d. Corresponding flow rates in the unfractured matrix were 7-19 mm/yr. For infiltrated bromide (nonreactive tracer) and mobile pesticides mecoprop (MCPP) and metsulfuron, very rapid migration (0.28-0.5 m/d) and high relative breakthrough concentrations (30-60%) into the aquifer were observed to occur along the fracture root channels using a constant hydraulic gradient of 1. Only traces were measured from infiltration of the strongly sorbed pesticide prochloraz. The concentrations of the bromide and pesticides in the monitoring wells were modeled with a discrete fracture matrix diffusion (DFDM) model coupled with a single porosity model (SP) for the till and aquifer, respectively. Using effective fracture spacings and mean fracture apertures for the fracture channel sections as modeling input parameters for the till, the concentrations observed in the wells of the aquifer could be reasonably approximated.

Prototype of a low cost multiparameter probe

NASA Astrophysics Data System (ADS)

Koski, K.; Schwingle, R.; Pullin, M.

2010-12-01

Commercial multi-parameter probes provide accurate, high-resolution temporal data collection of a variety of water quality parameters, but their cost (>5,000) prohibits more than a few sampling locations. We present a design and prototype for a low cost (<250) probe. The cost of the probe is ~5% of commercially available probes, allowing for data collection from ~20 times more sampling points in a field location. The probe is constructed from a single-board microcontroller, a commercially available temperature sensor, a conductivity sensor, and a fabricated optical rhodamine sensor. Using a secure digital (SD) memory card, the probe can record over a month of data at a user specified interval. Construction, calibration, field deployment and data retrieval can be accomplished by a skilled undergraduate. Initial deployment will take place as part of a tracer test in the Valles Caldera National Preserve in northern New Mexico. Future work includes: addition of commercial ion selective electrodes (pH, bromide, nitrate, and others); construction of optically based sensors (chlorophyll, dissolved oxygen, and others); wireless networking between the sensors; and reduction of biofouling.

Innovative techniques for the description of reservoir heterogeneity using tracers. Second technical annual progress report, October 1991--September 1992

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

Pope, G.A.; Sepehrnoori, K.

1992-12-31

This second annual report on innovative uses of tracers for reservoir characterization contains four sections each describing a novel use of oilfield tracers. The first section describes and illustrates the use of a new single-well tracer test to estimate wettability. This test consists of the injection of brine containing tracers followed by oil containing tracers, a shut-in period to allow some of the tracers to react, and then production of the tracers. The inclusion of the oil injection slug with tracers is unique to this test, and this is what makes the test work. We adapted our chemical simulator, UTCHEM,more » to enable us to study this tracer method and made an extensive simulation study to evaluate the effects of wettability based upon characteristic curves for relative permeability and capillary pressure for differing wetting states typical of oil reservoirs. The second section of this report describes a new method for analyzing interwell tracer data based upon a type-curve approach. Theoretical frequency response functions were used to build type curves of ``transfer function`` and ``phase spectrum`` that have dimensionless heterogeneity index as a parameter to characterize a stochastic permeability field. We illustrate this method by analyzing field tracer data. The third section of this report describes a new theory for interpreting interwell tracer data in terms of channeling and dispersive behavior for reservoirs. Once again, a stochastic approach to reservoir description is taken. The fourth section of this report describes our simulation of perfluorocarbon gas tracers. This new tracer technology developed at Brookhaven National Laboratory is being tested at the Elk Hills Naval Petroleum Reserve No. 1 in California. We report preliminary simulations made of these tracers in one of the oil reservoirs under evaluation with these tracers in this field. Our compostional simulator (UTCOMP) was used for this simulation study.« less

Lanthanide-labeled clay: A new method for tracing sediment transport in Karst

USGS Publications Warehouse

Mahler, B.J.; Bennett, P.C.; Zimmerman, M.

1998-01-01

Mobile sediment is a fundamental yet poorly characterized aspect of mass transport through karst aquifers. Here the development and field testing of an extremely sensitive particle tracer that may be used to characterize sediment transport in karst aquifers is described. The tracer consists of micron-size montmorillonite particles homoionized to the lanthanide form; after injection and retrieval from a ground water system, the lanthanide ions are chemically stripped from the clay and quantified by high performance liquid chromatography. The tracer meets the following desired criteria: low detection limit; a number of differentiable signatures; inexpensive production and quantification using standard methods; no environmental risks; and hydrodynamic properties similar to the in situ sediment it is designed to trace. The tracer was tested in laboratory batch experiments and field tested in both surface water and ground water systems. In surface water, arrival times of the tracer were similar to those of a conservative water tracer, although a significant amount of material was lost due to settling. Two tracer tests were undertaken in a karst aquifer under different flow conditions. Under normal flow conditions, the time of arrival and peak concentration of the tracer were similar to or preceded that of a conservative water tracer. Under low flow conditions, the particle tracer was not detected, suggesting that in low flow the sediment settles out of suspension and goes into storage.Mobile sediment is a fundamental yet poorly characterized aspect of mass transport through karst aquifers. Here the development and field testing of an extremely sensitive particle tracer that may be used to characterize sediment transport in karst aquifers is described. The tracer consists of micron-size montmorillonite particles homoionized to the lanthanide form; after injection and retrieval from a ground water system, the lanthanide ions are chemically stripped from the clay and quantified by high performance liquid chromatography. The tracer meets the following desired criteria: low detection limit; a number of differentiable signatures; inexpensive production and quantification using standard methods; no environmental risks; and hydrodynamic properties similar to the in situ sediment it is designed to trace. The tracer was tested in laboratory batch experiments and field tested in both surface water and ground water systems. In surface water, arrival times of the tracer were similar to those of a conservative water tracer, although a significant amount of material was lost due to settling. Two tracer tests were undertaken in a karst aquifer under different flow conditions. Under normal flow conditions, the time of arrival and peak concentration of the tracer were similar to or preceded that of a conservative water tracer. Under low flow conditions, the particle tracer was not detected, suggesting that in low flow the sediment settles out of suspension and goes into storage.

Using noble gas tracers to estimate residual CO2 saturation in the field: results from the CO2CRC Otway residual saturation and dissolution test

NASA Astrophysics Data System (ADS)

LaForce, T.; Ennis-King, J.; Paterson, L.

2013-12-01

Residual CO2 saturation is a critically important parameter in CO2 storage as it can have a large impact on the available secure storage volume and post-injection CO2 migration. A suite of single-well tests to measure residual trapping was conducted at the Otway test site in Victoria, Australia during 2011. One or more of these tests could be conducted at a prospective CO2 storage site before large-scale injection. The test involved injection of 150 tonnes of pure carbon dioxide followed by 454 tonnes of CO2-saturated formation water to drive the carbon dioxide to residual saturation. This work presents a brief overview of the full test sequence, followed by the analysis and interpretation of the tests using noble gas tracers. Prior to CO2 injection krypton (Kr) and xenon (Xe) tracers were injected and back-produced to characterise the aquifer under single-phase conditions. After CO2 had been driven to residual the two tracers were injected and produced again. The noble gases act as non-partitioning aqueous-phase tracers in the undisturbed aquifer and as partitioning tracers in the presence of residual CO2. To estimate residual saturation from the tracer test data a one-dimensional radial model of the near-well region is used. In the model there are only two independent parameters: the apparent dispersivity of each tracer and the residual CO2 saturation. Independent analysis of the Kr and Xe tracer production curves gives the same estimate of residual saturation to within the accuracy of the method. Furthermore the residual from the noble gas tracer tests is consistent with other measurements in the sequence of tests.

Colloid facilitated transport of lanthanides through discrete fractures in chalk

NASA Astrophysics Data System (ADS)

Tran, Emily; Klein Ben-David, Ofra; Teutsch, Nadya; Weisbrod, Noam

2015-04-01

Geological disposal of high-level radioactive waste is the internationally agreed-upon, long term solution for the disposal of long lived radionuclides and spent fuel. Eventually, corrosion of the waste canisters may lead to leakage of their hazardous contents, and the radionuclides can ultimately make their way into groundwater and pose a threat to the biosphere. Engineered bentonite barriers placed around nuclear waste repositories are generally considered sufficient to impede the transport of radionuclides from their storage location to the groundwater. However, colloidal-sized mobile bentonite particles eroding from these barriers have come under investigation as a potential transport vector for radionuclides sorbed to them. In addition, the presence of organic matter in groundwater has been shown to additionally facilitate the uptake of radionuclides by the clay colloids. This study aims to evaluate the transport behaviors of radionuclides in colloid-facilitated transport through a fractured chalk matrix and under geochemical conditions representative of the Negev desert, Israel. Lanthanides are considered an acceptable substitute to actinides for research on radionuclide transportation due to their similar chemical behavior. In this study, the migration of Ce both with and without colloidal particles was explored and compared to the migration of a conservative tracer (bromide). Tracer solutions containing known concentrations of Ce, bentonite colloids, humic acid and bromide were prepared in a matrix solution containing salt concentrations representative of that of the average rain water found in the Negev. These solutions were then injected into a flow system constructed around a naturally fractured chalk core. Samples were analyzed for Ce and Br using ICP-MS, and colloid concentrations were determined using spectrophotographic analysis. Breakthrough curves comparing the rates of transportation of each tracer were obtained, allowing for comparison of transport rates and calculation of overall tracer recovery. Preliminary results suggest that mobility of Ce as a solute is negligible, and in experiments conducted without bentonite colloids, the 2% of the Ce that was recovered during the experiments travelled as "intrinsic" colloids in the form of Ce2(CO3)3-6H2O precipitate. However, the total recovery of the Ce increased to 9% when it was injected into the core in the presence of bentonite colloids and 13% when both bentonite and the carbonate precipitate colloids were injected. In addition, the maximum relative concentration (C/C0) of the Ce in the samples from the experiments conducted without bentonite colloids is about 0.002, whereas that of the experiments conducted in the presence of bentonite colloids reaches almost 0.2. This indicates that colloid presence does indeed markedly increase the mobility of radionuclides through fractured chalk matrices and should therefore be considered in models representing transport of radionuclide waste originating from nuclear repositories.

Detection of water contamination from hydraulic fracturing wastewater: a μPAD for bromide analysis in natural waters.

PubMed

Loh, Leslie J; Bandara, Gayan C; Weber, Genevieve L; Remcho, Vincent T

2015-08-21

Due to the rapid expansion in hydraulic fracturing (fracking), there is a need for robust, portable and specific water analysis techniques. Early detection of contamination is crucial for the prevention of lasting environmental damage. Bromide can potentially function as an early indicator of water contamination by fracking waste, because there is a high concentration of bromide ions in fracking wastewaters. To facilitate this, a microfluidic paper-based analytical device (μPAD) has been developed and optimized for the quantitative colorimetric detection of bromide in water using a smartphone. A paper microfluidic platform offers the advantages of inexpensive fabrication, elimination of unstable wet reagents, portability and high adaptability for widespread distribution. These features make this assay an attractive option for a new field test for on-site determination of bromide.

Analysis of genotoxic activity of ketamine and rocuronium bromide using the somatic mutation and recombination test in Drosophila melanogaster.

PubMed

Koksal, Pakize Muge; Gürbüzel, Mehmet

2015-03-01

The present study evaluated the mutagenic and recombinogenic effects of two commonly used anesthetic agents, ketamine and rocuronium bromide, in medicine using the wing somatic mutation and recombination test (SMART) in Drosophila. The standard (ST) cross and the high-bioactivation (HB) cross with high sensitivity to procarcinogens and promutagens were used. The SMART test is based on the loss of heterozygosity, which occurs via various mechanisms, such as chromosome loss and deletion, half-translocation, mitotic recombination, mutation, and non-disjunction. Genetic alterations occurring in the somatic cells of the wing's imaginal discs result in mutant clones in the wing blade. Three-day-old trans-heterozygous larvae with two recessive markers, multiple wing hairs (mwh) and flare (flr(3)), were treated with ketamine and rocuronium bromide. Analysis of the ST cross indicated that ketamine exhibited genotoxicity activity and that this activity was particularly dependent on homologous mitotic recombination at concentrations of 250 μg/ml and above. Rocuronium bromide did not exert mutagenic and/or recombinogenic effects. In the HB cross, ketamine at a concentration of 1000 μg/ml and rocuronium bromide at all concentrations, with the exception of 250 μg/ml (inconclusive), exerted genotoxic effects, which could also be associated with the increase in mitotic recombination. Copyright © 2015 Elsevier B.V. All rights reserved.

Fractured-rock hydrogeophysics with electrically conductive and neutrally buoyant tracers

NASA Astrophysics Data System (ADS)

Shakas, A.; Linde, N.; Baron, L.; Le Borgne, T.; Bour, O.; Lavenant, N.; Gerard, M. F.

2016-12-01

Artificial tracer tests help to characterize and understand the dynamics of groundwater systems. This remains a challenging task, especially when dealing with highly heterogeneous formations in which flow can be very localized and the interpretation of tracer breakthrough curves may be ambiguous. As a complement to tracer tests, ground-penetrating radar (GPR) and electrical resistivity tomography can map the space-time migration of electrically conductive tracers. In hydrogeophysics, the most common tracer is dissolved table salt in water. However, conventional salt tracers lead to density effects that are often ignored. Even less than 1% density variations can have a dramatic effect on transport behavior and affect tracer tests in complex ways. Such effects have been demonstrated in our previous experiments that used single-hole GPR to monitor saline push-pull tests in fractured granite. It is possible to model density effects, but this leads to computational complexity and field dynamics that are not necessarily representative of the natural responses of the system. To minimize density effects, we performed a new set of push-pull tests using a neutrally buoyant and electrically conductive tracer at the same test site located close to Ploemeur, France. This novel tracer consists of a mixture of salt (NaCl), water and pure ethanol. Ethanol has a density of 789 g/L at 20° C and is used to counter-act the salt-induced density increase. Our GPR time-lapse images and tracer breakthrough data indicate a largely reversible transport process that confirms the neutral buoyancy of the tracer. Ethanol is biodegradable and does not pose significant environmental issues. Furthermore, calibration of the neutral-buoyant mixture is straightforward to perform in the field using Archimedes principle. Based on these results, we argue that neutrally buoyant ethanol-salt-water mixtures are ideal for a wide variety of hydrogeophysical tracer tests in porous or fractured media.

Ambiguity in measuring matrix diffusion with single-well injection/recovery tracer tests

USGS Publications Warehouse

Lessoff, S.C.; Konikow, Leonard F.

1997-01-01

Single-well injection/recovery tracer tests are considered for use in characterizing and quantifying matrix diffusion in dual-porosity aquifers. Numerical modeling indicates that neither regional drift in homogeneous aquifers, nor heterogeneity in aquifers having no regional drift, nor hydrodynamic dispersion significantly affects these tests. However, when drift is coupled simultaneously with heterogeneity, they can have significant confounding effects on tracer return. This synergistic effect of drift and heterogeneity may help explain irreversible flow and inconsistent results sometimes encountered in previous single-well injection/recovery tracer tests. Numerical results indicate that in a hypothetical single-well injection/recovery tracer test designed to demonstrate and measure dual-porosity characteristics in a fractured dolomite, the simultaneous effects of drift and heterogeneity sometimes yields responses similar to those anticipated in a homogeneous dual-porosity formation. In these cases, tracer recovery could provide a false indication of the occurrence of matrix diffusion. Shortening the shut-in period between injection and recovery periods may make the test less sensitive to drift. Using multiple tracers having different diffusion characteristics, multiple tests having different pumping schedules, and testing the formation at more than one location would decrease the ambiguity in the interpretation of test data.

Chloride and bromide sources in water: Quantitative model use and uncertainty

NASA Astrophysics Data System (ADS)

Horner, Kyle N.; Short, Michael A.; McPhail, D. C.

2017-06-01

Dissolved chloride is a commonly used geochemical tracer in hydrological studies. Assumptions underlying many chloride-based tracer methods do not hold where processes such as halide-bearing mineral dissolution, fluid mixing, or diffusion modify dissolved Cl- concentrations. Failure to identify, quantify, or correct such processes can introduce significant uncertainty to chloride-based tracer calculations. Mass balance or isotopic techniques offer a means to address this uncertainty, however, concurrent evaporation or transpiration can complicate corrections. In this study Cl/Br ratios are used to derive equations that can be used to correct a solution's total dissolved Cl- and Br- concentration for inputs from mineral dissolution and/or binary mixing. We demonstrate the equations' applicability to waters modified by evapotranspiration. The equations can be used to quickly determine the maximum proportion of dissolved Cl- and Br- from each end-member, providing no halide-bearing minerals have precipitated and the Cl/Br ratio of each end member is known. This allows rapid evaluation of halite dissolution or binary mixing contributions to total dissolved Cl- and Br-. Equation sensitivity to heterogeneity and analytical uncertainty is demonstrated through bench-top experiments simulating halite dissolution and variable degrees of evapotranspiration, as commonly occur in arid environments. The predictions agree with the experimental results to within 6% and typically much less, with the sensitivity of the predicted results varying as a function of end-member compositions and analytical uncertainty. Finally, we present a case-study illustrating how the equations presented here can be used to quantify Cl- and Br- sources and sinks in surface water and groundwater and how the equations can be applied to constrain uncertainty in chloride-based tracer calculations.

Nitrous oxide as a tracer gas in the ASHRAE 110-1995 Standard.

PubMed

Burke, Martin; Wong, Larry; Gonzales, Ben A; Knutson, Gerhard

2014-01-01

ANSI/ASHRAE Standard 110 provides a quantitative method for testing the performance of laboratory fume hoods. Through release of a known quantity (4.0 Lpm) of a tracer gas, and subsequent monitoring of the tracer gas concentration in the "breathing zone" of a mannequin positioned in front of the hood, this method allows for evaluation of laboratory hood performance. Standard 110 specifies sulfur hexafluoride (SF6) as the tracer gas; however, suitable alternatives are allowed. Through three series of performance tests, this analysis serves to investigate the use of nitrous oxide (N2O) as an alternate tracer gas for hood performance testing. Single gas tests were performed according to ASHRAE Standard 110-1995 with each tracer gas individually. These tests showed identical results using an acceptance criterion of AU 0.1 with the sash half open, nominal 18 inches (0.46m) high, and the face velocity at a nominal 60 fpm (0.3 m/s). Most data collected in these single gas tests, for both tracer gases, were below the minimum detection limit, thus two dual gas tests were developed for simultaneous sampling of both tracer gases. Dual gas dual ejector tests were performed with both tracer gases released simultaneously through two ejectors, and the concentration measured with two detectors using a common sampling probe. Dual gas single ejector tests were performed with both tracer gases released though a single ejector, and the concentration measured in the same manner as the dual gas dual ejector tests. The dual gas dual ejector tests showed excellent correlation, with R typically greater than 0.9. Variance was observed in the resulting regression line for each hood, likely due to non-symmetry between the two challenges caused by variables beyond the control of the investigators. Dual gas single ejector tests resulted in exceptional correlation, with R>0.99 typically for the consolidated data, with a slope of 1.0. These data indicate equivalent results for ASHRAE 110 performance testing using either SF6 or N2O, indicating N2O as an applicable alternate tracer gas.

Tracer-Test Planning Using the Efficient Hydrologic Tracer ...

EPA Pesticide Factsheets

Hydrological tracer testing is the most reliable diagnostic technique available for establishing flow trajectories and hydrologic connections and for determining basic hydraulic and geometric parameters necessary for establishing operative solute-transport processes. Tracer-test design can be difficult because of a lack of prior knowledge of the basic hydraulic and geometric parameters desired and the appropriate tracer mass to release. A new efficient hydrologic tracer-test design (EHTD) methodology has been developed that combines basic measured field parameters (e.g., discharge, distance, cross-sectional area) in functional relationships that describe solute-transport processes related to flow velocity and time of travel. The new method applies these initial estimates for time of travel and velocity to a hypothetical continuously stirred tank reactor as an analog for the hydrologic flow system to develop initial estimates for tracer concentration and axial dispersion, based on a preset average tracer concentration. Root determination of the one-dimensional advection-dispersion equation (ADE) using the preset average tracer concentration then provides a theoretical basis for an estimate of necessary tracer mass.Application of the predicted tracer mass with the hydraulic and geometric parameters in the ADE allows for an approximation of initial sample-collection time and subsequent sample-collection frequency where a maximum of 65 samples were determined to be

Temperature dependence of chloride, bromide, iodide, thiocyanate and salicylate transport in human red cells

PubMed Central

Dalmark, Mads; Wieth, Jens Otto

1972-01-01

1. The temperature dependence of the steady-state self-exchange of chloride between human red cells and a plasma-like electrolyte medium has been studied by measuring the rate of 36Cl- efflux from radioactively labelled cells. Between 0 and 10° C the rate increased by a factor of eight corresponding to an Arrhenius activation energy of 33 kcal/mole. 2. The rate of chloride exchange decreased significantly in experiments where 95% of the chloride ions in cells and medium were replaced by other monovalent anions of a lyotropic series. The rate of chloride self-exchange was increasingly reduced by bromide, bicarbonate, nitrate, iodide, thiocyanate, and salicylate. The latter aromatic anion was by far the most potent inhibitor, reducing the rate of chloride self-exchange to 0·2% of the value found in a chloride medium. 3. The temperature sensitivity of the chloride self-exchange was not affected significantly by the anionic inhibitors. The Arrhenius activation energies of chloride exchange were between 30 and 40 kcal/mole in the presence of the six inhibitory anions mentioned above. 4. The rate of self-exchange of bromide, thiocyanate, and iodide between human red cells and media was determined after washing and labelling cells in media containing 120 mM bromide, thiocyanate, or iodide respectively. The rate of self-exchange of the three anions were 12, 3, and 0·4% of the rate of chloride self-exchange found in the chloride medium. 5. The Arrhenius activation energies of the self-exchange of bromide, iodide, and thiocyanate were all between 29 and 37 kcal/mole, the same magnitude as found for the self-exchange of chloride. 6. Although approximately 40% of the intracellular iodide and salicylate ions appeared to be adsorbed to intracellular proteins, the rate of tracer anion efflux followed first order kinetics until at least 98% of the intracellular anions had been exchanged. 7. The self-exchange of salicylate across the human red cell membrane occurred by a different mechanism than the one utilized by the inorganic monovalent anions. The activation energy of salicylate exchange (13·2 kcal/mole) was significantly lower than that of inorganic anion exchange. Salicylate exchange increased with decreasing pH in contrast to the exchange of chloride, which decreases when pH is lowered. PMID:5071931

Three-Dimensional Bayesian Geostatistical Aquifer Characterization at the Hanford 300 Area using Tracer Test Data

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

Chen, Xingyuan; Murakami, Haruko; Hahn, Melanie S.

2012-06-01

Tracer testing under natural or forced gradient flow holds the potential to provide useful information for characterizing subsurface properties, through monitoring, modeling and interpretation of the tracer plume migration in an aquifer. Non-reactive tracer experiments were conducted at the Hanford 300 Area, along with constant-rate injection tests and electromagnetic borehole flowmeter (EBF) profiling. A Bayesian data assimilation technique, the method of anchored distributions (MAD) [Rubin et al., 2010], was applied to assimilate the experimental tracer test data with the other types of data and to infer the three-dimensional heterogeneous structure of the hydraulic conductivity in the saturated zone of themore » Hanford formation. In this study, the Bayesian prior information on the underlying random hydraulic conductivity field was obtained from previous field characterization efforts using the constant-rate injection tests and the EBF data. The posterior distribution of the conductivity field was obtained by further conditioning the field on the temporal moments of tracer breakthrough curves at various observation wells. MAD was implemented with the massively-parallel three-dimensional flow and transport code PFLOTRAN to cope with the highly transient flow boundary conditions at the site and to meet the computational demands of MAD. A synthetic study proved that the proposed method could effectively invert tracer test data to capture the essential spatial heterogeneity of the three-dimensional hydraulic conductivity field. Application of MAD to actual field data shows that the hydrogeological model, when conditioned on the tracer test data, can reproduce the tracer transport behavior better than the field characterized without the tracer test data. This study successfully demonstrates that MAD can sequentially assimilate multi-scale multi-type field data through a consistent Bayesian framework.« less

Methyl bromide as a microbicidal fumigant for tree nuts.

PubMed Central

Schade, J E; King, A D

1977-01-01

Methyl bromide (MeBr) has broad microbicidal activity, but its use as a disinfectant for food is limited by the resulting bromide residues. Increasing the MeBr concentration, exposure temperature, or exposure period of a treatment tended to increase both the microbicidal efficacy of MeBr and the bromide residues. Its sporicidal activity was less at high than at low relative humidity within the range of 20 to 99%. Both the efficacy and the resulting residues of a MeBr treatment varied inversely with the load of product in a fumigation chamber due to sorption of the fumigant. Fumigation tests with almond kernels inoculated with Escherichia coli or Salmonella typhimurium indicated that MeBr can be used to disinfect whole nut kernels without resulting in excessive bromide residues, although the MeBr level necessary is higher than that normally used for insect control. PMID:406844

AN INTEGRATED APPROACH TO CHARACTERIZING BYPASSED OIL IN HETEROGENEOUS AND FRACTURED RESERVOIRS USING PARTITIONING TRACERS

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

Akhil Datta-Gupta

2003-08-01

We explore the use of efficient streamline-based simulation approaches for modeling partitioning interwell tracer tests in hydrocarbon reservoirs. Specifically, we utilize the unique features of streamline models to develop an efficient approach for interpretation and history matching of field tracer response. A critical aspect here is the underdetermined and highly ill-posed nature of the associated inverse problems. We have adopted an integrated approach whereby we combine data from multiple sources to minimize the uncertainty and non-uniqueness in the interpreted results. For partitioning interwell tracer tests, these are primarily the distribution of reservoir permeability and oil saturation distribution. A novel approachmore » to multiscale data integration using Markov Random Fields (MRF) has been developed to integrate static data sources from the reservoir such as core, well log and 3-D seismic data. We have also explored the use of a finite difference reservoir simulator, UTCHEM, for field-scale design and optimization of partitioning interwell tracer tests. The finite-difference model allows us to include detailed physics associated with reactive tracer transport, particularly those related with transverse and cross-streamline mechanisms. We have investigated the potential use of downhole tracer samplers and also the use of natural tracers for the design of partitioning tracer tests. Finally, the behavior of partitioning tracer tests in fractured reservoirs is investigated using a dual-porosity finite-difference model.« less

Using Noble Gas Tracers to Estimate CO2 Saturation in the Field: Results from the 2014 CO2CRC Otway Repeat Residual Saturation Test

NASA Astrophysics Data System (ADS)

LaForce, T.; Ennis-King, J.; Boreham, C.; Serno, S.; Cook, P. J.; Freifeld, B. M.; Gilfillan, S.; Jarrett, A.; Johnson, G.; Myers, M.; Paterson, L.

2015-12-01

Residual trapping efficiency is a critical parameter in the design of secure subsurface CO2 storage. Residual saturation is also a key parameter in oil and gas production when a field is under consideration for enhanced oil recovery. Tracers are an important tool that can be used to estimate saturation in field tests. A series of measurements of CO2 saturation in an aquifer were undertaken as part of the Otway stage 2B extension field project in Dec. 2014. These tests were a repeat of similar tests in the same well in 2011 with improvements to the data collection and handling method. Two single-well tracer tests using noble gas tracers were conducted. In the first test krypton and xenon are injected into the water-saturated formation to establish dispersivity of the tracers in single-phase flow. Near-residual CO2 saturation is then established near the well. In the second test krypton and xenon are injected with CO2-saturated water to measure the final CO2 saturation. The recovery rate of the tracers is similar to predicted rates using recently published partitioning coefficients. Due to technical difficulties, there was mobile CO2 in the reservoir throughout the second tracer test in 2014. As a consequence, it is necessary to use a variation of the previous simulation procedure to interpret the second tracer test. One-dimensional, radial simulations are used to estimate average saturation of CO2 near the well. Estimates of final average CO2 saturation are computed using two relative permeability models, thermal and isothermal simulations, and three sets of coefficients for the partitioning of the tracers between phases. Four of the partitioning coefficients used were not previously available in the literature. The noble gas tracer field test and analysis of the 2011 and 2014 data both give an average CO2 saturation that is consistent with other field measurements. This study has demonstrated the repeatability of the methodology for noble gas tracer tests in the field.

Tracer Tests in the Fractured Rock to Investigate Preferential Groundwater Flow

NASA Astrophysics Data System (ADS)

Chan, W.; Chung, L.; Lee, T.; Liu, C.; Chia, Y.; Teng, M.

2012-12-01

Hydraulic tests are often used to obtain hydraulic conductivity in the aquifer. Test results usually reflect the average hydraulic conductivity in the surrounding strat. However, in fractured rock, groundwater flows primarily through a few fractures. Saltwater tracer test can be used to detect the direction of groundwater flow, but it was difficult to know the hydraulic connectivity between fractures. In this study, we use a variety of field tests, including tracer test, hydraulic test, and heat-pulse flowmeter test, to locate the permeable fractures and detect the hydraulic connections between boreholes. There are eight test wells and two observation wells on field experimental site in central Taiwan. Geological survey results show that there are at least three sets of joint planes. In order to realize the location of the preferential pathway of groundwater flow, heat-pulse flowmeter measurement was adopted to identify the depth of permeable fractures. Multi-well pumping test was also performed to investigate the hydraulic connectivity between these wells. Tracer tests were then used to detect the hydraulic connectivity of permeable fractures between two wells. Injection of nano zero valent iron in one well and and collection of iron tracer with a magnet array in the other well can specifically locate the permeable fracture and determine the connectivity. Saltwater tracer test result can be used to support that of nano-iron tracer test, and verify the relationship between well water conductivity increases and rock fracture location. The results show that tracer test is a useful tool to investigate the preferential groundwater flow in the fractured rock, but it is essential to flush the mud in fractures prior to the test.

EFFICIENT HYDROLOGICAL TRACER-TEST DESIGN (EHTD ...

EPA Pesticide Factsheets

Hydrological tracer testing is the most reliable diagnostic technique available for establishing flow trajectories and hydrologic connections and for determining basic hydraulic and geometric parameters necessary for establishing operative solute-transport processes. Tracer-test design can be difficult because of a lack of prior knowledge of the basic hydraulic and geometric parameters desired and the appropriate tracer mass to release. A new efficient hydrologic tracer-test design (EHTD) methodology has been developed that combines basic measured field parameters (e.g., discharge, distance, cross-sectional area) in functional relationships that describe solute-transport processes related to flow velocity and time of travel. The new method applies these initial estimates for time of travel and velocity to a hypothetical continuously stirred tank reactor as an analog for the hydrologic flow system to develop initial estimates for tracer concentration and axial dispersion, based on a preset average tracer concentration. Root determination of the one-dimensional advection-dispersion equation (ADE) using the preset average tracer concentration then provides a theoretical basis for an estimate of necessary tracer mass.Application of the predicted tracer mass with the hydraulic and geometric parameters in the ADE allows for an approximation of initial sample-collection time and subsequent sample-collection frequency where a maximum of 65 samples were determined to

Comparison of phenobarbital with bromide as a first-choice antiepileptic drug for treatment of epilepsy in dogs.

PubMed

Boothe, Dawn Merton; Dewey, Curtis; Carpenter, David Mark

2012-05-01

To compare efficacy and safety of treatment with phenobarbital or bromide as the first-choice antiepileptic drug (AED) in dogs. Double-blinded, randomized, parallel, clinical trial. 46 AED-naïve dogs with naturally occurring epilepsy. Study inclusion was based on age, history, findings on physical and neurologic examinations, and clinicopathologic test results. For either phenobarbital treatment (21 dogs) or bromide treatment (25), a 7-day loading dose period was initiated along with a maintenance dose, which was adjusted on the basis of monthly monitoring. Efficacy and safety outcomes were compared between times (baseline and study end [generally 6 months]) and between drugs. Phenobarbital treatment resulted in eradication of seizures (17/20 [85%]) significantly more often than did bromide (12/23 [52%]); phenobarbital treatment also resulted in a greater percentage decrease in seizure duration (88 ± 34%), compared with bromide (49 ± 75%). Seizure activity worsened in 3 bromide-treated dogs only. In dogs with seizure eradication, mean ± SD serum phenobarbital concentration was 25 ± 6 μg/mL (phenobarbital dosage, 4.1 ± 1.1 mg/kg [1.9 ± 0.5 mg/lb], p.o., q 12 h) and mean serum bromide concentration was 1.8 ± 0.6 mg/mL (bromide dosage, 31 ± 11 mg/kg [14 ± 5 mg/lb], p.o., q 12 h). Ataxia, lethargy, and polydipsia were greater at 1 month for phenobarbital-treated dogs; vomiting was greater for bromide-treated dogs at 1 month and study end. Both phenobarbital and bromide were reasonable first-choice AEDs for dogs, but phenobarbital was more effective and better tolerated during the first 6 months of treatment.

A Multiple-Tracer Approach for Identifying Sewage Sources to an Urban Stream System

USGS Publications Warehouse

Hyer, Kenneth Edward

2007-01-01

The presence of human-derived fecal coliform bacteria (sewage) in streams and rivers is recognized as a human health hazard. The source of these human-derived bacteria, however, is often difficult to identify and eliminate, because sewage can be delivered to streams through a variety of mechanisms, such as leaking sanitary sewers or private lateral lines, cross-connected pipes, straight pipes, sewer-line overflows, illicit dumping of septic waste, and vagrancy. A multiple-tracer study was conducted to identify site-specific sources of sewage in Accotink Creek, an urban stream in Fairfax County, Virginia, that is listed on the Commonwealth's priority list of impaired streams for violations of the fecal coliform bacteria standard. Beyond developing this multiple-tracer approach for locating sources of sewage inputs to Accotink Creek, the second objective of the study was to demonstrate how the multiple-tracer approach can be applied to other streams affected by sewage sources. The tracers used in this study were separated into indicator tracers, which are relatively simple and inexpensive to apply, and confirmatory tracers, which are relatively difficult and expensive to analyze. Indicator tracers include fecal coliform bacteria, surfactants, boron, chloride, chloride/bromide ratio, specific conductance, dissolved oxygen, turbidity, and water temperature. Confirmatory tracers include 13 organic compounds that are associated with human waste, including caffeine, cotinine, triclosan, a number of detergent metabolites, several fragrances, and several plasticizers. To identify sources of sewage to Accotink Creek, a detailed investigation of the Accotink Creek main channel, tributaries, and flowing storm drains was undertaken from 2001 to 2004. Sampling was conducted in a series of eight synoptic sampling events, each of which began at the most downstream site and extended upstream through the watershed and into the headwaters of each tributary. Using the synoptic sampling approach, 149 sites were sampled at least one time for indicator tracers; 52 of these sites also were sampled for confirmatory tracers at least one time. Through the analysis of multiple-tracer levels in the synoptic samples, three major sewage sources to the Accotink Creek stream network were identified, and several other minor sewage sources to the Accotink Creek system likely deserve additional investigation. Near the end of the synoptic sampling activities, three additional sampling methods were used to gain better understanding of the potential for sewage sources to the watershed. These additional sampling methods included optical brightener monitoring, intensive stream sampling using automated samplers, and additional sampling of several storm-drain networks. The samples obtained by these methods provided further understanding of possible sewage sources to the streams and a better understanding of the variability in the tracer concentrations at a given sampling site. Collectively, these additional sampling methods were a valuable complement to the synoptic sampling approach that was used for the bulk of this study. The study results provide an approach for local authorities to use in applying a relatively simple and inexpensive collection of tracers to locate sewage sources to streams. Although this multiple-tracer approach is effective in detecting sewage sources to streams, additional research is needed to better detect extremely low-volume sewage sources and better enable local authorities to identify the specific sources of the sewage once it is detected in a stream reach.

Dissipation of hydrological tracers and the herbicide S-metolachlor in batch and continuous-flow wetlands.

PubMed

Maillard, Elodie; Lange, Jens; Schreiber, Steffi; Dollinger, Jeanne; Herbstritt, Barbara; Millet, Maurice; Imfeld, Gwenaël

2016-02-01

Pesticide dissipation in wetland systems with regard to hydrological conditions and operational modes is poorly known. Here, we investigated in artificial wetlands the impact of batch versus continuous-flow modes on the dissipation of the chiral herbicide S-metolachlor (S-MET) and hydrological tracers (bromide, uranine and sulforhodamine B). The wetlands received water contaminated with the commercial formulation Mercantor Gold(®) (960 g L(-1) of S-MET, 87% of the S-enantiomer). The tracer mass budget revealed that plant uptake, sorption, photo- and presumably biodegradation were prominent under batch mode (i.e. characterized by alternating oxic-anoxic conditions), in agreement with large dissipation of S-MET (90%) under batch mode. Degradation was the main dissipation pathway of S-MET in the wetlands. The degradate metolachlor oxanilic acid (MOXA) mainly formed under batch mode, whereas metolachlor ethanesulfonic acid (MESA) prevailed under continuous-flow mode, suggesting distinct degradation pathways in each wetland. R-enantiomer was preferentially degraded under batch mode, which indicated enantioselective biodegradation. The release of MESA and MOXA by the wetlands as well as the potential persistence of S-MET compared to R-MET under both oxic and anoxic conditions may be relevant for groundwater and ecotoxicological risk assessment. This study shows the effect of batch versus continuous modes on pollutant dissipation in wetlands, and that alternate biogeochemical conditions under batch mode enhance S-MET biodegradation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effectiveness of methyl bromide as a cargo fumigant for brown treesnakes

USGS Publications Warehouse

Savarie, P.J.; Wood, W.S.; Rodda, G.H.; Bruggers, R.L.; Engeman, R.M.

2005-01-01

The effectiveness of methyl bromide as a fumigant for brown treesnake (Boiga irregularis) management was evaluated on Guam. Eighteen snakes in secured cloth bags were randomly positioned in a 47.7-m3 tarpaulin-covered cargo container for each fumigation treatment. Methyl bromide treatments tested were: 24 g m−3 and and 12 g m−3, both for 2-h and 1-h exposures. All treatments, except for 12 g m−3 for 1 h, resulted in 100% mortality. Two-hour exposures to methyl bromide at 24 and 12 g m−3 appear to be effective in killing brown treesnakes within reasonable time-frames for shippers under Guam field conditions.

Nano-scale zero valent iron transport in a variable aperture dolomite fracture and a glass fracture

NASA Astrophysics Data System (ADS)

Mondal, P.; Sleep, B. E.; Cui, Z.; Zhou, Z.

2014-12-01

Experiments and numerical simulations are being performed to understand the transport behavior of carboxymethyl cellulose polymer stabilized nano-scale zero valent iron (nZVI) in a variable aperture dolomite rock fracture and a variable aperture glass replica of a fractured slate. The rock fracture was prepared by artificially inducing a fracture in a dolomite block along a stylolite, and the glass fracture was prepared by creating molds with melted glass on two opposing sides of a fractured slate rock block. Both of the fractures were 0.28 m in length and 0.21 m in width. Equivalent hydraulic apertures are about 110 microns for the rock fracture and 250 microns for the glass replica fracture. Sodium bromide and lissamine green B (LGB) serve as conservative tracers in the rock fracture and glass replica fracture, respectively. A dark box set-up with a light source and digital camera is being used to visualize the LGB and CMC-nZVI movement in the glass fracture. Experiments are being performed to determine the effects of water specific discharge and CMC concentration on nZVI transport in the fractures. Transmission electron microscopy, dynamic light scattering, and UV-visual spectrophotometry were performed to determine the stability and characteristics of the CMC-nZVI mixture. The transport of bromide, LGB, CMC, and CMC-nZVI in both fractures is being evaluated through analysis of the effluent concentrations. Time-lapse images are also being captured for the glass fracture. Bromide, LGB, and CMC recoveries have exceeded 95% in both fractures. Significant channeling has been observed in the fractures for CMC transport due to viscous effects.

Pyridostimine Bromide 30mg Stability in Extended Storage Conditions

DTIC Science & Technology

2017-12-03

limit 100 words): Pyridostigmine bromide 30mg is approved by the Federal Drug Administration (FDA) as a pre -treatment of nerve gas exposure. The...under controlled temperatu,re and humidity. The tablets will be tested at 0, 3, 4, 5, and 6 months after removal from refrigerator when stored at both...Guidance definitions of storage conditions required for stability testing to obtain new drug approval in different climate zones in the world. At

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 aspects of flagellate transport behavior in groundwater.

Mixtures of Quaternary Ammonium Compounds and Long-chain Fatty Acids as Antifungal Agents

PubMed Central

Kull, F. C.; Eisman, P. C.; Sylwestrowicz, H. D.; Mayer, R. L.

1961-01-01

The influence of undecylenic acid on the fungistatic effect of phenoxyethyldimethyldodecylammonium bromide (Domiphen bromide) against Trichophyton mentagrophytes was investigated. The unsaturated fatty acid was found to enhance the fungistatic activity of Domiphen bromide against this organism. The ratio of concentrations of these agents has a marked influence on the results of in vitro tests for antifungal action resulting in a completely different effect than heretofore noted in combination experiments against bacteria. The enhancing phenomenon is not particular to T. mentagrophytes, it was observed also with Candida albicans. PMID:14460466

CO2CRC's Otway Residual Saturation and Dissolution Test: Using Reactive Ester Tracers to Determine Residual CO2 Saturation

NASA Astrophysics Data System (ADS)

Myers, M.; Stalker, L.; LaForce, T.; Pejcic, B.; Dyt, C.; Ho, K.; Ennis-King, J.

2013-12-01

Residual trapping, that is CO2 held in the rock pore space due to capillarity, is an important storage mechanism in geo-sequestration of over the short to medium term (up to 1000 years). As such residual CO2 saturation is a critical reservoir parameter for assessing the storage capacity and security of carbon capture and storage (CCS). As a component of the CO2CRC's Residual Gas Saturation and Dissolution Test at the CO2CRC Otway Project site in Victoria (Australia), we have recently tested a suite of reactive esters (triacetin, tripropionin and propylene glycol diacetate) in a single well chemical tracer test to determine residual CO2 saturation. The goal of this project was to assess and validate a suite of possible tests that could be implemented to determine residual CO2 saturation. For this test, the chemical tracers were injected with a saturated CO2/water mixture into the formation (that is already at residual CO2 saturation) where they were allowed to 'soak' for approximately 10 days allowing for the partial hydrolysis of the esters to their corresponding carboxylic acids and alcohols. Water containing the tracers was then produced from the well resulting in over 600 tracer samples over a period of 12 hours. A selection of these samples were analysed for tracer content and to establish tracer breakthrough curves. To understand the behaviour of these chemical tracers in the downhole environment containing residually trapped supercritical CO2 and formation water, it is necessary to determine the supercritical CO2/water partition coefficients. We have previously determined these in the laboratory (Myers et al., 2012) and they are used here to model the tracer behaviour and provide an estimate of the residual CO2 saturation. Two different computational simulators were used to analyse the tracer breakthrough profiles. The first is based on simple chromatographic retardation and has been used extensively in single well chemical tracer tests to determine residual oil saturation and the second is based on TOUGH2. The estimates of residual saturation given by these models were similar giving a very low residual CO2 saturation value. We suspect that this low value might be due to CO2 being inadvertently dissolved in the near wellbore region prior to this test. This possible dissolution of CO2 may be attributed to the complexity of the multi-test sequence (including other tracer tests prior to this particular test) used in the overall program at of the Residual Gas Saturation and Dissolution Test. References Myers, M., Stalker, L., Ross, A., Dyt, C., Ho, K.-B., 2012. Method for the determination of residual carbon dioxide saturation using reactive ester tracers. Applied Geochemistry 27, 2148-2156.

SIMULATIONS OF TWO-WELL TRACER TESTS IN STRATIFIED AQUIFERS AT THE CHALK RIVER AND THE MOBILE SITES

EPA Science Inventory

A simulation of two-well injection-withdrawal tracer tests in stratified granular aquifers is presented for two widely separated sites substantially different in terms of vertical distributions of hydraulic conductivity, well spacings, flow rates, test durations and tracer travel...

Containment testing of isolation rooms.

PubMed

Rydock, J P; Eian, P K

2004-07-01

Results from the tracer containment testing of four 'state-of-the-art' airborne infection isolation rooms, in a new hospital, are presented. A testing technician exited an isolation room several minutes after a small quantity of tracer gas was injected over the patient bed in that room. Easily measurable tracer gas concentrations were then found in the anterooms outside the patient rooms and corridor outside the isolation room suites. Containment factors for the isolation rooms and dilution factors in the anterooms and corridor were calculated, based on the measured tracer concentrations. These results indicate the desirability of evidence-based design standards and guidelines for assessing performance of airborne infection isolation rooms. The study also demonstrates that the tracer testing procedure yields comparable results for equivalent isolation room suites, suggesting good reproducibility of the testing method.

Multi-Scale Thermal Heat Tracer Tests for Characterizing Transport Processes and Flow Channelling in Fractured Media: Theory and Field Experiments

NASA Astrophysics Data System (ADS)

de La Bernardie, J.; Klepikova, M.; Bour, O.; Le Borgne, T.; Dentz, M.; Guihéneuf, N.; Gerard, M. F.; Lavenant, N.

2017-12-01

The characterization of flow and transport in fractured media is particularly challenging because hydraulic conductivity and transport properties are often strongly dependent on the geometric structure of the fracture surfaces. Here we show how thermal tracer tests may be an excellent complement to conservative solute tracer tests to infer fracture geometry and flow channeling. We performed a series of thermal tracer tests at different scales in a crystalline rock aquifer at the experimental site of Ploemeur (H+ observatory network). The first type of thermal tracer tests are push-pull tracer tests at different scales. The temporal and spatial scaling of heat recovery, measured from thermal breakthrough curves, shows a clear signature of flow channeling. In particular, the late time tailing of heat recovery under channeled flow is shown to diverge from the T(t) α t-1,5 behavior expected for the classical parallel plate model and follow the scaling T(t) α 1/t(logt)2 for a simple channel modeled as a tube. Flow channeling is also manifested on the spatial scaling of heat recovery as flow channeling affects the decay of the thermal breakthrough peak amplitude and the increase of the peak time with scale. The second type of thermal tracer tests are flow-through tracer tests where a pulse of hot water was injected in a fracture isolated by a double straddle packer while pumping at the same flow rate in another fracture at a distance of about 10 meters to create a dipole flow field. Comparison with a solute tracer test performed under the same conditions also present a clear signature of flow channeling. We derive analytical expressions for the retardation and decay of the thermal breakthrough peak amplitude for different fracture geometries and show that the observed differences between thermal and solute breakthrough can be explained only by channelized flow. These results suggest that heat transport is much more sensitive to fracture heterogeneity and flow channeling than conservative solute transport. These findings, which bring new insights on the effect of flow channeling on heat transfer in fractured rocks, show how heat recovery in geothermal systems may be controlled by fracture geometry. This highlights the interest of thermal tracer tests as a complement to solute tracers tests to infer fracture aperture and geometry.

Three-Dimensional Bayesian Geostatistical Aquifer Characterization at the Hanford 300 Area using Tracer Test Data

NASA Astrophysics Data System (ADS)

Chen, X.; Murakami, H.; Hahn, M. S.; Hammond, G. E.; Rockhold, M. L.; Rubin, Y.

2010-12-01

Tracer testing under natural or forced gradient flow provides useful information for characterizing subsurface properties, by monitoring and modeling the tracer plume migration in a heterogeneous aquifer. At the Hanford 300 Area, non-reactive tracer experiments, in addition to constant-rate injection tests and electromagnetic borehole flowmeter (EBF) profiling, were conducted to characterize the heterogeneous hydraulic conductivity field. A Bayesian data assimilation technique, method of anchored distributions (MAD), is applied to assimilate the experimental tracer test data and to infer the three-dimensional heterogeneous structure of the hydraulic conductivity in the saturated zone of the Hanford formation. In this study, the prior information of the underlying random hydraulic conductivity field was obtained from previous field characterization efforts using the constant-rate injection tests and the EBF data. The posterior distribution of the random field is obtained by further conditioning the field on the temporal moments of tracer breakthrough curves at various observation wells. The parallel three-dimensional flow and transport code PFLOTRAN is implemented to cope with the highly transient flow boundary conditions at the site and to meet the computational demand of the proposed method. The validation results show that the field conditioned on the tracer test data better reproduces the tracer transport behavior compared to the field characterized previously without the tracer test data. A synthetic study proves that the proposed method can effectively assimilate tracer test data to capture the essential spatial heterogeneity of the three-dimensional hydraulic conductivity field. These characterization results will improve conceptual models developed for the site, including reactive transport models. The study successfully demonstrates the capability of MAD to assimilate multi-scale multi-type field data within a consistent Bayesian framework. The MAD framework can potentially be applied to combine geophysical data with other types of data in site characterization.

Tracer tomography: design concepts and field experiments using heat as a tracer.

PubMed

Doro, Kennedy O; Cirpka, Olaf A; Leven, Carsten

2015-04-01

Numerical and laboratory studies have provided evidence that combining hydraulic tomography with tomographic tracer tests could improve the estimation of hydraulic conductivity compared with using hydraulic data alone. Field demonstrations, however, have been lacking so far, which we attribute to experimental difficulties. In this study, we present a conceptual design and experimental applications of tracer tomography at the field scale using heat as a tracer. In our experimental design, we improve active heat tracer testing by minimizing possible effects of heat losses, buoyancy, viscosity, and changing boundary conditions. We also utilize a cost-effective approach of measuring temperature changes in situ at high resolution. We apply the presented method to the 8 m thick heterogeneous, sandy gravel, alluvial aquifer at the Lauswiesen Hydrogeological Research Site in Tübingen, Germany. Results of our tomographic heat-tracer experiments are in line with earlier work on characterizing the aquifer at the test site. We demonstrate from the experimental perspective that tracer tomography is applicable and suitable at the field scale using heat as a tracer. The experimental results also demonstrate the potential of heat-tracer tomography as a cost-effective means for characterizing aquifer heterogeneity. © 2014, National Ground Water Association.

Demonstration of In situ Anaerobic Transformation of Toluene and Xylene Using Single-Well Push-Pull Tests and Deuterated BTEX Surrogates

NASA Astrophysics Data System (ADS)

Field, J. A.; Reusser, D. E.; Beller, H. R.; Istok, J. D.

2001-12-01

Obtaining unambiguous evidence of in-situ transformation of benzene, toluene, ethylbenzene and xylene (BTEX) in the subsurface is a difficult task. Recently, benzylsuccinic acid and its methyl analogues were shown to be unequivocal degradation products of anaerobic toluene and xylene biodegradation. Conducting tracer tests at BTEX-contaminated field sites is problematic because background contaminant concentrations potentially interfere with the interpretation of field test data. To avoid the time and cost associated with removing background contaminants, alternative approaches are needed. Deuterated analogs of toluene and xylene are well-suited for use in field tracer tests because they are inexpensive and can be distinguished analytically from background toluene and xylene. In this study, single-well push-pull tests, in which deuterated toluene and xylene were injected, were performed to assess the in-situ anaerobic biotransformation of toluene and xylene in BTEX-contaminated wells. A total of 4 single-well push-pull tests were conducted at BTEX-contaminated field sites near Portland, OR and Kansas City, KS. Test solutions consisting of 100 mg/L bromide, 250 mg/L nitrate, 0.4 to 2.5 mg/L toluene-d8, and 0.4 to 1.0 mg/L o-xylene-d10.were injected at a rate of 0.5 - 2 L/min. During the extraction phase, samples were taken daily to biweekly for up to 30 days. Samples for volatile organic analytes were collected in 40-mL volatile organic analysis (VOA) vials without headspace. Samples for BSA and methyl-BSA were collected in 1 L glass bottles and preserved with 5% (w/w) formalin. Samples were shipped on ice and stored at 4 C until analysis. Unambiguous evidence of toluene and xylene biotransformation was obtained with the in-situ formation of BSA and methyl-BSA. The concentrations of BSA ranged from below the detection limit (0.2 ug/L) to 1.5 ug/L. The concentrations of methyl-BSA ranged from below detection to the quantitation limit (0.7 ug/L). The highest BSA concentrations detected corresponded to 0.1 - 0.2 mol% of the injected deuterated toluene. Zero-order degradation rates for deuterated toluene, estimated as the rates of BSA formation, were 0.0004 to 0.001 day-1. Because methyl-BSA concentrations did not exceed the quantitation limit, the rate of xylene degradation could not be calculated. The formation of BSA and methyl-BSA was coupled with the utilization of nitrate, presumably due to denitrification. Transformation of toluene and xylene to BSA and methyl-BSA, respectively, was observed for wells characterized by low concentrations of toluene and xylene relative to total BTEX. To the best of our knowledge, this is the first report to document the use of deuterated BTEX surrogates in field-tracer experiments.

Maintaining Flatness of a Large Aperture Potassium Bromide Beamsplitter Through Mounting and Vibration

NASA Technical Reports Server (NTRS)

Losch, Patricia; Lyons, James J., III; Morell, Armando; Heaney, Jim

1998-01-01

The Composite Infrared Spectrometer (CIRS) instrument on the Cassini Mission launched in October of 1997. The CIRS instrument contains a mid-infrared (MIR) and a far-infrared interferometer (FIR) and operates at 170 Kelvin. The MIR is a Michelson Fourier transform spectrometer utilizing a 76 mm (3 inch) diameter potassium bromide beamsplitter and compensator pair. The potassium bromide elements were tested to verify effects of cooldown and vibration prior to integration into the instrument. The instrument was then aligned at ambient temperatures, tested cryogenically and re-verified after vibration. 'Me stringent design optical figure requirements for the beamsplitter and compensator included fabrication errors, mounting stresses and vibration load effects. This paper describes the challenges encountered in mounting the elements to minimize distortion and to survive vibration.

Maintaining Flatness of a Large Aperture Potassium Bromide Beamsplitter through Mounting and Vibration

NASA Technical Reports Server (NTRS)

Losch, Patricia; Lyons, James, III; Morell, Armando; Heaney, Jim

1998-01-01

The Composite Infrared Spectrometer (CIRS) instrument on the Cassini Mission launched in October of 1997. The CIRS instrument contains a mid-infrared and a far-infrared interferometer and operates at 170 Kelvin. The mid-infrared interferometer is a Michelson- type Fourier transform spectrometer utilizing a 3 inch diameter potassium bromide beamsplitter/compensator pair. The potassium bromide elements were tested to verify effects of cooldown and vibration prior to integration into the instrument. The instrument was then aligned at ambient temperatures, tested cryogenically and re-verified after vibration. The stringent design optical figure requirements for the beamsplitter and compensator included fabrication errors, mounting stresses and vibration load effects. This paper describes the challenges encountered in mounting the elements to minimize distortion and to survive vibration.

Effect of preconditioning on silver leaching and bromide removal properties of silver-impregnated activated carbon (SIAC).

PubMed

Rajaeian, Babak; Allard, Sébastien; Joll, Cynthia; Heitz, Anna

2018-07-01

Silver impregnated activated carbon (SIAC) has been found to be effective in mitigating the formation of brominated-disinfection by products during drinking water treatment. However, there are still uncertainties regarding its silver leaching properties, and strategies for the prevention of silver leaching have remained elusive. This study focused on the evaluation of one type of commercially available SIAC for its ability to remove bromide while minimising silver leaching from the material. Both synthetic and real water matrices were tested. Depending on solution pH, it was found that changing the surface charge properties of SIAC, as measured by the point of zero charge pH, can result in additional bromide removal while minimising the extent of silver leaching. To better understand the mechanism of silver leaching from the SIAC, eight preconditioning environments, i.e. variable pH and ionic strength were tested for a fixed amount of SIAC and two preconditioning environments were selected for a more detailed investigation. Experiments carried out in synthetic water showed that preconditioning at pH 10.4 did not deteriorate the capacity of SIAC to remove bromide, but significantly decreased the release of silver in the form of ionic silver (Ag + ), silver bromide (AgBr) and silver chloride (AgCl) from 40% for the pristine to 3% for the treated SIAC. This was confirmed using a groundwater sample. These results suggest that preconditioned SIAC has the potential to be an effective method for bromide removal with minimised silver leaching in a long-term field application for drinking water production. Copyright © 2018 Elsevier Ltd. All rights reserved.

Development of Models to Simulate Tracer Tests for Characterization of Enhanced Geothermal Systems

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

Williams, Mark D.; Reimus, Paul; Vermeul, Vincent R.

2013-05-01

A recent report found that power and heat produced from enhanced (or engineered) geothermal systems (EGSs) could have a major impact on the U.S energy production capability while having a minimal impact on the environment. EGS resources differ from high-grade hydrothermal resources in that they lack sufficient temperature distribution, permeability/porosity, fluid saturation, or recharge of reservoir fluids. Therefore, quantitative characterization of temperature distributions and the surface area available for heat transfer in EGS is necessary for the design and commercial development of the geothermal energy of a potential EGS site. The goal of this project is to provide integrated tracermore » and tracer interpretation tools to facilitate this characterization. This project was initially focused on tracer development with the application of perfluorinated tracer (PFT) compounds, non-reactive tracers used in numerous applications from atmospheric transport to underground leak detection, to geothermal systems, and evaluation of encapsulated PFTs that would release tracers at targeted reservoir temperatures. After the 2011 midyear review and subsequent discussions with the U.S. Department of Energy Geothermal Technology Program (GTP), emphasis was shifted to interpretive tool development, testing, and validation. Subsurface modeling capabilities are an important component of this project for both the design of suitable tracers and the interpretation of data from in situ tracer tests, be they single- or multi-well tests. The purpose of this report is to describe the results of the tracer and model development for simulating and conducting tracer tests for characterizing EGS parameters.« less

Detection and control of Fusarium oxysporum and Cylindrocarpon destructans in forest nursery soils

Treesearch

Catherine Crosby; Lynne Carpenter-Boggs; Stewart Higgins; Nabil Khadduri

2010-01-01

Fusarium oxysporum and Cylindrocarpon destructans cause root disease that leads to significant crop losses in forest nurseries when not treated. Treatment currently relies on methyl bromide fumigation to eradicate soil pathogens. New environmental protection laws, however, are phasing out methyl bromide. Alternative chemical treatments are being tested, as well as...

MULTISPECIES REACTIVE TRACER TEST IN A SAND AND GRAVEL AQUIFER, CAPE COD, MASSACHUSETTS: PART 2: TRANSPORT OF CHROMIUM (VI) AND LEAD-, COPPER-, AND ZINC-EDTA TRACERS

EPA Science Inventory

This report discusses the transport of a group of reactive tracers over the course of a large-scale, natural gradient tracer test conducted at the USGS Cape Cod Toxic Substances Hydrology Research site, near Falmouth, Massachusetts. The overall objectives of the experiment were ...

Identification and characterization of conservative organic tracers for use as hydrologic tracers for the Yucca Mountain site characterization study. Final report

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

Stetzenbach, K.; Farnham, I.

1996-06-01

Extensive tracer testing is expected to take place at the C-well complex in the Nevada Test Site as part of the Yucca Mountain Site Characterization Project. The C-well complex consists of one pumping well, C3, and two injection wells, C1 and C2 into which tracer will be introduced. The goal of this research was to provide USGS with numerous tracers to completed these tests. Several classes of fluorinated organic acids have been evaluated. These include numerous isomers of fluorinated benzoic acids, cinnamic acids, and salicylic acids. Also several derivatives of 2-hydroxy nicotinic acid (pyridone) have been tested. The stability ofmore » these compounds was determined using batch and column tests. Ames testing (mutagenicity/carcinogenicity) was conducted on the fluorinated benzoic acids and a literature review of toxicity of the fluorobenzoates and three perfluoro aliphatic acids was prepared. Solubilities were measured and method development work was performed to optimize the detection of these compounds. A Quality Assurance (QA) Program was developed under existing DOE and USGS guidelines. The program includes QA procedures and technical standard operating procedures. A tracer test, using sodium iodide, was performed at the C-well complex. HRC chemists performed analyses on site, to provide real time data for the USGS hydrologists and in the laboratories at UNLV. Over 2,500 analyses were performed. This report provides the results of the laboratory experiments and literature reviews used to evaluate the potential tracers and reports on the results of the iodide C-well tracer test.« less

A stream-based methane monitoring approach for evaluating groundwater impacts associated with unconventional gas development.

PubMed

Heilweil, Victor M; Stolp, Bert J; Kimball, Briant A; Susong, David D; Marston, Thomas M; Gardner, Philip M

2013-01-01

Gaining streams can provide an integrated signal of relatively large groundwater capture areas. In contrast to the point-specific nature of monitoring wells, gaining streams coalesce multiple flow paths. Impacts on groundwater quality from unconventional gas development may be evaluated at the watershed scale by the sampling of dissolved methane (CH4 ) along such streams. This paper describes a method for using stream CH4 concentrations, along with measurements of groundwater inflow and gas transfer velocity interpreted by 1-D stream transport modeling, to determine groundwater methane fluxes. While dissolved ionic tracers remain in the stream for long distances, the persistence of methane is not well documented. To test this method and evaluate CH4 persistence in a stream, a combined bromide (Br) and CH4 tracer injection was conducted on Nine-Mile Creek, a gaining stream in a gas development area in central Utah. A 35% gain in streamflow was determined from dilution of the Br tracer. The injected CH4 resulted in a fivefold increase in stream CH4 immediately below the injection site. CH4 and δ(13) CCH4 sampling showed it was not immediately lost to the atmosphere, but remained in the stream for more than 2000 m. A 1-D stream transport model simulating the decline in CH4 yielded an apparent gas transfer velocity of 4.5 m/d, describing the rate of loss to the atmosphere (possibly including some microbial consumption). The transport model was then calibrated to background stream CH4 in Nine-Mile Creek (prior to CH4 injection) in order to evaluate groundwater CH4 contributions. The total estimated CH4 load discharging to the stream along the study reach was 190 g/d, although using geochemical fingerprinting to determine its source was beyond the scope of the current study. This demonstrates the utility of stream-gas sampling as a reconnaissance tool for evaluating both natural and anthropogenic CH4 leakage from gas reservoirs into groundwater and surface water. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

The Qtracer2 Program for Tracer-Breakthrough Curve Analysis for Tracer Tests in Karstic Aquifers and Other Hydrologic Systems (2002)

EPA Science Inventory

Tracer testing is generally regarded as the most reliable and efficient method of gathering surface and subsurface hydraulic information. This is especially true for karstic and fractured-rock aquifers. Qualitative tracing tests have been conventionally employed in most karst s...

Reactive transport studies at the Raymond Field Site

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

Freifeld, B.; Karasaki, K.; Solbau, R.

1995-12-01

To ensure the safety of a nuclear waste repository, an understanding of the transport of radionuclides from the repository nearfield to the biosphere is necessary. At the Raymond Field Site, in Raymond, California, tracer tests are being conducted to test characterization methods for fractured media and to evaluate the equipment and tracers that will be used for Yucca Mountain`s fracture characterization. Recent tracer tests at Raymond have used reactive cations to demonstrate transport with sorption. A convective-dispersive model was used to simulate a two-well recirculating test with reasonable results. However, when the same model was used to simulate a radiallymore » convergent tracer test, the model poorly predicted the actual test data.« less

ANALYTICAL METHOD DEVELOPMENTS TO SUPPORT PARTITIONING INTERWELL TRACER TESTING

EPA Science Inventory

Partitioning Interwell Tracer Testing (PITT) uses alcohol tracer compounds in estimating subsurface contamination from non-polar pollutants. PITT uses the analysis of water samples for various alcohols as part of the overall measurement process. The water samples may contain many...

Re-manufacture of cobalt-manganese-bromide as a liquid catalyst from spent catalyst containing cobalt generated from petrochemical processes via hydrometallurgy.

