Bibliografie tematiche / Chemical tracers

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Letteratura scientifica selezionata sul tema "Chemical tracers"

Autore: Grafiati
Pubblicato: 4 giugno 2021
Ultima modifica: 13 febbraio 2022

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Articoli di riviste sul tema "Chemical tracers"

1

Cao, Viet, Mario Schaffer, Reza Taherdangkoo e Tobias Licha. "Solute Reactive Tracers for Hydrogeological Applications: A Short Review and Future Prospects". Water 12, n. 3 (28 febbraio 2020): 653. http://dx.doi.org/10.3390/w12030653.

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Abstract (sommario):
Tracer testing is a mature technology used for characterizing aquatic flow systems. To gain more insights from tracer tests a combination of conservative (non-reactive) tracers together with at least one reactive tracer is commonly applied. The reactive tracers can provide unique information about physical, chemical, and/or biological properties of aquatic systems. Although, previous review papers provide a wide coverage on conservative tracer compounds there is no systematic review on reactive tracers yet, despite their extensive development during the past decades. This review paper summarizes the recent development in compounds and compound classes that are exploitable and/or have been used as reactive tracers, including their systematization based on the underlying process types to be investigated. Reactive tracers can generally be categorized into three groups: (1) partitioning tracers, (2) kinetic tracers, and (3) reactive tracers for partitioning. The work also highlights the potential for future research directions. The recent advances from the development of new tailor-made tracers might overcome existing limitations.
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2

Braconnier, Benjamin, Christophe Preux, Frédéric Douarche e Bernard Bourbiaux. "MUSCL scheme for Single Well Chemical Tracer Test simulation, design and interpretation". Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles 74 (2019): 10. http://dx.doi.org/10.2516/ogst/2018090.

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Our paper presents an improved numerical scheme to simulate Single Well Chemical Tracer Test (SWCTT) method. SWCTT is mainly applied to determine the residual oil saturation of reservoirs. It consists in injecting an aqueous slug of a primary tracer into the reservoir formation and displacing it at a certain distance from the well. This tracer is partly miscible with oil on the one hand, and generates in situ a secondary tracer on the other hand. As a consequence, a shift is observed between the primary and the secondary tracers arrival times when production is resumed. This time shift is used to evaluate the residual oil saturation. In our paper, we propose a numerical scheme based on a fractional time stepping technique to decouple the resolution of the phases mass conservation equations and the chemical tracers mole conservation equations. For the phases resolution, we use an implicit scheme to ensure stability and robustness. For the chemical tracers, we propose an explicit second-order scheme in time and in space via MUSCL technique to improve the tracers time-shift calculation. The proposed numerical method is implemented on a realistic simulation model consisting of a vertical well crossing a reservoir consisting of a stack of homogeneous layers. By reducing the numerical dispersion, the proposed scheme improves the accuracy of predicted concentration profiles, without significantly increasing the computation time. Finally, the advantages of using a second-order scheme for residual oil saturation assessment are discussed on the basis of a radial 1D mesh convergence study.
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3

Jöckel, P., A. Kerkweg, J. Buchholz, H. Tost, R. Sander e A. Pozzer. "Technical Note: Coupling of chemical processes with the Modular Earth Submodel System (MESSy) submodel TRACER". Atmospheric Chemistry and Physics Discussions 7, n. 6 (23 novembre 2007): 17069–97. http://dx.doi.org/10.5194/acpd-7-17069-2007.

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Abstract. The implementation of processes related to chemistry into Earth System Models and their coupling within such systems requires the consistent description of the chemical species involved. We provide a tool (written in Fortran95) to structure and manage information about constituents, herein after referred to as tracers, namely the Modular Earth Submodel System (MESSy) generic (i.e., infrastructure) submodel TRACER. With TRACER it is possible to define a multitude of tracer sets, depending on the spatio-temporal representation (i.e., the grid structure) of the model. The required information about a specific chemical species is split into the static meta-information about the characteristics of the species, and its (generally in time and space variable) abundance in the corresponding representation. TRACER moreover includes two submodels. One is TRACER_FAMILY, an implementation of the tracer family concept. It distinguishes between two types: type-1 families are usually applied to handle strongly related tracers (e.g., fast equilibrating species) for a specific process (e.g., advection). In contrast to this, type-2 families are applied for tagging techniques, in which specific species are artificially decomposed and associated with additional information, in order to conserve the linear relationship between the family and its members. The second submodel is TRACER_PDEF, which corrects and budgets numerical negative overshoots that arise in many process implementations due to the numerical limitations (limited precision, rounding errors). The submodel therefore guarantees the positive definiteness of the tracers and stabilises the integration scheme. As a by-product, it further provides a global tracer mass diagnostic. Last but not least, we present the submodel PTRAC for the definition of prognostic tracers via a Fortran95 namelist. TRACER with its submodels and PTRAC can readily be applied to a variety of models without further requirements. The code and a documentation is included in the electronic supplement.
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4

Jöckel, P., A. Kerkweg, J. Buchholz-Dietsch, H. Tost, R. Sander e A. Pozzer. "Technical Note: Coupling of chemical processes with the Modular Earth Submodel System (MESSy) submodel TRACER". Atmospheric Chemistry and Physics 8, n. 6 (19 marzo 2008): 1677–87. http://dx.doi.org/10.5194/acp-8-1677-2008.