PubMed

Joo, Sung-Ho; Shin, Dong Ju; Oh, Chang Hyun; Wang, Jei-Pil; Shin, Shun Myung

2016-11-15

Cobalt and manganese have been the subject of individual separation studies because their fields of application are different. However, this study shows that high-value products can be manufactured in the form of a cobalt-manganese-bromide (CMB) liquid catalyst by simultaneously recovering cobalt and manganese. Na-bis-(2,4,4-tri-methyl-pentyl)phosphinic acid was employed in order to manufacture the CMB liquid catalyst from the spent catalyst generated from petroleum chemistry processes. The pH-isotherm, degree of saponification of solvent and separation factor values were investigated. ΔpH50 and separation factor values show that Co and Mn can be separated from impurities such as Mg and Ca. Further, the extraction stages and organic/aqueous ratio isotherms were investigated using counter-current simulation extraction batch tests. To prepare CMB from a loaded organic phase obtained in a stripping study using hydrogen bromide, the Co and Mn were completely stripped and concentrated by a factor of 6 using a 2M hydrogen bromide solution. When compared with manufactured and commercial CMB, the CMB liquid catalyst could be produced by supplying a shortage of Mn in the form of manganese bromide. Finally, the method of manufacture of CMB was subjected to a real pilot plant test. Copyright © 2016. Published by Elsevier B.V.

3-D numerical evaluation of density effects on tracer tests.

PubMed

Beinhorn, M; Dietrich, P; Kolditz, O

2005-12-01

In this paper we present numerical simulations carried out to assess the importance of density-dependent flow on tracer plume development. The scenario considered in the study is characterized by a short-term tracer injection phase into a fully penetrating well and a natural hydraulic gradient. The scenario is thought to be typical for tracer tests conducted in the field. Using a reference case as a starting point, different model parameters were changed in order to determine their importance to density effects. The study is based on a three-dimensional model domain. Results were interpreted using concentration contours and a first moment analysis. Tracer injections of 0.036 kg per meter of saturated aquifer thickness do not cause significant density effects assuming hydraulic gradients of at least 0.1%. Higher tracer input masses, as used for geoelectrical investigations, may lead to buoyancy-induced flow in the early phase of a tracer test which in turn impacts further plume development. This also holds true for shallow aquifers. Results of simulations with different tracer injection rates and durations imply that the tracer input scenario has a negligible effect on density flow. Employing model cases with different realizations of a log conductivity random field, it could be shown that small variations of hydraulic conductivity in the vicinity of the tracer injection well have a major control on the local tracer distribution but do not mask effects of buoyancy-induced flow.

Three-dimensional Bayesian geostatistical aquifer characterization at the Hanford 300 Area using tracer test data

NASA Astrophysics Data System (ADS)

Chen, Xingyuan; Murakami, Haruko; Hahn, Melanie S.; Hammond, Glenn E.; Rockhold, Mark L.; Zachara, John M.; Rubin, Yoram

2012-06-01

Tracer tests performed under natural or forced gradient flow conditions can provide useful information for characterizing subsurface properties, through monitoring, modeling, and interpretation of the tracer plume migration in an aquifer. Nonreactive tracer experiments were conducted at the Hanford 300 Area, along with constant-rate injection tests and electromagnetic borehole flowmeter tests. A Bayesian data assimilation technique, the method of anchored distributions (MAD) (Rubin et al., 2010), was applied to assimilate the experimental tracer test data with the other types of data and to infer the three-dimensional heterogeneous structure of the hydraulic conductivity in the saturated zone of the Hanford formation.In this study, the Bayesian prior information on the underlying random hydraulic conductivity field was obtained from previous field characterization efforts using constant-rate injection and borehole flowmeter test data. The posterior distribution of the conductivity field was obtained by further conditioning the field on the temporal moments of tracer breakthrough curves at various observation wells. MAD was implemented with the massively parallel three-dimensional flow and transport code PFLOTRAN to cope with the highly transient flow boundary conditions at the site and to meet the computational demands of MAD. A synthetic study proved that the proposed method could effectively invert tracer test data to capture the essential spatial heterogeneity of the three-dimensional hydraulic conductivity field. Application of MAD to actual field tracer data at the Hanford 300 Area demonstrates that inverting for spatial heterogeneity of hydraulic conductivity under transient flow conditions is challenging and more work is needed.

Photoacoustic infrared spectroscopy for conducting gas tracer tests and measuring water saturations in landfills

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

Jung, Yoojin; Han, Byunghyun; Mostafid, M. Erfan

2012-02-15

Highlights: Black-Right-Pointing-Pointer Photoacoustic infrared spectroscopy tested for measuring tracer gas in landfills. Black-Right-Pointing-Pointer Measurement errors for tracer gases were 1-3% in landfill gas. Black-Right-Pointing-Pointer Background signals from landfill gas result in elevated limits of detection. Black-Right-Pointing-Pointer Technique is much less expensive and easier to use than GC. - Abstract: Gas tracer tests can be used to determine gas flow patterns within landfills, quantify volatile contaminant residence time, and measure water within refuse. While gas chromatography (GC) has been traditionally used to analyze gas tracers in refuse, photoacoustic spectroscopy (PAS) might allow real-time measurements with reduced personnel costs and greater mobilitymore » and ease of use. Laboratory and field experiments were conducted to evaluate the efficacy of PAS for conducting gas tracer tests in landfills. Two tracer gases, difluoromethane (DFM) and sulfur hexafluoride (SF{sub 6}), were measured with a commercial PAS instrument. Relative measurement errors were invariant with tracer concentration but influenced by background gas: errors were 1-3% in landfill gas but 4-5% in air. Two partitioning gas tracer tests were conducted in an aerobic landfill, and limits of detection (LODs) were 3-4 times larger for DFM with PAS versus GC due to temporal changes in background signals. While higher LODs can be compensated by injecting larger tracer mass, changes in background signals increased the uncertainty in measured water saturations by up to 25% over comparable GC methods. PAS has distinct advantages over GC with respect to personnel costs and ease of use, although for field applications GC analyses of select samples are recommended to quantify instrument interferences.« less

Conceptualization of flow and transport in a limestone aquifer by multiple dedicated hydraulic and tracer tests

NASA Astrophysics Data System (ADS)

Mosthaf, Klaus; Brauns, Bentje; Fjordbøge, Annika S.; Rohde, Magnus M.; Kerrn-Jespersen, Henriette; Bjerg, Poul L.; Binning, Philip J.; Broholm, Mette M.

2018-06-01

Limestone aquifers are of great interest as a drinking water resource in many countries. They often have a complex crushed and fractured geology, which makes the analysis and description of flow and transport processes in such aquifers a challenging task. In this study, the solute transport behavior including fracture-matrix interaction in hydrogeological units of a limestone aquifer in eastern Denmark was characterized by designing, conducting and interpreting six depth-specific tracer tests involving natural- and forced-gradient conditions with multiple tracers representing different diffusion properties. To determine flow parameters, the tracer tests were complemented by a comprehensive set of depth-specific borehole and hydraulic tests. Based on the tests, a new and stronger conceptual understanding was developed for the different aquifer units. The investigated limestone aquifer is composed of a glacially crushed unit and two fractured units, with calcarenitic and bryozoan limestone of similar hydraulic properties. Hydraulic tests revealed that the crushed unit has a lower hydraulic conductivity than the fractured limestone units, likely due to the crushed conditions with small limestone clusters and small-aperture fractures potentially filled with fine material. In the fractured limestone units, a distinct preferential flow and primary transport along major horizontal fractures was inferred from the tracer tests under forced-gradient conditions. The dominant horizontal fractures were identified on impeller flow logs and appear connected between wells, having an extent of up to several hundred meters. Connectivity between the aquifer units was investigated with a long-term pumping test and tracer tests, revealing restricted vertical flow and transport. A very pronounced hydraulic conductivity contrast between major fractures and matrix could also be inferred from the borehole and hydraulic tests, which is consistent with the findings from the tracer tests. The difference in the matrix diffusion behavior of the simultaneously injected tracers and a long tailing in the breakthrough curves revealed that matrix diffusion has a strong influence on the solute transport in the fractured limestone.

IMAGE Project: Results of Laboratory Tests on Tracers for Supercritical Conditions.

NASA Astrophysics Data System (ADS)

Brandvoll, Øyvind; Opsahl Viig, Sissel; Nardini, Isabella; Muller, Jiri

2016-04-01

The use of tracers is a well-established technique for monitoring dynamic behaviour of water and gas through a reservoir. In geothermal reservoirs special challenges are encountered due to high temperatures and pressures. In this work, tracer candidates for monitoring water at supercritical conditions (temperature > 374°C, pressure ca 218 bar), are tested in laboratory experiments. Testing of tracers at supercritical water conditions requires experimental set-ups which tolerate harsh conditions with respect to high temperature and pressure. In addition stringent HES (health, environment and safety) factors have to be taken into consideration when designing and performing the experiments. The setup constructed in this project consists of a pressure vessel, high pressure pump, instrumentation for pressure and temperature control and instrumentation required for accurate sampling of tracers. In order to achieve accurate results, a special focus has been paid to the development of the tracer sampling technique. Perfluorinated cyclic hydrocarbons (PFCs) have been selected as tracer candidates. This group of compounds is today commonly used as gas tracers in oil reservoirs. According to the literature they are stable at temperatures up to 400°C. To start with, five PFCs have been tested for thermal stability in static experiments at 375°C and 108 bar in the experimental setup described above. The tracer candidates will be further tested for several months at the relevant conditions. Preliminary results indicate that some of the PFC compounds show stability after three months. However, in order to arrive at conclusive results, the experiments have to be repeated over a longer period and paying special attention to more accurate sampling procedures.

Tracer element for indoor PM2.5 in China migrated from outdoor

NASA Astrophysics Data System (ADS)

Ji, Wenjing; Li, Hongyu; Zhao, Bin; Deng, Furong

2018-03-01

Sulfur and nickel have been widely used as tracers of outdoor PM2.5 (particulate matter with an aerodynamic diameter ≤ 2.5 μm) in the United States and Europe; however, their feasibility as tracers has not been verified yet in China. We aim to verify whether sulfur or nickel could be used as a tracer element and, if not, to identify a suitable tracer element for outdoor PM2.5 in China. We conduct two types of experiments, namely, preliminary and main-study experiments. We analyze 102 pairs of indoor and outdoor PM2.5 samples in Beijing. The correlation between the I/O (indoor/outdoor) ratio of an element and the I/O ratio of total PM2.5 is one of the criteria used to test whether this element can be used as a tracer element. The average concentrations of nickel are found to be below the detection limits in both preliminary and main-study tests. Thus, nickel cannot be used as a tracer element in China. Based on the correlations of elemental I/O ratios and the I/O ratio of total PM2.5 in the preliminary and main-study tests, sulfur also cannot be used as a tracer element; however, it should be feasible to use iron as a tracer element in Beijing according to the test results. The estimated infiltration factor obtained by using iron as tracer is extremely consistent with the calculations based on the mass balance model. In summary, iron is found to be more suitable as a tracer for outdoor PM2.5 in Beijing than sulfur or nickel.

Non-conservative characteristics of fluorescent tracers help to assess in-situ transport and attenuation of pesticides

NASA Astrophysics Data System (ADS)

Lange, Jens; Payraudeau, Sylvain; Imfeld, Gwenaël

2016-04-01

Traditionally, hydrological tracers are selected to behave as conservatively as possible, since most applications aim to investigate the transport of water or conservative solutes. Non-conservative tracer behavior is regarded as a limitation. However, the environmental behavior of organic pesticides is strictly non-conservative as their fate is affected by various processes, including sorption, photolysis and biochemical transformation in various environmental compartments. If tracers are used to study pesticides under these conditions, we believe that a paradigm shift is necessary: only a tracer that is affected by similar attenuation processes can realistically reproduce the overall behavior of a target pesticide. We present here two examples from two different environmental compartments: (i) agricultural soils and (ii) wetland systems. In both studies two organic fluorescent tracers (uranine, UR and sulforhodamine-B, SRB) and the salt tracer bromide (BR) were applied together with the chloroacetanilide herbicide S-metolachlor (S-MET). On an agricultural field, plot experiments were conducted under artificial and natural rainfall conditions. The use of BR overestimated both slow leaching and fast preferential transport of S-MET in the unsaturated zone, while UR/SRB were more realistic markers. Under artificial conditions, recovery rates of BR in a tile drain were twice as high as UR and one order of magnitude higher than SRB. Under natural conditions, BR concentrations in surface soils (0-1 cm) displayed larger variances during wetting and drying periods than UR, SRB and S-MET. BR also leached deeper (below 5 cm) than S-MET in the soil column. After 70 days, characteristic fluorescent peaks of UR and SRB gradually decreased in soil samples, while a new peak increased in another spectrum, which suggests the production of a potential transformation product. In two artificial wetland systems the impact of hydrological conditions (batch versus continuous-flow) on solute dissipation was studied. The solute mass budgets included plants, sediment and water phases and reflected the main dissipation pathways. Apart from plant uptake, BR was conservative under both conditions. Similar to S-MET, UR and SRB were affected by sorption, photo- and presumably biodegradation and all processes were more prominent in the batch than in the continuous flow wetland. This was in agreement with a larger overall dissipation of S-MET under batch (90%) than continuous mode (60%). Hence, only UR/SRB realistically illustrated the effect of hydrological conditions (different hydraulic residence times and alternating biogeochemical conditions) on S-MET attenuation in the wetland systems.

Characterization of an alluvial aquifer with thermal tracer tomography

NASA Astrophysics Data System (ADS)

Somogyvári, Márk; Bayer, Peter

2017-04-01

In the summer of 2015, a series of thermal tracer tests was performed at the Widen field site in northeast Switzerland. At this site numerous hydraulic, tracer, geophysical and hydrogeophysical field tests have been conducted in the past to investigate a shallow alluvial aquifer. The goals of the campaign in 2015 were to design a cost-effective thermal tracer tomography setup and to validate the concept of travel time-based thermal tracer tomography under field conditions. Thermal tracer tomography uses repeated thermal tracer injections with different injection depths and distributed temperature measurements to map the hydraulic conductivity distribution of a heterogeneous aquifer. The tracer application was designed with minimal experimental time and cost. Water was heated in inflatable swimming pools using direct sunlight of the warm summer days, and it was injected as low temperature pulses in a well. Because of the small amount of injected heat, no long recovery times were required between the repeated heat tracer injections and every test started from natural thermal conditions. At Widen, four thermal tracer tests were performed during a period of three days. Temperatures were measured in one downgradient well using a distributed temperature measurement system installed at seven depth points. Totally 12 temperature breakthrough curves were collected. Travel time based tomographic inversion assumes that thermal transport is dominated by advection and the travel time of the thermal tracer can be related to the hydraulic conductivities of the aquifer. This assumption is valid in many shallow porous aquifers where the groundwater flow is fast. In our application, the travel time problem was treated by a tomographic solver, analogous to seismic tomography, to derive the hydraulic conductivity distribution. At the test site, a two-dimensional cross-well hydraulic conductivity profile was reconstructed with the travel time based inversion. The reconstructed profile corresponds well with the findings of the earlier hydraulic and geophysical experiments at the site.

Isotopic Tracers for Delineating Non-Point Source Pollutants in Surface Water

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

Davisson, M L

2001-03-01

This study tested whether isotope measurements of surface water and dissolved constituents in surface water could be used as tracers of non-point source pollution. Oxygen-18 was used as a water tracer, while carbon-14, carbon-13, and deuterium were tested as tracers of DOC. Carbon-14 and carbon-13 were also used as tracers of dissolved inorganic carbon, and chlorine-36 and uranium isotopes were tested as tracers of other dissolved salts. In addition, large databases of water quality measurements were assembled for the Missouri River at St. Louis and the Sacramento-San Joaquin Delta in California to enhance interpretive results of the isotope measurements. Muchmore » of the water quality data has been under-interpreted and provides a valuable resource to investigative research, for which this report exploits and integrates with the isotope measurements.« less

Field-scale Prediction of Enhanced DNAPL Dissolution Using Partitioning Tracers and Flow Pattern Effects

NASA Astrophysics Data System (ADS)

Wang, F.; Annable, M. D.; Jawitz, J. W.

2012-12-01

The equilibrium streamtube model (EST) has demonstrated the ability to accurately predict dense nonaqueous phase liquid (DNAPL) dissolution in laboratory experiments and numerical simulations. Here the model is applied to predict DNAPL dissolution at a PCE-contaminated dry cleaner site, located in Jacksonville, Florida. The EST is an analytical solution with field-measurable input parameters. Here, measured data from a field-scale partitioning tracer test were used to parameterize the EST model and the predicted PCE dissolution was compared to measured data from an in-situ alcohol (ethanol) flood. In addition, a simulated partitioning tracer test from a calibrated spatially explicit multiphase flow model (UTCHEM) was also used to parameterize the EST analytical solution. The ethanol prediction based on both the field partitioning tracer test and the UTCHEM tracer test simulation closely matched the field data. The PCE EST prediction showed a peak shift to an earlier arrival time that was concluded to be caused by well screen interval differences between the field tracer test and alcohol flood. This observation was based on a modeling assessment of potential factors that may influence predictions by using UTCHEM simulations. The imposed injection and pumping flow pattern at this site for both the partitioning tracer test and alcohol flood was more complex than the natural gradient flow pattern (NGFP). Both the EST model and UTCHEM were also used to predict PCE dissolution under natural gradient conditions, with much simpler flow patterns than the forced-gradient double five spot of the alcohol flood. The NGFP predictions based on parameters determined from tracer tests conducted with complex flow patterns underestimated PCE concentrations and total mass removal. This suggests that the flow patterns influence aqueous dissolution and that the aqueous dissolution under the NGFP is more efficient than dissolution under complex flow patterns.

Human Metabolism and Interactions of Deployment-Related Chemicals

DTIC Science & Technology

2003-08-01

with individual test compounds (final concentration, 100 PM), agent pyridostigmine bromide to protect against possible nerve gas NADPH-generating system...an insect repellent (N,N-diethyl-m- toluamide) a nerve gas prophyllactic (pyridostigmine bromide) did not cause the inhibition of trans-permethrin...mechanism of organophosphorus anticholinesterase agents , namely; covalent modification of the active site of the esterases in question. Carbaryl, another

Seeking alternatives to probit 9 when developing treatments for wood packaging materials under ISPM No. 15

Treesearch

R.A. Haack; A. Uzunovic; K. Hoover; J.A. Cook

2011-01-01

ISPM No. 15 presents guidelines for treating wood packaging material used in international trade. There are currently two approved phytosanitary treatments: heat treatment and methyl bromide fumigation. New treatments are under development, and are needed given that methyl bromide is being phased out. Probit 9 efficacy (100% mortality of at least 93 613 test organisms...

The history and future of methyl bromide alternatives in the southern United States

Treesearch

Tom E. Starkey

2012-01-01

This article gives a brief history of the efforts of the Southern Forest Nursery Management Cooperative (SFNMC) in testing methyl bromide (MBr) alternatives for soil fumigation. In the southeastern United States, fumigation with MBr has been the most commonly used method for producing high quality, pest-free forest seedlings in an environment that is conducive for soil...

Eradicating European pine shoot moth on ornamental pines with methyl bromide.

Treesearch

V.M. Carolin; W.H. Klein; R.M. Thompson

1962-01-01

The recent introduction of the European pine shoot moth into this region poses a serious threat to natural pine stands. To combat this threat, quarantines were invoked and eradication programs undertaken. Destruction of infested trees has been used tentatively as an eradication technique. In the meantime, fumigation with methyl bromide was tested over the period of a...

Estimating ground-water exchange with lakes using water-budget and chemical mass-balance approaches for ten lakes in ridge areas of Polk and Highlands counties, Florida

USGS Publications Warehouse

Sacks, L.A.; Swancar, Amy; Lee, T.M.

1998-01-01

Water budget and chemical mass-balance approaches were used to estimate ground-water exchange with 10 lakes in ridge areas of Polk and Highlands Counties, Florida. At each lake, heads were monitored in the surficial aquifer system and deeper Upper Floridan aquifer, lake stage and rainfall were measured continuously, and lakes and wells were sampled three times between October 1995 and December 1996. The water-budget approach computes net ground-water flow (ground-water inflow minus outflow) as the residual of the monthly waterbudget equation. Net ground-water flow varied seasonally at each of the 10 lakes, and was notably different between lakes, illustrating short-term differences in ground-water fluxes. Monthly patterns in net ground-water flow were related to monthly patterns of other hydrologic variables such as rainfall, ground-water flow patterns, and head differences between the lake and the Upper Floridan aquifer. The chemical mass-balance approach combines the water budget and solute or isotope mass-balance equations, and assumes steady-state conditions. Naturally occurring tracers that were analyzed for include calcium, magnesium, sodium, potassium, chloride, and bromide, the isotopes deuterium and oxygen-18. Chloride and sodium were the most successful solute tracers; however, their concentrations in ground water typically varied spatially, and in places were similar to that in lake water, limiting their sensitivity as tracers. In contrast, the isotopes were more robust tracers because the isotopic composition of ground water was relatively uniform and was distinctly different from the lake water. Groundwater inflow computed using the chemical massbalance method varied significantly between lakes, and ranged from less than 10 to more than 150 inches per year. Both water-budget and chemical mass-balance approaches had limitations, but the multiple lines of evidence gained using both approaches improved the understanding of the role of ground water in the water budget of the lakes.

Trace Gas Trends in the Stratosphere: 1991-2005

NASA Astrophysics Data System (ADS)

Elkins, J. W.; Moore, F. L.; Dutton, G. S.; Hurst, D. F.; Ray, E. A.; Montzka, S. A.; Butler, J. H.; Fahey, D. W.; Hall, B. H.; Atlas, E.; Wofsy, S. C.; Romashkin, P. A.

2005-05-01

The first NOAA airborne gas chromatograph measured chlorofluorocarbon-11 (CFC-11) and CFC-113 during the Arctic Airborne Stratospheric Experiment in 1991-1992. In 1994, we added nitrous oxide (N2O), sulfur hexafluoride (SF6), CFC-12, halon-1211, methyl chloroform, carbon tetrachloride, methane, and hydrogen. NOAA scientists have since operated five airborne gas chromatographs on NASA airborne platforms, including the NASA Jet Propulsion Laboratory (JPL) balloon gondola and ER-2, WB-57F, DC-8, and NASA Altair Unmanned Air Vehicle (UAV) aircraft. Using these in situ measurements and tracer-tracer correlations from flask observations for the unmeasured halogen species (HCFCs and methyl halides including methyl chloride and bromide), we have estimated trends of total chlorine and bromine in the stratosphere. The determination of inorganic equivalent chlorine (Cl + 45*Br) requires the trend of tropospheric equivalent chlorine and the mean age of the parcel of stratospheric air. In general, there is good agreement between the mean age of the air mass calculations using carbon dioxide and SF6, except for regions of extreme down welling of mesospheric air where SF6 is consumed. Tropospheric trends of the methyl halides have been compiled against stable standards. We operated a airborne gas chromatograph on the Sage 3 Ozone Loss Validation Experiment (SOLVE-II) mission from Kiruna, Sweden during 2002. It measured the major HCFCs and methyl halides, so that these compounds do not have to be estimated from tracer-tracer correlations in the future. In 2005, we have added a new lightweight airborne instrument (<25 kg) that can measure CFC-11, CFC-12, halon-1211, SF6, N2O, and ozone. This instrument can operate on small or UAV aircraft and will be used for Aura satellite validation. This presentation will show trends for selected trace gases and our estimates of total equivalent chlorine stratospheric trends since 1991.

Tracer SWIW tests in propped and un-propped fractures: parameter sensitivity issues, revisited

NASA Astrophysics Data System (ADS)

Ghergut, Julia; Behrens, Horst; Sauter, Martin

2017-04-01

Single-well injection-withdrawal (SWIW) or 'push-then-pull' tracer methods appear attractive for a number of reasons: less uncertainty on design and dimensioning, and lower tracer quantities required than for inter-well tests; stronger tracer signals, enabling easier and cheaper metering, and shorter metering duration required, reaching higher tracer mass recovery than in inter-well tests; last not least: no need for a second well. However, SWIW tracer signal inversion faces a major issue: the 'push-then-pull' design weakens the correlation between tracer residence times and georeservoir transport parameters, inducing insensitivity or ambiguity of tracer signal inversion w. r. to some of those georeservoir parameters that are supposed to be the target of tracer tests par excellence: pore velocity, transport-effective porosity, fracture or fissure aperture and spacing or density (where applicable), fluid/solid or fluid/fluid phase interface density. Hydraulic methods cannot measure the transport-effective values of such parameters, because pressure signals correlate neither with fluid motion, nor with material fluxes through (fluid-rock, or fluid-fluid) phase interfaces. The notorious ambiguity impeding parameter inversion from SWIW test signals has nourished several 'modeling attitudes': (i) regard dispersion as the key process encompassing whatever superposition of underlying transport phenomena, and seek a statistical description of flow-path collectives enabling to characterize dispersion independently of any other transport parameter, as proposed by Gouze et al. (2008), with Hansen et al. (2016) offering a comprehensive analysis of the various ways dispersion model assumptions interfere with parameter inversion from SWIW tests; (ii) regard diffusion as the key process, and seek for a large-time, asymptotically advection-independent regime in the measured tracer signals (Haggerty et al. 2001), enabling a dispersion-independent characterization of multiple-scale diffusion; (iii) attempt to determine both advective and non-advective transport parameters from one and the same conservative-tracer signal (relying on 'third-party' knowledge), or from twin signals of a so-called 'dual' tracer pair, e. g.: using tracers with contrasting reactivity and partitioning behavior to determine residual saturation in depleted oilfields (Tomich et al. 1973), or to determine advective parameters (Ghergut et al. 2014); using early-time signals of conservative and sorptive tracers for propped-fracture characterization (Karmakar et al. 2015); using mid-time signals of conservative tracers for a reservoir-borne inflow profiling in multi-frac systems (Ghergut et al. 2016), etc. The poster describes new uses of type-(iii) techniques for the specific purposes of shale-gas reservoir characterization, productivity monitoring, diagnostics and engineering of 're-frac' treatments, based on parameter sensitivity findings from German BMWi research project "TRENDS" (Federal Ministry for Economic Affairs and Energy, FKZ 0325515) and from the EU-H2020 project "FracRisk" (grant no. 640979).

Photoacoustic infrared spectroscopy for conducting gas tracer tests and measuring water saturations in landfills.

PubMed

Jung, Yoojin; Han, Byunghyun; Mostafid, M Erfan; Chiu, Pei; Yazdani, Ramin; Imhoff, Paul T

2012-02-01

Gas tracer tests can be used to determine gas flow patterns within landfills, quantify volatile contaminant residence time, and measure water within refuse. While gas chromatography (GC) has been traditionally used to analyze gas tracers in refuse, photoacoustic spectroscopy (PAS) might allow real-time measurements with reduced personnel costs and greater mobility and ease of use. Laboratory and field experiments were conducted to evaluate the efficacy of PAS for conducting gas tracer tests in landfills. Two tracer gases, difluoromethane (DFM) and sulfur hexafluoride (SF(6)), were measured with a commercial PAS instrument. Relative measurement errors were invariant with tracer concentration but influenced by background gas: errors were 1-3% in landfill gas but 4-5% in air. Two partitioning gas tracer tests were conducted in an aerobic landfill, and limits of detection (LODs) were 3-4 times larger for DFM with PAS versus GC due to temporal changes in background signals. While higher LODs can be compensated by injecting larger tracer mass, changes in background signals increased the uncertainty in measured water saturations by up to 25% over comparable GC methods. PAS has distinct advantages over GC with respect to personnel costs and ease of use, although for field applications GC analyses of select samples are recommended to quantify instrument interferences. Copyright © 2011 Elsevier Ltd. All rights reserved.

Can contaminant transport models predict breakthrough?

USGS Publications Warehouse

Peng, Wei-Shyuan; Hampton, Duane R.; Konikow, Leonard F.; Kambham, Kiran; Benegar, Jeffery J.

2000-01-01

A solute breakthrough curve measured during a two-well tracer test was successfully predicted in 1986 using specialized contaminant transport models. Water was injected into a confined, unconsolidated sand aquifer and pumped out 125 feet (38.3 m) away at the same steady rate. The injected water was spiked with bromide for over three days; the outflow concentration was monitored for a month. Based on previous tests, the horizontal hydraulic conductivity of the thick aquifer varied by a factor of seven among 12 layers. Assuming stratified flow with small dispersivities, two research groups accurately predicted breakthrough with three-dimensional (12-layer) models using curvilinear elements following the arc-shaped flowlines in this test. Can contaminant transport models commonly used in industry, that use rectangular blocks, also reproduce this breakthrough curve? The two-well test was simulated with four MODFLOW-based models, MT3D (FD and HMOC options), MODFLOWT, MOC3D, and MODFLOW-SURFACT. Using the same 12 layers and small dispersivity used in the successful 1986 simulations, these models fit almost as accurately as the models using curvilinear blocks. Subtle variations in the curves illustrate differences among the codes. Sensitivities of the results to number and size of grid blocks, number of layers, boundary conditions, and values of dispersivity and porosity are briefly presented. The fit between calculated and measured breakthrough curves degenerated as the number of layers and/or grid blocks decreased, reflecting a loss of model predictive power as the level of characterization lessened. Therefore, the breakthrough curve for most field sites can be predicted only qualitatively due to limited characterization of the hydrogeology and contaminant source strength.

Effects of Monovalent and Divalent Salt Solutions on the Transport of Toxoplasma gondii in Saturated Porous Media

NASA Astrophysics Data System (ADS)

Darnault, C. J. G.; Pullano, C. P.; Mutty, T.; L'Ollivier, C.; Dubey, J. P.; Dumetre, A.

2017-12-01

The pathogenic microorganism Toxoplasma gondii is a current public health threat. Knowledge of the fate and transport of T. gondii in the environment, especially the subsurface, is critical to evaluate the risk of soil and groundwater contaminations. The physico-chemcial properties of groundwater systems, i.e. solution chemistry and aquifer materials, play a key role in the interaction of biocolloids with surfaces and therefore their mobility. This research examines how different salt solutions alter the mobility of T. gondii through saturated porous media. Salt solutions containing varying ionic strengths and concentrations of sodium chloride, calcium chloride, and magnesium chloride were used to test the transport of the T. gondii oocysts. These tests were performed using quartz silica sand columns fed by a peristaltic pump in order to generate flow and transport of the biocolloids. The salt solution was pumped though the column followed by a pulse of the T. gondii oocysts, then a pulse of salt solution without oocysts, and then lastly a pulse of distilled water. Sampling of the solution exiting the columns was tested for T. gondii oocysts using qPCR in order to quantify the oocysts present. The breakthough curve results were then compared to a conservative bromide tracer test in order to determine the factors associated with the movement of these biocolloids through the sand columns. A model of the flow of the toxoplasma colloids through the sand matrix was made in order to characterize the parameters affecting the transport and retention of T. gondii occysts though saturated porous media.

Transport and attenuation of carboxylate-modified latex microspheres in fractured rock laboratory and field tracer tests

USGS Publications Warehouse

Becker, M.W.; Reimus, P.W.; Vilks, P.

1999-01-01

Understanding colloid transport in ground water is essential to assessing the migration of colloid-size contaminants, the facilitation of dissolved contaminant transport by colloids, in situ bioremediation, and the health risks of pathogen contamination in drinking water wells. Much has been learned through laboratory and field-scale colloid tracer tests, but progress has been hampered by a lack of consistent tracer testing methodology at different scales and fluid velocities. This paper presents laboratory and field tracer tests in fractured rock that use the same type of colloid tracer over an almost three orders-of-magnitude range in scale and fluid velocity. Fluorescently-dyed carboxylate-modified latex (CML) microspheres (0.19 to 0.98 ??m diameter) were used as tracers in (1) a naturally fractured tuff sample, (2) a large block of naturally fractured granite, (3) a fractured granite field site, and (4) another fractured granite/schist field site. In all cases, the mean transport time of the microspheres was shorter than the solutes, regardless of detection limit. In all but the smallest scale test, only a fraction of the injected microsphere mass was recovered, with the smaller microspheres being recovered to a greater extent than the larger microspheres. Using existing theory, we hypothesize that the observed microsphere early arrival was due to volume exclusion and attenuation was due to aggregation and/or settling during transport. In most tests, microspheres were detected using flow cytometry, which proved to be an excellent method of analysis. CML microspheres appear to be useful tracers for fractured rock in forced gradient and short-term natural gradient tests, but longer residence times may result in small microsphere recoveries.Understanding colloid transport in ground water is essential to assessing the migration of colloid-size contaminants, the facilitation of dissolved contaminant transport by colloids, in situ bioremediation, and the health risks of pathogen contamination in drinking water wells. Much has been learned through laboratory and field-scale colloid tracer tests, but progress has been hampered by a lack of consistent tracer testing methodology at different scales and fluid velocities. This paper presents laboratory and field tracer tests in fractured rock that use the same type of colloid tracer over an almost three orders-of-magnitude range in scale and fluid velocity. Fluorescently-dyed carboxylate-modified latex (CML) microspheres (0.19 to 0.98 ??m diameter) were used as tracers in (1) a naturally fractured tuff sample, (2) a large block of naturally fractured granite, (3) a fractured granite field site, and (4) another fractured granite/schist field site. In all cases, the mean transport time of the microspheres was shorter than the solutes, regardless of detection limit. In all but the smallest scale test, only a fraction of the injected microsphere mass was recovered, with the smaller microspheres being recovered to a greater extent than the larger microspheres. Using existing theory, we hypothesize that the observed microsphere early arrival was due to volume exclusion and attenuation was due to aggregation and/or settling during transport. In most tests, microspheres were detected using flow cytometry, which proved to be an excellent method of analysis. CML microspheres appear to be useful tracers for fractured rock in forced gradient and short-term natural gradient tests, but longer residence times may result in small microsphere recoveries.

Field and laboratory investigations of inactivation of viruses (PRD1 and MS2) attached to iron oxide-coated quartz san

USGS Publications Warehouse

Ryan, Joseph N.; Harvey, Ronald W.; Metge, David W.; Elimelech, Menachem; Navigato, Theresa; Pieper, Ann P.

2002-01-01

Field and laboratory experiments were conducted to investigate inactivation of viruses attached to mineral surfaces. In a natural gradient transport field experiment, bacteriophage PRD1, radiolabeled with 32P, was injected into a ferric oxyhydroxide-coated sand aquifer with bromide and linear alkylbenzene sulfonates. In a zone of the aquifer contaminated by secondary sewage infiltration, small fractions of infective and 32P-labeled PRD1 broke through with the bromide tracer, followed by the slow release of 84% of the 32P activity and only 0.011% of the infective PRD1. In the laboratory experiments, the inactivation of PRD1, labeled with 35S (protein capsid), and MS2, dual radiolabeled with 35S (protein capsid) and 32P (nucleic acid), was monitored in the presence of groundwater and sediment from the contaminated zone of the field site. Release of infective viruses decreased at a much faster rate than release of the radiolabels, indicating that attached viruses were undergoing surface inactivation. Disparities between 32P and35S release suggest that the inactivated viruses were released in a disintegrated state. Comparison of estimated solution and surface inactivation rates indicates solution inactivation is ∼3 times as fast as surface inactivation. The actual rate of surface inactivation may be substantially underestimated owing to slow release of inactivated viruses.

Leaching of oxadyxil and tebuconazole in Colombian soil.

PubMed

Aldana, M; De Prado, R; Martínez, M J

2011-01-01

Lake Tota (Boyaca, Colombia) supplies water for human consumption, agriculture and industry for more than 500.000 people. Oxadixyl and Tebuconazole are fungicides used in onion crops in the lake catchment area. The mobility of pesticides in soil, bioavailability and transfer to other environmental compartments depend on sorption and desorption kinetics and mechanisms. An understanding of these processes is essential for transport modeling and the rational design of corrective measures against pollution. A displacement study was performed on a hand packed soil column in laboratory conditions. A pulse of 0,01 M CaCl2 solution, containing a tracer (Bromide) and the fungicides Oxadixyl y Tebuconazole, was injected. Column experiment was performed at 0.078 cmh(-1) flow rate under unsaturated conditions. Eluates were collected in flasks at constant intervals and the volumes of eluate were recorded. After rainfall simulation, the soil from the column was sliced into six successive sections (5 cm). Methanol extraction was used to determine the fungicide in each soil section. Samples were measured by HPLC. Only Oxadixyl was recovered in leachates. Unlike bromide breakthrough curve, Oxadixyl was asymmetrical, with early breakthrough and increased tailing. The percentage eluted was 96.7% after ten pore volumes. Tebuconazole showed the highest retention in the first five cm of soil layer. The results suggest that oxadyxil presents highs risk to leachate through the soil profile and that Tebuconazole is strongly absorbed in Colombian soil.

Impact of rainfall intensity on the transport of two herbicides in undisturbed grassed filter strip soil cores

NASA Astrophysics Data System (ADS)

Pot, V.; Šimůnek, J.; Benoit, P.; Coquet, Y.; Yra, A.; Martínez-Cordón, M.-J.

2005-12-01

Two series of displacement experiments with isoproturon and metribuzin herbicides were performed on two undisturbed grassed filter strip soil cores, under unsaturated steady-state flow conditions. Several rainfall intensities (0.070, 0.147, 0.161, 0.308 and 0.326 cm h - 1 ) were used. A water tracer (bromide) was simultaneously injected in each displacement experiment. A descriptive analysis of experimental breakthrough curves of bromide and herbicides combined with a modeling analysis showed an impact of rainfall intensity on the solute transport. Two contrasting physical non-equilibrium transport processes occurred. Multiple (three) porosity domains contributed to flow at the highest rainfall intensities, including preferential flow through macropore pathways. Macropores were not active any longer at intermediate and lowest velocities, and the observed preferential transport was described using dual-porosity-type models with a zero or low flow in the matrix domain. Chemical non-equilibrium transport of herbicides was found at all rainfall intensities. Significantly higher estimated values of degradation rate parameters as compared to batch data were correlated with the degree of non-equilibrium sorption. Experimental breakthrough curves were analyzed using different physical and chemical equilibrium and non-equilibrium transport models: convective-dispersive model (CDE), dual-porosity model (MIM), dual-permeability model (DP), triple-porosity, dual permeability model (DP-MIM); each combined with both chemical instantaneous and kinetic sorption.

Experimental and numerical study of the relation between flow paths and fate of a pesticide in a riparian wetland

NASA Astrophysics Data System (ADS)

Kidmose, Jacob; Dahl, Mette; Engesgaard, Peter; Nilsson, Bertel; Christensen, Britt S. B.; Andersen, Stine; Hoffmann, Carl Christian

2010-05-01

SummaryA field-scale pulse-injection experiment with the herbicide Isoproturon was conducted in a Danish riparian wetland. A non-reactive tracer (bromide) experiment was also carried out to characterize the physical transport system. Groundwater flow and reactive transport modelling was used to simulate flow paths, residence times, as well as bromide and Isoproturon distributions. The wetland can be characterized by two distinct riparian flow paths; one flow path discharges 2/3 of the incoming groundwater directly to the free water surface of the wetland near the foot of the hillslope with an average residence time of 205 days, and another flow path diffusively discharging the remaining 1/3 of the incoming groundwater to the stream with an average residence time of 425 days. The reactive transport simulations reveal that Isoproturon is retarded by a factor of 2-4, which is explained by the high organic content in the peat layer of the wetland. Isoproturon was found to be aerobically degraded with a half-life in the order of 12-80 days. Based on the quantification of flow paths, residence times and half-lives it is estimated that about 2/3 of the injected Isoproturon is removed in the wetland. Thus, close to 1/3 may find its way to the stream through overland flow. It is also possible that high concentrations of metabolites will reach the stream.

First Tracer Test After Circulation in Desert Peak 27-15

DOE Data Explorer

Rose, Peter

2013-11-16

Following the successful stimulation of Desert Peak target EGS well 27-15, a circulation test was initiated by injecting a conservative tracer (1,5-nds) in combination with a reactive tracer (7-amino-1,3-naphthalene disulfonate). The closest production well 74-21 was monitored over the subsequent several months.

ANALYSIS OF A GAS-PHASE PARTITIONING TRACER TEST CONDUCTED IN AN UNSATURATED FRACTURED-CLAY FORMATION

EPA Science Inventory

The gas-phase partitioning tracer method was used to estimate non-aqueous phase liquid (NAPL), water, and air saturations in the vadose zone at a chlorinated-solvent contaminated field site in Tucson, AZ. The tracer test was conducted in a fractured-clay system that is the confin...

Mapping fracture flow paths with a nanoscale zero-valent iron tracer test and a flowmeter test

NASA Astrophysics Data System (ADS)

Chuang, Po-Yu; Chia, Yeeping; Chiu, Yung-Chia; Teng, Mao-Hua; Liou, Sofia Ya Hsuan

2018-02-01

The detection of preferential flow paths and the characterization of their hydraulic properties are important for the development of hydrogeological conceptual models in fractured-rock aquifers. In this study, nanoscale zero-valent iron (nZVI) particles were used as tracers to characterize fracture connectivity between two boreholes in fractured rock. A magnet array was installed vertically in the observation well to attract arriving nZVI particles and identify the location of the incoming tracer. Heat-pulse flowmeter tests were conducted to delineate the permeable fractures in the two wells for the design of the tracer test. The nZVI slurry was released in the screened injection well. The arrival of the slurry in the observation well was detected by an increase in electrical conductivity, while the depth of the connected fracture was identified by the distribution of nZVI particles attracted to the magnet array. The position where the maximum weight of attracted nZVI particles was observed coincides with the depth of a permeable fracture zone delineated by the heat-pulse flowmeter. In addition, a saline tracer test produced comparable results with the nZVI tracer test. Numerical simulation was performed using MODFLOW with MT3DMS to estimate the hydraulic properties of the connected fracture zones between the two wells. The study results indicate that the nZVI particle could be a promising tracer for the characterization of flow paths in fractured rock.

Preferential flow paths in fractured rock detected by cross-borehole nano-iron tracer test

NASA Astrophysics Data System (ADS)

Chia, Yeeping; Chuang, Po-Yu

2017-04-01

Characterization of the preferential flow paths and their hydraulic properties is desirable for developing a hydrogeological conceptual model in fractured rock. However, the heterogeneity and anisotropy of the hydraulic property often make it difficult to understand groundwater flow paths through fractures. In this study, we adopted nanoscale zero-valent iron (nZVI) as a tracer to characterize fracture connectivity and hydraulic properties. A magnet array was placed in an observation well to attract arriving nZVI particles for identifying the location of incoming tracer. This novel approach was developed for the investigation of fracture flow at a hydrogeological research station in central Taiwan. A heat-pulse flowmeter test was performed to delineate the vertical distribution of permeable fractures in two boreholes, making it possible to design a field tracer test. The nZVI slurry was released in the sealed injection well. The arrival of the slurry in the observation well was evidenced by a breakthrough curve recorded by the fluid conductivity sensor as well as the nZVI particles attracted to the magnets. The iron nanoparticles attracted to the magnets provide the quantitative criteria for locating the position of tracer inlet in the observation well. The position of the magnet attracting the maximum weight of iron nanoparticles agrees well with the depth of a permeable fracture zone delineated by the flowmeter. Besides, a conventional saline tracer test was conducted in the field, producing a similar outcome as the nZVI tracer test. Our study results indicate that the nano-iron tracer test could be a promising method for the characterization of the preferential flow paths in fractured rock.

Hydrological mixing and geochemical processes characterization in an estuarine/mangrove system using environmental tracers in Babitonga Bay (Santa Catarina, Brazil)

NASA Astrophysics Data System (ADS)

Barros Grace, Virgínia; Mas-Pla, Josep; Oliveira Novais, Therezinha; Sacchi, Elisa; Zuppi, Gian Maria

2008-03-01

The hydrologic complex of Babitonga Bay (Brazil) forms a vast environmental complex where agriculture, shellfish farming, and industries coexist with a unique natural area of Atlantic rain forest and mangrove systems. The origin of different continental hydrological components, the environmental transition between saline and freshwaters, and the influence of the seasonality on Babitonga Bay waters are evaluated using isotopes and chemistry. End-member mixing analysis is used to explore hydrological processes in the bay. We show that a mixing of waters from different origins takes place in the bay modifying its chemical characteristics. Furthermore, biogeochemical processes related to well-developed mangrove systems are responsible for an efficient bromide uptake, which limit its use as a tracer as commonly used in non-biologically active environments. Seasonal behaviours are also distinguished from our datasets. The rainy season (April) provides a homogenization of the hydrological processes that is not seen after the dry season (October), when larger spatial differences appear and when the effects of biological processes on the bay hydrochemistry are more dynamic, or can be better recognized. Moreover, Cl/Br and stable isotopes of water molecule allow a neat definition of the hydrological and biogeochemical processes that control chemical composition in coastal and transition areas.

In vitro Cell Viability by CellProfiler® Software as Equivalent to MTT Assay.

PubMed

Gasparini, Luciana S; Macedo, Nayana D; Pimentel, Elisângela F; Fronza, Marcio; Junior, Valdemar L; Borges, Warley S; Cole, Eduardo R; Andrade, Tadeu U; Endringer, Denise C; Lenz, Dominik

2017-07-01

This study evaluated in vitro cell viability by the colorimetric MTT stands for 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay compared to image analysis by CellProfiler ® software. Hepatoma (Hepa-1c1c7) and fibroblast (L929) cells were exposed to isolated substances, camptothecin, lycorine, tazettine, albomaculine, 3-epimacronine, trispheridine, galanthine and Padina gymnospora , Sargassum sp. methanolic extract, and Habranthus itaobinus Ravenna ethyl acetate in different concentrations. After MTT assay, cells were stained with Panotic dye kit. Cell images were obtained with an inverted microscope equipped with a digital camera. The images were analyzed by CellProfiler ® . No cytotoxicity at the highest concentration analyzed for 3-epimacronine, albomaculine, galanthine, trispheridine, P. gymnospora extract and Sargassum sp. extract where detected. Tazettine offered cytotoxicity only against the Hepa1c1c7 cell line. Lycorine, camptothecin, and H. itaobinus extract exhibited cytotoxic effects in both cell lines. The viability methods tested were correlated demonstrated by Bland-Atman test with normal distribution with mean difference between the two methods close to zero, bias value 3.0263. The error was within the limits of the confidence intervals and these values had a narrow difference. The correlation between the two methods was demonstrated by the linear regression plotted as R 2 . CellProfiler ® image analysis presented similar results to the MTT assay in the identification of viable cells, and image analysis may assist part of biological analysis procedures. The presented methodology is inexpensive and reproducible. In vitro cell viability assessment with MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay may be replaced by image analysis by CellProfiler ® . The viability methods tested were correlated demonstrated by Bland-Atman test with normal distribution with mean difference between the two methods close to zero, bias value 3.0263. The correlation between the two methods was demonstrated by the linear regression plotted as R2. Abbreviations: HPLC: High pressure liquid chromatography MTT: (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide).

Alkali Halide FLIR Lens Development

DTIC Science & Technology

1981-10-01

in the atmosphere. The main emphasis in this 3 report has been development of protective coatings for potassium bromide lenses. The most favorable...placed onto the bottom electrode. Pieces of single-crystalline potassium chloride of approximately the same thickness as coated alkali halide samples...none of the samples appeared to be degraded by the high humidity associated with the exposure. 2. UNITS TESTED Four coated potassium bromide lenses

Optical detection of tracer species in strongly scattering media.

PubMed

Brauser, Eric M; Rose, Peter E; McLennan, John D; Bartl, Michael H

2015-03-01

A combination of optical absorption and scattering is used to detect tracer species in a strongly scattering medium. An optical setup was developed, consisting of a dual-beam scattering detection scheme in which sample scattering beam overlaps with the characteristic absorption feature of quantum dot tracer species, while the reference scattering beam is outside any absorption features of the tracer. This scheme was successfully tested in engineered breakthrough tests typical of wastewater and subsurface fluid analysis, as well as in batch analysis of oil and gas reservoir fluids and biological samples. Tracers were detected even under highly scattering conditions, conditions in which conventional absorption or fluorescence methods failed.

In situ measurement of methane oxidation in groundwater by using natural-gradient tracer tests

USGS Publications Warehouse

Smith, R.L.; Howes, B.L.; Garabedian, S.P.

1991-01-01

Methane oxidation was measured in an unconfined sand and gravel aquifer (Cape Cod, Mass.) by using in situ natural-gradient tracer tests at both a pristine, oxygenated site and an anoxic, sewage-contaminated site. The tracer sites were equipped with multilevel sampling devices to create target grids of sampling points; the injectate was prepared with groundwater from the tracer site to maintain the same geochemical conditions. Methane oxidation was calculated from breakthrough curves of methane relative to halide and inert gas (hexafluoroethane) tracers and was confirmed by the appearance of 13C-enriched carbon dioxide in experiments in which 13C-enriched methane was used as the tracer. A V(max) for methane oxidation could be calculated when the methane concentration was sufficiently high to result in zero-order kinetics throughout the entire transport interval. Methane breakthrough curves could be simulated by modifying a one-dimensional advection-dispersion transport model to include a Michaelis-Menten-based consumption term for methane oxidation. The K(m) values for methane oxidation that gave the best match for the breakthrough curve peaks were 6.0 and 9.0 ??M for the uncontaminated and contaminated sites, respectively. Natural-gradient tracer tests are a promising approach for assessing microbial processes and for testing in situ bioremediation potential in groundwater systems.

In situ measurement of methane oxidation in groundwater by using natural-gradient tracer tests.

PubMed Central

Smith, R L; Howes, B L; Garabedian, S P

1991-01-01

Methane oxidation was measured in an unconfined sand and gravel aquifer (Cape Cod, Mass.) by using in situ natural-gradient tracer tests at both a pristine, oxygenated site and an anoxic, sewage-contaminated site. The tracer sites were equipped with multilevel sampling devices to create target grids of sampling points; the injectate was prepared with groundwater from the tracer site to maintain the same geochemical conditions. Methane oxidation was calculated from breakthrough curves of methane relative to halide and inert gas (hexafluroethane) tracers and was confirmed by the appearance of 13C-enriched carbon dioxide in experiments in which 13C-enriched methane was used as the tracer. A Vmax for methane oxidation could be calculated when the methane concentration was sufficiently high to result in zero-order kinetics throughout the entire transport interval. Methane breakthrough curves could be simulated by modifying a one-dimensional adevection-dispersion transport model to include a Michaelis-Menten-based consumption term for methane oxidation. The Km values for methane oxidation that gave the best match for the breakthrough curve peaks were 6.0 and 9.0 microM for the uncontaminated and contaminated sites, respectively. Natural-gradient tracer tests are a promising approach for assessing microbial processes and for testing in situ bioremediation potential in groundwater systems. PMID:1892389

Performance Testing of Tracer Gas and Tracer Aerosol Detectors for use in Radionuclide NESHAP Compliance Testing

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

Fuehne, David Patrick; Lattin, Rebecca Renee

The Rad-NESHAP program, part of the Air Quality Compliance team of LANL’s Compliance Programs group (EPC-CP), and the Radiation Instrumentation & Calibration team, part of the Radiation Protection Services group (RP-SVS), frequently partner on issues relating to characterizing air flow streams. This memo documents the most recent example of this partnership, involving performance testing of sulfur hexafluoride detectors for use in stack gas mixing tests. Additionally, members of the Rad-NESHAP program performed a functional trending test on a pair of optical particle counters, comparing results from a non-calibrated instrument to a calibrated instrument. Prior to commissioning a new stack samplingmore » system, the ANSI Standard for stack sampling requires that the stack sample location must meet several criteria, including uniformity of tracer gas and aerosol mixing in the air stream. For these mix tests, tracer media (sulfur hexafluoride gas or liquid oil aerosol particles) are injected into the stack air stream and the resulting air concentrations are measured across the plane of the stack at the proposed sampling location. The coefficient of variation of these media concentrations must be under 20% when evaluated over the central 2/3 area of the stack or duct. The instruments which measure these air concentrations must be tested prior to the stack tests in order to ensure their linear response to varying air concentrations of either tracer gas or tracer aerosol. The instruments used in tracer gas and aerosol mix testing cannot be calibrated by the LANL Standards and Calibration Laboratory, so they would normally be sent off-site for factory calibration by the vendor. Operational requirements can prevent formal factory calibration of some instruments after they have been used in hazardous settings, e.g., within a radiological facility with potential airborne contamination. The performance tests described in this document are intended to demonstrate the reliable performance of the test instruments for the specific tests used in stack flow characterization.« less

Combining 3D Hydraulic Tomography with Tracer Tests for Improved Transport Characterization.

PubMed

Sanchez-León, E; Leven, C; Haslauer, C P; Cirpka, O A

2016-07-01

Hydraulic tomography (HT) is a method for resolving the spatial distribution of hydraulic parameters to some extent, but many details important for solute transport usually remain unresolved. We present a methodology to improve solute transport predictions by combining data from HT with the breakthrough curve (BTC) of a single forced-gradient tracer test. We estimated the three dimensional (3D) hydraulic-conductivity field in an alluvial aquifer by inverting tomographic pumping tests performed at the Hydrogeological Research Site Lauswiesen close to Tübingen, Germany, using a regularized pilot-point method. We compared the estimated parameter field to available profiles of hydraulic-conductivity variations from direct-push injection logging (DPIL), and validated the hydraulic-conductivity field with hydraulic-head measurements of tests not used in the inversion. After validation, spatially uniform parameters for dual-domain transport were estimated by fitting tracer data collected during a forced-gradient tracer test. The dual-domain assumption was used to parameterize effects of the unresolved heterogeneity of the aquifer and deemed necessary to fit the shape of the BTC using reasonable parameter values. The estimated hydraulic-conductivity field and transport parameters were subsequently used to successfully predict a second independent tracer test. Our work provides an efficient and practical approach to predict solute transport in heterogeneous aquifers without performing elaborate field tracer tests with a tomographic layout. © 2015, National Ground Water Association.

Single well thermal tracer test, a new experimental set up for characterizing thermal transport in fractured media

NASA Astrophysics Data System (ADS)

de La Bernardie, Jérôme; Bour, Olivier; Guihéneuf, Nicolas; Chatton, Eliot; Labasque, Thierry; Longuevergne, Laurent; Le Lay, Hugo; Koch, Floriant; Gerard, Marie-Françoise; Le Borgne, Tanguy

2017-04-01

Thermal transport in fractured media depends on the hydrological properties of fractures and thermal characteristics of rock. Tracer tests using heat as tracer can thus be a good alternative to characterize fractured media for shallow geothermal needs. This study investigates the possibility of implementing a new thermal tracer test set up, the single well thermal tracer test, to characterize hydraulic and thermal transport properties of fractured crystalline rock. The experimental setup is based on injecting hot water in a fracture isolated by a double straddle packer in the borehole while pumping and monitoring the temperature in a fracture crossing the same borehole at greater elevation. One difficulty comes from the fact that injection and withdrawal are achieved in the same borehole involving thermal losses along the injection tube that may disturb the heat recovery signal. To be able to well localize the heat influx, we implemented a Fiber-Optic Distributed Temperature Sensing (FO-DTS) which allows the temperature monitoring with high spatial and temporal resolution (29 centimeters and 30 seconds respectively). Several tests, at different pumping and injection rates, were performed in a crystalline rock aquifer at the experimental site of Ploemeur (H+ observatory network). We show through signal processing how the thermal breakthrough may be extracted thanks to Fiber-Optic distributed temperature measurements. In particular, we demonstrate how detailed distributed temperature measurements were useful to identify different inflows and to estimate how much heat was transported and stored within the fractures network. Thermal breakthrough curves of single well thermal tracer tests were then interpreted with a simple analytical model to characterize hydraulic and thermal characteristics of the fractured media. We finally discuss the advantages of these tests compared to cross-borehole thermal tracer tests.

Long residence times - bad tracer tests?

NASA Astrophysics Data System (ADS)

Ghergut, Julia; Behrens, Horst; Sauter, Martin

2015-04-01

Tracer tests conducted at geothermal well doublets or triplets in the Upper Rhine Rift Valley [1] all face, with very few exceptions so far, one common issue: lack of conclusive tracer test results, or tracer signals still undetectable for longer than one or two years after tracer injection. While the reasons for this surely differ from site to site (Riehen, Landau, Insheim, Bruchsal, ...), its effects on how the usefulness of tracer tests is perceived by the non-tracer community are pretty much the same. The 'poor-signal' frustration keeps nourishing two major 'alternative' endeavours : (I) design and execute tracer tests in single-well injection-withdrawal (push-pull), 'instead of' inter-well flow-path tracing configurations; (II) use 'novel' tracer substances instead of the 'old' ones which have 'obviously failed'. Frustration experienced with most inter-well tracer tests in the Upper Rhine Rift Valley has also made them be regarded as 'maybe useful for EGS' ('enhanced', or 'engineered' geothermal systems, whose fluid RTD typically include a major share of values below one year), but 'no longer worthwhile a follow-up sampling' in natural, large-scale hydrothermal reservoirs. We illustrate some of these arguments with the ongoing Bruchsal case [2]. The inter-well tracer test conducted at Bruchsal was (and still is!) aimed at assessing inter-well connectivity, fluid residence times, and characterizing the reservoir structure [3]. Fluid samples taken at the geothermal production well after reaching a fluid turnover of about 700,000 m3 showed tracer concentrations in the range of 10-8 Minj per m3, in the liquid phase of each sample (Minj being the total quantity of tracer injected as a short pulse at the geothermal re-injection well). Tracer signals might actually be higher, owing to tracer amounts co-precipitated and/or adsorbed onto the solid phase whose accumulation in the samples was unavoidable (due to pressure relief and degassing during the very sampling process, and later on during sample aeration); the adsorbed and/or co-precipitated tracer amounts appear to be non-zero, but their accurate metering was not completed to date. Thus, a conservative estimate of cumulative tracer recovery amounts to (at least) 2 parts-per-thousand for the first 700,000 m3 of fluid turnover within the geothermal well doublet. Neither do such recovery values automatically imply 'bad news' (poor inter-well connectivity), nor do they appear as implausibly low (cf. fig. 2 of [3]), considering the possibility of major vertical drainage along the large-scale fault zone that isolates the 'aquifer basin' around the re-injection well from the 'aquifer catchment' around the production well, along with the prospect of transport-effective porosity and/or thickness within these 'aquifers' being rather high, due to extensive fissuring/fracturing. In more general terms, we argue that (a) inter-well flow-path spikings are still worthwhile being conducted even in large-scale hydrothermal reservoirs; (b) results gained from single-well tests [3] can never serve as a substitute for the kind of information (primarily: residence time distribution RTD, or flow-storage repartition FSR) being expected from inter-well tests; (c) tracer species that are 'novel' in terms of thermo-/reactivity/sorptivity/exchange at phase interfaces and thus involve some transport-retarding process cannot alleviate the frustration associated with long RT; (d) augmenting the tracer quantity Minj to use for inter-well spiking might render the tracer signal detectable, say, one or two years earlier, but it does not make FSR available sooner, since Minj cannot alter the RTD of fluids traveling through the reservoir; moreover, for inter-well configurations and reservoir structures typical of the Upper Rhine Rift Valley, the Minj augmenting factors necessary to render tracer signals detectable 1 or 2 years earlier mostly range beyond the limits of the reasonably-recommendable (e. g., for Bruchsal: 2 tons, instead of 100 kg of a particular tracer). Acknowledgements: We gratefully acknowledge financial support from Energie Baden-Württemberg (EnBW), from the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, and from the Federal Ministry for Economic Affairs and Energy (BMU and BMWi, Germany), within research projects with grant nos. 0327579, 0325111B, 0325515. References: [1] www.bfe.admin.ch/forschunggeothermie/02484/02766/index.html?lang=de&dossier_id=06049 [2] http://www.geothermal-energy.org/pdf/IGAstandard/WGC/2010/0619.pdf [3] presentations.copernicus.org/EGU2012-13687_presentation.pdf

Tracer tests and the structure of permeability in the Corallian limestone aquifer of northern England, UK

NASA Astrophysics Data System (ADS)

Foley, Aidan; Cachandt, Gerd; Franklin, Janine; Willmore, Fergus; Atkinson, Tim

2012-05-01

The Corallian limestone of northern England (UK) is widely exploited for water supplies and exhibits the karstic phenomena of sinking rivers, conduit development and groundwater velocities of several kilometres per day. To test a number of model-derived source protection zones and elucidate contaminant transport mechanisms in the aquifer, three tracer tests were conducted from a set of swallow-holes draining the River Derwent toward public water supply wells in the eastern part of the aquifer. Tracers used included: Enterobacter cloacae (bacteriophage), Photine C (optical brightener), sodium fluorescein (fluorescent dye) and sulphur hexafluoride (dissolved gas), the varying properties of which make them suitable analogues for different types of potential contaminant. Observed tracer transport times and arrival patterns indicate that tracer transport occurs through karstic channels embedded in a network of primary fissures which exert control over tracer concentrations once initial tracer plumes have passed. A dipole flow system is observed between the swallow-holes and the closest abstraction well, whilst previously modelled source protection zones do not accurately reflect either groundwater velocity or those areas of the aquifer supplying the wells. These findings imply that managing such aquifers for potential contamination should rely upon empirical tracer evidence for source-protection zone modelling.

Insight from simulations of single-well injection-withdrawal tracer tests on simple and complex fractures

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

Tsang, C.-F.; Doughty, C.

2009-08-06

The single-well injection withdrawal (SWIW) test, a tracer test utilizing only one well, is proposed as a useful contribution to site characterization of fractured rock, as well as providing parameters relevant to tracer diffusion and sorption. The usual conceptual model of flow and solute transport through fractured rock with low matrix permeability involves solute advection and dispersion through a fracture network coupled with diffusion and sorption into the surrounding rock matrix. Unlike two-well tracer tests, results of SWIW tests are ideally independent of advective heterogeneity, channeling and flow dimension, and, instead, focus on diffusive and sorptive characteristics of tracer (solute)more » transport. Thus, they can be used specifically to study such characteristics and evaluate the diffusive parameters associated with tracer transport through fractured media. We conduct simulations of SWIW tests on simple and complex fracture models, the latter being defined as having two subfractures with altered rock blocks in between and gouge material in their apertures. Using parameters from the Aspo site in Sweden, we calculate and study SWIW tracer breakthrough curves (BTCs) from a test involving four days of injection and then withdrawal. By examining the peak concentration C{sub pk} of the SWIW BTCs for a variety of parameters, we confirm that C{sub pk} is largely insensitive to the fracture advective flow properties, in particular to permeability heterogeneity over the fracture plane or to subdividing the flow into two subfractures in the third dimension orthogonal to the fracture plane. The peak arrival time t{sub pk} is not a function of fracture or rock properties, but is controlled by the time schedule of the SWIW test. The study shows that the SWIW test is useful for the study of tracer diffusion-sorption processes, including the effect of the so-called flow-wetted surface (FWS) of the fracture. Calculations with schematic models with different FWS values are conducted and the possibility of direct in situ measurement of FWS with SWIW tests is demonstrated.« less

Effect of increasing bromide concentration on toxicity in treated drinking water.

PubMed

Sawade, Emma; Fabris, Rolando; Humpage, Andrew; Drikas, Mary

2016-04-01

Research is increasingly indicating the potential chronic health effects of brominated disinfection by-products (DBPs). This is likely to increase with elevated bromide concentrations resulting from the impacts of climate change, projected to include extended periods of drought and the sudden onset of water quality changes. This will demand more rigorous monitoring throughout distribution systems and improved water quality management at water treatment plants (WTPs). In this work the impact of increased bromide concentration on formation of DBPs following conventional treatment and chlorination was assessed for two water sources. Bioanalytical tests were utilised to determine cytotoxicity of the water post disinfection. Coagulation was shown to significantly reduce the cytotoxicity of the water, indicating that removal of natural organic matter DBP precursors continues to be an important factor in drinking water treatment. Most toxic species appear to form within the first half hour following disinfectant addition. Increasing bromide concentration across the two waters was shown to increase the formation of trihalomethanes and shifted the haloacetic acid species distribution from chlorinated to those with greater bromine substitution. This correlated with increasing cytotoxicity. This work demonstrates the challenges faced by WTPs and the possible effects increasing levels of bromide in source waters could have on public health.

Data for methyl bromide decon testing

EPA Pesticide Factsheets

Spreadsheets containing data for recovery of spores from different materials. Data on the fumigation parameters are also included.This dataset is associated with the following publication:Wood , J., M. Wendling, W. Richter, A. Lastivka, and L. Mickelsen. Evaluation of the Efficacy of Methyl Bromide in the Decontamination of Building and Interior Materials Contaminated with Bacillus anthracis Spores. APPLIED AND ENVIRONMENTAL MICROBIOLOGY. American Society for Microbiology, Washington, DC, USA, 1-28, (2016).