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Abstract (sommario):
Abstract. The implementation of processes related to chemistry into Earth System Models and their coupling within such systems requires the consistent description of the chemical species involved. We provide a tool (written in Fortran95) to structure and manage information about constituents, hereinafter referred to as tracers, namely the Modular Earth Submodel System (MESSy) generic (i.e., infrastructure) submodel TRACER. With TRACER it is possible to define a multitude of tracer sets, depending on the spatio-temporal representation (i.e., the grid structure) of the model. The required information about a specific chemical species is split into the static meta-information about the characteristics of the species, and its (generally in time and space variable) abundance in the corresponding representation. TRACER moreover includes two submodels. One is TRACER_FAMILY, an implementation of the tracer family concept. It distinguishes between two types: type-1 families are usually applied to handle strongly related tracers (e.g., fast equilibrating species) for a specific process (e.g., advection). In contrast to this, type-2 families are applied for tagging techniques. Tagging means the artificial decomposition of one or more species into parts, which are additionally labelled (e.g., by the region of their primary emission) and then processed as the species itself. The type-2 family concept is designed to conserve the linear relationship between the family and its members. The second submodel is TRACER_PDEF, which corrects and budgets numerical negative overshoots that arise in many process implementations due to the numerical limitations (e.g., rounding errors). The submodel therefore guarantees the positive definiteness of the tracers and stabilises the integration scheme. As a by-product, it further provides a global tracer mass diagnostic. Last but not least, we present the submodel PTRAC, which allows the definition of tracers via a Fortran95 namelist, as a complement to the standard tracer definition by application of the TRACER interface routines in the code. TRACER with its submodels and PTRAC can readily be applied to a variety of models without further requirements. The code and a documentation are included in the electronic supplement.
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5

Bayet, E., T. A. Davis, T. A. Bell e S. Viti. "Chemical tracers of high-metallicity environments". Monthly Notices of the Royal Astronomical Society 424, n. 4 (17 luglio 2012): 2646–58. http://dx.doi.org/10.1111/j.1365-2966.2012.21330.x.

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McLeod, M., J. Aislabie, J. Ryburn, A. McGill e M. Taylor. "Microbial and chemical tracer movement through two Southland soils, New Zealand". Soil Research 41, n. 6 (2003): 1163. http://dx.doi.org/10.1071/sr02149.

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Abstract (sommario):
There has been a recent, rapid increase in both land application of dairy shed effluent in Southland, New Zealand, and the microbial load in ground and surface waters. We investigated the fate of faecal coliforms, a host-specific Salmonella bacteriophage, and a non-reactive chemical tracer (Br–), when applied to large intact lysimeter soil cores (500 mm diam. by 500 mm high), to determine the pattern of microbial transport through typical Southland soils. The soils were a poorly drained Fragic Perch-gley Pallic Soil, and a well-drained Typic Firm Brown Soil. A depth of 25 mm of dairy shed effluent containing faecal coliforms and spiked with bacteriophage and Br– was applied to the soil at a rate of 5 mm/h followed by ~1 pore volume of simulated rainfall applied at 5 mm/h. Resulting leachates, collected continuously over ~1 pore volume, were analysed for the microbial and bromide tracers. The microbial tracers moved rapidly through both soils, peaking early in the leachate at ~0.15 pore volume and then tailing off in a pattern indicative of bypass flow. Bromide moved more uniformly through the soils but peaked at ~0.5–0.8 pore volume. The microbial flow pattern observed indicates that the structure in these soils makes them vulnerable to leaching of microbes into local surface and ground water. The large difference between the rate of microbial and chemical tracer transport indicates chemical tracers should only be used with caution to model microbial transport parameters.
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Wu, Xiaokang, Huang Yang, Darryn W. Waugh, Clara Orbe, Simone Tilmes e Jean-Francois Lamarque. "Spatial and temporal variability of interhemispheric transport times". Atmospheric Chemistry and Physics 18, n. 10 (29 maggio 2018): 7439–52. http://dx.doi.org/10.5194/acp-18-7439-2018.

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Abstract. The seasonal and interannual variability of transport times from the northern midlatitude surface into the Southern Hemisphere is examined using simulations of three idealized “age” tracers: an ideal age tracer that yields the mean transit time from northern midlatitudes and two tracers with uniform 50- and 5-day decay. For all tracers the largest seasonal and interannual variability occurs near the surface within the tropics and is generally closely coupled to movement of the Intertropical Convergence Zone (ITCZ). There are, however, notable differences in variability between the different tracers. The largest seasonal and interannual variability in the mean age is generally confined to latitudes spanning the ITCZ, with very weak variability in the southern extratropics. In contrast, for tracers subject to spatially uniform exponential loss the peak variability tends to be south of the ITCZ, and there is a smaller contrast between tropical and extratropical variability. These differences in variability occur because the distribution of transit times from northern midlatitudes is very broad and tracers with more rapid loss are more sensitive to changes in fast transit times than the mean age tracer. These simulations suggest that the seasonal–interannual variability in the southern extratropics of trace gases with predominantly NH midlatitude sources may differ depending on the gases' chemical lifetimes.
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England, Matthew H., e Ernst Maier-Reimer. "Using chemical tracers to assess ocean models". Reviews of Geophysics 39, n. 1 (febbraio 2001): 29–70. http://dx.doi.org/10.1029/1998rg000043.