A New Kind of Single-Well Tracer Test for Assessing Subsurface Heterogeneity

NASA Astrophysics Data System (ADS)

Hansen, S. K.; Vesselinov, V. V.; Lu, Z.; Reimus, P. W.; Katzman, D.

2017-12-01

Single-well injection-withdrawal (SWIW) tracer tests have historically been interpreted using the idealized assumption of tracer path reversibility (i.e., negligible background flow), with background flow due to natural hydraulic gradient being an un-modeled confounding factor. However, we have recently discovered that it is possible to use background flow to our advantage to extract additional information about the subsurface. To wit: we have developed a new kind of single-well tracer test that exploits flow due to natural gradient to estimate the variance of the log hydraulic conductivity field of a heterogeneous aquifer. The test methodology involves injection under forced gradient and withdrawal under natural gradient, and makes use of a relationship, discovered using a large-scale Monte Carlo study and machine learning techniques, between power law breakthrough curve tail exponent and log-hydraulic conductivity variance. We will discuss how we performed the computational study and derived this relationship and then show an application example in which our new single-well tracer test interpretation scheme was applied to estimation of heterogeneity of a formation at the chromium contamination site at Los Alamos National Laboratory. Detailed core hole records exist at the same site, from which it was possible to estimate the log hydraulic conductivity variance using a Kozeny-Carman relation. The variances estimated using our new tracer test methodology and estimated by direct inspection of core were nearly identical, corroborating the new methodology. Assessment of aquifer heterogeneity is of critical importance to deployment of amendments associated with in-situ remediation strategies, since permeability contrasts potentially reduce the interaction between amendment and contaminant. Our new tracer test provides an easy way to obtain this information.

Fate of Volatile Organic Compounds in Constructed Wastewater Treatment Wetlands

USGS Publications Warehouse

Keefe, S.H.; Barber, L.B.; Runkel, R.L.; Ryan, J.N.

2004-01-01

The fate of volatile organic compounds was evaluated in a wastewater-dependent constructed wetland near Phoenix, AZ, using field measurements and solute transport modeling. Numerically based volatilization rates were determined using inverse modeling techniques and hydraulic parameters established by sodium bromide tracer experiments. Theoretical volatilization rates were calculated from the two-film method incorporating physicochemical properties and environmental conditions. Additional analyses were conducted using graphically determined volatilization rates based on field measurements. Transport (with first-order removal) simulations were performed using a range of volatilization rates and were evaluated with respect to field concentrations. The inverse and two-film reactive transport simulations demonstrated excellent agreement with measured concentrations for 1,4-dichlorobenzene, tetrachloroethene, dichloromethane, and trichloromethane and fair agreement for dibromochloromethane, bromo-dichloromethane, and toluene. Wetland removal efficiencies from inlet to outlet ranged from 63% to 87% for target compounds.

Heat tracer test in an alluvial aquifer: Field experiment and inverse modelling

NASA Astrophysics Data System (ADS)

Klepikova, Maria; Wildemeersch, Samuel; Hermans, Thomas; Jamin, Pierre; Orban, Philippe; Nguyen, Frédéric; Brouyère, Serge; Dassargues, Alain

2016-09-01

Using heat as an active tracer for aquifer characterization is a topic of increasing interest. In this study, we investigate the potential of using heat tracer tests for characterization of a shallow alluvial aquifer. A thermal tracer test was conducted in the alluvial aquifer of the Meuse River, Belgium. The tracing experiment consisted in simultaneously injecting heated water and a dye tracer in an injection well and monitoring the evolution of groundwater temperature and tracer concentration in the pumping well and in measurement intervals. To get insights in the 3D characteristics of the heat transport mechanisms, temperature data from a large number of observation wells closely spaced along three transects were used. Temperature breakthrough curves in observation wells are contrasted with what would be expected in an ideal layered aquifer. They reveal strongly unequal lateral and vertical components of the transport mechanisms. The observed complex behavior of the heat plume is explained by the groundwater flow gradient on the site and heterogeneities in the hydraulic conductivity field. Moreover, due to high injection temperatures during the field experiment a temperature-induced fluid density effect on heat transport occurred. By using a flow and heat transport numerical model with variable density coupled with a pilot point approach for inversion of the hydraulic conductivity field, the main preferential flow paths were delineated. The successful application of a field heat tracer test at this site suggests that heat tracer tests is a promising approach to image hydraulic conductivity field. This methodology could be applied in aquifer thermal energy storage (ATES) projects for assessing future efficiency that is strongly linked to the hydraulic conductivity variability in the considered aquifer.

Surface time-lapse electrical resistivity tomography (TLERT) monitoring of an SRS injection and associated biogeochemical processes, Oak Ridge National Laboratory, Tennessee USA

NASA Astrophysics Data System (ADS)

Baker, G. S.; Wu, Y.; Hubbard, S. S.; Wu, W.; Gaines, D. P.; Pratt, J. C.; Modi, A. L.; Watson, D.; Jardine, P.

2009-05-01

We present results from surface time-lapse electrical resistivity tomography (TLERT) data collected within a uranium-contaminated unconfined aquifer underlying the Oak Ridge Field Research Center (ORFRC) located at the Oak Ridge National Laboratory (ORNL) in Tennessee. As part of an Integrated Field Research Challenge (IFRC) project supported by the DOE Environmental Remediation Sciences Program (ERSP), bioreduction of U(VI) to U(IV) with ethanol as an electron donor has been tested during the last four years. Low U concentration (below US EPA MCL of 0.03 mg/L) can be achieved by frequent injection of electron donor. To reduce the costs and improve the sustainability for remediation and site maintenance, our IFRC team is exploring the effectiveness of a slowly degrading substrate such as commercial emulsified vegetable oil substrate (EVO) as alternative electron donor sources. Laboratory batch and flow-through column experiments were carried out to investigate the sensitivity of various physical properties (e.g., electrical conductivity) to EVO injection to test the applicability of geophysics as a monitoring tool at the field scale. Results revealed increased electrical conductivity during both EVO injection and subsequent degradation of surfactant with an overall increase in conductivity of ˜35%; thus, surface TLERT was selected as a monitoring tool to supplement well fluid samples. The field stimulation test began at Area 2 during early February 2009. Prior to the injection of the EVO, preliminary characterization completed, including a geochemical survey of the ground water from ˜50 wells, microbial samples of groundwater and sediment collected from selected wells, and site hydrology characterized by bromide tracer test and surface ERT methods. On February 9, 2009, diluted EVO solution (20% concentration, 900 gal vol) was injected into three injection wells within 1.5 hours. Distribution of the injected EVO and accompanying biogeochemical processes has been monitored since injection through analysis of numerous well fluid samples and TLERT data from 2 profiles. Initial TLERT data were collected at the 2 profiles over a two-week period at 12 different time steps. The surface profiles, situated parallel to and perpendicular to the major flow direction (as delineated by tracer tests), are each 40 m long and consist of 52 electrodes spaced at 0.75 m. Initial analysis indicate good correlation between well fluid samples and TLERT data and allow for improved extrapolation of well data to the field scale. Long-term monitoring is in place to track the continuing hydrologic dynamics and reduction duration in this test area throughout Spring 2009.

Surface confined ionic liquid as a stationary phase for HPLC

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

Wang, Qian; Baker, Gary A; Baker, Sheila N

Trimethoxysilane ionosilane derivatives of room temperature ionic liquids based on alkylimidazolium bromides were synthesized for attachment to silica support material. The derivatives 1-methyl-3-(trimethoxysilylpropyl)imidazolium bromide and 1-butyl-3-(trimethoxysilylpropyl)imidazolium bromide were used to modify the surface of 3 {micro}m diameter silica particles to act as the stationary phase for HPLC. The modified particles were characterized by thermogravimetric analysis (TGA) and {sup 13}C and {sup 29}Si NMR spectroscopies. The surface modification procedure rendered particles with a surface coverage of 0.84 {micro}mol m{sup -2} for the alkylimidazolium bromide. The ionic liquid moiety was predominantly attached to the silica surface through two siloxane bonds of themore » ionosilane derivative (63%). Columns packed with the modified silica material were tested under HPLC conditions. Preliminary evaluation of the stationary phase for HPLC was performed using aromatic carboxylic acids as model compounds. The separation mechanism appears to involve multiple interactions including ion exchange, hydrophobic interaction, and other electrostatic interactions.« less

Fumigation of Jute Bags with Ethylene Oxide and Methyl Bromide to Eradicate Potato Ring Rot Bacteria1

PubMed Central

Richardson, L. T.; Monro, H. A. U.

1962-01-01

In a series of full-scale tests, the effectiveness of various fumigant treatments for the eradication of potato ring rot bacteria from bulk lots of contaminated jute bags was evaluated. Survival of these bacteria on infested sample fibers located at various positions within and around a tightly wired bale was determined quantitatively from the growth lag in a liquid medium as indicated by the rate of turbidity development. Ethylene oxide, though highly toxic to Corynebacterium sepedonicum in laboratory tests, failed to penetrate the jute sufficiently to be effective in the interior of a bale. Methyl bromide showed better penetration, but was not sufficiently toxic at practical dosage levels. A mixture of 5% ethylene oxide and 10% methyl bromide achieved complete eradication throughout a bale in an 18-hr exposure period. On the basis of these results, eradication of ring rot bacteria from contaminated jute bags by fumigation with a combination of these two gases would appear to be feasible under commercial conditions. PMID:13982125

Field-scale prediction of enhanced DNAPL dissolution based on partitioning tracers.

PubMed

Wang, Fang; Annable, Michael D; Jawitz, James W

2013-09-01

The equilibrium streamtube model (EST) has demonstrated the ability to accurately predict dense nonaqueous phase liquid (DNAPL) dissolution in laboratory experiments and numerical simulations. Here the model is applied to predict DNAPL dissolution at a tetrachloroethylene (PCE)-contaminated dry cleaner site, located in Jacksonville, Florida. The EST model is an analytical solution with field-measurable input parameters. Measured data from a field-scale partitioning tracer test were used to parameterize the EST model and the predicted PCE dissolution was compared to measured data from an in-situ ethanol flood. In addition, a simulated partitioning tracer test from a calibrated, three-dimensional, spatially explicit multiphase flow model (UTCHEM) was also used to parameterize the EST analytical solution. The EST ethanol prediction based on both the field partitioning tracer test and the simulation closely matched the total recovery well field ethanol data with Nash-Sutcliffe efficiency E=0.96 and 0.90, respectively. The EST PCE predictions showed a peak shift to earlier arrival times for models based on either field-measured or simulated partitioning tracer tests, resulting in poorer matches to the field PCE data in both cases. The peak shifts were concluded to be caused by well screen interval differences between the field tracer test and ethanol flood. Both the EST model and UTCHEM were also used to predict PCE aqueous dissolution under natural gradient conditions, which has a much less complex flow pattern than the forced-gradient double five spot used for the ethanol flood. The natural gradient EST predictions based on parameters determined from tracer tests conducted with a complex flow pattern underestimated the UTCHEM-simulated natural gradient total mass removal by 12% after 170 pore volumes of water flushing indicating that some mass was not detected by the tracers likely due to stagnation zones in the flow field. These findings highlight the important influence of well configuration and the associated flow patterns on dissolution. © 2013.

Field-scale prediction of enhanced DNAPL dissolution based on partitioning tracers

NASA Astrophysics Data System (ADS)

Wang, Fang; Annable, Michael D.; Jawitz, James W.

2013-09-01

The equilibrium streamtube model (EST) has demonstrated the ability to accurately predict dense nonaqueous phase liquid (DNAPL) dissolution in laboratory experiments and numerical simulations. Here the model is applied to predict DNAPL dissolution at a tetrachloroethylene (PCE)-contaminated dry cleaner site, located in Jacksonville, Florida. The EST model is an analytical solution with field-measurable input parameters. Measured data from a field-scale partitioning tracer test were used to parameterize the EST model and the predicted PCE dissolution was compared to measured data from an in-situ ethanol flood. In addition, a simulated partitioning tracer test from a calibrated, three-dimensional, spatially explicit multiphase flow model (UTCHEM) was also used to parameterize the EST analytical solution. The EST ethanol prediction based on both the field partitioning tracer test and the simulation closely matched the total recovery well field ethanol data with Nash-Sutcliffe efficiency E = 0.96 and 0.90, respectively. The EST PCE predictions showed a peak shift to earlier arrival times for models based on either field-measured or simulated partitioning tracer tests, resulting in poorer matches to the field PCE data in both cases. The peak shifts were concluded to be caused by well screen interval differences between the field tracer test and ethanol flood. Both the EST model and UTCHEM were also used to predict PCE aqueous dissolution under natural gradient conditions, which has a much less complex flow pattern than the forced-gradient double five spot used for the ethanol flood. The natural gradient EST predictions based on parameters determined from tracer tests conducted with a complex flow pattern underestimated the UTCHEM-simulated natural gradient total mass removal by 12% after 170 pore volumes of water flushing indicating that some mass was not detected by the tracers likely due to stagnation zones in the flow field. These findings highlight the important influence of well configuration and the associated flow patterns on dissolution.

Characterization of thermal tracer tests and heat exchanges in fractured media

NASA Astrophysics Data System (ADS)

de La Bernardie, Jérôme; Bour, Olivier; Guihéneuf, Nicolas; Chatton, Eliot; Labasque, Thierry; Longuevergne, Laurent; Le Lay, Hugo; Koch, Florian; Gerard, Marie-Françoise; Lavenant, Nicolas; Le Borgne, Tanguy

2016-04-01

Geothermal energy is a renewable energy source particularly attractive due to associated low greenhouse gas emission rates. Crystalline rocks are in general considered of poor interest for geothermal applications at shallow depths (< 100m), because of the low permeability of the medium. In some cases, fractures may enhance permeability, but thermal energy storage at these shallow depths is still remaining very challenging because of the low storativity of the medium. Within this framework, the purpose of this study is to test the possibility of efficient thermal energy storage in shallow fractured rocks with a single well semi open loop heat exchanger (standing column well). For doing so, several heat tracer tests have been achieved along a borehole between two connected fractures. The heat tracer tests have been achieved at the experimental site of Ploemeur (H+ observatory network). The tracer tests consist in monitoring the temperature in the upper fracture while injecting hot water in the deeper one thanks to a field boiler. For such an experimental setup, the main difficulty to interpret the data comes from the requirement for separating the temperature advective signal of the tracer test (temperature recovery) from the heat increase due to injection of hot water through the borehole which induces heat losses all along the injection tube in the water column. For doing so, in addition to a double straddle packer used for isolating the injection chamber, the particularity of the experimental set up is the use of fiber optic distributed temperature sensing (FO-DTS); an innovative technology which allows spatial and temporal monitoring of the temperature all along the well. Thanks to this tool, we were able to estimate heat increases coming from diffusion along the injection tube which is found much lower than localized temperature increases resulting from tracer test recovery. With local temperatures probes, separating both effects would not have been feasible. We also show through signal processing how diffusive and advective effects may be differentiated. This allowed us to estimate temperature recovery for different heat tracer durations and setups. In particular we show that temperature recovery is highly dependent on hydraulic configuration such as perfect dipole or fully convergent heat tracer tests.

Experimental study of refrigeration performance based on linear Fresnel solar thermal photovoltaic system

NASA Astrophysics Data System (ADS)

Song, Jinghui; Yuan, Hui; Xia, Yunfeng; Kan, Weimin; Deng, Xiaowen; Liu, Shi; Liang, Wanlong; Deng, Jianhua

2018-03-01

This paper introduces the working principle and system constitution of the linear Fresnel solar lithium bromide absorption refrigeration cycle, and elaborates several typical structures of absorption refrigeration cycle, including single-effect, two-stage cycle and double-effect lithium bromide absorption refrigeration cycle A 1.n effect absorption chiller system based on the best parameters was introduced and applied to a linear Fresnel solar absorption chiller system. Through the field refrigerator performance test, the results show: Based on this heat cycle design and processing 1.n lithium bromide absorption refrigeration power up to 35.2KW, It can meet the theoretical expectations and has good flexibility and reliability, provides guidance for the use of solar thermal energy.

The history and future of methyl bromide alternatives used in the production of forest seedlings in the southern United States

Treesearch

Scott A. Enebak

2013-01-01

This paper gives a brief history of the Southern Forest Nursery Management Cooperative’s (SFNMC) efforts in testing methyl bromide (MBr) alternatives for soil fumigation. In the southeastern United States, fumigation with MBr has been the most commonly used method for producing high quality, pest-free forest-tree seedlings in an environment that is conducive for soil-...

Residues after fumigation with methyl bromide: bromide ion and methyl bromide in middlings and final cereal foodstuffs.

PubMed

Cova, D; Molinari, G P; Rossini, L

1986-01-01

Methyl bromide and bromide ion concentrations were estimated in pasta manufactured before and after fumigation with methyl bromide. The first trial estimated the bromide ion concentrations in fumigated and unfumigated flours and in pastas obtained from these. The concentration of bromide ions in fumigated flours was not significantly different from unfumigated flours. Only some pastas, manufactured from fumigated flours, showed a higher bromide ion concentration than those manufactured from unfumigated flours. The second trial evaluated the bromide ion concentrations of rices, white flours, flours, pastas made only from flours, pastas with eggs and pastas with eggs and spinach, before and after exposure to methyl bromide in their retail packagings. The bromide ion concentrations in fumigated pastas with eggs, pastas with eggs and spinach and rice were higher than in those unfumigated. In the pastas with eggs the bromide ion concentration after fumigation increased ten times (from about 4 to 40 mg/kg). Results showed that the bromide ion and methyl bromide levels estimated in all the foodstuffs examined were lower than the maximum limits fixed by several different national regulations.

Preferential transport of isoproturon at a plot scale and a field scale tile-drained site

NASA Astrophysics Data System (ADS)

Zehe, Erwin; Flühler, Hannes

2001-06-01

Irrigation experiments using the tracers Brilliant Blue (BB) and Bromide (Br) were conducted on three plots of 1.4×1.4 m 2 (plot scale) and a field scale subsurface drained test site (900 m 2) to clarify mechanisms causing rapid transport of surface applied Isoproturon (IPU) during preferential flow events. One of the small plots (site 10) and the field scale test site are located on the same field. One day after irrigation of the plot scale sites the Br and IPU concentration in two vertical soil profiles as well as the macroporousity on separate profiles and hydraulic properties of single macropores were determined. During irrigation of the field scale test site discharge, soil moisture as well as the concentration of IPU and Br in the drainage outlet were measured. Preferential flow in deep penetrating earthworm burrows caused a fast breakthrough of IPU and Br into the tile drain (1.2 m depth) at the field scale site as well as leaching of IPU into the subsoil (>0.8 m) at site 10. The results suggest a hierarchy of preconditions for the occurrence of preferential flow events of which a sufficient number of deep penetrating macropores interconnected to the soil surface seems to be the most important one. Moreover there is evidence that facilitated transport of IPU attached to mobile soil particles occurred during the preferential flow events at the field scale site and site 10. The susceptibility for preferential flow as well as the susceptibility for facilitated transport appear to be intrinsic properties of the investigated soil.

Evaluation of multiple tracer methods to estimate low groundwater flow velocities.

PubMed

Reimus, Paul W; Arnold, Bill W

2017-04-01

Four different tracer methods were used to estimate groundwater flow velocity at a multiple-well site in the saturated alluvium south of Yucca Mountain, Nevada: (1) two single-well tracer tests with different rest or "shut-in" periods, (2) a cross-hole tracer test with an extended flow interruption, (3) a comparison of two tracer decay curves in an injection borehole with and without pumping of a downgradient well, and (4) a natural-gradient tracer test. Such tracer methods are potentially very useful for estimating groundwater velocities when hydraulic gradients are flat (and hence uncertain) and also when water level and hydraulic conductivity data are sparse, both of which were the case at this test location. The purpose of the study was to evaluate the first three methods for their ability to provide reasonable estimates of relatively low groundwater flow velocities in such low-hydraulic-gradient environments. The natural-gradient method is generally considered to be the most robust and direct method, so it was used to provide a "ground truth" velocity estimate. However, this method usually requires several wells, so it is often not practical in systems with large depths to groundwater and correspondingly high well installation costs. The fact that a successful natural gradient test was conducted at the test location offered a unique opportunity to compare the flow velocity estimates obtained by the more easily deployed and lower risk methods with the ground-truth natural-gradient method. The groundwater flow velocity estimates from the four methods agreed very well with each other, suggesting that the first three methods all provided reasonably good estimates of groundwater flow velocity at the site. The advantages and disadvantages of the different methods, as well as some of the uncertainties associated with them are discussed. Published by Elsevier B.V.

76 FR 71610 - Market Test of First-Class Tracer

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-18

... POSTAL REGULATORY COMMISSION [Docket No. MT2012-1; Order No. 959] Market Test of First-Class... recently-field Postal Service proposal to conduct a market test of a market dominant product, First- Class Tracer. This document describes the proposed test, addresses procedural aspects of the filing, and...

Simple Spreadsheet Models For Interpretation Of Fractured Media Tracer Tests

EPA Science Inventory

An analysis of a gas-phase partitioning tracer test conducted through fractured media is discussed within this paper. The analysis employed matching eight simple mathematical models to the experimental data to determine transport parameters. All of the models tested; two porous...

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

Rose, David Martin; Schenkman, Benjamin L.; Borneo, Daniel R.

The Department of Energy Office of Electricity (DOE/OE), Sandia National Laboratories (SNL) and the Base Camp Integration Lab (BCIL) partnered together to incorporate an energy storage system into a microgrid configured Forward Operating Base to reduce the fossil fuel consumption and to ultimately save lives. Energy storage vendors will be sending their systems to SNL Energy Storage Test Pad (ESTP) for functional testing and then to the BCIL for performance evaluation. The technologies that will be tested are electro-chemical energy storage systems comprising of lead acid, lithium-ion or zinc-bromide. GS Battery and EPC Power have developed an energy storage systemmore » that utilizes zinc-bromide flow batteries to save fuel on a military microgrid. This report contains the testing results and some limited analysis of performance of the GS Battery, EPC Power HES RESCU.« less

49 CFR 173.193 - Bromoacetone, methyl bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc.

Code of Federal Regulations, 2010 CFR

2010-10-01

... methyl bromide or methyl chloride mixtures, etc. 173.193 Section 173.193 Transportation Other Regulations... bromide, chloropicrin and methyl bromide or methyl chloride mixtures, etc. (a) Bromoacetone must be...) Bromoacetone, methyl bromide, chloropicrin and methyl bromide mixtures, chloropicrin and methyl chloride...

Revisitation of the dipole tracer test for heterogeneous porous formations

NASA Astrophysics Data System (ADS)

Zech, Alraune; D'Angelo, Claudia; Attinger, Sabine; Fiori, Aldo

2018-05-01

In this paper, a new analytical solution for interpreting dipole tests in heterogeneous media is derived by associating the shape of the tracer breakthrough curve with the log-conductivity variance. It is presented how the solution can be used for interpretation of dipole field test in view of geostatistical aquifer characterization on three illustrative examples. The analytical solution for the tracer breakthrough curve at the pumping well in a dipole tracer test is developed by considering a perfectly stratified formation. The analysis is carried out making use of the travel time of a generic solute particle, from the injection to the pumping well. Injection conditions are adapted to different possible field setting. Solutions are presented for resident and flux proportional injection mode as well as for an instantaneous pulse of solute and continuous solute injections. The analytical form of the solution allows a detailed investigation on the impact of heterogeneity, the tracer input conditions and ergodicity conditions at the well. The impact of heterogeneity manifests in a significant spreading of solute particles that increases the natural tendency to spreading induced by the dipole setup. Furthermore, with increasing heterogeneity the number of layers needed to reach ergodic conditions become larger. Thus, dipole test in highly heterogeneous aquifers might take place under non-ergodic conditions giving that the log-conductivity variance is underestimated. The method is a promising geostatistical analyzing tool being the first analytical solution for dipole tracer test analysis taking heterogeneity of hydraulic conductivity into account.

Advanced secondary recovery demonstration for the Sooner Unit. Progress report, July 1--September 30, 1995

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

Sippel, M.A.; Cammon, T.J.

1995-09-30

The objective of this project is to increase production from the Cretaceous ``D`` Sand in the Denver-Julesburg (D-J) Basin through geologically targeted infill drilling and improved reservoir management of waterflood operations. This project involves multi-disciplinary reservoir characterization using high-density 3-D seismic, detailed stratigraphy and reservoir simulation studies. Infill drilling, water-injection conversion and recompleting some wells to add short-radius laterals will be based on the results of the reservoir characterization studies. Production response will be evaluated using reservoir simulation and production tests. Technology transfer will utilize workshops, presentations and technical papers which will emphasize the economic advantages of implementing the demonstratedmore » technologies. The success of this project and effective technology transfer should prompt-re-appraisal of older waterflood projects and implementation of new projects in oil provinces such as the D-J Basin. Three wells have been drilled by the project based on 3-D seismic and integrated reservoir characterization study. Oil production has increased in September to 54.0 m{sup 3}/D (340 bopd) after the completion of the SU 21-16-9. Combination-attribute maps from 3-D seismic data closely predicted the net-pay thickness of the new well. Inter-well tracer tests with sodium bromide indicate a high-permeability channel between two wells. An oral presentation was made at the Rocky Mountain AAPG meeting in Reno, NV.« less

Preliminary Interpretation of a Radionuclide and Colloid Tracer Test in a Granodiorite Shear Zone at the Grimsel Test Site, Switzerland

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

Reimus, Paul W.

2012-08-30

In February and March 2012, a tracer test involving the injection of a radionuclide-colloid cocktail was conducted in the MI shear zone at the Grimsel Test Site, Switzerland, as part of the Colloids Formation and Migration (CFM) project. The colloids were derived from FEBEX bentonite, which is mined in Spain and is being considered as a potential waste package backfill in a Spanish nuclear waste repository. The tracer test, designated test 12-02 (second test in 2012), involved the injection of the tracer cocktail into borehole CFM 06.002i2 and extraction from the Pinkel surface packer at the main access tunnel wallmore » approximately 6.1 m from the injection interval. The test configuration is depicted in Figure 1. This configuration has been used in several conservative tracer tests and two colloid-homologue tracer tests since 2007, and it is will be employed in an upcoming test involving the emplacement of a radionuclide-doped bentonite plug into CFM 06.002i2 to evaluate the swelling and erosion of the bentonite and the transport of bentonite colloids and radionuclides from the source to the extraction point at the tunnel wall. Interpretive analyses of several of the previous tracer tests, from 09-01 through 12-02 were provided in two previous Used Fuel Disposition Program milestone reports (Arnold et al., 2011; Kersting et al., 2012). However, only the data for the conservative tracer Amino-G Acid was previously analyzed from test 12-02 because the other tracer data from this test were not available at the time. This report documents the first attempt to quantitatively analyze the radionuclide and colloid breakthrough curves from CFM test 12-02. This report was originally intended to also include an experimental assessment of colloid-facilitated transport of uranium by bentonite colloids in the Grimsel system, but this assessment was not conducted because it was reported by German collaborators at the Karlsruhe Institute of Technology (KIT) that neither uranium nor neptunium adsorbed appreciably to FEBEX bentonite colloids in Grimsel groundwater (Huber et al., 2011). The Grimsel groundwater has a relatively high pH of {approx}9, so the lack of uranium and neptunium adsorption to clay is not surprising given the tendency for these actinides to form very stable negative or neutrally-charged uranyl- or calcium-uranyl-carbonate complexes at these pH, particularly in a water that is effectively saturated with respect to calcite. It was also observed in testing conducted at LANL earlier in 2012 that uranium did not adsorb measurably to Grimsel granodiorite in a synthetic Grimsel groundwater at pH {approx}8.5 (Kersting et al., 2012). Thus, the planned experimental work was not pursued because all the available information clearly pointed to an expected result that uranium transport would not be facilitated by clay colloids in the Grimsel system.« less

A new tracer‐density criterion for heterogeneous porous media

USGS Publications Warehouse

Barth, Gilbert R.; Illangasekare, Tissa H.; Hill, Mary C.; Rajaram, Harihar

2001-01-01

Tracer experiments provide information about aquifer material properties vital for accurate site characterization. Unfortunately, density‐induced sinking can distort tracer movement, leading to an inaccurate assessment of material properties. Yet existing criteria for selecting appropriate tracer concentrations are based on analysis of homogeneous media instead of media with heterogeneities typical of field sites. This work introduces a hydraulic‐gradient correction for heterogeneous media and applies it to a criterion previously used to indicate density‐induced instabilities in homogeneous media. The modified criterion was tested using a series of two‐dimensional heterogeneous intermediate‐scale tracer experiments and data from several detailed field tracer tests. The intermediate‐scale experimental facility (10.0×1.2×0.06 m) included both homogeneous and heterogeneous (σln k2 = 1.22) zones. The field tracer tests were less heterogeneous (0.24 < σln k2 < 0.37), but measurements were sufficient to detect density‐induced sinking. Evaluation of the modified criterion using the experiments and field tests demonstrates that the new criterion appears to account for the change in density‐induced sinking due to heterogeneity. The criterion demonstrates the importance of accounting for heterogeneity to predict density‐induced sinking and differences in the onset of density‐induced sinking in two‐ and three‐dimensional systems.

Plan for radionuclide tracer studies of the residence time distribution in the Wilsonville dissolver and preheater

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

Jolley, R.L.; Begovich, J.M.; Brashear, H.R.

1983-12-01

Stimulus-response measurements using radiotracers to measure residence time distribution (RTD) and hydrodynamic parameters for the preheaters and dissolvers at the Ft. Lewis Solvent Refined Coal (SRC) and the Exxon Donor Solvent (EDS) coal conversion pilot plants are reviewed. A plan is also presented for a series of radioactive tracer studies proposed for the Advanced Coal Liquefaction Facility at Wilsonville, Alabama, to measure the RTD for the preheater and dissolvers in the SRC-I mode. The tracer for the gas phase will be /sup 133/Xe, and /sup 198/Au (on carbonized resin or as an aqueous colloidal suspension) will be used as themore » slurry tracer. Four experimental phases are recommended for the RTD tracer studies: (1) preheater; (2) dissolver with 100% takeoff; (3) dissolver with 100% takeoff and solids withdrawal; and (4) dissolver with 50% takeoff. Eighteen gas-tracer and 22 liquid-tracer injections are projected to accomplish the four experimental phases. Two to four tracer injections are projected for preliminary tests to ensure the capability of safe injection of the radiotracers and the collection of statistically significant data. A complete projected cost and time schedule is provided, including procurement of necessary components, preparation of the radiotracers, assembly and testing of tracer injection apparatus and detection systems, onsite work and tracer injections, laboratory experimentation, data analysis, and report writing.« less

Analytical solutions for efficient interpretation of single-well push-pull tracer tests

EPA Science Inventory

Single-well push-pull tracer tests have been used to characterize the extent, fate, and transport of subsurface contamination. Analytical solutions provide one alternative for interpreting test results. In this work, an exact analytical solution to two-dimensional equations descr...

Study of the antibacterial and antifungal activities of synthetic benzyl bromides, ketones, and corresponding chalcone derivatives.

PubMed

Shakhatreh, Muhamad Ali K; Al-Smadi, Mousa L; Khabour, Omar F; Shuaibu, Fatima A; Hussein, Emad I; Alzoubi, Karem H

2016-01-01

Several applications of chalcones and their derivatives encouraged researchers to increase their synthesis as an alternative for the treatment of pathogenic bacterial and fungal infections. In the present study, chalcone derivatives were synthesized through cross aldol condensation reaction between 4-( N , N -dimethylamino)benzaldehyde and multiarm aromatic ketones. The multiarm aromatic ketones were synthesized through nucleophilic substitution reaction between 4-hydroxy acetophenone and benzyl bromides. The benzyl bromides, multiarm aromatic ketones, and corresponding chalcone derivatives were evaluated for their activities against eleven clinical pathogenic Gram-positive, Gram-negative bacteria, and three pathogenic fungi by the disk diffusion method. The minimum inhibitory concentration was determined by the microbroth dilution technique. The results of the present study demonstrated that benzyl bromide derivatives have strong antibacterial and antifungal properties as compared to synthetic chalcone derivatives and ketones. Benzyl bromides (1a and 1c) showed high ester activity against Gram-positive bacteria and fungi but moderate activity against Gram-negative bacteria. Therefore, these compounds may be considered as good antibacterial and antifungal drug discovery. However, substituted ketones (2a-b) as well as chalcone derivatives (3a-c) showed no activity against all the tested strains except for ketone (2c), which showed moderate activity against Candida albicans .

Study of the antibacterial and antifungal activities of synthetic benzyl bromides, ketones, and corresponding chalcone derivatives

PubMed Central

Shakhatreh, Muhamad Ali K; Al-Smadi, Mousa L; Khabour, Omar F; Shuaibu, Fatima A; Hussein, Emad I; Alzoubi, Karem H

2016-01-01

Several applications of chalcones and their derivatives encouraged researchers to increase their synthesis as an alternative for the treatment of pathogenic bacterial and fungal infections. In the present study, chalcone derivatives were synthesized through cross aldol condensation reaction between 4-(N,N-dimethylamino)benzaldehyde and multiarm aromatic ketones. The multiarm aromatic ketones were synthesized through nucleophilic substitution reaction between 4-hydroxy acetophenone and benzyl bromides. The benzyl bromides, multiarm aromatic ketones, and corresponding chalcone derivatives were evaluated for their activities against eleven clinical pathogenic Gram-positive, Gram-negative bacteria, and three pathogenic fungi by the disk diffusion method. The minimum inhibitory concentration was determined by the microbroth dilution technique. The results of the present study demonstrated that benzyl bromide derivatives have strong antibacterial and antifungal properties as compared to synthetic chalcone derivatives and ketones. Benzyl bromides (1a and 1c) showed high ester activity against Gram-positive bacteria and fungi but moderate activity against Gram-negative bacteria. Therefore, these compounds may be considered as good antibacterial and antifungal drug discovery. However, substituted ketones (2a–b) as well as chalcone derivatives (3a–c) showed no activity against all the tested strains except for ketone (2c), which showed moderate activity against Candida albicans. PMID:27877017

Sensitivity models and design protocol for partitioning tracer tests in alluvial aquifers

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

Jin, M.; Butler, G.W.; Jackson, R.E.

1997-11-01

Zones of dense, nonaqueous phase liquids (DNAPLs) are difficult to characterize as to their volume, composition, and spatial distribution using conventional ground-water extraction and soil-sampling methods. Such incompletely characterized sites have negative consequences for those responsible for their remedial design, e.g., the uncertainties in the optimal placement of ground-water extraction wells and in the duration of remediation. However, the recent use of the partitioning interwell tracer test (PITT) to characterize DNAPL zones at sites in New Mexico [unsaturated alluvium] and in Ohio, Texas, and Utah [saturated alluvium] demonstrates that the volume and spatial distribution of residual DNAPL can be determinedmore » with accuracy. The PITT involves injection of a suite of tracers which reversibly partition to different degrees between the DNAPL and the ground water or soil air resulting in the chromatographic separation of the tracer signals observed at the extraction well(s). The design of a PITT requires careful consideration of the hydrostratigraphic, hydraulic, and certain geochemical properties of the alluvium being tested. A three-dimensional, numerical model of a heterogeneous alluvial aquifer containing DNAPL has been developed for use with the UTCHEM simulator to demonstrate partitioning tracer testing and to address questions that are frequently raised in its application. The simulations include (1) the estimation of DNAPL volume for the simple case where only residual DNAPL is present in heterogeneous alluvium, (2) sensitivity studies to demonstrate the effect of increasingly low residual DNAPL saturation on the tracer signal, and (3) the effect of free-phase DNAPL on the estimation of the volume of DNAPL present. Furthermore, the potential interference of sedimentary organic carbon as a DNAPL surrogate on the tracer signal is considered and shown to be readily resolved by the careful choice of tracers.« less

Transport of sulfonamide antibiotics in small fields during monsoon season

NASA Astrophysics Data System (ADS)

Park, J. Y.; Huwe, B.; Kolb, A.; Tenhunen, J.

2012-04-01

Transport and fate of 3 sulfonamide antibiotics (sulfamethoxazole, sulfadimethoxine and sulfamethazine) were studied in small agricultural land during monsoon period. The experiment has been conducted in 2 typical sandy loam potato fields of South Korea after application of the veterinary antibiotics and bromide. Precipitation was measured by AWS (Automatic Weather Station) near the fields during the whole monsoon season. Runoff generation was estimated by multislot divisors in combination with pressure sensor. Concentration of the target antibiotics and the conservative tracer in runoff, soil-water and soil was determined using HPLC-MS-MS and Br selected electrode. Transport simulation has been performed with Hydrus-2D program which can consider soil characteristics, climate condition, adsorption/desorption and degradation. Results from the measurements and modeling focus on the role of heavy rainfall, of related the ratio of runoff and infiltration in terms of the selected antibiotics distribution and fate. Bromide on topsoil was moved into soil as increasing rainfall loading. On the contrary, the sulfonamides were relatively retarded in upper soil layer owing to adsorption onto soil particles. Different patterns of runoff were observed, and slope and rain intensity was representative factor in this study. Distribution of target pharmaceuticals was strongly dependent on constitution of furrow and ridge in the agricultural fields. Modeling results positively matched with background studies that describe physico-chemical properties of the sulfonamides, interaction between soil and the antibiotic group, solute transport through vadose zone and runoff induction by storm events.

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

NASA Astrophysics Data System (ADS)

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

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

Identification and characterization of conservative organic tracers for use as hydrologic tracers for the Yucca Mountain Site characterization study; Progress report, April 1, 1993--June 30, 1993

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

Dombrowski, T.; Stetzenbach, K.

1993-08-01

This report is in two parts one for the fluorinated benzoic acids and one for the fluorinated aliphatic acids. The assumptions made in the report regarding the amount of tracer that will be used, dilution of the tracer during the test and the length of exposure (if any) to individuals drinking the water were made by the authors. These assumptions must really come from the USGS hydrologists in charge of the c-well tracer testing program. Accurate estimates of dilution of the tracer during the test are also important because of solubility limitations of some of the tracers. Three of themore » difluorobenzoic acids have relatively low solubilities and may not be usable if the dilution estimates are large. The toxicologist that reviewed the document agreed with our conclusion that the fluorinated benzoic and toluic acids do not represent a health hazard if used under the conditions as outlined in the report. We are currently testing 15 of these compounds, and if even if three difluorobenzoic acids cannot be used because of solubility limitations we will still have 12 tracers. The toxicologist felt that the aliphatic fluorinated acids potentially present more of a health risk than the aromatic. This assessment was based on the fact of a known allergic response to halothane anesthetic. This risk, although minimal, is known and he felt that was enough reason to recommend against their use. The authors feel that the toxicologists interpretation of this risk was overly conservative, however, we will not go against his recommendation at this time for the following reasons. First, without the aliphatic compounds we still have 12 to 15 fluorinated aromatic acids which, should be enough for the c-well tests. Second, to get a permit to use aliphatic compounds would undoubtedly require a hearing which could be quite lengthy.« less

Delineation of Groundwater Flow Pathway in Fractured Bedrock Using Nano-Iron Tracer Test in the Sealed Well

NASA Astrophysics Data System (ADS)

Chuang, Po-Yu; Chia, Yeeping; Chiu, Yung-Chia; Liou, Ya-Hsuan; Teng, Mao-Hua; Liu, Ching-Yi; Lee, Tsai-Ping

2016-04-01

Deterministic delineation of the preferential flow paths and their hydraulic properties are desirable for developing hydrogeological conceptual models in bedrock aquifers. In this study, we proposed using nanoscale zero-valent iron (nZVI) as a tracer to characterize the fractured connectivity and hydraulic properties. Since nZVI particles are magnetic, we designed a magnet array to attract the arriving nZVI particles in the observation well for identifying the location of incoming tracer. This novel approach was examined at two experiment wells with well hydraulic connectivity in a hydrogeological research station in the fractured aquifer. Heat-pulse flowmeter test was used to detect the vertical distribution of permeable zones in the borehole, providing the design basis of tracer test. Then, the less permeable zones in the injection well were sealed by casing to prevent the injected nZVI particles from being stagnated at the bottom hole. Afterwards, hydraulic test was implemented to examine the hydraulic connectivity between two wells. When nZVI slurry was released in the injection well, they could migrate through connected permeable fractures to the observation well. A breakthrough curve was obtained by the fluid conductivity sensor in the observation well, indicating the arrival of nZVI slurry. The iron nanoparticles that were attracted to the magnets in the observation well provide the quantitative information to locate the position of tracer inlet, which corroborates well with the depth of a permeable zone delineated by the flowmeter. Finally, the numerical method was utilized to simulate the process of tracer migration. This article demonstrates that nano-iron tracer test can be a promising approach for characterizing connectivity patterns and transmissivities of the flow paths in the fractured rock.

Application of nanoscale zero-valent iron tracer to delineate groundwater flow paths between a screened well and an open well in fractured rock

NASA Astrophysics Data System (ADS)

Chuang, P. Y.; Chiu, Y.; Liou, Y. H.; Teng, M. H.; Chia, Y.

2016-12-01

Fracture flow is of importance for water resources as well as the investigation of contaminant pathways. In this study, a novel characterization approach of nanoscale zero-valent iron (nZVI) tracer test was developed to accurately identify the connecting fracture zones of preferential flow between a screened well and an open well. Iron nanoparticles are magnetic and can be attracted by a magnet. This feature make it possible to design a magnet array for attracting nZVI particles at the tracer inlet to characterize the location of incoming tracer in the observation well. This novel approach was tested at two experiment wells with well hydraulic connectivity in a hydrogeological research station in central Taiwan. A heat-pulse flowmeter can be used to detect changes in flow velocity for delineating permeable fracture zones in the borehole and providing the design basis for the tracer test. Then, the most permeable zone in the injection well was hydraulically isolated by well screen to prevent the injected nZVI particles from being stagnated at the hole bottom. Afterwards, another hydraulic test was implemented to re-examine the hydraulic connectivity between the two wells. When nZVI slurry was injected in the injection well, they migrated through connected permeable fractures to the observation well. A breakthrough curve, observed by the fluid conductivity sensor in the observation well, indicated the arrival of nZVI slurry. The iron nanoparticles attracted to the magnets in the observation well provide the position of tracer inlet, which corroborates well with the depth of a permeable zone delineated by the flowmeter. This article demonstrates the potential of nano-iron tracer test to provide the quantitative information of fracture flow paths in fractured rock.

Transport Studies at the Vadose Zone Research Park, Idaho National Engineering and Environmental Laboratory: Results of Initial Tests

NASA Astrophysics Data System (ADS)

Roback, R. C.; Jones, C. L.; Hull, L. C.; McLing, T. L.; Baker, K. E.; Abdel-Fattah, A. I.; Adams, J. D.; Nichols, E. M.

2003-12-01

The Vadose Zone Research Park (VZRP) provides a unique opportunity to investigate flow and transport in a thick, fractured and layered vadose zone. The VZRP includes two newly constructed percolation ponds each approximately 160000 square ft in area, which receive roughly 1.0 to 1.5 million gallons/day of uncontaminated process water. Monitoring wells and instrumented boreholes surround the percolation ponds. These are distributed in nested sets that allow continuous monitoring and sample collection along two important hydrologic contacts; one located at roughly 60' bls along a contact between alluvium and basalt and the other at 125' bls, along a sedimentary interbed in basalt. Both of these contacts support perched water zones. Hydraulic data have been collected nearly continuously since the first use of the percolation ponds in August 2002. Samples for geochemical studies were also collected during the first few weeks of discharge to the south pond to observe geochemical trends during initial wetting of the subsurface. During the summer of 2003, two tracer tests were performed. The first test consisted of injecting a conservative tracer (2,4,5-trifluorobenzoic acid) into the south pond, which had been receiving water for almost 10 months prior and for which hydraulic data indicated a steady state hydraulic system. The second tracer test was conducted in the north pond and consisted of simultaneous injection of two conservative tracers with different diffusion coefficients (2,4-difluorobenzoic acid, and Br- ion). Tracer injection coincided with the switching of water from the south to the north pond, which had been dry for 10 months prior. Thus, this test afforded us the opportunity to evaluate transport behavior in a relatively dry vadose zone, and to compare this to observed transport behavior under the earlier steady state, more saturated flow condition. Results from the first tracer test show tracer breakthrough in a shallow well, close to the south pond within approximately 30 hours with the peak at approximately 70 hours. In an adjacent, though deeper well located in a perched water zone at the 125' interbed, two tracer peaks were observed, one at approximately 50 hours and the other at approximately 200 hours, indicating multiple flow pathways and different travel times. Flow velocities calculated from this test are on the order of 100 m/day, in good agreement with velocities determined through hydraulic data. Initial results from the second tracer test show tracer recovery in at least four of the sampled wells. During this test, the discharge and four wells were also sampled for colloid concentration and particle size distribution. Colloid concentrations in the wells are roughly equivalent to, or larger than, those from the discharge and show sharp peaks up to an order of magnitude above background values. Comparison of colloid concentration data from the discharge, shallow wells located in the alluvium, and deeper wells in fractured basalt suggest that colloids are liberated in the alluvium and that advection through the fractured basalt does not affect the stability of the colloids. Preliminary tracer data show that tracer breakthrough in the monitoring wells occurred at similar times to colloid peaks. Further analytical work will yield breakthrough curves for the 2,4-tFBA that will be quantitatively compared with the colloid peaks.

Modification of Rhodamine WT tracer tests procedure in activated sludge reactors

NASA Astrophysics Data System (ADS)

Knap, Marta; Balbierz, Piotr

2017-11-01

One of the tracers recommended for use in wastewater treatment plants and natural waters is Rhodamine WT, which is a fluorescent dye, allowing to work at low concentrations, but may be susceptible to sorption to activated sludge flocs and chemical quenching of fluorescence by dissolved water constituents. Additionally raw sewage may contain other natural materials or pollutants exhibiting limited fluorescent properties, which are responsible for background fluorescence interference. This paper presents the proposed modifications to the Rhodamine WT tracer tests procedure in activated sludge reactors, which allow to reduce problems with background fluorescence and tracer loss over time, developed on the basis of conducted laboratory and field experiments.

Using the tracer-dilution discharge method to develop streamflow records for ice-affected streams in Colorado

USGS Publications Warehouse

Capesius, Joseph P.; Sullivan, Joseph R.; O'Neill, Gregory B.; Williams, Cory A.

2005-01-01

Accurate ice-affected streamflow records are difficult to obtain for several reasons, which makes the management of instream-flow water rights in the wintertime a challenging endeavor. This report documents a method to improve ice-affected streamflow records for two gaging stations in Colorado. In January and February 2002, the U.S. Geological Survey, in cooperation with the Colorado Water Conservation Board, conducted an experiment using a sodium chloride tracer to measure streamflow under ice cover by the tracer-dilution discharge method. The purpose of this study was to determine the feasibility of obtaining accurate ice-affected streamflow records by using a sodium chloride tracer that was injected into the stream. The tracer was injected at two gaging stations once per day for approximately 20 minutes for 25 days. Multiple-parameter water-quality sensors at the two gaging stations monitored background and peak chloride concentrations. These data were used to determine discharge at each site. A comparison of the current-meter streamflow record to the tracer-dilution streamflow record shows different levels of accuracy and precision of the tracer-dilution streamflow record at the two sites. At the lower elevation and warmer site, Brandon Ditch near Whitewater, the tracer-dilution method overestimated flow by an average of 14 percent, but this average is strongly biased by outliers. At the higher elevation and colder site, Keystone Gulch near Dillon, the tracer-dilution method experienced problems with the tracer solution partially freezing in the injection line. The partial freezing of the tracer contributed to the tracer-dilution method underestimating flow by 52 percent at Keystone Gulch. In addition, a tracer-pump-reliability test was conducted to test how accurately the tracer pumps can discharge the tracer solution in conditions similar to those used at the gaging stations. Although the pumps were reliable and consistent throughout the 25-day study period, the pumps underdischarged the tracer by 5.8-15.9 percent as compared to the initial pumping rate setting, which may explain some of the error in the tracer-dilution streamflow record as compared to current-meter streamflow record.

76 FR 71087 - Market Test of Experimental Product: “First-Class Tracer”

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-16

... POSTAL SERVICE Market Test of Experimental Product: ``First-Class Tracer'' AGENCY: Postal Service \\TM\\. ACTION: Notice. SUMMARY: The Postal Service gives notice of a market test of an experimental... ``First-Class Tracer'' experimental product on or after December 7, 2011. The Postal Service has filed...

Applying tracer techniques to determine recharge rate, groundwater age and travel times in Permo-Triassic sandstones.

NASA Astrophysics Data System (ADS)

Butcher, Andrew; Gallagher, Alexander; Darling, W. George; Gooddy, Daren; Burke, Sean

2010-05-01

The Eden Valley in East Cumbria is underlain by Permo-Triassic sandstone, the major aquifer in Northwest England. Rising nitrate trends in some boreholes has prompted collaborative research into flow systems and timescales in the area. The use of slurry and artificial fertilisers following agricultural intensification during the 1980s is believed to be responsible for the rise in nitrate concentrations. The broad aim of this research is to enable prediction of future nitrate concentrations at abstraction boreholes and in groundwater discharge to surface water. The approach taken has been to study groundwater processes along a 4km transect (approximating a groundwater flowline) in order to estimate groundwater travel timescales through the sandstone and thin superficial Till . A combination of porewater sampling during borehole coring, discrete interval sampling using a borehole packer system, geophysical logging and imaging were employed to develop physical and hydrochemical profiles. Separate tracer techniques were used to estimate recharge rates at different parts of the transect. Tracers used were: deuterium and bromide through Till, nitrate, chloride and tritium through the unsaturated zone and CFCs and SF6 within the saturated zone. Tracer profiles in Till demonstrated a correspondence between Till thickness, type of cultivation and recharge rate. In the thick unsaturated zone of the sandstone they suggested relatively rapid groundwater recharge rates. Key fractures or fracture zones in the saturated sandstone were identified and sampled. The hydrochemistry (particularly nitrate) of samples from discrete intervals in the profiles exhibited a remarkably good relationship with the proportion of modern water (and year of recharge) for example, the age of groundwater increasing to c. 1950 towards the bottom of a 90m borehole. This work demonstrates that the combination of discrete sampling and dating of groundwater is a powerful tool in characterising groundwater movement and timescales in boreholes and hence in parts of aquifers where pollution is most significant. With timescales and processes better constrained, a more reliable prediction of nitrate (and other) trends can be made.

Hydrogeomorphology of the hyporheic zone: stream solute and fine particle interactions with a dynamic streambed

USGS Publications Warehouse

Harvey, J.W.; Drummond, J.D.; Martin, R.L.; McPhillips, L.E.; Packman, A.I.; Jerolmack, D.J.; Stonedahl, S.H.; Aubeneau, A.F.; Sawyer, A.H.; Larsen, L.G.; Tobias, C.R.

2012-01-01

Hyporheic flow in streams has typically been studied separately from geomorphic processes. We investigated interactions between bed mobility and dynamic hyporheic storage of solutes and fine particles in a sand-bed stream before, during, and after a flood. A conservatively transported solute tracer (bromide) and a fine particles tracer (5 μm latex particles), a surrogate for fine particulate organic matter, were co-injected during base flow. The tracers were differentially stored, with fine particles penetrating more shallowly in hyporheic flow and retained more efficiently due to the high rate of particle filtration in bed sediment compared to solute. Tracer injections lasted 3.5 h after which we released a small flood from an upstream dam one hour later. Due to shallower storage in the bed, fine particles were rapidly entrained during the rising limb of the flood hydrograph. Rather than being flushed by the flood, we observed that solutes were stored longer due to expansion of hyporheic flow paths beneath the temporarily enlarged bedforms. Three important timescales determined the fate of solutes and fine particles: (1) flood duration, (2) relaxation time of flood-enlarged bedforms back to base flow dimensions, and (3) resulting adjustments and lag times of hyporheic flow. Recurrent transitions between these timescales explain why we observed a peak accumulation of natural particulate organic matter between 2 and 4 cm deep in the bed, i.e., below the scour layer of mobile bedforms but above the maximum depth of particle filtration in hyporheic flow paths. Thus, physical interactions between bed mobility and hyporheic transport influence how organic matter is stored in the bed and how long it is retained, which affects decomposition rate and metabolism of this southeastern Coastal Plain stream. In summary we found that dynamic interactions between hyporheic flow, bed mobility, and flow variation had strong but differential influences on base flow retention and flood mobilization of solutes and fine particulates. These hydrogeomorphic relationships have implications for microbial respiration of organic matter, carbon and nutrient cycling, and fate of contaminants in streams.

Rapid breakthrough of pesticides via biopres into tile drains and shallow groundwater: a combined experimental and model study

NASA Astrophysics Data System (ADS)

Klaus, J.; Zehe, E.; Palm, J.; Schroeder, B.

2009-04-01

Preferential flow in macropores is a key process which strongly affects infiltration and may cause rapid transport of pesticides into depths of 80 to 150 cm. At these depths they experience a much slower degradation, may leach into shallow groundwater or enter a tile-drain and are transported in surface water bodies. Therefore, preferential transport is an environ¬mental problem because the topsoil is bypassed, which has been originally thought to act as a filter to protect the subsoil and shallow groundwater. To get a better insight in the process of pesticide transport in agricultural soils an irrigation experiment was performed on a 400 m² field site. The experimental plot is located in the Weiherbach valley, south-west Germany, which basic geology consists of Loess and Keuper layers, the soil at the test site is a gleyic Colluvisol. The distance of the irrigation site to the Weiherbach brook is aprox. 12 m, the field is drained with a tile-drain in about 1.2 m depth and the shows runoff over the entire year. Three hours before the irrigation started the farmer applied a pesticide solution consisting of Isoproturon and Flufenacet according to conventional agricultural practice. The irrigation took place in three time blocks (80 min, 60 min, 80 min) and had a total irrigation rate of 33.6 mm measured with ten precipitation samplers. During the first block a tracer solution of 1600 g Bromide and 2000 g Brilliant Blue was irrigated on the test site. The drainage outlet was instrumented with a pressure probe to measure the water level. About 50 water samples were taken on the day of the experiment from the drainage outlet by hand, and in an eight hour interval for six days with an automatic sample procedure. Discharge at the drainage outlet showed two peaks in response irrigation. The breakthrough of the tracer into the brook is much faster then the reaction of the discharge on the precipitation impulse. To gain insight in the vertical transport behaviour three vertical soil profiles were excavated on the first day after the irrigation and two vertical profiles were excavated one week after the experiment. In those profiles soil samples were taken in a 10cm*10cm grid to analyse for the tracer concentrations. Based on that information the probability distribution function of the travel depths for each tracer could be calculated for two points in time. As burrows of deep digging earth worms often act as preferential pathways we counted the individuals of worm burrows using a nested sampling procedure. Though endogeic earthworms were apparent we didn't find any individuals of Lumbricus Terrestris nor macropores with diameter larger than 2 mm at a depth larger than 30-35 cm. So far we didn't identify those pathways that caused this rapid pesticide breakthrough into the tile drain, though a very small number macropores would suffice. Based on the collected data we will setup up a numerical model to simulate observed and flow and transport and test the hypothesis that earthworm burrows are the reason for this rapid breakthrough of pesticides into the tile drain.

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 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.

In situ monitoring of tracer tests: how to distinguish tracer recovery from natural background

NASA Astrophysics Data System (ADS)

Bailly-Comte, V.; Durepaire, X.; Batiot-Guilhe, C.; Schnegg, P.-A.

2018-03-01

Hydrogeological tracer tests are primarily conducted with fluorescent tracers. Field fluorometers make it possible to monitor tracers at very low concentrations (<1 ppb) and at high frequency. However, changes in natural fluorescence at a site resulting from variations of dissolved and suspended inorganic and organic material may compromise the measurement of useful signals, thereby limiting the chances of identifying or quantifying the real tracer recovery. An elevated natural signal can mask small concentrations of the tracer while its variability can give the impression of a false recovery. This article shows how the use of a combination of several continuous measurements at different wavelengths allows a better extraction of the natural signal. Field multispectral fluorometers were installed at two Mediterranean karst outlets; both drain carbonate systems but have different environmental conditions. The fluorometers functioned over several hydrologic cycles, in periods affected or not by artificial tracers, making it possible to observe natural signal variations at these sites. The optical properties of this type of field fluorometer were used to calculate the spectral response of the different optics of the measuring probe. These responses, superimposed on three-dimensional excitation/emission matrices produced from laboratory fluorescence measurements, allowed an understanding of what the fluorometer sees under natural flow conditions. The result is an innovative method for correcting artificial tracer results. This type of correction makes it possible to fine-tune the effect of natural background variation on tracer recovery curves for a clear identification of the tracer presence and a more precise quantification of its recovery.

EGS in sedimentary basins: sensitivity of early-flowback tracer signals to induced-fracture parameters

NASA Astrophysics Data System (ADS)

Karmakar, Shyamal; Ghergut, Julia; Sauter, Martin

2015-04-01

Artificial-fracture design, and fracture characterization during or following stimulation treatment is a central aspect of many EGS ('enhanced' or 'engineered' geothermal system) projects. During the creation or stimulation of an EGS, the injection of fluids, followed by flowback and production stages offers the opportunity for conducting various tracer tests in a single-well (SW) configuration, and given the typical operational and time limitations associated with such tests, along with the need to assess treatment success in real time, investigators mostly favour using short-time tracer-test data, rather than awaiting long-term 'tailings' of tracer signals. Late-time tracer signals from SW injection-flowback and production tests have mainly been used for the purpose of multiple-fracture inflow profiling in multi-layer reservoirs [1]. However, the potential of using SW short-term tracer signals for fracture characterization [2, 3] remained little explored as yet. Dealing with short-term flowback signals, we face a certain degree of parameter interplay, leading to ambiguity in fracture parameter inversion from the measured signal of a single tracer. This ambiguity can, to a certain extent, be overcome by - combining different sources of information (lithostratigraphy, and hydraulic monitoring) in order to constrain the variation range of hydrogeologic parameters (matrix and fracture permeability and porosity, fracture size), - using different types of tracers, such as conservative tracer pairs with contrasting diffusivity, or tracers pairs with contrasting sorptivity onto target surfaces. Fracture height is likely to be constrained by lithostratigraphy, while fracture length is supposed to be determinable from hydraulic monitoring (pressure recordings); the flowback rate can be assumed as a known (measurable) quantity during individual-fracture flowback. This leaves us with one or two unknown parameters to be determined from tracer signals: - the transport-effective aperture, in a water fracture (WF), or - fracture thickness and porosity, for a gel-proppant fracture (GPF). We find that parameter determination from SW early signals can significantly be improved by concomitantly using a number of solute tracers with different transport and retardation behaviour. We considered tracers of different sorptivity to proppant coatings, and to matrix rock surfaces, for GPF, as well as contrasting-diffusivity or -sorptivity tracers, for WF. An advantage of this SW approach is that it requires only small chaser volumes (few times the fracture volume), not relying on advective penetration into the rock matrix. Thus, selected tracer species are to be injected during the very last stage of the fracturing process, when fracture sizes and thus target parameters are supposed to attain more or less stable values. We illustrate the application of these tracer test design principles using hydro- and lithostratigraphy data from the Geothermal Research Platform at Groß Schönebeck [4], targeting a multi-layer reservoir (sedimentary and crystalline formations in 4-5 km depth) in the NE-German Sedimentary Basin. Acknowledgments: This work benefited from long-term support from Baker Hughes (Celle) and from the Lower-Saxonian Science and Culture Ministry (MWK Niedersachsen) within the applied research project gebo (Geothermal Energy and High-Performance Drilling, 2009-2014). The first author gratefully acknowledges continued financial support from the DAAD (German Academic Exchange Service) to pursuing Ph. D. work. References: [1] http://www.sciencedirect.com/science/article/pii/S1876610214017391 [2] http://www.geothermal-energy.org/cpdb/record_detail.php?id=7215 [3] http://www.geothermal-energy.org/cpdb/record_detail.php?id=19034 [4] http://www.gfz-potsdam.de/en/scientific-services/laboratories/gross-schoenebeck/

Feasibility of Rapid Multitracer PET Tumor Imaging

NASA Astrophysics Data System (ADS)

Kadrmas, D. J.; Rust, T. C.

2005-10-01

Positron emission tomography (PET) can characterize different aspects of tumor physiology using various tracers. PET scans are usually performed using only one tracer since there is no explicit signal for distinguishing multiple tracers. We tested the feasibility of rapidly imaging multiple PET tracers using dynamic imaging techniques, where the signals from each tracer are separated based upon differences in tracer half-life, kinetics, and distribution. Time-activity curve populations for FDG, acetate, ATSM, and PTSM were simulated using appropriate compartment models, and noisy dual-tracer curves were computed by shifting and adding the single-tracer curves. Single-tracer components were then estimated from dual-tracer data using two methods: principal component analysis (PCA)-based fits of single-tracer components to multitracer data, and parallel multitracer compartment models estimating single-tracer rate parameters from multitracer time-activity curves. The PCA analysis found that there is information content present for separating multitracer data, and that tracer separability depends upon tracer kinetics, injection order and timing. Multitracer compartment modeling recovered rate parameters for individual tracers with good accuracy but somewhat higher statistical uncertainty than single-tracer results when the injection delay was >10 min. These approaches to processing rapid multitracer PET data may potentially provide a new tool for characterizing multiple aspects of tumor physiology in vivo.

Addition of tracers into the polypropylene in view of automatic sorting of plastic wastes using X-ray fluorescence spectrometry.

PubMed

Bezati, F; Froelich, D; Massardier, V; Maris, E

2010-04-01

This study focused on the detection of rare earth oxides, used as tracers for the identification of polymer materials, using XRF (X-ray fluorescence) spectrometry. The tests were carried out in a test system device which allows the collection of static measurements of the samples' spectrum through the use of energy dispersive X-ray fluorescence technology. A sorting process based on tracers added into the polymer matrix is proposed in order to increase sorting selectivity of polypropylene during end-of-life recycling. Tracers consist of systems formed by one or by several substances dispersed into a material, to add a selective property to it, with the aim of improving the efficiency of sorting and high speed identification. Several samples containing rare earth oxides (Y(2)O(3), CeO(2), Nd(2)O(3), Gd(2)O(3), Dy(2)O(3), Er(2)O(3) and Yb(2)O(3)) in different concentrations were prepared in order to analyse some of the parameters which can influence the detection, such as the concentration of tracers, the acquisition time and the possible overlapping among the tracers. This work shows that by using the XRF test system device, it was possible to detect 5 of the 7 tracers tested for 1min exposure time and at a concentration level of 1000ppm. These two parameters will play an important role in the development of an industrial device, which indicates the necessity of further works that needs to be conducted in order to reduce them. Copyright 2009 Elsevier Ltd. All rights reserved.

Dual-porosity analysis of conservative tracer testing in saturated volcanic rocks at Yucca Mountain in Nye County, Nevada

USGS Publications Warehouse

Fahy, M.F.

1997-01-01

A radially convergent conservative tracer injection test was conducted between boreholes UE-25 #2 and UE-25 c #3 of the C-hole complex at Yucca Mountain to determine effective porosity and longitudinal dispersivity. Approximately 47% of the tracer mass was recovered and a dual-porosity analytical model replicates the breakthrough curve. Fractured-rock analyses focus on the fracture-porosity and geometry as the controlling factors in transport.

Test of synthetic DNA tracers in a periodic hydrodynamic system for time-variable transit time distribution assessment

NASA Astrophysics Data System (ADS)

Dahlke, H. E.; Wang, C.; McNew, C.; McLaughlin, S.; Lyon, S. W.

2016-12-01

Recent research on time-varying transport through hydrologic systems proposed using decomposed over-printed tracer breakthrough curves to directly observe transport through complex flow systems. This method, also known as the PERTH (Periodic Tracer Hierarchy) method requires periodic flow and multiple tracer injections to reveal changes in flow pathways and transport behavior. Time-variable transit time distributions (TTD) estimated from tracer breakthrough curves often vary with the storage state of the system, which in turn is influenced by internal and external variabilities, such as the arrangement of flow pathways and fluctuations in system inputs. Deciphering internal from external variabilities in TTDs might help to advance the use of TTDs for estimating the physical state of a system; however, thus far the finite number of unique conservative tracers available for tracing has limited deeper insights. Synthetic DNA tracers consisting of short strands of synthetic DNA encapsulated by polylactic acid (PLA) microspheres could potentially provide multiple unique tracers with identical transport properties needed to explore time varying transport through hydrologic systems in more detail. An experiment was conducted on the miniLeo hillslope, a 1 m3 sloping lysimeter, within the Biosphere 2 Landscape Evolution Observatory near Tucson, AZ to investigate transit time variability. The goal of the experiment was to 1) test the suitability of using synthetic DNA tracers for estimating TTDs in a hydrologic system and 2) to determine the TTDs of individual tracer pulses under periodic steady-state conditions. Five DNA tracers, consisting of four unique, encapsulated DNA sequences and one free/non-encapsulated DNA sequence, were applied as reference and probe tracers together with deuterium, using the PERTH method. The lysimeter received three 2-hour pulses of rainfall at a rate of 30 mm/hr for 10 days. Initial results show that both the encapsulated and free DNA tracers were successfully transported in a pulsed manner through the system, but had overall longer breakthrough times than the reference deuterium tracer. Comparison of the DNA probe tracers indicate differences in transit times, likely related to differences in tracer mobilization in response to the time-variant rainfall input.

Biodegradation of imidazolium ionic liquids by activated sludge microorganisms.

PubMed

Liwarska-Bizukojc, Ewa; Maton, Cedric; Stevens, Christian V

2015-11-01

Biological properties of ionic liquids (ILs) have been usually tested with the help of standard biodegradation or ecotoxicity tests. So far, several articles on the identification of intermediate metabolites of microbiological decay of ILs have been published. Simultaneously, the number of novel ILs with unrecognized characteristics regarding biodegradability and effect on organisms and environment is still increasing. In this work, seven imidazolium ionic liquids of different chemical structure were studied. Three of them are 1-alkyl-3-methyl-imidazolium bromides, while the other four are tetra- or completely substituted imidazolium iodides. This study focused on the identification of intermediate metabolites of the aforementioned ionic liquids subjected to biodegradation in a laboratory activated sludge system. Both fully substituted ionic liquids and 1-ethyl-3-methyl-imidazolium bromide were barely biodegradable. In the case of two of them, no biotransformation products were detected. The elongation of the alkyl side chain made the IL more susceptible for microbiological decomposition. 1-Decyl-3-methyl-imidazolium bromide was biotransformed most easily. Its primary biodegradation up to 100 % could be achieved. Nevertheless, the cleavage of the imidazolium ring has not been observed.

PARTITIONING TRACERS FOR MEASURING RESIDUAL NAPL: FIELD-SCALE TEST RESULTS

EPA Science Inventory

The difficult task of locating and quantifying nonaqueous phase liquids (NAPLs) present in the vadose and saturated zones has prompted the development of innovative, nondestructive characterization techniques. The use of the interwell partitioning tracer's (IWPT) test, in which ...

Evaluation of multiple tracer methods to estimate low groundwater flow velocities

DOE PAGES

Reimus, Paul W.; Arnold, Bill W.

2017-02-20

Here, four different tracer methods were used to estimate groundwater flow velocity at a multiple-well site in the saturated alluvium south of Yucca Mountain, Nevada: (1) two single-well tracer tests with different rest or “shut-in” periods, (2) a cross-hole tracer test with an extended flow interruption, (3) a comparison of two tracer decay curves in an injection borehole with and without pumping of a downgradient well, and (4) a natural-gradient tracer test. Such tracer methods are potentially very useful for estimating groundwater velocities when hydraulic gradients are flat (and hence uncertain) and also when water level and hydraulic conductivity datamore » are sparse, both of which were the case at this test location. The purpose of the study was to evaluate the first three methods for their ability to provide reasonable estimates of relatively low groundwater flow velocities in such low-hydraulic-gradient environments. The natural-gradient method is generally considered to be the most robust and direct method, so it was used to provide a “ground truth” velocity estimate. However, this method usually requires several wells, so it is often not practical in systems with large depths to groundwater and correspondingly high well installation costs. The fact that a successful natural gradient test was conducted at the test location offered a unique opportunity to compare the flow velocity estimates obtained by the more easily deployed and lower risk methods with the ground-truth natural-gradient method. The groundwater flow velocity estimates from the four methods agreed very well with each other, suggesting that the first three methods all provided reasonably good estimates of groundwater flow velocity at the site. We discuss the advantages and disadvantages of the different methods, as well as some of the uncertainties associated with them.« less

Evaluation of multiple tracer methods to estimate low groundwater flow velocities

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

Reimus, Paul W.; Arnold, Bill W.

Here, four different tracer methods were used to estimate groundwater flow velocity at a multiple-well site in the saturated alluvium south of Yucca Mountain, Nevada: (1) two single-well tracer tests with different rest or “shut-in” periods, (2) a cross-hole tracer test with an extended flow interruption, (3) a comparison of two tracer decay curves in an injection borehole with and without pumping of a downgradient well, and (4) a natural-gradient tracer test. Such tracer methods are potentially very useful for estimating groundwater velocities when hydraulic gradients are flat (and hence uncertain) and also when water level and hydraulic conductivity datamore » are sparse, both of which were the case at this test location. The purpose of the study was to evaluate the first three methods for their ability to provide reasonable estimates of relatively low groundwater flow velocities in such low-hydraulic-gradient environments. The natural-gradient method is generally considered to be the most robust and direct method, so it was used to provide a “ground truth” velocity estimate. However, this method usually requires several wells, so it is often not practical in systems with large depths to groundwater and correspondingly high well installation costs. The fact that a successful natural gradient test was conducted at the test location offered a unique opportunity to compare the flow velocity estimates obtained by the more easily deployed and lower risk methods with the ground-truth natural-gradient method. The groundwater flow velocity estimates from the four methods agreed very well with each other, suggesting that the first three methods all provided reasonably good estimates of groundwater flow velocity at the site. We discuss the advantages and disadvantages of the different methods, as well as some of the uncertainties associated with them.« less

Abschätzung des Einflusses von Parameterunsicherheiten bei der Planung und Auswertung von Tracertests unter Verwendung von Ensembleprognosen

NASA Astrophysics Data System (ADS)

Klotzsch, Stephan; Binder, Martin; Händel, Falk

2017-06-01

While planning tracer tests, uncertainties in geohydraulic parameters should be considered as an important factor. Neglecting these uncertainties can lead to missing the tracer breakthrough, for example. One way to consider uncertainties during tracer test design is the so called ensemble forecast. The applicability of this method to geohydrological problems is demonstrated by coupling the method with two analytical solute transport models. The algorithm presented in this article is suitable for prediction as well as parameter estimation. The parameter estimation function can be used in a tracer test for reducing the uncertainties in the measured data which can improve the initial prediction. The algorithm was implemented into a software tool which is freely downloadable from the website of the Institute for Groundwater Management at TU Dresden, Germany.

PARTITIONING INTERWELL TRACER TEST FOR NAPL SOURCE CHARACTERIZATION: A GENERAL OVERVIEW

EPA Science Inventory

Innovative and nondestructive characterization techniques have been developed to locate and quantify nonaqueous phase liquids (NAPLs) in the vadose and saturated zones in the subsurface environment. One such technique is the partitioning interwell tracer test (PITT). The PITT i...

A line source tracer test - a better method for assessing high groundwater velocity

NASA Astrophysics Data System (ADS)

Magal, E.; Weisbrod, N.; Yakirevich, A.; Kurtzman, D.; Yechieli, Y.

2009-12-01

A line source injection is suggested as an effective method for assessing groundwater velocities and flow directions in subsurface characterized by high water fluxes. Modifying the common techniques of injecting a tracer into a well was necessary after frequently-used methods of natural and forced gradient tracer tests ended with no reliable information on the local groundwater flow. In a field experiment, tracers were injected into 8-m long line injection system constructed below the water table almost perpendicular to the assumed flow direction. The injection system was divided to four separate segments (each 2 m long) enabling the injection of four different tracers along the line source. An array of five boreholes located in an area of 10x10 m downstream was used for monitoring the tracers' transport. Two dye tracers (Uranine and Na Naphthionate) were injected in a long pulse of several hours into two of the injection pipe segments and two tracers (Rhenium oxide and Gd-DTPA) were instantaneously injected to the other two segments. The tracers were detected 0.7 to 2.3 hours after injection in four of the five observation wells, located 2.3 to 10 m from the injection system, respectively. Groundwater velocities were calculated directly from the tracers' arrival times and by fitting the observed breakthrough curves to simulations with one and two dimensions analytical solutions for conservative tracer transport. The groundwater velocity was determined to be ~100 m/d. The longitudinal dispersivity value, generated from fitting the tracer breakthrough curves, was in a range of 0.2-3m. The groundwater flow direction was derived based on the arrival of the tracers and was found to be consistent with the apparent direction of the hydraulic gradient. The hydraulic conductivity derived from the groundwater velocity was ~1200 m/d, which is in the upper range of gravel sediment.

Measuring air-water interfacial area for soils using the mass balance surfactant-tracer method.

PubMed

Araujo, Juliana B; Mainhagu, Jon; Brusseau, Mark L

2015-09-01

There are several methods for conducting interfacial partitioning tracer tests to measure air-water interfacial area in porous media. One such approach is the mass balance surfactant tracer method. An advantage of the mass-balance method compared to other tracer-based methods is that a single test can produce multiple interfacial area measurements over a wide range of water saturations. The mass-balance method has been used to date only for glass beads or treated quartz sand. The purpose of this research is to investigate the effectiveness and implementability of the mass-balance method for application to more complex porous media. The results indicate that interfacial areas measured with the mass-balance method are consistent with values obtained with the miscible-displacement method. This includes results for a soil, for which solid-phase adsorption was a significant component of total tracer retention. Copyright © 2015 Elsevier Ltd. All rights reserved.

Interpretation of single-well push-pull spikings conducted in deep crystalline formations (Soultz-s.-F. in the Upper Rhine Graben, and KTB-VB at the German site of ICDP)

NASA Astrophysics Data System (ADS)

Ghergut, J.; Sauter, M.; Behrens, H.; (Steffen) Fischer, S.; (Steffi) Fischer, S.; Licha, T.; Nottebohm, M.

2009-04-01

Two somewhat contrasting model approaches are presented, both aimed at interpreting long-term return signals from tracer push-pull tests conducted at single wells penetrating increased-permeability features in crystalline rock, about 4 km deep. The general idea is that single-well tracer push-pull tests, owing to the flow-field reversal, should provide privileged access to advection-independent parameters of solute transport, like the density of fluid-rock contact surface areas (Sauter et al., 2002). The latter is equivalent to the heat exchange area for a liquid-based geothermal system. At the geothermal site of Soultz-sous-Forêts in the Upper Rhine Graben, the French BRGM, in cooperation with EGI Utah and other partners, conducted a comprehensive tracer testing programme, whose results were presented in detail by Sanjuan et al. (2004, 2006), Rose et al. (2006). Of these results, we pick the tracer return signals detected during post-stimulation backflow periods at borehole GPK-2 between 2000 and 2002 (as published by Sanjuan et al., 2004) and attempt to interpret them in terms of a single-well injection-withdrawal sequence. Two chemically dissimilar organic tracers have been used by BRGM; however the difference between their return signals seems not significant enough to allow quantifying fluid-rock contact surfaces from this difference alone (additional / a priori information on coefficients of solute exchange across these surfaces would be required). Instead, the tracer return signals enable characterizing the nature of solute exchange processes within the spiked volume of the assumed fractured-porous formation (highly altered crystalline rock). At least one rapid-exchange (E-7 / d), slightly dispersive (Pe~12) component and one moderate-exchange (2E-8 / d), less dispersive (Pe~20) component appear to act within few hundred metres and, respectively, within at least 1 km radial distance from the borehole. - An alternative component of extremely fast exchange (increase of solute exchange fluxes by factor E+5) can as well reproduce the available data, but is physically implausible. For a reliable determination of heat exchange areas at geothermally relevant space scales, additional tracer testings (including heat backflow tests) would be required. At the German site of ICDP (Intl. Continental Scientific Drilling Program, with 'Kontinentale Tiefbohrung' at Windischeschenbach in NE Bavaria), a sequence of multi-tracer push-pull tests was conducted by the Göttingen Group between 2004 and 2006 at the pilot hole (KTB-VB) in hydraulically depleted, stimulated and post-stimulated states (following a long-term pumping test, and massive injection tests, respectively). Here, the spiking design was such that significant differences occurred between the signals of various simultaneously-injected tracers, enabling - at least theoretically - to quantify fracture densities; furthermore, the differences between solute and heat backflow signals produced under different hydraulic regimes can be used to characterize hydro-thermo-mechanical processes induced by massive cold-water injection. Both spiking-derived informations are relevant to a future geothermal project at this site. References: - P. E. Rose, M. Mella, J. McCulloch (2006) A Comparison of Hydraulic Stimulation Experiments at the Soultz/France and Coso/California Engineered Geothermal Systems. Stanford University, SGP-TR-179. - B. Sanjuan, P. Rose, J.-C. Foucher, M. Brach, G. Braibant (2004) Tracer testing at Soultz-sous-Forêts (France) using Na-benzoate, 1,5- and 2,7-napththalene disulfonate. Stanford University, SGP-TR-175. - B. Sanjuan, J.-L. Pinault, P. Rose, A. Gérard, M. Brach, G. Braibant, C. Crouzet, J.-C. Foucher, A. Gautier, S. Touzelet (2006) Tracer testing of the geothermal heat exchanger at Soultz-sous-Forêts (France) between 2000 and 2005. Geothermics, 35, 622-653. - M. Sauter, et al. (2002) Tracer push-pull experiment at the deep borehole Urach-3. Report, University of Göttingen.

Multispecies reactive tracer test in an aquifer with spatially variable chemical conditions

USGS Publications Warehouse

Davis, J.A.; Kent, D.B.; Coston, J.A.; Hess, K.M.; Joye, J.L.

2000-01-01

A field investigation of multispecies reactive transport was conducted in a well‐characterized, sand and gravel aquifer on Cape Cod, Massachusetts. The aquifer is characterized by regions of differing chemical conditions caused by the disposal of secondary sewage effluent. Ten thousand liters of groundwater with added tracers (Br, Cr(VI), and EDTA complexed with Pb, Zn, Cu, and Ni) were injected into the aquifer and distributions of the tracers were monitored for 15 months. Most of the tracers were transported more than 200 m; transport was quantified using spatial moments computed from the results of a series of synoptic samplings. Cr(VI) transport was retarded relative to Br; the retardation factor varied from 1.1 to 2.4 and was dependent on chemical conditions. At 314 days after the injection, dissolved Cr(VI) mass in the tracer cloud had decreased 85%, with the likely cause being reduction to Cr(III) in a suboxic region of the aquifer. Transport of the metal‐EDTA complexes was affected by aqueous complexation, adsorption, and dissolution‐precipitation reactions of Fe oxyhydroxide minerals in the aquifer sediments. Dissolved Pb‐EDTA complexes disappeared from the tracer cloud within 85 days, probably due to metal exchange reactions with Fe and adsorbed Zn (present prior to the injection from contamination by the sewage effluent). About 30% of the Cu‐EDTA complexes remained within the tracer cloud 314 days after injection, even though the thermodynamic stability of the Pb‐EDTA complex is greater than Cu‐EDTA. It is hypothesized that stronger adsorption of Pb2+ to the aquifer sediments causes the Pb‐EDTA complex to disassociate to a greater degree than the Cu‐EDTA complex. The mass of dissolved Zn‐EDTA increased during the first 175 days of the tracer test to 140% of the mass injected, with the increase due to desorption of sewage‐derived Zn. Dissolved Ni‐EDTA mass remained nearly constant throughout the tracer test, apparently only participating in reversible adsorption reactions. The results of the field experiment provide a chemically complex data set that can be used in the testing of reactive transport models of flow coupled with chemical reactions.

Stable Carbon Isotope Evidence and Quantification of Reductive Dechlorination of Chlorinated Ethenes at Kelly AFB, TX

NASA Astrophysics Data System (ADS)

Morrill, P.; Lacrampe-Couloume, G.; Slater, G.; Sleep, B.; Edwards, E.; McMaster, M.; Major, D.; Sherwood Lollar, B.

2002-12-01

Cis-1, 2-dichloroethene (cDCE) was the primary volatile organic compound (VOC) after biostimulation of a perchloroethene (PCE) plume in a pilot test at Kelly Air Force Base (AFB) in San Antonio Texas. A stable natural microbial consortium, KB-1, shown in laboratory experiments to reduce chlorinated ethenes to non-toxic ethene was added in a pilot test area (PTA). After the addition of KB-1 stable carbon isotope values were measured for each chlorinated ethene to verify the occurrence of reductive dechlorination and quantify the extent of cDCE degradation. After bioaugmentation with KB-1, PCE, TCE and cDCE concentrations declined, while VC concentrations increased and subsequently decreased, as ethene became the dominant transformation product measured. Shifts in carbon isotopic values up to 2.7 permil, 6.4 permil, 10.9 permil and 10.6 permil were observed for PCE, TCE, cDCE and VC respectively. These isotopic shifts are consistent with the effects of biodegradation observed during laboratory and field studies. Most notably, isotopic enrichment trends characteristic of reductive dechlorination were detectable in the parent compounds before measurable concentrations of daughter products VC and ethene were produced. These results illustrate the advantage of using the more sensitive compound specific isotope analysis to confirm degradation in addition to the traditional method of monitoring the appearance of degradation products. Fractionation factors obtained from laboratory studies were used in conjunction with isotope data measured in the field to estimate the extent of cDCE degraded. It is estimated that within a 44 day period, 37 to 48 percent of the cDCE was reductively dechlorinated. Independent biodegradation estimates using data from a bromide tracer test, a groundwater flow model, and concentration analyses were all in good agreement with the isotope degradation estimate.

A Lagrangian particle method with remeshing for tracer transport on the sphere

DOE PAGES

Bosler, Peter Andrew; Kent, James; Krasny, Robert; ...

2017-03-30

A Lagrangian particle method (called LPM) based on the flow map is presented for tracer transport on the sphere. The particles carry tracer values and are located at the centers and vertices of triangular Lagrangian panels. Remeshing is applied to control particle disorder and two schemes are compared, one using direct tracer interpolation and another using inverse flow map interpolation with sampling of the initial tracer density. Test cases include a moving-vortices flow and reversing-deformational flow with both zero and nonzero divergence, as well as smooth and discontinuous tracers. We examine the accuracy of the computed tracer density and tracermore » integral, and preservation of nonlinear correlation in a pair of tracers. Here, we compare results obtained using LPM and the Lin–Rood finite-volume scheme. An adaptive particle/panel refinement scheme is demonstrated.« less

A Lagrangian particle method with remeshing for tracer transport on the sphere

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

Bosler, Peter Andrew; Kent, James; Krasny, Robert

A Lagrangian particle method (called LPM) based on the flow map is presented for tracer transport on the sphere. The particles carry tracer values and are located at the centers and vertices of triangular Lagrangian panels. Remeshing is applied to control particle disorder and two schemes are compared, one using direct tracer interpolation and another using inverse flow map interpolation with sampling of the initial tracer density. Test cases include a moving-vortices flow and reversing-deformational flow with both zero and nonzero divergence, as well as smooth and discontinuous tracers. We examine the accuracy of the computed tracer density and tracermore » integral, and preservation of nonlinear correlation in a pair of tracers. Here, we compare results obtained using LPM and the Lin–Rood finite-volume scheme. An adaptive particle/panel refinement scheme is demonstrated.« less

Recover Act. Verification of Geothermal Tracer Methods in Highly Constrained Field Experiments

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

Becker, Matthew W.

2014-05-16

The prediction of the geothermal system efficiency is strong linked to the character of the flow system that connects injector and producer wells. If water flow develops channels or “short circuiting” between injection and extraction wells thermal sweep is poor and much of the reservoir is left untapped. The purpose of this project was to understand how channelized flow develops in fracture geothermal reservoirs and how it can be measured in the field. We explored two methods of assessing channelization: hydraulic connectivity tests and tracer tests. These methods were tested at a field site using two verification methods: ground penetratingmore » radar (GPR) images of saline tracer and heat transfer measurements using distributed temperature sensing (DTS). The field site for these studies was the Altona Flat Fractured Rock Research Site located in northeastern New York State. Altona Flat Rock is an experimental site considered a geologic analog for some geothermal reservoirs given its low matrix porosity. Because soil overburden is thin, it provided unique access to saturated bedrock fractures and the ability image using GPR which does not effectively penetrate most soils. Five boreholes were drilled in a “five spot” pattern covering 100 m2 and hydraulically isolated in a single bedding plane fracture. This simple system allowed a complete characterization of the fracture. Nine small diameter boreholes were drilled from the surface to just above the fracture to allow the measurement of heat transfer between the fracture and the rock matrix. The focus of the hydraulic investigation was periodic hydraulic testing. In such tests, rather than pumping or injection in a well at a constant rate, flow is varied to produce an oscillating pressure signal. This pressure signal is sensed in other wells and the attenuation and phase lag between the source and receptor is an indication of hydraulic connection. We found that these tests were much more effective than constant pumping tests in identifying a poorly connected well. As a result, we were able to predict which well pairs would demonstrate channelized flow. The focus of the tracer investigation was multi-ionic tests. In multi-ionic tests several ionic tracers are injected simultaneously and the detected in a nearby pumping well. The time history of concentration, or breakthrough curve, will show a separation of the tracers. Anionic tracers travel with the water but cationic tracer undergo chemical exchange with cations on the surface of the rock. The degree of separation is indicative of the surface area exposed to the tracer. Consequently, flow channelization will tend to decrease the separation in the breakthrough. Estimation of specific surface area (the ration of fracture surface area to formation volume) is performed through matching the breakthrough curve with a transport model. We found that the tracer estimates of surface area were confirmed the prediction of channelized flow between well pairs produced by the periodic hydraulic tests. To confirm that the hydraulic and tracer tests were correctly predicting channelize flow, we imaged the flow field using surface GPR. Saline water was injected between the well pairs which produced a change in the amplitude and phase of the reflected radar signal. A map was produced of the migration of saline tracer from these tests which qualitatively confirmed the flow channelization predicted by the hydraulic and tracer tests. The resolution of the GPR was insufficient to quantitatively estimate swept surface area, however. Surface GPR is not applicable in typical geothermal fields because the penetration depths do not exceed 10’s of meters. Nevertheless, the method of using of phase to measure electrical conductivity and the assessment of antennae polarization represent a significant advancement in the field of surface GPR. The effect of flow character on fracture / rock thermal exchange was evaluated using heated water as a tracer. Water elevated 30 degrees C above the formation water was circulated between two wells pairs. One well pair had been identified in hydraulic and tracer testing as well connected and the other poorly connected. Temperature rise was measured in the adjacent rock matrix using coiled fiber optic cable interrogated for temperature using a DTS. This experimental design produced over 4000 temperature measurements every hour. We found that heat transfer between the fracture and the rock matrix was highly impacted by the character of the flow field. The strongly connected wells which had demonstrated flow channelization produced heat rise in a much more limited area than the more poorly connected wells. In addition, the heat increase followed the natural permeability of the fracture rather than the induced flow field. The primary findings of this work are (1) even in a single relatively planar fracture, the flow field can be highly heterogeneous and exhibit flow channeling, (2) channeling results from a combination of fracture permeability structure and the induced flow field, and (3) flow channeling leads to reduced heat transfer. Multi-ionic tracers effectively estimate relative surface area but an estimate of ion-exchange coefficients are necessary to provide an absolute measure of specific surface area. Periodic hydraulic tests also proved a relative indicator of connectivity but cannot prove an absolute measure of specific surface area.« less

SPECT/CT tracer uptake is influenced by tunnel orientation and position of the femoral and tibial ACL graft insertion site.

PubMed

Hirschmann, Michael T; Mathis, Dominic; Rasch, Helmut; Amsler, Felix; Friederich, Niklaus F; Arnold, Markus P

2013-02-01

SPECT/CT is a hybrid imaging modality, which combines a 3D scintigraphy (SPECT) and a conventional computerised tomography (CT). SPECT/CT allows accurate anatomical localisation of metabolic tracer activity. It allows the correlation of surgical factors such as tunnel position and orientation with mechanical alignment, clinical outcome and biological factors. The purpose of this study was to investigate whether the SPECT/CT tracer uptake (intensity and distribution) correlates with the stability and laxity of the knee joint and the position and orientation of the tibial and femoral tunnels in patients after anterior cruciate ligament (ACL) reconstruction. A consecutive series of knees (n=66), with symptoms of pain and/or instability after ACL reconstruction were prospectively evaluated using clinical examination and 99mTc-HDP-SPECT/CT. Clinical laxity testing was performed using the Rolimeter (Ormed, Freiburg, Germany) including Lachman testing (0-2 mm, 3-5 mm, 6-10 mm, >10 mm), anterior drawer test (0-2 mm, 3-5 mm, 6-10 mm, >10 mm), pivot shift test (positive versus negative) and patient-based subjective instability (yes versus no). For analysis of SPECT/CT tracer uptake a previously validated SPECT/CT localisation scheme consisting of 17 tibial, nine femoral and four patellar regions on standardised axial, coronal, and sagittal slices was used. The tracer activity on SPECT/CT was localised and recorded using a 3D volumetric and quantitative analysis software. Mean, standard deviation, minimum and maximum of grading for each area of the localisation scheme were recorded. The position and orientation of the tibial and femoral tunnel was assessed using a previously published method on 3D-CT. Correlation of instability, pivot shift as well as clinical laxity testing with 99mTc-HDP-SPECT/CT tracer uptake intensity and distribution showed no significant correlation. 99mTc-HDP-SPECT/CT tracer uptake correlated significantly with the position and orientation of the ACL graft. A more horizontal femoral graft position showed significantly increased tracer uptake within the superior and posterior femoral regions. A more posteriorly-placed femoral insertion site showed significantly more tracer uptake within the femoral and tibial tunnel regions. A more vertical or a less medial tibial tunnel orientation showed significant increased uptake within the tibial and femoral tunnel regions. A more anterior tibial tunnel position showed significantly more tracer uptake in the femoral and tibial tunnel regions as well as the entire tibiofemoral joint. SPECT/CT tracer uptake intensity and distribution showed a significant correlation with the femoral and tibial tunnel position and orientation in patients with symptomatic knees after ACL reconstruction. No correlation was found with stability or clinical laxity. SPECT/CT tracer uptake distribution has the potential to give us important information on joint homeostasis and remodelling after ACL reconstruction. It might help to predict ACL graft failure and improve our surgical ACL reconstruction technique in finding the optimal tunnel and graft position and orientation.

77 FR 20752 - Methyl Bromide; Proposed Pesticide Tolerance

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-06

... fumigated with methyl bromide requires a tolerance. Without a tolerance or exemption, food or feed... livestock feeding items resulting from fumigation of cottonseed with methyl bromide are covered by existing... produced from cottonseed fumigated with methyl bromide would not contain residues of methyl bromide...

A MULTI-STREAM MODEL FOR VERTICAL MIXING OF A PASSIVE TRACER IN THE CONVECTIVE BOUNDARY LAYER

EPA Science Inventory

We study a multi-stream model (MSM) for vertical mixing of a passive tracer in the convective boundary layer, in which the tracer is advected by many vertical streams with different probabilities and diffused by small scale turbulence. We test the MSM algorithm for investigatin...

The effect of entrapped nonaqueous phase liquids on tracer transport in heterogeneous porous media: Laboratory experiments at the intermediate scale

USGS Publications Warehouse

Barth, Gilbert R.; Illangasekare, T.H.; Rajaram, H.

2003-01-01

This work considers the applicability of conservative tracers for detecting high-saturation nonaqueous-phase liquid (NAPL) entrapment in heterogeneous systems. For this purpose, a series of experiments and simulations was performed using a two-dimensional heterogeneous system (10??1.2 m), which represents an intermediate scale between laboratory and field scales. Tracer tests performed prior to injecting the NAPL provide the baseline response of the heterogeneous porous medium. Two NAPL spill experiments were performed and the entrapped-NAPL saturation distribution measured in detail using a gamma-ray attenuation system. Tracer tests following each of the NAPL spills produced breakthrough curves (BTCs) reflecting the impact of entrapped NAPL on conservative transport. To evaluate significance, the impact of NAPL entrapment on the conservative-tracer breakthrough curves was compared to simulated breakthrough curve variability for different realizations of the heterogeneous distribution. Analysis of the results reveals that the NAPL entrapment has a significant impact on the temporal moments of conservative-tracer breakthrough curves. ?? 2003 Elsevier B.V. All rights reserved.

The fluorescent tracer experiment on Holiday Beach near Mugu Canyon, Southern California

USGS Publications Warehouse

Kinsman, Nicole; Xu, J. P.

2012-01-01

After revisiting sand tracer techniques originally developed in the 1960s, a range of fluorescent coating formulations were tested in the laboratory. Explicit steps are presented for the preparation of the formulation evaluated to have superior attributes, a thermoplastic pigment/dye in a colloidal mixture with a vinyl chloride/vinyl acetate copolymer. In September 2010, 0.59 cubic meters of fluorescent tracer material was injected into the littoral zone about 4 kilometers upcoast of Mugu submarine canyon in California. The movement of tracer was monitored in three dimensions over the course of 4 days using manual and automated techniques. Detailed observations of the tracer's behavior in the coastal zone indicate that this tracer successfully mimicked the native beach sand and similar methods could be used to validate models of tracer movement in this type of environment. Recommendations including how to time successful tracer studies and how to scale the field of view of automated camera systems are presented along with the advantages and disadvantages of the described tracer methodology.

Preservation of commonly applied fluorescent tracers in complex water samples

NASA Astrophysics Data System (ADS)

Cao, Viet; Schaffer, Mario; Jin, Yulan; Licha, Tobias

2017-06-01

Water sample preservation and pre-treatment are important steps for achieving accurate and reproductive results from tracer tests. However, this is particularly challenging for complex water mixtures prior to fluorescence analysis. In this study, the interference of iron and calcium precipitation with nine commonly applied conservative tracers, uranine, eosin, 1-naphthalene sulfonate, 1,5-naphthalene disulfonate, 2,6-naphthalene disulfonate, 4-amino-1-naphthalene sulfonate, 6-hydroxy-2-naphthalene sulfonate, 1,3,6-naphthalene trisulfonate, and 1,3,6,8-pyrene tetrasulfonate, was investigated in batch experiments. In general, the observed results are influenced by precipitates. A technique consisting of pH adjustment and centrifugation is described for preserving samples and avoiding the impact of these precipitates on the tracer test results.

Multiport well design for sampling of ground water at closely spaced vertical intervals

USGS Publications Warehouse

Delin, G.N.; Landon, M.K.

1996-01-01

Detailed vertical sampling is useful in aquifers where vertical mixing is limited and steep vertical gradients in chemical concentrations are expected. Samples can be collected at closely spaced vertical intervals from nested wells with short screened intervals. However, this approach may not be appropriate in all situations. An easy-to-construct and easy-to-install multiport sampling well to collect ground-water samples from closely spaced vertical intervals was developed and tested. The multiport sampling well was designed to sample ground water from surficial sand-and-gravel aquifers. The device consists of multiple stainless-steel tubes within a polyvinyl chloride (PVC) protective casing. The tubes protrude through the wall of the PVC casing at the desired sampling depths. A peristaltic pump is used to collect ground-water samples from the sampling ports. The difference in hydraulic head between any two sampling ports can be measured with a vacuum pump and a modified manometer. The usefulness and versatility of this multiport well design was demonstrated at an agricultural research site near Princeton, Minnesota where sampling ports were installed to a maximum depth of about 12 m below land surface. Tracer experiments were conducted using potassium bromide to document the degree to which short-circuiting occurred between sampling ports. Samples were successfully collected for analysis of major cations and anions, nutrients, selected herbicides, isotopes, dissolved gases, and chlorofluorcarbon concentrations.

Enhanced vadose zone nitrogen removal by poplar during dormancy.

PubMed

Ausland, Hayden; Ward, Adam; Licht, Louis; Just, Craig

2015-01-01

A pilot-scale, engineered poplar tree vadose zone system was utilized to determine effluent nitrate (NO3(-)) and ammonium concentrations resulting from intermittent dosing of a synthetic wastewater onto sandy soils at 4.5°C. The synthetic wastewater replicated that of an industrial food processor that irrigates onto sandy soils even during dormancy which can leave groundwater vulnerable to NO3(-) contamination. Data from a 21-day experiment was used to assess various Hydrus model parameterizations that simulated the impact of dormant roots. Bromide tracer data indicated that roots impacted the hydraulic properties of the packed sand by increasing effective dispersion, water content and residence time. The simulated effluent NO3(-) concentration on day 21 was 1.2 mg-N L(-1) in the rooted treatments compared to a measured value of 1.0 ± 0.72 mg-N L(-1). For the non-rooted treatment, the simulated NO3(-) concentration was 4.7 mg-N L(-1) compared to 5.1 ± 3.5 mg-N L(-1) measured on day 21. The model predicted a substantial "root benefit" toward protecting groundwater through increased denitrification in rooted treatments during a 21-day simulation with 8% of dosed nitrogen converted to N2 compared to 3.3% converted in the non-rooted test cells. Simulations at the 90-day timescale provided similar results, indicating increased denitrification in rooted treatments.

Simplified behaviors from increased heterogeneity: II. 3-D uranium transport at the decimeter scale and intertank comparisons.

PubMed

Miller, Andrew W; Rodriguez, Derrick R; Honeyman, Bruce D

2013-05-01

Upscaling from bench scale systems to field scale systems incorporates physical and chemical heterogeneities from atomistic up to field scales. Heterogeneities of intermediate scale (~10(-1) m) are impossible to incorporate in a bench scale experiment. To transcend these scale discrepancies, this second in a pair of papers presents results from an intermediate scale, 3-D tank experiment completed using five different particle sizes of uranium contaminated sediment from a former uranium mill field site. The external dimensions of the tank were 2.44 m×0.61 m×0.61 m (L×H×W). The five particle sizes were packed in a heterogeneous manner using roughly 11 cm cubes. Small groundwater wells were installed for spatial characterization of chemical gradients and flow parameters. An approximately six month long bromide tracer test was used for flow field characterization. Within the flow domain, local uranium breakthrough curves exhibited a wide range of behaviors. However, the global effluent breakthrough curve was smooth, and not unlike breakthrough curves observed in column scale experiments. This paper concludes with an inter-tank comparison of all three experimental systems presented in this pair of papers. Although there is a wide range of chemical and physical variability between the three tanks, major chemical constituent behaviors are often quite similar or even identical. Copyright © 2013 Elsevier B.V. All rights reserved.

Partitioning Tracer Test for Detection, Estimation, and Remediation Performance Assessment of Subsurface Nonaqueous Phase Liquids

NASA Astrophysics Data System (ADS)

Jin, Minquan; Delshad, Mojdeh; Dwarakanath, Varadarajan; McKinney, Daene C.; Pope, Gary A.; Sepehrnoori, Kamy; Tilburg, Charles E.; Jackson, Richard E.

1995-05-01

In this paper we present a partitioning interwell tracer test (PITT) technique for the detection, estimation, and remediation performance assessment of the subsurface contaminated by nonaqueous phase liquids (NAPLs). We demonstrate the effectiveness of this technique by examples of experimental and simulation results. The experimental results are from partitioning tracer experiments in columns packed with Ottawa sand. Both the method of moments and inverse modeling techniques for estimating NAPL saturation in the sand packs are demonstrated. In the simulation examples we use UTCHEM, a comprehensive three-dimensional, chemical flood compositional simulator developed at the University of Texas, to simulate a hypothetical two-dimensional aquifer with properties similar to the Borden site contaminated by tetrachloroethylene (PCE), and we show how partitioning interwell tracer tests can be used to estimate the amount of PCE contaminant before remedial action and as the remediation process proceeds. Tracer tests results from different stages of remediation are compared to determine the quantity of PCE removed and the amount remaining. Both the experimental (small-scale) and simulation (large-scale) results demonstrate that PITT can be used as an innovative and effective technique to detect and estimate the amount of residual NAPL and for remediation performance assessment in subsurface formations.

Partitioning tracer test for detection, estimation, and remediation performance assessment of subsurface nonaqueous phase liquids

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

Jin, M.; Delshad, M.; Dwarakanath, V.

1995-05-01

In this paper we present a partitioning interwell tracer test (PITT) technique for the detection, estimation, and remediation performance assessment of the subsurface contaminated by nonaqueous phase liquids (NAPLs). We demonstrate the effectiveness of this technique by examples of experimental and simulation results. The experimental results are from partitioning tracer experiments in columns packed with Ottawa sand. Both the method of moments and inverse modeling techniques for estimating NAPL saturation in the sand packs are demonstrated. In the simulation examples we use UTCHEM, a comprehensive three-dimensional, chemical flood compositional simulator developed at the University of Texas, to simulate a hypotheticalmore » two-dimensional aquifer with properties similar to the Borden site contaminated by tetrachloroethylene (PCE), and we show how partitioning interwell tracer tests can be used to estimate the amount of PCE contaminant before remedial action and as the remediation process proceeds. Tracer test results from different stages of remediation are compared to determine the quantity of PCE removed and the amount remaining. Both the experimental (small-scale) and simulation (large-scale) results demonstrate that PITT can be used as an innovative and effective technique to detect and estimate the amount of residual NAPL and for remediation performance assessment in subsurface formations. 43 refs., 10 figs., 1 tab.« less

An inverse modeling approach to estimate groundwater flow and transport model parameters at a research site at Vandenberg AFB, CA

NASA Astrophysics Data System (ADS)

Rasa, E.; Foglia, L.; Mackay, D. M.; Ginn, T. R.; Scow, K. M.

2009-12-01

A numerical groundwater fate and transport model was developed for analyses of data from field experiments evaluating the impacts of ethanol on the natural attenuation of benzene, toluene, ethylbenzene, and xylenes (BTEX) and methyl tert-butyl ether (MTBE) at Vandenberg Air Force Base, Site 60. We used the U.S. Geological Survey (USGS) groundwater flow (MODFLOW2000) and transport (MT3DMS) models in conjunction with the USGS universal inverse modeling code (UCODE) to jointly determine flow and transport parameters using bromide tracer data from multiple experiments in the same location. The key flow and transport parameters include hydraulic conductivity of aquifer and aquitard layers, porosity, and transverse and longitudinal dispersivity. Aquifer and aquitard layers were assumed homogenous in this study. Therefore, the calibration parameters were not spatially variable within each layer. A total of 162 monitoring wells in seven transects perpendicular to the mean flow direction were monitored over the course of ten months, resulting in 1,766 bromide concentration data points and 149 head values used as observations for the inverse modeling. The results showed the significance of the concentration observation data in predicting the flow model parameters and indicated the sensitivity of the hydraulic conductivity of different zones in the aquifer including the excavated former contaminant zone. The model has already been used to evaluate alternative designs for further experiments on in situ bioremediation of the tert-butyl alcohol (TBA) plume remaining at the site. We describe the recent applications of the model and future work, including adding reaction submodels to the calibrated flow model.

Fate of 4-nonylphenol and 17β-estradiol in the Redwood River of Minnesota

USGS Publications Warehouse

Writer, Jeffrey H.; Ryan, Joseph N.; Keefe, Steffanie H.; Barber, Larry B.

2012-01-01

The majority of previous research investigating the fate of endocrine-disrupting compounds has focused on single processes generally in controlled laboratory experiments, and limited studies have directly evaluated their fate and transport in rivers. This study evaluated the fate and transport of 4-nonylphenol, 17β-estradiol, and estrone in a 10-km reach of the Redwood River in southwestern Minnesota. The same parcel of water was sampled as it moved downstream, integrating chemical transformation and hydrologic processes. The conservative tracer bromide was used to track the parcel of water being sampled, and the change in mass of the target compounds relative to bromide was determined at two locations downstream from a wastewater treatment plant effluent outfall. In-stream attenuation coefficients (kstream) were calculated by assuming first-order kinetics (negative values correspond to attenuation, whereas positive values indicate production). Attenuation of 17β-estradiol (kstream = −3.2 ± 1.0 day–1) was attributed primarily due to sorption and biodegradation by the stream biofilm and bed sediments. Estrone (kstream = 0.6 ± 0.8 day–1) and 4-nonylphenol (kstream = 1.4 ± 1.9 day–1) were produced in the evaluated 10-km reach, likely due to biochemical transformation from parent compounds (17β-estradiol, 4-nonylphenolpolyethoxylates, and 4-nonyphenolpolyethoxycarboxylates). Despite attenuation, these compounds were transported kilometers downstream, and thus additive concentrations from multiple sources and transformation of parent compounds into degradates having estrogenic activity can explain their environmental persistence and widespread observations of biological disruption in surface waters.

Testing high resolution numerical models for analysis of contaminant storage and release from low permeability zones

NASA Astrophysics Data System (ADS)

Chapman, Steven W.; Parker, Beth L.; Sale, Tom C.; Doner, Lee Ann

2012-08-01

It is now widely recognized that contaminant release from low permeability zones can sustain plumes long after primary sources are depleted, particularly for chlorinated solvents where regulatory limits are orders of magnitude below source concentrations. This has led to efforts to appropriately characterize sites and apply models for prediction incorporating these effects. A primary challenge is that diffusion processes are controlled by small-scale concentration gradients and capturing mass distribution in low permeability zones requires much higher resolution than commonly practiced. This paper explores validity of using numerical models (HydroGeoSphere, FEFLOW, MODFLOW/MT3DMS) in high resolution mode to simulate scenarios involving diffusion into and out of low permeability zones: 1) a laboratory tank study involving a continuous sand body with suspended clay layers which was 'loaded' with bromide and fluorescein (for visualization) tracers followed by clean water flushing, and 2) the two-layer analytical solution of Sale et al. (2008) involving a relatively simple scenario with an aquifer and underlying low permeability layer. All three models are shown to provide close agreement when adequate spatial and temporal discretization are applied to represent problem geometry, resolve flow fields and capture advective transport in the sands and diffusive transfer with low permeability layers and minimize numerical dispersion. The challenge for application at field sites then becomes appropriate site characterization to inform the models, capturing the style of the low permeability zone geometry and incorporating reasonable hydrogeologic parameters and estimates of source history, for scenario testing and more accurate prediction of plume response, leading to better site decision making.

Interaction of pyridostigmine bromide and N,N-diethyl-m-toluamide alone and in combination with P-glycoprotein expressed in Escherichia coli leaky mutant.

PubMed

El-Masry, Eman M; Abou-Donia, Mohamed B

2006-05-01

P-glycoprotein (P-gp), the most extensively studied ATP-binding transporter, functions as a biological barrier by extruding toxic substances and xenobiotics out of the cell. This study was carried out to determine the effect of N,N-diethyl-m-toluamide (DEET) and pyridostigmine bromide (PB), alone and in combination, on P-gp expression using Escherichia coli leaky mutant transformed with Mdr1 gene (pT5-7/mdr1), which codes for P-gp or lactose permease (pT5-7/lacY) as negative control. Also, daunomycin (a known P-gp sustrate) was used as a positive control and reserpine (a known P-gp inhibitor) served as a negative control. An in vitro cell-resistant assay was used to monitor the potential of test compounds to interact with P-gp. Following exposure of the cells to pyridostigmine bromide or daunomycin, P-gp conferred significant resistance against both compounds, while reserpine and DEET significantly inhibited the glycoprotein. Cells were grown in the presence of noncytotoxic concentrations of daunomycin, pyridostigmine bromide, reserpine, or DEET, and membrane fractions were examined by Western immunoblotting for expression of P-gp. Daunomycin induced P-gp expression quantitatively more than pyridostigmine bromide, while reserpine and DEET significantly inhibited P-gp expression in cells harboring mdr1. Photoaffinity labeling experiment performed with the P-gp ligand [125I]iodoarylazidoprazosin demonstrated that compounds that induced or inhibited P-gp transport activity also bound to P-gp. DEET was also found to be a potent inhibitor of P-gp-mediated ATPase activity, whereas pyridostigmine bromide increased P-gp ATPase activity. Cells expressing P-gp or lac permease were exposed to pyridostigmine bromide and DEET, alone and in combination. Noncytotoxic concentrations of DEET significantly inhibited P-gp-mediated resistance against pyridostigmine bromide, resulting in a reduction of the number of effective drug interactions with biological targets. An explanation of these results might be that DEET is a third-generation inhibitor of P-gp; it has high potency and specificity for P-gp, it inhibits hydrolysis of ATP, it exerts no appreciable impact on cytochrome P-450 3A4, and it prevents transport of xenobiotics, such as pyridostigmine bromide, out of the cell. This conclusion explains, at least in part, the increased toxicity and bioavailability of pyridostigmine bromide following combined administration with DEET. This study improves our understanding of the basis of chemical interactions with DEET by defining the ability of drugs to interact with P-gp either as inhibitors or substrates, which may in turn lead to altered efficacy or toxicity.

Tracer Transport Along a Vertical Fault Located in Welded Tuffs

NASA Astrophysics Data System (ADS)

Salve, R.; Liu, H.; Hu, Q.

2002-12-01

A near-vertical fault that intercepts the fractured welled tuff formation in the underground Exploratory Studies Facility (ESF) at Yucca Mountain, Nevada, has provided a unique opportunity to evaluate important hydrological parameters associated with faults (e.g., flow velocity, matrix diffusion, fault-fracture-matrix interactions). Alcove 8, which intersects the fault is located in the cross drift of the ESF, has been excavated for liquid releases through this fault and a network of fractures. Located 25 m below Alcove 8 in the main drift of the ESF, Niche 3 which also intercepts the fault, serves as the site for monitoring the wetting front and for collecting seepage following liquid releases in Alcove 8. To investigate the importance of matrix diffusion and the extent of area subject to fracture-matrix interactions, we released a mix of conservative tracers (pentafluorobenzoic acid [PFBA] and lithium bromide [LiBr]) along the fault. The ceiling of Niche 3 was blanketed with an array of trays to capture seepage, and seepage rates were continuously monitored by a water collection system connected to the trays. Additionally, a water sampling device, the passive-discreet water sampler (PDWS), was connected to three of the collections trays in Niche 3 into which water was seeping. The PDWS, designed to isolate continuous seepage from each tray into discreet samples for chemical analysis, remained connected to the trays over a period of three months. During this time, all water that seeped into the three trays was captured sequentially into sampling bottles and analyzed for concentrations of PFBA and LiBr. Water released along the fault initially traveled the 25 m vertical distance over a period of 36 days (at a velocity ~0.7 m/day). The seepage recovered in Niche 3 was less than 10% of the injected water with significant spatial and temporal fluctuations in seepage rates. Along a fast flow path, the benzoic tracer (PFBA) and LiBr were first detected ~12 days after they were released into the fault. Along slower flow paths the tracers appeared ~ two weeks later, with PFBA preceding the LiB. The differing travel times of the two conservative tracers suggests the impact of matrix diffusion in the transport process. This work was supported by the Director, Office of Civilian Radioactive Waste Management, U.S. Department of Energy, through Memorandum Purchase Order EA9013MC5X between Bechtel SAIC Company, LLC, and the Ernest Orlando Lawrence Berkeley National Laboratory (Berkeley Lab). The support is provided to Berkeley Lab through the U.S. Department of Energy Contract No. DE-AC03-76SF00098.

Cetyltrimethyl Ammonium Bromide as Corrosion Inhibitor for Zinc Used in Hydrochloric Acid

NASA Astrophysics Data System (ADS)

Sun, C. X.; Du, J. J.; Ma, Z. W.; Huang, C. S.; Wu, J. Y.

2018-05-01

A compound inhibitor composed of cetyltrimethyl ammonium bromide (CTAB) and bromohexadecyl pyridine was tested as corrosion inhibitor for zinc in hydrochloric acid. The results of static coupon test show that the compound inhibitor can effectively protect zinc from corrosion and the best concentration ratio is CTAB 50 mg/L and bromohexadecyl pyridine 200 mg/L. The polarization results show that the compound inhibitor will cause a negative shift of E0 of zinc in hydrochloric acid. The EIS (electrchemical impedance spectra) results show that the inhibitor leads to a bigger radius and has one time constant. SEM results show that the CTAB and bromohexadecyl pyridine form a uniform and compact membrane on the surface of zinc that can protect zinc from corroding effectively.

A Tracer Test to Characterize Treatment of TCE in a Permeable Reactive Barrier

EPA Science Inventory

A tracer test was conducted to characterize the flow of ground water surrounding a permeable reactive barrier constructed with plant mulch (a biowall) at the OU-1 site on Altus Air Force Base, Oklahoma. This biowall is intended to intercept and treat ground water contaminated by ...

Qtracer Program for Tracer-Breakthrough Curve Analysis for Karst and Fractured-Rock Aquifers (2000)

EPA Science Inventory

Tracer tests are generally regarded as being the most reliable and efficient means of gathering subsurface hydraulic information. This is true for all types of aquifers, but especially so for karst and fractured-rock aquifers. Qualitative tracing tests have been conventionally em...

Aluminum electroplating on steel from a fused bromide electrolyte

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

Prabhat K. Tripathy; Laura A. Wurth; Eric J. Dufek

A quaternary bromide bath (LiBr–KBr–CsBr–AlBr3) was used to electro-coat aluminum on steel substrates. The electrolytewas prepared by the addition of AlBr3 into the eutectic LiBr–KBr–CsBr melt. A smooth, thick, adherent and shiny aluminum coating could be obtained with 80 wt.% AlBr3 in the ternary melt. The SEM photographs of the coated surfaces suggest the formation of thick and dense coatings with good aluminum coverage. Both salt immersion and open circuit potential measurement suggested that the coatings did display a good corrosionresistance behavior. Annealing of the coated surfaces, prior to corrosion tests, suggested the robustness of the metallic aluminum coating inmore » preventing the corrosion of the steel surfaces. Studies also indicated that the quaternary bromide plating bath can potentially provide a better aluminumcoating on both ferrous and non-ferrous metals, including complex surfaces/geometries.« less

Aluminium Electroplating on Steel from a Fused Bromide Electrolyte

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

Prabhat Tripathy; Laura Wurth; Eric Dufek

A quaternary bromide bath (LiBr-KBr-CsBr-AlBr3) was used to electro-coat aluminium on steel substrates. The electrolyte was prepared by the addition of AlBr3 into the eutectic LiBr-KBr-CsBr melt. A smooth, thick, adherent and shiny aluminium coating could be obtained with 80 wt.% AlBr3 in the ternary melt. The SEM photographs of the coated surfaces suggest the formation of thick and dense coatings with good aluminium coverage. Both salt immersion and open circuit potential measurement suggest that the coatings did display good corrosion-resistance behavior. Annealing of the coated surfaces, prior to corrosion tests, suggested the robustness of the metallic aluminium coating inmore » preventing the corrosion of the steel surfaces. Studies also indicated that the quaternary bromide plating bath can potentially provide a better aluminium coating on both ferrous and non-ferrous metals, including complex surfaces/geometries.« less

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

Sathyalakshmi, R.; Bhagavannarayana, G.; Ramasamy, P.

L-(+)-Glutamic acid hydro bromide, an isomorphic salt of L-glutamic acid hydrochloride, was synthesized and the synthesis was confirmed using Fourier transform infrared analysis. Solubility of the material in water was determined. L-Glutamic acid hydro bromide crystals were grown by low temperature solution growth using the solvent evaporation technique. Single crystal X-ray diffraction studies were carried out and the cell parameters, atomic co-ordinates, bond lengths and bond angles were reported. High-resolution X-ray diffraction studies were carried out and good crystallinity for the grown crystal was observed from the diffraction curve. The grown crystals were subjected to dielectric studies. Ultraviolet-visible-near infrared spectralmore » analysis shows good optical transmission in the visible and infrared region of the grown crystals. The second harmonic generation efficiency of L-glutamic acid hydro bromide crystal was determined using the Kurtz powder test and it was found that it had efficiency comparable with that of the potassium di-hydrogen phosphate crystal.« less

Time-lapse Mise-á-la-Masse measurements and modeling for tracer test monitoring in a shallow aquifer

NASA Astrophysics Data System (ADS)

Perri, Maria Teresa; De Vita, Pantaleone; Masciale, Rita; Portoghese, Ivan; Chirico, Giovanni Battista; Cassiani, Giorgio

2018-06-01

The main goal of this study is to evaluate the reliability of the Mise-á-la-Masse (MALM) technique associated with saline tracer tests for the characterization of groundwater flow direction and velocity. The experimental site is located in the upper part of the Alento River alluvial plain (Campania Region, Southern Italy). In this paper we present the hydrogeological setting, the experimental setup and the relevant field results. Subsequently, we compare those data against the simulated results obtained with a 3D resistivity model of the test area, coupled with a model describing the Advection - Dispersion equation for continuous tracer injection. In particular, we calculate a series of 3D forward solutions starting from a reference model, all derived from electrical tomography results, but taking into consideration different values of mean flow velocity and directions. Each electrical resistivity 3D model is used to produce synthetic voltage maps for MALM surveys. Finally, the synthetic MALM voltage maps are compared with the ones measured in the field in order to assess the information content of the MALM dataset with respect to the groundwater field characteristics. The results demonstrate that the information content of the MALM data is sufficient to define important characteristics of the aquifer geometry and properties. This work shows how a combination of three-dimensional time-lapse modeling of flow, tracer transport and electrical current can substantially contribute towards a quantitative interpretation of MALM measurements during a saline tracer test. This approach can thus revive the use of MALM as a practical, low cost field technique for tracer test monitoring and aquifer hydrodynamic characterization.

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.

The use of novel DNA nanotracers to determine groundwater flow paths - a test study at the Grimsel Deep Underground Geothermal (DUG) Laboratory in Switzerland

NASA Astrophysics Data System (ADS)

Kittilä, Anniina; Evans, Keith; Puddu, Michela; Mikutis, Gediminas; Grass, Robert N.; Deuber, Claudia; Saar, Martin O.

2016-04-01

Groundwater flow in fractured media is heterogeneous and takes place in structures with complex geometry and scale effects, which make the characterization and modeling of the groundwater flow technically challenging. Surface geophysical surveys have limited resolution of permeable structures, and often provide ambiguous results, whereas the interpretation of borehole flow logs to infer hydraulic flow paths within fractured reservoirs is usually non-unique. Nonetheless, knowledge of the hydraulic properties of individual fractures and the role they play in determining the larger-scale flow within the fracture network (i.e. the overall flow conditions) is required in many hydrogeological and geo-engineering situations, such as in geothermal reservoir studies. Tracer tests can overcome some of the aforementioned limitations by providing strong constraints on the geometry and characteristics of flow paths linking boreholes within both porous media and fracture-dominated types of reservoirs. In the case of geothermal reservoirs, tracer tests are often used to provide estimates of the pore/fracture volume swept by flow between injection and production wells. This in turn places constraints on the swept surface area, a parameter that is key for estimating the commercial longevity of the geothermal system. A problem with conventional tracer tests is that the solute species used as the tracer tend to persist in detectable quantities within the reservoir for a long time, thereby impeding repeat tracer tests. DNA nanotracers do not suffer from this problem as they can be designed with a unique signature for each test. DNA nanotracers are environmentally friendly, sub-micron sized silica particles encapsulating small fragments of synthetic DNA which can be fabricated to have a specified, uniquely detectable configuration. For this reason, repeat tracer tests conducted with a differently-encoded DNA fragment to that used in the original will not suffer interference from the earlier test. In this study, we present the results of tests of applying novel DNA nanotracers to characterize groundwater flow properties and the flow pathways in a fracture-dominated reservoir in the Deep Underground Geothermal (DUG) Laboratory at the Grimsel Test Site in the Swiss Alps. This study is motivated by subsequent comparisons of similar characterizations of fractured rock masses after hydraulic stimulation. These will take place at the DUG Lab at the end of 2016. The results of the flow-path characterization are also compared with those obtained from classical solute tracer tests.

40 CFR 180.123 - Inorganic bromide residues resulting from fumigation with methyl bromide; tolerances for residues.

Code of Federal Regulations, 2010 CFR

2010-07-01

... from fumigation with methyl bromide; tolerances for residues. 180.123 Section 180.123 Protection of... fumigation with methyl bromide; tolerances for residues. (a) General. (1) Tolerances are established for... on dog food, resulting from fumigation with methyl bromide. (ii) 125 parts per million for residues...

40 CFR 180.123 - Inorganic bromide residues resulting from fumigation with methyl bromide; tolerances for residues.

Code of Federal Regulations, 2011 CFR

2011-07-01

... from fumigation with methyl bromide; tolerances for residues. 180.123 Section 180.123 Protection of... fumigation with methyl bromide; tolerances for residues. (a) General. (1) Tolerances are established for... result of fumigation of the processed food with methyl bromide or from such fumigation in addition to the...

A practical comparison of Copper Bromide Laser for the treatment of vascular lesions.

PubMed

Lee, SunWoo; Lee, TaeBum; Kim, HoYoun; Kim, JungSoo; Eun, HyeJun; Kim, RyunKyung

2013-01-01

The recent rapid growth in demand for aesthetic non-invasive laser treatments such as unwanted skin rejuvenation, removal of age-related vascular blemishes has led to a boom in the medical devices to treat these conditions. Among diverse laser for skin treatment, copper bromide laser is a very effective, safe, and well tolerated treatment for facial telangiectasia at various energy levels and the most important thing of the copper bromide laser device is that the stability of the energy. However there is no evidence about effective copper bromide laser's energy level for the treatment of vascular lesions. We compared energy stability and treatment performance between two energy levels in 2 W and 8 W which commonly use in laser treatment for the vascular lesions. 8 W copper bromide laser was more stable compared than 2 W copper bromide laser. Also, 8 W copper bromide laser was effectively superior to 2 W copper bromide laser in treatment of vascular legion. Consequently, 8 W copper bromide laser treatment for vascular lesion might be more suitable than 2 W copper bromide laser.

Single well surfactant test to evaluate surfactant floods using multi tracer method

DOEpatents

Sheely, Clyde Q.

1979-01-01

Data useful for evaluating the effectiveness of or designing an enhanced recovery process said process involving mobilizing and moving hydrocarbons through a hydrocarbon bearing subterranean formation from an injection well to a production well by injecting a mobilizing fluid into the injection well, comprising (a) determining hydrocarbon saturation in a volume in the formation near a well bore penetrating formation, (b) injecting sufficient mobilizing fluid to mobilize and move hydrocarbons from a volume in the formation near the well bore, and (c) determining the hydrocarbon saturation in a volume including at least a part of the volume of (b) by an improved single well surfactant method comprising injecting 2 or more slugs of water containing the primary tracer separated by water slugs containing no primary tracer. Alternatively, the plurality of ester tracers can be injected in a single slug said tracers penetrating varying distances into the formation wherein the esters have different partition coefficients and essentially equal reaction times. The single well tracer method employed is disclosed in U.S. Pat. No. 3,623,842. This method designated the single well surfactant test (SWST) is useful for evaluating the effect of surfactant floods, polymer floods, carbon dioxide floods, micellar floods, caustic floods and the like in subterranean formations in much less time and at much reduced cost compared to conventional multiwell pilot tests.

Critical zone properties control the fate of nitrogen during experimental rainfall in montane forests of the Colorado Front Range

USGS Publications Warehouse

Hinckley, Eve-Lyn S.; Ebel, Brian A.; Barnes, Rebecca T.; Murphy, Sheila F.; Anderson, Suzanne P.

2017-01-01

Several decades of research in alpine ecosystems have demonstrated links among the critical zone, hydrologic response, and the fate of elevated atmospheric nitrogen (N) deposition. Less research has occurred in mid-elevation forests, which may be important for retaining atmospheric N deposition. To explore the fate of N in the montane zone, we conducted plot-scale experimental rainfall events across a north–south transect within a catchment of the Boulder Creek Critical Zone Observatory. Rainfall events mimicked relatively common storms (20–50% annual exceedance probability) and were labeled with 15N-nitrate (NO3−">NO−3NO3−) and lithium bromide tracers. For 4 weeks, we measured soil–water and leachate concentrations of Br−, 15NO3−,">15NO−3,15NO3−, and NO3−">NO−3NO3− daily, followed by recoveries of 15N species in bulk soils and microbial biomass. Tracers moved immediately into the subsurface of north-facing slope plots, exhibiting breakthrough at 10 and 30 cm over 22 days. Conversely, little transport of Br− or 15NO3−">15NO−315NO3− occurred in south-facing slope plots; tracers remained in soil or were lost via pathways not measured. Hillslope position was a significant determinant of soil 15N-NO3−">NO−3NO3− recoveries, while soil depth and time were significant determinants of 15N recovery in microbial biomass. Overall, 15N recovery in microbial biomass and leachate was greater in upper north-facing slope plots than lower north-facing (toeslope) and both south-facing slope plots in August; by October, 15N recovery in microbial N biomass within south-facing slope plots had increased substantially. Our results point to the importance of soil properties in controlling the fate of N in mid-elevation forests during the summer season.

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.

A hierarchy of models for simulating experimental results from a 3D heterogeneous porous medium

NASA Astrophysics Data System (ADS)

Vogler, Daniel; Ostvar, Sassan; Paustian, Rebecca; Wood, Brian D.

2018-04-01

In this work we examine the dispersion of conservative tracers (bromide and fluorescein) in an experimentally-constructed three-dimensional dual-porosity porous medium. The medium is highly heterogeneous (σY2 = 5.7), and consists of spherical, low-hydraulic-conductivity inclusions embedded in a high-hydraulic-conductivity matrix. The bimodal medium was saturated with tracers, and then flushed with tracer-free fluid while the effluent breakthrough curves were measured. The focus for this work is to examine a hierarchy of four models (in the absence of adjustable parameters) with decreasing complexity to assess their ability to accurately represent the measured breakthrough curves. The most information-rich model was (1) a direct numerical simulation of the system in which the geometry, boundary and initial conditions, and medium properties were fully independently characterized experimentally with high fidelity. The reduced-information models included; (2) a simplified numerical model identical to the fully-resolved direct numerical simulation (DNS) model, but using a domain that was one-tenth the size; (3) an upscaled mobile-immobile model that allowed for a time-dependent mass-transfer coefficient; and, (4) an upscaled mobile-immobile model that assumed a space-time constant mass-transfer coefficient. The results illustrated that all four models provided accurate representations of the experimental breakthrough curves as measured by global RMS error. The primary component of error induced in the upscaled models appeared to arise from the neglect of convection within the inclusions. We discuss the necessity to assign value (via a utility function or other similar method) to outcomes if one is to further select from among model options. Interestingly, these results suggested that the conventional convection-dispersion equation, when applied in a way that resolves the heterogeneities, yields models with high fidelity without requiring the imposition of a more complex non-Fickian model.

(-)-N-[(11)C]propyl-norapomorphine: a positron-labeled dopamine agonist for PET imaging of D(2) receptors.

PubMed

Hwang, D R; Kegeles, L S; Laruelle, M

2000-08-01

Imaging neuroreceptors with radiolabeled agonists might provide valuable information on the in vivo agonist affinity states of receptors of interest. We report here the radiosynthesis, biodistribution in rodents, and imaging studies in baboons of [(11)C]-labeled (-)-N-propyl-norapomorphine [(-)-NPA]. (-)-[(11)C]NPA was prepared by reacting norapomorphine with [(11)C]propionyl chloride and a lithium aluminum hydride reduction. [(11)C]Propionyl chloride was prepared by reacting [(11)C]CO(2) with ethylmagnesium bromide, followed by reacting with phthaloyl chloride. The radiochemical yield of (-)-[(11)C]NPA was 2.5% at end of synthesis (EOS), and the synthesis time was 60 min. The specific activity was 1700+/-1900 mCi/micromol ( N=7; ranged 110-5200 mCi/micromol at EOS). Rodent biodistribution studies showed high uptake of [(11)C](-)-NPA in D(2) receptor-rich areas, and the striatum/cerebellum ratios were 1.7, 3.4, and 4.4 at 5 min, 30 min, and 60 min postinjection, respectively. Pretreating the animals with haloperidol (1 mg/kg) decreased the striatum/cerebellum ratio at 30 min postinjection to 1.3. (-)-[(11)C]NPA was also evaluated via baboon positron emission tomography (PET) studies. Under control conditions ( N=4), rapid uptake of the tracer was observed and the striatum/cerebellum ratio reached 2.86+/-0.15 at 45 min postinjection. Following haloperidol pretreatment (0.2 mg/kg IV), the striatum/cerebellum ratio was 1.29 at 45 min postinjection. The result demonstrated the existence of specific binding of this new tracer to the D(2) receptor. To our knowledge, the current finding of a striatum/cerebellum ratio of 2.8 in baboon was the highest reported with a radiolabeled D(2) agonist. (-)-[(11)C]NPA is a promising new D(2) agonist PET tracer for probing D(2) receptors in vivo using PET.