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9

Wang, Zhen, Masoume Amirkhani, Suemar A. G. Avelar, Daibin Yang e Alan G. Taylor. "Systemic Uptake of Fluorescent Tracers by Soybean (Glycine max (L.) Merr.) Seed and Seedlings". Agriculture 10, n. 6 (26 giugno 2020): 248. http://dx.doi.org/10.3390/agriculture10060248.

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Abstract (sommario):
Systemic seed treatment uptake was investigated in seeds and seedlings using fluorescent tracers to mimic systemic agrochemicals. Soybean was used as the model as soybean has the permeable seed coat characteristic to both charged and noncharged molecules. The purpose of the paper is to (1) screen 32 fluorescent tracers and then use optimal tracers for seed and seedling uptake, (2) investigate varietal differences in seed uptake, (3) examine the distribution of tracer uptake into 14-day-old seedlings, and (4) study the relationship between seed treatment lipophilicity, measured as log P on seed and root uptake. The major chemical families that displayed both seed and seedling uptake were coumarins and xanthenes. Seed uptake of coumarin 120 ranged from 1.1% to 4.8% of the applied seed treatment tracer from 15 yellow-seeded varieties. Rhodamine B, a xanthene compound uptake in seedlings, showed translocation from the applied seed treatment to all seedling tissues. Most of the tracer was measured in the hypocotyl and root, with lesser amounts in the epicotyl and true leaves. Log P is well documented in the literature to model systemic uptake by roots, but log P of the tracers were not related to seed uptake.
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Podglajen, Aurélien, e Felix Ploeger. "Retrieving the age of air spectrum from tracers: principle and method". Atmospheric Chemistry and Physics 19, n. 3 (8 febbraio 2019): 1767–83. http://dx.doi.org/10.5194/acp-19-1767-2019.

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Abstract. Surface-emitted tracers with different dependencies on transit time (e.g., due to chemical loss or time-dependent boundary conditions) carry independent pieces of information on the age of air spectrum (the distribution of transit times from the surface). This paper investigates how and to what extent knowledge of tracer concentrations can be used to retrieve the age spectrum. Since the mixing ratios of the tracers considered depend linearly on the transit time distribution, the question posed can be formulated as a linear inverse problem of small dimension. An inversion methodology is introduced, which does not assume a prescribed shape for the spectrum. The performance of the approach is first evaluated on a constructed set of artificial radioactive tracers derived from idealized spectra. Hereafter, the inversion method is applied to outputs of a chemistry–transport model. The latter experiment highlights the limits of inversions using only parent radioactive tracers: they are unable to retrieve fine-scale structures such as the annual cycle. Improvements can be achieved by including daughter decaying tracers and tracers with an annual cycle at the surface. This study demonstrates the feasibility of retrieving the age spectrum from tracers and has implications for transport diagnosis in models and observations.
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Più fonti

Tesi sul tema "Chemical tracers"

1

Fahrenfeld, Nicole L. "Fecal coliform source identification using chemical tracers". Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1219853511/.

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2

White, Iain Robert. "Novel applications of chemical tracers in the atmosphere and trace pollutant monitoring". Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.509768.

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3

Robinson, Bruce A. "Non-reactive and chemically reactive tracers : theory and applications". Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/17188.

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4

Lazzara, Matthew J. "Effects of plasma proteins on the sieving of macromolecular tracers in the kidney". Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/38443.