Simulating Bioremediation of Chloroethenes in a Fractured Rock Aquifer.

NASA Astrophysics Data System (ADS)

Curtis, G. P.

2016-12-01

Reactive transport simulations are being conducted to synthesize the results of a field experiment on the enhanced bioremediation of chloroethenes in a heterogeneous fractured-rock aquifer near West Trenton, NJ. The aquifer consists of a sequence of dipping mudstone beds, with water-conducting bedding-plane fractures separated by low-permeability rock where transport is diffusion-limited. The enhanced bioremediation experiment was conducted by injecting emulsified vegetable oil as an electron donor (EOS™) and a microbial consortium (KB1™) that contained dehalococcoides ethenogenes into a fracture zone that had maximum trichloroethene (TCE) concentrations of 84µM. TCE was significantly biodegraded to dichloroethene, chloroethene and ethene or CO2 at the injection well and at a downgradient well. The results also show the concomitant reduction of Fe(III) and S(6) and the production of methane . The results were used to calibrate transport models for quantifying the dominant mass-removal mechanisms. A nonreactive transport model was developed to simulate advection, dispersion and matrix diffusion of bromide and deuterium tracers present in the injection solution. This calibrated model matched tracer concentrations at the injection well and a downgradient observation well and demonstrated that matrix diffusion was a dominant control on tracer transport. A reactive transport model was developed to extend the nonreactive transport model to simulate the microbially mediated sequential dechlorination reactions, reduction of Fe(III) and S(6), and methanogenesis. The reactive transport model was calibrated to concentrations of chloride, chloroethenes, pH, alkalinity, redox-sensitive species and major ions, to estimate key biogeochemical kinetic parameters. The simulation results generally match the diverse set of observations at the injection and observation wells throughout the three year experiment. In addition, the observations and model simulations indicate that a significant pool of TCE that was initially sorbed to either the fracture surfaces or in the matrix was degraded during the field experiment. The calibrated reactive transport model will be used to quantify the extent of chloroethene mass removal from a range of hypothetical aquifers.

Assessing the sorption and leaching behaviour of three sulfonamides in pasture soils through batch and column studies.

PubMed

Srinivasan, Prakash; Sarmah, Ajit K

2014-09-15

We investigated the sorption potential and transport behaviour of three sulfonamides, namely, sulfamethoxazole (SMO), sulfachloropyridazine (SCP) and sulfamethazine (SM), and a conservative bromide tracer (Br(-)) in two undisturbed soil columns collected from the dairy farming regions in the North Island of New Zealand. Based on the low log Koc values obtained from the sorption study, all three sulfonamides are likely to have high mobility, making them a potential threat to surface and ground water. Soil column studies also showed that the mobility of the sulfonamides varied among soils and antibiotic type. Sulfonamides exhibited a mobility pattern similar to that of conservative Br(-) tracer. Considerable retardation was observed for the Hamilton soil, and the delayed peak arrival time (or maxima) was due to the role of sorption-related retention processes under saturated flow conditions. Residual antibiotic concentrations for SMO and SCP were detected in all soil sections including at 18 cm depth, while no resident concentration of SM was detected at any depth in the entire length of the core for both soils. The deterministic, physical equilibrium model (CXTFIT) described the peak arrival time as well as the maximum concentration of the antibiotic breakthrough curves reasonably, but showed some underestimation at the advanced stages of the leaching process. There was a significant difference in the model estimated retardation factors obtained from column study and the experimental retardation factors obtained from the conventional batch sorption experiments. Copyright © 2014 Elsevier B.V. All rights reserved.

Multitracing Experiment With Solved and Particulate Tracers In An Unsaturated Field Soil

NASA Astrophysics Data System (ADS)

Burkhardt, M.; Kasteel, R.; Vereecken, H.

Solute movement and colloid migration follow preferential flow paths in structured soils at the field scale. The use of microsphreres is a possible option to mimic colloid transport through the vadose zone into the groundwater. We present results of multi- tracing experiments conducted in an Orthic Luvisol using bromide (Br-), the reactive dye tracer Brilliant Blue (BB) and microspheres. The fluorescent microspheres (1 and 10 µm in diameter) were functionalized with a negative surface charge. Eight field plots (about 2 m2) were irrigated with 10 mm and 40 mm during 6 h. Four field plots were sampled directly after the irrgation, the others were exposed for 90 days to natural wheather conditions. Photographs of horizontal cross-sections and disturbed soil sam- ples were taken every 5 to 10 cm down to a depth of 160 cm. Image analysis was used to derive concentration distributions of BB using a calibration relationship between concentration and color spectra. The microspheres were quantified after desorption of the soil samples by fluorescent microscopy and image analysis. We used moment analysis to characterize transport phenomena. We found that transport through the soil matrix was affected by sorption, but all of the applied compounds were transported through preferential flow paths (earthworm burrows) down to a depth of 160 cm irre- spective of their chemical properties. Furthermore, this study shows that microspheres can be used to mimic colloid facilitated transport under unsaturated conditions in a field soil.

Saline tracer visualized with three-dimensional electrical resistivity tomography: Field-scale spatial moment analysis

USGS Publications Warehouse

Singha, Kamini; Gorelick, Steven M.

2005-01-01

Cross-well electrical resistivity tomography (ERT) was used to monitor the migration of a saline tracer in a two-well pumping-injection experiment conducted at the Massachusetts Military Reservation in Cape Cod, Massachusetts. After injecting 2200 mg/L of sodium chloride for 9 hours, ERT data sets were collected from four wells every 6 hours for 20 days. More than 180,000 resistance measurements were collected during the tracer test. Each ERT data set was inverted to produce a sequence of 3-D snapshot maps that track the plume. In addition to the ERT experiment a pumping test and an infiltration test were conducted to estimate horizontal and vertical hydraulic conductivity values. Using modified moment analysis of the electrical conductivity tomograms, the mass, center of mass, and spatial variance of the imaged tracer plume were estimated. Although the tomograms provide valuable insights into field-scale tracer migration behavior and aquifer heterogeneity, standard tomographic inversion and application of Archie's law to convert electrical conductivities to solute concentration results in underestimation of tracer mass. Such underestimation is attributed to (1) reduced measurement sensitivity to electrical conductivity values with distance from the electrodes and (2) spatial smoothing (regularization) from tomographic inversion. The center of mass estimated from the ERT inversions coincided with that given by migration of the tracer plume using 3-D advective-dispersion simulation. The 3-D plumes seen using ERT exhibit greater apparent dispersion than the simulated plumes and greater temporal spreading than observed in field data of concentration breakthrough at the pumping well.

A Lagrangian model for the age of tracer in surface water

NASA Astrophysics Data System (ADS)

Ding, Yu; Liu, Haifei; Yi, Yujun

The age of tracer is a spatio-temporal scale, indicating the transition time of solute particles, which is helpful to monitor and manage the pollutant leakage accidents. In this study, an effective Lagrangian model for the age of tracer is developed based on the lattice Boltzmann method in D2Q5 lattices. A tracer age problem in an asymmetrical circular reservoir is then employed as a benchmark test to verify this method. Then it is applied to computing the age of tracers under two different reservoir operation schemes in the Danjiangkou Reservoir, the drinking water source for the Middle Route of South-to-North Water Transfer Project.

Characterization of preferential flow paths between boreholes in fractured rock using a nanoscale zero-valent iron tracer test

NASA Astrophysics Data System (ADS)

Chuang, Po-Yu; Chia, Yeeping; Liou, Ya-Hsuan; Teng, Mao-Hua; Liu, Ching-Yi; Lee, Tsai-Ping

2016-11-01

Recent advances in borehole geophysical techniques have improved characterization of cross-hole fracture flow. The direct detection of preferential flow paths in fractured rock, however, remains to be resolved. In this study, a novel approach using nanoscale zero-valent iron (nZVI or `nano-iron') as a tracer was developed for detecting fracture flow paths directly. Generally, only a few rock fractures are permeable while most are much less permeable. A heat-pulse flowmeter can be used to detect changes in flow velocity for delineating permeable fracture zones in the borehole and providing the design basis for the tracer test. When nano-iron particles are released in an injection well, they can migrate through the connecting permeable fracture and be attracted to a magnet array when arriving in an observation well. Such an attraction of incoming iron nanoparticles by the magnet can provide quantitative information for locating the position of the tracer inlet. A series of field experiments were conducted in two wells in fractured rock at a hydrogeological research station in Taiwan, to test the cross-hole migration of the nano-iron tracer through permeable connected fractures. The fluid conductivity recorded in the observation well confirmed the arrival of the injected nano-iron slurry. All of the iron nanoparticles attracted to the magnet array in the observation well were found at the depth of a permeable fracture zone delineated by the flowmeter. This study has demonstrated that integrating the nano-iron tracer test with flowmeter measurement has the potential to characterize preferential flow paths in fractured rock.

Methodology for quantitative rapid multi-tracer PET tumor characterizations.

PubMed

Kadrmas, Dan J; Hoffman, John M

2013-10-04

Positron emission tomography (PET) can image a wide variety of functional and physiological parameters in vivo using different radiotracers. As more is learned about the molecular basis for disease and treatment, the potential value of molecular imaging for characterizing and monitoring disease status has increased. Characterizing multiple aspects of tumor physiology by imaging multiple PET tracers in a single patient provides additional complementary information, and there is a significant body of literature supporting the potential value of multi-tracer PET imaging in oncology. However, imaging multiple PET tracers in a single patient presents a number of challenges. A number of techniques are under development for rapidly imaging multiple PET tracers in a single scan, where signal-recovery processing algorithms are employed to recover various imaging endpoints for each tracer. Dynamic imaging is generally used with tracer injections staggered in time, and kinetic constraints are utilized to estimate each tracers' contribution to the multi-tracer imaging signal. This article summarizes past and ongoing work in multi-tracer PET tumor imaging, and then organizes and describes the main algorithmic approaches for achieving multi-tracer PET signal-recovery. While significant advances have been made, the complexity of the approach necessitates protocol design, optimization, and testing for each particular tracer combination and application. Rapid multi-tracer PET techniques have great potential for both research and clinical cancer imaging applications, and continued research in this area is warranted.

Methodology for Quantitative Rapid Multi-Tracer PET Tumor Characterizations

PubMed Central

Kadrmas, Dan J.; Hoffman, John M.

2013-01-01

Positron emission tomography (PET) can image a wide variety of functional and physiological parameters in vivo using different radiotracers. As more is learned about the molecular basis for disease and treatment, the potential value of molecular imaging for characterizing and monitoring disease status has increased. Characterizing multiple aspects of tumor physiology by imaging multiple PET tracers in a single patient provides additional complementary information, and there is a significant body of literature supporting the potential value of multi-tracer PET imaging in oncology. However, imaging multiple PET tracers in a single patient presents a number of challenges. A number of techniques are under development for rapidly imaging multiple PET tracers in a single scan, where signal-recovery processing algorithms are employed to recover various imaging endpoints for each tracer. Dynamic imaging is generally used with tracer injections staggered in time, and kinetic constraints are utilized to estimate each tracers' contribution to the multi-tracer imaging signal. This article summarizes past and ongoing work in multi-tracer PET tumor imaging, and then organizes and describes the main algorithmic approaches for achieving multi-tracer PET signal-recovery. While significant advances have been made, the complexity of the approach necessitates protocol design, optimization, and testing for each particular tracer combination and application. Rapid multi-tracer PET techniques have great potential for both research and clinical cancer imaging applications, and continued research in this area is warranted. PMID:24312149

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

Karingithi, C.W.

Tracer and injection tests were performed in the Olkaria North East Field with the objective to reduce uncertainty in the engineering design and to determine the suitability of well OW-704 as a re-injection well for the waste brine from the steam field during production. An organic dye (sodium fluorescein) was injected into well OW-704 as a slug. The tracer returns were observed in well OW-M2 which is 580 m deep, 620 m from well OW-704 and well OW-716 which is 900 m from well OW-704. The other wells on discharge, OW-714, and OW-725 did not show any tracer returns. However,more » other chemical constituents suggested., that well OW-716 experienced a chemical breakthrough earlier than OW-M2. Tracer return velocities of 0.31 m/hr and 1.3 m/hr were observed. Results of the tracer and injection tests indicate that OW-704 may be used as a re-injection well provided a close monitoring program is put in place.« less

System Validation Experiments for Obtaining Tracer Laser-Induced Fluorescence Data at Elevated Pressure and Temperature.

PubMed

Hartwig, Jason; Mittal, Gaurav; Kumar, Kamal; Sung, Chih-Jen

2018-04-01

This paper presents a set of system validation experiments that can be used to qualify either static or flow experimental systems for gathering tracer photophysical data or conducting laser diagnostics at high pressure and temperature in order to establish design and operation limits and reduce uncertainty in data interpretation. Tests demonstrated here quantify the effect of tracer absorption at the test cell walls, stratification, photolysis, pyrolysis, adequacy of mixing and seeding, and reabsorption of laser light using acetone as the tracer and 282 nm excitation. Results show that acetone exhibits a 10% decrease in fluorescence signal over 36 000 shots at 127.4 mJ/cm 2 , and photolysis is negligible below 1000 shots collected. Meanwhile, appropriately chosen gas residence times can mitigate risks due to pyrolysis and inadequate mixing and seeding; for the current work 100 ms residence time ensured <0.5% alteration of tracer number density due to thermal destruction. Experimental results here are compared to theoretical values from the literature.

Short-term fluid, heat, and solute transport in deep 'georeservoirs' likely to become 'EGS': some challenges to ICDP hydrogeologists who might like using artificial tracers

NASA Astrophysics Data System (ADS)

Ghergut, Julia; Behrens, Horst; Huenges, Ernst; Rose, Peter; Sauter, Martin

2014-05-01

During Fall 2013, the Integrated Continental Scientific Drilling Programme (ICDP) set out to define a new Science Plan that shall replace its past-decade version (Harms et al., eds., 2005) for the decade to come. Geoscientists worldwide were welcomed to suggest new imaging and exploration methods, new sites to drill, new challenges to be addressed with a view at new 'societal needs' (Harms and Wiersberg 2013). Save for two outstanding exceptions at the Mutnovsky volcano in Russia and the KTB site in Germany, the use of artificial tracers, especially within forced-gradient tests, has not been on the agenda of most ICDP projects so far (other than for purposes of monitoring microbial contamination in conjunction with drilling activities); deep-reservoir exploration and characterization efforts were restrained to non-fluid-invasive techniques on the one hand, and to sites featuring some unique earth-historical traits, on the other hand. Surely, this was not for lack of interest in quantifying fluid transport in the deep subsurface in general, but mainly due to operational, technical, and financial constraints (lack of resources / lack of opportunity for significant fluid turnover within the target, deep-seated georeservoirs, and fear of persistent, large-scale georeservoir contamination by non-pristine fluids). - This is likely to change during the forthcoming decade(s), owing to worldwide increased interest in some 'georesource' or 'georeservoir' play types (Moeck 2013) that have not been in the ICDP focus so far, including non-volcanogenic geothermal, and allowing for man-made design and intervention into how those 'georesources' or 'georeservoirs' shall work for us. Among the latter, petrothermal systems (Jung 2013, Huenges and Jung 2004) acquire growing recognition as a promising (and maybe unique) option for baseload energy supply in vast areas of the Northern hemisphere, at very low emissions and (in the long run) moderate costs. With petrothermal coming into play, forced-gradient turnover of significant fluid amounts shall be on the agenda, and with it also a more comprehensive use of artificial tracers, for far more ambitious tasks than just the monitoring of drilling-related contamination. Since any ICDP project is likely to start (and mostly also end) with not more than one deep well, single-well forced-gradient test experience gained within the non-ICDP areas of hydrocarbon and geothermal exploration and engineering seem predestined for a specific knowledge transfer. Single-well 'push-then-pull' (SW) tracer methods appear as attractive for a number of reasons: less uncertainty of design and dimensioning, and lower tracer quantities required, than for inter-well (IW) tests; stronger tracer signals, enabling easier and cheaper metering, and shorter metering duration required, reaching higher tracer mass recovery, than in IW tests; last not least: no need for a second well! However, SW tracer signal inversion faces a major issue: the 'push-then-pull' design weakens the correlation between tracer residence time distribution (RTD) and fluid transport parameters, inducing insensitivity or ambiguity of tracer signal inversion against some of those georeservoir parameters that are supposed to be the target of tracer tests par excellence: pore velocity, transport-effective porosity, fracture aperture and spacing or density (where applicable), fluid/solid or fluid/fluid phase interface density. Hydraulic and geophysical methods cannot measure the transport-effective values of such parameters, because the signals they detect correlate neither with fluid motion, nor with material fluxes through (fluid-rock, or fluid-fluid) phase interfaces. Typically, pressure signals obtained in hydraulic tests do not enable to distinguish between geological formations with equal permeability, but different transport-effective porosity, nor between formations with equal permeability, equal transport-effective porosity, but different fluid-rock interface area. The ability to measure this latter parameter is crucial to lifetime predictability for geothermal, gas storage, waste disposal, or hydrocarbon reservoirs (especially in advanced depletion stages). From IW tracer signals, fluid RTD can be derived, whose statistical moments relate to major hydrogeological properties of target georeservoirs. By contrast, SW tests can be used to quantify processes other than advection-dispersion: typically, the exchange of some extensive quantity (mass, energy) between fluid and solid/fluid phases by matrix diffusion or sorption/partitioning, whose rate or amount depends on the phase saturation and/or interface area density. Flow-field reversal during the 'pull' stage of a SW test is supposed to largely compensate the effects of flow path heterogeneity, and to enhance the effects of tracer exchange processes at phase interfaces. However, it always destroys the equivalence between fluid RT and reservoir size; transport-effective porosities, closely relating to fluid RT, can only be measured reliably by means of conservative-tracer IW tests. The SW inability to determine porosity also (indirectly) impedes the SW-based ability to determine those complementary, non-advective parameters: increased sensitivity comes along with increased ambiguity. Reactive tracers can aid overcoming some of the limitations to parameter determinability associated with the SW design. Specific use of reactive tracers has first been made by Tomich et al. (1973), for a SW-based measurement of residual-oil saturation in (depleted) oil reservoirs; later on by Robinson (1985), for tracking temperature fronts in laboratory-scale geothermal-reservoir IW-test 'analogues'; more recently by Schaffer et al. (2013), for tracking brine-(sc)CO2 interfaces during CO2 injection within CCS research projects. The paper discusses some lessons derived from a twelve-year experience using artificial tracers in various IW and SW field tests in Germany, aimed at deep-georeservoir characterization and/or short- to mid-term process monitoring during reservoir operation: - if those tests have been successful to a certain extent, it was primarily owing to ascertainedly conservative tracer transport behavior; - if those tests have been of limited success, it was because of lack of reactive tracer species with well-defined, and reasonable properties (reasonable means: sensitive to 'something', but not to 'everything' that may 'happen' within the target georeservoir). If the artificial-tracer-based quantification of deep-georeservoir hydrogeology and of induced (short- to mid-term) transport processes therein is to become a task for some future ICDP projects, they will need to effectively address this dilemma. Further, if EGS, and especially the petrothermal type shall be on the agenda, then SW tests will be 'unavoidable'. Finally, if the most is to be made out of a SW test, then tailored reactive tracer pairs (Tomich et al. 1973, Ghergut et al. 2013) are a must: not just reactive, not just retarded, but: conservative alongside with reactive, and with contrasting retardation behavior between product and reactant. Selected references: Harms U, Koeberl C, Zoback M, eds (2005) Continental Scientific Drilling: A Decade of Progress, and Challenges for the Future. Springer, 366 pp. Harms U, Wiersberg T (2013) Conference on ICDP's New Science Plan. Scientific Drilling, 15: 77. Huenges E, Jung R (2004) Technologies for the Utilisation of Enhanced Geothermal Systems (www.bgr.de/ veransta/renewables_2004/presentations_DGP/Block1Introduction_pdf/2_Huenges_Jung.pdf) Jung R (2013) EGS - Goodbye or Back to the Future. Chapter 5, dx.doi.org/10.5772/56458 (www.intechopen.com/ books/effective-and-sustainable-hydraulic-fracturing) Moeck I (2013) Classification of geothermal plays according to geological habitats. IGA Academy Report 0101-2013 (www.geothermal-energy.org/iga_service_gmbh/projects/ifc_project/workshop_izmir.html) Robinson B A (1985) Non-reactive and chemically reactive tracers: Theory and applications. Ph D Thesis, MIT, Cambridge, MA, 551 pp. Rose P, Mella M, Kasteler C, Johnson S (2004) The estimation of reservoir pore volume from tracer data. Procs 29th Workshop on Geothermal Reservoir Engineering, Stanford University, SGP-TR-175 (pangea.stanford.edu/ERE/pdf/IGAstandard/SGW/2004/Rose.pdf) Schaffer M, Maier F, Licha T, Sauter M (2013) A new generation of tracers for the characterization of interfacial areas during supercritical carbon dioxide injections into deep saline aquifers: kinetic interface-sensitive (KIS) tracers. Intl J Greenhouse Gas Control, 14: 200-208. Tomich J F, Dalton R L Jr, Deans H A, Shallenberger L K (1973) Single-Well Tracer Method to Measure Residual Oil Saturation. J Petrol Technol Transact, 255: 211-218. Ghergut I, Behrens H, Sauter M (2013) Can Peclet numbers depend on tracer species? going beyond SW test insensitivity to advection or equilibrium exchange. Procs 38th Workshop on Geothermal Reservoir Engineering, Stanford University, SGP-TR-198 (pangea.stanford.edu/ERE/pdf/IGAstandard/SGW/2013/Ghergut5.pdf) Acknowledgements: The Göttingen group gratefully acknowledges financial support (to developing tracer SW methods for petrothermal-reservoir testing) from Baker Hughes (Celle) and the Lower-Saxonian Government within the interdisciplinary research project 'gebo' ('Geothermal Energy and High-Performance Drilling').

Estimation of time-variable fast flow path chemical concentrations for application in tracer-based hydrograph separation analyses

USGS Publications Warehouse

Kronholm, Scott C.; Capel, Paul D.

2016-01-01

Mixing models are a commonly used method for hydrograph separation, but can be hindered by the subjective choice of the end-member tracer concentrations. This work tests a new variant of mixing model that uses high-frequency measures of two tracers and streamflow to separate total streamflow into water from slowflow and fastflow sources. The ratio between the concentrations of the two tracers is used to create a time-variable estimate of the concentration of each tracer in the fastflow end-member. Multiple synthetic data sets, and data from two hydrologically diverse streams, are used to test the performance and limitations of the new model (two-tracer ratio-based mixing model: TRaMM). When applied to the synthetic streams under many different scenarios, the TRaMM produces results that were reasonable approximations of the actual values of fastflow discharge (±0.1% of maximum fastflow) and fastflow tracer concentrations (±9.5% and ±16% of maximum fastflow nitrate concentration and specific conductance, respectively). With real stream data, the TRaMM produces high-frequency estimates of slowflow and fastflow discharge that align with expectations for each stream based on their respective hydrologic settings. The use of two tracers with the TRaMM provides an innovative and objective approach for estimating high-frequency fastflow concentrations and contributions of fastflow water to the stream. This provides useful information for tracking chemical movement to streams and allows for better selection and implementation of water quality management strategies.

Thermal single-well injection-withdrawal tracer tests for determining fracture-matrix heat transfer area

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

Pruess, K.; Doughty, C.

2010-01-15

Single-well injection-withdrawal (SWIW) tracer tests involve injection of traced fluid and subsequent tracer recovery from the same well, usually with some quiescent time between the injection and withdrawal periods. SWIW are insensitive to variations in advective processes that arise from formation heterogeneities, because upon withdrawal, fluid parcels tend to retrace the paths taken during injection. However, SWIW are sensitive to diffusive processes, such as diffusive exchange of conservative or reactive solutes between fractures and rock matrix. This paper focuses on SWIW tests in which temperature itself is used as a tracer. Numerical simulations demonstrate the sensitivity of temperature returns tomore » fracture-matrix interaction. We consider thermal SWIW response to the two primary reservoir improvements targeted with stimulation, (1) making additional fractures accessible to injected fluids, and (2) increasing the aperture and permeability of pre-existing fractures. It is found that temperature returns in SWIW tests are insensitive to (2), while providing a strong signal of more rapid temperature recovery during the withdrawal phase for (1).« less

Comparison of different tracers for PIV measurements in EHD airflow

NASA Astrophysics Data System (ADS)

Hamdi, M.; Havet, M.; Rouaud, O.; Tarlet, D.

2014-04-01

In this study, a proposed method for selecting a tracer for particle imaging velocimetry (PIV) measurement in electrohydrodynamics flows was developed. To begin with, several published studies were identified that exploit different tracers, such as oil smoke, cigarette smoke and titanium dioxide (TiO2). An assortment of tracers was then selected based on comparisons with conventional dimensionless numbers; Stokes number ( St), Archimedes number ( Ar) and electrical mobility ratio ( M). Subsequently, an experimental study for testing tracers was developed, which enabled the velocity profile of an ionic wind generated by a needle/ring configuration to be measured. Air velocity measurements carried out with a Pitot tube, considered as the reference measurements, were compared to PIV measurements for each tracer. In addition, the current-voltage curves and the evolution of the current during seeding were measured. All the experimental results show that TiO2, SiO2 microballoons and incense smoke are the ideal tracers in the series of tracers investigated.

Determination of stream reaeration coefficients by use of tracers

USGS Publications Warehouse

Kilpatrick, F.A.; Rathbun, R.E.; Yotsukura, N.; Parker, G.W.; DeLong, L.L.

1987-01-01

Stream reaeration is the physical absorption of oxygen from the atmosphere by a flowing stream. This is the primary process by which a stream replenishes the oxygen consumed in the biodegradation of organic wastes.Prior to 1965, reaeration rate coefficients could be estimated only by indirect methods. In 1965, a direct method of measuring stream reaeration coefficients was developed in which a radioactive tracer gas was injected into a stream--the tracer gas being desorbed from the stream inversely to how oxygen would be absorbed. The technique has since been modified by substituting hydrocarbon gases for the radioactive tracer gas.This manual describes the slug-injection and constant-rate injection methods of performing gas-tracer desorption measurements. Emphasis is on the use of rhodamine WT dye as a relatively conservative tracer and propane as the nonconservative gas tracer, on planning field tests, methods of injection, sampling and analysis, and computational techniques to compute desorption and reaeration coefficients.

Qualification of oil-based tracer particles for heated Ludwieg tubes

NASA Astrophysics Data System (ADS)

Casper, Marcus; Stephan, Sören; Scholz, Peter; Radespiel, Rolf

2014-06-01

The generation, insertion, pressurization and use of oil-based tracer particles is qualified for the application in heated flow facilities, typically hypersonic facilities such as Ludwieg tubes. The operative challenges are to ensure a sub-critical amount of seeding material in the heated part, to qualify the methods that are used to generate the seeding, pressurize it to storage tube pressure, as well as to test specific oil types. The mass of the seeding material is held below the lower explosion limit such that operation is safe. The basis for the tracers is qualified in off-situ particle size measurements. In the main part different methods and operational procedures are tested with respect to their ability to generate a suitable amount of seeding in the test section. For the best method the relaxation time of the tracers is qualified by the oblique shock wave test. The results show that the use of a special temperature resistant lubricant oil "Plantfluid" is feasible under the conditions of a Mach-6 Ludwieg tube with heated storage tube. The method gives high-quality tracers with high seeding densities. Although the experimental results of the oblique shock wave test differ from theoretical predictions of relaxation time, still the relaxation time of 3.2 μs under the more dense tunnel conditions with 18 bar storage tube pressure is low enough to allow the use of the seeding for meaningful particle image velocimetry studies.

Rocuronium Bromide Inhibits Inflammation and Pain by Suppressing Nitric Oxide Production and Enhancing Prostaglandin E2 Synthesis in Endothelial Cells.

PubMed

Baek, Sang Bin; Shin, Mal Soon; Han, Jin Hee; Moon, Sang Woong; Chang, Boksoon; Jeon, Jung Won; Yi, Jae Woo; Chung, Jun Young

2016-12-01

Rocuronium bromide is a nondepolarizing neuromuscular blocking drug and has been used as an adjunct for relaxation or paralysis of the skeletal muscles, facilitation of endotracheal intubation, and improving surgical conditions during general anesthesia. However, intravenous injection of rocuronium bromide induces injection pain or withdrawal movement. The exact mechanism of rocuronium bromide-induced injection pain or withdrawal movement is not yet understood. We investigated whether rocuronium bromide treatment is involved in the induction of inflammation and pain in vascular endothelial cells. For this study, calf pulmonary artery endothelial (CPAE) cells were used, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, Western blot, nitric oxide detection, and prostaglandin E 2 immunoassay were conducted. Rocuronium bromide treatment inhibited endothelial nitric oxide synthase and suppressed nitric oxide production in CPAE cells. Rocuronium bromide activated cyclooxygenase-2, inducible nitric oxide synthase and increased prostaglandin E 2 synthesis in CPAE cells. Rocuronium bromide induced inflammation and pain in CPAE cells. Suppressing nitric oxide production and enhancing prostaglandin E 2 synthesis might be associated with rocuronium bromide-induced injection pain or withdrawal movement.

Power Plant Bromide Discharges and Downstream Drinking Water Systems in Pennsylvania.

PubMed

Good, Kelly D; VanBriesen, Jeanne M

2017-10-17

Coal-fired power plants equipped with wet flue gas desulfurization (FGD) systems have been implicated in increasing bromide levels and subsequent increases in disinfection byproducts at downstream drinking water plants. Bromide was not included as a regulated constituent in the recent steam electric effluent limitations guidelines and standards (ELGs) since the U.S. EPA analysis suggested few drinking water facilities would be affected by bromide discharges from power plants. The present analysis uses a watershed approach to identify Pennsylvania drinking water intakes downstream of wet FGD discharges and to assess the potential for bromide discharge effects. Twenty-two (22) public drinking water systems serving 2.5 million people were identified as being downstream of at least one wet FGD discharge. During mean August conditions (generally low-flow, minimal dilution) in receiving rivers, the median predicted bromide concentrations contributed by wet FGD at Pennsylvania intake locations ranged from 5.2 to 62 μg/L for the Base scenario (including only natural bromide in coal) and from 16 to 190 μg/L for the Bromide Addition scenario (natural plus added bromide for mercury control); ranges depend on bromide loads and receiving stream dilution capacity.

Results of ground-water tracer tests using tritiated water at Oak Ridge National Laboratory, Tennessee

USGS Publications Warehouse

Webster, D.A.

1996-01-01

Ground-water tracer test were conducted at two sites in the radioactive-waste disposal area of Oak Ridge National Laboratory from 1977 to 1982. The purpose of the tests was to determine if the regolith beds had weathered sufficiently to permit the substantial flow of water across them. About 50 curies of tritium dissolved in water were used as the tracer in one site, and about 100 curies at the other. Results demonstrated that ground water is able to flow through joints in the weathered bedding and that the direction of the water-table gradient is the primary factor governint flow direction. Nevertheless, the substantial lateral spread of the plume as it developed showed that bedding-plane openings can still exert a significant secondary influence on flow direction in weathered rock. About 3,500 water samples from the injection and observation wells were analyzed for tritium during the test period. Concentrations detected spanned 11 orders of magnitude. Measurable concentrations were still present in the two injection wells and most observation wells 5 years after the tracer was introduced. Matrix diffusion may have played a significant role in these tests. The process would account for the sustained concentrations of tritium at many of the observation wells, the long-term residual concentrations at the injection and observation wells, and the apparent slow movement of the centers of mass across the two well fields. The process also would have implications regarding aquifer remediation. Other tracer tests have been conducted in the regolith of the Conasauga Group. Results differ from the results described in this report.

Fractional flow in fractured chalk; a flow and tracer test revisited.

PubMed

Odling, N E; West, L J; Hartmann, S; Kilpatrick, A

2013-04-01

A multi-borehole pumping and tracer test in fractured chalk is revisited and reinterpreted in the light of fractional flow. Pumping test data analyzed using a fractional flow model gives sub-spherical flow dimensions of 2.2-2.4 which are interpreted as due to the partially penetrating nature of the pumped borehole. The fractional flow model offers greater versatility than classical methods for interpreting pumping tests in fractured aquifers but its use has been hampered because the hydraulic parameters derived are hard to interpret. A method is developed to convert apparent transmissivity and storativity (L(4-n)/T and S(2-n)) to conventional transmissivity and storativity (L2/T and dimensionless) for the case where flow dimension, 2

Assessment of local hydraulic properties from electrical resistivity tomography monitoring of a three-dimensional synthetic tracer test experiment

NASA Astrophysics Data System (ADS)

Camporese, M.; Cassiani, G.; Deiana, R.; Salandin, P.

2011-12-01

In recent years geophysical methods have become increasingly popular for hydrological applications. Time-lapse electrical resistivity tomography (ERT) represents a potentially powerful tool for subsurface solute transport characterization since a full picture of the spatiotemporal evolution of the process can be obtained. However, the quantitative interpretation of tracer tests is difficult because of the uncertainty related to the geoelectrical inversion, the constitutive models linking geophysical and hydrological quantities, and the a priori unknown heterogeneous properties of natural formations. Here an approach based on the Lagrangian formulation of transport and the ensemble Kalman filter (EnKF) data assimilation technique is applied to assess the spatial distribution of hydraulic conductivity K by incorporating time-lapse cross-hole ERT data. Electrical data consist of three-dimensional cross-hole ERT images generated for a synthetic tracer test in a heterogeneous aquifer. Under the assumption that the solute spreads as a passive tracer, for high Peclet numbers the spatial moments of the evolving plume are dominated by the spatial distribution of the hydraulic conductivity. The assimilation of the electrical conductivity 4D images allows updating of the hydrological state as well as the spatial distribution of K. Thus, delineation of the tracer plume and estimation of the local aquifer heterogeneity can be achieved at the same time by means of this interpretation of time-lapse electrical images from tracer tests. We assess the impact on the performance of the hydrological inversion of (i) the uncertainty inherently affecting ERT inversions in terms of tracer concentration and (ii) the choice of the prior statistics of K. Our findings show that realistic ERT images can be integrated into a hydrological model even within an uncoupled inverse modeling framework. The reconstruction of the hydraulic conductivity spatial distribution is satisfactory in the portion of the domain directly covered by the passage of the tracer. Aside from the issues commonly affecting inverse models, the proposed approach is subject to the problem of the filter inbreeding and the retrieval performance is sensitive to the choice of K prior geostatistical parameters.

An analytical model for solute transport in an infiltration tracer test in soil with a shallow groundwater table

NASA Astrophysics Data System (ADS)

Liang, Ching-Ping; Hsu, Shao-Yiu; Chen, Jui-Sheng

2016-09-01

It is recommended that an in-situ infiltration tracer test is considered for simultaneously determining the longitudinal and transverse dispersion coefficients in soil. Analytical solutions have been derived for two-dimensional advective-dispersive transport in a radial geometry in the literature which can be used for interpreting the result of such a tracer test. However, these solutions were developed for a transport domain with an unbounded-radial extent and an infinite thickness of vadose zone which might not be realistically manifested in the actual solute transport during a field infiltration tracer test. Especially, the assumption of infinite thickness of vadose zone should be invalid for infiltration tracer tests conducted in soil with a shallow groundwater table. This paper describes an analytical model for interpreting the results of an infiltration tracer test based on improving the transport domain with a bounded-radial extent and a finite thickness of vadose zone. The analytical model is obtained with the successive application of appropriate integral transforms and their corresponding inverse transforms. A comparison of the newly derived analytical solution against the previous analytical solutions in which two distinct sets of radial extent and thickness of vadose zone are considered is conducted to determine the influence of the radial and exit boundary conditions on the solute transport. The results shows that both the radial and exit boundary conditions substantially affect the trailing segment of the breakthrough curves for a soil medium with large dispersion coefficients. Previous solutions derived for a transport domain with an unbounded-radial and an infinite thickness of vadose zone boundary conditions give lower concentration predictions compared with the proposed solution at late times. Moreover, the differences between two solutions are amplified when the observation positions are near the groundwater table. In addition, we compare our solution against the approximate solutions that derived from the previous analytical solution and has been suggested to serve as fast tools for simultaneously estimating the longitudinal and transverse dispersion coefficients. The results indicate that the approximate solutions offer predictions that are markedly distinct from our solution for the entire range of dispersion coefficient values. Thus, it is not appropriate to use the approximate solution for interpreting the results of an infiltration tracer test.

TRAC, a collaborative computer tool for tracer-test interpretation

NASA Astrophysics Data System (ADS)

Gutierrez, A.; Klinka, T.; Thiéry, D.; Buscarlet, E.; Binet, S.; Jozja, N.; Défarge, C.; Leclerc, B.; Fécamp, C.; Ahumada, Y.; Elsass, J.

2013-05-01

Artificial tracer tests are widely used by consulting engineers for demonstrating water circulation, proving the existence of leakage, or estimating groundwater velocity. However, the interpretation of such tests is often very basic, with the result that decision makers and professionals commonly face unreliable results through hasty and empirical interpretation. There is thus an increasing need for a reliable interpretation tool, compatible with the latest operating systems and available in several languages. BRGM, the French Geological Survey, has developed a project together with hydrogeologists from various other organizations to build software assembling several analytical solutions in order to comply with various field contexts. This computer program, called TRAC, is very light and simple, allowing the user to add his own analytical solution if the formula is not yet included. It aims at collaborative improvement by sharing the tool and the solutions. TRAC can be used for interpreting data recovered from a tracer test as well as for simulating the transport of a tracer in the saturated zone (for the time being). Calibration of a site operation is based on considering the hydrodynamic and hydrodispersive features of groundwater flow as well as the amount, nature and injection mode of the artificial tracer. The software is available in French, English and Spanish, and the latest version can be downloaded from the web site http://trac.brgm.fr">http://trac.brgm.fr.

Evaluation of nitrous oxide as a substitute for sulfur hexafluoride to reduce global warming impacts of ANSI/HPS N13.1 gaseous uniformity testing

NASA Astrophysics Data System (ADS)

Yu, Xiao-Ying; Barnett, J. Matthew; Amidan, Brett G.; Recknagle, Kurtis P.; Flaherty, Julia E.; Antonio, Ernest J.; Glissmeyer, John A.

2018-03-01

The ANSI/HPS N13.1-2011 standard requires gaseous tracer uniformity testing for sampling associated with stacks used in radioactive air emissions. Sulfur hexafluoride (SF6), a greenhouse gas with a high global warming potential, has long been the gas tracer used in such testing. To reduce the impact of gas tracer tests on the environment, nitrous oxide (N2O) was evaluated as a potential replacement to SF6. The physical evaluation included the development of a test plan to record percent coefficient of variance and the percent maximum deviation between the two gases while considering variables such as fan configuration, injection position, and flow rate. Statistical power was calculated to determine how many sample sets were needed, and computational fluid dynamic modeling was utilized to estimate overall mixing in stacks. Results show there are no significant differences between the behaviors of the two gases, and SF6 modeling corroborated N2O test results. Although, in principle, all tracer gases should behave in an identical manner for measuring mixing within a stack, the series of physical tests guided by statistics was performed to demonstrate the equivalence of N2O testing to SF6 testing in the context of stack qualification tests. The results demonstrate that N2O is a viable choice leading to a four times reduction in global warming impacts for future similar compliance driven testing.

Repeated tracer tests in a karst system with concentrated allogenic recharge (Johnsbachtal, Austria)

NASA Astrophysics Data System (ADS)

Birk, Steffen; Wagner, Thomas; Pauritsch, Marcus; Winkler, Gerfried

2015-04-01

The Johnsbachtal (Austria) is a high Alpine headwater catchment covering an area of approximately 65 km², which is equipped with a hydrometeorological monitoring network (Strasser at al. 2013). The catchment is composed of carbonate rocks and crystalline rocks belonging to the Northern Calceraous Alps and the Greywacke Zone. The largest spring within the catchment, the Etzbach spring, is bound on karstified carbonate rocks of the Greywacke Zone. A stream sink located at a distance of approximately 1 km from the spring was used as injection point for repeated tracer tests in the years 2012, 2013, and 2014. In each case the tracer was recovered at the spring indicating an allogenic recharge component from the crystalline parts of the catchment. The spring discharge at the times of the three tracer tests varied between approximately 0.3 and 0.6 m³/s. Likewise the tracer travel times and thus the flow velocities were found to be different. Surprisingly, the largest tracer travel time (and thus lowest flow velocity) was obtained in 2013 when the spring discharge was highest (0.6 m³/s). In addition, the flow velocities in 2012 and 2014 were found to be clearly different, although the spring discharge was similar (roughly 0.3 m³/s) in both tests. Thus, the tracer velocity appears to be not correlated with the spring discharge. Field observations indicate that this finding can potentially be attributed to complexities at both the injection location (e.g., plugging of injection points and thus different flow paths) and the sampling point (i.e., the spring, which is composed of several outlet points representing different subcatchments). References: Strasser, U., Marke, T., Sass, O., Birk, S., Winkler, G. (2013): John's creek valley: a mountainous catchment for long-term interdisciplinary human-environment system research in Upper Styria (Austria). Environmental Earth Sciences, doi: 10.1007/s12665-013-2318-y

Corrosion Problems in Absorption Chillers

ERIC Educational Resources Information Center

Stetson, Bruce

1978-01-01

Absorption chillers use a lithium bromide solution as the medium of absorption and water as the refrigerant. Discussed are corrosion and related problems, tests and remedies, and cleaning procedures. (Author/MLF)

Application of separable parameter space techniques to multi-tracer PET compartment modeling.

PubMed

Zhang, Jeff L; Michael Morey, A; Kadrmas, Dan J

2016-02-07

Multi-tracer positron emission tomography (PET) can image two or more tracers in a single scan, characterizing multiple aspects of biological functions to provide new insights into many diseases. The technique uses dynamic imaging, resulting in time-activity curves that contain contributions from each tracer present. The process of separating and recovering separate images and/or imaging measures for each tracer requires the application of kinetic constraints, which are most commonly applied by fitting parallel compartment models for all tracers. Such multi-tracer compartment modeling presents challenging nonlinear fits in multiple dimensions. This work extends separable parameter space kinetic modeling techniques, previously developed for fitting single-tracer compartment models, to fitting multi-tracer compartment models. The multi-tracer compartment model solution equations were reformulated to maximally separate the linear and nonlinear aspects of the fitting problem, and separable least-squares techniques were applied to effectively reduce the dimensionality of the nonlinear fit. The benefits of the approach are then explored through a number of illustrative examples, including characterization of separable parameter space multi-tracer objective functions and demonstration of exhaustive search fits which guarantee the true global minimum to within arbitrary search precision. Iterative gradient-descent algorithms using Levenberg-Marquardt were also tested, demonstrating improved fitting speed and robustness as compared to corresponding fits using conventional model formulations. The proposed technique overcomes many of the challenges in fitting simultaneous multi-tracer PET compartment models.

Application of separable parameter space techniques to multi-tracer PET compartment modeling

NASA Astrophysics Data System (ADS)

Zhang, Jeff L.; Morey, A. Michael; Kadrmas, Dan J.

2016-02-01

Multi-tracer positron emission tomography (PET) can image two or more tracers in a single scan, characterizing multiple aspects of biological functions to provide new insights into many diseases. The technique uses dynamic imaging, resulting in time-activity curves that contain contributions from each tracer present. The process of separating and recovering separate images and/or imaging measures for each tracer requires the application of kinetic constraints, which are most commonly applied by fitting parallel compartment models for all tracers. Such multi-tracer compartment modeling presents challenging nonlinear fits in multiple dimensions. This work extends separable parameter space kinetic modeling techniques, previously developed for fitting single-tracer compartment models, to fitting multi-tracer compartment models. The multi-tracer compartment model solution equations were reformulated to maximally separate the linear and nonlinear aspects of the fitting problem, and separable least-squares techniques were applied to effectively reduce the dimensionality of the nonlinear fit. The benefits of the approach are then explored through a number of illustrative examples, including characterization of separable parameter space multi-tracer objective functions and demonstration of exhaustive search fits which guarantee the true global minimum to within arbitrary search precision. Iterative gradient-descent algorithms using Levenberg-Marquardt were also tested, demonstrating improved fitting speed and robustness as compared to corresponding fits using conventional model formulations. The proposed technique overcomes many of the challenges in fitting simultaneous multi-tracer PET compartment models.

Effects of aquatic exercises in a rat model of brainstem demyelination with ethidium bromide on the beam walking test.

PubMed

Nassar, Cíntia Cristina Souza; Bondan, Eduardo Fernandes; Alouche, Sandra Regina

2009-09-01

Multiple sclerosis is a demyelinating disease of the central nervous system associated with varied levels of disability. The impact of early physiotherapeutic interventions in the disease progression is unknown. We used an experimental model of demyelination with the gliotoxic agent ethidium bromide and early aquatic exercises to evaluate the motor performance of the animals. We quantified the number of footsteps and errors during the beam walking test. The demyelinated animals walked fewer steps with a greater number of errors than the control group. The demyelinated animals that performed aquatic exercises presented a better motor performance than those that did not exercise. Therefore aquatic exercising was beneficial to the motor performance of rats in this experimental model of demyelination.

Growth and characterization of Cadmium Thiosemicarbazide Bromide crystals for antibacterial and nonlinear optical applications

NASA Astrophysics Data System (ADS)

Thomas Joseph Prakash, J.; Martin Sam Gnanaraj, J.

2015-01-01

Semiorganic nonlinear optical crystals of Cadmium Thiosemicarbazide Bromide was grown by slow evaporation solution growth technique. The unit cell parameters were estimated by subjecting the crystals to single crystal X-ray diffraction. The grown crystals were subjected to Powder X-ray diffraction for analyzing the crystalline nature of the sample. FTIR studies reveal the functional groups and the optical characters were analyzed by UV-Vis spectral studies. Mechanical stability of the sample was assessed by Vicker's micro hardness test. The presence of surface dislocations was identified by chemical etching technique. Antibacterial study was carried out against ACDP declared harmful pathogens. SHG efficiency of CTSB crystal was tested using Nd: YAG laser and it was found to be ∼1.8 times that of potassium dihydrogen phosphate.

Development and characterization of food-grade tracers for the global grain tracing and recall system.

PubMed

Lee, Kyung-Min; Armstrong, Paul R; Thomasson, J Alex; Sui, Ruixiu; Casada, Mark; Herrman, Timothy J

2010-10-27

Tracing grain from the farm to its final processing destination as it moves through multiple grain-handling systems, storage bins, and bulk carriers presents numerous challenges to existing record-keeping systems. This study examines the suitability of coded caplets to trace grain, in particular, to evaluate methodology to test tracers' ability to withstand the rigors of a commercial grain handling and storage systems as defined by physical properties using measurement technology commonly applied to assess grain hardness and end-use properties. Three types of tracers to dispense into bulk grains for tracing the grain back to its field of origin were developed using three food-grade substances [processed sugar, pregelatinized starch, and silicified microcrystalline cellulose (SMCC)] as a major component in formulations. Due to a different functionality of formulations, the manufacturing process conditions varied for each tracer type, resulting in unique variations in surface roughness, weight, dimensions, and physical and spectroscopic properties before and after coating. The applied two types of coating [pregelatinized starch and hydroxypropylmethylcellulose (HPMC)] using an aqueous coating system containing appropriate plasticizers showed uniform coverage and clear coating. Coating appeared to act as a barrier against moisture penetration, to protect against mechanical damage of the surface of the tracers, and to improve the mechanical strength of tracers. The results of analysis of variance (ANOVA) tests showed the type of tracer, coating material, conditioning time, and a theoretical weight gain significantly influenced the morphological and physical properties of tracers. Optimization of these factors needs to be pursued to produce desirable tracers with consistent quality and performance when they flow with bulk grains throughout the grain marketing channels.

The distribution of bromide in water in the Floridan aquifer system, Duval County, northeastern Florida

USGS Publications Warehouse

German, E.R.; Taylor, G.F.

1995-01-01

Although Duval County, Florida, has ample ground-water resources for public supply, the potential exists for a problem with excessive disinfectant by-products. These disinfectant by-products result from the treatment of raw water containing low concentrations of bromide and naturally occurring organic compounds. Because of this potential problem, the relation of bromide concentrations to aquifer tapped, well location and depth, and chemical characteristics of water in the Floridan aquifer system underlying Duval County were studied to determine if these relations could be applied to delineate water with low-bromide concentrations for future supplies. In 1992, water samples from 106 wells that tap the Floridan aquifer system were analyzed for bromide and major dissolved constituents. A comparison of bromide concentrations from the 1992 sampling with data from earlier studies (1979-80) indicates that higher bromide concentrations were detected during the earlier studies. The difference between the old and new data is probably because of a change in analytical methodology in the analysis of samples. Bromide concentrations exceeded the detection limit (0.10 milligrams per liter) in water from 28 of the 106 wells (26 percent) sampled in 1992. The maximum concentration was 0.56 milligrams per liter. There were no relations between bromide and major dissolved constituents, well depth, or aquifer tapped that would be useful for determining bromide concentrations. Areal patterns of bromide occurrence are not clearly defined, but areas with relatively high bromide concentrations tend to be located in a triangular area near the community of Sunbeam, Florida, and along the St. Johns River throughout Duval County.

A comparison between tracer gas and aerosol particles distribution indoors: The impact of ventilation rate, interaction of airflows, and presence of objects.

PubMed

Bivolarova, M; Ondráček, J; Melikov, A; Ždímal, V

2017-11-01

The study investigated the separate and combined effects of ventilation rate, free convection flow produced by a thermal manikin, and the presence of objects on the distribution of tracer gas and particles in indoor air. The concentration of aerosol particles and tracer gas was measured in a test room with mixing ventilation. Three layouts were arranged: an empty room, an office room with an occupant sitting in front of a table, and a single-bed hospital room. The room occupant was simulated by a thermal manikin. Monodisperse particles of three sizes (0.07, 0.7, and 3.5 μm) and nitrous oxide tracer gas were generated simultaneously at the same location in the room. The particles and gas concentrations were measured in the bulk room air, in the breathing zone of the manikin, and in the exhaust air. Within the breathing zone of the sitting occupant, the tracer gas emerged as reliable predictor for the exposure to all different-sized test particles. A change in the ventilation rate did not affect the difference in concentration distribution between tracer gas and larger particle sizes. Increasing the room surface area did not influence the similarity in the dispersion of the aerosol particles and the tracer gas. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Development and Field Test of an Audit Tool and Tracer Methodology for Clinician Assessment of Quality in End-of-Life Care.

PubMed

Bookbinder, Marilyn; Hugodot, Amandine; Freeman, Katherine; Homel, Peter; Santiago, Elisabeth; Riggs, Alexa; Gavin, Maggie; Chu, Alice; Brady, Ellen; Lesage, Pauline; Portenoy, Russell K

2018-02-01

Quality improvement in end-of-life care generally acquires data from charts or caregivers. "Tracer" methodology, which assesses real-time information from multiple sources, may provide complementary information. The objective of this study was to develop a valid brief audit tool that can guide assessment and rate care when used in a clinician tracer to evaluate the quality of care for the dying patient. To identify items for a brief audit tool, 248 items were created to evaluate overall quality, quality in specific content areas (e.g., symptom management), and specific practices. Collected into three instruments, these items were used to interview professional caregivers and evaluate the charts of hospitalized patients who died. Evidence that this information could be validly captured using a small number of items was obtained through factor analyses, canonical correlations, and group comparisons. A nurse manager field tested tracer methodology using candidate items to evaluate the care provided to other patients who died. The survey of 145 deaths provided chart data and data from 445 interviews (26 physicians, 108 nurses, 18 social workers, and nine chaplains). The analyses yielded evidence of construct validity for a small number of items, demonstrating significant correlations between these items and content areas identified as latent variables in factor analyses. Criterion validity was suggested by significant differences in the ratings on these items between the palliative care unit and other units. The field test evaluated 127 deaths, demonstrated the feasibility of tracer methodology, and informed reworking of the candidate items into the 14-item Tracer EoLC v1. The Tracer EoLC v1 can be used with tracer methodology to guide the assessment and rate the quality of end-of-life care. Copyright © 2017 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.

Fracture characterization in a deep geothermal reservoir

NASA Astrophysics Data System (ADS)

Rühaak, Wolfram; Hehn, Vera; Hassanzadegan, Alireza; Tischner, Torsten

2017-04-01

At the geothermal research drilling Horstberg in North West Germany studies for the characterization of a vertical fracture are performed. The fracture was created by a massive hydraulic stimulation in 2003 in approx. 3700 m depth within rocks of the middle Buntsandstein. The fracture surface is in the order of 100,000 m2, depending on the flow rate at which water is injected. Besides hydraulic characterization, multiple tracer tests are planned. At the depth of interest the reservoir temperature is around 150 °C, pressure is around 600 bar (60 MPa) and due to salinity the water density is around 1200 kg/m3. Knowledge of tracer stability and behavior at these reservoir conditions is limited. Additionally, the planned tracer tests will be performed within one single borehole. In a closed cycle water is injected into the inner pipe of the well (tubing), which is separated by a permanent packer from the outer pipe (annulus). The water is produced back from the annulus approximately 150 m above the injection point. Thus, the circulation of thermal water between two sandstone layers via an artificial fracture can be achieved. Tests will be carried out with different flow rates and accordingly with different pressures, resulting in different fracture areas. Due to this test setup tracer signals will be stacked and will remain for a longer time in the fracture - which is the reason why different tracers are required. For an optimal characterization both conservative and reactive tracers will be used and different injection methods (continuous, instantaneous and pulsed) will be applied. For a proper setup of the tracer test numerical modelling studies are performed in advance. The relevant thermal, hydraulic and chemical processes (mainly adsorption and degredation) are coupled, resulting in a THC model; additionally the dependence of fracture aperture and area on fluid pressure has to be considered. Instead of applying a mechanically coupled model (THMC) a simplified approach is applied which takes the pressure dependence of the fracture permeability into account by using constitutive relations. Results of this modeling study will be presented together with details of the planned field study.

Virus fate and transport during artificial recharge with recycled water

USGS Publications Warehouse

Anders, Robert; Chrysikopoulos, C.V.

2005-01-01

A field‐scale experiment was conducted at a research site using bacterial viruses (bacteriophage) MS2 and PRD1 as surrogates for human viruses, bromide as a conservative tracer, and tertiary‐treated municipal wastewater (recycled water) to investigate the fate and transport of viruses during artificial recharge. Observed virus concentrations were fitted using a mathematical model that simulates virus transport in one‐dimensional, homogeneous, water‐saturated porous media accounting for virus sorption (or filtration), virus inactivation, and time‐dependent source concentration. The fitted time‐dependent clogging rate constants were used to estimate the collision efficiencies for bacteriophage MS2 and PRD1 during vertical fully saturated flow. Furthermore, the corresponding time‐dependent collision efficiencies for both bacteriophage asymptotically reached similar values at the various sampling locations. These results can be used to develop an optimal management scenario to maximize the amount of recycled water that can be applied to the spreading grounds while still maintaining favorable attachment conditions for virus removal.

On the use of flow-storage repartitions derived from artificial tracer tests for geothermal reservoir characterization in the Malm-Molasse basin: a theoretical study

NASA Astrophysics Data System (ADS)

Dewi, Dina Silvia; Osaigbovo Enomayo, Augustine; Mohsin, Rizwan; Karmakar, Shyamal; Ghergut, Julia; Sauter, Martin

2016-04-01

Flow-storage repartition (FSR) analysis (Shook 2003) is a versatile tool for characterizing subsurface flow and transport systems. FSR can be derived from measured signals of inter-well tracer tests, if certain requirements are met - basically, the same as required for equivalence between fluid residence time distribution (RTD) and a measured inter-well tracer signal (pre-processed and de-convolved if necessary). Nominally, a FSR is derived from a RTD as a trajectory in normalized {1st, 0th}-order statistical moment space; more intuitively, as a parametric plot of 0th-order against 1st-order statistical moments of RTD truncated at time t, with t as a parameter running from the first tracer input to the latest available tracer sampling; 0th-order moments being normalized by the total tracer recovery, and 1st-order moments by the mean RT. Fracture-dominated systems plot in the upper left (high F , low S) region of FSR diagrams; a homogeneous single-continuum with no dispersion (infinite Peclet number) displays a straight line from {F ,S}={0,0} to {F ,S}={1,1}. This analysis tool appears particularly attractive for characterizing markedly-heterogeneous, porous-fissured-fractured (partly karstified) formations like those targeted by geothermal exploration in the Malm-Molasse basin in Southern Germany, and especially for quantifying flow and transport contributions from contrasting facies types ('reef' versus 'bedded'). However, tracer tests conducted in such systems with inter-well distances of some hundreds of metres (as required by economic considerations on geothermal reservoir sizing) face the problem of very long residence times - and thus the need to deal with incomplete (truncated) signals. For the geothermal well triplet at the Sauerlach site near Munich, tracer peak arrival times exceeding 2 years have been predicted, and signal tails decreasing by less than 50% over >10 years, which puts great uncertainty on the (extrapolation-based) normalizing factors needed to calculate FSR. Looking at the Sauerlach example, we find that premature interruption of tracer sampling systematically leads to overestimating the reservoir's storage capacity and underestimating its flow capacity, with misestimation generally increasing as the bedded/reef interfacial area per volume is increased. It is interesting to correlate these findings with the tracer-based approach to facies identification for the shallower Malm aquifers of the Southern Franconian Alb, proposed by Seiler et al. (1989, 1995) and with expectations from the direct (i. e., distributed-parameter) modeling of matrix-diffusive effects (Maloszewski and Zuber 1985) on measured tracer signals. References: Maloszewski P, Zuber A (1985) On the theory of tracer experiments in fissured rocks with a porous matrix, Journal of Hydrology, 79, 333-358 Seiler K-P, Behrens H, Wolf M (1995) Use of artificial and environmental tracers to study storage and drainage of groundwater in the Franconian Alb, Germany, and the consequences for groundwater protection, Proc Isotopes in Water Resources Management, 2, 135-146 (IAEA, Vienna) Seiler K-P, Maloszewski P, Behrens H (1989) Hydrodynamic dispersion in karstified limestones and dolomites in the Upper Jurassic of the Franconian Alb, FRG, Journal of Hydrology, 108, 235-247 Shook G M (2003) A Simple, Fast Method of Estimating Fractured Reservoir Geometry from Tracer Tests, Geothermal Resources Council Transactions, 27, 407-411 Financial support from the German Federal Ministry for Economic Affairs and Energy is gratefully acknowledged. - Gefördert durch BMWi aufgrund eines Beschlusses des Deutschen Bundestages (FKZ 0325515 "TRENDS").

Determination of the Isotopic Enrichment of 13C- and 2H-Labeled Tracers of Glucose Using High-Resolution Mass Spectrometry: Application to Dual- and Triple-Tracer Studies.

PubMed

Trötzmüller, Martin; Triebl, Alexander; Ajsic, Amra; Hartler, Jürgen; Köfeler, Harald; Regittnig, Werner

2017-11-21

Multiple-tracer approaches for investigating glucose metabolism in humans usually involve the administration of stable and radioactive glucose tracers and the subsequent determination of tracer enrichments in sampled blood. When using conventional, low-resolution mass spectrometry (LRMS), the number of spectral interferences rises rapidly with the number of stable tracers employed. Thus, in LRMS, both computational effort and statistical uncertainties associated with the correction for spectral interferences limit the number of stable tracers that can be simultaneously employed (usually two). Here we show that these limitations can be overcome by applying high-resolution mass spectrometry (HRMS). The HRMS method presented is based on the use of an Orbitrap mass spectrometer operated at a mass resolution of 100 000 to allow electrospray-generated ions of the deprotonated glucose molecules to be monitored at their exact masses. The tracer enrichment determination in blood plasma is demonstrated for several triple combinations of 13 C- and 2 H-labeled glucose tracers (e.g., [1- 2 H 1 ]-, [6,6- 2 H 2 ]-, [1,6- 13 C 2 ]glucose). For each combination it is shown that ions arising from 2 H-labeled tracers are completely differentiated from those arising from 13 C-labeled tracers, thereby allowing the enrichment of a tracer to be simply calculated from the observed ion intensities using a standard curve with curve parameters unaffected by the presence of other tracers. For each tracer, the HRMS method exhibits low limits of detection and good repeatability in the tested 0.1-15.0% enrichment range. Additionally, due to short sample preparation and analysis times, the method is well-suited for high-throughput determination of multiple glucose tracer enrichments in plasma samples.

Analysis of Conservative Tracer Tests in the Bullfrog, Tram, and Prow Pass Tuffs, 1996 to 1998, Yucca Mountain, Nye County, Nevada

USGS Publications Warehouse

Umari, Amjad; Fahy, Michael F.; Earle, John D.; Tucci, Patrick

2008-01-01

To evaluate the potential for transport of radionuclides in ground water from the proposed high-level nuclear-waste repository at Yucca Mountain, Nevada, conservative (nonsorbing) tracer tests were conducted among three boreholes, known as the C-hole Complex, and values for transport (or flow) porosity, storage (or matrix) porosity, longitudinal dispersivity, and the extent of matrix diffusion were obtained. The C-holes are completed in a sequence of Miocene tuffaceous rock, consisting of nonwelded to densely welded ash-flow tuff with intervals of ash-fall tuff and volcaniclastic rocks, covered by Quaternary alluvium. The lower part of the tuffaceous-rock sequence includes the Prow Pass, Bullfrog, and Tram Tuffs of the Crater Flat Group. The rocks are pervaded by tectonic and cooling fractures. Paleozoic limestone and dolomite underlie the tuffaceous rocks. Four radially convergent and one partially recirculating conservative (nonsorbing) tracer tests were conducted at the C-hole Complex from 1996 to 1998 to establish values for flow porosity, storage porosity, longitudinal dispersivity, and extent of matrix diffusion in the Bullfrog and Tram Tuffs and the Prow Pass Tuff. Tracer tests included (1) injection of iodide into the combined Bullfrog-Tram interval; (2) injection of 2,6 difluorobenzoic acid into the Lower Bullfrog interval; (3) injection of 3-carbamoyl-2-pyridone into the Lower Bullfrog interval; and (4) injection of iodide and 2,4,5 trifluorobenzoic acid, followed by 2,3,4,5 tetrafluorobenzoic acid, into the Prow Pass Tuff. All tracer tests were analyzed by the Moench single- and dual-porosity analytical solutions to the advection-dispersion equation or by superposition of these solutions. Nonlinear regression techniques were used to corroborate tracer solution results, to obtain optimal parameter values from the solutions, and to quantify parameter uncertainty resulting from analyzing two of the three radially convergent conservative tracer tests conducted in the Bullfrog and Tram intervals. Longitudinal dispersivity values in the Bullfrog and Tram Tuffs ranged from 1.83 to 2.6 meters, flow-porosity values from 0.072 to 0.099, and matrix-porosity values from 0.088 to 0.19. The flow-porosity values indicate that the pathways between boreholes UE-25 c#2 and UE-25 c#3 in the Bullfrog and Tram intervals are not connected well. Tracer testing in the Prow Pass interval indicates different transport characteristics than those obtained in the Bullfrog and Tram intervals. In the Prow Pass Tuff, longitudinal dispersivity was 0.27 meter, flow porosity was 4.5 ? 10?4, and matrix porosity was 0.01. This indicates that the flow network in the Prow Pass is dominated by interconnected fractures, whereas in the Bullfrog and Tram, the flow network is dominated by discontinuous fractures with connecting segments of matrix.

Probability density function of non-reactive solute concentration in heterogeneous porous formations.

PubMed

Bellin, Alberto; Tonina, Daniele

2007-10-30

Available models of solute transport in heterogeneous formations lack in providing complete characterization of the predicted concentration. This is a serious drawback especially in risk analysis where confidence intervals and probability of exceeding threshold values are required. Our contribution to fill this gap of knowledge is a probability distribution model for the local concentration of conservative tracers migrating in heterogeneous aquifers. Our model accounts for dilution, mechanical mixing within the sampling volume and spreading due to formation heterogeneity. It is developed by modeling local concentration dynamics with an Ito Stochastic Differential Equation (SDE) that under the hypothesis of statistical stationarity leads to the Beta probability distribution function (pdf) for the solute concentration. This model shows large flexibility in capturing the smoothing effect of the sampling volume and the associated reduction of the probability of exceeding large concentrations. Furthermore, it is fully characterized by the first two moments of the solute concentration, and these are the same pieces of information required for standard geostatistical techniques employing Normal or Log-Normal distributions. Additionally, we show that in the absence of pore-scale dispersion and for point concentrations the pdf model converges to the binary distribution of [Dagan, G., 1982. Stochastic modeling of groundwater flow by unconditional and conditional probabilities, 2, The solute transport. Water Resour. Res. 18 (4), 835-848.], while it approaches the Normal distribution for sampling volumes much larger than the characteristic scale of the aquifer heterogeneity. Furthermore, we demonstrate that the same model with the spatial moments replacing the statistical moments can be applied to estimate the proportion of the plume volume where solute concentrations are above or below critical thresholds. Application of this model to point and vertically averaged bromide concentrations from the first Cape Cod tracer test and to a set of numerical simulations confirms the above findings and for the first time it shows the superiority of the Beta model to both Normal and Log-Normal models in interpreting field data. Furthermore, we show that assuming a-priori that local concentrations are normally or log-normally distributed may result in a severe underestimate of the probability of exceeding large concentrations.

Solute transport characterization in karst aquifers by tracer injection tests for a sustainable water resource management

NASA Astrophysics Data System (ADS)

Morales, T.; Angulo, B.; Uriarte, J. A.; Olazar, M.; Arandes, J. M.; Antiguedad, I.

2017-04-01

Protection of water resources is a major challenge today, given that territory occupation and land use are continuously increasing. In the case of karst aquifers, its dynamic complexity requires the use of specific methodologies that allow establishing local and regional flow and transport patterns. This information is particularly necessary when springs and wells harnessed for water supply are concerned. In view of the present state of the art, this work shows a new approach based on the use of a LiCl based tracer injection test through a borehole for transport characterization from a local to a regional scale. Thus a long term tracer injection test was conducted in a particularly sensitive sector of the Egino karst massif (Basque Country, Spain). The initial displacement of tracer in the vicinity of the injection was monitored in a second borehole at a radial distance of 10.24 m. This first information, assessed by a radial divergent model, allows obtaining transport characteristic parameters in this immediate vicinity during injection. At a larger (regional) scale, the tracer reaches a highly transmissive network with mean traveling velocities to the main springs being from 4.3 to 13.7 m/h. The responses obtained, particularly clear in the main spring used for water supply, and the persistence of part of the tracer in the injection zone, pose reconsidering the need for their protection. Thus, although the test allows establishing the 24-h isochrone, which is the ceiling value in present European vulnerability approaches, the results obtained advise widening the zone to protect in order to guarantee water quality in the springs. Overall, this stimulus-response test allows furthering the knowledge on the dynamics of solute transport in karst aquifers and is a particularly useful tool in studies related to source vulnerability and protection in such a complex medium.

Determination of stream reaeration coefficients by use of tracers

USGS Publications Warehouse

Kilpatrick, F.A.; Rathbun, R.E.; Yotsukura, Nobuhiro; Parker, G.W.; DeLong, L.L.

1989-01-01

Stream reaeration is the physical absorption of oxygen from the atmosphere by a flowing stream. This is the primary process by which a stream replenishes the oxygen consumed in the biodegradation of organic wastes. Prior to 1965, reaeration rate coefficients could be estimated only by indirect methods. In 1965, a direct method of measuring stream reaeration coefficients was developed whereby a radioactive tracer gas was injected into a stream-the principle being that the tracer gas would be desorbed from the stream inversely to how oxygen would be absorbed. The technique has since been modified by substituting hydrocarbon gases for the radioactive tracer gas. This manual describes the slug-injection and constant-rate-injection methods of measuring gas-tracer desorption. Emphasis is on the use of rhodamine WT dye as a relatively conservative tracer and propane as the nonconservative gas tracer, on planning field tests, on methods of injection, sampling, and analysis, and on techniques for computing desorption and reaeration coefficients.

Freeze core sampling to validate time-lapse resistivity monitoring of the hyporheic zone.

PubMed

Toran, Laura; Hughes, Brian; Nyquist, Jonathan; Ryan, Robert

2013-01-01

A freeze core sampler was used to characterize hyporheic zone storage during a stream tracer test. The pore water from the frozen core showed tracer lingered in the hyporheic zone after the tracer had returned to background concentration in collocated well samples. These results confirmed evidence of lingering subsurface tracer seen in time-lapse electrical resistivity tomographs. The pore water exhibited brine exclusion (ion concentrations in ice lower than source water) in a sediment matrix, despite the fast freezing time. Although freeze core sampling provided qualitative evidence of lingering tracer, it proved difficult to quantify tracer concentration because the amount of brine exclusion during freezing could not be accurately determined. Nonetheless, the additional evidence for lingering tracer supports using time-lapse resistivity to detect regions of low fluid mobility within the hyporheic zone that can act as chemically reactive zones of importance in stream health. © 2012, The Author(s). GroundWater © 2012, National Ground Water Association.

Application of separable parameter space techniques to multi-tracer PET compartment modeling

PubMed Central

Zhang, Jeff L; Morey, A Michael; Kadrmas, Dan J

2016-01-01

Multi-tracer positron emission tomography (PET) can image two or more tracers in a single scan, characterizing multiple aspects of biological functions to provide new insights into many diseases. The technique uses dynamic imaging, resulting in time-activity curves that contain contributions from each tracer present. The process of separating and recovering separate images and/or imaging measures for each tracer requires the application of kinetic constraints, which are most commonly applied by fitting parallel compartment models for all tracers. Such multi-tracer compartment modeling presents challenging nonlinear fits in multiple dimensions. This work extends separable parameter space kinetic modeling techniques, previously developed for fitting single-tracer compartment models, to fitting multi-tracer compartment models. The multi-tracer compartment model solution equations were reformulated to maximally separate the linear and nonlinear aspects of the fitting problem, and separable least-squares techniques were applied to effectively reduce the dimensionality of the nonlinear fit. The benefits of the approach are then explored through a number of illustrative examples, including characterization of separable parameter space multi-tracer objective functions and demonstration of exhaustive search fits which guarantee the true global minimum to within arbitrary search precision. Iterative gradient-descent algorithms using Levenberg–Marquardt were also tested, demonstrating improved fitting speed and robustness as compared to corresponding fits using conventional model formulations. The proposed technique overcomes many of the challenges in fitting simultaneous multi-tracer PET compartment models. PMID:26788888

Global Visualization in Water using AnodizedAluminum PressureSensitive Paint and Dissolved Oxygen as Tracer

NASA Astrophysics Data System (ADS)

Ozaki, Tatsuya; Ishikawa, Hitoshi; Sakaue, Hirotaka

2009-11-01

We have developed anodized-aluminum pressuresensitive paint (AA-PSP) for flow visualization in water using dissolved oxygen as a tracer. Developed AA-PSP is characterized using water calibration setup by controlling a dissolved oxygen concentration. It is shown that the developed AA-PSP gives 4.0 percent change in luminescence per 1 mg/l of oxygen concentration. This AA-PSP is applied to visualize flows in a water tunnel. Oxygen concentrations of the water tunnel and the dissolved oxygen are 9.5 mg/l and 20 mg/l, respectively. We can capture horseshoe vortices over the base of 10 mm cylinder by using this technique at Reynolds number of 1000 and a water speed of 100 mm/s, respectively. Unlike conventional tracers such as ink, milk, and fluorescent dyes, this visualization technique gives flow information on the AA-PSP coated surface without integrating flows between the AA-PSP and an optical detector. Because of using dissolved oxygen as a tracer, it holds the material properties of testing water except for the amount of oxygen. The tracer does not interfere with optical measurements and it does not contaminate the testing water. A conventional visualization technique using milk as a tracer is also employed for comparison.

VAPOR-PHASE TRANSPORT OF TRICHLOROETHENE IN AN INTERMEDIATE-SCALE VADOSE-ZONE SYSTEM: RETENTION PROCESSES AND TRACER-BASED PREDICTION

PubMed Central

Costanza-Robinson, Molly S.; Carlson, Tyson D.; Brusseau, Mark L.

2013-01-01

Gas-phase miscible-displacement experiments were conducted using a large weighing lysimeter to evaluate retention processes for volatile organic compounds (VOCs) in water-unsaturated (vadoze-zone) systems, and to test the utility of gas-phase tracers for predicting VOC retardation. Trichloroethene (TCE) served as a model VOC, while trichlorofluoromethane (CFM) and heptane were used as partitioning tracers to independently characterize retention by water and the air-water interface, respectively. Retardation factors for TCE ranged between 1.9 and 3.5, depending on water content. The results indicate that dissolution into the bulk water was the primary retention mechanism for TCE under all conditions studied, contributing approximately two thirds of the total measured retention. Accumulation at the air-water interface comprised a significant fraction of the observed retention for all experiments, with an average contribution of approximately 24%. Sorption to the solid phase contributed approximately 10% to retention. Water contents and air-water interfacial areas estimated based on the CFM and heptane tracer data, respectively, were similar to independently measured values. Retardation factors for TCE predicted using the partitioning-tracer data were in reasonable agreement with the measured values. These results suggest that gas-phase tracer tests hold promise for characterizing the retention and transport of VOCs in the vadose-zone. PMID:23333418

Case study: Minimization of corrosion using activated sodium bromide in a medium-size cooling tower

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

Nalepa, C.J.; Moore, R.M.; Golson, G.L.

1996-10-01

The process loop cooling tower at the Albemarle Process Development Center in Baton Rouge, LA has historically used chlorine as the biocide together with industry accepted phosphorus-based corrosion/scale inhibitors. Although this regimen provided biocontrol, sludge and iron build-up was a recurring problem, especially in low-velocity, small cross-sectional areas of piping. A general clean-up of the system was performed in April, 1995. This clean-up was followed with a switch to a two-component corrosion inhibitor/dispersant package. It was decided to study alternate biocides as well at this time. Activated sodium bromide was found to be particularly effective in this tower, which operatesmore » at pH {approximately}8.4. Relative to chlorine, the use of activated sodium bromide led to a decrease in general and pitting corrosion on mild steel while maintaining prior performance on admiralty brass. The reduced corrosion appears to be due to a combination of both chemical (less attack on passivated metal surfaces) and biological factors (better control of heterotrophic and sessile bacteria). These conclusions are supported by chemical analyses, corrosion meter and coupon data, dip slides, BART (biological activity reaction test) tests, and visual observations of the tower sump and heat exchanger surfaces.« less

Evaluation of nitrous oxide as a substitute for sulfur hexafluoride to reduce global warming impacts of ANSI/HPS N13.1 gaseous uniformity testing

DOE PAGES

Yu, Xiao-Ying; Barnett, J. Matthew; Amidan, Brett G.; ...

2017-12-12

The ANSI/HPS N13.1–2011 standard requires gaseous tracer uniformity testing for sampling associated with stacks used in radioactive air emissions. Sulfur hexafluoride (SF 6), a greenhouse gas with a high global warming potential, has long been the gas tracer used in such testing. To reduce the impact of gas tracer tests on the environment, nitrous oxide (N 2O) was evaluated as a potential replacement to SF 6. The physical evaluation included the development of a test plan to record percent coefficient of variance and the percent maximum deviation between the two gases while considering variables such as fan configuration, injection position,more » and flow rate. Statistical power was calculated to determine how many sample sets were needed, and computational fluid dynamic modeling was utilized to estimate overall mixing in stacks. Results show there are no significant differences between the behaviors of the two gases, and SF 6 modeling corroborated N 2O test results. Although, in principle, all tracer gases should behave in an identical manner for measuring mixing within a stack, the series of physical tests guided by statistics was performed to demonstrate the equivalence of N 2O testing to SF 6 testing in the context of stack qualification tests. In conclusion, the results demonstrate that N 2O is a viable choice leading to a four times reduction in global warming impacts for future similar compliance driven testing.« less

Evaluation of nitrous oxide as a substitute for sulfur hexafluoride to reduce global warming impacts of ANSI/HPS N13.1 gaseous uniformity testing

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

Yu, Xiao-Ying; Barnett, J. Matthew; Amidan, Brett G.

The ANSI/HPS N13.1–2011 standard requires gaseous tracer uniformity testing for sampling associated with stacks used in radioactive air emissions. Sulfur hexafluoride (SF 6), a greenhouse gas with a high global warming potential, has long been the gas tracer used in such testing. To reduce the impact of gas tracer tests on the environment, nitrous oxide (N 2O) was evaluated as a potential replacement to SF 6. The physical evaluation included the development of a test plan to record percent coefficient of variance and the percent maximum deviation between the two gases while considering variables such as fan configuration, injection position,more » and flow rate. Statistical power was calculated to determine how many sample sets were needed, and computational fluid dynamic modeling was utilized to estimate overall mixing in stacks. Results show there are no significant differences between the behaviors of the two gases, and SF 6 modeling corroborated N 2O test results. Although, in principle, all tracer gases should behave in an identical manner for measuring mixing within a stack, the series of physical tests guided by statistics was performed to demonstrate the equivalence of N 2O testing to SF 6 testing in the context of stack qualification tests. In conclusion, the results demonstrate that N 2O is a viable choice leading to a four times reduction in global warming impacts for future similar compliance driven testing.« less

Simulation of soluble waste transport and buildup in surface waters using tracers

USGS Publications Warehouse

Kilpatrick, F.A.

1993-01-01

Soluble tracers can be used to simulate the transport and dispersion of soluble wastes that might have been introduced or are planned for introduction into surface waters. Measured tracer-response curves produced from the injection of a known quantity of soluble tracer can be used in conjunction with the superposition principle to simulate potential waste buildup in streams, lakes, and estuaries. Such information is particularly valuable to environmental and water-resource planners in determining the effects of proposed waste discharges. The theory, techniques, analysis, and presentation of results of tracer-waste simulation tests in rivers, lakes, and estuaries are described. This manual builds on other manuals dealing with dye tracing by emphasizing the expanded use of data from time-of-travel studies.

Simulation of soluble waste transport and buildup in surface waters using tracers

USGS Publications Warehouse

Kilpatrick, Frederick A.

1992-01-01

Soluble tracers can be used to simulate the transport and dispersion of soluble wastes that might have been introduced or are planned for introduction into surface waters. Measured tracer-response curves produced from the injection of a known quantity of soluble tracer can be used in conjunction with the superposition principle to simulate potential waste buildup in streams, lakes, and estuaries. Such information is particularly valuable to environmental and water-resource planners in determining the effects of proposed waste discharges.The theory, techniques, analysis, and presentation of results of tracer-waste simulation tests in rivers, lakes, and estuaries are described. This manual builds on other manuals on dye tracing with emphasis on the expanded use of time-of-travel type data.

Production of plutonium, yttrium and strontium tracers for using in environmental research

NASA Astrophysics Data System (ADS)

Arzumanov, A.; Batischev, V.; Berdinova, N.; Borissenko, A.; Chumikov, G.; Lukashenko, S.; Lysukhin, S.; Popov, Yu.; Sychikov, G.

2001-12-01

Summary of cyclotron production methods of 237Pu (45,2 d), 88Y (106,65 d) and 85Sr (64,84 d) tracers via nuclear reactions with protons and alphas on 235U, 88Sr and 85Rb targets in wide energy range is given. Chemical methods of separation and purification of the tracers from the irradiated uranium, strontium and rubidium targets are described. The tracers were used for determination of Pu (239-240), Sr-90 and Am-241 in the samples (soil, plants, underground waters) from Semipalatinsk Test Site. Obtained results are discussed.

Land cover controls on depression-focused recharge: an example from southern Ontario

NASA Astrophysics Data System (ADS)

Buttle, J. M.; Greenwood, W. J.

2015-12-01

The Oak Ridges Moraine (ORM) is a critical hydrogeologic feature in southern Ontario. Although previous research has highlighted the implications of spatially-focused recharge in closed topographic depressions for regional groundwater resources, such depression-focused recharge (DFR) has not been empirically demonstrated on the ORM. Permeable surficial sands and gravels mantling much of the ORM imply that water fluxes will largely be vertical recharge rather than lateral downslope transfer into depressions. Nevertheless, lateral fluxes may occur in winter and spring, when concrete frost development encourages surface runoff of rainfall and snowmelt. The potential for DFR was examined under forest and agricultural land cover with similar soils and surficial geology. Soil water contents, soil temperatures and ground frost thickness were measured at the crest and base of closed depressions in two agricultural fields and two forest stands on permeable ORM outcrops. Recharge from late-fall to the end of spring snowmelt was estimated via 1-d water balances and surface-applied bromide tracing. Both forest and agricultural sites experienced soil freezing; however, greater soil water contents prior to freeze-up at the latter led to concrete soil frost development. This resulted in lateral movement of snowmelt and rainfall into topographic depressions and surface ponding, which did not occur in forest depressions. Water balance recharge exceeded estimates from the bromide tracer approach at all locations; nevertheless, both methods indicated DRF exceeded recharge at the depression crest in agricultural areas with little difference in forest areas. Water balance estimates suggest winter-spring DFR (1300 - 2000 mm) is 3-5× recharge on level agricultural sites. Differences in the potential for DFR between agricultural and forest land covers have important implications for the spatial variability of recharge fluxes and the quality of recharging water on the ORM.

Assessment of existing roadside swales with engineered filter soil: II. Treatment efficiency and in situ mobilization in soil columns.

PubMed

Ingvertsen, Simon T; Cederkvist, Karin; Jensen, Marina B; Magid, Jakob

2012-01-01

Use of roadside infiltration systems using engineered filter soil for optimized treatment has been common practice in Germany for decades, but little documentation is available regarding their long-term treatment performance. Here we present the results of laboratory leaching experiments with intact soil columns (15 cm i.d., 25-30 cm length) collected from two German roadside infiltration swales constructed in 1997. The columns were irrigated with synthetic solutions of unpolluted or polluted (dissolved heavy metals and fine suspended solids) road runoff, as well as a soluble nonreactive tracer (bromide) and a dye (brilliant blue). The experiments were performed at two irrigation rates corresponding to catchment rainfall intensities of approximately 5.1 and 34 mm/h. The bromide curves indicated that preferential flow was more pronounced at high irrigation rates, which was supported by the flow patterns revealed in the dye tracing experiment. Nonetheless, the soils seemed to be capable of retaining most of the dissolved heavy metals from the polluted road runoff at both low and high irrigation rates, except for Cr, which appears to pass through the soil as chromate. Fluorescent microspheres (diameter = 5 μm) used as surrogates for fine suspended solids were efficiently retained by the soils (>99%). However, despite promising treatment abilities, internal mobilization of heavy metals and P from the soil was observed, resulting in potentially critical effluent concentrations of Cu, Zn, and Pb. This is mainly ascribed to high concentrations of in situ mobilized dissolved organic carbon (DOC). Suggestions are provided for possible improvements and further research to minimize DOC mobilization in engineered filter soils. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Assessment of the Revised 3410 Building Filtered Exhaust Stack Sampling Probe Location

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

Yu, Xiao-Ying; Recknagle, Kurtis P.; Glissmeyer, John A.

2013-12-01

In order to support the air emissions permit for the 3410 Building, Pacific Northwest National Laboratory performed a series of tests in the exhaust air discharge from the reconfigured 3410 Building Filtered Exhaust Stack. The objective was to determine whether the location of the air sampling probe for emissions monitoring meets the applicable regulatory criteria governing such effluent monitoring systems. In particular, the capability of the air sampling probe location to meet the acceptance criteria of ANSI/HPS N13.1-2011 , Sampling and Monitoring Releases of Airborne Radioactive Substances from the Stack and Ducts of Nuclear Facilities was determined. The qualification criteriamore » for these types of stacks address 1) uniformity of air velocity, 2) sufficiently small flow angle with respect to the axis of the duct, 3) uniformity of tracer gas concentration, and 4) uniformity of tracer particle concentration. Testing was performed to conform to the quality requirements of NQA-1-2000. Fan configurations tested included all fan combinations of any two fans at a time. Most of the tests were conducted at the normal flow rate, while a small subset of tests was performed at a slightly higher flow rate achieved with the laboratory hood sashes fully open. The qualification criteria for an air monitoring probe location are taken from ANSI/HPS N13.1-2011 and are paraphrased as follows with key results summarized: 1. Angular Flow—The average air velocity angle must not deviate from the axis of the stack or duct by more than 20°. Our test results show that the mean angular flow angles at the center two-thirds of the ducts are smaller than 4.5% for all testing conditions. 2. Uniform Air Velocity—The acceptance criterion is that the COV of the air velocity must be ≤ 20% across the center two thirds of the area of the stack. Our results show that the COVs of the air velocity across the center two-thirds of the stack are smaller than 2.9% for all testing conditions. 3. Uniform Concentration of Tracer Gases—The uniformity of the concentration of potential contaminants is first tested using a tracer gas to represent gaseous effluents. The tracer is injected downstream of the fan outlets and at the junction downstream fan discharges meet. The acceptance criteria are that 1) the COV of the measured tracer gas concentration is ≤20% across the center two-thirds of the sampling plane and 2) at no point in the sampling plane does the concentration vary from the mean by >30%. Our test results show that 1) the COV of the measured tracer gas concentration is < 2.9% for all test conditions and 2) at no point in the sampling plane does the concentration vary from the mean by >6.5%. 4. Uniform Concentration of Tracer Particles—Tracer particles of 10-μm aerodynamic diameter are used for the second demonstration of concentration uniformity. The acceptance criterion is that the COV of particle concentration is ≤ 20% across the center two thirds of the sampling plane. Our test results indicate that the COV of particle concentration is <9.9% across the center two-thirds of the sampling plane among all testing conditions. Thus, the reconfigured 3410 Building Filtered Exhaust Stack was determined to meet the qualification criteria given in the ANSI/HPS N13.1-2011 standard. Changes to the system configuration or operations outside the bounds described in this report (e.g., exhaust stack velocity changes, relocation of sampling probe, and addition of fans) may require re-testing or re-evaluation to determine compliance.« less

Bioturbation, advection, and diffusion of a conserved tracer in a laboratory flume

NASA Astrophysics Data System (ADS)

Work, P. A.; Moore, P. R.; Reible, D. D.

2002-06-01

Laboratory experiments indicating the relative influences of advection, diffusion, and bioturbation on transport of NaCl tracer between a stream and streambed are described. Data were collected in a recirculating flume housing a box filled with test sediments. Peclet numbers ranged from 0 to 1.5. Sediment components included a medium sand (d50 = 0.31 mm), kaolinite, and topsoil. Lumbriculus variegatus were introduced as bioturbators. Conductivity probes were employed to document the flux of the tracer solution out of the bed. Measurements are compared to one-dimensional effective diffusion models assuming one or two horizontal sediment layers. These simple models provide a good indication of tracer half-life in the bed if a suitable effective diffusion coefficient is chosen but underpredict initial flux and overpredict flux at long times. Organism activity was limited to the upper reaches of the sediment test box but eventually exerts a secondary influence on flux from deeper regions.

A volatile tracer-assisted headspace analytical technique for determining the swelling capacity of superabsorbent polymers.

PubMed

Zhang, Shu-Xin; Jiang, Ran; Chai, Xin-Sheng

2017-09-01

This paper reports on a new method for the determination of swelling capacity of superabsorbent polymers by a volatile tracer-assisted headspace gas chromatography (HS-GC). Toluene was used as a tracer and added to the solution for polymers swelling test. Based on the differences of the tracer partitioned between the vapor and hydrogel phase before and after the polymer's swelling capacity, a transition point (corresponding to the material swelling capacity) can be observed when plotting the GC signal of toluene vs. the ratio of solution added to polymers. The present method has good precision (RSD<2.1%) and good accuracy, in which the relative deference between the data measured by the HS-GC method and the reference method were within 8.0%. The present method is very suitable to be used for testing the swelling capacity of polymers at the elevated temperatures. Copyright © 2017 Elsevier B.V. All rights reserved.

Emission quantification using the tracer gas dispersion method: The influence of instrument, tracer gas species and source simulation.

PubMed

Delre, Antonio; Mønster, Jacob; Samuelsson, Jerker; Fredenslund, Anders M; Scheutz, Charlotte

2018-09-01

The tracer gas dispersion method (TDM) is a remote sensing method used for quantifying fugitive emissions by relying on the controlled release of a tracer gas at the source, combined with concentration measurements of the tracer and target gas plumes. The TDM was tested at a wastewater treatment plant for plant-integrated methane emission quantification, using four analytical instruments simultaneously and four different tracer gases. Measurements performed using a combination of an analytical instrument and a tracer gas, with a high ratio between the tracer gas release rate and instrument precision (a high release-precision ratio), resulted in well-defined plumes with a high signal-to-noise ratio and a high methane-to-tracer gas correlation factor. Measured methane emission rates differed by up to 18% from the mean value when measurements were performed using seven different instrument and tracer gas combinations. Analytical instruments with a high detection frequency and good precision were established as the most suitable for successful TDM application. The application of an instrument with a poor precision could only to some extent be overcome by applying a higher tracer gas release rate. A sideward misplacement of the tracer gas release point of about 250m resulted in an emission rate comparable to those obtained using a tracer gas correctly simulating the methane emission. Conversely, an upwind misplacement of about 150m resulted in an emission rate overestimation of almost 50%, showing the importance of proper emission source simulation when applying the TDM. Copyright © 2018 Elsevier B.V. All rights reserved.

An Integrated Approach to Characterizing Bypassed Oil in Heterogeneous and Fractured Reservoirs Using Partitioning Tracers

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

Akhil Datta-Gupta

2006-12-31

We explore the use of efficient streamline-based simulation approaches for modeling partitioning interwell tracer tests in hydrocarbon reservoirs. Specifically, we utilize the unique features of streamline models to develop an efficient approach for interpretation and history matching of field tracer response. A critical aspect here is the underdetermined and highly ill-posed nature of the associated inverse problems. We have investigated the relative merits of the traditional history matching ('amplitude inversion') and a novel travel time inversion in terms of robustness of the method and convergence behavior of the solution. We show that the traditional amplitude inversion is orders of magnitudemore » more non-linear and the solution here is likely to get trapped in local minimum, leading to inadequate history match. The proposed travel time inversion is shown to be extremely efficient and robust for practical field applications. The streamline approach is generalized to model water injection in naturally fractured reservoirs through the use of a dual media approach. The fractures and matrix are treated as separate continua that are connected through a transfer function, as in conventional finite difference simulators for modeling fractured systems. A detailed comparison with a commercial finite difference simulator shows very good agreement. Furthermore, an examination of the scaling behavior of the computation time indicates that the streamline approach is likely to result in significant savings for large-scale field applications. We also propose a novel approach to history matching finite-difference models that combines the advantage of the streamline models with the versatility of finite-difference simulation. In our approach, we utilize the streamline-derived sensitivities to facilitate history matching during finite-difference simulation. The use of finite-difference model allows us to account for detailed process physics and compressibility effects. The approach is very fast and avoids much of the subjective judgments and time-consuming trial-and-errors associated with manual history matching. We demonstrate the power and utility of our approach using a synthetic example and two field examples. We have also explored the use of a finite difference reservoir simulator, UTCHEM, for field-scale design and optimization of partitioning interwell tracer tests. The finite-difference model allows us to include detailed physics associated with reactive tracer transport, particularly those related with transverse and cross-streamline mechanisms. We have investigated the potential use of downhole tracer samplers and also the use of natural tracers for the design of partitioning tracer tests. Finally, we discuss several alternative ways of using partitioning interwell tracer tests (PITTs) in oil fields for the calculation of oil saturation, swept pore volume and sweep efficiency, and assess the accuracy of such tests under a variety of reservoir conditions.« less

The anomaly in a breakthrough curve of a single well "push-pull" tracer test: A density driven effect?

NASA Astrophysics Data System (ADS)

Zeilfelder, Sarah; Hebig, Klaus; Ito, Narimitsu; Machida, Isao; Scheytt, Traugott; Marui, Atsunao

2013-04-01

What method is appropriate to investigate an aquifer when there is only one well available? A single well "push-pull" tracer test (PP Test) may be a suitable method in order to characterize an aquifer and to obtain information about the hydraulic and chemical properties when only one well is available for the investigations. In a PP test, a test solution that contains a known amount of solutes and a conservative tracer is injected into the aquifer ("push") and extracted afterwards ("pull"). Optionally, the test solution is flushed out of the well and the casing with untreated test solution with a so called "chaser" before being extracted. Also between the injection and the extraction phase a drifting time may be included. The breakthrough of the tracer during the extraction phase is measured and used for analyses and interpretation. In the last three years, several PP Test campaigns were conducted at two different test sites in Japan (Hebig et al. 2011, Zeilfelder et al. 2012). The aim was to investigate the applicability of the PP Test method in different geological settings and in different types of aquifers. The latest field campaign thus focussed on the question how variations of the setup are influencing the breakthrough curve of the PP Test in order to develop and enhance this method. Also the standardization of the PP Test was an aim of this study. During the campaign, a total of seven PP Tests were performed, while only single aspects of the setup were varied from test to test. The tests differed in injection and extraction rate, in the salinity of the injected test solution and in the use of a chaser solution. The general shapes of the breakthrough curves were similar and conclusions about the repeatability of the PP Test could be drawn. However, a sharp anomaly was observed in the breakthrough curve of one specific setup type. By repeating this PP test under the same boundary conditions, we were able to recreate the anomaly and could exclude any technical aspects as a source. In this version of the PP test higher salinized test solution was injected into the aquifer. There are several hypotheses that could explain the behavior of the breakthrough curves of the tracer in this test design. Of all the possibilities (like sorption processes, unexpected tracer reactions, inhomogeneities in the aquifer, influence of the well design), we assume that ion exchange processes and density driven flow are the main reasons for the repeatedly observed anomaly. References: Hebig, K.H., Ito, N., Scheytt, T.J. & Marui, A. (2011). Hydraulic and hydrochemical characterization of deep coastal sedimentary basins by single-well Push-Pull tests. GSA Annual Meeting, 9-12 October 2011, Minneapolis, USA. Zeilfelder, S., Ito, N., Marui, A., Hebig, K. & Scheytt, T. (2012). Push-Pull-Test und Tracer-Test in einem tiefen Grundwasserleiter in Kameoka, Japan. Kurzfassung in: Liedl, R., Burghardt, D., Simon, E., Reimann, T. & Kaufmann-Knoke (Hg.). Grundwasserschutz und Grundwassernutzung. Tagung der Fachsektion Hydrogeologie in der DGG (FH-DGG). 16. - 20. Mai 2012, Dresden. Kurfassungen der Vorträge und Poster. Schriftenreihe der DGG, Heft 78, S. 192.

21 CFR 522.275 - N-Butylscopolammonium bromide.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 6 2011-04-01 2011-04-01 false N-Butylscopolammonium bromide. 522.275 Section 522....275 N-Butylscopolammonium bromide. (a) Specifications. Each milliliter of solution contains 20 milligrams (mg) N-butylscopolammonium bromide. (b) Sponsor. See No. 000010 in § 510.600(c) of this chapter...

21 CFR 522.275 - N-Butylscopolammonium bromide.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false N-Butylscopolammonium bromide. 522.275 Section 522....275 N-Butylscopolammonium bromide. (a) Specifications. Each milliliter of solution contains 20 milligrams (mg) N-butylscopolammonium bromide. (b) Sponsor. See No. 000010 in § 510.600(c) of this chapter...

Physical Sciences Laboratory 1 Rooftop Stack Mixing Study

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

Flaherty, Julia E.; Antonio, Ernest J.

To address concerns about worker exposures on the Physical Science Laboratory (PSL) rooftop, a tracer study was conducted to measure gaseous tracer concentrations downwind of six stacks on the southern half of the PSL building (PSL-1). These concerns were raised, in part, due to the non-standard configuration of the stacks on this building. Five of the six stacks were only about 8 feet tall, with one shorter stack that was essentially level with the roof deck. These stacks were reconfigured in August 2016, and these exhaust points on PSL-1 are now 18 feet tall. This report describes the objectives ofmore » the tracer tests performed on PSL-1, provides an overview of how the tests were executed, and presents results of the tests. The tests on the PSL rooftop were a follow-on project from a similar study performed on the LSL-II ventilation exhaust (Flaherty and Antonio, 2016).« less

Palladium-Catalyzed Borylation of Primary Alkyl Bromides

PubMed Central

Joshi-Pangu, Amruta; Ma, Xinghua; Diane, Mohamed; Iqbal, Sidra; Kribs, Robert J.; Huang, Richard; Wang, Chao-Yuan

2012-01-01

A mild Pd-catalyzed process for the borylation of alkyl bromides has been developed using bis(pinacolato)diboron as a boron source. This process accommodates the use of a wide range of functional groups on the alkyl bromide substrate. Primary bromides react with complete selectivity in the presence of a secondary bromide. The generality of this approach is demonstrated by its extension to the use of alkyl iodides and alkyl tosylates, as well as borylation reactions employing bis(neopentyl glycolato)diboron as the boron source. PMID:22774861

Channel water balance and exchange with subsurface flow along a mountain headwater stream in Montana, United States

USGS Publications Warehouse

Payn, R.A.; Gooseff, M.N.; McGlynn, B.L.; Bencala, K.E.; Wondzell, S.M.

2009-01-01

Channel water balances of contiguous reaches along streams represent a poorly understood scale of stream-subsurface interaction. We measured reach water balances along a headwater stream in Montana, United States, during summer base flow recessions. Reach water balances were estimated from series of tracer tests in 13 consecutive reaches delineated evenly along a 2.6 km valley segment. For each reach, we estimated net change in discharge, gross hydrologic loss, and gross hydrologic gain from tracer dilution and mass recovery. Four series of tracer tests were performed during relatively high, intermediate, and low base flow conditions. The relative distribution of channel water along the stream was strongly related to a transition in valley structure, with a general increase in gross losses through the recession. During tracer tests at intermediate and low flows, there were frequent substantial losses of tracer mass (>10%) that could not be explained by net loss in flow over the reach, indicating that many of the study reaches were concurrently losing and gaining water. For example, one reach with little net change in discharge exchanged nearly 20% of upstream flow with gains and losses along the reach. These substantial bidirectional exchanges suggest that some channel interactions with subsurface flow paths were not measurable by net change in flow or transient storage of recovered tracer. Understanding bidirectional channel water balances in stream reaches along valleys is critical to an accurate assessment of stream solute fate and transport and to a full assessment of exchanges between the stream channel and surrounding subsurface.

Channel water balance and exchange with subsurface flow along a mountain headwater stream in Montana, United States

USGS Publications Warehouse

Payn, R.A.; Gooseff, M.N.; McGlynn, B.L.; Bencala, K.E.; Wondzell, S.M.

2009-01-01

Channel water balances of contiguous reaches along streams represent a poorly understood scale of stream-subsurface interaction. We measured reach water balances along a headwater stream in Montana, United States, during summer base flow recessions. Reach water balances were estimated from series of tracer tests in 13 consecutive reaches delineated evenly along a 2.6 km valley segment. For each reach, we estimated net change in discharge, gross hydrologic loss, and gross hydrologic gain from tracer dilution and mass recovery. Four series of tracer tests were performed during relatively high, intermediate, and low base flow conditions. The relative distribution of channel water along the stream was strongly related to a transition in valley structure, with a general increase in gross losses through the recession. During tracer tests at intermediate and low flows, there were frequent substantial losses of tracer mass (>10%) that could not be explained by net loss in flow over the reach, indicating that many of the study reaches were concurrently losing and gaining water. For example, one reach with little net change in discharge exchanged nearly 20% of upstream flow with gains and losses along the reach. These substantial bidirectional exchanges suggest that some channel interactions with subsurface flow paths were not measurable by net change in flow or transient storage of recovered tracer. Understanding bidirectional channel water balances in stream reaches along valleys is critical to an accurate assessment of stream solute fate and transport and to a full assessment of exchanges between the stream channel and surrounding subsurface. Copyright 2009 by the American Geophysical Union.

Physiological considerations in applying laboratory-determined buoyant densities to predictions of bacterial and protozoan transport in groundwater: Results of in-situ and laboratory tests

USGS Publications Warehouse

Harvey, R.W.; Metge, D.W.; Kinner, N.; Mayberry, N.

1997-01-01

Buoyant densities were determined for groundwater bacteria and microflagellates (protozoa) from a sandy aquifer (Cape Cod, MA) using two methods: (1) density-gradient centrifugation (DGC) and (2) Stoke's law approximations using sedimentation rates observed during natural-gradient injection and recovery tests. The dwarf (average cell size, 0.3 ??m), unattached bacteria inhabiting a pristine zone just beneath the water table and a majority (~80%) of the morphologically diverse community of free- living bacteria inhabiting a 5-km-long plume of organically-contaminated groundwater had DGC-determined buoyant densities <1.019 g/cm3 before culturing. In the aquifer, sinking rates for the uncultured 2-??m size class of contaminant plume bacteria were comparable to that of the bromide tracer (1.9 x 10-3 M), also suggesting a low buoyant density. Culturing groundwater bacteria resulted in larger (0.8-1.3 ??m), less neutrally- buoyant (1.043-1.081 g/cm3) cells with potential sedimentation rates up to 64-fold higher than those predicted for the uncultured populations. Although sedimentation generally could be neglected in predicting subsurface transport for the community of free-living groundwater bacteria, it appeared to be important for the cultured isolates, at least until they readapt to aquifer conditions. Culturing-induced alterations in size of the contaminant-plume microflagellates (2-3 ??m) were ameliorated by using a lower nutrient, acidic (pH 5) porous growth medium. Buoyant densities of the cultured microflagellates were low, i.e., 1.024-1.034 g/cm3 (using the DGC assay) and 1.017-1.039 g/cm3 (estimated from in-situ sedimentation rates), suggesting good potential for subsurface transport under favorable conditions.

Testing high resolution numerical models for analysis of contaminant storage and release from low permeability zones.

PubMed

Chapman, Steven W; Parker, Beth L; Sale, Tom C; Doner, Lee Ann

2012-08-01

It is now widely recognized that contaminant release from low permeability zones can sustain plumes long after primary sources are depleted, particularly for chlorinated solvents where regulatory limits are orders of magnitude below source concentrations. This has led to efforts to appropriately characterize sites and apply models for prediction incorporating these effects. A primary challenge is that diffusion processes are controlled by small-scale concentration gradients and capturing mass distribution in low permeability zones requires much higher resolution than commonly practiced. This paper explores validity of using numerical models (HydroGeoSphere, FEFLOW, MODFLOW/MT3DMS) in high resolution mode to simulate scenarios involving diffusion into and out of low permeability zones: 1) a laboratory tank study involving a continuous sand body with suspended clay layers which was 'loaded' with bromide and fluorescein (for visualization) tracers followed by clean water flushing, and 2) the two-layer analytical solution of Sale et al. (2008) involving a relatively simple scenario with an aquifer and underlying low permeability layer. All three models are shown to provide close agreement when adequate spatial and temporal discretization are applied to represent problem geometry, resolve flow fields and capture advective transport in the sands and diffusive transfer with low permeability layers and minimize numerical dispersion. The challenge for application at field sites then becomes appropriate site characterization to inform the models, capturing the style of the low permeability zone geometry and incorporating reasonable hydrogeologic parameters and estimates of source history, for scenario testing and more accurate prediction of plume response, leading to better site decision making. Copyright © 2012 Elsevier B.V. All rights reserved.

Indirect spectrophotometric determination of traces of bromide in water

USGS Publications Warehouse

Fishman, M. J.; Skougstad, M.W.

1963-01-01

A rapid, accurate, and sensitive indirect spectrophotometric method for the determination of bromide in natural waters is based on the catalytic effect of bromide on the oxidation of iodine to iodate by potassium permanganate in sulfuric acid solution. The method is applicable to concentrations ranging from 1 to 100 ??g. of bromide per liter, but may be modified to extend the concentration range. Most ions commonly occurring in water do not interfere. The standard deviation is 2.9 at bromide concentrations of 100 ??g. per liter and less at lower concentrations. The determination of bromide in samples containing known added amounts gave values ranging from 99 to 105% of the concentration calculated to be present.

Are single-well "push-pull" tests suitable tracer methods for aquifer characterization?

NASA Astrophysics Data System (ADS)

Hebig, Klaus; Zeilfelder, Sarah; Ito, Narimitsu; Machida, Isao; Scheytt, Traugott; Marui, Atsunao

2013-04-01

Recently, investigations were conducted for geological and hydrogeological characterisation of the sedimentary coastal basin of Horonobe (Hokkaido, Japan). Coastal areas are typical geological settings in Japan, which are less tectonically active than the mountain ranges. In Asia, and especially in Japan, these areas are often densely populated. Therefore, it is important to investigate the behaviour of solutes in such unconsolidated aquifers. In such settings sometimes only single boreholes or groundwater monitoring wells are available for aquifer testing for various reasons, e.g. depths of more than 100 m below ground level and slow groundwater velocities due to density driven flow. A standard tracer test with several involved groundwater monitoring wells is generally very difficult or even not possible at these depths. One of the most important questions in our project was how we can obtain information about chemical and hydraulic properties in such aquifers. Is it possible to characterize solute transport behaviour parameters with only one available groundwater monitoring well or borehole? A so-called "push-pull" test may be one suitable method for aquifer testing with only one available access point. In a push-pull test a known amount of several solutes including a conservative tracer is injected into the aquifer ("push") and afterwards extracted ("pull"). The measured breakthrough curve during the pumping back phase can then be analysed. This method has already been used previously with various aims, also in the recent project (e.g. Hebig et al. 2011, Zeilfelder et al. 2012). However, different test setups produced different tracer breakthrough curves. As no systematic evaluation of this aquifer tracer test method was done so far, nothing is known about its repeatability. Does the injection and extraction rate influence the shape of the breakthrough curve? Which role plays the often applied "chaser", which is used to push the test solution out from the borehole and gravel pack? How does density difference between the original groundwater and the test solution influence the tracer breakthrough curves? To solve these questions, seven push-pull tests were performed under controlled boundary conditions in the same well DD-2 (100 m depth). Only single parameters, as e.g. flow rate or salinization of the test solution, were varied during the experiments. By conducting these different test setups, conclusions could be drawn about the application of the push-pull method under different settings. References: Hebig, K.H., Ito, N., Scheytt, T.J. & Marui, A. (2011). Hydraulic and hydrochemical characterization of deep coastal sedimentary basins by single-well Push-Pull tests. GSA Annual Meeting, 9-12 October 2011, Minneapolis, USA. Zeilfelder, S., Ito, N., Marui, A., Hebig, K. & Scheytt, T. (2012). Push-Pull-Test und Tracer-Test in ei-nem tiefen Grundwasserleiter in Kameoka, Japan. Kurzfassung in: Liedl, R., Burghardt, D., Simon, E., Reimann, T. & Kaufmann-Knoke (Hg.). Grundwasserschutz und Grundwassernutzung. Tagung der Fachsektion Hydrogeologie in der DGG (FH-DGG). 16. - 20. Mai 2012, Dresden. Kurfassungen der Vorträge und Poster. Schriftenreihe der DGG, Heft 78, S. 192.

Corrosion of carbon steels, stainless steels, and titanium in aqueous lithium bromide solution

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

Guinon, J.L.; Garcia-Anton, J.; Perez-Herranz, V.

1994-03-01

Effects of lithium bromide (LiBr) concentration, pH, temperature, exposure time, and the action of some inhibitors on corrosion of several carbon (C) steels, stainless steels (SS), and a titanium (Ti) alloy were studied. Corrosion rates were determined by the polarization resistance method and compared to rates determined by weight-loss measurements. Pitting potentials (E[sub p]) were evaluated in neutral LiBr solution and with different inhibitors. Pit density and average pit depth depended on the metal tested, with lowest values for Ti, the next lowest values for type 316 SS (UNS S31600), and the highest values for UNS G41350 tempered steel.

40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with the...

40 CFR 180.519 - Bromide ion and residual bromine; tolerances for residues.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Bromide ion and residual bromine... Tolerances § 180.519 Bromide ion and residual bromine; tolerances for residues. (a) General. The food additives, bromide ion and residual bromine, may be present in water, potable in accordance with the...

Depth distribution of sulfonamide antibiotics in pore water of an undisturbed loamy grassland soil.

PubMed

Burkhardt, Michael; Stamm, Christian

2007-01-01

Despite the concern raised by the detections of veterinary antibiotics like sulfonamides (SA) in the environment, their fate in soils is still not sufficiently understood. In a previous article, we demonstrated that manure may substantially influence losses of SA via runoff from soils. Here, we report on the effect of manure on SA availability in soil pore water. Three sulfonamides (sulfadimidine, sulfadiazine, sulfathiazole) and two tracers (bromide and Brilliant Blue) were either applied in manure or as aqueous solution on grassland plots. After 1 and 3 d contact time, the plots were irrigated with deionized water. One day after irrigation, soil cores were taken and profiles of pore water concentrations were determined. The median SA concentrations of the top layer on manured plots varied between 40 and 60 microg L(-1) and between 10 and 30 microg L(-1) on the controls. For the conservative tracer Br the mass recovery was about 60 to 75% and much lower for the SA (2 to 14%). Apparent distribution coefficients K(d,app) of the SA in the topsoil ranged between 3 and 15 L kg(-1) on the manured plots and between 30 to 35 kg L(-1) on the controls. Below the top layer, the concentration distribution showed a pattern typical for preferential flow. Locally, SA concentrations down to 30- to 50-cm depth were as high as in the top 5 cm with little effect of the two application matrices. In the topmost layer, the data indicate that 10 to 25% of sulfadimidine were transformed to its acetyl-metabolite.

Design and utilisation of protocols to characterise dynamic PET uptake of two tracers using basis pursuit.

PubMed

Bell, Christopher; Puttick, Simon; Rose, Stephen; Smith, Jye; Thomas, Paul; Dowson, Nicholas

2017-06-21

Imaging using more than one biological process using PET could be of great utility, but despite previously proposed approaches to dual-tracer imaging, it is seldom performed. The alternative of performing multiple scans is often infeasible for clinical practice or even in research studies. Dual-tracer PET scanning allows for multiple PET radiotracers to be imaged within the same imaging session. In this paper we describe our approach to utilise the basis pursuit method to aid in the design of dual-tracer PET imaging experiments, and later in separation of the signals. The advantage of this approach is that it does not require a compartment model architecture to be specified or even that both signals are distinguishable in all cases. This means the method for separating dual-tracer signals can be used for many feasible and useful combinations of biology or radiotracer, once an appropriate scanning protocol has been decided upon. Following a demonstration in separating the signals from two consecutively injected radionuclides in a controlled experiment, phantom and list-mode mouse experiments demonstrated the ability to test the feasibility of dual-tracer imaging protocols for multiple injection delays. Increases in variances predicted for kinetic macro-parameters V D and K I in brain and tumoral tissue were obtained when separating the synthetically combined data. These experiments confirmed previous work using other approaches that injections delays of 10-20 min ensured increases in variance were kept minimal for the test tracers used. On this basis, an actual dual-tracer experiment using a 20 min delay was performed using these radio tracers, with the kinetic parameters (V D and K I ) extracted for each tracer in agreement with the literature. This study supports previous work that dual-tracer PET imaging can be accomplished provided certain constraints are adhered to. The utilisation of basis pursuit techniques, with its removed need to specify a model architecture, allows the feasibility of a range of imaging protocols to be investigated via simulation in a straight-forward manner for a wide range of possible scenarios. The hope is that the ease of utilising this approach during feasibility studies and in practice removes any perceived technical barrier to performing dual-tracer imaging.

Design and utilisation of protocols to characterise dynamic PET uptake of two tracers using basis pursuit

NASA Astrophysics Data System (ADS)

Bell, Christopher; Puttick, Simon; Rose, Stephen; Smith, Jye; Thomas, Paul; Dowson, Nicholas

2017-06-01

Imaging using more than one biological process using PET could be of great utility, but despite previously proposed approaches to dual-tracer imaging, it is seldom performed. The alternative of performing multiple scans is often infeasible for clinical practice or even in research studies. Dual-tracer PET scanning allows for multiple PET radiotracers to be imaged within the same imaging session. In this paper we describe our approach to utilise the basis pursuit method to aid in the design of dual-tracer PET imaging experiments, and later in separation of the signals. The advantage of this approach is that it does not require a compartment model architecture to be specified or even that both signals are distinguishable in all cases. This means the method for separating dual-tracer signals can be used for many feasible and useful combinations of biology or radiotracer, once an appropriate scanning protocol has been decided upon. Following a demonstration in separating the signals from two consecutively injected radionuclides in a controlled experiment, phantom and list-mode mouse experiments demonstrated the ability to test the feasibility of dual-tracer imaging protocols for multiple injection delays. Increases in variances predicted for kinetic macro-parameters V D and K I in brain and tumoral tissue were obtained when separating the synthetically combined data. These experiments confirmed previous work using other approaches that injections delays of 10-20 min ensured increases in variance were kept minimal for the test tracers used. On this basis, an actual dual-tracer experiment using a 20 min delay was performed using these radio tracers, with the kinetic parameters (V D and K I) extracted for each tracer in agreement with the literature. This study supports previous work that dual-tracer PET imaging can be accomplished provided certain constraints are adhered to. The utilisation of basis pursuit techniques, with its removed need to specify a model architecture, allows the feasibility of a range of imaging protocols to be investigated via simulation in a straight-forward manner for a wide range of possible scenarios. The hope is that the ease of utilising this approach during feasibility studies and in practice removes any perceived technical barrier to performing dual-tracer imaging.

100-NR-2 Apatite Treatability Test: Fall 2010 Tracer Infiltration Test (White Paper)

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

Vermeul, Vincent R.; Fritz, Brad G.; Fruchter, Jonathan S.

The primary objectives of the tracer infiltration test were to 1) determine whether field-scale hydraulic properties for the compacted roadbed materials and underlying Hanford fm. sediments comprising the zone of water table fluctuation beneath the site are consistent with estimates based laboratory-scale measurements on core samples and 2) characterize wetting front advancement and distribution of soil moisture achieved for the selected application rate. These primary objectives were met. The test successfully demonstrated that 1) the remaining 2 to 3 ft of compacted roadbed material below the infiltration gallery does not limit infiltration rates to levels that would be expected tomore » eliminate near surface application as a viable amendment delivery approach and 2) the combined aqueous and geophysical monitoring approaches employed at this site, with some operational adjustments based on lessons learned, provides an effective means of assessing wetting front advancement and the distribution of soil moisture achieved for a given solution application. Reasonably good agreement between predicted and observed tracer and moisture front advancement rates was observed. During the first tracer infiltration test, which used a solution application rate of 0.7 cm/hr, tracer arrivals were observed at the water table (10 to 12 ft below the bottom of the infiltration gallery) after approximately 5 days, for an advancement rate of approximately 2 ft/day. This advancement rate is generally consistent with pre-test modeling results that predicted tracer arrival at the water table after approximately 5 days (see Figure 8, bottom left panel). This agreement indicates that hydraulic property values specified in the model for the compacted roadbed materials and underlying Hanford formation sediments, which were based on laboratory-scale measurements, are reasonable estimates of actual field-scale conditions. Additional work is needed to develop a working relationship between resistivity change and the associated change in moisture content so that 4D images of moisture content change can be generated. Results from this field test will be available for any future Ca-citrate-PO4 amendment infiltration tests, which would be designed to evaluate the efficacy of using near surface application of amendments to form apatite mineral phases in the upper portion of the zone of water table fluctuation.« less

Laboratory longitudinal diffusion tests: 1. Dimensionless formulations and validity of simplified solutions

NASA Astrophysics Data System (ADS)

Takeda, M.; Nakajima, H.; Zhang, M.; Hiratsuka, T.

2008-04-01

To obtain reliable diffusion parameters for diffusion testing, multiple experiments should not only be cross-checked but the internal consistency of each experiment should also be verified. In the through- and in-diffusion tests with solution reservoirs, test interpretation of different phases often makes use of simplified analytical solutions. This study explores the feasibility of steady, quasi-steady, equilibrium and transient-state analyses using simplified analytical solutions with respect to (i) valid conditions for each analytical solution, (ii) potential error, and (iii) experimental time. For increased generality, a series of numerical analyses are performed using unified dimensionless parameters and the results are all related to dimensionless reservoir volume (DRV) which includes only the sorptive parameter as an unknown. This means the above factors can be investigated on the basis of the sorption properties of the testing material and/or tracer. The main findings are that steady, quasi-steady and equilibrium-state analyses are applicable when the tracer is not highly sorptive. However, quasi-steady and equilibrium-state analyses become inefficient or impractical compared to steady state analysis when the tracer is non-sorbing and material porosity is significantly low. Systematic and comprehensive reformulation of analytical models enables the comparison of experimental times between different test methods. The applicability and potential error of each test interpretation can also be studied. These can be applied in designing, performing, and interpreting diffusion experiments by deducing DRV from the available information for the target material and tracer, combined with the results of this study.

Heat and solute tracers: how do they compare in heterogeneous aquifers?

PubMed

Irvine, Dylan J; Simmons, Craig T; Werner, Adrian D; Graf, Thomas

2015-04-01

A comparison of groundwater velocity in heterogeneous aquifers estimated from hydraulic methods, heat and solute tracers was made using numerical simulations. Aquifer heterogeneity was described by geostatistical properties of the Borden, Cape Cod, North Bay, and MADE aquifers. Both heat and solute tracers displayed little systematic under- or over-estimation in velocity relative to a hydraulic control. The worst cases were under-estimates of 6.63% for solute and 2.13% for the heat tracer. Both under- and over-estimation of velocity from the heat tracer relative to the solute tracer occurred. Differences between the estimates from the tracer methods increased as the mean velocity decreased, owing to differences in rates of molecular diffusion and thermal conduction. The variance in estimated velocity using all methods increased as the variance in log-hydraulic conductivity (K) and correlation length scales increased. The variance in velocity for each scenario was remarkably small when compared to σ2 ln(K) for all methods tested. The largest variability identified was for the solute tracer where 95% of velocity estimates ranged by a factor of 19 in simulations where 95% of the K values varied by almost four orders of magnitude. For the same K-fields, this range was a factor of 11 for the heat tracer. The variance in estimated velocity was always lowest when using heat as a tracer. The study results suggest that a solute tracer will provide more understanding about the variance in velocity caused by aquifer heterogeneity and a heat tracer provides a better approximation of the mean velocity. © 2013, National Ground Water Association.

Can nanotechnology help advance glaciological research?

NASA Astrophysics Data System (ADS)

Dahlke, H. E.; McNew, C.; Wang, C.; McLaughlin, S.; Kocis, T. N.

2017-12-01

In a rapidly changing cryosphere, identifying sources, pathways, and residence times of snow and glacier meltwater is critical to developing improved understanding of watershed-stream connections and hydrological/glaciological melt models. Traditionally, glaciologists have used a variety of tracers, including chloride, microparticles, and dyes, to identify the structure and morphology of subglacial drainage systems. However, minimum detection limits, tracer expense, and the ability of watersheds to retain a memory of past tracer inputs have restricted both the scale of tracer application and the repeated or simultaneous use of most known tracers, thus limiting our ability to study complex glacial systems. These shortcomings in hydrologic tracers can be overcome by utilizing a tracer that allows for the unique identification between spatial and temporal inputs while maintaining identical transport characteristics. Here, we present the use of DNA-labeled nanoparticles, developed for nano-medicine and drug delivery, as environmental tracers. The DNA-labeled particle tracers consist of short DNA strands encapsulated within biodegradable polymer microspheres, which allow for repeatable production of numerous uniquely labelled tracers of pre-determined size and physical transport properties. Each batch of tracers are independently quantifiable; even a single DNA molecule can be detected with cost-effective quantitative polymerase chain reaction (qPCR). We have tested our tracer technology in complex systems such as valley glaciers in Sweden and Alaska and in both laboratory and field studies of channel flow, overland flow, and flow in porous media; these proof-of-concept studies indicate that nanotechnology allows for powerful characterization, description, and, ultimately, prediction of flow pathways in glacial systems and the environment.

Impact of polymer surface characteristics on the microrheological measurement quality of protein solutions - A tracer particle screening.

PubMed

Bauer, Katharina Christin; Schermeyer, Marie-Therese; Seidel, Jonathan; Hubbuch, Jürgen

2016-05-30

Microrheological measurements prove to be suitable to identify rheological parameters of biopharmaceutical solutions. These give information about the flow characteristics but also about the interactions and network structures in protein solutions. For the microrheological measurement tracer particles are required. Due to their specific surface characteristic not all are suitable for reliable measurement results in biopharmaceutical systems. In the present work a screening of melamine, PMMA, polystyrene and surface modified polystyrene as tracer particles were investigated at various protein solution conditions. The surface characteristics of the screened tracer particles were evaluated by zeta potential measurements. Furthermore each tracer particle was used to determine the dynamic viscosity of lysozyme solutions by microrheology and compared to a standard. The results indicate that the selection of the tracer particle had a strong impact on the quality of the microrheological measurement dependent on pH and additive type. Surface modified polystyrene was the only tracer particle that yielded good microrheological results for all tested conditions. The study indicated that the electrostatic surface charge of the tracer particle had a minor impact than its hydrophobicity. This characteristic was the crucial surface property that needs to be considered for the selection of a suitable tracer particle to achieve high measurement accuracy. Copyright © 2016 Elsevier B.V. All rights reserved.

Prediction of down-gradient impacts of DNAPL source depletion using tracer techniques: Laboratory and modeling validation

NASA Astrophysics Data System (ADS)

Jawitz, J. W.; Basu, N.; Chen, X.

2007-05-01

Interwell application of coupled nonreactive and reactive tracers through aquifer contaminant source zones enables quantitative characterization of aquifer heterogeneity and contaminant architecture. Parameters obtained from tracer tests are presented here in a Lagrangian framework that can be used to predict the dissolution of nonaqueous phase liquid (NAPL) contaminants. Nonreactive tracers are commonly used to provide information about travel time distributions in hydrologic systems. Reactive tracers have more recently been introduced as a tool to quantify the amount of NAPL contaminant present within the tracer swept volume. Our group has extended reactive tracer techniques to also characterize NAPL spatial distribution heterogeneity. By conceptualizing the flow field through an aquifer as a collection of streamtubes, the aquifer hydrodynamic heterogeneities may be characterized by a nonreactive tracer travel time distribution, and NAPL spatial distribution heterogeneity may be similarly described using reactive travel time distributions. The combined statistics of these distributions are used to derive a simple analytical solution for contaminant dissolution. This analytical solution, and the tracer techniques used for its parameterization, were validated both numerically and experimentally. Illustrative applications are presented from numerical simulations using the multiphase flow and transport simulator UTCHEM, and laboratory experiments of surfactant-enhanced NAPL remediation in two-dimensional flow chambers.

Effect of adsorbed metals ions on the transport of Zn- and Ni-EDTA complexes in a sand and gravel aquifer

USGS Publications Warehouse

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

2002-01-01

Adsorption, complexation, and dissolution reactions strongly influenced the transport of metal ions complexed with ethylenediaminetetraacetic acid (EDTA) in a predominantly quartz-sand aquifer during two tracer tests conducted under mildly reducing conditions at pH 5.8 to 6.1. In tracer test M89, EDTA complexes of zinc (Zn) and nickel (Ni), along with excess free EDTA, were injected such that the lower portion of the tracer cloud traveled through a region with adsorbed manganese (Mn) and the upper portion of the tracer cloud traveled through a region with adsorbed Zn. In tracer test S89, Ni- and Zn-EDTA complexes, along with excess EDTA complexed with calcium (Ca), were injected into a region with adsorbed Mn. The only discernable chemical reaction between Ni-EDTA and the sediments was a small degree of reversible adsorption leading to minor retardation. In the absence of adsorbed Zn, the injected Zn was displaced from EDTA complexes by iron(III) [Fe(III)] dissolved from the sediments. Displacement of Zn by Fe(III) on EDTA became increasingly thermodynamically favorable with decreasing total EDTA concentration. The reaction was slow compared to the time-scale of transport. Free EDTA rapidly dissolved aluminum (Al) from the sediments, which was subsequently displaced slowly by Fe. In the portion of tracer cloud M89 that traveled through the region contaminated with adsorbed Zn, little displacement of Zn complexed with EDTA was observed, and Al was rapidly displaced from EDTA by Zn desorbed from the sediments, in agreement with equilibrium calculations. In tracer test S89, desorption of Mn dominated over the more thermodynamically favorable dissolution of Al oxyhydroxides. Comparison with results from M89 suggests that dissolution of Al oxyhydroxides in coatings on these sediment grains by Ca-EDTA was rate-limited whereas that by free EDTA reached equilibrium on the time-scale of transport. Rates of desorption are much faster than rates of dissolution of Fe oxyhydroxides from sediment-grain surfaces and, therefore, adsorbed metal ions can strongly influence the speciation of ligands like EDTA in soils and sediments, especially over small temporal and spatial scales. Copyright ?? 2002 Elsevier Science Ltd.

Tracer water transport and subgrid precipitation variation within atmospheric general circulation models

NASA Astrophysics Data System (ADS)

Koster, Randal D.; Eagleson, Peter S.; Broecker, Wallace S.

1988-03-01

A capability is developed for monitoring tracer water movement in the three-dimensional Goddard Institute for Space Science Atmospheric General Circulation Model (GCM). A typical experiment with the tracer water model follows water evaporating from selected grid squares and determines where this water first returns to the Earth's surface as precipitation or condensate, thereby providing information on the lateral scales of hydrological transport in the GCM. Through a comparison of model results with observations in nature, inferences can be drawn concerning real world water transport. Tests of the tracer water model include a comparison of simulated and observed vertically-integrated vapor flux fields and simulations of atomic tritium transport from the stratosphere to the oceans. The inter-annual variability of the tracer water model results is also examined.

Tracer water transport and subgrid precipitation variation within atmospheric general circulation models

NASA Technical Reports Server (NTRS)

Koster, Randal D.; Eagleson, Peter S.; Broecker, Wallace S.

1988-01-01

A capability is developed for monitoring tracer water movement in the three-dimensional Goddard Institute for Space Science Atmospheric General Circulation Model (GCM). A typical experiment with the tracer water model follows water evaporating from selected grid squares and determines where this water first returns to the Earth's surface as precipitation or condensate, thereby providing information on the lateral scales of hydrological transport in the GCM. Through a comparison of model results with observations in nature, inferences can be drawn concerning real world water transport. Tests of the tracer water model include a comparison of simulated and observed vertically-integrated vapor flux fields and simulations of atomic tritium transport from the stratosphere to the oceans. The inter-annual variability of the tracer water model results is also examined.

What is your diagnosis? Marked hyperchloremia in a dog.

PubMed

Piperisova, Ida; Neel, Jennifer A; Papich, Mark G

2009-09-01

A 5-year-old neutered male Cavalier King Charles Spaniel was evaluated for a 3-week history of progressive paresis. The dog had been receiving potassium citrate capsules to acidify urine for the past 2 years because of an earlier history of urolithiasis. Results of neurologic examination, spinal cord radiography, and magnetic resonance imaging of the skull and spinal cord revealed no lesions that could have accounted for the neurologic signs. The main abnormalities on a clinical chemistry profile were marked hyperchloremia (179 mmol/L, reference interval 108-122 mmol/L) and an anion gap of -50.4 mmol/L (reference interval 16.3-28.6 mmol/L). Because of the severe hyperchloremia, serum bromide concentration was measured (400 mg/dL; toxic concentration >150 mg/dL; some dogs may tolerate up to 300 mg/dL). Analysis of the potassium citrate capsules, which had been compounded at a local pharmacy, yielded a mean bromide concentration of 239 mg/capsule. Administration of the capsules was discontinued and there was rapid resolution of the dog's neurologic signs. This case of extreme bromide toxicity, which apparently resulted from inadvertent use of bromide instead of citrate at the pharmacy, illustrates the importance of knowing common interferents with analyte methodologies and of pursing logical additional diagnostic tests based on clinical and laboratory evidence, even when a patient's history appears to rule out a potential etiology.