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Abstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2003.
Includes bibliographical references (leaves 191-202).
The ultrafiltration of plasma in the mammalian glomerulus is the first step in the processing of blood by the kidney. Proper functioning of this process is critical to the kidney's ability to effectively eliminate waste and retain desirable substances. The glomerular barrier has long been regarded as both a size and charge selective screen for plasma solutes. The origin of this selectivity is found in the unique three-layered structure of the glomerular capillary wall (GCW), consisting of a fenestrated endothelium, the interdigitating foot processes of the glomerular epithelium, and the shared glomerular basement membrane (GBM). The selectivity properties of the GCW have commonly been probed by measuring the sieving coefficients of a variety of tracers, both proteins and exogenous polymers, across the intact glomerular barrier and across isolated components of the GCW. It was found previously that the sieving coefficients of the tracers Ficoll and Ficoll sulfate across isolated GBM were greatly elevated when BSA was present at physiological levels (Bolton et al. 1998). It was suggested that most of this increase was the result of steric interactions between BSA and the tracers which increased tracer partitioning from the bulk into the GBM. Such an effect, if present, would have important implications for the interpretation of macromolecular sieving studies, both in vivo and in vitro. The goals of this thesis research were to model the effect of an abundant protein on the partitioning of a dissimilar tracer molecule, to incorporate that effect into models for glomerular sieving, and to test the partitioning model by measuring the effect of protein concentration on the partitioning of protein and Ficoll in agarose gels. The theoretical effects of solute size on partition coefficients in straight pores or randomly oriented fiber matrices have been investigated previously for very dilute solutions, where solute-solute interactions are negligible, and also for more concentrated solutions consisting of spherical solutes of uniform size. For concentrated solutions it has been found that steric and other repulsive interactions among solutes increase the partition coefficient above the dilute limit. To extend the results for porous or fibrous media to include concentrated mixtures of solutes with different sizes or shapes, we used an excluded volume approach. In this formulation, which describes steric interactions only, partition coefficients were computed by summing all volumes excluded to a solute molecule by virtue of its finite size, the finite size of other solutes, and the presence of fixed obstacles (pore walls or fibers). For a mixture of two spherical solutes, the addition of any second solute at finite concentration increased the partition coefficient of the first solute. That increase was sensitive to the size of the second solute; for a given volume fraction of the second solute, the smaller its radius, the larger the effect. When the total volume fraction of solutes was fixed, an increase in the amount of a second, smaller solute increased the partition coefficient of the first solute, whereas an increase in the amount of a second, larger solute had the opposite effect. Results were obtained also for oblate or prolate spheroidal solutes and for fibrous media with multiple fiber radii. For constant total fiber volume fraction, an increase in the amount of a second, smaller fiber decreased the partition coefficient of a spherical solute, whereas an increase in the amount of a second, larger fiber had the opposite effect. Overall, the theory suggests that the introduction of heterogeneity, whether as mixtures of solute sizes or mixtures of fiber sizes, may cause partition coefficients to differ markedly from those of uniform systems. Using the excluded volume partitioning model, the theory for the sieving of macromolecular tracers was extended to account for the presence of a second, abundant solute. Using that theory, we returned to the experimental data of Bolton et al. (1998) and attempted to model the effect of protein concentration on Ficoll sieving. The osmotic reduction in filtrate velocity caused by an abundant, mostly retained solute will also tend to elevate the tracer sieving coefficient. The osmotic effect alone explained only about one third of the observed increase in the sieving coefficients of Ficoll and Ficoll sulfate, whereas the effect of BSA on tracer partitioning was sufficient to account for the remainder. At physiological concentrations, predictions for tracer sieving in the presence of BSA were found to be insensitive to the assumed shape of the protein (sphere or prolate spheroid). The effect of plasma proteins on tracer partitioning is expected to influence sieving not only in isolated GBM, but also in intact glomerular capillaries in vivo. To test the predicted effects of solute concentration on the equilibrium partitioning of single macromolecules and macromolecule mixtures, measurements of the equilibrium partition coefficients of BSA and four narrow fractions of Ficoll were made in agarose. Solutions of each test macromolecule were equilibrated with a known volume of gel, final liquid concentrations measured, and partition coefficients calculated by applying a material balance. The partition coefficient of each molecule was measured under dilute conditions and under conditions where BSA was present at concentrated levels. All measurements were made for two different gel solid volume fractions (4 and 6%). As expected, the partition coefficients decreased with increasing gel solid volume fraction and with increasing molecular size. Increasing BSA concentration caused an increase in the partitioning of BSA itself and that of all four sizes of Ficoll. This effect was most significant for the largest molecules. A subset of the measurements repeated at a higher ionic strength demonstrated that electrostatic interactions were unimportant. The experimental results were compared with predictions generated from the excluded volume partitioning theory. Agarose was represented as a randomly oriented array of cylindrical fibers, BSA was modeled as a prolate spheroid, and Ficoll was treated as a sphere. Comparisons of the theoretical predictions with the experimental data produced generally good agreement, indicating that steric interactions among solute molecules and between solute molecules and gel fibers could explain the partitioning behavior.
by Matthew Jordan Lazzara.
Ph.D.
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5

Antoniewicz, Maciek Robert. "Comprehensive analysis of metabolic pathways through the combined use of multiple isotopic tracers". Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/37457.

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Abstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2006.
Includes bibliographical references (p. 287-294).
Metabolic Flux Analysis (MFA) has emerged as a tool of great significance for metabolic engineering and the analysis of human metabolic diseases. An important limitation of MFA, as carried out via stable isotope labeling and GC/MS measurements, is the large number of isotopomer equations that need to be solved. This restriction reduces the ability of MFA to fully utilize the power of multiple isotopic tracers in elucidating the physiology of complex biological networks. Here, we present a novel framework for modeling isotopic distributions that significantly reduces the number of system variables without any loss of information. The elementary metabolite units (EMU) framework is based on a highly efficient decomposition algorithm identifies the minimum amount of information needed to simulate isotopic labeling within a reaction network using knowledge of atomic transitions occurring in the network reactions. The developed computational and experimental methodologies were applied to two biological systems of major industrial and medical significance. First, we describe the analysis of metabolic fluxes in E. coli in a fed-batch fermentation for overproduction of 1,3-propanediol (PDO).
(cont.) A dynamic 13C-labeling experiment was performed and nonstationary intracellular fluxes (with confidence intervals) were determined by fitting labeling patterns of 191 cellular amino acids and 8 external fluxes to a detailed network model of E. coli. We established for the first time detailed time profiles of in vivo fluxes. Flux results confirmed the genotype of the organism and provided further insight into the physiology of PDO overproduction in E. coli. Second, we describe the analysis of metabolic fluxes in the pathway of gluconeogenesis in cultured primary hepatocytes, i.e. isolated liver cells. We applied multiple 13C and 2H-labeled tracers and measured isotopomer distributions of glucose fragments. From this overdetermined data set we estimated net and exchange fluxes in the gluconeogenesis pathway. We identified limitations in current methods to estimate gluconeogenesis in vivo, and developed a novel [U-13C,2Hs]glycerol method that allows accurate analysis of gluconeogenesis fluxes independent of the assumption of isotopic steady-state and zonation of tracers. The developed methodologies have wide implications for in vivo studies of glucose metabolism in Type II diabetes, and other metabolic diseases.
by Maciek Robert Antoniewicz.
Ph.D.
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6

Jeansson, Emil. "Chemical tracers in the Nordic Seas : studies on water masses and anthropogenic carbon /". Göteborg : Göteborg University, Department of Chemistry, 2005. http://www.loc.gov/catdir/toc/fy0801/2006421403.html.