Full-scale demonstration of in situ cometabolic biodegradation of trichloroethylene in groundwater 1. Dynamics of a recirculating well system

NASA Astrophysics Data System (ADS)

Gandhi, Rahul K.; Hopkins, Gary D.; Goltz, Mark N.; Gorelick, Steven M.; McCarty, Perry L.

2002-04-01

Recirculating well systems provide an engine for the in situ treatment of subsurface contaminants. Although numerous recirculating wells have been installed in the field, for such systems, there is a paucity of comprehensive monitoring data and models constrained to data appearing in the research literature. Here we present an extensive data set combined with detailed inverse and simulation analyses for a two-well groundwater recirculation system used for in situ bioremediation at Edwards Air Force Base in southern California. The ``conveyor belt'' flow system, which was established for in situ treatment of trichloroethylene (TCE) in two bioactive zones, was created by pumping water upward in one well and downward in another well, each well being screened in both the upper and lower aquifers. A bromide tracer test was conducted and extensively monitored for 60 days. Combined inverse analysis was conducted on hydraulic heads from 38 monitoring wells, 32 bromide concentration histories, and a constraint on the degree of recirculation that was based on TCE concentration data. Four different formulations involving alternative weighting schemes used in a nonlinear weighted least squares simulation-regression analysis were explored. The best formulation provided parameter estimates with tight bounds on estimated covariances, suggesting that the model provides a reasonable description of the hydrogeologic system. Our investigation indicates the geometry of the recirculation zone and the degree of recirculation under two different sets of operating conditions. Surprisingly, our analysis suggests that the effects of aquifer heterogeneity are not significant at this site under the conditions of forced recirculation. Furthermore, anomalous flow through an open monitoring well created significant vertical short-circuiting between the generally insulated aquifers. Flow through this small open conduit was equivalent to as much as 33% of the flow through the pumping wells. Using the model as a guide, we treated the aquifer system and bioactive zones as an equivalent mixed reactor to develop simple expressions relating effluent concentrations to influent concentrations. We demonstrate how these expressions are useful in predicting the removal of TCE that had undergone in situ bioremediation in the recirculatory treatment well system. The finite element model developed in this work serves as the foundation for a reactive transport simulator that we developed to analyze bioremediation which occurred during a 444 day experiment [Gandhi et al., 2002].

Vapor-phase transport of trichloroethene in an intermediate-scale vadose-zone system: retention processes and tracer-based prediction.

PubMed

Costanza-Robinson, Molly S; Carlson, Tyson D; Brusseau, Mark L

2013-02-01

Gas-phase transport experiments were conducted using a large weighing lysimeter to evaluate retention processes for volatile organic compounds (VOCs) in water-unsaturated (vadose-zone) systems, and to test the utility of gas-phase tracers for predicting VOC retardation. Trichloroethene (TCE) served as a model VOC, while trichlorofluoromethane (CFM) and heptane were used as partitioning tracers to independently characterize retention by water and the air-water interface, respectively. Retardation factors for TCE ranged between 1.9 and 3.5, depending on water content. The results indicate that dissolution into the bulk water was the primary retention mechanism for TCE under all conditions studied, contributing approximately two-thirds of the total measured retention. Accumulation at the air-water interface comprised a significant fraction of the observed retention for all experiments, with an average contribution of approximately 24%. Sorption to the solid phase contributed approximately 10% to retention. Water contents and air-water interfacial areas estimated based on the CFM and heptane tracer data, respectively, were similar to independently measured values. Retardation factors for TCE predicted using the partitioning-tracer data were in reasonable agreement with the measured values. These results suggest that gas-phase tracer tests hold promise for characterizing the retention and transport of VOCs in the vadose-zone. Copyright © 2012 Elsevier B.V. All rights reserved.

Tracking tracer breakthrough in the hyporheic zone using time‐lapse DC resistivity, Crabby Creek, Pennsylvania

USGS Publications Warehouse

Nyquist, Jonathan E.; Toran, Laura; Fang, Allison C.; Ryan, Robert J.; Rosenberry, Donald O.

2010-01-01

Characterization of the hyporheic zone is of critical importance for understanding stream ecology, contaminant transport, and groundwater‐surface water interaction. A salt water tracer test was used to probe the hyporheic zone of a recently re‐engineered portion of Crabby Creek, a stream located near Philadelphia, PA. The tracer solution was tracked through a 13.5 meter segment of the stream using both a network of 25 wells sampled every 5–15 minutes and time‐lapse electrical resistivity tomographs collected every 11 minutes for six hours, with additional tomographs collected every 100 minutes for an additional 16 hours. The comparison of tracer monitoring methods is of keen interest because tracer tests are one of the few techniques available for characterizing this dynamic zone, and logistically it is far easier to collect resistivity tomographs than to install and monitor a dense network of wells. Our results show that resistivity monitoring captured the essential shape of the breakthrough curve and may indicate portions of the stream where the tracer lingered in the hyporheic zone. Time‐lapse resistivity measurements, however, represent time averages over the period required to collect a tomographic data set, and spatial averages over a volume larger than captured by a well sample. Smoothing by the resistivity data inversion algorithm further blurs the resulting tomograph; consequently resistivity monitoring underestimates the degree of fine‐scale heterogeneity in the hyporheic zone.

Measuring gravel transport and dispersion in a mountain river using passive radio tracers

USGS Publications Warehouse

Bradley, D. N.; Tucker, G. E.

2012-01-01

Random walk models of fluvial sediment transport recognize that grains move intermittently, with short duration steps separated by rests that are comparatively long. These models are built upon the probability distributions of the step length and the resting time. Motivated by these models, tracer experiments have attempted to measure directly the steps and rests of sediment grains in natural streams. This paper describes results from a large tracer experiment designed to test stochastic transport models. We used passive integrated transponder (PIT) tags to label 893 coarse gravel clasts and placed them in Halfmoon Creek, a small alpine stream near Leadville, Colorado, USA. The PIT tags allow us to locate and identify tracers without picking them up or digging them out of the streambed. They also enable us to find a very high percentage of our rocks, 98% after three years and 96% after the fourth year. We use the annual tracer displacement to test two stochastic transport models, the Einstein–Hubbell–Sayre (EHS) model and the Yang–Sayre gamma-exponential model (GEM). We find that the GEM is a better fit to the observations, particularly for slower moving tracers and suggest that the strength of the GEM is that the gamma distribution of step lengths approximates a compound Poisson distribution. Published in 2012. This article is a US Government work and is in the public domain in the USA.

TRACER DISPERSION STUDIES FOR HYDRAULIC CHARACTERIZATION OF PIPES

EPA Science Inventory

A series of experiments were conducted at the U. S. Environmental Protection Agency (EPA) Test & Evaluation (T&E) Facility in Cincinnati, Ohio, to quantify longitudinal dispersion of a sodium fluoride tracer in polyvinyl chloride (PVC) pipe and ductile iron pipe under laminar, tr...

EFFECT OF BROMIDE ION IN WATER TREATMENT. 2. A LITERATURE REVIEW OF OZONE AND BROMIDE ION INTERACTIONS AND THE FORMATION OF ORGANIC BROMINE COMPOUNDS

EPA Science Inventory

Where bromide ion is found in water used as a source of drinking water, and chlorination is used for disinfection, bromide ion is oxidized to bromine and can result in the formation of organic bromine compounds. There are presently no treatment techniques available for economic r...

Automated determination of bromide in waters by ion chromatography with an amperometric detector

USGS Publications Warehouse

Pyen, G.S.; Erdmann, D.E.

1983-01-01

An automated ion chromatograph, including a program controller, an automatic sampler, an integrator, and an amperometric detector, was used to develop a procedure for the determination of bromide in rain water and many ground waters. Approximately 10 min is required to obtain a chromatogram. The detection limit for bromide is 0.01 mg l-1 and the relative standard deivation is <5% for bromide concentrations between 0.05 and 0.5 mg l-1. Chloride interferes if the chloride-to-bromide ratio is greater than 1 000:1 for a range of 0.01-0.1 mg l-1 bromide; similarly, chloride interferes in the 0.1-1.0 mg l-1 range if the ratio is greater than 5 000:1. In the latter case, a maximum of 2 000 mg l-1 of chloride can be tolerated. Recoveries of known concentrations of bromide added to several samples, ranged from 97 to 110%. ?? 1983.

Fluoride tracer test for the performance analysis of a basin used as a lagooning pre-treatment facility in a WTP.

PubMed

Ruffino, Barbara

2015-07-01

The water treatment plant (WTP) of the city of Torino (NW Italy), which treats about 40 · 10(6) m(3)/year of raw water from Po river, has a 15-ha basin used as a lagooning pre-treatment facility. Since the efficiency of the lagooning process in the removal of pollutants from raw water depends on the internal hydrodynamics of the basin, the hydraulic performance of the basin was studied by combining the results of a stimulus-response tracer test with the monitoring of the tracer (fluoride) concentration throughout the basin at different times. The outcomes of the test demonstrated that the system was efficiently mixed and could be assimilated to a continuous stirred reactor presenting no flow anomalies, with an actual mean residence time (RT) of 12.7 days, compared with a nominal RT of 18 days. This assured that dissolved contaminants (such as fluoride) coming from the river were efficiently diluted before entering the WTP. The axial dispersion coefficient calculated from the RT distribution was approximately 47,300 m(2)/day. Three of the most popular formulae developed for the calculation of the axial dispersion coefficient provided results spreading over three orders of magnitude, thus showing their limitations. Finally, because of the width extent of the basin and the characteristics of its inflow, the 1-D advection-dispersion model failed in predicting the tracer concentration values in time at the outlet channel. On the contrary, the analytical solution of the 2-D advection-dispersion model proved to be suitable to fit the tracer concentration data over time at the outlet channel but it failed in describing the tracer distribution throughout the basin on the monitoring dates.

Analysis of Chromatin Organisation

ERIC Educational Resources Information Center

Szeberenyi, Jozsef

2011-01-01

Terms to be familiar with before you start to solve the test: chromatin, nucleases, sucrose density gradient centrifugation, melting point, gel electrophoresis, ethidium bromide, autoradiography, Southern blotting, Northern blotting, Sanger sequencing, restriction endonucleases, exonucleases, linker DNA, chloroform extraction, nucleosomes,…

Bromide's effect on DBP formation, speciation, and control; Part 1: Ozonation

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

Shukairy, H.M.; Summers, R.S.; Miltner, R.J.

1994-06-01

The effect of variable ozone dosage and bromide concentration on the formation of organic disinfection by-products (DBPs) and bromate were evaluated. Low ozone dosages resulted in oxidation of organic precursors, yielding decreases in the formation potential for total trihalomethanes (THMs), six haloacetic acids (HAAs), and total organic halide (TOX). Increasing the ozone dosage oxidized bromide to bromate, decreasing the bromide for incorporation into DBPs. Bromate concentrations were linearly correlated with ozone residuals. Changes in the bromine incorporation factors n and n[prime] reflected differences in the resulting speciation of THMs and HAAs, respectively. Because TOX measurements based on chloride equivalence maymore » underestimate the halogenated DBP yield for high-bromide waters, a procedure is described whereby bromide and bromate concentrations were used to correct the TOX measurement.« less

Analytical solutions for efficient interpretation of single-well push-pull tracer tests

NASA Astrophysics Data System (ADS)

Huang, Junqi; Christ, John A.; Goltz, Mark N.

2010-08-01

Single-well push-pull tracer tests have been used to characterize the extent, fate, and transport of subsurface contamination. Analytical solutions provide one alternative for interpreting test results. In this work, an exact analytical solution to two-dimensional equations describing the governing processes acting on a dissolved compound during a modified push-pull test (advection, longitudinal and transverse dispersion, first-order decay, and rate-limited sorption/partitioning in steady, divergent, and convergent flow fields) is developed. The coupling of this solution with inverse modeling to estimate aquifer parameters provides an efficient methodology for subsurface characterization. Synthetic data for single-well push-pull tests are employed to demonstrate the utility of the solution for determining (1) estimates of aquifer longitudinal and transverse dispersivities, (2) sorption distribution coefficients and rate constants, and (3) non-aqueous phase liquid (NAPL) saturations. Employment of the solution to estimate NAPL saturations based on partitioning and non-partitioning tracers is designed to overcome limitations of previous efforts by including rate-limited mass transfer. This solution provides a new tool for use by practitioners when interpreting single-well push-pull test results.

Development of a solar powered residential air conditioner (General optimization)

NASA Technical Reports Server (NTRS)

Lowen, D. J.

1976-01-01

A commercially available 3-ton residential Lithium Bromide (LiBr) absorption air conditioner was modified for use with lower temperature solar heated water. The modification included removal of components such as the generator, concentration control chamber, liquid trap, and separator; and the addition of a Chrysler designed generator, an off-the-shelf LiBr-solution pump. The design goal of the modified unit was to operate with water as the heat-transfer fluid at a target temperature of 85 C (185 F), 29.4 C (85 F) cooling water inlet, producing 10.5 kW (3 tons) of cooling. Tests were performed on the system before and after modification to provide comparative data. At elevated temperatures (96 C, 205 F), the test results show that Lithium Bromide was carried into the condenser due to the extremely violent boiling and degraded the evaporator performance.

Ipratropium bromide in patients with nocturnal asthma.

PubMed Central

Cox, I. D.; Hughes, D. T.; McDonnell, K. A.

1984-01-01

Fourteen patients with nocturnal asthma were recruited to a two period crossover trial which compared a run-in period on nightly salbutamol (200 micrograms) with a period on nightly ipratropium bromide (160 micrograms) and a period on nightly salbutamol plus ipratropium at night. Morning dipping, as assessed by the fall in peak flow overnight, was significantly reduced in the periods when ipratropium bromide was taken. Peak flow in the morning and also at night was improved when taking ipratropium bromide. Ipratropium bromide in adequate dosage appears to be effective in reducing morning dipping in asthma. PMID:6236436

Deuterium used as artificial tracer in column studies under saturated water flow conditions

NASA Astrophysics Data System (ADS)

Koeniger, P.; Geiges, M.; Leibundgut, Ch.

2003-04-01

In contrast to numerous investigations using deuterium as an environmental tracer, hydrological investigations with deuterium-labelled water are rather rare. Currently applications in groundwater studies are restricted due to increasing costs of spiking large water quantities but an application as intelligent tracer might be of advantage especially in combination with other tracers and under distinct environmental conditions. Therefore deuterium was applied as artificial tracer in column experiments that are well proved as a tool to characterise tracer behaviour in recent studies. Deuterium was tested in comparison to the more familiar conservative tracer fluorescein. Varying experimental conditions, e.g. column length (0.5, 1.0, 1.5 m), initial tracer concentration (0.01, 0.02, 0.2 mg) and flow velocity (1.5 to 6.0 m/d) were used to investigate tracer behaviour under saturated water flow conditions. Deuterium was analysed using an H/Device with chrome reduction connected to an isotope ratio mass spectrometer and expressed in relative concentrations [per mill V-SMOW]. Theoretical tracer breakthrough curves were calculated using a one dimensional dispersion model. The results indicate higher mean transport velocities and smaller dispersion for deuterium in all experiments. Due to different molecule properties that also determine the interaction of soil substrate and tracer, deuterium indicates a more conservative transport behaviour. Deuterium is non-toxic, completely soluble, chemically and biologically stable and not subject to light-influenced decay. Furthermore, it shows promise for investigations of water flow in the unsaturated zone, and of interactions of water in soil-plant-atmosphere systems. A further discussion of problems, together with possibilities for applying deuterium as an artificial tracer, will be presented.

Translation of New Molecular Imaging Approaches to the Clinical Setting: Bridging the Gap to Implementation.

PubMed

van Es, Suzanne C; Venema, Clasina M; Glaudemans, Andor W J M; Lub-de Hooge, Marjolijn N; Elias, Sjoerd G; Boellaard, Ronald; Hospers, Geke A P; Schröder, Carolina P; de Vries, Elisabeth G E

2016-02-01

Molecular imaging with PET is a rapidly emerging technique. In breast cancer patients, more than 45 different PET tracers have been or are presently being tested. With a good rationale, after development of the tracer and proven feasibility, it is of interest to evaluate whether there is a potential meaningful role for the tracer in the clinical setting-such as in staging, in the (early) prediction of a treatment response, or in supporting drug choices. So far, only (18)F-FDG PET has been incorporated into breast cancer guidelines. For proof of the clinical relevance of tracers, especially for analysis in a multicenter setting, standardization of the technology and access to the novel PET tracer are required. However, resources for PET implementation research are limited. Therefore, next to randomized studies, novel approaches are required for proving the clinical value of PET tracers with the smallest possible number of patients. The aim of this review is to describe the process of the development of PET tracers and the level of evidence needed for the use of these tracers in breast cancer. Several breast cancer trials have been performed with the PET tracers (18)F-FDG, 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT), and (18)F-fluoroestradiol ((18)F-FES). We studied them to learn lessons for the implementation of novel tracers. After defining the gap between a good rationale for a tracer and implementation in the clinical setting, we propose solutions to fill the gap to try to bring more PET tracers to daily clinical practice. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Application of zinc isotope tracer technology in tracing soil heavy metal pollution

NASA Astrophysics Data System (ADS)

Norbu, Namkha; Wang, Shuguang; Xu, Yan; Yang, Jianqiang; Liu, Qiang

2017-08-01

Recent years the soil heavy metal pollution has become increasingly serious, especially the zinc pollution. Due to the complexity of this problem, in order to prevent and treat the soil pollution, it's crucial to accurately and quickly find out the pollution sources and control them. With the development of stable isotope tracer technology, it's able to determine the composition of zinc isotope. Based on the theory of zinc isotope tracer technique, and by means of doing some latest domestic and overseas literature research about the zinc isotope multi-receiving cups of inductively coupled plasma mass spectrometer (MC-ICP-MS) testing technology, this paper summarized the latest research results about the pollution tracer of zinc isotope, and according to the deficiencies and existing problems of previous research, made outlooks of zinc isotope fractionation mechanism, repository establishment and tracer multiple solutions.

Patient Positioning Based on a Radioactive Tracer Implanted in Patients With Localized Prostate Cancer: A Performance and Safety Evaluation

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

Kruijf, Willy J.M. de, E-mail: kruijf.de.w@bvi.nl; Verstraete, Jan; Neustadter, David

2013-02-01

Purpose: To evaluate the performance and safety of a radiation therapy positioning system (RealEye) based on tracking a radioactive marker (Tracer) implanted in patients with localized prostate cancer. Methods and Materials: We performed a single-arm multi-institutional trial in 20 patients. The iridium-192 ({sup 192}Ir)-containing Tracer was implanted in the patient together with 4 standard gold seed fiducials. Patient prostate-related symptoms were evaluated with the International Prostate Symptom Score (IPSS) questionnaire. Computed tomography (CT) was performed for treatment planning, during treatment, and after treatment to evaluate the migration stability of the Tracer. At 5 treatment sessions, cone beam CT was performedmore » to test the positioning accuracy of the RealEye. Results: The Tracer was successfully implanted in all patients. No device or procedure-related adverse events occurred. Changes in IPSS scores were limited. The difference between the mean change in Tracer-fiducial distance and the mean change in fiducial-fiducial distance was -0.39 mm (95% confidence interval [CI] upper boundary, -0.22 mm). The adjusted mean difference between Tracer position according to RealEye and the Tracer position on the CBCT for all patients was 1.34 mm (95% CI upper boundary, 1.41 mm). Conclusions: Implantation of the Tracer is feasible and safe. Migration stability of the Tracer is good. Prostate patients can be positioned and monitored accurately by using RealEye.« less

Patient positioning based on a radioactive tracer implanted in patients with localized prostate cancer: a performance and safety evaluation.

PubMed

de Kruijf, Willy J M; Verstraete, Jan; Neustadter, David; Corn, Benjamin W; Hol, Sandra; Venselaar, Jack L M; Davits, Rob J; Wijsman, Bart P; Van den Bergh, Laura; Budiharto, Tom; Oyen, Raymond; Haustermans, Karin; Poortmans, Philip M P

2013-02-01

To evaluate the performance and safety of a radiation therapy positioning system (RealEye) based on tracking a radioactive marker (Tracer) implanted in patients with localized prostate cancer. We performed a single-arm multi-institutional trial in 20 patients. The iridium-192 ((192)Ir)-containing Tracer was implanted in the patient together with 4 standard gold seed fiducials. Patient prostate-related symptoms were evaluated with the International Prostate Symptom Score (IPSS) questionnaire. Computed tomography (CT) was performed for treatment planning, during treatment, and after treatment to evaluate the migration stability of the Tracer. At 5 treatment sessions, cone beam CT was performed to test the positioning accuracy of the RealEye. The Tracer was successfully implanted in all patients. No device or procedure-related adverse events occurred. Changes in IPSS scores were limited. The difference between the mean change in Tracer-fiducial distance and the mean change in fiducial-fiducial distance was -0.39 mm (95% confidence interval [CI] upper boundary, -0.22 mm). The adjusted mean difference between Tracer position according to RealEye and the Tracer position on the CBCT for all patients was 1.34 mm (95% CI upper boundary, 1.41 mm). Implantation of the Tracer is feasible and safe. Migration stability of the Tracer is good. Prostate patients can be positioned and monitored accurately by using RealEye. Copyright © 2013 Elsevier Inc. All rights reserved.

Alternatives to Methyl Bromide (1993)

EPA Pesticide Factsheets

The report examines the alternatives that have been discussed as substitutes for current methyl bromide uses if methyl bromide should no longer be available and discusses the economic implications of such a phaseout.

Prostate cancer and toxicity from critical use exemptions of methyl bromide: Environmental protection helps protect against human health risks

PubMed Central

2012-01-01

Background Although ozone-depleting methyl bromide was destined for phase-out by 2005, it is still widely applied as a consequence of various critical-use-exemptions and mandatory international regulations aiming to restrict the spread of pests and alien species (e.g. in globalized transport and storage). The withdrawal of methyl bromide because of its environmental risk could fortuitously help in the containment of its human toxicity. Methods We performed a systematic review of the literature, including in vitro toxicological and epidemiological studies of occupational and community exposure to the halogenated hydrocarbon pesticide methyl bromide. We focused on toxic (especially chronic) or carcinogenic effects from the use of methyl bromide, on biomonitoring data and reference values. Eligible epidemiological studies were subjected to meta-analysis. Results Out of the 542 peer reviewed publications between 1990-2011, we found only 91 referring to toxicity of methyl bromide and 29 using the term "carcinogenic", "neoplastic" or "mutagenic". Several studies provide new additional data pertaining to the mechanistic aspects of methyl bromide toxicity. Few studies have performed a detailed exposure assessment including biomonitoring. Three evaluated epidemiological studies assessed a possible association between cancer and methyl bromide. Overall, exposure to methyl bromide is associated with an increased risk of prostate cancer OR, 1.21; 95% CI (0,98-1.49), P = 0.076. Two epidemiological studies have analyzed environmental, non-occupational exposure to methyl bromide providing evidence for its health risk to the general public. None of the epidemiological studies addressed its use as a fumigant in freight containers, although recent field and case reports do refer to its toxic effects associated with its use in shipping and storage. Conclusions Both the epidemiological evidence and toxicological data suggest a possible link between methyl bromide exposure and serious health problems, including prostate cancer risk from occupational and community exposure. The environmental risks of methyl bromide are not in doubt, but also its health risks, especially for genetically predisposed subjects, should not be underestimated. PMID:22284215

An Assessment of Aquifer/Well Flow Dynamics: Identification of Parameters Key to Passive Sampling and Application of Downhole Sensor Technologies

DTIC Science & Technology

2014-12-01

Simulated Solute Transport in a Numerical Replication of Britt’s 2005 Experiment Figure 44 In-Well Flow Inhibitor Figure 45 Results of a Preliminary Dye ...Tracer Experiment Conducted at INL Figure 46 Results Horizontally-Oriented Dye Tracer Experiment Conducted at INL ER-1704 Final Report 2014 vii...possible sources of well convection and mixing. Specifically, the modeling explored: • 2D and 3D physical tank models. Dye tracer testing was conducted

Geological modeling of submeter scale heterogeneity and its influence on tracer transport in a fluvial aquifer

NASA Astrophysics Data System (ADS)

Ronayne, Michael J.; Gorelick, Steven M.; Zheng, Chunmiao

2010-10-01

We developed a new model of aquifer heterogeneity to analyze data from a single-well injection-withdrawal tracer test conducted at the Macrodispersion Experiment (MADE) site on the Columbus Air Force Base in Mississippi (USA). The physical heterogeneity model is a hybrid that combines 3-D lithofacies to represent submeter scale, highly connected channels within a background matrix based on a correlated multivariate Gaussian hydraulic conductivity field. The modeled aquifer architecture is informed by a variety of field data, including geologic core sampling. Geostatistical properties of this hybrid heterogeneity model are consistent with the statistics of the hydraulic conductivity data set based on extensive borehole flowmeter testing at the MADE site. The representation of detailed, small-scale geologic heterogeneity allows for explicit simulation of local preferential flow and slow advection, processes that explain the complex tracer response from the injection-withdrawal test. Based on the new heterogeneity model, advective-dispersive transport reproduces key characteristics of the observed tracer recovery curve, including a delayed concentration peak and a low-concentration tail. Importantly, our results suggest that intrafacies heterogeneity is responsible for local-scale mass transfer.

Determination of Groundwater Velocity and Dispersion Parameters by Borehole Wall Multielectrode Geoelectrics

NASA Astrophysics Data System (ADS)

Kessels, W.; Wuttke, M. W.

2007-05-01

A single well technique to determine groundwater flow values and transport parameters is presented. Multielectrode arrays are placed at the filtered casing depth by an inflatable packer or are installed on the borehole wall behind the casing.Tracer water with a higher or lower specific electrical conductivity (salinity) which is injected between the electrodes. This tracer plume then moves into the natural groundwater flow field. The observation of this movement by geoelectric logging enables the determination of the groundwater velocity and salinity. The transport parameters "effective porosity" and "dispersion length" can also be derived. The geoelectric logging uses n borehole electrodes and two grounding electrodes. Thus, either n independent two point measurements or n*(n-1)/2 pole-to-pole measurements can be conducted to obtain a full set of geoelectric measurements. This set is used to derive all electrode combinations by applying the law of superposition and reciprocity. The tracer distribution around the borehole during and after injection depends on the hydraulic and transport parameters of the aquifer and the filter sand. The transport parameter "porosity" plus the total injected tracer volume determines the tracer distribution around the borehole. The transport parameter "dispersivity" determines the abruptness of the tracer front. The method was tested by undertaking measurements in a lab aquifer filled with sand. The results are discussed and the limitations of the method are shown. Multielectrode installations behind casing were tested in situ in the two scientific boreholes CAT-LUD-1 and CAT- LUD-1A drilled in the northern part of Germany. A multielectrode packer system was designed, built and tested in these boreholes. The results are compared with colloid observations in the borehole and hydraulic triangulation in surrounded observation wells. Here, the interpretation of these in situ measurements is mainly restricted to two point geoelectric measurements and vertical four point electrode interpretations. The transport equation for NaCl-tracered water is the basic rule to determine the groundwater transport velocity. Numerical calculations to simulate the measurement are carried out with the program FEFLOW. Due to the density contrast, the tracer undergoes vertical movement. Kessels, W., Zoth, G.(1998): Doppelmantel - Packer mit geoelektrischer Meßtechnik zur Bestimmung der Abstandsgeschwindigkeit des Grundwassers, Patent Az:19855048.0, GGA-Institut, Germany, Hannover. KESSELS, W., RIFAI, H., THORENZ, C., ZOTH, G.(2002): Multi Electrode Geoelectric on the Borehole Wall- Determination of groundwater velocity and dispersion parameters, AGU spring meeting, Washington KESSELS, W., ZOTH, G., WONIK, T., FULDA, C. (1999): THE USE OF SALT CARTRIDGES FOR FLUID LOGGING. XXIV GENERAL ASSEMBLY OF E.G.S. THE HAGUE, THE NETHERLANDS PANTELEIT,B., KESSELS, W., BINOT, F (2006): MUD TRACER TEST DURING SOFT ROCK DRILLING; W.R.R., VOL. 42, W11415, DOI:10.1029/2005WR004487

Removal of bromide and iodide anions from drinking water by silver-activated carbon aerogels.

PubMed

Sánchez-Polo, M; Rivera-Utrilla, J; Salhi, E; von Gunten, U

2006-08-01

The aim of this study is to analyze the use of Ag-doped activated carbon aerogels for bromide and iodide removal from drinking water and to study how the activation of Ag-doped aerogels affects their behavior. It has been observed that the carbonization treatment and activation process of Ag-doped aerogels increased the surface area value ( [Formula: see text] ), whereas the volume of meso-(V(2)) and macropores (V(3)) decreased slightly. Chemical characterization of the materials revealed that carbonization and especially activation process considerably increased the surface basicity of the sample. Original sample (A) presented acidic surface properties (pH(PZC)=4.5) with 21% surface oxygen, whereas the sample that underwent activation showed mainly basic surface chemical properties (pH(PZC)=9.5) with only 6% of surface oxygen. Carbonization and especially, activation process considerable increased the adsorption capacity of bromide and iodide ions. This would mainly be produced by (i) an increase in the microporosity of the sample, which increases Ag-adsorption sites available to halide anions, and (ii) a rise of the basicity of the sample, which produces an increase in attractive electrostatic interactions between the aerogel surface, positively charged at the working pH (pH(solution)

Post-Explosion Tracer Gas Study in Fractured Granite

NASA Astrophysics Data System (ADS)

Avendano, S.; Horne, M.; Herrera, C.; Person, M. A.; Gorman, E.; Stroujkova, A. F.; Gomez-Velez, J. D.

2017-12-01

Radioactive noble gas detection at suspected underground nuclear test sites is the only proven way to confirm that a nuclear test has occurred. However, the migration of gas effluent through fracture networks is still poorly understood. A pilot field study of the gas migration through rock damaged by explosions was conducted in a rock quarry in New Hampshire in the summer of 2017. Tracer gas (SF6), used as a proxy for the noble gas, was released into a cavity created by an explosion (63 kg of TNT at a depth of 13 m) conducted during the summer of 2016. The upper 5 m of borehole were grouted with stainless steel tubing sealed in the concrete and the gas was pumped through the tubing. Before the gas release, we conducted a series of geophysical and hydrologic tests: a pump test, several slug tests, a salt tracer release in two boreholes, and TEM and ERT surveys. Pressure and electrical conductivity transducers were placed in the surrounding boreholes to monitor the pressure changes and tracer arrival during the pumping. The results of the pump test show that the rock is well connected and has high permeability. Interestingly, the injection of gas resulted in a substantial increase of the local hydraulic conductivity, as evidenced by slug test results before and after injection. The pressure changes in the surrounding boreholes were also monitored during the gas release. We observed gas breakthrough immediately after the release. During the first minute after injection, a pressure wave was observed in two boreholes suggestive of inertial effects and hydraulic fracturing after gas release. The concentrations observed at each monitoring site are consistent with the pump testing. The results of this study will be used in our upcoming experiments and to test detailed mathematical models.

The Effects of More Extreme Rainfall Patterns on Infiltration and Nutrient Losses in Agricultural Soils

NASA Astrophysics Data System (ADS)

Hess, L.; Basso, B.; Hinckley, E. L. S.; Robertson, G. P.; Matson, P. A.

2015-12-01

In the coming century, the proportion of total rainfall that falls in heavy storm events is expected to increase in many areas, especially in the US Midwest, a major agricultural region. These changes in rainfall patterns may have consequences for hydrologic flow and nutrient losses, especially in agricultural soils, with potentially negative consequences for receiving ground- and surface waters. We used a tracer experiment to examine how more extreme rainfall patterns may affect the movement of water and solutes through an agricultural soil profile in the upper Midwest, and to what extent tillage may moderate these effects. Two rainfall patterns were created with 5m x 5m rainout shelters at the Kellogg Biological Station LTER site in replicated plots with either conventional tillage or no-till management. Control rainfall treatments received water 3x per week, and extreme rainfall treatments received the same total amount of water but once every two weeks, to simulate less frequent but larger storms. In April 2015, potassium bromide (KBr) was added as a conservative tracer of water flow to all plots, and Br- concentrations in soil water at 1.2m depth were measured weekly from April through July. Soil water Br- concentrations increased and peaked more quickly under the extreme rainfall treatment, suggesting increased infiltration and solute transfer to depth compared to soils exposed to control rainfall patterns. Soil water Br- also increased and peaked more quickly in no-till than in conventional tillage treatments, indicating differences in flow paths between management systems. Soil moisture measured every 15 minutes at 10, 40, and 100cm depths corroborates tracer experiment results: rainfall events simulated in extreme rainfall treatments led to large increases in deep soil moisture, while the smaller rainfall events simulated under control conditions did not. Deep soil moisture in no-till treatments also increased sooner after water application as compared to in conventional soils. Our results suggest that exposure to more extreme rainfall patterns will likely increase infiltration depth and nutrient losses in agricultural soils. In particular, soils under no-till management, which leads to development of preferential flow paths, may be particularly vulnerable to vertical nutrient losses.

Minimization of corrosion using activated sodium bromide in a medium-size cooling tower

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

Nalepa, C.J.; Moore, R.M.; Golson, G.L.

1996-07-01

The cooling tower at the Albermarle Process Development Center in Baton Rouge, Louisiana, historically used chlorine as a biocide in combination with phosphorus-based corrosion/scale inhibitors. Although this regimen provided biocontrol, sludge and iron buildup was a problem in low-velocity, small cross-sectional areas of piping. A general cleanup of the system was performed in April 1995. This cleanup was followed with a switch to a two-component corrosion inhibitor/dispersant package. Alternate biocides were evaluated at this time. Activated sodium bromide was found to be particularly effective in this tower, which operates at pH {approximately}8.4. Relative to chlorine, the use of activated sodiummore » bromide led to a decrease in general and pitting corrosion on mild steel. The reduced corrosion appears to be due to a combination of both chemical (less attack on passivated metal surfaces) and biological factors (better control of heterotrophic and sessile bacteria). These conclusions are supported by chemical analyses, corrosion meter and coupon data, dip slides, biological activity reaction tests, and visual observations of the tower sump and heat exchanger surfaces.« less

Retention time and flow patterns in Lake Marion, South Carolina, 1984

USGS Publications Warehouse

Patterson, G.G.; Harvey, R.M.

1995-01-01

In 1984, six dye tracer tests were made on Lake Marion to determine flow patterns and retention times under conditions of high and low flow. During the high-flow tests, with an average inflow of about 29,000 cubic feet per second, the approximate travel time through the lake for the peak tracer concentration was 14 days. The retention time was about 20 days. During the low-flow tests, with an average inflow of about 9,000 cubic feet per second, the approximate travel time was 41 days, and the retention time was about 60 days. The primary factors controlling movement of water in the lake are lake inflow and outflow. The tracer cloud moved consistently downstream, slowing as the lake widened. Flow patterns in most of the coves, and in some areas along the northeastern shore, are influenced more by tributary inflow than by factors attributable to water from the main body of the lake.

Toxicological and ecotoxicological assessment of water tracers

NASA Astrophysics Data System (ADS)

Behrens, H.; Beims, U.; Dieter, H.; Dietze, G.; Eikmann, T.; Grummt, T.; Hanisch, H.; Henseling, H.; Käß, W.; Kerndorff, H.; Leibundgut, C.; Müller-Wegener, U.; Rönnefahrt, I.; Scharenberg, B.; Schleyer, R.; Schloz, W.; Tilkes, F.

2001-06-01

Uncertainties regarding possible negative effects on the environment or on human health of authorizing tracing experiments in groundwater and surface waters led to the establishment of a Working Group at the German Federal Environmental Agency (Umweltbundesamt - UBA) for conducting a toxicological and ecotoxicological assessment. A total of 17 water tracers was assessed by the Working Group on the basis of the results of toxicological tests, the available literature, and the group's expert knowledge. In the future, tracers that pose a risk to the environment or to human health should no longer be used. Nevertheless, there are a number of tracers that could be used in hydrogeological and hydrological investigations for water-pollution-control purposes with no adverse environmental impact.

Contamination Tracer Testing With Seabed Rock Drills: IODP Expedition 357

NASA Astrophysics Data System (ADS)

Orcutt, B.; Bergenthal, M.; Freudenthal, T.; Smith, D. J.; Lilley, M. D.; Schneiders, L.; Fruh-Green, G. L.

2016-12-01

IODP Expedition 357 utilized seabed rock drills for the first time in the history of the ocean drilling program, with the aim of collecting intact core of shallow mantle sequences from the Atlantis Massif to examine serpentinization processes and the deep biosphere. This new drilling approach required the development of a new system for delivering synthetic tracers during drilling to assess for possible sample contamination. Here, we describe this new tracer delivery system, assess the performance of the system during the expedition, provide an overview of the quality of the core samples collected for deep biosphere investigations based on tracer concentrations, and make recommendations for future applications of the system.

Contamination tracer testing with seabed drills: IODP Expedition 357

NASA Astrophysics Data System (ADS)

Orcutt, Beth N.; Bergenthal, Markus; Freudenthal, Tim; Smith, David; Lilley, Marvin D.; Schnieders, Luzie; Green, Sophie; Früh-Green, Gretchen L.

2017-11-01

IODP Expedition 357 utilized seabed drills for the first time in the history of the ocean drilling program, with the aim of collecting intact sequences of shallow mantle core from the Atlantis Massif to examine serpentinization processes and the deep biosphere. This novel drilling approach required the development of a new remote seafloor system for delivering synthetic tracers during drilling to assess for possible sample contamination. Here, we describe this new tracer delivery system, assess the performance of the system during the expedition, provide an overview of the quality of the core samples collected for deep biosphere investigations based on tracer concentrations, and make recommendations for future applications of the system.

Statistical atmospheric inversion of local gas emissions by coupling the tracer release technique and local-scale transport modelling: a test case with controlled methane emissions

NASA Astrophysics Data System (ADS)

Ars, Sébastien; Broquet, Grégoire; Yver Kwok, Camille; Roustan, Yelva; Wu, Lin; Arzoumanian, Emmanuel; Bousquet, Philippe

2017-12-01

This study presents a new concept for estimating the pollutant emission rates of a site and its main facilities using a series of atmospheric measurements across the pollutant plumes. This concept combines the tracer release method, local-scale atmospheric transport modelling and a statistical atmospheric inversion approach. The conversion between the controlled emission and the measured atmospheric concentrations of the released tracer across the plume places valuable constraints on the atmospheric transport. This is used to optimise the configuration of the transport model parameters and the model uncertainty statistics in the inversion system. The emission rates of all sources are then inverted to optimise the match between the concentrations simulated with the transport model and the pollutants' measured atmospheric concentrations, accounting for the transport model uncertainty. In principle, by using atmospheric transport modelling, this concept does not strongly rely on the good colocation between the tracer and pollutant sources and can be used to monitor multiple sources within a single site, unlike the classical tracer release technique. The statistical inversion framework and the use of the tracer data for the configuration of the transport and inversion modelling systems should ensure that the transport modelling errors are correctly handled in the source estimation. The potential of this new concept is evaluated with a relatively simple practical implementation based on a Gaussian plume model and a series of inversions of controlled methane point sources using acetylene as a tracer gas. The experimental conditions are chosen so that they are suitable for the use of a Gaussian plume model to simulate the atmospheric transport. In these experiments, different configurations of methane and acetylene point source locations are tested to assess the efficiency of the method in comparison to the classic tracer release technique in coping with the distances between the different methane and acetylene sources. The results from these controlled experiments demonstrate that, when the targeted and tracer gases are not well collocated, this new approach provides a better estimate of the emission rates than the tracer release technique. As an example, the relative error between the estimated and actual emission rates is reduced from 32 % with the tracer release technique to 16 % with the combined approach in the case of a tracer located 60 m upwind of a single methane source. Further studies and more complex implementations with more advanced transport models and more advanced optimisations of their configuration will be required to generalise the applicability of the approach and strengthen its robustness.

Estimating fracture spacing from natural tracers in shale-gas production

NASA Astrophysics Data System (ADS)

Bauer, S. J.; McKenna, S. A.; Heath, J. E.; Gardner, P.

2012-12-01

Resource appraisal and long-term recovery potential of shale gas relies on the characteristics of the fracture networks created within the formation. Both well testing and analysis of micro-seismic data can provide information on fracture characteristics, but approaches that directly utilize observations of gas transport through the fractures are not well-developed. We examine transport of natural tracers and analyze the breakthrough curves (BTC's) of these tracers with a multi-rate mass transfer (MMT) model to elucidate fracture characteristics. The focus here is on numerical simulation studies to determine constraints on the ability to accurately estimate fracture network characteristics as a function of the diffusion coefficients of the natural tracers, the number and timing of observations, the flow rates from the well, and the noise in the observations. Traditional tracer testing approaches for dual-porosity systems analyze the BTC of an injected tracer to obtain fracture spacing considering a single spacing value. An alternative model is the MMT model where diffusive mass transfer occurs simultaneously over a range of matrix block sizes defined by a statistical distribution (e.g., log-normal, gamma, or power-law). The goal of the estimation is defining the parameters of the fracture spacing distribution. The MMT model has not yet been applied to analysis of natural in situ natural tracers. Natural tracers are omnipresent in the subsurface, potentially obviating the needed for introduced tracers, and could be used to improve upon fracture characteristics estimated from pressure transient and decline curve production analysis. Results of this study provide guidance for data collection and analysis of natural tracers in fractured shale formations. Parameter estimation on simulated BTC's will provide guidance on the necessary timing of BTC sampling in field experiments. The MMT model can result in non-unique or nonphysical parameter estimates. We address this with Bayesian estimation approaches that can define uncertainty in estimated parameters as a posterior probability distribution. We will also use Bayesian estimation to examine model identifiability (e.g., selecting between parametric distributions of fracture spacing) from various BTC's. Application of the MMT model to natural tracers and hydraulic fractures in shale will require extension of the model to account for partitioning of the tracers between multiple phases and different mass transfer behavior in mixed gas-liquid (e.g., oil or groundwater rich) systems. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

In-Situ 13C-Labeling of Microbial Phospholipid Fatty Acids: Tracing Substrate Assimilation in a Petroleum-Contaminated Aquifer

NASA Astrophysics Data System (ADS)

Pombo, S. A.; Schroth, M. H.; Pelz, O.; Zeyer, J.

2001-12-01

Stable isotope analysis of phospholipid-derived fatty acids (PLFA) is a novel tool to trace assimilation of organic carbon in microbial communities. The 13C-labeling of biomarker fatty acids allows the identification of specific microbial populations involved in the metabolism of particular substrates, supplemented in 13C-labeled form. The goal of this study was to investigate the feasibility of 13C-labeling of PLFA and produced dissolved inorganic carbon (DIC) in a petroleum hydrocarbon (PHC)-contaminated aquifer during an in-situ experiment. To this end, we performed a single-well "push-pull" test in a monitoring well located in the denitrifying zone of a PHC-contaminated aquifer in Studen, Switzerland. During the experiment, we injected 500 L of site groundwater that was amended with 13C-labeled acetate (50% [2-13C]) and nitrate as reactants, and bromide as conservative tracer. Following the injection, we extracted a total of 1000 L of test solution/groundwater mixture after 4, 23 and 46 h from the same location. Concentrations of anions were measured in samples collected during the extraction. From these data, we computed first order rate coefficients for consumption of acetate (0.70 +/- 0.05 1/d) and nitrate (0.63 +/- 0.08 1/d). In addition, we extracted and identified PLFA, and measured \\delta13C values of PLFA and DIC. After only 4 h of incubation, we detected 13C-enrichment of certain PLFA in suspended biomass of extracted groundwater. After 46 h, we measured enrichments of up to 5000 per mil in certain PLFA (e.g. 16:1ω 7c), and up to 1500 per mil in the produced DIC. Our results demonstrate the feasibility of in-situ 13C-labeling of PLFA and DIC using push-pull tests to determine microbial activities in-situ in a natural ecosystem.

METHOD OF SEPARATING URANIUM, PLUTONIUM AND FISSION PRODUCTS BY BROMINATION AND DISTILLATION

DOEpatents

Jaffey, A.H.; Seaborg, G.T.

1958-12-23

The method for separation of plutonium from uranium and radioactive fission products obtained by neutron irradiation of uranlum consists of reacting the lrradiated material with either bromine, hydrogen bromide, alumlnum bromide, or sulfur and bromine at an elevated temperature to form the bromides of all the elements, then recovering substantlally pure plutonium bromide by dlstillatlon in combinatlon with selective condensatlon at prescribed temperature and pressure.

Modeling Single Well Injection-Withdrawal (SWIW) Tests for Characterization of Complex Fracture-Matrix Systems

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

Cotte, F.P.; Doughty, C.; Birkholzer, J.

2010-11-01

The ability to reliably predict flow and transport in fractured porous rock is an essential condition for performance evaluation of geologic (underground) nuclear waste repositories. In this report, a suite of programs (TRIPOLY code) for calculating and analyzing flow and transport in two-dimensional fracture-matrix systems is used to model single-well injection-withdrawal (SWIW) tracer tests. The SWIW test, a tracer test using one well, is proposed as a useful means of collecting data for site characterization, as well as estimating parameters relevant to tracer diffusion and sorption. After some specific code adaptations, we numerically generated a complex fracture-matrix system for computationmore » of steady-state flow and tracer advection and dispersion in the fracture network, along with solute exchange processes between the fractures and the porous matrix. We then conducted simulations for a hypothetical but workable SWIW test design and completed parameter sensitivity studies on three physical parameters of the rock matrix - namely porosity, diffusion coefficient, and retardation coefficient - in order to investigate their impact on the fracture-matrix solute exchange process. Hydraulic fracturing, or hydrofracking, is also modeled in this study, in two different ways: (1) by increasing the hydraulic aperture for flow in existing fractures and (2) by adding a new set of fractures to the field. The results of all these different tests are analyzed by studying the population of matrix blocks, the tracer spatial distribution, and the breakthrough curves (BTCs) obtained, while performing mass-balance checks and being careful to avoid some numerical mistakes that could occur. This study clearly demonstrates the importance of matrix effects in the solute transport process, with the sensitivity studies illustrating the increased importance of the matrix in providing a retardation mechanism for radionuclides as matrix porosity, diffusion coefficient, or retardation coefficient increase. Interestingly, model results before and after hydrofracking are insensitive to adding more fractures, while slightly more sensitive to aperture increase, making SWIW tests a possible means of discriminating between these two potential hydrofracking effects. Finally, we investigate the possibility of inferring relevant information regarding the fracture-matrix system physical parameters from the BTCs obtained during SWIW testing.« less

Subsurface drip application of alternative fumigants to methyl bromide for controlling nematodes in replanted grapevines.

PubMed

Cabrera, J Alfonso; Wang, Dong; Schneider, Sally M; Hanson, Bradley D

2012-05-01

Many California grape growers use preplant fumigation to ensure uniform and healthy grapevine establishment in replant situations. A field study was conducted to evaluate the performance of subsurface drip-applied chemical alternatives to methyl bromide on plant-parasitic nematodes, plant vigor and fruit yield during the 6 year period following replanting. Subsurface drip fumigation with 1,3-dichloropropene plus chloropicrin and with iodomethane plus chloropicrin had generally similar nematicide activity as methyl bromide in three grape types, while sodium azide was less effective. The combination of 1,3-dichloropropene plus chloropicrin enhanced vine vigor similarly to methyl bromide. However, all plots treated with alternative fumigants produced less fruit yield than methyl bromide over the 4 years of evaluation. Subsurface drip fumigation with alternative chemicals to methyl bromide generally provided adequate management of plant-parasitic nematodes during the vine establishment period. However, further research is required to increase the performance of alternative chemicals against other components of the replant problem, as grape yield in vines grown in the alternative treatments was lower than in methyl bromide. Copyright © 2011 Society of Chemical Industry.

Role of the bottom sediments immediately beneath the lake water-groundwater interface in the transport and removal of cyanobacteria, cyanophage, and dissolved organic carbon during natural lake-bank filtration at a kettle pond subject to harmful algal blooms

NASA Astrophysics Data System (ADS)

Harvey, R. W.; Metge, D. W.; LeBlanc, D. R.; Underwood, J. C.; Aiken, G.; McCobb, T. D.; Jasperse, J.

2015-12-01

Bank filtration has proven to be a sustainable, cost-effective method of removing cyanobacteria and their harmful toxins from surface water during filtration through bottom and aquifer sediments. The biologically active layer of sediments immediately beneath the sediment-water interface (colmation layer) is believed to be particularly important in this process. An in situ experiment was conducted that involved assessing the transport behaviors of bromide (conservative tracer), Synechococcus sp. IU625 (cyanobacterium, 2.6 ± 0.2 µm), AS-1 (tailed cyanophages, 110 nm long), MS2 (coliphages, 26 nm diameter), and carboxylate-modified microspheres (1.7 µm diameter) introduced to the colmation layer using a bag-and-barrel (Lee-type) seepage meter. The constituents were monitored as they advected through the colmation layer and underlying aquifer sediments at Ashumet Pond in Cape Cod, MA, a mesotrophic kettle pond that recharges a portion of a sole-source, drinking water aquifer. Because the pond DOC includes the various cyanotoxins produced during harmful algal bloom senescence, the DOC and aforementioned colloids were tracked concomitantly. The tracer test constituents were monitored as they advected across the pond water-groundwater interface and through the underlying aquifer sediments under natural-gradient conditions past push-points samplers placed at ~30-cm intervals along a 1.2-m-long, diagonally downward flow path. More than 99% of the microspheres, IU625, MS2, AS-1, and ~42% of the pond DOC were removed in the colmation layer (upper 25 cm of poorly sorted bottom sediments) at two test locations characterized by dissimilar seepage rates (1.7 vs. 0.26 m d-1). Retention profiles in recovered core material indicated that >82% of the attached IU625 were in the top 3 cm of bottom sediments. The colmation layer was also responsible for rapid changes in the character of the DOC and was more effective (by 3 orders of magnitude) at removing microspheres than was the underlying 30-cm-long segment of sediment. A follow-up study conducted the following year at the same location demonstrated that removal of the top 5 cm of sediment resulted in a six-fold decrease in the efficiency of the near-surface bottom sediments for filtering out Synechococcus, cyanophage, and well-characterized microspheres.

Applicability of ELISA-based Determination of Pesticides for Groundwater Quality Monitoring

NASA Astrophysics Data System (ADS)

Tsuchihara, Takeo; Yoshimoto, Shuhei; Ishida, Satoshi; Imaizumi, Masayuki

The principals and procedures of ELISA (Enzyme-linked Immunosorbent Assay)-based determination of pesticides (Fenitrothion) in environmental samples were reviewed, and the applicability of the ELISA method for groundwater quality monitoring were validated through the experimental tracer tests in soil columns and the field test in Okinoerabu Island. The test results showed that the ELISA method could be useful not only for screening but also for quantitative analysis of pesticides. In the experimental tracer tests in soil columns, the retardation of pesticides leaching compared with conservative tracers were observed. In the field test, the contamination of the pesticide was detected in groundwater samples in Okinoerabu Island, even though the targeted pesticide was considered to be applied to the upland field 4 months ago. In order to investigate the transport and fate of pesticides in groundwater taking into account retardation from the field to groundwater table and the residue in groundwater, continuous observations of pesticides in groundwater are in a strong need, and the ELISA method is applicable to the long-term quality groundwater monitoring.

Assessing the Accuracy of the Tracer Dilution Method with Atmospheric Dispersion Modeling

NASA Astrophysics Data System (ADS)

Taylor, D.; Delkash, M.; Chow, F. K.; Imhoff, P. T.

2015-12-01

Landfill methane emissions are difficult to estimate due to limited observations and data uncertainty. The mobile tracer dilution method is a widely used and cost-effective approach for predicting landfill methane emissions. The method uses a tracer gas released on the surface of the landfill and measures the concentrations of both methane and the tracer gas downwind. Mobile measurements are conducted with a gas analyzer mounted on a vehicle to capture transects of both gas plumes. The idea behind the method is that if the measurements are performed far enough downwind, the methane plume from the large area source of the landfill and the tracer plume from a small number of point sources will be sufficiently well-mixed to behave similarly, and the ratio between the concentrations will be a good estimate of the ratio between the two emissions rates. The mobile tracer dilution method is sensitive to different factors of the setup such as placement of the tracer release locations and distance from the landfill to the downwind measurements, which have not been thoroughly examined. In this study, numerical modeling is used as an alternative to field measurements to study the sensitivity of the tracer dilution method and provide estimates of measurement accuracy. Using topography and wind conditions for an actual landfill, a landfill emissions rate is prescribed in the model and compared against the emissions rate predicted by application of the tracer dilution method. Two different methane emissions scenarios are simulated: homogeneous emissions over the entire surface of the landfill, and heterogeneous emissions with a hot spot containing 80% of the total emissions where the daily cover area is located. Numerical modeling of the tracer dilution method is a useful tool for evaluating the method without having the expense and labor commitment of multiple field campaigns. Factors tested include number of tracers, distance between tracers, distance from landfill to transect path, and location of tracers with respect to the hot spot. Results show that location of the tracers relative to the hot spot of highest landfill emissions makes the largest difference in accuracy of the tracer dilution method.

USING CONTINUOUS MONITORS FOR CONDUCTING TRACER STUDIES IN WATER DISTRIBUTION SYSTEMS

EPA Science Inventory

The use of online monitors for conducting a distribution system tracer study is proving to be an essential tool to accurately understand the flow dynamics in a distribution system. In a series of field testing sponsored by U. S. Environmental Protection Agency (EPA) and Greater ...

EVALUATION AND SENSITIVITY ANALYSES RESULTS OF THE MESOPUFF II MODEL WITH CAPTEX MEASUREMENTS

EPA Science Inventory

The MESOPUFF II regional Lagrangian puff model has been evaluated and tested against measurements from the Cross-Appalachian Tracer Experiment (CAPTEX) data base in an effort to assess its abilIty to simulate the transport and dispersion of a nonreactive, nondepositing tracer plu...

A novel cetyltrimethyl ammonium silver bromide complex and silver bromide nanoparticles obtained by the surfactant counterion.

PubMed

Liu, Xian-Hao; Luo, Xiao-Hong; Lu, Shu-Xia; Zhang, Jing-Chang; Cao, Wei-Liang

2007-03-01

A novel cetyltrimethyl ammonium silver bromide (CTASB) complex has been prepared simply through the reaction of silver nitrate with cetyltrimethyl ammonium bromide (CTAB) in aqueous solution at room temperature by controlling the concentration of CTAB and the molar ratio of CTAB to silver nitrate in the reaction solution, in which halogen in CTAB is used as surfactant counterion. The structure and thermal behavior of cetyltrimethyl ammonium silver bromide have been investigated by using X-ray diffraction (XRD), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), UV/vis spectroscopy, thermal analysis (TG-DTA), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The results show that the complex possesses a metastable layered structure. Upon heating the CTASB aqueous dispersion to above 80 degrees C, the structure change of the complex took place and CTAB-capped nanosized silver bromide particles further formed.

Interpretation of Tracer Experiments on Inverted Five-spot Well-patterns within the Western Half of the Farnsworth Unit Oil Field

DOE PAGES

White, Mark D.; Esser, R. P.; McPherson, B. P.; ...

2017-07-01

The Southwest Carbon Partnership (SWP), one of the U.S. Department of Energy (U.S. DOE) seven Regional Carbon Sequestration Partnerships, is currently working to demonstrate the utilization and storage of CO 2 in the Farnsworth Unit (FWU) Enhanced Oil Recovery (EOR) site under the final development phase of this U.S. DOE initiative. A component of the research is to use fluid tracers to understand the multifluid flow patterns that develop between injection and production wells via collected field data and supporting numerical reservoir models. The FWU, located in the Anadarko Basin, Ochiltree County, Texas, and being operated by Chaparral Energy, ismore » a mature EOR water-flood field, which is currently being converted to a CO 2 flow, with inverted 5-spot patterns transitioning from pure water to alternating CO 2 and water floods (i.e., water alternating gas (WAG)) at an approximate rate of one every 6 to 10 months. The SWP tracer program is conducting a suite of tracer injections into the active 5-spot patterns at the FWU. Tracers have been selected to be nonreactive and either principally soluble in CO 2 (gas soluble) or water (aqueous soluble). In addition to characterizing the multifluid flow behaviour within reservoir, the gas and aqueous tracers have roles in detecting any leakage from the reservoir. A total of seven unique perfluorocarbon tracer (PFT) compounds make up the suite of gas soluble tracers and eight unique naphthalene sulfonate tracer (NPT) compounds comprise the aqueous soluble tracers. Lastly, all selected tracers are significantly detectable below the parts per billion concentrations, allowing for high resolution for the inter-well tests at relatively low injection volumes.« less

Interpretation of Tracer Experiments on Inverted Five-spot Well-patterns within the Western Half of the Farnsworth Unit Oil Field

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

White, Mark D.; Esser, R. P.; McPherson, B. P.

The Southwest Carbon Partnership (SWP), one of the U.S. Department of Energy (U.S. DOE) seven Regional Carbon Sequestration Partnerships, is currently working to demonstrate the utilization and storage of CO 2 in the Farnsworth Unit (FWU) Enhanced Oil Recovery (EOR) site under the final development phase of this U.S. DOE initiative. A component of the research is to use fluid tracers to understand the multifluid flow patterns that develop between injection and production wells via collected field data and supporting numerical reservoir models. The FWU, located in the Anadarko Basin, Ochiltree County, Texas, and being operated by Chaparral Energy, ismore » a mature EOR water-flood field, which is currently being converted to a CO 2 flow, with inverted 5-spot patterns transitioning from pure water to alternating CO 2 and water floods (i.e., water alternating gas (WAG)) at an approximate rate of one every 6 to 10 months. The SWP tracer program is conducting a suite of tracer injections into the active 5-spot patterns at the FWU. Tracers have been selected to be nonreactive and either principally soluble in CO 2 (gas soluble) or water (aqueous soluble). In addition to characterizing the multifluid flow behaviour within reservoir, the gas and aqueous tracers have roles in detecting any leakage from the reservoir. A total of seven unique perfluorocarbon tracer (PFT) compounds make up the suite of gas soluble tracers and eight unique naphthalene sulfonate tracer (NPT) compounds comprise the aqueous soluble tracers. Lastly, all selected tracers are significantly detectable below the parts per billion concentrations, allowing for high resolution for the inter-well tests at relatively low injection volumes.« less

Permeation of halide anions through phospholipid bilayers occurs by the solubility-diffusion mechanism

NASA Technical Reports Server (NTRS)

Paula, S.; Volkov, A. G.; Deamer, D. W.

1998-01-01

Two alternative mechanisms are frequently used to describe ionic permeation of lipid bilayers. In the first, ions partition into the hydrophobic phase and then diffuse across (the solubility-diffusion mechanism). The second mechanism assumes that ions traverse the bilayer through transient hydrophilic defects caused by thermal fluctuations (the pore mechanism). The theoretical predictions made by both models were tested for halide anions by measuring the permeability coefficients for chloride, bromide, and iodide as a function of bilayer thickness, ionic radius, and sign of charge. To vary the bilayer thickness systematically, liposomes were prepared from monounsaturated phosphatidylcholines (PC) with chain lengths between 16 and 24 carbon atoms. The fluorescent dye MQAE (N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide) served as an indicator for halide concentration inside the liposomes and was used to follow the kinetics of halide flux across the bilayer membranes. The observed permeability coefficients ranged from 10(-9) to 10(-7) cm/s and increased as the bilayer thickness was reduced. Bromide was found to permeate approximately six times faster than chloride through bilayers of identical thickness, and iodide permeated three to four times faster than bromide. The dependence of the halide permeability coefficients on bilayer thickness and on ionic size were consistent with permeation of hydrated ions by a solubility-diffusion mechanism rather than through transient pores. Halide permeation therefore differs from that of a monovalent cation such as potassium, which has been accounted for by a combination of the two mechanisms depending on bilayer thickness.

Dual pore-connectivity and flow-paths affect shale hydrocarbon production

NASA Astrophysics Data System (ADS)

Hayman, N. W.; Daigle, H.; Kelly, E. D.; Milliken, K. L.; Jiang, H.

2016-12-01

Aided with integrated characterization approaches of droplet contact angle measurement, mercury intrusion capillary pressure, low-pressure gas physisorption, scanning electron microscopy, and small angle neutron scattering, we have systematically studied how pore connectivity and wettability are associated with mineral and organic matter phases of shales (Barnett, Bakken, Eagle Ford), as well as their influence on macroscopic fluid flow and hydrocarbon movement, from the following complementary tests: vacuum saturation with vacuum-pulling on dry shale followed with tracer introduction and high-pressure intrusion, tracer diffusion into fluid-saturated shale, fluid and tracer imbibition into partially-saturated shale, and Wood's metal intrusion followed with imaging and elemental mapping. The first three tests use tracer-bearing fluids (hydrophilic API brine and hydrophobic n-decane) fluids with a suite of wettability tracers of different sizes and reactivities developed in our laboratory. These innovative and integrated approaches indicate a Dalmatian wettability behavior at a scale of microns, limited connectivity (<500 microns from shale sample edge) shale pores, and disparity of well-connected hydrophobic pore network ( 10 nm) and sparsely connected hydrophilic pore systems (>50-100 nm), which is linked to the steep initial decline and low overall recovery because of the limited connection of hydrocarbon molecules in the shale matrix to the stimulated fracture network.

Travel-time-based thermal tracer tomography

NASA Astrophysics Data System (ADS)

Somogyvári, Márk; Bayer, Peter; Brauchler, Ralf

2016-05-01

Active thermal tracer testing is a technique to get information about the flow and transport properties of an aquifer. In this paper we propose an innovative methodology using active thermal tracers in a tomographic setup to reconstruct cross-well hydraulic conductivity profiles. This is facilitated by assuming that the propagation of the injected thermal tracer is mainly controlled by advection. To reduce the effects of density and viscosity changes and thermal diffusion, early-time diagnostics are used and specific travel times of the tracer breakthrough curves are extracted. These travel times are inverted with an eikonal solver using the staggered grid method to reduce constraints from the pre-defined grid geometry and to improve the resolution. Finally, non-reliable pixels are removed from the derived hydraulic conductivity tomograms. The method is applied to successfully reconstruct cross-well profiles as well as a 3-D block of a high-resolution fluvio-aeolian aquifer analog data set. Sensitivity analysis reveals a negligible role of the injection temperature, but more attention has to be drawn to other technical parameters such as the injection rate. This is investigated in more detail through model-based testing using diverse hydraulic and thermal conditions in order to delineate the feasible range of applications for the new tomographic approach.

Removal of microbial pathogens in a sandy gravel aquifer under forced-gradient subsurface flow conditions

NASA Astrophysics Data System (ADS)

Oudega, Thomas James; Derx, Julia; van Driezum, Inge; Cisneros, Anibal; Sommer, Regina; Kirschner, Alexander; Farnleitner, Andreas; Blaschke, Alfred Paul

2017-04-01

Subsurface media are being used around the world as a means to mitigate microbial contamination, but vary widely in their ability to remove pathogens. To help to provide accurate risk assessments of microbial contamination of groundwaters, and establish safe setback distances between receiving waters and disposal fields, this study aims to use aquifer tracer tests to evaluate the ability of subsurface media to attenuate these pathogens. The novelty of this work is the use of a variety of different tracer substances (e.g. phages, spores, microspheres, conservative tracers) together in field experiments. This will be done by means of injecting these substances under a forced gradient in a sandy gravel aquifer in Lobau, Austria. The extraction of the tracers will be monitored in a pumping well at a distrance of 50m downgradient. This will be able to provide us with insight to the characteristics of microbial transport and how the microorganisms react to the subsurface in the study site. Subsequent numerical modelling of the experiments can tell us more about quantification of subsurface processes such as attachment/detachment, inactivation and die-off of these substances. The first field experiment with conservative tracers (NaCl) has been carried out in December 2016, and subsequent tests are being planned for the next months.