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7

Jardine, Angela Beth. "Aqueous Phase Tracers of Chemical Weathering in a Semi-arid Mountain Critical Zone". Thesis, The University of Arizona, 2011. http://hdl.handle.net/10150/144594.

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Chemical weathering reactions are important for the physical, chemical, and biological development of the critical zone. We present findings from aqueous phase chemical analyses of surface and soil pore waters during a 15 month study in a small semi-arid mountain catchment of the Santa Catalina Mountain Critical Zone Observatory. Stream water geochemical solutes are sourced to two distinct locations - fractured bedrock baseflow stores and soil quickflow stores. Solid phase observations of albite, anorthite, and K-feldspar transformation to Ca-montmorillonite and kaolinite are supported by stream water saturation states calculated via a PHREEQC geochemical model. While differences in mineral assemblages, soil depths, and horizonation suggest greater weathering in schist versus granite lithologies and in hillslope divergent versus convergent zones, soil pore water solute ratio analysis does not readily distinguish these differences. However, preliminary investigation of aqueous rare earth elements suggests detectable lithologic and landscape positional differences warranting focus for future research efforts.
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Kilgallon, Rachel. "Investigating the role of chemical and geochemical tracers for CO2 transport and storage". Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/21702.

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Abstract (sommario):
Changes in the atmospheric concentration of greenhouse gases and aerosols alter the energy balance of the climate system. CO2 is the most significant anthropogenic greenhouse gas. The primary source of the increased atmospheric concentration of CO2 since the preindustrial period is from fossil fuel exploitation. As the global need for energy is currently met by combustion of fossil fuels it is imperative that a method of reducing the levels of CO2 being emitted is used. Carbon capture and storage (CCS) is the combination of CO2 capture from large point sources, with the transport of CO2 to a suitable geological storage site where it can safely be contained. Geological CCS technology has the potential to a make a significant contribution to a low carbon technology future. As with any technology, it is imperative to identify techniques that could be used to form part of the monitoring programme. In this thesis, the role of chemical and geochemical tracers are investigated during the transport and storage of CO2. For the first part of this research, a review of the natural gas and CO2 pipeline network in North America and United Kingdom has been compiled from published literature and historical experience. Using this information, research was carried out to determine why odourising has been suggested for CO2 pipeline transport and what benefit it would add. Based on experience from natural gas, it is concluded that high pressure pipelines of CO2 through sparsely populated areas could have odourant added, but will gain little safety benefit. However, adding odourant to CO2 gas phase pipes could aid detection of leaks as well improve public assurance and should be considered in more detail. For the second part of this research, a specially constructed flow cell was designed and built to investigate how noble gases could be used as effective early warning tracers for CO2 migration in storage sites. From this equipment, experimental breakthrough curves for noble gases and SF6 travelling through a sample of Fell sandstone in relation to CO2 over a pressure gradient range of 10,000 – 50,000 Pa were generated. Although noble gases are described as conservative tracers, comparing the breakthrough curves over a range of pressure gradients show that they do not behave as simply as previously assumed. These results were then modelled using a one dimensional advective dispersion transport equation to fit curves to the experimental outputs using two different modelling approaches. A statistical approach can derive the input parameters for an analytical approach, which is needed to understand the dispersivity behaviour of the tracers. A set of values for the dispersivity of noble gases, SF6 and CO2 through porous media is presented in this research. Using a baseline value approach, initial arrival times for krypton and xenon from this research suggest that they could be used as a means of detecting CO2 migration. While helium, neon and argon appear to be unsuitable as early warning tracers for initial detection of CO2, this suggests that they can be used as part of mixture to fingerprint individual CO2 storage sites that may be in close proximity to one another. Results from the experimental and modelling analysis, identify a system where preferential paths exist depending on the change in pressure gradient. The different transport channels progress from a Darcy linear flow regime to a non-linear laminar flow. These results propose an explanation for the patterns observed from tracers in large-scale reservoirs but the output values obtained are limited by scale-dependence and would not be suitable for direct upscaling.
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9

DiPaola, Tracey Stickley. "Biological and Chemical Renovation of Wastewater with a Soil Infiltrator Low-Pressure Distribution System". Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36809.