Dual pore-connectivity and flow-paths affect shale hydrocarbon production

NASA Astrophysics Data System (ADS)

Hu, Q.; Barber, T.; Zhang, Y.; Md Golam, K.

2017-12-01

Aided with integrated characterization approaches of droplet contact angle measurement, mercury intrusion capillary pressure, low-pressure gas physisorption, scanning electron microscopy, and small angle neutron scattering, we have systematically studied how pore connectivity and wettability are associated with mineral and organic matter phases of shales (Barnett, Bakken, Eagle Ford), as well as their influence on macroscopic fluid flow and hydrocarbon movement, from the following complementary tests: vacuum saturation with vacuum-pulling on dry shale followed with tracer introduction and high-pressure intrusion, tracer diffusion into fluid-saturated shale, fluid and tracer imbibition into partially-saturated shale, and Wood's metal intrusion followed with imaging and elemental mapping. The first three tests use tracer-bearing fluids (hydrophilic API brine and hydrophobic n-decane) fluids with a suite of wettability tracers of different sizes and reactivities developed in our laboratory. These innovative and integrated approaches indicate a Dalmatian wettability behavior at a scale of microns, limited connectivity (<500 microns from shale sample edge) shale pores, and disparity of well-connected hydrophobic pore network ( 10 nm) and sparsely connected hydrophilic pore systems (>50-100 nm), which is linked to the steep initial decline and low overall recovery because of the limited connection of hydrocarbon molecules in the shale matrix to the stimulated fracture network.

Investigating ebullition in a sand column using dissolved gas analysis and reactive transport modeling

USGS Publications Warehouse

Amos, Richard T.; Mayer, K. Ulrich

2006-01-01

Ebullition of gas bubbles through saturated sediments can enhance the migration of gases through the subsurface, affect the rate of biogeochemical processes, and potentially enhance the emission of important greenhouse gases to the atmosphere. To better understand the parameters controlling ebullition, methanogenic conditions were produced in a column experiment and ebullition through the column was monitored and quantified through dissolved gas analysis and reactive transport modeling. Dissolved gas analysis showed rapid transport of CH4 vertically through the column at rates several times faster than the bromide tracer and the more soluble gas CO2, indicating that ebullition was the main transport mechanism for CH4. An empirically derived formulation describing ebullition was integrated into the reactive transport code MIN3P allowing this process to be investigated on the REV scale in a complex geochemical framework. The simulations provided insights into the parameters controlling ebullition and show that, over the duration of the experiment, 36% of the CH4 and 19% of the CO2 produced were transported to the top of the column through ebullition.

Hyporheic exchange and fulvic acid redox reactions in an alpine stream/wetland ecosystem, Colorado front range

USGS Publications Warehouse

Miller, Matthew P.; McKnight, Diane M.; Cory, R.M.; Williams, Mark W.; Runkel, Robert L.

2006-01-01

The influence of hyporheic zone interactions on the redox state of fulvic acids and other redox active species was investigated in an alpine stream and adjacent wetland, which is a more reducing environment. A tracer injection experiment using bromide (Br-) was conducted in the stream system. Simulations with a transport model showed that rates of exchange between the stream and hyporheic zone were rapid (?? ??? 10-3 s -1). Parallel factor analysis of fluorescence spectra was used to quantify the redox state of dissolved fulvic acids. The rate coefficient for oxidation of reduced fulvic acids (?? = 6.5 ?? 10-3 s -1) in the stream indicates that electron-transfer reactions occur over short time scales. The rate coefficients for decay of ammonium (?? = 1.2 ?? 10-3 s-1) and production of nitrate (?? = -1.0 ?? 10-3 s-1) were opposite in sign but almost equal in magnitude. Our results suggest that fulvic acids are involved in rapid electron-transfer processes in and near the stream channel and may be important in determining ecological energy flow at the catchment scale. ?? 2006 American Chemical Society.

Water recharge and solute transport through the vadose zone of fractured chalk under desert conditions

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

Nativ, R.; Dahan, O.; Adar, E.

In the present study the inferred mechanism of groundwater recharge and contamination was studied using tracer concentrations in the fractured vadose zone of the Avdat chalk. The results of this study are important for an evaluation of groundwater contamination from existing and planned facilities in the northern Negev desert in Israel. This study focused on the vicinity of the Ramat Hovav industrial chemical complex in the northern Negev, which also includes the national site for hazardous waste. Water recharge and solute migration rates were examined in five core holes and one borehole which penetrate the entire vadose zone and enabledmore » the collection of rock samples for chemical and isotopic analyses, and an observation of fracture distribution with depth. Tritium profiles were used to estimate water percolation rates through the vadose zone, chloride profiles were used to assess the migration rate of nonreactive solutes, and bromide profiles were also used to evaluate the migration rate of nonreactive contaminants. Deuterium and oxygen 18 profiles were used to assess the evaporation of the infiltrating water at and near land surface.« less

Physicochemical and in vitro deposition properties of salbutamol sulphate/ipratropium bromide and salbutamol sulphate/excipient spray dried mixtures for use in dry powder inhalers.

PubMed

Corrigan, Deirdre O; Corrigan, Owen I; Healy, Anne Marie

2006-09-28

The physicochemical and aerodynamic properties of spray dried powders of the drug/drug mixture salbutamol sulphate/ipratropium bromide were investigated. The in vitro deposition properties of spray dried salbutamol sulphate and the spray dried drug/excipient mixtures salbutamol sulphate/lactose and salbutamol sulphate/PEG were also determined. Spray drying ipratropium bromide monohydrate resulted in a crystalline material from both aqueous and ethanolic solution. The product spray dried from aqueous solution consisted mainly of ipratropium bromide anhydrous. There was evidence of the presence of another polymorphic form of ipratropium bromide. When spray dried from ethanolic solution the physicochemical characterisation suggested the presence of an ipratropium bromide solvate with some anhydrous ipratropium bromide. Co-spray drying salbutamol sulphate with ipratropium bromide resulted in amorphous composites, regardless of solvent used. Particles were spherical and of a size suitable for inhalation. Twin impinger studies showed an increase in the fine particle fraction (FPF) of spray dried salbutamol sulphate compared to micronised salbutamol sulphate. Co-spray dried salbutamol sulphate:ipratropium bromide 10:1 and 5:1 systems also showed an increase in FPF compared to micronised salbutamol sulphate. Most co-spray dried salbutamol sulphate/excipient systems investigated demonstrated FPFs greater than that of micronised drug alone. The exceptions to this were systems containing PEG 4000 20% or PEG 20,000 40% both of which had FPFs not significantly different from micronised salbutamol sulphate. These two systems were crystalline unlike most of the other spray dried composites examined which were amorphous in nature.

Identifying novel radiotracers for PET imaging of the brain: application of LC-MS/MS to tracer identification.

PubMed

Barth, Vanessa; Need, Anne

2014-12-17

Nuclear medicine imaging biomarker applications are limited by the radiotracers available. Radiotracers enable the measurement of target engagement, or occupancy in relation to plasma exposure. These tracers can also be used as pharmacodynamic biomarkers to demonstrate functional consequences of binding a target. More recently, radiotracers have also been used for patient tailoring in Alzheimer's disease seen with amyloid imaging. Radiotracers for the central nervous system (CNS) are challenging to identify, as they require a unique intersection of multiple properties. Recent advances in tangential technologies, along with the use of iterative learning for the purposes of deriving in silico models, have opened up additional opportunities to identify radiotracers. Mass spectral technologies and in silico modeling have made it possible to measure and predict in vivo characteristics of molecules to indicate potential tracer performance. By analyzing these data alongside other measures, it is possible to delineate guidelines to increase the likelihood of selecting compounds that can perform as radiotracers or serve as the best starting point to develop a radiotracer following additional structural modification. The application of mass spectrometry based technologies is an efficient way to evaluate compounds as tracers in vivo, but more importantly enables the testing of potential tracers that have either no label site or complex labeling chemistry which may deter assessment by traditional means; therefore, use of this technology allows for more rapid iterative learning. The ability to differentially distribute toward target rich tissues versus tissue with no/less target present is a unique defining feature of a tracer. By testing nonlabeled compounds in vivo and analyzing tissue levels by LC-MS/MS, rapid assessment of a compound's ability to differentially distribute in a manner consistent with target expression biology guides the focus of chemistry resources for both designing and labeling tracer candidates. LC-MS/MS has only recently been used for de novo tracer identification; however, this connection of mass spectral technology to imaging has initiated engagement from a wider community that brings diverse backgrounds into the tracer discovery arena.

Sympathetic influence on the pupillary light response in three red-eared slider turtles (Trachemys scripta elegans).

PubMed

Dearworth, James R; Cooper, Lori J

2008-01-01

We investigated the effects of phenylephrine and its combination with vecuronium bromide on the iris of turtles to determine if the pupillary light response is affected by sympathetic innervation. Three red-eared slider turtles, Trachemys scripta elegans. Diameters of light-adapted pupils were tracked before and after topical application of drugs to eyes. Phenylephrine was applied independently; in a second group of trials, vecuronium bromide was applied with phenylephrine. Rates of pupil dilation in response to drugs were quantified by fitting data with time constant (tau) equations. Phenylephrine dilated the pupil 24%, tau = 29 min. Combination of phenylephrine with vecuronium bromide increased the pupil size 35%, and dilation was more rapid, tau = 14 min. We also were able to predict these time constants by performing different mathematical operations with an equation developed from a prior study using only vecuronium bromide. When this equation was subtracted from the equation for eyes treated with both vecuronium bromide and phenylephrine, the difference gave the observed tau for phenylephrine; when added to phenylephrine, the sum closely matched the tau for eyes treated with vecuronium bromide and phenylephrine. Further, the tau for vecuronium bromide treated eyes was predicted by subtracting the equation for phenylephrine from that of eyes treated with both vecuronium bromide and phenylephrine. Our results suggest that sympathetic innervation interacts with the parasympathetic pathway to control the pupillary light response in turtles.

Surfactant-Induced Changes of Water Flow and Solute Transport in Soils

NASA Astrophysics Data System (ADS)

Kinsey, E. N.; Korte, C.; Peng, Z.; Yu, C.; Powelson, D.; Jacobson, A. R.; Baveye, P. C.; Darnault, C. J. G.

2016-12-01

Surfactants are present in the environment due to agricultural practices such as irrigation with wastewater, biosolid soil amendments, and/or environmental engineering remediation. Furthermore, surfactants occur widely in soils due to the application of pesticides in surfactant solution sprays, or the application of surfactants as soil wetting agents. Surfactants, because they are amphiphilic and impact the surface tension of aqueous solutions and the contact angle between aqueous and solid phases have the potential to influence water flow in porous media and the physicochemical properties of soils. The objective of this study was to assess the impact of surfactant on the soil infiltration process. Four different soils were used in this study: two sandy loam soils (Lewiston and Greenson series) and two loamy sand soils (Sparta and Gilford series). Rainfall was simulated to flow through different columns filled with the four different types of soil and effluent samples were collected at the end of each column. Each type of soil had two columns, one with a non-ionic surfactant Aerosol®22 at twice the critical micelle concentration, in the rainfall solution and one without. A conservative tracer, potassium bromide, was added to all rainfalls to monitor the infiltration process in soil. Tracer breakthrough curves were used to characterize flow in soils. Flow rates were also recorded for each soil. The presence of surfactant decreased the flow rate by a significant amount in most soil types. The decrease in flow rate can be attributed to the effects on the soil properties of hydraulic conductivity and soil aggregates. A decrease in pore space from the swelling of the soil particles can decrease the hydraulic conductivity. The properties in surfactants also decrease the surface tension and therefore soil particles are able to be dislodged from soil aggregates and cause potential soil clogging.

Colloid transport in dual-permeability media

NASA Astrophysics Data System (ADS)

Leij, Feike J.; Bradford, Scott A.

2013-07-01

It has been widely reported that colloids can travel faster and over longer distances in natural structured porous media than in uniform structureless media used in laboratory studies. The presence of preferential pathways for colloids in the subsurface environment is of concern because of the increased risks for disease caused by microorganisms and colloid-associated contaminants. This study presents a model for colloid transport in dual-permeability media that includes reversible and irreversible retention of colloids and first-order exchange between the aqueous phases of the two regions. The model may also be used to describe transport of other reactive solutes in dual-permeability media. Analytical solutions for colloid concentrations in aqueous and solid phases were obtained using Laplace transformation and matrix decomposition. The solutions proved convenient to assess the effect of model parameters on the colloid distribution. The analytical model was used to describe effluent concentrations for a bromide tracer and 3.2- or 1-μm-colloids that were observed after transport through a composite 10-cm long porous medium made up of a cylindrical lens or core of sand and a surrounding matrix with sand of a different grain size. The tracer data were described very well and realistic estimates were obtained for the pore-water velocity in the two flow domains. An accurate description was also achieved for most colloid breakthrough curves. Dispersivity and retention parameters were typically greater for the larger 3.2-μm-colloids while both reversible and irreversible retention rates tended to be higher for the finer sands than the coarser sand. The relatively small sample size and the complex flow pattern in the composite medium made it difficult to reach definitive conclusions regarding transport parameters for colloid transport.

Impact of long-term wastewater irrigation on sorption and transport of atrazine in Mexican agricultural soils.

PubMed

Müller, K; Duwig, C; Prado, B; Siebe, C; Hidalgo, C; Etchevers, J

2012-01-01

In the Mezquital Valley, Mexico, crops have been irrigated with untreated municipal wastewater for more than a century. Atrazine has been applied to maize and alfalfa grown in the area for weed control for 15 years. Our objectives were to analyse (i) how wastewater irrigation affects the filtering of atrazine, and (ii) if the length of irrigation has a significant impact. We compared atrazine sorption to Phaeozems that have been irrigated with raw wastewater for 35 (P35) and 85 (P85) years with sorption to a non-irrigated (P0) Phaeozem soil under rainfed agriculture. The use of bromide as an inert water tracer in column experiments and the subsequent analysis of the tracers' breakthrough curves allowed the calibration of the hydrodynamic parameters of a two-site non equilibrium convection-dispersion model. The quality of the irrigation water significantly altered the soils' hydrodynamic properties (hydraulic conductivity, dispersivity and the size of pores that are hydraulically active). The impacts on soil chemical properties (total organic carbon content and pH) were not significant, while the sodium adsorption ratio was significantly increased. Sorption and desorption isotherms, determined in batch and column experiments, showed enhanced atrazine sorption and reduced and slower desorption in wastewater-irrigated soils. These effects increased with the length of irrigation. The intensified sorption-desorption hysteresis in wastewater-irrigated soils indicated that the soil organic matter developed in these soils had fewer high-energy, easily accessible sorption sites available, leading to lower and slower atrazine desorption rates. This study leads to the conclusion that wastewater irrigation decreases atrazine mobility in the Mezquital valley Phaeozems by decreasing the hydraulic conductivity and increasing the soil's sorption capacity.

Surface runoff and transport of sulfonamide antibiotics and tracers on manured grassland.

PubMed

Burkhardt, Michael; Stamm, Christian; Waul, Christopher; Singer, Heinz; Müller, Stephan

2005-01-01

Despite their common use in animal production the environmental fate of the veterinary sulfonamide antibiotics after excretion is only poorly understood. We performed irrigation experiments to investigate the transport of these substances with surface runoff on grassland. Liquid manure from pigs treated with sulfadimidine was spiked with sulfadiazine, sulfathiazole, the herbicide atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine), and the conservative tracer bromide and spread onto eight plots. Four plots received the same amounts of the spiked substances in aqueous solution (controls). Apart from the application matrix we varied the time between application and irrigation. Manure increased the runoff volume up to six times compared with the controls. It seemed that manure enhanced the runoff by sealing the soil surface. On manured plots the relative antibiotic concentrations in runoff were higher than on the controls, reaching an average of 0.3% (sulfadiazine), 0.8% (sulfathiazole), and 1.4% (sulfadimidine) of the input concentrations after a 1-d contact time. The corresponding values on the controls were 0.16% for sulfadiazine and 0.08% for sulfathiazole. After 3 d, the maximum values on the manured plots were even higher, whereas they had fallen below the limit of quantification on the controls. As a consequence, the sulfonamide losses were 10 to 40 times larger on the manured plots. The relative mobility of the sulfonamides on the control plots followed the trend expected from their chromatographic separation but the opposite was found on the manured plots. Hence it is important to consider explicitly the physical and chemical effects of manure when assessing the environmental fate of sulfonamides.

BROMIDE-OXIDANT INTERACTIONS AND THM (TRIHALOMETHANE) FORMATION: A LITERATURE REVIEW

EPA Science Inventory

The review focuses on the interactions, not only of bromide and chlorine, but also of bromide and two common oxidation alternatives to chlorine--chlorine dioxide and monochloramine. The data evaluations include discussions of reaction products, potentials for trihalomethane (THM)...

78 FR 32646 - Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-31

... being treated/produced. List how many mills have been fumigated with methyl bromide over the last three... facilities. Dried Cured Pork Applicants must list how many facilities have been fumigated with methyl bromide...

76 FR 34700 - Protection of Stratospheric Ozone: Request for Methyl Bromide Critical Use Exemption Applications...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-14

... pest control methods. List how many mills have been fumigated with methyl bromide over the last three... been fumigated with methyl bromide over the last three years, rate, volume and target CT of methyl...

Development of radon-222 as a natural tracer for monitoring the remediation of NAPL contamination in the subsurface. 1998 annual progress report

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

Semprini, L.; Istok, J.

'The objective of this research is to develop a unique method of using naturally occurring radon-222 as a tracer for locating and quantitatively describing the presence of subsurface NAPL contamination. The research will evaluate using radon as an inexpensive, yet highly accurate, means of detecting NAPL contamination and assessing the effectiveness of NAPL remediation. Laboratory, field, and modeling studies are being performed to evaluate this technique, and to develop methods for its successful implementation in practice. This report summarizes work that has been accomplished after 1-year of a 3-year project. The research to date has included radon tracer tests inmore » physical aquifer models (PAMs) and field studies at Site 300 of the Lawrence Livermore National Laboratory, CA, and Site 100D at Hanford DOE Facility, WA. The PAM tests have evaluated the ability of radon as a tracer to monitor the remediation of TCE NAPL contamination using surfactant treatment, and oxidation with permanganate. The surfactant tests were performed in collaboration with Dr. Jack Istok and Dr. Jennifer Field and their EMSP project ``In-situ, Field-Scale Evaluation of Surfactant Enhanced DNAPL Recovery Using a Single-Well-Push-Pull Test.'''' This collaboration enabled the EMSP radon project to make rapid progress. The PAM surfactant tests were performed in a radial flow geometry to simulate the push-pull-method that is being developed for surfactant field tests. The radon tests were easily incorporated into these experiments, since they simply rely on measuring the natural radon present in the subsurface fluids. Two types of radon tests were performed: (1) static tests where radon was permitted to build-up to steady-state concentrations in the pore fluids and the groundwater concentrations were monitored, and (2) dynamic tests were the radon response during push-pull surfactant tests was measured. Both methods were found to be useful in determining how NAPL remediation was progressing.'« less

Atmospheric Tracer Depletion Testing for Unfiltered Air In-Leakage Determination at the Wolf Creek Nuclear Power Plant

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

Sullivan, T. M.; Wilke, R. J.; Roberts, T.

Atmospheric Tracer Depletion tests were conducted at the Wolf Creek Nuclear Power Plant to quantify the unfiltered in-leakage (UI) into the Control Room (CR), Control Building (CB), and Equipment Rooms (ER) at the Wolf Creek Nuclear Power Plant. Wolf Creek has two independent charcoal filter Emergency Ventilation Systems (EVS) that can be used to purify air entering the control building and control room. The Bravo System contains a filtration system in Room 1501 in the Auxiliary Building for the Control Room and another filtration system (FGK02B) on Elevation 2016 for the Control Building. The Alpha system contains a filtration systemmore » in Room 1512 in the Auxiliary Building for the Control Room and another filtration system (FGK02A) on Elevation 2016 for the Control Building. The Atmospheric Tracer Depletion (ATD) test is a technique to measure in-leakage using the concentration of perfluorocarbon compounds that have a constant atmospheric background. These levels are present in the Control Room and Control Building under normal operating conditions. When air is supplied by either of the EVS, most of the PFTS are removed by the charcoal filters. If the concentrations of the PFTs measured in protected areas are the same as the levels at the output of the EVS, the in-leakage of outside air into the protected area would be zero. If the concentration is higher in the protected area than at the output of the filter system, there is in-leakage and the in-leakage can be quantified by the difference. Sampling was performed using state-of-the-art Brookhaven Atmospheric Tracer Samplers (BATS) air sampling equipment and analysis performed on Brookhaven National Laboratory (BNL) dedicated PFT analytical systems. In the Alpha test two tracers PMCH and mcPDCH were used to determine in-leakage into the control building. The analytical system was tuned to maximize sensitivity after initial analysis of the Alpha test. The increased sensitivity permitted accurate quantification of five isomers of the PFT PDCH (mtPDCH, pcPDCH, otPDCH, mcPDCH, and ptPDCH). These isomers were quantified in the low concentration samples in the Alpha test and in all samples in the Bravo test. The best estimates of UI (Rui) for the four zones are provided in Table ES-1. For the CB, this estimate averages the four tracers at the four elevations. For the CR, this estimate uses the four sampling units located in the Control Room.« less

Atmospheric Tracer Depletion Testing for Unfiltered Air In-Leakage Determination at the Wolf Creek Nuclear Power Plant

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

Sullivan, T. M.; Wilke, R. J.; Roberts, T.

Atmospheric Tracer Depletion tests were conducted at the Wolf Creek Nuclear Power Plant to quantify the unfiltered in-leakage (UI) into the Control Room (CR), Control Building (CB), and Equipment Rooms (ER) at the Wolf Creek Nuclear Power Plant. Wolf Creek has two independent charcoal filter Emergency Ventilation Systems (EVS) that can be used to purify air entering the control building and control room. The Bravo System contains a filtration system in Room 1501 in the Auxiliary Building for the Control Room and another filtration system (FGK02B) on Elevation 2016 for the Control Building. The Alpha system contains a filtration systemmore » in Room 1512 in the Auxiliary Building for the Control Room and another filtration system (FGK02A) on Elevation 2016 for the Control Building.The Atmospheric Tracer Depletion (ATD) test is a technique to measure in-leakage using the concentration of perfluorocarbon compounds that have a constant atmospheric background. These levels are present in the Control Room and Control Building under normal operating conditions. When air is supplied by either of the EVS, most of the PFTS are removed by the charcoal filters. If the concentrations of the PFTs measured in protected areas are the same as the levels at the output of the EVS, the in-leakage of outside air into the protected area would be zero. If the concentration is higher in the protected area than at the output of the filter system, there is in-leakage and the in-leakage can be quantified by the difference.Sampling was performed using state-of-the-art Brookhaven Atmospheric Tracer Samplers (BATS) air sampling equipment and analysis performed on Brookhaven National Laboratory (BNL) dedicated PFT analytical systems. In the Alpha test two tracers PMCH and mcPDCH were used to determine in-leakage into the control building. The analytical system was tuned to maximize sensitivity after initial analysis of the Alpha test. The increased sensitivity permitted accurate quantification of five isomers of the PFT PDCH (mtPDCH, pcPDCH, otPDCH, mcPDCH, and ptPDCH). These isomers were quantified in the low concentration samples in the Alpha test and in all samples in the Bravo test.The best estimates of UI (Rui) for the four zones are provided in Table ES-1. For the CB, this estimate averages the four tracers at the four elevations. For the CR, this estimate uses the four sampling units located in the Control Room.« less

THE NEW YORK CITY URBAN DISPERSION PROGRAM MARCH 2005 FIELD STUDY: TRACER METHODS AND RESULTS.

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

WATSON, T.B.; HEISER, J.; KALB, P.

The Urban Dispersion Program March 2005 Field Study tracer releases, sampling, and analytical methods are described in detail. There were two days where tracer releases and sampling were conducted. A total of 16.0 g of six tracers were released during the first test day or Intensive Observation Period (IOP) 1 and 15.7 g during IOP 2. Three types of sampling instruments were used in this study. Sequential air samplers, or SAS, collected six-minute samples, while Brookhaven atmospheric tracer samplers (BATS) and personal air samplers (PAS) collected thirty-minute samples. There were a total of 1300 samples resulting from the two IOPs.more » Confidence limits in the sampling and analysis method were 20% as determined from 100 duplicate samples. The sample recovery rate was 84%. The integrally averaged 6-minute samples were compared to the 30-minute samples. The agreement was found to be good in most cases. The validity of using a background tracer to calculate sample volumes was examined and also found to have a confidence level of 20%. Methods for improving sampling and analysis are discussed. The data described in this report are available as Excel files. An additional Excel file of quality assured tracer data for use in model validation efforts is also available. The file consists of extensively quality assured BATS tracer data with background concentrations subtracted.« less

Advanced hydrogen electrode for hydrogen-bromide battery

NASA Technical Reports Server (NTRS)

Kosek, Jack A.; Laconti, Anthony B.

1987-01-01

Binary platinum alloys are being developed as hydrogen electrocatalysts for use in a hydrogen bromide battery system. These alloys were varied in terms of alloy component mole ratio and heat treatment temperature. Electrocatalyst evaluation, performed in the absence and presence of bromide ion, includes floating half cell polarization studies, electrochemical surface area measurements, X ray diffraction analysis, scanning electron microscopy analysis and corrosion measurements. Results obtained to date indicate a platinum rich alloy has the best tolerance to bromide ion poisoning.

Petrothermal heat extraction using a single deviated well (Horstberg, revisited)

NASA Astrophysics Data System (ADS)

Ghergut, Julia; Behrens, Horst; Vogt, Esther; Bartetzko, Anne; Sauter, Martin

2013-04-01

The single-well tracer test conducted (Behrens et al. 2006) in conjunction with waterfrac experiments at Horstberg is re-examined with a view at four basic issues: why single-well? why fracturing? why tracers? does this only work at Horstberg, or can it work almost anywhere else in the Northern-German sedimentary basin? Heat and tracer transport within a composite reservoir (impermeable matrix + waterfrac + permeable layer), as accessed by a single deviated well, turn out to fit into a surprisingly simple description, as the plain (arithmetic) sum of certain petrothermal-type and aquifer-type contributions, whose weighting relative to each other can vary from site to site, depending upon stratigraphy and upon wellbore geometry. At Horstberg, within the particular formations tested ('Volpriehausen', 'Detfurth', 'Solling', comprising mainly claystone and sandstone layers), thermal lifetime results to be petrothermally-dominated, while tracer residence times prove to be 'aquifer'-dominated. Despite this disparity, the reservoir's thermal lifetime can reliably be predicted from tracer test results. What cannot be determined from waterfrac flow-path tracing is the very waterfrac's aperture. Aperture uncertainty, however, does not impede upon thermal lifetime predictability. The results of the semi-analytical approach are confirmed by numerical simulations using a FE model that includes more details of hydrogeological heterogeneity for the Horstberg site. They are complemented by a parameter sensitivity analysis. ACKNOWLEDGEMENT: This study is funded by MWK Niedersachsen (Lower-Saxony's Science and Culture Ministry) and by Baker Hughes (Celle) within task unit G6 of the Collaborative Research Project 'gebo' ('Geothermal Energy and High-Performance Drilling').

Quantification of tracer plume transport parameters in 2D saturated porous media by cross-borehole ERT imaging

NASA Astrophysics Data System (ADS)

Lekmine, G.; Auradou, H.; Pessel, M.; Rayner, J. L.

2017-04-01

Cross-borehole ERT imaging was tested to quantify the average velocity and transport parameters of tracer plumes in saturated porous media. Seven tracer tests were performed at different flow rates and monitored by either a vertical or horizontal dipole-dipole ERT sequence. These sequences were tested to reconstruct the shape and temporally follow the spread of the tracer plumes through a background regularization procedure. Data sets were inverted with the same inversion parameters and 2D model sections of resistivity ratios were converted to tracer concentrations. Both array types provided an accurate estimation of the average pore velocity vz. The total mass Mtot recovered was always overestimated by the horizontal dipole-dipole and underestimated by the vertical dipole-dipole. The vertical dipole-dipole was however reliable to quantify the longitudinal dispersivity λz, while the horizontal dipole-dipole returned better estimation for the transverse component λx. λ and Mtot were mainly influenced by the 2D distribution of the cumulated electrical sensitivity and the Shadow Effects induced by the third dimension. The size reduction of the edge of the plume was also related to the inability of the inversion process to reconstruct sharp resistivity contrasts at the interface. Smoothing was counterbalanced by a non-realistic rise of the ERT concentrations around the centre of mass returning overpredicted total masses. A sensitivity analysis on the cementation factor m and the porosity ϕ demonstrated that a change in one of these parameters by 8% involved non negligible variations by 30 and 40% of the dispersion coefficients and mass recovery.

Metal loading in Soda Butte Creek upstream of Yellowstone National Park, Montana and Wyoming; a retrospective analysis of previous research; and quantification of metal loading, August 1999

USGS Publications Warehouse

Boughton, G.K.

2001-01-01

Acid drainage from historic mining activities has affected the water quality and aquatic biota of Soda Butte Creek upstream of Yellowstone National Park. Numerous investigations focusing on metals contamination have been conducted in the Soda Butte Creek basin, but interpretations of how metals contamination is currently impacting Soda Butte Creek differ greatly. A retrospective analysis of previous research on metal loading in Soda Butte Creek was completed to provide summaries of studies pertinent to metal loading in Soda Butte Creek and to identify data gaps warranting further investigation. Identification and quantification of the sources of metal loading to Soda Butte Creek was recognized as a significant data gap. The McLaren Mine tailings impoundment and mill site has long been identified as a source of metals but its contribution relative to the total metal load entering Yellowstone National Park was unknown. A tracer-injection and synoptic-sampling study was designed to determine metal loads upstream of Yellowstone National Park.A tracer-injection and synoptic-sampling study was conducted on an 8,511-meter reach of Soda Butte Creek from upstream of the McLaren Mine tailings impoundment and mill site downstream to the Yellowstone National Park boundary in August 1999. Synoptic-sampling sites were selected to divide the creek into discrete segments. A lithium bromide tracer was injected continuously into Soda Butte Creek for 24.5 hours. Downstream dilution of the tracer and current-meter measurements were used to calculate the stream discharge. Stream discharge values, combined with constituent concentrations obtained by synoptic sampling, were used to quantify constituent loading in each segment of Soda Butte Creek.Loads were calculated for dissolved calcium, silica, and sulfate, as well as for dissolved and total-recoverable iron, aluminum, and manganese. Loads were not calculated for cadmium, copper, lead, and zinc because these elements were infrequently detected in mainstem synoptic samples. All of these elements were detected at high concentrations in the seeps draining the McLaren Mine tailings impoundment. The lack of detection of these elements in the downstream mainstem synoptic samples is probably because of sorption (coprecipitation and adsorption) to metal colloids in the stream.Most of the metal load that entered Soda Butte Creek was contributed by the inflows draining the McLaren Mine tailings impoundment (between 505 meters and 760 meters downstream from the tracer-injection site), Republic Creek (1,859 meters), and Unnamed Tributary (8,267 meters). Results indicate that treatment or removal of the McLaren Mine tailings impoundment would greatly reduce metal loading in Soda Butte Creek upstream of Yellowstone National Park. However, removing only that single source may not reduce metal loads to acceptable levels. The sources of metal loading in Republic Creek and Unnamed Tributary merit further investigation.

RE-ENTRAINMENT AND DISPERSION OF EXHAUSTS FROM INDOOR RADON REDUCTION SYSTEMS: ANALYSIS OF TRACER GAS DATA

EPA Science Inventory

Tracer gas studies were conducted around four model houses in a wind tunnel, and around one house in the field, to quantify re-entrainment and dispersion of exhaust gases released from residential indoor radon reduction systems. Re-entrainment tests in the field suggest that acti...

Field Test of Enhanced Remedial Amendment Delivery Using a Shear-Thinning Fluid

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

Truex, Michael J.; Vermeul, Vincent R.; Adamson, David

2015-03-01

Heterogeneity of hydraulic properties in aquifers may lead to contaminants residing in lower-permeability zones where it is difficult to deliver remediation amendments using conventional injection processes. The focus of this effort is to examine use of a shear-thinning fluid (STF) to improve the uniformity of remedial amendment distribution within a heterogeneous aquifer. Previous studies have demonstrated the significant potential of STFs for improving remedial amendment delivery in heterogeneous aquifers, but quantitative evaluation of these improvements from field applications are lacking. A field-scale test was conducted that compares data from successive injection of a tracer in water followed by injection ofmore » a tracer in a STF to evaluate the impact of the STF on tracer distribution uniformity in the presence of permeability contrasts within the targeted injection zone. Data from tracer breakthrough at multiple depth-discrete monitoring intervals and electrical resistivity tomography showed that inclusion of STF in the injection solution slowed movement in high-permeability pathways, improved delivery of amendment to low-permeability materials, and resulted in better uniformity in injected fluid distribution within the targeted treatment zone.« less

Pyridostigmine in the treatment of orthostatic intolerance.

PubMed

Gales, Barry J; Gales, Mark A

2007-02-01

To review the efficacy of pyridostigmine bromide for the treatment of orthostatic intolerance. MEDLINE and International Pharmaceutical Abstracts were searched (1966-December 2006) using the terms pyridostigmine, acetylcholinesterase inhibitor, orthostatic intolerance, orthostatic hypotension, neurogenic orthostatic hypotension, postural tachycardia syndrome, tachycardia, and orthostatic tachycardia. Pertinent English-language human clinical trials, case reports, and background material were evaluated for safety and efficacy data. The references of reviewed articles were reviewed and used to identify additional sources. Pyridostigmine bromide has been associated with improved baroreceptor sensitivity and presents a novel approach to treatment of orthostatic intolerance. Four single-dose trials and a follow-up survey encompassing a total of 106 patients were identified. One open-label and one placebo-controlled single-dose trial in patients with neurogenic orthostatic hypotension (NOH) found statistically significant improvement in standing diastolic blood pressures (DBP). Absolute improvements in standing DBP were 3.7 and 6.4 mm Hg in the open-label and controlled trials, respectively. Long-term data consist of a single survey of patients receiving open-label pyridostigmine bromide. Twenty-nine percent of patients who initiated maintenance pyridostigmine bromide discontinued therapy. Concomitant NOH medications were taken by 75% of patients, and 85% of patients reported receiving benefit from pyridostigmine bromide. When evaluated for postural tachycardia syndrome, pyridostigmine bromide significantly reduced standing heart rate (10%). Pyridostigmine bromide significantly reduced symptom scores when compared with baseline but not placebo. The majority of patients included in these trials did not have supine hypertension. Single doses of pyridostigmine bromide produced modest but statistically significant improvements in hemodynamic measurements. At this time, long-term data are insufficient to support recommending the routine use of pyridostigmine bromide for treatment of orthostatic intolerance.

Effects of nitrate on the stability of uranium in a bioreduced region of the subsurface.

PubMed

Wu, Wei-Min; Carley, Jack; Green, Stefan J; Luo, Jian; Kelly, Shelly D; Van Nostrand, Joy; Lowe, Kenneth; Mehlhorn, Tonia; Carroll, Sue; Boonchayanant, Benjaporn; Löfller, Frank E; Watson, David; Kemner, Kenneth M; Zhou, Jizhong; Kitanidis, Peter K; Kostka, Joel E; Jardine, Philip M; Criddle, Craig S

2010-07-01

The effects of nitrate on the stability of reduced, immobilized uranium were evaluated in field experiments at a U.S. Department of Energy site in Oak Ridge, TN. Nitrate (2.0 mM) was injected into a reduced region of the subsurface containing high levels of previously immobilized U(IV). The nitrate was reduced to nitrite, ammonium, and nitrogen gas; sulfide levels decreased; and Fe(II) levels increased then deceased. Uranium remobilization occurred concomitant with nitrite formation, suggesting nitrate-dependent, iron-accelerated oxidation of U(IV). Bromide tracer results indicated changes in subsurface flowpaths likely due to gas formation and/or precipitate. Desorption-adsorption of uranium by the iron-rich sediment impacted uranium mobilization and sequestration. After rereduction of the subsurface through ethanol additions, background groundwater containing high levels of nitrate was allowed to enter the reduced test zone. Aqueous uranium concentrations increased then decreased. Clone library analyses of sediment samples revealed the presence of denitrifying bacteria that can oxidize elemental sulfur, H(2)S, Fe(II), and U(IV) (e.g., Thiobacillus spp.), and a decrease in relative abundance of bacteria that can reduce Fe(III) and sulfate. XANES analyses of sediment samples confirmed changes in uranium oxidation state. Addition of ethanol restored reduced conditions and triggered a short-term increase in Fe(II) and aqueous uranium, likely due to reductive dissolution of Fe(III) oxides and release of sorbed U(VI). After two months of intermittent ethanol addition, sulfide levels increased, and aqueous uranium concentrations gradually decreased to <0.1 microM.

METHYL BROMIDE ALTERNATIVES FOR VINEYARD REPLANT

USDA-ARS?s Scientific Manuscript database

Soil fumigation with methyl bromide is needed by grape growers in central California to control soilborne pests. However, use of methyl bromide is banned and soil fumigation with other chemicals subjects to strict regulations to protect human health and air quality. The objective was to determine,...

Methyl bromide: effective pest management tool and environmental threat.

PubMed

Thomas, W B

1996-12-01

Methyl bromide is used extensively on a global basis as a pesticide against nematodes, weeds, insects, fungi, bacteria, and rodents. As a soil fumigant, it is used in significant quantities in the production of strawberry and tomato, as well as other agriculture commodities. Grain, fresh fruit, forestry products, and other materials are fumigated with methyl bromide to control pest infestations during transport and storage. Structures also are treated with this chemical to control wood-destroying insects and rodents. However, methyl bromide has been identified as a significant ozone-depleting substance, resulting in regulatory actions being taken by the U.S. Environmental Protection Agency and the United Nations Environment Program (Montreal Protocol). The science linking methyl bromide to ozone depletion is strong and was reinforced by the 1994 UNEP Montreal Protocol Science Assessment on Ozone Depletion, which states, "Methyl bromide continues to be viewed as a significant ozone-depleting compound." Identifying efficacious and viable alternatives in the near term is critical.

Formation of NDMA and halogenated DBPs by chloramination of tertiary amines: the influence of bromide ion.

PubMed

Le Roux, Julien; Gallard, Hervé; Croué, Jean-Philippe

2012-02-07

The formation of NDMA and other DBPs (including THMs, HANs, and HKs) has been investigated by chloramination of several tertiary amines in the absence and presence of bromide ion. NDMA formation from the most reactive tertiary amines (e.g., dimethylaminomethylfurfuryl alcohol or DMP30) was enhanced in the presence of bromide due to the formation of brominated oxidant species such as bromochloramine (NHBrCl) and the hypothetical UDMH-Br as an intermediate. The formation of NDMA by chloramination of less reactive model compounds was inhibited in the presence of bromide. This can be explained by competitive reactions leading to the production of brominated DBPs (i.e., THMs). In the presence of bromide, the formation of brominated THMs during chloramination can be attributed to the presence of small amounts of HOBr produced by the decomposition of chloramines and bromamines. The results are of particular interest to understand NDMA formation mechanisms, especially during chloramination of wastewaters impacted by anthropogenic tertiary amines and containing bromide ion.

Testing mixing models of old and young groundwater in a tropical lowland rain forest with environmental tracers

NASA Astrophysics Data System (ADS)

Solomon, D. Kip; Genereux, David P.; Plummer, L. Niel; Busenberg, Eurybiades

2010-04-01

We tested three models of mixing between old interbasin groundwater flow (IGF) and young, locally derived groundwater in a lowland rain forest in Costa Rica using a large suite of environmental tracers. We focus on the young fraction of water using the transient tracers CFC-11, CFC-12, CFC-113, SF6, 3H, and bomb 14C. We measured 3He, but 3H/3He dating is generally problematic due to the presence of mantle 3He. Because of their unique concentration histories in the atmosphere, combinations of transient tracers are sensitive not only to subsurface travel times but also to mixing between waters having different travel times. Samples fall into three distinct categories: (1) young waters that plot along a piston flow line, (2) old samples that have near-zero concentrations of the transient tracers, and (3) mixtures of 1 and 2. We have modeled the concentrations of the transient tracers using (1) a binary mixing model (BMM) of old and young water with the young fraction transported via piston flow, (2) an exponential mixing model (EMM) with a distribution of groundwater travel times characterized by a mean value, and (3) an exponential mixing model for the young fraction followed by binary mixing with an old fraction (EMM/BMM). In spite of the mathematical differences in the mixing models, they all lead to a similar conceptual model of young (0 to 10 year) groundwater that is locally derived mixing with old (>1000 years) groundwater that is recharged beyond the surface water boundary of the system.

Assessment of key transport parameters in a karst system under different dynamic conditions based on tracer experiments: the Jeita karst system, Lebanon

NASA Astrophysics Data System (ADS)

Doummar, Joanna; Margane, Armin; Geyer, Tobias; Sauter, Martin

2018-03-01

Artificial tracer experiments were conducted in the mature karst system of Jeita (Lebanon) under various flow conditions using surface and subsurface tracer injection points, to determine the variation of transport parameters (attenuation of peak concentration, velocity, transit times, dispersivity, and proportion of immobile and mobile regions) along fast and slow flow pathways. Tracer breakthrough curves (TBCs) observed at the karst spring were interpreted using a two-region nonequilibrium approach (2RNEM) to account for the skewness in the TBCs' long tailings. The conduit test results revealed a discharge threshold in the system dynamics, beyond which the transport parameters vary significantly. The polynomial relationship between transport velocity and discharge can be related to the variation of the conduit's cross-sectional area. Longitudinal dispersivity in the conduit system is not a constant value (α = 7-10 m) and decreases linearly with increasing flow rate because of dilution effects. Additionally, the proportion of immobile regions (arising from conduit irregularities) increases with decreasing water level in the conduit system. From tracer tests with injection at the surface, longitudinal dispersivity values are found to be large (8-27 m). The tailing observed in some TBCs is generated in the unsaturated zone before the tracer actually arrives at the major subsurface conduit draining the system. This work allows the estimation and prediction of the key transport parameters in karst aquifers. It shows that these parameters vary with time and flow dynamics, and they reflect the geometry of the flow pathway and the origin of infiltrating (potentially contaminated) recharge.

Hybrid dynamic radioactive particle tracking (RPT) calibration technique for multiphase flow systems

NASA Astrophysics Data System (ADS)

Khane, Vaibhav; Al-Dahhan, Muthanna H.

2017-04-01

The radioactive particle tracking (RPT) technique has been utilized to measure three-dimensional hydrodynamic parameters for multiphase flow systems. An analytical solution to the inverse problem of the RPT technique, i.e. finding the instantaneous tracer positions based upon instantaneous counts received in the detectors, is not possible. Therefore, a calibration to obtain a counts-distance map is needed. There are major shortcomings in the conventional RPT calibration method due to which it has limited applicability in practical applications. In this work, the design and development of a novel dynamic RPT calibration technique are carried out to overcome the shortcomings of the conventional RPT calibration method. The dynamic RPT calibration technique has been implemented around a test reactor with 1foot in diameter and 1 foot in height using Cobalt-60 as an isotopes tracer particle. Two sets of experiments have been carried out to test the capability of novel dynamic RPT calibration. In the first set of experiments, a manual calibration apparatus has been used to hold a tracer particle at known static locations. In the second set of experiments, the tracer particle was moved vertically downwards along a straight line path in a controlled manner. The obtained reconstruction results about the tracer particle position were compared with the actual known position and the reconstruction errors were estimated. The obtained results revealed that the dynamic RPT calibration technique is capable of identifying tracer particle positions with a reconstruction error between 1 to 5.9 mm for the conditions studied which could be improved depending on various factors outlined here.

An Advanced Reservoir Simulator for Tracer Transport in Multicomponent Multiphase Compositional Flow and Applications to the Cranfield CO2 Sequestration Site

NASA Astrophysics Data System (ADS)

Moortgat, J.

2015-12-01

Reservoir simulators are widely used to constrain uncertainty in the petrophysical properties of subsurface formations by matching the history of injection and production data. However, such measurements may be insufficient to uniquely characterize a reservoir's properties. Monitoring of natural (isotopic) and introduced tracers is a developing technology to further interrogate the subsurface for applications such as enhanced oil recovery from conventional and unconventional resources, and CO2 sequestration. Oak Ridge National Laboratory has been piloting this tracer technology during and following CO2 injection at the Cranfield, Mississippi, CO2 sequestration test site. Two campaigns of multiple perfluorocarbon tracers were injected together with CO2 and monitored at two wells at 68 m and 112 m from the injection site. The tracer data suggest that multiple CO2 flow paths developed towards the monitoring wells, indicative of either channeling through high permeability pathways or of fingering. The results demonstrate that tracers provide an important complement to transient pressure data. Numerical modeling is essential to further explain and interpret the observations. To aid the development of tracer technology, we enhanced a compositional multiphase reservoir simulator to account for tracer transport. Our research simulator uses higher-order finite element (FE) methods that can capture the small-scale onset of fingering on the coarse grids required for field-scale modeling, and allows for unstructured grids and anisotropic heterogeneous permeability fields. Mass transfer between fluid phases and phase behavior are modeled with rigorous equation-of-state based phase-split calculations. We present our tracer simulator and preliminary results related to the Cranfield experiments. Applications to noble gas tracers in unconventional resources are presented by Darrah et al.

Simultaneous measurement of ventilation using tracer gas techniques and VOC concentrations in homes, garages and vehicles.

PubMed

Batterman, Stuart; Jia, Chunrong; Hatzivasilis, Gina; Godwin, Chris

2006-02-01

Air exchange rates and interzonal flows are critical ventilation parameters that affect thermal comfort, air migration, and contaminant exposure in buildings and other environments. This paper presents the development of an updated approach to measure these parameters using perfluorocarbon tracer (PFT) gases, the constant injection rate method, and adsorbent-based sampling of PFT concentrations. The design of miniature PFT sources using hexafluorotoluene and octafluorobenzene tracers, and the development and validation of an analytical GC/MS method for these tracers are described. We show that simultaneous deployment of sources and passive samplers, which is logistically advantageous, will not cause significant errors over multiday measurement periods in building, or over shorter periods in rapidly ventilated spaces like vehicle cabins. Measurement of the tracers over periods of hours to a week may be accomplished using active or passive samplers, and low method detection limits (<0.025 microg m(-3)) and high precisions (<10%) are easily achieved. The method obtains the effective air exchange rate (AER), which is relevant to characterizing long-term exposures, especially when ventilation rates are time-varying. In addition to measuring the PFT tracers, concentrations of other volatile organic compounds (VOCs) are simultaneously determined. Pilot tests in three environments (residence, garage, and vehicle cabin) demonstrate the utility of the method. The 4 day effective AER in the house was 0.20 h(-1), the 4 day AER in the attached garage was 0.80 h(-1), and 16% of the ventilation in the house migrated from the garage. The 5 h AER in a vehicle traveling at 100 km h(-1) under a low-to-medium vent condition was 92 h(-1), and this represents the highest speed test found in the literature. The method is attractive in that it simultaneously determines AERs, interzonal flows, and VOC concentrations over long and representative test periods. These measurements are practical, cost-effective, and helpful in indoor air quality and other investigations.

Selective oxidation of bromide in wastewater brines from hydraulic fracturing.

PubMed

Sun, Mei; Lowry, Gregory V; Gregory, Kelvin B

2013-07-01

Brines generated from oil and natural gas production, including flowback water and produced water from hydraulic fracturing of shale gas, may contain elevated concentrations of bromide (~1 g/L). Bromide is a broad concern due to the potential for forming brominated disinfection byproducts (DBPs) during drinking water treatment. Conventional treatment processes for bromide removal is costly and not specific. Selective bromide removal is technically challenging due to the presence of other ions in the brine, especially chloride as high as 30-200 g/L. This study evaluates the ability of solid graphite electrodes to selectively oxidize bromide to bromine in flowback water and produced water from a shale gas operation in Southwestern PA. The bromine can then be outgassed from the solution and recovered, as a process well understood in the bromine industry. This study revealed that bromide may be selectively and rapidly removed from oil and gas brines (~10 h(-1) m(-2) for produced water and ~60 h(-1) m(-2) for flowback water). The electrolysis occurs with a current efficiency between 60 and 90%, and the estimated energy cost is ~6 kJ/g Br. These data are similar to those for the chlor-alkali process that is commonly used for chlorine gas and sodium hydroxide production. The results demonstrate that bromide may be selectively removed from oil and gas brines to create an opportunity for environmental protection and resource recovery. Copyright © 2013 Elsevier Ltd. All rights reserved.

The orbital PDF: general inference of the gravitational potential from steady-state tracers

NASA Astrophysics Data System (ADS)

Han, Jiaxin; Wang, Wenting; Cole, Shaun; Frenk, Carlos S.

2016-02-01

We develop two general methods to infer the gravitational potential of a system using steady-state tracers, I.e. tracers with a time-independent phase-space distribution. Combined with the phase-space continuity equation, the time independence implies a universal orbital probability density function (oPDF) dP(λ|orbit) ∝ dt, where λ is the coordinate of the particle along the orbit. The oPDF is equivalent to Jeans theorem, and is the key physical ingredient behind most dynamical modelling of steady-state tracers. In the case of a spherical potential, we develop a likelihood estimator that fits analytical potentials to the system and a non-parametric method (`phase-mark') that reconstructs the potential profile, both assuming only the oPDF. The methods involve no extra assumptions about the tracer distribution function and can be applied to tracers with any arbitrary distribution of orbits, with possible extension to non-spherical potentials. The methods are tested on Monte Carlo samples of steady-state tracers in dark matter haloes to show that they are unbiased as well as efficient. A fully documented C/PYTHON code implementing our method is freely available at a GitHub repository linked from http://icc.dur.ac.uk/data/#oPDF.

Nano-iron Tracer Test for Characterizing Preferential Flow Path in Fractured Rock

NASA Astrophysics Data System (ADS)

Chia, Y.; Chuang, P. Y.

2015-12-01

Deterministic description of the discrete features interpreted from site characterization is desirable for developing a discrete fracture network conceptual model. It is often difficult, however, to delineate preferential flow path through a network of discrete fractures in the field. A preliminary cross-borehole nano-iron tracer test was conducted to characterize the preferential flow path in fractured shale bedrock at a hydrogeological research station. Prior to the test, heat-pulse flowmeter measurements were performed to detect permeable fracture zones at both the injection well and the observation well. While a few fracture zones are found permeable, most are not really permeable. Chemical reduction method was used to synthesize nano zero-valent iron particles with a diameter of 50~150 nm. The conductivity of nano-iron solution is about 3100 μs/cm. The recorded fluid conductivity shows the arrival of nano-iron solution in the observation well 11.5 minutes after it was released from the injection well. The magnetism of zero-valent iron enables it to be absorbed on magnet array designed to locate the depth of incoming tracer. We found nearly all of absorbed iron on the magnet array in the observation well were distributed near the most permeable fracture zone. The test results revealed a preferential flow path through a permeable fracture zone between the injection well and the observation well. The estimated hydraulic conductivity of the connected fracture is 2.2 × 10-3 m/s. This preliminary study indicated that nano-iron tracer test has the potential to characterize preferential flow path in fractured rock.

A&M. TAN607. Special equipment services room. Workers are filling viewing ...

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

A&M. TAN-607. Special equipment services room. Workers are filling viewing window with zinc bromide through tube penetrating concrete shield wall. Date: August 16, 1954. INEEL negative no. 11689 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

Application of the UTCHEM simulator to DNAPL site characterization

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

Butler, G.W.

1995-12-31

Numerical simulation using the University of Texas Chemical Flood Simulator (UTCHEM) was used to evaluate two dense, nonaqueous phase liquid (DNAPL) characterization methods. The methods involved the use of surfactants and partitioning tracers to characterize a suspected trichloroethene (TCE) DNAPL zone beneath a US Air Force Plant in Texas. The simulations were performed using a cross-sectional model of the alluvial aquifer in an area that is believed to contain residual TCE at the base of the aquifer. Characterization simulations compared standard groundwater sampling, an interwell NAPL Solubilization Test, and an interwell NAPL Partitioning Tracer Test. The UTCHEM simulations illustrated howmore » surfactants and partitioning tracers can be used to give definite evidence of the presence and volume of DNAPL in a situation where conventional groundwater sampling can only indicate the existence of the dissolved contaminant plume.« less

Re-evaluation of the sorption behaviour of Bromide and Sulfamethazine under field conditions using leaching data and modelling methods

NASA Astrophysics Data System (ADS)

Gassmann, Matthias; Olsson, Oliver; Höper, Heinrich; Hamscher, Gerd; Kümmerer, Klaus

2016-04-01

The simulation of reactive transport in the aquatic environment is hampered by the ambiguity of environmental fate process conceptualizations for a specific substance in the literature. Concepts are usually identified by experimental studies and inverse modelling under controlled lab conditions in order to reduce environmental uncertainties such as uncertain boundary conditions and input data. However, since environmental conditions affect substance behaviour, a re-evaluation might be necessary under environmental conditions which might, in turn, be affected by uncertainties. Using a combination of experimental data and simulations of the leaching behaviour of the veterinary antibiotic Sulfamethazine (SMZ; synonym: sulfadimidine) and the hydrological tracer Bromide (Br) in a field lysimeter, we re-evaluated the sorption concepts of both substances under uncertain field conditions. Sampling data of a field lysimeter experiment in which both substances were applied twice a year with manure and sampled at the bottom of two lysimeters during three subsequent years was used for model set-up and evaluation. The total amount of leached SMZ and Br were 22 μg and 129 mg, respectively. A reactive transport model was parameterized to the conditions of the two lysimeters filled with monoliths (depth 2 m, area 1 m²) of a sandy soil showing a low pH value under which Bromide is sorptive. We used different sorption concepts such as constant and organic-carbon dependent sorption coefficients and instantaneous and kinetic sorption equilibrium. Combining the sorption concepts resulted in four scenarios per substance with different equations for sorption equilibrium and sorption kinetics. The GLUE (Generalized Likelihood Uncertainty Estimation) method was applied to each scenario using parameter ranges found in experimental and modelling studies. The parameter spaces for each scenario were sampled using a Latin Hypercube method which was refined around local model efficiency maxima. Results of the cumulative SMZ leaching simulations suggest a best conceptualization combination of instantaneous sorption to organic carbon which is consistent with the literature. The best Nash-Sutcliffe efficiency (Neff) was 0.96 and the 5th and 95th percentile of the uncertainty estimation were 18 and 27 μg. In contrast, both scenarios of kinetic Br sorption had similar results (Neff =0.99, uncertainty bounds 110-176 mg and 112-176 mg) but were clearly better than instantaneous sorption scenarios. Therefore, only the concept of sorption kinetics could be identified for Br modelling whereas both tested sorption equilibrium coefficient concepts performed equally well. The reasons for this specific case of equifinality may be uncertainties of model input data under field conditions or an insensitivity of the sorption equilibrium method due to relatively low adsorption of Br. Our results show that it may be possible to identify or at least falsify specific sorption concepts under uncertain field conditions using a long-term leaching experiment and modelling methods. Cases of environmental fate concept equifinality arouse the possibility of future model structure uncertainty analysis using an ensemble of models with different environmental fate concepts.

Tidal volume single breath washout of two tracer gases--a practical and promising lung function test.

PubMed

Singer, Florian; Stern, Georgette; Thamrin, Cindy; Fuchs, Oliver; Riedel, Thomas; Gustafsson, Per; Frey, Urs; Latzin, Philipp

2011-03-10

Small airway disease frequently occurs in chronic lung diseases and may cause ventilation inhomogeneity (VI), which can be assessed by washout tests of inert tracer gas. Using two tracer gases with unequal molar mass (MM) and diffusivity increases specificity for VI in different lung zones. Currently washout tests are underutilised due to the time and effort required for measurements. The aim of this study was to develop and validate a simple technique for a new tidal single breath washout test (SBW) of sulfur hexafluoride (SF(6)) and helium (He) using an ultrasonic flowmeter (USFM). The tracer gas mixture contained 5% SF(6) and 26.3% He, had similar total MM as air, and was applied for a single tidal breath in 13 healthy adults. The USFM measured MM, which was then plotted against expired volume. USFM and mass spectrometer signals were compared in six subjects performing three SBW. Repeatability and reproducibility of SBW, i.e., area under the MM curve (AUC), were determined in seven subjects performing three SBW 24 hours apart. USFM reliably measured MM during all SBW tests (n = 60). MM from USFM reflected SF(6) and He washout patterns measured by mass spectrometer. USFM signals were highly associated with mass spectrometer signals, e.g., for MM, linear regression r-squared was 0.98. Intra-subject coefficient of variation of AUC was 6.8%, and coefficient of repeatability was 11.8%. The USFM accurately measured relative changes in SF(6) and He washout. SBW tests were repeatable and reproducible in healthy adults. We have developed a fast, reliable, and straightforward USFM based SBW method, which provides valid information on SF(6) and He washout patterns during tidal breathing.

Tidal Volume Single Breath Washout of Two Tracer Gases - A Practical and Promising Lung Function Test

PubMed Central

Singer, Florian; Stern, Georgette; Thamrin, Cindy; Fuchs, Oliver; Riedel, Thomas; Gustafsson, Per; Frey, Urs; Latzin, Philipp

2011-01-01

Background Small airway disease frequently occurs in chronic lung diseases and may cause ventilation inhomogeneity (VI), which can be assessed by washout tests of inert tracer gas. Using two tracer gases with unequal molar mass (MM) and diffusivity increases specificity for VI in different lung zones. Currently washout tests are underutilised due to the time and effort required for measurements. The aim of this study was to develop and validate a simple technique for a new tidal single breath washout test (SBW) of sulfur hexafluoride (SF6) and helium (He) using an ultrasonic flowmeter (USFM). Methods The tracer gas mixture contained 5% SF6 and 26.3% He, had similar total MM as air, and was applied for a single tidal breath in 13 healthy adults. The USFM measured MM, which was then plotted against expired volume. USFM and mass spectrometer signals were compared in six subjects performing three SBW. Repeatability and reproducibility of SBW, i.e., area under the MM curve (AUC), were determined in seven subjects performing three SBW 24 hours apart. Results USFM reliably measured MM during all SBW tests (n = 60). MM from USFM reflected SF6 and He washout patterns measured by mass spectrometer. USFM signals were highly associated with mass spectrometer signals, e.g., for MM, linear regression r-squared was 0.98. Intra-subject coefficient of variation of AUC was 6.8%, and coefficient of repeatability was 11.8%. Conclusion The USFM accurately measured relative changes in SF6 and He washout. SBW tests were repeatable and reproducible in healthy adults. We have developed a fast, reliable, and straightforward USFM based SBW method, which provides valid information on SF6 and He washout patterns during tidal breathing. PMID:21423739

Evaluation of sprayable fixatives on a sandy soil for potential use in a dirty bomb response.

PubMed

Fritz, Brad G; Whitaker, John D

2008-06-01

After the events of 11 September 2001, the possibility of a dirty bomb being detonated within the United States seems more realistic. Development of tools for use in response to a dirty bomb detonation has become a topic of both discussion and research. While it has been reported that the health risk to the public from such an event would likely be small, it is thought that the psychological impact could be considerable. One response option that has been considered is adapting sprayable solutions for the purpose of fixing contamination in place, thereby limiting the spread of contamination by wind and rain and facilitating subsequent cleanup. This work evaluated two commercially available particle fixatives (IsoFIX-HT and IsoFIX-RC) for their effectiveness in preventing dispersal of simulated contamination. Nonradioactive cesium chloride and cobalt oxide particles were selected as the simulated contamination and applied to the surface of three outdoor test plots. Two test plots were treated with fixatives; the third plot provided a control. Samples were collected over 95 days to observe changes in tracer concentration on the surface of the test plots. One fixative (IsoFIX-RC) effectively held the tracer in place with no net loss of tracer, while the other fixative (IsoFIX-HT) had no impact on the loss of tracer relative to the control. Under the conditions tested, IsoFIX-RC appears capable of fixing surface contamination in place for at least several months.

Tumor Endothelial Marker Imaging in Melanomas Using Dual-Tracer Fluorescence Molecular Imaging

PubMed Central

Tichauer, Kenneth M.; Deharvengt, Sophie J.; Samkoe, Kimberley S.; Gunn, Jason R.; Bosenberg, Marcus W.; Turk, Mary-Jo; Hasan, Tayyaba; Stan, Radu V.; Pogue, Brian W.

2014-01-01

Purpose Cancer-specific endothelial markers available for intravascular binding are promising targets for new molecular therapies. In this study, a molecular imaging approach of quantifying endothelial marker concentrations (EMCI) is developed and tested in highly light-absorbing melanomas. The approach involves injection of targeted imaging tracer in conjunction with an untargeted tracer, which is used to account for nonspecific uptake and tissue optical property effects on measured targeted tracer concentrations. Procedures Theoretical simulations and a mouse melanoma model experiment were used to test out the EMCI approach. The tracers used in the melanoma experiments were fluorescently labeled anti-Plvap/PV1 antibody (plasmalemma vesicle associated protein Plvap/PV1 is a transmembrane protein marker exposed on the luminal surface of endothelial cells in tumor vasculature) and a fluorescent isotype control antibody, the uptakes of which were measured on a planar fluorescence imaging system. Results The EMCI model was found to be robust to experimental noise under reversible and irreversible binding conditions and was capable of predicting expected overexpression of PV1 in melanomas compared to healthy skin despite a 5-time higher measured fluorescence in healthy skin compared to melanoma: attributable to substantial light attenuation from melanin in the tumors. Conclusions This study demonstrates the potential of EMCI to quantify endothelial marker concentrations in vivo, an accomplishment that is currently unavailable through any other methods, either in vivo or ex vivo. PMID:24217944

Time‐lapse imaging of saline‐tracer transport in fractured rock using difference‐attenuation radar tomography

USGS Publications Warehouse

Day-Lewis, Frederick D.; Lane, John W.; Harris, Jerry M.; Gorelick, Steven M.

2003-01-01

Accurate characterization of fractured‐rock aquifer heterogeneity remains one of the most challenging and important problems in groundwater hydrology. We demonstrate a promising strategy to identify preferential flow paths in fractured rock using a combination of geophysical monitoring and conventional hydrogeologic tests. Cross‐well difference‐attenuation ground‐penetrating radar was used to monitor saline‐tracer migration in an experiment at the U.S. Geological Survey Fractured Rock Hydrology Research Site in Grafton County, New Hampshire. Radar data sets were collected every 10 min in three adjoining planes for 5 hours during each of 12 tracer tests. An innovative inversion method accounts for data acquisition times and temporal changes in attenuation during data collection. The inverse algorithm minimizes a combination of two functions. The first is the sum of weighted squared data residuals. Second is a measure of solution complexity based on an a priori space‐time covariance function, subject to constraints that limit radar‐attenuation changes to regions of the tomograms traversed by high difference‐attenuation ray paths. The time series of tomograms indicate relative tracer concentrations and tracer arrival times in the image planes; from these we infer the presence and location of a preferential flow path within a previously identified zone of transmissive fractures. These results provide new insights into solute channeling and the nature of aquifer heterogeneity at the site.

Stability and Microtox Response of Butenyltin Compounds

DTIC Science & Technology

compound was as stable as tributyltin bromide. Stability in seawater, in the absence of ultraviolet (UV) light, was less for both tri-1-butenyltin...bromides necessary to produce a toxic responses were three to six times greater than for tributyltin bromide. Keywords: Marine fouling; Environmental impact statement; Antifouling coatings; Organotin; Reprints.

76 FR 14320 - Importation of Figs and Pomegranates From Chile Under a Systems Approach

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-16

... pomegranates from Chile using mitigation measures other than fumigation with methyl bromide. DATES: We will... with methyl bromide. The Animal and Plant Health Inspection Service (APHIS) also received a request... mitigation measures other than fumigation with methyl bromide. Implementation of this rule will require...