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Abstract (sommario):
An alternative on-site wastewater treatment and disposal system (OSWTDS) consisting of a soil infiltrator with low pressure distribution was evaluated in a soil that was unsuitable for a conventional OSWTDS under current Commonwealth of Virginia Sewage Handling and Disposal Regulations, due to a shallow seasonally perched water table and low hydraulic conductivity. The absorption field consisted of two subsystems numbered as 1 and 2 with effluent design loading rates of 5.1 and 10.2 Lpd/m2, respectively (actual loading rates of 2.4 and 4.9 Lpd/m2, respectively). Soil matric potentials compared seasonally for each subsystem and indicated that both provided similar hydraulic performance. Background water quality was generally improved by subsurface movement through the absorption fields. A bacterial tracer was found in shallow (45.7 cm) and deep (213.4 cm) sampling wells within 24 h in the two subsystems (but in low numbers) over both summer and winter sampling periods. A viral tracer was detected within 48 h in both shallow and deep wells, but only in subsystem 2 in the winter. In evaluating denitrification potential, the addition of glucose to soil core samples did increase quantitatively, although not significantly, nitrous oxide production in each subsystem, at each depth, during each season. Overall, the performance of both subsystems was very similar. The soil infiltrator functioned very well, as designed for the site and soil limitations. It appears to be a potential alternative OSWTDS for use in problem soils.
Master of Science
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10

Van, Heerden Michael Rudi. "Improving the selectivity of the radio-labelling of ion exchange resin tracers for positron emission particle tracking". Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/24310.

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Positron emission particle tracking (PEPT) is a technique which non-invasively tracks tracer particles labelled with a positron emitting radionuclide in a system of flow. The tracers are tracked through the detection in a PET scanner, of the two nearly collinear 511 keV gamma rays resulting from the annihilations of the positrons. For this technique to be effective, the tracer must be representative of the media in the system under study, and labelled with a sufficient activity of radionuclides. Organic ion exchange resins are suitable tracer materials for PEPT experiments, and are usually labelled with ⁶⁸Ga at the laboratories of PEPT Cape Town. The labelling performance relies on the chemical and physical properties of organic strongly acidic cation exchange resins and the nuclear chemistry of ⁶⁸Ga. The objective of this study is to obtain consistent tracer labelling throughout, or even beyond, the lifespan of the SnO₂ ⁶⁸Ge/⁶⁸Ga generator which degrades over time. The objective 1s achieved by integrating a purification technique into a "standard" radiolabelling method used at iThemba LABS. A small 0.5 ml Amberchrom CG-71 column is loaded with the ⁶⁸Ga generator eluent in 7 M HCl, then rinsed of most the contaminants before eluting the product with distilled water and used in the radiolabelling method. Using a 1-year-old 30 mCi SnO₂ ⁶⁸Ge/⁶⁸Ga generator eluent that has been purified by this method improved the radiolabelling performance by an average of at least 10% when compared to the performance of the un-purified product. Purifying the generator eluent will enable PEPT experiments of longer duration, and in highly shielded systems where tracers with high activity are required, such as granular and fluid flow in engineering applications.
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Libri sul tema "Chemical tracers"

1

Iller, Edward. Dyspersyjny model transportu mediów w radioznacznikowych badaniach pracy wybranych instalacji przemysłowych. Warszawa: Instytut Chemii i Techniki Ja̜drowej, 1999.

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Jeansson, Emil. Chemical tracers in the Nordic seas: Studies on water masses and anthropogenic carbon. [Go̊teborg, Sweden]: Dept. of Chemistry, Göteborg University, 2005.

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3

LeGrand, Pascal. What do paleo-geochemical tracers tell us about the deep ocean circulation during the last ice age? Woods Hole, Mass: Woods Hole Oceanographic Institution, 1994.

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4

Tian ran qi sheng cheng dong li xue ji qi ying yong. Beijing: Di zhi chu ban she, 2011.

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5

LeGrand, Pascal. What do paleo-geochemical tracers tell us about the deep ocean circulation during the last ice age? Woods Hole, Mass: Woods Hole Oceanographic Institution, 1994.

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6

Friedrich, Jana. Polonium-210 und Blei-210 im Südpolarmeer: Natürliche Tracer für biologische und hydrographische Prozesse im Oberflächenwasser des Antarktischen Zirkumpolarstroms und des Weddellmeeres = Polonium-210 and lead-210 in the southern Polar Ocean : naturally occurring tracers of biological and hydrographical processes in the surface waters of the Antarctic Circumpolar current and the Weddell Sea. Bremerhaven: Alfred-Wegener-Institut für Polar- und Meeresforschung, 1997.

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7

Fitznar, Hans Peter. D-Aminosäuren als Tracer für biogeochemische Prozesse im Fluss-Schelf-Ozean-System der Arktis =: D-amino acids as tracers for biogeochemical processes in the river-shelf-ocean-system of the Arctic. Bremerhaven: Alfred-Wegener-Institut für Polar- und Meeresforschung, 1999.

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8

Juracek, Kyle E. Estimation of sediment sources using selected chemical tracers in the Perry Lake and Lake Wabaunsee basins, northeast Kansas. Reston, Va: U.S. Geological Survey, 2007.

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9

Li, Xingwen. Constraining the North Atlantic circulation with transient tracer observations. Cambridge, Mass: Massachusetts Institute of Technology, 2003.

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10

1970-, Hill Vanessa, François Patrick, Primas Francesca e International Astronomical Union, a cura di. From lithium to uranium: Elemental tracers of the early chemical evolution : proceedings of the 228th symposium of the International Astronomical Union held in Paris, France, May 23-27, 2005. Cambridge: Cambridge University Press, 2005.

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Capitoli di libri sul tema "Chemical tracers"

1

Nissen, Poul Erik. "Chemical Abundances as Population Tracers". In Planets, Stars and Stellar Systems, 21–54. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-5612-0_2.

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2

Spanhoff, R., e J. M. Suijlen. "Chemical Tracers — A New and Desirable Technique?" In Estuarine Water Quality Management, 235–38. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-75413-5_35.

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Spanhoff, R., e J. M. Suijlen. "Chemical tracers—A new and desirable technique?" In Estuarine Water Quality Management Monitoring, Modelling and Research, 235–38. Washington, D. C.: American Geophysical Union, 1990. http://dx.doi.org/10.1029/ce036p0235.

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4

Ferro, A. Arellano, L. Parrao e L. Mantegazza. "Supergiant Stars as Tracers of Galactic Chemical Composition". In Stellar Populations, 366. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0125-7_42.

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5

Minster, J. F. "Introduction to Chemical Tracers of the Ocean Circulation". In Oceanic Circulation Models: Combining Data and Dynamics, 345–76. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-1013-3_11.

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6

Jeandel, Catherine, Pieter Van Beek e François Lacan. "Chemical Elements and Isotopes, Tracers of Land-Sea Exchanges". In The Land-Sea Interactions, 39–69. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781119007647.ch2.

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7

Genthon, Christophe, Alexandre Armengaud e Gerhard Krinner. "Climate and Atmospheric Tracers Modelling with GCM, Polar Applications". In Chemical Exchange Between the Atmosphere and Polar Snow, 573–79. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-642-61171-1_26.

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Chollet, J. P., e R. J. Gathmann. "Coherent Structures in Shear Flows, Chemical Tracers and Turbulent Combustion". In Eddy Structure Identification in Free Turbulent Shear Flows, 443–51. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-2098-2_36.

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9

Sturges, William T., Stuart A. Penkett, Jean-Marc Barnola e Jerome A. Chappellaz. "Fluorocarbon Tracers of the Age of Air in Alpine Firn". In Chemical Exchange Between the Atmosphere and Polar Snow, 617–22. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-642-61171-1_32.

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10

Tripathy, Gyana Ranjan, Sunil Kumar Singh e S. Krishnaswami. "Sr and Nd Isotopes as Tracers of Chemical and Physical Erosion". In Advances in Isotope Geochemistry, 521–52. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-10637-8_26.

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Atti di convegni sul tema "Chemical tracers"

1

Gardien, C. J., G. A. Pope e A. D. Hill. "Hydraulic Fracture Diagnosis Using Chemical Tracers". In SPE Annual Technical Conference and Exhibition. Society of Petroleum Engineers, 1996. http://dx.doi.org/10.2118/36675-ms.

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2

Sagen, J., B. Cvetkovic, E. Brendsdal, G. Halvorsen, Y. L. You e T. Bjornstad. "Reservoir Chemical-Thermal Simulation with Tracers". In European Petroleum Conference. Society of Petroleum Engineers, 1996. http://dx.doi.org/10.2118/36921-ms.

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3

Nisbet, William J. R., Kevin Cooper, Philip Wollenberg, Moye Wicks Shell e Szabolcs Balkanyi. "Flowline Deposition Assessment Using Chemical Tracers". In Offshore Technology Conference. Offshore Technology Conference, 2004. http://dx.doi.org/10.4043/16690-ms.

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4

Huseby, O., C. Galdiga, S. Hartvig, G. Zarruk e Ø. Dugstad. "A New Generation of Single Well Chemical Tracer Tests – Tracers and Methodologies". In IOR 2019 – 20th European Symposium on Improved Oil Recovery. European Association of Geoscientists & Engineers, 2019. http://dx.doi.org/10.3997/2214-4609.201900064.

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5

Burkhardt, Andrew, Eric Herbst, Anthony Remijan, Brett McGuire, Romane Le Gal e Christopher Shingledecker. "TIME-SENSITIVE CHEMICAL TRACERS WITHIN SHOCKED ASTROPHYSICAL SOURCES". In 72nd International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2017. http://dx.doi.org/10.15278/isms.2017.tf06.

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Mendis, Champake, Ajith Gunatilaka, Alex Skvortsov e Shanika Karunasekera. "The effect of correlation of chemical tracers on chemical sensor network performance". In 2010 Sixth International Conference on Intelligent Sensors, Sensor Networks and Information Processing (ISSNIP). IEEE, 2010. http://dx.doi.org/10.1109/issnip.2010.5706768.

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Asadi, Mahmoud, e G. Michael Shook. "Application of Chemical Tracers in IOR: A Case History". In North Africa Technical Conference and Exhibition. Society of Petroleum Engineers, 2010. http://dx.doi.org/10.2118/126029-ms.

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8

Filev, Maksim, Vadim Soldatov, Igor Novikov, Jianhua Xu, Kirill Ovchinnikov, Anna Belova e Albina Drobot. "Technology for Determining the Inflow from Near and Far Zones of Fractures During Hydraulic Fracturing by Chemical Tracers in a Production Well". In International Petroleum Technology Conference. IPTC, 2021. http://dx.doi.org/10.2523/iptc-21357-ms.

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Abstract The tracer-based production logging technology can be used to obtain the well production data continuously for several years without the need for risky well interventions and expensive equipment. The paper examines the case of placing polymer-coated tracers dopped proppant in a horizontal well with ten multi-stage frac intervals and using two different tracers dopped proppant codes for two frac ports (the first and the last ones) to identify the performance of the far and near zones of a hydraulic fracture. Upon the completion of the hydraulic fracturing operations, the collected reservoir fluid samples were studied in the laboratory. Chemical tracers contained in the samples were detected by flow cytofluorometry using custom-tailored machine learning-based software. The studies helped identify the productivity of each frac port, calculate the contribution of each port in percentage points, and also evaluate the productivity of the near and far hydraulic fracture zones in the first and the last intervals. The analysis provided data on the exact content of oil and water in the production profile for each frac interval. The results of tracer-based logging in the well in question revealed that the interval productivity is changing in the course of several months of surveillance. The most productive ports and those showing increasing oil flow rate were identified during quantitative analysis. The use of tracer dopped proppant with different codes within one multi-stage frac interval enabled detecting a peak release of chemical tracers from the far fracture zone in the initial periods of well operation followed by a consistent smoothing of the far and near zones’ production profiles. Laboratory analysis of reservoir fluid samples and hydraulic fracturing simulations proved the uniform distribution of proppant across the entire reservoir pay zone and laid the foundation for further research required to better understand the fracture geometry and reduce uncertainties in production optimization operations.
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Myers, Matthew, Cameron White, Charles Heath, Bobby Pejcic e Linda Stalker. "Chemical Tracers for the Offshore Determination of Residual Oil Saturation". In Offshore Technology Conference-Asia. Offshore Technology Conference, 2014. http://dx.doi.org/10.2118/24952-ms.

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Mulkern, Mark E., Mahmoud Asadi e Scott McCallun. "Fracture Extent and Zonal Communication Evaluation Using Chemical Gas Tracers". In SPE Eastern Regional Meeting. Society of Petroleum Engineers, 2010. http://dx.doi.org/10.2118/138877-ms.

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Rapporti di organizzazioni sul tema "Chemical tracers"

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Dale Spall e Robert Villarreal. Selection of Actinide Chemical Analogues for WIPP Tests: Potential Nonradioactive Sorbing and Nonsorbing Tracers for Study of Ion Transport in the Environment. Office of Scientific and Technical Information (OSTI), agosto 1998. http://dx.doi.org/10.2172/1249.

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Williams, A. Trace Chemical Mine Detection Data Collection. Fort Belvoir, VA: Defense Technical Information Center, settembre 2003. http://dx.doi.org/10.21236/ada462212.

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PHELAN, JAMES M. Chemical Sensing for Buried Landmines - Fundamental Processes Influencing Trace Chemical Detection. Office of Scientific and Technical Information (OSTI), maggio 2002. http://dx.doi.org/10.2172/800794.

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4

Daniels, Jeanette. Results of Chemical Analyses for Alcove 8/Niche 3 Tracer Studies. Office of Scientific and Technical Information (OSTI), febbraio 2006. http://dx.doi.org/10.2172/876579.

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5

Janecky, D. R., W. D. Spall, W. Sandoval e S. Williams. Coupled transport and chemical interactions in petroleum reservoirs: Multicomponent tracer demonstration large scale application. Office of Scientific and Technical Information (OSTI), luglio 1996. http://dx.doi.org/10.2172/263991.

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Ji, Yi, Bob McCullouch e Zhi Zhou. Evaluation of Anti-Icing/De-Icing Products Under Controlled Environmental Conditions. Purdue University, 2020. http://dx.doi.org/10.5703/1288284317253.

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Snow and ice removal are important tasks during the winter season and large amounts of anti-icing and de-icing chemicals are used and there is a critical need to review and synthesize information from the literature to compare and contrast anti-icing and de-icing chemicals to understand their environmental impact and support decision making. The effectiveness, costs, and environmental impact of commonly used and alternative anti-icing and de-icing chemicals were reviewed in this study. Application of anti-icing and de-icing chemicals may increase ion concentrations in soils and change nitrogen cycle, soil pH, and trace metal concentrations, affect surface water and groundwater, and increase public health risks. Life cycle assessment was conducted to quantitively evaluate environmental impact of selected anti-icing and de-icing chemicals. A decision support tool on environmental impact was developed to evaluate environmental impact of anti-icing and de-icing chemicals in ten different environmental impact categories. The results showed the environmental life cycle assessment tool developed in this study can be used to compare multiple environment impacts to support decision making for winter operation chemicals.
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Velsko, S. Null Hypothesis Significance Testing for Trace Chemical Weapon Analyte Detection. Office of Scientific and Technical Information (OSTI), dicembre 2012. http://dx.doi.org/10.2172/1059082.

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Adams, M. C., J. N. Moore, W. R. Benoit, C. Doughty e G. S. Bodvarsson. Chemical tracer test at the Dixie Valley geothermal field, Nevada. Geothermal Reservoir Technology research program. Office of Scientific and Technical Information (OSTI), ottobre 1993. http://dx.doi.org/10.2172/10189365.

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Udey, Ruth Norma. Statistical Data Analyses of Trace Chemical, Biochemical, and Physical Analytical Signatures. Office of Scientific and Technical Information (OSTI), gennaio 2013. http://dx.doi.org/10.2172/1080408.

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Huckaby, James L. An Alternative Treatment of Trace Chemical Constituents in Calculated Chemical Source Terms for Hanford Tank Farms Safety Analsyes. Office of Scientific and Technical Information (OSTI), settembre 2006. http://dx.doi.org/10.2172/894876.

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